10,707 research outputs found
Effect of picosecond strain pulses on thin layers of the ferromagnetic semiconductor (Ga,Mn)(As,P)
The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of
(Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect
(MOKE). A transient MOKE signal followed by low amplitude oscillations was
evidenced, with a strong dependence on applied magnetic field, temperature and
ps-ASP amplitude. Careful interferometric measurement of the layer's thickness
variation induced by the ps-ASP allowed us to model very accurately the
resulting signal, and interpret it as the strain modulated reflectivity
(differing for probe polarizations), independently from dynamic
magnetization effects.Comment: 6 pages, 5 figure
Work distribution functions for hysteresis loops in a single-spin system
We compute the distribution of the work done in driving a single Ising spin
with a time-dependent magnetic field. Using Glauber dynamics we perform
Monte-Carlo simulations to find the work distributions at different driving
rates. We find that in general the work-distributions are broad with a
significant probability for processes with negative dissipated work. The
special cases of slow and fast driving rates are studied analytically. We
verify that various work fluctuation theorems corresponding to equilibrium
initial states are satisfied while a steady state version is not.Comment: 9 pages, 15 figure
The evaluation of Education Maintenance Allowance Pilots: three years' evidence: a quantitative evaluation
This is the third report of the longitudinal quantitative evaluation of Education Maintenance Allowance (EMA) pilots and the first since the government announced that EMA is to be rolled out nationally from 2004. The evaluation was commissioned in 1999, by the Department for Education and Skills (DfES) from a consortium of research organisations, led by the Centre for Research in Social Policy (CRSP) and including the National Centre for Social Research, the Institute for Fiscal Studies (IFS) and the National Institute for Careers Education and Counselling (NICEC).
The statistical evaluation design is a longitudinal cohort study involving large random sample surveys of young people (and their parents) in 10 EMA pilot areas and eleven control areas. Two cohorts of young people were selected from Child Benefit records. The first cohort of young people left compulsory schooling in the summer of 1999 and they, and their parents, were interviewed between October 1999 and April 2000 (Year 12 interview). A second interview was carried out with these young people between October 2000 and April 2001 (Year 13 interview). The second cohort left compulsory education the following summer of 2000 and young people, and their parents, were first interviewed between October 2000 and April 2001.
The report uses both propensity score matching (PSM) and descriptive techniques, each of which brings their own particular strengths to the analysis
Dirac neutrino mass from the beta decay end-point modified by the dynamics of a Lorentz-violating equation of motion
Using a generalized procedure for obtaining the equation of motion of a
propagating fermionic particle, we examine previous claims for a lightlike
preferred axis embedded in the framework of Lorentz-invariance violation with
preserved algebra. In a high energy scale, the corresponding equation of motion
is reduced to a conserving lepton number chiral (VSR) equation, and in a low
energy scale, the Dirac equation for a free is recovered. The new dynamics
introduces some novel ingredients (modified cross section) to the phenomenology
of the tritium beta decay end-point.Comment: 11 pages, 4 figure
Costs borne by families of children hospitalized in a pediatric intensive care unit: a pilot study.
Hospitalisation of a child in a paediatric intensive care unit (PICU) involves major stress for parents. They wish to stay at their child's bedside while at the same time giving the usual attention to their other children. The resultant out-of-pocket expenses have rarely been studied.
Over a 6-month period all the families of children hospitalised in our PICU for more than 4 days, speaking French and insured by our social security system, were eligible for inclusion. Participation was proposed only after diagnosis, treatment and prognosis had been determined. Costs were retrieved from a diary list of customised items and computed as the amount in excess of usual expenses until the end of the hospital stay.
117 children were hospitalised in our PICU for a total of 131 stays. The families of 16 fulfilled the inclusion criteria. One dropped out after a week at the parents' request. The children's age was 2.9 +/- 3.8 years and 67% were male. The majority had malformations (53%) or infections (33%). The total length of stay was 49 +/- 51 days, of which 24 +/- 41 were spent in the PICU. On average, parents spent CHF 86 +/- 31 every day, mainly on travel and meals. Over the entire hospital stay their expenses amounted to CHF 4,078 +/- 4,552.
Direct out-of-pocket expenses for parents of children hospitalised in the PICU are considerable. Improvement in the social security system may be necessary to address this issue
Exploring the major difficulties perceived by residents in training: a pilot study.
To assess residents' difficulties during the first year of residency. In contrast to previous studies that mainly used structured questionnaires, a qualitative procedure was applied.
Twenty-four consecutive first-year residents in internal medicine were asked to "Please identify two to three major difficulties or concerns related to your practice of medicine within this hospital". The answers were submitted to content analysis performed by three independent researchers. Inter-rater agreement was high (kappa coefficient = 0.92). Disagreements were solved by consensus.
Physicians' characteristics: female 37%, mean age 28 +/- 2.2 years, mean duration of postgraduate training 2.5 +/- 1.3 years. Total number of answers: 122, average answers/resident 5.1 +/- 1.3. Nine categories were extracted from content analysis: communication problems at the workplace, feelings of not being respected, constraints of collaborative work, experiencing the gap between medical school and clinical care, work overload, responsibility towards and emotional investment in patients, worries about career plans, and lack of theoretical knowledge. Residents expressed major difficulties in communicating with and being respected by seniors and peers in particular, and hospital staff in general. They also voiced problems in coping with emotions, either their own or those of their patients.
The residents' responses stressed the complexity of blending the requirements of the physician's role when instrumental/cognitive knowledge is not sufficient to deal with problems requiring personal and relational dimensions. Learning to combine medical knowledge and practice necessitates helping students/residents identify and deal with the constraints of these requirements
An exploration of occupation in nursing home residents with dementia
Objectives: This study evaluated the sitting room environment of two nursing homes
in Ireland, using interactive occupation and social engagement as outcome measures
and defining these rooms as occupational spaces.
Method: Snapshot observational recordings were made in the main sitting rooms
during the periods of time when the rooms were in most active use. Narrative
information was also recorded.
Results: Residents were more likely to occupy their time in the main sitting room
passively, rather than in interactive occupation and social engagement. The nursing
home residents with dementia spent approximately 70% of their daily time in the
main sitting room areas in states of occupational disengagement.
Discussion: Additional insight is provided through pragmatic narrative descriptions
of the functioning of the main sitting room environment in terms of interactive
occupation and social engagement.
Relevance: The research study demonstrates a methodology for evaluating the
sitting room areas of a care environment, using interactive occupation and social
engagement as outcome measures,which can be used for descriptive and comparative
insights into the performance of care environments
Pair correlations of scattered atoms from two colliding Bose-Einstein Condensates: Perturbative Approach
We apply an analytical model for anisotropic, colliding Bose-Einstein
condensates in a spontaneous four wave mixing geometry to evaluate the second
order correlation function of the field of scattered atoms. Our approach uses
quantized scattering modes and the equivalent of a classical, undepleted pump
approximation. Results to lowest order in perturbation theory are compared with
a recent experiment and with other theoretical approaches.Comment: 9 pages, 3 figure
Laser Guide Star Adaptive Optics Integral Field Spectroscopy of a Tightly Collimated Bipolar Jet from the Herbig Ae star LkHa 233
We have used the integral field spectrograph OSIRIS and laser guide star
adaptive optics at Keck Observatory to obtain high angular resolution (0.06"),
moderate spectral resolution (R ~ 3800) images of the bipolar jet from the
Herbig Ae star LkHa 233, seen in near-IR [Fe II] emission at 1.600 & 1.644
microns. This jet is narrow and tightly collimated, with an opening angle of
only 9 degrees, and has an average radial velocity of ~ 100 km/s. The jet and
counterjet are asymmetric, with the red-shifted jet much clumpier than its
counterpart at the angular resolution of our observations. The observed
properties are in general similar to jets seen around T Tauri stars, though it
has a relatively large mass flux of (1.2e-7 +- 0.3e-7) M_sun/year, near the
high end of the observed mass flux range around T Tauri stars. We also
spatially resolve an inclined circumstellar disk around LkHa 233, which
obscures the star from direct view. By comparison with numerical radiative
transfer disk models, we estimate the disk midplane to be inclined i = 65 +- 5
degrees relative to the plane of the sky. Since the star is seen only in
scattered light at near-infrared wavelengths, we detect only a small fraction
of its intrinsic flux. Because previous estimates of its stellar properties did
not account for this, either LkHa 233 must be located closer than the
previously believed, or its true luminosity must be greater than previously
supposed, consistent with its being a ~4 M_sun star near the stellar birthline.Comment: Accepted for publication in the Ap
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