Model test study of frost heaving pressures in tunnels excavated in fractured rock mass in cold regions

Based on the similarity theory, taking the horseshoe, city-gate and round linings as examples, the value and distribution regularities of normal frost heaving pressures （hereinafter as frost heaving pressures） in tunnels excavated in fractured rock mass in cold regions under different constraints and freezing depths were studied by a test model. It was found that the larger the frozen depth, the larger the frost heaving pressure, and the stronger the top constraint, the larger the frost heaving pressure. For the horseshoe lining and city-gate lining, the top constraint has a greater effect on the frost heaving pressures on the arch and the inverted arch. For the round lining, the influences of the top constraint on the frost heaving pressure in all linings are almost the same. The frost heaving pressure is maximum on the city-gate lining and minimal on the round lining. The largest frost heaving pressure all occur near the foot of the inverted arch for the three kinds of lining. Thus, the test data basically coincide with the observed in situ data.

Design and Evaluation of a Differential Accelerometer for Drop-Tower Equivalence Principle Test with Rotating Masses

A differential accelerometer comprising of two rotating masses made of the same material is proposed for drop tower-based free-fall testing of the spin-spin force between the rotating mass and the Earth. The measurement is performed by placing the two concentric masses of very different momenta in a vacuum drop capsule which is falling freely in the Earth＇s gravitational field. A nonzero output of the differential aeeelerometer is an indication of possible violation of new equivalence principle （NEP）. We present the conceptual design of a modified free-fall NEP experiment which can be performed at the Belting drop tower. Design and evaluation of the differential accelerometer with a hybrid electrostatic/magnetic suspension system are presented to accommodate for operation on ground and drop-tower tests. Details specific to the measurement uncertainty are discussed to yield an NEP test accuracy of 7.2×10^-9.

Rock borehole shear tests in dam foundation of Xiangjiaba hydropower station

Xiangjiaba hydropowcr station is one of the complicated geological conditions of its dam foundation, parameters of rock masses are very important issues. To cascade power stations on the Jinsha River, China. Due to the evaluating the rock mass quality and determining the mechanical address these issues, several groups of rock borehole shear tests （RBSTs） were conducted on the black mudstone in the dam foundation of Xiangjiaba hydropower station in the second construction phase. Forty three groups of shear strengths of black mudstone samples were obtained from RBSTs, and the shear strength parameters （c and f） were calculated using the least squares method. In addition, the limitations and merits of RBST employed in the Xiangjiaba hydropower station were discussed. Test results indicate that the shear strength parameters obtained from RBST have a good correlation with the results from sotmd wave test in borehole. It is believed that RBST has a good adaptability and applicability in geotechnical engineering.

No Evidence for the Compensation Hypothesis in the Swelled Vent Frog(Feirana quadranus)

The compensation hypothesis predicts that if the left testis is defective e.g.due to developmental stress,the increased right testis serves a compensatory role,and thereby displaying testes asymmetry which can be a reliable indicator of male body condition.Here,to test the prediction of the compensation hypothesis,we analyzed difference in size between left testis and right testis and the relationship between testes asymmetry and male body condition in the swelled vent frog(Feirana quadranus).We found that the left testis was larger than right testis,displaying a significant directional asymmetry in testes size.Although testes mass was correlated with body condition,testes asymmetry was not correlated with body condition,which cannot provide evidence that the right testis had a compensatory function.Our findings suggest no evidence for the compensation hypothesis in this species due to lacking the compensatory function in right testis.

A mathematical model to predict the risk of hepatitis B infection through needle/syringe sharing in mass vaccination

Background:The Japanese Government settled a class litigation case with hepatitis B virus(HBV)carriers who claim to have been infected through needle/syringe sharing in childhood mass vaccination with a blanket compensation agreement.However,it is difficult to estimate how many of the present HBV carriers were infected horizontally from mass vaccination and how many were infected vertically from mothers.Methods:A mathematical model to predict the risk of infection through needle/syringe sharing in mass vaccination was proposed and a formula was developed.The formula was presented in a logarithmic graph enabling users to estimate how many people will be infected if a needle/syringe is shared by how many people for how many times under certain probability of infection.The formula was then applied to the historical data of mass tuberculin skin tests(TSTs)and BCG inoculation,from which a best estimate of how much needle/syringe sharing was practiced in different birth cohorts was determined.Results:For the oldest cohort born between 1951 and 1955,the prevalence of HBV carriers-0.65%at birth through vertical transmission-more than doubled in 1995(1.46%)through horizontal transmission.If the probability of infection through needle/syringe sharing is assumed to be 10%,it is theoretically likely that an average of five or more people shared a needle/syringe four times to achieve the prevalence of HBV carriers in 1995.However,for the youngest cohort born between 1981 and 1985,the effects of needle/syringe sharing were negligible because the later prevalence of HBV carriers was lower than the prevalence at birth.Conclusions:More than half of the HBV carriers born in the early 1950s might have contracted the disease by mass vaccinations.Japan’s experience needs to be shared with other countries as a caution in conducting mass vaccination programs under scarce needle/syringe supply(291 words).

SARS-COV-2 outbreak and control in Kenya - Mathematical model analysis

The coronavirus disease 2019(COVID-19)pandemic reached Kenya in March 2020 with the initial cases reported in the capital city Nairobi and in the coastal area Mombasa.As reported by the World Health Organization,the outbreak of COVID-19 has spread across the world,killed many,collapsed economies and changed the way people live since it was first reported inWuhan,China,in the end of 2019.As at the end of December 2020,it had led to over 2.8 million confirmed cases in Africa with over 67 thousand deaths.The trend poses a huge threat to global public health.Understanding the early transmission dynamics of the infection and evaluating the effectiveness of control measures is crucial for assessing the potential for sustained transmission to occur in new areas.We employed a SEIHCRD mathematical transmission model with reported Kenyan data on cases of COVID-19 to estimate how transmission varies over time.The model is concise in structure,and successfully captures the course of the COVID-19 outbreak,and thus sheds light on understanding the trends of the outbreak.The next generation matrix approach was adopted to calculate the basic reproduction number(R_(0))from the model to assess the factors driving the infection.The model illustrates the effect of mass testing on COVID-19 as well as individual self initiated behavioral change.The results have significant impact on the management of COVID-19 and implementation of prevention policies.The results from the model analysis shows that aggressive and effective mass testing as well as individual self initiated behaviour change play a big role in getting rid of the COVID-19 epidemic otherwise the rate of infection will continue to increase despite the increased rate of recovery.