1,638 research outputs found
In Defense of Dynamical Explanation
Proponents of mechanistic explanation have argued that dynamical models are mere phenomenal models, in that they describe rather than explain the scientific phenomena produced by complex systems. I argue instead that dynamical models can, in fact, be explanatory. Using an example from neuroscientific research on epilepsy, I show that dynamical models can meet the explanatory demands met by mechanistic models, and as such occupy their own unique place within the space of explanatory scientific models
Global Action on Social Determinants of Health: National Approaches to Addressing Health Disparities
Strategies to address health disparities, including through a social determinants approach, vary according to stakeholders\u27principles, defined priorities, partners, evidence base, and understanding of pathways, not to mention political and economic factors. This presentation will look at the experiences of the Global Equity Gauge Alliance and the World Health Organization Commission on Social Determinants of Health in supporting local and national initiatives in Latin America, Africa and Asia to reduce disparities. The presentation will describe the frameworks proposed by GEGA and the WHO CSDH, present the initiatives adopted by several countries, explain how strategies were adapted to fit local and national priorities and conditions, and look at some of the common lessons learned
Infrared Evidence for Collagen Structures
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71134/2/JCPSA6-22-9-1621-1.pd
A Variational Principle Based Study of KPP Minimal Front Speeds in Random Shears
Variational principle for Kolmogorov-Petrovsky-Piskunov (KPP) minimal front
speeds provides an efficient tool for statistical speed analysis, as well as a
fast and accurate method for speed computation. A variational principle based
analysis is carried out on the ensemble of KPP speeds through spatially
stationary random shear flows inside infinite channel domains. In the regime of
small root mean square (rms) shear amplitude, the enhancement of the ensemble
averaged KPP front speeds is proved to obey the quadratic law under certain
shear moment conditions. Similarly, in the large rms amplitude regime, the
enhancement follows the linear law. In particular, both laws hold for the
Ornstein-Uhlenbeck process in case of two dimensional channels. An asymptotic
ensemble averaged speed formula is derived in the small rms regime and is
explicit in case of the Ornstein-Uhlenbeck process of the shear. Variational
principle based computation agrees with these analytical findings, and allows
further study on the speed enhancement distributions as well as the dependence
of enhancement on the shear covariance. Direct simulations in the small rms
regime suggest quadratic speed enhancement law for non-KPP nonlinearities.Comment: 28 pages, 14 figures update: fixed typos, refined estimates in
section
Isospin splitting of the nucleon mean field
The isospin splitting of the nucleon mean field is derived from the Brueckner
theory extended to asymmetric nuclear matter. The Argonne V18 has been adopted
as bare interaction in combination with a microscopic three body force. The
isospin splitting of the effective mass is determined from the
Brueckner-Hartree-Fock self-energy: It is linear acording to the Lane ansatz
and such that for neutron-rich matter. The symmetry potential
is also determined and a comparison is made with the predictions of the
Dirac-Brueckner approach and the phenomenological interactions. The theoretical
predictions are also compared with the empirical parametrizations of neutron
and proton optical-model potentials based on the experimental nucleon-nucleus
scattering and the phenomenological ones adopted in transport-model simulations
of heavy-ion collisions. The direct contribution of the rearrangement term due
to three-body forces to the single particle potential and symmetry potential is
discussed.Comment: 8 pages, 10 figure
Slowdown for time inhomogeneous branching Brownian motion
We consider the maximal displacement of one dimensional branching Brownian
motion with (macroscopically) time varying profiles. For monotone decreasing
variances, we show that the correction from linear displacement is not
logarithmic but rather proportional to . We conjecture that this is
the worse case correction possible
Integrating Low- and High-Level Skills in Instructional Protocols for Writing Disabilities
Twenty-four children with writing problems were given instruction in handwriting automaticity, spelling strategies, and the composing process (plan, write, review, revise) in 14 one-hour individual tutorials during the summer between third and fourth grade. Half the children (8 boys, 4 girls) received extra practice in composing, while half the children (8 boys, 4 girls) received special training in orthographic and phonological coding. Hierarchical linear modeling of growth curves was used to compare the treatment groups to a non-contact control group (10 boys, 5 girls) on a standard battery at pretest, midtest, posttest, and the two treatment groups with each other on probe measures of handwriting, spelling, and composition in each tutorial session. The treatment groups improved at a faster rate than the control group on some measures of handwriting, spelling, and composition (fluency and quality) in the standard battery, but Verbal IQ did not predict rate of improvement. Differences were found between the two treatment groups in some probe measures of writing and a motivation variable (work avoidance). Repeated-measures ANOVA was used to compare treatment groups to a non-contact control group at pretest, midtest, posttest, and follow-up. Differences between the treatment and control groups favoring the treatment groups were maintained at 6- month follow-up on some handwriting, spelling, and composition (quality) measures. Individual differences were found in learner characteristics prior to treatment and in response to the same treatment. The importance of affect and motivation as well as cognitive variables is emphasized
The influence of rumination and distraction on depressed and anxious mood: a prospective examination of the response styles theory in children and adolescents
The present study sought to test predictions of the response styles theory in a sample of children and adolescents. More specifically, a ratio approach to response styles was utilized to examine the effects on residual change scores in depression and anxiety. Participants completed a battery of questionnaires including measures of rumination, distraction, depression, and anxiety at baseline (Time 1) and 8–10 weeks follow-up (Time 2). Results showed that the ratio score of rumination and distraction was significantly associated with depressed and anxious symptoms over time. More specifically, individuals who have a greater tendency to ruminate compared to distracting themselves have increases in depression and anxiety scores over time, whereas those who have a greater tendency to engage in distraction compared to rumination have decreases in depression and anxiety symptoms over time. These findings indicate that a ratio approach can be used to examine the relation between response styles and symptoms of depression and anxiety in non-clinical children and adolescents. Implications of the results may be that engaging in distractive activities should be promoted and that ruminative thinking should be targeted in juvenile depression treatment
Coulomb Energy of Nuclei
The density functional determining the Coulomb energy of nuclei is calculated
to the first order in . It is shown that the Coulomb energy includes three
terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy
(CCE), which contributes considerably to the surface energy, the mass
difference between mirror nuclei, and the single-particle spectrum. A CCE-based
mechanism of a systematic shift of the single-particle spectrum is proposed. A
dominant contribution to the CCE is shown to come from the surface region of
nuclei. The CCE effect on the calculated proton drip line is examined, and the
maximum charge of nuclei near this line is found to decrease by 2 or 3
units. The effect of Coulomb interaction on the effective proton mass is
analyzed.Comment: 10 pages, Latex. Devoted to 90-th Anniversary of A.B. Migdal's
Birthda
Parity Violating Measurements of Neutron Densities
Parity violating electron nucleus scattering is a clean and powerful tool for
measuring the spatial distributions of neutrons in nuclei with unprecedented
accuracy. Parity violation arises from the interference of electromagnetic and
weak neutral amplitudes, and the of the Standard Model couples primarily
to neutrons at low . The data can be interpreted with as much confidence
as electromagnetic scattering. After briefly reviewing the present theoretical
and experimental knowledge of neutron densities, we discuss possible parity
violation measurements, their theoretical interpretation, and applications. The
experiments are feasible at existing facilities. We show that theoretical
corrections are either small or well understood, which makes the interpretation
clean. The quantitative relationship to atomic parity nonconservation
observables is examined, and we show that the electron scattering asymmetries
can be directly applied to atomic PNC because the observables have
approximately the same dependence on nuclear shape.Comment: 38 pages, 7 ps figures, very minor changes, submitted to Phys. Rev.
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