Theory of Spin-Transfer Torque in the Current-in-Plane Geometries

Two alternative current-induced switching geometries, in which the current flows parallel to the magnet/nonmagnet interface, are investigated theoretically using the nonequilibrium Keldysh theory. In the first geometry, the current is perpendicular to the polarizing magnet/nonmagnet interface but parallel to the nonmagnet/switching magnet interface (CPIP). In the second geometry, the current is parallel to both the polarizing magnet/nonmagnet and nonmagnet/switching magnet interfaces (CIP). Calculations for a single-orbital tight binding model indicate that the spin current flowing parallel to the switching magnet/nonmagnet interface can be absorbed by a lateral switching magnet as efficiently as in the traditional current-perpendicular-to-plane (CPP) geometry. The results of the model calculations are shown to be valid also for experimentally relevant Co/Cu CPIP system described by fully realistic tight binding bands fitted to an ab initio band structure. It is shown that almost complete absorption of the incident spin current by a lateral switching magnet occurs when the lateral dimensions of the switching magnet are of the order of 50-100 interatomic distances, i.e., about 20nm and its height as small as a few atomic planes. It is also demonstratedthat strong spin current absorption in the CPIP/CIP geometry is not spoilt by the presence of a rough interface between the switching magnet and nonmagnetic spacer. Polarization achieved using a lateral magnet in the CIP geometry is found to be about 25% of that in the traditional CPP geometry. The present CPIP calculations of the spin transfer torque are also relevant to the so called pure-spin-current-induced magnetization switching that had been recently observed.Comment: 9 pages 8 figure

Comparison of the effects of two anaesthetic combinations in rabbits on some neutrophil functions in vitro

[EN] Tissue injury during surgery as well as anaesthesia can lead to modulation of neutrophil function. The aim of this study was to assess how two types of anaesthesia, i.e. combination of ketamine/midazolam/propofol (Group I) and ketamine/propofol (Group II) influenced neutrophil function during and 24 h after operation in rabbits. Blood samples were taken prior to anaesthesia, at 30 and 60 min, and 24 h after starting the experiment. At these time points, degranulation and free radical generation were assessed in both groups. After 30 min of anaesthesia, we observed a decrease in elastase release from 50.96±0.71% to 26.52±4.85% in Group I and from 51.00±0.7% to 41.00±5.48% in Group II, respectively. In subsequent measurements, the elastase level increased to values lower than before starting anaesthesia. The myeloperoxidase (MPO) release decreased significantly after 30 min of anaesthesia in Group I, then increased to the value similar to the pre-anaesthetic level after 60 min. MPO level in Group II also decreased after 30 min but to a lesser degree, and then after 1 h MPO slightly exceeded the pre-anaesthetic level. In both groups, 24 h after the start anaesthesia the values obtained decreased, but remained at a level higher than at the time before anaesthesia. We observed a decrease in alkaline phosphatase (ALKP) levels in both studied groups after 30 min of anaesthesia (from 24.77±5.9% to 15.7±2.1% and from 23.6±1.14% to 10.6±0.89%, in Groups I and II, respectively), with a subsequent increase after 60 min. In Group I, we observed a significant (P<0.01) decrease in NO production 30 min after the start of anaesthesia. After increasing to the pre-anaesthetic level, the NO level was almost constant in both subsequent measurements. In Group II, NO level decreased 30 min after the onset of anaesthesia and then increased, reaching a slightly higher level than at the start of anaesthesia. The superoxide generation by neutrophils from rabbits of both groups decreased after 30 min of anaesthesia and then rose. Because the anaesthetic combinations used alter neutrophil function only transiently, both of them would be applied in surgery in rabbits without the risk of disturbance to the healing process.Wessely-Szponder, J.; Szponder, T. (2010). Comparison of the effects of two anaesthetic combinations in rabbits on some neutrophil functions in vitro. World Rabbit Science. 18(3). doi:10.4995/wrs.2010.841418

Current driven magnetization dynamics in helical spin density waves

A mechanism is proposed for manipulating the magnetic state of a helical spin density wave using a current. In this paper, we show that a current through a bulk system with a helical spin density wave induces a spin transfer torque, giving rise to a rotation of the order parameter.The use of spin transfer torque to manipulate the magnetization in bulk systems does not suffer from the obstacles seen for magnetization reversal using interface spin transfer torque in multilayered systems. We demonstrate the effect by a quantitative calculation of the current induced magnetization dynamics of Erbium. Finally we propose a setup for experimental verification.Comment: In the previous version of this paper was a small numerical mistake made when evaluating equation 3 and 9. The number of digits given in the calculation of the torque current tensor is reduced to better represent the accuracy of the calculation. A slightly modified paper have been published in Phys. Rev. Lett. 96, 256601 (2006) 4 pages 3 figure

‘What’s it like to have ME?’ The discursive construction of ME in computer-mediated communication and face-to-face interaction

ME/CFS (chronic fatigue syndrome) is a debilitating illness for which no cause or medical tests have been identified. Debates over its nature have generated interest from qualitative researchers. However, participants are difficult to recruit because of the nature of their condition. Therefore, this study explores the utility of the internet as a means of eliciting accounts. We analyse data from focus groups and the internet in order to ascertain the extent to which previous research findings apply to the internet domain. Interviews were conducted among 49 members of internet (38 chatline, 11 personal) and 7 members of two face-to-face support groups. Discourse analysis of descriptions and accounts of ME/CFS revealed similar devices and interactional concerns in both internet and face-to-face communication. Participants constructed their condition as serious, enigmatic and not psychological. These functioned to deflect problematic assumptions about ME/CFS and to manage their accountability for the illness and its effects

Evaluation of three different methods of distance learning for postgraduate diagnostic imaging education: A pilot study

Objective : The purpose of this study was to evaluate the perceived effectiveness and learning potential of 3 Web-based educational methods in a postgraduate radiology setting. Methods : Three chiropractic radiology faculty from diverse geographic locations led mini-courses using asynchronous discussion boards, synchronous Web conferencing, and asynchronous voice-over case presentations formatted for Web viewing. At the conclusion of each course, participants filled out a 14-question survey (using a 5-point Likert scale) designed to evaluate the effectiveness of each method in achieving specified course objectives and goals and their satisfaction when considering the learning potential of each method. The mean, standard deviation, and percentage agreements were tabulated. Results : Twenty, 15, and 10 participants completed the discussion board, Web conferencing, and case presentation surveys, respectively. All educational methods demonstrated a high level of agreement regarding the course objective (total mean rating >4.1). The case presentations had the highest overall rating for achieving the course goals; however, all but one method still had total mean ratings >4.0 and overall agreement levels of 70%-100%. The strongest potential for interactive learning was found with Web conferencing and discussion boards, while case presentations rated very low in this regard. Conclusions : The perceived effectiveness in achieving the course objective and goals was high for each method. Residency-based distance education may be a beneficial adjunct to current methods of training, allowing for international collaboration. When considering all aspects tested, there does not appear to be a clear advantage to any one method. Utilizing various methods may be most appropriate

Cost of post-deployment screening for mental illness in the UK military: findings from a cluster randomised controlled trial

Background: Little is known about the economic impact of military mental health screening. Aims: To investigate (1) whether post-deployment screening of military personnel affects use and cost of services and (2) the impact of psychiatric morbidity on costs. Methods: Participants were recruited from UK Royal Marine and Army platoons and randomised to an intervention group (which received tailored advice predicated upon mental health status) or a control group (which received general advice following assessment of mental health status). The intervention costs were calculated while service use and associated costs were assessed at 12 month follow-up. Results: Data were available for 6,323 participants. Mean screening cost was £34. Service costs were slightly higher in the control group compared to the intervention group (£1,197 vs. £1,147) which was not statistically significant (bootstrapped 95% CI, -£363 to £434. In both groups, screening and control, costs were significantly higher for those who screened positive for mental health problems. Conclusion: Costs were not affected by screening. In countries which have already implemented post-deployment screening, the political cost of disinvestment needs careful consideration. Those who develop psychiatric morbidity have substantially higher care costs than those who do not

Transcatheter Aortic Valve Implantation in Dialysis Patients

Background/Aims: Transcatheter aortic valve implantation (TAVI) has emerged as a new therapeutic option for high-risk patients. However, dialysis patients were excluded from all previous studies. The aim of this study is to compare the outcomes of TAVI for dialysis patients with those for patients with chronic kidney disease (CKD) stages 3 and 4 and to compare TAVI with open surgery in dialysis patients. Methods: Part I: comparison of 10 patients on chronic hemodialysis with 116 patients with non-dialysis-dependent CKD undergoing TAVI. Part II: comparison of transcatheter (n = 15) with open surgical (n = 24) aortic valve replacement in dialysis patients. Results: Part I: dialysis patients were significantly younger (72.3 vs. 82.0 years; p < 0.01). Hospital stay was significantly longer in dialysis patients (21.8 vs. 12.1 days; p = 0.01). Overall 30-day mortality was 3.17%, with no deaths among dialysis patients. Six-month survival rates were similar (log-rank p = 0.935). Part II: patient age was comparable (66.5 vs. 69.5 years; p = 0.42). Patients in the surgical group tended to stay longer in hospital than TAVI patients (29.5 vs. 22.5 days; p = 0.35). Conclusion: TAVI is a safe procedure in patients on chronic hemodialysis. Until new data become available, we find no compelling reason to refuse these patients TAVI. Copyright (C) 2012 S. Karger AG, Base