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1
Baek, Jang-Woon, Chang-Su Jang e Young-Jun Park. "A Methodology for the Zoning Danger Region in Small Arm Firing Range Using Aerial Photogrammetry with Drone". Advances in Civil Engineering 2020 (16 giugno 2020): 1–12. http://dx.doi.org/10.1155/2020/8864409.
Testo completoAbstract (sommario):
During firing exercises in the military forces, safety accidents have occurred and caused nonbattle loss of human lives. Despite huge impact of the safety accidents in firing ranges on the military forces and civilians, the preventive measures have been limited and inflexible. In this study, to decrease the accident rate in small arm firing ranges, a methodology was presented to determine danger zones in firing ranges that resulted from direct bullets or ricochets during firing exercises. On the basis of ballistic theory and the actual terrain data surveyed by a drone, the danger zone of OO Firing Range was identified by schematizing the trajectories of the direct bullets and ricochets. The Monte Carlo simulation (MCS) with the accuracy of the small arm on the terrain data showed that the danger zone of the current firing range was limited due to topographic advantages. However, when human errors were included in the MCS, the danger zones were significantly enlarged. The methodology of the present study can provide a safety check-up model that identifies danger zones in the firing ranges used by the Army.
2
Stern, A. H. "Lead exposure in indoor firing ranges." American Journal of Public Health 80, n. 3 (marzo 1990): 353–54. http://dx.doi.org/10.2105/ajph.80.3.353-b.
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3
Svensson, Bengt-G�ran, Andrejs Sch�tz, Anita Nilsson e Staffan Skerfving. "Lead exposure in indoor firing ranges". International Archives of Occupational and Environmental Health 64, n. 4 (novembre 1992): 219–21. http://dx.doi.org/10.1007/bf00378278.
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4
Greenberg, Nili, Ron Frimer, Robert Meyer, Estella Derazne e Gabrial Chodick. "Lead Exposure in Military Outdoor Firing Ranges". Military Medicine 181, n. 9 (settembre 2016): 1121–26. http://dx.doi.org/10.7205/milmed-d-15-00454.
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Goldberg, Robert Leonard, Anthony M. Hicks, Lindy M. O??Leary e Stephanie London. "Lead Exposure at Uncovered Outdoor Firing Ranges". Journal of Occupational and Environmental Medicine 33, n. 6 (giugno 1991): 718–19. http://dx.doi.org/10.1097/00043764-199106000-00013.
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Robbins, Sarah K., Kenneth D. Blehm e Roy M. Buchan. "Controlling Airborne Lead in Indoor Firing Ranges". Applied Occupational and Environmental Hygiene 5, n. 7 (luglio 1990): 435–39. http://dx.doi.org/10.1080/1047322x.1990.10389671.
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7
Kardous, Chucri A., e William J. Murphy. "Noise control solutions for indoor firing ranges". Noise Control Engineering Journal 58, n. 4 (2010): 345. http://dx.doi.org/10.3397/1.3455050.
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Jackson, M. H., e K. R. Dell. "Personal exposures to lead in indoor firing ranges". International Journal of Environmental Health Research 2, n. 4 (dicembre 1992): 201–5. http://dx.doi.org/10.1080/09603129209356753.
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Bergiadis, Willaim L. "Acoustic treatments for indoor and outdoor firing ranges". Journal of the Acoustical Society of America 152, n. 4 (ottobre 2022): A160. http://dx.doi.org/10.1121/10.0015883.
Testo completoAbstract (sommario):
Small-caliber firearms can produce impulse noises that frequently exceed 150 dB peak sound pressure level (dB pSPL) and can approach 185 dB pSPL. These impulse noises can present a significant risk for noise-induced hearing loss for the unprotected ear and pose a risk for persons wearing hearing protection that is possibly poorly fitted or insufficient. For range safety officers and personnel who work in the firing range on a regular basis, the daily cumulative effects of noise exposure can lead to increased fatigue and stress. Acoustic treatments of the reflective surfaces can mitigate these health risks. This paper will review some community noise guidelines as well as health and safety regulations. As a manufacturer of acoustic range treatments, the Troy System materials will be reviewed with regards to their laboratory performance and their capabilities to reduce noise in various firing ranges. One aspect of performance that may be overlooked is the safety features of the materials which Troy Acoustics provides, such as flammability, ability to be cleaned, and the resistance to moisture and mold.
10
Kreeger, Lauren J., Arslaan Arshed e Katrina M. MacLeod. "Intrinsic firing properties in the avian auditory brain stem allow both integration and encoding of temporally modulated noisy inputs in vitro". Journal of Neurophysiology 108, n. 10 (15 novembre 2012): 2794–809. http://dx.doi.org/10.1152/jn.00092.2012.
Testo completoAbstract (sommario):
The intrinsic properties of tonically firing neurons in the cochlear nucleus contribute to representing average sound intensity by favoring synaptic integration across auditory nerve inputs, reducing phase locking to fine temporal acoustic structure and enhancing envelope locking. To determine whether tonically firing neurons of the avian cochlear nucleus angularis (NA) resemble ideal integrators, we investigated their firing responses to noisy current injections during whole cell patch-clamp recordings in brain slices. One subclass of neurons (36% of tonically firing neurons, mainly subtype tonic III) showed no significant changes in firing rate with noise fluctuations, acting like pure integrators. In contrast, many tonically firing neurons (>60%, mainly subtype tonic I or II) showed a robust sensitivity to noisy current fluctuations, increasing their firing rates with increased fluctuation amplitudes. For noise-sensitive tonic neurons, the firing rate vs. average current curves with noise had larger maximal firing rates, lower gains, and wider dynamic ranges compared with FI curves for current steps without noise. All NA neurons showed fluctuation-driven patterning of spikes with a high degree of temporal reliability and millisecond spike time precision. Single-spiking neurons in NA also responded to noisy currents with higher firing rates and reliable spike trains, although less precisely than nucleus magnocellularis neurons. Thus some NA neurons function as integrators by encoding average input levels over wide dynamic ranges regardless of current fluctuations, others detect the degree of coherence in the inputs, and most encode the temporal patterns contained in their inputs with a high degree of precision.
11
Jackson, M. H., e K. R. Dell. "The spatial distribution of lead in indoor firing ranges". International Journal of Environmental Health Research 2, n. 4 (dicembre 1992): 206–11. http://dx.doi.org/10.1080/09603129209356754.
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Braida, Washington, Christos Christodoulatos, Adebayo Ogundipe, Dimitris Dermatas e Gregory O’Connor. "Electrokinetic treatment of firing ranges containing tungsten-contaminated soils". Journal of Hazardous Materials 149, n. 3 (novembre 2007): 562–67. http://dx.doi.org/10.1016/j.jhazmat.2007.06.114.
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Park, Won-Ju, Suk-Ho Lee, Se-Ho Lee, Hye-Sik Yoon e Jai-Dong Moon. "Occupational Lead Exposure from Indoor Firing Ranges in Korea". Journal of Korean Medical Science 31, n. 4 (2016): 497. http://dx.doi.org/10.3346/jkms.2016.31.4.497.
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Zvîncu, N.-D., C.-E. Moldoveanu, A.-D. Mandache-Dodoiu, F.-M. Dîrloman e I. Vedinaș. "Research on small caliber weapons firing ranges security enhancement considering the projectile-obstacle impact". IOP Conference Series: Materials Science and Engineering 1182, n. 1 (1 ottobre 2021): 012086. http://dx.doi.org/10.1088/1757-899x/1182/1/012086.
Testo completoAbstract (sommario):
Abstract Weapons systems are used to gain a tactical, strategic, material or mental advantage over an adversary or enemy target. The modern weapons systems are designed to be technologically complex but practical for operator usage. The firing phenomenon consists of a multitude of mechanical and thermodynamic processes with the result being the movement of the projectile towards a chosen target. The projectile movement from the weapon to the point of impact defines its trajectory. Firing ranges are locations where military personnel is operating certain weapons systems in order to achieve specific results and certain levels of readiness. Due to increasing urbanisation of the areas adjacent to firing ranges, monitoring the projectile trajectory becomes mandatory in order to be able to provide a secure climate for both military personnel and civilians. It is the purpose of the author to provide the numerical simulation tool (a MATLAB application) which is useful for tracking the projectile trajectory from the muzzle of the weapon to the impacted obstacle. By computing the useful information obtained with the internal and external ballistics, the theoretical trajectory of a projectile can be calculated. In order to get the most accurate values, preliminary knowledge is needed. So by using appropriate tools and software, a projectile’s trajectory can be calculated if the correct values are provided (mass, diameter, initial angle, initial speed). The tool created has different weapons-ammunition specifications and initial conditions parameters loaded that can be combined with the existing drag laws known in ballistics (Siacci law, 1930 law or 1943 law) to describe the projectile movement in atmosphere. As obstacles are defined, similar to the ones existing in a firing range, the tool can assess where the impact occurred and is able to display necessary values (impact points coordinates, velocities, impact angles, etc) while also creating 3D and 2D visualisations on the integrated graphic area. This way, the tool can be used to create impact assessments for specific weapons systems and decisions can be made to enhance the security of the firing range and the firing safety. Three different firing range configurations are considered for comparison when using certain small caliber weapons used by NATO countries.
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Chover, Joshua. "Neural Correlation via Random Connections". Neural Computation 8, n. 8 (novembre 1996): 1711–29. http://dx.doi.org/10.1162/neco.1996.8.8.1711.
Testo completoAbstract (sommario):
A simple neural network is studied, which has sparse, random, plastic, excitatory connections and also feedback loops between sensory cells and correlator cells. Time is limited to several discrete instants, where firing is synchronous. For parameter values within biological ranges, the system exhibits a capacity for associative recall, with a controlled amount of extraneous firing, following Hebb-like synaptic changes.
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Kudriashov, V., D. Lytovchenko, V. Voinov, L. Khrol e V. Kutsenko. "FIRING EFFICIENCY OF ANTI-AIRCRAFT MISSILE COMPLEX “STRILA-10” IN TARGET DETECTION THROUGH THE OPTICAL VISOR AND AUTOMATED TARGET POINTER". Наукові праці Державного науково-дослідного інституту випробувань і сертифікації озброєння та військової техніки 18, n. 4 (1 dicembre 2023): 41–48. http://dx.doi.org/10.37701/dndivsovt.18.2023.06.
Testo completoAbstract (sommario):
When preparing for and conducting combat operations of the “SA-13 Gopher” anti-aircraft missile system, commanders and combat personnel of the system must know the missile firing efficiency indicators [1–4]. As an indicator of missile firing efficiency, the probability of hitting a target with one missile is usually used. Massive homing is carried out via the contrast channel or the infrared channel of the missile homing head. Under various conditions of use, it is necessary to evaluate the detection ranges that are realised and the probability of timely target detection, launch range and missile launch probability. It is also necessary to imagine the possible values of the inclined distances to the far edge of the kill zone of the complex. The probability of hitting a target with a single missile is affected by the geometric dimensions of the targets, their colour and contrast in the infrared wavelength range, the presence of target designation, meteorological range of visibility etc.
The task of determining the firing efficiency of the “SA-13 Gopher” anti-aircraft missile system when detecting targets through the optical sight and automated targeting is therefore relevant and important.
Research presented in the published [1–4; 12–13] do not allow determining the value of the probability of hitting different air targets in various conditions of the complex’s use. This literature provides only general approaches to solving this problem for typical conditions of use of an anti-aircraft missile system. A numerical modeling technique for determining the firing efficiency indicator in the form of values of the probability of hitting targets by a missile has been developed. The modeling took into account the speed of the targets, their plane in the shooting picture, their radiating capabilities and meteorological visibility range, the quality of the combat work of the operators of the combat vehicle, the sun exposure and the closing angles of the combat vehicle. Found possible detection ranges and detection probabilities of a typical target and a small unmanned aerial vehicle (UAV). A high probability of the operator of a combat vehicle missing a typical target at low and medium flight altitudes was noted. Considered launch ranges of missiles that are implemented and the probability of launching a missile when targets are captured in the contrast and infrared channels of the homing head. The largest inclined ranges to the far boundary of the zone of damage of the complex were calculated. The values of the probability of hitting a typical target and UAV in various firing conditions are determined. Sufficient firing efficiency has been proven when capturing and launching a missile in the contrast guidance channel and firing at a typical target. A comparison of the contrast and infrared channels of the homing missile head when firing at UAVs was carried out. Analytical expressions for the calculation of missile firing efficiency indicators and corresponding graphic material are presented.
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Travé Allepuz, Esther. "Colour Transformation and Textural Change in Biotite: Some Remarks for the Interpretation of Firing Technology in Greyware Pottery Thin-Sections". Minerals 11, n. 4 (18 aprile 2021): 428. http://dx.doi.org/10.3390/min11040428.
Testo completoAbstract (sommario):
Firing is a crucial step in the production of pottery, as it irreversibly transforms the clay into ceramic. Clay sintering and subsequent vitrification occur during firing, together with other transformations undergone by specific minerals and rock inclusions according to their optical and physical properties, including their colour. Some of these are visible in thin-sections and might be interpreted as technological markers or contribute to the estimation of firing temperatures, although most of them are poorly documented. In this paper, we approach the transformations in colour, texture and optical properties that occurred in biotite inclusions from medieval greyware pottery. Our study considers a batch of 40 pottery samples from medieval Catalonia analysed by XRD. According to the estimated firing temperature ranges and atmospheres, we examined the behaviour of biotite at different temperature ranges from 700 °C to 1000 °C by means of optical microscopy, considering its size, shape and abundance, and compared these features to a wider assemblage of thin-sections from medieval earthenware. The results obtained are interesting, as they offer a valuable reference for petrographic studies on pottery. We discuss the potential of ceramic petrography as a way to perform more precise and refined sample selection for further analysis on archaeothermometry.
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Dortch, Mark S., Billy E. Johnson e Jeffrey A. Gerald. "Modeling Fate and Transport of Munitions Constituents on Firing Ranges". Soil and Sediment Contamination: An International Journal 22, n. 6 (18 agosto 2013): 667–88. http://dx.doi.org/10.1080/15320383.2013.756453.
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Murphy, William J., e Randy L. Tubbs. "Assessment of Noise Exposure for Indoor and Outdoor Firing Ranges". Journal of Occupational and Environmental Hygiene 4, n. 9 (23 luglio 2007): 688–97. http://dx.doi.org/10.1080/15459620701537390.
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Harish, Omri, e David Golomb. "Control of the Firing Patterns of Vibrissa Motoneurons by Modulatory and Phasic Synaptic Inputs: A Modeling Study". Journal of Neurophysiology 103, n. 5 (maggio 2010): 2684–99. http://dx.doi.org/10.1152/jn.01016.2009.
Testo completoAbstract (sommario):
Vibrissa motoneurons (vMNs) generate rhythmic firing that controls whisker movements, even without cortical, cerebellar, or sensory inputs. vMNs receive serotonergic modulation from brain stem areas, which mainly increases their persistent sodium conductance ( gNaP) and, possibly, phasic input from a putative central pattern generator (CPG). In response to serotonergic modulation or just-suprathreshold current steps, vMNs fire at low rates, below the firing frequency of exploratory whisking. In response to periodic inputs, vMNs exhibit nonlinear suprathreshold resonance in frequency ranges of exploratory whisking. To determine how firing patterns of vMNs are determined by their 1) intrinsic ionic conductances and 2) responses to periodic input from a putative CPG and to serotonergic modulation, we construct and analyze a single-compartment, conductance-based model of vMNs. Low firing rates are supported in extended regimes by adaptation currents and the minimal firing rate decreases with gNaP and increases with M-potassium and h-cation conductances. Suprathreshold resonance results from the locking properties of vMN firing to stimuli and from reduction of firing rates at low frequencies by slow M and afterhyperpolarization potassium conductances. h conductance only slightly affects the suprathreshold resonance. When a vMN is subjected to a small periodic CPG input, serotonergically induced gNaP elevation may transfer the system from quiescence to a firing state that is highly locked to the CPG input. Thus we conclude that for vMNs, the CPG controls firing frequency and phase and enables bursting, whereas serotonergic modulation controls transitions from quiescence to firing unless the CPG input is sufficiently strong.
21
Fayiga, Abioye O. "Remediation of inorganic and organic contaminants in military ranges". Environmental Chemistry 16, n. 2 (2019): 81. http://dx.doi.org/10.1071/en18196.
Testo completoAbstract (sommario):
Environmental contextContaminants occur in the soil and water associated with military ranges. This review article describes how the extent of contamination depends not only on the type of military range and its period of activity, but also on the chemistry of both the soil and the contaminant. A full understanding of the soil chemistry is necessary to develop effective remediation methods for the restoration of these impacted environments. AbstractThis review discusses the contaminants associated with military ranges and the approaches taken to remediate these sites. The type and extent of contamination depends on the type of range, period of activity, soil chemistry and contaminant chemistry. Small arms firing ranges typically have high concentrations of metals and metalloids whereas military ranges typically have high concentrations of perchlorates, white phosphorus, explosives and propellants. For explosives, higher concentrations are found in sites that have undergone a low order detonation than in sites with a high order detonation. Remediation technologies for small arms firing ranges include leaching and immobilisation whereas for military ranges, methods such as alkaline hydrolysis, photolysis, bioremediation and phytoremediation have been tested. A lot of work has been done to immobilise metals/metalloids using soil amendments, which show a high effectiveness in stabilising them. Some of these amendments, however, also mobilise other co-contaminants. More studies are needed to simultaneously immobilise all inorganic contaminants. Explosives can be transformed into simpler non-toxic forms by photolysis, bioremediation or phytodegradation. The introduction of bacteria transgenes into plants has been used to enhance uptake and degradation of explosives in transgenic plants. Adoption of appropriate remediation technologies in impacted military ranges will reduce contaminant levels and protect public health.
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i Gen�s, Carme Torras. "Pacemaker neuron model with plastic firing rate: Entrainment and learning ranges". Biological Cybernetics 52, n. 2 (giugno 1985): 79–91. http://dx.doi.org/10.1007/bf00363998.
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Wyszomirski, P., e K. Galos. "Polish clayey raw materials for the production of ceramic tiles". Clay Minerals 44, n. 4 (dicembre 2009): 497–509. http://dx.doi.org/10.1180/claymin.2009.044.4.497.
Testo completoAbstract (sommario):
AbstractDevelopment of the Polish ceramic industry over the last ten years has resulted in a sharp increase in demand for basic raw materials, especially for ceramic clays – both white- and light-firing as well as red-firing varieties. Polish sources of white-firing clays are rather scarce. Their production is based on Santonian sandy-clayey sediments of the North-Sudetic Trough (Lower Silesia, SW Poland). Light-firing varieties occur mainly in Lower Jurassic sediments on the northern margin of the Holy Cross Mountains (central Poland). Red-firing well-sintering clays of Triassic age are known in the northern margin of the Holy Cross Mountains as well as in the Cracow-Silesian Monocline.The white-firing Santonian clays contain mainly highly-ordered kaolinite (~50%) and quartz (~30%) with minor amounts of illite. Their grain-size median ranges between 1.9 and 2.5 μm. They show moderate plasticity (bending strength after drying at 1.7–1.9 MPa) and weak sinterability (water absorption after firing ~12%), but greater lightness after firing (L parameter ~86%). The light-firing Jurassic clays are kaolinitic-illitic in character, with a variable content of quartz. Kaolinite is represented by the low-ordered variety. The grain-size median is also variable, ranging between 1.1 and 3.4 μm. They show good plasticity (bending strength after drying 2.6–2.8 MPa), good or very good sinterability (water absorption after firing <6%) but moderate lightness (L ~79%).Triassic red clays are highly polymineralic, with illite, kaolinite, smectite, chlorite and mixed-layered minerals occurring in variable amounts. Their specific features are: large hematite content (5–12%), commonly small CaO content (<0.5 wt.%) and an extremely small organic matter content (⩽0.1 wt.%). Their grain-size median usually varies between 2 and 3 mm. Using such clays, sintered ceramics (e.g. stoneware tiles) are obtained after firing in the temperature range 1150–1200ºC.
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Tanbar, Fefria, Nur Cahyo e Muhammad Zahoor. "Characteristics of Co-firing Solid Recovered Fuel with sub-bituminous Coal on Pulverized Coal Boiler Power Plant 300 MWe". E3S Web of Conferences 432 (2023): 00009. http://dx.doi.org/10.1051/e3sconf/202343200009.
Testo completoAbstract (sommario):
The biomass co-firing test was conducted at a pulverized coal power plant with a capacity of 300 MWe to determine the effect of cofiring on the operating parameters, such as Mill Outlet Temperature (MOT), Furnace Exit Gas Temperature (FEGT), Specific Fuel Consumption (SFC) and environment. Biomass Solid Recovered Fuel (SRF) and coal was mixed in a stockpile with a composition of 5 % SRF and 95 % coal. Fuel mix was fed into the four operating bunker mills. The load stabilization process duration is 1 h after the biomass is fed to the boiler by keeping the loading constant at the maximum capacity rate. The data was recorded for 2 h with a retrieval interval of every 15 min. The results showed that the FEGT value during co-firing was 0.7 % lower than during coal firing. The mill outlet temperature ranges from 58 °C to 60 °C in both test conditions. NOx emissions increase by 10.1 %, and SO2 emissions increase by 5.5 % during co-firing than coal-firing conditions. There is no significant change in SFC where the value equals 0.54 kg kWh-1 on both tests.
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I Wayan Oka Prayasa, Agus Putu Abiyasa e I. Putu Angga Kristyawan. "Ceramic Firing Temperature Trajectory Monitoring System on IoT-Based Gas Furnace". Jurnal Nasional Pendidikan Teknik Informatika (JANAPATI) 12, n. 3 (31 dicembre 2023): 398–405. http://dx.doi.org/10.23887/janapati.v12i3.69708.
Testo completoAbstract (sommario):
This study introduces a novel system where a conventional ceramic furnace is upgraded with IoT capabilities, specifically utilizing NodeMCU and a thermocouple sensor. The integrated system enables real-time temperature monitoring, facilitating the correction of firing trajectory errors in the ceramic firing process. The sensors reading minimizes errors by detecting temperature changes with a maximum deviation of -2.5 °C and a minimum deviation of -1 °C. The average error ranges from 1.81% to 3.79%. The collected data is seamlessly transmitted to Google Spreadsheet for online monitoring. This comprehensive solution not only minimizes recording errors but also ensures the quality of final ceramic products by preventing issues such as cracks, breaks, black cores, and non-uniform sizes. The incorporation of NodeMCU, thermocouple sensors, and online monitoring represents a significant technological leap in optimizing ceramic firing processes for heightened precision and efficiency.
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Vancea, Cosmin, Giannin Mosoarca, Simona Popa, Mircea Dan e Sorina Boran. "New Glass Ceramic Materials Obtained from Cathode Ray Tubes Glass Wastes and Fly Ash". Sustainability 15, n. 4 (7 febbraio 2023): 3021. http://dx.doi.org/10.3390/su15043021.
Testo completoAbstract (sommario):
This paper presents an alternative way to recycle cathode ray tube glass waste, together with fly ash and kaolin, into new glass ceramic materials. The samples were obtained using three firing temperatures: 700, 800, and 900 °C. The effect of the fly ash/CRT waste ratio upon the materials’ firing shrinkage, apparent density, apparent and total porosity, chemical stability, and compression strength was investigated. The firing shrinkage used as a dimensional stability parameter, a firing shrinkage range between 2.19–8.18%, was positively influenced by the waste mix amount. The apparent density of the obtained materials is positively affected by the heat treatment temperature, rising from 2.09 to 2.93 (g·cm−3), while the apparent porosity decreases with the increase of the firing temperature from 6.08 to 2.24 %. All the studied glass ceramics show very good chemical stability and complete immobilization of the Pb2+ and Ba2+ ions in the glass ceramic matrix. The compression strength of the sintered materials ranges between 1.42–11.83 (N·mm−2), being positively influenced by the kaolin amount and negatively influenced by porosity. The obtained results confirm the viability of the proposed alternative to use CRT waste and fly ash together with kaolin to obtain glass ceramic materials that can be used for outdoor paving applications.
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Davis, Jeffrey L., Michael C. Brooks, Steven L. Larson, Catherine C. Nestler e Deborah R. Felt. "Lime Treatment of Explosives-Contaminated Soil from Munitions Plants and Firing Ranges". Soil and Sediment Contamination: An International Journal 15, n. 6 (dicembre 2006): 565–80. http://dx.doi.org/10.1080/15320380600959032.
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Landsberger, S., F. Iskander, S. Basunia, D. Barnes e M. Kaminski. "Lead and copper contamination of soil from industrial activities and firing ranges". Biological Trace Element Research 71-72, n. 1 (dicembre 1999): 387–96. http://dx.doi.org/10.1007/bf02784226.
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Jeridi, K., M. Hachani, W. Hajjaji, B. Moussi, M. Medhioub, A. López-Galindo, F. Kooli, F. Zargouni, J. Labrincha e F. Jamoussi. "Technological behaviour of some Tunisian clays prepared by dry ceramic processing". Clay Minerals 43, n. 3 (settembre 2008): 339–50. http://dx.doi.org/10.1180/claymin.2008.043.3.01.
Testo completoAbstract (sommario):
AbstractLower Cretaceous (AJO and AJR) and Oligocene clays (AS) from northern Tunisia were analysed to evaluate their possible use in the production of earthenware tiles by dry processing and fast double-firing. The Cretaceous clays are carbonate-rich (AJO = 20%, AJR = 12%) while the Oligocene ones are carbonate-free. This led to noticeable differences in firing behaviour (shrinkage, sintering rate and loss on ignition) and consequently in functional properties (water absorption, mechanical strength, porosity). The AJO firing shrinkage is very small, which makes this clay suitable for rapid firing. The clays are illite-kaolinite-rich but the AS sample is mostly smectitic (44%) and so is used (10 wt.% maximum) only to adjust the consistency of the powder during pressing. The average agglomerate size ranges from 100 to 350 μm and the distribution is suitable for easy pressing of powders without any special need for further adjustments. Characterization of fired products confirms the high potential of these clays since all properties fall within the ceramic International Standards (ISO). For both technical and economic reasons dry processing is recommended for production of earthenware tiles, in particular for countries in sunnier climates, where solar energy can be exploited for clay drying.
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Lee, Chi Youn, Hyun Soo Lee e Kyung Hyun Shin. "Effects of ZrO2 on Zinc Crystalline Glaze". Advanced Materials Research 716 (luglio 2013): 228–34. http://dx.doi.org/10.4028/www.scientific.net/amr.716.228.
Testo completoAbstract (sommario):
Zinc Crystal Glaze has its limits in practical use of commercial glaze due to the sensitive firing schedule. In order to overcome these limits, and to improve the practical usage, this study is aimed to develop a stable zinc crystalline glaze. This study altered the quantity of nuclear formation of zinc crystal glaze in order to control the willemite (Zn2SiO4) formation in the glaze. The addition of ZrO2 to zinc crystal glaze influences the quantity of nuclear formation and its preservation; thus ZrO2 was used to control the optimal firing temperature and the size of the crystal formation in the glaze to find a zinc crystal glaze capable of withstanding various ranges of temperatures.
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Li, Yunru, Monica A. Gorassini e David J. Bennett. "Role of Persistent Sodium and Calcium Currents in Motoneuron Firing and Spasticity in Chronic Spinal Rats". Journal of Neurophysiology 91, n. 2 (febbraio 2004): 767–83. http://dx.doi.org/10.1152/jn.00788.2003.
Testo completoAbstract (sommario):
After chronic spinal injury, motoneurons spontaneously develop two persistent inward currents (PICs): a TTX-sensitive persistent sodium current (sodium PIC) and a nimodipine-sensitive persistent calcium current (calcium PIC). In the present paper, we examined how these PICs contributed to motoneuron firing. Adult rats were spinalized at the S2 sacral level, and after 2 months intracellular recordings were made from sacrocaudal motoneurons in vitro. The PICs and repetitive firing were measured with slow triangular voltage and current ramps, respectively. The sodium PIC was examined after blocking the calcium PIC with nimodipine (20 μM; n = 12). It was always activated subthreshold, and during current ramps in nimodipine, it produced a sodium plateau that assisted in initiating and maintaining firing (self-sustained firing). The sodium PIC oscillated off and on during firing and helped initiate each spike, and near threshold this caused abnormally slow firing (2.82 ± 1.21 Hz). A low dose of TTX (0.5 μM) blocked the sodium PIC, sodium plateau, and very slow firing prior to affecting the spike itself. The calcium PIC was estimated as the current blocked by nimodipine or current remaining in TTX (2 μM; n = 13). In 59% of motoneurons, the calcium PIC was activated subthreshold to firing and produced a plateau that assisted in initiating and sustaining firing because nimodipine significantly increased the firing threshold current and decreased the self-sustained firing. In the remaining motoneurons (41%), the calcium PIC was activated suprathreshold to firing and during current ramps did not initially affect firing but eventually was activated and caused an acceleration in firing followed by self-sustained firing, which were blocked by nimodipine. The frequency-current ( F-I) slope was 3.0 ± 1.0 Hz/nA before the calcium PIC activation (primary range), 6.3 ± 3.6 Hz/nA during the calcium PIC onset (secondary range; acceleration), and 2.1 ± 1.3 Hz/nA with the calcium PIC steadily activated (tertiary range). Nimodipine eliminated the secondary and tertiary ranges, leaving a linear F-I slope of 3.7 ± 1.0 Hz/nA. A single low-threshold shock to the dorsal root evoked a many-second-long discharge, the counterpart of a muscle spasm in the awake chronic spinal rat. This long-lasting reflex was caused by the motoneuron PICs because when the activation of the voltage-dependent PICs was prevented by hyperpolarization, the same dorsal root stimulation only produced a brief excitatory postsynaptic potential (<1 s). Both the calcium and sodium PIC were involved because nimodipine only partly reduced the reflex and there remained very slow firing mediated by the sodium PIC.
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Rhode, W. S., e P. H. Smith. "Encoding timing and intensity in the ventral cochlear nucleus of the cat". Journal of Neurophysiology 56, n. 2 (1 agosto 1986): 261–86. http://dx.doi.org/10.1152/jn.1986.56.2.261.
Testo completoAbstract (sommario):
Physiological response properties of neurons in the ventral cochlear nucleus have a variety of features that are substantially different from the stereotypical auditory nerve responses that serve as the principal source of activation for these neurons. These emergent features are the result of the varying distribution of auditory nerve inputs on the soma and dendrites of the various cell types within the nucleus; the intrinsic membrane characteristics of the various cell types causing different responses to the same input in different cell types; and secondary excitatory and inhibitory inputs to different cell types. Well-isolated units were recorded with high-impedance glass microelectrodes, both intracellularly and extracellularly. Units were characterized by their temporal response to short tones, rate vs. intensity relation, and response areas. The principal response patterns were onset, chopper, and primary-like. Onset units are characterized by a well-timed first spike in response to tones at the characteristic frequency. For frequencies less than 1 kHz, onset units can entrain to the stimulus frequency with greater precision than their auditory nerve inputs. This implies that onset units receive converging inputs from a number of auditory nerve fibers. Onset units are divided into three subcategories, OC, OL, and OI. OC units have extraordinarily wide dynamic ranges and low-frequency selectivity. Some are capable of sustaining firing rates of 800 spikes/s at high intensities. They have the smallest standard deviation and coefficient of variation of the first spike latency of any cells in the cochlear nuclei. OC units are candidates for encoding intensity. OI and OL units differ from OC units in that they have dynamic ranges and frequency selectivity ranges much like those of auditory nerve fibers. They differ from one another in their steady-state firing rates; OI units fire mainly at the onset of a tone. OI units also differ from OL units in that they prefer frequency sweeps in the low to high direction. Primary-like-with-notch (PLN) units also respond to tones with a well-timed first spike. They differ from onset cells in that the onset peak is not always as precise as the spontaneous rate is higher. A comparison of spontaneous firing rate and saturation firing rate of PLN units with auditory nerve fibers suggest that PLN units receive one to four auditory nerve fiber inputs. Chopper units fire in a sustained regular manner when they are excited by sound.(ABSTRACT TRUNCATED AT 400 WORDS)
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Somogyi, Peter, Linda Katona, Thomas Klausberger, Bálint Lasztóczi e Tim J. Viney. "Temporal redistribution of inhibition over neuronal subcellular domains underlies state-dependent rhythmic change of excitability in the hippocampus". Philosophical Transactions of the Royal Society B: Biological Sciences 369, n. 1635 (5 febbraio 2014): 20120518. http://dx.doi.org/10.1098/rstb.2012.0518.
Testo completoAbstract (sommario):
The behaviour-contingent rhythmic synchronization of neuronal activity is reported by local field potential oscillations in the theta, gamma and sharp wave-related ripple (SWR) frequency ranges. In the hippocampus, pyramidal cell assemblies representing temporal sequences are coordinated by GABAergic interneurons selectively innervating specific postsynaptic domains, and discharging phase locked to network oscillations. We compare the cellular network dynamics in the CA1 and CA3 areas recorded with or without anaesthesia. All parts of pyramidal cells, except the axon initial segment, receive GABA from multiple interneuron types, each with distinct firing dynamics. The axon initial segment is exclusively innervated by axo-axonic cells, preferentially firing after the peak of the pyramidal layer theta cycle, when pyramidal cells are least active. Axo-axonic cells are inhibited during SWRs, when many pyramidal cells fire synchronously. This dual inverse correlation demonstrates the key inhibitory role of axo-axonic cells. Parvalbumin-expressing basket cells fire phase locked to field gamma activity in both CA1 and CA3, and also strongly increase firing during SWRs, together with dendrite-innervating bistratified cells, phasing pyramidal cell discharge. Subcellular domain-specific GABAergic innervation probably developed for the coordination of multiple glutamatergic inputs on different parts of pyramidal cells through the temporally distinct activity of GABAergic interneurons, which differentially change their firing during different network states.
34
Wilson, Charles J., Angela Weyrick, David Terman, Nicholas E. Hallworth e Mark D. Bevan. "A Model of Reverse Spike Frequency Adaptation and Repetitive Firing of Subthalamic Nucleus Neurons". Journal of Neurophysiology 91, n. 5 (maggio 2004): 1963–80. http://dx.doi.org/10.1152/jn.00924.2003.
Testo completoAbstract (sommario):
Subthalamic nucleus neurons exhibit reverse spike-frequency adaptation. This occurs only at firing rates of 20–50 spikes/s and higher. Over this same frequency range, there is an increase in the steady-state frequency–intensity ( F– I) curve's slope (the secondary range). Specific blockade of high-voltage activated calcium currents reduced the F– I curve slope and reverse adaptation. Blockade of calcium-dependent potassium current enhanced secondary range firing. A simple model that exhibited these properties used spike-triggered conductances similar to those in subthalamic neurons. It showed: 1) Nonaccumulating spike afterhyperpolarizations produce positively accelerating F– I curves and spike-frequency adaptation that is complete after the second spike. 2) Combinations of accumulating aftercurrents result in a linear F– I curve, whose slope depends on the relative contributions of inward and outward currents. Spike-frequency adaptation can be gradual. 3) With both accumulating and nonaccumulating aftercurrents, primary and secondary ranges will be present in the F– I curve. The slope of the primary range is determined by the nonaccumulating conductance; the accumulating conductances govern the secondary range. The transition is determined by the relative strengths of accumulating and nonaccumulating currents. 4) Spike-threshold accommodation contributes to the secondary range, reducing its slope at high firing rates. Threshold accommodation can stabilize firing when inward aftercurrents exceed outward ones. 5) Steady-state reverse adaptation results when accumulated inward aftercurrents exceed outward ones. This requires spike-threshold accommodation. Transient speedup arises when inward currents are smaller than outward ones at steady state, but accumulate more rapidly. 6) The same mechanisms alter firing in response to irregular patterns of synaptic conductances, as cell excitability fluctuates with changes in firing rate.
35
Venkatachari, K. R., Dai Huang, Steven P. Ostrander, Walter A. Schulze e Gregory C. Stangle. "Preparation of nanocrystalline yttria-stabilized zirconia". Journal of Materials Research 10, n. 3 (marzo 1995): 756–61. http://dx.doi.org/10.1557/jmr.1995.0756.
Testo completoAbstract (sommario):
Nanocrystalline powder with an average crystallite size of 8–12 nm, which was produced by a combustion synthesis process, was used to prepare dense, nanocrystalline articles. Green compacts of high green density were prepared by dry pressing and densified by a fast-firing process. During fast-firing, the dwell temperature significantly affected the final grain size and final density. On the other hand, the ranges of heating rates and dwell times that were used had a much less significant effect on the final density and final grain size. It was determined, however, that a high final density (>99% ρth) and a very fine final average grain size (<200 nm) can be simultaneously achieved under three different firing conditions. The high densification rates are, in part, a result of the minimal coarsening that the particles undergo when the sample is taken rapidly through the temperature regime in which surface diffusion predominates to the temperature regime in which the densification mechanisms of grain boundary and lattice diffusion predominate.
36
Dean, J. B., e J. A. Boulant. "Delayed firing rate responses to temperature in diencephalic slices". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 263, n. 3 (1 settembre 1992): R679—R684. http://dx.doi.org/10.1152/ajpregu.1992.263.3.r679.
Testo completoAbstract (sommario):
Thermoregulatory responses may be delayed in onset and offset by several minutes after changes in hypothalamic temperature. Our preceding study found neurons that displayed delayed firing rate responses during clamped thermal stimulation in remote regions of rat diencephalic tissue slices. The present study looked for similar delayed firing rate responses during clamped (1.5-10 min) changes in each neuron's local temperature. Of 26 neurons tested with clamped thermal stimulation, six (i.e., 23%) showed delayed responses, with on-latencies of 1.0-7.8 min. These neurons rarely showed off-latencies, and the delayed response was not eliminated by synaptic blockade. The on-latencies and ranges of local thermosensitivity were similar to delayed neuronal responses to remote temperature; however, remote-sensitive neurons displayed off-latencies, higher firing rates at 37 degrees C, and greater sensitivity to thermal stimulation. Our findings suggest that delayed thermosensitivity is an intrinsic property of certain neurons and may initiate more elaborate or prolonged delayed responses in synaptically connected diencephalic networks. These networks could explain the delayed thermoregulatory responses observed during hypothalamic thermal stimulation.
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Merkel, Drorit, Nir Hirshhoren, Tzippora Shochat e Asaf Vivante. "The Association between Acute Lead Exposure from Indoor Firing Ranges and Iron Metabolism." Blood 108, n. 11 (16 novembre 2006): 3747. http://dx.doi.org/10.1182/blood.v108.11.3747.3747.
Testo completoAbstract (sommario):
Abstract Objective: To assess the impact of short term indoor firing ranges lead exposure and its relationship to iron, ferritin, lead, zinc protoporphyrin and hemoglobin concentration among young adults. Methods: We report of a clinical observation that was carried out in 30 young and healthy soldiers serving in the Israel Defense Forces (IDF) Counter Terrorist Unit (CTU). Blood samples were drawn for Lead (Pb), Zinc Protoporphyrin (ZPP),Iron, Hemoglobin (Hb) and ferritin prior to and after a 6 weeks period of intensive shooting practice in indoor firing ranges. Results: A mean Blood lead level increase (p< 0.0001) with a mean Iron (p<0.0005) and mean ferritin (p<0.0625) decrease simultaneously after 6 weeks period of Lead dusts exposure were demonstrated. We found a trend for inverse correlation between pre-exposure low ferritin levels and post exposure high blood lead levels. Conclusion: We found decreased iron and ferritin levels after short term lead exposure among young adults. This can be explained by competition of iron and lead absorption viatransporters like DMT1 suggesting that lead poisoning can cause iron depletion and that iron depletion can aggravate lead poisoning. This synergistic effect should come to every physicians mind especially when treating patients with a potential risk for each problem separately. Lead (Pb), Zinc Protoporphryn (ZPP), Hemoglobin (Hb), Iron and Ferritin among the CTU soldiers before and after the indoor firing ranges lead exposer variable N Pre-exposure N Post-exposure Difference *P value Pb (mcg/dl) 29 10.3±2.3 30 18.9±3.6 8.8±2.6 0.0001 ZPP(mcg/dl) 29 42±7.5 30 42.9±8.1 0.03±6.5 NS Hb (g/dl) 30 15±0.7 30 14.8±0.9 0.2±0.2 NS MCV (fl) 30 88.7±2.5 30 89±2.7 0.3±0.2 NS Iron (mcg/dl) 29 108.5±43.6 30 77.4±24.4 −30.4±41.2 0.0005 Ferritin (mcg/l) 27 58.1±27.7 16 51±19.9 −6.1±10.7 0.0625 Correlation between Pre-exposure Ferritin levels and Post exposure Lead level.(Person correlation coefficient = −0.28 r=0.14 number of observations = 27) Correlation between Pre-exposure Ferritin levels and Post exposure Lead level.(Person correlation coefficient = −0.28 r=0.14 number of observations = 27)
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Kerry, Geoff, e Martin West. "The development of prediction models to control noise levels around UK firing ranges". Journal of the Acoustical Society of America 105, n. 2 (febbraio 1999): 1133. http://dx.doi.org/10.1121/1.425396.
Testo completo
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Burton, Shawn D., G. Bard Ermentrout e Nathaniel N. Urban. "Intrinsic heterogeneity in oscillatory dynamics limits correlation-induced neural synchronization". Journal of Neurophysiology 108, n. 8 (15 ottobre 2012): 2115–33. http://dx.doi.org/10.1152/jn.00362.2012.
Testo completoAbstract (sommario):
Synchronous neural oscillations are found throughout the brain and are thought to contribute to neural coding and the propagation of activity. Several proposed mechanisms of synchronization have gained support through combined theoretical and experimental investigation, including mechanisms based on coupling and correlated input. Here, we ask how correlation-induced synchrony is affected by physiological heterogeneity across neurons. To address this question, we examined cell-to-cell differences in phase-response curves (PRCs), which characterize the response of periodically firing neurons to weak perturbations. Using acute slice electrophysiology, we measured PRCs across a single class of principal neurons capable of sensory-evoked oscillations in vivo: the olfactory bulb mitral cells (MCs). Periodically firing MCs displayed a broad range of PRCs, each of which was well fit by a simple three-parameter model. MCs also displayed differences in firing rate-current relationships and in preferred firing rate ranges. Both the observed PRC heterogeneity and moderate firing rate differences (∼10 Hz) separately reduced the maximum correlation-induced synchrony between MCs by up to 25–30%. Simulations further demonstrated that these components of heterogeneity alone were sufficient to account for the difference in synchronization among heterogeneous vs. homogeneous populations in vitro. Within this simulation framework, independent modulation of specific PRC features additionally revealed which aspects of PRC heterogeneity most strongly impact correlation-induced synchronization. Finally, we demonstrated good agreement of novel mathematical theory with our experimental and simulation results, providing a theoretical basis for the influence of heterogeneity on correlation-induced neural synchronization.
40
Bordyian, P. "RECOMMENDATIONS FOR INCREASING THE EFFICIENCY OF SNIPER WEAPON FIRE BY ADJUSTING EXISTING AND COMPILING NEW FIRING TABLES". Collection of scientific works of Odesa Military Academy, n. 17 (31 agosto 2022): 101–9. http://dx.doi.org/10.37129/2313-7509.2022.17.101-109.
Testo completoAbstract (sommario):
The article examines the use of sniper weapons in the Armed Forces, both outdated and modern, domestically produced and provided by Ukraine's allied states as military aid. Some features of the construction of sniper weapons and their characteristics are considered. Evaluation of the effectiveness of firing from various weapons is carried out using so-called fire efficiency indicators. Based on them, the possible level of damage to various typical targets is calculated, on the basis of which firing rules are developed. The range of effective fire is understood as the maximum range at which a given level of target defeat is achieved with a rational consumption of ammunition and firing time. It is necessary to understand that the range of effective fire of a weapon is not a constant value, the same for all conditions. It is impossible to remember all cases of the range of effective fire from different targets, from different positions, with different ammunition. It is enough to understand and remember only the typical variants of the conditions of firing with this weapon and the corresponding ranges of effective fire. And use them to solve the problem in specific conditions. the range of effective fire from it depends on specific conditions. Some answers to the evaluation of the effectiveness of fire from the SGD army sniper rifle are given by the Tables of shooting at ground targets with small arms of 5.45 and 7.62 mm caliber. However, the effect of these Tables does not extend to the latest samples of domestic production and provided to Ukraine by Western partners. That is why suggestions and recommendations have been developed for correcting existing and compiling similar shooting tables for modern sniper rifles. Keywords: small arms, sniper rifle, large-caliber sniper rifle - rifles for defeating material means, ammunition, firing tables, firing efficiency.
41
Pape, Hans-Christian, Denis Paré e Robert B. Driesang. "Two Types of Intrinsic Oscillations in Neurons of the Lateral and Basolateral Nuclei of the Amygdala". Journal of Neurophysiology 79, n. 1 (1 gennaio 1998): 205–16. http://dx.doi.org/10.1152/jn.1998.79.1.205.
Testo completoAbstract (sommario):
Pape, Hans-Christian, Denis Paré, and Robert B. Driesang. Two types of intrinsic oscillations in neurons of the lateral and basolateral nuclei of the amygdala. J. Neurophysiol. 79: 205–216, 1998. Intracellular recordings in the guinea pig and cat basolateral amygdaloid (BL) complex maintained as slices in vitro revealed that a subpopulation of neurons (79%) in the lateral (AL) and basolateral (ABl) nuclei generated two types of slow oscillations of the membrane potential upon steady depolarization from resting potential. The cells were of a stellate or pyramidal-like shape and possessed spiny dendrites and an axon leaving the local synaptic environment, and thus presumably represented projection neurons. Similar oscillatory activity was observed in projection neurons of the cat AL nucleus recorded in vivo. Oscillatory activity with a low threshold of activation (low-threshold oscillation, LTO) appeared as rhythmic deflections (amplitudes, 2–6 mV) of the membrane potential positive to −60 mV. Fast Fourier transformation (FFT) demonstrated a range of frequencies of LTOs between 0.5 and 9 Hz, with >80% occurring at 1–3.5 Hz and an average at 2.3 ± 1.1 Hz. LTOs were more regular after pharmacological blockade of synaptic transmission and were blocked by tetrodotoxin (TTX). Blockade of LTOs and Na+ spikes revealed a second type of oscillatory activity (high-threshold oscillation, HTO) at depolarizations beyond −40 mV, which was capable of triggering high-threshold spikes. HTOs ranged between 1 and 7.5 Hz, with >80% occurring at 2–6 Hz and an average at 5.8 ± 1.1 Hz. HTOs vanished at a steady membrane polarization positive to −20 mV. Current versus voltage relations obtained under voltage-clamp conditions revealed two regions of negative slope conductance at −55 to −40 mV and at around −30 mV, which largely overlapped with the voltage ranges of LTOs and HTOs. TTX abolished the first region of negative slope conductance (−55 to −40 mV) and did not significantly influence the second region of negative slope conductance. Neuronal responses to maintained depolarizing current pulses consisted of an initial high-frequency discharge (up to 100 Hz), the frequency of which depended on the amplitude of the depolarizing current pulse, followed by a progressive decline (“adaptation”) toward a slow-rhythmic firing pattern. The decay in firing frequency followed a double-exponential function, with time constants averaging 57 ± 28 ms and 3.29 ± 1.85 s, and approached steady-state frequencies at 6.3 ± 2.9 Hz ( n = 17). Slow-rhythmic firing remained at this frequency over a wide range of membrane polarization between approximately −50 and −20 mV, although individual electrogenic events changed from Na+ spikes and underlying LTOs to high-threshold spikes and underlying HTOs. Rhythmic regular firing was only interrupted at an intermediate range of membrane polarization by the occurrence of spike doublets. In conclusion, the integrative behavior of a class of neurons in the BL complex appears to be largely shaped by the slow-oscillatory properties of the membrane. While LTOs are likely to synchronize synaptic signals near firing threshold, HTOs are a major determinant for the slow steady-state firing patterns during maintained depolarizing influence. These intrinsic oscillatory mechanisms, in turn, can be assumed to promote population activity at this particular frequency, which ranges well within that of the limbic theta (Θ) rhythm and the delta (δ) waves in the electroencephalogram during slow-wave sleep.
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Meunier, Claude, e Karol Borejsza. "How Membrane Properties Shape the Discharge of Motoneurons: A Detailed Analytical Study". Neural Computation 17, n. 11 (1 novembre 2005): 2383–420. http://dx.doi.org/10.1162/0899766054796923.
Testo completoAbstract (sommario):
Electrophysiological experiments and modeling studies have shown that after hyperpolarization regulates the discharge of lumbar motoneurons in anesthetized cats and is an important determinant of their firing properties. However, it is still unclear how firing properties depend on slow after hyperpolarization, input conductance, and the fast currents responsible for spike generation. We study a single-compartment integrate-andfire model with a slow potassium conductance that exponentially decays between spikes. We show that this model is analytically solvable, and we investigate how passive and active membrane properties control the discharge. We show that the model exhibits three distinct firing ranges (primary, secondary, and high frequency), and we explain the origin of these three ranges. Explicit expressions are established for the gain of the steady-state current-frequency (I− f) curve in the primary range and for the gain of the I− f curve for the first interspike interval. They show how the gain is controlled by the maximal conductance and the kinetic parameters of the after hyperpolarization conductance. The gain also depends on the spike voltage threshold, and we compute how it is decreased by threshold accommodation (i.e., the increase of the threshold with the injected current). In contrast, the gain is not very sensitive to the input conductance. This implies that tonic synaptic activity shifts the current-frequency curve in its primary range, in agreement with experiments. Taking into account the absolute refractory period associated with spikes somewhat reduces the gain in the primary range. More importantly, it accounts for the approximately linear and steep secondary range observed in many motoneurons. In the nonphysiological high-frequency range, the behavior of the I− f curve is determined by the fast voltage-dependent currents, via the amplitude of the fast repolarization afterspike, the duration of the refractory period, and voltage threshold accommodation, if present.
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Itoh, Y., R. F. Waldeck, A. Tessler e M. J. Pinter. "Regenerated dorsal root fibers form functional synapses in embryonic spinal cord transplants". Journal of Neurophysiology 76, n. 2 (1 agosto 1996): 1236–45. http://dx.doi.org/10.1152/jn.1996.76.2.1236.
Testo completoAbstract (sommario):
1. The aim of the present study was to determine whether synapses formed by dorsal root afferents that regenerate into intraspinal transplants of fetal spinal cord are functional. Severed L4 or L5 dorsal root stumps were placed at the bottom of dorsal quadrant cavities made in the lumbar spinal cords of adult rats and juxtaposed to embryonic day 14 spinal cord transplants. 2. In animals examined 5-10 weeks later, we recorded extracellularly in transplants from 43 units that fired in response to electrical stimulation of the implanted dorsal root. Latency fluctuations of extracellular firing that increase with stimulus and failure to follow high-frequency and posttetanic potentiation of extracellular firing stimulation suggest that synapses with conventional properties are formed between regenerating afferents and transplant neurons. Limited intracellular recordings confirmed the existence of excitatory postsynaptic potentials in transplant neurons after dorsal root stimulation. 3. In 16 units, extracellular firing occurred in response to single shock stimulation. The remainder of the units required two or more dorsal root shocks to evoke firing; some of these connections also may be monosynaptic. 4. Under the assumption that single shock firing was most likely the result of monosynaptic connections between transplant neurons and regenerated dorsal root fibers, we estimated the conduction velocities of regenerated fibers. These estimates suggest that fibers with conduction velocities in the C, A delta, and A alpha/beta ranges regenerate into transplants of embryonic spinal cord. 5. The results demonstrate that regenerated dorsal root axons establish functional synaptic connections with transplant neurons. The implications for using fetal transplants to help rebuild spinal reflex circuits after spinal cord injury are considered.
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Saikia, Raktim Ranjan, Chaitra Dhar Taye, Nurul Amin, Sorat Konwar, Laura Panzeri e Anna Galli. "Chronological and Archaeometric Evaluation of Bricks from Archaeological Sites of Upper Assam, Northeast India: Estimation of the Firing Temperature and Civilization History". Applied Sciences 14, n. 14 (18 luglio 2024): 6271. http://dx.doi.org/10.3390/app14146271.
Testo completoAbstract (sommario):
This study aimed to uncover the chronology and production technologies of ancient bricks unearthed from various locations in Upper Assam, Northeast India. To achieve this goal, complementary spectroscopic techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) coupled with Energy Dispersive Spectrometer (EDS), as well as Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL/IRSL) dating, were applied. FTIR and XRD analyses revealed the presence of quartz, feldspar (microcline, orthoclase, albite), kaolinite, chlorite, cerussite, palygorskite, magnetite, hematite, and organic carbon. The mineralogical composition indicates two distinct groups with firing temperatures below 650 °C and above ~800 °C. These two groups could be the first indication of the presence of two civilizations or at least two different production technologies involving different firing temperatures and kiln atmospheric conditions. Further, the SEM-EDS study suggests that both calcareous and non-calcareous clays were used in brick making, which have low and high refractory properties, respectively. The internal morphology of the samples shows the existence of micropores and microfractures, indicating the influence of higher-temperature firing. Absolute dating techniques associate the two brick groups with different age ranges: a firing temperature above ~800 °C indicates a superior technology corresponding to a production period between the 7th and 10th centuries CE. In contrast, a temperature below 650 °C indicates a technologically less advanced group of people, with the age group dated between the 11th and 14th centuries CE.
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Butkus, Michael A., e Marie C. Johnson. "Reevaluation of Phosphate as a Means of Retarding Lead Transport from Sandy Firing Ranges". Soil and Sediment Contamination: An International Journal 20, n. 2 (28 febbraio 2011): 172–87. http://dx.doi.org/10.1080/15320383.2011.546444.
Testo completo
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Dufayet, Laurène, Jérôme Langrand, Natacha Bercessio‐Nguon, Antoine Villa, Robert Garnier e Hervé Laborde‐Castérot. "Lead exposure at firing ranges in France: An addendum to Johnson‐Arbor et al". American Journal of Industrial Medicine 63, n. 9 (5 luglio 2020): 838–39. http://dx.doi.org/10.1002/ajim.23151.
Testo completo
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De Luca, Carlo J., Alexander Adam, Robert Wotiz, L. Donald Gilmore e S. Hamid Nawab. "Decomposition of Surface EMG Signals". Journal of Neurophysiology 96, n. 3 (settembre 2006): 1646–57. http://dx.doi.org/10.1152/jn.00009.2006.
Testo completoAbstract (sommario):
This report describes an early version of a technique for decomposing surface electromyographic (sEMG) signals into the constituent motor unit (MU) action potential trains. A surface sensor array is used to collect four channels of differentially amplified EMG signals. The decomposition is achieved by a set of algorithms that uses a specially developed knowledge-based Artificial Intelligence framework. In the automatic mode the accuracy ranges from 75 to 91%. An Interactive Editor is used to increase the accuracy to >97% in signal epochs of about 30-s duration. The accuracy was verified by comparing the firings of action potentials from the EMG signals detected simultaneously by the surface sensor array and by a needle sensor. We have decomposed up to six MU action potential trains from the sEMG signal detected from the orbicularis oculi, platysma, and tibialis anterior muscles. However, the yield is generally low, with typically ≤5 MUs per contraction. Both the accuracy and the yield should increase as the algorithms are developed further. With this technique it is possible to investigate the behavior of MUs in muscles that are not easily studied by needle sensors. We found that the inverse relationship between the recruitment threshold and the firing rate previously reported for muscles innervated by spinal nerves is also present in the orbicularis oculi and the platysma, which are innervated by cranial nerves. However, these two muscles were found to have greater and more widespread values of firing rates than those of large limb muscles.
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Hu, Maoyang, e Siqin Chang. "Study on Valve Strategy and Fuel Benefits of Skip Fire Based on Electromagnetic Valve Train". MATEC Web of Conferences 202 (2018): 02003. http://dx.doi.org/10.1051/matecconf/201820202003.
Testo completoAbstract (sommario):
Cylinder deactivation (CDA) is a fuel consumption reduction technology for gasoline engines. Skip fire is a new type of CDA because the load and the density of firing cylinder are in proportion to the torque demand. However, it is difficult to realize because valves need to be switched between valve deactivation and normal operation stroke by stroke. The Electromagnetic valve train (EMVT) provides a fully flexible control method to achieve skip fire. In the paper, a new skip fire strategy based on electromagnetic intake valve train (EMIV) is proposed. Then, the oxygen concentration of the exhaust pipe, energy losses, in-cylinder pressure of the skipped cycle and exhaust gas recirculation (EGR) rate of the firing cycle are studied by the 1D simulation in GT-Power. The results shows the majority of gas sucked into the skipped cylinder is exhaust gas by reasonable control of IVO and IVC, and the exhaust oxygen-rich can be avoided. Meanwhile, EGR rate of the firing cylinder and energy losses of the skipped cylinder are maintained at lower level. At the conditions of 1200 and 1600 rpm, fuel economy has been improved respectively 8.1%-16.6% and 6.4%-14.6% when the brake mean effective pressure (BMEP) ranges from 0.4MPa to 0.2MPa.
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Aras, A., e S. Kiliç. "The mineralogy and firing behaviour of pottery clays of the Lake Van region, eastern Turkey". Clay Minerals 52, n. 4 (dicembre 2017): 453–68. http://dx.doi.org/10.1180/claymin.2017.052.4.04.
Testo completoAbstract (sommario):
AbstractThe present study focused on the mineralogical and chemical characterization and firing behaviour of clays from the Lake Van region and compared them with the same characteristics established for two ancient pot sherds. Four pottery clays collected from Kutki and Kuşluk in the Kesan Valley to the south, from Kavakbaşı to the southwest and from Bardakçı village on the east coast of Lake Van were analysed by X-ray diffraction to identify mineralogical composition (bulk clays and <2 μm fractions after heating at 300–500°C and ethylene glycol solvation). Further analyses were conducted to determine the size distribution, chemical composition and physical properties of test bodies derived from these clays. The in situ weathered schist forming the primary micaceous red clays which are suitable for local pottery production are characterized by large muscovite-sericite-illite and small calcite contents. In contrast, the Bardakçı clays are dominated by large smectite contents and are only used sparingly in mixtures of local pottery production because they undergo firing shrinkage and present drying and firing flaws in the fired bodies. Firing ranges of ~800–900°C were inferred from the mineralogy and colours of the two ancient sherds from Kutki. As a result of mineralogical analysis of fired and unfired test bodies of these pottery clays and pot sherds, two different types of pastes were determined for pottery production in the Lake Van region: metamorphic and volcanic paste, the former characterized by a calcite-poor and mica-sericite-rich matrix and the latter by large smectite and small calcite contents.
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Gomi, Hiroaki, Munetaka Shidara, Aya Takemura, Yuka Inoue, Kenji Kawano e Mitsuo Kawato. "Temporal Firing Patterns of Purkinje Cells in the Cerebellar Ventral Paraflocculus During Ocular Following Responses in Monkeys I. Simple Spikes". Journal of Neurophysiology 80, n. 2 (1 agosto 1998): 818–31. http://dx.doi.org/10.1152/jn.1998.80.2.818.
Testo completoAbstract (sommario):
Gomi, Hiroaki, Munetaka Shidara, Aya Takemura, Yuka Inoue, Kenji Kawano, and Mitsuo Kawato. Temporal firing patterns of Purkinje cells in the cerebellar ventral paraflocculus during ocular following responses in monkeys. I. Simple spikes. J. Neurophysiol. 80: 818–831, 1998. The simple-spike firing frequency of 30 Purkinje cells (P cells) in the ventral paraflocculus (VPFL) of alert monkeys was studied in relation to vertical slow eye movements, termed ocular following response (OFR), induced by large-field visual motions of different velocities and durations. To quantitatively analyze the relationship between eye movement and firing frequency, an inverse dynamics representation of the eye movement was used for reconstructing the temporal waveform of firing. Coefficients of eye-acceleration, velocity, and position, bias, and time lag between firing and eye movement were estimated by least-square error method. In the regression analyses for each stimulus condition, 86% (146/170) of the well-modulated temporal firing patterns taken from those 30 P cells were reconstructed successfully from eye movement. The model with acceleration, velocity, and position terms, which we used, was shown as the best among several potential models by Cp statistics, consistent with t-test of significance of each term. Reliable coefficients were obtained from 75% (109/146) of the well-reconstructed firing patterns of 28 cells among 30. The estimated coefficients were larger (statistically significant) for slow stimuli than for fast stimuli, suggesting changes in sensitivities under different conditions. However, firing patterns of each cell under several different conditions were frequently well reconstructed by an inverse dynamics representation with a single set of coefficients (13 cells among 21). This indicates that the relationships between P cell firing and OFR are roughly linear in those stimulus ranges. The estimated coefficients for acceleration and velocity suggested that the VPFL P cells properly encode the dynamic components of the motor command during vertical OFR. As for the positional component, however, these P cells are correlated with eye movement in the opposite direction. In the regression analysis without positional component, remarkable differences between observed and reconstructed firing patterns were noted especially in the initial phase of the movements, indicating that the negative positional component was not negligible during OFR. Thus we conclude that, during OFR, the VPFL P cells cannot provide the necessary final motor command, and other brain regions, downstream neural structures, or other types of P cells must provide lacking position-dependent motor commands. This finding about the negative correlation with the position is in the opposite sign with previous studies obtained from the fixation and the smooth pursuit movement. From these comparisons, how the VPFL contributes to a part of the final motor command or how other brain regions complement the VPFL is suggested to be different for early and late phases of the movements.