Graviton Propagation and Vacuum Polarization in Curved Space

The effects of vacuum polarization arising from loops of massive scalar particles on graviton propagation in curved space are considered. Physically, they are due to curvature induced tidal forces acting on the cloud of virtual scalar particles surrounding the graviton. The effects are tractable in a WKB and large mass limit and the results can be written as an effective refractive index for the graviton modes with both a real and imaginary part. The imaginary part of the refractive index is a curvature induced contribution to the wavefunction renormalization of the graviton in real affine time and can have the effect of dressing or un-dressing the graviton. The real part of the refractive index increases logarithmically at high frequency as long as the null energy condition is satisfied by the background.Comment: 21 pages, typos correcte

Low frequency sound propagation in activated carbon

Activated carbon can adsorb and desorb gas molecules onto and off its surface. Research has examined whether this sorption affects low frequency sound waves, with pressures typical of audible sound, interacting with granular activated carbon. Impedance tube measurements were undertaken examining the resonant frequencies of Helmholtz resonators with different backing materials. It was found that the addition of activated carbon increased the compliance of the backing volume. The effect was observed up to the highest frequency measured (500 Hz), but was most significant at lower frequencies (at higher frequencies another phenomenon can explain the behavior). An apparatus was constructed to measure the effective porosity of the activated carbon as well as the number of moles adsorbed at sound pressures between 104 and 118 dB and low frequencies between 20 and 55 Hz. Whilst the results were consistent with adsorption affecting sound propagation, other phenomena cannot be ruled out. Measurements of sorption isotherms showed that additional energy losses can be caused by water vapor condensing onto and then evaporating from the surface of the material. However, the excess absorption measured for low frequency sound waves is primarily caused by decreases in surface reactance rather than changes in surface resistance

Mental health problems: Are they or are they not a risk factor for dropout from drug treatment? A systematic review of the evidence

Background: A sizeable number of recent studies investigating whether clients with substance misuse and mental health problems (dual diagnosis clients) are at heightened risk of dropout from drug treatment have been published. It is timely that their findings are brought together in a comprehensive review of the current evidence. Aims: The aim of the review is to examine whether dually diagnosed clients are less likely to be retained in drug treatment than clients without mental health problems, and, if so, whether this varies for clients diagnosed with different types of mental health problems. Methods: The review considers peer-reviewed research published after 1 January 1990, which was located using the literature databases Medline and PsycInfo. Predefined search terms were used. Further papers were identified from the bibliographies of relevant publications. Findings: 58 studies (84% from the USA) met the inclusion criteria for the review. The findings suggest that for most clients, having a past history of mental health problems does not influence the likelihood of being retained in drug treatment. The body of evidence regarding concurrent mental health problems is contradictory. On the whole, the majority of studies suggest that neither presence nor severity of depressive, anxiety, or other Axis-I disorders is related to retention, but these findings are not entirely unequivocal, as a few studies report strong positive or negative associations between depression and anxiety disorders and retention. Few researchers looked separately at psychotic spectrum disorders hence no conclusions could be drawn. The presence of most personality disorders also did not appear to affect treatment tenure, with the exception of antisocial personality disorder, for which the evidence points towards a greater risk of dropout. Conclusions: The balance of evidence suggests that, overall, dual diagnosis clients with Axis-I disorders who seek treatment in drug treatment services are retained as well as clients without dual diagnosis. Subgroups of clients who appear more vulnerable to premature dropout include those with antisocial personality disorder. Methodological shortcomings of the reviewed studies and resulting implications for this review and future research are discussed

Meta-Analysis of Prevalence and Risk Factors for Cognitive Decline and Improvement After Transcatheter Aortic Valve Implantation

Changes to cognition, both decline and improvement, are commonly reported after transcatheter aortic valve implantation (TAVI). However, previous systematic reviews and meta-analyses have missed these subgroups by assessing whole-group-averages for cognitive outcomes. We sought to pool estimates to identify the prevalence of cognitive decline and improvement after TAVI, as well as associated factors for these outcomes. A systematic review identified 15 articles appropriate for meta-analysis. When robust cognitive change definitions were employed, the pooled prevalence of incident cognitive impairment up to 1-, 1 to 6-, and ≥6-months post-TAVI was 7%, 14%, and 12%, respectively. For cognitive improvement, the prevalence from 1 to 6 months and ≥6 months after TAVI was estimated to be 19% and 11%, respectively. Two factors were associated with these cognitive outcomes: (1) using a cerebral embolic protection device was associated with decreased prevalence of cognitive decline up to 1-week post-TAVI; (2) baseline cognitive impairment had a large association with post-TAVI cognitive improvement. In conclusion, cognitive decline and cognitive improvement are experienced by approximately 7% to 19% of patients after TAVI, respectively. Those with the lowest cognitive performance pre-TAVI appear to have the most to gain in terms of cognitive improvement post-TAVI. Identifying further predictive factors for cognitive decline and improvement post-TAVI will facilitate a personalized-medicine approach for cognitive care and prognosis

Prescription Drugs Associated with Reports of Violence Towards Others

CONTEXT: Violence towards others is a seldom-studied adverse drug event and an atypical one because the risk of injury extends to others. OBJECTIVE: To identify the primary suspects in adverse drug event reports describing thoughts or acts of violence towards others, and assess the strength of the association. METHODOLOGY: From the Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) data, we extracted all serious adverse event reports for drugs with 200 or more cases received from 2004 through September 2009. We identified any case report indicating homicide, homicidal ideation, physical assault, physical abuse or violence related symptoms. MAIN OUTCOME MEASURES: Disproportionality in reporting was defined as a) 5 or more violence case reports, b) at least twice the number of reports expected given the volume of overall reports for that drug, c) a χ2 statistic indicating the violence cases were unlikely to have occurred by chance (p<0.01). RESULTS: We identified 1527 cases of violence disproportionally reported for 31 drugs. Primary suspect drugs included varenicline (an aid to smoking cessation), 11 antidepressants, 6 sedative/hypnotics and 3 drugs for attention deficit hyperactivity disorder. The evidence of an association was weaker and mixed for antipsychotic drugs and absent for all but 1 anticonvulsant/mood stabilizer. Two or fewer violence cases were reported for 435/484 (84.7%) of all evaluable drugs suggesting that an association with this adverse event is unlikely for these drugs. CONCLUSIONS: Acts of violence towards others are a genuine and serious adverse drug event associated with a relatively small group of drugs. Varenicline, which increases the availability of dopamine, and antidepressants with serotonergic effects were the most strongly and consistently implicated drugs. Prospective studies to evaluate systematically this side effect are needed to establish the incidence, confirm differences among drugs and identify additional common features

Modulating attentional load affects numerosity estimation: evidence against a pre-attentive subitizing mechanism

Traditionally, the visual enumeration of a small number of items (1 to about 4), referred to as subitizing, has been thought of as a parallel and pre-attentive process and functionally different from the serial attentive enumeration of larger numerosities. We tested this hypothesis by employing a dual task paradigm that systematically manipulated the attentional resources available to an enumeration task. Enumeration accuracy for small numerosities was severely decreased as more attentional resources were taken away from the numerical task, challenging the traditionally held notion of subitizing as a pre-attentive, capacity-independent process. Judgement of larger numerosities was also affected by dual task conditions and attentional load. These results challenge the proposal that small numerosities are enumerated by a mechanism separate from large numerosities and support the idea of a single, attention-demanding enumeration mechanism

Timeliness of Clinic Attendance is a good predictor of Virological Response and Resistance to Antiretroviral drugs in HIV-infected patients

Ensuring long-term adherence to therapy is essential for the success of HIV treatment. As access to viral load monitoring and genotyping is poor in resource-limited settings, a simple tool to monitor adherence is needed. We assessed the relationship between an indicator based on timeliness of clinic attendance and virological response and HIV drug resistance

Towards the Formalization of Fractional Calculus in Higher-Order Logic

Fractional calculus is a generalization of classical theories of integration and differentiation to arbitrary order (i.e., real or complex numbers). In the last two decades, this new mathematical modeling approach has been widely used to analyze a wide class of physical systems in various fields of science and engineering. In this paper, we describe an ongoing project which aims at formalizing the basic theories of fractional calculus in the HOL Light theorem prover. Mainly, we present the motivation and application of such formalization efforts, a roadmap to achieve our goals, current status of the project and future milestones.Comment: 9 page

The need to promote behaviour change at the cultural level: one factor explaining the limited impact of the MEMA kwa Vijana adolescent sexual health intervention in rural Tanzania. A process evaluation

Background - Few of the many behavioral sexual health interventions in Africa have been rigorously evaluated. Where biological outcomes have been measured, improvements have rarely been found. One of the most rigorous trials was of the multi-component MEMA kwa Vijana adolescent sexual health programme, which showed improvements in knowledge and reported attitudes and behaviour, but none in biological outcomes. This paper attempts to explain these outcomes by reviewing the process evaluation findings, particularly in terms of contextual factors. Methods - A large-scale, primarily qualitative process evaluation based mainly on participant observation identified the principal contextual barriers and facilitators of behavioural change. Results - The contextual barriers involved four interrelated socio-structural factors: culture (i.e. shared practices and systems of belief), economic circumstances, social status, and gender. At an individual level they appeared to operate through the constructs of the theories underlying MEMA kwa Vijana - Social Cognitive Theory and the Theory of Reasoned Action – but the intervention was unable to substantially modify these individual-level constructs, apart from knowledge. Conclusion - The process evaluation suggests that one important reason for this failure is that the intervention did not operate sufficiently at a structural level, particularly in regard to culture. Recently most structural interventions have focused on gender or/and economics. Complementing these with a cultural approach could address the belief systems that justify and perpetuate gender and economic inequalities, as well as other barriers to behaviour change