Migration in later life: evidence from the British Household Panel Study

This article uses data from the British Household Panel Study over the period 1991 - 2007 to examine the factors associated with residential mobility among people aged 50 and over. In line with earlier research, the likelihood of migrating, that is, changing address, is found to vary according to the demographic and socio-economic characteristics of the older person. Those in late middle age (50-59) and the oldest-old (90 and over) were most likely to move. Migration was also strongly associated with changes in partnership, health and economic status during the last 12 months, highlighting the importance of seeing migration within a life course context with certain life course events such as divorce, widowhood or retirement being important triggers for prompting a move. As divorce and remarriage become more common in later life, 'relationship driven migration' is likely to become more important, adding a new category to the classical typology of later life migration.     

The changing demography of mid-life, from the 1980s to the 2000s

This article examines changes between 1984 and 2007 in the demographic and socio-economic circumstances of British men and women in mid-life. Changing living arrangements in mid-life reflect historical changes in the occurrence and timing of life events such as marriage and parenthood, as well as increased longevity. In order to place mid-life in this wider demographic context, the article first reviews changes over time in kin availability across the adult life course using the British Household Panel Survey (2001) and Understanding Society (2009). The article goes on to use data from the General Household Survey (1984-2007) to document shifts over time in living arrangements for those aged 20- 79. In the final part of the article we focus specifically on those aged between 45 and 64 and examine how their characteristics in terms of marital status, educational attainment, activity status and housing tenure have changed over the past quarter century.     

Genomic and functional adaptation in surface ocean planktonic prokaryotes

The understanding of marine microbial ecology and metabolism has been hampered by the paucity of sequenced reference genomes. To this end, we report the sequencing of 137 diverse marine isolates collected from around the world. We analysed these sequences, along with previously published marine prokaryotic genomes, in the context of marine metagenomic data, to gain insights into the ecology of the surface ocean prokaryotic picoplankton (0.1-3.0?μm size range). The results suggest that the sequenced genomes define two microbial groups: one composed of only a few taxa that are nearly always abundant in picoplanktonic communities, and the other consisting of many microbial taxa that are rarely abundant. The genomic content of the second group suggests that these microbes are capable of slow growth and survival in energy-limited environments, and rapid growth in energy-rich environments. By contrast, the abundant and cosmopolitan picoplanktonic prokaryotes for which there is genomic representation have smaller genomes, are probably capable of only slow growth and seem to be relatively unable to sense or rapidly acclimate to energy-rich conditions. Their genomic features also lead us to propose that one method used to avoid predation by viruses and/or bacterivores is by means of slow growth and the maintenance of low biomass.     

Recent decline in the global land evapotranspiration trend due to limited moisture supply

More than half of the solar energy absorbed by land surfaces is currently used to evaporate water. Climate change is expected to intensify the hydrological cycle and to alter evapotranspiration, with implications for ecosystem services and feedback to regional and global climate. Evapotranspiration changes may already be under way, but direct observational constraints are lacking at the global scale. Until such evidence is available, changes in the water cycle on land?a key diagnostic criterion of the effects of climate change and variability?remain uncertain. Here we provide a data-driven estimate of global land evapotranspiration from 1982 to 2008, compiled using a global monitoring network, meteorological and remote-sensing observations, and a machine-learning algorithm. In addition, we have assessed evapotranspiration variations over the same time period using an ensemble of process-based land-surface models. Our results suggest that global annual evapotranspiration increased on average by 7.1?±?1.0?millimetres per year per decade from 1982 to 1997. After that, coincident with the last major El Ni?o event in 1998, the global evapotranspiration increase seems to have ceased until 2008. This change was driven primarily by moisture limitation in the Southern Hemisphere, particularly Africa and Australia. In these regions, microwave satellite observations indicate that soil moisture decreased from 1998 to 2008. Hence, increasing soil-moisture limitations on evapotranspiration largely explain the recent decline of the global land-evapotranspiration trend. Whether the changing behaviour of evapotranspiration is representative of natural climate variability or reflects a more permanent reorganization of the land water cycle is a key question for earth system science.     

研究人员究竟该不该通过动物实验来拯救人类的生命?动物实验,是耶、非耶?

科学家蒂姆·唐兹(Tim Townes)小心翼翼地从笼子里抓出一只小白鼠,它挣扎着想逃出他的手心,唐兹在小白鼠的皮下注射满满一针筒试验药物.数日后他又从小白鼠身上抽取血样,望着显微镜下的血样,这位阿拉巴马州立大学的研究员满意地频频点头,他把结果记录下来.     

First records of dendrobranchiate prawns (Decapoda: Dendrobranchiata) from the Andaman Sea,India

ABSTRACT

The Andaman Sea adjoining the Indian Territory is biologically rich in terms of marine diversity. However, inadequate surveys during the post-independence era have resulted in large lacunae in data on the species composition in these waters. In this paper, we report the first observation of two species of dendrobranchiate prawns, Metapenaeopsis difficilis Crosnier, 1991 and Haliporus taprobanensis Alcock and Anderson, 1899, in the Indian seas, supplemented with notes on their morphological diagnoses, comparison with closely related species and zoogeographical distribution. Crustacean specimens were collected using trawl nets and a naturalists’ dredge on board the Fisheries Oceanography Research Vessel Sagar Sampada in the deeper offshore region between 124 and 850 m depth in the Andaman Sea during the period 2015–2017. Metapenaeopsis difficilis is distinguished by an oval-shaped thelycal plate and a low, unarmed bead-like plate on the thoracic sternum between the third pereiopods. Metapenaeopsis difficilis is previously reported from the Philippines, Indonesia, Coral Sea, New Caledonia, Marquesas Islands, and Wallis and Futuna Islands at depths between 21 and 440 m, thereby indicating its westward range extension. Haliporus taprobanensis is distinguished by a tough integument, presence of a postero-dorsal spine on the fourth pleonal somite, and smooth dorsum of the first four pleonal somites. Haliporus taprobanensis is previously reported from South Africa, Madagascar, off Sri Lanka, Indonesia, Philippines and northern Australia at depths between 300 and 1650 m.     

Determination and (re)parametrization of rational developable surfaces

The developable surface is an important surface in computer aided design, geometric modeling and industrial manufactory. It is often given in the standard parametric form, but it can also be in the implicit form which is commonly used in algebraic geometry. Not all algebraic developable surfaces have rational parametrizations. In this paper, the authors focus on the rational developable surfaces. For a given algebraic surface, the authors ?rst determine whether it is developable by geometric inspection, and then give a rational proper parametrization in the affrmative case. For a rational parametric surface, the authors also determine the developability and give a proper reparametrization for the developable surface.