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1.
We study folding dynamics of proteinlike sequences on a square lattice using a physical move set that exhausts all possible conformational changes. By analytically solving the master equation, we follow the time-dependent probabilities of occupancy of all 802 075 conformations of 16 mers over 7 orders of time span. We find that (i) folding rates of these proteinlike sequences of the same length can differ by 4 orders of magnitude, (ii) folding rates of sequences of the same conformation can differ by a factor of 190, and (iii) parameters of the native structures, designability, and thermodynamic properties are weak predictors of the folding rates; rather, a basin analysis of the kinematic energy landscape defined by the moves can provide an excellent account of the observed folding rates. 相似文献
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Organs form during morphogenesis, the process that gives rise to specialized biological structures of specific shape and function in early embryonic development. Morphogenesis is under strict genetic control, but shape evolution itself is a physical process. Here we report the results of experimental and modeling biophysical studies on in vitro biological structure formation. Experimentally, by controlling the interaction between cells and their embedding matrices, we were able to build living structures of definite geometry. The experimentally observed shape evolution was reproduced by Monte Carlo simulations, which also shed light on the biophysical basis of the process. Our work suggests a novel way to engineer biological structures of controlled shape. 相似文献
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I. I. Gogonin 《Thermophysics and Aeromechanics》2009,16(1):111-118
It has been experimentally proved that heat transfer at boiling appears to be the problem with the conjugated boundary conditions.
Heat transfer and critical heat fluxes at boiling depend both on physical properties of the boiling liquid and on the number
of characteristics of the heat transferring wall.
Various experimental data of the problem of boiling liquid with various physical properties have been analysed. To eliminate
or minimize influence of the properties of the cooled wall on the value of critical heat transfer, the data obtained at boiling
on the thick cooled wall only from the stainless steel or nichrome are considered. To eliminate effect of capillary forces
specific linear size of heat transferring wall satisfied the condition ≥ 2.0. 相似文献
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Diego Julio Cirilo-Lombardo 《Physics of Particles and Nuclei Letters》2016,13(1):26-31
As it is well known, a certain lack of theoretical understanding of the mechanisms governing the various phenomena exists in several areas of physics. In particular, it concerns those which involve transport of charged particles in low dimensions. In this work the physics of the 2-dimensional charge transport with parallel (in plane) magnetic field is analyzed from the geometrical and algebraic viewpoint making emphasis of how the physical interpretation arises from a consistent mathematical formulation of the problem. As a new result of this investigation with respect to the current literature we explicitly show that: (i) the specific form of the low dimensional Dirac equation enforces the field solution to fulfil the Majorana condition, (ii) the quantum Hall effect is successfully explained, (iii) a new topological effect (as the described by the Aharonov–Casher theorems) is presented and (iv) the link with supersymmetrical models is briefly commented. 相似文献
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研究了量子态在一条均匀耦合的反铁磁自旋链中传输时, 信道中自旋激发数变化对其传输性质的影响. 利用信息流方法分析输出端粒子的算符演化动力学, 获得了量子态传输的平均保真度与信道自旋初态之间的关系. 结果表明, 平均保真度的大小只依赖于信道中自旋激发数的奇偶性. 通过比较在奇偶激发信道中获得的最大平均保真度, 构建了优化信道来提升量子态在自旋链中的传输质量. 进一步分析了纠缠在激发信道中的传输情况, 发现纠缠的传输质量不仅和信道中自旋激发的具体个数有关, 还取决于激发自旋的初始排列. 特别地, 当信道中自旋无激发或全部激发时, 纠缠传输的大小和持续时间都优于其他的激发信道. 上述研究结果有助于在实际系统中搭建适合量子态和纠缠传输的量子信道. 相似文献
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该文以成都市浣花溪公园为研究对象,通过对景观空间中声环境的综合研究探究其声景观特性,以此作为营造城市声环境的有效依据。文章首先通过声压级、声景观多样性指数和清晰度指数来定量探讨公园中17种景观空间下的声环境异同;然后以声景观舒适度指数和重要性-满意度-清晰度模型对12种声音类型进行主客观评价;最后通过声景观提升指数综合反映各景观空间下声景观的提升重点。研究发现,声景观会受到基底-覆盖-围合层面的不同类型和组合的影响,尤其在建设面开敞和绿色半开敞或绿色半封闭空间中得到社会声和自然声最为明显;声景提升应重点关注风声、鸟声、水声、昆虫声和音响声在对应景观空间中的利用。 相似文献
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Milan Paluš 《Contemporary Physics》2013,54(6):307-348
Principles and applications of statistical testing as a tool for inference of underlying mechanisms from experimental time series are discussed. The computational realizations of the test null hypothesis known as the surrogate data are introduced within the context of discerning nonlinear dynamics from noise, and discussed in examples of testing for nonlinearity in atmospheric dynamics, solar cycle and brain signals. The concept is further generalized for detection of directional interactions, or causality in bivariate time series. 相似文献
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Foster K.R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(1):15-23
This paper reviews thermal and nonthermal mechanisms of interaction between radiofrequency (RF) fields and biological systems, focusing on pulsed fields with high peak power but low duty cycle. Models with simplified geometry are used to illustrate the coupling between external electromagnetic fields and the body, and with cellular and subcellular structures. Mechanisms of interaction may be linear or nonlinear with field strength, and thermal or nonthermal. Each mechanism is characterized by a threshold field strength (below which no observable response is produced) and time constant of response. Several classes of nonthermal mechanisms of interaction are well established; however, the anticipated thresholds for producing observable effects are expected to be very high. The bioeffects literature contains many open questions, including many reports of effects that are not clearly interpretable in terms of the mechanisms discussed in this paper 相似文献
10.
Peter Tullet 《辐射效应与固体损伤》2013,168(5):336-343
Observations were made of impulse events in Poynting flux calculated from electric and magnetic disturbances encountered by the Polar satellite when on high-latitude field-lines in the magnetotail. These were found to be coincident within±6 min with impulsive spikes in cosmic radio background absorption in the D region of the ionosphere as detected by the Imaging Riometer for Ionospheric Studies riometer in Finland. They were also coincident with substorm onset at the same geomagnetic latitude as determined by a change of gradient in International Monitor for Auroral Geomagnetic Effects’ X-component magnetograms. The interpretation of the observations was that magnetospheric compression waves from the geomagnetic equator region of the magnetotail were coupling to progressively initiate field-guided Alfvén shear waves towards higher geomagnetic latitudes over a large volume of the magnetosphere. The study suggested that they were then able either directly or indirectly to ionise the D region of the ionosphere and in the process to cut deep electrically conducting channels between the magnetosphere and the ionosphere through which currents could flow and initiate the characteristic signature of geomagnetic substorms in ground magnetograms. 相似文献
11.
BL Lacs天体的辐射谱变化、多波段的相关性及偏振的特性为研究各辐射分量的内禀相互关联提供重要的信息.本文用收集了RBLs和XBLs的红移、中心黑洞质量,统计得到RBLs天体的红移大于XBLs天体,RBLs天体的平均中心黑洞质量小于XBLs天体的平均中心黑洞质量.本文还收集了低态时射电波段、红外波段、光学波段及X射线波段的辐射流量,并分析了它们之间的相关性,及其与红移的相关性.本文的结果支持了RBLs和XBLs可作为BL Lac天体的有效分类标准的观点,并且表明它们的物理性质可能存在差异,而非选择效应的
关键词:
BL Lac天体
多波段辐射流量 相似文献
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Design of square-shaped heat flux cloaks and concentrators using method of coordinate transformation
A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed theoretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flux in these devices can be modulated as desired. Using the method of coordinate transformation, the inhomogeneous and anisotropic thermal conductivity in the transformation region have been acquired. Two-dimensional finite element simulations were performed to confirm the theoretical results. 相似文献
16.
Sandip P. Trivedi 《Pramana》2004,63(4):777-783
We discuss a recent proposal to construct de Sitter vacua in string theory. It is based on flux compactifications in string
theory where all the moduli are stabilised and supersymmetry is broken with control. The resulting picture is that of a complicated
landscape with many vacua of widely varying values for the cosmological constant. 相似文献
17.
Christian Gruber Nicolas Macris Alain Messager Daniel Ueltschi 《Journal of statistical physics》1997,86(1-2):57-108
The Falicov-Kimball model is a lattice model of itinerant spinless fermions (electrons) interacting by an on-site potential with classical particles (ions). We continue the investigations of the crystalline ground states that appear for various filling of electrons and ions for large coupling. We investigate the model for square as well as triangular lattices. New ground states are found and the effects of a magnetic flux on the structure of the phase diagram are studied. The flux phase problem where one has to find the optimal flux configurations and the nuclei configurations is also solved in some cases. Finally we consider a model where the fermions are replaced by hard-core bosons. This model also has crystalline ground states. Therefore their existence does not require the Pauli principle, but only the on-site hard-core constraint for the itinerant particles. 相似文献
18.
Constructing reduced model for complex physical systems via interpolation and neural networks 下载免费PDF全文
The work studies model reduction method for nonlinear systems based on proper orthogonal decomposition (POD)and discrete empirical interpolation method (DEIM). Instead of using the classical DEIM to directly approximate thenonlinear term of a system, our approach extracts the main part of the nonlinear term with a linear approximation beforeapproximating the residual with the DEIM. We construct the linear term by Taylor series expansion and dynamic modedecomposition (DMD), respectively, so as to obtain a more accurate reconstruction of the nonlinear term. In addition, anovel error prediction model is devised for the POD-DEIM reduced systems by employing neural networks with the aid oferror data. The error model is cheaply computable and can be adopted as a remedy model to enhance the reduction accuracy.Finally, numerical experiments are performed on two nonlinear problems to show the performance of the proposed method. 相似文献
19.
For a mesoscopic radio frequency superconducting quantum
interference device (rfSQUID), at a degeneracy point, the system
reduces to a quantum two-state system which can be used as a flux
qubit. When the noise environment is equivalent to a harmonic
oscillators bath, by virtue of an operator-norm measure for the
short time decoherence, this paper investigates the initial
decoherence of the flux qubit operating in the ohmic noise
environment and illustrates its property by means of the numerical
evaluation. 相似文献
20.
Recent developments in microcanonical multifractal formalism have lead to a sensible improvement in the numerical techniques for the determination of the multifractal characteristics of real signals. With the aid of these techniques, we have found empirical evidence of a common multifractal signature in six very different systems, ranging from stock market time series to sea surface temperature records. These systems are not only found to be multifractal, but their singularity spectra are coincident. We propose an explanation of this striking coincidence in terms of a cascade process and analyze its consequences. 相似文献