Relativistic Stellar Pulsations With Near-Zone Boundary Conditions

A new method is presented here for evaluating approximately the pulsation modes of relativistic stellar models. This approximation relies on the fact that gravitational radiation influences these modes only on timescales that are much longer than the basic hydrodynamic timescale of the system. This makes it possible to impose the boundary conditions on the gravitational potentials at the surface of the star rather than in the asymptotic wave zone of the gravitational field. This approximation is tested here by predicting the frequencies of the outgoing non-radial hydrodynamic modes of non-rotating stars. The real parts of the frequencies are determined with an accuracy that is better than our knowledge of the exact frequencies (about 0.01%) except in the most relativistic models where it decreases to about 0.1%. The imaginary parts of the frequencies are determined with an accuracy of approximately M/R, where M is the mass and R is the radius of the star in question.Comment: 10 pages (REVTeX 3.1), 5 figs., 1 table, fixed minor typos, published in Phys. Rev. D 56, 2118 (1997

Generalized r-Modes of the Maclaurin Spheroids

Analytical solutions are presented for a class of generalized r-modes of rigidly rotating uniform density stars---the Maclaurin spheroids---with arbitrary values of the angular velocity. Our analysis is based on the work of Bryan; however, we derive the solutions using slightly different coordinates that give purely real representations of the r-modes. The class of generalized r-modes is much larger than the previously studied `classical' r-modes. In particular, for each l and m we find l-m (or l-1 for the m=0 case) distinct r-modes. Many of these previously unstudied r-modes (about 30% of those examined) are subject to a secular instability driven by gravitational radiation. The eigenfunctions of the `classical' r-modes, the l=m+1 case here, are found to have particularly simple analytical representations. These r-modes provide an interesting mathematical example of solutions to a hyperbolic eigenvalue problem.Comment: 12 pages, 3 figures; minor changes and additions as will appear in the version to be published in Physical Review D, January 199

On the Geometry of Planar Domain Walls

The Geometry of planar domain walls is studied. It is argued that the planar walls indeed have plane symmetry. In the Minkowski coordinates the walls are mapped into revolution paraboloids.Comment: 11 paghoj, Late

Pharmacotherapy for post-traumatic stress disorder : a systematic review and meta-analysis

The original publication is available at http://www.samj.org.zaCITATION: Ipser, J., [et al.]. 2006. Pharmacotherapy for post-traumatic stress disorder: a systematic review and meta-analysis. South African Medical Journal, 96(10):1088-1096.Background. Post-traumatic stress disorder (PTSD) is a prevalent and disabling condition. Evidence that PTSD is characterised by specific psychobiological dysfunctions has contributed to a growing interest in use of medication in its treatment. Objectives. To assess the effects of medication in the treatment of PTSD. Design. Systematic review of randomised controlled trials (RCTs) following the Cochrane Collaboration guidelines. A more detailed version of the review is published in the Cochrane Database of Systematic Reviews. Methods. We searched the Cochrane Depression, Anxiety and Neurosis Group specialised register, the Cochrane Central Register of Controlled Trials (Cochrane Library issue 4, 2004), MEDLINE (January 1966 - December 2004), PsycINFO (1966 - 2004), the National PTSD Center Pilots database, and the meta register module of the Controlled Trials'database. Reference lists of retrieved articles were searched for additional studies. Two raters independently assessed RCTs for inclusion in the review, collated trial data, and assessed trial quality. Investigators were contacted to obtain missing data. Summary statistics were stratified by medication class, and by medication agent for the selective serotonin-re-uptake inhibitors (SSRIs). Dichotomous and continuous measures were calculated using a random effects model, heterogeneity was assessed, and subgroup/sensitivity analyses were done. Main results. Thirty-five short-term (14 weeks or less) RCTs were included in the analysis (4 547, participants). Symptom severity for 17 trials was significantly reduced in the medication groups, relative to placebo (weighted mean difference (WMD) = -5.76, 95% confidence interval (CI): -8.16 - -3.36, N = 2 507). Similarly, summary statistics for responder status from 13 trials demonstrated overall superiority of a variety of medication agents compared with placebo (relative risk (RR) = 1.49, 95% CI: 1.28, 1.73, number needed to treat (NNT) = 4.85, N = 1272). Medication and placebo response occurred in 59.1% (N = 644) and 38.5% (N = 628) of patients, respectively. Of the medication classes, evidence of treatment efficacy was most convincing for the SSRIs. Medication was also effective in reducing the severity of the PTSD re-experiencing/intrusion, avoidance/numbing, and hyperarousal symptom clusters in 9 trials (N = 1 304). In addition, medication was superior to placebo in reducing co-morbid depression and disability. Medication was also less well tolerated than placebo. A narrative review of the 3 maintenance trials suggested that long-term medication may be required in treating PTSD. Conclusion. Medication treatments can be effective in treating PTSD, acting to reduce its core symptoms, as well as associated depression and disability, and should be considered as part of the treatment of this disorder. The findings of this review support the status of SSRIs as first-line agents in the pharmacotherapy of PTSD, as well as their value in long-term treatment. However, there remain important gaps in the evidence base, and there is a continued need for more effective agents in the management of PTSD.Publisher’s versio

Pharmacotherapy for post-traumatic stress disorder- a systematic review and meta-analysis

Background. Post-traumatic stress disorder (PTSD) is a prevalent and disabling condition. Evidence that PTSD is characterised by specific psychobiological dysfunctions has contributed to a growing interest in use of medication in its treatment. Objectives. To assess the effects of medication in the treatment of PTSD. Objectives. To assess the effects of medication in the treatment of PTSD. Design. Systematic review of randomised controlled trials (RCTs) following the Cochrane Collaboration guidelines. A more detailed version of the review is published in the Cochrane Database of Systematic Reviews. Methods. We searched the Cochrane Depression, Anxiety and Neurosis Group specialised register, the Cochrane Central Register of Controlled Trials (Cochrane Library issue 4, 2004), MEDLINE (January 1966 - December 2004), PsycINFO (1966 - 2004), the National PTSD Center Pilots database, and the meta register module of the Controlled Trials database. Reference lists of retrieved articles were searched for additional studies. Two raters independently assessed RCTs for inclusion in the review, collated trial data, and assessed trial quality. Investigators were contacted to obtain missing data. Summary statistics were stratified by medication class, and by medication agent for the selective serotonin re-uptake inhibitors (SSRIs). Dichotomous and continuous measures were calculated using a random effects model, heterogeneity was assessed, and subgroup/sensitivity analyses were done. Main results. Thirty-five short-term (14 weeks or less) RCTs were included in the analysis (4 597 participants). Symptom severity for 17 trials was significantly reduced in the medication groups, relative to placebo (weighted mean difference (WMD) = −5.76, 95% confidence interval (CI): −8.16 - −3.36, N = 2 507). Similarly, summary statistics for responder status from 13 trials demonstrated overall superiority of a variety of medication agents compared with placebo (relative risk (RR) = 1.49, 95% CI: 1.28, 1.73, number needed to treat (NNT) = 4.85, N = 1 272). Medication and placebo response occurred in 59.1% (N = 644) and 38.5% (N = 628) of patients, respectively. Of the medication classes, evidence of treatment efficacy was most convincing for the SSRIs. Medication was also effective in reducing the severity of the PTSD re-experiencing/intrusion, avoidance/numbing, and hyperarousal symptom clusters in 9 trials (N = 1 304). In addition, medication was superior to placebo in reducing comorbid depression and disability. Medication was also less well tolerated than placebo. A narrative review of the 3 maintenance trials suggested that long-term medication may be required in treating PTSD. Conclusion. Medication treatments can be effective in treating PTSD, acting to reduce its core symptoms, as well as associated depression and disability, and should be considered as part of the treatment of this disorder. The findings of this review support the status of SSRIs as first-line agents in the pharmacotherapy of PTSD, as well as their value in longterm treatment. However, there remain important gaps in the evidence base, and there is a continued need for more effective agents in the management of PTSD

Cosmic balloons

Cosmic balloons, consisting of relativistic particles trapped inside a spherical domain wall, may be created in the early universe. We calculate the balloon mass $M$ as a function of the radius $R$ and the energy density profile, $\rho (r)$, including the effects of gravity. At the maximum balloon mass $2GM/R\approx 0.52$ for any value of the mass density of the wall.Comment: 9 pages, LaTeX, 2 figures in separate file, UPTP-93-1

Exemplar variance supports robust learning of facial identity

Differences in the visual processing of familiar and unfamiliar faces have prompted considerable interest in face learning, the process by which unfamiliar faces become familiar. Previous work indicates that face learning is determined in part by exposure duration; unsurprisingly, viewing faces for longer affords superior performance on subsequent recognition tests. However, there has been further speculation that exemplar variation, experience of different exemplars of the same facial identity, contributes to face learning independently of viewing time. Several leading accounts of face learning, including the averaging and pictorial coding models, predict an exemplar variation advantage. Nevertheless, the exemplar variation hypothesis currently lacks empirical support. The present study therefore sought to test this prediction by comparing the effects of unique exemplar face learning - a condition rich in exemplar variation - and repeated exemplar face learning œ a condition that equates viewing time, but constrains exemplar variation. Crucially, observers who received unique exemplar learning displayed better recognition of novel exemplars of the learned identities at test, than observers in the repeated exemplar condition. These results have important theoretical and substantive implications for models of face learning and for approaches to face training in applied contexts

Second-order rotational effects on the r-modes of neutron stars

Techniques are developed here for evaluating the r-modes of rotating neutron stars through second order in the angular velocity of the star. Second-order corrections to the frequencies and eigenfunctions for these modes are evaluated for neutron star models. The second-order eigenfunctions for these modes are determined here by solving an unusual inhomogeneous hyperbolic boundary-value problem. The numerical techniques developed to solve this unusual problem are somewhat non-standard and may well be of interest beyond the particular application here. The bulk-viscosity coupling to the r-modes, which appears first at second order, is evaluated. The bulk-viscosity timescales are found here to be longer than previous estimates for normal neutron stars, but shorter than previous estimates for strange stars. These new timescales do not substantially affect the current picture of the gravitational radiation driven instability of the r-modes either for neutron stars or for strange stars.Comment: 13 pages, 5 figures, revte