To Test or Not to Test: Barriers and Solutions to Testing African American College Students for HIV at a Historically Black College/University

Young African Americans are disproportionately affected by sexually transmitted infections, including HIV. The purpose was to identify reasons that African American college students at a historically Black college/university (HBCU) identified as barriers to HIV testing, and how these barriers can be removed. Fifty-seven heterosexual-identified undergraduate students (ages 18-25) attending an HBCU in the southeastern US participated in the study. Latent content analytic techniques were used to code the transcripts for themes and categories, and representative quotations were used in the findings. Qualitative data indicates three main themes used to avoid testing and three themes to encourage testing. Students were forthcoming in discussing the themes around avoidance of HIV testing (being scared to know, preferring not to know, and lack of discussion about HIV) and encouraging testing (group testing, increasing basic knowledge, and showing the reality of HIV). It is important for college healthcare professionals, researchers, and officials to identify appropriate ways to encourage HIV testing, and promote testing as part of overall health

Food resources of stream macroinvertebrates determined by natural-abundance stable C and N isotopes and a 15N tracer addition

Trophic relationships were examined using natural-abundance 13C and 15N analyses and a 15N-tracer addition experiment in Walker Branch, a 1st-order forested stream in eastern Tennessee. In the 15N-tracer addition experiment, we added 15NH4, to stream water over a 6-wk period In early spring, and measured 15N:14N ratios in different taxa and biomass compartments over distance and time. Samples collected from a station upstream from the 15N addition provided data on natural-abundance 13C:12C and 15N:14N ratios. The natural-abundance 15N analysis proved to be of limited value in identifying food resources of macroinvertebrates because 15N values were not greatly different among food resources. In general, the natural-abundance stable isotope approach was most useful for determining whether epilithon or detritus were important food resources for organisms that may use both (e.g., the snail Elimia clavaeformis), and to provide corroborative evidence of food resources of taxa for which the 15N tracer results were not definitive. The 15N tracer results showed that the mayflies Stenonema spp. and Baetis spp. assimilated primarily epilithon, although Baetis appeared to assimilate a portion of the epilithon (e.g., algal cells) with more rapid N turnover than the bulk pool sampled. Although Elimia did not reach isotopic equilibrium during the tracer experiment, application of a N-turnover model to the field data suggested that it assimilated a combination of epilithon and detritus. The amphipod Gammarus minus appeared to depend mostly on fine benthic organic matter (FBOM), and the coleopteran Anchytarsus bicolor on epixylon. The caddisfly Diplectrona modesta appeared to assimilate primarily a fast N-turnover portion of the FBOM pool, and Simuliidae a fast N- turnover component of the suspended particulate organic matter pool rather than the bulk pool sampled. Together, the natural-abundance stable C and N isotope analyses and the experimental 15N tracer approach proved to be very useful tools for identifying food resources in this stream ecosystem

NITROGEN CYCLING IN A FOREST STREAM DETERMINED BY A 15N TRACER ADDITION

Nitrogen uptake and cycling was examined using a six‐week tracer addition of 15N‐labeled ammonium in early spring in Walker Branch, a first‐order deciduous forest stream in eastern Tennessee. Prior to the 15N addition, standing stocks of N were determined for the major biomass compartments. During and after the addition, 15N was measured in water and in dominant biomass compartments upstream and at several locations downstream. Residence time of ammonium in stream water (5–6 min) and ammonium uptake lengths (23–27 m) were short and relatively constant during the addition. Uptake rates of NH4 were more variable, ranging from 22 to 37 μg N·m−2·min−1 and varying directly with changes in streamwater ammonium concentration (2.7–6.7 μg/L). The highest rates of ammonium uptake per unit area were by the liverwort Porella pinnata, decomposing leaves, and fine benthic organic matter (FBOM), although epilithon had the highest N uptake per unit biomass N. Nitrification rates and nitrate uptake lengths and rates were determined by fitting a nitrification/nitrate uptake model to the longitudinal profiles of 15N‐NO3 flux. Nitrification was an important sink for ammonium in stream water, accounting for 19% of the total ammonium uptake rate. Nitrate production via coupled regeneration/nitrification of organic N was about one‐half as large as nitrification of streamwater ammonium. Nitrate uptake lengths were longer and more variable than those for ammonium, ranging from 101 m to infinity. Nitrate uptake rate varied from 0 to 29 μg·m−2·min−1 and was ∼1.6 times greater than assimilatory ammonium uptake rate early in the tracer addition. A sixfold decline in instream gross primary production rate resulting from a sharp decline in light level with leaf emergence had little effect on ammonium uptake rate but reduced nitrate uptake rate by nearly 70%. At the end of the addition, 64–79% of added 15N was accounted for, either in biomass within the 125‐m stream reach (33–48%) or as export of 15N‐NH4 (4%), 15N‐NO3 (23%), and fine particulate organic matter (4%) from the reach. Much of the 15N not accounted for was probably lost downstream as transport of particulate organic N during a storm midway through the experiment or as dissolved organic N produced within the reach. Turnover rates of a large portion of the 15N taken up by biomass compartments were high (0.04–0.08 per day), although a substantial portion of the 15N in Porella (34%), FBOM (21%), and decomposing wood (17%) at the end of the addition was retained 75 d later, indicating relatively long‐term retention of some N taken up from water. In total, our results showed that ammonium retention and nitrification rates were high in Walker Branch, and that the downstream loss of N was primarily as nitrate and was controlled largely by nitrification, assimilatory demand for N, and availability of ammonium to meet that demand. Our results are consistent with recent 15N tracer experiments in N‐deficient forest soils that showed high rates of nitrification and the importance of nitrate uptake in regulating losses of N. Together these studies demonstrate the importance of 15N tracer experiments for improving our understanding of the complex processes controlling N cycling and loss in ecosystems

Separation of river network–scale nitrogen removal among the main channel and two transient storage compartments

Transient storage (TS) zones are important areas of dissolved inorganic nitrogen (DIN) processing in rivers. We assessed sensitivities regarding the relative impact that the main channel (MC), surface TS (STS), and hyporheic TS (HTS) have on network denitrification using a model applied to the Ipswich River in Massachusetts, United States. STS and HTS connectivity and size were parameterized using the results of in situ solute tracer studies in first‐ through fifth‐order reaches. DIN removal was simulated in all compartments for every river grid cell using reactivity derived from Lotic Intersite Nitrogen Experiment (LINX2) studies, hydraulic characteristics, and simulated discharge. Model results suggest that although MC‐to‐STS connectivity is greater than MC‐to‐HTS connectivity at the reach scale, at basin scales, there is a high probability of water entering the HTS at some point along its flow path through the river network. Assuming our best empirical estimates of hydraulic parameters and reactivity, the MC, HTS, and STS removed approximately 38%, 21%, and 14% of total DIN inputs during a typical base flow period, respectively. There is considerable uncertainty in many of the parameters, particularly the estimates of reaction rates in the different compartments. Using sensitivity analyses, we found that the size of TS is more important for DIN removal processes than its connectivity with the MC when reactivity is low to moderate, whereas TS connectivity is more important when reaction rates are rapid. Our work suggests a network perspective is needed to understand how connectivity, residence times, and reactivity interact to influence DIN processing in hierarchical river systems

Model-based spacecraft and mission design for the evaluation of technology

In order to meet the future vision of robotic missions, engineers will face intricate mission concepts, new operational approaches, and technologies that have yet to be developed. The concept of smaller, model driven projects helps this transition by including life-cycle cost as part of the decision making process. For example, since planetary exploration missions have cost ceilings and short development periods, heritage flight hardware is utilized. However, conceptual designs that rely solely on heritage technology will result in estimates that may not be truly representative of the actual mission being designed and built. The Laboratory for Spacecraft and Mission Design (LSMD) at the California Institute of Technology is developing integrated concurrent models for mass and cost estimations. The purpose of this project is to quantify the infusion of specific technologies where the data would be useful in guiding technology developments leading up to a mission. This paper introduces the design-to-cost model to determine the implications of various technologies on the spacecraft system in a collaborative engineering environment. In addition, comparisons of the benefits of new or advanced technologies for future deep space missions are examined

Wildlife as Biosamplers: Contaminants in Hair of Elk Harvested Near the Anaconda Smelter Site

The purpose of this research was to test a new way of investigating biological uptake of smelting-related contaminants with a focus on harvested wildlife. Specific objectives were 1) to collect hair samples from elk (Cervus elaphus) harvested in the vicinity of the Anaconda Smelter National Priority List Site in Montana, 2) to analyze the samples using inductively coupled plasma – mass spectrometry (ICP-MS), and 3) to identify potential elements of concern from the data. Hair samples were collected from 56 elk, and concentration data were processed using a hazard quotient/index approach based on concepts commonly used in fields of ecological and human health risk analyses. Arsenic concentrations in the hair decreased as a function of increasing distance from the Anaconda smelter stack, and 57 % of the elk sampled were identified as animals of concern. For elk harvested within 25 km of the stack, elements of concern were aluminum, arsenic, barium, boron, lithium, manganese, molybdenum, strontium, and vanadium. For elk harvested within 76-101.5 km of the stack, elements of concern were aluminum, barium, boron, lithium, and manganese. Hazard indices for uranium, arsenic, cadmium, and lithium were larger by factors of ~17, 9, 7, and 6, respectively, for elk harvested within 25 km of the stack compared to hazard indices for elk harvested within 76-101.5 km

The risk, burden, and management of non-communicable diseases in cerebral palsy: a scoping review.

AIM: To examine the risk, burden, and management of non-communicable diseases (NCDs) among people with cerebral palsy (CP). METHOD: Databases (Ovid MEDLINE, Embase Ovid, CINAHL Plus) were systematically searched up to August 2017. Data on the prevalence of risk factors for, and the burden and management of, cardiovascular diseases, diabetes, cancers, and respiratory diseases were extracted. RESULTS: Thirty-six studies that examined the prevalence of risk factors among people with CP were identified. There was inconsistent evidence that people with CP had higher prevalence of metabolic risk factors such as hypertension, hyperlipidaemia, and obesity, but strong evidence that they participated in low levels of physical activity, compared with people without CP. Seven studies reported on the burden of NCDs. Adults with CP had a higher risk of NCDs, including stroke, chronic obstructive pulmonary disease, and other heart conditions, and death due to NCDs, including cancers, chronic obstructive pulmonary disease, stroke, and ischaemic heart disease, compared with the general population. Only one study reported on the management of NCD, specifically the uptake of breast cancer screening among females. INTERPRETATION: The burden of NCDs is higher among adults with CP compared with the general population. Further research is required to determine the prevalence of metabolic risk factors and management of NCDs among people with CP. WHAT THIS PAPER ADDS: Adults with cerebral palsy (CP) have an increased risk of non-communicable diseases (NCDs) and increased risk of death because of NCDs. Evidence is inconsistent about the elevated prevalence of metabolic risk factors for NCDs. Evidence is consistent that people with CP participate in reduced physical activity. Only one study reported on management of NCD among people with CP. Available evidence suggests people with CP are less likely to receive preventive medicine

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