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1.
It is shown that the difference between the specific thermal conductivity coefficients in the absence of an electric current and field has a substantial effect on the maximum temperature drop.Chernovitsy State University, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 6, pp. 729–732, June, 1994. 相似文献
2.
Pontine cat is an ectothermic preparation, whose central temperature can artificially be lowered from 36 degrees C to 26 degrees C; this gradual hypothermia is accompanied by a dramatic increase in paradoxical sleep (PS). Two main hypotheses might explain this result: executive systems of PS might be switched on gradually by cold-sensitive thermodetectors, whereas inhibitory monoaminergic mechanisms appear to be warm-sensitive. On the other hand, energy saving mechanisms peculiar to hypothermia might promote PS appearance. Indeed, in normal animals, PS is selectively suppressed both by hyperthermia and hypoxia. The inhibitory effect of hypoxia might explain why hypothermia, which protects the brain against hypoxic alterations, might facilitate PS. If this last hypothesis is correct, the putative increase in cerebral oxygen supply might increase PS. For this reason, we submitted eight pontine carotid-deafferented cats, kept at the same central temperature (34 +/- 0.5 degrees C: temperature clamp) to periodic hyperoxia (PaO2 = 58 +/- 7 kPa) or room air (PaO2 = 17 +/- 2 kPa) alternatively during 4- or 12-h periods. Hyperoxia induced an 85% increase in PS, mainly due to an increase in PS rhythm (PS cycle duration was 65 +/- 4 min in normoxia and 45 +/- 4 min in hyperoxia, p<0.0001). In five animals, after hyperoxia, PS cycle returned gradually back to control values in 4 to 12 h. These findings show that PS is exquisitely sensitive to conditions that impair oxidative metabolism. The role of cholinergic executive PS systems as putative metabolic-sensitive neurons remains to be established. 相似文献
3.
Linas Minkevičius Vincas Tamošiūnas Martynas Kojelis Ernestas Žąsinas Virginijus Bukauskas Arūnas Šetkus Renata Butkutė Irmantas Kašalynas Gintaras Valušis 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(6):689-707
A detailed electrical characterization of high-performance bow-tie InGaAs-based terahertz detectors is presented along with simulation results. The local surface potential and tunnelling current were scanned over the surfaces of the detectors by means of Kelvin probe force microscopy (KPFM) and scanning tunnelling microscopy (STM), which also enabled the determination of the Fermi level. Current-voltage curves were measured and modelled using the Synopsys Sentaurus TCAD package to gain deeper insight into the processes involved in detector operation. In addition, we performed finite-difference time-domain (FDTD) simulations to reveal features related to changes in the electric field due to the metal detector contacts. The investigation revealed that field-effect-induced conductivity modulation is a possible mechanism contributing to the high sensitivity of the studied detectors. 相似文献
4.
5.
This paper presents the latest results on a block turbo decoder design. We propose a block turbo decoder circuit for the error protection of small data blocks such asAtm cells on anAwgn (additive white Gaussian noise) channel with a code rate close to 0.5. A prototype was developed atEnst Bretagne. It allowsBer (bit error rate) measurements down to 10?9 and uses programmable gate arrays (Fpga Xilinx circuits). The elementary extendedBch code and the data block size can be modified to fit specifications of different applications. 相似文献
6.
Löfstedt C Zhu J Kozlov MV Buda V Jirle EV Hellqvist S Löfqvist J Plass E Franke S Francke W 《Journal of chemical ecology》2004,30(3):643-658
Under an artificial light:dark cycle, females of Lampronia capitella were observed calling, with extended terminal abdominal segments, during the first 2 hr of the photoperiod. Extracts of terminal abdominal segments from females elicited large electroantennographic responses from male antennae. Gas chromatography with electroantennographic detection revealed three active peaks. Based on comparison of retention times and mass spectra of synthetic standards, these compounds were identified as (Z,Z)-9,11-tetradecadienol and the corresponding acetate and aldehyde. The electroantennographic activity of the four geometric isomers of all three compounds was investigated, and the respective (Z,Z)-isomer was found to be the most active in all cases. Aldehydes generally elicited larger antennal responses than alcohols, whereas acetates were the least active compounds. A subtractive trapping assay in the field, based on a 13:26:100 micrograms mixture of (Z,Z)-9,11-tetradecadienal, (Z,Z)-9,11-tetradecadienyl acetate, and (Z,Z)-9,11-tetradecadienol confirmed that all three compounds are pheromone components. Subtraction of (Z,Z)-9,11-tetradecadienol from the blend completely eliminated its attractiveness, whereas the other two-component blends showed reduced activity. This is the first pheromone identification from the monotrysian superfamily Incurvarioidea, confirming that the common pheromones among ditrysian moths (long-chain fatty acid derivatives comprising alcohols, acetates, and aldehydes with one or more double bonds) is not an autapomorphy of Ditrysia, but a synapomorphy of the more advanced heteroneuran lineages. 相似文献
7.
8.
Rodolphe Buda 《Computational Economics》2008,31(4):397-408
The aggregation procedure is an important theoretical and empirical topic of economics. It appears in the Microeconomics and
Macroeconomics, in Panel and Cross-Sectional Data Analysis, in Data Mining Analysis, in Input–Output and Agent-based Computational
Economics Modelling. The question of the choice of algorithm is became important since the size of the sample data has became
more important, and despite of the speed of the computers. In this paper we present the “classical” algorithm (the “matrix
algebraic” one) of aggregation of the two-dimensional sample data, and compare it to the alternative algorithms (the “vectorial”
one) we developed. Then we present some extensions to the multidimensional aggregation.
相似文献
9.
M. Buda H.H. Tan L. Fu L. Josyula C. Jagadish 《Photonics Technology Letters, IEEE》2003,15(12):1686-1688
The kink-free output power in 980-nm emitting laser diodes can be increased by 30%-50% in ridge-waveguide devices when the thickness of the oxide is decreased such that the optical field is allowed to interact with the lossy Ti-PtAu metallization outside the ridge. This provides selective loss for the first-order lateral mode and delays the onset of the beam steering associated with kinks in the power output-current characteristic. The method is very simple and can be applied for any kind of ridge-waveguide semiconductor laser diode device. 相似文献
10.
Fluorescence anisotropy parameter of [p-(6-phenyl)-1,3,5-hexatrienyl]phenyl-propionic acid (DPH-PA) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene
(TMA-DPH) embedded in synaptic plasma membranes prepared from brains of cold (5°C) and warm (22°C) adapted fish (Cyprinus carpio L.), rat (Rattus norvegicus) and bird (Branta canadensis), was studied. Fatty acid composition of total lipids as well as molecular species composition of diacyl phosphatidylcholines
and phosphatidylethanolamines was also determined. The amount of long-chain polyunsaturated fatty acids decreased with increasing
body temperature. There was a nearcomplete compensation of membrane structural order for environmental/body tempeature over
the evolutionary scale as seen by DPH-PA. Using TMA-DPH, the compensation was partial with rat and bird. Since DPH-PA and
TMA-DPH differ in their charges, it is proposed, that the former reported membrane regions rich in cationic or zwitterionic
(neutral) phospholipids and the latter, membrane regions rich in negatively charged phospholipids in the synaptic plasma membranes.
Many different molecular species (20–25) of diacyl phosphatidylcholines and diacyl phosphatidylethanolamines were identified.
The level of 16:0/22:6 phosphatidylcholine decreased while disaturated phosphatidylcholines increased with increase of environmental/body
temperature from the fish through the bird. Level of 1-monoenoic 2-polyenoic phosphatidylethanolamines also decreased with
an increase in environmental/body temperature. Experiments using vesicles made of mixed synthetic phosphatidylcholine vesicles
(16:0/16:0, 16:0/18:1, 16:0/22:6 in various proportions) showed that increase in disaturated phosphatidylcholine species does
not explain the observed complete adjustment of membrane structural order in synaptic plasma membranes. Change in level of
1-monoenoic, 2-polyenoic phosphatidylethanolamines might be one of the factors involved in controlling the biophysical properties
of the membrane according to the temperature. 相似文献