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IOP Conference Series: Materials Science and engineering 2021年第1期1099卷

作者： T Mehta R Mehta M Kumar Department of Mathematics S. S. Jain Subodh College Jaipur Rajasthan India Department of Mathematics & Statistics Manipal University Jaipur Rajasthan India Department of Computer and Communication Engineering Manipal University Jaipur Rajasthan India

Focus of the present study is to explore Joule heating effect on incompressible, radiating, electrically conducting viscoelastic unsteady magnetohydrodynamic fluid and heat transfer through an absorbent media between upstanding equidistant plates with constant suction and slip condition. Lorentz force and Joule heating is discussed by momentum and energy equation respectively. Electric conductivity and the electromagnetic force both are in very small case in fluid flow. A consistent magnetic field is taking to perpendicular to the plane of the plates. The oscillatory time-dependent coupled equations (non-linear) are simplified to provide result for the fluid velocity and heat transfer by using structured perturbation execution. It has been noticed that velocity and heat transfer rise due to rise in Grashof number, Eckert number, heat source parameter or slip parameter while decrease as permeability parameter, radiation parameter or wavelength rises. As Hartmann number rises the fluid velocity diminishes, while opposite behaviour is noted in case of heat transfer effect. The velocity and heat transfer impact of the fluid rise with cross flow Reynolds parameter or frequency of the oscillation. Numerical outcomes for the motion and heat transpose effect profiles for multiples physical numbers also the local skin friction coefficient and spot Nusselt number are argued numerically, presented graphically along with.

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Maternal health and child health disparities among Indigenous and non-Indigenous Australian children: Insights from repeated measures across infancy and adolescence

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Social science & medicine (1982) 2025年 381卷 118292页

作者： Nahida Afroz Enamul Kabir Khorshed Alam Zakir Hossain School of Mathematics Physics and Computing Faculty of Health Engineering and Sciences University of Southern Queensland Toowoomba Queensland 4350 Australia Department of Statistics Faculty of Science Comilla University Cumilla 3506 Bangladesh. Electronic address: Nahida.Afroz@unisq.edu.au. School of Mathematics Physics and Computing Faculty of Health Engineering and Sciences University of Southern Queensland Toowoomba Queensland 4350 Australia. Electronic address: Enamul.Kabir@unisq.edu.au. School of Business Faculty of Business Education Law & Arts University of Southern Queensland Toowoomba Queensland 4350 Australia. Electronic address: Khorshed.Alam@unisq.edu.au. Department of Statistics University of Dhaka Dhaka 1000 Bangladesh. Electronic address: zakir.hossain@du.ac.bd.

BACKGROUND:This study investigates the prevalence and predictors of inferior or less-optimal health (LOPTH) and the Physical Health Outcome Index (PHOIND) among Indigenous and non-Indigenous Australian children from infancy to adolescence, focusing on the impact of maternal health factors. METHODS:Data from the Longitudinal Study of Australian Children (LSAC) (Wave 1, 2004; Wave 8, 2018) were analyzed using binary logistic and linear regression models. Bootstrap resampling was employed to address the small Indigenous sample size, and multicollinearity was assessed using variance inflation factors (VIF), generalized VIF, tolerance, and eigenvalues. RESULTS:Indigenous infants had a higher prevalence of LOPTH (21.5 %) compared to non-Indigenous infants (12.7 %), with disparities widening in adolescence (Indigenous: 27.0 %; non-Indigenous: 14.9 %). Maternal smoking during pregnancy significantly increased the odds of LOPTH among Indigenous infants (OR = 3.91, 95 % CI: 1.33, 11.49). Maternal physical activity was associated with reduced odds of LOPTH and higher PHOIND scores, indicating protective effects. Maternal psychological distress and stressful life events (SLEs) were linked to lower PHOIND scores in Indigenous infants but not in non-Indigenous infants. Maternal LOPTH significantly impacted non-Indigenous infants' and adolescents' health but was not significant for Indigenous groups, despite Indigenous infants had nearly twice the LOPTH rate, a trend that continued into adolescence. CONCLUSION:Persistent disparities between Indigenous and non-Indigenous children are evident, highlighting the impact of maternal health. Culturally tailored interventions addressing maternal mental health, smoking, and physical activity are crucial to reduce inequities and improve health outcomes for Indigenous families in Australia.

关键词： Bootstrap estimation Health disparities Health related behavior's Indigenous health Longitudinal study Maternal and child health

Acoustic waveguide with a dissipative inclusion

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arXiv 2022年

作者： Chesnel, Lucas Heleine, Jérémy Nazarov, Sergei A. Taskinen, Jari Inria Ensta Paris Institut Polytechnique de Paris 828 Boulevard des Maréchaux Palaiseau91762 France Institut de Mathématiques de Toulouse CNRS UMR 5219 Université Paul Sabatier ToulouseF-31062 Cedex 9 France Institute of Problems of Mechanical Engineering RAS V.O. Bolshoi pr. 61 St. Petersburg199178 Russia Department of Mathematics and Statistics University of Helsinki P.O.Box 68 HelsinkiFI-00014 Finland

We consider the propagation of acoustic waves in a waveguide containing a penetrable dissipative inclusion. We prove that as soon as the dissipation, characterized by some coefficient η, is non zero, the scattering solutions are uniquely defined. Additionally, we give an asymptotic expansion of the corresponding scattering matrix when η → 0+ (small dissipation) and when η → +∞ (large dissipation). Surprisingly, at the limit η → +∞, we show that no energy is absorbed by the inclusion. This is due to the so-called skin-effect phenomenon and can be explained by the fact that the field no longer penetrates into the highly dissipative inclusion. These results guarantee that in monomode regime, the amplitude of the reflection coefficient has a global minimum with respect to η. The situation where this minimum is zero, that is when the device acts as a perfect absorber, is particularly interesting for certain applications. However it does not happen in general. In this work, we show how to perturb the geometry of the waveguide to create 2D perfect absorbers in monomode regime. Asymptotic expansions are justified by error estimates and theoretical results are supported by numerical illustrations. Copyright © 2022, The Authors. All rights reserved.

关键词： Boundary layers

Steady Rayleigh-BénardRayleigh-Bénard convection between stress-free boundaries

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arXiv 2020年

作者： Wen, Baole Goluskin, David LeDuc, Matthew Chini, Gregory P. Doering, Charles R. Department of Mathematics University of Michigan Ann ArborMI48109-1043 United States Department of Mathematics & Statistics University of Victoria VictoriaBCV8P 5C2 Canada Department of Physics University of Michigan Ann ArborMI48109-1040 United States Program in Integrated Applied Mathematics University of New Hampshire DurhamNH03824 United States Department of Mechanical Engineering University of New Hampshire DurhamNH03824 United States Center for the Study of Complex Systems University of Michigan Ann ArborMI48109-1042 United States

Steady two-dimensional Rayleigh-Bénard convection between stress-free isothermal boundaries is studied via numerical computations. We explore properties of steady convective rolls with aspect ratios π/5 ⩽ Γ ⩽ 4π, where Γ is the width-to-height ratio for a pair of counter-rotating rolls, over eight orders of magnitude in the Rayleigh number, 103 ⩽ Ra ⩽ 1011, and four orders of magnitude in the Prandtl number, 10−2 ⩽ Pr ⩽ 102. At large Ra where steady rolls are dynamically unstable, the computed rolls display Ra → ∞ asymptotic scaling. In this regime, the Nusselt number Nu that measures heat transport scales as Ra1/3 uniformly in Pr. The prefactor of this scaling depends on Γ and is largest at Γ ≈ 1.9. The Reynolds number Re for large-Ra rolls scales as Pr−1Ra2/3 with a prefactor that is largest at Γ ≈ 4.5. All of these large-Ra features agree quantitatively with the semi-analytical asymptotic solutions constructed by Chini & Cox (2009). Convergence of Nu and Re to their asymptotic scalings occurs more slowly when Pr is larger and when Γ is smaller. Copyright © 2020, The Authors. All rights reserved.

关键词： Prandtl number

An Expanded Optimal Control Policy for a Coupled Tanks System with Random Disturbance

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Advances in Pure mathematics 2019年第4期9卷 317-329页

作者： Sie Long Kek Sy Yi Sim Chuei Yee Chen Department of Mathematics and Statistics Universiti Tun Hussein Onn Malaysia Pagoh Malaysia Department of Electrical Engineering Technology Universiti Tun Hussein Onn Malaysia Pagoh Malaysia Department of Mathematics Universiti Putra Malaysia Serdang Malaysia

In this paper, an expanded optimal control policy is proposed to study the coupled tanks system, where the random disturbance is added into the system. Since the dynamics of the coupled tanks system can be formulated as a nonlinear system, determination of the optimal water level in the tanks is useful for the operation decision. On this point of view, the coupled tanks system dynamics is usually linearized to give the steady state operating height. In our approach, a model-based optimal control problem, which is adding with adjusted parameters, is considered to obtain the true operating height of the real coupled tanks system. During the computation procedure, the differences between the real plant and the model used are measured repeatedly, where the optimal solution of the model used is updated. On this basis, system optimization and parameter estimation are integrated. At the end of the iteration, the iterative solution approximates to the correct optimal solution of the original optimal control problem, in spite of model-reality differences. In conclusion, the efficiency of the approach proposed is shown.

关键词： Expanded Optimal Control Coupled Tanks System Model-Reality Differences Iterative Solution Adjusted Parameters

The dynamics of small-scale magnetic fields modulated by the solar cycle

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arXiv 2025年

作者： Stangalini, M. Verth, G. Fedun, V. Perrone, D. Berretti, M. Bushby, P. Jafarzadeh, S. Jess, D.B. Giannattasio, F. Keys, P.H. Bruno, R. Berrilli, F. ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Plasma Dynamics Group School of Mathematical and Physical Sciences The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Plasma Dynamics Group School of Electrical and Electronic Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom University of Trento Via Calepina 14 Trento38122 Italy University of Rome Tor Vergata Department of Physics Via della Ricerca Scientifica 3 Rome00133 Italy School of Mathematics Statistics and Physics Newcastle University Newcastle upon TyneNE1 7RU United Kingdom Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast Northern Ireland BelfastBT7 1NN United Kingdom Niels Bohr International Academy Niels Bohr Institute Blegdamsvej 17 CopenhagenDK-2100 Denmark Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States INGV Istituto Nazionale di Geofisica e Vulcanologia Rome Italy INAF-IAPS Istituto Nazionale di Astrofisica Rome Italy

In addition to sunspots, which represent the most easily visualized manifestation of solar magnetism, cutting-edge observations of the solar atmosphere have uncovered a plethora of magnetic flux tubes, down to the resolving power of modern high-resolution telescopes (a few tens of km), revealing how the Sun is a fully magnetized star. These magnetic elements are advected and buffeted by ambient plasma flows and turbulent convection, resulting in perturbations of the flux tubes that make them natural conduits for channeling wave energy into the upper layers of the Sun’s atmosphere and significantly contributing to the acceleration of the solar wind. Today, data acquired by the Helioseismic and Magnetic Imager (HMI) onboard NASA’s Solar Dynamics Observatory (SDO), have made it possible to study the dynamics of small-scale magnetic fields over long timescales. Here, for the first time, we present the discovery of a modulation in the dynamical behavior of small-scale magnetic concentrations in the photosphere over temporal scales consistent with the solar activity cycle (i.e., 11 years), which has only been made possible by the long observing lifetime of the SDO/HMI spacecraft. Furthermore, a temporal varying polarization of their perturbations is also found on similar timescales. This demonstrates how the small-scale dynamics of magnetic fields are also affected by the global dynamo. These discoveries were realized through automated tracking of magnetic fields in the solar photosphere across 11 continuous years, resulting in the most extended statistical analyses of its kind so far, with more than 31 million magnetic concentrations examined. © 2025, CC BY.

关键词： NASA

Broadening the scope of Education, Career and Open Science in HEP

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arXiv 2022年

作者： Malik, Sudhir DeMuth, David de Jong, Sijbrand Ruchti, Randal Thais, Savannah Fidalgo, Guillermo Heller, Ken Muether, Mathew Betancourt, Minerba Narain, Meenakshi Lewis, Tiffany R. Cranmer, Kyle Watts, Gordon Physics Department University of Puerto Rico Mayaguez PR Mayaguez00682 Puerto Rico Science Department Valley City State University Valley CityND58072 United States Physics Department Radboud University Nijmegen Netherlands Physics Department University of Notre Dame IN46556 United States Physics Department Princeton University Princeton NJ08544 United States School of Physics and Astronomy MinneapolisMN55455 United States Department of Mathematics Statistics and Physics Wichita State University WichitaKS67260 United States Fermilab PO Box 500 BataviaIL60510 United States Department of Physics Brown University ProvidenceRI02912 United States NASA Postdoctoral Program Astroparticle Physics Laboratory NASA Goddard Space Flight Center GreenbeltMD20771 United States

High Energy Particle Physics (HEP) faces challenges over the coming decades with a need to attract young people to the field and STEM careers, as well as a need to recognize, promote and sustain those in the field who are making important contributions to the research effort across the many specialties needed to deliver the science. On one hand, trends in education and career opportunities in HEP have been highly selective and generally exclusionary of participation by underrepresented minority and female students. Missed are a significant pool of students and faculty at Predominantly Undergraduate Institutions (PUIs) and Community Colleges (CC) that could be tapped to increase and strengthen underrepresented participation. On the other hand, a current mindset in the field is that highly specialized skills such as software and firmware development and instrumentation development are not broadly recognized as "physics" work, and thus the perception of what it means to 'be a physicist' must also be challenged. The view of what constitutes significant contribution to the physics must be reexamined, expanded and rewarded. Confronting and addressing these issues would encourage an influx of new workforce into the field, help retain those who are in the field, and equip those who might seek careers outside of HEP. Despite the challenges, there are reasons for optimism. The collaborative nature of the HEP community and the excitement of the science can serve as potentially powerful organizing mechanisms to confront systemic issues such as these. The PUI and CC faculty could be invited to participate and contribute meaningfully to HEP along with their students, who would acquire a variety of skills that prepare them for STEM careers. Access to a master's degree in Applied Physics could enable technological careers in laboratories, accelerator facilities, the private sector and could open avenues to more advanced degrees including PhDs. The Open Science tools established by

关键词： Students

Spatiotemporal development of expanding bacterial colonies driven by emergent mechanical constraints and nutrient gradients

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Nature communications 2025年第1期16卷 4878页

作者： Harish Kannan Hui Sun Mya Warren Tolga Çağlar Pantong Yao Brian R Taylor Kinshuk Sahu Daotong Ge Matteo Mori David Kleinfeld JiaJia Dong Bo Li Terence Hwa Department of Mathematics University of California San Diego La Jolla CA USA. Department of Mathematics and Statistics California State University Long Beach CA USA. paul.sun@csulb.edu. Department of Physics University of California San Diego La Jolla CA USA. San Diego Supercomputer Center University of California San Diego La Jolla CA USA. Neurosciences Graduate Program University of California San Diego La Jolla CA USA. Joint BioEnergy Institute Emeryville CA USA and Systems Biology Department Sandia National Laboratories Livermore CA USA. Department of Bioengineering University of California San Diego La Jolla CA USA. Department of Biomedical Engineering Duke University Durham NC USA. Department of Neurobiology University of California San Diego La Jolla CA USA. Department of Physics & Astronomy Bucknell University Lewisburg PA USA. jiajia.dong@bucknell.edu. Department of Mathematics and Ph.D. Program in Quantitative Biology University of California San Diego La Jolla CA USA. bli@ucsd.edu. Department of Physics University of California San Diego La Jolla CA USA. hwa@ucsd.edu.

Bacterial colonies growing on solid surfaces can exhibit robust expansion kinetics, with constant radial growth and saturating vertical expansion, suggesting a common developmental program. Here, we study this process for Escherichia coli cells using a combination of modeling and experiments. We show that linear radial colony expansion is set by the verticalization of interior cells due to mechanical constraints rather than radial nutrient gradients as commonly assumed. In contrast, vertical expansion slows down from an initial linear regime even while radial expansion continues linearly. This vertical slowdown is due to limitation of cell growth caused by vertical nutrient gradients, exacerbated by concurrent oxygen depletion. Starvation in the colony interior results in a distinct death zone which sets in as vertical expansion slows down, with the death zone increasing in size along with the expanding colony. Thus, our study reveals complex heterogeneity within simple monoclonal bacterial colonies, especially along the vertical dimension. The intricate dynamics of such emergent behavior can be understood quantitatively from an interplay of mechanical constraints and nutrient gradients arising from obligatory metabolic processes.

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An outlier analysis on the trend of Indonesian propensity to save

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Journal of Physics: Conference Series 2021年第1期1899卷

作者： Edi Cahyono Lilis Laome Muh. Syarif La Ode Saidi Makkulau Swasono Raharjo Department of Mathematics Universitas Halu Oleo Indonesia Graduate Program in Economics Universitas Halu Oleo Indonesia Department of Statistics Universitas Halu Oleo Indonesia Faculty of Economics and Business Universitas Halu Oleo Indonesia Department of Mathematics Universitas Negeri Malang Indonesia

Economic cycle is in the interest of researchers as well as governments. Kaldor model of economic cycle is among the existing models. This model is a system consists of two difference equations for discrete model, and two differential equations for continuous model. Two functions of time playing role to the model are capital and production. Saving and investment as functions of capital and production also appear in the model. Often, saving is assumed as a linear function where it is a multiplication of production and a parameter the so-called propensity to save. Hence, it is assumed to be constant. In this paper, Indonesian propensity to save was analyzed. The production is the gross domestic product (GDP). The data of GDP and saving were collected from World Bank. Outlier detection was applied to anlyze the data. Neglecting the outlier, the propensity to save was obtained in the form of logarithmic function. The finding is inline with an economic assumption, and it will be important for studying the Indonesian economy.

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Utilizing the wavelet transform’s structure in compressed sensing

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arXiv 2020年

作者： Dwork, Nicholas Baron, Corey A. O’Connor, Daniel Johnson, Ethan M.I. Kerr, Adam B. Pauly, John M. Larson, Peder E.Z. Department of Radiology and Biomedical Imaging University of California in San Francisco Robarts Research Institute University of Western Ontario Department of Mathematics and Statistics University of San Francisco Department of Biomedical Engineering Northwestern University Stanford Center for Cognitive and Neurobiological Imaging Stanford University Department of Electrical Engineering Stanford University

Compressed sensing has empowered quality image reconstruction with fewer data samples than previously thought possible. These techniques rely on a sparsifying linear transformation. The Daubechies wavelet transform is commonly used for this purpose. In this work, we take advantage of the structure of this wavelet transform and identify an affine transformation that increases the sparsity of the result. After inclusion of this affine transformation, we modify the resulting optimization problem to comply with the form of the Basis Pursuit Denoising problem. Finally, we show theoretically that this yields a lower bound on the error of the reconstruction and present results where solving this modified problem yields images of higher quality for the same sampling patterns using both magnetic resonance and optical images.2 Copyright © 2020, The Authors. All rights reserved.

关键词： Magnetic resonance imaging