High-brightness seven-octave carrier envelope phase-stable light source

High-brightness sources of coherent and few-cycle-duration light waveforms with spectral coverage from the UV to the THz would offer unprecedented versatility and opportunities for a spectacular range of applications from bio-chemical sensing, to time-resolved and nonlinear spectroscopy, to attosecond light-wave electronics. Combinations of various sources with frequency conversion and supercontinuum generation can provide relatively large spectral coverage, but many applications require much broader spectral range and low-jitter synchronization for time-domain measurements. Here, we present a carrier-envelope-phase stable light source, seeded by a mid-IR frequency comb, with simultaneous spectral coverage across 7 optical octaves, from the UV (340 nm) into the THz (40,000 nm). Combining soliton self-compression and dispersive wave generation in an anti-resonant-reflection photonic crystal fibre with intra-pulse difference frequency generation in BaGa2GeSe6, the spectral brightness is 2-5 orders of magnitude above synchrotron sources. This enables high-dynamic-range spectroscopies and provides enticing prospects for attosecond physics and material sciences.Comment: 4 figure

Study of GABA in Healthy Volunteers: Pharmacokinetics and Pharmacodynamics

Preclinical studies show that GABA exerts anti-diabetic effects in rodent models of type 1 diabetes. Because little is known about its absorption and effects in humans, we investigated the pharmacokinetics and pharmacodynamics of GABA in healthy volunteers. Twelve subjects were subjected to an open-labeled, three-period trial involving sequential oral administration of placebo, 2 g GABA once, and 2 g GABA three times/day for 7 days, with a 7-day washout between each period. GABA was rapidly absorbed (Tmax: 0.5 ~ 1 h) with the half-life (t1/2) of 5 h. No accumulation was observed after repeated oral GABA administration for 7 days. Remarkably, GABA significantly increased circulating insulin levels in the subjects under either fasting (1.6-fold, single dose; 2.0-fold, repeated dose; p \u3c 0.01) or fed conditions (1.4-fold, single dose; 1.6-fold, repeated dose; p \u3c 0.01). GABA also increased glucagon levels only under fasting conditions (1.3-fold, single dose, p \u3c 0.05; 1.5-fold, repeated dose, p \u3c 0.01). However, there were no significant differences in the insulin-to-glucagon ratio and no significant change in glucose levels in these healthy subjects during the study period. Importantly, GABA significantly decreased glycated albumin levels in the repeated dosing period. Subjects with repeated dosing showed an elevated incidence of minor adverse events in comparison to placebo or the single dosing period, most notably transient discomforts such as dizziness and sore throat. However, there were no serious adverse events observed throughout the study. Our data show that GABA is rapidly absorbed and tolerated in human beings; its endocrine effects, exemplified by increasing islet hormonal secretion, suggest potential therapeutic benefits for diabetes

On the Empirics of Institutions and Quality of Growth: Evidence for Developing Countries

We explore a newly available dataset on quality of growth to investigate the effect of institutions on growth quality in 93 developing countries for the period 1990 to 2011. Quality of institutions is measured in term of political risk. The empirical evidence is based on: (i) Ordinary Least Squares (OLS) and Two Stage Least Squares (2SLS) and (ii) cross-sectional and panel data structures. In order to avail room for more policy implications, the dataset is further disaggregated into income levels, namely: Lower middle income (LMIC), low income (LI) and upper middle income (UMIC). Three main findings are established. First, institutions are positively related to the quality of growth. Second, institutions have significantly contributed to growth quality in increasing order during the following time intervals: 2005-2011, 1995-1999 and 2000-2004. Third, the positive nexus between institutions and growth quality is fundamentally driven by LMIC. Policy implications are discussed

The Comparative Economics of Catch-Up in Output per worker, total factor productivity and technological gain in Sub-Saharan Africa

After investigating the effect of external financial flows on total factor productivity and technological gain, we use the beta catch-up and sigma convergence to compare dispersions in output per worker, total factor productivity and technological gain in Sub-Saharan Africa (SSA) for the years 1980-2010. The comparative evidence is articulated with income levels, years of schooling, and health factors. We find; first, a positive association between foreign direct investment, trade openness, foreign aid, remittances and total factor productivity. However, when foreign direct investment is interacted with schooling, it is direct effect becomes negative on total factor productivity. Second, beta catch-up is between19.22% and 19.70% per annum with corresponding time to full catch-up of 25.38 years and 26.01 years respectively. Third, we find sigma-convergence among low-income nations and upper-middle income nations separately, but not for the entire sample together. Fourth, schooling in SSA is not yet a significant source of technology, but it can make external financial inflows more effective. Policies to induce external financial flows are not enough for development if absorptive capacity is low. More policy implications are discussed