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Javier Rodríguez Árbol, Pandelis Perakakis, Alba Garrido, José Luis Mata, M Carmen Fernández-Santaella, Jaime Vila
The preejection period (PEP) is an index of left ventricle contractility widely used in psychophysiological research. Its computation requires detecting the moment when the aortic valve opens, which coincides with the B point in the first derivative of impedance cardiogram (ICG). Although this operation has been traditionally made via visual inspection, several algorithms based on derivative calculations have been developed to enable an automatic performance of the task. However, despite their popularity, data about their empirical validation are not always available...
December 3, 2016: Psychophysiology
Jie Li, Patrice Koehl
Computational protein sequence design is the rational design based on computer simulation of new protein molecules to fold to target three-dimensional structures, with the ultimate goal of designing novel functions. It requires a good understanding of the thermodynamic equilibrium properties of the protein of interest. Here, we consider the contribution of the solvent to the stability of the protein. We describe implicit solvent models, focusing on approximations of their nonpolar components using geometric potentials...
2017: Methods in Molecular Biology
Efrath Barta
Long-chain fatty acids cross a few membranes on their way from the capillary blood to the cardiomyocyte cytosol, where they are utilized as an essential source of energy. Details of the transport mechanism across those membranes remained elusive despite decades of laboratory and theoretical work. Here we inspect several optional scenarios for the crossing of the luminal membrane of the endothelial cell, the first barrier that should be crossed: a passive diffusion, facilitation by receptors for albumin and facilitation by fatty acids transporters...
December 3, 2016: Journal of Membrane Biology
Joseph H R Hetmanski, Jean-Marc Schwartz, Patrick T Caswell
Metastasis, initially driven by cells migrating and invading through the local environment, leads to most cancer-associated deaths. Cells can use a variety of modes to move in vitro, all of which depend on Rho GTPases at some level. While traditionally it was thought that Rac1 activity drives protrusive lamellipodia at the leading edge of a polarised cell while RhoA drives rear retraction, more recent work in 3D microenvironments has revealed a much more complicated picture of GTPase dynamics. In particular, RhoA activity can dominate the leading edge polymerisation of actin to form filopodial actin-spike protrusions that drive more invasive cell migration...
December 15, 2016: Biochemical Society Transactions
Katsumi Fumoto, Hisako Takigawa-Imamura, Kenta Sumiyama, Tomoyuki Kaneiwa, Akira Kikuchi
In lung development the apically constricted columnar epithelium forms numerous buds during the pseudoglandular stage and subsequently changes the shape into flat or cuboidal pneumocytes that compose the air sacs during the canalicular and saccular (canalicular-saccular) stages, yet the impact of cell shapes on tissue morphogenesis remains unclear. The expression of Wnt components were decreased in the canalicular-saccular stages, and genetically constitutive activation of Wnt signaling impaired air sac formation by inducing apical constriction in the epithelium as seen in the pseudoglandular stage...
December 2, 2016: Development
Jia Li, Chenyan Bai, Zhouchen Lin, Jian Yu
In most of existing digital cameras, color images have to be reconstructed from raw images which only have one color sensed at each pixel, as their imaging sensors are covered by color filter arrays (CFAs). At each pixel a CFA usually allows only a portion of the light spectrum to pass through and thereby reduces the light sensitivity of pixels. To address this issue, previous works have explored adding panchromatic pixels into CFAs. However, almost all existing methods assign panchromatic pixels empirically, making the designed CFAs prone to aliasing artifacts...
December 1, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Jingqi Q X Gong, Jaehee V Shim, Elisa Núñez-Acosta, Eric A Sobie
No abstract text is available yet for this article.
November 29, 2016: Journal of Molecular and Cellular Cardiology
Dharmendra Tripathi, Ashu Yadav, O Anwar Bég
Analytical solutions are developed for the electro-kinetic flow of a viscoelastic biological liquid in a finite length cylindrical capillary geometry under peristaltic waves. The Jefferys' non-Newtonian constitutive model is employed to characterize rheological properties of the fluid. The unsteady conservation equations for mass and momentum with electro-kinetic and Darcian porous medium drag force terms are reduced to a system of steady linearized conservation equations in an axisymmetric coordinate system...
November 29, 2016: Mathematical Biosciences
Bruce Pell, Yang Kuang, Cecile Viboud, Gerardo Chowell
BACKGROUND: The rising number of novel pathogens threatening the human population has motivated the application of mathematical modeling for forecasting the trajectory and size of epidemics. MATERIALS AND METHODS: We summarize the real-time forecasting results of the logistic equation during the 2015 Ebola challenge focused on predicting synthetic data derived from a detailed individual-based model of Ebola transmission dynamics and control. We also carry out a post-challenge comparison of two simple phenomenological models...
November 19, 2016: Epidemics
Vajiheh Akbarzadeh, Ghina R Mumtaz, Susanne F Awad, Helen A Weiss, Laith J Abu-Raddad
BACKGROUND: Hepatitis C virus (HCV) and HIV are both transmitted through percutaneous exposures among people who inject drugs (PWID). Ecological analyses on global epidemiological data have identified a positive association between HCV and HIV prevalence among PWID. Our objective was to demonstrate how HCV prevalence can be used to predict HIV epidemic potential among PWID. METHODS: Two population-level models were constructed to simulate the evolution of HCV and HIV epidemics among PWID...
December 3, 2016: BMC Public Health
Matthew G Reuter
Complex band structure generalizes conventional band structure by also considering wavevectors with complex components. In this way, complex band structure describes both the bulk-propagating states from conventional band structure and the evanescent states that grow or decay from one unit cell to the next. Even though these latter states are excluded by translational symmetry, they become important when translational symmetry is broken via, for example, a surface or impurity. Many studies over the last 80 years have directly or indirectly developed complex band structure for an impressive range of applications, but very few discuss its fundamentals or compare its various results...
December 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Thomas M Beardsley, Mark W Matsen
The equivalent behavior among analogous block copolymer systems involving chemically distinct molecules or mathematically different models has long hinted at an underlying universality, but only recently has it been rigorously demonstrated by matching results from different simulations. The profound implication of universality is that simple coarse-grained models can be calibrated so as to provide quantitatively accurate predictions to experiment. Here, we provide the first compelling demonstration of this by simulating a polyisoprene-polylactide diblock copolymer melt using a previously calibrated lattice model...
November 18, 2016: Physical Review Letters
Sneha Pandya, Amy Kuceyeski, Ashish Raj
Alzheimer's disease (AD), one of the most common causes of dementia in adults, is a progressive neurodegenerative disorder exhibiting well-defined neuropathological hallmarks. It is known that disease pathology involves misfolded amyloid-β (Aβ) and tau proteins, and exhibits a relatively stereotyped progression over decades. The relationship between AD neuropathological hallmarks (Aβ, hypometabolism, and tau proteins) and imaging biomarkers (MRI, AV-45/FDG-PET) is not fully understood. In addition, biomarker pathologies are oftentimes discordant, wherein it may show varying levels of abnormality across brain regions...
November 28, 2016: Journal of Alzheimer's Disease: JAD
Tobias Cramer, Lorenzo Travaglini, Stefano Lai, Luca Patruno, Stefano de Miranda, Annalisa Bonfiglio, Piero Cosseddu, Beatrice Fraboni
The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects...
December 2, 2016: Scientific Reports
Marek Daszkiewicz, Agnieszka Mielcarek
Crystal structures of (H2m4na)NO3 (1), (H2m4na)HSO4 (2), (H2m4na)2SiF6 (3) and (H2m4na)2SiF6·2H2O (4), where 2m4na = 2-methyl-4-nitroaniline, are presented. Two layers of interactions occur in the structures, N-H...O/F hydrogen bonds and interactions with the nitro group. Although diverse, hydrogen-bonding patterns are compared with each other by means of interrelations among elementary graph-set descriptors and descriptors of hydrogen-bonding patterns. Using mathematical relations, the gradual expansion of the ring patterns was shown in the crystal structures...
December 1, 2016: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
H B Ray, T M Biewer, D T Fehling, R C Isler, E A Unterberg
Fast visible cameras and a filterscope are used to examine the visible light emission from Oak Ridge National Laboratory's Proto-MPEX. The filterscope has been configured to perform helium line ratio measurements using emission lines at 667.9, 728.1, and 706.5 nm. The measured lines should be mathematically inverted and the ratios compared to a collisional radiative model (CRM) to determine Te and ne. Increasing the number of measurement chords through the plasma improves the inversion calculation and subsequent Te and ne localization...
November 2016: Review of Scientific Instruments
Mingxin An, Lihao Zhang, Shuyan Xu, Jihong Dong
A statically determinate kinematic mount structure is designed for an astronomical observation instrument. The basic principle of the proposed kinematic mount is introduced in detail, including the design principle, its structure, and its degrees of freedom. The compliance equations for the single-axis right circle flexure hinge are deduced, and mathematical models of the compliances of the bipod in the X-axis and Z-axis directions are established. Based on the index requirements, the range of one design parameter (the hinge groove depth, R) for the kinematic mount is determined...
November 2016: Review of Scientific Instruments
Qi Wang, Zhijie Lian, Jianming Wang, Qingliang Chen, Yukuan Sun, Xiuyan Li, Xiaojie Duan, Ziqiang Cui, Huaxiang Wang
Electrical impedance tomography (EIT) reconstruction is a nonlinear and ill-posed problem. Exact reconstruction of an EIT image inverts a high dimensional mathematical model to calculate the conductivity field, which causes significant problems regarding that the computational complexity will reduce the achievable frame rate, which is considered as a major advantage of EIT imaging. The single-step method, state estimation method, and projection method were always used to accelerate reconstruction process. The basic principle of these methods is to reduce computational complexity...
November 2016: Review of Scientific Instruments
Ayman Hamzawy, Dimitar N Grozdanov, Mohamed S Badawi, Fuad A Aliyev, Abouzeid A Thabet, Mahmoud I Abbas, Ivan N Ruskov, Ahmed M El-Khatib, Yuri N Kopatch, Mona M Gouda
Scintillation crystals are usually used for detection of energetic photons at room temperature in high energy and nuclear physics research, non-destructive analysis of materials testing, safeguards, nuclear treaty verification, geological exploration, and medical imaging. Therefore, new designs and construction of radioactive beam facilities are coming on-line with these science brunches. A good number of researchers are investigating the efficiency of the γ-ray detectors to improve the models and techniques used in order to deal with the most pressing problems in physics research today...
November 2016: Review of Scientific Instruments
Antonio Fasano, Prof Emeritus, Luca Anfuso Md, Stefano Bozzi Md, Claudio Pandozi Prof
BACKGROUND: Radiofrequency ablation is extensively used to achieve pulmonary veins isolation for the cure of atrial fibrillation. Luminal esophageal temperature can be monitored by means of suitable probes to prevent the onset of lesions. OBJECTIVE: To compute the thermal field generated by the ablation, to investigate the interaction between the electromagnetic field and the probe sensors, and to provide a safe interpretation of the temperature detected by the probe, supported by clinical data...
June 2016: Journal of Atrial Fibrillation
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