Spontaneous firing of hypothalamic neurones over a narrow temperature interval

Nature ◽  
1978 ◽  
Vol 273 (5659) ◽  
pp. 242-243 ◽  
Author(s):  
PETER MASON ◽  
HELEN HASAN ◽  
MILENA VALIS
Keyword(s):  
Temperature Interval ◽  
Spontaneous Firing ◽  
Narrow Temperature Interval

scholarly journals The formation conditions of birch tar in oxygen-depleted environments

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Tabea J. Koch ◽  
Patrick Schmidt
Keyword(s):  
Temperature Interval ◽  
Production Systems ◽  
Technical Skills ◽  
Middle Palaeolithic ◽  
Dry Distillation ◽  
Narrow Temperature Interval ◽  
Glass Tubes ◽  
Formation Conditions ◽  
The Relationship ◽  
Heating Duration

AbstractBirch tar is the oldest manmade adhesive dating back to the European Middle Palaeolithic. Its study is of importance for understanding the cognitive capacities and technical skills of Neanderthals and the aceramic production systems employed in the European Palaeolithic and Mesolithic. Several methods may have been used to make birch tar, the most common proposition being dry distillation in oxygen-depleted atmospheres. One of the major impediments for our understanding of the conditions employed to make Neanderthal birch tar, and ultimately the technique used, is that it remains unknown at which temperatures exactly birch tar forms. The relationship between heating duration and tar formation is also unknown. To address these questions, we conduct a laboratory heating experiment, using sealed glass tubes and an electric furnace. We found that birch tar is only produced at a narrow temperature interval (350 °C and 400 °C). Heating times longer than 15 min have no effect on the quantity of tar produced. These findings, notwithstanding previous propositions of necessarily long heating times and larger tolerances for temperature, have important implications for our understanding of the investment in time needed for Palaeolithic birch tar making.

Recrystallization of ion-implanted α-SiC

1987 ◽  
Vol 2 (1) ◽  
pp. 107-116 ◽  
Author(s):  
H. G. Bohn ◽  
J. M. Williams ◽  
C. J. McHargue ◽  
G. M. Begun
Keyword(s):  
Raman Scattering ◽  
Single Crystal ◽  
Temperature Interval ◽  
High Dose ◽  
Low Doses ◽  
Surface Layers ◽  
Annealing Behavior ◽  
Narrow Temperature Interval ◽  
Amorphous Surface ◽  
Ion Implanted

The annealing behavior of ion-implanted α-SiC single crystal was determined for samples implanted with 62 keV 14N to doses of 5.5X1014/cm2 and 8.0X1016/cm2 and with 260 keV 52Cr to doses of 1.5X1014/cm2 and 1.0X1016/cm2. The high-dose samples formed amorphous surface layers to depths of 0.17 μm (N) and 0.28 μm (Cr), while for the low doses only highly damaged but not randomized regions were formed. The samples were isochronically annealed up to 1600°C, holding each temperature for 10 min. The remaining damage was analyzed by Rutherford backscattering of 2 MeV He+, Raman scattering, and electron channeling. About 15% of the width of the amorphous layers regrew cpitaxially from the underlying undamaged material up to 1500°C, above which the damage annealed rapidly in a narrow temperature interval. The damage in the crystalline samples annealed linearly with temperature and was unmeasurable above 1000°C.

Heat capacities of liquid 2,3,6-trimethylpyridine, 2,4,6-trimethylpyridine and 3-methoxypropionitrile within the range of temperatures of 300 to 328 K

1991 ◽  
Vol 56 (12) ◽  
pp. 2786-2790 ◽  
Author(s):  
Václav Svoboda ◽  
Milan Zábranský
Keyword(s):  
Temperature Interval ◽  
Atmospheric Pressure ◽  
Liquid State ◽  
Adiabatic Calorimeter ◽  
Heat Capacities

Molar heat capacities of 2,3,6-trimethylpyridine, 2,4,6-trimethylpyridine and 3-methoxypropionitrile in the liquid state were measured at the constant atmospheric pressure in the temperature interval of 300.60 to 328.35 K. The static type of adiabatic calorimeter was used for the measurements.

scholarly journals Quark Cluster Expansion Model for Interpreting Finite-T Lattice QCD Thermodynamics

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 514
Author(s):  
David Blaschke ◽  
Kirill A. Devyatyarov ◽  
Olaf Kaczmarek
Keyword(s):  
Lattice Qcd ◽  
Cluster Expansion ◽  
Quark Gluon Plasma ◽  
Degrees Of Freedom ◽  
Gluon Plasma ◽  
Polyakov Loop ◽  
Unified Approach ◽  
Narrow Temperature Interval ◽  
Levinson Theorem ◽  
Expansion Model

In this work, we present a unified approach to the thermodynamics of hadron–quark–gluon matter at finite temperatures on the basis of a quark cluster expansion in the form of a generalized Beth–Uhlenbeck approach with a generic ansatz for the hadronic phase shifts that fulfills the Levinson theorem. The change in the composition of the system from a hadron resonance gas to a quark–gluon plasma takes place in the narrow temperature interval of 150–190 MeV, where the Mott dissociation of hadrons is triggered by the dropping quark mass as a result of the restoration of chiral symmetry. The deconfinement of quark and gluon degrees of freedom is regulated by the Polyakov loop variable that signals the breaking of the Z(3) center symmetry of the color SU(3) group of QCD. We suggest a Polyakov-loop quark–gluon plasma model with O(αs) virial correction and solve the stationarity condition of the thermodynamic potential (gap equation) for the Polyakov loop. The resulting pressure is in excellent agreement with lattice QCD simulations up to high temperatures.

scholarly journals Specific heat of refractory carbides (ZrC0.95, HfC0.85 and Ta0.8Hf0.2C) in the temperature interval 2500-5000 K

2020 ◽  
Vol 1686 ◽  
pp. 012055
Author(s):  
A I Savvatimskiy ◽  
NM Aristova ◽  
S V Onufriev ◽  
G E Valiano
Keyword(s):  
Specific Heat ◽  
Temperature Interval

Normal spontaneous firing of cardiac pacemaker cells is regulated by basal pkc delta activation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
T Vinogradova ◽  
K Tarasov ◽  
D Riordon ◽  
Y Tarasova ◽  
E Lakatta
Keyword(s):  
Protein Kinase ◽  
Cycle Length ◽  
Cardiac Pacemaker ◽  
Funding Source ◽  
Spontaneous Firing ◽  
Pacemaker Cells ◽  
Patch Clamp Technique ◽  
Sa Node ◽  
Pkc Delta ◽  
Pkc Isoforms

Abstract   The spontaneous beating rate of rabbit sinoatrial node cells (SANC) is regulated by local subsarcolemmal calcium releases (LCRs) from sarcoplasmic reticulum (SR). LCRs appear during diastolic depolarization (DD) and activate an inward sodium/calcium exchange current which increases DD rate and thus accelerates spontaneous SANC firing. High basal level of protein kinase A and calcium/calmodulin-dependent protein kinase II phosphorylation are required to sustain basal LCRs and normal spontaneous SANC firing. Recently we discovered that basal PKC activation is also obligatory for cardiac pacemaker function: inhibition of PKC activity by broad spectrum PKC inhibitors Bis I or calphostin C markedly suppressed SR calcium cycling and decreased or abolished spontaneous beating of freshly isolated rabbit SANC. Here we studied which PKC isoforms mediate PKC-dependent effects on cardiac pacemaker cell automaticity. The PKC superfamily consists of 3 major subgroups: conventional, novel and atypical. All PKC isoforms were detected at the RNA level (RT-qPCR) in the rabbit SA node and ventricle, and expression levels were comparable in both tissues. Expression of PKCβ, however, was markedly higher in the rabbit SA node, compared to other PKC isoenzymes in either tissue. We verified expression of conventional PKC (α, β) and novel PKC-delta at the protein level in SANC and ventricular myocytes (VM). Western blot confirmed RNA results, showing a 6-fold higher PKCβ protein abundance in SANC compared to VM. Expression of PKCα protein was similar in both cell types, while PKC-delta protein was more abundant in VM. To study whether PKCβ regulates spontaneous beating of SANC we employed selective inhibitor of conventional (α, β, gamma) PKC isoforms Go6976 (10 μmol/L), which had no effects on either LCR characteristics (confocal microscopy, calcium indicator Fluo-3AM) or spontaneous beating of freshly isolated rabbit SANC (perforated patch-clamp technique). Because selective PKC-delta inhibitors are not available, we explored effects of PKC-delta inhibition comparing effects of Go6976 (the inhibitor of conventional PKCs) and Go6983, which inhibits conventional PKCs and PKC-delta. In contrast to Go6976, Go6983 (5 μmol/L) markedly decreased the LCR size (from 7.1±0.4 to 4.5±0.3 μm) and number per each spontaneous cycle (from 1.3±0.1 to 0.8±0.1). It also markedly increased the LCR period (time from the prior AP-induced calcium transient to the subsequent LCR) which was paralleled by an increase in the spontaneous SANC cycle length. Rottlerin, another PKC-delta inhibitor, produced similar effects on LCR characteristics, and markedly and time-dependently decreased DD rate, leading to an increase in the spontaneous cycle length, and finally abrogated the spontaneous SANC firing. Thus, our data indicate that basal activity of PKC-delta, but not that of PKCβ, is essential for generation of LCRs and normal spontaneous firing of cardiac pacemaker cells. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Intramural Research Program, National Institute on Aging, National Institute of Health, USA

Single-unit analysis of different hippocampal cell types during classical conditioning of rabbit nictitating membrane response

1983 ◽  
Vol 50 (5) ◽  
pp. 1197-1219 ◽  
Author(s):  
T. W. Berger ◽  
P. C. Rinaldi ◽  
D. J. Weisz ◽  
R. F. Thompson
Keyword(s):  
Classical Conditioning ◽  
Pyramidal Cell ◽  
Action Potentials ◽  
Pyramidal Cells ◽  
Cell Types ◽  
Firing Frequency ◽  
Spontaneous Firing ◽  
Nictitating Membrane ◽  
Nictitating Membrane Response ◽  
Firing Characteristics

Extracellular single-unit recordings from neurons in the CA1 and CA3 regions of the dorsal hippocampus were monitored during classical conditioning of the rabbit nictitating membrane response. Neurons were classified as different cell types using response to fornix stimulation (i.e., antidromic or orthodromic activation) and spontaneous firing characteristics as criteria. Results showed that hippocampal pyramidal neurons exhibit learning-related neural plasticity that develops gradually over the course of classical conditioning. The learning-dependent pyramidal cell response is characterized by an increase in frequency of firing within conditioning trials and a within-trial pattern of discharge that correlates strongly with amplitude-time course of the behavioral response. In contrast, pyramidal cell activity recorded from control animals given unpaired presentations of the conditioned and unconditioned stimulus (CS and UCS) does not show enhanced discharge rates with repeated stimulation. Previous studies of hippocampal cellular electrophysiology have described what has been termed a theta-cell (19-21, 45), the activity of which correlates with slow-wave theta rhythm generated in the hippocampus. Neurons classified as theta-cells in the present study exhibit responses during conditioning that are distinctly different than pyramidal cells. theta-Cells respond during paired conditioning trials with a rhythmic bursting; the between-burst interval occurs at or near 8 Hz. In addition, two different types of theta-cells were distinguishable. One type of theta-cell increases firing frequency above pretrial levels while displaying the theta bursting pattern. The other type decreases firing frequency below pretrial rates while showing a theta-locked discharge. In addition to pyramidal and theta-neurons, several other cell types recorded in or near the pyramidal cell layer could be distinguished. One cell type was distinctive in that it could be activated with a short, invariant latency following fornix stimulation, but spontaneous action potentials of such neurons could not be collided with fornix shock-induced action potentials. These neurons exhibit a different profile of spontaneous firing characteristics than those of antidromically identified pyramidal cells. Nevertheless, neurons in this noncollidable category display the same learning-dependent response as pyramidal cells. It is suggested that the noncollidable neurons represent a subpopulation of pyramidal cells that do not project an axon via the fornix but project, instead, to other limbic cortical regions.(ABSTRACT TRUNCATED AT 400 WORDS)

An Improved Low-Temperature Brittleness Test

1949 ◽  
Vol 22 (3) ◽  
pp. 820-827 ◽  
Author(s):  
E. F. Smith ◽  
G. J. Dienes
Keyword(s):  
Low Temperature ◽  
Temperature Interval ◽  
Statistical Study ◽  
Distribution Curve ◽  
Simple Analysis ◽  
Reasonable Amount ◽  
Brittle Point

Abstract An improved low-temperature brittleness tester, capable of testing five specimens simultaneously, is described. All machine specifications conform to A.S.T.M. Method D 746-44T. Data are presented which show that many elastomers do not possess a sharp brittle point but are characterized by a distribution of failures over a temperature interval. The improved brittleness tester makes it possible to carry out the necessary statistical study of the distribution of per cent failures versus temperature with a reasonable amount of work. A simple analysis of the resulting distribution curve is presented.

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