Echo-Mapping of Swift J1753.5-0127

We present two epochs of coordinated X-ray-optical timing observations of the black hole candidate Swift J1753.5-0127 during its 2005 outburst. The first epoch in July occurred at outburst peak. Two consecutive nights of observations using the McDonald Observatory Argos camera with the Rossi X-ray Timing Explorer show a consistent correlation with an immediate response and an extended tail lasting ~5s. The properties of the variability and the correlation are consistent with thermal reprocessing in an accretion disk. The shortness of the lag suggests a short orbital period consistent with that recently claimed. The second epoch in August used the VLT FORS2 HIT mode again in conjunction with RXTE. Again a repeatable correlation is seen between two independent subsets of the data. In this case, though, the cross-correlation function has an unusual structure comprising a dip followed by a double-peak. We suggest that this may be equivalent to the dip plus single peak structure seen by Kanbach et al. (2001) in XTE J1118+480 and attributed there to synchrotron emission; a similar structure was seen during later activity of Swift J1753.5-0127 by Durant et al. (2008).Comment: 7 pages, accepted for publication in Monthly Notices of the Royal Astronomical Societ

Self similar Barkhausen noise in magnetic domain wall motion

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/\omega^\alpha$, where $\alpha\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.Comment: 7 pages, RevTex. To appear in Phys. Rev. Let

Magnetic Correlation Length and Universal Amplitude of the Lattice E_8 Ising Model

The perturbation approach is used to derive the exact correlation length $\xi$ of the dilute A_L lattice models in regimes 1 and 2 for L odd. In regime 2 the A_3 model is the E_8 lattice realisation of the two-dimensional Ising model in a magnetic field h at T=T_c. When combined with the singular part f_s of the free energy the result for the A_3 model gives the universal amplitude $f_s \xi^2 = 0.061~728...$ as $h\to 0$ in precise agreement with the result obtained by Delfino and Mussardo via the form-factor bootstrap approach.Comment: 7 pages, Late

Patient experience of Guided self-help CBT intervention for VoicEs (GiVE) delivered within a pilot randomized controlled trial

Background: Access to cognitive behaviour therapy for those with psychosis (CBTp) remains poor. The most frequently endorsed barrier to implementation is a lack of resources. To improve access to CBTp, we developed a brief form of CBTp that specifically targets voice-related distress. The results of our pilot trial of guided self-help CBT for voices (GiVE) suggest the therapy is both acceptable and beneficial. Aims: The present study aims to explore the subjective patient experience of accessing GiVE in the context of a trial. Method: We interviewed 9 trial participants using the Change Interview and a mixed methods approach. Results: Most participants reported at least one positive change that they attributed to GiVE. We extracted five themes: (1) changes that I have noticed; (2) I am not alone; (3) positive therapy experiences; (4) I want more therapy; and (5) helping myself. The themes indicate that participating in the GiVE trial was generally a positive experience. The main areas in which participants experienced changes were improved self-esteem, and the ability to cope with voices. Positive changes were facilitated by embracing and enacting ‘self-help’ and having support both in and out of the therapy sessions. Conclusions: The findings support the use of self-help materials with those distressed by hearing voices, but that support both within and outside the clinical setting can aid engagement and outcomes. Overall, the findings support the continued investigation of GiVE

Outcomes of a remote, decentralized health center-based HIV/AIDS antiretroviral program in Zambia, 2003 to 2007

A cross-sectional study of patients living with HIV/ AIDS treated during 2003 to 2007 in decentralized, rural health centers in Zambia was performed to measure virological outcomes after 12 months of antiretroviral therapy and identify factors associated with virological failure. Data from 228 patients who started antiretroviral therapy >12 months prior were analyzed. In all, 93% received stavudine + lamivudine + nevirapine regimens, and median antiretroviral therapy duration was 23.5 months (interquartile range 20-28). Of the 205 patients tested for viral load, 177 (86%) had viral load <1000 copies/mL. Probability of developing virological failure (viral load >1000 copies/mL) was 8.9% at 24 months and 19.6% at 32 months. Predictors for virological failure were <100% adherence, body mass index <18.5 kg/m(2), and women <40 years old. Of those with virological failure who underwent 3 to 6 months of intensive adherence counseling, 45% obtained virological success. In a remote, resource-limited setting in decentralized health centers, virological and immunological assessments of patients on antiretroviral therapy >12 months showed that positive health outcomes are achievable

Lattice realizations of unitary minimal modular invariant partition functions

The conformal spectra of the critical dilute A-D-E lattice models are studied numerically. The results strongly indicate that, in branches 1 and 2, these models provide realizations of the complete A-D-E classification of unitary minimal modular invariant partition functions given by Cappelli, Itzykson and Zuber. In branches 3 and 4 the results indicate that the modular invariant partition functions factorize. Similar factorization results are also obtained for two-colour lattice models.Comment: 18 pages, Latex, with minor corrections and clarification

Exchange in silicon-based quantum computer architecture

The silicon-based quantum computer proposal has been one of the intensely pursued ideas during the past three years. Here we calculate the donor electron exchange in silicon and germanium, and demonstrate an atomic-scale challenge for quantum computing in Si (and Ge), as the six (four) conduction band minima in Si (Ge) lead to inter-valley electronic interferences, generating strong oscillations in the exchange splitting of two-donor two-electron states. Donor positioning with atomic scale precision within the unit cell thus becomes a decisive factor in determining the strength of the exchange coupling--a fundamental ingredient for two-qubit operations in a silicon-based quantum computer.Comment: 5 pages, 2 figure

Edge-emitting quantum well laser with integrated intracavity electrostatic gate

Ridge waveguide, edge-emitting single quantum well GaAs lasers with an integrated gating electrode have been fabricated. These devices integrate a MESFET structure with the laser PN junction so that the SBD (Schottky barrier diode) depletion layer can be used for transverse current confinement in the laser. Device fabrication was very simple requiring only an anisotropic etch for waveguide definition followed by a single self-aligned contact deposition step. The Schottky barrier depletion layers on either side of the ridge waveguide act to confine free carriers. This structure allows for separation of the optical and electrical confinement in the transverse direction without requiring complex fabrication. The device demonstrated modulation of the pulsed lasing threshold with gate control voltage on a 30 micron wide ridge. Above threshold, increasing power output with increasing gate voltage was demonstrated with negligible gate current. The multimode lasing spectrum showed that the increased power output occurred for all modes with no shift in the mode wavelengths to within the resolution of the measurement system

The Microchannel X-ray Telescope on Board the SVOM Satellite

We present the Micro-channel X-ray Telescope (MXT), a new narrow-field (about 1{\deg}) telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science, scheduled for launch in 2021. MXT is based on square micro pore optics (MPOs), coupled with a low noise CCD. The optics are based on a "Lobster Eye" design, while the CCD is a focal plane detector similar to the type developed for the seven eROSITA telescopes. MXT is a compact and light (<35 kg) telescope with a 1 m focal length, and it will provide an effective area of about 45 cmsq on axis at 1 keV. The MXT PSF is expected to be better than 4.2 arc min (FWHM) ensuring a localization accuracy of the afterglows of the SVOM GRBs to better than 1 arc min (90\% c.l. with no systematics) provided MXT data are collected within 5 minutes after the trigger. The MXT sensitivity will be adequate to detect the afterglows for almost all the SVOM GRBs as well as to perform observations of non-GRB astrophysical objects. These performances are fully adapted to the SVOM science goals, and prove that small and light telescopes can be used for future small X-ray missions.Comment: 6 pages, 6 figures, proceedings of the conference "Swift: 10 years of Discovery", Rome, December 2-5, 2014. To be published by Po