Laminar flow of two miscible fluids in a simple network

When a fluid comprised of multiple phases or constituents flows through a network, non-linear phenomena such as multiple stable equilibrium states and spontaneous oscillations can occur. Such behavior has been observed or predicted in a number of networks including the flow of blood through the microcirculation, the flow of picoliter droplets through microfluidic devices, the flow of magma through lava tubes, and two-phase flow in refrigeration systems. While the existence of non-linear phenomena in a network with many inter-connections containing fluids with complex rheology may seem unsurprising, this paper demonstrates that even simple networks containing Newtonian fluids in laminar flow can demonstrate multiple equilibria. The paper describes a theoretical and experimental investigation of the laminar flow of two miscible Newtonian fluids of different density and viscosity through a simple network. The fluids stratify due to gravity and remain as nearly distinct phases with some mixing occurring only by diffusion. This fluid system has the advantage that it is easily controlled and modeled, yet contains the key ingredients for network non-linearities. Experiments and 3D simulations are first used to explore how phases distribute at a single T-junction. Once the phase separation at a single junction is known, a network model is developed which predicts multiple equilibria in the simplest of networks. The existence of multiple stable equilibria is confirmed experimentally and a criteria for their existence is developed. The network results are generic and could be applied to or found in different physical systems

Living with ‘melanoma’…for a day: a phenomenological analysis of medical students’ simulated experiences

Background Despite the rising incidence of melanoma, medical students have progressively fewer opportunities to encounter patients with this important condition. Curricula tend to attach the greatest value to intellectual forms of learning. Compared to intellectual learning, however, experiential learning affords students deep insights about a condition. Doctors who experience ill health are more empathic towards patients. However opportunities to learn about cancer experientially are limited. Temporary transfer tattoos can simulate the ill health associated with melanoma. We reasoned that, if doctors who have been sick are more empathic, temporarily ‘having’ melanoma might have a similar effect. Objectives Explore the impact of wearing a melanoma tattoo on medical students’ understanding of patienthood and attitudes towards patients with melanoma. Methods Ten fourth year medical students were recruited to a simulation. They wore a melanoma tattoo for 24 hours and listened to a patient’s account of receiving their diagnosis. Data were captured using audio-diaries and face-to-face interviews, transcribed, and analysed phenomenologically using the template analysis method. Results There were four themes: 1) Melanoma simulation: opening up new experiences; 2) Drawing upon past experiences; 3) A transformative introduction to patienthood; 4) Doctors in the making: seeing cancer patients in a new light. Conclusions By means of a novel simulation, medical students were introduced to lived experiences of having a melanoma. Such an inexpensive simulation can prompt students to reflect critically on the empathetic care of such patients in the future

Naming names: Perceptions of name-based HIV reporting, partner notification, and criminalization of non-disclosure among persons living with HIV

Policies of name-based HIV reporting, partner notification (PN), and criminalization of non-disclosure of HIV positive status to sexual partners remain controversial. The views of people living with HIV (PLH) are critical to the success of these three initiatives, but have been understudied. Thus, we interviewed 76 PLH about these policies. Themes arose of potential public health benefits (e.g., epidemiological surveillance and notification of possible exposure) and costs (e.g., deterrence of testing); threats to privacy, civil rights and relationships; government mistrust; and beliefs that prevention is an individual, not governmental responsibility. Misperceptions about the intent, content and scope of these policies, and past experiences of discrimination, shaped these attitudes. To enhance development and implementation of HIV prevention strategies, the views of PLH must be taken into account, and education campaigns need to address misperceptions and mistrust. These data shed light on difficulties in developing and implementing policies that may affect sexual behavior, and have critical implications for future research

Intricacies and inter-relationships between HIV disclosure and HAART: A qualitative study

This study aimed to understand whether and how highly active antiretroviral treatment (HAART) affects views and patterns of disclosure and how disclosure interacts with treatment decisions. One hundred and fifty-two HIV-positive adults (52 MSM, 56 women and 44 IDU men) from four US cities participated in two to three-hour, semi-structured interviews in 1998–99. Results indicate that HAART interacts with and shapes HIV disclosure issues in several ways. Medications may ‘out’ people living with HIV. Thus, in different settings (e.g. work, prisons, drug rehabs and public situations), some try to hide medications or modify dosing schedules, which can contribute to non-adherence, and affect sexual behaviours. Disclosure of HIV and/or HAART may also result in antagonism from others who hold negative attitudes and beliefs about HAART, potentially impeding adherence. Observable side effects of medications can also ‘out’ individuals. Conversely, medications may improve appearance, delaying or impeding disclosure. Some wait until they are on HAART and look ‘well’ before disclosing; some who look healthy as a result of medication deny being HIV-positive. Alternatively, HIV disclosure can lead to support that facilitates initiation of, and adherence to, treatment. HIV disclosure and adherence can shape one another in critical ways. Yet these interactions have been under-studied and need to be further examined. Interventions and studies concerning each of these domains have generally been separate, but need to be integrated, and the importance of relationships between these two areas needs to be recognized

It's not just what you say: Relationships of HIV dislosure and risk reduction among MSM in the post-HAART era

In the post-HAART era, critical questions arise as to what factors affect disclosure decisions and how these decisions are associated with factors such as high-risk behaviors and partner variables. We interviewed 1,828 HIV-positive men who have sex with men (MSM), of whom 46% disclosed to all partners. Among men with casual partners, 41.8% disclosed to all of these partners and 21.5% to none. Disclosure was associated with relationship type, perceived partner HIV status and sexual behaviors. Overall, 36.5% of respondents had unprotected anal sex (UAS) with partners of negative/unknown HIV status. Of those with only casual partners, 80.4% had >1 act of UAS and 58% of these did not disclose to all partners. This 58% were more likely to self-identify as gay (versus bisexual), be aware of their status for <5 years and have more partners. Being on HAART, viral load and number of symptoms were not associated with disclosure. This study—the largest conducted to date of disclosure among MSM and one of the few conducted post-HAART—indicates that almost 1/5th reported UAS with casual partners without disclosure, highlighting a public health challenge. Disclosure needs to be addressed in the context of relationship type, partner status and broader risk-reduction strategies

Developing an intervention to facilitate family communication about inherited genetic conditions, and training genetic counsellors in its delivery.

Many families experience difficulty in talking about an inherited genetic condition that affects one or more of them. There have now been a number of studies identifying the issues in detail, however few have developed interventions to assist families. The SPRinG collaborative have used the UK Medical Research Council's guidance on Developing and Evaluating Complex Interventions, to work with families and genetic counsellors (GCs) to co-design a psycho-educational intervention to facilitate family communication and promote better coping and adaptation to living with an inherited genetic condition for parents and their children (<18 years). The intervention is modelled on multi-family discussion groups (MFDGs) used in psychiatric settings. The MFDG was developed and tested over three phases. First focus groups with parents, young people, children and health professionals discussed whether MFDG was acceptable and proposed a suitable design. Using evidence and focus group data, the intervention and a training manual were developed and three GCs were trained in its delivery. Finally, a prototype MFDG was led by a family therapist and co-facilitated by the three GCs. Data analysis showed that families attending the focus groups and intervention thought MFDG highly beneficial, and the pilot sessions had a significant impact on their family' functioning. We also demonstrated that it is possible to train GCs to deliver the MFDG intervention. Further studies are now required to test the feasibility of undertaking a definitive randomised controlled trial to evaluate its effectiveness in improving family outcomes before implementing into genetic counselling practice.The National Institute of Health Research funded the study but any views expressed do not necessarily reflect those of the Authority. Funded by NIHR reference number: RP-DG-1211-10015

The effect of nitric oxide surface flux on the foreign body response to subcutaneous implants

Although the release of nitric oxide (NO) from biomaterials has been shown to reduce the foreign body response (FBR), the optimal NO release kinetics and doses remain unknown. Herein, polyurethane-coated wire substrates with varying NO release properties were implanted into porcine subcutaneous tissue for 3, 7, 21 and 42 d. Histological analysis revealed that materials with short NO release durations (i.e., 24 h) were insufficient to reduce the collagen capsule thickness at 3 and 6 weeks, whereas implants with longer release durations (i.e., 3 and 14 d) and greater NO payloads significantly reduced the collagen encapsulation at both 3 and 6 weeks. The acute inflammatory response was mitigated most notably by systems with the longest duration and greatest dose of NO release, supporting the notion that these properties are most critical in circumventing the FBR for subcutaneous biomedical applications (e.g., glucose sensors)

The Effect of Partner Sex: Nondisclosure of HIV Status to Male and Female Partners Among Men who Have Sex with Men and Women (MSMW)

A common concern within HIV prevention is that HIV positive MSMW do not disclose their HIV status to female partners who are thus at increased risk for HIV infection. The present study uses unique data to examine whether MSMW disclose more often to male rather than female partners. Data were collected on most recent male and/or female primary partner and four most recent casual partners from 150 MSMW (50 African American, 50 Latino, 50 White). MSMW reported on 590 partners (31% female; 69% male). Disclosure was coded as disclosure before sex, disclosure after sex, or nondisclosure. A series of multinomial logistic regressions with partners clustered within respondents were conducted to evaluate effects of respondent characteristics and partner characteristics on timing of disclosure. In bivariate and multivariate analyses there were no significant differences in odds of disclosure to male and female partners before or after sex. Although MSMW were substantially less likely to disclose to HIV negative partners before sex compared to HIV positive partners regardless of sex, when we fully interacted the multivariate model by partner sex, the odds of disclosure to HIV negative male partners compared to HIV positive male partners before sex were significantly higher than the odds of disclosure to HIV negative female partners compared to HIV positive female partners. Patterns of mutual nondisclosure and nonreciprocal disclosure were observed with both primary and casual partners. The paper makes additional methodological contributions to the measurement and analysis of disclosure