2,231 research outputs found

    The Effects of Fish Trap Mesh Size on Reef Fish Catch off Southeastern Florida

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    Catch and mesh selectivity of wire-meshed fish traps were tested for eleven different mesh sizes ranging from 13 X 13 mm (0.5 x 0.5") to 76 x 152 mm (3 X 6"). A total of 1,810 fish (757 kg) representing 85 species and 28 families were captured during 330 trap hauls off southeastern Florida from December 1986 to July 1988. Mesh size significantly affected catches. The 1.5" hexagonal mesh caught the most fish by number, weight, and value. Catches tended to decline as meshes got smaller or larger. Individual fish size increased with larger meshes. Laboratory mesh retention experiments showed relationships between mesh shape and size and individual retention for snapper (Lutjanidae), grouper (Serranidae), jack (Carangidae), porgy (Sparidae), and surgeonfish (Acanthuridae). These relationships may be used to predict the effect of mesh sizes on catch rates. Because mesh size and shape greatly influenced catchability, regulating mesh size may provide a useful basis for managing the commercial trap fishery

    Lower Limb Muscle Activation in Young Adults Walking in Water and on Land

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    Previous research has shown that exercise interventions requiring increased activation of the tibialis anterior (TA), the primary ankle dorsiflexor, can improve walking performance in individuals with foot drop. Correspondingly, heightened drag forces experienced during walking performed in water may augment TA activation during the swing phase of gait, potentially leading to improved walking gait on land. Therefore, this study aimed to compare surface electromyographic (sEMG) activation in the TA and medial gastrocnemius (GM) during gait performed in water versus on land. Thirty-eight healthy, recreationally active young adults, comprising 18 females and 20 males, participated in the study. Each participant completed 2 min walking trials under five conditions: land 2.5 mph, land 3.5 mph, water 2.5 mph, water 3.5 mph, and water 3.5 mph with added jet resistance. Stride kinematics were collected using 2-dimensional underwater motion capture. TA and GM, muscle activation magnitudes, were quantified using sEMG root-mean-square (RMS) amplitudes for both the swing and stance phases of walking. Additionally, TA and GM co-activation (Co-A) indices were estimated. Two-way within-subjects repeated measures analyses of variance were used to evaluate the main effects of and interactions between the environment and walking speed. Additionally, paired sample t-tests were conducted as a secondary analysis to investigate differences between walking in water at 3.5 mph with and without added jet resistance. Main effects and interactions were observed across various stride kinematics and sEMG measures. Notably, TA sEMG RMS during the swing phase of walking gait performed at 2.5 mph was 15% greater in water than on land (p \u3c 0.001). This effect increased when walking gait was performed at 3.5 mph (94%; p \u3c 0.001) and when jet resistance was added to the 3.5 mph condition (52%; p \u3c 0.001). Furthermore, TA Co-A was increased during the stance phase of gait in water compared to on land (p \u3c 0.001), while GM Co-A was reduced during the swing phase (p \u3c 0.001). The findings of this study offer compelling evidence supporting the efficacy of aquatic treadmill walking as a potential treatment for individuals suffering from foot drop. However, further research is needed to evaluate whether a causal relationship exists between heightened TA activation observed during aquatic treadmill walking and improvements in voluntary dorsiflexion during gait

    Influence of Northern Bobwhite Nest Site Selection on Nest Survival in an Agricultural Landscape

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    Working farms provide excellent potential for conserving northern bobwhite (Colinus virginianus) habitat in agricultural landscapes. Managing for areas of early successional vegetation can increase bobwhite abundance with little reduction in crop production on working farms, but the mechanisms behind the increase is not well known. Our objective was to determine nest site characteristics that may predict nest initiation and survival on agricultural lands to inform future management activities. We radio-collared 241 wild bobwhite on 1 farm with and 2 farms without bobwhite habitat management in southeastern North Carolina. Study sites consisted of a 1,740-ha farm with 9% of property actively managed for early successional cover using areas planted in native vegetation and fallow field borders, a 170-ha farm with 2% of property in early-successional field borders monitored in 2014, and a 395-ha farm with no previous early successional management efforts monitored in 2015. We monitored nests (n = 71) from 15 May to 30 September, 2014 and 2015. We compared vegetation cover between nests and paired reference sites within 250 m of each nest using a generalized linear mixed-effect model. We used measurements of vegetation cover types at nest sites as predictors of nest survival using the Program MARK nest survival model. Bobwhite on the farm with habitat management exhibited higher nest initiation (1 nest/2 marked individuals) than those on unmanaged farms (1 nest/4 marked individuals). On the managed farm, 76% of nests were located in fallow early successional vegetation. Percent forb cover (P = \u3c 0.001) was greater at nest sites on managed (μ = 53.61, SE = 4.32) than unmanaged (μ = 17.01, SE = 2.49) farms. Bobwhite selected nest sites with greater forb cover (β = 1.08, SE = 0.21) than reference sites. Daily nest survival was 0.962 (SE = 0.007) with no covariates that described variation in nest survival rates. Results indicate increasing fallow forb cover on agricultural lands can benefit nest initiation rates by increasing the cover bobwhite select for nesting

    Determining the accuracy of zero-flux and ingestible thermometers in the peri-operative setting

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    Accurately monitoring peri-operative core temperature is a cornerstone of good practice. Relatively invasive devices such as oesophageal temperature probes and pulmonary artery catheters facilitate this, but are inappropriate for many patients. There remains a need for accurate monitors of core temperature that can be used in awake patients. This study compared the accuracy of two core temperature thermometers that can be used for this purpose: the 3M Bair Hugger™ Temperature Monitoring System Zero Flux Thermometer and the CorTempR™ Wireless Ingestible Temperature Sensor. Readings were compared with the oesophageal probe, the current intraoperative standard. Thirty patients undergoing elective surgical procedures under general anaesthesia were recruited. The ingestible sensor was ingested prior to induction of anaethesia, and post induction, the zero-flux electrode attached above the right eyebrow and oesophageal probe inserted. During surgery, the temperature on each device was recorded every minute. Measurements were compared using Bland–Altman analysis. The ingestible sensor experienced interference from use of diathermy and fluoroscopy in the operating theatre, rendering 39% of its readings unusable. These were removed from analysis. With remaining readings the bias compared with oesophageal probe was + 0.42 °C, with 95% limits of agreement − 2.4 °C to 3.2 °C. 75.4% of readings were within ± 0.5 °C of the OTP reading. The bias for the zero flux electrode compared to oesophageal probe was + 0.02 °C with 95% limits of agreement − 0.5 °C to 0.5 °C. 97.7% of readings were within ± 0.5 °C of the oesophageal probe. The study findings suggest the zero-flux thermometer is sufficiently accurate for clinical use, whereas the ingestible sensor is not

    Measuring and predicting reservoir heterogeneity in complex deposystems: the Late Cambrian Rose Run sandstone of Eastern Ohio and Western Pennsylvania

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    A cooperative two-year multidisciplinary research program, conducted by the Ohio Division of Geological Survey (ODGS) and the Pennsylvania Bureau of Topographic and Geologic Survey (PTGS), designed to measure and predict reservoir heterogeneity in the Upper Cambrian Rose Run sandstone in those two states.257 pages, 125 figures (including numerous maps, cross sections, seismic lines, and photographs of rock thin sections), 6 tables, and five case studies of Rose Run oil and gas fields.Prepared for U.S. Department of Energy, Assistant Secretary for Fossil Energy. Work performed under Contract No. DE-AC22-90BC14657.This two-year investigation of the Upper Cambrian Rose Run sandstone in Eastern Ohio and Western Pennsylvania was conducted by the Ohio and Pennsylvania Geological Surveys in a cost-sharing agreement with the U.S. Department of Energy under the auspices of the Appalachian Oil and Natural Gas Research Consortium, which consists of West Virginia University and the state geological surveys of Kentucky, Ohio, Pennsylvania, and West Virginia

    The Dynamics of Radiation Pressure-Dominated HII Regions

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    We evaluate the role of radiation pressure in the dynamics of HII regions. We first determine under what conditions radiation pressure is significant in comparison to gas pressure and show that, while radiation pressure is generally unimportant for HII regions driven by a handful of massive stars, it is dominant for the larger HII regions produced by the massive star clusters found near the Galactic center and in starburst environments. We then provide a solution for the problem of how HII regions expand when radiation pressure influences their behavior. Finally, we compare radiation-dominated HII regions to other sources of stellar feedback, and argue that HII regions are probably the primary mechanism for regulating the formation of massive star clusters.Comment: 11 pages, 3 figures, emulateapj format, accepted to ApJ; minor arithmetic error in previous version correcte

    Epigenetic regulation of F2RL3 associates with myocardial infarction and platelet function

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    DNA hypomethylation at the F2RL3 (F2R like thrombin or trypsin receptor 3) locus has been associated with both smoking and atherosclerotic cardiovascular disease; whether these smoking-related associations form a pathway to disease is unknown. F2RL3 encodes protease-activated receptor 4, a potent thrombin receptor expressed on platelets. Given the role of thrombin in platelet activation and the role of thrombus formation in myocardial infarction, alterations to this biological pathway could be important for ischemic cardiovascular disease. METHODS: We conducted multiple independent experiments to assess whether DNA hypomethylation at F2RL3 in response to smoking is associated with risk of myocardial infarction via changes to platelet reactivity. Using cohort data (N=3205), we explored the relationship between smoking, DNA hypomethylation at F2RL3, and myocardial infarction. We compared platelet reactivity in individuals with low versus high DNA methylation at F2RL3 (N=41). We used an in vitro model to explore the biological response of F2RL3 to cigarette smoke extract. Finally, a series of reporter constructs were used to investigate how differential methylation could impact F2RL3 gene expression. RESULTS: Observationally, DNA methylation at F2RL3 mediated an estimated 34% of the smoking effect on increased risk of myocardial infarction. An association between methylation group (low/high) and platelet reactivity was observed in response to PAR4 (protease-activated receptor 4) stimulation. In cells, cigarette smoke extract exposure was associated with a 4.9% to 9.3% reduction in DNA methylation at F2RL3 and a corresponding 1.7-(95% CI, 1.2–2.4, P=0.04) fold increase in F2RL3 mRNA. Results from reporter assays suggest the exon 2 region of F2RL3 may help control gene expression. CONCLUSIONS: Smoking-induced epigenetic DNA hypomethylation at F2RL3 appears to increase PAR4 expression with potential downstream consequences for platelet reactivity. Combined evidence here not only identifies F2RL3 DNA methylation as a possible contributory pathway from smoking to cardiovascular disease risk but from any feature potentially influencing F2RL3 regulation in a similar manner

    Additive manufacturing of multielectrode arrays for biotechnological applications

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    Multielectrode arrays (MEAs) are electrical devices that transduce (record/deliver) cellular voltage signals. Commercially available MEAs are expensive and here we provide proof of concept for the application of an additive manufacturing approach to prepare inexpensive MEAs and demonstrate their ability to interact with brain tissue ex vivo
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