Quasi-independent triangular contingency tables.

The model of quasi-independence in a triangular contingency table is parametrised in a way which is both easy to interpret probabilistically, and easy to analyse.     

Increment-decrement tables for human reproduction.

An increment-decrement life table method has been applied to family building patterns among women. Age at the occurrence of a specified birth is considered the principal duration variable. The data base used to illustrate the table method was a sample of currently married women from the 1965 U.S. National Fertility Survey. It is possible to calculate the average number of births occurring to a woman of given parity during any specific age interval. The average number of births occurring before age 25 for women who are childless at age 20 can be obtained by completing the reproductive history for 100,000 childless 20 year old women through age 25. In a sample of 86,242 first births, 51,425 second births, 17,485 third births, and 4755 fourth births for an average of 1.6 children before age 25. Summary measures such as average parity attained within a given age interval and the conditional probability of transition from one parity to the next in a given age interval can be calculated from a table providing the age intervals do not involve fractions of the age groups used in constructing the abridged table.     

Analysis of life tables with grouping and withdrawals.

A number of individuals is observed at the beginning of a period. At the end of the period the number is surviving, the number who have died and the number who have withdrawn are noted. From these three numbers it is required to estimate the death rate for the period. All relevant quantities are supposed independent and identically distributed for the individuals. The likelihood is calculated and found to depend on two parameters, other than the death rate, and to be unidenttifiable so that no consistent estimators exist. For large numbers, the posterior distribution of the death rate is approximated by a normal distribution whose mean is the root of a quadratic equation and whose variance is the sum of two terms; the first is proportional to the reciprocal of the number of individuals, as usually happens with a consistent estimator; the second does not tend to zero and depends on initial opinions about one of the nuisance parameters. The paper is a simple exercise in the routine use of coherent, Bayesian methodology. Numerical calucations illustrate the results.     

The prion 2018 round tables (I): the structure of PrPSc

Understanding the structure of PrP^Sc is without doubt a sine qua non to understand not only PrP^Sc propagation, but also critical features of that process such as the strain phenomenon and transmission barriers. While elucidation of the PrP^Sc structure has been full of difficulties, we now have a large amount of structural information that allows us to begin to understand it. This commentary article summarizes a round table that took place within the Prion 2018 meeting held in Santiago de Compostela to discuss the state of the art in this matter. Two alternative models of PrP^Sc exist: the PIRIBS and the 4-rung β-solenoid models. Both of them have relevant features. The 4-rung β-solenoid model agrees with experimental constraints of brain derived PrP^Sc obtained from cryo-EM and X-ray fiber diffraction studies. Furthermore, it allows facile accommodation of the bulky glycans that decorate brain-derived PrP^Sc. On the other hand, the infectious PrP23-144 amyloid exhibits a PIRIBS architecture. Perhaps, both types of structure co-exist.     

Large tables

The traditional exploration of large contingency tables leads to multiple comparisons with the inherent generation of chance associations. To allow for this, a simple empirical Bayesian approach is used here to derive estimates of association 'shrunk' towards a global mean. Estimates are displayed on ordered normal plots, to allow visual detection of outliers, with the addition of 'guide rails', derived from simulation, to facilitate their detection. The methods, and the interpretation of results, are illustrated using a large table of occupations for cancer registrations in England and Wales for 1971-90.     

云龟履硕蚧的生物学及其自然种群生命表

云龟履硕蚧Perissopneumonxyliae (Ayyar)主要分布于云南玉溪、曲靖、楚雄等地 (州 )的板栗产区 ,是板栗的主要害虫之一。该虫在云南易门每年发生 1代 ,幼虫有 3龄 ,以 3龄若虫在树皮缝隙或树干基部越冬。高温、雨水冲刷、瓢虫捕食、紫胶白虫Eublemmaamabilis捕食和白蜡虫花翅跳小蜂Microterysericeri寄生是其主要的自然控制因子