Significant drivers of growth in Africa

We employ bootstrap techniques in a production frontier framework to provide statistical inference for each component in the decomposition of labor productivity growth, which has essentially been ignored in this literature. We show that only two of the four components (efficiency changes and human capital accumulation) have significantly contributed to growth in Africa. Although physical capital accumulation is the largest force, it is not statistically significant on average. Thus, ignoring statistical significance would falsely identify physical capital accumulation as a major driver of growth in Africa when it is not

Non-steady-state calcium handling in failing hearts from the spontaneously hypertensive rat

It is generally agreed that changes in Ca(2+) cycling are often associated with heart failure, yet the impact of these changes on a beat-to-beat basis remains unclear. Measurements of isometric force and [Ca(2+)](i) were made at 37°C in left ventricular trabeculae from failing spontaneously hypertensive rat (SHR) hearts, and their normotensive Wistar-Kyoto (WKY) controls. At 1 Hz, peak stress was reduced in SHR (14.5 ± 2.4 mN mm(-2) versus 22.5 ± 6.7 mN mm⁻² for WKY), although the Ca(2+) transients were bigger (peak [Ca(2+)](i) 0.60 ± 0.08 μM versus 0.38 ± 0.03 μM for WKY) with a slower decay of fluorescence (time constant 0.105 ± 0.005 s versus 0.093 ± 0.002 s for WKY). To probe dynamic Ca(2+) cycling, two experimental protocols were used to potentiate force: (1) an interval of 30 s rest, and (2) a 30-s train of paired-pulses, and the recirculation fraction (RF) calculated for recovery to steady-state. No difference was found between rat strains for RF calculated from either peak force or Ca(2+), although the RF was dependent on potentiation protocol. Since SR uptake is slower in SHR, the lack of change in RF must be due to a parallel decrease in trans-sarcolemmal Ca(2+) extrusion. This view was supported by a slower decay of caffeine-induced Ca(2+) transients in SHR trabeculae. Confocal analysis of LV free wall showed t-tubules were distorted in SHR myocytes, with reduced intensity of NCX and SERCA2a labelling in comparison to WKY

The DNA sequence of the human X chromosome

The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence