bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilizing Ultrasonic Waves in the Investigation of Contact Stresses, Areas, and Embedment of Spheres in Manufactured Materials Replicating Proppants and Brittle Rocks
Authors: Bou-Hamdan Kamel Fahmi , Abbas Azza Hashim 
Published: December 2021

AbstractIn the oil and gas industry, hydraulic fracturing (HF) is a common application to create additional permeability in unconventional reservoirs. Using proppant in HF requires understanding the interactions with rocks such as shale, and the mechanical aspects of their contacts. However, these studies are limited in literature and inconclusive. Therefore, the current research aims to apply a novel method, mainly ultrasound, to investigate the proppant embedment phenomena for different rocks. The study used proppant materials that are susceptible to fractures (glass) and others that are hard and do not break (steel). Additionally, the materials used to represent brittle shale rocks (polycarbonate and phenolic) were based on the ratio of elastic modulus to yield strength (E/Y). A combination of experimental and numerical modeling was used to investigate the contact stresses, deformation, and vertical displacement. The results showed that the relation between the stresses and ultrasound reflection coefficient follows a power-law equation, which validated the method application. From the experiments, plastic deformation was encountered in phenolic surfaces despite the corresponding contacted material. Also, the phenolic stresses showed a difference compared to polycarbonate for both high and low loads, which is explained by the high attenuation coefficient of phenolic that limited the quality of the reflected signal. The extent of vertical displacements surrounding the contact zone was greater for the polycarbonate materials due to the lower E/Y, while the phenolic material was limited to smaller areas not exceeding 50% of polycarbonate for all tested load conditions. Therefore, the study confirms that part of the contact energy in phenolic material was dissipated in the plastic deformation, indicating greater proppant embedment, and leading to a loss in fracture conductivity for rocks of higher E/Y.
Interfacial Engineering Strategy for High-Performance Zn Metal Anodes
Authors: Li Bin , Zhang Xiaotan , Wang Tingting , He Zhangxing , Lu Bingan , Liang Shuquan , Zhou Jiang 
Published: December 2021

AbstractDue to their high safety and low cost, rechargeable aqueous Zn-ion batteries (RAZIBs) have been receiving increased attention and are expected to be the next generation of energy storage systems. However, metal Zn anodes exhibit a limited-service life and inferior reversibility owing to the issues of Zn dendrites and side reactions, which severely hinder the further development of RAZIBs. Researchers have attempted to design high-performance Zn anodes by interfacial engineering, including surface modification and the addition of electrolyte additives, to stabilize Zn anodes. The purpose is to achieve uniform Zn nucleation and flat Zn deposition by regulating the deposition behavior of Zn ions, which effectively improves the cycling stability of the Zn anode. This review comprehensively summarizes the reaction mechanisms of interfacial modification for inhibiting the growth of Zn dendrites and the occurrence of side reactions. In addition, the research progress of interfacial engineering strategies for RAZIBs is summarized and classified. Finally, prospects and suggestions are provided for the design of highly reversible Zn anodes.
Evolution of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) seroprevalence among employees of a US academic children’s hospital during coronavirus disease 2019 (COVID-19) pandemic
Authors: Fisher Brian T. , Sharova Anna , Boge Craig L. K. , Gouma Sigrid , Kamrin Audrey , Blumenstock Jesse , Shuster Sydney , Gianchetti Lauren , Collins Danielle , Akaho Elikplim , Weirick Madison E. , McAllister Christopher M. , Bolton Marcus J. , Arevalo Claudia P. , Goodwin Eileen C. , Anderson Elizabeth M. , Christensen Shannon R. , Balamuth Fran , John Audrey R. Odom , Li Yun , Coffin Susan , Gerber Jeffrey S. , Hensley Scott E. 
Published: December 2021

AbstractObjective:To describe the cumulative seroprevalence of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) antibodies during the coronavirus disease 2019 (COVID-19) pandemic among employees of a large pediatric healthcare system.Design, setting, and participants:Prospective observational cohort study open to adult employees at the Children’s Hospital of Philadelphia, conducted April 20–December 17, 2020.Methods:Employees were recruited starting with high-risk exposure groups, utilizing e-mails, flyers, and announcements at virtual town hall meetings. At baseline, 1 month, 2 months, and 6 months, participants reported occupational and community exposures and gave a blood sample for SARS-CoV-2 antibody measurement by enzyme-linked immunosorbent assays (ELISAs). A post hoc Cox proportional hazards regression model was performed to identify factors associated with increased risk for seropositivity.Results:In total, 1,740 employees were enrolled. At 6 months, the cumulative seroprevalence was 5.3%, which was below estimated community point seroprevalence. Seroprevalence was 5.8% among employees who provided direct care and was 3.4% among employees who did not perform direct patient care. Most participants who were seropositive at baseline remained positive at follow-up assessments. In a post hoc analysis, direct patient care (hazard ratio [HR], 1.95; 95% confidence interval [CI], 1.03–3.68), Black race (HR, 2.70; 95% CI, 1.24–5.87), and exposure to a confirmed case in a nonhealthcare setting (HR, 4.32; 95% CI, 2.71–6.88) were associated with statistically significant increased risk for seropositivity.Conclusions:Employee SARS-CoV-2 seroprevalence rates remained below the point-prevalence rates of the surrounding community. Provision of direct patient care, Black race, and exposure to a confirmed case in a nonhealthcare setting conferred increased risk. These data can inform occupational protection measures to maximize protection of employees within the workplace during future COVID-19 waves or other epidemics.
Abelian actions on compact nonorientable Riemann surfaces
Authors: Rodríguez Jesús 
Published: December 2021

AbstractGiven an integer
$g>2$
, we state necessary and sufficient conditions for a finite Abelian group to act as a group of automorphisms of some compact nonorientable Riemann surface of genus g. This result provides a new method to obtain the symmetric cross-cap number of Abelian groups. We also compute the least symmetric cross-cap number of Abelian groups of a given order and solve the maximum order problem for Abelian groups acting on nonorientable Riemann surfaces.
Stabilization and tracking control of an x-z type inverted pendulum system using Lightning Search Algorithm tuned nonlinear PID controller
Authors: Gürsel Özmen Nurhan , Marul Musa 
Published: December 2021

AbstractInverted pendulum systems (IPSs) are mostly used to demonstrate the control rules for keeping the pendulum at a balanced upright position due to a slight force applied to the cart system. This paper presents an application for nonlinear control of an x-z type IPS by using a proportional-integral-derivative (PID) controller with newly established evolutionary tuning method Lightning Search Algorithm (LSA). A single, double and triple PID controller system is tested with the conventional and the self-tuning controllers to get a better understanding of the performance of the given system. The mathematical modelling of the x-z type IPS, the theoretical explanation of the LSA and the simulation analysis of the x-z type IPS is put forward entirely. The LSA algorithm solves the optimization problem of PID controller in an evolutionary way. The most effective way of making comparisons is evaluating the performance results with a well-known optimization technique or with the previous accepted results. We have compared the system’s performance with particle swarm optimization and with a classical control study in the literature. According to the simulation results, LSA-tuned PID controller has the ability to decrease the overshoot better than the conventional-tuned controllers. Finally, it can be concluded that the LSA-supported PID can better stabilize the pendulum angle and track the reference better for non-disturbed and the slightly disturbed systems.
Heritage preservation in religious contexts. Disciplinary challenges for the Middle East and North Africa (MENA) region
Authors: Rico Trinidad 
Published: December 2021

AbstractThis article examines the ways in which global heritage discourse has operated across the Middle East and North Africa (MENA) region, from an ideological and historical perspective. Ideologically, I consider tensions between heritage preservation practice and religious traditions that share the same landscape or material culture. This discussion, which is relatively marginalized in the heritage literature, has an adverse effect on many attempts by heritage preservationists to mediate or resolve conflicts and contradictions surrounding this type of historic resource. Historically, I revisit the presence and inclusion of experts from the MENA region in the formative years of a global heritage ideology. In this discussion, I juxtapose the relative marginalization of the Middle East and North Africa in global heritage debates against the frequency with which sites and communities across this region are put in the spotlight of religion-driven heritage conflict. Addressing these two forms of (mis)representation, I aim to bring to the foreground the way in which heritage studies is implicated in the constructions of narratives about – not from or by – the MENA region.
A Combinatorial Approach to Reliable Quantitative Analysis of Small Nano-Sized Precipitates: A Case Study with α′ Precipitates in Fe–20 at% Cr Alloy
Authors: Sarkar Sudip Kumar , Shinde Deodatta , Sen Debasis , Biswas Aniruddha 
Published: December 2021

Abstract
The quantitative characterization of small nano-sized precipitates poses genuine challenges and is often deficient in accuracy due to the inherent limitations inevitably associated with the individual experimental techniques. A convenient solution is to utilize multiple complementary techniques. The present work demonstrates an effective way to reliably quantify nano-sized precipitates using a combination of complementary techniques of atom probe tomography (APT), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). As a case study, the size (radius, r), number density (NP), volume fraction (ϕ), and chemical composition of Cr-rich α′ precipitates are determined in Fe–20 at% Cr alloy, thermally aged at 773 K for 1,000 h. This combinatorial approach utilizes the strength of each technique in such a way that the overall accuracy of quantitative precipitation analysis improves significantly. For example, the superior spatial resolution makes TEM the appropriate technique to estimate the size and size distribution of the precipitates, while APT provides the chemical composition. Similarly, SANS analysis incorporates both the size and the compositional information thus derived independently and provides statiscally averaged quantitative analysis overcoming the field-of-view limitations of both TEM and APT. This combinatorial approach improves the accuracy of quantification and provides the true representation of the microstructure.
Assessing the need for a question prompt list that encourages end-of-life discussions between patients with advanced cancer and their physicians: A focus group interview study
Authors: Sato Ayako , Fujimori Maiko , Shirai Yuki , Umezawa Shino , Mori Masanori , Jinno Sayaka , Umehashi Mihoto , Okamura Masako , Okusaka Takuji , Majima Yoshiyuki , Miyake Satoshi , Uchitomi Yosuke 
Published: December 2021

AbstractObjectiveEarly integration of palliative and cancer care improves the quality of life and is facilitated by discussions about the end of life after cessation of active cancer treatment between patients with advanced cancer and their physicians. However, both patients and physicians find end-of-life discussions challenging. The aim of this study was to assess the need for a question prompt list (QPL) that encourages end-of-life discussions between patients with advanced cancer and their physicians.MethodsFocus group interviews (FGIs) were conducted with 18 participants comprising 5 pancreatic cancer patients, 3 family caregivers, 4 bereaved family members, and 6 physicians. Three themes were discussed: question items that should be included in the QPL that encourages end-of-life discussions with patients, family caregivers, and physicians after cessation of active cancer treatment; when the QPL should be provided; and who should provide the QPL. Each interview was audio-recorded, and content analysis was performed.ResultsThe following 9 categories, with 57 question items, emerged from the FGIs: (1) preparing for the end of life, (2) treatment decision-making, (3) current and future quality of life, (4) current and future symptom management, (5) information on the transition to palliative care services, (6) coping with cancer, (7) caregivers’ role, (8) psychological care, and (9) continuity of cancer care. Participants felt that the physician in charge of the patient's care and other medical staff should provide the QPL early during active cancer treatment.Significance of resultsData were collected to develop a QPL that encourages end-of-life discussions between patients with advanced cancer and their physicians.
Functional disability with systematic trends and uncertainty: a comparison between China and the US
Authors: Fu Yu , Sherris Michael , Xu Mengyi 
Published: December 2021

AbstractChina and the US are two contrasting countries in terms of functional disability and long-term care. China is experiencing declining family support for long-term care and developing private long-term care insurance. The US has a more developed public aged care system and private long-term care insurance market than China. Changes in the demand for long-term care are driven by the levels, trends and uncertainty in mortality and functional disability. To understand the future potential demand for long-term care, we compare mortality and functional disability experiences in China and the US, using a multi-state latent factor intensity model with time trends and systematic uncertainty in transition rates. We estimate the model with the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and the US Health and Retirement Study (HRS) data. The estimation results show that if trends continue, both countries will experience longevity improvement with morbidity compression and a declining proportion of the older population with functional disability. Although the elderly Chinese have a shorter estimated life expectancy, they are expected to spend a smaller proportion of their future lifetime functionally disabled than the elderly Americans. Systematic uncertainty is shown to be significant in future trends in disability rates and our model estimates higher uncertainty in trends for the Chinese elderly, especially for urban residents.
Polar Vortices in Planetary Atmospheres
Authors: Mitchell Dann M. , Scott Richard K. , Seviour William J. M. , Thomson Stephen I. , Waugh Darryn W. , Teanby Nicholas A. , Ball Emily R. 
Published: December 2021

AbstractAmong the great diversity of atmospheric circulation patterns observed throughout the solar system, polar vortices stand out as a nearly ubiquitous planetary‐scale phenomenon. In recent years, there have been significant advances in the observation of planetary polar vortices, culminating in the fascinating discovery of Jupiter's polar vortex clusters during the Juno mission. Alongside these observational advances has been a major effort to understand polar vortex dynamics using theory, idealized and comprehensive numerical models, and laboratory experiments. Here, we review our current knowledge of planetary polar vortices, highlighting both the diversity of their structures, as well as fundamental dynamical similarities. We propose a new convention of vortex classification, which adequately captures all those observed in our solar system, and demonstrates the key role of polar vortices in the global circulation, transport, and climate of all planets. We discuss where knowledge gaps remain, and the observational, experimental, and theoretical advances needed to address them. In particular, as the diversity of both solar system and exoplanetary data increases exponentially, there is now a unique opportunity to unify our understanding of polar vortices under a single dynamical framework.
Observations of Pitch Angle Changes of Electrons and High‐Frequency Wave Activities in the Magnetotail Plasma Bubble
Authors: Wei Y. Y. , Huang S. Y. , Yuan Z. G. , Jiang K. , Xu S. B. , Deng X. H. , Zhang J. , Zhang Z. H. , Xiong Q. Y. , Yu L. , Lin T. R. 
Published: December 2021

AbstractPlasma bubble, a low‐entropy flux tube, is usually regarded as the bearer of plasma flux transport in the magnetotail. In this study, we perform a complete analysis of electron dynamics in a plasma bubble in the Earth's magnetotail based on the high time‐resolution data from the Magnetospheric Multiscale (MMS) mission. An electron jet is observed at the center of this plasma bubble. Simultaneously, intense electric field and significant current density, as well as the strong energy dissipation are detected associated with this electron jet. The pitch angle distributions (PADs) of high‐energy electrons exhibit different features at different substructures in this plasma bubble. In Region‐1 and Region‐3, pancake‐type PAD is formed; the PAD becomes isotropic type in Region‐2. The electrons pitch angle changes to field‐aligned distribution in Region‐4. All these changes of electron PADs in substructures can be interpreted mainly by the capture of magnetic mirror and betatron cooling. High‐frequency waves, including whistler waves and electrostatic waves, are detected in several parts of the plasma bubble. The observations of abundant electron‐scale phenomena or processes reveal that the electrons are very dynamic in the large‐scale plasma bubble.
Implications of Laterally Varying Scattering Properties for Subsurface Monitoring With Coda Wave Sensitivity Kernels: Application to Volcanic and Fault Zone Setting
Authors: van Dinther Chantal , Margerin Ludovic , Campillo Michel 
Published: December 2021

AbstractMonitoring changes of seismic properties at depth can provide a first‐order insight into Earth’s dynamic evolution. Coda wave interferometry is the primary tool for this purpose. This technique exploits small changes of waveforms in the seismic coda and relates them to temporal variations of attenuation or velocity at depth. While most existing studies assume statistically homogeneous scattering strength in the lithosphere, geological observations suggest that this hypothesis may not be fulfilled in active tectonic or volcanic areas. In a numerical study we explore the impact of a non‐uniform distribution of scattering strength on the spatio‐temporal sensitivity of coda waves. Based on Monte Carlo simulation of the radiative transfer process, we calculate sensitivity kernels for three different observables, namely travel‐time, decorrelation, and intensity. Our results demonstrate that laterally varying scattering properties can have a profound impact on the sensitivities of coda waves. Furthermore, we demonstrate that the knowledge of the mean intensity, specific intensity, and energy flux, governed by spatial variation of scattering strength, is key to understanding the decorrelation, travel‐time, and scattering kernels, respectively. A number of previous works on coda wave sensitivity kernels neglect the directivity of energy fluxes by employing formulas extrapolated from the diffusion approximation. In this work, we demonstrate and visually illustrate the importance of the use of specific intensity for the travel‐time and scattering kernels, in the context of volcanic and fault zone setting models. Our results let us foresee new applications of coda wave monitoring in environments of high scattering contrast.
3D Seismic Anatomy of a Watershed Reveals Climate‐Topography Coupling That Drives Water Flowpaths and Bedrock Weathering
Authors: Wang Wei , Nyblade Andrew , Mount Greg , Moon Seulgi , Chen Po , Accardo Natalie , Gu Xin , Forsythe Brandon , Brantley Susan L. 
Published: December 2021

AbstractTo investigate how bedrock transforms to soil, we mapped the topography of the interface demarcating onset of weathering under an east‐west trending shale watershed in the Valley and Ridge province in the USA Using wave equation travel‐time tomography from a seismic array of >4,000 geophones, we obtained a 3D P‐wave velocity (Vp) model that resolves structures ∼20 m below land surface (mbls). The depth of mobile soil and the onset of dissolution of chlorite roughly match Vp = 600 m/s and Vp = 2,700 m/s, respectively. Chlorite dissolution initiates porosity growth in the shale matrix. Depth to the 2,700 m/s contour is greater under the N‐ as compared to S‐facing hillslopes and under sub‐planar as compared to concave‐up land surfaces. Broadly, the geometries of the ‘soil’ and ‘chlorite’ Vp contours are consistent with the calculated potential for shear fracture opening under weak regional compression. However, this calculated fracture potential does not consistently explain observations related to N‐ versus S‐facing aspect nor fracture density observed by borehole televiewer. Apparently, regional compression is only a secondary influence on Vp: the primary driver of P‐wave slowing in the upper layers of this catchment is topographic control of reactive water flowpaths and their integrated effects on weathering. The Vp result is best explained as the long‐term integrated effect of groundwater flow‐induced geochemical weathering of shale in response to climate‐driven patterns of micro‐ and macro‐topography.
Fast, Cheap, and Turbulent—Global Ocean Modeling With GPU Acceleration in Python
Authors: Häfner Dion , Nuterman Roman , Jochum Markus 
Published: December 2021

AbstractEven to this date, most earth system models are coded in Fortran, especially those used at the largest compute scales. Our ocean model Veros takes a different approach: it is implemented using the high‐level programming language Python. Besides numerous usability advantages, this allows us to leverage modern high‐performance frameworks that emerged in tandem with the machine learning boom. By interfacing with the JAX library, Veros is able to run high‐performance simulations on both central processing units (CPU) and graphical processing unit (GPU) through the same code base, with full support for distributed architectures. On CPU, Veros is able to match the performance of a Fortran reference, both on a single process and on hundreds of CPU cores. On GPU, we find that each device can replace dozens to hundreds of CPU cores, at a fraction of the energy consumption. We demonstrate the viability of using GPUs for earth system modeling by integrating a global 0.1° eddy‐resolving setup in single precision, where we achieve 1.3 model years per day on a single compute instance with 16 GPUs, comparable to over 2,000 Fortran processes.