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statistical mechanics

Yang Liu, Xiao Yuan, Ming-Han Li, Weijun Zhang, Qi Zhao, Jiaqiang Zhong, Yuan Cao, Yu-Huai Li, Luo-Kan Chen, Hao Li, Tianyi Peng, Yu-Ao Chen, Cheng-Zhi Peng, Sheng-Cai Shi, Zhen Wang, Lixing You, Xiongfeng Ma, Jingyun Fan, Qiang Zhang, Jian-Wei Pan
Quantum mechanics provides the means of generating genuine randomness that is impossible with deterministic classical processes. Remarkably, the unpredictability of randomness can be certified in a manner that is independent of implementation devices. Here, we present an experimental study of device-independent quantum random number generation based on a detection-loophole-free Bell test with entangled photons. In the randomness analysis, without the independent identical distribution assumption, we consider the worst case scenario that the adversary launches the most powerful attacks against the quantum adversary...
January 5, 2018: Physical Review Letters
Federico Elias-Wolff, Martin Lindén, Alexander P Lyubartsev, Erik G Brandt
Membrane curvature sensing, where the binding free energies of membrane-associated molecules depend on the local membrane curvature, is a key factor to modulate and maintain the shape and organization of cell membranes. However, the microscopic mechanisms are not well understood, partly due to absence of efficient simulation methods. Here, we describe a method to compute the curvature dependence of the binding free energy of a membrane-associated probe molecule that interacts with a buckled membrane, which has been created by lateral compression of a flat bilayer patch...
January 19, 2018: Journal of Chemical Theory and Computation
Laura K Triantafylidis, Jenna S Clemons, Emily P Peron, John Roefaro, Kristin M Zimmerman
BACKGROUND: Case reports have demonstrated that dual use of cholinesterase inhibitors (ChIs) and urinary anticholinergics (UAChs) in older adults may be associated with delusions, aggression, changes in cognition, and anxiety, which typically resolve on drug discontinuation. Despite opposing mechanisms of action, these drugs continue to be co-prescribed. OBJECTIVE: This systematic review evaluates cognitive and functional outcomes of dual use of ChIs and UAChs and describes its prevalence...
January 19, 2018: Drugs & Aging
Jessica C Delmoral, Sandra M Rua Ventura, João Manuel Rs Tavares
Quantification of the anatomic and functional aspects of the tongue is pertinent to analyse the mechanisms involved in speech production. Speech requires dynamic and complex articulation of the vocal tract organs, and the tongue is one of the main articulators during speech production. Magnetic resonance imaging has been widely used in speech-related studies. Moreover, the segmentation of such images of speech organs is required to extract reliable statistical data. However, standard solutions to analyse a large set of articulatory images have not yet been established...
January 1, 2018: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
Qiang Liu, Jun Zhang, Shu-Chun Sun, Fei Wang
The finite element model is one of the most important methods in study of modern spinal biomechanics, according to the needs to simulate the various states of the spine, calculate the stress force and strain distribution of the different groups in the state, and explore its principle of mechanics, mechanism of injury, and treatment effectiveness. In addition, in the study of the pathological state of the spine, the finite element is mainly used in the understanding the mechanism of lesion location, evaluating the effects of different therapeutic tool, assisting and completing the selection and improvement of therapeutic tool, in order to provide a theoretical basis for the rehabilitation of spinal lesions...
February 25, 2017: Zhongguo Gu Shang, China Journal of Orthopaedics and Traumatology
Sabrina Yesmin, Syed Jamil Abdal, Aminur Rahman, Md Nazrul Islam, Alamgir Mustak Ahammad, Shamim Ahmed, Md Abu Shahin, Minhaj Rahim Chowdhury, Syed Atiqul Haq
AIM: Inflammatory back pain (IBP) is the earliest symptom of axial and other forms of spondyloarthritis (SpA). However, there are no published data on prevalence of IBP among patients suffering from chronic low back pain (CLBP) in Bangladesh. In this study, we estimated the prevalence of IBP and the subtypes of SpA in a tertiary hospital in Bangladesh. METHODS: This 1 year cross-sectional study was conducted among 240 CLBP patients in a rheumatology outpatient clinic...
January 18, 2018: International Journal of Rheumatic Diseases
Chunhong Liu, Zhiwei Qin, Xiuyan Zhou, Ming Xin, Chunhua Wang, Dong Liu, Shengnan Li
BACKGROUND: Cucumber downy mildew is among the most important diseases that can disrupt cucumber production. Propamocarb, also known as propyl-[3-(dimethylamino)propyl]carbamate (PM), is a systemic carbamate fungicide pesticide that is widely applied in agricultural production because of its high efficiency of pathogens control, especially cucumber downy mildew. However, residual PM can remain in cucumbers after the disease has been controlled. To explore the molecular mechanisms of PM retention, cucumber cultivars 'D9320' (with the highest residual PM content) and 'D0351' (lowest residual PM content) were studied...
January 18, 2018: BMC Plant Biology
Madina Agénor, Ashley Pérez, Sarah M Peitzmeier, Sonya Borrero
OBJECTIVE: To ascertain the magnitude and potential mechanisms of racial/ethnic disparities in initiating and completing the 3-dose human papillomavirus (HPV) vaccine among U.S. women in the post-Affordable Care Act era. DESIGN: Using 2015 National Health Interview Survey data, we used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between race/ethnicity and HPV vaccination initiation and completion among black, Latina, Asian, and white U...
January 18, 2018: Ethnicity & Health
David Santillán, Juan-Carlos Mosquera, Luis Cueto-Felgueroso
Hydraulic fracture trajectories in rocks and other materials are highly affected by spatial heterogeneity in their mechanical properties. Understanding the complexity and structure of fluid-driven fractures and their deviation from the predictions of homogenized theories is a practical problem in engineering and geoscience. We conduct a Monte Carlo simulation study to characterize the influence of heterogeneous mechanical properties on the trajectories of hydraulic fractures propagating in elastic media. We generate a large number of random fields of mechanical properties and simulate pressure-driven fracture propagation using a phase-field model...
November 2017: Physical Review. E
Wen Zhang, Peiqing Liu, Hao Guo, Jinjun Wang
The permutation entropy and the statistical complexity are employed to study the boundary-layer transition induced by the surface roughness. The velocity signals measured in the transition process are analyzed with these symbolic quantifiers, as well as the complexity-entropy causality plane, and the chaotic nature of the instability fluctuations is identified. The frequency of the dominant fluctuations has been found according to the time scales corresponding to the extreme values of the symbolic quantifiers...
November 2017: Physical Review. E
Bryan Iotti, Alberto Antonioni, Seth Bullock, Christian Darabos, Marco Tomassini, Mario Giacobini
The study of complex networks, and in particular of social networks, has mostly concentrated on relational networks, abstracting the distance between nodes. Spatial networks are, however, extremely relevant in our daily lives, and a large body of research exists to show that the distances between nodes greatly influence the cost and probability of establishing and maintaining a link. A random geometric graph (RGG) is the main type of synthetic network model used to mimic the statistical properties and behavior of many social networks...
November 2017: Physical Review. E
Rodrigo Freitas, Timofey Frolov, Mark Asta
Molecular dynamics (MD) simulations are employed to investigate the capillary fluctuations of steps on the surface of a model metal system. The fluctuation spectrum, characterized by the wave number (k) dependence of the mean squared capillary-wave amplitudes and associated relaxation times, is calculated for 〈110〉 and 〈112〉 steps on the {111} surface of elemental copper near the melting temperature of the classical potential model considered. Step stiffnesses are derived from the MD results, yielding values from the largest system sizes of (37±1)meV/A[over ˚] for the different line orientations, implying that the stiffness is isotropic within the statistical precision of the calculations...
October 2017: Physical Review. E
Bartłomiej Dybiec, Ewa Gudowska-Nowak, Igor M Sokolov
We investigate the distribution of potential and kinetic energy in stationary states of the linearly damped stochastic oscillator driven by Lévy noises. In the long time limit distributions of kinetic and potential energies of the oscillator follow the power-law asymptotics and do not fulfill the equipartition theorem. The partition of the mechanical energy is controlled by the damping coefficient. In the limit of vanishing damping a stochastic analog of the equipartition theorem can be proposed, namely, the statistical properties of potential and kinetic energies attain distributions characterized by the same widths...
October 2017: Physical Review. E
J Javier Brey, M I García de Soria, P Maynar
A Boltzmann-like kinetic equation for a quasi-two-dimensional gas of hard spheres is derived. The system is confined between two parallel hard plates separated a distance between one and two particle diameters. An entropy Lyapunov function for the equation is identified. In addition to the usual Boltzmann expression, it contains a contribution associated to the confinement of the particles. The steady properties of the system agree with equilibrium statistical mechanics results. Equations describing the energy transfer between the degrees of freedom parallel and perpendicular to the confining plates are obtained for some simple initial configurations...
October 2017: Physical Review. E
Raz Halifa Levi, Yacov Kantor, Mehran Kardar
A polymer repelled by unfavorable interactions with a uniform flat surface may still be pinned to attractive edges and corners. This is demonstrated by considering adsorption of a two-dimensional ideal polymer to an attractive corner of a repulsive wedge. The well-known mapping between the statistical mechanics of an ideal polymer and the quantum problem of a particle in a potential is then used to analyze the singular behavior of the unbinding transition of the polymer. The divergence of the localization length is found to be governed by an exponent that varies continuously with the angle (when reflex)...
December 2017: Physical Review. E
Alan R Denton
Interparticle interactions and bulk properties of colloidal suspensions can be substantially modified by the addition of nanoparticles. Extreme asymmetries in size and charge between colloidal particles and nanoparticles present severe computational challenges to molecular-scale modeling of such complex systems. We present a statistical mechanical theory of effective electrostatic interactions that can greatly ease large-scale modeling of charged colloid-nanoparticle mixtures. By applying a sequential coarse-graining procedure, we show that a multicomponent mixture of charged colloids, nanoparticles, counterions, and coions can be mapped first onto a binary mixture of colloids and nanoparticles and then onto a one-component model of colloids alone...
December 2017: Physical Review. E
Lorna R M Wilson, Keith I Hopcraft
The problem of zero crossings is of great historical prevalence and promises extensive application. The challenge is to establish precisely how the autocorrelation function or power spectrum of a one-dimensional continuous random process determines the density function of the intervals between the zero crossings of that process. This paper investigates the case where periodicities are incorporated into the autocorrelation function of a smooth process. Numerical simulations, and statistics about the number of crossings in a fixed interval, reveal that in this case the zero crossings segue between a random and deterministic point process depending on the relative time scales of the periodic and nonperiodic components of the autocorrelation function...
December 2017: Physical Review. E
Alexandr Nasedkin, Jan Davidsson, Antti J Niemi, Xubiao Peng
We propose a computationally effective approach that builds on Landau mean-field theory in combination with modern nonequilibrium statistical mechanics to model and interpret protein dynamics and structure formation in small- to wide-angle x-ray scattering (S/WAXS) experiments. We develop the methodology by analyzing experimental data in the case of Engrailed homeodomain protein as an example. We demonstrate how to interpret S/WAXS data qualitatively with a good precision and over an extended temperature range...
December 2017: Physical Review. E
Avanish Kumar, Chaitanya Narayanam, Rajesh Khanna, Sanjay Puri
We address in detail the problem of true morphological phase separation (MPS) in three-dimensional or (2+1)-dimensional unstable thin liquid films (>100nm) under the influence of gravity. The free-energy functionals of these films are asymmetric and show two points of common tangency, which facilitates the formation of two equilibrium phases. Three distinct patterns formed by relative preponderance of these phases are clearly identified in "true MPS". Asymmetricity induces two different pathways of pattern formation, viz...
December 2017: Physical Review. E
Ali Ü C Hardal, Nur Aslan, C M Wilson, Özgür E Müstecaplıoğlu
We propose a quantum heat engine composed of two superconducting transmission line resonators interacting with each other via an optomechanical-like coupling. One resonator is periodically excited by a thermal pump. The incoherently driven resonator induces coherent oscillations in the other one due to the coupling. A limit cycle, indicating finite power output, emerges in the thermodynamical phase space. The system implements an all-electrical analog of a photonic piston. Instead of mechanical motion, the power output is obtained as a coherent electrical charging in our case...
December 2017: Physical Review. E
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