Constant elevation of southern Tibet over the past 15 million years

The uplift of the Tibetan plateau, an area that is 2,000 km wide, to an altitude of about 5,000 m has been shown to modify global climate and to influence monsoon intensity. Mechanical and thermal models for homogeneous thickening of the lithosphere make specific predictions about uplift rates of the Tibetan plateau, but the precise history of the uplift of the plateau has yet to be confirmed by observations. Here we present well-preserved fossil leaf assemblages from the Namling basin, southern Tibet, dated to approximately 15 Myr ago, which allow us to reconstruct the temperatures within the basin at that time. Using a numerical general circulation model to estimate moist static energy at the location of the fossil leaves, we reconstruct the elevation of the Namling basin 15 Myr ago to be 4,689 +/- 895 m or 4,638 +/- 847 m, depending on the reference data used. This is comparable to the present-day altitude of 4,600 m. We conclude that the elevation of the southern Tibetan plateau probably has remained unchanged for the past 15 Myr.     

New ages for human occupation and climatic change at Lake Mungo,Australia

Australia's oldest human remains, found at Lake Mungo, include the world's oldest ritual ochre burial (Mungo III) and the first recorded cremation (Mungo I). Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information. Mungo III, the source of the world's oldest human mitochondrial DNA, has been variously estimated at 30 thousand years (kyr) old, 42-45 kyr old and 62 +/- 6 kyr old, while radiocarbon estimates placed the Mungo I cremation near 20-26 kyr ago. Here we report a new series of 25 optical ages showing that both burials occurred at 40 +/- 2 kyr ago and that humans were present at Lake Mungo by 50-46 kyr ago, synchronously with, or soon after, initial occupation of northern and western Australia. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40 kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world's driest inhabited continent.     

The use of growth curves in forecasting market development—a review and appraisal

The growth curves suitable for forecasting market development are identified and described. The underlying theoretical basis, if any, for their use is examined, and published examples of their applications are given. Doubt is cast on the value of long-term forecasts derived from growth curves applied to markets for consumables. The problems of choice between competing curves are demonstrated by means of some examples. The requirements that a growth curve should meet in order to be an appropriate forecasting tool are identified and illustrated. Many of the published examples of growth curve use are shown to be vulnerable to criticism under one or more of these criteria.     

Cointegration and forecast evaluation: Some lessons from National Institute Forecasts

The recent experience of macroeconomic forecasting in the United Kingdom has prompted renewed interest in the evaluation of economic forecasts. This paper uses cointegration tests to investigate what can be learnt from the forecasts produced by the National Institute of Economic and Social Research (NIESR) over the last two decades. Whilst the forecasts and outturns are found to be cointegrated, there remains evidence of systematic relationships between a number of forecast errors. Our results also fail to reject non-cointegration between different vintages of data, suggesting that considerable care should be exercised in both the choice of realisation data used and in the means by which efficiency is tested.     

Glycine absorption from the small intestines of rats after secondary infections withEimeria nieschulzi

Summary A second (challenge) infection ofEimeria nieschulzi in clinically immune rats did not produce weight gain depression but caused a decrease in the absorption of glycine from the ileum. The malabsorption due to challenge was equivalent to that caused by the primary infection which did cause weight loss.     

A DNA damage checkpoint response in telomere-initiated senescence

Most human somatic cells can undergo only a limited number of population doublings in vitro. This exhaustion of proliferative potential, called senescence, can be triggered when telomeres--the ends of linear chromosomes-cannot fulfil their normal protective functions. Here we show that senescent human fibroblasts display molecular markers characteristic of cells bearing DNA double-strand breaks. These markers include nuclear foci of phosphorylated histone H2AX and their co-localization with DNA repair and DNA damage checkpoint factors such as 53BP1, MDC1 and NBS1. We also show that senescent cells contain activated forms of the DNA damage checkpoint kinases CHK1 and CHK2. Furthermore, by chromatin immunoprecipitation and whole-genome scanning approaches, we show that the chromosome ends of senescent cells directly contribute to the DNA damage response, and that uncapped telomeres directly associate with many, but not all, DNA damage response proteins. Finally, we show that inactivation of DNA damage checkpoint kinases in senescent cells can restore cell-cycle progression into S phase. Thus, we propose that telomere-initiated senescence reflects a DNA damage checkpoint response that is activated with a direct contribution from dysfunctional telomeres.     

Control of HIV infection by IFN-α: implications for latency and a cure

Viral infections, including HIV, trigger the production of type I interferons (IFNs), which in turn, activate a signalling cascade that ultimately culminates with the expression of anti-viral proteins. Mounting evidence suggests that type I IFNs, in particular IFN-α, play a pivotal role in limiting acute HIV infection. Highly active anti-retroviral treatment reduces viral load and increases life expectancy in HIV positive patients; however, it fails to fully eliminate latent HIV reservoirs. To revisit HIV as a curable disease, this article reviews a body of literature that highlights type I IFNs as mediators in the control of HIV infection, with particular focus on the anti-HIV restriction factors induced and/or activated by IFN-α. In addition, we discuss the relevance of type I IFN treatment in the context of HIV latency reversal, novel therapeutic intervention strategies and the potential for full HIV clearance.