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See detailFunctional inequalities for Feynman-Kac semigroups
Thompson, James UL

in Journal of Theoretical Probability (2020)

Using stochastic analysis, we prove various gradient estimates and Harnack inequalities for Feynman-Kac semigroups with possibly unbounded potentials. One of the main results is a derivative formula which ... [more ▼]

Using stochastic analysis, we prove various gradient estimates and Harnack inequalities for Feynman-Kac semigroups with possibly unbounded potentials. One of the main results is a derivative formula which can be used to characterize a lower bound on Ricci curvature using a potential. [less ▲]

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See detailPrevalence of memory impairment 2000-2015 in Sao Paolo, Brazil
Ribeiro, Fabiana UL; de Oliveira Duarte, Yeda; Santos, Jair Licio Ferreira et al

in Alzheimer's and Dementia: the Journal of the Alzheimer's Association (2020), 16

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes ... [more ▼]

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes in prevalence of cognitive impairment across four waves of the Health, Welfare and Aging survey (SABE) with data collected in Sao Paolo, Brazil, in 2000, 2006, 2010, and 2015. Method: Mini Mental State Exam (MMSE) scores and covariate values were available for 5,191 respondents (62.4% female) aged 60 to 99 across four waves. Cognitive impairment was defined as having <=12 points on a 19-point abbreviated version of the MMSE. Age group, educational attainment (no formal schooling, primary, secondary, post-secondary), self-reported heart disease, stroke, diabetes, hypertension, and BMI (<18.5, 18.5-24.9, 25-29.9, 30+) were adjusted for. Result: In more recent waves, prevalence of cognitive impairment was higher for respondents aged 60-64 years (9.0% in 2015 vs. 4.6% in 2000), 65-69 years (9.7% in 2015 vs. 5.8% in 2006) and 70-74 years (13.9% in 2015 vs. 5.8% in 2006). Between 2015 and 2000, respondents were increasingly more likely to report some formal education (90.8% vs. 75.3%), secondary (17.6% vs. 7.3%) or postsecondary education (11.4% vs. 4.3%). Respondents were increasingly more likely to report hypertension (66.5% vs. 54.2%), diabetes (28.7% vs. 17.8%), and be overweight/obese (74.1% vs. 58.9%). In age-adjusted logistic regressions, respondents in 2015 were more likely to show cognitive impairment compared to 2000 (OR 1.84, CI 1.20-2.82). Conclusion: SABE respondents showed higher prevalence of cognitive impairment in 2015 compared to respondents of the same age in earlier waves, but differences disappeared after adjusting for chronic disease burden and educational attainment. [less ▲]

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See detailUsing cohort data to emulate lifestyle interventions: Long-term beneficial effects of initiating physical activity on cognitive decline and dementia
Leist, Anja UL; Muniz-Terrera, Graciela; Solomon, Alina

in Alzheimer's and Dementia: the Journal of the Alzheimer's Association (2020), 16

Background: Intervention studies have shown beneficial short-term effects of physical activity on cognitive decline and reduced risk of dementia. However, randomized controlled trial data of lifestyle ... [more ▼]

Background: Intervention studies have shown beneficial short-term effects of physical activity on cognitive decline and reduced risk of dementia. However, randomized controlled trial data of lifestyle interventions over long time spans are not available due to lack of resources, feasibility or ethical reasons. Drawing from the principles of emulating a ‘target trial’, which apply design principles of randomized trials to the analysis of observational data, cohort data of a large European survey were analyzed to understand the long-term effects of physical activity changes. Method: Biennial assessments of the economic, social, and health situation of respondents aged 50 and older came from the Survey of Health, Ageing and Retirement in Europe (2004-2017). Cognitive functioning (immediate recall, delayed recall, and verbal fluency) and self-reported diagnosis of dementia were assessed at each follow-up. The target trial included sedentary respondents at t1 who, at follow-up (t2), stayed sedentary (“control group”) or newly reported vigorous physical activity more often than once a week (initiators, “treatment group”). Inclusion and exclusion criteria were implemented as close as possible to those of the FINGER trial. Inverse-probability weighting accounted for the probability of initiating physical activity with a large set of predictor variables. Selecting respondents aged 50-85 years old who met the target trial inclusion and exclusion criteria, assessments of cognitive functioning and self-reported diagnosis of dementia were available for 8,781 respondents at t3 (on average 3.02 years later), 3,858 respondents at t4 (5.84 years), and 2,304 respondents at t5 (7.72 years). A total of 304 respondents reported a diagnosis of dementia. Result: Initiators of vigorous physical activity had higher cognitive functioning at two follow-ups compared to non-initiators (t3: “average treatment effect on the treated”, ATET=0.059, CI: 0.028, 0.090), which remained significant after implementing inclusion and exclusion criteria. Initiators had lower risk of dementia compared to non-initiators at all three follow-ups (t3: ATET=-0.009, CI: -0.015, -0.005, relative risk decrease -46.7%), remaining significant after implementing inclusion and exclusion criteria. Conclusion: Emulating a target trial showed long-term benefits of initiating physical activity for cognitive functioning and dementia risk. Multidomain interventions related to nutrition, social, cognitive activities etc. can be similarly emulated. [less ▲]

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See detailParabolic semi-orthogonal decompositions and Kummer flat invariants of log schemes
Scherotzke, Sarah UL; Sibilla, Nicolo; Talpo, Mattia

in Documenta Mathematica (2020)

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See detailGluing semi-orthogonal decompositions
Scherotzke, Sarah UL; Sibilla, Nicolo; Talpo, Mattia

in Journal of Algebra (2020)

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See detailNegative life events, self-efficacy, and social support: Risk and protective factors for school dropout intentions and dropout
Samuel, Robin UL; Burger, Kaspar

in Journal of Educational Psychology (2020), 112(5), 973-986

Prior studies have noted several risk and protective factors for school dropout; however, only a few have examined longer-term vulnerabilities alongside temporary risk and protective factors. Consequently ... [more ▼]

Prior studies have noted several risk and protective factors for school dropout; however, only a few have examined longer-term vulnerabilities alongside temporary risk and protective factors. Consequently, we focused on the role that both stable and time-varying psychosocial risk and protective factors play in dropout intentions and actual dropout, using a 4-year longitudinal design. We investigated to what extent dropout intentions and dropout can be predicted by an interplay between negative life events, general self-efficacy, and perceived social support. We distinguished between time-averaged levels of self-efficacy and social support, and within-person change in self-efficacy and social support over time. This enabled us to establish whether dropout intentions and dropout were sensitive to fluctuations in perceived self-efficacy and social support over time when controlling for person-specific levels of these psychosocial resources. Calculating multilevel models with data from a prospective cohort study (N = 4,956, 43% male), we found that negative life events were significantly associated with an increase in dropout intentions and the likelihood of school dropout. Furthermore, time-averaged levels of self-efficacy and social support, and a within-person (situational) increase in these characteristics relative to their time-averaged levels, were related to lower levels of dropout intentions but did not prevent dropout. The positive relationship between negative life events and dropout intentions was attenuated for individuals who perceived higher levels of self-efficacy than usual. Our findings suggest future research should further investigate time-averaged and situational psychosocial drivers of school dropout in combination. [less ▲]

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See detailIntersymbol and Intercarrier Interference in OFDM Systems: Unified Formulation and Analysis
Cruz–Roldán, Fernando; Alves Martins, Wallace UL; García, Fausto G. et al

E-print/Working paper (2020)

A unified matrix formulation is presented for the analysis of intersymbol and intercarrier interference in orthogonal frequency-division multiplexing (OFDM) systems. The proposed formulation relies on six ... [more ▼]

A unified matrix formulation is presented for the analysis of intersymbol and intercarrier interference in orthogonal frequency-division multiplexing (OFDM) systems. The proposed formulation relies on six parameters and allows studying various schemes, including those with windowing in the transmitter and/or in the receiver (called windowed OFDM systems), which may add cyclic suffix and/or cyclic prefix (CP), besides the conventional CP-OFDM. The proposed framework encompasses seven different OFDM systems. It considers the overlap-and-add procedure performed in the transmitter of windowed OFDM systems, being jointly formulated with the channel convolution. The intersymbol and intercarrier interference, caused when the order of the channel impulse response is higher than the number of CP samples, is characterized. A new equivalent channel matrix that is useful for calculating both the received signal and the interference power is defined and characterized. Unlike previous works, this new channel matrix has no restrictions on the length of the channel impulse response, which means that the study is not constrained to the particular case of two or three data blocks interfering in the received signal. Theoretical expressions for the powers of three different kinds of interference are derived. These expressions allow calculating the signal-to-interference-plus-noise ratio, useful for computing the data rate of each OFDM system. The proposed formulation is applied to realistic examples, showing its effectiveness through comparisons based on numerical performance assessments of the considered OFDM systems. [less ▲]

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See detailStochastic and Quantum Thermodynamics of Driven RLC Networks
Freitas, Nahuel; Delvenne, Jean-Charles; Esposito, Massimiliano UL

in Phys. Rev. X (2020), 10(3), 031005

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See detailLarge Intelligent Surface for Positioning in Millimeter Wave MIMO Systems
He, Jiguang; Wymeersch, Henk; Kong, Long UL et al

in 2020 IEEE 91st Vehicular Technology Conference (VTC2020-Spring) (2020)

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large ... [more ▼]

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large bandwidth and inherently high angular resolution. In this paper, we introduce the newly invented concept, large intelligent surface (LIS), to mmWave positioning systems, study the theoretical performance bounds (i.e., Cramér-Rao lower bounds) for positioning, and evaluate the impact of the number of LIS elements and the value of phase shifters on the position estimation accuracy compared to the conventional scheme with one direct link and one non-line-of-sight path. It is verified that better performance can be achieved with a LIS from the theoretical analyses and numerical study. [less ▲]

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See detailPositionPeak: Stimulating position changes during meetings
Damen, Ida; Heerkens, Lidewij; Van Den Broek, Annabel et al

in Proceedings of Conference on Human Factors in Computing Systems (2020)

In office environments, workers spend the majority of their workday sitting in a static position behind a desk or around a meeting table. Prolonged sitting time and sedentary behavior have severe negative ... [more ▼]

In office environments, workers spend the majority of their workday sitting in a static position behind a desk or around a meeting table. Prolonged sitting time and sedentary behavior have severe negative health effects. Through this explorative study, we studied how different postures can be stimulated during meetings. We designed PositionPeak: three pieces of furniture aimed at composing a 'dynamic meeting room', subtly encouraging participants to avoid static postures. We video-recorded 5 meetings (N=16) and coded the number of position changes per participant. Participants also filled out a pre- and post-questionnaire about their experience. Our findings show that PositionPeak triggers people to adopt a variety of postures. Participants on average experienced a more efficient meeting but reported physical discomfort with some objects. We discuss the influence of PositionPeak on the meetings' social dynamics, the acceptance of new conventions and design recommendations for new meeting facilities. © 2020 Owner/Author. [less ▲]

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See detailField Dependence of Magnetic Disorder in Nanoparticles
Zákutná, Dominika; Nižňanský, Daniel; Barnsley, Lester C. et al

in Physical Review X (2020), 10

The performance characteristics of magnetic nanoparticles toward application, e.g., in medicine and imaging or as sensors, are directly determined by their magnetization relaxation and total magnetic ... [more ▼]

The performance characteristics of magnetic nanoparticles toward application, e.g., in medicine and imaging or as sensors, are directly determined by their magnetization relaxation and total magnetic moment. In the commonly assumed picture, nanoparticles have a constant overall magnetic moment originating from the magnetization of the single-domain particle core surrounded by a surface region hosting spin disorder. In contrast, this work demonstrates the significant increase of the magnetic moment of ferrite nanoparticles with an applied magnetic field. At low magnetic field, the homogeneously magnetized particle core initially coincides in size with the structurally coherent grain of 12.8(2) nm diameter, indicating a strong coupling between magnetic and structural disorder. Applied magnetic fields gradually polarize the uncorrelated, disordered surface spins, resulting in a magnetic volume more than 20% larger than the structurally coherent core. The intraparticle magnetic disorder energy increases sharply toward the defect-rich surface as established by the field dependence of the magnetization distribution. In consequence, these findings illustrate how the nanoparticle magnetization overcomes structural surface disorder. This new concept of intraparticle magnetization is deployable to other magnetic nanoparticle systems, where the in-depth knowledge of spin disorder and associated magnetic anisotropies are decisive for a rational nanomaterials design. [less ▲]

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See detailSidelobe Performance Analysis of Noise Waveforms Considering the Doppler Mismatch
Tedgue Beltrao, Gabriel UL; Pralon, Leandro; Alaeekerahroodi, Mohammad UL et al

in Proceedings of the 21st International Radar Symposium (IRS), Warsaw, Poland, 2020 (2020)

Waveform design and optimization algorithms generally assume a zero-Doppler ideal case to reach an optimum or satisfactory solution in terms of the matched filter output. Therefore, its performance is ... [more ▼]

Waveform design and optimization algorithms generally assume a zero-Doppler ideal case to reach an optimum or satisfactory solution in terms of the matched filter output. Therefore, its performance is usually characterized only in terms of the resultant waveforms autocorrelation function, neglecting the practical situation in which the received signal is modulated by the target’s Doppler shift. Within this context, this work investigates the Doppler mismatch effects in the Integrated Sidelobe Level (ISL) performance of previously designed/optimized noise waveforms. The analysis has shown that, despite much better results for steady targets, the increasing Doppler mismatch reduces the ISL performance of optimized waveforms, until similar levels achieved when no optimization is performed. To address that, a subpulse Doppler processing approach is also considered, and the results have shown that, besides increasing the Doppler tolerance, it has also increased the optimized waveform robustness to the Doppler mismatch, reducing the resultant ISL loss and thus extending its applicability. [less ▲]

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See detailInterrogating helical nanorod self-assembly with fractionated cellulose nanocrystal suspensions
Honorato-Rios, Camila; Lagerwall, Jan UL

in Communications Materials (2020), 1

The helical self-assembly of cholesteric liquid crystals is a powerful motif in nature, enabling exceptional performance in many biological composites. Attempts to mimic these remarkable materials by ... [more ▼]

The helical self-assembly of cholesteric liquid crystals is a powerful motif in nature, enabling exceptional performance in many biological composites. Attempts to mimic these remarkable materials by drying cholesteric colloidal nanorod suspensions often yield films with a non-uniform mosaic-like character, severely degrading optical and mechanical properties. Here we show---using the example of cellulose nanocrystals---that these problems are due to rod length dispersity: uncontrolled phase separation results from a ... [less ▲]

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See detailBordertextures – vers une approche transdisciplinaire des frontières. Un rapport d’atelier
Weier, Sebastian; Fellner, Astrid; Frenk, Joachim et al

in Hamez, Grégory; Defays, Jean-Marc (Eds.) Réalités, perceptions et représentations des frontières. L’espace transfrontalier de la Grande Région Sarre-Lor-Lux (2020)

La présente contribution est conçue sous forme d'un rapport d'atelier et donne un premier aperçu concernant le développement d'une approche des phénomènes de frontières et d'espaces frontaliers sur la ... [more ▼]

La présente contribution est conçue sous forme d'un rapport d'atelier et donne un premier aperçu concernant le développement d'une approche des phénomènes de frontières et d'espaces frontaliers sur la base des études culturelles. Cette approche tente d'être plus large que celle correspondant aux perspectives jusqu'à présent préconisées par les sciences sociales et appréhende les phénomènes des frontières et des espaces frontaliers en tant qu'entités composées de différentes pratiques et différents discours faisant référence aux frontières et aux différences. Ces entités comprises au sens de bordertextures sont exemplairement illustrées à travers des phénomènes concernant la frontière entre les États-Unis et le Mexique, la frontière franco-allemande et l'Irlande du Nord et elles sont déclinées en différentes dimensions d'analyse. Parmi ces dernières, la corporéalité, la spatialité et la matérialité figurent parmi les approches heuristiques des bordertextures que la présente contribution aborde à titre d'exemples. L'approche relativise la perspective largement répandue correspondant à une conception territoriale de la frontière pour élargir la palette des perspectives analytiques et celles des domaines analysés au sein des Border Studies. [less ▲]

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See detailMachine Learning Meets Quantum Physics
Schütt, Kristof T; Chmiela, Stefan; von Lilienfeld, O Anatole et al

in Lecture Notes in Physics (2020)

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See detailAutomatic Testing and Improvement of Machine Translation
Sun, Zeyu; Zhang, Jie; Harman, Mark et al

in International Conference on Software Engineering (ICSE) (2020)

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See detailThe coronavirus (COVID‐19) fatality risk perception of US adult residents in March and April 2020
Niepel, Christoph UL; Kranz, Dirk; Borgonovi, Francesca et al

in British Journal of Health Psychology (2020)

The study compares empirical results on the coronavirus SARS‐CoV‐2 (causing COVID‐19) fatality risk perception of US adult residents stratified for age, gender, and race in mid‐March 2020 (N1 = 1,182) and ... [more ▼]

The study compares empirical results on the coronavirus SARS‐CoV‐2 (causing COVID‐19) fatality risk perception of US adult residents stratified for age, gender, and race in mid‐March 2020 (N1 = 1,182) and mid‐April 2020 (N2 = 953). While the fatality risk perception has increased from March 2020 to April 2020, our findings suggest that many US adult residents severely underestimated their absolute and relative fatality risk (i.e., differentiated for subgroups defined by pre‐existing medical conditions and age) at both time points compared to current epidemiological figures. These results are worrying because risk perception, as our study indicates, relates to actual or intended health‐protective behaviour that can reduce SARS‐CoV‐2 transmission rates. [less ▲]

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See detailImplicit motives and children's salivary cortisol reactivity to an adapted version of the Trier Social Stress Test for Children (TSST-C)
Spengler, Benedikt; Hofer, Jan; Busch, Holger et al

in Personality and Individual Differences (2020), 162

This research addresses the interplay between two implicit motives, that are power (nPow) and affiliation (nAff), and the cortisol reactivity (CR) to a psychosocial stressor (an adaption of the Trier ... [more ▼]

This research addresses the interplay between two implicit motives, that are power (nPow) and affiliation (nAff), and the cortisol reactivity (CR) to a psychosocial stressor (an adaption of the Trier Social Stress Test for Children; TSST-C; Buske-Kirschbaum et al., 1997) in 89 healthy children (45 female; Mage = 7.74, SDAge = 0.46). We assessed implicit motives by a 6-image Picture Story Exercise (PSE) and cortisol by 6 saliva samples. As hypothesized, the procedure triggered a significant cortisol reaction, F(1.44, 127.05Greenhouse-Geisser) = 8.22, p = .002, η²part = 0.09. Contrary to our hypothesis, children high in nPow showed no significant increase in CR (β = 0.06, p = .60). However, our results were in line with the findings of Wegner, Schüler, and Budde (2014) that a high implicit affiliation motive is associated with an attenuated CR (β = −0.21, p = .05). Perspectives for future research on implicit motives and children's CR to psychosocial stress are discussed. [less ▲]

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See detailTopological network measures for drug repositioning.
Badkas, Apurva UL; De Landtsheer, Sébastien; Sauter, Thomas UL

in Briefings in bioinformatics (2020)

Drug repositioning has received increased attention since the past decade as several blockbuster drugs have come out of repositioning. Computational approaches are significantly contributing to these ... [more ▼]

Drug repositioning has received increased attention since the past decade as several blockbuster drugs have come out of repositioning. Computational approaches are significantly contributing to these efforts, of which, network-based methods play a key role. Various structural (topological) network measures have thereby contributed to uncovering unintuitive functional relationships and repositioning candidates in drug-disease and other networks. This review gives a broad overview of the topic, and offers perspectives on the application of topological measures for network analysis. It also discusses unexplored measures, and draws attention to a wider scope of application efforts, especially in drug repositioning. [less ▲]

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