bluuebunny/crossref_metadata_2025_split huggingface dataset:
The spatio-temporal epidemic dynamics of COVID-19 outbreak in Africa
Authors: Gayawan Ezra , Awe Olushina O. , Oseni Bamidele M. , Uzochukwu Ikemefuna C. , Adekunle Adeshina , Samuel Gbemisola , Eisen Damon P. , Adegboye Oyelola A. 
Published: September 2020

AbstractCorona virus disease 2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in the city of Wuhan, China in December 2019. Although, the disease appeared in Africa later than other regions, it has now spread to virtually all countries on the continent. We provide early spatio-temporal dynamics of COVID-19 within the first 62 days of the disease's appearance on the African continent. We used a two-parameter hurdle Poisson model to simultaneously analyse the zero counts and the frequency of occurrence. We investigate the effects of important healthcare capacities including hospital beds and number of medical doctors in different countries. The results show that cases of the pandemic vary geographically across Africa with notably high incidence in neighbouring countries particularly in West and North Africa. The burden of the disease (per 100 000) mostly impacted Djibouti, Tunisia, Morocco and Algeria. Temporally, during the first 4 weeks, the burden was highest in Senegal, Egypt and Mauritania, but by mid-April it shifted to Somalia, Chad, Guinea, Tanzania, Gabon, Sudan and Zimbabwe. Currently, Namibia, Angola, South Sudan, Burundi and Uganda have the least burden. These findings could be useful in guiding epidemiological interventions and the allocation of scarce resources based on heterogeneity of the disease patterns.
Extensional constructive real analysis via locators
Authors: Booij Auke B. 
Published: September 2020

AbstractReal numbers do not admit an extensional procedure for observing discrete information, such as the first digit of its decimal expansion, because every extensional, computable map from the reals to the integers is constant, as is well known. We overcome this by considering real numbers equipped with additional structure, which we call a locator. With this structure, it is possible, for instance, to construct a signed-digit representation or a Cauchy sequence, and conversely, these intensional representations give rise to a locator. Although the constructions are reminiscent of computable analysis, instead of working with a notion of computability, we simply work constructively to extract observable information, and instead of working with representations, we consider a certain locatedness structure on real numbers.
Examining taste testing and point-of-purchase prompting as strategies to promote healthier food selection from food trucks
Authors: Bleasdale Jacob , Kruger Jessica S , Gampp April , Kurtz Kelsey , Anzman-Frasca Stephanie 
Published: September 2020

AbstractObjective:To examine the feasibility of taste testing and point-of-purchase prompting to promote healthier food choices at a food truck event.Design:A pre-/post-study was conducted where food trucks provided samples of healthy food items to patrons and implemented point-of-purchase prompting (promotional signage; verbal cues). Implementation fidelity, acceptability and initial effectiveness were assessed via observation, patron surveys and sales data. A linear mixed model with a random effect for subject (food truck) and fixed effect for time point (baseline, intervention and post-intervention) was used to assess changes in relative sales of promoted healthy items as a percentage of food items sold.Setting:Weekly food truck event in Buffalo, New York.Participants:Seven food trucks; 179 patrons.Results:Implementation fidelity data illustrated that all food trucks complied with manualised procedures. Approximately one-third of surveyed patrons accepted a healthy sample, with the majority rating the sample positively. There was no main effect of time when examining changes in relative sales of promoted healthy items across all periods (P = 0·32); however, effect sizes representing changes between individual time points are consistent with an increase from baseline to intervention (d = 0·51), which was maintained through post-intervention (d = 0·03). The change from baseline to post-intervention corresponded to a medium effect size (d = 0·55).Conclusions:Findings generally support the feasibility of implementing taste testing and point-of-purchase prompting to increase the selection of healthy food items from food trucks; implications for future research in this novel setting are discussed.
A Psychophysiological Examination of the Mutability of Type D Personality in a Therapeutic Trial
Authors: Hodgson Kirsty L. , Clayton Debbie A. , Carmi Michael A. , Carmi Louise H. , Ruden Ronald A. , Fraser William D. , Cameron Donnie 
Published: September 2020

Abstract. Identifying the associations between health and personality has been a focus for psychophysiological research. Type D personality is associated with predisposition to physical and psychological ill-health. This statistician-blind parallel-group controlled trial (intervention group vs. waiting list control group) examined the impact of Havening Techniques on the Type D constituents of negative affect (NA) and social inhibition (SI). One hundred twenty-five adult (18+ years) participants in the United Kingdom (72 females, 53 males) completed the Type D Scale-14 (DS14) measure of Type D personality at baseline (T1), 24-hours (T2), and at 1-month (T3). Forty participants in the treatment group received additional stress biomarker assessment of heart rate, blood pressure, and salivary cortisol. Type D caseness remained stable in the waiting list participants ( n = 57). In the treatment group ( n = 68); NA, SI, and total scores decreased from T1 to T2 ( p < .001, p < .001, and p < .001, respectively), and from T2 to T3 ( p = .004, p < .001, and p < .001, respectively), significantly transmuting to non-caseness ( p < .001 for T1 to T2; p = .025 for T2 to T3). Between T1 and T2, decreases in cortisol ( p < .001), diastolic blood pressure ( p < .001), and systolic blood pressure ( p < .001) were demonstrated. Heart rate fell nonsignificantly between T1 and T2 ( p = .063), but significantly from T1 to T3 ( p = .048). The findings of this study indicate the potential mutability of the psychophysiological illness-prone characteristics of Type D personality.
Nowcasting and Validating Earth's Electric Field Response to Extreme Space Weather Events Using Magnetotelluric Data: Application to the September 2017 Geomagnetic Storm and Comparison to Observed and Modeled Fields in Scotland
Authors: Simpson Fiona , Bahr Karsten 
Published: September 2020

AbstractIn the United Kingdom, geomagnetically induced currents (GICs) are calculated from thin‐sheet electrical conductivity models. In the absence of conductivity models, time derivatives of magnetic fields are sometimes used as proxies for GIC‐related electric fields. An alternative approach, favored in the United States, is to calculate storm time electric fields from time‐independent impedance tensors computed from an array of magnetotelluric (MT) sites and storm time magnetic fields recorded at geomagnetic observatories or assumed from line current models. A paucity of direct measurements of storm time electric fields has restricted validation of these different techniques for nowcasting electric fields and GICs. Here, we present unique storm time electric field data from seven MT sites in Scotland that recorded before, during, and after the September 2017 magnetic storm. By Fourier transforming electric field spectra computed using different techniques back to the time domain, we are able to make direct comparisons with these measured storm time electric field time series. This enables us to test the validity of different approaches to nowcasting electric fields. Our preferred technique involves frequency domain multiplication of magnetic field spectra from a regional site with a local impedance tensor that has been corrected for horizontal magnetic field gradients present between the local site and the regional site using perturbation tensors derived from geomagnetic depth sounding (GDS). Scatter plots of scaling factors between measured and nowcasted electric fields demonstrate the importance of coupling between the polarization of the storm time magnetic source field and Earth's direction‐dependent deep electrical conductivity structure.
Long‐Term Variations of Quasi‐Trapped and Trapped Electrons in the Inner Radiation Belt Observed by DEMETER and SAMPEX
Authors: Zhang Kun , Li Xinlin , Xiang Zheng , Khoo Leng Ying , Zhao Hong , Looper Mark D. , Temerin Michael A. , Sauvaud Jean‐André 
Published: September 2020

AbstractElectrons in the Earth's radiation belts can be categorized into three populations: precipitating, quasi‐trapped, and trapped. We use data from the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and Solar, Anomalous, and Magnetospheric Particle Explorer satellite (SAMPEX) missions and from ground‐based neutron monitors (NM) and sunspot observations to investigate the long‐term variation of quasi‐trapped and trapped sub‐MeV electrons on different L shells in the inner belt. DEMETER and SAMPEX measurements span over 17 years and show that at L ≤ 1.14 the electron flux is anticorrelated with sunspot number, but proportional to the cosmic ray intensity represented by NM count rates, which suggests that electrons at the inner edge of the inner belt are produced by Cosmic Ray Albedo Neutron Decay (CRAND). The solar cycle variation of cosmic rays increased the electron flux at L ≤ 1.14 by a factor of 2 from solar maximum at 2001 to solar minimum at 2009. At L ≥ 1.2, both quasi‐trapped and trapped electrons are enhanced during geomagnetic storms and decay to a background level during extended quiet times. At L > 2, quasi‐trapped electrons resemble trapped electrons, with correlation coefficients as high as 0.97, indicating that pitch angle scattering is the dominant process in this region.
Measuring the Electron Density Roughness of the D‐Region Ionosphere
Authors: Higginson‐Rollins Marc A. , Cohen Morris B. 
Published: September 2020

AbstractWe present a method of characterizing the horizontal and vertical electron density roughness of the D‐region ionosphere using Nationwide Differential Global Position System (NDGPS) transmitters as low‐frequency (LF; 30–300 kHz) and medium‐frequency (MF; 300–3,000 kHz) signals of opportunity. The horizontal roughness is characterized using an amplitude cross‐correlation method, which yields the correlation length scale metric. The vertical roughness is characterized using a differential phase height, which is needed to mitigate the effects of transmitter phase instability. The ranges and typical values of roughness metrics are investigated using data from several field campaign measurements. Finally, the roughness metrics for an NDGPS transmitter and very low frequency (VLF) transmitter are compared. It is found that the roughness detected by the VLF transmitter is significantly smoother and demonstrates the utility of this method to complement traditional VLF measurements.
An FDTD Investigation of Orthogonality and the Backscattering of HF Waves in the Presence of Ionospheric Irregularities
Authors: Smith D. R. , Tan T. , Dao E. , Huang C. , Simpson J. J. 
Published: September 2020

AbstractOne of the most successful instruments used to investigate the Earth's ionosphere is coherent scatter radars such as the Super Dual Auroral Radar Network (SuperDARN). Their method of mapping plasma convection at high latitudes is contingent on irregularities that momentarily exist in the ionosphere and are elongated along the direction of the geomagnetic field. Under these conditions, SuperDARN transmits high‐frequency (HF) waves that are then backscattered from these plasma irregularities. In order for maximum backscatter to occur, the wave vector of the incident wave must be orthogonal to the magnetic field lines. This is called the “orthogonality condition.” Over the years, ray tracing results have generated many assumptions, where and how orthogonality occurs. However, since ray tracing only tracks the primary direction of energy flow and typically does not account for diffraction, it provides an incomplete understanding of the interaction of HF waves with small ionospheric irregularities. This work investigates the orthogonality assumptions by modeling at high‐resolution HF electromagnetic wave interactions with small‐scale irregularities in the ionosphere. Specifically, the finite‐difference time‐domain (FDTD) method is employed to determine where orthogonality occurs in the ionosphere and the number of times the condition is satisfied during the simulation. The results provide insights into the orthogonality condition as a function of source frequency and elevation angle for both unperturbed and perturbed ionospheres. From these results, small‐scale irregularities are observed to sometimes contribute significantly to the production of backscatter. A discussion is provided to highlight where three existing orthogonality condition assumptions are incorrect or misleading.
Kinetic Ballooning Instability of the Near‐Earth Magnetotail in Voigt Equilibrium
Authors: Khan Abdullah , Zhu Ping , Han Rui , Ali Ahmad 
Published: September 2020

AbstractFor a long time, ballooning instabilities have been believed to be a possible triggering mechanism for the onset of substorm and current disruption initiation in the near‐Earth magnetotail. Yet the stability of the kinetic ballooning mode (KBM) in a global and realistic magnetotail configuration has not been well examined. In this paper, stability of the KBM is evaluated for the two‐dimensional Voigt equilibrium of the near‐Earth magnetotail based on an analytical kinetic theory of ballooning instability in the framework of kinetic magnetohydrodynamic (MHD) model, where the kinetic effects such as the finite gyroradius effect, wave‐particle resonances, and particle drifts motions are included usually through kinetic closures. The growth rate of the KBM strongly depends on the magnetic field line stiffening factor S, which is in turn determined by the effects of the trapped electrons, the finite ion gyroradius, and the magnetic drift motion of charged particles. The KBM is unstable in a finite intermediate range of equatorial βeq and only marginally unstable at higher βeq regime for higher Te/Ti values. The finite ion gyroradius and the trapped electron fraction enhance the stiffening factor that tends to stabilize the KBM in the magnetotail far away from Earth. On the other hand, the current sheet thinning destabilizes KBM in the lower βeq regime and stabilizes KBM in the higher βeq regime.
Ganymede's Far‐Ultraviolet Reflectance: Constraining Impurities in the Surface Ice
Authors: Molyneux P. M. , Nichols J. D. , Becker T. M. , Raut U. , Retherford K. D. 
Published: September 2020

AbstractWe present reflectance spectra of Ganymede's leading and trailing hemispheres in the wavelength range 138–215 nm, obtained by the Hubble Space Telescope Cosmic Origins Spectrograph (HST/COS) in 2014. The most notable feature of both spectra is the absence of a sharp water absorption edge at ~165 nm, seen in laboratory measurements of ice reflectivity and in previous observations of Saturn's icy moons and rings. Rather than displaying a sharp change in the reflectivity at the wavelength of the water ice absorption edge, Ganymede's reflectance gradually increases with wavelength at λ > 165 nm. We show that the observed shape of Ganymede's UV reflectance is inconsistent with intimate mixture models of pure ice with UV‐dark materials including tholins, amorphous carbon, graphite, and silicates. However, we find that intraparticle models, in which a small proportion of a UV‐absorbing contaminant is trapped as inclusions within the ice matrix, are able to suppress the 165 nm feature at contaminant concentrations of <1%. We show that models of ice with inclusions of silicates, Triton‐type tholin, or H2O2 are able to produce the observed gradual increase in reflectivity at λ > 165 nm, but additional absorbing surface materials are required to produce a good fit to Ganymede's previously observed near‐UV and visible reflectance.
Mesozoic Subduction Accretion History in Central Tibet Constrained From Provenance Analysis of the Mugagangri Subduction Complex in the Bangong‐Nujiang Suture Zone
Authors: Ma Anlin , Hu Xiumian , Kapp Paul , Lai Wen , Han Zhong , Xue Weiwei 
Published: September 2020

AbstractThe Mugagangri Complex in central Tibet provides a record of the subduction accretion history between the Lhasa and Qiangtang terranes and consists of coherent sedimentary sequences, strongly dismembered formations, and siliciclastic‐matrix block‐in‐matrix mélange. We identified three different groups of sandstone within the Mugagangri Complex. Group 1 is volcaniclastic lithic (Q41F19L40, Lm16Lv77Ls7) and exhibits youngest U‐Pb detrital zircon (YDZ) ages of 177–170 Ma. Group 2 is litho‐quartzose (Q67F6L27, Lm23Lv63Ls13) with YDZ ages of 237–213 Ma. Groups 1 and 2 show provenance affinity with the Qiangtang terrane to the north. Group 3 is similar to Group 2 in detrital mode (Q67F2L31) and U‐Pb detrital zircon age spectra but is distinguished by more sedimentary fragments (Lm17Lv24Ls59), a 1,200–1,100 Ma age peak that is possibly characteristic of the Lhasa terrane to the south and YDZ ages of 284–246 Ma. During (and possibly prior to) Late Triassic time, the recycled orogen‐derived sandstones, including Group 2 and possibly Group 3, were deposited on the ocean floor adjacent to the Qiangtang terrane. During the early Middle Jurassic, the arc‐derived sandstone (Group 1) was deposited and accreted through the northward subduction of Bangong‐Nujiang oceanic lithosphere. During the late Middle to Late Jurassic, Groups 2 and 3 may have been deposited in a trench or trench slope basin, with Group 3 receiving detritus from both the Lhasa and Qiangtang terranes. These three groups of sandstone and ocean plate stratigraphy were mixed in the mélange during the accretion between the Lhasa and Qiangtang terranes.
An Explicit Scheme to Represent the Bidirectional Hydrologic Exchanges Between the Vadose Zone, Phreatic Aquifer, and River
Authors: Hong M. , Mohanty B. P. , Sheng Z. 
Published: September 2020

AbstractUnderstanding groundwater storage variations as a result of effects from both the vadose zone and the river is of critical importance in the hydraulically connected surface‐subsurface system. In this study, we present a novel Bidirectional Exchange Scheme in Surface and Subsurface (BE3S) that represents bidirectional exchanges between the vadose zone, phreatic aquifer, and river. The approach enables explicit representations of each flow regime while conserving mass, and successfully yields solutions of the coupled system for multiple temporal resolutions. We test the scheme by comparing the BE3S‐derived outputs against other models and corresponding observational data. We apply the scheme to simulate hydrologic states in a reach of the Brazos River in Southeast Texas, such as soil moisture content, groundwater level, and river stage as well as net subsurface discharge fluxes. Good agreements between the simulated and observed data for all the components show the suitability of the proposed scheme in modeling the bidirectional flows and exchanges. We also assess how the bidirectional hydrologic exchanges are affected by adjacent flow domains. We find that vertical percolation is significantly affected by unsaturated soil thickness, resulting in the spatial variability of vertical percolation across sloping topography. Hilltop‐to‐valley convergent groundwater flow is also found to impede vertical percolation in river valleys due to shallow water table while facilitating percolation in the hilltops. The capability of the presented scheme that accounts for the topographically driven lateral groundwater flow and drainage dynamics provides the potential to enhance the representation of the surface‐subsurface system in Earth System Models (ESMs).
Flow and Entrainment Mechanisms Around a Freshwater Mussel Aligned With the Incoming Flow
Authors: Wu Hao , Constantinescu George , Zeng Jie 
Published: September 2020

AbstractThe paper uses information from eddy‐resolving simulations to characterize flow and turbulence around freshwater mussels at the organism scale. The focus is on the simplest case of a partially burrowed, isolated mussel aligned with the incoming flow in an open channel. The wake structure and the capacity of the flow to displace the mussel from the bed substrate and to induce local scour around the mussel are investigated as a function of the ratio between the height of the exposed part of the mussel, h, and the total mussel height, d, and as a function of the filtration velocity ratio (VR) between the incoming channel flow velocity, U0, and the mean velocity inside the excurrent siphon, Ue. As opposed to the flow past most surface‐mounted obstacles where the bed shear stresses are reduced in the wake of the body, the capacity of the flow to induce bed erosion behind isolated mussels aligned with the flow is relatively large because of strong downwelling motions inside the horizontal separated shear layers. These flow features are associated with the formation of counterrotating base vortices of unequal coherence that induce upwash behind the mussel. The total circulation of the base vortices increases with increasing h/d and VR. Though both symmetrical and antisymmetrical shedding are observed in the wake, the antisymmetrical mode dominates, and its strength increases with increasing VR. The nondimensional streamwise force acting on the emerged part of the mussel's shell increases with increasing h/d and VR. Finally, the paper discusses the effects of varying h/d and VR on the dynamics and dilution of the jet of filtered water originating in the excurrent siphon, which is important to understand how mussels affect mixing and water quality (e.g., nutrient availability and phytoplankton concentration) in natural streams.
Improved Prediction of Management‐Relevant Groundwater Discharge Characteristics Throughout River Networks
Authors: Barclay J. R. , Starn J. J. , Briggs M. A. , Helton A. M. 
Published: September 2020

AbstractGroundwater discharge zones connect aquifers to surface water, generating baseflow and serving as ecosystem control points across aquatic ecosystems. The influence of groundwater discharge on surface flow connectivity, fate and transport of contaminants and nutrients, and thermal habitat depends strongly on hydrologic characteristics such as the spatial distribution, age, and depth of source groundwater flow paths. Groundwater models have the potential to predict spatial discharge characteristics within river networks, but models are often not evaluated against these critical characteristics and model equifinality with respect to discharge processes is a known challenge. We quantify discharge characteristics across a suite of groundwater models with commonly used frameworks and calibration data. We developed a base model (MODFLOW‐NWT) for a 1,570‐km2 watershed in the northeastern United States and varied the calibration data, control of river‐aquifer exchange directionality, and resolution. Most models (n = 11 of 12) fit similarly to calibration metrics, but patterns in discharge location, flow path depth, and subsurface travel time varied substantially. We found (1) a 15% difference in the percent of discharge going to first‐order streams, (2) threefold variations in flow path depth, and (3) sevenfold variations in the subsurface travel times among the models. We recalibrated three models using a synthetic discharge location data set. Calibration with discharge location data reduced differences in simulated discharge characteristics, suggesting an approach to improved equifinality based on widespread field‐based mapping of discharge zones. Our work quantifying variation across common modeling approaches is an important step toward characterizing and improving predictions of groundwater discharge characteristics.