1,698 research outputs found
Pulsed laser deposition growth of Fe3O4 on III–V semiconductors for spin injection
We report on the growth of thin layers of Fe3O4 on GaAs and InAs by pulsed laser deposition. It is found that Fe3O4 grows epitaxially on InAs at a temperature of 350 °C. X-ray photoelecton spectroscopy (XPS) studies of the interface show little if any interface reaction resulting in a clean epitaxial interface. In contrast, Fe3O4 grows in columnar fashion on GaAs, oriented with respect to the growth direction but with random orientation in the plane of the substrate. In this case XPS analysis showed much more evidence of interface reactions, which may contribute to the random-in-plane growth
Autonomous agile teams: Challenges and future directions for research
According to the principles articulated in the agile manifesto, motivated and
empowered software developers relying on technical excellence and simple
designs, create business value by delivering working software to users at
regular short intervals. These principles have spawned many practices. At the
core of these practices is the idea of autonomous, self-managing, or
self-organizing teams whose members work at a pace that sustains their
creativity and productivity. This article summarizes the main challenges faced
when implementing autonomous teams and the topics and research questions that
future research should address
State transition of a non-Ohmic damping system in a corrugated plane
Anomalous transport of a particle subjected to non-Ohmic damping of the power
in a tilted periodic potential is investigated via Monte Carlo
simulation of generalized Langevin equation. It is found that the system
exhibits two relative motion modes: the locking state and the running state.
Under the surrounding of sub-Ohmic damping (), the particle should
transfer into a running state from a locking state only when local minima of
the potential vanish; hence the particle occurs a synchronization oscillation
in its mean displacement and mean square displacement (MSD). In particular, the
two motion modes are allowed to coexist in the case of super-Ohmic damping
() for moderate driving forces, namely, where exists double centers
in the velocity distribution. This induces the particle having faster
diffusion, i.e., its MSD reads . Our result shows that the effective power index
can be enhanced and is a nonmonotonic function of the
temperature and the driving force. The mixture effect of the two motion modes
also leads to a breakdown of hysteresis loop of the mobility.Comment: 7 pages,7 figure
Anomalous Rotational Relaxation: A Fractional Fokker-Planck Equation Approach
In this study we obtained analytically relaxation function in terms of
rotational correlation functions based on Brownian motion for complex
disordered systems in a stochastic framework. We found out that rotational
relaxation function has a fractional form for complex disordered systems, which
indicates relaxation has non-exponential character obeys to
Kohlrausch-William-Watts law, following the Mittag-Leffler decay.Comment: Revtex4, 9 pages. Paper was revised. References adde
Fractional Generalization of Gradient Systems
We consider a fractional generalization of gradient systems. We use
differential forms and exterior derivatives of fractional orders. Examples of
fractional gradient systems are considered. We describe the stationary states
of these systems.Comment: 11 pages, LaTe
Spectral Asymptotics of Eigen-value Problems with Non-linear Dependence on the Spectral Parameter
We study asymptotic distribution of eigen-values of a quadratic
operator polynomial of the following form ,
where is a second order differential positive elliptic operator
with quadratic dependence on the spectral parameter . We derive
asymptotics of the spectral density in this problem and show how to compute
coefficients of its asymptotic expansion from coefficients of the asymptotic
expansion of the trace of the heat kernel of . The leading term in
the spectral asymptotics is the same as for a Laplacian in a cavity. The
results have a number of physical applications. We illustrate them by examples
of field equations in external stationary gravitational and gauge backgrounds.Comment: latex, 20 page
Factorial Moments of Continuous Order
The normalized factorial moments are continued to noninteger values of
the order , satisfying the condition that the statistical fluctuations
remain filtered out. That is, for Poisson distribution for all .
The continuation procedure is designed with phenomenology and data analysis in
mind. Examples are given to show how can be obtained for positive and
negative values of . With being continuous, multifractal analysis is
made possible for multiplicity distributions that arise from self-similar
dynamics. A step-by-step procedure of the method is summarized in the
conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late
Fractional dynamics of coupled oscillators with long-range interaction
We consider one-dimensional chain of coupled linear and nonlinear oscillators
with long-range power-wise interaction. The corresponding term in dynamical
equations is proportional to . It is shown that the
equation of motion in the infrared limit can be transformed into the medium
equation with the Riesz fractional derivative of order , when
. We consider few models of coupled oscillators and show how their
synchronization can appear as a result of bifurcation, and how the
corresponding solutions depend on . The presence of fractional
derivative leads also to the occurrence of localized structures. Particular
solutions for fractional time-dependent complex Ginzburg-Landau (or nonlinear
Schrodinger) equation are derived. These solutions are interpreted as
synchronized states and localized structures of the oscillatory medium.Comment: 34 pages, 18 figure
Attitudes and diagnostic practice in low back pain: A qualitative study amongst Greek and British physiotherapists
AIM To explore current diagnostic practice and attitudes of Greek and United Kingdom physiotherapists (PTs) on assessing low back pain (LBP) patients. METHODS Three focus groups were undertaken, followed by a structured questionnaire-type survey comprising 23 health professionals and a random stratified sample of 150 PTs, respectively. Twenty-nine themes relating to LBP diagnostic practice emerged. These were then given to 30 British PTs assessing their level of agreement with their Greek counterparts. Analysis was performed by percentage agreements and χ2 tests. RESULTS The survey was divided into three subsections; PTs' attitudes on LBP assessment, patients' attitudes and diagnostic/healthcare issues, each constituting 14, 7 and 8 statements, respectively. Over half of the statements fell within the 30%-80% agreement between Greece and United Kingdom whereas, 5 statements reported low ( 90%) PT percentage agreement. Similarities across British and Greek PTs were detected in history taking methods and in the way PTs feel patients perceive physiotherapy practice whereas, re-assessment was undertaken less frequently in Greece. Diagnosis according to 91% of the Greek PTs is considered a "privilege" which is exclusive for doctors in Greece (only 17% British PTs agreed) and is accompanied with a great overuse of medical investigations. Forty percent of Greek PTs (compared to 0% of British) consider themselves as "executers", being unable to interfere with treatment plan, possibly implying lack of autonomy. CONCLUSION Although similarities on history taking methods and on patients' attitudes were detected across both groups, gross differences were found in re-assessment procedures and diagnostic issues between Greek and British physiotherapists, highlighting differences in service delivery and professional autonomy
- …