Multistate Models for the Recovery Process in the Covid-19 Context:An Empirical Study of Chinese Enterprises

The Covid-19 pandemic has severely affected enterprises worldwide.It is thus of practical significance to study the process of enterprise recovery from Covid-19.However,the research on the effects of relevant determinants of business recovery is limited.This article presents a multistate modeling framework that considers the determinants,recovery time,and transition likelihood of Chinese enterprises by the state of those enterprises as a result of the pandemic(recovery state),with the help of an accelerated failure time model.Empirical data from 750 enterprises were used to evaluate the recovery process.The results indicate that the main problems facing non-manufacturing industries are supply shortages and order cancellations.With the increase of supplies and orders,the probability of transition between different recovery states gradually increases,and the recovery time of enterprises becomes shorter.For manufacturing industries,the factors that hinder recovery are more complex.The main problems are employee panic and order cancellations in the initial stage,employee shortages in the middle stage,and raw material shortages in the full recovery stage.This study can provide a reference for enterprise recovery in the current pandemic context and help policymakers and business managers take necessary measures to accelerate recovery.

Covariates of Disability-Profile Transitions in Older People Living at Home

The objective of this study was to explore the relationship of sociodemographic, clinical, and health-services use-related variables with transitions between disability-based profiles. In a longitudinal study of 1386 people aged 75 and over living in the community at baseline, disabilities were assessed annually for up to four years with the Functional Autonomy Measurement System (SMAF), which generates 14 Iso-SMAF profiles. These profiles are grouped into 4 disability states, which are predominant alterations in instrumental activities of daily living (IADLs), mobility, mental functions as well as severe and mixed disabilities. Continuous-time, multi-state Markov modeling was used to identify the factors associated with transitions made by older people between these states and to institutionalization and death. Greater age and receiving help for ADL were associated with four transitions, while altered cognitive functions and hospitalization were associated with three, all involving more decline or less recovery. From mild IADL profiles, men have a higher risk of transitioning to intermediate predominantly mental profiles, while women are at higher risk of transitioning to intermediate predominantly mobility profiles. Unmet needs are associated with deterioration, from mild IADL to intermediate predominantly mobility profiles. These results help understanding the complex progression of disabilities in older people.

Optimal planning of stand-alone microgrids incorporating reliability

This paper proposes a new method for the planning of stand-alone microgrids.By means of clustering techniques,possible operating scenarios are obtained considering the daily patterns of wind and load profiles.Then,an approximate analytical model for reliability evaluation of battery energy storage system is developed in terms of the diverse scenarios,along with multistate models for wind energy system and diesel generating system.An optimal planning model is further illustrated based on the scenarios and the reliability models,with the objective of minimizing the present values of the costs occurring within the project lifetime,and with the constraints of system operation and reliability.Finally,a typical stand-alone microgrid is studied to verify the efficiency of the proposed method.

Survival and maturation rates of the African rodent, Mastomys natalensis: density-dependence and rainfall

Survival and maturation rates of female Mastomys natalensis were analysed based on a ten-year monthlycapture-recapture data set. We investigated whether direct and delayed density dependent and independent (rainfall)variables accounted for the considerable variation in demographic traits. It was estimated that seasonal and annualcovariates accounted for respectively 29 and 26% of the total variation in maturation rates and respectively 17 and11% of the variation in survival rates. Explaining the between-year differences in maturation rates with annual pastrainfall or density did not improve the model fit. On the other hand we showed that maturation rates were correlatednegatively with density the previous month and positively to cumulative rainfall over the past three months.Survival estimates of both adults and subadults varied seasonally, with higher estimates during the increase phase(dry season). The subadults were characterised by a very high survival rate (> 0.95) during this phase. In thedecrease phase only minor differences were found between survival rates of subadults and adults. We found that39% of the between-year variation in survival can be explained by accumulated rainfall over the past year.