Near-wall velocity measurements by Particle-Shadow-Tracking

We report a new method to measure the velocity of a fluid in the vicinity of a wall. The method, that we call Particle-Shadow Tracking (PST), simply consists in seeding the fluid with a small number of fine tracer particles of density close to that of the fluid. The position of each particle and of its shadow on the wall are then tracked simultaneously, allowing one to accurately determine the distance separating tracers from the wall and therefore to extract the velocity field. We present an application of the method to the determination of the velocity profile inside a laminar density current flowing along an inclined plane

Pathologies in Asymptotically Lifshitz Spacetimes

There has been significant interest in the last several years in studying possible gravitational duals, known as Lifshitz spacetimes, to anisotropically scaling field theories by adding matter to distort the asymptotics of an AdS spacetime. We point out that putative ground state for the most heavily studied example of such a spacetime, that with a flat spatial section, suffers from a naked singularity and further point out this singularity is not resolvable by any known stringy effect. We review the reasons one might worry that asymptotically Lifshitz spacetimes are unstable and employ the initial data problem to study the stability of such systems. Rather surprisingly this question, and even the initial value problem itself, for these spacetimes turns out to generically not be well-posed. A generic normalizable state will evolve in such a way to violate Lifshitz asymptotics in finite time. Conversely, enforcing the desired asymptotics at all times puts strong restrictions not just on the metric and fields in the asymptotic region but in the deep interior as well. Generically, even perturbations of the matter field of compact support are not compatible with the desired asymptotics.Comment: 36 pages, 1 figure, v2: Enhanced discussion of singularity, including relationship to Gubser's conjecture and singularity in RG flow solution, plus minor clarification

Lymph node core biopsies reliably permit diagnosis of lymphoproliferative diseases. Real‐World Experience from 554 sequential core biopsies from a single centre

INTRODUCTION: Whilst excision biopsy is traditionally preferred, advances in radiological and histological techniques warrant a re-look at core biopsy as a viable primary diagnostic method. METHOD: Over a 3-year period, all patients who underwent core biopsy to investigate lymphoma at our centre were included. RESULTS: 554 consecutive patients were included (40.1% prior lymphoma and 59.4% new presentations). Three or more cores were taken in 420 (75.8%) cases. Median time from request to biopsy and biopsy to histology report was 2 (0-40) days and 7 (1-24) days respectively. 510/544 (93.8%) biopsies were diagnostic. There was no difference in whether the biopsy was diagnostic based on indication (new vs. relapsed lymphoma) (p=0.445), whether biopsy was PET-directed (p=0.507), for T-cell lymphoma (p=0.468) or nodal vs. extra-nodal (p=0.693). Thirty-eight patients (6.9%) required a second biopsy due to inadequate tissue. In a patient experience survey, only 13.9% reported any complications (1 self-limiting minor bleeding, 4 bruising) whilst 16.7% reported any discomfort beyond 12 hours. CONCLUSION: Core biopsy performed by experienced radiologists and analysed by expert haemato-pathologists is a reliable, well-tolerated method for diagnosing lymphoma and confirming relapse. Multiple cores can be obtained under local anaesthetic yielding sufficient material in the majority of cases

Cell-free (RNA) and cell-associated (DNA) HIV-1 and postnatal transmission through breastfeeding

<p>Introduction - Transmission through breastfeeding remains important for mother-to-child transmission (MTCT) in resource-limited settings. We quantify the relationship between cell-free (RNA) and cell-associated (DNA) shedding of HIV-1 virus in breastmilk and the risk of postnatal HIV-1 transmission in the first 6 months postpartum.</p> <p>Materials and Methods - Thirty-six HIV-positive mothers who transmitted HIV-1 by breastfeeding were matched to 36 non-transmitting HIV-1 infected mothers in a case-control study nested in a cohort of HIV-infected women. RNA and DNA were quantified in the same breastmilk sample taken at 6 weeks and 6 months. Cox regression analysis assessed the association between cell-free and cell-associated virus levels and risk of postnatal HIV-1 transmission.</p> <p>Results - There were higher median levels of cell-free than cell-associated HIV-1 virus (per ml) in breastmilk at 6 weeks and 6 months. Multivariably, adjusting for antenatal CD4 count and maternal plasma viral load, at 6 weeks, each 10-fold increase in cell-free or cell-associated levels (per ml) was significantly associated with HIV-1 transmission but stronger for cell-associated than cell-free levels [2.47 (95% CI 1.33–4.59) vs. aHR 1.52 (95% CI, 1.17–1.96), respectively]. At 6 months, cell-free and cell-associated levels (per ml) in breastmilk remained significantly associated with HIV-1 transmission but was stronger for cell-free than cell-associated levels [aHR 2.53 (95% CI 1.64–3.92) vs. 1.73 (95% CI 0.94–3.19), respectively].</p> <p>Conclusions - The findings suggest that cell-associated virus level (per ml) is more important for early postpartum HIV-1 transmission (at 6 weeks) than cell-free virus. As cell-associated virus levels have been consistently detected in breastmilk despite antiretroviral therapy, this highlights a potential challenge for resource-limited settings to achieve the UNAIDS goal for 2015 of eliminating vertical transmission. More studies would further knowledge on mechanisms of HIV-1 transmission and help develop more effective drugs during lactation.</p&gt

Considerations for a combined index for limited cutaneous systemic sclerosis to support drug development and improve outcomes

Systemic sclerosis (systemic scleroderma) is characterized by a heterogeneous range of clinical manifestations. Systemic sclerosis is classified into limited cutaneous systemic sclerosis and diffuse cutaneous systemic sclerosis subgroups based on the extent of skin involvement. Randomized controlled trials in scleroderma have mainly focused on diffuse cutaneous systemic sclerosis partly because the measurement of skin involvement, critical for evaluating a therapeutic intervention, is more dynamic in this subset. Nonetheless, limited cutaneous systemic sclerosis, the most common cutaneous subset (about two-third), is also associated with significant morbidity and detrimental impact on health-related quality of life. The lack of interventional studies in limited cutaneous systemic sclerosis is partly due to a lack of relevant outcome measures to evaluate this subgroup. Combining several clinically meaningful outcomes selected specifically for limited cutaneous systemic sclerosis may improve representativeness in clinical trials and responsiveness of outcomes measured in randomized controlled trials. A composite index dedicated to limited cutaneous systemic sclerosis combining such relevant outcomes could advance clinical trial development for limited cutaneous systemic sclerosis by providing the opportunity to test and select among candidate drugs that could act as disease-modifying treatments for this neglected subgroup of systemic sclerosis. This proposed index would include items selected by expert physicians and patients with limited cutaneous systemic sclerosis across domains grounded in the lived experience of limited cutaneous systemic sclerosis. This article reviews the reasons behind the relative neglect of limited cutaneous systemic sclerosis, discusses the current state of outcome measures for limited cutaneous systemic sclerosis, identifies challenges, and proposes a roadmap for a combined limited cutaneous systemic sclerosis-specific treatment response index

On the relationship between the reversed hazard rate and elasticity

Despite hazard and reversed hazard rates sharing a number of similar aspects, reversed hazard functions are far less frequently used. Understanding their meaning is not a simple task. The aim of this paper is to expand the usefulness of the reversed hazard function by relating it to other well-known concepts broadly used in economics: (linear or cumulative) rates of increase and elasticity. This will make it possible (i) to improve our understanding of the consequences of using a particular distribution and, in certain cases, (ii) to introduce our hypotheses and knowledge about the random process in a more meaningful and intuitive way, thus providing a means to achieving distributions that would otherwise be hardly imaginable or justifiable

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

The construction of an idealised urban masculinity among men with concurrent sexual partners in a South African township

Background : The perspectives of heterosexual males who have large sexual networks comprising concurrent sexual partners and who engage in high-risk sexual behaviours are scarcely documented. Yet these perspectives are crucial to understanding the high HIV prevalence in South Africa where domestic violence, sexual assault and rape are alarmingly high, suggesting problematic gender dynamics. Objective : To explore the construction of masculinities and men's perceptions of women and their sexual relationships, among men with large sexual networks and concurrent partners. Design : This qualitative study was conducted in conjunction with a larger quantitative survey among men at high risk of HIV, using respondent-driven sampling to recruit participants, where long referral chains allowed us to reach far into social networks. Twenty in-depth, open-ended interviews with South African men who had multiple and concurrent sexual partners were conducted. A latent content analysis was used to explore the characteristics and dynamics of social and sexual relationships. Results : We found dominant masculine ideals characterised by overt economic power and multiple sexual partners. Reasons for large concurrent sexual networks were the perception that women were too empowered, could not be trusted, and lack of control over women. Existing masculine norms encourage concurrent sexual networks, ignoring the high risk of HIV transmission. Biological explanations and determinism further reinforced strong and negative perceptions of women and female sexuality, which helped polarise men's interpretation of gender constructions. Conclusions : Our results highlight the need to address sexuality and gender dynamics among men in growing, informal urban areas where HIV prevalence is strikingly high. Traditional structures that could work as focal entry points should be explored for effective HIV prevention aimed at normative change among hard-to-reach men in high-risk urban and largely informal contexts

Prioritising the most needed paediatric antiretroviral formulations: the PADO4 list

Despite considerable progress in paediatric HIV treatment and timely revision of global policies recommending the use of more effective and tolerable antiretroviral regimens, optimal antiretroviral formulations for infants, children, and adolescents remain limited. The Paediatric Antiretroviral Drug Optimization group reviews medium-term and long-term priorities for antiretroviral drug development to guide industry and other stakeholders on formulations most needed for low-income and middle-income countries. The group convened in December, 2018, to assess progress since the previous meeting and update the list of priority formulations. Issues relating to drug optimisation for neonatal prophylaxis and paediatric treatment, and those relating to the investigation of novel antiretrovirals in adolescents and pregnant and lactating women were also discussed. Continued focus on identifying, prioritising, and providing access to optimal antiretroviral formulations suitable for infants, children, and adolescents is key to ensuring that global HIV treatment targets can be met