bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonnegative control of finite-dimensional linear systems
Authors: Lohéac Jérôme , Trélat Emmanuel , Zuazua Enrique 
Published: July 2020

We consider the controllability problem for finite-dimensional linear autonomous control systems with nonnegative controls. Despite the Kalman condition, the unilateral nonnegativity control constraint may cause a positive minimal controllability time. When this happens, we prove that, if the matrix of the system has a real eigenvalue, then there is a minimal time control in the space of Radon measures, which consists of a finite sum of Dirac impulses. When all eigenvalues are real, this control is unique and the number of impulses is less than half the dimension of the space. We also focus on the control system corresponding to a finite-difference spatial discretization of the one-dimensional heat equation with Dirichlet boundary controls, and we provide numerical simulations.

Résumé
Dans cet article, nous considérons la contrôlabilité d'un système linéaire avec des contrôles positifs. Malgré la condition du rang de Kalman, la condition de positivité des contrôles peut conduire à l'existence d'un temps minimal de contrôlabilité strictement positif. Lorsque tel est le cas, nous démontrons que si la matrice du système de contrôle possède une valeur propre réelle, alors il existe dans l'espace des mesures de Radon positives, un contrôle en le temps minimal et ce contrôle est nécessairement une somme finie de masse de Dirac. De plus, lorsque toutes les valeurs propres de la matrice sont réelles, ce contrôle est unique et le nombre de masses de Dirac le constituant est d'au plus la moitié de la dimension de l'espace d'état. Nous particularisons ces résultats sur l'exemple de l'équation de la chaleur unidimensionnelle, avec des contrôles frontières de type Dirichlet, discrétisée en espace et nous proposons quelques simulations numériques.
Endurance improvement by battery dumping strategy considering Peukert effect for electric-powered disposable UAVs
Authors: Feng X. , Sun Y. , Chang M. , Bai J. 
Published: July 2020

ABSTRACTElectric-powered disposable unmanned aerial vehicles (UAVs) have wide applications due to their advantages in terms of long time flight and load capacity. Thus, improving their endurance has become an important task to enhance the performance of these UAVs. To achieve this, we investigated a battery dumping strategy which splits the battery into several packs that are used and dumped in sequence to reduce the dead weight. The Peukert effect is also considered. In this paper, the sensitivity analysis method was employed to analyse the endurance benefits for different battery weight ratios, Peukert constants and capacities, quantitatively. The results show that the endurance benefits are significantly affected by all three parameters. For ideal batteries, the endurance can be improved by 20% and 28% respectively when employing a double-pack or triple-pack battery strategy (for a battery weight ratio of 0.4), but these benefits will fall rapidly if the Peukert constant exceeds 1.0 or the battery weight declines. Besides, the endurance will be 10% longer if the lift coefficient rather than the velocity remains constant after the battery packs are dumped at a Peukert constant of 1.2.
Factors Influencing Hospital Resilience
Authors: Khademi Jolgehnejad Afsaneh , Ahmadi Kahnali Reza , Heyrani ALi 
Published: July 2020

ABSTRACTThis study aims at investigating the influencing factors on hospital resilience. For this purpose, a systematic review of the literature was conducted. Six databases, including Web of Science, Scopus, SAGE, EBSCO, Google Scholar, and PubMed were searched for articles published between 2000 and 2018. Sixteen studies were selected based on inclusion/exclusion criteria. Content analysis revealed 22 influencing factors were included in a framework with 2 dimensions: (1) phases of the hospital resilience process (preparation, response, and recovery/growth) and (2) the key components of the hospital (staff, infrastructure, management, and logistics). Considering the factors that emerged from this research, suggestions were made to improve hospital resilience. The results of this research will enable a hospital manager to develop better plans for hospital preparedness, as well as perform more effectively before, during, and after disasters.
The utility of chest computed tomography (CT) and RT-PCR screening of asymptomatic patients for SARS-CoV-2 prior to semiurgent or urgent hospital procedures
Authors: Shah Aditya S. , Walkoff Lara A. , Kuzo Ronald S. , Callstrom Matthew R. , Brown Michael J. , Kendrick Michael L. , Narr Bradly J. , Berbari Elie 
Published: July 2020

AbstractObjective:Presently, evidence guiding clinicians on the optimal approach to safely screen patients for coronavirus disease 2019 (COVID-19) to a nonemergent hospital procedure is scarce. In this report, we describe our experience in screening for SARS-CoV-2 prior to semiurgent and urgent hospital procedures.Design:Retrospective case series.Setting:A single tertiary-care medical center.Participants:Our study cohort included patients ≥18 years of age who had semiurgent or urgent hospital procedures or surgeries.Methods:Overall, 625 patients were screened for SARS-CoV-2 using a combination of phone questionnaire (7 days prior to the anticipated procedure), RT-PCR and chest computed tomography (CT) between March 1, 2020, and April 30, 2020.Results:Of the 625 patients, 520 scans (83.2%) were interpreted as normal; 1 (0.16%) had typical features of COVID-19; 18 scans (2.88%) had indeterminate features of COVID-19; and 86 (13.76%) had atypical features of COVID-19. In total, 640 RT-PCRs were performed, with 1 positive result (0.15%) in a patient with a CT scan that yielded an atypical finding. Of the 18 patients with chest CTs categorized as indeterminate, 5 underwent repeat negative RT-PCR nasopharyngeal swab 1 week after their initial swab. Also, 1 patient with a chest CT categorized as typical had a follow-up repeat negative RT-PCR, indicating that the chest CT was likely a false positive. After surgery, none of the patients developed signs or symptoms suspicious of COVID-19 that would indicate the need for a repeated RT-PCR or CT scan.Conclusion:In our experience, chest CT scanning did not prove provide valuable information in detecting asymptomatic cases of SARS-CoV-2 (COVID-19) in our low-prevalence population.
Limit theory for unbiased and consistent estimators of statistics of random tessellations
Authors: Flimmel Daniela , Pawlas Zbyněk , Yukich J. E. 
Published: July 2020

AbstractWe observe a realization of a stationary weighted Voronoi tessellation of the d-dimensional Euclidean space within a bounded observation window. Given a geometric characteristic of the typical cell, we use the minus-sampling technique to construct an unbiased estimator of the average value of this geometric characteristic. Under mild conditions on the weights of the cells, we establish variance asymptotics and the asymptotic normality of the unbiased estimator as the observation window tends to the whole space. Moreover, weak consistency is shown for this estimator.
Body size correlates with discrete-character morphological proxies
Authors: Brougham Tom , Campione Nicolás E. 
Published: July 2020

AbstractPrincipal coordinates analysis (PCoA) is a statistical ordination technique commonly applied to morphology-based cladistic matrices to study macroevolutionary patterns, morphospace occupation, and disparity. However, PCoA-based morphospaces are dissociated from the original data; therefore, whether such morphospaces accurately reflect body-plan disparity or extrinsic factors, such as body size, remains uncertain. We collated nine character–taxon matrices of dinosaurs together with body-mass estimates for all taxa and tested for relationships between body size and both the principal axis of variation (i.e., PCo1) and the entire set of PCo scores. The possible effects of body size on macroevolutionary hypotheses derived from ordinated matrices were tested by reevaluating evidence for the accelerated accumulation of avian-type traits indicated by a strong directional shift in PCo1 scores in hypothetical ancestors of modern birds. Body mass significantly accounted for, on average, approximately 50% and 16% of the phylogenetically corrected variance in PCo1 and all PCo scores, respectively. Along the avian stem lineage, approximately 30% of the morphological variation is attributed to the reconstructed body masses of each ancestor. When the effects of body size are adjusted, the period of accelerated trait accumulation is replaced by a more gradual, additive process. Our results indicate that even at low proportions of variance, body size can noticeably affect macroevolutionary hypotheses generated from ordinated morphospaces. Future studies should thoroughly explore the nature of their character data in association with PCoA-based morphospaces and use a residual/covariate approach to account for potential correlations with body size.
Modelling and peeling extended sources with shapelets: A Fornax A case study
Authors: Line J. L. B. , Mitchell D. A. , Pindor B. , Riding J. L. , McKinley B. , Webster R. L. , Trott C. M. , Hurley-Walker N. , Offringa A. R. 
Published: July 2020

Abstract
To make a power spectrum (PS) detection of the 21-cm signal from the Epoch of Reionisation (EoR), one must avoid/subtract bright foreground sources. Sources such as Fornax A present a modelling challenge due to spatial structures spanning from arc seconds up to a degree. We compare modelling with multi-scale (MS) CLEAN components to ‘shapelets’, an alternative set of basis functions. We introduce a new image-based shapelet modelling package, SHAMFI. We also introduce a new CUDA simulation code (WODEN) to generate point source, Gaussian, and shapelet components into visibilities. We test performance by modelling a simulation of Fornax A, peeling the model from simulated visibilities, and producing a residual PS. We find the shapelet method consistently subtracts large-angular-scale emission well, even when the angular resolution of the data is changed. We find that when increasing the angular resolution of the data, the MS CLEAN model worsens at large angular scales. When testing on real Murchison Widefield Array data, the expected improvement is not seen in real data because of the other dominating systematics still present. Through further simulation, we find the expected differences to be lower than obtainable through current processing pipelines. We conclude shapelets are worthwhile for subtracting extended galaxies, and may prove essential for an EoR detection in the future, once other systematics have been addressed.
‘Waiting and Wanting’: older peoples’ initial experiences of adapting to life in a care home: a grounded theory study
Authors: O'Neill Marie , Ryan Assumpta , Tracey Anne , Laird Liz 
Published: July 2020

AbstractA grounded theory approach, consistent with the work of Strauss and Corbin, was used to undertake semi-structured interviews with 17 older people, to explore their experiences of living in a care home, during the four- to six-week period following the move. Purposive sampling was initially adopted, thereafter, theoretical sampling was employed to recruit individuals identified by care managers within older peoples’ community teams and care home managers within a large Health and Social Care Trust in the United Kingdom. Consistent with grounded theory methodology, data collection and analysis occurred simultaneously. Constant comparative analysis underpinned data analysis and data management techniques. Data analysis revealed five distinct categories that captured these experiences. These were: (a) wanting to connect – ‘I am so lost here’, (b) wanting to adapt – ‘Well mentally you have to make the best of it’, (c) waiting for assistance – ‘it's a frustration for me’, (d) ‘waiting on the end’ – I am making no plans’ and (e) wanting to re-establish links with family and home – ‘I love getting home and I like getting out to the town’. Together these five categories formed the basis of the core category, ‘Waiting and Wanting’, which encapsulates the initial adaptation experiences of the men and women in the study. Findings indicate that individuals were dependent on others to create a sense of belonging, independence and wellbeing. Moreover, risk aversive practices were perceived as a threat to individuals’ independence and autonomy. Recommendations include the need to amend policy and practice for the development of a bespoke induction programme for each resident facilitated by a senior member of the care home staff working in partnership with individuals and families, in addition to the health and social care team, to support a more positive transition for new residents, relatives and care home staff.
Psychometric properties of the Turkish version of the Child Three-Factor Eating Questionnaire for primary and secondary school students
Authors: Demir Dilek , Bektaş Murat , Bektaş İlknur , Demir Şenay , Bryant Eleanor J 
Published: July 2020

AbstractObjective:This study aims to evaluate the validity and reliability of the Turkish version of the Child Three-Factor Eating Questionnaire for primary and secondary school students.Design:A methodological, descriptive and correlational study design was adopted.Setting:The study was conducted in the western and central regions of Turkey.Participants:This methodological–descriptive–correlational study was conducted with 351 children between July 2018 and August 2018. The mean age of children is 10·74 ± 1·79 (8–14).Results:The scale consists of seventeen items and three sub-dimensions (restraint, uncontrolled eating and emotional eating), which explained 52·88 % of the total variance. All the factor loadings were >0·40 in both exploratory factor analysis and confirmatory factor analysis (CFA). In CFA, all of the fit indices were >0·85, and root mean square error of approximation was <0·08. For the whole of the scale, Cronbach’s α was 0·81 and it was found that Cronbach’s α values of all sub-dimensions were >0·70.Conclusions:The results of the study show that the Child Three-Factor Eating Questionnaire for primary and secondary school students is a valid and reliable measurement tool for Turkish sampling.
Occurrence and Altitude of the Long‐Lived Nonspecular Meteor Trails During Meteor Showers at High Latitudes
Authors: Kozlovsky A. , Lukianova R. , Lester M. 
Published: July 2020

AbstractMeteoroids entering the Earth's atmosphere produce ionized trails, which are detectable by radio sounding. Cylindrical underdense (and partly overdense) trails form a great majority of meteor echoes received by meteor radars (MRs). Additionally, the long‐lived nonspecular (LLNS) meteor echoes are received from irregularities of ionization generated along tracks of relatively large meteoroids. At high latitudes where the magnetic field is nearly perpendicular to the Earth's surface the LLNS echoes are possible only from non‐field‐aligned irregularities. The occurrence and height distributions of LLNS echoes are studied using MR observations at the high‐latitude Sodankylä Geophysical Observatory (SGO, 67°22′N, 26°38′E, Finland) during 2008–2019. Two parameters are analyzed: the percentage and height distribution of LLNS echoes. These LLNS echoes constitute about 3% of all MR detections. However, during certain meteor showers (i.e., the Geminids, Perseids, Quadrantids, Arietids or/and Daytime ζ‐Perseids, and Lyrids) the percentage of LLNS echoes is noticeably higher (about 10%, 8%, 7%, 7%, and 4%, respectively). Typically, the LLNSs occur ∼1–2 km higher than other echoes (in June–July the height difference is reduced to ∼0.5–1 km). Moreover, during the Lyrids, η‐Aquariids, Perseids, Orionids, and Leonids the LLNS echoes occur noticeably, up to 3–5 km, higher than the echoes from other types of trails.
A Framework for the Cross‐Validation of Categorical Geostatistical Simulations
Authors: Juda Przemysław , Renard Philippe , Straubhaar Julien 
Published: July 2020

AbstractThe mapping of subsurface parameters and the quantification of spatial uncertainty requires selecting adequate models and their parameters. Cross‐validation techniques have been widely used for geostatistical model selection for continuous variables, but the situation is different for categorical variables. In these cases, cross‐validation is seldom applied, and there is no clear consensus on which method to employ. Therefore, this paper proposes a systematic framework for the cross‐validation of geostatistical simulations of categorical variables such as geological facies. The method is based on K‐fold cross‐validation combined with a proper scoring rule. It can be applied whenever an observation data set is available. At each cross‐validation iteration, the training set becomes conditioning data for the tested geostatistical model, and the ensemble of simulations is compared to true values. The proposed framework is generic. Its application is illustrated with two examples using multiple‐point statistics simulations. In the first test case, the aim is to identify a training image from a given data set. In the second test case, the aim is to identify the parameters in a situation including nonstationarity for a coastal alluvial aquifer in the south of France. Cross‐validation scores are used as metrics of model performance and quadratic scoring rule, zero‐one score, and balanced linear score are compared. The study shows that the proposed fivefold stratified cross‐validation with the quadratic scoring rule allows ranking the geostatistical models and helps to identify the proper parameters.
Evaluation of CERES and CloudSat Surface Radiative Fluxes Over Macquarie Island, the Southern Ocean
Authors: Hinkelman Laura M. , Marchand Roger 
Published: July 2020

AbstractMany studies involving surface radiative fluxes rely on surface fluxes retrieved by the Clouds and the Earth's Radiant Energy System (CERES) project or derived from spaceborne cloud radar and lidar observations (CloudSat‐CALIPSO). In particular, most climate models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) were found to have too little shortwave (SW) radiation being reflected back to space and excessive SW radiation reaching the surface over the Southern Ocean—an error with significant consequences for predicting both regional and global climate. There have been few evaluations of CERES or CloudSat retrievals over the Southern Ocean. In this article, CERES and CloudSat retrieved surface SW and longwave (LW) downwelling fluxes are evaluated using surface observations collected over the Southern Ocean during the Macquarie Island Cloud and Radiation Experiment (MICRE). Overall, biases (CERES—surface observations) in the CERES‐surface fluxes are found to be slightly larger over Macquarie Island than most other regions, approximately +10 W m−2 for the SW and −10 W m−2 for the LW in the annual mean, but with significant seasonal and diurnal variations. If the Macquarie observations are representative of the larger SO, these results imply that CMIP5 model errors in SW surface fluxes are (if anything) somewhat larger than previous evaluation studies suggest. The bias in LW surface flux shows a marked increase at night, which explains most of the total LW bias. The nighttime bias is due to poor representation of cloud base associated with low clouds.
Longitudinally Dependent Low‐Latitude Ionospheric Disturbances Linked to the Antarctic Sudden Stratospheric Warming of September 2019
Authors: Goncharenko L. P. , Harvey V. L. , Greer K. R. , Zhang S.‐R. , Coster A. J. 
Published: July 2020

AbstractThe strongest Southern Hemisphere minor sudden stratospheric warming (SSW) in the last 40 years occurred in September 2019 and resulted in unprecedented weakening of the stratospheric polar vortex. Ionospheric total electron content (TEC) observations are used to provide an overview of statistically significant anomalies in the low‐latitude ionosphere during this event. Quasi‐semidiurnal perturbations of TEC are observed in response to the SSW, similar to those seen during Northern Hemisphere SSWs. Analysis indicates the existence of quasi‐periodic oscillations in TEC in the crests of the equatorial ionization anomaly, with strong 5‐ to 6‐day and 2‐ to 3‐day periodicities. Ionospheric anomalies from the combined effects of multiple mechanisms exceed a factor of 2, comparable to the strongest anomalies associated with Northern Hemisphere SSWs. These results also indicate a remarkable longitudinal variation in the character and magnitude of variations that could be related to a modulation of the non‐migrating diurnal tide.
Increased anticipatory brain response to pleasant touch in women remitted from bulimia nervosa
Authors: Wierenga Christina E. , Bischoff-Grethe Amanda , Berner Laura A. , Simmons Alan N. , Bailer Ursula , Paulus Martin P. , Kaye Walter H. 
Published: July 2020

AbstractBulimia nervosa (BN) is characterized by affective instability and dysregulated behaviors (binge eating, fasting, self-induced vomiting) that disrupt bodily homeostasis. Mechanisms underlying dysregulation in BN are unclear, although altered reward responsivity, anticipatory processing of environmental cues, and interoception (detection and integration of body-state signals to regulate behavior) have been implicated in BN pathophysiology. We aimed to determine whether BN is associated with ineffectively predicting body state or integrating predicted experience with actual experience by examining neural response to anticipation and experience of affective touch, a pleasant interoceptive stimulus that acts on sensory and emotional systems to guide behavior. During fMRI, we administered soft strokes to the palm and forearm in women remitted from BN (RBN;N = 23) and control women (CW;N = 25). A Group (RBN/CW) × Condition (anticipation/touch) interaction was found in the right dorsal caudate; both CW and RBN had increased activation during touch compared with anticipation, with RBN demonstrating marginally greater anticipatory response than CW. For RBN, those individuals who showed greater anticipatory response in the dorsal caudate also reported higher levels of harm avoidance. RBN individuals relative to CW showed greater activation in left putamen and insula during the anticipation but not when experiencing an affective touch. This increase during anticipation rather than the actual experience of the affective touch is consistent with a top-down preparatory process which is associated with harm avoidance and is similar to what has been observed in anxious individuals. This aberrant signal integration could disrupt feedback processing, serving to maintain disordered behavior.