Elliptical flux vortices in YBa2Cu3O7

The most energetically favorable vortex in YBa2Cu3O7 forms perpendicular to an anisotropic plane. This vortex is elliptical in shape and is distinguished by an effective interchange of London penetration depths from one axis of the ellipse to another. By generalizing qualitatively from the isotropic to the anisotropic case, we suggest that the flux flow resistivity for the vortex that forms perpendicular to an anistropic plane should have a preferred direction. Similar reasoning indicates that the Kosterlitz-Thouless transition temperature for a vortex mediated transition should be lower if the vortex is elliptical in shape

Arrival processes in port modeling: insights from a case study

This paper investigates the impact of arrival processes on the ship handling process. Two types of arrival processes are considered: controlled and uncontrolled. Simulation results show that uncontrolled arrivals of ships perform worst in terms of both ship delays and required storage capacity. Stock-controlled arrivals perform best with regard to large vessel delays and storage capacity. The combination of stock-controlled arrivals for large vessels and equidistant arrivals for barges also performs better than the uncontrolled process. Careful allocation of ships to the mooring points of a jetty further improves the efficiency.supply chain management;logistics;simulation;transportation;case study

Role of an intermediate state in homogeneous nucleation

We explore the role of an intermediate state (phase) in homogeneous nucleation phenomenon by examining the decay process through a doubly-humped potential barrier. As a generic model we use the fourth- and sixth-order Landau potentials and analyze the Fokker-Planck equation for the one-dimensional thermal diffusion in the system characterized by a triple-well potential. In the low temperature case we apply the WKB method to the decay process and obtain the decay rate which is accurate for a wide range of depth and curvature of the middle well. In the case of a deep middle well, it reduces to a doubly-humped-barrier counterpart of the Kramers escape rate: the barrier height and the curvature of an initial well in the Kramers rate are replaced by the arithmetic mean of higher(or outer) and lower(or inner) partial barriers and the geometric mean of curvatures of the initial and intermediate wells, respectively. It seems to be a universal formula. In the case of a shallow-enough middle well, Kramers escape rate is alternatively evaluated within the standard framework of the mean-first-passage time problem, which certainly supports the WKB result. The criteria whether or not the existence of an intermediate state can enhance the decay rate are revealed.Comment: 9pages, 11figure

Algebraic treatment of PT\mathcal{PT}-symmetric coupled oscillators

The purpose of this paper is the discussion of a pair of coupled linear oscillators that has recently been proposed as a model of a system of two optical resonators. By means of an algebraic approach we show that the frequencies of the classical and quantum-mechanical interpretations of the optical phenomenon are exactly the same. Consequently, if the classical frequencies are real, then the quantum-mechanical eigenvalues are also real

An ICF-based education programme in amputation rehabilitation for medical residents in the Netherlands

Background and Aim: Education programmes of the International Society for Prosthetics and Orthotics (ISPO) are directed primarily at prosthetists and orthotists. In a multidisciplinary setting, greater attention should be given to other professionals working in the field of amputation, prosthetics and orthotics. This includes, among others, physiotherapists, occupational therapists and residents and physicians from orthopaedics, vascular surgery and physical medicine and rehabilitation (PM&R). The aim of this paper is to describe the education programme in amputation and prosthetics for residents in PM&R in the Netherlands. The programme is based on concepts of the International Classification on Functioning, Disability and Health (ICF). Technique: This narrative paper presents the amputation and prosthetics education programme for residents in PM&R in the Netherlands. The programme is based on two models: the ICF and the Canadian Medical Education Directives for Specialists (CanMEDS). Discussion: ICF core sets for amputation and prosthetics need further development. Subsequently, the application of these core sets can help stimulate the education of residents in PM&R, and other multidisciplinary team members who work in amputation rehabilitatio

Pre-operative rehabilitation in lower-limb amputation patients and its effect on post-operative outcomes

Major lower-limb amputation (LLA) is a life-changing event associated with poor post-operative physical and psychological functioning and decreased quality of life. The general physical condition of most LLA patients prior to surgery is already significantly deteriorated due to chronic peripheral vascular disease often in combination with diabetes. Pre-operative rehabilitation (also called `pre-rehabilitation') is an increasingly common strategy used in multiple patient populations to improve patients' physical and mental condition prior to surgery, thus aiming at improving the post-operative patient outcomes. Given the positive effects of post-surgical outcomes in many patient populations, we hypothesize that pre-operative rehabilitation will improve post-operative outcomes after LLA. To test this hypothesis, a literature search of PubMed, EMBASE, EBSCOhost, Web of Science and ScienceDirect was performed to identify studies that investigated the impact of a pre-operative rehabilitation therapy on post-operative outcomes such as length of hospital stay, mobility, physical functioning, and health related quality of life. No time restrictions were applied to the search. Only articles published in English were included in the selection. Two studies satisfied the eligibility criteria for inclusion in the review, one qualitative and one quantitative study. The quantitative study reported a beneficial effect of pre-rehabilitation, resulting in post-operative mobility (at least indoor ambulation) in 63% of the included LLA patients. There is a need for prospective clinical studies examining the effect of pre-rehabilitation on post-operative outcomes to be able to confirm or reject our hypothesis. Although the hypothesis seems plausible, evidence is lacking to support our hypothesis that pre-operative rehabilitation will improve post-operative outcomes in patients with LLA. The qualitative study indicated that integrating pre-rehabilitation in the care for LLA patients seems to be limited to a selected group of dysvascular patients, but at this stage cannot be advised based on current evidence even in this subgroup. Further research is needed to clarify whether such an intervention prior to amputation would be a useful and effective tool for optimizing post-operative outcomes in LLA patients

Current--Voltage Characteristics of Two--Dimensional Vortex Glass Models

We have performed Monte Carlo simulations to determine current--voltage characteristics of two different vortex glass models in two dimensions. The results confirm the conclusions of earlier studies that there is a transition at $T=0$. In addition we find that, as $T\to 0$, the linear resistance vanishes exponentially, and the current scale, $J_{nl}$, where non-linearities appear in the $I$--$V$ characteristics varies roughly as $T^3$, quite different from the predictions of conventional flux creep theory, $J_{nl} \sim T$. The results for the two models agree quite well with each other, and also agree fairly well with recent experiments on very thin films of YBCO.Comment: 18 pages with 10 figures available upon request from R. A. Hyman at [email protected]. The only change in the new version is the deletion of an unimportant comment.IUCM94-01

Models for local ohmic quantum dissipation

We construct model master equations for local quantum dissipation. The master equations are in the form of Lindblad generators, with imposed constraints that the dissipations be strictly linear (i.e. ohmic), isotropic and translationally invariant. A particular form for is chosen to satisfy the constraints. The resulting master equations are given in both the Schr\"odinger and Heisenberg forms. We obtain fluctuation-dissipation relations, and discuss the relaxation of average kinetic energy to effective thermal equilibrium values. We compare our results to the Dekker and the Caldeira-Leggett master equations. These master equations allow a more general approach to quantum dissipation and the dynamics of quantum coherence to account for the nontrivial system-environment coupling in a local environment.Comment: 19 pages, REVTEX, PSU/TH/12