bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bifurcation of point vortex equilibria: four-vortex translating configurations and five-vortex stationary configurations
Authors: Tsai Ya-Lun 
Published: October 2020

Abstract
Point vortices in a plane form a dynamical system. A vortex equilibrium is a solution where all vortices move with a common velocity. The configuration is stationary or translating depending on whether the velocity is zero or not. In this paper, we study the bifurcation for four-vortex translating configurations and five-vortex stationary configurations. The number of distinct four-vortex translating configurations can be 0, 3, 4, 6. Among the nonzero cases, there are 1, 0, and 0, or 2 collinear ones, respectively. The number of distinct five-vortex stationary configurations can be 0, 2, 4, 6. In each case, all smaller or equal even numbers of collinear configurations among them are possible. We provide simple and clear necessary and sufficient conditions on nonzero real circulations for all the possible numbers of collinear and strictly planer equilibrium. How two or three equilibrium merge and then apart is also described. All configurations are studied through the minimal polynomial systems obtained and defined by O’Neil. The 4, 5-vortex systems contain two and three independent circulation parameters, respectively. We count the numbers of zeros by univariate polynomials after triangulating the polynomial systems. Information on the numbers of real or complex zeros and their intersection multiplicities for different components are glued together to study the bifurcation as parameters vary in

R

2

and

R

3

for the four-vortex and five-vortex cases, respectively. Many computations are assisted by a computer algebra system.
A prototype Multi-X-ray-source array (MXA) for digital breast tomosynthesis
Authors: Becker Amy E , Hernandez Andrew M , Boone John M , Schwoebel Paul R 
Published: October 2020

Abstract
The design and testing of a prototype Multi-X-ray-source Array (MXA) for digital breast tomosynthesis is reported. The MXA is comprised of an array of tungsten filament cathodes with focus cup grid-controlled modulation and a common rotating anode housed in a single vacuum envelope. Prototypes consisting of arrays of three-source elements and eleven-source-elements were fabricated and evaluated. The prototype sources demonstrated focal spot sizes of 0.3 mm at 45 kV with 50 mA. Measured x-ray spectra were consistent with the molybdenum anode employed, and the tube output (air kerma) was between 0.6 mGy/100 mAs at 20 kV and 17 mGy/100 mAs at 45 kV with a distance of 100 cm. HVL measurements ranged from 0.5 mm Al at 30 kV to 0.8 mm Al at 45 kV, and x-ray pulse widths were varied from 20 ms to 110 ms at operating frequencies ultimately to be limited by source turn-on/off times of ∼1 ms. Initial results of reconstructed tomographic data are presented.
Influences of magnetic field on the coexistence of diquark and chiral condensates in the Nambu–Jona–Lasinio model with axial anomaly
Authors: Zhang Xiao-Bing , Peng Fu-Ping , Wu Yun-Ben , Zhang Yi 
Published: October 2020

Abstract
In this paper, we study the influences of magnetic fields on the coexistence of diquark and chiral condensates in an extended Nambu–Jona–Lasinio model with QCD axial anomaly, as it relates to color-flavor-locked quark matter. Due to the coupling of rotated-charged quarks to magnetic fields, diquark condensates become split, and the coexistence region is thus superseded in favor of a specific diquark Bose–Einstein condensation (BEC), denoted as the BECI phase. For strong magnetic fields, we find that the BECI transition is pushed to larger quark chemical potentials. The effect of magnetic catalysis tends to disrupt the BEC–BCS (Bardeen–Cooper–Schrieffer) crossover predicted in previous works. For intermediate fields, the effect of inverse magnetic catalysis is observed, and the axial-anomaly-induced phase structure is essentially unchanged.
Photon polarization tensor in a magnetized plasma system
Authors: Chao Jingyi , Huang Mei 
Published: October 2020

Abstract
We investigate the photon polarization tensor at finite temperatures in the presence of a static and homogeneous external magnetic field. In our scheme, the summing of the Matsubara frequency is performed after Poisson resummation, which is easily completed and converges quickly. Moreover, the behaviors of finite Landau levels are presented explicitly. It shows a convergence while summing infinite Landau levels. Consequently, there is no necessity to truncate the Landau level in a numerical estimation. At zero temperature, the lowest Landau level (LLL) approximation is analytically satisfied for the vacuum photon polarization tensor. However, we examine that the LLL approximation is not enough for the thermal polarization tensor. The thermal tensor obtains non-trivial contributions from the finite-n Landau levels. And, photon spectra gains a large imaginary contribution in thermal medium, which is the so-called Landau damping. Finally, it is argued that the summation of Matsubara frequency is not commuted with Landau level ones, such conjecture is excluded in our calculations.
Pathological environment directed in situ peptidic supramolecular assemblies for nanomedicines
Authors: Chen Jiali , Zhao Yan , Yao Qingxin , Gao Yuan 
Published: October 2020

Abstract
Peptidic self-assembly provides a powerful method to build biomedical materials with integrated functions. In particular, pathological environment instructed peptidic supramolecular have gained great progress in treating various diseases. Typically, certain pathology related factors convert hydrophilic precursors to corresponding more hydrophobic motifs to assemble into supramolecular structures. Herein, we would like to review the recent progress of nanomedicines based on the development of instructed self-assembly against several specific disease models. Firstly we introduce the cancer instructed self-assembly. These assemblies have exhibited great inhibition efficacy, as well as enhanced imaging contrast, against cancer models both in vitro and in vivo. Then we discuss the infection instructed peptidic self-assembly. A number of different molecular designs have demonstrated the potential antibacterial application with satisfied efficiency for peptidic supramolecular assemblies. Further, we discuss the application of instructed peptidic self-assembly for other diseases including neurodegenerative disease and vaccine. The assemblies have succeeded in down-regulating abnormal Aβ aggregates and immunotherapy. In summary, the self-assembly precursors are typical two-component molecules with (1) a self-assembling motif and (2) a cleavable trigger responsive to the pathological environment. Upon cleavage, the self-assembly occurs selectively in pathological loci whose targeting capability is independent from active targeting. Bearing the novel targeting regime, we envision that the pathological conditions instructed peptidic self-assembly will lead a paradigm shift on biomedical materials.
How do countries specialize in agricultural production? A complex network analysis of the global agricultural product space
Authors: Campi Mercedes , Dueñas Marco , Fagiolo Giorgio 
Published: October 2020

Abstract
Using a complex-network perspective, this paper empirically explores the determinants of the process through which countries, given their capabilities, specialize in agricultural production. Using production data from the Food and Agriculture Organization (FAO) for the period 1993–2013, we characterize the agricultural production space as a time-sequence of bipartite networks, connecting countries to the agricultural products they produce. We then project this representation in the agricultural production spaces, linking countries or products according to their similarity in production profiles, and we identify properties and determinants underlying their evolution. We find that, despite the unprecedented pressure that food systems have been undergoing in recent years, the agricultural production space is a very dense network displaying well-defined and stable communities of countries and products. We also show that the observed country community structures are not only shaped by environmental conditions, but also by economic, socio-political, and technological factors. We conclude by discussing the implications of such findings on our understanding of the complex relationships involving production capabilities and specialization patterns.
Ecophysiological adjustments of a pine forest to enhance early spring activity in hot and dry climate
Authors: Wang Huanhuan , Gitelson Anatoly , Sprintsin Michael , Rotenberg Eyal , Yakir Dan 
Published: October 2020

Abstract
Climate change can impose large offsets between the seasonal cycle of photosynthesis and that in solar radiation and temperature which drive it. Ecophysiological adjustments to such offsets in forests growing under hot and dry conditions are critical for maintaining carbon uptake and survival. Here, we investigate the adjustments that underlie the unusually short and intense early spring productive season, under suboptimal radiation and temperature conditions in a semi-arid pine forest.
We used eddy covariance flux, meteorological, and close-range sensing measurements, together with leaf chlorophyll content over four years in a semi-arid pine forest to identify the canopy-scale ecophysiological adjustments to the short active season, and long seasonal drought.
The results reveal a range of processes that intricately converge to support the early spring peak (March) in photosynthetic activity, including peaks in light use efficiency, leaf chlorophyll content, increase in the absorption of solar radiation, and high leaf scattering properties (indicating optimizing leaf orientation). These canopy-scale adjustments exploit the tradeoffs between the yet increasing temperature and solar radiation, but the concurrently rapidly diminishing soil moisture. In contrast, during the long dry stressful period with rapidly declining photosynthesis under high and potentially damaging solar radiation, physiological photoprotection was conferred by strongly relaxing the early spring adjustments.
The results provide evidence for canopy-scale ecophysiological adjustments, detectable by spectral measurements, that support the survival and productivity of a pine forest under the hot and dry conditions, which may apply to large areas in the Mediterranean and other regions in the next few decades due to the current warming and drying trends.
The role of beliefs, expectations and values in decision-making favoring climate change adaptation—implications for communications with European forest professionals
Authors: Blennow K , Persson J , Gonçalves L M S , Borys A , Dutcă I , Hynynen J , Janeczko E , Lyubenova M , Merganič J , Merganičová K , Peltoniemi M , Petr M , Reboredo F , Vacchiano G , Reyer C P O 
Published: October 2020

Abstract
Beliefs, expectations and values are often assumed to drive decisions about climate change adaptation. We tested hypotheses based on this assumption using survey responses from 508 European forest professionals in ten countries. We used the survey results to identify communication needs and the decision strategies at play, and to develop guidelines on adequate communications about climate change adaptation. We observed polarization in the positive and negative values associated with climate change impacts accepted by survey respondents. We identified a mechanism creating the polarization that we call the ‘blocked belief’ effect. We found that polarized values did not correlate with decisions about climate change adaptation. Strong belief in the local impacts of climate change on the forest was, however, a prerequisite of decision-making favoring adaptation. Decision-making in favor of adaptation to climate change also correlated with net values of expected specific impacts on the forest and generally increased with the absolute value of these in the absence of ‘tipping point’ behavior. Tipping point behavior occurs when adaptation is not pursued in spite of the strongly negative or positive net value of expected climate change impacts. We observed negative and positive tipping point behavior, mainly in SW Europe and N-NE Europe, respectively. In addition we found that advice on effective adaptation may inhibit adaptation when the receiver is aware of effective adaptation measures unless it is balanced with information explaining how climate change leads to negative impacts. Forest professionals with weak expectations of impacts require communications on climate change and its impacts on forests before any advice on adaptation measures can be effective. We develop evidence-based guidelines on communications using a new methodology which includes Bayesian machine learning modeling of the equivalent of an expected utility function for the adaptation decision problem.
Grey matter network trajectories across the Alzheimer’s disease continuum and relation to cognition
Authors: Dicks Ellen , Vermunt Lisa , van der Flier Wiesje M , Barkhof Frederik , Scheltens Philip , Tijms Betty M ,   Alzheimer’s Disease Neuroimaging Initiative
Published: October 2020

Abstract
Biomarkers are needed to monitor disease progression in Alzheimer’s disease. Grey matter network measures have such potential, as they are related to amyloid aggregation in cognitively unimpaired individuals and to future cognitive decline in predementia Alzheimer’s disease. Here, we investigated how grey matter network measures evolve over time within individuals across the entire Alzheimer’s disease cognitive continuum and whether such changes relate to concurrent decline in cognition. We included 190 cognitively unimpaired, amyloid normal (controls) and 523 individuals with abnormal amyloid across the cognitive continuum (preclinical, prodromal, Alzheimer’s disease dementia) from the Alzheimer’s Disease Neuroimaging Initiative and calculated single-subject grey matter network measures (median of five networks per individual over 2 years). We fitted linear mixed models to investigate how network measures changed over time and whether such changes were associated with concurrent changes in memory, language, attention/executive functioning and on the Mini-Mental State Examination. We further assessed whether associations were modified by baseline disease stage. We found that both cognitive functioning and network measures declined over time, with steeper rates of decline in more advanced disease stages. In all cognitive stages, decline in network measures was associated with concurrent decline on the Mini-Mental State Examination, with stronger effects for individuals closer to Alzheimer’s disease dementia. Decline in network measures was associated with concurrent cognitive decline in different cognitive domains depending on disease stage: In controls, decline in networks was associated with decline in memory and language functioning; preclinical Alzheimer’s disease showed associations of decline in networks with memory and attention/executive functioning; prodromal Alzheimer’s disease showed associations of decline in networks with cognitive decline in all domains; Alzheimer’s disease dementia showed associations of decline in networks with attention/executive functioning. Decline in grey matter network measures over time accelerated for more advanced disease stages and was related to concurrent cognitive decline across the entire Alzheimer’s disease cognitive continuum. These associations were disease stage dependent for the different cognitive domains, which reflected the respective cognitive stage. Our findings therefore suggest that grey matter measures are helpful to track disease progression in Alzheimer’s disease.
Repeated Coronavirus Disease 2019 Molecular Testing: Correlation of Severe Acute Respiratory Syndrome Coronavirus 2 Culture With Molecular Assays and Cycle Thresholds
Authors: Gniazdowski Victoria , Paul Morris C , Wohl Shirlee , Mehoke Thomas , Ramakrishnan Srividya , Thielen Peter , Powell Harrison , Smith Brendan , Armstrong Derek T , Herrera Monica , Reifsnyder Carolyn , Sevdali Maria , Carroll Karen C , Pekosz Andrew , Mostafa Heba H 
Published: October 2020

AbstractBackgroundRepeated coronavirus disease 2019 (COVID-19) molecular testing can lead to positive test results after negative results and to multiple positive results over time. The association between positive test results and infectious virus is important to quantify.MethodsA 2-month cohort of retrospective data and consecutively collected specimens from patients with COVID-19 or patients under investigation were used to understand the correlation between prolonged viral RNA positive test results, cycle threshold (Ct) values and growth of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in cell culture. Whole-genome sequencing was used to confirm virus genotype in patients with prolonged viral RNA detection. Droplet digital polymerase chain reaction was used to assess the rate of false-negative COVID-19 diagnostic test results.ResultsIn 2 months, 29 686 specimens were tested and 2194 patients underwent repeated testing. Virus recovery in cell culture was noted in specimens with a mean Ct value of 18.8 (3.4) for SARS-CoV-2 target genes. Prolonged viral RNA shedding was associated with positive virus growth in culture in specimens collected up to 21 days after the first positive result but mostly in individuals symptomatic at the time of sample collection. Whole-genome sequencing provided evidence the same virus was carried over time. Positive test results following negative results had Ct values &gt;29.5 and were not associated with virus culture. Droplet digital polymerase chain reaction results were positive in 5.6% of negative specimens collected from patients with confirmed or clinically suspected COVID-19.ConclusionsLow Ct values in SARS-CoV-2 diagnostic tests were associated with virus growth in cell culture. Symptomatic patients with prolonged viral RNA shedding can also be infectious.
Neutralization of S100A4 induces stabilization of atherosclerotic plaques: role of smooth muscle cells
Authors: Sakic Antonija , Chaabane Chiraz , Ambartsumian Noona , Klingelhöfer Jörg , Lemeille Sylvain , Kwak Brenda R , Grigorian Mariam , Bochaton-Piallat Marie-Luce 
Published: October 2020

Abstract

Aims
During atherosclerosis, smooth muscle cells (SMCs) accumulate in the intima where they switch from a contractile to a synthetic phenotype. From porcine coronary artery, we isolated spindle-shaped (S) SMCs exhibiting features of the contractile phenotype and rhomboid (R) SMCs typical of the synthetic phenotype. S100A4 was identified as a marker of R-SMCs in vitro and intimal SMCs, in pig and man. S100A4 exhibits intra- and extracellular functions. In this study, we investigated the role of extracellular S100A4 in SMC phenotypic transition.

Methods and results
S-SMCs were treated with oligomeric recombinant S100A4 (oS100A4), which induced nuclear factor (NF)-κB activation. Treatment of S-SMCs with oS100A4 in combination with platelet-derived growth factor (PDGF)-BB induced a complete SMC transition towards a pro-inflammatory R-phenotype associated with NF-κB activation, through toll-like receptor-4. RNA sequencing of cells treated with oS100A4/PDGF-BB revealed a strong up-regulation of pro-inflammatory genes and enrichment of transcription factor binding sites essential for SMC phenotypic transition. In a mouse model of established atherosclerosis, neutralization of extracellular S100A4 decreased area of atherosclerotic lesions, necrotic core, and CD68 expression and increased α-smooth muscle actin and smooth muscle myosin heavy chain expression.

Conclusion
We suggest that the neutralization of extracellular S100A4 promotes the stabilization of atherosclerotic plaques. Extracellular S100A4 could be a new target to influence the evolution of atherosclerotic plaques.
Risk factor management and atrial fibrillation
Authors: Hendriks Jeroen M , Gallagher Celine , Middeldorp Melissa E , Lau Dennis H , Sanders Prashanthan 
Published: October 2020

AbstractThe management of atrial fibrillation (AF) is multifaceted and treatment paradigms have changed significantly in the last century. The treatment of AF requires a comprehensive approach which goes beyond the treatment of the arrhythmia alone. Risk factor management has been introduced as a crucial pillar of AF management. As a result, the landscape of care delivery is changing as well, and novel models of comprehensive care delivery for AF have been introduced. This article reviews the evidence for the role of risk factor management in AF, how this can be integrated and implemented in clinical practice by applying novel models of care delivery, and finally identifies areas for ongoing research and potential healthcare reform to comprehensively manage the burgeoning AF population.
Compressible Euler equations on a sphere and elliptic–hyperbolic property
Authors: Holloway Ian , Sritharan Sivaguru S 
Published: October 2020

Abstract
In this work, we systematically derive the governing equations of supersonic conical flow by projecting the 3D Euler equations onto the unit sphere. These equations result from taking the assumption of conical invariance on the 3D flow field. Under this assumption, the compressible Euler equations reduce to a system defined on the surface of the unit sphere. This compressible flow problem has been successfully used to study the steady supersonic flow past cones of arbitrary cross section by reducing the number of spatial dimensions from three down to two while still capturing many of the relevant 3D effects. In this paper, the powerful machinery of tensor calculus is utilized to avoid reference to any particular coordinate system. With the flexibility to use any coordinate system on the surface of a sphere, the equations can be more readily solved numerically when a structured mesh is used by defining the mesh lines to be the coordinate lines. The type of the system of partial differential equations would be hyperbolic or elliptic based on whether the crossflow Mach number is supersonic or subsonic.
Counting Rational Curves on K3 Surfaces With Finite Group Actions
Authors: Zhan Sailun 
Published: October 2020

Abstract
Göttsche gave a formula for the dimension of the cohomology of Hilbert schemes of points on a smooth projective surface $S$. When $S$ admits an action by a finite group $G$, we describe the action of $G$ on the Hodge structure. In the case that $S$ is a K3 surface, each element of $G$ gives a trace on $\sum _{n=0}^{\infty }\sum _{i=0}^{\infty }(-1)^{i}H^{i}(S^{[n]},\mathbb{C})q^{n}$. When $G$ acts faithfully and symplectically on $S$, the resulting generating function is of the form $q/f(q)$, where $f(q)$ is a cusp form. We relate the Hodge structure of Hilbert schemes of points to the Hodge structure of the compactified Jacobian of the tautological family of curves over an integral linear system on a K3 surface as $G$-representations. Finally, we give a sufficient condition for a $G$-orbit of curves with nodal singularities not to contribute to the representation.