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

Local IRBs vs. Federal Agencies: Shifting Dynamics, Systems, and Relationships

How IRBs relate to federal agencies, and the implications of these relationships, have received little, if any, systematic study. I interviewed 46 IRB chairs, directors, administrators, and members, contacting the leadership of 60 U.S. IRBs (every fourth one in the list of the top 240 institutions by NIH funding), interviewing IRB leaders from 34 (response rate=55%). IRBs describe complex direct and indirect relationships with federal agencies that affect IRBs through audits, guidance documents, and other communications, and can generate problems and challenges. Researchers often blame IRBs for frustrations, but IRBs often serve as the “local face” of federal regulations and agencies and are “stuck in the middle.” These data have critical implications for policy, practice, and research

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

“Am I my genes?”: Questions of identity among individuals confronting genetic disease

Purpose: To explore many questions raised by genetics concerning personal identities that have not been fully investigated. Methods: We interviewed in depth, for 2 hours each, 64 individuals who had or were at risk for Huntington disease, breast cancer, or alpha-1 antitrypsin deficiency. Results: These individuals struggled with several difficult issues of identity. They drew on a range of genotypes and phenotypes (e.g., family history alone; mutations, but no symptoms; or symptoms). They often felt that their predicament did not fit preexisting categories well (e.g., “sick,” “healthy,” “disabled,” “predisposed”), due in part to uncertainties involved (e.g., unclear prognoses, since mutations may not produce symptoms). Hence, individuals varied in how much genetics affected their identity, in what ways, and how negatively. Factors emerged related to disease, family history, and other sources of identity. These identities may, in turn, shape disclosure, coping, and other health decisions. Conclusions: Individuals struggle to construct a genetic identity. They view genetic information in highly subjective ways, varying widely in what aspects of genetic information they focus on and how. These data have important implications for education of providers (to assist patients with these issues), patients, and family members; and for research, to understand these issues more fully

Misunderstandings Concerning Genetics Among Patients Confronting Genetic Disease

Critical questions arise about misunderstandings of genetics. We interviewed for 2 h each, 64 individuals who had or were at risk for Huntington's disease (HD), breast cancer or Alpha‐1 antitrypsin deficiency. These individuals revealed various misunderstandings that can affect coping, and testing, treatment and reproductive decisions. A therapeutic misconception about testing appeared: that testing would be helpful in and of itself. Many believed they could control genetic disorders (even HD), yet these beliefs were often incorrect, and could impede coping, testing, and treatment. Misunderstandings about statistics and genetics often fueled each other, and reflected denial, and desires for hope and control. Emotional needs can thus outweigh understandings of genetics and statistics, and providers’ input. Individuals often maintained non‐scientific beliefs, though embarrassed by these. These data have implications for care, and public and professional education. Misunderstandings’ persistence, despite realization of their inaccuracy, suggests that providers need to address not just cognitive facts, but underlying emotional issues

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

“In Sickness and in Health”? Disclosures of Genetic Risks in Dating

Individuals who have, or are at risk for, various genetic disorders face many challenges concerning disclosures of genetic information in dating situations. We conducted a qualitative interview study of 64 individuals confronting Huntington's disease, breast cancer, or Alpha‐1 antitrypsin deficiency, examining what issues these individuals encountered, and how they viewed and addressed these—including issues of understandings, privacy, and disclosures of genetic information to various groups (e.g., family members). Incidental to the primary research questions addressed, participants also often described a series of dilemmas in dating situations that they and/or family members, friends, and fellow patients faced of whether to date, and if so, whether, what, how, why, and when to disclose their genetic risk or illness. At times, these individuals feared and experienced rejection, and hence delayed, avoided, or opposed disclosure, or disclosed indirectly or inadvertently. These data are reported in this paper and highlight the importance of patients, their loved ones, genetic counselors, and other health care providers being aware of these issues, and appreciating the complex factors involved, which can affect patients’ coping and social support. This paper, the first to explore several key aspects of disclosures of genetic information in dating, thus suggests needs for public and professional education, and future research in this area

Attitudes and Practices Among Internists Concerning Genetic Testing

Many questions remain concerning whether, when, and how physicians order genetic tests, and what factors are involved in their decisions. We surveyed 220 internists from two academic medical centers about their utilization of genetic testing. Rates of genetic utilizations varied widely by disease. Respondents were most likely to have ordered tests for Factor V Leiden (16.8 %), followed by Breast/Ovarian Cancer (15.0 %). In the past 6 months, 65 % had counseled patients on genetic issues, 44 % had ordered genetic tests, 38.5 % had referred patients to a genetic counselor or geneticist, and 27.5 % had received ads from commercial labs for genetic testing. Only 4.5 % had tried to hide or disguise genetic information, and <2 % have had patients report genetic discrimination. Only 53.4 % knew of a geneticist/genetic counselor to whom to refer patients. Most rated their knowledge as very/somewhat poor concerning genetics (73.7 %) and guidelines for genetic testing (87.1 %). Most felt needs for more training on when to order tests (79 %), and how to counsel patients (82 %), interpret results (77.3 %), and maintain privacy (80.6 %). Physicians were more likely to have ordered a genetic test if patients inquired about genetic testing (p  < .001), and if physicians had a geneticist/genetic counselor to whom to refer patients (p  < .002), had referred patients to a geneticist/genetic counselor in the past 6 months, had more comfort counseling patients about testing (p  < .019), counseled patients about genetics, larger practices (p  < .032), fewer African‐American patients (p  < .027), and patients who had reported genetic discrimination (p  < .044). In a multiple logistic regression, ordering a genetic test was associated with patients inquiring about testing, having referred patients to a geneticist/genetic counselor and knowing how to order tests. These data suggest that physicians recognize their knowledge deficits, and are interested in training. These findings have important implications for future medical practice, research, and education

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