大连市银杏叶斑病病原菌鉴定

银杏(Ginkgo biloba L.)是常见的城市园林观赏绿化树种,并具有极高的材用、食用和药用价值.近年来,大连市银杏树发生了一种不明病因且较为严重的叶斑病,查明病因、为病害防治提供理论依据迫在眉睫.从病害发生严重区域采集叶斑病病叶样本,采用感病叶片单斑分离法,对分离菌株进行致病性测定、形态学鉴定及分子生物学鉴定等,对大连市银杏树发生的叶斑病进行了病原菌鉴定.结果表明,大连银杏叶斑病致病菌有2种,分别为链格孢属细极链格孢(Alternaria tenuissima)和链格孢(Alternaria alternata).迄今为止,细极链格孢(Alternaria tenuissima)侵染银杏导致其发生叶斑病鲜有报道.     

Estimating the changing population of the 'oldest old'

The population of England and Wales is becoming older. This poses an increasing demand for detailed data on the size an trends of the population at the oldes ages. Using the recently released Offic for National Statistics estimates of th population aged 90 and over in England and Wales, this article shows trends in the population of the oldest old and demographic causes of the rapid increase in centenarians during the twentieth century. It also presents further validation of the ON estimates of the oldest old with estimat from other data sources.     

Mortality of the 'Golden Generation': what can the ONS Longitudinal study tell us?

It is well documented that the generations born around 1930 are consistently exhibiting higher rates of mortality improvement than the generations either side of them. There is currently no evidence that these differentials are declining. In current ONS National Population Projections, it is assumed that these cohorts will continue to experience higher rates of improvement. However, it is not yet precisely clear why this is so. This article details preliminary research carried out using the ONS Longitudinal Study to try to understand better why the members of the generation born around 1930 have been enjoying higher rates of mortality improvement throughout their adult life.     

Migration trends at older ages in England and Wales

Information on the behaviour and characteristics of our rapidly growing older population is of increasing importance to policy makers, who want to ensure a good quality of life for our elderly. This article uses data from the Office for National Statistics Longitudinal Study (1971-2001) to illustrate trends in migration at older ages. It shows how the propensity to migrate differs by age, sex, marital status, living arrangements, economic resources and health in later life, amongst people aged 50 and over in England and Wales. Results show that moves at older ages are associated with changes in health and living arrangements, but also that these associations are inter-related with other factors such as age.