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https://www.readbyqxmd.com/read/29352582/a-microfluidic-distributor-combining-minimal-volume-minimal-dispersion-and-minimal-sensitivity-to-clogging
#1
Sander Jespers, Sander Deridder, Gert Desmet
A new type of microfluidic flow distributor (referred to as the mixed mode or MM-distributor) is proposed. Its performance characteristics are determined using computational fluid dynamics (CFD), both in the absence and the presence of clogging, which is an important problem in microfluidic systems. A comparison is made with two existing, well-performing distributor types: the bifurcating (BF) distributor and an optimized diverging distributor, the so-called radially interconnected (RI) distributor. It was found that, in the absence of clogging, the MM-distributor produces only a little more dispersion than the bifurcating (BF) distributor, but much less than the radially interconnected (RI) distributor...
January 12, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29352283/using-a-model-comparison-approach-to-describe-the-assembly-pathway-for-histone-h1
#2
Carlos Contreras, Minaya Villasana, Michael J Hendzel, Gustavo Carrero
Histones H1 or linker histones are highly dynamic proteins that diffuse throughout the cell nucleus and associate with chromatin (DNA and associated proteins). This binding interaction of histone H1 with the chromatin is thought to regulate chromatin organization and DNA accessibility to transcription factors and has been proven to involve a kinetic process characterized by a population that associates weakly with chromatin and rapidly dissociates and another population that resides at a binding site for up to several minutes before dissociating...
2018: PloS One
https://www.readbyqxmd.com/read/29352137/iron-biogeochemistry-in-the-high-latitude-north-atlantic-ocean
#3
Eric P Achterberg, Sebastian Steigenberger, Chris M Marsay, Frédéric A C LeMoigne, Stuart C Painter, Alex R Baker, Douglas P Connelly, C Mark Moore, Alessandro Tagliabue, Toste Tanhua
Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world's ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (<0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29352116/the-chemical-fluctuation-theorem-governing-gene-expression
#4
Seong Jun Park, Sanggeun Song, Gil-Suk Yang, Philip M Kim, Sangwoon Yoon, Ji-Hyun Kim, Jaeyoung Sung
Gene expression is a complex stochastic process composed of numerous enzymatic reactions with rates coupled to hidden cell-state variables. Despite advances in single-cell technologies, the lack of a theory accurately describing the gene expression process has restricted a robust, quantitative understanding of gene expression variability among cells. Here we present the Chemical Fluctuation Theorem (CFT), providing an accurate relationship between the environment-coupled chemical dynamics of gene expression and gene expression variability...
January 19, 2018: Nature Communications
https://www.readbyqxmd.com/read/29352036/multiple-memory-systems-multiple-time-points-how-science-can-inform-treatment-to-control-the-expression-of-unwanted-emotional-memories
#5
REVIEW
Renée M Visser, Alex Lau-Zhu, Richard N Henson, Emily A Holmes
Memories that have strong emotions associated with them are particularly resilient to forgetting. This is not necessarily problematic, however some aspects of memory can be. In particular, the involuntary expression of those memories, e.g. intrusive memories after trauma, are core to certain psychological disorders. Since the beginning of this century, research using animal models shows that it is possible to change the underlying memory, for example by interfering with its consolidation or reconsolidation...
March 19, 2018: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/29351994/full-molecular-trajectories-of-rna-polymerase-at-single-base-pair-resolution
#6
Maurizio Righini, Antony Lee, Cristhian Cañari-Chumpitaz, Troy Lionberger, Ronen Gabizon, Yves Coello, Ignacio Tinoco, Carlos Bustamante
In recent years, highly stable optical tweezers systems have enabled the characterization of the dynamics of molecular motors at very high resolution. However, the motion of many motors with angstrom-scale dynamics cannot be consistently resolved due to poor signal-to-noise ratio. Using an acousto-optic deflector to generate a "time-shared" dual-optical trap, we decreased low-frequency noise by more than one order of magnitude compared with conventional dual-trap optical tweezers. Using this instrument, we implemented a protocol that synthesizes single base-pair trajectories, which are used to test a Large State Space Hidden Markov Model algorithm to recover their individual steps...
January 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29351809/axonal-transport-in-a-peripheral-diabetic-neuropathy-model-sex-dimorphic-features
#7
Marzia Pesaresi, Silvia Giatti, Roberto Spezzano, Simone Romano, Silvia Diviccaro, Tiziana Borsello, Nico Mitro, Donatella Caruso, Luis Miguel Garcia-Segura, Roberto Cosimo Melcangi
BACKGROUND: Disruption of axonal transport plays a pivotal role in diabetic neuropathy. A sex-dimorphism exists in the incidence and symptomatology of diabetic neuropathy; however, no studies so far have addressed sex differences in axonal motor proteins expression in early diabetes as well as the possible involvement of neuroactive steroids. Interestingly, recent data point to a role for mitochondria in the sexual dimorphism of neurodegenerative diseases. Mitochondria have a fundamental role in axonal transport by producing the motors' energy source, ATP...
January 19, 2018: Biology of Sex Differences
https://www.readbyqxmd.com/read/29351723/mitochondrial-uncoupling-proteins-subtle-regulators-of-cellular-redox-signaling
#8
Petr Jezek, Blanka Holendová, Keith D Garlid, Martin Jaburek
SIGNIFICANCE: Mitochondria are the energetic, metabolic, redox and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the above aspects, being involved in numerous physiological events including redox signaling...
January 19, 2018: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29351651/radiotherapy-proton-beam-profilometry-with-sccvd-diamond-detector-in-single-particle-mode
#9
Marzena Rydygier, Marcin Jastrzab, Dawid Krzempek, Tomasz Nowak, Leszek Grzanka, Piotr Bednarczyk, Liliana Stolarczyk
Proton radiotherapy requires precise knowledge of the volumetric dose distribution. In proton beam delivery systems, based on narrow pencil beams, a contribution from small doses in low-intensity regions, consisting mainly of scattered protons, may have not negligible influence on total dose delivered to patient. Insufficient information about dose profile can cause underestimation of dose and potential delivery of inflated dose during hadrontherapy treatment. Presented work aims to verify applicability of diamond detectors, produced by Chemical Vapor Deposition method, for therapeutic proton beam profilometry at large fields...
January 17, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29351559/characterisation-of-ictal-and-interictal-states-of-epilepsy-a-system-dynamic-approach-of-principal-dynamic-modes-analysis
#10
Zabit Hameed, Saqib Saleem, Jawad Mirza, Muhammad Salman Mustafa, Qamar-Ul-Islam
Epilepsy is a brain disorder characterised by the recurrent and unpredictable interruptions of normal brain function, called epileptic seizures. The present study attempts to derive new diagnostic indices which may delineate between ictal and interictal states of epilepsy. To achieve this, the nonlinear modeling approach of global principal dynamic modes (PDMs) is adopted to examine the functional connectivity of the temporal and frontal lobes with the occipital brain segment using an ensemble of paediatric EEGs having the presence of epileptic seizure...
2018: PloS One
https://www.readbyqxmd.com/read/29351430/dynamic-changes-in-nitric-oxide-synthase-expression-are-involved-in-seawater-acclimation-of-rainbow-trout-oncorhynchus-mykiss
#11
Lucie Gerber, Frank B Jensen, Steffen S Madsen
Recent research has shown that nitric oxide (NO) produced by nitric oxide synthases (Nos) is an inhibitor of ion transporter activity and a modulator of epithelial ion transport in fish but little is known on changes in the Nos/NO system during osmotic stress. We hypothesized that the Nos/NO system responds to salinity changes as an integrated part of the acclimation process. Expression and localization of nos1/Nos1 and nos2/Nos2 were investigated in gill, kidney and intestine of FW- and SW-transferred trout using qPCR, Western blotting and immunohistochemistry, along with expressional changes of major ion transporters in the gill...
December 20, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29351287/a-novel-association-rule-mining-approach-using-tid-intermediate-itemset
#12
Iyad Aqra, Tutut Herawan, Norjihan Abdul Ghani, Adnan Akhunzada, Akhtar Ali, Ramdan Bin Razali, Manzoor Ilahi, Kim-Kwang Raymond Choo
Designing an efficient association rule mining (ARM) algorithm for multilevel knowledge-based transactional databases that is appropriate for real-world deployments is of paramount concern. However, dynamic decision making that needs to modify the threshold either to minimize or maximize the output knowledge certainly necessitates the extant state-of-the-art algorithms to rescan the entire database. Subsequently, the process incurs heavy computation cost and is not feasible for real-time applications. The paper addresses efficiently the problem of threshold dynamic updation for a given purpose...
2018: PloS One
https://www.readbyqxmd.com/read/29351262/imu-to-segment-assignment-and-orientation-alignment-for-the-lower-body-using-deep-learning
#13
Tobias Zimmermann, Bertram Taetz, Gabriele Bleser
Human body motion analysis based on wearable inertial measurement units (IMUs) receives a lot of attention from both the research community and the and industrial community. This is due to the significant role in, for instance, mobile health systems, sports and human computer interaction. In sensor based activity recognition, one of the major issues for obtaining reliable results is the sensor placement/assignment on the body. For inertial motion capture (joint kinematics estimation) and analysis, the IMU-to-segment (I2S) assignment and alignment are central issues to obtain biomechanical joint angles...
January 19, 2018: Sensors
https://www.readbyqxmd.com/read/29351020/a-dynamic-state-model-of-migratory-behavior-and-physiology-to-assess-the-consequences-of-environmental-variation-and-anthropogenic-disturbance-on-marine-vertebrates
#14
Enrico Pirotta, Marc Mangel, Daniel P Costa, Bruce Mate, Jeremy A Goldbogen, Daniel M Palacios, Luis A Hückstädt, Elizabeth A McHuron, Lisa Schwarz, Leslie New
Integrating behavior and physiology is critical to formulating new hypotheses on the evolution of animal life-history strategies. Migratory capital breeders acquire most of the energy they need to sustain migration, gestation, and lactation before parturition. Therefore, when predicting the impact of environmental variation on such species, a mechanistic understanding of the physiology of their migratory behavior is required. Using baleen whales as a model system, we developed a dynamic state variable model that captures the interplay among behavioral decisions, energy, reproductive needs, and the environment...
February 2018: American Naturalist
https://www.readbyqxmd.com/read/29351014/coinfection-timing-drives-host-population-dynamics-through-changes-in-virulence
#15
Katherine M Marchetto, Alison G Power
Infections of one host by multiple parasites are common, and several studies have found that the order of parasite invasion can affect both within-host competition and disease severity. However, it is unclear to what extent coinfection timing might be important to consider when modeling parasite impacts on host populations. Using a model system of two viruses infecting barley, we found that simultaneous infections of the two viruses were significantly more damaging to hosts than sequential coinfections. While priority effects were evident in within-host concentrations of sequential coinfections, priority did not influence any parameters (such as virulence or transmission rate) that affect host population dynamics...
February 2018: American Naturalist
https://www.readbyqxmd.com/read/29350968/spin-switching-via-quantum-dot-spin-valves
#16
N M Gergs, S A Bender, R A Duine, D Schuricht
We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state...
January 5, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29350961/electron-correlation-from-the-adiabatic-connection-for-multireference-wave-functions
#17
Katarzyna Pernal
An adiabatic connection (AC) formula for the electron correlation energy is derived for a broad class of multireference wave functions. The AC expression recovers dynamic correlation energy and assures a balanced treatment of the correlation energy. Coupling the AC formalism with the extended random phase approximation allows one to find the correlation energy only from reference one- and two-electron reduced density matrices. If the generalized valence bond perfect pairing model is employed a simple closed-form expression for the approximate AC formula is obtained...
January 5, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29350957/relativistic-fluid-dynamics-far-from-local-equilibrium
#18
Paul Romatschke
Fluid dynamics is traditionally thought to apply only to systems near local equilibrium. In this case, the effective theory of fluid dynamics can be constructed as a gradient series. Recent applications of resurgence suggest that this gradient series diverges, but can be Borel resummed, giving rise to a hydrodynamic attractor solution which is well defined even for large gradients. Arbitrary initial data quickly approaches this attractor via nonhydrodynamic mode decay. This suggests the existence of a new theory of far-from-equilibrium fluid dynamics...
January 5, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29350725/effects-of-chemically-heterogeneous-nanoparticles-on-polymer-dynamics-insights-from-molecular-dynamics-simulations
#19
Zijian Zheng, Fanzhu Li, Jun Liu, Raffaele Pastore, Guido Raos, Youping Wu, Liqun Zhang
The dispersion of solid nanoparticles within polymeric materials is widely used to enhance their performance. Many scientific and technological aspects of the resulting polymer nanocomposites have been studied, but the role of the structural and chemical heterogeneity of the nanoparticles has just started to be appreciated. For example, simulations of polymer films on planar heterogeneous surfaces revealed unexpected, non-monotonic activation energy to diffusion on varying the surface composition. Motivated by these intriguing results, here we simulate via molecular dynamics a different, fully three-dimensional system, in which the heterogeneous nanoparticles are incorporated in a polymer melt...
January 19, 2018: Soft Matter
https://www.readbyqxmd.com/read/29350616/a-disassembly-driven-mechanism-explains-f-actin-mediated-chromosome-transport-in-starfish-oocytes
#20
Philippe Bun, Serge Dmitrieff, Julio M Belmonte, François J Nédélec, Péter Lénárt
While contraction of sarcomeric actomyosin assemblies is well understood, this is not the case for disordered networks of actin filaments (F-actin) driving diverse essential processes in animal cells. For example, at the onset of meiosis in starfish oocytes a contractile F-actin network forms in the nuclear region transporting embedded chromosomes to the assembling microtubule spindle. Here, we addressed the mechanism driving contraction of this 3D disordered F-actin network by comparing quantitative observations to computational models...
January 19, 2018: ELife
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