Psychosocial and sexual characteristics associated with sexualised drug use and chemsex among men who have sex with men (MSM) in the UK.

OBJECTIVE: To understand how the emerging public health issue of chemsex relates to broader patterns of sexualised drug use (SDU) among men who have sex with men (MSM), which has been understudied. METHODS: Potential participants were invited to take part in an anonymous, cross-sectional online survey through Facebook advertising and community organisations' social media posts (April-June 2018). Multivariable logistic regression was used to compare MSM who engaged in recent SDU (past 12 months) with those who did not, and those who engaged in chemsex (γ-hydroxybutyrate/γ-butyrolactone, crystal methamphetamine, mephedrone, ketamine) with those who engaged in other SDU (eg, poppers, cocaine, cannabis). RESULTS: Of the 1648 MSM included, 41% reported recent SDU; 15% of these (6% of total, n=99) reported chemsex. Factors associated with SDU were recent STI diagnosis (aOR=2.44, 95% CI 1.58 to 3.76), sexual health clinic attendance (aOR=2.46, 95% CI 1.90 to 3.20), image and performance-enhancing drug use (aOR=3.82, 95% CI 1.87 to 7.82), greater number of condomless anal male partners, lower satisfaction with life and greater sexual satisfaction. Predictors of chemsex compared with other SDU were not being UK-born (aOR=2.02, 95% CI 1.05 to 3.86), living in a densely populated area (aOR=2.69, 95% CI 1.26 to 5.74), low sexual self-efficacy (aOR=4.52, 95% CI 2.18 to 9.40) and greater number of condomless anal male partners. Living with HIV, taking pre-exposure prophylaxis (PrEP), and experiencing or being unsure of experiencing sexual contact without consent were significantly associated with SDU and chemsex in bivariate analyses but not in the multivariable. CONCLUSION: Health and behavioural differences were observed between MSM engaging in chemsex, those engaging in SDU and those engaging in neither. While some MSM engaging in chemsex and SDU appeared content with these behaviours, the association with life satisfaction and sexual self-efficacy indicates psychosocial support is needed for some. The association with sexual risk and sexual consent also indicates the importance of promoting harm reduction among this population (eg, condoms, PrEP, drug knowledge)

A systematic approach to the failed plastic surgical reconstruction of the diabetic foot

Plastic reconstruction for diabetic foot wounds must be approached carefully and follow sound micro-surgical principles as it relates to the anatomy of the designated flap chosen for coverage. First, the surgeon always needs to evaluate the local and general conditions of the presenting pathology and patient, respectively when considering a flap for reconstruction. The flap that is chosen is based on the vascularity, location, and size of the defect. Salvage of the failed flap and revisional reconstructive procedures are very challenging. Often, adjunctive therapies such as hyperbaric oxygen, negative pressure wound therapy, vasodilators, and/or vascular surgery is required. In certain case scenarios, such as patients with poor general health and compromised local vascularity in which revisional flap coverage cannot be performed, the above mentioned adjunctive therapies could be used as a primary treatment to potentially salvage a failing flap

Core components for effective infection prevention and control programmes: new WHO evidence-based recommendations

Abstract Health care-associated infections (HAI) are a major public health problem with a significant impact on morbidity, mortality and quality of life. They represent also an important economic burden to health systems worldwide. However, a large proportion of HAI are preventable through effective infection prevention and control (IPC) measures. Improvements in IPC at the national and facility level are critical for the successful containment of antimicrobial resistance and the prevention of HAI, including outbreaks of highly transmissible diseases through high quality care within the context of universal health coverage. Given the limited availability of IPC evidence-based guidance and standards, the World Health Organization (WHO) decided to prioritize the development of global recommendations on the core components of effective IPC programmes both at the national and acute health care facility level, based on systematic literature reviews and expert consensus. The aim of the guideline development process was to identify the evidence and evaluate its quality, consider patient values and preferences, resource implications, and the feasibility and acceptability of the recommendations. As a result, 11 recommendations and three good practice statements are presented here, including a summary of the supporting evidence, and form the substance of a new WHO IPC guideline

Psychosocial and sexual factors associated with recent sexual health clinic attendance and HIV testing among trans people in the UK.

OBJECTIVES: Trans people remain an understudied population in the UK, with unmet sexual health needs. The aim of this research was to identify possible barriers and facilitators for sexual health clinic attendance and HIV testing among trans people. METHODS: Lesbian, gay, bisexual and transgender (LGBT) participants from across the UK were invited to take part in a cross-sectional online survey through Facebook advertising (April-June 2018). Psychosocial and sexual factors associated with recent sexual health clinic attendance, and ever having an HIV test were examined using multivariate logistic regression. RESULTS: A total of 3007 cisgender and 500 trans participants completed the survey. Trans participants were less likely to attend a sexual health clinic than cisgender participants (27% vs 36%, p<0.001) and report ever having an HIV test (49% vs 64%, p<0.001). One trans participant reported living with HIV and three reported currently taking pre-exposure prophylaxis. Factors associated with trans sexual health clinic attendance were: living in London, having a relationship with multiple partners, engaging in condomless anal intercourse, greater life satisfaction, and having alcohol and/or drugs before sex. Being a person of colour, aged 25-49 years, in a relationship with multiple partners, condomless anal intercourse, lower body dissatisfaction, and having drugs before sex were associated with ever having an HIV test among trans participants. CONCLUSIONS: Trans people were less likely to attend sexual health services than cisgender people, and half of trans participants who reported condomless anal intercourse had never had an HIV test. Further research is needed to understand and improve uptake of sexual health services among trans people

Optimal measurement of visual motion across spatial and temporal scales

Sensory systems use limited resources to mediate the perception of a great variety of objects and events. Here a normative framework is presented for exploring how the problem of efficient allocation of resources can be solved in visual perception. Starting with a basic property of every measurement, captured by Gabor's uncertainty relation about the location and frequency content of signals, prescriptions are developed for optimal allocation of sensors for reliable perception of visual motion. This study reveals that a large-scale characteristic of human vision (the spatiotemporal contrast sensitivity function) is similar to the optimal prescription, and it suggests that some previously puzzling phenomena of visual sensitivity, adaptation, and perceptual organization have simple principled explanations.Comment: 28 pages, 10 figures, 2 appendices; in press in Favorskaya MN and Jain LC (Eds), Computer Vision in Advanced Control Systems using Conventional and Intelligent Paradigms, Intelligent Systems Reference Library, Springer-Verlag, Berli

Spacelike Singularities and Hidden Symmetries of Gravity

We review the intimate connection between (super-)gravity close to a spacelike singularity (the "BKL-limit") and the theory of Lorentzian Kac-Moody algebras. We show that in this limit the gravitational theory can be reformulated in terms of billiard motion in a region of hyperbolic space, revealing that the dynamics is completely determined by a (possibly infinite) sequence of reflections, which are elements of a Lorentzian Coxeter group. Such Coxeter groups are the Weyl groups of infinite-dimensional Kac-Moody algebras, suggesting that these algebras yield symmetries of gravitational theories. Our presentation is aimed to be a self-contained and comprehensive treatment of the subject, with all the relevant mathematical background material introduced and explained in detail. We also review attempts at making the infinite-dimensional symmetries manifest, through the construction of a geodesic sigma model based on a Lorentzian Kac-Moody algebra. An explicit example is provided for the case of the hyperbolic algebra E10, which is conjectured to be an underlying symmetry of M-theory. Illustrations of this conjecture are also discussed in the context of cosmological solutions to eleven-dimensional supergravity.Comment: 228 pages. Typos corrected. References added. Subject index added. Published versio

Verticalization of bacterial biofilms

Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms of rod-shaped bacteria were observed at single-cell resolution and shown to develop from a disordered, two-dimensional layer of founder cells into a three-dimensional structure with a vertically-aligned core. Here, we elucidate the physical mechanism underpinning this transition using a combination of agent-based and continuum modeling. We find that verticalization proceeds through a series of localized mechanical instabilities on the cellular scale. For short cells, these instabilities are primarily triggered by cell division, whereas long cells are more likely to be peeled off the surface by nearby vertical cells, creating an "inverse domino effect". The interplay between cell growth and cell verticalization gives rise to an exotic mechanical state in which the effective surface pressure becomes constant throughout the growing core of the biofilm surface layer. This dynamical isobaricity determines the expansion speed of a biofilm cluster and thereby governs how cells access the third dimension. In particular, theory predicts that a longer average cell length yields more rapidly expanding, flatter biofilms. We experimentally show that such changes in biofilm development occur by exploiting chemicals that modulate cell length.Comment: Main text 10 pages, 4 figures; Supplementary Information 35 pages, 15 figure

Phenotypic covariance of longevity, immunity and stress resistance in the Caenorhabditis nematodes

Background \ud Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin– like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four \ud Caenorhabditis species. \ud \ud Methodology/Principal Findings \ud We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged \ud significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. \ud \ud Conclusions \ud The gonochoristic species display a significantly longer lifespan (p < 0.0001)and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants

Phenotypic covariance of Longevity, Immunity and Stress Resistance in the Caenorhabditis Nematodes

Background: Ageing, immunity and stresstolerance are inherent characteristics of all organisms. In animals, these traits are regulated, at least in part, by forkhead transcription factors in response to upstream signals from the Insulin/Insulin–like growth factor signalling (IIS) pathway. In the nematode Caenorhabditis elegans, these phenotypes are molecularly linked such that activation of the forkhead transcription factor DAF-16 both extends lifespan and simultaneously increases immunity and stress resistance. It is known that lifespan varies significantly among the Caenorhabditis species but, although DAF-16 signalling is highly conserved, it is unclear whether this phenotypic linkage occurs in other species. Here we investigate this phenotypic covariance by comparing longevity, stress resistance and immunity in four Caenorhabditis species. \ud \ud Methodology/Principal Findings: We show using phenotypic analysis of DAF-16 influenced phenotypes that among four closely related Caenorhabditis nematodes, the gonochoristic species (Caenorhabditis remanei and Caenorhabditis brenneri) have diverged significantly with a longer lifespan, improved stress resistance and higher immunity than the hermaphroditic species (C. elegans and Caenorhabditis briggsae). Interestingly, we also observe significant differences in expression levels between the daf-16 homologues in these species using Real-Time PCR, which positively correlate with the observed phenotypes. Finally, we provide additional evidence in support of a role for DAF-16 in regulating phenotypic coupling by using a combination of wildtype isolates, constitutively active daf-16 mutants and bioinformatic analysis. \ud \ud Conclusions: The gonochoristic species display a significantly longer lifespan (p<0.0001) and more robust immune and stress response (p<0.0001, thermal stress; p<0.01, heavy metal stress; p<0.0001, pathogenic stress) than the hermaphroditic species. Our data suggests that divergence in DAF-16 mediated phenotypes may underlie many of the differences observed between these four species of Caenorhabditis nematodes. These findings are further supported by the correlative higher daf-16 expression levels among the gonochoristic species and significantly higher lifespan, immunity and stress tolerance in the constitutively active daf-16 hermaphroditic mutants

A Survey on Continuous Time Computations

We provide an overview of theories of continuous time computation. These theories allow us to understand both the hardness of questions related to continuous time dynamical systems and the computational power of continuous time analog models. We survey the existing models, summarizing results, and point to relevant references in the literature