Read by QxMD icon Read

Theory of constraints

N Sato, Z Yoshida
Topological constraints on a dynamical system often manifest themselves as breaking of the Hamiltonian structure; well-known examples are nonholonomic constraints on Lagrangian mechanics. The statistical mechanics under such topological constraints is the subject of this study. Conventional arguments based on phase spaces, Jacobi identity, invariant measure, or the H theorem are no longer applicable since all these notions stem from the symplectic geometry underlying canonical Hamiltonian systems. Remembering that Hamiltonian systems are endowed with field tensors (canonical 2-forms) that have zero helicity, our mission is to extend the scope toward the class of systems governed by finite-helicity field tensors...
February 2018: Physical Review. E
Giovani L Vasconcelos, Domingos S P Salazar, A M S Macêdo
A formalism, called H-theory, is applied to the problem of statistical equilibrium of a hierarchical complex system with multiple time and length scales. In this approach, the system is formally treated as being composed of a small subsystem-representing the region where the measurements are made-in contact with a set of "nested heat reservoirs" corresponding to the hierarchical structure of the system, where the temperatures of the reservoirs are allowed to fluctuate owing to the complex interactions between degrees of freedom at different scales...
February 2018: Physical Review. E
Sarah Jane Holcombe
Unsafe abortion is one of the three leading causes of maternal mortality in low-income countries; however, few countries have reformed their laws to permit safer, legal abortion, and professional medical associations have not tended to spearhead this type of reform. Support from a professional association typically carries more weight than does that from an individual medical professional. However, theory predicts and the empirical record largely reveals that medical associations shy from engagement in conflictual policymaking such as on abortion, except when professional autonomy or income is at stake...
March 12, 2018: Health Policy and Planning
Wendy D Manning, Monica A Longmore, Peggy C Giordano
In recent years, a majority of young adults experience cohabitation. Nevertheless, cohabitation is a risk factor for intimate partner violence (IPV). Drawing on social exchange and commitment theory we analyzed young adults' IPV experiences using the recently collected (2011-2012) Toledo Adolescent Relationships Study data (n = 926). We found that sociodemographic characteristics, relationship commitment, quality, and constraints as well as prior experience with violence (in prior relationships and family of origin) were associated with IPV, but did not explain the association between cohabitation and IPV...
March 2018: Journal of Family Issues
G Zhou, K P Wang, H W Liu, L Wang, X F Xiao, D D Dou, Y B Fan
Owing to low bearing capacity and efficiency, traditional filters or adsorbents for removal of contaminants like crystal violet (CV) dye required frequent replacement. Besides, the combination of three-dimensional (3D) printing and bionics could break the constraints of traditional configuration. In this study, a novel depth-type hybrid polylactic acid (PLA)@graphene oxide (GO)/chitosan (CS) sponge filter with bionic fish-mouth structure was prepared and fabricated, assisted by 3D printing and double freeze-drying technology, according to the theories of vertical cross-step filtration and swirling flow...
March 9, 2018: International Journal of Biological Macromolecules
Sophia Uddin, Shannon L M Heald, Stephen C Van Hedger, Howard C Nusbaum
Environmental sounds (ES) can be understood easily when substituted for words in sentences, suggesting that linguistic context benefits may be mediated by processes more general than some language-specific theories assert. However, the underlying neural processing is not understood. EEG was recorded for spoken sentences ending in either a spoken word or a corresponding ES. Endings were either congruent or incongruent with the sentence frame, and thus were expected to produce N400 activity. However, if ES and word meanings are combined with language context by different mechanisms, different N400 responses would be expected...
March 6, 2018: Brain and Language
Colin Klein, Peter Clutton, Vince Polito
Conspiracy theories play a troubling role in political discourse. Online forums provide a valuable window into everyday conspiracy theorizing, and can give a clue to the motivations and interests of those who post in such forums. Yet this online activity can be difficult to quantify and study. We describe a unique approach to studying online conspiracy theorists which used non-negative matrix factorization to create a topic model of authors' contributions to the main conspiracy forum on This subreddit provides a large corpus of comments which spans many years and numerous authors...
2018: Frontiers in Psychology
Bonan Jin, Xiaosu Xu, Tao Zhang
Finding the position of a radiative source based on time-difference-of-arrival (TDOA) measurements from spatially separated receivers has been widely applied in sonar, radar, mobile communications and sensor networks. For the nonlinear model in the process of positioning, Taylor series and other novel methods are proposed. The idea of cone constraint provides a new way of solving this problem. However, these approaches do not always perform well and are away from the Cramer-Rao-Lower-Bound (CRLB) in the situations when the source is set at the array edge, the noise in measurement is loud, or the initial position is biased...
March 4, 2018: Sensors
Sean T Hunt, Yuriy Román-Leshkov
Conspecuts Commercial and emerging renewable energy technologies are underpinned by precious metal catalysts, which enable the transformation of reactants into useful products. However, the noble metals (NMs) comprise the least abundant elements in the lithosphere, making them prohibitively scarce and expensive for future global-scale technologies. As such, intense research efforts have been devoted to eliminating or substantially reducing the loadings of NMs in various catalytic applications. These efforts have resulted in a plethora of heterogeneous NM catalyst morphologies beyond the traditional supported spherical nanoparticle...
March 6, 2018: Accounts of Chemical Research
David Zwicker, Rodolfo Ostilla-Mónico, Daniel E Lieberman, Michael P Brenner
The nasal cavity is a vital component of the respiratory system that heats and humidifies inhaled air in all vertebrates. Despite this common function, the shapes of nasal cavities vary widely across animals. To understand this variability, we here connect nasal geometry to its function by theoretically studying the airflow and the associated scalar exchange that describes heating and humidification. We find that optimal geometries, which have minimal resistance for a given exchange efficiency, have a constant gap width between their side walls, while their overall shape can adhere to the geometric constraints imposed by the head...
March 5, 2018: Proceedings of the National Academy of Sciences of the United States of America
Yadvinder Malhi, Tobias Jackson, Lisa Patrick Bentley, Alvaro Lau, Alexander Shenkin, Martin Herold, Kim Calders, Harm Bartholomeus, Mathias I Disney
Terrestrial laser scanning (TLS) opens up the possibility of describing the three-dimensional structures of trees in natural environments with unprecedented detail and accuracy. It is already being extensively applied to describe how ecosystem biomass and structure vary between sites, but can also facilitate major advances in developing and testing mechanistic theories of tree form and forest structure, thereby enabling us to understand why trees and forests have the biomass and three-dimensional structure they do...
April 6, 2018: Interface Focus
Rosemary L Hopcroft
Fitness is always relative to the fitness of others in the group or breeding population. Even in very low-fertility societies, individual fitness as measured by the share of genes in subsequent generations may still be maximized. Further, sexual selection theory from evolutionary biology suggests that the relationship between status and fertility will differ for males and females. For this reason it is important to examine the relationship between status and fertility separately for males and females-something few demographic studies of fertility do...
March 5, 2018: Journal of Biosocial Science
John S Lomas
Density functional theory calculations are used to compute proton NMR chemical shifts, interatomic distances, atom-atom interaction energies and atomic charges for partial structures and conformers of α-D-glucopyranose, β-D-glucopyranose and α-D-galactopyranose built up by introducing OH groups into 2-methyltetrahydropyran stepwisely. For the counter-clockwise conformers the most marked effects on the NMR shift and the charge on the OH1 proton are produced by OH2, those of OH3 and OH4 being somewhat smaller...
March 1, 2018: Magnetic Resonance in Chemistry: MRC
Caitlin Lanssens, Paul W Ayers, Dimitri Van Neck, Stijn De Baerdemacker, Klaas Gunst, Patrick Bultinck
In methods like geminal-based approaches or coupled cluster that are solved using the projected Schrödinger equation, direct computation of the 2-electron reduced density matrix (2-RDM) is impractical and one falls back to a 2-RDM based on response theory. However, the 2-RDMs from response theory are not N-representable. That is, the response 2-RDM does not correspond to an actual physical N-electron wave function. We present a new algorithm for making these non-N-representable 2-RDMs approximately N-representable, i...
February 28, 2018: Journal of Chemical Physics
Yinsheng Li, John William Garrett, Ke Li, Yijing Wu, Kevin Johnson, Sebastian Schafer, Charles Strother, Guang-Hong Chen
Time-resolved C-arm cone-beam CT (CBCT) angiography (TR-CBCTA) images can be generated from a series of CBCT acquisitions that satisfy data sufficiency condition in analytical image reconstruction theory. In this work, a new technique was developed to generate TR-CBCTA images from a single short-scan CBCT data acquisition with contrast media injection. The reconstruction technique enabling this application is a previously developed image reconstruction technique, Synchronized Multi-Artifact Reduction with Tomographic Reconstruction (SMART-RECON)...
March 1, 2018: Physics in Medicine and Biology
Samuel Edelbring, Ioannis Parodis, Ingrid E Lundberg
BACKGROUND: Collaborative reasoning occurs in clinical practice but is rarely developed during education. The computerized virtual patient (VP) cases allow for a stepwise exploration of cases and thus stimulate active learning. Peer settings during VP sessions are believed to have benefits in terms of reasoning but have received scant attention in the literature. OBJECTIVE: The objective of this study was to thoroughly investigate interactions during medical students' clinical reasoning in two-party VP settings...
February 27, 2018: JMIR Medical Education
Brandi West, Sarah Rodriguez Castillo, Alicia Sit, Sabria Mohamad, Bethany Lowe, Christine Joblin, Andras Bodi, Paul M Mayer
Imaging photoelectron photoion coincidence spectroscopy was employed to explore the unimolecular dissociation of the ionized polycyclic aromatic hydrocarbons (PAHs) acenaphthylene, fluorene, cyclopenta[d,e,f]phenanthrene, pyrene, perylene, fluoranthene, dibenzo[a,e]pyrene, dibenzo[a,l]pyrene, coronene and corannulene. The primary reaction is always hydrogen atom loss, with the smaller species also exhibiting loss of C2 H2 to varying extents. Combined with previous work on smaller PAH ions, trends in the reaction energies (E0 ) for loss of H from sp2 -C and sp3 -C centres, along with hydrocarbon molecule loss were found as a function of the number of carbon atoms in the ionized PAHs ranging in size from naphthalene to coronene...
February 26, 2018: Physical Chemistry Chemical Physics: PCCP
Yingtian Yu, N M Anoop Krishnan, Morten M Smedskjaer, Gaurav Sant, Mathieu Bauchy
The surface reactivity and hydrophilicity of silicate materials are key properties for various industrial applications. However, the structural origin of their affinity for water remains unclear. Here, based on reactive molecular dynamics simulations of a series of artificial glassy silica surfaces annealed at various temperatures and subsequently exposed to water, we show that silica exhibits a hydrophilic-to-hydrophobic transition driven by its silanol surface density. By applying topological constraint theory, we show that the surface reactivity and hydrophilic/hydrophobic character of silica are controlled by the atomic topology of its surface...
February 21, 2018: Journal of Chemical Physics
Patrick Ishizuka
In recent decades, cohabitation has become an increasingly important relationship context for U.S. adults and their children, a union status characterized by high levels of instability. To understand why some cohabiting couples marry but others separate, researchers have drawn on theories emphasizing the benefits of specialization, the persistence of the male breadwinner norm, low income as a source of stress and conflict, and rising economic standards associated with marriage (the marriage bar). Because of conflicting evidence and data constraints, however, important theoretical questions remain...
February 22, 2018: Demography
Gustavo M Tavares, Filipe Sobral, Rafael Goldszmidt, Felipe Araújo
Although research on implicit leadership theories (ILTs) has concentrated on determining which attributes define a leadership prototype, little attention has been paid to testing the relative importance of each of these attributes for individuals' leadership perceptions. Building on socio-cognitive theories of impression processes, we experimentally explore the formation of leadership perceptions based on the recognition of six key attributes in a series of three experimental studies comprising 566 US-based participants recruited online via Amazon Mechanical Turk...
2018: Frontiers in Psychology
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"