Concise Synthesis of the Antidepressive Drug Candidate GSK1360707 by a Highly Enantioselective Gold-Catalyzed Enyne Cycloisomerization Reaction

Out of depression: Indeed, no depressing results are obtained from a gold-catalyzed enyne cycloisomerization controlled by phosphoramidite ligands with TADDOL-related but acyclic backbones (see scheme; Cbz=benzyloxycarbonyl). The “triple-reuptake inhibitor” GSK1360707 was obtained in excellent yield and optical purity, therefore highlighting the relevance of asymmetric gold catalysis for practical applications

Spatial frequency tuned covariance channels for red–green and luminance-modulated gratings: psychophysical data from human adults

AbstractBoth chromatic and luminance-modulated stimuli are served by multiple spatial-frequency-tuned channels. This experiment investigated the independence versus interdependence of spatial frequency channels that serve the detection of red–green chromatic versus yellow–black luminance-modulated stimuli at low spatial frequencies. Contrast thresholds for both chromatic and luminance-modulated gratings were measured within 12 individual subjects using a repeated-measures design. Spatial frequencies ranged from 0.27 to 2.16 c/deg. A covariance structure analysis of individual differences was applied to the data. We computed statistical sources of individual variability, used them to define covariance channels, and determined the number and frequency tuning of these channels. For luminance-modulated gratings, two covariance channels were found, including one above and one below 1 c/deg [cf. Peterzell, & Teller (1996). Individual differences in contrast sensitivity functions: the coarsest spatial pattern analyzer. Vision Research, 36, 3077–3085]. For chromatic gratings, correlations between thresholds for most spatial frequencies were uniformly high, yielding a single covariance channel covering all but the highest spatial frequency tested. A combined analysis of both data sets recovered the same three covariance channels, and showed that detection thresholds for low-frequency red–green chromatic and luminance-modulated stimuli are served by separate, statistically independent processes

Space-based geoengineering: challenges and requirements

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures

Supply Chain Management and Hypercompetition

Firms nowadays face significant challenges in their operating environments, which have been characterised in two different ways. From a strategic management perspective these environments are in a state of hypercompetition while from a logistics or supply chain perspective these environments require market responsiveness predicated upon agile supply chains. However, firms must also rely on many interorganizational relationships to ensure efficient and effective movements within their supply chains. This paper discusses the relationships among these concepts and proposes a research framework combining aspects of the hypercompetition and responsiveness and agility viewpoints

The uniqueness of the Ethiopian demographic transition within sub-Saharan Africa: multiple responses to population pressure, and preconditions for rural fertility decline and capturing the demographic dividend

The findings of our new book on population and development in the second largest country, Ethiopia, are presented. We highlight its uniqueness in demographic transitions among countries in sub-Saharan African. Ethiopia has the largest rural-urban fertility gap (with below replacement fertility for Addis Ababa), the lowest maternal health service coverage by far, the highest percentage of illiterate mothers, the largest number of food insecure people, and 83% of the population concentrated mainly in densely populated rural areas. We present a new framework for the study of both poverty and development-driven causes and demographic responses to frequent hazards common in the fragile Horn of Africa. Multiple vulnerabilities and responses are rigorously documented, with migration and off-farm labor mobility, female education, delayed marriage, and lower family size norms predisposing a predicted acceleration of the rural fertility decline. We propose numerous policy and research implications to evaluate progress on what may now be reachable 2015 population policy targets in TFR and CPR, and to prepare for a potential demographic dividend

High yield fusion in a Staged Z-pinch

We simulate fusion in a Z-pinch; where the load is a xenon-plasma liner imploding onto a deuterium-tritium plasma target and the driver is a 2 MJ, 17 MA, 95 ns risetime pulser. The implosion system is modeled using the dynamic, 2-1/2 D, radiation-MHD code, MACH2. During implosion a shock forms in the Xe liner, transporting current and energy radially inward. After collision with the DT, a secondary shock forms pre-heating the DT to several hundred eV. Adiabatic compression leads subsequently to a fusion burn, as the target is surrounded by a flux-compressed, intense, azimuthal-magnetic field. The intense-magnetic field confines fusion $\alpha$-particles, providing an additional source of ion heating that leads to target ignition. The target remains stable up to the time of ignition. Predictions are for a neutron yield of $3.0\times 10^{19}$ and a thermonuclear energy of 84 MJ, that is, 42 times greater than the initial, capacitor-stored energy

Weyl’s gauge argument

The standard U(1) “gauge principle” or “gauge argument” produces an exact potential A=dλ and a vanishing field F=ddλ=0. Weyl has his own gauge argument, which is sketchy, archaic and hard to follow; but at least it produces an inexact potential A and a nonvanishing field F=dA≠0. I attempt a reconstruction