Read by QxMD icon Read

Computational model

Johannes Leugering, Gordon Pipa
A neuronal population is a computational unit that receives a multivariate, time-varying input signal and creates a related multivariate output. These neural signals are modeled as stochastic processes that transmit information in real time, subject to stochastic noise. In a stationary environment, where the input signals can be characterized by constant statistical properties, the systematic relationship between its input and output processes determines the computation carried out by a population. When these statistical characteristics unexpectedly change, the population needs to adapt to its new environment if it is to maintain stable operation...
January 17, 2018: Neural Computation
Dorian Florescu, Daniel Coca
Inferring mathematical models of sensory processing systems directly from input-output observations, while making the fewest assumptions about the model equations and the types of measurements available, is still a major issue in computational neuroscience. This letter introduces two new approaches for identifying sensory circuit models consisting of linear and nonlinear filters in series with spiking neuron models, based only on the sampled analog input to the filter and the recorded spike train output of the spiking neuron...
January 17, 2018: Neural Computation
Jorge Maícas-Royo, Gareth Leng, Duncan J MacGregor
Oxytocin neurons of the rat hypothalamus project to the posterior pituitary where they secrete their products into the bloodstream. The pattern and quantity of that release depends on the afferent inputs to the neurons, on their intrinsic membrane properties, and on non-linear interactions between spiking activity and exocytosis: a given number of spikes will trigger more secretion when they arrive close together. Here we present a quantitative computational model of oxytocin neurons that can replicate the results of a wide variety of published experiments...
January 12, 2018: Endocrinology
Andrew W Frank-Wilson, Didier Chalhoub, Pedro Figueiredo, Pálmi V Jónsson, Kristín Siggeirsdóttir, Sigurdur Sigurdsson, Gudny Eiriksdottir, Vilmundur Guðnason, Lenore Launer, Tamara B Harris
Background: Atrophy and fatty infiltration of muscle with aging are associated with fractures and falls, however, their direct associations with muscle function are not well described. It was hypothesized that participants with lower quadriceps muscle attenuation, area, and greater intra-muscular adipose tissue (IMAT) will exhibit slower rates of torque development (RTD) and lower peak knee extension torques. Methods: Data from 4842 participants (2041 men, 2801 women) from the Age Gene/Environment Susceptibility Reykjavik Study (mean age 76±0...
January 12, 2018: Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
Chunpeng James Chen, Zhiwu Zhang
Summary: The ultimate goal of genomic research is to effectively predict phenotypes from genotypes so that medical management can improve human health and molecular breeding can increase agricultural production. Genomic prediction or selection (GS) plays a complementary role to genome-wide association studies (GWAS), which is the primary method to identify genes underlying phenotypes. Unfortunately, most computing tools cannot perform data analyses for both GWAS and GS. Furthermore, the majority of these tools are executed through a command-line interface (CLI), which requires programming skills...
January 11, 2018: Bioinformatics
Chao Ning, Dan Wang, Huimin Kang, Raphael Mrode, Lei Zhou, Shizhong Xu, Jian-Feng Liu
Motivation: Epistasis provides a feasible way for probing potential genetic mechanism of complex traits. However, time-consuming computation challenges successful detection of interaction in practice, especially when linear mixed model (LMM) is used to control type I error in the presence of population structure and cryptic relatedness. Results: A rapid epistatic mixed-model association analysis (REMMA) method was developed to overcome computational limitation. This method first estimates individuals' epistatic effects by an extended genomic best linear unbiased prediction (EG-BLUP) model with additive and epistatic kinship matrix, then pairwise interaction effects are obtained by linear retransformations of individuals' epistatic effects...
January 12, 2018: Bioinformatics
Viviane S Straatmann, Ylva B Almquist, Aldair J Oliveira, Mikael Rostila, Claudia S Lopes
We investigated the stability and the directionality of being body bullied and a set of four variables- 1) Body Mass Index (BMI), 2) moderate and vigorous physical activity (MVPA), 3) television time (TV) and 4) video game/computer time (VG)-, termed in the present study as 'health-related state and behaviours (HRSB)'-across adolescence. The Adolescent Nutritional Assessment Longitudinal Study (ELANA) is a cohort study conducted among middle school students from two public and four private schools in Rio de Janeiro-Brazil...
2018: PloS One
Ping Zhu, Xinliang Liu, Xiaoming Mao
BACKGROUND It has been reported that overt and mild thyroid dysfunctions are associated with insulin resistance (IR). We performed this retrospective study to evaluate the relationships between thyroid-stimulating hormone (TSH) levels within the reference range and IR. MATERIAL AND METHODS A total of 447 outpatients were enrolled in this study: 298 with type 2 diabetes mellitus and 149 nondiabetic individuals. Based on a cutoff HbA1c value of 7%, diabetic patients were additionally divided into 2 groups: a high-HbA1c group (n=240) and a low-HbA1c group (n=58)...
January 17, 2018: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Bing Wang, Gerard Bredael, Piero M Armenante
The hydrodynamics characteristics of a mini vessel and a USP 2 dissolution testing system were obtained and compared to predict the tablet-liquid mass transfer coefficient from velocity distributions near the tablet and establish the dynamic operating conditions under which dissolution in mini vessels could be conducted to generate concentration profiles similar to those in the USP 2. Velocity profiles were obtained experimentally using Particle Image Velocimetry (PIV). Computational Fluid Dynamics (CFD) was used to predict the velocity distribution and strain rate around a model tablet...
January 13, 2018: International Journal of Pharmaceutics
Riccardo Rossi
We present a simple trick that allows us to consider the sum of all connected Feynman diagrams at fixed position of interaction vertices for general fermionic models, such that the thermodynamic limit can be taken analytically. With our approach one can achieve superior performance compared to conventional diagrammatic Monte Carlo algorithm, while rendering the algorithmic part dramatically simpler. By considering the sum of all connected diagrams at once, we allow for massive cancellations between different diagrams, greatly reducing the sign problem...
July 28, 2017: Physical Review Letters
Andrew S Darmawan, David Poulin
The surface code is a many-body quantum system, and simulating it in generic conditions is computationally hard. While the surface code is believed to have a high threshold, the numerical simulations used to establish this threshold are based on simplified noise models. We present a tensor-network algorithm for simulating error correction with the surface code under arbitrary local noise. We use this algorithm to study the threshold and the subthreshold behavior of the amplitude damping and systematic rotation channels...
July 28, 2017: Physical Review Letters
Alberto Camjayi, Liliana Arrachea, Armando Aligia, Felix von Oppen
Time-reversal-invariant topological superconducting (TRITOPS) wires are known to host a fractional spin ℏ/4 at their ends. We investigate how this fractional spin affects the Josephson current in a TRITOPS-quantum dot-TRITOPS Josephson junction, describing the wire in a model that can be tuned between a topological and a nontopological phase. We compute the equilibrium Josephson current of the full model by continuous-time Monte Carlo simulations and interpret the results within an effective low-energy theory...
July 28, 2017: Physical Review Letters
Sridhar Sadasivam, Maria K Y Chan, Pierre Darancet
We compute the transient dynamics of phonons in contact with high energy "hot" charge carriers in 12 polar and nonpolar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic temperature departs significantly from a single-exponential model at times ranging from 1 to 15 ps after electronic excitation, a phenomenon concomitant with the appearance of nonthermal vibrational modes. We demonstrate that these effects result from slow thermalization within the phonon subsystem, caused by the large heterogeneity in the time scales of electron-phonon and phonon-phonon interactions in these materials...
September 29, 2017: Physical Review Letters
Richard Brito, Shrobana Ghosh, Enrico Barausse, Emanuele Berti, Vitor Cardoso, Irina Dvorkin, Antoine Klein, Paolo Pani
Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models of massive and stellar-mass black hole populations to compute, for the first time, the stochastic gravitational-wave background from these sources. In optimistic scenarios the background is observable by Advanced LIGO and LISA for field masses m_{s} in the range ∼[2×10^{-13},10^{-12}] and ∼5×[10^{-19},10^{-16}]  eV, respectively, and it can affect the detectability of resolvable sources...
September 29, 2017: Physical Review Letters
Juan Bermejo-Vega, Nicolas Delfosse, Dan E Browne, Cihan Okay, Robert Raussendorf
A central question in quantum computation is to identify the resources that are responsible for quantum speed-up. Quantum contextuality has been recently shown to be a resource for quantum computation with magic states for odd-prime dimensional qudits and two-dimensional systems with real wave functions. The phenomenon of state-independent contextuality poses a priori an obstruction to characterizing the case of regular qubits, the fundamental building block of quantum computation. Here, we establish contextuality of magic states as a necessary resource for a large class of quantum computation schemes on qubits...
September 22, 2017: Physical Review Letters
Amangeldi Torayev, José Alexis Rucci, Pieter M Magusin, Arnaud Demortiere, Vincent De Andrade, Clare P Grey, Céline Merlet, Alejandro A Franco
While large dispersions in electrochemical performance have been reported for lithium oxygen batteries in the literature, they have not been investigated in any depth. The variability in the results is often assumed to arise from differences in cell design, electrode structure, handling and cell preparation at different times. An accurate theoretical framework turns out to be needed to get a better insight into the mechanisms underneath and to interpreting experimental results. Here, we develop and use a pore network model to simulate the electrochemical performance of three-dimensionally resolved lithium-oxygen cathode mesostructures obtained from TXM nano-computed tomography images...
January 17, 2018: Journal of Physical Chemistry Letters
Jose Navarrete, Chris Siefe, Samuel Alcantar, Michael Belt, Galen D Stucky, Martin Moskovits
Metallic nanostructures exhibit a strong plasmon resonance at a wavelength whose value is sensitive to the charge density in the nanostructure, its size, shape, interparticle coupling and the dielectric properties of its surrounding medium. Here we use UV-Visible transmission and reflectance spectroscopy to track the shifts of the plasmon resonance in an array of gold nanoparticles buried under metal-oxide layers of varying thickness produced using atomic layer deposition (ALD), then coated with bulk layers of one of three metals: aluminum, silver, and gold...
January 17, 2018: Nano Letters
Ramya Parasuram, Timothy A Coulther, Judith M Hollander, Elise Keston-Smith, Mary Jo Ondrechen, Penny J Beuning
The process of DNA replication is carried out with high efficiency and accuracy by DNA polymerases. The replicative polymerase in E. coli is DNA Pol III, which is a complex of 10 different subunits that coordinates simultaneous replication on the leading and lagging strands. The 1160-residue Pol III alpha subunit is responsible for the polymerase activity and copies DNA accurately, making one error per 105 nucleotide incorporations. The goal of this research is to determine the residues that contribute to the activity of the polymerase subunit...
January 17, 2018: Biochemistry
YangBo Hu, Huan Hu, LiYun Miao, Xin Zhao, Wei Gu, Wei Heng, ZiLi Meng, Jian Feng, Yi You, XingXiang Xu, Rong Hu, HaiQuan Li, Jie Zhao, XiaoLi Zhu, MeiQi Shi, Li Shen, XiuWei Zhang, XiaoWei Yin, Hang Ma, MinHua Shi, Yong Yu, Hong Lv, LiMing Cai, GaoHua Feng, YeQing Zhang, Feng Wu, TangFeng Lv, Yong Song
BACKGROUND: Jiangsu Province, China, is highly developed economically and culturally, and has a high prevalence of lung cancer. We aimed to evaluate the diagnostic procedures, genetic aberration analysis status, and first-line treatment models of lung cancer in Jiangsu Province. METHODS: Lung cancer patients diagnosed in 2016 at 22 tertiary care hospitals were evaluated. Demographic characteristics, tumor histology, staging, family history of lung cancer, auxiliary examinations, genetic testing, and first-line treatment were collected on discharge...
January 17, 2018: Thoracic Cancer
Pär Johansson, Sargon Barkarmo, Mohammed Hawthan, Niccolò Peruzzi, Per Kjellin, Ann Wennerberg
No abstract text is available yet for this article.
January 17, 2018: Journal of Biomedical Materials Research. Part A
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"