Pastures in Vanuatu

Livestock Production/Industries,

New evidence for a dramatic rise in atmosphere oxygen ca. 1,900 m.y. ago

Several lines of geologic evidence have pointed to a significant increase in P sub O2 about 2,000 m.y. ago, but the magnitude of P sub O2 before and after that time has been quite uncertain. The data that we have recently accumulated suggest that P sub O2 was approximately less than 2 x 10 (exp -3) atm more than 2,000 m.y. ago, and approximately greater than 0.03 atm more recently than ca. 1,900 m.y. ago. These estimates are based on the behavior of iron in Precambrian weathering horizons. More than ca. 2,000 m.y. ago, Fe(+2), released during the weathering of basalts was not oxidized to Fe(+3), and was removed in ground water from the upper layers of soil horizons. More recently than ca. 1,850 m.y. ago, Fe(+2) was oxidized to Fe(+3) and precipitated as iron oxides and hydroxides in such soil horizons and in the weathering products of a carbonate facies banded iron formation in Griqualand West, South Africa. The O2 content of the atmosphere must have increased dramatically about 1,900 m.y. ago to explain these observations. The reasons for the increase are still obscure, but are probably related to changes in the biologic productivity of the oceans. Eukaryotes appear to have developed shortly after the increase in P sub O2, perhaps in response to the subsequent increase in the supply of nitrate from the atmosphere to the oceans

Egypt at a Crossroads: an Analysis of Morsi\u27s Strategies of Military Control in the Post-Revolutionary State

Following Tunisia, Egypt was the second Arab nation to engage in the Arab Spring, as massive civil uprisings in protest of its former repressive dictator Hosni Mubarak succeeded in toppling his regime after thirty years of rule. After seventeen months of military rule in the period following Mubarak’s fall, Mohamed Morsi, a member of Egypt’s Muslim Brotherhood, was elected the fifth president of Egypt. Morsi is Egypt’s first civilian president. Ever since the Free Officers Revolution of 1952, Egypt has been ruled by a succession of military leaders, including Gamal Abdel Nasser, Anwar Sadat, and Hosni Mubarak. Consequently, political and economic authority has since rested in the hands of the military. The purpose of this paper is to evaluate the strategic approaches undertaken by Egypt’s former leaders in an overall attempt to provide a comprehensive answer to this central question: what are President Morsi’s strategies for controlling the military in post-revolutionary Egypt? I will argue that, while Morsi has demonstrated his desire to control the armed forces through various institutional changes, his efforts have fallen short of attacking the heart of the problem, which is the deeply-rooted militaristic culture that has come to be valued and accepted by Egyptian society throughout the course of the last sixty years

Numerical Modeling Of Hohlraum Radiation Conditions: Spatial And Spectral Variations Due To Sample Position, Beam Pointing, And Hohlraum Geometry

View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold Hohlraums and single-ended gold Hohlraums (\u27\u27 halfraums \u27\u27) used in inertial confinement fusion and high-energy density physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the Hohlraum \u27\u27 drive \u27\u27 can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature and especially the differences between what diagnostics looking in the LEH measure versus the radiation temperature on wall-mounted experimental packages are generally greater for double-ended Hohlraums than for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, sample position, and beam pointing) that can be adjusted in order to, for example, maximize the radiation flux onto a sample, or other package. In this vein, simulations of Hohlraums and halfraums with LEH shields are also presented. (c) 2005 American Institute of Physics

Direct measurement of penetration length in ultra-thin and/or mesoscopic superconducting structures

We describe a method for direct measurement of the magnetic penetration length in thin (10 - 100 nm) superconducting structures having overall dimensions in the range 1 to 100 micrometers. The method is applicable for broadband magnetic fields from dc to MHz frequencies.Comment: Accepted by Journal of Applied P:hysics (Jun 2006).5 pages, 5 figure

Quantum mechanics over a q-deformed (0+1)-dimensional superspace

We built up a explicit realization of (0+1)-dimensional q-deformed superspace coordinates as operators on standard superspace. A q-generalization of supersymmetric transformations is obtained, enabling us to introduce scalar superfields and a q-supersymmetric action. We consider a functional integral based on this action. Integration is implemented, at the level of the coordinates and at the level of the fields, as traces over the corresponding representation spaces. Evaluation of these traces lead us to standard functional integrals. The generation of a mass term for the fermion field leads, at this level, to an explicitely broken version of supersymmetric quantum mechanics.Comment: 11 pages, Late

Reduced hypothalamic-pituitary-adrenal axis activity in chronic multi-site musculoskeletal pain : partly masked by depressive and anxiety disorders

Peer reviewedPublisher PD

New Challenges For Wind Shock Models: The Chandra Spectrum Of The Hot Star Delta Orionis

The Chandra spectrum of delta Ori A shows emission lines from hydrogen- and helium-like states of Si, Mg, Ne, and O, along with N VII Lyalpha and lines from ions in the range Fe XVII-Fe XXI In contrast to the broad lines seen in zeta Pup and zeta Ori (850 +/- 40 and 1000 +/- 240 km s(-1) half-width at half-maximum [HWHM], respectively), these lines are broadened to only 430 +/- 60 km s(-1) HWHM. This is much lower than the measured wind terminal velocity of 2000 km s(-1). The forbidden, intercombination, and resonance (fir) lines from He-like ions indicate that the majority of the X-ray line emission does not originate at the base of the wind, in agreement with the standard wind shock models for these objects. However, in that model the X-ray emission is distributed throughout an expanding, X-ray-absorbing wind, and it is therefore surprising that the emission lines appear relatively narrow, unshifted, and symmetric. We compare the observed line profiles to recent detailed models for X-ray line pro le generation in hot stars, but none of them offers a fully satisfactory explanation for the observed line profiles