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https://www.readbyqxmd.com/read/28109232/thermodynamics-and-simulation-of-hard-sphere-fluid-and-solid-kinetic-monte-carlo-method-versus-standard-metropolis-scheme
#1
E A Ustinov
The paper aims at a comparison of techniques based on the kinetic Monte Carlo (kMC) and the conventional Metropolis Monte Carlo (MC) methods as applied to the hard-sphere (HS) fluid and solid. In the case of the kMC, an alternative representation of the chemical potential is explored [E. A. Ustinov and D. D. Do, J. Colloid Interface Sci. 366, 216 (2012)], which does not require any external procedure like the Widom test particle insertion method. A direct evaluation of the chemical potential of the fluid and solid without thermodynamic integration is achieved by molecular simulation in an elongated box with an external potential imposed on the system in order to reduce the particle density in the vicinity of the box ends...
January 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28109217/the-hydration-structure-of-carbon-monoxide-by-ab-initio-methods
#2
Ernest Awoonor-Williams, Christopher N Rowley
The solvation of carbon monoxide (CO) in liquid water is important for understanding its toxicological effects and biochemical roles. In this paper, we use ab initio molecular dynamics (AIMD) and CCSD(T)-F12 calculations to assess the accuracy of the Straub and Karplus molecular mechanical (MM) model for CO(aq). The CCSD(T)-F12 CO-H2O potential energy surfaces show that the most stable structure corresponds to water donating a hydrogen bond to the C center. The MM-calculated surface incorrectly predicts that the O atom is a stronger hydrogen bond acceptor than the C atom...
January 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28106892/theoretical-study-on-the-need-for-laser-iridotomy-in-an-implantable-collamer-lens-with-a-hole-using-computational-fluid-dynamics
#3
T Kawamorita, K Shimizu, N Shoji
PurposeAlthough one of the advantages of the Hole-ICL implantation is that laser iridotomy (LI) is unnecessary, the evidence have not been reported from the viewpoint of aqueous humor circulation. We investigated the effect of laser iridotomy (LI) on the fluid dynamics of aqueous humor in an implantable collamer lens (ICL) with a central hole, that is, a Hole-ICL using computational fluid dynamics.MethodsA fluid dynamics simulation was performed using the thermal-hydraulic analysis software FloEFD (Mentor Graphics Corp...
January 20, 2017: Eye
https://www.readbyqxmd.com/read/28106683/collaboration-between-academia-and-practice-interprofessional-crises-leadership-and-disaster-management
#4
Cheryl Hoying, Sharon Farra, Rosalie Mainous, Rebecca Baute, Matthew Gneuhs
An innovative interprofessional disaster preparedness program was designed and implemented through an academic-practice partnership between a large midwestern children's hospital and a community-based state university. This course was part of a constellation of courses developed in response to Presidential Directive (HSPD) 8, a mandate to standardize disaster response training that was issued after the inefficiencies following Hurricane Katrina. A hybrid immersive and didactic approach was used to train senior leadership and frontline clinicians...
February 2017: Journal of Nursing Administration
https://www.readbyqxmd.com/read/28106328/on-the-influence-of-the-protonation-states-of-active-site-residues-on-ache-reactivation-a-qm-mm-approach
#5
Thomas Driant, Florian Nachon, Cyril Ollivier, Pierre-Yves Renard, Etienne Derat
Acetylcholinesterase (AChE) is an enzyme of the serine hydrolase superfamily and a mediator of the signal transmission at cholinergic synapses catalysing acetylcholine cleavage into an acetate and a choline. This enzyme is vulnerable to covalent inhibition by organophosphate compounds (like VX). The covalent inhibition of AChE does not revert spontaneously and in order to restore catalytic activity known reactivator compounds have limited action. Simulations of VX-inhibited AChE reactivation by pralidoxime, a classical reactivator, were performed by QM/MM...
January 19, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28103440/carbon-nanotubes-mediate-fusion-of-lipid-vesicles
#6
Ramachandra Moorthy Bhaskara, Stephanie M Linker, Martin Vögele, Juergen Koefinger, Gerhard Hummer
The fusion of lipid membranes is opposed by high energetic barriers. In living organisms, complex protein machineries carry out this biologically essential process. Here we show that membrane-spanning carbon nanotubes (CNTs) can trigger spontaneous fusion of small lipid vesicles. In coarse-grained molecular dynamics simulations, we find that a CNT bridging between two vesicles locally perturbs their lipid structure. Their outer leaflets merge as the CNT pulls lipids out of the membranes, creating an hourglass-shaped fusion intermediate with still intact inner leaflets...
January 19, 2017: ACS Nano
https://www.readbyqxmd.com/read/28102956/experimental-verification-of-4d-monte-carlo-simulations-of-dose-delivery-to-a-moving-anatomy
#7
Sara Gholampourkashi, Miro Vujicic, Jason Belec, Joanna E Cygler, Emily Heath
PURPOSE: To evaluate a novel 4D Monte Carlo simulation tool by comparing calculations to physical measurements using a respiratory motion phantom. METHODS: We used a dynamic Quasar phantom in both stationary and breathing states (sinusoidal motion of amplitude of 1.8 cm and period of 3.3 s) for dose measurements on an Elekta Agility linear accelerator. Gafchromic EBT3 film and the RADPOS 4D dosimetry system were placed inside the lung insert of the phantom to measure dose profiles and point-dose values at the center of the spherical tumor inside the insert...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102953/air-kerma-strength-determination-of-an-hdr-192-ir-source-including-a-geometric-sensitivity-study-of-the-seven-distance-method
#8
Blake R Smith, John A Micka, Manik Aima, Larry A DeWerd, Wesley S Culberson
PURPOSE: To perform an in-air air-kerma strength (SK) calibration of the Bebig model Ir2.A85-2 192Ir high-dose rate (HDR) brachytherapy source manufactured by Mallinckrodt Medical (Westerduinweg, Germany) with the NIST-traceable seven-distance technique established by the University of Wisconsin. A comparison was made between the reference air-kerma rate (RAKR) reported on a certificate from the Physikalisch-Technische Bundesanstalt (Berlin, Germany) (PTB) primary laboratory and the SK determined at the University of Wisconsin Madison Radiation Research Center (UWMRRC)...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102351/origins-of-ripples-in-cvd-grown-few-layered-mos2-structures-under-applied-strain-at-atomic-scales
#9
Jin Wang, Raju R Namburu, Madan Dubey, Avinash M Dongare
The potential of the applicability of two-dimensional molybdenum disulfide (MoS2) structures, in various electronics, optoelectronics, and flexible devices requires a fundamental understanding of the effects of strain on the electronic, magnetic and optical properties. Particularly important is the recent capability to grow large flakes of few-layered structures using chemical vapor deposition (CVD) wherein the top layers are relatively smaller in size than the bottom layers, resulting in the presence of edges/steps across adjacent layers...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28101675/operative-planning-aid-for-optimal-endoscopic-third-ventriculostomy-entry-points-in-pediatric-cases
#10
Zsolt Zador, David J Coope, Abteen Mostofi, Ian D Kamaly-Asl
OBJECT: Endoscopic third ventriculostomy (ETV) uses anatomical spaces of the ventricular system to reach the third ventricle floor and create an alternative pathway for cerebrospinal fluid flow. Optimal ETV trajectories have been previously proposed in the literature, designed to grant access to the third ventricle floor without a displacement of eloquent periventricular structures. However, in hydrocephalus, there is a significant variability to the configuration of the ventricular system, implying that the optimal ETV trajectory and cranial entry point needs to be planned on a case-by-case basis...
January 18, 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/28101416/light-field-otoscope-design-for-3d-in-vivo-imaging-of-the-middle-ear
#11
Noah Bedard, Timothy Shope, Alejandro Hoberman, Mary Ann Haralam, Nader Shaikh, Jelena Kovačević, Nikhil Balram, Ivana Tošić
We present a light field digital otoscope designed to measure three-dimensional shape of the tympanic membrane. This paper describes the optical and anatomical considerations we used to develop the prototype, along with the simulation and experimental measurements of vignetting, field curvature, and lateral resolution. Using an experimental evaluation procedure, we have determined depth accuracy and depth precision of our system to be 0.05-0.07 mm and 0.21-0.44 mm, respectively. To demonstrate the application of our light field otoscope, we present the first three-dimensional reconstructions of tympanic membranes in normal and otitis media conditions, acquired from children who participated in a feasibility study at the Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center...
January 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28100294/why-do-we-remember-the-communicative-function-of-episodic-memory
#12
Johannes Mahr, Gergely Csibra
Episodic memory has been analyzed in a number of different ways in both philosophy and psychology, and most controversy has centered on its self-referential, 'autonoetic' character. Here, we offer a comprehensive characterization of episodic memory in representational terms, and propose a novel functional account on this basis. We argue that episodic memory should be understood as a distinctive epistemic attitude taken towards an event simulation. On this view, episodic memory has a metarepresentational format and should not be equated with beliefs about the past...
January 19, 2017: Behavioral and Brain Sciences
https://www.readbyqxmd.com/read/28098313/the-glass-transition-and-interfacial-dynamics-of-single-strand-fibers-of-polymers
#13
Hyun Woo Cho, Bong June Sung
We investigate the glass transition and interfacial dynamics of single strand fibers of flexible polymers by employing molecular dynamics (MD) simulations along with a coarse grained model. While the polymer fiber has drawn significant attention due to its applicability in tissue engineering and stretchable electronics, its dynamic properties, especially the glass transition temperature (Tg), are yet to be understood at the molecular level. For example, there has been a controversy on the effect of the polymer fiber radius (R) on Tg: Tg decreased with a decrease in R for some polymer fibers, whereas Tg of other polymer fibers was not sensitive to R...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28097753/fully-copper-exchanged-high-silica-lta-zeolites-as-unrivaled-hydrothermally-stable-nh3-scr-catalysts
#14
Taekyung Ryu, Nak Ho Ahn, Seungwan Seo, Jung Cho, Hyojun Kim, Donghui Jo, Gi Tae Park, Pyung Soon Kim, Chang Hwan Kim, Elliott L Bruce, Paul A Wright, In-Sik Nam, Suk Bong Hong
Diesel engine technology is still the most effective solution to meet tighter CO2 regulations in the mobility and transport sector. In implementation of fuel-efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NOx ) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high-silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NOx reduction with NH3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu-SSZ-13 catalyst cannot overcome owing to thermal deactivation...
January 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28097218/energy-penetration-into-arrays-of-aligned-nanowires-irradiated-with-relativistic-intensities-scaling-to-terabar-pressures
#15
Clayton Bargsten, Reed Hollinger, Maria Gabriela Capeluto, Vural Kaymak, Alexander Pukhov, Shoujun Wang, Alex Rockwood, Yong Wang, David Keiss, Riccardo Tommasini, Richard London, Jaebum Park, Michel Busquet, Marcel Klapisch, Vyacheslav N Shlyaptsev, Jorge J Rocca
Ultrahigh-energy density (UHED) matter, characterized by energy densities >1 × 10(8) J cm(-3) and pressures greater than a gigabar, is encountered in the center of stars and inertial confinement fusion capsules driven by the world's largest lasers. Similar conditions can be obtained with compact, ultrahigh contrast, femtosecond lasers focused to relativistic intensities onto targets composed of aligned nanowire arrays. We report the measurement of the key physical process in determining the energy density deposited in high-aspect-ratio nanowire array plasmas: the energy penetration...
January 2017: Science Advances
https://www.readbyqxmd.com/read/28096708/evaluating-medical-students-proficiency-with-a-handheld-ophthalmoscope-a-pilot-study
#16
Gregory Gilmour, James McKivigan
INTRODUCTION: Historically, testing medical students' skills using a handheld ophthalmoscope has been difficult to do objectively. Many programs train students using plastic models of the eye which are a very limited fidelity simulator of a real human eye. This makes it difficult to be sure that actual proficiency is attained given the differences between the various models and actual patients. The purpose of this article is to introduce a method of testing where a medical student must match a patient with his/her fundus photo, ensuring objective evaluation as well as developing skills on real patients which are more likely to transfer into clinical practice directly...
2017: Advances in Medical Education and Practice
https://www.readbyqxmd.com/read/28096110/bra-sizing-and-the-plastic-surgery-herd-effect-are-breast-augmentation-patients-getting-accurate-information
#17
Christopher R Costa, Kevin H Small, William P Adams
BACKGROUND: Bra sizing is a common method to preoperatively select implants for breast augmentation; however, no series has analyzed the accuracy of this modality postoperatively. Alternatively, previous investigations have validated the accuracy and utility of three-dimensional (3D) imaging for preoperative simulation in breast augmentation. OBJECTIVES: This investigation utilizes 3D analysis to determine if preoperative bra sizing provides equivocal information compared to surgical 3D simulation for patient education and planning prior to a breast augmentation...
January 17, 2017: Aesthetic Surgery Journal
https://www.readbyqxmd.com/read/28095441/moving-model-test-of-high-speed-train-aerodynamic-drag-based-on-stagnation-pressure-measurements
#18
Mingzhi Yang, Juntao Du, Zhiwei Li, Sha Huang, Dan Zhou
A moving model test method based on stagnation pressure measurements is proposed to measure the train aerodynamic drag coefficient. Because the front tip of a high-speed train has a high pressure area and because a stagnation point occurs in the center of this region, the pressure of the stagnation point is equal to the dynamic pressure of the sensor tube based on the obtained train velocity. The first derivation of the train velocity is taken to calculate the acceleration of the train model ejected by the moving model system without additional power...
2017: PloS One
https://www.readbyqxmd.com/read/28095400/computational-analysis-of-residue-interaction-networks-and-coevolutionary-relationships-in-the-hsp70-chaperones-a-community-hopping-model-of-allosteric-regulation-and-communication
#19
Gabrielle Stetz, Gennady M Verkhivker
Allosteric interactions in the Hsp70 proteins are linked with their regulatory mechanisms and cellular functions. Despite significant progress in structural and functional characterization of the Hsp70 proteins fundamental questions concerning modularity of the allosteric interaction networks and hierarchy of signaling pathways in the Hsp70 chaperones remained largely unexplored and poorly understood. In this work, we proposed an integrated computational strategy that combined atomistic and coarse-grained simulations with coevolutionary analysis and network modeling of the residue interactions...
January 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28094951/diabat-interpolation-for-polymorph-free-energy-differences
#20
Kartik Kamat, Baron Peters
Existing methods to compute free energy differences between polymorphs use harmonic approximations, advanced non-Boltzmann bias sampling techniques, and/or multistage free energy perturbations. This work demonstrates how Bennett's diabat interpolation method (J.Comp. Phys. 1976, 22, 245) can be combined with energy gaps from lattice switch Monte Carlo techniques (Phys. Rev. E 2001, 61, 906) to swiftly estimate polymorph free energy differences. The new method requires only two unbiased molecular dynamics simulations, one for each polymorph...
January 17, 2017: Journal of Physical Chemistry Letters
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