Understanding the influence of past land use changes on climate is needed to improve regional projections of future climate change and inform debates about the tradeoffs associated with land use decisions. The effects of rapid expansion of irrigated area in the 20th century has remained unclear relative to other land use changes, such as urbanization, that affected a similar total land area. Using spatial and temporal variations in temperature and irrigation extent observed in California, we show that irrigation expansion has had a large cooling effect on summertime average daily daytime temperatures (-0.14 degrees C to -0.25 degrees C per decade), which corresponds to an estimated cooling of -1.8 degrees C to -3.2 degrees C since the introduction of irrigation practices. Irrigation has negligible effects on nighttime temperatures, leading to a net cooling effect of irrigation on climate (-0.06 degrees C to -0.19 degrees C per decade). Stabilization of irrigated area has occurred in California since 1980 and is expected in the near future for many irrigated regions. The suppression of past human-induced greenhouse warming by increased irrigation is therefore likely to slow in the future, and a potential decrease in irrigation may even contribute to a more rapid warming. Changes in irrigation alone are not expected to influence broad-scale temperatures, but they may introduce large uncertainties in climate projections for irrigated agricultural regions, which provide approximately 40% of global food production.
The purpose of the investigation was to monitor changes in the labour market situation for dentists who received authorization to practise dentistry in Norway during the years 1972-1975. Data was collected by postal questionnaire during April/May of the year following authorization, except for the 1972 cohort, which was contacted the second year after authorization. A 92-95 per cent response rate was achieved using one follow-up (Table 1). The percentage of respondents who waited 8 weeks or more to acquire a job in dentistry increased from 15 for those authorized in 1972 to 36 for the 1975 group (Table 3). The proportion of dentists who took paid employment other than dentistry, increased from just over 3 per cent for the 1973 to 14 per cent for the 1975 cohort (Table 4). This development has occured despite a decrease in the number of dentists receiving authorization each year and has resulted in a limited emigration of dentists. It is suggested that the favourable supply of dentists in relation to existing demand for dental services presents an ideal opportunity for attempting to solve dental health problems which have received inadequate attention in the past.
Predictions of the effects of global warming suggest that climate change may have large impacts on ecosystems. The length of the growing season is predicted to increase in response to increasing global temperatures. The object of this study was to evaluate different indices used for calculating the thermal growing season for the Greater Baltic Area (GBA). We included established indices of growing season start, end and length, as well as new and modified indices. Based on the results, the GBA can be divided into a maritime western part and a more continental eastern part, with the western part reacting more sensitively to the use of different indices. The eastern part is more stable, but even here the index-to-index differences are large. It was found that including or excluding a frost criterion had a significant influence on the initiation of the growing season in the western, maritime, parts of the GBA. Frost has not the same importance for the end of the growing season. However, some end indices can result in a "never ending" growing season. When looking at twentieth century trends in growing season parameters, it was found that, when averaged over the whole GBA, there was little difference in trends depending on the indices used. The general mean trend in the GBA for the twentieth century discloses an earlier onset of c. 12 days, a delayed end of c. 8 days and consequently a lengthening of the growing season of about 20 days.
Following the example of other Canadian provinces, those in Atlantic Canada are affected, albeit to a lesser degree, by the increase in the number of persons aged 65 or over, a trend that we can define as gerontogrowth. In addition, this region of Canada seems particularly affected by the trend of an aging population, that is, the rise in the proportion of people in the total population aged 65 or more. For example, on a national scale, New Brunswick is the third oldest province according to the last five-year period (2001-2006), having advanced from the fourth position it held between 1981 and 2001 and from the fifth position occupied between 1971 and 1981. In addition, these trends evolve in different manners in different places, contrasts that are strongest at the regional and local level. The goal of this article is to examine the strength of these disparities during the period 1981 to 2006 and to identify some potential solutions for a territorial development strategy for seniors.
This paper is based on work done on accumulated career doses. The data are taken from the National Dose Registry and consist of accumulated doses to the monitored workforce from the years 1970, 1975, 1980, 1985, and 1990. Four broad occupational categories are analyzed: medicine, nuclear power, uranium processing (including mining, milling, refining, and fuel fabrication), and industry. Two- and three-dimensional bar charts are used to display workforce sizes, collective accumulated doses, and average accumulated doses over time, broken down by career start. Lognormal plots are used to show the distribution of accumulated doses. Many trends are as could be expected, and some of those may be used for construction of statistical models for career-dose accumulation. The size and accumulated career doses in the workforces of the uranium processing category do not vary regularly with time, and in this case modeling is likely to be difficult.
The changing seasonal patterns of reported measles cases in Iceland during this century are analysed. These changes are related to increased population mobility following the development of external and internal transport links, particularly since 1945. The forging of such links has resulted in a shift in the seasonal distribution of cases from one peculiar to the local social and economic conditions in Iceland to one broadly similar to that in other countries of northern temperate latitudes.
Cites: J Theor Biol. 1966 Jul;11(2):207-115965486
Cites: Am J Epidemiol. 1979 Feb;109(2):103-23218446