Off-Diagonal Deformations of Kerr Metrics and Black Ellipsoids in Heterotic Supergravity

Geometric methods for constructing exact solutions of motion equations with first order $\alpha ^{\prime}$ corrections to the heterotic supergravity action implying a non-trivial Yang-Mills sector and six dimensional, 6-d, almost-K\"ahler internal spaces are studied. In 10-d spacetimes, general parametrizations for generic off-diagonal metrics, nonlinear and linear connections and matter sources, when the equations of motion decouple in very general forms are considered. This allows us to construct a variety of exact solutions when the coefficients of fundamental geometric/physical objects depend on all higher dimensional spacetime coordinates via corresponding classes of generating and integration functions, generalized effective sources and integration constants. Such generalized solutions are determined by generic off-diagonal metrics and nonlinear and/or linear connections. In particular, as configurations which are warped/compactified to lower dimensions and for Levi-Civita connections. The corresponding metrics can have (non) Killing and/or Lie algebra symmetries and/or describe (1+2)-d and/or (1+3)-d domain wall configurations, with possible warping nearly almost-K\"ahler manifolds, with gravitational and gauge instantons for nonlinear vacuum configurations and effective polarizations of cosmological and interaction constants encoding string gravity effects. A series of examples of exact solutions describing generic off-diagonal supergravity modifications to black hole/ ellipsoid and solitonic configurations are provided and analyzed. We prove that it is possible to reproduce the Kerr and other type black solutions in general relativity (with certain types of string corrections) in 4-d and to generalize the solutions to non-vacuum configurations in (super) gravity/ string theories.Comment: latex2e, 44 pages with table of content, v2 accepted to EJPC with minor typos modifications requested by editor and referee and up-dated reference

From Davydov solitons to decoherence-free subspaces: self-consistent propagation of coherent-product states

The self-consistent propagation of generalized $D_{1}$ [coherent-product] states and of a class of gaussian density matrix generalizations is examined, at both zero and finite-temperature, for arbitrary interactions between the localized lattice (electronic or vibronic) excitations and the phonon modes. It is shown that in all legitimate cases, the evolution of $D_{1}$ states reduces to the disentangled evolution of the component $D_{2}$ states. The self-consistency conditions for the latter amount to conditions for decoherence-free propagation, which complement the $D_{2}$ Davydov soliton equations in such a way as to lift the nonlinearity of the evolution for the on-site degrees of freedom. Although it cannot support Davydov solitons, the coherent-product ansatz does provide a wide class of exact density-matrix solutions for the joint evolution of the lattice and phonon bath in compatible systems. Included are solutions for initial states given as a product of a [largely arbitrary] lattice state and a thermal equilibrium state of the phonons. It is also shown that external pumping can produce self-consistent Frohlich-like effects. A few sample cases of coherent, albeit not solitonic, propagation are briefly discussed.Comment: revtex3, latex2e; 22 pages, no figs.; to appear in Phys.Rev.E (Nov.2001

Targets for high repetition rate laser facilities: Needs, challenges and perspectives

A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10Ã\u82 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: Dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities

Inferring transient dynamics of human populations from matrix non-normality

This is the final version of the article. Available from Springer Verlag via the DOI in this record.In our increasingly unstable and unpredictable world, population dynamics rarely settle uniformly to long-term behaviour. However, projecting period-by-period through the preceding fluctuations is more data-intensive and analytically involved than evaluating at equilibrium. To efficiently model populations and best inform policy, we require pragmatic suggestions as to when it is necessary to incorporate short-term transient dynamics and their effect on eventual projected population size. To estimate this need for matrix population modelling, we adopt a linear algebraic quantity known as non-normality. Matrix non-normality is distinct from normality in the Gaussian sense, and indicates the amplificatory potential of the population projection matrix given a particular population vector. In this paper, we compare and contrast three well-regarded metrics of non-normality, which were calculated for over 1000 age-structured human population projection matrices from 42 European countries in the period 1960 to 2014. Non-normality increased over time, mirroring the indices of transient dynamics that peaked around the millennium. By standardising the matrices to focus on transient dynamics and not changes in the asymptotic growth rate, we show that the damping ratio is an uninformative predictor of whether a population is prone to transient booms or busts in its size. These analyses suggest that population ecology approaches to inferring transient dynamics have too often relied on suboptimal analytical tools focussed on an initial population vector rather than the capacity of the life cycle to amplify or dampen transient fluctuations. Finally, we introduce the engineering technique of pseudospectra analysis to population ecology, which, like matrix non-normality, provides a more complete description of the transient fluctuations than the damping ratio. Pseudospectra analysis could further support non-normality assessment to enable a greater understanding of when we might expect transient phases to impact eventual population dynamics.This work was funded by Wellcome Trust New Investigator 103780 to TE, who is also funded by NERC Fellowship NE/J018163/1. JB gratefully acknowledges the ESRC Centre for Population Change ES/K007394/1

The effect of hydroxychloroquine on activities of daily living and hand function in systemic sclerosis: results from an analysis of the EUSTAR cohort

Background: To evaluate the use of hydroxychloroquine (HCQ) and its impact on the Health Assessment Questionnaire disability index(HAQ-DI) and the Cochin Hand Function Status(CHFS) in a large Systemic Sclerosis (SSc) cohort. // Methods: SSc patients from the European Scleroderma Trials and Research (EUSTAR) database treated with HCQ for at least 6 months were evaluated and compared to a matched group of SSc patients not using HCQ. Demographic and clinical data, concomitant drugs, HAQ-DI and CHFS (at least 2 evaluations) were recorded and were the outcome variables of interest. Statistical analysis was performed using propensity score matching for age, gender, disease duration, corticosteroids, immunosuppressives, vasoactive drugs in a 3:1 control: HCQ ratio. Standard descriptive statistics and Student’s t-test and Chi-square test were used to assess the propensity-matched groups. // Results: Out of 17,805 SSc patients evaluated, 468 (2.6%) used HCQ and constituted the HCQ group. Among them, 50 (10.7%) had at least a baseline and follow-up HAQ-DI evaluation and 44 (9.4%) had at least a baseline and follow-up CHFS evaluation. Propensity matching assured that patients were matched for female gender (HCQ vs. control 92.0% vs. 85.3%), mean age (49.8 vs. 50.0 years) disease duration (8.3 vs. 9.1 years), limited disease (55.3 vs. 62.6%) as well as background medications (all P > 0.1). We did not find any significant differences among the two groups in the change of HAQ-DI or CHFS, over up to 365 days (all P > 0.05). // Conclusions: Results from the EUSTAR registry showed that HCQ was used by 2.6% of SSc patients. HCQ use did not improve the HAQ-DI, or CHFS when comparing HCQ users to non-HCQ users

Photonic quantum information processing: a review

Photonic quantum technologies represent a promising platform for several applications, ranging from long-distance communications to the simulation of complex phenomena. Indeed, the advantages offered by single photons do make them the candidate of choice for carrying quantum information in a broad variety of areas with a versatile approach. Furthermore, recent technological advances are now enabling first concrete applications of photonic quantum information processing. The goal of this manuscript is to provide the reader with a comprehensive review of the state of the art in this active field, with a due balance between theoretical, experimental and technological results. When more convenient, we will present significant achievements in tables or in schematic figures, in order to convey a global perspective of the several horizons that fall under the name of photonic quantum information.Comment: 36 pages, 6 figures, 634 references. Updated version with minor changes and extended bibliograph

The effect of hydroxychloroquine on activities of daily living and hand function in systemic sclerosis: results from an analysis of the EUSTAR cohort

Background To evaluate the use of hydroxychloroquine (HCQ) and its impact on the Health Assessment Questionnaire disability index(HAQ-DI) and the Cochin Hand Function Status(CHFS) in a large Systemic Sclerosis (SSc) cohort. Methods SSc patients from the European Scleroderma Trials and Research (EUSTAR) database treated with HCQ for at least 6 months were evaluated and compared to a matched group of SSc patients not using HCQ. Demographic and clinical data, concomitant drugs, HAQ-DI and CHFS (at least 2 evaluations) were recorded and were the outcome variables of interest. Statistical analysis was performed using propensity score matching for age, gender, disease duration, corticosteroids, immunosuppressives, vasoactive drugs in a 3:1 control: HCQ ratio. Standard descriptive statistics and Student’s t-test and Chi-square test were used to assess the propensity-matched groups. Results Out of 17,805 SSc patients evaluated, 468 (2.6%) used HCQ and constituted the HCQ group. Among them, 50 (10.7%) had at least a baseline and follow-up HAQ-DI evaluation and 44 (9.4%) had at least a baseline and follow-up CHFS evaluation. Propensity matching assured that patients were matched for female gender (HCQ vs. control 92.0% vs. 85.3%), mean age (49.8 vs. 50.0 years) disease duration (8.3 vs. 9.1 years), limited disease (55.3 vs. 62.6%) as well as background medications (all P > 0.1). We did not find any significant differences among the two groups in the change of HAQ-DI or CHFS, over up to 365 days (all P > 0.05). Conclusions Results from the EUSTAR registry showed that HCQ was used by 2.6% of SSc patients. HCQ use did not improve the HAQ-DI, or CHFS when comparing HCQ users to non-HCQ us

Pandemic Boredom: Little Evidence That Lockdown-Related Boredom Affects Risky Public Health Behaviors Across 116 Countries

Some public officials have expressed concern that policies mandating collective public health behaviors (e.g., national/regional "lockdown ") may result in behavioral fatigue that ultimately renders such policies ineffective. Boredom, specifically, has been singled out as one potential risk factor for noncompliance. We examined whether there was empirical evidence to support this concern during the COVID-19 pandemic in a large cross-national sample of 63,336 community respondents from 116 countries. Although boredom was higher in countries with more COVID-19 cases and in countries that instituted more stringent lockdowns, such boredom did not predict longitudinal within-person decreases in social distancing behavior (or vice versa; n = 8,031) in early spring and summer of 2020. Overall, we found little evidence that changes in boredom predict individual public health behaviors (handwashing, staying home, self-quarantining, and avoiding crowds) over time, or that such behaviors had any reliable longitudinal effects on boredom itself. In summary, contrary to concerns, we found little evidence that boredom posed a public health risk during lockdown and quarantine

‘We are all in the same boat’: How societal discontent affects intention to help during the COVID-19 pandemic

The coronavirus disease 2019 (COVID-19) pandemic has caused a global health crisis. Consequently, many countries have adopted restrictive measures that caused a substantial change in society. Within this framework, it is reasonable to suppose that a sentiment of societal discontent, defined as generalized concern about the precarious state of society, has arisen. Literature shows that collectively experienced situations can motivate people to help each other. Since societal discontent is conceptualized as a collective phenomenon, we argue that it could influence intention to help others, particularly those who suffer from coronavirus. Thus, in the present study, we aimed (a) to explore the relationship between societal discontent and intention to help at the individual level and (b) to investigate a possible moderating effect of societal discontent at the country level on this relationship. To fulfil our purposes, we used data collected in 42 countries (N = 61,734) from the PsyCorona Survey, a cross-national longitudinal study. Results of multilevel analysis showed that, when societal discontent is experienced by the entire community, individuals dissatisfied with society are more prone to help others. Testing the model with longitudinal data (N = 3,817) confirmed our results. Implications for those findings are discussed in relation to crisis management. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement