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15,544 results on '"Worku, A."'

1. Rapid Methods for Modeling Overdensities of Massive Neutrinos and Other Non-Cold Relics

Author

Worku, Keduse, Sabti, Nashwan, and Kamionkowski, Marc

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Phenomenology
Abstract

Recent work has highlighted the potentially detectable gravitational-lensing effect of neutrino halos on cosmic-microwave-background (CMB) fluctuations with upcoming instruments like SO, CMB-S4, and CMB-HD. Accurate modeling of neutrino-halo density profiles are essential for making theory predictions of their cosmological effects. Yet, they are computationally intensive, particularly in the nonlinear regime. In this work, we present an efficient numerical framework for computing neutrino profiles based on N-1-body simulations within a flat FRW Universe. Our approach enables highly parallelized, rapid calculations of neutrino trajectories near spherically symmetric dark-matter halos, delivering results within seconds. In addition to neutrinos, we demonstrate an application to model the clustering of other non-cold relics, such as a freeze-in dark-matter component. The framework is flexible in its definitions of cosmological and dark-matter-halo parameters, which can be particularly valuable for rapid-scanning tasks. It can also seamlessly incorporate new physics, as we demonstrate with examples of a time-varying gravitational constant and nonstandard neutrino phase-space distributions.

Published
2024

2. Factors Affecting Learning Outcomes Achievement of Public Administration Bachelor Students in Ethiopia

Author

Kiflie Worku Angaw, Bacha Kebede Debela, and Marleen Brans

Abstract

Public administration education is a key instrument to address emerging public administration challenges. Ethiopia started public administration education in the 1950s, and currently, 13 public universities are offering bachelor programs in public administration. Nevertheless, PA program learning outcome achievements are not been studied, and comparative studies are absent. By relying on the resource dependency theory and survey data collected from PA Bachelor students (n = 91) and faculty members (n = 28) in three PA-teaching public universities, this article tries to fill these gaps. Significant differences were found between students and faculty members, and between universities with regard to PA learning outcome achievements. The variation between universities in terms of access to resources and student support is also substantial. The difference between students and faculty members, and between universities on the PA faculty quality and the quality of the teaching-learning method proved insignificant. The study confirms public administration faculty members, access to resources, and student support services positively influence PA learning outcomes. The article contributes to PA education literature and PA program evaluation.

Published
2024
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3. Very high-order symmetric positive-interior quadrature rules on triangles and tetrahedra

Author

Worku, Zelalem Arega, Hicken, Jason E., and Zingg, David W.

Subjects
Mathematics - Numerical Analysis
Abstract

We present novel fully-symmetric quadrature rules with positive weights and strictly interior nodes of degrees up to 84 on triangles and 40 on tetrahedra. Initial guesses for solving the nonlinear systems of equations needed to derive quadrature rules are generated by forming tensor-product structures on quadrilateral/hexahedral subdomains of the simplices using the Legendre-Gauss nodes on the first half of the line reference element. In combination with a methodology for node elimination, these initial guesses lead to the development of highly efficient quadrature rules, even for very high polynomial degrees. Using existing estimates of the minimum number of quadrature points for a given degree, we show that the derived quadrature rules on triangles and tetrahedra are more than 95% and 80% efficient, respectively, for almost all degrees. The accuracy of the quadrature rules is demonstrated through numerical examples., Comment: 17 pages, 6 figures

Published
2024

4. Tensor-Product Split-Simplex Summation-By-Parts Operators

Author

Worku, Zelalem Arega, Hicken, Jason E., and Zingg, David W.

Subjects
Mathematics - Numerical Analysis
Abstract

We present an approach to construct efficient sparse summation-by-parts (SBP) operators on triangles and tetrahedra with a tensor-product structure. The operators are constructed by splitting the simplices into quadrilateral or hexahedral subdomains, mapping tensor-product SBP operators onto the subdomains, and assembling back using a continuous-Galerkin-type procedure. These tensor-product split-simplex operators do not have repeated degrees of freedom at the interior interfaces between the split subdomains. Furthermore, they satisfy the SBP property by construction, leading to stable discretizations. The accuracy and sparsity of the operators substantially enhance the efficiency of SBP discretizations on simplicial meshes. The sparsity is particularly important for entropy-stable discretizations based on two-point flux functions, as it reduces the number of two-point flux computations. We demonstrate through numerical experiments that the operators exhibit efficiency surpassing that of the existing dense multidimensional SBP operators by more than an order of magnitude in many cases. This superiority is evident in both accuracy per degree of freedom and computational time required to achieve a specified error threshold., Comment: 28 pages, 15 figures

Published
2024

5. Detecting self-organising patterns in crowd motion: Effect of optimisation algorithms

Author

Worku, Samson and Mullick, Pratik

Subjects
Mathematics - Optimization and Control, Nonlinear Sciences - Adaptation and Self-Organizing Systems, Nonlinear Sciences - Pattern Formation and Solitons, Physics - Physics and Society
Abstract

The escalating process of urbanization has raised concerns about incidents arising from overcrowding, necessitating a deep understanding of large human crowd behavior and the development of effective crowd management strategies. This study employs computational methods to analyze real-world crowd behaviors, emphasizing self-organizing patterns. Notably, the intersection of two streams of individuals triggers the spontaneous emergence of striped patterns, validated through both simulations and live human experiments. Addressing a gap in computational methods for studying these patterns, previous research utilized the pattern-matching technique, employing the Nelder-Mead Simplex algorithm for fitting a two-dimensional sinusoidal function to pedestrian coordinates. This paper advances the pattern-matching procedure by introducing Simulated Annealing as the optimization algorithm and employing a two-dimensional square wave for data fitting. The amalgamation of Simulated Annealing and the square wave significantly enhances pattern fitting quality, validated through statistical hypothesis tests. The study concludes by outlining potential applications of this method across diverse scenarios., Comment: 12 pages, 7 figures. Accepted for publication in Journal of Mathematics in Industry

Published
2024

6. Robust Nonparametric Stochastic Frontier Analysis

Author

Zheng, Peng, Worku, Nahom, Bannick, Marlena, Dielemann, Joseph, Weaver, Marcia, Murray, Christopher, and Aravkin, Aleksandr

Subjects
Statistics - Methodology, Mathematics - Optimization and Control, 65K10, 62P20
Abstract

Benchmarking tools, including stochastic frontier analysis (SFA), data envelopment analysis (DEA), and its stochastic extension (StoNED) are core tools in economics used to estimate an efficiency envelope and production inefficiencies from data. The problem appears in a wide range of fields -- for example, in global health the frontier can quantify efficiency of interventions and funding of health initiatives. Despite their wide use, classic benchmarking approaches have key limitations that preclude even wider applicability. Here we propose a robust non-parametric stochastic frontier meta-analysis (SFMA) approach that fills these gaps. First, we use flexible basis splines and shape constraints to model the frontier function, so specifying a functional form of the frontier as in classic SFA is no longer necessary. Second, the user can specify relative errors on input datapoints, enabling population-level analyses. Third, we develop a likelihood-based trimming strategy to robustify the approach to outliers, which otherwise break available benchmarking methods. We provide a custom optimization algorithm for fast and reliable performance. We implement the approach and algorithm in an open source Python package `sfma'. Synthetic and real examples show the new capabilities of the method, and are used to compare SFMA to state of the art benchmarking packages that implement DEA, SFA, and StoNED., Comment: 42 pages, 9 figures

Published
2024

16. Magnitude of psychological distress and associated factors among war survivor women in Northern, Ethiopia, 2022: a community-based cross-sectional survey

Author

Salelew, Endalamaw, Assefa, Yohannes Awoke, Getachew, Rediet, Nenko, Goshu, Fanta, Biruk, Amare, Tadele, Demilew, Demeke, Dellie, Endalkachew, Aschalew, Andualem Yalew, Asrade, Geta, Demeke, Zelalem, Shitu, Kegnie, Eriku, Getachew Azeze, Worku, Chanyalew, Kibret, Alemu Kassaw, Haile, Tsegaye Gebremedhin, Hunegnaw, Melkamu Tamir, Fekadu, Haileab, Molla, Ayenew, Belew, Aysheshim Kassahun, Atnafu, Asmamaw, Guadu, Tadesse, Yitayal, Mezgebu, Worku, Netsanet, Gelaye, Kassahun Alemu, Azale, Telake, and Awoke, Tadesse

Published
2024
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17. Correction: Determinants of Malnutrition and its associated factors among pregnant and lactating women under armed conflict areas in North Gondar Zone, Northwest Ethiopia: a community-based study

Author

Belew, Aysheshim Kassahun, Awoke, Tadesse, Gelaye, Kassahun Alemu, Atnafu, Asmamaw, Guadu, Tadesse, Azale, Telake, Yitayal, Mezigebu, Assefa, Yohannes Awoke, Getachew, Rediet, Amare, Tadele, Yitayih, Sewbesew, Shitu, Kegnie, Demilew, Demeke, Dellie, Endalkachew, Aschalew, Andualem Yalew, Fanta, Biruk, Worku, Netsanet, Yalew, Ermias Solomon, Abich, Yohannes, Azeze, Getachew, Worku, Chanyalew, Kibret, Alemu Kassaw, G/Medhin, Tsegaye, Hunegnaw, Melkamu Tamir, Salelew, Endalamaw, Nenko, Goshu, Fekadu, Hailab, and Molla, Ayenew

Published
2024
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22. Harnessing landrace diversity empowers wheat breeding

Author

Cheng, Shifeng, Feng, Cong, Wingen, Luzie U., Cheng, Hong, Riche, Andrew B., Jiang, Mei, Leverington-Waite, Michelle, Huang, Zejian, Collier, Sarah, Orford, Simon, Wang, Xiaoming, Awal, Rajani, Barker, Gary, O’Hara, Tom, Lister, Clare, Siluveru, Ajay, Quiroz-Chávez, Jesús, Ramírez-González, Ricardo H., Bryant, Ruth, Berry, Simon, Bansal, Urmil, Bariana, Harbans S., Bennett, Malcolm J., Bicego, Breno, Bilham, Lorelei, Brown, James K. M., Burridge, Amanda, Burt, Chris, Buurman, Milika, Castle, March, Chartrain, Laetitia, Chen, Baizhi, Denbel, Worku, Elkot, Ahmed F., Fenwick, Paul, Feuerhelm, David, Foulkes, John, Gaju, Oorbessy, Gauley, Adam, Gaurav, Kumar, Hafeez, Amber N., Han, Ruirui, Horler, Richard, Hou, Junliang, Iqbal, Muhammad S., Kerton, Matthew, Kondic-Spica, Ankica, Kowalski, Ania, Lage, Jacob, Li, Xiaolong, Liu, Hongbing, Liu, Shiyan, Lovegrove, Alison, Ma, Lingling, Mumford, Cathy, Parmar, Saroj, Philp, Charlie, Playford, Darryl, Przewieslik-Allen, Alexandra M., Sarfraz, Zareen, Schafer, David, Shewry, Peter R., Shi, Yan, Slafer, Gustavo A., Song, Baoxing, Song, Bo, Steele, David, Steuernagel, Burkhard, Tailby, Phillip, Tyrrell, Simon, Waheed, Abdul, Wamalwa, Mercy N., Wang, Xingwei, Wei, Yanping, Winfield, Mark, Wu, Shishi, Wu, Yubing, Wulff, Brande B. H., Xian, Wenfei, Xu, Yawen, Xu, Yunfeng, Yuan, Quan, Zhang, Xin, Edwards, Keith J., Dixon, Laura, Nicholson, Paul, Chayut, Noam, Hawkesford, Malcolm J., Uauy, Cristobal, Sanders, Dale, Huang, Sanwen, and Griffiths, Simon

Published
2024
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31. Schools of public health as a cornerstone for pandemic preparedness and response: the Africa COVID-19 experience

Author

Ndejjo, Rawlance, Mitonga, Honore Kabwebwe, Amde, Woldekidan, Lubega, Grace Biyinzika, Muula, Adamson S., Mariam, Damen Haile, Kabwama, Steven N., Patrick, Sean Mark, Haufiku, Desderius, Amour, Maryam, Bosonkie, Marc, Mukama, Trasias, Bello, Segun, Dwomoh, Duah, Nja, Glory Mbe Egom, Bulafu, Douglas, Halake, Dabo Galgalo, Frumence, Gasto, Leye, Mamadou Makhtar Mbacke, Katangolo-Nakashwa, Ndasilohenda, Abaya, Samson Wakuma, Diallo, Issakha, Egbende, Landry, Worku, Netsanet, Bassoum, Oumar, Mbunga, Branly, Musoke, David, Mohamed, Hussein, Seck, Ibrahima, Fobil, Julius, Kiwanuka, Suzanne N., Fawole, Olufunmilayo I., Mapatano, Mala Ali, Alfven, Tobias, Gilson, Lucy, Syombua Muinde, Jacinta Victoria, van Marwijk, Harm, Lehmann, Uta, Speybroeck, Niko, Kaseje, Margaret, and Wanyenze, Rhoda K.

Published
2024
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37. Timely initiation of breastfeeding and its associated factors among immediate postpartum mother-newborn pairs in Debre Tabor comprehensive specialized hospital, South Gondar Zone, North West, Ethiopia

Author

Ayalew, Gizat, Gessesse, Abraham Dessie, Tigabu, Dagnew, Admass, Zeleke Endalew, Girma, Bekahegn, Ayehu, Mequanint, Sibhat, Migbar Mekonnen, Demeke, Abel Desalegn, Aragaw, Getie Mihret, Kelkay, Jenberu Mekurianew, Rade, Bayew Kelkay, and Gudayu, Temsegen Worku

Published
2024
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48. Building a machine learning-assisted echocardiography prediction tool for children at risk for cancer therapy-related cardiomyopathy

Author

Edwards, Lindsay A., Yang, Christina, Sharma, Surbhi, Chen, Zih-Hua, Gorantla, Lahari, Joshi, Sanika A., Longhi, Nicolas J., Worku, Nahom, Yang, Jamie S., Martinez Di Pietro, Brandy, Armenian, Saro, Bhat, Aarti, Border, William, Buddhe, Sujatha, Blythe, Nancy, Stratton, Kayla, Leger, Kasey J., Leisenring, Wendy M., Meacham, Lillian R., Nathan, Paul C., Narasimhan, Shanti, Sachdeva, Ritu, Sadak, Karim, Chow, Eric J., and Boyle, Patrick M.

Published
2024
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