Monte Carlo simulation of the exposure factor

In this paper, we simulate the exposure factor by a simple model of a flee-air ionization chamber with the Monte Carlo programme Geant4. Special emphasis is placed on the discussion of the exposure factor related to parameters of the chamber model. The reason for the variation in exposure factor with incident ray energy is also analysed in terms of reaction cross section for different types of reactions. The obtained results indicate that our simulation is accurate in the calculation of the exposure factor and can serve as a reference in designing air ionization chambers.

Maternal Lead Exposure Induces Down-regulation of Hippocampal Insulin-degrading Enzyme and Nerve Growth Factor Expression in Mouse Pups

Lead exposure is a known potential risk factor for neurodegenerative diseases such as Alzheimer’s disease （AD）. Exposure to lead during the critical phase of brain development has been linked with mental retardation and hypophrenia in later life.

Research Progress in Early-onset Colorectal Cancer

Colorectal cancer used to be a common disease among middle-aged and elderly people.In recent years,the incidence of colorectal cancer(Early-onset colorectal cancer,EOCRC)under 50 years old has increased year by year.Different from the traditional late-onset colon cancer(LOCRC),the diagnosis stage of EOCRC is mostly in the late stage,with poor cell differentiation and poor diagnosis,and there is a layer of consensus and guidance on the diagnosis,treatment or screening of EOCRC at presentation.Therefore,fully understanding the disease characteristics and risk exposure factors of EOCRC is helpful to guide early screening and treatment,which ultimately reduces the mortality of EOCRC.In this review article,we summarized the epidemiology,physiology,risk exposure factors and pathological diagnosis of EOCRC,and discussed the diagnosis and treatment prospect of EOCRC.

Prevalence and risk factors of lens opacities in rural populations living at two different altitudes in China

AIM： To investigate the prevalence of and risk factors for lens opacities in populations living at two different altitudes in China.·METHODS： A total of 813 subjects aged ≥40y in Lhasa（Tibet Autonomous Region, China. Altitude： 3658 m） and Shaoxing（Zhejiang Province, China. Altitude： 15 m） were underwent eye examinations and interviewed in this cross-sectional study. Participants＇ lens opacities were graded according to the Lens Opacities Classification System II（LOCS II） and the types of opacities with LOCS II scores ≥2 were determined. Univariate and stepwise logistic regression were used to evaluate the associations of independent risk factors with lens opacities.· RESULTS： Lens opacities were significantly more prevalent in the high-altitude than in the low-altitude area（χ2=10.54, P 〈0.001）. Lens opacities appear to develop earlier in people living at high than at low altitude. The main types of lens opacity in Lhasa and Shaoxing were mixed（23.81%） and cortical（17.87%）,respectively. Independent risk factors associated with all lens opacities were age, ultraviolet（UV） radiation exposure,and educational level. Compared with participants aged40-49 y, the risk of lens opacities increased gradually from 2 to 85 times per 10 y [odds ratio（OR）=2.168-84.731,P 〈0.05）. The risk of lens opacities was about two times greater in participants with the highest UV exposure than in those with the lowest exposure（OR=2.606, P =0.001）.Educational level was inversely associated with lensopacities; literacy deceased the risk by about 25%compared with illiteracy（OR=0.758, P =0.041）.·CONCLUSION： Old age, higher UV exposure and lower educational level are important risk factors for the development of lens opacities. Lens opacities are more prevalent among high-altitude than low-altitude inhabitants.

Comparison and harmonization of building wind loading codes among the Asia-Pacific Economies

This paper reviews wind loading codes and standards in the Asia-Pacific Region,in particular in the 15 countries and areas.A general description of wind loading model is given as a famous wind loading chain described by four variables including velocity pressure,exposure factor,pressure coefficient,and gust response factor.Through the APEC-WW Workshops and the extensive calculations for three examples of low,medium and high rise buildings,these four important variables of wind loads are evaluated and compared with statistical parameters,mean values and coefficients of variation.The main results of the comparison show some differences among the 15 economies,and the reasons and further incorporation are discussed and suggested.