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Alexander Kotelsky, Chandler W Woo, Luis F Delgadillo, Michael S Richards, Mark R Buckley
With the onset and progression of osteoarthritis (OA), articular cartilage (AC) mechanical properties are altered. These alterations can serve as an objective measure of tissue degradation. Although the mouse is a common and useful animal model for studying OA, it is extremely challenging to measure the mechanical properties of murine AC due to its small size (thickness < 50 um). In this study, we developed novel and direct approach to independently quantify two quasi-static mechanical properties of mouse AC: the load-dependent (non-linear) solid matrix Young's modulus (E) and drained Poisson ratio (v)...
October 10, 2017: Journal of Biomechanical Engineering
Peep Adamson
A new optical method for determining anisotropic dielectric constants of graphene-like two-dimensional materials on semiconductor or metal substrates is developed. The method is based on the surface differential reflectance measurements at three different incident angles. The inversion problem is resolved analytically in a long-wavelength approximation, where graphene is discussed within the framework of macroscopic electrodynamics as a uniaxially anisotropic film with the optical axis perpendicular to the film surface...
October 1, 2017: Applied Optics
Dylan Molenaar, Maria Bolsinova, Jeroen K Vermunt
In item response theory, modelling the item response times in addition to the item responses may improve the detection of possible between- and within-subject differences in the process that resulted in the responses. For instance, if respondents rely on rapid guessing on some items but not on all, the joint distribution of the responses and response times will be a multivariate within-subject mixture distribution. Suitable parametric methods to detect these within-subject differences have been proposed. In these approaches, a distribution needs to be assumed for the within-class response times...
October 17, 2017: British Journal of Mathematical and Statistical Psychology
Sean James Fallon, Rozemarijn Margaretha Mattiesing, Kinan Muhammed, Sanjay Manohar, Masud Husain
Deficits in working memory (WM) in Parkinson's disease (PD) are often considered to be secondary to dopaminergic depletion. However, the neurocognitive mechanisms by which dopamine causes these deficits remain highly contested, and PD is now also known to be associated with nondopaminergic pathology. Here, we examined how PD and dopaminergic medication modulate three components of WM: maintenance over time, updating contents with new information and making memories distracter-resistant. Compared with controls, patients were disproportionately impaired when retaining information for longer durations...
October 13, 2017: Cerebral Cortex
Aditi Krishnapriyan, Ping Yang, Anders M N Niklasson, Marc J Cawkwell
New parameterizations for semi-empirical density functional tight binding (DFTB) theory have been developed by the numerical optimization of adjustable parameters to minimize errors in the atomization energy and interatomic forces with respect to ab initio calculated data. Initial guesses for the radial dependences of the Slater-Koster bond integrals and overlap integrals were obtained from minimum basis density functional theory calculations. The radial dependences of the pair potentials and the bond and overlap integrals were represented by simple analytic functions...
October 17, 2017: Journal of Chemical Theory and Computation
Mohamed Hafid, Marcel Lacroix
Cryosurgery has become a well-established technique for the ablation of undesirable tissues such as tumors and cancers. The motivation for this study is to improve the efficacy and safety of this technique. This study presents an inverse heat transfer method for monitoring the motion of the freezing front from a cryoprobe. With the help of a thermocouple inserted into the layer of diseased tissue, the inverse heat transfer method estimates simultaneously the blood perfusion rate and the thermal conductivities of both frozen and unfrozen tissues...
October 2017: Journal of Thermal Biology
Robert M Nosofsky, Jason M Gold
Research is reported that provides evidence for a significant role of mixed states and guessing processes in tasks of visual working memory (VWM). Subjects engaged in a complete-identification VWM task. The stimulus set consisted of 16 colors roughly equally spaced around a color circle. On each trial, a memory-set drawn from the colors was briefly presented, followed by a location probe. Subjects attempted to reproduce the color of the probed item by clicking on the appropriate response button of a discrete color wheel...
October 16, 2017: Journal of Experimental Psychology. Human Perception and Performance
Paula Carneiro, Ana Lapa, Bridgid Finn
It is well known that successful retrieval enhances subsequent adults' learning by promoting long-term retention. Recent research has also found benefits from unsuccessful retrieval, but the evidence is not as clear-cut when the participants are children. In this study, we employed a methodology based on guessing-the weak associate paradigm-to test whether children can learn from generated errors or whether errors are harmful for learning. We tested second- and third-grade children in Experiment 1 and tested preschool and kindergarten children in Experiment 2...
October 12, 2017: Journal of Experimental Child Psychology
Patrick F Sullivan
No abstract text is available yet for this article.
November 15, 2017: Biological Psychiatry
Weile Jia, Lin Lin
Fermi operator expansion (FOE) methods are powerful alternatives to diagonalization type methods for solving Kohn-Sham density functional theory (KSDFT). One example is the pole expansion and selected inversion (PEXSI) method, which approximates the Fermi operator by rational matrix functions and reduces the computational complexity to at most quadratic scaling for solving KSDFT. Unlike diagonalization type methods, the chemical potential often cannot be directly read off from the result of a single step of evaluation of the Fermi operator...
October 14, 2017: Journal of Chemical Physics
Ryan Crone
No abstract text is available yet for this article.
September 2017: Techniques in Vascular and Interventional Radiology
A Fielding, Y Fu, E A Franz
What if the brain's response to reward occurs even when there is no reward? Wouldn't that be a further concern for people prone to problem gambling and other forms of addiction, like those related to eating? Electroencephalography was employed to investigate this possibility using probabilistic feedback manipulations and measures of known event-related potentials (ERPs) related to reward processing. We tested the hypothesis-that reward-based ERPs would occur even in the absence of a tangible reward and when manipulations on expectation are implicit...
October 12, 2017: Journal of Gambling Studies
Natania A Crane, Stephanie M Gorka, Jessica Weafer, Scott A Langenecker, Harriet de Wit, K Luan Phan
Aims: Dysfunctional brain reward circuitry, particularly in the nucleus accumbens (NAcc), has been proposed as a risk factor for alcohol use disorder (AUD). This risk factor may be evident in binge drinkers (BD), who are at high risk for developing AUD. We examined whole-brain and NAcc reactivity to reward in BD compared to non-binge drinkers (NBD), hypothesizing that groups would differ in their neural reactivity and connectivity. Methods: Healthy BD (N = 27) and NBD (N = 23)-none meeting AUD criteria-completed a reward-guessing game, the 'Doors' task, during functional magnetic resonance imaging...
September 8, 2017: Alcohol and Alcoholism: International Journal of the Medical Council on Alcoholism
Nicolas Burra, Alexis Hervais-Adelman, Alessia Celeghin, Beatrice de Gelder, Alan J Pegna
The human brain can process facial expressions of emotions rapidly and without awareness. Several studies in patients with damage to their primary visual cortices have shown that they may be able to guess the emotional expression on a face despite their cortical blindness. This non-conscious processing, called affective blindsight, may arise through an intact subcortical visual route that leads from the superior colliculus to the pulvinar, and thence to the amygdala. This pathway is thought to process the crude visual information conveyed by the low spatial frequencies of the stimuli...
October 6, 2017: Neuropsychologia
Nora Turoman, Suzy J Styles
In three experiments, we asked whether diverse scripts contain interpretable information about the speech sounds they represent. When presented with a pair of unfamiliar letters, adult readers correctly guess which is /i/ (the 'ee' sound in 'feet'), and which is /u/ (the 'oo' sound in 'shoe') at rates higher than expected by chance, as shown in a large sample of Singaporean university students (Experiment 1) and replicated in a larger sample of international Internet users (Experiment 2). To uncover what properties of the letters contribute to different scripts' 'guessability,' we analysed the visual spatial frequencies in each letter (Experiment 3)...
September 2017: Royal Society Open Science
Brandon Milholland, Xiao Dong, Jan Vijg
Using segmented linear regression to reanalyze the "best-guess" maximum reported age at death data supplied in Aubrey de Grey's editorial, we find compelling evidence for a breakpoint in the mid-1990s, with a positive slope before the breakpoint and a flat or slightly negative slope after it. This confirmation of our earlier results was also modeled using exponential regression. Both the segmented and exponential models were superior to a simple linear regression, providing a better fit for the data even after taking into account their greater number of parameters...
October 2017: Rejuvenation Research
Blaire Dube, Stephen M Emrich, Naseem Al-Aidroos
Across 2 experiments we revisited the filter account of how feature-based attention regulates visual working memory (VWM). Originally drawing from discrete-capacity ("slot") models, the filter account proposes that attention operates like the "bouncer in the brain," preventing distracting information from being encoded so that VWM resources are reserved for relevant information. Given recent challenges to the assumptions of discrete-capacity models, we investigated whether feature-based attention plays a broader role in regulating memory...
October 2017: Journal of Experimental Psychology. Human Perception and Performance
Julia J Rucklidge, Matthew J F Eggleston, Jeanette M Johnstone, Kathryn Darling, Chris M Frampton
BACKGROUND: Evaluation of broad-spectrum micronutrient (vitamins and minerals) treatment for childhood ADHD has been limited to open-label studies that highlight beneficial effects across many aspects of psychological functioning. METHOD: This is the first fully blinded randomized controlled trial of medication-free children (n = 93) with ADHD (7-12 years) assigned to either micronutrients (n = 47) or placebo (n = 46) in a 1:1 ratio, for 10 weeks. All children received standardized ADHD assessments...
October 2, 2017: Journal of Child Psychology and Psychiatry, and Allied Disciplines
Leif D Jacobson, Art D Bochevarov, Mark A Watson, Thomas F Hughes, David Rinaldo, Stephan Ehrlich, Thomas B Steinbrecher, S Vaitheeswaran, Dean M Philipp, Mathew D Halls, Richard A Friesner
Transition state search is at the center of multiple types of computational chemical predictions related to mechanistic investigations, reactivity and regioselectivity predictions, and catalyst design. The process of finding transition states in practice is however a laborious multistep operation that requires significant user involvement. Here we report a highly automated workflow designed to locate transition states for a given elementary reaction with a minimal setup overhead. The only essential inputs required from the user are the structures of the separated reactants and products...
September 28, 2017: Journal of Chemical Theory and Computation
Orianna DeMasi, Konrad Kording, Benjamin Recht
A new trend in medicine is the use of algorithms to analyze big datasets, e.g. using everything your phone measures about you for diagnostics or monitoring. However, these algorithms are commonly compared against weak baselines, which may contribute to excessive optimism. To assess how well an algorithm works, scientists typically ask how well its output correlates with medically assigned scores. Here we perform a meta-analysis to quantify how the literature evaluates their algorithms for monitoring mental wellbeing...
2017: PloS One
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