7,748 research outputs found
Using a Gridded Global Dataset to Characterize Regional Hydroclimate in Central Chile
Central Chile is facing dramatic projections of climate change, with a consensus for declining precipitation, negatively affecting hydropower generation and irrigated agriculture. Rising from sea level to 6000 m within a distance of 200 km, precipitation characterization is difficult because of a lack of long-term observations, especially at higher elevations. For understanding current mean and extreme conditions and recent hydroclimatological change, as well as to provide a baseline for downscaling climate model projections, a temporally and spatially complete dataset of daily meteorology is essential. The authors use a gridded global daily meteorological dataset at 0.25° resolution for the period 1948â2008, adjusted by monthly precipitation observations interpolated to the same grid using a cokriging method with elevation as a covariate. For validation, daily statistics of the adjusted gridded precipitation are compared to station observations. For further validation, a hydrology model is driven with the gridded 0.25° meteorology and streamflow statistics are compared with observed flow. The high elevation precipitation is validated by comparing the simulated snow extent to Moderate Resolution Imaging Spectroradiometer (MODIS) images. Results show that the daily meteorology with the adjusted precipitation can accurately capture the statistical properties of extreme events as well as the sequence of wet and dry events, with hydrological model results displaying reasonable agreement with observed streamflow and snow extent. This demonstrates the successful use of a global gridded data product in a relatively data-sparse region to capture hydroclimatological characteristics and extremes
Kink-induced symmetry breaking patterns in brane-world SU(3)^3 trinification models
The trinification grand unified theory (GUT) has gauge group SU(3)^3 and a
discrete symmetry permuting the SU(3) factors. In common with other GUTs, the
attractive nature of the fermionic multiplet assignments is obviated by the
complicated multi-parameter Higgs potential apparently needed for
phenomenological reasons, and also by vacuum expectation value (VEV)
hierarchies within a given multiplet. This motivates the rigorous consideration
of Higgs potentials, symmetry breaking patterns and alternative symmetry
breaking mechanisms in models with this gauge group. Specifically, we study the
recently proposed ``clash of symmetries'' brane-world mechanism to see if it
can help with the symmetry breaking conundrum. This requires a detailed
analysis of Higgs potential global minima and kink or domain wall solutions
interpolating between the disconnected global minima created through
spontaneous discrete symmetry breaking. Sufficiently long-lived metastable
kinks can also be considered. We develop what we think is an interesting,
albeit speculative, brane-world scheme whereby the hierarchical symmetry
breaking cascade, trinification to left-right symmetry to the standard model to
colour cross electromagnetism, may be induced without an initial hierarchy in
vacuum expectation values. Another motivation for this paper is simply to
continue the exploration of the rich class of kinks arising in models that are
invariant under both discrete and continuous symmetries.Comment: 12 pages, RevTex, references adde
On the complete digraphs which are simply disconnected
Homotopic methods are employed for the characterization of the complete digraphs which are the composition of non-trivial highly regular tournaments
Fostering Emotional, Social, Physical And Educational Wellbeing In Rural India: The Methods Of A Multi-Arm Randomized Controlled Trial Of Girls First
Background: There are 600 million girls in low and middle income countries (LMICs), many of whom are at great risk for poor health and education. There is thus great need for programs that can effectively improve wellbeing for these girls. Although many interventions have been developed to address these issues, most focus on health and education without integrating attention to social and emotional factors. This omission is unfortunate, as nascent evidence indicates that these factors are closely related to health and education. This paper describes the methods of a 4-arm randomized controlled trial among 3,560 adolescent girls in rural Bihar, India that tested whether adding an intervention targeting social-emotional issues (based on a âresilience frameworkâ) to an adolescent health intervention would improve emotional, social, physical, and educational wellbeing to a greater extent than its components and a control group. Study arms were: (1) Girls First, a combination of the Girls First Resilience Curriculum (RC) and the Girls First Health Curriculum (HC); (2) Girls First Resilience Curriculum (RC) alone; (3) Girls First Health Curriculum (HC) alone; and (4) a school-as-usual control group (SC). Methods: Seventy-six schools were randomized (19 per condition) and 74 local women with a tenth grade education were trained and monitored to facilitate the program. Quantitative data were collected from 3,560 girls over 4 assessment points with very low rates of participant attrition. Qualitative assessments were conducted with a subset of 99 girls and 27 facilitators. Results and conclusions: In this article, we discuss guiding principles that facilitated trial implementation, including integrating diverse local and non-local sources of knowledge, focusing on flexibility of planning and implementation, prioritizing systematic measurement selection, and striking a balance between scientific rigor and real-world feasibility
Building Psychosocial Assets And Wellbeing Among Adolescent Girls: A Randomized Controlled Trial
We conducted a randomized controlled trial of a 5-month resilience-based program (Girls First Resilience Curriculum or RC) among 2308 rural adolescent girls at 57 government schools in Bihar, India. Local women with at least a 10th grade education served as group facilitators. Girls receiving RC improved more (vs. controls) on emotional resilience, self-efficacy, social-emotional assets, psychological wellbeing, and social wellbeing. Effects were not detected on depression. There was a small, statistically significant negative effect on anxiety (though not likely clinically significant). Results suggest psychosocial assets and wellbeing can be improved for girls in high-poverty, rural schools through a brief school-day program. To our knowledge, this is one of the largest developing country trials of a resilience-based school-day curriculum for adolescents. (C) 2015 The Authors. Published by Elsevier Ltd on behalf of The Foundation for Professionals in Services for Adolescents. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Local control by radiotherapy: is that all there is?
Radiotherapy is a local treatment modality employed in breast cancer to reduce local recurrence following surgery. The observed association of optimal local control with improved survival was not expected in a disease characterized by early systemic spread. The underlying mechanisms whereby the application of ionizing radiation to the primary tumor site can have systemic effects remain unclear and are the subject of much debate. In the present article we discuss the hypothesis that radiotherapy has unique biological effects and that, in addition to killing residual neoplastic cells after surgery is performed, it might favorably alter the microenvironment at the primary tumor site during the process of wound healing and the development of antitumor immune responses
Training school teachers to promote mental and social well-being in low and middle income countries : lessons to facilitate scale-up from a participatory action research trial of youth first in India
Mental and social wellbeing (MSWB) promotion programs could improve mental health
and other outcomes for youth in Low and Middle Income Countries (LMICs).
Unfortunately, few such programs have progressed to scale-up and few studies have
detailed processes and considerations that could facilitate doing so. This study begins to
fill these gaps, describing key findings from training and supporting government middle
school teachers to deliver the Youth First Resilience Curriculum, a MSWB promotion
program, in Bihar, India. We conducted a Participatory Action Research trial of the
resilience curriculum among 792 middle school youth and 55 teachers at 15 government
schools. Participant-observations, exit interviews, and group discussions were conducted
and analyzed via multiple rounds of coding to generate thematic findings. A number of
schools showed relatively high levels of interest, session reliability and fidelity, student
interaction and teacher facilitative abilities, but there was great variation within the
sample. Three leverage points emerged to facilitate future scale-up: factors for successful
site assessment and program initiation, supporting teacher success via interest and
motivation, and responding to varied teacher skill levels. These points represent critical
focus areas for practitioners and policy-makers as more MSWB promotion programs
begin to scale in LMICs.peer-reviewe
Comparison of two- and three-dimensional echocardiography with cineventriculography for measurement of left ventricular volume in patients
AbstractObjectives. We compared two- and three-dimensional echocardiopaphy with cineventriculography for measurement of left ventricular volume in patients.Background. Three-dimensional echocardiography has been shown to be highly accurate and superior to two-dimensional echocardiography in measuring left ventricular volume in vitro. However, there has been little comparison of the two methods in patients.Methods. Two- and three-dimensional echocardiography were performed in 35 patients (mean age 48 years) 1 to 3 h before left ventricular cineventriculography. Three-dimensional echocardiography used an acoustic spatial locator to register image position. Volume was computed using a polyhedral surface reconstruction algorithm based on multiple nonparallel, unevenly spaced short-axis cross sections. Two-dimensional echocardiography used the apical biplane summation of disks method. Single-plane cineventriculographic volumes were calculated using the summation of disks algorithm. The methods were compared by linear regression and a limits of agreement analysis. For the latter, systematic error was assessed by the mean of the deferences (cineventriculography minus echocardiography), and the limits of agreement were defined as ±2 SD from the mean difference.Results. Three-dimensional echocardiographic volumes demonstrated excellent correlation (end-diastole r = 0.97; end-systole r = 0.98) with cineventriculography. Standard errors of the estimate were approximately half those of two-dimensional echocardiography (end-diastole ±11.0 ml vs. ±21.5 ml; end-systole ±10.2 ml vs. ±17.0 ml). By limits of agreement analysis the end-diastolic mean diferences for two- and three-dimensional echocardiography were 21.1 and 12.9 ml, respectively. The limits of agreement (±2 SD) were ±54.0 and ±24.8 ml, respectively. For end-systole, comparable improvement was obtained by three-dimensional echocardiography. Results for ejection fraction by the two methods were similar.Conclusions. Three-dimensional echocardiography correlates highly with cineventriculography for estimation of ventricular volumes in patients and has approximately half the variability of two-dimensional echocardiography for these measurements. On the basis of this study, three-dimensional echocardiography is the preferred echocardiographic technique for measurement of ventricular volume. Three-dimensional echocardiography is equivalent to two-dimensional echocardiography for measuring ejection fraction
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