检索结果-南通市图书馆

A　Possible　Origin　of　dark　Energy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2004年第6期21卷 1187-1188页

作者： T.d.Lee Physicsdepartment ColumbiaUniversityNewYorkNY10027USA

We discuss the possibility that the existence of dark energy may be due to the presence of a spin zero field φ(x), either elementary or composite. In the presence of other matter field, the transformation φ(x)→φ(x) + constant can generate a negative pressure, like the cosmological constant. In this picture, our universe can be thought as a very large bag, similar to the much smaller MIT bag model for a single nucleon.

关键词： Gravitation and cosmology Particle physics and field theory Astrophysics and astroparticles

Frequency Switches at Transition Temperature in Voltage-Gated Ion Channel dynamics of Neural Oscillators

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2018年第5期35卷 152-155页

作者： Yasuomi d.Sato department of System Information Sciences Graduate School of Information Sciences Tohoku University Institute of Industrial Science University of Tokyo

Understanding of the mechanisms of neural phase transitions is crucial for clarifying cognitive processes in the brain. We investigate a neural oscillator that undergoes different bifurcation transitions from the big saddle homoclinic orbit type to the saddle node on an invariant circle type, and the saddle node on an invariant circle type to the small saddle homoclinic orbit type. The bifurcation transitions are accompanied by an increase in thermodynamic temperature that affects the voltage-gated ion channel in the neural oscillator. We show that nonlinear and thermodynamical mechanisms are responsible for different switches of the frequency in the neural oscillator. We report a dynamical role of the phase response curve in switches of the frequency, in terms of slopes of frequency-temperature curve at each bifurcation transition. Adopting the transition state theory of voltagegated ion channel dynamics, we confirm that switches of the frequency occur in the first-order phase transition temperature states and exhibit different features of their potential energy derivatives in the ion channel. Each bifurcation transition also creates a discontinuity in the Arrhenius plot used to compute the time constant of the ion channel.

关键词： Frequency Switches at Transition Temperature in Voltage-Gated Ion Channel dynamics of Neural Oscillators

Changes in Repetitive Firing Rate Related to Phase Response Curves for Andronov-Hopf Bifurcations

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2014年第5期31卷 13-16页

作者： Yasuomi d. Sato department of Brain Science and Engineering Graduate School of Life Science and Systems Engineering Kyushu Institute of Technology 2-4 Hibikino Wakamatsu Kitakyushu 808-0196 Japan Frankfurt Institute for Advanced Studies (FIAS) Johann Wolfgang Goethe University Ruth-Moufang-Str.1 D60438 Frankfurt am Main Germany Institute of Industrial Science the University of Tokyo 4-6-1 Komaba Meguro Tokyo 153-8505 Japan

We study specific changes in repetitive firing in the two-dimensional Hindmarsh-Rose （2dHR） oscillatory sys- tem that undergoes a bifurcation transition from the supercritical Andronov-Hopf （All） type to the subcritical Andronov-Hopf （SAH） type. We identify dynamical mechanisms which are responsible for changes of the repeti- tive firing rate during the AH to SAH bifurcation transitions. These include frequency-shift functions in response to small perturbations of a timescale parameter, its multiplicative parameter, and an external input current in the 2dHR oscillatory system. The frequency-shift functions are explicitly represented as functions relating to the phase response curves （PRCs）. Then, we demonstrate that when the timescale is normal and relatively fast, the repetitive firing rate slightly increases and decreases respectively during the AH to SAH bifurcation transition with a change of the intrinsic parameter, whereas it decreases during the SAH to AH bifurcation transition with an increase in the timescale. By analyzing the three different frequency-shift functions, we show that such changes of the repetitive firing rate depend largely on changes of the PRC size. The PRC size for the SAH bifurcation shrinks to the PRC size for the AH bifurcation.

关键词： HOPF bifurcations FREQUENCY shift keying MONOTONIC functions VAN der Pol oscillators (Physics) LIMIT cycles

dirac Points in Two-dimensional Inverse Opals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第10期30卷 164-166页

作者： G.d.Mahan department of Physics Pennsylvania State UniversityUniversity ParkPA 16802USA

The electron energy states and energy bands are calculated for a two-dimensional inverse opal *** that the opal structure is closed-packed circles,the inverse opal has the honeycomb *** honeycomb lattice in two dimensions has a diract *** properties can be manipulated by altering the structure of the inverse opal:the radius of the circle,and the small gap between circles.

关键词： structure inverse dirac

Frequency Gradient with Respect to Temperature for determination of Classification of the Phase Response Curve

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第12期30卷 170-173页

作者： Yasuomi d.Sato department of Brain Science and Engineering Graduate School of Life Science and Systems EngineeringKyushu Institute of Technology2-4HibikinoWakamatsuKitakyushu808-0196Japan Frankfurt Institute for Advanced Studies(FIAS)Johann Wolfgang Goethe UniversityRuth-Moufang-Str.1D60438Frankfurt am MainGermany

The interesting task here is to study the frequency-current(f–I)curve and phase response curve(PRC),subject to neural temperature variations,because the f–I curve and PRC are important measurements to understand dynamical mechanisms of generation of neural oscillations,and the neural temperature is widely known to significantly affect the ***,little is discussed about how the temperature affects the f–I curve and *** this study,frequencies of the neural oscillations,modulated with the temperature variations,are quantified with an average of the *** frequency gradient with respect to temperature derived here gives clear classifications of the PRC,regardless of the *** is also indicated that frequency decreases with an increase in temperature,resulted from bifurcation switching of the saddle-homoclinic to the saddle-node on an invariant circle.

关键词： form saddle invariant

An Optimal Power-Law for Synchrony and Lognormally Synaptic Weighted Hub Networks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第9期30卷 190-193页

作者： Yasuomi d.Sato department of Brain Science and Engineering Graduate School of Life Science and Systems EngineeringKyushu Institute of Technology2-4HibikinoWakamatsuKitakyushu808-0196Japan Frankfurt Institute for Advanced Studies(FIAS) Johann Wolfgang Goethe UniversityRuth-Moufang-Str.1D60438Frankfurt am MainGermany

details about the structure of a network model are revealed at the spontaneous spike activity level,in which the power-law of synchrony is optimized to that observed in the CA3 hippocampal slice *** network model is subject to spike noise with exponentially distributed interspike *** excitatory(E)and/or inhibitory(I)neurons interact through synapses whose weights show a log-normal *** spike behavior observed in the network model with the appropriate log-normal distributed synaptic weights fits best to that observed in the *** best-fit is then achieved with high activities of I neurons having a hub-like structure,in which the I neurons,subject to optimized spike noise,are intensively projected from low active E neurons.

关键词： app weights network

Fermion bound states in geometrically deformed backgrounds

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2019年第1期43卷 1-8页

作者： d.Bazeia A.Mohammadi d.C.Moreira departamento de Física Universidade Federal da Paraíba departamento de Física Universidade Federal de Pernambuco Unidade Acadêmica de Física Universidade Federal de Campina Grande

This work deals with the behavior of fermions in the background of kinklike structures in the twodimensional spacetime. The kinklike structures appear from bosonic scalar field models that engender distinct profiles and interact with the fermion fields via the standard Yukawa coupling. We first consider two models that engender parity symmetry, one leading to the exclusion of fermion bound states, and the other to the inclusion of bound states, when the parameter that controls the bosonic structure varies from zero to unity. We then investigate a third model where the kinklike solution explicitly breaks parity symmetry, leading to fermion bound states that are spatially asymmetric.

关键词： topological defect fermion interaction bound state

An investigation of roof runoff during rain events at the Royal Military College of Canada and potential discharge to Lake Ontario

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2011年第7期23卷 1072-1078页

作者： david G. Kelly Ron d. Weir Steven d. White Analytical Sciences Group & SLOWPOKE-2 Facility at RMC Department of Chemistry and Chemical Engineering Royal Military College of Canada 11 General Crerar Crescent

The Royal Military College of Canada, located on the north eastern shore of Lake Ontario, possesses an abundance of copper roofs and lacks surface water treatment prior to discharge into Lake Ontario. Rainwater, roof runoff and soil samples were collected and analyzed for copper and other parameters. Copper was consistently detected in runoff samples with average concentrations of 3200 ± 2100 μg/L. Multivariable linear regression analysis for a dependant copper runoff concentration yielded an adjusted R 2 value of 0.611, based on an independent variable model using minimum temperature, maximum temperature, total precipitation, and wind speed. Lake water samples taken in the vicinity of storm water outfalls draining areas with copper roofs ranged from 2.0 to 40 μg/L copper. Such data exceed the 2.0 μg/L Canadian Water Quality Guidelines for the Protection of Aquatic Life as outlined by the Canadian Council of Ministers of the Environment （CCME）. Analysis of raw, filtered and digested forms suggested that the majority of copper present in runoff and lake water samples was in a dissolved form. The majority of soils taken in this study displayed copper concentrations below the 63 μg/g CCME residential/parkland land use limits. These findings suggested that ion exchange processes between runoff water and soil do not occur to a sufficient extent to elevate copper levels in soil. It may therefore be concluded that the eventual fate of copper, which is not discharged via storm water outfalls, is lost to the water table and Lake Ontario through the sub-soil.

关键词： copper roof runoff Lake Ontario Canadian water quality guidelines for the protection of aquatic life

TIC-Tox: A preliminary discussion on identifying the forcing agents of dBP-mediated toxicity of disinfected water

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2017年第8期29卷 208-216页

作者： Michael J.Plewa Elizabeth d.Wagner Susan d.Richardson Safe Global Water Institute and the Department of Crop Sciences University of Illinois at Urbana-Champaign department of Chemistry and Biochemistry University of South Carolina

The disinfection of drinking water is a major public health achievement; however, an unintended consequence of disinfection is the generation of disinfection by-products（dBPs）. Many of the identified dBPs exhibit in vitro and in vivo toxicity, generate a diversity of adverse biological effects, and may be hazards to the public health and the *** a few dBPs are regulated by several national and international agencies and it is not clear if these regulated dBPs are the forcing agents that drive the observed toxicity and their associated health effects. In this study, we combine analytical chemical and biological data to resolve the forcing agents associated with mammalian cell cytotoxicity of drinking water samples from three cities. These data suggest that the trihalomethanes（THMs） and haloacetic acids may be a small component of the overall cytotoxicity of the organic material isolated from disinfected drinking water. Chemical classes of nitrogen-containing dBPs, such as the haloacetonitriles and haloacetamides, appear to be the major forcing agents of toxicity in these samples. These findings may have important implications for the design of epidemiological studies that primarily rely on the levels of THMs to define dBP exposure among populations. The TIC-Tox approach constitutes a beginning step in the process of identifying the forcing agents of toxicity in disinfected water.

关键词： dBPs CHO cell cytotoxicity Toxicity Additivity