857 research outputs found

    One-Dimensional Dynamic Modeling of the Lower Mississippi River

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    The Mississippi River (MR) has been engineered with the development of the levee system, dams for flood control measures, jetties, revetments and dredging of the navigation channel. These alterations have reduced the replenishment of the sediment to the Louisiana Coastal area. To aid in the restoration planning, 1-D numerical models have been calibrated and validated to predict the river response to various changes such as channel modifications, varied flow conditions and hurricane situations. This study utilized the HEC-RAS 4.1 and the CHARIMA (Dr. Forrest Holly, University of Iowa). The models were calibrated for hydrodynamics and sediment using Tarbert Landing discharges (HEC-RAS), Belle Chasse sand concentrations (CHARIMA), and Gulf of Mexico (GOM) stages. The models showed that a large percentage of the river flow is lost over the East Bank downstream of Bohemia which reduces the sand transport capacity of the river. This reach is subject to flow reversals during hurricanes

    Enabling Water-Energy–Food Nexus: a New Approach for Sustainable Agriculture and Food Security in Mountainous Landlocked Countries

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    Majority of landlocked mountainous countries are poorly ranked in Human Development Index (HDI), mostly due to poor per capita agriculture production, increasing population, unemployment, expensive and delayed transportation including several other factors. Generally, economy of such countries substantially relies on subsistence agriculture, tourism, hydropower and largely on remittance etc. Recently, it has been argued that to utilize scarce suitable land efficiently for food production, poor inland transport, hydropower, irrigation, drinking water in integration with other developmental infrastructures, an overarching policy linking water - energy – food nexus within a country for combating water, energy and food security would be most relevant. Thus, in present paper it has been opined that promotion of such linkage via nexus approach is the key to sustainable development of landlocked mountainous countries. Major land mass in mountainous countries like Nepal remains unsuitable for agriculture, road and other infrastructure profoundly imposing food, nutrition and energy security. However, large pristine snowy mountains function as wildlife sanctuaries, pastures, watershed, recharge areas for regional and global water, food and energy security. In return, landlocked mountainous countries are offered certain International leverages. For more judicious trade off, it is recommended that specific countries aerial coverage of mountains would be more appropriate basis for such leverages. Moreover, for sustainability of mountainous countries an integrated approach enabling water - energy – food nexus via watershed-hydropower-irrigation-aquaculture-agriculture-integrated linking policy model is proposed. This model would enable protection of watershed for pico, micro, and mega hydro power plants and tail waters to be used for aquaculture or irrigation or drinking water purposes for food and nutrition security

    Aspirin for prophylactic use in the primary prevention of cardiovascular disease and cancer : a systematic review and overview of reviews

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    Background: Prophylactic aspirin has been considered to be beneficial in reducing the risks of heart disease and cancer. However, potential benefits must be balanced against the possible harm from side effects, such as bleeding and gastrointestinal (GI) symptoms. It is particularly important to know the risk of side effects when aspirin is used as primary prevention - that is when used by people as yet free of, but at risk of developing, cardiovascular disease (CVD) or cancer. In this report we aim to identify and re-analyse randomised controlled trials (RCTs), systematic reviews and meta-analyses to summarise the current scientific evidence with a focus on possible harms of prophylactic aspirin in primary prevention of CVD and cancer. Objectives: To identify RCTs, systematic reviews and meta-analyses of RCTs of the prophylactic use of aspirin in primary prevention of CVD or cancer. To undertake a quality assessment of identified systematic reviews and meta-analyses using meta-analysis to investigate study-level effects on estimates of benefits and risks of adverse events; cumulative meta-analysis; exploratory multivariable meta-regression; and to quantify relative and absolute risks and benefits. Methods: We identified RCTs, meta-analyses and systematic reviews, and searched electronic bibliographic databases (from 2008 September 2012) including MEDLINE, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, NHS Centre for Reviews and Dissemination, and Science Citation Index. We limited searches to publications since 2008, based on timing of the most recent comprehensive systematic reviews. Results: In total, 2572 potentially relevant papers were identified and 27 met the inclusion criteria. Benefits of aspirin ranged from 6% reduction in relative risk (RR) for all-cause mortality [RR 0.94, 95% confidence interval (CI) 0.88 to 1.00] and 10% reduction in major cardiovascular events (MCEs) (RR 0.90, 95% CI 0.85 to 0.96) to a reduction in total coronary heart disease (CHD) of 15% (RR 0.85, 95% CI 0.69 to 1.06). Reported pooled odds ratios (ORs) for total cancer mortality ranged between 0.76 (95% CI 0.66 to 0.88) and 0.93 (95% CI 0.84 to 1.03). Inclusion of the Women's Health Study changed the estimated OR to 0.82 (95% CI 0.69 to 0.97). Aspirin reduced reported colorectal cancer (CRC) incidence (OR 0.66, 95% CI 0.90 to 1.02). However, including studies in which aspirin was given every other day raised the OR to 0.91 (95% CI 0.74 to 1.11). Reported cancer benefits appeared approximately 5 years from start of treatment. Calculation of absolute effects per 100,000 patient-years of follow-up showed reductions ranging from 33 to 46 deaths (all-cause mortality), 60-84 MCEs and 47-64 incidents of CHD and a possible avoidance of 34 deaths from CRC. Reported increased RRs of adverse events from aspirin use were 37% for GI bleeding (RR 1.37, 95% CI 1.15 to 1.62), between 54% (RR 1.54, 95% CI 1.30 to 1.82) and 62% (RR 1.62, 95% CI 1.31 to 2.00) for major bleeds, and between 32% (RR 1.32, 95% CI 1.00 to 1.74) and 38% (RR 1.38, 95% CI 1.01 to 1.82) for haemorrhagic stroke. Pooled estimates of increased RR for bleeding remained stable across trials conducted over several decades. Estimates of absolute rates of harm from aspirin use, per 100,000 patient-years of follow-up, were 99-178 for non-trivial bleeds, 46-49 for major bleeds, 68-117 for GI bleeds and 8-10 for haemorrhagic stroke. Meta-analyses aimed at judging risk of bleed according to sex and in individuals with diabetes were insufficiently powered for firm conclusions to be drawn. Limitations: Searches were date limited to 2008 because of the intense interest that this subject has generated and the cataloguing of all primary research in so many previous systematic reviews. A further limitation was our potential over-reliance on study-level systematic reviews in which the person-years of follow-up were not accurately ascertainable. However, estimates of number of events averted or incurred through aspirin use calculated from data in study-level meta-analyses did not differ substantially from estimates based on individual patient data-level meta-analyses, for which person-years of follow-up were more accurate (although based on less-than-complete assemblies of currently available primary studies). Conclusions: We have found that there is a fine balance between benefits and risks from regular aspirin use in primary prevention of CVD. Effects on cancer prevention have a long lead time and are at present reliant on post hoc analyses. All absolute effects are relatively small compared with the burden of these diseases. Several potentially relevant ongoing trials will be completed between 2013 and 2019, which may clarify the extent of benefit of aspirin in reducing cancer incidence and mortality. Future research considerations include expanding the use of IPD meta-analysis of RCTs by pooling data from available studies and investigating the impact of different dose regimens on cardiovascular and cancer outcomes

    Learning in Multi-Agent Information Systems - A Survey from IS Perspective

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    Multiagent systems (MAS), long studied in artificial intelligence, have recently become popular in mainstream IS research. This resurgence in MAS research can be attributed to two phenomena: the spread of concurrent and distributed computing with the advent of the web; and a deeper integration of computing into organizations and the lives of people, which has led to increasing collaborations among large collections of interacting people and large groups of interacting machines. However, it is next to impossible to correctly and completely specify these systems a priori, especially in complex environments. The only feasible way of coping with this problem is to endow the agents with learning, i.e., an ability to improve their individual and/or system performance with time. Learning in MAS has therefore become one of the important areas of research within MAS. In this paper we present a survey of important contributions made by IS researchers to the field of learning in MAS, and present directions for future research in this area

    Aspirin in primary prevention of cardiovascular disease and cancer : a systematic review of the balance of evidence from reviews of randomized trials

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    Background: Aspirin has been recommended for primary prevention of cardiovascular disease (CVD) and cancer, but overall benefits are unclear. We aimed to use novel methods to re-evaluate the balance of benefits and harms of aspirin using evidence from randomised controlled trials, systematic reviews and meta-analyses. Methods and Findings: Data sources included ten electronic bibliographic databases, contact with experts, and scrutiny of reference lists of included studies. Searches were undertaken in September 2012 and restricted to publications since 2008. Of 2,572 potentially relevant papers 27 met the inclusion criteria. Meta-analysis of control arms to estimate event rates, modelling of all-cause mortality and L'Abbé plots to estimate heterogeneity were undertaken. Absolute benefits and harms were low: 60-84 major CVD events and 34-36 colorectal cancer deaths per 100,000 person-years were averted, whereas 46-49 major bleeds and 68-117 gastrointestinal bleeds were incurred. Reductions in all-cause mortality were minor and uncertain (Hazard Ratio 0.96; 95% CI: 0.90-1.02 at 20 years, Relative Risk [RR] 0.94, 95% CI: 0.88-1.00 at 8 years); there was a non-significant change in total CVD (RR 0.85, 95% CI: 0.69-1.06) and change in total cancer mortality ranged from 0.76 (95% CI: 0.66-0.88) to 0.93 (95% CI: 0.84-1.03) depending on follow-up time and studies included. Risks were increased by 37% for gastrointestinal bleeds (RR 1.37, 95% CI: 1.15-1.62), 54%-66% for major bleeds (Rate Ratio from IPD analysis 1.54, 95% CI: 1.30-1.82, and RR 1.62, 95% CI: 1.31-2.00), and 32%-38% for haemorrhagic stroke (Rate Ratio from IPD analysis 1.32; 95% CI: 1.00-1.74; RR 1.38; 95% CI: 1.01-1.82). Conclusions: Findings indicate small absolute effects of aspirin relative to the burden of these diseases. When aspirin is used for primary prevention of CVD the absolute harms exceed the benefits. Estimates of cancer benefit rely on selective retrospective re-analysis of RCTs and more information is needed

    Photocurrent Calculations in Semiconductors using Kronig-Penney Model

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    Optical Studies of Zero-Field Magnetization of CdMnTe Quantum Dots: Influence of Average Size and Composition of Quantum Dots

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    We show that through the resonant optical excitation of spin-polarized excitons into CdMnTe magnetic quantum dots, we can induce a macroscopic magnetization of the Mn impurities. We observe very broad (4 meV linewidth) emission lines of single dots, which are consistent with the formation of strongly confined exciton magnetic polarons. Therefore we attribute the optically induced magnetization of the magnetic dots results to the formation of spin-polarized exciton magnetic polarons. We find that the photo-induced magnetization of magnetic polarons is weaker for larger dots which emit at lower energies within the QD distribution. We also show that the photo-induced magnetization is stronger for quantum dots with lower Mn concentration, which we ascribe to weaker Mn-Mn interaction between the nearest neighbors within the dots. Due to particular stability of the exciton magnetic polarons in QDs, where the localization of the electrons and holes is comparable to the magnetic exchange interaction, this optically induced spin alignment persists to temperatures as high as 160 K.Comment: 26 pages, 7 figs - submitted for publicatio

    Sex Ratio at Birth: Where Did Our Female Fetus Go?

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    Objectives: The aim of the study was to determine the ratio of male to female gender at birth and compare the sex ratio between primipara and multipara women. Methods: This is a cross sectional retrospective study done using the data available from the medical records of the patients who were admitted in the labor room of Gandaki Medical College Teaching Hospital from July 2016 to June 2017 (Shrawan 2073 to Asad 2074). Results: In one year period, a total of 1625 women were admitted for delivery. There were 845 male and 780 female babies delivered to those women. The sex ratio calculated was 108 male births for every 100 females. When comparing the sex ratios at birth for primipara, multipara with previous abortions and fetal death and mulipara with no history of abortions and fetal death, the sex ratio was 81.75, 125.89 and 120.16 respectively. Conclusions: Overall there were more male births than female. But in primiparous women more female babies were born unlike in multipara. There is definitely a need of in depth study to identify the cause for the skewed value. The society needs to acknowledge that high sex ratios at birth will adversely affect the fertility patterns causing the imbalance in the overall development of community.  J-GMC-N | Volume 11 | Issue 01 | January-June 2018, Page: 1-
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