1,606 research outputs found
Wigner Measure Propagation and Conical Singularity for General Initial Data
We study the evolution of Wigner measures of a family of solutions of a
Schr\"odinger equation with a scalar potential displaying a conical
singularity. Under a genericity assumption, classical trajectories exist and
are unique, thus the question of the propagation of Wigner measures along these
trajectories becomes relevant. We prove the propagation for general initial
data.Comment: 24 pages, 1 figur
Replacement names for the therapsid genera Criocephalus Broom 1928 and Olivieria Brink 1965.
Main articleOur knowledge of premammalian synapsid
evolutionary history has benefited from over a hundred
years of fossil collecting, especially within the Permo-Triassic
sediments of South Africa's Beaufort Group
(Rubidge 1995) and the Cis-Ural region of Eastern
Europe (Ivachnenko et al. 1997). In the course of our
research and discussions we have discovered several
errors in the present state of non-mammalian synapsid
taxonomy. Here we propose emendations concerning
the genera Criocephalus Broom 1928 and Olivieria
Brink 1965.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service
The Relationship between Cost Analysis and Program Management
Cost analysis if often viewed as applying basic principles and cost methodologies to determine total system cost. These finished estimates then flow into a decision making process and the cost estimator leaves the stage. Reality shows that the cost estimator is actually one of the main contributors to the decision making process. Our introduction to this special issue explores the areas where cost estimating plays a major role in program management in areas beyond the normal program estimate. We have included articles that show the key role estimators can play in source selection strategies and evaluation; cost of delay analysis for management decisions, earned value management methods to predict program costs; decision criteria to rank competing projects that complement traditional cost-based methods; and a new methodology for determining research and development budget profiles
A Nonlinear Adiabatic Theorem for Coherent States
We consider the propagation of wave packets for a one-dimensional nonlinear
Schrodinger equation with a matrix-valued potential, in the semi-classical
limit. For an initial coherent state polarized along some eigenvector, we prove
that the nonlinear evolution preserves the separation of modes, in a scaling
such that nonlinear effects are critical (the envelope equation is nonlinear).
The proof relies on a fine geometric analysis of the role of spectral
projectors, which is compatible with the treatment of nonlinearities. We also
prove a nonlinear superposition principle for these adiabatic wave packets.Comment: 21 pages, no figur
Cluster-resolved dynamic scaling theory and universal corrections for transport on percolating systems
For percolating systems, we propose a universal exponent relation connecting
the leading corrections to scaling of the cluster size distribution with the
dynamic corrections to the asymptotic transport behaviour at criticality. Our
derivation is based on a cluster-resolved scaling theory unifying the scaling
of both the cluster size distribution and the dynamics of a random walker. We
corroborate our theoretical approach by extensive simulations for a site
percolating square lattice and numerically determine both the static and
dynamic correction exponents.Comment: 6 pages, 5 figures, 1 tabl
Nutritional supplements for muscle building and fat loss
Adquirir una buena forma física es el objetivo de la mayoría de las personas que asisten a un centro de acondicionamiento físico; sin embargo, este proceso requiere de una individualización en la programación del entrenamiento y en la estrategia de alimentación, razón por la cual muchas personas no alcanzan sus metas y resultan adoptando prácticas innecesarias y peligrosas de suplementación. De acuerdo a la evidencia científica actual cuando el objetivo es incrementar la masa muscular, y solo de recomendarse por un profesional, se podría hacer uso de la suplementación con proteína de suero de leche o Whey Protein (0.4 - 0.5 g / kg / post-ejercicio), caseína (≈30 g antes de dormir) y monohidrato de creatina (0.3 g / kg / día durante 5-7 días seguido de 0.075 g / kg / post-entrenamiento durante 4-6 semanas). Se requiere más investigación respecto al consumo de Ashwagandha - Withania somnifera (300 mg dos veces al día) durante el mesociclo de entrenamiento de la fuerza. Por otro lado, durante una estrategia de reducción de grasa corporal para sujetos con sobrepeso u obesidad, los profesionales de la salud que realizan el seguimiento del caso pueden valorar el consumo de un reemplazo de comida en polvo (Meal Replacement Powder), como una alternativa para incrementar el aporte diario de proteína si se requiere, además de contemplar el consumo de Isomaltulosa (Palatinosa®) o amilopectinas modificadas en algunas comidas o 1-2 horas antes del ejercicio, sobre todo para controlar la hiperinsulinemia postprandial. La ingesta de un suplemento de cafeína anhidra (2-4 mg·kg-1·día-1) y algunos compuestos termogénicos; tales como, capsaicina (capsicum), té verde (Camelia sinensis), pimienta negra (Piper nigrum) y jengibre (Ginger officinale) pueden ser una alternativa para mejorar la adherencia a la dieta y aprovechar su potencial para reducir el porcentaje de grasa corporal, aunque se necesita más investigación a largo plazo para respaldar un efecto con significancia clínica
Photo- and halochromism of spiropyran-based main-chain polymers
Advanced functional polymeric materials based on spiropyrans (SPs) feature multi-stimuli responsive characteristics, such as a change in color with exposure to light (photochromism) or acids (halochromism). The inclusion of stimuli-responsive molecules in general – and SPs in particular – as main-chain repeating units is a scarcely explored macromolecular architecture compared to side chain responsive polymers. Herein, we establish the effects of substitution patterns on SPs within a homopolymer main-chain synthesized via head-to-tail Acyclic Diene METathesis (ADMET) polymerization. We unambiguously demonstrate that varying the location of the ester group (–OCOR) on the chromophore, which is essential to incorporate the SPs in the polymer backbone, determines the photo- and halochromism of the resulting polymers. While one polymer shows effective photochromism and resistance towards acids, the opposite – weak photochromism and effective response to acid – is observed for an isomeric polymer, simply by changing the position of the ester-linker relative to the benzopyran oxygen on the chromene unit. Our strategy represents a simple approach to manipulate the stimuli-response of main-chain SP bearing polymers and highlights the critical importance of isomeric molecular constitution on main-chain stimuli-sensitive polymers as emerging materials
Use of Cyclic Simple Shear Testing in Evaluation of the Deformation Potential of Liquefiable Soils
In recent years, a significant research effort has been focused on assessing the performance of structures founded on potentially liquefiable materials. While significant progress has been made on predictive tools for cases in which large deformations are likely, the ability to accurately and reliably predict small to moderate lateral deformations (\u3c1m) has proven more elusive. As a result, there is a universal need for high quality, element-level laboratory test data to calibrate and validate constitutive laws and numerical models for predicting the deformation of soil with limited liquefaction potential. To address this increasingly urgent need, a comprehensive cyclic simple shear testing program on liquefiable sands has been undertaken using the UC Berkeley Bi-directional Simple Shear Device. Many of the tests performed have new and innovative aspects that can provide information and insight into the behavior of soils showing limited deformation potential. Descried in this paper are results from a Kα test series, which replicates sloping ground conditions, and a newly developed and innovative “fabric” test series, which examines the influence of previous loading history on soil fabric and behavior
Unconventional motional narrowing in the optical spectrum of a semiconductor quantum dot
Motional narrowing refers to the striking phenomenon where the resonance line
of a system coupled to a reservoir becomes narrower when increasing the
reservoir fluctuation. A textbook example is found in nuclear magnetic
resonance, where the fluctuating local magnetic fields created by randomly
oriented nuclear spins are averaged when the motion of the nuclei is thermally
activated. The existence of a motional narrowing effect in the optical response
of semiconductor quantum dots remains so far unexplored. This effect may be
important in this instance since the decoherence dynamics is a central issue
for the implementation of quantum information processing based on quantum dots.
Here we report on the experimental evidence of motional narrowing in the
optical spectrum of a semiconductor quantum dot broadened by the spectral
diffusion phenomenon. Surprisingly, motional narrowing is achieved when
decreasing incident power or temperature, in contrast with the standard
phenomenology observed for nuclear magnetic resonance
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