715 research outputs found

    Electron gyroscale fluctuation measurements in National Spherical Torus Experiment H-mode plasmas

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    A collective scattering system has measured electron gyroscale fluctuations in National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000)] H-mode plasmas to investigate electron temperature gradient (ETG) turbulence. Observations and results pertaining to fluctuation measurements in ETG-stable regimes, the toroidal field scaling of fluctuation amplitudes, the relation between fluctuation amplitudes and transport quantities, and fluctuation magnitudes and k-spectra are presented. Collectively, the measurements provide insight and guidance for understanding ETG turbulence and anomalous electron thermal transport. (C) 2009 American Institute of Physics. [doi:10.1063/1.3262530]X116sciescopu

    Short-scale turbulent fluctuations driven by the electron-temperature gradient in the national spherical torus experiment

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    Measurements with coherent scattering of electromagnetic waves in plasmas of the National Spherical Torus Experiment indicate the existence of turbulent fluctuations in the range of wave numbers k(perpendicular to)rho(e)=0.1-0.4, corresponding to a turbulence scale length nearly equal to the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.X1155sciescopu

    Observations of Reduced Electron Gyroscale Fluctuations in National Spherical Torus Experiment H-Mode Plasmas with Large E X B Flow Shear

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    Electron gyroscale fluctuation measurements in National Spherical Torus Experiment H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temperature gradient (ETG) turbulence. Large toroidal rotation in National Spherical Torus Experiment plasmas with neutral beam injection generates ExB flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the ExB flow shear rate exceeds ETG linear growth rates. The observations indicate that ExB flow shear can be an effective suppression mechanism for ETG turbulence.X1129sciescopu

    Internal transport barriers in the National Spherical Torus Experiment

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    In the National Spherical Torus Experiment [M. Ono , Nucl. Fusion 41, 1435 (2001)], internal transport barriers (ITBs) are observed in reversed (negative) shear discharges where diffusivities for electron and ion thermal channels and momentum are reduced. While neutral beam heating can produce ITBs in both electron and ion channels, high harmonic fast wave heating can also produce electron ITBs (e-ITBs) under reversed magnetic shear conditions without momentum input. Interestingly, the location of the e-ITB does not necessarily match that of the ion ITB (i-ITB). The e-ITB location correlates best with the magnetic shear minima location determined by motional Stark effect constrained equilibria, whereas the i-ITB location better correlates with the location of maximum ExB shearing rate. Measured electron temperature gradients in the e-ITB can exceed critical gradients for the onset of electron thermal gradient microinstabilities calculated by linear gyrokinetic codes. A high-k microwave scattering diagnostic shows locally reduced density fluctuations at wave numbers characteristic of electron turbulence for discharges with strongly negative magnetic shear versus weakly negative or positive magnetic shear. Reductions in fluctuation amplitude are found to be correlated with the local value of magnetic shear. These results are consistent with nonlinear gyrokinetic simulations predicting a reduction in electron turbulence under negative magnetic shear conditions despite exceeding critical gradients.X1128sciescopu

    Serotonin transporter binding of [123I]ADAM in bulimic women, their healthy twin sisters, and healthy women: a SPET study

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    <p>Abstract</p> <p>Background</p> <p>Bulimia Nervosa (BN) is believed to be caused by an interaction of genetic and environmental factors. Previous studies support the existence of a bulimia-related endophenotype as well as disturbances in serotonin (5-HT) transmission. We studied serotonin transporter (SERT) binding in BN, and to investigate the possibility of a SERT-related endophenotype for BN, did this in a sample of female twins. We hypothesized clearly reduced SERT binding in BN women as opposed to healthy women, and intermediate SERT binding in unaffected co-twins.</p> <p>Methods</p> <p>We studied 13 female twins with BN (9 with purging and 4 with non-purging BN) and 25 healthy women, including 6 healthy twin sisters of BN patients and 19 women from 10 healthy twin pairs. [<sup>123</sup>I]ADAM, a selective SERT radioligand for single photon emission tomography (SPET) imaging, was used to assess SERT availability in the midbrain and the thalamus.</p> <p>Results</p> <p>No differences in SERT binding were evident when comparing the BN women, their unaffected co-twins and the healthy controls (p = 0.14). The healthy sisters of the BN patients and the healthy control women had similar SERT binding in both brain regions. In a <it>post hoc </it>subgroup analysis, the purging bulimics had higher SERT binding than the healthy women in the midbrain (p = 0.03), but not in the thalamus.</p> <p>Conclusion</p> <p>Our finding of increased SERT binding in the midbrain in the purging BN women raises the possibility that this subgroup of bulimics might differ in serotonergic function from the non-purging ones. The similarity of the unaffected co-twins and the healthy controls doesn't support our initial assumption of a SERT-related endophenotype for BN. Due to the small sample size, our results need to be interpreted with caution and verified in a larger sample.</p

    Zinc intake, status and indices of cognitive function in adults and children: a systematic review and meta-analysis

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    In developing countries, deficiencies of micronutrients are thought to have a major impact on child development; however, a consensus on the specific relationship between dietary zinc intake and cognitive function remains elusive. The aim of this systematic review was to examine the relationship between zinc intake, status and indices of cognitive function in children and adults. A systematic literature search was conducted using EMBASE, MEDLINE and Cochrane Library databases from inception to March 2014. Included studies were those that supplied zinc as supplements or measured dietary zinc intake. A meta-analysis of the extracted data was performed where sufficient data were available. Of all of the potentially relevant papers, 18 studies met the inclusion criteria, 12 of which were randomised controlled trials (RCTs; 11 in children and 1 in adults) and 6 were observational studies (2 in children and 4 in adults). Nine of the 18 studies reported a positive association between zinc intake or status with one or more measure of cognitive function. Meta-analysis of data from the adult’s studies was not possible because of limited number of studies. A meta-analysis of data from the six RCTs conducted in children revealed that there was no significant overall effect of zinc intake on any indices of cognitive function: intelligence, standard mean difference of <0.001 (95% confidence interval (CI) –0.12, 0.13) P=0.95; executive function, standard mean difference of 0.08 (95% CI, –0.06, 022) P=0.26; and motor skills standard mean difference of 0.11 (95% CI –0.17, 0.39) P=0.43. Heterogeneity in the study designs was a major limitation, hence only a small number (n=6) of studies could be included in the meta-analyses. Meta-analysis failed to show a significant effect of zinc supplementation on cognitive functioning in children though, taken as a whole, there were some small indicators of improvement on aspects of executive function and motor development following supplementation but high-quality RCTs are necessary to investigate this further

    Ethical implications of the use of whole genome methods in medical research

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    The use of genome-wide association studies (GWAS) in medical research and the increased ability to share data give a new twist to some of the perennial ethical issues associated with genomic research. GWAS create particular challenges because they produce fine, detailed, genotype information at high resolution, and the results of more focused studies can potentially be used to determine genetic variation for a wide range of conditions and traits. The information from a GWA scan is derived from DNA that is a powerful personal identifier, and can provide information not just on the individual, but also on the individual's relatives, related groups, and populations. Furthermore, it creates large amounts of individual-specific digital information that is easy to share across international borders. This paper provides an overview of some of the key ethical issues around GWAS: consent, feedback of results, privacy, and the governance of research. Many of the questions that lie ahead of us in terms of the next generation sequencing methods will have been foreshadowed by GWAS and the debates around ethical and policy issues that these have created

    Male involvement in birth preparedness and complication readiness for emergency obstetric referrals in rural Uganda

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    <p>Abstract</p> <p>Background</p> <p>Every pregnant woman faces risk of life-threatening obstetric complications. A birth-preparedness package promotes active preparation and assists in decision-making for healthcare seeking in case of such complications. The aim was to assess factors associated with birth preparedness and complication-readiness as well as the level of male participation in the birth plan among emergency obstetric referrals in rural Uganda.</p> <p>Methods</p> <p>This was a cross-sectional study conducted at Kabale regional hospital maternity ward among 140 women admitted as emergency obstetric referrals in antenatal, labor or the postpartum period. Data was collected on socio-demographics and birth preparedness and what roles spouses were involved in during developing the birth plan. Any woman who attended antenatal care at least 4 times, received health education on pregnancy and childbirth danger signs, saved money for emergencies, made a plan of where to deliver from and made preparations for a birth companion, was deemed as having made a birth plan. Multivariate logistic regression analysis was conducted to analyze factors that were independently associated with having a birth plan.</p> <p>Results</p> <p>The mean age was 26.8 ± 6.6 years, while mean age of the spouse was 32.8 ± 8.3 years. Over 100 (73.8%) women and 75 (55.2%) of their spouses had no formal education or only primary level of education respectively. On multivariable analysis, Primigravidae compared to multigravidae, OR 1.8 95%CI (1.0-3.0), education level of spouse of secondary or higher versus primary level or none, OR 3.8 95%CI (1.2-11.0), formal occupation versus informal occupation of spouse, OR 1.6 95%CI (1.1-2.5), presence of pregnancy complications OR 1.4 95%CI (1.1-2.0) and the anticipated mode of delivery of caesarean section versus vaginal delivery, OR 1.6 95%CI (1.0-2.4) were associated with having a birth plan.</p> <p>Conclusion</p> <p>Individual women, families and communities need to be empowered to contribute positively to making pregnancy safer by making a birth plan.</p

    Herbal medicine use by surgery patients in Hungary: a descriptive study

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    BACKGROUND: The popularity of non-conventional treatments, especially the consumption of herbs is showing an increasing tendency all over the world. The consumption of herbal medicines might cause several complications during perioperative care. METHODS: The survey was conducted at the First Department of Surgery of Semmelweis University and focused on the demographics of patients consuming herbal medicines who had undergone elective surgery between July 1(st) 2014 and February 28(th) 2015. A one-page questionnaire, that the patients filled in individually and anonymously, was used. The response rate was 17.3 %. RESULTS: Out of the 390 patients who filled in the questionnaire, 7.2 % (28 patients) used herbal medicines, 3.6 % (14 patients) of them two weeks prior to their hospitalization. The other 3.6 % (14 patients) took herbal medicines sometime in the past. The majority of those who have ever consumed herbs are women (18/28), have completed secondary or tertiary education (23/28), more than half of them suffer from tumorous diseases and only a quarter of them (7/28) informed their physician about their use of herbal medication of their own accord. CONCLUSIONS: Attention must be paid to the exploration of herb consumption habits of surgery patients during the preoperative examinations in order to avoid potential side effects, complications or drug interactions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12906-015-0890-2) contains supplementary material, which is available to authorized users

    Assessing community perspectives of the community based education and service model at Makerere University, Uganda: a qualitative evaluation

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    <p>Abstract</p> <p>Background</p> <p>Community partnerships are defined as groups working together with shared goals, responsibilities, and power to improve the community. There is growing evidence that these partnerships contribute to the success and sustainability of community-based education and service programs (COBES), facilitating change in community actions and attitudes. Makerere University College of Health Sciences (MakCHS) is forging itself as a transformational institution in Uganda and the region. The College is motivated to improve the health of Ugandans through innovative responsive teaching, provision of service, and community partnerships. Evaluating the COBES program from the community perspective can assist the College in refining an innovative and useful model that has potential to improve the health of Ugandans.</p> <p>Methods</p> <p>A stratified random sample of 11 COBES sites was selected to examine the community’s perception of the program. Key Informant Interviews of 11 site tutors and 33 community members were completed. The data was manually analyzed and themes developed.</p> <p>Results</p> <p>Communities stated the students consistently engaged with them with culturally appropriate behaviour. They rated the student’s communication as very good even though translators were frequently needed. Half the community stated they received some feedback from the students, but some communities interpreted any contact after the initial visit as feedback. Communities confirmed and appreciated that the students provided a number of interventions and saw positive changes in health and health seeking behaviours. The community reflected that some programs were more sustainable than others; the projects that needed money to implement were least sustainable. The major challenges from the community included community fatigue, and poor motivation of community leaders to continue to take students without compensation.</p> <p>Conclusions</p> <p>Communities hosting Makerere students valued the students’ interventions and the COBES model. They reported witnessing health benefits of fewer cases of disease, increased health seeking behavior and sustainable healthcare programs. The evidence suggests that efforts to standardize objectives, implement structural adjustments, and invest in development of the program would yield even more productive community interactions and a healthcare workforce with public health skills needed to work in rural communities.</p
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