2,502 research outputs found
Low uptake of antiretroviral therapy after admission with human immunodeficiency virus and tuberculosis in KwaZulu-Natal, South Africa.
A prospective cohort study was conducted among human immunodeficiency virus (HIV) infected in-patients with tuberculosis (TB) or other opportunistic infections (OIs) in South Africa to estimate subsequent antiretroviral therapy (ART) uptake and survival
Psychological flourishing and Self-esteem as predictors of adjustment to university life among a sample of Qatar university students
يهدف البحث إلى الكشف عن العلاقة بين الازدهار النفسي وتقدير الذات والتوافق مع الحياة الجامعية لدى عينة من الطلاب في جامعة قطر، كما يهدف إلى تعرف الفروق بين عينة الدراسة في ضوء النوع والفرقة الدراسية والحالة الاجتماعية والتفاعل بينهم في تلك المتغيرات، وإمكانية التنبؤ بالتوافق مع الحياة الجامعية من خلال الازدهار النفسي وتقدير الذات. تكونت عينة الدراسة من 329 طالبًا وطالبة من طلاب جامعة قطر، طبق عليهم الباحثان مقياس الازدهار النفسي (Diener et al., 2009) ومقياس تقدير الذات (Rosenberg, 1965) ومقياس التوافق مع الحياة الجامعية (Baker & Siryk, 1989). وتشير نتائج الدراسة إلى وجود علاقة ارتباطية دالة إحصائيا بين الازدهار النفسي وتقدير الذات والتوافق مع الحياة الجامعية لدى عينة الدراسة. كما أشارت النتائج إلى وجود فروق ذات دلالة إحصائية تعزى للنوع على بعد التوافق الشخصي الانفعالي والازدهار لصالح الذكور، كما ظهرت فروق تعزى للحالة الاجتماعية على التوافق الأكاديمي، والتعلق، والدرجة الكلية، وتقدير الذات والازدهار النفسي لصالح المتزوجين. وأخيرا، أظهرت النتائج أنه يمكن التنبؤ بالتوافق مع الحياة الجامعية وأبعاده الفرعية من خلال الازدهار النفسي وتقدير الذات
A note on the integrable discretization of the nonlinear Schr\"odinger equation
We revisit integrable discretizations for the nonlinear Schr\"odinger
equation due to Ablowitz and Ladik. We demonstrate how their main drawback, the
non-locality, can be overcome. Namely, we factorize the non-local difference
scheme into the product of local ones. This must improve the performance of the
scheme in the numerical computations dramatically. Using the equivalence of the
Ablowitz--Ladik and the relativistic Toda hierarchies, we find the
interpolating Hamiltonians for the local schemes and show how to solve them in
terms of matrix factorizations.Comment: 24 pages, LaTeX, revised and extended versio
Interaction of Nonlinear Schr\"odinger Solitons with an External Potential
Employing a particularly suitable higher order symplectic integration
algorithm, we integrate the 1- nonlinear Schr\"odinger equation numerically
for solitons moving in external potentials. In particular, we study the
scattering off an interface separating two regions of constant potential. We
find that the soliton can break up into two solitons, eventually accompanied by
radiation of non-solitary waves. Reflection coefficients and inelasticities are
computed as functions of the height of the potential step and of its steepness.Comment: 14 pages, uuencoded PS-file including 10 figure
Reconnection and acoustic emission of quantized vortices in superfluid by the numerical analysis of the Gross-Pitaevskii equation
We study numerically the reconnection of quantized vortices and the
concurrent acoustic emission by the analysis of the Gross-Pitaevskii equation.
Two quantized vortices reconnect following the process similar to classical
vortices; they approach, twist themselves locally so that they become
anti-parallel at the closest place, reconnect and leave separately.The
investigation of the motion of the singular lines where the amplitude of the
wave function vanishes in the vortex cores confirms that they follow the above
scenario by reconnecting at a point. This reconnection is not contradictory to
the Kelvin's circulation theorem, because the potential of the superflow field
becomes undefined at the reconnection point. When the locally anti-parallel
part of the vortices becomes closer than the healing length, it moves with the
velocity comparable to the sound velocity, emits the sound waves and leads to
the pair annihilation or reconnection; this phenomena is concerned with the
Cherenkov resonance. The vortices are broken up to smaller vortex loops through
a series of reconnection, eventually disappearing with the acoustic emission.
This may correspond to the final stage of the vortex cascade process proposed
by Feynman. The change in energy components, such as the quantum, the
compressible and incompressible kinetic energy is analyzed for each dynamics.
The propagation of the sound waves not only appears in the profile of the
amplitude of the wave function but also affects the field of its phase,
transforming the quantum energy due to the vortex cores to the kinetic energy
of the phase field.Comment: 11 pages, 16 figures, LaTe
Parallel Methods and Higher Dimensional NLS Equations
Alternating direction implicit (ADI) schemes are proposed for the solution of the two-dimensional coupled nonlinear Schrödinger
equation. These schemes are of second- and fourth-order accuracy in space
and second order in time. The resulting schemes in each ADI computation step correspond to a block tridiagonal system which can be solved
by using one-dimensional block tridiagonal algorithm with a considerable
saving in computational time. These schemes are very well suited for parallel implementation on a high performance system with many processors
due to the nature of the computation that involves solving the same block
tridiagonal systems with many right hand sides. Numerical experiments
on one processor system are conducted to demonstrate the efficiency and
accuracy of these schemes by comparing them with the analytic solutions.
The results show that the proposed schemes give highly accurate results
Methods of the epidemics spread mathematical modeling
This paper presents a review of SIR mathematical models used for Epidemics modelling over the past years. Mathematical modelling of epidemic spread makes an important contribution to disease contro
Early Prediction of Movie Box Office Success based on Wikipedia Activity Big Data
Use of socially generated "big data" to access information about collective
states of the minds in human societies has become a new paradigm in the
emerging field of computational social science. A natural application of this
would be the prediction of the society's reaction to a new product in the sense
of popularity and adoption rate. However, bridging the gap between "real time
monitoring" and "early predicting" remains a big challenge. Here we report on
an endeavor to build a minimalistic predictive model for the financial success
of movies based on collective activity data of online users. We show that the
popularity of a movie can be predicted much before its release by measuring and
analyzing the activity level of editors and viewers of the corresponding entry
to the movie in Wikipedia, the well-known online encyclopedia.Comment: 13 pages, Including Supporting Information, 7 Figures, Download the
dataset from: http://wwm.phy.bme.hu/SupplementaryDataS1.zi
A PROPOSED DUAL SIZE DESIGN FOR ENERGY MINIMIZATION IN SUB-THRESHOLD CIRCUITS
Sub-threshold operation has received a lot of attention in limited performance applications.However, energy optimization of sub-threshold circuits should be performed with the concern of the performance limitation of such circuit. In this paper, a dual size design is proposed for energy minimization of sub-threshold CMOS circuits. The optimal downsizing factor is determined and assigned for some gates on the off-critical paths to minimize the energy at the maximum allowable performance. This assignment is performed using the proposed slack based genetic algorithm which is a heuristic-mixed evolutionary algorithm. Some gates are heuristically assigned to the original and the downsized design based on their slack time determined by static timing analysis. Other gates are subjected to the genetic algorithm to perform an optimal downsizing assignment taking into account the previous assignments. The algorithm is applied for different downsizing factors to determine the optimal dual size for low energy operation without a performance degradation. Experimental results are obtained for some ISCAS-85 benchmark circuits such as 74283, 74L85, ALU74181, and 16 bit ripple carry adder. The proposed design shows an energy per cycle saving ranged from (29.6% to 56.59%) depending on the utilization of available slack time from the off-critical paths
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