Line tension and structure of smectic liquid crystal multilayers at the air-water interface

At the air/water interface, 4,-8-alkyl[1,1,-biphenyl]-4-carbonitrile (8CB) domains with different thicknesses coexist in the same Langmuir film, as multiple bilayers on a monolayer. The edge dislocation at the domain boundary leads to line tension, which determines the domain shape and dynamics. By observing the domain relaxation process starting from small distortions, we find that the line tension is linearly dependent on the thickness difference between the coexisting phases in the film. Comparisons with theoretical treatments in the literature suggest that the edge dislocation at the boundary locates near the center of the film, which means that the 8CB multilayers are almost symmetric with respect to the air/water interface.Comment: 21 pages, 6 figure

Determination of Inter-Phase Line Tension in Langmuir Films

A Langmuir film is a molecularly thin film on the surface of a fluid; we study the evolution of a Langmuir film with two co-existing fluid phases driven by an inter-phase line tension and damped by the viscous drag of the underlying subfluid. Experimentally, we study an 8CB Langmuir film via digitally-imaged Brewster Angle Microscopy (BAM) in a four-roll mill setup which applies a transient strain and images the response. When a compact domain is stretched by the imposed strain, it first assumes a bola shape with two tear-drop shaped reservoirs connected by a thin tether which then slowly relaxes to a circular domain which minimizes the interfacial energy of the system. We process the digital images of the experiment to extract the domain shapes. We then use one of these shapes as an initial condition for the numerical solution of a boundary-integral model of the underlying hydrodynamics and compare the subsequent images of the experiment to the numerical simulation. The numerical evolutions first verify that our hydrodynamical model can reproduce the observed dynamics. They also allow us to deduce the magnitude of the line tension in the system, often to within 1%. We find line tensions in the range of 200-600 pN; we hypothesize that this variation is due to differences in the layer depths of the 8CB fluid phases.Comment: See (http://www.math.hmc.edu/~ajb/bola/) for related movie

Effector memory differentiation increases detection of replication-competent HIV-l in resting CD4+ T cells from virally suppressed individuals.

Studies have demonstrated that intensive ART alone is not capable of eradicating HIV-1, as the virus rebounds within a few weeks upon treatment interruption. Viral rebound may be induced from several cellular subsets; however, the majority of proviral DNA has been found in antigen experienced resting CD4+ T cells. To achieve a cure for HIV-1, eradication strategies depend upon both understanding mechanisms that drive HIV-1 persistence as well as sensitive assays to measure the frequency of infected cells after therapeutic interventions. Assays such as the quantitative viral outgrowth assay (QVOA) measure HIV-1 persistence during ART by ex vivo activation of resting CD4+ T cells to induce latency reversal; however, recent studies have shown that only a fraction of replication-competent viruses are inducible by primary mitogen stimulation. Previous studies have shown a correlation between the acquisition of effector memory phenotype and HIV-1 latency reversal in quiescent CD4+ T cell subsets that harbor the reservoir. Here, we apply our mechanistic understanding that differentiation into effector memory CD4+ T cells more effectively promotes HIV-1 latency reversal to significantly improve proviral measurements in the QVOA, termed differentiation QVOA (dQVOA), which reveals a significantly higher frequency of the inducible HIV-1 replication-competent reservoir in resting CD4+ T cells

Documenting Nursing and Medical Students’ Stereotypes about Hispanic and American Indian Patients

Objective: Hispanic Americans and American Indians face significant health disparities compared with White Americans. Research suggests that stereotyping of minority patients by members of the medical community is an important antecedent of race and ethnicity-based health disparities. This work has primarily focused on physicians’ perceptions, however, and little research has examined the stereotypes healthcare personnel associate with Hispanic and American Indian patients. The present study assesses: 1) the health-related stereotypes both nursing and medical students hold about Hispanic and American Indian patients, and 2) nursing and medical students’ motivation to treat Hispanic and American Indian patients in an unbiased manner. Design: Participants completed a questionnaire assessing their awareness of stereotypes that healthcare professionals associate with Hispanic and American Indian patients then completed measures of their motivation to treat Hispanics and American Indians in an unbiased manner. Results: Despite being highly motivated to treat Hispanic and American Indian individuals fairly, the majority of participants reported awareness of stereotypes associating these patient groups with noncompliance, risky health behavior, and difficulty understanding and/or communicating health-related information. Conclusion: This research provides direct evidence for negative health-related stereotypes associated with two understudied minority patient groups—Hispanics and American Indians—among both nursing and medical personnel

Antibody Testing and Lyme Disease Risk

Lyme disease test results for >9,000 dogs were collected from participating veterinary clinics. Testing was conducted by using the IDEXX 3Dx kit, used widely by Maine veterinarians to screen clinically normal dogs during heartworm season. This study demonstrates how this test can be a valuable public health disease surveillance tool

The Gulf Stream Front, Its Role in Larval Fish Survival and Recruitment in Florida: Hydrographic Station and Plankton Data

The goal of this project was to develop a clearer understanding of the role that the Gulf Stream system plays in larval fish survival and recruitment in Florida waters. The specific objectives of this study were to: Determine whether the biomass of fish larva, other zooplankton, microzooplankton and phytoplankton is higher at the shoreward front of the Gulf Stream than on either side of it. Characterize the assemblages of fish larvae predators and prey both at the front and on either side of it. Determine if the composition, abundance and size frequency distribution of larval and juvenile fishes in the front is different from that in the coastal zone or in the Gulf Stream. Monitor the position of the Gulf Stream by continuous measurements of physical variables at moorings located in the Gulf Stream off Fort Lauderdale and within Port Everglades. This project was a first effort to characterize the coupling between physical and biological processes that may influence the early life histories of fishes in Florida\u27s coastal waters. This report contains the hydrographic and plankton data from the project. It is intended to facilitate data access by the scientific and management communities. Interpretations and detailed analyses of these data are being given in meeting presentations, peer-reviewed journal articles (Stone et al. draft manuscript, Braker et al. draft manuscript, Frazel et al. in preparation) and graduate theses (Stone 1993; Braker 1993)

Validity and reliability of lower-limb pulse-wave velocity assessments using an oscillometric technique

There is a growing interest in the deleterious effects of sedentary behaviour on lower-limb arterial health. To permit further investigation, including in larger epidemiological studies, there is a need to identify lower-limb arterial health assessment tools that are valid and reliable, yet simple to administer. Purpose: This study sought to determine the validity and between-day reliability of femoral-ankle pulse-wave velocity (faPWV) measures obtained using an oscillometric-based device (SphygmocCor XCEL) in supine and seated positions. Doppler ultrasound (US) was used as the criterion. Methods: A total of 47 healthy adults were recruited for validity (n=32) and reliability (n=15) analyses. Validity was determined by measuring faPWV in seated and supine positions using the XCEL and US devices, in a randomised order. Between-day reliability was determined by measuring seated and supine faPWV using the XCEL on 3 different mornings, separated by a maximum of 7 days. Results: The validity criteria (absolute standard error of estimate [aSEE] <1.0 m/s) was met in the supine (aSEE = 0.8 m/s, 95% CI: 0.4-1.0), but not the seated (aSEE = 1.2 m/s, 95 % CI: 1.1, 1.2) position. Intras-class correlation coefficient estimates revealed the XCEL demonstrated good reliability in the supine position (ICC=0.83, 95% CI: 0.65, 0.93), but poor reliability in the seated position (ICC = 0.29, 95% CI: 0.23, 0.63). Conclusions: The oscillometric XCEL device can be used to determine lower-limb PWV with acceptable validity and reliability in the conventionally recommended supine position, but not the seated position

Drinking water and the implications for gender equity and empowerment: a systematic review of qualitative and quantitative evidence

Background: Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE). Methods: A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and clinicaltrials.gov). Drinking water studies with an all-female cohort or disaggregated findings according to gender were included. Results: A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men. Conclusion: This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy

The Chandra Source Catalog

The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed to satisfy the needs of a broad-based group of scientists, including those who may be less familiar with astronomical data analysis in the X-ray regime. The first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public ACIS imaging observations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents <~ 30''. The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1 sigma uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of <~ 1 false source per field for a 100 ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively.Comment: To appear in The Astrophysical Journal Supplement Series, 53 pages, 27 figure