bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability and instability of breathers in the U(1) Sasa–Satsuma and nonlinear Schrödinger models*
Authors: Alejo Miguel A , Fanelli Luca , Muñoz Claudio 
Published: May 2021

Abstract
We consider the Sasa–Satsuma (SS) and nonlinear Schrödinger (NLS) equations posed along the line, in 1 + 1 dimensions. Both equations are canonical integrable U(1) models, with solitons, multi-solitons and breather solutions Yang (2010 SIAM Mathematical Modeling and Computation). For these two equations, we recognize four distinct localized breather modes: the Sasa–Satsuma for SS, and for NLS the Satsuma–Yajima, Kuznetsov–Ma and Peregrine breathers. Very little is known about the stability of these solutions, mainly because of their complex structure, which does not fit into the classical soliton behavior Grillakis et al (1987 J. Funct. Anal.
74 160–97). In this paper we find the natural H
2 variational characterization for each of them. This seems to be the first known variational characterization for these solutions; in particular, the first one obtained for the famous Peregrine breather. We also prove that Sasa–Satsuma breathers are H
2 nonlinearly stable, improving the linear stability property previously proved by Pelinovsky and Yang (2005 Chaos
15 037115). Moreover, in the SS case, we provide an alternative understanding of the SS solution as a breather, and not only as an embedded soliton. The method of proof is based in the use of a H
2 based Lyapunov functional, in the spirit of Alejo and Muñoz (2013 Commun. Math. Phys.
324 233–62), extended this time to the vector-valued case. We also provide another rigorous justification of the instability of the remaining three nonlinear modes (Satsuma–Yajima, Peregrine and Kuznetsov–Ma), based in the study of their corresponding linear variational structure (as critical points of a suitable Lyapunov functional), and complementing the instability results recently proved e.g. in Muñoz (2017 Proyecciones (Antofagasta) 36 653–83).
How modular structure determines operational resilience of power grids
Authors: Kim Heetae 
Published: May 2021

AbstractThe synchronization stability has been analyzed as one of the important dynamical characteristics of power grids. In this study, we bring the operational perspective to the synchronization stability analysis by counting not only full but also partial synchronization between nodes. To do so, we introduce two distinct measures that estimate the operational resilience of power-grid nodes: functional secureness centrality and functional robustness centrality. We demonstrate the practical applicability of the measures in a model network motif and an IEEE test power grid. As a case study of German power grid, we reveal that the modular structure of a power grid and particular unidirectional current flow determine the distribution of the operational resilience of power-grid nodes. Reproducing our finding on clustered benchmark networks, we validate the modular effect on power grid stability and confirm that our measures can be the insightful tools to understand the power grids’ synchronization dynamics.
Oscillon collapse to black holes
Authors: Nazari Zainab , Cicoli Michele , Clough Katy , Muia Francesco 
Published: May 2021

Abstract
Using numerical relativity simulations we study the dynamics of pseudo-topological objects called oscillons for a class of models inspired by axion-monodromy. Starting from free field solutions supported by gravitational attractions, we investigate the effect of adding self-interactions, and contrast this with the effect of adding self-interactions whilst removing gravitational support. We map out regions of the parameter space where the initial conditions rapidly collapse to black holes, and other regions where they remain pseudo-stable or disperse.
The SPIRAL1 charge breeder: key points for a high-performance 1+ beam injection
Authors: Maunoury L. , Kamalou O. , Cam J.F. , Damoy S. , Delahaye P. , Dubois M. , Frigot R. , Hormigos S. , Vandamme C. 
Published: May 2021

Abstract
The SPIRAL1 charge breeder is now under operation. Radioactive beam has already been delivered [1] to physicists for performing experiments. Although charge breeding efficiencies demonstrated high performances for stable ion beams, efficiencies regarding radioactive ion beams were found to be lower than expected in the first experiment. The beam optics, prior to the injection of the 1+ ions into the SPIRAL1 charge breeder, is of prime importance [2] for reaching such high efficiencies. Moreover, the intensities of the radioactive ion beams are so low that it is very difficult to tune the charge breeder. The tuning of the charge breeder for radioactive ion beams requires a particular procedure often referred to as “blind tuning”. A stable beam with a similar Brho (within a few percent) is required to find the set of optic parameters before tuning the radioactive ion beam. Hence, it has been decided to focus our efforts on this procedure in order to get control of the 1+ beam optics leading to high charge breeding efficiencies whatever the 1+ mass, energy and Target Ion Source System (TISS) used. Knowing that each TISS provides ion beams with a specific energy spread ΔE, and given that the energy acceptance window of the charge breeder is rather narrow, this parameter must also play an important role in determining the overall charge breeding efficiency.

This contribution will show the strategy undertaken to overcome the difficulties encountered in the charge breeding tuning with 1+ radioactive ion beams from the different ion sources, and the results already obtained. A series of experiments have been done to record beam parameters as well as beam profiles in two modes: “shooting through” and 1+/N+. Simulations have been developed to replicate the measurements: for this purpose a combination of SIMION and TraceWin software was used. The final goal is to define a set of beam optics reliable enough for operation covering a large range of 1+ mass, energy and emittance; applying the resulting set of parameters must eventually allow to approach the expected optimal charge breeder performances while producing a radioactive ion beam.
Dissolved and gaseous nitrogen losses in forests controlled by soil nutrient stoichiometry
Authors: Oulehle Filip , Goodale Christine L , Evans Christopher D , Chuman Tomáš , Hruška Jakub , Krám Pavel , Navrátil Tomáš , Tesař Miroslav , Ač Alexandr , Urban Otmar , Tahovská Karolina 
Published: May 2021

Abstract
Global chronic nitrogen (N) deposition to forests can alleviate ecosystem N limitation, with potentially wide ranging consequences for biodiversity, carbon sequestration, soil and surface water quality, and greenhouse gas emissions. However, the ability to predict these consequences requires improved quantification of hard-to-measure N fluxes, particularly N gas loss and soil N retention. Here we combine a unique set of long-term catchment N budgets in the central Europe with ecosystem 15N data to reveal fundamental controls over dissolved and gaseous N fluxes in temperate forests. Stream leaching losses of dissolved N corresponded with nutrient stoichiometry of the forest floor, with stream N losses increasing as ecosystems progress towards phosphorus limitation, while soil N storage increased with oxalate extractable iron and aluminium content. Our estimates of soil gaseous losses based on 15N stocks averaged 2.5 ± 2.2 kg N ha−1 yr−1 and comprised 20% ± 14% of total N deposition. Gaseous N losses increased with forest floor N:P ratio and with dissolved N losses. Our relationship between gaseous and dissolved N losses was also able to explain previous 15N-based N loss rates measured in tropical and subtropical catchments, suggesting a generalisable response driven by nitrate (NO3
−) abundance and in which the relative importance of dissolved N over gaseous N losses tended to increase with increasing NO3
− export. Applying this relationship globally, we extrapolated current gaseous N loss flux from forests to be 8.9 Tg N yr−1, which represent 39% of current N deposition to forests worldwide.
A quantitative genetics approach to validate lab- versus field-based behavior in novel environments
Authors: Mouchet Alexia , Dingemanse Niels J 
Published: May 2021

AbstractConclusions about the adaptive nature of repeatable variation in behavior (i.e., “personality”) are often derived from laboratory-based assays. However, the expression of genetic variation differs between laboratory and field. Laboratory-based behavior might not predict field-based behavior thus, cross-context validation is required. We estimated the cross-context correlation between behavior expressed by wild great tits (Parus major) in established laboratory versus field novel environment assays. Both assays have been used as proxies for “exploration tendency.” Behavior in both contexts had similar repeatability (R = 0.35 vs. 0.37) but differed in heritability (h2 = 0.06 vs. 0.23), implying differences in selection pressures. Unexpectedly, there was no cross-context correlation. Laboratory- and field-based behavior thus reflected expressions of two distinct underlying characters. Post hoc simulations revealed that sampling bias did not explain the lack of correlation. Laboratory-based behavior may reflect fear and exploration, but field-based behavior may reflect escape behavior instead, though other functional interpretations cannot be excluded. Thus, in great tits, activity expressed in laboratory versus field novel environment assays is modulated by multiple quasi-independent characters. The lack of cross-context correlation shown here may also apply to other setups, other repeatable behaviors, and other taxa. Our study thus implies care should be taken in labeling behaviors prior to firm validation studies.
Motor cortex stimulation for chronic neuropathic pain: results of a double-blind randomized study
Authors: Hamani Clement , Fonoff Erich T , Parravano Daniella C , Silva Valquiria A , Galhardoni Ricardo , Monaco Bernardo A , Navarro Jessie , Yeng Lin T , Teixeira Manoel J , de Andrade Daniel Ciampi 
Published: May 2021

Abstract
Motor cortex stimulation via surgically implanted electrodes has been used as an off-label treatment for chronic neuropathic pain, but its efficacy has not been fully established. We aimed to objectively study the efficacy of motor cortex stimulation and characterize potential predictors of response.
In this randomized, double-blind, sham-controlled, single centre trial, we recruited 18 patients with chronic neuropathic pain who did not adequately respond to conventional treatment and had a numerical pain rating scale (NRS) score ≥6. Patients were initially assigned to receive 3 months of active (‘on’) or sham (‘off’) stimulation in a double-blind cross-over phase. This was followed by a 3-month single-blind phase, and 6 months of open-label follow-up. A meaningful response in our trial was defined as a ≥30% or 2-point reduction in NRS scores during active stimulation.
Using Bayesian statistics, we found a 41.4% probability of response towards on versus off motor cortex stimulation. The probability of improvement during active stimulation (double-blind, single-blind and open-label phases) compared to baseline was 47.2–68.5%. Thirty nine per cent of the patients were considered long-term responders, 71.4% of whom had facial pain, phantom limb pain or complex regional pain syndrome. In contrast, 72.7% of non-responders had either post-stroke pain or pain associated with brachial plexus avulsion. Thirty-nine per cent of patients had a substantial postoperative analgesic effect after electrode insertion in the absence of stimulation. Individuals with diagnoses associated with a good postoperative outcome or those who developed an insertional effect had a near 100% probability of response to motor cortex stimulation.
In summary, we found that ∼40% of patients responded to motor cortex stimulation, particularly those who developed an insertional effect or had specific clinical conditions that seemed to predict an appropriate postoperative response.
Classification of Cortical Neurons by Spike Shape and the Identification of Pyramidal Neurons
Authors: Lemon Roger N , Baker Stuart N , Kraskov Alexander 
Published: May 2021

Abstract
Many investigators who make extracellular recordings from populations of cortical neurons are now using spike shape parameters, and particularly spike duration, as a means of classifying different neuronal sub-types. Because of the nature of the experimental approach, particularly that involving nonhuman primates, it is very difficult to validate directly which spike characteristics belong to particular types of pyramidal neurons and interneurons, as defined by modern histological approaches. This commentary looks at the way antidromic identification of pyramidal cells projecting to different targets, and in particular, pyramidal tract neurons (PTN), can inform the utility of spike width classification. Spike duration may provide clues to a diversity of function across the pyramidal cell population, and also highlights important differences that exist across species. Our studies suggest that further electrophysiological and optogenetic approaches are needed to validate spike duration as a means of cell classification and to relate this to well-established histological differences in neocortical cell types.
Coronavirus Disease 2019 (COVID-19) Disease Severity: Pregnant vs Nonpregnant Women at 82 Facilities
Authors: Hsu Albert L , Ohler Adrienne M , Goldstein Andrea , Truong Sarah , Tang Cynthia Y , Wan Xiu-Feng , McElroy Jane A 
Published: May 2021

Abstract

Background
Pregnancy has been reported to be a risk factor for severe COVID-19. We evaluated the impact of pregnancy on severe COVID-19 and mortality in an electronic medical record (EMR) database that enabled exclusion of labor and delivery (L&D) encounters.

Methods
In this retrospective cohort study, EMRs from 82 healthcare facilities in the Cerner COVID-19 Datamart were analyzed. The study comprised 38 106 individuals aged 18–45 years old with COVID-19 who had emergency department, urgent care, or inpatient encounters from December 2019 to September 2020. Subgroups were balanced through propensity score weights for age, race, smoking status, and number of comorbidities. The primary outcome was COVID-19–related mortality; secondary outcomes were markers of severe COVID-19: intubations, mechanical ventilation, use of vasopressors, diagnosis of sepsis, and diagnosis of acute respiratory distress syndrome.

Results
In comparing pregnant and nonpregnant women, no statistical differences were found for markers of severe COVID-19, after adjusting for age, smoking, race, and comorbidities. The adjusted odds of an inpatient encounter were higher for pregnant vs nonpregnant women (adjusted odds ratio [aOR], 13.2; 95% confidence interval [CI], 11.6–15.3; P &lt; .001), but notably lower after excluding L&D encounters (aOR, 2.3; 95% CI, 1.89–2.88; P &lt; .001). In comparison to women without L&D encounters, hospitalization was significantly more likely for men.

Conclusions
We did not find an increased risk of severe COVID-19 or mortality in pregnancy. Hospitalization does not necessarily indicate severe COVID-19 in pregnancy, as half of pregnant patients with COVID-19 were admitted for L&D encounters in this study.
State Continuity in the Absence of Government: The Underlying Rationale in International Law
Authors: Rim Yejoon 
Published: May 2021

Abstract
The traditional criteria for statehood assume that a state must have a government that enables state effectiveness. In the absence of a separate criterion for state continuity, the ‘constitutive elements’ for state creation have been regarded as also ‘continuative elements’ that preserve a state from extinction. However, practice has shown that a state can continue to exist even in the absence of government, which implies that simple assumptions on state continuity, paralleling rationale developed in the discourse of state creation, are inadequate as an explanatory framework for the situation and should thus be reconsidered. To this end, the article examines the underlying rationale for state continuity in the absence of a government, drawing a distinction between constitutive and continuative elements of statehood. Further, it suggests reframing the element of government as an entitlement belonging to the people and apprehending the state as a legally framed concept that cannot be simply determined by its effectiveness. In so doing, the article explores the role of international law in supporting the legal continuity of the state beyond effectiveness.
The Associations of Handgrip Strength and Leg Extension Power Asymmetry on Incident Recurrent Falls and Fractures in Older Men
Authors: McGrath Ryan , Blackwell Terri L , Ensrud Kristine E , Vincent Brenda M , Cawthon Peggy M 
Published: May 2021

Abstract

Background
Evaluating asymmetries in muscle function could provide important insights for fall risk assessments. We sought to determine the associations of (i) handgrip strength (HGS) asymmetry and (ii) leg extension power (LEP) asymmetry on risk of incident recurrent falls and fractures in older men.

Method
There were 5 730 men with HGS asymmetry data and 5 347 men with LEP asymmetry data from the Osteoporotic Fractures in Men (MrOS) study. A handgrip dynamometer measured HGS and a Nottingham Power Rig ascertained LEP. Percent difference in maximal HGS between hands was calculated, and asymmetric HGS was defined as men in the highest quartile of dissimilarity for HGS between hands. The same approach was used to determine asymmetric LEP. Participants self-reported falls every 4 months after the baseline exam, and persons with ≥2 falls in the first year were considered recurrent fallers. Fractures and their dates of occurrence were self-reported and confirmed with radiographic reports.

Results
Older men in the highest HGS asymmetry quartile had a 1.20 (95% confidence interval [CI]: 1.01–1.43) relative risk for incident recurrent falls. Likewise, men in the highest HGS asymmetry quartile had a higher risk for incident fractures: 1.41 (CI: 1.02–1.96) for hip, 1.28 (CI: 1.04–1.58) for major osteoporotic, and 1.24 (CI: 1.06–1.45) for nonspine. There were no significant associations between LEP asymmetry and recurrent falls or fractures.

Conclusions
Asymmetric HGS could be a novel risk factor for falls and fractures that is more feasible to measure than LEP. Fall risk assessments should consider evaluating muscle function, including HGS asymmetry.
Metabolomic Changes Are Predictive of Aging in Laying Hens
Authors: Bendikov-Bar Inna , Malitsky Sergey , Itkin Maxim , Rusal Mark , Sagi Dror 
Published: May 2021

AbstractAging in vertebrates is an extremely complex process that is still poorly understood. One confining factor to studying vertebrate aging is the lack of appropriate models. The laying hen is a good model to study vertebrate aging, as it can be maintained under standard housing conditions, its breeds are genetically well defined and it exhibits significant aging phenotypes at around 18 months of age. Furthermore, laying hens are maintained in a challenging realistic environment and possess a fully functional immune system. Here we used, for the first time, metabolomic profiling of laying hens’ blood for identifying biomarkers of aging. Random forest classifier was used to quantify the quality of the markers and found that the markers can predict the correct age group of individuals with 90% accuracy. Animals under time-restricted feeding, a condition known to increase health span, appeared younger under the markers, indicating that the aging biomarkers can also predict the effectiveness of environmental treatments. Additionally, we found that noise, defined as the ratio between the standard deviation and the mean, is an exceptionally robust and universal biomarker of aging, as metabolomic noise increases significantly with age in laying hens, humans, and mice. Our study suggests the laying hen as a useful model to study aging in vertebrates and establishes metabolomic noise as a novel, universal biomarker of aging.
A minimal sequon sufficient for O-linked glycosylation by the versatile oligosaccharyltransferase PglS
Authors: Knoot Cory J , Robinson Lloyd S , Harding Christian M 
Published: May 2021

Abstract
Bioconjugate vaccines, consisting of polysaccharides attached to carrier proteins, are enzymatically generated using prokaryotic glycosylation systems in a process termed bioconjugation. Key to bioconjugation are a group of enzymes known as oligosaccharyltransferases (OTases) that transfer polysaccharides to engineered carrier proteins containing conserved amino acid sequences known as sequons. The most recently discovered OTase, PglS, has been shown to have the broadest substrate scope, transferring many different types of bacterial glycans including those with glucose at the reducing end. However, PglS is currently the least understood in terms of the sequon it recognizes. PglS is a pilin-specific O-linking OTase that naturally glycosylates a single protein, ComP. In addition to ComP, we previously demonstrated that an engineered carrier protein containing a large fragment of ComP is also glycosylated by PglS. Here we sought to identify the minimal ComP sequon sufficient for PglS glycosylation. We tested &gt;100 different ComP fragments individually fused to Pseudomonas aeruginosa exotoxin A (EPA), leading to the identification of an 11-amino acid sequence sufficient for robust glycosylation by PglS. We also demonstrate that the placement of the ComP sequon on the carrier protein is critical for stability and subsequent glycosylation. Moreover, we identify novel sites on the surface of EPA that are amenable to ComP sequon insertion and find that Cross-Reactive Material 197 fused to a ComP fragment is also glycosylated. These results represent a significant expansion of the glycoengineering toolbox as well as our understanding of bacterial O-linking sequons.
Testing predictions on supplier governance from the global value chains literature
Authors: Van Biesebroeck Johannes , Schmitt Alexander 
Published: May 2021

Abstract
A vast empirical literature analyzes the determinants of the make-or-buy decision. How to organize supplier relationships when the buy option is chosen has received much less attention. The global value chains framework provides testable predictions on the nature of buyer–supplier collaboration. We use a unique transaction-level dataset of outsourced automotive components to study carmakers’ choices between four distinct types of supplier governance: market, captive, relational, or modular. The theory formulates predictions based on three characteristics: the complexity or contractibility of a transaction, the capabilities in the supply base, and how objectively codifiable performance requirements are. Our results illustrate that sourcing relationships vary systematically and that the effects of proxies for the three characteristics are in line with the theory.