13,902 research outputs found

    Selectivity in regeneration of the oculomotor nerve in the cichlid fish, Astronotus ocellatus

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    It has long been considered a general rule for nerve regeneration that the reinnervation of skeletal muscle is nonselective. Regenerating nerve fibers are supposed to reconnect with one skeletal muscle as readily as another according to studies covering a wide range of vertebrates (Weiss, 1937; Weiss & Taylor, 1944; Weiss & Hoag, 1946; Bernstein & Guth, 1961; Guth, 1961, 1962, 1963). Similarly, in embryogenesis proper functional connexions between nerve centers and particular muscles are supposedly attained, not by selective nerve outgrowth but rather through a process of ‘myotypic modulation’ (Weiss, 1955) that presupposes nonselective peripheral innervation. Doubt about the general validity of this rule and the concepts behind it has come from a series of studies on regeneration of the oculomotor nerve in teleosts, urodeles, and anurans and of spinal fin nerves in teleosts (Sperry, 1946, 1947, 1950, 1965; Sperry & Deupree, 1956; Arora & Sperry, 1957a, 1964)

    X-ray CT analysis after blast of composite sandwich panels

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    Four composite sandwich panels with either single density or graded density foam cores and different face-sheet materials were subjected to full-scale underwater blast testing. The panels were subjected to 1kg PE4 charge at a stand-off distance of 1 m. The panel with graded density core and carbon fiber face-sheets had the lowest deflection. Post-blast damage assessment was carried out using X-ray CT scanning. The damage assessment revealed that there is a trade-off between reduced panel deflection and panel damage. This research has been performed as part of a program sponsored by the Office of Naval Research (ONR)

    Association of Breakfast Intake with Obesity, Dietary and Physical Activity Behavior Among Urban School-Aged Adolescents in Delhi, India: Results of a Cross-Sectional Study

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    In developed countries, regular breakfast consumption is inversely associated with excess weight and directly associated with better dietary and improved physical activity behaviors. Our objective was to describe the frequency of breakfast consumption among school-going adolescents in Delhi and evaluate its association with overweight and obesity as well as other dietary, physical activity, and sedentary behaviors. Methods: Design: Cross-sectional study. Setting: Eight schools (Private and Government) of Delhi in the year 2006. Participants: 1814 students from 8th and 10th grades; response rate was 87.2%; 55% were 8th graders, 60% were boys and 52% attended Private schools. Main outcome measures: Body mass index, self-reported breakfast consumption, diet and physical activity related behaviors, and psychosocial factors. Data analysis: Mixed effects regression models were employed, adjusting for age, gender, grade level and school type (SES). Results: Significantly more Government school (lower SES) students consumed breakfast daily as compared to Private school (higher SES) students (73.8% vs. 66.3%; p<0.01). More 8th graders consumed breakfast daily vs. 10th graders (72.3% vs. 67.0%; p<0.05). A dose-response relationship was observed such that overall prevalence of overweight and obesity among adolescents who consumed breakfast daily (14.6%) was significantly lower vs. those who only sometimes (15.2%) or never (22.9%) consumed breakfast (p<0.05 for trend). This relationship was statistically significant for boys (15.4 % vs. 16.5% vs. 26.0; p<0.05 for trend) but not for girls. Intake of dairy products, fruits and vegetables was 5.5 (95% CI 2.4-12.5), 1.7 (95% CI 1.1-2.5) and 2.2 (95% CI 1.3-3.5) times higher among those who consumed breakfast daily vs. those who never consumed breakfast. Breakfast consumption was associated with greater physical activity vs. those who never consumed breakfast. Positive values and beliefs about healthy eating; body image satisfaction; and positive peer and parental influence were positively associated with daily breakfast consumption, while depression was negatively associated. Conclusion: Daily breakfast consumption is associated with less overweight and obesity and with healthier dietary-and physical activity-related behaviors among urban Indian students. Although prospective studies should confirm the present results, intervention programs to prevent or treat childhood obesity in India should consider emphasizing regular breakfast consumption.Obesity Prevention Center, University of MinnesotaPRIME program of the University of Texas, School of Public Health (Stigler, PI)Center for Health Promotion and Disease Prevention Research in Underserved Population

    Electric Quadrupole Moments of Metastable States of Ca+, Sr+, and Ba+

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    Electric quadrupole moments of the metastable nd3/2 and nd5/2 states of Ca+, Sr+, and Ba+ are calculated using the relativistic all-order method including all single, double, and partial triple excitations of the Dirac-Hartree-Fock wave function to provide recommended values for the cases where no experimental data are available. The contributions of all non-linear single and double terms are also calculated for the case of Ca+ for comparison of our approach with the CCSD(T) results. The third-order many body perturbation theory is used to evaluate contributions of high partial waves and the Breit interaction. The remaining omitted correlation corrections are estimated as well. Extensive study of the uncertainty of our calculations is carried out to establish accuracy of our recommended values to be 0.5% - 1% depending on the particular ion. Comprehensive comparison of our results with other theoretical values and experiment is carried out. Our result for the quadrupole moment of the 3d5/2 state of Ca+ ion, 1.849(17)ea_0^2, is in agreement with the most precise recent measurement 1.83(1)ea_0^2 by Roos et al. [Nature 443, 316 (2006)].Comment: 7 page

    Surface optical Raman modes in InN nanostructures

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    Raman spectroscopic investigations are carried out on one-dimensional nanostructures of InN,such as nanowires and nanobelts synthesized by chemical vapor deposition. In addition to the optical phonons allowed by symmetry; A1, E1 and E2(high) modes, two additional Raman peaks are observed around 528 cm-1 and 560 cm-1 for these nanostructures. Calculations for the frequencies of surface optical (SO) phonon modes in InN nanostructures yield values close to those of the new Raman modes. A possible reason for large intensities for SO modes in these nanostructures is also discussed.Comment: 13 pages, 4 figures, Submitted in Journa

    State-insensitive trapping of Rb atoms: linearly versus circularly polarized lights

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    We study the cancellation of differential ac Stark shifts in the 5s and 5p states of rubidium atom using the linearly and circularly polarized lights by calculating their dynamic polarizabilities. Matrix elements were calculated using a relativistic coupled-cluster method at the single, double and important valence triple excitations approximation including all possible non-linear correlation terms. Some of the important matrix elements were further optimized using the experimental results available for the lifetimes and static polarizabilities of atomic states. "Magic wavelengths" are determined from the differential Stark shifts and results for the linearly polarized light are compared with the previously available results. Possible scope of facilitating state-insensitive optical trapping schemes using the magic wavelengths for circularly polarized light are discussed. Using the optimized matrix elements, the lifetimes of the 4d and 6s states of this atom are ameliorated.Comment: 13 pages, 13 tables and 4 figure

    Evaluating Primary Blast Effects In Vitro

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    Exposure to blast events can cause severe trauma to vital organs such as the lungs, ears, and brain. Understanding the mechanisms behind such blast-induced injuries is of great importance considering the recent trend towards the use of explosives in modern warfare and terrorist related incidents. To fully understand blast-induced injury, we must first be able to replicate such blast events in a controlled environment using a reproducible method. In this technique using shock tube equipment, shock waves at a range of pressures can be propagated over live cells grown in 2D, and markers of cell viability can be immediately analyzed using a redox indicator assay and the fluorescent imaging of live and dead cells. This method demonstrated that increasing the peak blast overpressure to 127 kPa can stimulate a significant drop in cell viability when compared to untreated controls. Test samples are not limited to adherent cells, but can include cell suspensions, whole-body and tissue samples, through minor modifications to the shock tube setup. Replicating the exact conditions that tissues and cells experience when exposed to a genuine blast event is difficult. Techniques such as the one presented in this article can help to define damage thresholds and identify the transcriptional and epigenetic changes within cells that arise from shock wave exposure

    The practical feasibility of using RFID in a metal environment

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    Passive Radio Frequency Identification (RFID) has revolutionized the way in which products are identified. This paper considers the effect of metals on the performance of RFID at ultra high frequency (UHF). The paper establishes read patterns in space, highlighting the interference of RF waves due to three different metals, one ferrous and the other two non ferrous, when placed behind a transponder. The effect of thickness of the metal plate is also examined. Different metals have been found to have different interference effects although there are some similarities in their read patterns related to their material properties. Also experiments have been carried out to identify and establish various methods of improving this performance. Finally, differences between performance-measuring parameters, namely attenuating transmitted power and calculating read rate at a fixed attenuation are established and possible reasons of these observations are presented

    A study on knowledge attitude and practices related to hepatitis B infection among nursing students of government nursing college, Jagdalpur, Bastar, Chhattisgarh

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    Background: Hepatitis-B virus is a potentially critical and familiar occupational hazard for health care workers including nursing students particularly those who are exposed to the populations whose HBsAg prevalence is high.The aim of the study was to assess the Hepatitis-B - knowledge, perception and vaccination status among nursing students.Methods: A cross-sectional study was conducted by Department of Community Medicine, Government Medical College, Jagdalpur, Chhattisgarh in July 2016, among nursing students of Government Nursing College, Jagdalpur, Chhattisgarh. Using purposive sampling data was collected via a pre-tested self- administered questionnaire. Overall 218 nursing students participated in the study. Statistical analysis was done using Stata version 12.1. Chi square test was used to identify any statistically significant difference among the nursing batches.Results: The study found that only 18.9% of the 1st year students are vaccinated. Knowledge regarding treatment options was found out to be significantly (p&lt;0.05) low among all nursing batches.Conclusions: There is lack of knowledge among all students regarding its treatment. Only 18.97% of the 1st year students reported to be vaccinated which puts them at a greater risk of acquiring the infection in future. Therefore, it is recommended that they should get themselves vaccinated before entering clinical rotations. More studies should b econducted on nursing/ medical staff to assess their knowledge on Hepatitis B infection in tribal areas which have high prevalence
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