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Theory of constraints

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https://www.readbyqxmd.com/read/27930304/emergent-oscillations-assist-obstacle-negotiation-during-ant-cooperative-transport
#1
Aviram Gelblum, Itai Pinkoviezky, Ehud Fonio, Nir S Gov, Ofer Feinerman
Collective motion by animal groups is affected by internal interactions, external constraints, and the influx of information. A quantitative understanding of how these different factors give rise to different modes of collective motion is, at present, lacking. Here, we study how ants that cooperatively transport a large food item react to an obstacle blocking their path. Combining experiments with a statistical physics model of mechanically coupled active agents, we show that the constraint induces a deterministic collective oscillatory mode that facilitates obstacle circumvention...
December 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27924867/constraints-and-spandrels-of-interareal-connectomes
#2
Mikail Rubinov
Interareal connectomes are whole-brain wiring diagrams of white-matter pathways. Recent studies have identified modules, hubs, module hierarchies and rich clubs as structural hallmarks of these wiring diagrams. An influential current theory postulates that connectome modules are adequately explained by evolutionary pressures for wiring economy, but that the other hallmarks are not explained by such pressures and are therefore less trivial. Here, we use constraint network models to test these postulates in current gold-standard vertebrate and invertebrate interareal-connectome reconstructions...
December 7, 2016: Nature Communications
https://www.readbyqxmd.com/read/27917505/might-constraint-be-compatible-with-care-home-care-as-a-situational-ethics
#3
Antoine Hennion, Pierre A Vidal-Naquet
Respecting the autonomy and will of people has legitimately led to strictly control the use of constraint in care activities, and promote a care ethics centred around people's needs and wills. But constraint is underlying in any action aiming at making people do something, even with their consent, especially when their ability to evaluate what is best for them may be altered. Ceaselessly present in care, this ordinary, silent constraint should not be only deemed as a necessary evil to be prevented. In contrast with this legally-based view, the paper adopts a pragmatic perspective...
December 5, 2016: Sociology of Health & Illness
https://www.readbyqxmd.com/read/27915074/evolutionary-stability-for-matrix-games-under-time-constraints
#4
József Garay, Villő Csiszár, Tamás F Móri
Game theory focuses on payoffs and typically ignores time constraints that play an important role in evolutionary processes where the repetition of games can depend on the strategies, too. We introduce a matrix game under time constraints, where each pairwise interaction has two consequences: both players receive a payoff and they cannot play the next game for a specified time duration. Thus our model is defined by two matrices: a payoff matrix and an average time duration matrix. Maynard Smith's concept of evolutionary stability is extended to this class of games...
November 30, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/27911565/radiative-screening-of-fifth-forces
#5
Clare Burrage, Edmund J Copeland, Peter Millington
We describe a symmetron model in which the screening of fifth forces arises at the one-loop level through the Coleman-Weinberg mechanism of spontaneous symmetry breaking. We show that such a theory can avoid current constraints on the existence of fifth forces but still has the potential to give rise to observable deviations from general relativity, which could be seen in cold atom experiments.
November 18, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27911490/what-does-it-take-to-learn-a-word
#6
REVIEW
Larissa K Samuelson, Bob McMurray
Vocabulary learning is deceptively hard, but toddlers often make it look easy. Prior theories proposed that children's rapid acquisition of words is based on language-specific knowledge and constraints. In contrast, more recent work converges on the view that word learning proceeds via domain-general processes that are tuned to richly structured-not impoverished-input. We argue that new theoretical insights, coupled with methodological tools, have pushed the field toward an appreciation of simple, content-free processes working together as a system to support the acquisition of words...
December 1, 2016: Wiley Interdisciplinary Reviews. Cognitive Science
https://www.readbyqxmd.com/read/27906316/ring-modulators-with-enhanced-efficiency-based-on-standing-wave-operation-on-a-field-matched-interdigitated-p-n-junction
#7
Fabio Pavanello, Xiaoge Zeng, Mark T Wade, Miloš A Popović
We propose ring modulators based on interdigitated p-n junctions that exploit standing rather than traveling-wave resonant modes to improve modulation efficiency, insertion loss and speed. Matching the longitudinal nodes and antinodes of a standing-wave mode with high (contacts) and low (depletion regions) carrier density regions, respectively, simultaneously lowers loss and increases sensitivity significantly. This approach permits further to relax optical constraints on contacts placement and can lead to lower device capacitance...
November 28, 2016: Optics Express
https://www.readbyqxmd.com/read/27906268/upper-bound-of-signal-relevant-efficiency-of-constrained-diffractive-elements
#8
Antonie D Verhoeven, Harald Aagedal, Frank Wyrowski, Jari Turunen
We define the signal-relevant efficiency (SRE) of a diffractive optical element as a measure of the proportion of the incident field power that ends up in the desired output signal. An upper bound for SRE is determined in the presence of arbitrary constraints imposed on the element, such as phase-dependent loss due to absorption within the microstructure and quantization of the surface profile. We apply the theory to the important class of diffractive elements that contain only one desired diffraction order (such as diffractive lenses) and derive the surface profile that provides the highest efficiency allowed by the constraints...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/27906033/the-role-of-the-backbone-torsion-in-protein-folding
#9
EDITORIAL
Irina Sorokina, Arcady Mushegian
BACKGROUND: The set of forces and sequence of events that govern the transition from an unfolded polypeptide chain to a functional protein with correct spatial structure remain incompletely known, despite the importance of the problem and decades of theory development, computer simulations, and laboratory experiments. Information about the correctly folded state of most proteins is likely to be present in their sequences, and yet many proteins fail to attain native structure after overexpression in a non-native environment or upon experimental denaturation and refolding...
December 1, 2016: Biology Direct
https://www.readbyqxmd.com/read/27889387/diet-microbiome-interactions-in-health-are-controlled-by-intestinal-nitrogen-source-constraints
#10
Andrew J Holmes, Yi Vee Chew, Feyza Colakoglu, John B Cliff, Eline Klaassens, Mark N Read, Samantha M Solon-Biet, Aisling C McMahon, Victoria C Cogger, Kari Ruohonen, David Raubenheimer, David G Le Couteur, Stephen J Simpson
Diet influences health and patterns of disease in populations. How different diets do this and why outcomes of diets vary between individuals are complex and involve interaction with the gut microbiome. A major challenge for predicting health outcomes of the host-microbiome dynamic is reconciling the effects of different aspects of diet (food composition or intake rate) on the system. Here we show that microbial community assembly is fundamentally shaped by a dichotomy in bacterial strategies to access nitrogen in the gut environment...
November 15, 2016: Cell Metabolism
https://www.readbyqxmd.com/read/27882654/digital-technologies-as-truth-bearers-in-health-care
#11
Ruth Bartlett, Andrew Balmer, Petula Brannelly
In this study, we explore the idea of digital technologies as truth-bearers in health care and argue that devices like SenseCam, which facilitate reflection and memory recall, have a potentially vital role in healthcare situations when questions of veracity are at stake (e.g., when best interest decisions are being made). We discuss the role of digital technologies as truth-bearers in the context of nursing people with dementia, as this is one area of health care in which the topic of truth-telling has been hotly debated...
November 23, 2016: Nursing Philosophy: An International Journal for Healthcare Professionals
https://www.readbyqxmd.com/read/27881432/what-not-to-expect-when-classifying-rare-events
#12
Rok Blagus, Jelle J Goeman
When building classifiers, it is natural to require that the classifier correctly estimates the event probability (Constraint 1), that it has equal sensitivity and specificity (Constraint 2) or that it has equal positive and negative predictive values (Constraint 3). We prove that in the balanced case, where there is equal proportion of events and non-events, any classifier that satisfies one of these constraints will always satisfy all. Such unbiasedness of events and non-events is much more difficult to achieve in the case of rare events, i...
November 22, 2016: Briefings in Bioinformatics
https://www.readbyqxmd.com/read/27874982/rethinking-presence-a-grounded-theory-of-nurses-and-teleconsultation
#13
David Barrett
AIMS AND OBJECTIVES: The study aimed to develop a theory that offered an evidence-based insight into the use of teleconsultation by nurses. BACKGROUND: Teleconsultation is the use of video to facilitate real-time, remote interaction between healthcare practitioners and patients. Though its popularity is growing, there is little understanding of how teleconsultation impacts on the role of nurses. METHOD: The study adopted a constructivist grounded theory method, supplemented by the use of Straussian analytical approaches...
November 22, 2016: Journal of Clinical Nursing
https://www.readbyqxmd.com/read/27874727/socialization-processes-and-clergy-offenders
#14
Jane Anderson
This article uses feminist theory to investigate how the socialization processes used to maintain the clergy community in the Roman Catholic Church contributes to a vulnerability in some clergy for sexually abusing children. This vulnerability is identified first in an examination of the literature on the impact of socialization processes on clergy offenders between the 1960s and 1980s. A comparison is then made with the implications of the apostolic exhortation, Pastores Dabo Vobis, which provides a theological basis to clergy formation...
November 2016: Journal of Child Sexual Abuse
https://www.readbyqxmd.com/read/27872367/the-neurobiology-of-uncertainty-implications-for-statistical-learning
#15
REVIEW
Uri Hasson
The capacity for assessing the degree of uncertainty in the environment relies on estimating statistics of temporally unfolding inputs. This, in turn, allows calibration of predictive and bottom-up processing, and signalling changes in temporally unfolding environmental features. In the last decade, several studies have examined how the brain codes for and responds to input uncertainty. Initial neurobiological experiments implicated frontoparietal and hippocampal systems, based largely on paradigms that manipulated distributional features of visual stimuli...
January 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/27870559/combinatorial-methods-for-epistasis-and-dominance
#16
Serge Sverdlov, Elizabeth Thompson
We develop computational tools for the analysis of nonlinear genotype-phenotype relationships with epistasis among multiple loci or dominance interactions among multiple alleles within the same locus. Theory distinguishes between separable traits, with removable epistasis, and traits with essential epistasis. Separable traits can be transformed to a natural scale where additive methods apply. The methods we present solve for the natural scale, exactly when possible and approximately when not. Through graph methods, our methods allow for enumeration, counting, or sampling of distinct trait architectures satisfying constraints from the separability theory...
November 21, 2016: Journal of Computational Biology: a Journal of Computational Molecular Cell Biology
https://www.readbyqxmd.com/read/27868314/experimental-whole-stream-warming-alters-community-size-structure
#17
Daniel Nelson, Jonathan P Benstead, Alexander D Huryn, Wyatt F Cross, James M Hood, Philip W Johnson, James R Junker, Gísli M Gíslason, Jón S Ólafsson
How ecological communities respond to predicted increases in temperature will determine the extent to which Earth's biodiversity and ecosystem functioning can be maintained into a warmer future. Warming is predicted to alter the structure of natural communities, but robust tests of such predictions require appropriate large-scale manipulations of intact, natural habitat that is open to dispersal processes via exchange with regional species pools. Here we report results of a two-year whole-stream warming experiment that shifted invertebrate assemblage structure via unanticipated mechanisms, while still conforming to community-level metabolic theory...
November 21, 2016: Global Change Biology
https://www.readbyqxmd.com/read/27863104/joint-l2-1-norm-and-fisher-discrimination-constrained-feature-selection-for-rational-synthesis-of-microporous-aluminophosphates
#18
Miao Qi, Ting Wang, Yugen Yi, Na Gao, Jun Kong, Jianzhong Wang
Feature selection has been regarded as an effective tool to help researchers understand the generating process of data. For mining the synthesis mechanism of microporous AlPOs, this paper proposes a novel feature selection method by joint l2,1 norm and Fisher discrimination constraints (JNFDC). In order to obtain more effective feature subset, the proposed method can be achieved in two steps. The first step is to rank the features according to sparse and discriminative constraints. The second step is to establish predictive model with the ranked features, and select the most significant features in the light of the contribution of improving the predictive accuracy...
November 9, 2016: Molecular Informatics
https://www.readbyqxmd.com/read/27861813/consequences-of-genetic-linkage-for-the-maintenance-of-sexually-antagonistic-polymorphism-in-hermaphrodites
#19
Colin Olito
When selection differs between males and females, pleiotropic effects among genes expressed by both sexes can result in sexually antagonistic selection (SA), where beneficial alleles for one sex are deleterious for the other. For hermaphrodites, alleles with opposing fitness effects through each sex function represent analogous genetic constraints on fitness. Recent theory based on single-locus models predicts that the maintenance of SA genetic variation should be greatly reduced in partially selfing populations...
November 9, 2016: Evolution; International Journal of Organic Evolution
https://www.readbyqxmd.com/read/27859120/disease-introduction-is-associated-with-a-phase-transition-in-bighorn-sheep-demographics
#20
Kezia Manlove, E Frances Cassirer, Paul C Cross, Raina K Plowright, Peter J Hudson
Ecological theory suggests that pathogens are capable of regulating or limiting host population dynamics, and this relationship has been empirically established in several settings. However, although studies of childhood diseases were integral to the development of disease ecology, few studies show population limitation by a disease affecting juveniles. Here, we present empirical evidence that disease in lambs constrains population growth in bighorn sheep (Ovis canadensis) based on 45 years of population-level and 18 years of individual-level monitoring across 12 populations...
October 2016: Ecology
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