199 research outputs found
Temporal dynamics of a two-neuron continuous network model with time delay
AbstractIn this paper we consider a simple analog neural network model consisting of two continuous nonlinear neurons with delay in signal transmission under appropriate restrictions on internal parameters. We derive conditions for the existence of single steady-state conditions for asymptotic stability, stability switches about the steady state, and bifurcation of the linearized system
How do intrahousehold dynamics change when assets are transferred to women? Evidence from BRACâs challenging the frontiers of poverty reductionâtargeting the ultra poor program in Bangladesh
Growing evidence shows that the distribution of individuals' ownership and control of assets within a household can have important implications for womenâs empowerment and childrenâs well-being. Interventions that target assets to specific individuals can shift these intrahousehold dynamics, yet little evidence exists from rigorous evaluations. We study BRACâs Challenging the Frontiers of Poverty ReductionâTargeting the Ultra Poor (CFPR-TUP) program in Bangladesh, which targets asset transfer (primarily livestock) and training to rural women in poor households. Previous research has shown large, significant positive program impacts at the household level. In this paper, we examine intrahousehold impacts using mixed methods. We focus on the Specially Targeted Ultra-Poor(STUP) component of the program, which targets households selected following a randomized controlled trial design. Adding a new round of data collection with quantitative sex-disaggregated information and qualitative exploration, we exploit the randomized design to assess intrahousehold impacts of STUP. Our analysis confirms that the program significantly increases household ownership of various assets but has complex effects on the targeted women. Quantitative estimates show increases in womenâs sole and joint ownership of or control over transferred assets such as livestock, but a much greater increase in menâs sole ownership over nearly all other assets (including agricultural and nonagricultural productive assets, land, and consumer durables). These findings suggest that while the transferred assets tend to remain with women, new investments from mobilized resources are controlled by men. Moreover, the program reduces womenâs mobility outside the home and their control over income, consistent with the transferred assetâs requiring maintenance at home. Qualitative findings are consistent with these quantitative results , but womenâs contribution to their households is perceived as increasing their confidence and social capital, which they themselves value. Therefore, while provision of assets and training to women has ambiguous effects on womenâs empowerment in terms of tangible assets and decisionmaking, women take intangibles into account and largely perceive positive (though still mixed) effects. The analysis shows that asset transfer targeted to women can increase womenâs ownership of and control over the transferred asset itself but may not necessarily increase womenâs intrahousehold bargaining position. Moreover, it reveals that outcomes valued by individuals may not always be tangible, highlighting the complexity of assessing whether interventions improve womenâs empowerment
3D DDD modelling of dislocation-precipitate interaction in a nickel-based single crystal superalloy under cyclic deformation
Strain-controlled cyclic deformation of a nickel-based single crystal superalloy has been modelled by using three-dimensional (3D) discrete dislocation dynamics (DDD) for both [001] and [111] orientations. The work focused on the interaction between dislocations and
precipitates during cyclic plastic deformation at elevated temperature, which has not been well studied yet. A representative volume element (RVE) with cubic Îłâ-precipitates was chosen to represent the material, with enforced periodical boundary conditions. In particular, cutting of superdislocations into precipitates was simulated by a back-force method. The global cyclic stress-strain responses were captured well by the DDD model when compared to experimental
data, particularly the effects of crystallographic orientation. Dislocation evolution showed that considerably high density of dislocations was produced for [111] orientation when compared to [001] orientation. Cutting of dislocations into the precipitates had a significant effect on the plastic deformation, leading to material softening. Contour plots of in-plane shear strain proved the development of heterogeneous strain field, resulting in the formation of shear-band embryos
Reduction of the Three Dimensional Schrodinger Equation for Multilayered Films
In this paper, we present a method for reducing the three dimensional
Schrodinger equation to study confined metallic states, such as quantum well
states, in a multilayer film geometry. While discussing some approximations
that are employed when dealing with the three dimensionality of the problem, we
derive a one dimensional equation suitable for studying such states using an
envelope function approach. Some applications to the Cu/Co multilayer system
with regard to spin tunneling/rotations and angle resolved photoemission are
discussed.Comment: 14 pages, 1 figur
Association of Plasma Lipids and Polar Metabolites with Low Bone Mineral Density in Singaporean-Chinese Menopausal Women: A Pilot Study.
The diagnosis of osteoporosis is mainly based on clinical examination and bone mineral density assessments. The present pilot study compares the plasma lipid and polar metabolite profiles in blood plasma of 95 Singaporean-Chinese (SC) menopausal women with normal and low bone mineral density (BMD) using an untargeted metabolomic approach. The primary finding of this study was the association between lipids and femoral neck BMD in SC menopausal women. Twelve lipids were identified to be associated with low BMD by the orthogonal partial least squares (OPLS) model. Plasma concentrations of eight glycerophospholipid, glycerolipid, and sphingolipid species were significantly lower in menopausal women with low BMD but higher in two glycerophospholipid species (phosphatidylinositol and phosphatidic acid). Further, this study found no significant differences in plasma amino acid metabolites. However, trends for lower 4-aminobutyric acid, turanose, proline, aminopropionitrile, threonine, and methionine were found in women with low BMD. This pilot study identified associations between lipid metabolism and femoral neck BMD in SC women. Further studies are required on larger populations for evaluating the bone health effect of these compounds and their usefulness as clinical biomarkers for osteoporosis prediction in women
Association of Insulin Resistance with Bone Strength and Bone Turnover in Menopausal Chinese-Singaporean Women without Diabetes.
Insulin resistance (IR) is accompanied by increased areal or volumetric bone mineral density (aBMD or vBMD), but also higher fracture risk. Meanwhile, imbalances in bone health biomarkers affect insulin production. This study investigates the effect of IR on proximal femur and lumbar spine BMD, femoral neck bending, compressive and impact strength indices (Composite Strength Indices) and circulating levels of parathyroid hormone (PTH), C-telopeptide of Type I collagen (CTx-1) and 25(OH) Vitamin Dâ, in a cohort of 97 healthy, non-obese, menopausal Chinese-Singaporean women. Lumbar spine aBMD was inversely associated with IR and dependent on lean body mass (LBM) and age. No such associations were found for vBMD of the third lumbar vertebra, aBMD and vBMD of the proximal femur, or circulating levels of PTH, CTx-1 and 25(OH) Vitamin Dâ. Composite Strength Indices were inversely associated with IR and independent of LBM, but after adjusting for fat mass and age, this association remained valid only for the impact strength index. Composite Strength Indices were significantly lower in participants with a high degree of IR. Our findings on IR and Composite Strength Indices relationships were in agreement with previous studies on different cohorts, but those on IR and BMD associations were not
Protein intake at twice the RDA in older men increases circulatory concentrations of the microbiome metabolite trimethylamine-N-oxide (TMAO)
Higher dietary protein intake is increasingly recommended for the elderly; however, high protein diets have also been linked to increased cardiovascular disease (CVD) risk. TrimethylamineN-oxide (TMAO) is a bacterial metabolite derived from choline and carnitine abundant from animal protein-rich foods. TMAO may be a novel biomarker for heightened CVD risk. The purpose of this study was to assess the impact of a high protein diet on TMAO. Healthy men (74.2 ± 3.6 years, n = 29) were randomised to consume the recommended dietary allowance of protein (RDA: 0.8 g protein/kg bodyweight/day) or twice the RDA (2RDA) as part of a supplied diet for 10 weeks. Fasting blood samples were collected pre-and post-intervention for measurement of TMAO, blood lipids, glucose tolerance, insulin sensitivity, and inflammatory biomarkers. An oral glucose tolerance test was also performed. In comparison with RDA, the 2RDA diet increased circulatory TMAO (p = 0.002) but unexpectedly decreased renal excretion of TMAO (p = 0.003). LDL cholesterol was increased in 2RDA compared to RDA (p = 0.049), but no differences in other biomarkers of CVD risk and insulin sensitivity were evident between groups. In conclusion, circulatory TMAO is responsive to changes in dietary protein intake in older healthy males
Dark Energy and Gravity
I review the problem of dark energy focusing on the cosmological constant as
the candidate and discuss its implications for the nature of gravity. Part 1
briefly overviews the currently popular `concordance cosmology' and summarises
the evidence for dark energy. It also provides the observational and
theoretical arguments in favour of the cosmological constant as the candidate
and emphasises why no other approach really solves the conceptual problems
usually attributed to the cosmological constant. Part 2 describes some of the
approaches to understand the nature of the cosmological constant and attempts
to extract the key ingredients which must be present in any viable solution. I
argue that (i)the cosmological constant problem cannot be satisfactorily solved
until gravitational action is made invariant under the shift of the matter
lagrangian by a constant and (ii) this cannot happen if the metric is the
dynamical variable. Hence the cosmological constant problem essentially has to
do with our (mis)understanding of the nature of gravity. Part 3 discusses an
alternative perspective on gravity in which the action is explicitly invariant
under the above transformation. Extremizing this action leads to an equation
determining the background geometry which gives Einstein's theory at the lowest
order with Lanczos-Lovelock type corrections. (Condensed abstract).Comment: Invited Review for a special Gen.Rel.Grav. issue on Dark Energy,
edited by G.F.R.Ellis, R.Maartens and H.Nicolai; revtex; 22 pages; 2 figure
Measurement of the cross section for isolated-photon plus jet production in pp collisions at âs=13 TeV using the ATLAS detector
The dynamics of isolated-photon production in association with a jet in protonâproton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fbâ1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photonâjet invariant mass and the scattering angle in the photonâjet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements
- âŠ