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https://www.readbyqxmd.com/read/29166242/dynamism-of-an-astrocyte-in-vivo-perspectives-on-identity-and-function
#1
Kira E Poskanzer, Anna V Molofsky
Astrocytes are an abundant and evolutionarily conserved central nervous system cell type. Despite decades of evidence that astrocytes are integral to neural circuit function, it seems as though astrocytic and neuronal biology continue to advance in parallel to each other, to the detriment of both. Recent advances in molecular biology and optical imaging are being applied to astrocytes in new and exciting ways but without fully considering their unique biology. From this perspective, we explore the reasons that astrocytes remain enigmatic, arguing that their responses to neuronal and environmental cues shape form and function in dynamic ways...
November 20, 2017: Annual Review of Physiology
https://www.readbyqxmd.com/read/29166119/two-phase-thermodynamic-model-for-computing-entropies-of-liquids-reanalyzed
#2
Tao Sun, Jiawei Xian, Huai Zhang, Zhigang Zhang, Yigang Zhang
The two-phase thermodynamic (2PT) model [S.-T. Lin et al., J. Chem. Phys. 119, 11792-11805 (2003)] provides a promising paradigm to efficiently determine the ionic entropies of liquids from molecular dynamics. In this model, the vibrational density of states (VDoS) of a liquid is decomposed into a diffusive gas-like component and a vibrational solid-like component. By treating the diffusive component as hard sphere (HS) gas and the vibrational component as harmonic oscillators, the ionic entropy of the liquid is determined...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166099/long-range-dipolar-order-and-dispersion-forces-in-polar-liquids
#3
Quinn Alexander Besford, Andrew Joseph Christofferson, Maoyuan Liu, Irene Yarovsky
Complex solvation phenomena, such as specific ion effects, occur in polar liquids. Interpretation of these effects in terms of structure and dispersion forces will lead to a greater understanding of solvation. Herein, using molecular dynamics, we probe the structure of polar liquids through specific dipolar pair correlation functions that contribute to the potential of mean force that is "felt" between thermally rotating dipole moments. It is shown that unique dipolar order exists at separations at least up to 20 Å for all liquids studied...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166088/extraction-of-effective-solid-liquid-interfacial-free-energies-for-full-3d-solid-crystallites-from-equilibrium-md-simulations
#4
L A Zepeda-Ruiz, B Sadigh, A A Chernov, T Haxhimali, A Samanta, T Oppelstrup, S Hamel, L X Benedict, J L Belof
Molecular dynamics simulations of an embedded atom copper system in the isobaric-isenthalpic ensemble are used to study the effective solid-liquid interfacial free energy of quasi-spherical solid crystals within a liquid. This is within the larger context of molecular dynamics simulations of this system undergoing solidification, where single individually prepared crystallites of different sizes grow until they reach a thermodynamically stable final state. The resulting equilibrium shapes possess the full structural details expected for solids with weakly anisotropic surface free energies (in these cases, ∼5% radial flattening and rounded [111] octahedral faces)...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166086/focused-conformational-sampling-in-proteins
#5
Marco Bacci, Cassiano Langini, Jiří Vymětal, Amedeo Caflisch, Andreas Vitalis
A detailed understanding of the conformational dynamics of biological molecules is difficult to obtain by experimental techniques due to resolution limitations in both time and space. Computer simulations avoid these in theory but are often too short to sample rare events reliably. Here we show that the progress index-guided sampling (PIGS) protocol can be used to enhance the sampling of rare events in selected parts of biomolecules without perturbing the remainder of the system. The method is very easy to use as it only requires as essential input a set of several features representing the parts of interest sufficiently...
November 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166080/continuum-balances-from-extended-hamiltonian-dynamics
#6
Giulio G Giusteri, Paolo Podio-Guidugli, Eliot Fried
The classical procedure devised by Irving and Kirkwood in 1950 and completed slightly later by Noll produces counterparts of the basic balance laws of standard continuum mechanics starting from an ordinary Hamiltonian description of the dynamics of a system of material points. Post-1980 molecular dynamics simulations of the time evolution of such systems use extended Hamiltonians such as those introduced by Andersen, Nosé, and Parrinello and Rahman. The additional terms present in these extensions affect the statistical properties of the system so as to capture certain target phenomenologies that would otherwise be beyond reach...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166067/equilibrium-configurations-of-large-nanostructures-using-the-embedded-saturated-fragments-stochastic-density-functional-theory
#7
Eitam Arnon, Eran Rabani, Daniel Neuhauser, Roi Baer
An ab initio Langevin dynamics approach is developed based on stochastic density functional theory (sDFT) within a new embedded saturated fragment formalism, applicable to covalently bonded systems. The forces on the nuclei generated by sDFT contain a random component natural to Langevin dynamics, and its standard deviation is used to estimate the friction term on each atom by satisfying the fluctuation-dissipation relation. The overall approach scales linearly with the system size even if the density matrix is not local and is thus applicable to ordered as well as disordered extended systems...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166055/the-entropy-of-a-complex-molecule
#8
Gérôme Faure, Rafael Delgado-Buscalioni, Pep Español
Entropy is a central concept in the theory of coarse-graining. Through Einstein's formula, it provides the equilibrium probability distribution of the coarse-grained variables used to describe the system of interest. We study with molecular dynamics simulations the equilibrium probability distribution of thermal blobs representing at a coarse-grained level star polymer molecules in melt. Thermal blobs are characterized by the positions and momenta of the centers of mass, and internal energies of the molecules...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29166051/a-time-correlation-function-approach-to-nuclear-dynamical-effects-in-x-ray-spectroscopy
#9
Sven Karsten, Sergey I Bokarev, Saadullah G Aziz, Sergei D Ivanov, Oliver Kühn
Modern X-ray spectroscopy has proven itself as a robust tool for probing the electronic structure of atoms in complex environments. Despite working on energy scales that are much larger than those corresponding to nuclear motions, taking nuclear dynamics and the associated nuclear correlations into account may be of importance for X-ray spectroscopy. Recently, we have developed an efficient protocol to account for nuclear dynamics in X-ray absorption and resonant inelastic X-ray scattering spectra [Karsten et al...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29165995/magnetic-particle-imaging-for-highly-sensitive-quantitative-and-safe-in-vivo-gut-bleed-detection-in-a-murine-model
#10
Elaine Y Yu, Prashant Chandrasekharan, Ran Berzon, Zhi Wei Tay, Xinyi Y Zhou, Amit P Khandhar, R Matthew Ferguson, Scott J Kemp, Bo Zheng, Patrick W Goodwill, Michael F Wendland, Kannan M Krishnan, Spencer Behr, Jonathan Carter, Steven M Conolly
Gastrointestinal (GI) bleeding causes more than 300,000 hospitalizations per year in the United States. Imaging plays a crucial role in accurately locating the source of the bleed for timely intervention. Magnetic Particle Imaging (MPI) is an emerging clinically translatable imaging modality that images superparamagnetic iron-oxide (SPIO) tracers with extraordinary contrast and sensitivity. This linearly quantitative modality has zero background tissue signal and zero signal depth attenuation. MPI is also safe: there is zero ionizing radiation exposure to the patient and clinically approved tracers can be used with MPI...
November 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/29165644/-the-money-can-be-a-motivator-to-me-a-little-but-mostly-pbf-just-helps-me-to-do-better-in-my-job-an-exploration-of-the-motivational-mechanisms-of-performance-based-financing-for-health-workers-in-malawi
#11
Julia Lohmann, Danielle Wilhelm, Christabel Kambala, Stephan Brenner, Adamson S Muula, Manuela De Allegri
Performance-based financing (PBF) is assumed to improve health care delivery by motivating health workers to enhance their work performance. However, the exact motivational mechanisms through which PBF is assumed to produce such changes are poorly understood to date. Although PBF is increasingly recognized as a complex health systems intervention, its motivational effect for individual health workers is still often reduced to financial 'carrots and sticks' in the literature and discourse. Aiming to contribute to the development of a more comprehensive understanding of the motivational mechanisms, we explored how PBF impacted health worker motivation in the context of the Malawian Results-based Financing for Maternal and Newborn Health (RBF4MNH) Initiative...
November 20, 2017: Health Policy and Planning
https://www.readbyqxmd.com/read/29165390/comparison-of-anionic-cationic-and-nonionic-surfactants-as-dispersing-agents-for-graphene-based-on-the-fluorescence-of-riboflavin
#12
Rocío Mateos, Soledad Vera, Mercedes Valiente, Ana María Díez-Pascual, María Paz San Andrés
Fluorescence quenching is a valuable tool to gain insight about dynamic changes of fluorophores in complex systems. Graphene (G), a single-layered 2D nanomaterial with unique properties, was dispersed in surfactant aqueous solutions of different nature: non-ionic polyoxyethylene-23-lauryl ether (Brij L23), anionic sodium dodecylsulphate (SDS), and cationic hexadecyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB). The influence of the surfactant type, chain length and concentration, G total concentration and G/surfactant weight ratio on the fluorescence intensity of vitamin B₂ (riboflavin) was investigated...
November 22, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29165248/neuromodulatory-connectivity-defines-the-structure-of-a-behavioral-neural-network
#13
Feici Diao, Amicia D Elliott, Fengqiu Diao, Sarav Shah, Benjamin H White
Neural networks are typically defined by their synaptic connectivity, yet synaptic wiring diagrams often provide limited insight into network function. This is due partly to the importance of non-synaptic communication by neuromodulators, which can dynamically reconfigure circuit activity to alter its output. Here we systematically map the patterns of neuromodulatory connectivity in a network that governs a developmentally critical behavioral sequence in Drosophila. This sequence, which mediates pupal ecdysis, is governed by the serial release of several key factors, which act both somatically as hormones and within the brain as neuromodulators...
November 22, 2017: ELife
https://www.readbyqxmd.com/read/29165233/the-sec-system-protein-export-in-escherichia-coli
#14
Jennine M Crane, Linda L Randall
In Escherichia coli, proteins found in the periplasm or the outer membrane are exported from the cytoplasm by the general secretory, Sec, system before they acquire stably folded structure. This dynamic process involves intricate interactions among cytoplasmic and membrane proteins, both peripheral and integral, as well as lipids. In vivo, both ATP hydrolysis and proton motive force are required. Here, we review the Sec system from the inception of the field through early 2016, including biochemical, genetic, and structural data...
November 2017: EcoSal Plus
https://www.readbyqxmd.com/read/29165062/recent-progress-of-crosslinking-strategies-for-polymeric-micelles-with-enhanced-drug-delivery-in-cancer-therapy
#15
Wei Fan, Luye Zhang, Yiwen Li, Haoxing Wu
The drug delivery by versatile types of self-assembled micelles for tumor treatment, which improved the diagnostic and therapeutic effectiveness, is advocated. However, despite the numerous advantages, applications of most micelle system have been retarded by low in vivo bio-stability which led to premature drug release and nonspecific tissue accumulation. To date, a range of chemistries has been introduced in intermolecular non-covalent/covalent crosslinking strategies for these dynamic nanostructures to produce robust functional nanoparticles with enhanced circulation stability and lower non-targeted organ toxicity...
November 20, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/29164995/novel-polyubiquitin-imaging-system-polyub-fc-reveals-that-k33-linked-polyubiquitin-is-recruited-by-sqstm1-p62
#16
Yoichi Nibe, Shigeru Oshima, Masanori Kobayashi, Chiaki Maeyashiki, Yu Matsuzawa, Kana Otsubo, Hiroki Matsuda, Emi Aonuma, Yasuhiro Nemoto, Takashi Nagaishi, Ryuichi Okamoto, Kiichiro Tsuchiya, Tetsuya Nakamura, Shinichiro Nakada, Mamoru Watanabe
Ubiquitin chains are formed with 8 structurally and functionally distinct polymers. However, the functions of each polyubiquitin remain poorly understood. We developed a polyubiquitin-mediated fluorescence complementation (PolyUb-FC) assay using Kusabira Green (KG) as a split fluorescent protein. The PolyUb-FC assay has the advantage that monoubiquitination is nonfluorescent and chain-specific poly-ubiquitination can be directly visualized in living cells without using antibodies. We applied the PolyUb-FC assay to examine K33-linked polyubiquitin...
November 22, 2017: Autophagy
https://www.readbyqxmd.com/read/29164592/the-moral-economy-of-ready-made-food
#17
Kathryn Wheeler
The aim of this paper is to develop and apply a framework to explore how moralities of consumption are constituted in and through markets. Using the case of ready-made foods, this paper argues moral economies are comprised through interactions between micro-, meso- and macro-level processes in the form of instituted systems of provision, state regulation, collective food customs promoted though media, NGOs and lifestyle practitioners, and the everyday reflections of consumers. Building on a theoretical framework developed to understand the moral economy of work and employment (Bolton and Laaser 2013), this paper explores how markets for ready-made food are incessantly negotiated in the context of moral ideas about cooking, femininity and individual responsibility...
November 22, 2017: British Journal of Sociology
https://www.readbyqxmd.com/read/29164226/nicking-enzyme-controlled-toehold-regulation-for-dna-logic-circuits
#18
Linqiang Pan, Zhiyu Wang, Yifan Li, Fei Xu, Qiang Zhang, Cheng Zhang
DNA strand displacement is widely used in DNA-related nanoengineering for its remarkable specificity and predictability. We report a nicking enzyme-assisted mechanism to regulate strand displacement, where DNA toeholds are dynamically controlled. To demonstrate the strategy, a protein/DNA-based Boolean operation system is constructed and based on it a two-channel multiplexer controlled by three different nicking enzymes is realized. The proposed regulatory mechanism can be used for switch logic statement and bridges protein and DNA logic circuits...
November 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/29164196/supramolecular-polymeric-biomaterials
#19
REVIEW
Joseph L Mann, Anthony C Yu, Gillie Agmon, Eric A Appel
Polymeric chains crosslinked through supramolecular interactions-directional and reversible non-covalent interactions-compose an emerging class of modular and tunable biomaterials. The choice of chemical moiety utilized in the crosslink affords different thermodynamic and kinetic parameters of association, which in turn illustrate the connectivity and dynamics of the system. These parameters, coupled with the choice of polymeric architecture, can then be engineered to control environmental responsiveness, viscoelasticity, and cargo diffusion profiles, yielding advanced biomaterials which demonstrate rapid shear-thinning, self-healing, and extended release...
November 22, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/29164094/application-of-the-intervention-mapping-framework-to-develop-an-integrated-twenty-first-century-core-curriculum-part-two-translation-of-mph-core-competencies-into-an-integrated-theory-based-core-curriculum
#20
Jaime A Corvin, Rita DeBate, Kate Wolfe-Quintero, Donna J Petersen
In the twenty-first century, the dynamics of health and health care are changing, necessitating a commitment to revising traditional public health curricula to better meet present day challenges. This article describes how the College of Public Health at the University of South Florida utilized the Intervention Mapping framework to translate revised core competencies into an integrated, theory-driven core curriculum to meet the training needs of the twenty-first century public health scholar and practitioner...
2017: Frontiers in Public Health
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