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Статті в журналах з теми "Current conducting channel"
1
Lau, Y. Y., M. Lampe, R. F. Fernsler, and B. Hui. "Current enhancement in a conducting channel." Physics of Fluids 28, no. 8 (1985): 2323. http://dx.doi.org/10.1063/1.865290.
Повний текст джерела
2
Johari, Zaharah, Nurul Ezaila Alias, and Zuriana Auzar. "Current Conduction in Dual Channel Black Phosphorene Nanoribbon Transistor." ELEKTRIKA- Journal of Electrical Engineering 17, no. 2 (August 29, 2018): 35–38. http://dx.doi.org/10.11113/elektrika.v17n2.107.
Повний текст джерелаАнотація:
Phosphorene continues to fascinate research community due to its excellent physical and electrical properties. In this paper, the feasibility study of using dual conducting channel in black phosphorene nanoribbon transistor is investigated using Atomistic simulation tool. Both electronic and transport properties are evaluated. Through simulation, it is demonstrated that the conduction behavior behave differently where the current exhibit a great deal of increment when using dual channel. The performance was superior compared to single channel and suggests that the number of conducting channel is a significant factor in improving device behavior.
3
Marom, S., D. Dagan, J. Winaver, and Y. Palti. "Brush-border membrane cation conducting channels from rat kidney proximal tubules." American Journal of Physiology-Renal Physiology 257, no. 3 (September 1, 1989): F328—F335. http://dx.doi.org/10.1152/ajprenal.1989.257.3.f328.
Повний текст джерелаАнотація:
This is a description and kinetic characterization of cation channels from rat kidney brush-border membrane vesicles and from apical membranes of proximal tubule cells in culture. Channel activity was demonstrated and characterized in both artificial phospholipid bilayers and in tissue culture. Intermediate conductance, approximately 50 pS, cation-selective channels were observed by both methods. Channels were characterized by a Na permeability (PNa)/K permeability (PK) of 1-5:1. Open-channel current-voltage curves were linear in symmetric 300 mM NaCl. In tissue culture the gating kinetics are described by two open-time constants and two closed-time constants. Channel activity was neither voltage nor Ca2+ dependent and the probability of being in the open state ranged from 0.6 to 0.95. In tissue culture experiments the channel demonstrated nonstationary gating activity. A second, 15-pS cation channel, seen in planar bilayers, demonstrated a higher selectivity for Na+ with a (PNa/PK ratio of greater than 10).
4
Olcese, Riccardo, Daniel Sigg, Ramon Latorre, Francisco Bezanilla, and Enrico Stefani. "A Conducting State with Properties of a Slow Inactivated State in a Shaker K+ Channel Mutant." Journal of General Physiology 117, no. 2 (January 29, 2001): 149–64. http://dx.doi.org/10.1085/jgp.117.2.149.
Повний текст джерелаАнотація:
In Shaker K+ channel, the amino terminus deletion Δ6-46 removes fast inactivation (N-type) unmasking a slow inactivation process. In Shaker Δ6-46 (Sh-IR) background, two additional mutations (T449V-I470C) remove slow inactivation, producing a noninactivating channel. However, despite the fact that Sh-IR-T449V-I470C mutant channels remain conductive, prolonged depolarizations (1 min, 0 mV) produce a shift of the QV curve by about −30 mV, suggesting that the channels still undergo the conformational changes typical of slow inactivation. For depolarizations longer than 50 ms, the tail currents measured during repolarization to −90 mV display a slow component that increases in amplitude as the duration of the depolarizing pulse increases. We found that the slow development of the QV shift had a counterpart in the amplitude of the slow component of the ionic tail current that is not present in Sh-IR. During long depolarizations, the time course of both the increase in the slow component of the tail current and the change in voltage dependence of the charge movement could be well fitted by exponential functions with identical time constant of 459 ms. Single channel recordings revealed that after prolonged depolarizations, the channels remain conductive for long periods after membrane repolarization. Nonstationary autocovariance analysis performed on macroscopic current in the T449V-I470C mutant confirmed that a novel open state appears with increasing prepulse depolarization time. These observations suggest that in the mutant studied, a new open state becomes progressively populated during long depolarizations (>50 ms). An appealing interpretation of these results is that the new open state of the mutant channel corresponds to a slow inactivated state of Sh-IR that became conductive.
5
Ravens, Ursula. "Atrial-selective K+ channel blockers: potential antiarrhythmic drugs in atrial fibrillation?" Canadian Journal of Physiology and Pharmacology 95, no. 11 (November 2017): 1313–18. http://dx.doi.org/10.1139/cjpp-2017-0024.
Повний текст джерелаАнотація:
In the wake of demographic change in Western countries, atrial fibrillation has reached an epidemiological scale, yet current strategies for drug treatment of the arrhythmia lack sufficient efficacy and safety. In search of novel medications, atrial-selective drugs that specifically target atrial over other cardiac functions have been developed. Here, I will address drugs acting on potassium (K+) channels that are either predominantly expressed in atria or possess electrophysiological properties distinct in atria from ventricles. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting IKur, the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting IK,ACh, the Ca2+-activated K+ channels of small conductance (SK) conducting ISK, and the two-pore domain K+ (K2P) channels (tandem of P domains, weak inward-rectifying K+ channels (TWIK-1), TWIK-related acid-sensitive K+ channels (TASK-1 and TASK-3)) that are responsible for voltage-independent background currents ITWIK-1, ITASK-1, and ITASK-3. Direct drug effects on these channels are described and their putative value in treatment of atrial fibrillation is discussed. Although many potential drug targets have emerged in the process of unravelling details of the pathophysiological mechanisms responsible for atrial fibrillation, we do not know whether novel antiarrhythmic drugs will be more successful when modulating many targets or a single specific one. The answer to this riddle can only be solved in a clinical context.
6
Roux, Michel J., Riccardo Olcese, Ligia Toro, Francisco Bezanilla, and Enrico Stefani. "Fast Inactivation in Shaker K+ Channels." Journal of General Physiology 111, no. 5 (May 1, 1998): 625–38. http://dx.doi.org/10.1085/jgp.111.5.625.
Повний текст джерелаАнотація:
Fast inactivating Shaker H4 potassium channels and nonconducting pore mutant Shaker H4 W434F channels have been used to correlate the installation and recovery of the fast inactivation of ionic current with changes in the kinetics of gating current known as “charge immobilization” (Armstrong, C.M., and F. Bezanilla. 1977. J. Gen. Physiol. 70:567–590.). Shaker H4 W434F gating currents are very similar to those of the conducting clone recorded in potassium-free solutions. This mutant channel allows the recording of the total gating charge return, even when returning from potentials that would largely inactivate conducting channels. As the depolarizing potential increased, the OFF gating currents decay phase at −90 mV return potential changed from a single fast component to at least two components, the slower requiring ∼200 ms for a full charge return. The charge immobilization onset and the ionic current decay have an identical time course. The recoveries of gating current (Shaker H4 W434F) and ionic current (Shaker H4) in 2 mM external potassium have at least two components. Both recoveries are similar at −120 and −90 mV. In contrast, at higher potentials (−70 and −50 mV), the gating charge recovers significantly more slowly than the ionic current. A model with a single inactivated state cannot account for all our data, which strongly support the existence of “parallel” inactivated states. In this model, a fraction of the charge can be recovered upon repolarization while the channel pore is occupied by the NH2-terminus region.
7
Quinn, Kerry E., and Barbara E. Ehrlich. "Methanethiosulfonate Derivatives Inhibit Current through the Ryanodine Receptor/Channel." Journal of General Physiology 109, no. 2 (February 1, 1997): 255–64. http://dx.doi.org/10.1085/jgp.109.2.255.
Повний текст джерелаАнотація:
To identify regions of the ryanodine receptor (RyR) important for ion conduction we modified the channel with sulfhydryl-reacting compounds. After addition of methanethiosulfonate (MTS) compounds channel conductance was decreased while other channel properties, including channel regulation by ATP, caffeine, or Ca, were unaffected. The site of action was accessible to the MTS compounds from the cytoplasmic, but not the luminal, side of the channel. In addition, the hydrophilic MTS compounds were only effective when the channel was open, suggesting that the compounds covalently modify the channel from within the water-filled ion conducting pathway. The decrease in channel current amplitude occurred in a step-wise fashion and was irreversible and cumulative over time, eventually leading to the complete block of channel current. However, the time required for each consecutive modification during continuous exposure to the MTS compounds increased, suggesting that successive modification by the MTS compounds is not independent. These results are consistent with the hypothesis that the channel forms a wide vestibule on the cytoplasmic side and contains a much smaller opening on the luminal side. Furthermore, our results indicate that the MTS compounds can serve as functional markers for specific residues of the RyR to be identified in molecular studies.
8
Shcherba, A. A., N. I. Suprunovska, and M. A. Shcherba. "FEATURES OF THE FORMATION OF MULTI-CHANNEL PULSE CURRENTS AND FAST-MIGRATING ELECTRIC SPARKS IN THE LAYER OF CURRENT-CONDUCTING GRANULES OF ELECTRIC-DISCHARGE INSTALLATIONS." Tekhnichna Elektrodynamika 2022, no. 2 (March 19, 2022): 3–11. http://dx.doi.org/10.15407/techned2022.02.003.
Повний текст джерелаАнотація:
The paper reveals the electro-physical features of the formation of multi-channel pulse currents and fast-migrating electric sparks in the layer of current-conductive granules of electric-discharge installations (EDIs) with reservoir capacitors. Such features make it possible to increase many times the productivity of the electric-spark dispersion of metal granules during single discharge current of reservoir capacitors, which flows between the electrodes of EDIs. Theoretical substantiation and experimental confirmation of multi-channel spark discharges in the layer of conductive granules are presented. The influence of the capacitance and charge voltage of reservoir capacitors on the nature of transient processes in the discharge circuit of the EDIs is investigated. The dependence of the effective value of the active load resistance of the EDIs on the value of the pre-charge voltage of its reservoir capacitors and the value of its capacitances has been experimentally determined. It is proved that an increase in the averaged Q-factor of the discharge circuit with an increase in the charge voltage of the capacitor bank of EDI is caused by a decrease in the effective value of the active resistance of the layer of metal granules when spark-generating discharge currents flow through it. References 16, Figures 7.
9
Yu, Xie. "Amplifier Design on 16-Channel High-Frequency Current Drive." Advanced Materials Research 658 (January 2013): 620–25. http://dx.doi.org/10.4028/www.scientific.net/amr.658.620.
Повний текст джерелаАнотація:
According to the situation that the transistor output interface type of PLC output current is too small to meet requirements of high-speed, frequently on or off electromagnetic valve and other great current load drives, a current driver amplifier was developed which connected PLC output interface and load. Its key realization technologies include signal acquisition input, bidirectional conducting, input and output display, and designs of isolation circuit of input and output and output amplification processing circuit. The device uses bidirectional optocoupler and bidirectional LED to gather small DC current signal which does not distinguish between positive and negative polarities and achieve photoelectric isolation, controls drive load work of MOS transistor conducting and achieves current amplification through amplification driver link of emitter output, and has high frequently on-off operation, simple wiring, great drive current, strong versatility, high reliability and other characteristics.
10
Palmer, L. G., L. Antonian, and G. Frindt. "Regulation of apical K and Na channels and Na/K pumps in rat cortical collecting tubule by dietary K." Journal of General Physiology 104, no. 4 (October 1, 1994): 693–710. http://dx.doi.org/10.1085/jgp.104.4.693.
Повний текст джерелаАнотація:
The patch-clamp technique was used to study the properties and the density of conducting K and Na channels in the apical membrane of rat cortical collecting tubule. The predominant K channel observed in cell-attached patches (SK channels) had an outward single-channel conductance (with LiCl in the pipette) of 10 pS. The inward conductance (with KCl in the pipette) was 42 pS. The channel had a high open probability that increased with depolarization. Kinetic analysis indicated the presence of a single open state and two closed states. Increasing K intake by maintaining animals on a high K diet for 12-16 d increased the number of SK channels per patch by threefold (0.7-2.0/patch) over control levels. In addition, conducting Na-selective channels, which were not observed in control animals, were seen at low density (0.5/patch). These channels had properties similar to those observed when the animals were on a low Na diet, except that the mean open probability (0.84) was higher. In other experiments, the whole-cell patch clamp technique was used to measure Na channel activity (as amiloride-sensitive current, INa) and Na pump activity (as ouabain-sensitive current, Ipump). In animals on a high K diet, INa was greater than in controls but much less than in rats on a low Na diet. Ipump was greater after K loading than in controls or Na-depleted animals. These K diet-dependent effects were not accompanied by a significant increase in plasma aldosterone concentrations. To further investigate the relationship between K channel activity and mineralocorticoids, rats were maintained on a low Na diet to increase endogenous aldosterone secretion. Under these conditions, no increase in SK channel density was observed, although there was a large increase in the number of Na channels (to 2.7/patch). Aldosterone was also administered exogenously through osmotic minipumps. As with the low Na diet, there was no change in the density of conducting SK channels, although Na channel activity was induced. These results suggest that SK channels, Na channels and Na/K pumps are regulated during changes in K intake by factors other than aldosterone.
Дисертації з теми "Current conducting channel"
1
Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин". Thesis, Національний науковий центр "Харківський фізико-технічний інститут", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33188.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
2
Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин". Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33183.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
3
Schwetz, Tara A. "Glycosylation Modulates Cardiac Excitability by Altering Voltage-Gated Potassium Currents." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/10.
Повний текст джерелаАнотація:
Neuronal, cardiac, and skeletal muscle electrical signaling is achieved through the highly regulated activity of several types of voltage-gated ion channels to produce an action potential (AP). Voltage-gated potassium (Kv) channels are responsible for repolarization of the AP. Kv channels are uniquely and heavily glycosylated proteins. Previous reports indicate glycosylation modulates gating of some Kv channel isoforms; often, terminal sialic acid residues alter Kv channel gating. Here, we questioned whether alterations in glycosylation impact Kv channel gating, thus altering APs and cardiac excitability. ST3Gal-IV, a sialyltransferase expressed at uniform levels throughout the heart, adds sialic acids to N- and O-glycans through alpha 2-3 linkages. Electrocardiograms (ECGs) suggest that cardiac conduction/rhythm are altered in ST3Gal-IV(-/-) animals, which show an increased incidence of arrhythmic beats. AP waveform parameters and two components of IK, the transient outward, Ito, and the slowly inactivating, IK,slow, were compared in neonatal control versus ST3Gal-IV(-/-) and glycosidase treated atrial and ventricular myocytes. Action potential durations (APDs) measured from ST3Gal-IV(-/-) and glycosidase treated atrial myocytes were lengthened significantly (~25-150%) compared to control; however, ventricular APDs were unaffected by changes in glycosylation. Consistently, atrial Ito and IK,slow activation were shifted to more depolarized potentials (by ~9-17 mV) in ST3Gal-IV(-/-) and glycosidase treated myocytes, while ventricular K+ currents were unaltered. Those channels responsible for producing Ito and IK,slow were examined under conditions of full and reduced glycosylation. Sialylation and N-glycosylation uniquely and differently impact gating of two mammalian Shaker family Kv channel isoforms, Kv1.4 and Kv1.5; Kv1.4 gating was unaffected by changes in channel glycosylation, while N-linked sialic acids, acting through electrostatic mechanisms, fully account for glycan effects on Kv1.5 gating. In addition, sialic acids modulate the gating of three Kv channel isoforms that are not N-glycosylated, Kv2.1, Kv4.2, and Kv4.3, through apparent electrostatic mechanisms. Click chemistry was utilized to confirm that these three isoforms are O-glycosylated and sialylated; thus, O-linked sialylation modulates gating of Kv2.1, Kv4.2, and Kv4.3. This study suggests that regulated or aberrant glycosylation alters the gating of channels producing IK in a chamber-specific manner, thus altering the rate of cardiac repolarization and potentially leading to arrhythmias.
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Billstein, Tova. "On Conducting a Life Cycle Assessment of Network Traffic : A Qualitative Analysis of Current Challenges and Possible Solutions." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297498.
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There is a growing demand for climate reporting of digital solutions and Internet services. However, the impacts of data transmission have historically been the least studied part of the ICT sector and in the few studies that exist, the magnitude of Internet energy intensity varies by a scale as large as 20,000. This indicates that the assessment of network traffic is a complex task, and there is currently no consensus of how to correctly assess it. In an attempt to guide process development within the area, this report sought to identify and address potential challenges with assessing the environmental impact of network traffic during its life cycle. This was completed through a combination of a literature review and semi-structured interviews with experts in the field. Several areas in the form of knowledge gaps, unsolved methodological issues, and areas in need of further development were identified and addressed. Eight key challenges were identified and relate to the areas of system boundaries, data collection methods, energy intensity metrics, transparency and data availability, age of data, allocation procedures, assumptions on inventory level, and impact categories. In an attempt to address said challenges, several suggestions on how to proceed were presented, as well as areas in need of further investigation. It was furthermore found that the sector should strive to agree upon a number of parameters of significance to enable future harmonized studies of the environmental impact of network traffic during its life cycle.Efterfrågan på klimatrapportering av digitala lösningar och Internettjänster ökar allt mer. Samtidigt är effekterna av datatrafik historiskt sett den minst studerade delen av IKT-sektorn, och i de få studier som finns varierar storleken på Internets energiintensitet med en skala på 20 000. Detta indikerar att bedömningen av nätverkstrafik är en komplex uppgift, och i nuläget saknas en konsensus kring hur det bäst kan mätas. I ett försök att vägleda processutveckling inom området försökte rapporten identifiera och analysera potentiella utmaningar som kan uppstå när man bedömer miljöpåverkan av nätverkstrafik under dess livscykel. Med en kombination av en litteraturstudie och halvstrukturerade kvalitativa forskningsintervjuer med experter inom forskningsområdet identifierades och behandlades ett flertal områden i form av kunskapsluckor, olösta metodologiska frågor och områden i behov av vidareutveckling. Resultatet visade att åtta utmaningar av hög relevans existerar inom områdena systemgränser, datainsamlingsmetoder, energiintensitetsmätvärden, transparens och datatillgänglighet, snabb teknikutveckling, allokering, antaganden och miljöpåverkningskategorier. I ett försök att ta itu med de nämnda utmaningarna presenterades ett flertal förslag till lösningar samt områden som behöver undersökas ytterligare i framtiden. Det konstaterades dessutom att sektorn behöver sträva efter att enas om ett antal parametrar av betydelse för att möjliggöra framtida harmoniserade studier av nätverkstrafikens miljöpåverkan under dess livscykel.
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Benada, Tomáš. "Ověřovací série rychlonabíječů pro olověné akumulátory 12V a 6V." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219722.
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This thesis is an engineering design of an intelligent fast-charger for lead-acid accumulators. It contains calculations of each component. The switching power supply is the mainstay of the charger that makes the charger portable, lightweight and small. The Intelligent fast-charger for lead-acid accumulators charges the accumulator by method of constant voltage with current limitation of 0,5A, 5A, 10A, 50A. 50A current is used in winter during starting of a car, when the battery can´t provide sufficient current. There are three LEDs placed on the front side of the charger reflecting status of the device. The device comprises safety protection for the charger, supply network and battery.
Книги з теми "Current conducting channel"
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Panigrahi, Muktikanta, and Arpan Kumar Nayak. Polyaniline based Composite for Gas Sensors. IOR PRESS, 2021. http://dx.doi.org/10.34256/ioriip212.
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In this research work, we have demonstrated the synthesis, spectroscopic characteristics, thermal behaviour and DC conductivity of a few nanostructured composites, substituted conducting polymers (ICPs) and composites of ICPs. The physical properties of aforementioned composites are significantly changed by the doping with HCl, H2SO4, HNO3, H3PO4, or acrylic acid. The charge transport properties of these polymeric materials have been studied in detail because of their potential application in gas sensors. In the current work, varieties of conducting polymer based materials such as PANI-ES/Cloisite 20A nanostructured composite, acrylic acid (AA) doped PANI polymer, N-substituted conducting polyaniline polymer, DL−PLA/PANI-ES composites, poly methyl methacrylate (PMMA) based polyaniline composite, and inorganic acid doped polyaniline are sucessfuly synthesized using aniline/aniline hydrochloride as precursors in acidic medium. Particularly, AA based synthesised PANI polymer was found with higher solubility The spectroscopic, thermal stability, enthalpy of fusion, room temperature DC conductivity and temperature dependent DC conductivity measurements with and without magnetic was carried out with as-synthesized materials. The FTR/ATR−FTIR spectra indicated the presence of different functional groups in the as-prepared composite materials. The UV−Visible absorption spectroscopic analysis showed the presence of polaron band suggesting PANI-ES form. The Room temperature DC conductivity, temperature variation DC conductivity (in presence and absence of magnetic field), and magnetoresistance (MR) of as-prepared conducting polyaniline based were analysed. The highest room temperature DC conductivity value was obtained from H2SO4 doped based composite materials and all prepared conductive composites were followed ohms law. The low temperature DC conductivity was carried out in order to study the semiconducting nature of prepared materials. The Mott type VRH model was found to be well fitted the conductivity data and described the density of states at the Fermi level which is constant in this temperature range. From MR plots, a negative MR was observed, which described the quantum interference effect on hopping conduction. We discuss different gas analytes i.e., NO2, LPG, H2, NH3, CH4, and CO of conducting polymer based materials.
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(Editor), A. J. Camm, Micha Tendera (Editor), and A. John Camm (Editor), eds. Heart Rate Slowing by If Current Inhibition (Advances in Cardiology). S. Karger AG (Switzerland), 2006.
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Archibald, Robert B. The Rhetoric of Higher Education in Crisis. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190251918.003.0001.
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Crisis rhetoric dominates the conversation about higher education. This chapter provides a few fictional stories about the future of colleges and universities facing today’s stresses. It introduces the threats that US higher education faces. These include internal threats, classified as those that come from conducting business as usual in the traditional model of producing a college education; environmental threats, broader economic changes in the world outside of higher education that make the current financial model for colleges and universities more challenging; and technological threats, that is, the expansion of online education. The chapter also discusses reasons apocalyptic predictions of disruption and bankruptcy for large segments of the US higher education system are overblown.
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Takanashi, K., and Y. Sakuraba. Spin polarization in magnets. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0005.
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This chapter explains how the exchange splitting between up- and down-spin bands in ferromagnets unexceptionally generates spin-polarized electronic states at the Fermi energy. The quantity of spin polarization P in ferromagnets is one of the important parameters for application in spintronics, since a ferromagnet having a higher P is able to generate larger various spin-dependent effects such as the magnetoresistance effect, spin transfer torque, spin accumulation, and so on. However, the spin polarizations of general 3d transition metals or alloys generally limit the size of spin-dependent effects. Thus,“‘half-metals” attract much interest as an ideal source of spin current and spin-dependent scattering because they possess perfectly spin-polarized conduction electrons due to the energy band gap in either the up- or down-spin channel at the Fermi level.
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Rothblum, Esther D., ed. The Oxford Handbook of Sexual and Gender Minority Mental Health. Oxford University Press, 2020. http://dx.doi.org/10.1093/oxfordhb/9780190067991.001.0001.
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The Oxford Handbook of Sexual and Gender Minority Mental Health provides an overview of the current research on the mental health of sexual and gender minority (SGM) populations. It is aimed at researchers conducting studies on the mental health of SGM populations, clinicians and researchers interested in psychiatric disorders that affect SGM populations, clinicians using evidence-based practice in the treatment of SGM patients/clients, students in mental health programs (clinical psychology, psychiatry, clinical social work, and psychiatric nursing), and policy makers. The twenty-first century has seen improvements in sampling, use of longitudinal research, mixed methods research, statistical methods for research, and funding opportunities for research with SGM populations. Nevertheless, the purpose of this Handbook is to point out the gaps in the research as well as the advances, in order to motivate future researchers to expand knowledge about SGM mental health. As this volume goes to press, the current socio-political context in many nations includes both progress and backlash, with laws and policies including protections for SGM individuals in some countries, and laws and policies denying protections in others. All of these changes will impact SGM individuals, mental health researchers, and especially young people coming of age in this era.
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Maringe, Felix, ed. Systematic Reviews of Research in Basic Education in South Africa. African Sun Media, 2021. http://dx.doi.org/10.18820/9781991201157.
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Maringe ought to be commended for putting together an invaluable contribution to our understanding of research into a complex education system in South Africa. This volume provides a useful foundation to the current state of education quality in South Africa including the impact of interventions. It also brings to the fore challenges still facing education transformation. The evidence presented which, taken together, lays out a coherent view of how improvements could be made. Albert Chanee Head of Planning, Gauteng Department of Education For too long the weight of educational scholarship produced in South Africa has been limited to that simple and standard form called the literature review. Now, for the first time, education researchers are provided with an African-based text on the concepts and methods of conducting systematic reviews. In this exceptional work of editorship, Felix Maringe brings together some of the leading researchers on South African education to model and demonstrate how to review a significant body of research on a chosen topic which is adjudicated strictly on the basis of the quality and efficacy of the evidence in hand. I have no doubt that this remarkable book will become a standard reference for educational researchers in and beyond the African continent. It will also lift the quality of educational inquiry by equipping a new generation of scholars with the capacity for doing evidence-based research that compels the attention of policymakers, planners and practitioners alike. Prof Jonathan Jansen Stellenbosch University
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Wojewodzic, Tomasz. Procesy dywestycji i dezagraryzacji w rolnictwie o rozdrobnionej strukturze agrarnej. Publishing House of the University of Agriculture in Krakow, 2017. http://dx.doi.org/10.15576/978-83-66602-31-1.
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The turn of the 20th and 21st centuries has been a very dynamic period of change in Poland and around the world; also a period of change in thinking about the economy and agriculture. The present work is a study of the decline, divestments and development of agriculture in the areas of fragmented farming structure. The reflections presented herein, upon the processes of the remodelling of agrarian structures, of divestments in farming, and disagrarisation, are mostly anchored in the achievements of the theory of spatial economy (land management), and the microeconomic theories of choice, including the theory of an agricultural holding (farm) and land rent theories. The work focuses on the economic issues of remodelling the agrarian structure, but due to the nature of the issues discussed herein, specifically in relation to family-owned farms, the social and environmental aspects also needed to be taken into account – in response to the need for a heterogeneous approach, which is increasingly stressed in economic sciences today. The main objective of the research was to diagnose and assess the scale and scope of the mechanisms and processes that inform the decline and growth of agricultural holdings in the areas with fragmented farming structure. The study covered the area comprising four regions (provinces) of south-eastern Poland, which – according to the FADN nomenclature – form the macro region of Małopolska and Pogórze. The study of subject literature has been enriched with an analysis of available statistics; data from the Farm Accountancy Data Network (FADN); information obtained from the Department of Programming and Reporting at the Agency for Restructuring and Modernisation of Agriculture; and author’s own research conducted among farm owners. The information thus obtained made it possible to: • Determine the theoretical premises for the spatial diversity of agriculture, and the role of small farms in the shaping of agrarian structure. • Adapt the concept of “divestment” for the description and analysis of the phenomena occurring in agriculture. • Indicate the role and importance of the processes of divestment and disagrarisation in the restructuring of agriculture. • Assess the natural, social and economic determinants of the process of restructuring agriculture in areas with fragmented farming structure. • Assess selected aspects of economic efficiency of agriculture in areas with fragmented farming structure, with the focus on small and micro farms. • Carry out an ex ante evaluation of the impact of agricultural policy instruments on the process of restructuring of agriculture in the macro region of Małopolska and Pogórze. • Identify the indicators of decline and fall, and barriers to the liquidation of farms. • Assess the relationship between the level of socio-economic development, the structure of farming, and the quality of agricultural production space in a given territorial unit, versus the intensity of the economic and production disagrarisation processes in agricultural holdings. • Propose targeted solutions conducive to the improvement of the farming structure in areas with a high framentation of agriculture. Observation of the processes occurring in agriculture, and the scientific theories created on the basis thereof, have shown that even the smallest farms have a chance to continue in existence, provided that we are able to positively verify their adaptation to the changing conditions in the environment. Carrying out farming activity is a prerequisite for implementing the economic, social and environmental functions associated with family farms. At the same time, based on the analyses performed, we need to assume that the advanced processes of the production and economic disagrarisation of agricultural holdings are to a greater extent determined by the anatomical features of agriculture, and by the natural conditions, than by the level of socio-economic development of the given territorial unit. In the current economic climate, the remodelling of the agrarian structure is only possible with the active participation of the institutions responsible for the creation of economic growth and agricultural policy development. It is extremely important from the point of view of environmental protection, and the viability of rural areas, to support small farms engaged in agricultural activities, and to introduce such instruments that will enable the replacement of an economic collapse with divestments, carried out in a planned manner, and allowing for thus released agricultural resources to find alternative application in units with a higher development potential. The area of theoretical research requiring further exploration includes the issues such as transactional costs of the liquidation of agricultural holdings, and the assessment of the economic effectiveness of conducting divestments.
Частини книг з теми "Current conducting channel"
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Hustad, Kristian Gregorius, Ena Ivanovic, Adrian Llop Recha, and Abinaya Abbi Sakthivel. "Conduction Velocity in Cardiac Tissue as Function of Ion Channel Conductance and Distribution." In Computational Physiology, 41–50. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05164-7_4.
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AbstractIon channels on the membrane of cardiomyocytes regulate the propagation of action potentials from cell to cell and hence are essential for the proper function of the heart. Through computer simulations with the classical monodomain model for cardiac tissue and the more recent extracellular-membrane-intracellular (EMI) model where individual cells are explicitly represented, we investigated how conduction velocity (CV) in cardiac tissue depends on the strength of various ion currents as well as on the spatial distribution of the ion channels. Our simulations show a sharp decrease in CV when reducing the strength of the sodium (Na+) currents, whereas independent reductions in the potassium (K1 and Kr) and L-type calcium currents have negligible effect on the CV. Furthermore, we find that an increase in number density of Na+ channels towards the cell ends increases the CV, whereas a higher number density of K1 channels slightly reduces the CV. These findings contribute to the understanding of ion channels (e.g. Na+ and K+ channels) in the propagation velocity of action potentials in the heart.
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Masetto, S., M. Toselli, and V. Taglietti. "Interactions among Cations in Current Conduction through the Stretch-Activated Channel of the Frog Oocyte." In Sensory Transduction, 17–22. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-5841-1_2.
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Quiring, Johanna, and Franziska Vogt. "Shared Reading for Valuing Diversity and Fostering Language Acquisition." In Migration, Religion and Early Childhood Education, 3–22. Wiesbaden: Springer Fachmedien Wiesbaden, 2020. http://dx.doi.org/10.1007/978-3-658-29809-8_1.
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Abstract It is not unknown that children with a migration background often have fewer chances for a successful school career. Traditionally, a lack of skills in the common language is considered the cause of this inequality. Current discussions however offer multidimensional approaches and emphasise the fact that there are many more factors that account for this development. Nonetheless, good knowledge of the common language does support school success and thus remains an important factor. From an early childhood education perspective, the approach of incorporating language acquisition into it in everyday activities seems to be auspicious. Specific strategies to foster language skill acquisition in children that can be incorporated into everyday activities have been discerned. Among other methods, dialogic book reading is widely accepted as an evidence-based method to support children in enhancing their language skills. As important as the development of a conductive environment for the acquisition of language skills in institutions is the inclusion of the children’s parents into this discussion. One possibility is to encourage parents to invest in the children’s first language.
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Wang, Yi, Y. Zenmei Ohkubo, and Emad Tajkhorshid. "Chapter 12 Gas Conduction of Lipid Bilayers and Membrane Channels." In Current Topics in Membranes, 343–67. Elsevier, 2008. http://dx.doi.org/10.1016/s1063-5823(08)00012-4.
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Feng, Lixiao, Junjie Bai, Chengyuan Chen, Jun Peng, and Guorong Chen. "Implanted Cardiac Pacemaker Mathematical Modeling and Research Based on the Volume Conduction." In Biotechnology, 923–39. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8903-7.ch036.
Повний текст джерелаАнотація:
The research of the communication between implanted Cardiac Pacemaker and external devices is a focus. In this paper, a data communications model based Volume Conduction is creatively presented, in this way the human body conductive ability will been utilized to transmit current, which is more effective and decrease for harm of the human body than the other ways, such as: RF, Optical Transcutaneous, etc. As the frequency increases the KHz level, the effect of background biological noise is considered negligible, the channel is thus modeled as AWGN channel in these frequencies. From Shannon information theory, in two-dimensional modulation, the volume conduction channel capacity formula was derived, further derivation: with extremely low SNR using in the two-level modulation can be very effective use of channel capacity, with high SNR a multi-level modulation is used in order to make full use of the channel capacity. Matlab software is used to the channel simulation, the input and output signal waveforms and eye diagram comparison, the curves of the BER and SNR.
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Elliott, Perry, Pier D. Lambiase, and Dhavendra Kumar. "Inherited arrhythmias and conduction disorders." In Inherited Cardiac Disease, 245–86. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198829126.003.0009.
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Long QT syndrome is primarily a disorder of repolarization with three principal ion channel currents accounting for the condition. Management revolves around optimization of beta blockade and avoidance of triggers with implantable cardiac defibrillators (ICD) recommended in high risk cases. Brugada syndrome is thought to be caused by Na channel mutations although the aetiology is not fully established. Controversy exists regarding optimal risk stratification approaches. Catecholaminergic polymorphic ventricular tachycardia is caused by abnormalities in calcium handling leading to bidirectional ventricular tachycardia/VF and can be managed using medication –principally beta blockers and occasionally sympathectomy with ICD in cardiac arrest survivors with specific caveats. Inherited conduction disorders should always be considered in patients presenting at a younger age with conduction disease paying specific attention to lamin mutations where an ICD will need to be considered.
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Deng, Shuwen, Suixian Yang, and Yong Yao. "Numerical Simulation on Stress Measurement with Eddy Current Thermography." In Studies in Applied Electromagnetics and Mechanics. IOS Press, 2020. http://dx.doi.org/10.3233/saem200018.
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Stress in components will lead to the change of material properties and even failure. Therefore, the assessment for the stress state of components is play an important role in testing industry. As a non-contact and multi-physical field nondestructive testing method, eddy current thermography (ECT) can be applied to detect non-homogeneous electromagnetic characteristics parameter distribution in conductive materials. Internal stress and its distribution in a material will affect the value of electromagnetic characteristic parameters. If induction current applied on conductive material, the Joule’s heat, which generate in the sample will lead to the temperature rise on the surface of the specimen by induction heating process. The temperature distribution on the specimen surface can be recorded by infra camera and stored as IR images or videos. The feature of the temperature distribution and its variation can be used to express the stress state in the specimen. It is concluded that there is an approximate linear relationship between the surface temperature appreciation and the loading force when the excitation source condition remains unchanged.
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Markellou, Penelope, Maria Rigou, and Spiros Sirmakessis. "Closer Look to the Online Consumer Behavior, A." In End-User Computing, 1543–51. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-945-8.ch105.
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Nowadays the Web comprises a significant advance in technology, and the rapidity of its acceptance has been remarkable. It is a powerful tool that has changed the way of conducting business, providing companies and customers with limitless options and opportunities. Online catalogs, 24/7 service availability, a cut down in transaction costs, reduction of customer service time, personalized features, and absence of paper and personalization features are only a few of the advantages. Companies, in an effort to stay competitive in the new global economy, are increasingly expanding their activities to this new communication channel, which features as a factor of major profit potential. As a direct consequence of e-commerce spreading, we are witnessing the emergence of a new consumer type, the online consumer or e-customer that uses the Internet for purchasing products/services (Solomon, 2001). The online consumer is empowered with new, exciting capabilities: he can search globally for products/services, compare available options, find additional information, read the opinion of other people who have bought the product/service, or proceed with the transaction. All these options are available from his office or home and can be used conveniently and fast, while all alternative e-shops are only a few clicks away. As in the case of trivial customers, ensuring e-customer satisfaction is not a simple task. To a certain degree, e-customers (expect to) behave online similarly to how they behave off-line (in traditional real-life shops); but in order to fully understand their behavior, one should explore issues like the reasons why people use the Internet for their purchases, the benefits/drawbacks of online buying, and the identification of clusters of customers who share common attitudes, behavior, and preferences online (Blackwell, Miniard, & Engel, 2000). According to Seybold and Marshak (1998), consumers prefer the Internet because it offers easier and faster shopping. Convenience, timesaving, moneysaving, greater options, and fun are among the top reasons, and this kind of knowledge is of great value for dictating efficient e-marketing strategies and motivating e-commerce use with twofold objective: turn non-shoppers into shoppers and increase shopping of current shoppers. This article presents the overall consumer purchase decision cycle and investigates the issues that affect Web users, from selecting a specific e-shop to the delivery of the product and the overall assessment of the shopping experience. This process has been divided into 13 states referring to customer behavior: outside the e-shop, inside the e-shop, and after sales. Special focus is set on identifying the potential abandonment factors thus leading to practical guidelines for all those whose decisions and objectives affect the online shopping experience (e-shop owners, marketing specialists, Web site designers, and developers).
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Lange, Birthe Kåfjord, and Anne Haugen Gausdal. "Hvordan påvirker tillit og psykologisk trygghet implementering av radikale endringer? En casestudie av digital tjenesteteknologi." In Ledelse av mennesker i det nye arbeidslivet, 257–77. Cappelen Damm Akademisk/NOASP, 2020. http://dx.doi.org/10.23865/noasp.118.ch10.
Повний текст джерелаАнотація:
Studies of radical change pay more attention to early phases of the change processes than to later phases and implementation. Research that can contribute to a deeper understanding of factors that influence the implementation of such changes is therefore called for. The purpose of this chapter is to increase the insight and understanding of how trust and psychological safety impact implementation of radical changes. To meet this purpose, we raise the following research questions: 1) What are the differences and similarities between the concepts of trust and psychological safety? 2) How does trust and psychological safety influence implementation of radical changes in organizations? To answer the first question, we start by conducting a review of the literature on trust and psychological safety in part one. Although both concepts are widely used, the observable level of precision and understanding of the concepts varies. Our review reveals that the concepts are popular and quite closely related, yet there are also important differences worth noticing. To answer the second research question, we apply the insight from part one to discuss a conceptual case, well-known to many organizations in current business life; the implementation of radical new service technology. The discussion reveals that both trust and psychological safety play important, but somewhat different roles in top-down and bottom-up organized radical and adaptive change processes respectively.
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Bala, Shashi, Raj Kumar, Jeetendra Singh, and Sanjeev Kumar Sharma. "Design and Simulation Analysis of NWFET for Digital Application." In Advances in Computer and Electrical Engineering, 123–38. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-6467-7.ch006.
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This chapter presents the design and simulation analysis nanowire-based FET (NWFET) for best possible Ig-Vgs characteristics. A NWFET is a device in which channel is wire-like structure with diameter or lateral dimension in nanometer (10-9 m) range. Performance analysis has been done for various design and process parameters variation to propose optimized parameter for best performance. Although a lot of focus has been put on homogenous Si based NWFETs, there has been a rising interest in III-V NWFETs. This is mainly due to the excellent carrier transport properties are provided by these materials. NWFETs have ability to suppress SCEs and are also good in suppressing OFF-current (IOFF), because of gate all around (GAA) configuration. Secondly, NWFETs have large ON-current (ION) due to quasi one-dimensional (1D) conduction of NWs, and as a result of low carrier scattering, conduction of NWs-based devices is very large.
Тези доповідей конференцій з теми "Current conducting channel"
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Tkachenko, Svetlana, Vera Romanova, Albert Mingaleev, Alexey Ter-Oganesyan, Tatiana Shelkovenko, Sergey Pikuz, Bruce R. Kusse, and David A. Hammer. "Distribution of Dense and Current-Conducting Matter in the Discharge Channel upon Electrical Explosion of Wires in Vacuum." In DENSE Z-PINCHES: Proceedings of the 7th International Conference on Dense Z-Pinches. AIP, 2009. http://dx.doi.org/10.1063/1.3079724.
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Prosperetti, A., He Yuan, and Zhizhong Yin. "Growth and Collapse of a Vapor Bubble Under Impulsive Heating." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24198.
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Abstract In the first part of the paper a micropump based on the periodic growth and collapse of a single vapor bubble in a small channel is described. An explanation of the pumping principle and some preliminary experimental results are presented. In the implementation described the liquid is electrically conductive and is heated by passing a current through it; the same principle would be applicable to the case of non-conducting liquids by using heaters embedded in the channel walls. In the second part of the paper a model for the growth of a bubble onto a heater in a liquid is presented and some numerical results are discussed.
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Parvez, Mohammad Salman, Md Fazlay Rubby, Shanzida Kabir, Meah Imtiaz Zulkarnain, and Nazmul Islam. "Effect of Non-Planar Tungsten V-Electrode Pattern in a 3D Printed Microfluidic System." In ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65659.
Повний текст джерелаАнотація:
Abstract Manipulation, guiding, and focusing of particles is an important phenomenon in the area of biomedical research. In most cases, particles are suspended in a microfluidic environment. These microfluidic environments can be high or low conductive. Most importantly these flows seeded with the micro-particles are manipulated and guided in microfluidic channels. Microfluidic channels have very low dimensions and considering the flow rate the characteristic of the flow in a microfluidic channel is laminar in nature. There are many micromachining methods available for fabricating microfluidic channels such as soft-lithography, wet etching, electroforming, PDMS molding, laser ablation followed by wet etching but in most of these cases, a microfabrication facility is required which is very costly in nature. Now a days 3D printing process is widely used to design microfluidic channels as a cheap process for conducting laboratory experiments. In this work, a 3D printed microfluidic channel fabrication process was presented along with a CAD drawing with microstructural dimension analysis. Previously V-electrode pattern was used in the static fluid system. In this work, a V-elect rode pattern was inserted in the microfluidic system for the first time to analyze the behavior of the flowing fluid of different conductivity under the application of AC current. The flow characteristics were presented and analyzed with the Reynolds number and the flow region of maximum velocity before and after the implementation of the AC electric field. The direction of the flow was also observed in the V-shaped microfluidics environment.
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Khan, Mesbah G., and Amir Fartaj. "Heat Transfer Experiments of Ethylene Glycol-Water Mixture in Multi-Port Serpentine Meso-Channel Heat Exchanger Slab." In ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31131.
Повний текст джерелаАнотація:
In past few years, narrow diameter flow passages (≤3 mm) have attracted huge research attentions due to their several advantageous features over conventional tubes (≥6 mm) especially from the view points of higher heat transfer, lesser weight, and smaller device size. Several classifications of narrow channels, based on sizes, are proposed in the open literature from mini to meso and micro (3 mm to 100 μm). The meso- and micro-channels have not yet entered into the HVAC and automotive heat exchanger industries to the expected potentials to take the above-mentioned advantages. The reasons may be the limited availability of experimental data on pressure drop and heat transfer and the lack of consolidated design correlations as compared to what is established for compact heat exchangers. While a number of studies available on standalone single straight channels, works on multi-channel slab similar to those used as typical thermal heat exchanger core elements are inadequate, especially the research on multichannel serpentine slab are limited in the open literature. The 50% ethylene glycol and water mixture is widely used in heat exchanger industry as a heat transfer fluid. Studies of pressure drop and heat transfer on this commercially important fluid using narrow tube multi-channel slab is scarce and the availability of experimental data is rare in the open literature. Conducting research on various shapes of meso- and micro-channel heat exchanger cores using a variety working fluids are a definite needs as recommended and consistently urged in ongoing research publications in this promising area. Under present long-term project, an automated dynamic single-phase experimental infrastructure has been developed to carryout the fluid flow and heat transfer research in meso- and micro-channel test specimens and prototype microchannel heat exchanger using a variety of working fluids in air-to-liquid crossflow orientation. In the series, experiments have been conducted on 50% ethylene glycol and water solution in a serpentine meso-channel slab having 68 individual channels of 1 mm hydraulic diameter to obtain the heat transfer data and the general pressure drop nature of the test fluid. Current paper presents the heat transfer characteristics of ethylene glycol-water mixture and the Reynolds number effects on pressure drop, heat transfer rate, test specimen NTU and effectiveness, overall thermal resistance, and the Nusselt number.
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Koganemaru, Masaaki, Keisuke Yoshida, Toru Ikeda, Noriyuki Miyazaki, and Hajime Tomokage. "Device Simulation of Mechanical Stress Effects on Electrical Characteristics of nMOSFETs: Impact of Local Stress in nMOSFETs." In ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability. ASMEDC, 2009. http://dx.doi.org/10.1115/interpack2009-89112.
Повний текст джерелаАнотація:
An electrical characteristic of a semiconductor device suffers from a residual stress during various packaging processes. Very few attempts have been made at developing a numerical method for evaluating such problems. Therefore, the objective of this study is to evaluate stress-induced effects by numerical simulation. That is, the effects of stress on the electrical characteristics of n-type Metal Oxide Semiconductor Field Effect Transistors (nMOSFETs) with a 85nm gate length were evaluated by mechanical stress simulation and drift-diffusion device simulation (multi-physics simulation). The device simulation model used includes the electron mobility model that considers the stress-induced effects. This study focused on the impact of the stress distribution in the nMOSFETs. The stress distribution in the nMOSFETs was considered in conducting the multi-physics simulation. As determined by mechanical stress simulation, stress concentrated around the STI, and the effect of such stress concentration reached the channel region of the nMOSFETs. Then, the drift-diffusion device simulation was carried out. The stress distribution in the nMOSFETs obtained by mechanical stress simulation was used as the stress effect in the device simulation model. As determined by device simulation, the drain current decreased under the estimated residual stress. The drain-current shift corresponded quantitatively to the stress at the region of the channel. It was demonstrated that the multi-physics simulation is essential for evaluating the effect of stress on electrical characteristics of a semiconductor device.
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Fujarra, Andre´ L. C., Ju´lio R. Meneghini, Ricardo Franciss, Guilherme R. Franzini, and Ivan Korkischko. "Experimental Investigation of Vortex-Induced Vibration on an Inclined Circular Cylinder." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29092.
Повний текст джерелаАнотація:
This paper presents experimental results of vortex-induced oscillations of an inclined circular cylinder mounted on an elastic base. Models are mounted on an air-bearing elastic base, instrumented with strain gages, accelerometers and a load cell. The experiments were carried out on a water channel facility at NDF-EPUSP. The elastic base has low structural damping and is free to oscillate only in the cross-flow direction. The cylinder axis is inclined in relation to the current. New measurements on the dynamic response oscillations of this inclined cylinder, due to vortex-induced vibrations (VIV), are compared with previous experiments on a vertical cylinder. VIV is investigated by conducting experiments in two ways: first, the cylinder is maintained vertical on the elastic base, with a uniform current normal to its axis, and the response curve is obtained; subsequently, the investigation is carried out changing the angle of inclination from 0 to 45 degrees in relation to vertical. The results for a vertical cylinder are in accordance with other literature measurements for mass ratio m*=2. For the inclined model, using the decomposition of the flow on the direction normal to cylinder axis, the results for amplitude, drag and lift coefficients are consistent with the vertical cylinder.
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Kim, Hee Reyoung. "The Design of a Small Annular Linear Induction EM Pump for the Transportation of Liquid Sodium in the SFR." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16162.
Повний текст джерелаАнотація:
The linear annular induction electromagnetic (EM) pump was designed for the purpose of transporting the electrically conducting liquid sodium that is used as a coolant in the Sodium cooled Fast Reactor (SFR) in the high temperature of 550 °C. The EM pump was designed by using an equivalent circuit method which is commonly employed to the design of the induction machines. The mathematical equations on the developing pressure and efficiency was found out by using Laithewaite’s standard design formula. The main geometrical parameters for the design were a pump core length, a diameter of the pump and an annular gap size. The dominant electromagnetic variables were the input frequency, magnetic pole pitch and number, and coil turns. Especially, it was shown that the developing pressure and efficiency were maximized at the range of the low frequency less than 60 Hz of the commercial frequency. Also, the size of an annular gap was suitably selected considering the hydraulic frictional loss at the narrow annular channel. The P-Q characteristic was theoretically predicted according to the change of the input current, voltage and power. The functional and structural components of the pump consisted of the material compatible with the high temperature and chemical reactivity of the liquid sodium. The designed pump was predicted to have the nominal flowrate of 10 L/min and the developing pressure of 4 bar.
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Gómez, Juan R., and Juan P. Escandón. "Combined Magnetohydrodynamic/Pressure Driven Flow of Multi-Layer Pseudoplastic Fluids Through a Parallel Flat Plates Microchannel." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86676.
Повний текст джерелаАнотація:
With the advance of microfluidic platforms and due to the need to solve different implications that still exist on the transport of electrically conducting fluids, the analysis on strategies in micropumps that involve a simplicity in its structure, absence of mechanical moving parts, flow reversibility and low power requirement is current. Therefore, the present investigation contributes with the analysis of the combined magnetohydrodynamic/pressure driven flow of multilayer immiscible fluids in a microchannel formed by two parallel flat plates. The mathematical model is based in a steady fully developed flow and the pumped fluids follow the power law model to describe the pseudoplastic fluids rheology, while magnetic effects on the flow are given from the Lorentz forces. The velocity profiles and flow rate are obtained in the limit of small Hartmann numbers by solving analytically a closed system of ordinary differential equations, together to the corresponding boundary conditions at the solid-liquid interfaces in the channel walls and at the liquid-liquid interfaces between the fluid layers. The results show that the flow field is controlled by the dimensionless parameters that arise from the mathematical modeling being a parameter that indicates the competition between pressure to the magnetic forces, magnetic parameters related to Hartmann numbers, viscosities ratios between the fluids, flow behavior indexes and the dimensionless position of the liquid-liquid interfaces.
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Gu, Pan, Karthik Pitchaiman, Ke Liu, Toshikazu Nishida, and Z. Hugh Fan. "Thermally Actuated Plastic Microfluidic Valves." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38041.
Повний текст джерелаАнотація:
This paper reports the design, fabrication, characterization, and integration of a thermally actuated microvalve. The valve is made of 4 plastic layers, consisting of a layer for temperature-sensitive fluid, flow channel substrate, elastomeric film and a plastic film patterned with microheaters. When the temperature-sensitive fluid is heated, its volumetric expansion deflects the elastomeric film into the microchannel, closing the valve. Heat supplied to the temperature-sensitive fluid comes from microfabricated heaters. The external power applied to the heaters can be controlled using a printed circuit board (PCB)-based controller. The main challenge of this design is to find a suitable elastomeric film that is both elastic and can be bonded with cyclic olefin copolymer (COC) substrates. Pressure-sensitive tape (PSA) was investigated as an elastomeric film for the valve. A valve using PSA was successfully fabricated and tested. A conductive solution (NaCl) was filled into a microfluidic channel containing the valve. The operation of the valve was investigated by measuring a change in the microchannel’s ionic conduction current mediated by the resistance variation corresponding to the deflection of the microvalve. In addition, we integrated an array of such valves with other components in a device and used the valves to control the introduction of different separation media for two-dimensional protein separation.
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Khodabakhsh, Mohammad, Mehran Ebrahimian, and Bogdan Epureanu. "Modeling Eddy-Current Damping Force in Magnetic Levitation Systems With Conductors." In ASME 2017 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/dscc2017-5164.
Повний текст джерелаАнотація:
An analytical method is used to develop a model to calculate steady-state eddy-current damping effects in two configurations of magnetic levitation (maglev) systems. The eddy-current based force (eddy-current force) is used for high precision positioning of a levitated permanent magnet in maglev systems. In these systems, the motion of the levitated permanent magnet and changes of the coil’s currents, generate eddy current in the conductors. The proposed analytical model is used to calculate both effects. A conductive cylindrical shell around the levitated object is implemented as a new technique to generate eddy currents in maglev systems. The model is also employed to obtain eddy-current damping effects in a system with a conductive plate beneath the levitated object. The analytical models match results from high fidelity finite element analysis (FEA) with acceptable accuracy in a wide range of operations. Advantages of the two configurations are discussed.
Звіти організацій з теми "Current conducting channel"
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Lau, Y. Y., M. Lampe, R. F. Fernsler, and B. Hui. Current Enhancement in a Conducting Channel. Fort Belvoir, VA: Defense Technical Information Center, May 1985. http://dx.doi.org/10.21236/ada155418.
Повний текст джерела
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Michalak, Julia, Josh Lawler, John Gross, and Caitlin Littlefield. A strategic analysis of climate vulnerability of national park resources and values. National Park Service, September 2021. http://dx.doi.org/10.36967/nrr-2287214.
Повний текст джерелаАнотація:
The U.S. national parks have experienced significant climate-change impacts and rapid, on-going changes are expected to continue. Despite the significant climate-change vulnerabilities facing parks, relatively few parks have conducted comprehensive climate-change vulnerability assessments, defined as assessments that synthesize vulnerability information from a wide range of sources, identify key climate-change impacts, and prioritize vulnerable park resources (Michalak et al. In review). In recognition that funding and planning capacity is limited, this project was initiated to identify geographies, parks, and issues that are high priorities for conducting climate-change vulnerability assessments (CCVA) and strategies to efficiently address the need for CCVAs across all U.S. National Park Service (NPS) park units (hereafter “parks”) and all resources. To help identify priority geographies and issues, we quantitatively assessed the relative magnitude of vulnerability factors potentially affecting park resources and values. We identified multiple vulnerability factors (e.g., temperature change, wildfire potential, number of at-risk species, etc.) and sought existing datasets that could be developed into indicators of these factors. To be included in the study, datasets had to be spatially explicit or already summarized for individual parks and provide consistent data for at least all parks within the contiguous U.S. (CONUS). The need for consistent data across such a large geographic extent limited the number of datasets that could be included, excluded some important drivers of climate-change vulnerability, and prevented adequate evaluation of some geographies. The lack of adequately-scaled data for many key vulnerability factors, such as freshwater flooding risks and increased storm activity, highlights the need for both data development and more detailed vulnerability assessments at local to regional scales where data for these factors may be available. In addition, most of the available data at this scale were related to climate-change exposures, with relatively little data available for factors associated with climate-change sensitivity or adaptive capacity. In particular, we lacked consistent data on the distribution or abundance of cultural resources or accessible data on infrastructure across all parks. We identified resource types, geographies, and critical vulnerability factors that lacked data for NPS’ consideration in addressing data gaps. Forty-seven indicators met our criteria, and these were combined into 21 climate-change vulnerability factors. Twenty-seven indicators representing 12 vulnerability factors addressed climate-change exposure (i.e., projected changes in climate conditions and impacts). A smaller number of indictors measured sensitivity (12 indicators representing 5 vulnerability factors). The sensitivity indicators often measured park or landscape characteristics which may make resources more or less responsive to climate changes (e.g., current air quality) as opposed to directly representing the sensitivity of specific resources within the park (e.g., a particular rare species or type of historical structure). Finally, 6 indicators representing 4 vulnerability factors measured external adaptive capacity for living resources (i.e., characteristics of the park and/or surrounding landscape which may facilitate or impede species adaptation to climate changes). We identified indicators relevant to three resource groups: terrestrial living, aquatic living (including living cultural resources such as culturally significant landscapes, plant, or animal species) and non-living resources (including infrastructure and non-living cultural resources such as historic buildings or archeological sites). We created separate indicator lists for each of these resource groups and analyzed them separately. To identify priority geographies within CONUS,...
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Vera, Cesar Allan, Ma Lourdes Brusola-Vera, Maria Rosario Felizco, and Janice Ian Manlutac. Local Humanitarian Leadership: The View from Local Actors. Oxfam, May 2021. http://dx.doi.org/10.21201/2021.7574.
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The global call for localization and locally led emergency response acknowledges the reality that the humanitarian system is currently organized around international actors. More than the limited access to direct funding, the core issue is the power imbalance between local and international actors. In the Philippines, national and local networks of humanitarian, faith-based, developmental organizations and private sector foundations have been conducting and leading small- and large-scale disaster responses for decades. However, the discourse and struggle for localization have grown in recent years due to the prominence and dominance of international humanitarian actors, especially during large-scale emergencies. Oxfam is one of several international organizations that have signed up to the Grand Bargain, Charter for Change and other agreements that push for localization, and Oxfam in the Philippines has embraced the local humanitarian leadership (LHL) approach holistically.
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Jansson, Anna, Arun Heer, Suzana Rice, Frank Buonaiuto, Danielle Tommaso, Lynn Bocamazo, Stephen Couch, and Jodi McDonald. South Shore of Long Island, New York Regional Sediment Management Investigation : an overview of challenges and opportunities. Engineer Research and Development Center (U.S.), April 2022. http://dx.doi.org/10.21079/11681/43920.
Повний текст джерелаАнотація:
The US Army Corps of Engineers (USACE) is conducting the “South Shore of Long Island, New York Regional Sediment Management Investigation” to further understand sediment dynamics and to develop a comprehensive regional sediment management plan for the south shore of Long Island, New York. Regional sediment management is a systems approach using best management practices for more efficient and effective use of sediments in coastal, estuarine, and inland environments. This investigation seeks to characterize sediment movement on the south shore of Long Island as a holistic system across the entire study area. It focuses on the regional system post-Hurricane Sandy (October 2012) as the storm significantly altered the physical landscape with severe shoreline erosion, which resulted in the construction of projects to reduce the risk of future storms and stakeholder priorities with a new emphasis on bay-side sediment dynamics, such as channel shoaling and disappearing wetlands. Despite the fact the storm caused severe erosion, the equilibrium beach profile, depth of closure, and general shoreline orientation seem to be unaffected. Previous studies have characterized sediment movement at specific sections of the south shore, but these data have not been incorporated to create a system-wide perspective. Coordinating sediment management across the six Atlantic Ocean inlets, Great South Bay Channel, Intracoastal Waterway, and coastal storm risk management (CSRM) projects could save the federal government millions of dollars in dredging and sand placement actions. This technical note presents the progress the investigation has made to date and will be followed with a more in-depth technical report titled South Shore of Long Island, New York Regional Sediment Management Investigation: A Post-Hurricane Sandy Shoreline Evaluation, currently in preparation.
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Ruisi-Besares, Pia, Matthias Sirch, Alyx Belisle, James Duncan, Josephine Robertson, Jennifer Pontius, Danielle Cook, and Elissa Schuett. Technical Report on Assembling Indicators to Monitor Climate-Driven Change in Northeastern Forests. Forest Ecosystem Monitoring Cooperative, September 2021. http://dx.doi.org/10.18125/99o4tq.
Повний текст джерелаАнотація:
Forest ecosystems are experiencing the impacts of climate change in many forms, however, comprehensive monitoring efforts are not always available to identify changing baselines. In order to improve our understanding of the impacts of climate change on ecosystem processes, the FEMC developed the Forest Impacts of Climate Change: Monitoring Indicators tool (Version 1.0). The Forest Impacts of Climate Change: Monitoring Indicators tool was developed for use by researchers and professionals to be able to easily access protocols used to monitor high priority indicators of the impacts of climate change in New England and New York. The monitoring protocols provide information for landowners and managers to implement their own monitoring programs that will be comparable to other studies being conducted across the region. By centralizing information about this network of monitoring sites, more data will become available to the community to help discern how forest ecosystems are changing. This report describes the methods and implementation used to build this tool. To develop the Forest Impacts of Climate Change: Monitoring Indicators tool, FEMC formed a committee of partners to select indicators and provide guidance about the literature review and eventual tool. The committee identified four ecological categories as important for monitoring climate change in the Northeast: Wildlife, Forest Systems, Trees, and Aquatic Systems. FEMC identified who is currently conducting monitoring efforts, what monitoring protocols are available for replication, gaps in monitoring data, and how we can make data and monitoring information easily available so that land managers can have the most up-to -date information possible. The developed tool compiles over 350 studies across 24 different indicators of the impacts of climate change. Through a filterable webtool users can find these studies, as well as 168 replicable protocols to direct implementation. The tool helps to identify gaps in monitoring efforts and provides a platform for users to contribute to regionally cohesive datasets. Monitoring of indicators across systems is critical for tracking and understanding climate change impacts. The Forest Impacts of Climate Change: Monitoring Indicators tool, developed for use by researchers, professionals, and land managers across the region, lets users find methods and protocols for monitoring climate change impacts and see where these monitoring efforts are already being conducted in our region. In addition, you can quickly visualize where there are gaps in our monitoring. As contributors in the Cooperative region share more information about their own monitoring efforts, this will become available to the community through this tool, increasing our ability to track and identify change in our forested ecosystems.
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Boyle, Maxwell, and Elizabeth Rico. Terrestrial vegetation monitoring at Fort Pulaski National Monument: 2019 data summary. National Park Service, December 2021. http://dx.doi.org/10.36967/nrds-2288716.
Повний текст джерелаАнотація:
The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is currently conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2019 marks the first year of conducting this monitoring effort on four SECN parks, including Fort Pulaski National Monument (FOPU). Twelve vegetation plots were established at Fort Pulaski National Monument in August. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Fort Pulaski National Monument in 2019. Data were stratified across two dominant broadly defined habitats within the park (Maritime Tidal Wetlands and Maritime Upland Forests and Shrublands). Noteworthy findings include: Sixty-six vascular plant taxa were observed across 12 vegetation plots, including six taxa not previously known from the park. Plots were located on both Cockspur and McQueen’s Island. The most frequently encountered species in each broadly defined habitat included: Maritime Tidal Wetlands: smooth cordgrass (Spartina alterniflora), perennial saltmarsh aster(Symphyotrichum enuifolium), and groundsel tree (Baccharis halimifolia) Maritime Upland Forests and Shrublands: yaupon (Ilex vomitoria), southern/eastern red cedar (Juniperus silicicola + virginiana), and cabbage palmetto (Sabal palmetto). Four non-native species identified as invasive by the Georgia Exotic Pest Plant Council (GA-EPPC 2018) were found during this monitoring effort. These species (and their overall frequency of occurrence within all plots) included: Japanese honeysuckle (Lonicera japonica; 17%), bahiagrass (Paspalum notatum; 8%), Vasey’s grass (Paspalum urvillei; 8%), and European common reed (Phragmites australis; 8%). Two rare plants tracked by the Georgia Department of Natural Resources (GADNR 2013) were found during this monitoring effort. These include Florida wild privet (Forestiera segregata) and Bosc’s bluet (Oldenlandia boscii). Southern/eastern red cedar and cabbage palmetto were the most dominant species within the tree stratum of the maritime Upland Forest and Shrubland habitat type. Species that dominated the sapling and seedling strata of this type included yaupon, cabbage palmetto, groundsel tree, and Carolina laurel cherry (Prunus caroliniana). The health status of sugarberry (Celtis laevigata)—a typical canopy species in maritime forests of the South Atlantic Coastal Plain--observed on park plots appeared to be in decline, with most stems experiencing elevated levels of dieback and low vigor. Over the past decade, this species has been experiencing unexplained high rates of dieback and mortality throughout its range in the Southeastern United States; current research is focusing on what may be causing these alarming die-off patterns. Duff and litter made up the majority of downed woody biomass (fuel loads) across FOPU vegetation plots.
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Boyle, Maxwell, and Elizabeth Rico. Terrestrial vegetation monitoring at Cape Hatteras National Seashore: 2019 data summary. National Park Service, January 2022. http://dx.doi.org/10.36967/nrr-2290019.
Повний текст джерелаАнотація:
The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is currently conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. The first year of conducting this monitoring effort at four SECN parks, including 52 plots on Cape Hatteras National Seashore (CAHA), was 2019. Twelve vegetation plots were established at Cape Hatteras NS in July and August. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Cape Hatteras National Seashore in 2019. Data were stratified across four dominant broadly defined habitats within the park (Maritime Tidal Wetlands, Maritime Nontidal Wetlands, Maritime Open Uplands, and Maritime Upland Forests and Shrublands) and four land parcels (Bodie Island, Buxton, Hatteras Island, and Ocracoke Island). Noteworthy findings include: A total of 265 vascular plant taxa (species or lower) were observed across 52 vegetation plots, including 13 species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Maritime Tidal Wetlands: saltmeadow cordgrass Spartina patens), swallow-wort (Pattalias palustre), and marsh fimbry (Fimbristylis castanea) Maritime Nontidal Wetlands: common wax-myrtle (Morella cerifera), saltmeadow cordgrass, eastern poison ivy (Toxicodendron radicans var. radicans), and saw greenbriar (Smilax bona-nox) Maritime Open Uplands: sea oats (Uniola paniculata), dune camphorweed (Heterotheca subaxillaris), and seabeach evening-primrose (Oenothera humifusa) Maritime Upland Forests and Shrublands: : loblolly pine (Pinus taeda), southern/eastern red cedar (Juniperus silicicola + virginiana), common wax-myrtle, and live oak (Quercus virginiana). Five invasive species identified as either a Severe Threat (Rank 1) or Significant Threat (Rank 2) to native plants by the North Carolina Native Plant Society (Buchanan 2010) were found during this monitoring effort. These species (and their overall frequency of occurrence within all plots) included: alligatorweed (Alternanthera philoxeroides; 2%), Japanese honeysuckle (Lonicera japonica; 10%), Japanese stilt-grass (Microstegium vimineum; 2%), European common reed (Phragmites australis; 8%), and common chickweed (Stellaria media; 2%). Eighteen rare species tracked by the North Carolina Natural Heritage Program (Robinson 2018) were found during this monitoring effort, including two species—cypress panicgrass (Dichanthelium caerulescens) and Gulf Coast spikerush (Eleocharis cellulosa)—listed as State Endangered by the Plant Conservation Program of the North Carolina Department of Agriculture and Consumer Services (NCPCP 2010). Southern/eastern red cedar was a dominant species within the tree stratum of both Maritime Nontidal Wetland and Maritime Upland Forest and Shrubland habitat types. Other dominant tree species within CAHA forests included loblolly pine, live oak, and Darlington oak (Quercus hemisphaerica). One hundred percent of the live swamp bay (Persea palustris) trees measured in these plots were experiencing declining vigor and observed with symptoms like those caused by laurel wilt......less
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Boyle, Maxwell, and Elizabeth Rico. Terrestrial vegetation monitoring at Timucuan Ecological and Historic Preserve: 2019 data summary—Version 2.0. National Park Service, February 2022. http://dx.doi.org/10.36967/nrds-2290196.
Повний текст джерелаАнотація:
The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and it is currently conducted on 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2019 marks the first year of conducting this monitoring effort on four SECN parks, including Timucuan Ecological and Historic Preserve (TIMU). A total of 23 vegetation plots were established in the park in May and June. Data collected in each plot include species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches (in)]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Timucuan Ecological and Historic Preserve in 2019. Data were stratified across three dominant broadly defined habitats within the park (Coastal Plain Nonalluvial Wetlands, Coastal Plain Open Uplands and Woodlands, and Maritime Upland Forests and Shrublands) and three land parcels (Cedar Point, Theodore Roosevelt, and Thomas Creek). Noteworthy findings include: A total of 157 vascular plant taxa (species or lower) were observed across 23 vegetation plots, including nine species not previously known from the park. Three plots were located in the footprint of the Yellow Bluff Fire, and were sampled only two weeks following the fire event. Muscadine (Muscadinia rotundifolia), cat greenbrier (Smilax glauca), water oak (Quercus nigra), and swamp tupelo (Nyssa biflora) were the most frequently encountered species in Coastal Plain Nonalluvial Wetland habitat; saw palmetto (Serenoa repens), slash pine (Pinus elliottii), and gallberry (Ilex glabra) were the most frequently encountered species in Coastal Plain Open Upland and Woodland habitat; and Darlington oak (Quercus hemisphaerica), Spanish moss (Tillandsia usenoides), and red bay (Persea borbonia) were the most frequently encountered species in Maritime Upland Forests and Shrublands. There were no exotic species of the Florida Exotic Pest Plant Council list of invasive plants (FLEPPC 2020) observed on any of these plots. Both red bay and swamp bay (Persea palustris) were largely absent from the tree stratum in these plots; however, they were present (occasionally in high abundance) in the seedling and sapling strata across all habitat types. Buckthorn bully (Sideroxylon lycioides)—listed as Endangered in the state of Florida by the Florida Department of Agriculture and Consumer Services (FDACS 2020)—was observed in three Maritime Upland Forest and Shrubland plots. The tree strata in each broadly defined habitat were dominated by the following species: Coastal Plain Nonalluvial Wetlands-loblolly bay (Gordonia lasianthus) Coastal Plain Open Uplands and Woodlands-longleaf pine (Pinus palustris) Maritime Upland Forests and Shrublands-oaks (Quercus sp.) Most stems within the tree strata exhibited healthy vigor and only moderate dieback across all habitat types. However, there was a large amount of standing dead trees in plots within Maritime Upland Forests and Shrublands. Downed woody biomass (fuel loads) were highest in the Cedar Point and Thomas Creek land parcels.
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Boyle, M., and Elizabeth Rico. Terrestrial vegetation monitoring at Fort Matanzas National Monument: 2019 data summary. National Park Service, May 2022. http://dx.doi.org/10.36967/nrds-2293409.
Повний текст джерелаАнотація:
The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and it is currently conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2019 marks the first year of conducting this monitoring effort at four SECN parks, including Fort Matanzas National Monument (FOMA). Nine vegetation plots, located on Anastasia and Rattlesnake Islands, were established at Fort Matanzas National Monument in June. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Fort Matanzas National Monument in 2019. Data were stratified across two dominant broadly defined habitats within the park (Maritime Upland Forests/Shrublands and Maritime Open Uplands). Noteworthy findings include: Eighty-two vascular plant taxa (species or lower) were observed across nine vegetation plots, including eight species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Maritime Upland Forests and Shrublands: saw palmetto (Serenoa repens), yaupon (Ilex vomitoria), southern/eastern red cedar (Juniperus silicicola + virginiana), American beautyberry (Callicarpa americana), and American burnweed (Erectites hieraciifolius). Maritime Open Uplands: sea oats (Uniola paniculata), earleaf greenbriar (Smilax auriculata), and dixie sandmat (Euphorbia bombensis). ne non-native species, Brazilian pepper (Schinus terebinthifolia), categorized as invasive by the Florida Exotic Pest Plant Council (FLEPPC 2019) was encountered in one Maritime Upland Forest and Shrubland plot during this monitoring effort. There were not any rare plants tracked by the Florida Department of Agriculture and Consumer Services (FDACS 2020) found during this monitoring effort. All plants located in these monitoring plots are fairly common throughout Florida, as well as across the Southeast Coast. Three species observed, however, are on the FDACS 2020 list of commercially exploited plants within the state. These include saw palmetto, cinnamon fern (Osmundastrum cinnamomeum), and coontie (Zamia integrifolia var. umbrosa). Southern/eastern red cedar and cabbage palmetto (Sabal palmetto) were the most dominant species within the tree stratum of the Maritime Upland Forest and Shrubland habitat type. Species that dominated the sapling and seedling strata of this type included yaupon and cabbage palmetto. More than 75% of the trees measured in the parks Maritime Upland Forest and Shrubland habitat type were alive and experiencing healthy vigor. Of the 22 trees that were dead, more than 50% of those were southern/eastern red cedar. Most of those individuals that were observed with moderate or severe decline and greater than 50% dieback were southern/eastern red cedars. Although red bay (Persea borbonia) was identified as one of the “principal understory tree” species within Fort Matanzas National Monument’s maritime forests in 2004 (Zomlefer et al. 2004), tree-sized individuals were rarely detected on plots during this monitoring effort. This may be in part due to the detection of laurel wilt disease within St. Johns County in 2006 (USDA 2021). Based on the low detection...