Real space first-principles derived semiempirical pseudopotentials applied to tunneling magnetoresistance

In this letter we present a real space density functional theory (DFT) localized basis set semi-empirical pseudopotential (SEP) approach. The method is applied to iron and magnesium oxide, where bulk SEP and local spin density approximation (LSDA) band structure calculations are shown to agree within approximately 0.1 eV. Subsequently we investigate the qualitative transferability of bulk derived SEPs to Fe/MgO/Fe tunnel junctions. We find that the SEP method is particularly well suited to address the tight binding transferability problem because the transferability error at the interface can be characterized not only in orbital space (via the interface local density of states) but also in real space (via the system potential). To achieve a quantitative parameterization, we introduce the notion of ghost semi-empirical pseudopotentials extracted from the first-principles calculated Fe/MgO bonding interface. Such interface corrections are shown to be particularly necessary for barrier widths in the range of 1 nm, where interface states on opposite sides of the barrier couple effectively and play a important role in the transmission characteristics. In general the results underscore the need for separate tight binding interface and bulk parameter sets when modeling conduction through thin heterojunctions on the nanoscale.Comment: Submitted to Journal of Applied Physic

Vortex Mass in BCS systems: Kopnin and Baym-Chandler contributions

The Kopnin mass and the Baym-Chandler mass of the vortex have the same origin. Both represent the mass of the normal component trapped by the vortex. The Kopnin mass of the vortex is formed by quasiparticles localized in the vicinity of the vortex. In the superclean limit it is calculated as linear response exactly in the same way as the density of the normal component is calculated in homogeneous superfluid. The Baym-Chandler mass is the hydrodynamical (associated) mass trapped by vortex. It is analogous to the normal component formed by inhomogeneities, such as pores and impurities. Both contributions are calculated for the generic model of the continuous vortex core.Comment: revtex file, 3 pages, 1 figure. Initially appeared as Comment to the paper by E.B. Sonin et al "Vortex motion in charged and neutral superfluids: A hydrodynamic approach" (Phys. Rev. B 57, 575 (1998)). The calculation of the backflow mass is adde

Modifications of Gait as Predictors of Natural Osteoarthritis Progression in STR/Ort Mice

Objective. Osteoarthritis (OA) is a common chronic disease for which disease-modifying therapies are not currently available. Studies to seek new targets for slowing the progress of OA rely on mouse models, but these do not allow for longitudinal monitoring of disease development. This study was undertaken to determine whether gait can be used to measure disease severity in the STR/Ort mouse model of spontaneous OA and whether gait changes are related to OA joint pain.Methods. Gait was monitored using a treadmill-based video system. Correlations between OA severity and gait at 3 treadmill speeds were assessed in STR/Ort mice. Gait and pain behaviors of STR/Ort mice and control CBA mice were analyzed longitudinally, with monthly assessments.Results. The best speed to identify paw area changes associated with OA severity in STR/Ort mice was found to be 17 cm . seconds(-1). Paw area was modified with age in CBA and STR/Ort mice, but this began earlier in STR/Ort mice and correlated with the onset of OA at 20 weeks of age. In addition, task noncompliance appeared at 20 weeks. Surprisingly, STR/Ort mice did not show any signs of pain with OA development, even when treated with the opioid antagonist naloxone, but did exhibit normal pain behaviors in response to complete Freund's adjuvant-induced arthritis.Conclusion. The present results identify an animal model in which OA severity and OA pain can be studied in isolation from one another. The findings suggest that paw area and treadmill noncompliance may be useful tools to longitudinally monitor nonpainful OA development in STR/Ort mice. This will help in providing a noninvasive means of assessing new therapies to slow the progression of OA.</p

Comment on "Transverse Force on a Quantized Vortex in a Superfluid"

The result of Thouless, Ao and Niu (TAN), that the mutual friction parameter $d_\perp =0$, contradicts to the experiments made in rotating 3He-B by Manchester group. The Manchester group observed that $d_\perp <0$ at low temperature and approaches 1 at high temperature. The reason of the contradiction is that TAN did not take into account the Iordanskii force on the vortex and the spectral flow force, which comes from the anomaly related to the low-energy bound states of fermions in cores of quantized vortices. The Iordanskii force is responsible for the negative $d_\perp <0$ at low temperature, while due to the spectral flow $d_\perp$ approaches 1 at high temperature. Relation of the spectral flow anomaly with the paradoxes of the linear and angular momenta in gapless superfluids is discussed.Comment: revtex, 2 pages, submitted to Physical Review Letters as "Comment" to the paper D.J. Thouless, P. Ao and Q. Niu, Phys. Rev. Lett. 76, 3758 (1996

Out-of-school lives of physically disabled children and young people in the United Kingdom: A qualitative literature review

Currently there appears to be few opportunities and little evidence of physically disabled children and young people (C&YP) participating in mainstream social activities. A qualitative review was undertaken to examine the factors affecting physically disabled C&YP (8–15 years) in the United Kingdom participating in out-of-school activities. Views and experiences were explored from the perspective of the service users and providers to assess current provision and to determine the need for future research into factors that may affect participation. Searches were conducted across eight databases, the references of the included studies were checked and the websites were searched. Studies that used a qualitative design that examined the views relating to out-of-school activities were included. Nine papers were identified, which included three peer-reviewed papers and six pieces of grey literature and pertinent government documents to include views and experiences of out-of-school activity provision. The main themes emerging from the review were the need for social inclusion, out-of-school activities run by volunteers and accessibility, with threads throughout, which require further research including parental influence, provision, training and attitudes. This review highlights the absence of the service user’s voice and sheds light on the limited provision and barriers affecting participation in out-of-school activities

Classical and quantum regimes of the superfluid turbulence

We argue that turbulence in superfluids is governed by two dimensionless parameters. One of them is the intrinsic parameter q which characterizes the friction forces acting on a vortex moving with respect to the heat bath, with 1/q playing the same role as the Reynolds number Re=UR/\nu in classical hydrodynamics. It marks the transition between the "laminar" and turbulent regimes of vortex dynamics. The developed turbulence described by Kolmogorov cascade occurs when Re >> 1 in classical hydrodynamics, and q << 1 in the superfluid hydrodynamics. Another parameter of the superfluid turbulence is the superfluid Reynolds number Re_s=UR/\kappa, which contains the circulation quantum \kappa characterizing quantized vorticity in superfluids. This parameter may regulate the crossover or transition between two classes of superfluid turbulence: (i) the classical regime of Kolmogorov cascade where vortices are locally polarized and the quantization of vorticity is not important; and (ii) the quantum Vinen turbulence whose properties are determined by the quantization of vorticity. The phase diagram of the dynamical vortex states is suggested.Comment: 12 pages, 1 figure, version accepted in JETP Letter

Vortex vs spinning string: Iordanskii force and gravitational Aharonov-Bohm effect

We discuss the transverse force acting on the spinning cosmic string, moving in the background matter. It comes from the gravitational Aharonov-Bohm effect and corresponds to the Iordanskii force acting on the vortex in superfluids, when the vortex moves with respect to the normal component of the liquid.Comment: Latex file, 9 pages, no figures, references are added, version submitted to JETP Let

Evaluation of the regional nurse-supported hepatitis C shared care program in Western Australia: a mixed methods study

Background: Nurse-supported shared care services for patients living with hepatitis C have been implemented in some regional areas of Western Australia to provide access to local treatment and care services for patients and to improve currently low levels of treatment uptake. This study collected data from health professionals involved in managing the care of patients living with hepatitis C and from patients engaged in regional nurse-supported hepatitis C shared care services in Western Australia. Methods: Key informant qualitative interviews were conducted with health professionals in regions operating a nurse-supported shared care service and in regions without this service. Patients engaged in the shared care program at the time of the study were invited to complete a short questionnaire. Results: Nurse-supported shared care services reduced patient transport costs to tertiary centres, accelerated access to treatment and delivered \u3e98 % compliance with treatment schedules. Patients engaged with regional hepatitis C shared care services expressed high levels of satisfaction and indicated that they would delay treatment if it was not available locally. Telehealth support from tertiary liver clinics and allied health services were available to health professionals engaged in regional shared care services and were used effectively. There was limited participation by general practitioners in regional hepatitis C shared care services and regional patients’ access to treatment was influenced by the availability and capacity of health professionals. Uptake of treatment and engagement in the regional shared care program was limited for Aboriginal people and younger people although these groups had the highest rates of hepatitis C notifications in Western Australia. Discussion: The patients consulted for this study preferred to access hepatitis C treatment and care locally rather than travel to tertiary liver clinics, up to 1500 kilometres away. The reasons for limited engagement in the shared care program by some groups with high rates of hepatitis C notifications requires further investigation. Health professionals identified several benefits of the shared care program including continuity of care for patients, shorter waiting times, longer appointment times and high levels of treatment compliance. Conclusions: Hepatitis nurses in regional areas can coordinate effective patient treatment and care when supported by treatment protocols and access to physicians and liver specialists, including through telehealth. Treatment and care options to suit individual preferences are required to avoid further stigmatising marginalized groups. The role of primary care in facilitating hepatitis C treatment uptake should be explored further including strategies for improving the participation of general practitioners in regional shared care services