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Artykuły w czasopismach na temat "HCN current"
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Brandt, Mathias C., Jeannette Endres-Becker, Naufal Zagidullin, Lukas J. Motloch, Fikret Er, Dennis Rottlaender, Guido Michels, Stefan Herzig i Uta C. Hoppe. "Effects of KCNE2 on HCN isoforms: distinct modulation of membrane expression and single channel properties". American Journal of Physiology-Heart and Circulatory Physiology 297, nr 1 (lipiec 2009): H355—H363. http://dx.doi.org/10.1152/ajpheart.00154.2009.
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Hyperpolarization-activated cation (HCN) channels give rise to an inward current with similar but not identical characteristics compared with the pacemaker current ( If), suggesting that HCN channel function is modulated by regulatory β-subunits in native tissue. KCNE2 has been proposed to serve as a β-subunit of HCN channels; however, available data remain contradictory. To further clarify this situation, we therefore analyzed the effect of KCNE2 on whole cell currents, single channel properties, and membrane protein expression of all cardiac HCN isoforms in the CHO cell system. On the whole cell level, current densities of all HCN isoforms were significantly increased by KCNE2 without altering voltage dependence or current reversal. While these results correlated well with the KCNE2-mediated 2.2-fold and 1.6-fold increases of membrane protein levels of HCN2 and HCN4, respectively, no effect of KCNE2 on HCN1 expression was obtained. All HCN subtypes displayed faster activation kinetics upon coexpression with KCNE2. Most importantly, for the first time, we demonstrated modulation of single channel function by KCNE2, thus supporting direct functional interaction with HCN subunits. In the presence of KCNE2, the single channel amplitudes and conductance of HCN1, HCN2, and HCN4 were significantly increased versus control recordings. Mean open time was significantly increased in cells coexpressing HCN2 + KCNE2, whereas it was unaffected in HCN1 + KCNE2 cotransfected cells and reduced in HCN4 + KCNE2 cotransfected cells compared with the respective HCN subunits alone. Thus, we demonstrate KCNE2-mediated distinct effects on HCN membrane expression and direct functional modulation of HCN isoforms, further supporting that KCNE2 surves as a regulatory β-subunit of HCN channels.
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Männikkö, Roope, Shilpi Pandey, H. Peter Larsson i Fredrik Elinder. "Hysteresis in the Voltage Dependence of HCN Channels". Journal of General Physiology 125, nr 3 (14.02.2005): 305–26. http://dx.doi.org/10.1085/jgp.200409130.
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Hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels are important for rhythmic activity in the brain and in the heart. In this study, using ionic and gating current measurements, we show that cloned spHCN channels undergo a hysteresis in their voltage dependence during normal gating. For example, both the gating charge versus voltage curve, Q(V), and the conductance versus voltage curve, G(V), are shifted by about +60 mV when measured from a hyperpolarized holding potential compared with a depolarized holding potential. In addition, the kinetics of the tail current and the activation current change in parallel to the voltage shifts of the Q(V) and G(V) curves. Mammalian HCN1 channels display similar effects in their ionic currents, suggesting that the mammalian HCN channels also undergo voltage hysteresis. We propose a model in which HCN channels transit between two modes. The voltage dependence in the two modes is shifted relative to each other, and the occupancy of the two modes depends on the previous activation of the channel. The shifts in the voltage dependence are fast (τ ≈ 100 ms) and are not accompanied by any apparent inactivation. In HCN1 channels, the shift in voltage dependence is slower in a 100 mM K extracellular solution compared with a 1 mM K solution. Based on these findings, we suggest that molecular conformations similar to slow (C-type) inactivation of K channels underlie voltage hysteresis in HCN channels. The voltage hysteresis results in HCN channels displaying different voltage dependences during different phases in the pacemaker cycle. Computer simulations suggest that voltage hysteresis in HCN channels decreases the risk of arrhythmia in pacemaker cells.
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Lieu, Deborah K., Yau Chi Chan, Chu Pak Lau, Hung Fat Tse, Chung Wah Siu i Ronald A. Li. "Overexpression of HCN-encoded pacemaker current silences bioartificial pacemakers". Heart Rhythm 5, nr 9 (wrzesień 2008): 1310–17. http://dx.doi.org/10.1016/j.hrthm.2008.05.010.
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Dekker, John P., i Gary Yellen. "Cooperative Gating between Single HCN Pacemaker Channels". Journal of General Physiology 128, nr 5 (16.10.2006): 561–67. http://dx.doi.org/10.1085/jgp.200609599.
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HCN pacemaker channels (If, Iq, or Ih) play a fundamental role in the physiology of many excitable cell types, including cardiac myocytes and central neurons. While cloned HCN channels have been studied extensively in macroscopic patch clamp experiments, their extremely small conductance has precluded single channel analysis to date. Nevertheless, there remain fundamental questions about HCN gating that can be resolved only at the single channel level. Here we present the first detailed single channel study of cloned mammalian HCN2. Excised patch clamp recordings revealed discrete hyperpolarization-activated, cAMP-sensitive channel openings with amplitudes of 150–230 fA in the activation voltage range. The average conductance of these openings was ∼1.5 pS at −120 mV in symmetrical 160 mM K+. Some traces with multiple channels showed unusual gating behavior, characterized by a variable long delay after a voltage step followed by runs of openings. Noise analysis on macroscopic currents revealed fluctuations whose magnitudes were systematically larger than predicted from the actual single channel current size, consistent with cooperativity between single HCN channels.
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Yang, Qizong, Pavlo Kuzyk, Igor Antonov, Caleb J. Bostwick, Andrea B. Kohn, Leonid L. Moroz i Robert D. Hawkins. "Hyperpolarization-activated, cyclic nucleotide-gated cation channels in Aplysia: Contribution to classical conditioning". Proceedings of the National Academy of Sciences 112, nr 52 (14.12.2015): 16030–35. http://dx.doi.org/10.1073/pnas.1501731113.
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Hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels are critical regulators of neuronal excitability, but less is known about their possible roles in synaptic plasticity and memory circuits. Here, we characterized the HCN gene organization, channel properties, distribution, and involvement in associative and nonassociative forms of learning in Aplysia californica. Aplysia has only one HCN gene, which codes for a channel that has many similarities to the mammalian HCN channel. The cloned acHCN gene was expressed in Xenopus oocytes, which displayed a hyperpolarization-induced inward current that was enhanced by cGMP as well as cAMP. Similarly to its homologs in other animals, acHCN is permeable to K+ and Na+ ions, and is selectively blocked by Cs+ and ZD7288. We found that acHCN is predominantly expressed in inter- and motor neurons, including LFS siphon motor neurons, and therefore tested whether HCN channels are involved in simple forms of learning of the siphon-withdrawal reflex in a semiintact preparation. ZD7288 (100 μM) significantly reduced an associative form of learning (classical conditioning) but had no effect on two nonassociative forms of learning (intermediate-term sensitization and unpaired training) or baseline responses. The HCN current is enhanced by nitric oxide (NO), which may explain the postsynaptic role of NO during conditioning. HCN current in turn enhances the NMDA-like current in the motor neurons, suggesting that HCN channels contribute to conditioning through this pathway.
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Meuth, Sven G., Tatyana Kanyshkova, Patrick Meuth, Peter Landgraf, Thomas Munsch, Andreas Ludwig, Franz Hofmann, Hans-Christian Pape i Thomas Budde. "Membrane Resting Potential of Thalamocortical Relay Neurons Is Shaped by the Interaction Among TASK3 and HCN2 Channels". Journal of Neurophysiology 96, nr 3 (wrzesień 2006): 1517–29. http://dx.doi.org/10.1152/jn.01212.2005.
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By combining molecular biological, electrophysiological, immunological, and computer modeling techniques, we here demonstrate a counterbalancing contribution of TASK channels, underlying hyperpolarizing K+ leak currents, and HCN channels, underlying depolarizing Ih, to the resting membrane potential of thalamocortical relay (TC) neurons. RT-PCR experiments revealed the expression of TASK1, TASK3, and HCN1–4. Quantitative determination of mRNA expression levels and immunocytochemical staining demonstrated that TASK3 and HCN2 channels represent the dominant thalamic isoforms and are coexpressed in TC neurons. Extracellular acidification, a standard procedure to inhibit TASK channels, blocked a TASK current masked by additional action on HCN channels. Only in the presence of the HCN blocker ZD7288 was the pH-sensitive component typical for a TASK current, i.e., outward rectification and current reversal at the K+ equilibrium potential. In a similar way extracellular acidification was able to shift the activity pattern of TC neurons from burst to tonic firing only during block of Ih or genetic knock out of HCN channels. A single compartmental computer model of TC neurons simulated the counterbalancing influence of TASK and HCN on the resting membrane potential. It is concluded that TASK3 and HCN2 channels stabilize the membrane potential by a mutual functional interaction, that the most efficient way to regulate the membrane potential of TC neurons is the converse modulation of TASK and HCN channels, and that TC neurons are potentially more resistant to insults accompanied by extracellular pH shifts in comparison to other CNS regions.
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Accili, E. A., C. Proenza, M. Baruscotti i D. DiFrancesco. "From Funny Current to HCN Channels: 20 Years of Excitation". Physiology 17, nr 1 (luty 2002): 32–37. http://dx.doi.org/10.1152/physiologyonline.2002.17.1.32.
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The “funny” (pacemaker) current has unusual characteristics, including activation on hyperpolarization, permeability to K+ and Na+, modulation by internal cAMP, and a tiny, single-channel conductance. In cardiac cells and neurons, pacemaker channels control repetitive activity and excitability. The recent cloning of HCN subunits provides new insight into the molecular basis for the funny channel properties.
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Li, Yu-Long, i Hong Zheng. "Angiotensin II-NADPH oxidase-derived superoxide mediates diabetes-attenuated cell excitability of aortic baroreceptor neurons". American Journal of Physiology-Cell Physiology 301, nr 6 (grudzień 2011): C1368—C1377. http://dx.doi.org/10.1152/ajpcell.00214.2011.
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Overactivation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is involved in diabetes-depressed excitability of aortic baroreceptor neurons in nodose ganglia. This involvement links to the autonomic dysfunction associated with high morbidity and mortality in diabetic patients. The present study examined the effects of an angiotensin II type I receptor (AT1R) antagonist (losartan), a NADPH oxidase inhibitor (apocynin), and a superoxide dismutase mimetic (tempol) on the enhanced HCN currents and attenuated cell excitability in diabetic nodose neurons. In sham and streptozotocin-induced type 1 diabetic rats, HCN currents and cell excitability of aortic baroreceptor neurons were recorded by the whole cell patch-clamp technique. The angiotensin II level in nodose ganglia from diabetic rats was higher than that from sham rats (101.6 ± 4.8 vs. 38.9 ± 4.2 pg/mg protein, P < 0.05). Single-cell RT-PCR, Western blot, immunofluorescence staining, and chemiluminescence data showed that mRNA and protein expression of AT1R, protein expression of NADPH oxidase components, and superoxide production in nodose neurons were increased in diabetic rats compared with those from sham rats. HCN current density was higher and cell excitability was lower in aortic baroreceptor neurons from diabetic rats than that from sham rats. Losartan (1 μM), apocynin (100 μM), and tempol (1 mM) normalized the enhanced HCN current density and increased the cell excitability in the aortic baroreceptor neurons of diabetic rats. These findings suggest that endogenous angiotensin II-NADPH oxidase-superoxide signaling contributes to the enhanced HCN currents and the depressed cell excitation in the aortic baroreceptor neurons of diabetic rats.
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Kelley, Craig, Salvador Dura-Bernal, Samuel A. Neymotin, Srdjan D. Antic, Nicholas T. Carnevale, Michele Migliore i William W. Lytton. "Effects of Ih and TASK-like shunting current on dendritic impedance in layer 5 pyramidal-tract neurons". Journal of Neurophysiology 125, nr 4 (1.04.2021): 1501–16. http://dx.doi.org/10.1152/jn.00015.2021.
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We simulated chirp current stimulation in the apical dendrites of 5 biophysically detailed multicompartment models of neocortical pyramidal tract neurons and found that a combination of HCN channels and TASK-like channels produced the best fit to experimental measurements of dendritic impedance. We then explored how HCN and TASK-like channels can shape the dendritic impedance as well as the voltage response to synaptic currents.
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Proenza, Catherine, i Gary Yellen. "Distinct Populations of HCN Pacemaker Channels Produce Voltage-dependent and Voltage-independent Currents". Journal of General Physiology 127, nr 2 (30.01.2006): 183–90. http://dx.doi.org/10.1085/jgp.200509389.
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Hyperpolarization-activated HCN pacemaker channels are critical for the generation of spontaneous activity and the regulation of excitability in the heart and in many types of neurons. These channels produce both a voltage-dependent current (Ih) and a voltage-independent current (Iinst or VIC). In this study, we explored the molecular basis of the voltage-independent current. We found that for the spHCN isoform, VIC averaged ∼4% of the maximum HCN conductance that could be activated by hyperpolarization. Cyclic AMP increased the voltage-independent current in spHCN to ∼8% of maximum. In HCN2, VIC was ∼2% of the maximal current, and was little affected by cAMP. VIC in both spHCN and HCN2 was blocked rapidly both by ZD7288 (an HCN channel blocker that is thought to bind in the conduction pore) and by application of Cd2+ to channels containing an introduced cysteine in the pore (spHCN-464C or HCN2-436C). These results suggest that VIC flows through the main conduction pathway, down the central axis of the protein. We suspected that VIC simply represented a nonzero limiting open probability for HCN channels at positive voltages. Surprisingly, we found instead that the spHCN channels carrying VIC were not in rapid equilibrium with the channels carrying the voltage-dependent current, because they could be blocked independently; a single application of blocker at a depolarized potential essentially eliminated VIC with little change in Ih. Thus, VIC appears to be produced by a distinct population of HCN channels. This voltage-independent current could contribute significantly to the role of HCN channels in neurons and myocytes; VIC flowing through the channels at physiological potentials would tend to promote excitability by accelerating both depolarization and repolarization.
Rozprawy doktorskie na temat "HCN current"
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Shah, Nikhil N. "SH3 AND MULTIPLE ANKYRIN REPEAT DOMAIN 3 (SHANK3) AFFECTS THE EXPRESSION OF HYPERPOLARIZATION-ACTIVATED CYCLIC NUCLEOTIDE-GATED (HCN) CHANNELS IN MOUSE MODELS OF AUTISM". VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4997.
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SH3 and multiple ankyrin repeat domains 3 (SHANK3) is a multidomain scaffold protein that is highly augmented in the postsynaptic density (PSD) of excitatory glutamatergic synapses within the central and peripheral nervous systems. SHANK3 links neurotransmitter receptors, ion channels, and other critical membrane proteins to intracellular cytoskeleton and signal transduction pathways. Mutations in SHANK3 are linked with a number neuropsychiatric disorders including autism spectrum disorders (ASDs). Intellectual disability, impaired memory and learning, and epilepsy are some of the deficits commonly associated with ASDs that result from mutations in SHANK3. Interestingly, these symptoms show some clinical overlap with presentations of human neurological disorders involving hyperpolarization-activated cyclin nucleotide-gated (HCN) channels. In fact, it has recently been demonstrated in human neurons that SHANK3 haploinsufficiency causes Ih-channel dysfunction, and that SHANK3 has a physical interaction with HCN channels via its ANKYRIN repeat domain. These insights suggest that SHANK3 may play important roles in HCN channel expression and function, and put forward the idea that HCN channelopathies may actually encourage some of the symptoms observed in patients with SHANK-deficiency related ASDs. In this study, we provide preliminary data that suggests the ANK domain of SHANK3 interacts with COOH portion of HCN1. We also exploited the differences between two mouse models of autism to show that a subset of SHANK3 isoforms may be involved in the proper expression and function of HCN channels. We found that HCN2 expression is significantly decreased in a mouse model lacking all major isoforms of SHANK3 (exons 13-16 deleted; Δ13-16), while HCN2 expression is unaltered in a mouse model only lacking SHANK3a and SHANK3b (exons 4-9 deleted; Δ4-9). Surprisingly, we also found that HCN4 expression is altered in SHANK3Δ13-16, but not SHANK3Δ4-9. Taken together, our results show HCN channelopathy as a major downstream carrier of SHANK3 deficiency.
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LICHERI, VALENTINA. "Modulation of Hyperpolarization-Activated Cation Currents (Ih) by Ethanol in Rat Hippocampal CA3 Pyramidal Neurons". Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266622.
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It is well established that ethanol (EtOH), through the interaction with several
membrane proteins, as well as intracellular pathways, is capable to modulate many
neuronal function. Recent reports show that EtOH increases the firing rate of
hippocampal GABAergic interneurons through the positive modulation of the
hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels. This effect
might be consistent with the increase of GABA release from presynaptic terminals
observed in both CA1 and CA3 inhibitory synapses that leads the enhancement of the
GABAergic system induced by EtOH. The activation of HCN produced an inward
currents that are commonly called Ih. Ih play an important role for generating specific
neuronal activities in different brain regions, including specific sub-regions of the
hippocampal formation, such as CA1 and CA3 pyramidal neurons and hippocampal
GABAergic interneurons. The main physiologic effect mediated by HCN-induced Ih is
directed to the control of the neuronal resting membrane potential and action
potential (AP) discharge as well as dampen synaptic integration. Since robust Ih are
also present in CA3 glutamatergic neurons, I here investigated whether the action of
EtOH in the control of CA3 excitability can be correlated with its possible direct
interaction with these cation channels. For this purpose, patch-clamp experiments
were performed in CA3 pyramidal neurons from hippocampal coronal slices obtained
from male Sprague-Dawley rats. The data obtained demonstrated that EtOH is able to
modulate Ih in biphasic manner depending on the concentrations used. Low EtOH
concentrations enhanced Ih amplitude, while high reversibly reduced them. This
biphasic action induced by EtOH reflects on firing rate and synaptic integration. In
addition, in this reports it has been shown that EtOH modulates the function of HCN
channels through interfering with the cAMP/AC/PKA intracellular pathways, an effect
that is mimicked also by other endogenous compounds such as dopamine through D1
receptors activation. These data suggest that the HCN-mediated Ih currents in CA3
pyramidal neurons are sensitive to EtOH action, which at low or relevant
concentrations is able to increase or reduce their function respectively. Altogether
these data suggest a potential new mechanism of EtOH actions on hippocampal
formation and may help to better understand the depressant central activity showed
by this drug of abuse
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Baktiono, Surya. "A Study of Field-Oriented Control of a Permanent Magnet Synchronous Generator and Hysteresis Current Control for Wind Turbine Application". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338314559.
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Hu, Shen. "Esquisse d’une théorie de l’encastrement thermo-économique du social : d’une enquête empirique sur la consommation d’alcool des Han à un renouveau épistémologique de la socio-anthropologie". Electronic Thesis or Diss., Paris 8, 2018. http://www.theses.fr/2018PA080106.
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Ce travail de thèse repose sur une enquête commanditée par un fabricant de cognac. Ce dernier, lourdement frappé par la compagne anti-corruption qu’ont lancée les dirigeants chinois fin 2012, souhaiterait développer un cognac dédié au marché sinophone (chinois, singapourien et taïwanais) de la boîte de nuit et du bar. Adoptant une approche soumettant la problématique marketing à la méthode ethnographique, nous avons d’abord réalisé une ethnographie de la consommation d’alcool des jeunes sinophones en boîte de nuit et au bar. Cette enquête a été ensuite complétée par une autre portant sur la consommation d’alcool des Chinois en général. La méthode inductive que nous avons employée a permis de faire de ces recherches ethnographiques un générateur de questionnements auxquelles nous ne nous étions pas attendus. Ainsi, outre la partie descriptive consistant à restituer les différents modes de consommation d’alcool que nous avons observés, cette thèse est aussi composée d’une autre partie théorique. A partir des questions soulevées par la première partie descriptive, cette partie théorique a pour objectif d’esquisser, à contre-courant de la mouvance sociologiste qui caractérise l’anthropologie d’après-guerre, une théorie de l’encastrement « économique » du « social ». Dans la perspective de rompre à la fois avec les excès évolutionnistes et anti-évolutionnistes de l’histoire anthropologique, cette thèse consiste entre autres en une refonte de la théorie monétaire, laquelle aurait pour fonction de rendre compte de l’actuelle synergie géopolitique entre la Chine monopartiste et l’Occident pluripartisteThis work is based on an investigation commissioned by a cognac manufacturer. Heavily hit by the anti-corruption campaign launched by Chinese top leaders at the end of 2012, this manufacturer was seeking to develop a cognac product dedicated to the Sinophone (Chinese, Singaporean and Taiwanese) market of nightclubs and bars. Using an approach that subjects the marketing problem to the ethnographic method, we first performed an ethnography of the alcohol consumption of young Sinophone people in nightclubs and bars. This investigation was then supplemented by another one on the consumption of alcohol by the Chinese in general. The inductive method which we have employed has allowed us to use these ethnographic materials as a generator of research questions which we had not expected. Thus, apart from the descriptive part that synthesises the different modes of alcohol consumption that we have observed, this thesis is also composed of another theoretical part. On the basis of the questions raised by the first descriptive part, this theoretical part aims at sketching a theory of the “economic” embedding of the “social”, which runs counter to the sociologist trends characterising the postwar anthropology. In order to break with both the evolutionist and anti-evolutionist excesses of anthropological history, this thesis consists, among other things, in a revision of the monetary theory, the function of which would be to account for the geopolitical synergy between the “one-party China” and the “multi-party West” at present
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Katyare, Nupur. "Stimulus statistics and HCN current mediated resonance sets the scale of input-output mapping in Stellate cells of the Medial Entorhinal Cortex". Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5441.
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The functional significance of the computations performed by Stellate cells of the Medial
Entorhinal Cortex, proven time and again, makes them insightful, yet intriguing. The
gradients of the intrinsic properties of these cells, aligned to the actual grid cell spacing
gradients, have encouraged many thoughtful experiments.
A long sought question in the stellate cell literature is thus the one seeking mechanistic
implications for these correlates. The intrinsic dynamics of these cells have been tested
previously in this light, primarily focusing on their spectral characteristics. However,
the resonance phenomenon underlying these dynamics has not received the attention
it deserves, and its potency under the in-vivo high conductance states to influence the
input-output mapping remains to be estimated.
In this light, we analysed the signal gain of stellate cells in the presence of in-vivo
like fluctuating conductance based synaptic inputs injected through the Dynamic clamp,
in rat brain slices. We observed a consistent, HCN current sensitive, theta frequency
peak in signal gain, indicating that the HCN current mediated resonance mechanisms
are functional even under a heavy input barrage.
Next, we tested the effects of an array of input statistics on this signal gain and
observed it to be mostly unaffected by the input strength, but relatively susceptible to
the input kinetics. Additionally, as a possible reflection of the underlying signal gain,
we observed a significant theta modulation of inputs by HCN current, the extent of
which was found to be influenced by the excitatory, but not inhibitory synaptic kinetics.
Surprisingly, a corresponding modulation in the gamma frequencies was also observed for
the firing rate response, wherein the signal gain in gamma frequencies was found to be
higher in the presence of HCN, which also coincided with increased occurrence of bursts A computational model with HCN-persistent sodium channels with similar simulated
in vivo conditions could reproduce the experimental results, additionally suggesting the
strength of inhibition and the kinetics of excitation as the input statistic based alternate
resonance mechanisms which can operate independent of HCN.
Our results thus suggest frequency dependent gain as an appropriate measure for
analysing the input-output mapping in the stellate cells, and point out the mechanisms
via which the HCN currents and input statistics can interact and determine the scaling
of responses in these cells.
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Deng, Yongan. "A comparison between STATCOMs using PWM voltage control and hysteresis current control (HCC)". Thesis, 2007. http://spectrum.library.concordia.ca/975587/1/MR40879.pdf.
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The Voltage Source Inverter (VSI) has now become the fundamental building block component in Flexible AC Transmission Systems (FACTS). Among the various applications of a VSI, the Static Synchronous Compensator (STATCOM) is the most popular one. It injects a set of three-phase balanced sinusoidal currents with controllable magnitude and phase angle, into the transmission line to regulate the transmission line voltage or to compensate for the reactive power. Under the condition that no external source/sink is available on the DC side, it should also absorb a small amount of active power from the transmission line to maintain the DC bus voltage constant and compensate for any real power losses within the VSI. In this process, the control method of the VSI is one of the key factors to influence the performance of the STATCOM. This thesis investigates the effect of two modulation schemes on the performance of a STATCOM. The first is the Pulse Width Modulation (PWM) voltage control and the second Hysteresis Current Control (HCC). The performance of the two schemes under steady-state and transient conditions are assessed by means of simulations using EMTPRV. The results presented in the thesis justify the fact that PWM voltage control has become the de-facto modulation technique for STATCOM applications despite well known limitation of generation of low voltage harmonics with large magnitudes when operating at low switching frequencies.
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Jao, Xiang-Jen, i 饒翔仁. "A Fast-Transient-Response HCC Buck Converter with Pseudo-Current- Detection Techniques and An OLED Current-Controlled Driver Using High-Voltage Processes". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/22978j.
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碩士國立臺北科技大學
電子工程系
106
The proposed circuit of the thesis is a fast-transient response HCC buck converter with pseudo-current-detection techniques in the first part. The pseudo-current-detection circuit is simpler and less transistors than the traditional current sensing circuit. The hysteresis-current-controlled (HCC) circuit can achieve the fast transient response. The proposed converter can supply an output voltage from 1V to 2.5V, output load current range from 0.05A to 0.5A, when the supply voltage is 3.3V. When the supply voltage is 3.3V. The switching frequency of the proposed converter is 1 MHz, when output voltage is 2.5V. The proposed buck converter has been fabricated with TSMC 0.35-μm CMOS 2P4M process, the total chip area is 1.5 × 1.5 mm2 (with PADs). The proposed circuit of the thesis is an OLED current controlled driver using high-voltage processes in the second part. This proposed circuit, which mainly provides the current to next OLED circuit, is designed according to the datasheet on the market. The work current is from 185mA to 310mA. The overall circuit can be divided into two parts, an AC-DC converter and an OLED current driver. The OLED driver, which can tolerate 110V to 800V, uses PWM control. The OLED driver has been fabricated with TSMC 0.5-μm UHV800V 2P3M process, the total chip area is 2 × 1.25 mm2 (with PADs).
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Faszewski, Ellen Evelyn. "Use of ion-selective microelectrodes to determine the contribution of H(+), K(+), and HCO(-) towards the asymmetric current in Xenopus laevis oocytes". 1999. https://scholarworks.umass.edu/dissertations/AAI9920597.
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The asymmetric current previously identified using voltage probe techniques in maturing Xenopus laevis oocytes has been further investigated using non-invasive ionselective microelectrodes. Three-dimensional fluxes of hydrogen (H+), potassium (K+), and bicarbonate ([special characters omitted]), of varying magnitudes, were found to be hidden within this net 10 pmol current. These fluxes were seen to vary with respect to developmental stage and presence of surrounding follicular tissue. The mechanisms of H + and K+ transport were also examined with P and V-type ATPase pump inhibitors, ortho-vanadate and N-ethyl maleimide (NEM), respectively. A representative flux pattern of H+, K+, and [special characters omitted] ions around fully developed Xenopus oocytes was obtained from this research. H+ effluxes, as well as K+ influxes and effluxes, were detected at the animal, vegetal, and equatorial regions of the membrane. The transport of these two ions was seen to be highly correlated in defolliculated oocytes, with large H+ effluxes accompanied by large K+ influxes. Small effluxes of [special characters omitted] were measured at the animal and vegetal hemispheres. The use of ATPase pump inhibitors also provided information regarding possible transport mechanisms. Vanadate (0.01 mM) and NEM (1 mM) significantly reduced the H+ flux in defolliculated and follicle-enclosed oocytes, respectively. However, the observed K+ fluxes were unaffected by these inhibitors. The combination of these results suggests that ATPase pumps are important only in the transport of H+ ions and more specifically, the presence of a P-type ATPase on the surface of the oocyte membrane and a V-type ATPase in the follicular tissue. The technique of measuring extracellular fluxes from developing cells with ion-selective electrodes was also examined. Construction of more efficient sampling rules, determination of electrode efficiencies using these sampling rules, and calibration of the carbonate electrode were some of the advances resulting from this research. In addition, the implementation of a multiple head ion probe provided simultaneous data collection of more than one ion type from the same oocyte, allowing for the study of ion-ion interactions and the determination of bicarbonate flux Patterns with H+ and carbonate electrodes.
Książki na temat "HCN current"
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Ni bian han ji yuan li yu she ji. Beijing Shi: Ji xie gong ye chu ban she, 2008.
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Dang dai Ying Han ci dian: A current English-Chinese dictionary. Kunming Shi: Yunnan ren min chu ban she, 1985.
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Nihon no shihei: Zaigaichi ginkōken Chūgoku heigō junbi ginkōken hen : The Federal Reserve Bank of China, 1938-1945. Wyd. 2. [Fukuoka-shi?: Horimoto Tadashi?], 1999.
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Dang dai Ying Han yi xue shi yong ci dian: Current English-Chinese practical medical dictionary. Shanghai Shi: Shanghai shi jie tu shu chu ban gong si, 2008.
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Xian dai gao ji Ying Han, Han Ying lei yi lian xiang ci dian: Advanced English-Chinese, Chinese-English lexicon of current English. Wuhan Shi: Hubei jiao yu chu ban she, 2002.
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Xian dai Ying Han Han Ying dian li dian zi ji shu ci dian: A dictionary of current power electronic technology, English-Chinese, Chinese-English. Wuhan Shi: Zhongguo di zhi da xue chu ban she, 2000.
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Niujin gao ji Ying Ying Ying Han shuang jie ci dian: Oxford advanced learner's dictionary of current English. Wyd. 6. Taibe Shi: Taiwan dong hua shu ju, 2002.
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Moreno, Fulgencio R. La cuestion monetaria en el Paraguay: Exposición del Ministro de Hacienda ... hecha en defensa de sus proyectos en la hon. Cámara de Diputados. Asunción, Paraguay: Clásicos Colorados, 1985.
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Yuling, Zhao, i Sun Huimin, red. Han Ying Zhongguo bao kan xin ci yu 2000 diao: Chinese-English a dictionary of 2000 current Chinese newspaper expressions. Beijing: Xian dai chu ban she, 1990.
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S, Hornby A., i Cowie Anthony Paul, red. Oxford advanced learner's dictionary of current English with Chinese translation =: Niu jin xian dai gao ji ying han shuang jie ci dian. Wyd. 3. [Oxford]: Oxford University Press, 1988.
Znajdź pełny tekst źródłaCzęści książek na temat "HCN current"
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Stanojevic, Mateusz-Milan, i Renata Geld. "New current relevance in Croatian". W Human Cognitive Processing, 159–80. Amsterdam: John Benjamins Publishing Company, 2011. http://dx.doi.org/10.1075/hcp.29.11sta.
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Button, Graham, i Wes Sharrock. "Current Status". W Studies of Work and the Workplace in HCI, 89–90. Cham: Springer International Publishing, 2009. http://dx.doi.org/10.1007/978-3-031-02186-2_8.
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Aravalli, Rajagopal N., i Clifford J. Steer. "Current Diagnosis and Treatment Options for HCC". W Hepatocellular Carcinoma, 7–13. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09414-4_3.
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Rashed, Wafaa M. "Current HCC Clinical and Research in Egypt". W Liver Cancer in the Middle East, 313–21. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78737-0_19.
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Bošanský, Miroslav, František Tóth, Ladislav Gulan, Juraj Rusnák i Adam Furstenzeller. "Scuffing Resistance of 16MnCr5 HCR TiAlCN-Coated Gears". W Current Methods of Construction Design, 445–52. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-33146-7_51.
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Tokumitsu, Yukio, i Hiroaki Nagano. "Current HCC Staging Systems: Their Uses and Limitations". W Hepatocellular Carcinoma, 425–42. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-34214-6_28.
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Li, Sean, i Xiaojun Yuan. "A Review of the Current Intelligent Personal Agents". W HCI International 2018 – Posters' Extended Abstracts, 253–57. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92270-6_35.
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Lemon, Stanley M. "Hepatitis C: Current Status and Future Directions for Antiviral Therapy". W HCV and Related Liver Diseases, 1–26. Tokyo: Springer Japan, 1999. http://dx.doi.org/10.1007/978-4-431-68488-6_1.
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Hussain, Zahid, Wolfgang Slany i Andreas Holzinger. "Current State of Agile User-Centered Design: A Survey". W HCI and Usability for e-Inclusion, 416–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-10308-7_30.
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Decker, Thomas, Ralf Gross, Alexander Koebler, Michael Lebacher, Ronald Schnitzer i Stefan H. Weber. "The Thousand Faces of Explainable AI Along the Machine Learning Life Cycle: Industrial Reality and Current State of Research". W Artificial Intelligence in HCI, 184–208. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-35891-3_13.
Pełny tekst źródłaStreszczenia konferencji na temat "HCN current"
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Kretschmann, M., Chr Barczus i V. Scherer. "Combustion Tests on a Blend of Liquid Refinery Residues and Coal: CFBC Operation Behaviour and Emissions Characteristics With Special Emphasis on the Intermediate Species CxHy, HCN and NH3". W 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78103.
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Investigations on the combustion of a blend of liquid refinery residues and a hard coal are presented in the current paper. The experiments were done in an atmospheric circulating fluidized bed combustor (CFBC) with a thermal capacity of 100 kW. The operation behaviour and pollutant formation characteristics are determined using axial profile measurements at 19 different ports along the combustion chamber. The measurement campaign included the variation of the primary to secondary air ratio, the global air to fuel ratio, the residence time in the primary zone, the overall temperature of the combustion chamber and the Ca/S ratio. The current paper concentrates on results obtained at primary air ratio of 0.65, an overall air ratio of 1.1, a mean combustion temperature of 850°C and a Ca/S-ratio of 0. Measurement of the flue gas components O2, CxHy, CO, CO2, H2, NOx, N2O, NH3 and SO2 are made by standard gas analysing techniques. In order to detect the specific hydrocarbon species produced and oxidized during the combustion process a Fourier Transformation Infrared Spectrometer (FTIR) extends the existing gas analysis system. The gas species measured by FTIR-Spectroscopy are CH4, C2H2, C2H4, C2H6, C3H6 and C3H8. Also the important precursors for the NOx-Formation HCN and NH3 are examined with the FTIR-Spectrometer in the primary and secondary zone. The current experiments are compared with results obtained by burning liquid refinery residues only, with special regard to the consumption of the nitrogenous intermediates HCN and NH3.
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Bolelli, G., V. Cannillo, L. Lusvarghi, E. Soragni, A. Loreto i T. Valente. "A Comprehensive Characterization of Industrially Manufactured Hard Chrome Platings and of Thermally Sprayed Alternatives". W ITSC2005, redaktor E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p1456.
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Abstract HVOF-sprayed coatings (WC-17Co, WC-10Co-4Cr, Co-28Mo-17Cr-3Si) have been compared with various kinds of industrially manufactured hard chrome coatings (HCC), whose substrate preparation, deposition process, post deposition treatments greatly affect their characteristics. Microstructure, micromechanical properties, tribological behaviour and corrosion resistance (electrochemical polarization tests and Corrodkote test) have been studied. HVOF-sprayed cermets are harder but less tough than HCC, Co-28Mo-17Cr-3Si are less hard than HCC. Splats detachment causes a comparable or higher mass loss in three-body abrasion than HCC coatings. Forming a uniform surface film, cermet coatings definitely overcome HCC in two-body sliding, while Co-28Mo-17Cr-3Si has insufficient hardness to display good sliding wear resistance. HVOF coatings show no passivation in corrosive media but cermets posses more noble corrosion potentials than HCC, and undergo generalized corrosion in HNO3 and HCl, with similar corrosion current densities (IC). HCC passivate and resist well in HNO3 0.1N, but undergo pitting corrosion in 0.1N HCl. Definitely different EC and IC are recorded for various HCC in HCl. HVOF-sprayed cermet coatings show lower IC in 0.1N HCl solution than several kinds of HCC. No visible damage occurs on HVOF-sprayed coatings after the Corrodkote test, while non de-hydrogenated HCC suffered pitting corrosion.
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Som, Sibendu, Anita I. Ramirez i Suresh Aggarwal. "Emission Characteristics of Syngas Flames". W ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14553.
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Synthesis gas or "Syngas" is being recognized as a viable energy source worldwide, particularly for stationary power generation due to its wide flexibility in fuel sources and superior pollutants characteristics. Although its composition may vary significantly, it generally contains CO and H2 as the dominant fuel components with varying amount of methane and diluents. There are, however, gaps in the fundamental understanding of syngas combustion and emissions, as most previous research has focused on flames burning individual fuel components such as H2 and CH4, rather than syngas mixtures. To ensure the environmental feasibility of syngas, the harmful emission, especially NOx, must comply with current and future regulations. In addition, the combustion of syngas occurs at elevated pressures and inlet temperatures. Most published research has considered the combustion of syngas constituents at atmospheric conditions. This paper presents a numerical investigation to gain fundamental understanding of combustion and emission characteristics of syngas with varying composition, pressure and inlet temperatures. Two representative syngas fuel mixtures, 50% H2/50% CO and 5% H2 / 95% CO (% vol.), are chosen based on fuel composition data from multiple power generation plants worldwide. Three detailed chemical kinetic models are used namely, GRI 3.0, Davis and Dryer mechanisms. Results indicate that for both representative mixtures an increase in reactant temperature leads to a significant increase in NOx due to increase in flame temperature caused by an increase in inlet temperature. As the pressure is increased from 1 to 6 atm, the peak NO increases rapidly, and then becomes nearly independent of pressure. This can be attributed to a similar trend in radical species responsible for NO production such as HCN and OH which both show the most significant increase at low pressures. The emission index for these flames is also found to follow a similar behavior with pressure.
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Abirami, T., K. Lalitha, P. Jayadharshini i T. Madhuvanthi. "Future: HCI in public conveyances". W PROCEEDINGS OF THE 4TH NATIONAL CONFERENCE ON CURRENT AND EMERGING PROCESS TECHNOLOGIES E-CONCEPT-2021. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0069393.
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Bhavsar, Vrajesh. "Current trends for hardware and software developers". W 2015 IEEE Hot Chips 27 Symposium (HCS). IEEE, 2015. http://dx.doi.org/10.1109/hotchips.2015.7477324.
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Nomura, Risa, Norihiko Iki, Osamu Kurata, Masako Kawabata, Atsushi Tsutsumi, Eiichi Koda i Hirohide Furutani. "System Analysis of IGFC With Exergy Recuperation Utilizing Low-Grade Coal". W ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46282.
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Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC) is expected to be the most efficient power generation system in coal fired power generation systems [1,2]. The Japanese project of the Strategic Technical Platform for Clean Coal Technology (STEP-CCT) aims a target efficiency of 65% (HHV) with exergy recuperation. We have been analyzing the processes of the exergy recuperated Integrated Coal Gasification Combined Cycle (IGCC) and the Advanced IGCC (A-IGCC) [3] which is expected to be realized in 2040. Previous studies have indicated a limitation of the quantity of high temperature steam in the case of auto-thermal reactions with the fluidized bed coal gasifier in the A-IGCC, in particular for TIT 1500 °C class gas turbine. The Advanced IGFC (A-IGFC) system can reduce the exergy loss resulting from combustion, and its ‘exergy recuperation’ is appealing. The waste heat exhausted from the fuel cells is recycled to the gasifier for steam reforming in an endothermic reaction with a low exergy loss and a high cold gas efficiency. Our current study focuses on the optimization of the unit configurations of the A-IGFC including gasifier, compressor, solid oxide fuel cell (SOFC), combustor, gas turbine, heat recovery steam generator (HRSG), and steam turbine. The process simulator HYSYS®.Plant (Aspen technology Inc.) is employed in order to express the gasifier, the SOFC and the other units. The optimum construction over the whole system by numerical simulation was examined for higher energy utilization efficiency. Under ideal conditions using bituminous coal, we verified the power generation efficiency to be 64.5% (HHV). However, utilizing low-grade coals, i.e., lignite and sub-bituminous coal, is deemed an important future energy resource to compensate for a decreasing supply of good-quality bituminous coal. For these low-grade coals, the power generation efficiency was as high as 53.6% (HHV) under the following conditions: Gasifier inlet: coal 23.6 Kg/s (667 MJ/s), steam 16.44 kg/s; Reactor reforming gas: 30.0, 8.7, 2.0, 0.8, 0.3, 0.05, 0.24, 0.14, 0.1 and 5.5 kg/s for CO, CO2, H2, CH4, C2H4, C2H6, C3H6, HCN, N2 and H2O respectively. The projected power outputs with this system were, SOFC: 214 MW; Gas turbine: 318 MW; Steam turbine: 86 MW.
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Yuan Lin. "Multithreaded programming challenges, current practice, and languages/tools support". W 2006 IEEE Hot Chips 18 Symposium (HCS). IEEE, 2006. http://dx.doi.org/10.1109/hotchips.2006.7477737.
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Plotnikova, T. V., G. Yu Ishmuratov, V. Ya Ismailov, M. P. Yakovleva i L. R. Garigullina. "Biological system for decreasing population of cotton bollworm Helicoverpa armigera Hbn. in tobacco agrocenosis". W CURRENT STATE, PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF AGRARIAN SCIENCE. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2019. http://dx.doi.org/10.33952/09.09.2019.43.
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Bykovskaya, A. V., i L. I. Trepashko. "Optimization of the application of the insecticides for corn protection against Ostrinia nubilalis Hbn. in Belarus". W CURRENT STATE, PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF AGRARIAN SCIENCE. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2019. http://dx.doi.org/10.33952/09.09.2019.06.
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Xanthidis, Dimitrios, Faisal Alsuwaidi, Mohammed Al Ali, Abduljalil Alolama i Mohammed Albaloushi. "Information Privacy and Emerging Technologies in the U.A.E.: Current standing and research directions". W 2019 Sixth HCT Information Technology Trends (ITT). IEEE, 2019. http://dx.doi.org/10.1109/itt48889.2019.9075076.
Pełny tekst źródłaRaporty organizacyjne na temat "HCN current"
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McKinnon, Mark, Sean DeCrane i Steve Kerber. Four Firefighters Injured in Lithium-Ion Battery Energy Storage System Explosion -- Arizona. UL Firefighter Safety Research Institute, lipiec 2020. http://dx.doi.org/10.54206/102376/tehs4612.
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On April 19, 2019, one male career Fire Captain, one male career Fire Engineer, and two male career Firefighters received serious injuries as a result of cascading thermal runaway within a 2.16 MWh lithium-ion battery energy storage system (ESS) that led to a deflagration event. The smoke detector in the ESS signaled an alarm condition at approximately 16:55 hours and discharged a total flooding clean agent suppressant (Novec 1230). The injured firefighters were members of a hazardous materials (HAZMAT) team that arrived on the scene at approximately 18:28 hours. The HAZMAT team noted low-lying white clouds of a gas/vapor mixture issuing from the structure and nearby components and drifting through the desert. The team defined a hot zone and made several entries into the hot zone to conduct 360-degree size-ups around the ESS using multi-gas meters, colorimetric tubes, and thermal imaging cameras (TICs). The team detected dangerously elevated levels of hydrogen cyanide (HCN) and carbon monoxide (CO) during each entry. The team continued to monitor the ESS and noted the white gas/vapor mixture stopped flowing out of the container at approximately 19:50 hours. The HAZMAT leadership developed an incident action plan with input from a group of senior fire officers and information about the ESS provided by representatives from the companies that owned, designed, and maintained the ESS. The HAZMAT team made a final entry into the hot zone and found that HCN and CO concentrations in the vicinity of the ESS were below an acceptable threshold. In following with the incident action plan, the team opened the door to the ESS at approximately 20:01 hours. A deflagration event was observed by the firefighters outside the hot zone at approximately 20:04 hours. All HAZMAT team members received serious injuries in the deflagration and were quickly transported to nearby hospitals. Note: The lithium-ion battery ESS involved in this incident was commissioned prior to release of a first draft of the current consensus standard on ESS installations, NFPA 855 [1]; the design of the ESS complied with the pertinent codes and standards active at the time of its commissioning.
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Seidl, P. A., D. Baca, F. M. Bieniosek, B. Bukh, C. M. Celata, A. Coorey, C. Dugan i in. Progress in the high current experiment (HCX) February-July 2002. Office of Scientific and Technical Information (OSTI), wrzesień 2002. http://dx.doi.org/10.2172/803867.
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Lewis, Erin, Victoria Cohen, Charlotte Evans i Iulia Gherman. Salmonella risk profile of UK-produced hen shell eggs. Food Standards Agency, lipiec 2023. http://dx.doi.org/10.46756/sci.fsa.rpp424.
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A previous risk assessment (Opens in a new window) from the Advisory Committee on the Microbiological Safety of Food (ACMSF) in 2016 concluded that due to the significant reduction in the risk from Salmonella in UK-produced hen shell eggs produced under a recognised farm assurance scheme (Lion Code or equivalent), the risk to consumers from eggs produced under these schemes was ‘very low’. This risk assessment led the FSA and FSS to update their consumer advice on the consumption of eggs in 2017, stating that vulnerable groups could consume raw or runny eggs produced within an assurance scheme. This risk profile will examine the current situation of Salmonella in UK-produced table eggs, and the factors that may influence the current risk of Salmonella in UK-produced eggs and highlight any that have changed since the risk assessment provided by the ACMSF in 2016.
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Kalman, Joseph, i Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, lipiec 2022. http://dx.doi.org/10.31979/mti.2021.2041.
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The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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Kalman, Joseph, i Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, lipiec 2022. http://dx.doi.org/10.31979/mti.2022.2041.
Pełny tekst źródłaStreszczenie:
The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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Or, Etti, David Galbraith i Anne Fennell. Exploring mechanisms involved in grape bud dormancy: Large-scale analysis of expression reprogramming following controlled dormancy induction and dormancy release. United States Department of Agriculture, grudzień 2002. http://dx.doi.org/10.32747/2002.7587232.bard.
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The timing of dormancy induction and release is very important to the economic production of table grape. Advances in manipulation of dormancy induction and dormancy release are dependent on the establishment of a comprehensive understanding of biological mechanisms involved in bud dormancy. To gain insight into these mechanisms we initiated the research that had two main objectives: A. Analyzing the expression profiles of large subsets of genes, following controlled dormancy induction and dormancy release, and assessing the role of known metabolic pathways, known regulatory genes and novel sequences involved in these processes B. Comparing expression profiles following the perception of various artificial as well as natural signals known to induce dormancy release, and searching for gene showing similar expression patterns, as candidates for further study of pathways having potential to play a central role in dormancy release. We first created targeted EST collections from V. vinifera and V. riparia mature buds. Clones were randomly selected from cDNA libraries prepared following controlled dormancy release and controlled dormancy induction and from respective controls. The entire collection (7920 vinifera and 1194 riparia clones) was sequenced and subjected to bioinformatics analysis, including clustering, annotations and GO classifications. PCR products from the entire collection were used for printing of cDNA microarrays. Bud tissue in general, and the dormant bud in particular, are under-represented within the grape EST database. Accordingly, 59% of the our vinifera EST collection, composed of 5516 unigenes, are not included within the current Vitis TIGR collection and about 22% of these transcripts bear no resemblance to any known plant transcript, corroborating the current need for our targeted EST collection and the bud specific cDNA array. Analysis of the V. riparia sequences yielded 814 unigenes, of which 140 are unique (keilin et al., manuscript, Appendix B). Results from computational expression profiling of the vinifera collection suggest that oxidative stress, calcium signaling, intracellular vesicle trafficking and anaerobic mode of carbohydrate metabolism play a role in the regulation and execution of grape-bud dormancy release. A comprehensive analysis confirmed the induction of transcription from several calcium–signaling related genes following HC treatment, and detected an inhibiting effect of calcium channel blocker and calcium chelator on HC-induced and chilling-induced bud break. It also detected the existence of HC-induced and calcium dependent protein phosphorylation activity. These data suggest, for the first time, that calcium signaling is involved in the mechanism of dormancy release (Pang et al., in preparation). We compared the effects of heat shock (HS) to those detected in buds following HC application and found that HS lead to earlier and higher bud break. We also demonstrated similar temporary reduction in catalase expression and temporary induction of ascorbate peroxidase, glutathione reductase, thioredoxin and glutathione S transferase expression following both treatments. These findings further support the assumption that temporary oxidative stress is part of the mechanism leading to bud break. The temporary induction of sucrose syntase, pyruvate decarboxylase and alcohol dehydrogenase indicate that temporary respiratory stress is developed and suggest that mitochondrial function may be of central importance for that mechanism. These finding, suggesting triggering of identical mechanisms by HS and HC, justified the comparison of expression profiles of HC and HS treated buds, as a tool for the identification of pathways with a central role in dormancy release (Halaly et al., in preparation). RNA samples from buds treated with HS, HC and water were hybridized with the cDNA arrays in an interconnected loop design. Differentially expressed genes from the were selected using R-language package from Bioconductor project called LIMMA and clones showing a significant change following both HS and HC treatments, compared to control, were selected for further analysis. A total of 1541 clones show significant induction, of which 37% have no hit or unknown function and the rest represent 661 genes with identified function. Similarly, out of 1452 clones showing significant reduction, only 53% of the clones have identified function and they represent 573 genes. The 661 induced genes are involved in 445 different molecular functions. About 90% of those functions were classified to 20 categories based on careful survey of the literature. Among other things, it appears that carbohydrate metabolism and mitochondrial function may be of central importance in the mechanism of dormancy release and studies in this direction are ongoing. Analysis of the reduced function is ongoing (Appendix A). A second set of hybridizations was carried out with RNA samples from buds exposed to short photoperiod, leading to induction of bud dormancy, and long photoperiod treatment, as control. Analysis indicated that 42 genes were significant difference between LD and SD and 11 of these were unique.
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Qamhia, Issam, i Erol Tutumluer. Evaluation of Geosynthetics Use in Pavement Foundation Layers and Their Effects on Design Methods. Illinois Center for Transportation, sierpień 2021. http://dx.doi.org/10.36501/0197-9191/21-025.
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This report presents findings of a research effort aimed at reviewing and updating existing Illinois Department of Transportation (IDOT) specifications and manuals regarding the use of geosynthetic materials in pavements. The project consisted of three tasks: evaluate current IDOT practice related to the use of geosynthetics; review research and state of the practice on geosynthetics applications, available products, design methods, and specifications; and propose recommendations for geosynthetic solutions in pavements to modernize IDOT’s practices and manuals. The review of IDOT specifications revealed that geotextiles are the most used geosynthetic product in Illinois, followed by geogrids. Several of IDOT’s manuals have comprehensive guidelines to properly design and construct pavements with geosynthetics, but several knowledge gaps and potential areas for modernization and adoption of new specifications still exist. Based on the review of the available design methods and the most relevant geosynthetic properties and characterization methods linked to field performance, several updates to IDOT’s practice were proposed. Areas of improvement are listed as follows. First, establish proper mechanisms for using geogrids, geocells, and geotextiles in subgrade restraint and base stabilization applications. This includes using shear wave transducers, i.e., bender elements, to quantify local stiffness enhancements and adopting the Giroud and Han design method for subgrade restraint applications. Second, update IDOT’s Subgrade Stability Manual to include property requirements for geogrids, geotextiles, and geocells suitable for subgrade restraint applications. Third, establish proper standards on stabilization, separation, and pumping resistance for geotextiles by incorporating recent research findings on geotextile clogging and permeability criteria. Fourth, promote the use of modern geosynthetic products, such as geotextiles with enhanced lateral drainage, and fifth, elaborate on proper methods for construction/quality control measures for pavements with geosynthetics.
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Ruiz, Susana. ¿Quién paga la cuenta? Gravar la riqueza para enfrentar la crisis de la COVID-19 en América Latina y el Caribe. Oxfam, lipiec 2020. http://dx.doi.org/10.21201/2020.6317.
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Las previsiones de retroceso económico y social en América Latina y el Caribe son alarmantes. La COVID-19 golpea con fuerza la región marcada que tendrá que afrontar una contracción del 9,4%, una de las más severas en todo el planeta. La desigualdad, la informalidad y la insuficiente dotación sanitaria lastran las posibilidades de hacer frente a la pandemia. Pero son los más vulnerables quienes asumen el costo, hasta 52 millones de personas que podrían caer en la pobreza y 40 millones podrían perder sus empleos, un retroceso de 15 años para la región. Pero la COVID-19 no afecta a todos por igual, una élite se mantiene inmune al contagio de la crisis económica. Desde el principio de los confinamientos, hay 8 nuevos milmillonarios en América Latina y el Caribe, personas con un patrimonio superior a los mil millones de dólares. Las personas más ricas han aumentado su fortuna en US$ 48 200 millones desde marzo 2020, lo que equivale a un tercio del total de los paquetes de estímulo de todos los países de la región. Para hacer frente a esta crisis tan profunda, Oxfam propone una serie de reformas que recaigan sobre quienes más tienen y menos han sufrido la pandemia. Entre otros un impuesto sobre el patrimonio neto de las personas más ricas con el que se podría recaudar al menos US$ 14 260 millones, 50 veces más de lo que ahora se estaría recaudando sobre esta élite de grandes fortunas. In the context of the COVID-19 pandemic, forecasts for economic and social decline in Latin America and the Caribbean are alarming. The region will face a 9.4% contraction in its economy, among the most severe in the world. Coping with the pandemic is hindered by inequality, weak and insufficient social protection and limited public health capabilities. Up to 52 million people could fall into poverty and 40 million could lose their jobs – a 15-year setback for the region. Yet, an elite remains ‘immune’ to the contagion of the economic crisis. Since the beginning of the pandemic, there have been 8 new billionaires in LAC: 1 every 2 weeks since the lockdowns began. The richest people have increased their fortune by $48.2bn since March 2020, equivalent to a third of the total stimulus packages of all countries in the region. In this paper, Oxfam proposes a series of reforms targeting those who have being less affected by the pandemic. They include a net wealth tax that could potentially generate $14.3bn, 50 times more than billionaires in the region pay now in theory, under current tax systems.
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Kudin, Roman, Prabhat Chand i Anura Bakmeedeniya. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive. Unitec ePress, sierpień 2020. http://dx.doi.org/10.34074/rsrp.083.
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This research has been commissioned by Eco Fuel Global Limited, a New Zealand-based company, to further evaluate the effects of their fuel-additive product on the tailpipe exhaust emissions of petrol cars. At the time this research was conducted (end of 2018), the product was still in development and had not been released to the market. Prior to the testing in this research, an initial pilot test was done for the same product on a single car (Nissan Pulsar 1998), which showed favourable results, with a reduction in hydrocarbons and oxides of nitrogen at the tailpipe by more than 70%. The current research included five test cars, all running on RON 95 fuel, with the years of manufacture ranging between 1994 and 2006, and the odometer readings between 112,004 km and 264,001 km. The effects of the fuel-additive product were assessed by comparing the emissions from a car running on standard fuel with the emissions from the same car after it completed a road run (250±20 km) on the additive-treated fuel. The exhaust emissions were measured using the AVL series 4000 Emission Tester, which analyses five components: carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOX), hydrocarbons (HC) and oxygen (O2). The most noticeable outcome of using the fuel-additive product was the reduction in the concentration of oxides of nitrogen in the tailpipe exhaust (by up to 27.7%), when compared with the same cars running on standard fuel. In addition, the results showed a decrease in residual oxygen concentration, which normally indicates more complete utilisation of O2 as an oxidising agent. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive Dr Roman Kudin, Prabhat Chand and Anura Bakmeedeniya 2 The changes for other emission parameters were either relatively small (below 1%) or were not statistically significant. The application of such fuel-additive products could be beneficial for mitigating nitrogen oxides exhaust emissions from petrol vehicles in countries with ageing car fleets. These include New Zealand, which has a relatively high proportion of old cars in use, with no government-run scrappage scheme, and without a mandatory objective emissions testing.
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Uni, Zehava, i Peter Ferket. Enhancement of development of broilers and poults by in ovo feeding. United States Department of Agriculture, maj 2006. http://dx.doi.org/10.32747/2006.7695878.bard.
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The specific objectives of this research were the study of the physical and nutritional properties of the In Ovo Feeding (IOF) solution (i.e. theosmostic properties and the carbohydrate: protein ratio composition). Then, using the optimal solution for determining its effect on hatchability, early nutritional status and intestinal development of broilers and turkey during the last quarter of incubation through to 7 days post-hatch (i.e. pre-post hatch period) by using molecular, biochemical and histological tools. The objective for the last research phase was the determination of the effect of in ovo feeding on growth performance and economically valuable production traits of broiler and turkey flocks reared under practical commercial conditions. The few days before- and- after hatch is a critical period for the development and survival of commercial broilers and turkeys. During this period chicks make the metabolic and physiological transition from egg nutriture (i.e. yolk) to exogenous feed. Late-term embryos and hatchlings may suffer a low glycogen status, especially when oxygen availability to the embryo is limited by low egg conductance or poor incubator ventilation. Much of the glycogen reserve in the late-term chicken embryo is utilized for hatching. Subsequently, the chick must rebuild that glycogen reserve by gluconeogenesis from body protein (mostly from the breast muscle) to support post-hatch thermoregulation and survival until the chicks are able to consume and utilize dietary nutrients. Immediately post-hatch, the chick draws from its limited body reserves and undergoes rapid physical and functional development of the gastrointestinal tract (GIT) in order to digest feed and assimilate nutrients. Because the intestine is the nutrient primary supply organ, the sooner it achieves this functional capacity, the sooner the young bird can utilize dietary nutrients and efficiently grow at its genetic potential and resist infectious and metabolic disease. Feeding the embryo when they consume the amniotic fluid (IOF idea and method) showed accelerated enteric development and elevated capacity to digest nutrients. By injecting a feeding solution into the embryonic amnion, the embryo naturally consume supplemental nutrients orally before hatching. This stimulates intestinal development to start earlier as was exhibited by elevated gene expression of several functional genes (brush border enzymes an transporters , elvated surface area, elevated mucin production . Moreover, supplying supplemental nutrients at a critical developmental stage by this in ovo feeding technology improves the hatchling’s nutritional status. In comparison to controls, administration of 1 ml of in ovo feeding solution, containing dextrin, maltose, sucrose and amino acids, into the amnion of the broiler embryo increased dramatically total liver glycogen in broilers and in turkeys in the pre-hatch period. In addition, an elevated relative breast muscle size (% of broiler BW) was observed in IOF chicks to be 6.5% greater at hatch and 7 days post-hatch in comparison to controls. Experiment have shown that IOF broilers and turkeys increased hatchling weights by 3% to 7% (P<0.05) over non injected controls. These responses depend upon the strain, the breeder hen age and in ovo feed composition. The weight advantage observed during the first week after hatch was found to be sustained at least through 35 days of age. Currently, research is done in order to adopt the knowledge for commercial practice.