Stock profiling using time–frequency‑varying systematic risk measure

This study proposes a wavelets approach to estimating time–frequency-varying betas in the capital asset pricing model(CAPM)framework.The dynamic of systematic risk across time and frequency is analyzed to investigate stock risk-profile robustness.Furthermore,we emphasize the effect of an investor’s investment horizon on the robustness of portfolio characteristics.We use a daily panel of French stocks from 2012 to 2022.Results show that varying systematic risk varies in time and frequency,and that its short and long-run evolutions differ.We observe differences in short and long dynamics,indicating that a stock’s betas differently fluctuate to early announcements or signs of events.However,short-run and long-run betas exhibit similar dynamics during persistent shocks.Betas are more volatile during times of crisis,resulting in greater or lesser robustness of risk profiles.Significant differences exist in short-run and longrun risk profiles,implying a different asset allocation.We conclude that the standard CAPM assumes short-run investment.Then,investors should consider time–frequency CAPM to perform systematic risk analysis and portfolio allocation.

A Systematic Assessment of Blood Lead Level in Children and Associated Risk Factors in China

In this study, we searched multiple databases for all relevant original articles (1996-2013). To investigate blood lead levels (BLL) and possible risk factors for lead exposure among children in China A total of 388 articles met our inclusion criteria. The overall geometric mean (GM) BLL was 71 μg/L, and the prevalence of elevated BLL (EBLL, defined as BLL ≥100 μg/L) was 18.48% among children. The prevalence of EBLL remained significantly higher among boys. In children less than 6 years of age, there were significantly increasing trends in both BLL and prevalence of EBLL in an age-dependent manner. The ban on leaded gasoline significantly reduced the BLL as well as EBLL prevalence; however, children whose parents had lower educational levels or were exposed to lead in the workplace had a higher EBLL prevalence. Despite its decline over time, the average BLL among children in China remains higher than the average level most recently reported in the United States. Childhood lead poisoning remains a public health problem in China.

An Empirical Study of CAPM’s Applicability to Rare Earth Permanent Magnet Material Stocks

China has the world’s largest reserves of rare earth elements.Rare earth permanent magnet material has always been one of the popular industries in the investment market.CAPM is the basic asset-pricing model in financial economics.There are a number of studies conducted to examine the applicability of CAPM to stock markets in different industries and to investigate the modification method to improve the model’s prediction accuracy.In this study,seven leading enterprises in China’s rare earth permanent magnet material industry listed on the A-share market were selected as the research subjects.Based on CAPM,regression analysis was conducted on the monthly data from March 2016 to February 2022.The results demonstrated that using the β coefficient to explain the risk of China’s rare earth permanent magnet industry is ineffective.The ultimate benefit was less affected by market indexes but mainly by non-systematic risks.CAPM has low applicability to China’s rare earth permanent magnet material industry and requires further improvement.Nevertheless,CAPM still has some guiding significance in making enterprise comparisons and investment decisions.

Associated risk factors in the early stage of diabetic retinopathy

Background:To investigate the retinal capillary density(RCD)of the macula using optical coherence tomography angiography(OCT-A)in type 2 diabetic patients and to further determine the association with risk factors.Methods:A total of 212 eyes from 212 subjects were recruited;subjects included diabetics with no retinopathy(NDR,n=90 eyes),diabetics with mild retinopathy DR(MDR,n=36 eyes),and healthy participants(Control,n=86 eyes).All participants underwent OCT-A scanning.RCD was quantified by superficial and deep retinal capillary layers(SRCL and DRCL)from OCT-A images.Results:RCD in SRCL and DRCL was lower in NDR(P<0.001)as well as in MDR(P<0.001)when compared with control eyes.Diabetic patients were subdivided according to individual risk factors,complications related to diabetes,and hyperglycemia.Diabetic patients showed lower RCD in both the SRCL and DRCL when compared with healthy controls.Diabetics with age>55y,HbA1c>7%had significantly reduced DRCL(P<0.05)when compared with the other group of diabetics(age<55y,HbA1c<7%).Diabetics with a blood urea nitrogen(BUN)>8.2 mmol/L had significantly reduced SRCL and DRCL when compared to the other group of diabetics.Conclusions:Risk factors including older age,higher level of HbA1c,LDL-C and BUN,were associated with lower RCDs found in type 2 diabetic patients with and without mild DR by OCT-A.The impairment of retinal capillary by OCT-A may play a key role in the early monitoring of management in diabetes.