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Daniel A Rowlands, Austen Lamacraft
We study a system of spins (qubits) coupled to a common noisy environment, each precessing at its own frequency. The correlated noise experienced by the spins implies long-lived correlations that relax only due to the differing frequencies. We use a mapping to a non-Hermitian integrable Richardson-Gaudin model to find the exact spectrum of the quantum master equation in the high-temperature limit and, hence, determine the decay rate. Our solution can be used to evaluate the effect of inhomogeneous splittings on a system of qubits coupled to a common bath...
March 2, 2018: Physical Review Letters
Masha M Rosenberg, Alfred G Redfield, Mary Roberts, Lizbeth Hedstrom
The ability of enzymes to modulate the dynamics of bound substrates and cofactors is a critical feature of catalysis, but the role of dynamics has largely been approached from the perspective of the protein. Here we use an underappreciated NMR technique, subtesla high resolution field cycling31 P NMR relaxometry, to interrogate the dynamics of enzyme bound substrates and cofactors in guanosine-5'-monophosphate reductase (GMPR). These experiments reveal distinct binding modes and dynamic profiles associated with the31 P nuclei in the Michaelis complexes for the deamination and hydride transfer steps of the catalytic cycle...
March 16, 2018: Biochemistry
Robert T Keys, Anina N Rich, Regine Zopf
Tracking one's own body is essential for environmental interaction, and involves integrating multisensory cues with stored information about the body's typical features. Exactly how multisensory information is integrated in own-body perception is still unclear. For example, Ide and Hidaka (Exp Brain Res 228:43-50, 2013) found that participants made less precise visuo-tactile temporal order judgments (TOJ) when viewing hands in a plausible orientation (upright; typical for one's own hand) compared to an implausible orientation (rotated 180°)...
March 15, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Ayori Mitsutake, Hiroshi Takano
Molecular dynamics simulation is a powerful method for investigating the structural stability, dynamics, and function of biopolymers at the atomic level. In recent years, it has become possible to perform simulations on time scales of the order of milliseconds using special hardware. However, it is necessary to derive the important factors contributing to structural change or function from the complicated movements of biopolymers obtained from long simulations. Although some analysis methods for protein systems have been developed using increasing simulation times, many of these methods are static in nature (i...
March 15, 2018: Biophysical Reviews
Narges Roustaei, Seyyed Mohammad Taghi Ayatollahi, Najaf Zare
In recent years, the joint models have been widely used for modeling the longitudinal and time-to-event data simultaneously. In this study, we proposed an approach (PA) to study the longitudinal and survival outcomes simultaneously in heterogeneous populations. PA relaxes the assumption of conditional independence (CI). We also compared PA with joint latent class model (JLCM) and separate approach (SA) for various sample sizes (150, 300, and 600) and different association parameters (0, 0.2, and 0.5). The average bias of parameters estimation (AB-PE), average SE of parameters estimation (ASE-PE), and coverage probability of the 95% confidence interval (CP) among the three approaches were compared...
2018: BioMed Research International
Selcuk Kayir, Hulya Ulusoy, Guvenc Dogan
Background/aims Sedation is one of the most important components of intensive care unit (ICU) in patients who are mechanically ventilated at intensive care conditions. As a result of sedation and analgesia in the intensive care unit, the patient is to be awakened a comfortable and easy process. The aim of the study is to demonstrate the effects of day-time sedation interruptions in intensive care patients. Material and methods We made a retrospective review of 100 patients who were monitored, mechanically ventilated and treated at our intensive care unit between January 2008 and January 2013...
January 13, 2018: Curēus
Sangmoon Yoon, Hyobin Yoo, Seoung-Hun Kang, Miyoung Kim, Young-Kyun Kwon
We report the existence of latent order during core relaxation in the high-angle grain boundaries (GBs) of GaN films using atomic-resolution scanning transmission electron microscopy and ab initio density functional theory calculations. Core structures in the high-angle GBs are characterized by two pairs of Ga-N bonds located next to each other. The core type correlates strongly with the bond angle differences. We identify an order of core relaxation hidden in the high-angle GBs by further classifying the 5/7 atom cores into a stable 5/7 core (5/7(S)) and a metastable 5/7 core (5/7(M))...
March 15, 2018: Scientific Reports
Sarah Crunkhorn
No abstract text is available yet for this article.
March 16, 2018: Nature Reviews. Drug Discovery
Naoki Ohno, Tosiaki Miyati, Shuto Suzuki, Hirohito Kan, Toshitaka Aoki, Yoshitaka Nakamura, Yuki Hiramatsu, Satoshi Kobayashi, Toshifumi Gabata
PURPOSE: To suppress olefinic signals and enable simultaneous and quantitative estimation of multiple functional parameters associated with water and lipid, we investigated a modified method using chemical shift displacement and recovery-based separation of lipid tissue (SPLIT) involving acquisitions with different inversion times (TIs), echo times (TEs), and b-values. MATERIALS AND METHODS: Single-shot diffusion echo-planar imaging (SSD-EPI) with multiple b-values (0-3000 s/mm2 ) was performed without fat suppression to separate water and lipid images using the chemical shift displacement of lipid signals in the phase-encoding direction...
March 12, 2018: Magnetic Resonance Imaging
Heather T Whittaker, Shenghua Zhu, Domenico L Di Curzio, Richard Buist, Xin-Min Li, Suzanna Noy, Frances K Wiseman, Jonathan D Thiessen, Melanie Martin
Alzheimer's disease (AD) pathology causes microstructural changes in the brain. These changes, if quantified with magnetic resonance imaging (MRI), could be studied for use as an early biomarker for AD. The aim of our study was to determine if T1 relaxation, diffusion tensor imaging (DTI), and quantitative magnetization transfer imaging (qMTI) metrics could reveal changes within the hippocampus and surrounding white matter structures in ex vivo transgenic mouse brains overexpressing human amyloid precursor protein with the Swedish mutation...
March 12, 2018: Magnetic Resonance Imaging
Nan Zhang, Lei Zhang, Linyin Feng, Lei Yao
ETHNOPHARMACOLOGICAL RELEVANCE: Cananga odorata essential oil, known as ylang-ylang essential oil (YYO), was commonly used in the aromatherapy for relaxation and mood adjusting use. In our previous study, YYO played anxiolytic effects on the mice in several behavioral tests that based on the instinctive responses to novel environments. AIM OF THE STUDY: To investigate the effects and mechanisms of YYO reversing the anxiety induced by 5-HT2C receptor agonist 1-(3-chlorophenyl) piperazine (m-CPP)...
March 12, 2018: Journal of Ethnopharmacology
Roel Tempelaar, David R Reichman
Fewest-switches surface hopping (FSSH) is perhaps the most widely used mixed quantum-classical approach for the modeling of non-adiabatic processes, but its original formulation is restricted to (adiabatic) population terms of the quantum density matrix, leaving its implementations with an inconsistency in the treatment of populations and coherences. In this article, we propose a generalization of FSSH that treats both coherence and population terms on equal footing and which formally reduces to the conventional FSSH algorithm for the case of populations...
March 14, 2018: Journal of Chemical Physics
E Pafong Sanjon, B Drossel, M Vogel
Silica is a network-forming liquid that shares many properties with water due to its tetrahedral structure. It undergoes a transition from a fragile to a strong liquid as the temperature is decreased, which is accompanied by a structural change to lower density and higher tetrahedral order. In order to disentangle the effects of Coulomb and van der Waals interactions on the structure and dynamics of liquid silica, we modify the bond polarity by changing the partial charges assigned to each atom. Using molecular dynamics simulations, we show that density, tetrahedral order, and structural relaxation times decrease when reducing bond polarity...
March 14, 2018: Journal of Chemical Physics
Serguei V Feskov, Anatoly I Ivanov
An approach to the construction of diabatic free energy surfaces (FESs) for ultrafast electron transfer (ET) in a supramolecule with an arbitrary number of electron localization centers (redox sites) is developed, supposing that the reorganization energies for the charge transfers and shifts between all these centers are known. Dimensionality of the coordinate space required for the description of multistage ET in this supramolecular system is shown to be equal to N - 1, where N is the number of the molecular centers involved in the reaction...
March 14, 2018: Journal of Chemical Physics
Beatriz A Pazmiño Betancourt, Francis W Starr, Jack F Douglas
Relaxation in glass-forming liquids occurs as a multi-stage hierarchical process involving cooperative molecular motion. First, there is a "fast" relaxation process dominated by the inertial motion of the molecules whose amplitude grows upon heating, followed by a longer time α-relaxation process involving both large-scale diffusive molecular motion and momentum diffusion. Our molecular dynamics simulations of a coarse-grained glass-forming polymer melt indicate that the fast, collective motion becomes progressively suppressed upon cooling, necessitating large-scale collective motion by molecular diffusion for the material to relax approaching the glass-transition...
March 14, 2018: Journal of Chemical Physics
Daniel Stopper, Alice L Thorneywork, Roel P A Dullens, Roland Roth
Using dynamical density functional theory (DDFT), we theoretically study Brownian self-diffusion and structural relaxation of hard disks and compare to experimental results on quasi two-dimensional colloidal hard spheres. To this end, we calculate the self-van Hove correlation function and distinct van Hove correlation function by extending a recently proposed DDFT-approach for three-dimensional systems to two dimensions. We find that the theoretical results for both self-part and distinct part of the van Hove function are in very good quantitative agreement with the experiments up to relatively high fluid packing fractions of roughly 0...
March 14, 2018: Journal of Chemical Physics
Michael M Linden, J Philipp Wagner, Bastian Bernhardt, Marcus A Bartlett, Wesley D Allen, Peter R Schreiner
Disentangling internal and external effects is a key requirement for understanding conformational tunneling processes. Here we report the s-trans/s-cis tunneling rotamerization of carbonic acid monomethyl ester (1) under matrix isolation conditions and make comparisons to its parent carbonic acid (3). The observed tunneling rate of 1 is temperature independent in the 3-20 K range and accelerates when using argon instead of neon as the matrix material. The methyl group increases the effective half-life (τeff) of the energetically disfavored s-trans-conformer from 3-5 h for 3 to 11-13 h for 1...
March 15, 2018: Journal of Physical Chemistry Letters
Casey R Guillot, Heidemarie Blumenthal, Michael J Zvolensky, Norman B Schmidt
Anxiety sensitivity (AS)- fear of anxiety symptoms and their potential negative consequences-has been implicated in the development of substance use problems and motivation to use substances for coping with distress, though the AS components (physical, cognitive, and social concerns) have not been studied extensively in relation to alcohol- and cannabis-related variables. In a cross-sectional design, self-report measures of AS and alcohol and cannabis use, motives, and problems were administered to 364 treatment-seeking cigarette smokers with a history of alcohol and cannabis use...
March 8, 2018: Addictive Behaviors
Bin Li, Yaqing Liu, Changjin Wan, Zhiyuan Liu, Ming Wang, Dianpeng Qi, Jiancan Yu, Pingqiang Cai, Meng Xiao, Yi Zeng, Xiaodong Chen
Memristive synapses based on resistive switching are promising electronic devices that emulate the synaptic plasticity in neural systems. Short-term plasticity (STP), reflecting a temporal strengthening of the synaptic connection, allows artificial synapses to perform critical computational functions, such as fast response and information filtering. To mediate this fundamental property in memristive electronic devices, the regulation of the dynamic resistive change is necessary for an artificial synapse. Here, it is demonstrated that the orientation of mesopores in the dielectric silica layer can be used to modulate the STP of an artificial memristive synapse...
March 15, 2018: Advanced Materials
Frank Niemeyer, Lutz Claes, Anita Ignatius, Nicholaus Meyers, Ulrich Simon
Distraction osteogenesis is an effective method for generating large amounts of bone in situ for treating pathologies such as large bone defects or skeletal malformations, for instance leg-length discrepancies. While an optimized distraction procedure might have the potential to reduce the rate of complications significantly, our knowledge of the underlying mechanobiological processes is still insufficient for systematic optimization of treatment parameters such as distraction rate or fixation stiffness. We present a novel numerical model of lateral distraction osteogenesis, based on a mechanically well-controlled in vivo experiment...
2018: PloS One
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