Hasil untuk "physics.comp-ph"

A. Airapetian, V. Dodonov, L. Micu et al.

A. Dautry‐Varsat, A. Ciechanover, H. Lodish

A. Lardner

The effect of alterations in extracellular pH on cellular and humoral immune function is reviewed. Because acidic pH predominates at inflammatory loci and other sites of immune activity, most studies to date focus on the effect of acidic rather than alkaline pH. Investigations on polymorphonuclear leukocytes demonstrate mainly inhibition of chemotaxis, respiratory activity, and bactericidal capacity at reduced pH. Evidence of impaired lymphocyte cytotoxicity and proliferation at acidic pH is also beginning to emerge. Many of the clinical acidoses are accompanied similarly by immunodeficiency. Studies on macrophages and eosinophils are few and inconclusive. A small number of studies demonstrate acid‐induced activation of complement proteins and the alternative complement pathway, plus increased antibody‐binding to leukocytes at lowered pH. A differential effect of acidic pH on humoral and cellular immunity may, therefore, exist. Increasing recognition of the significance of extracellular pH in relation to immune function warrants further studies in this presently incomplete but rewarding field.

A. Richter, G. Paschew, Stephan Klatt et al.

Stimuli-responsive hydrogels are materials with great potential for development of active functionalities in fluidics and micro-fluidics. Based on the current state of research on pH sensors, hydrogel sensors are described qualitatively and quantitatively for the first time. The review introduces the physical background of the special properties of stimuli-responsive hydrogels. Following, transducers are described which are able to convert the non-electrical changes of the physical properties of stimuli-responsive hydrogels into an electrical signal. Finally, the specific sensor properties, design rules and general conditions for sensor applications are discussed.

R. Rozendal, H. Hamelers, C. Buisman

A. Walker, S. Duncan, E. C. McWilliam Leitch et al.

M. Högberg, P. Högberg, D. Myrold

S. Kemmitt, D. Wright, K. Goulding et al.

S. Dai, P. Ravi, K. Tam

Dengyu Pan, Jingchun Zhang, Zhen Li et al.

Huan Meng, Min Xue, T. Xia et al.

I. Yu, Wei Zhang, H. Holdaway et al.

Jonathan W. Wojtkowiak, Daniel Verduzco, K. Schramm et al.

Maksim Radionov, Daria Popova-Gorelova

Improving our understanding of electron dynamics is essential for advancing energy transfer, optoelectronics, light harvesting systems and quantum computing. Recent developments in attosecond x-ray sources provide the fundamental possibility of observing these dynamics with atomic-scale resolution. However, connecting a time-resolved signal to dynamics is challenging due to the broad bandwidth of an attosecond probe pulse. This makes exploring the capabilities of different attosecond imaging techniques crucial. Here, we propose attosecond momentum-resolved resonant inelastic x-ray scattering as a prominent technique for tracking ultrafast dynamics. We demonstrate that the scattering signal contains an information about the instantaneous distribution of charge density across the scattering atoms. To illustrate this, we consider scattering from an $α$-sexithiophene molecule, in which coupled electron-hole dynamics are excited.

Arnaud E Felber, Marie-Hélène Dufresne, J. Leroux

Wen Shi, Xiaohua Li, Huimin Ma

Siu A. Chin

It is widely known that there is no sign problem in Path Integral Monte Carlo (PIMC) simulations of fermions in one dimension. Yet, as far as the author is aware, there is no direct proof of this in the literature. This work shows that the $sign$ of the $N$-fermion anti-symmetric free propagator is given by the product of all possible pairs of particle separations, or relative displacements. For a non-vanishing closed-loop product of such propagators, as required by PIMC, all relative displacements from adjacent propagators are paired into perfect squares, and therefore the loop product must be positive, but only in one dimension. By comparison, permutation sampling, which does not evaluate the determinant of the anti-symmetric propagator exactly, remains plagued by a low-level sign problem, even in one dimension.

G. Elmasry, Da‐Wen Sun, P. Allen

Zechen Wu, Yi Zhu, Weiya Huang et al.

Lev Barash, Arman Babakhani, Itay Hen

We present a universal parameter-free quantum Monte Carlo (QMC) algorithm designed to simulate arbitrary spin-$1/2$ Hamiltonians. To ensure the convergence of the Markov chain to equilibrium for every conceivable case, we devise a clear and simple automated protocol that produces QMC updates that are provably ergodic and satisfy detailed balance. We demonstrate the applicability and versatility of our method by considering several illustrative examples, including the simulation of the XY model on a triangular lattice, the toric code, and random $k$-local Hamiltonians. We have made our program code freely accessible on GitHub.