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Theory of constraints

Marjolein J A M van Dijk, Tom Claassen, Christiany Suwartono, William M van der Veld, Paul T van der Heijden, Marc P H Hendriks
OBJECTIVE: Since the publication of the WAIS-IV in the U.S. in 2008, efforts have been made to explore the structural validity by applying factor analysis to various samples. This study aims to achieve a more fine-grained understanding of the structure of the Dutch language version of the WAIS-IV (WAIS-IV-NL) by applying an alternative analysis based on causal modeling in addition to confirmatory factor analysis (CFA). The Bayesian Constraint-based Causal Discovery (BCCD) algorithm learns underlying network structures directly from data and assesses more complex structures than is possible with factor analysis...
July 20, 2017: Clinical Neuropsychologist
Michael J Kane, Georgina M Gross, Charlotte A Chun, Bridget A Smeekens, Matt E Meier, Paul J Silvia, Thomas R Kwapil
Undergraduates ( N = 274) participated in a weeklong daily-life experience-sampling study of mind wandering after being assessed in the lab for executive-control abilities (working memory capacity; attention-restraint ability; attention-constraint ability; and propensity for task-unrelated thoughts, or TUTs) and personality traits. Eight times a day, electronic devices prompted subjects to report on their current thoughts and context. Working memory capacity and attention abilities predicted subjects' TUT rates in the lab, but predicted the frequency of daily-life mind wandering only as a function of subjects' momentary attempts to concentrate...
July 1, 2017: Psychological Science
John Ellis, Nick E Mavromatos, Tevong You
The recent measurement by ATLAS of light-by-light scattering in LHC Pb-Pb collisions is the first direct evidence for this basic process. We find that it excludes a range of the mass scale of a nonlinear Born-Infeld extension of QED that is ≲100  GeV, a much stronger constraint than those derived previously. In the case of a Born-Infeld extension of the standard model in which the U(1)_{Y} hypercharge gauge symmetry is realized nonlinearly, the limit on the corresponding mass reach is ∼90  GeV, which, in turn, imposes a lower limit of ≳11  TeV on the magnetic monopole mass in such a U(1)_{Y} Born-Infeld theory...
June 30, 2017: Physical Review Letters
Stephanie T Child, Andrew T Kaczynski, Melissa L Fair, Ellen W Stowe, S Morgan Hughey, Lauren Boeckerman, Sally Wills, Yvonne Reeder
OBJECTIVE: The purpose of this study was to explore perceptions of the benefits of and influencing factors for neighborhood-based physical activity (PA), and elicit suggestions for increasing neighborhood-based PA among primarily Black residents living in lower income neighborhoods. DESIGN: Eight focus groups were conducted in low-income, predominantly Black neighborhoods (n = 8) in Greenville, SC during Spring 2014. Using a semi-structured focus group guide with open-ended questions, residents were asked to describe benefits of PA, neighborhood factors associated with PA, and ways to increase PA within their neighborhoods...
July 14, 2017: Ethnicity & Health
Wei-Lin Chen, Shiang-Tai Lin
The activity coefficient of a chemical in a mixture is important in understanding the thermodynamic properties and non-ideality of the mixture. The COSMO-SAC model based on the result of quantum mechanical implicit solvation calculations has been shown to provide reliable predictions of activity coefficients for mixed fluids. However, it is found that the prediction accuracy is in general inferior for associating fluids. Existing methods for describing the hydrogen-bonding interaction consider the strength of the interaction based only on the polarity of the screening charges, neglecting the fact that the formation of hydrogen bonds requires a specific orientation between the donor and acceptor pairs...
July 12, 2017: Physical Chemistry Chemical Physics: PCCP
Xieyining Huang, Jessica D Ribeiro, Katherine M Musacchio, Joseph C Franklin
BACKGROUND: Certain demographic factors have long been cited to confer risk or protection for suicidal thoughts and behaviors. However, many studies have found weak or non-significant effects. Determining the effect strength and clinical utility of demographics as predictors is crucial for suicide risk assessment and theory development. As such, we conducted a meta-analysis to determine the effect strength and clinical utility of demographics as predictors. METHODS: We searched PsycInfo, PubMed, and GoogleScholar for studies published before January 1st, 2015...
2017: PloS One
Eugene Stephane Mananga
In this work, we investigated the orders to which the Floquet-Magnus expansion (FME) and Fer expansion (FE) are equivalent or different for the three-level system. Specifically, we performed the third-order calculations of both approaches based on elegant integrations formalism. We present an important close relationship between the Floquet-Magnus and Fer expansions. As the propagator from the FME takes the form of the evolution operator which removes the constraint of a stroboscopic observation, we appreciated the effects of time-evolution under Hamiltonians with different orders separately...
July 12, 2017: Journal of Physical Chemistry. A
Tim Phillips
Evolutionary theory predicts competition in nature yet altruistic and cooperative behaviour appears to reduce the ability to compete in order to help others compete better. This evolutionary puzzle is usually explained by kin selection where close relatives perform altruistic and cooperative acts to help each other and by reciprocity theory (i.e. direct, indirect and generalized reciprocity) among non-kin. Here, it is proposed that the concepts of asymmetry and symmetry in power and dominance are critical if we are ever to resolve the puzzle of altruism and cooperation towards non-kin...
July 11, 2017: Biological Reviews of the Cambridge Philosophical Society
Daniel C Elton
We critically review the literature on the Debye absorption peak of liquid water and the excess response found on the high frequency side of the Debye peak. We find a lack of agreement on the microscopic phenomena underlying both of these features. To better understand the molecular origin of Debye peak we ran large scale molecular dynamics simulations and performed several different distance-dependent decompositions of the low frequency dielectric spectra, finding that it involves processes that take place on scales of 1...
July 11, 2017: Physical Chemistry Chemical Physics: PCCP
Ulrich Pferschy, Rostislav Staněk
The traveling salesman problem (TSP) is one of the most prominent combinatorial optimization problems. Given a complete graph [Formula: see text] and non-negative distances d for every edge, the TSP asks for a shortest tour through all vertices with respect to the distances d. The method of choice for solving the TSP to optimality is a branch and cut approach. Usually the integrality constraints are relaxed first and all separation processes to identify violated inequalities are done on fractional solutions...
2017: Cent Eur J Oper Res
Cinzia Muriana
Today, the role of the supply chain (SC) strategies in Food-Waste/Losses (F-W/L) generation is neglected, because F-W/L are generally considered an unavoidable consequence of accidental events. Therefore, only operating plans are today put into practice, which aim at reducing the impact of product losses along the SC. This involves that structured analyses and strategic SC approaches are not available for the prevention/minimization of F-W/L. The paper aims at changing the perspective, and promoting the hypothesis that generation of F-W/L mainly depends on the SC strategies put into practice that are usually optimized on the basis of the market demand...
July 5, 2017: Waste Management
Robert P Spunt, Ralph Adolphs
The concept of domain specificity - which suggests that some aspects of neural processing are specialized for particular types of stimuli - has been invoked to explain a range of cognitive phenomena, including language, face perception and theory of mind, and has been a hallmark of theories of cognitive architecture. More recent usage of this concept draws on neuroscientific data and, in particular, on work in social neuroscience. A critical examination of the part that the concept of domain specificity has played in theories of human brain function leads us to suggest a new view according to which domain specificity pertains to centrally generated constraints on information processing that can be both dynamic and context sensitive...
July 6, 2017: Nature Reviews. Neuroscience
Reuben Strydom, Mandyam Srinivasan
The aim of this study is to derive a guidance law by which an Unmanned Aerial System(s) (UAS) can pursue a moving target at a constant distance, while concealing its own motion. We derive a closed-form solution for the trajectory of the UAS by imposing two key constraints: (1) the shadower moves in such a way as to be perceived as a stationary object by the shadowee, and (2) the distance between the shadower and shadowee is kept constant. Additionally, the theory presented in this paper considers constraints on the maximum achievable speed and acceleration of the shadower...
July 4, 2017: Bioinspiration & Biomimetics
S R Kashuk, J Williams, G Thorpe, P H Wilson, G F Egan
Recent research has demonstrated that adults with probable Developmental Coordination Disorder (pDCD) show similar behavioural deficits as those observed in children DCD when performing a motor imagery task. The aim of this study was to investigate whether the pattern of neural activation in adults with pDCD during motor imagery differed from adults without motor skill impairment. Twelve adults with pDCD (5 male; age M=24.5 yrs) and 11 adults without pDCD (6 male; age M=26.7 yrs) participated. The hand rotation task was used to assess motor imagery ability, while functional neural images were acquired using a 3 Tesla MR scanner...
June 30, 2017: Behavioural Brain Research
László von Szentpály
It has been overlooked that the change of hardness, η, upon bonding is intimately connected to thermochemical cycles, which determine whether hardness is increased according to Pearson's "maximum hardness principle" (MHP) or equalized, as expected by Datta's "hardness equalization principle" (HEP). So far the performances of these likely incompatible "structural principles" have not been compared. Computational validations have been inconclusive because the hardness values and even their qualitative trends change drastically and unsystematically at different levels of theory...
July 2017: Journal of Molecular Modeling
Omri Barak
Recurrent neural networks (RNNs) are a class of computational models that are often used as a tool to explain neurobiological phenomena, considering anatomical, electrophysiological and computational constraints. RNNs can either be designed to implement a certain dynamical principle, or they can be trained by input-output examples. Recently, there has been large progress in utilizing trained RNNs both for computational tasks, and as explanations of neural phenomena. I will review how combining trained RNNs with reverse engineering can provide an alternative framework for modeling in neuroscience, potentially serving as a powerful hypothesis generation tool...
June 29, 2017: Current Opinion in Neurobiology
Steven A Benner
To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence and/or absence of life in this exotic locale? This question is, of course, relevant for life detection in any aqueous lagoon that we might be able to sample. This manuscript reviews physical chemical constraints that must be met by a genetic polymer for it to support Darwinism, a process believed to be required for a chemical system to generate properties that we value in biology...
June 30, 2017: Astrobiology
Johannes Weickenmeier, Cedric Fischer, Dennis Carter, Ellen Kuhl, Alain Goriely
After birth, the skull grows and remodels in close synchrony with the brain to allow for an increase in intracranial volume. Increase in skull area is provided primarily by bone accretion at the sutures. Additional remodeling, to allow for a change in curvatures, occurs by resorption on the inner surface of the bone plates and accretion on their outer surfaces. When a suture fuses too early, normal skull growth is disrupted, leading to a deformed final skull shape. The leading theory assumes that the main stimulus for skull growth is provided by mechanical stresses...
June 16, 2017: Physical Review Letters
Carolyn R Hodges-Simeon, Sean P Prall, Aaron D Blackwell, Michael Gurven, Steven J C Gaulin
OBJECTIVES: Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for potential life-history associations with growth and mucosal immunity in a rural population of immune-challenged Bolivian juveniles and adolescents...
June 27, 2017: American Journal of Human Biology: the Official Journal of the Human Biology Council
Mark Blokpoel
In this commentary, I advocate for strict relations between Marr's levels of analysis. Under a strict relationship, each level is exactly implemented by the subordinate level. This yields two benefits. First, it brings consistency for multilevel explanations. Second, similar to how a sculptor chisels away superfluous marble, a modeler can chisel a computational-level model by applying constraints. By sculpting the model, one restricts the (potentially infinitely large) set of possible algorithmic- and implementational-level theories...
June 27, 2017: Topics in Cognitive Science
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