1,542 research outputs found

    Parameter Estimation for Log-Pearson Type III Distribution by Pome

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    The principle of maximum entropy (POME) is employed to derive an alternative method of parameter estimation for the log-Pearson type (LPT) III distribution. Historical flood data are used to evaluate this method and compare it with the methods of moments (MOM) and maximum likelihood estimation (MLE). The parameter estimates yielded by POME are comparable to those by MOM and MLE

    A NARRATIVE REVIEW ON DEFINING AGING: A MULTIDISCIPLINARY REVIEW OF BIOLOGICAL, PSYCHOLOGICAL, SOCIOLOGICAL, AND CLINICAL PERSPECTIVES WITH A FOCUS ON SUCCESSFUL AGING.

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    Aging is a complex, multifaceted process affecting every living organism, characterized by progressive physiological changes, functional decline, and increased susceptibility to diseases and death. As the global population continues to age, understanding and defining aging becomes increasingly important for healthcare, policy-making, and social support systems. The review aims to explore and synthesize various definitions of aging, including biological, psychological, sociological, and clinical perspectives, and to examine the concept of successful aging. The review identifies distinct definitions of aging across different disciplines, highlighting the multifaceted nature of the idea. Biological aging involves cellular senescence, genetic theories, and damage accumulation. Psychological aging encompasses cognitive changes and emotional regulation, while sociological aging focuses on social roles and cultural attitudes. Clinical aging addresses the decline in physical and mental health and the emergence of geriatric syndromes. The maintenance of physical health, mental well-being, social engagement, and productive activities defines successful aging. Factors influencing successful aging include genetics, lifestyle choices, social support, and access to healthcare. Understanding the various definitions of aging is crucial for advancing research, developing effective interventions, and shaping policies that support healthy aging. Future research should explore the interplay between genetic, environmental, and social determinants of aging, and promote societal attitudes that value and support older adults. Insights from this review can inform the design of clinical programs and policies aimed at enhancing the quality of life for older adults. Emphasizing preventive measures, health promotion, and social support can help mitigate the negative impacts of aging and promote successful aging across populations

    Full-Range Approximation for the Theis Well Function Using Ramanujan's Series and Bounds for the Exponential Integral

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    The solution of the governing equation representing the drawdown in a horizontal confined aquifer, where groundwater flow is unsteady, is provided in terms of the exponential integral, which is famously known as the Well function. For the computation of this function in practical applications, it is important to develop not only accurate but also a simple approximation that requires evaluation of the fewest possible terms. To that end, introducing Ramanujan's series expression, this work proposes a full-range approximation to the exponential integral using Ramanujan's series for the small argument (u \leq 1) and an approximation based on the bound of the integral for the other range (u \in (1,100]). The evaluation of the proposed approximation results in the most accurate formulae compared to the existing studies, which possess the maximum percentage error of 0.05\%. Further, the proposed formula is much simpler to apply as it contains just the product of exponential and logarithm functions. To further check the efficiency of the proposed approximation, we consider a practical example for evaluating the discrete pumping kernel, which shows the superiority of this approximation over the others. Finally, the authors hope that the proposed efficient approximation can be useful for groundwater and hydrogeological applications.Comment: 10 page

    Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact

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    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell\u27s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. This work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process

    Multimodel regression-sampling algorithm for generating rich monthly streamflow scenarios

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    This paper presents a multimodel regression-sampling algorithm (MRS) for monthly streamflow simulation. MRS is motivated from the acknowledgment that typical nonparametric models tend to simulate sequences exhibiting too close a resemblance to historical records and parametric models have limitations in capturing complex distributional and dependence characteristics, such as multimodality and nonlinear autocorrelation. The aim of MRS is to generate streamflow sequences with rich scenarios while properly capturing complex distributional and dependence characteristics. The basic assumptions of MRS include: (1) streamflow of a given month depends on a feature vector consisting of streamflow of the previous month and the dynamic aggregated flow of the past 12 months and (2) streamflow can be multiplicatively decomposed into a deterministic expectation term and a random residual term. Given a current feature vector, MRS first relates the conditional expectation to the feature vector through an ensemble average of multiple regression models. To infer the conditional distribution of the residual, MRS adopts the k-nearest neighbor concept. More precisely, the conditional distribution is estimated by a gamma kernel smoothed density of historical residuals inside the k-neighborhood of the given feature vector. Rather than obtaining the residuals from the averaged model only, MRS retains all residuals from all the original regression models. In other words, MRS perceives that the original residuals put together would better represent the covariance structure between streamflow and the feature vector. By doing so, the benefit is that a kernel smoothed density of the residual with reliable accuracy can be estimated, which is hardly possible in a single-model framework. It is the smoothed density that ensures the generation of sequences with rich scenarios unseen in historical record. We evaluated MRS at selected stream gauges and compared with several existing models. Results show that (1) compared with typical nonparametric models, MRS is more apt at generating sequences with richer scenarios and (2) in contrast to parametric models, MRS can reproduce complex distributional and dependence characteristics. Since MRS is flexible at incorporating different covariates, it can be tailored for other potential applications, such as hydrologic forecasting, downscaling, as well as postprocessing deterministic forecasts into probabilistic ones

    Encyclopedia of Snow, Ice and Glaciers

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    The objective of this encyclopedia is to present the current state of scientific understanding of various aspects of earth’s cryosphere – snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost – and their related interdisciplinary connections under one umbrella. Therefore, every effort has been made to provide a comprehensive coverage of cryosphere by including a broad array of topics, such as the atmospheric processes responsible for snow formation; snowfall observations; snow cover and snow surveys; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide distribution; glaciation and ice ages; glacier dynamics; glacier surface and subsurface characteristics; geomorphic processes and landscape formation; hydrology and sedimentary systems; hydrochemical and isotopic properties; permafrost modeling; hazards caused by cryospheric changes; trends of glacier retreat on a global scale along with the impact of climate change; and many more quantitative estimates of various glacier parameters, such as degree-day, mass balance, extent and volume, and downwasting. Also included are articles on GPS application, and satellite image application in glaciology; GPR analysis; and sea level rise

    A Look at 20th Century Droughts

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    Droughts exercise a profound effect on the social and economic fabric of nations. Many nations of the world experienced droughts encompassing the full spectrum of severity, areal extent and duration. The result has been that the economic development was hampered and many countries have not yet recouped fully from the ravages of droughts. The first decade of the 21st century has also witnessed varying degrees of droughts across the globe. Therefore, we ask the following questions: (a) Do droughts affect every part of the world? (b) Are there similarities in major droughts around the world? (c) Are climate change and global warming impacting drought occurrences? (d) How much impact do droughts have on water resources? (e) What can be said about food security, energy security and water security? (f) What do different Global Climate Models (GCMs) and the IPCC report say about future drought scenarios? (g) How can our understanding of past drought episodes help with planning and managing future water resources

    AFFECT OF FATIGUE ON ACTIVATION STRATEGY OF MUSCLES: SEMG STUDY

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    This research aims to identify the neuromotor changes in muscles associated with fatigue during sprint cycling among 11 recreational cyclists who performed the WAT of 30s. The paper reports experiments conducted where changes in muscle recruitment strategies were studied using multiple recordings of SEMG of lower limb muscles and load was kept constant It is observed that near the end of such an exercise, there is a delay in activation / deactivation of the muscles. This causes the agonist muscles to do negative work during the upward part of the pedal cycle and reduces efficiency. It is suggested that if cyclists activated their muscles for shorter durations after they were fatigued, they may increase their output and reduce the stress on their muscles

    2-Bromo-3-nitro­benzaldehyde

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    The title compound, C7H4BrNO3, was isolated as a by-product while attempting to prepare a diselenide. There is a close intra­molecular Br⋯O contact [2.984 (2) Å]. The mol­ecules form loosely associated dimers held together by weak inter­molecular Br⋯O inter­actions with the nitro O atoms [Br⋯O = 3.179 (3) Å]. As a result of these inter­actions, there is also a close Br⋯Br inter­molecular contact [3.8714 (6) Å]. In addition, there are weak inter­molecular C—H⋯O inter­actions. The combination of these inter­actions produces sheets which propagate in the (210) and (10) directions perpendicular to c
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