South Africa and the search of strategic effect in the Central African Republic

This article provides a critical assessment from a strategic perspective of the South African military involvement in the Central African Republic that culminated in the Battle of Bangui. The strategic assessment was aimed at an understanding of the South African armed forces and their government’s strategic approach and logic (i.e. strategic ways) through a consideration of, firstly, their strategic objectives and end states and, secondly, a critical reflection on the military means that were available and employed in the Central African Republic. The authors question the logic of South African political and military objectives through an emphasis on the absence of South African interests in the Central African Republic, the failure of the executive to inform parliament, the dubious and blurred intentions of the African National Congress government and the absence of a clear political–military nexus for the operation. The lack of sufficient military capabilities for the deployment was assessed through a consideration of overstretch, obsolescence, neglect and mismanagement of military resources. The article concludes that not only did the government set the military up for failure; it also succeeded in creating the perfect conditions for a strategic fiasco

Neurogenin3 restricts serotonergic neuron differentiation to the hindbrain

The development of the nervous system is critically dependent on the production of functionally diverse neuronal cell types at their correct locations. In the embryonic neural tube, dorsoventral signaling has emerged as a fundamental mechanism for generating neuronal diversity. In contrast, far less is known about how different neuronal cell types are organized along the rostrocaudal axis. In the developing mouse and chick neural tube, hindbrain serotonergic neurons and spinal glutamatergic V3 interneurons are produced from ventral p3 progenitors, which possess a common transcriptional identity but are confined to distinct anterior-posterior territories. In this study, we show that the expression of the transcription factor Neurogenin3 (Neurog3) in the spinal cord controls the correct specification of p3-derived neurons. Gain- and loss-of-function manipulations in the chick and mouse embryo show that Neurog3 switches ventral progenitors from a serotonergic to V3 differentiation program by repressing Ascl1 in spinal p3 progenitors through a mechanism dependent on Hes proteins. In this way, Neurog3 establishes the posterior boundary of the serotonergic system by actively suppressing serotonergic specification in the spinal cord. These results explain how equivalent p3 progenitors within the hindbrain and the spinal cord produce functionally distinct neuron cell types.Fil: Carcagno, Abel Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Di Bella, Daniela Jesica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Goulding, Martyn. Salk Institute for Biological Studies; Estados UnidosFil: Guillemot, Francois. MRC National Institute for Medical Research; Reino UnidoFil: Lanuza, Guillermo Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

THE MAKING OF STRATEGY; RULERS, STATES AND WAR

The Making of Modern Strategy in the product of a spectrum of contributors working on the concept of strategy and in particular the strategy formulation processes. These contributors include not only historians but also political scientists, some of whom focus on security and strategic studies. Thus editors and contributors represent a necessary balance, as the making of strategy requires insights and understanding of both fields. Throughout the book the writers focus upon the historical Selous Scouts and the Fireforce Commandos of the Rhodesian Light Infantry are all here. Viewers are treated to an expose of their training regimes, weaponry and bush tactics. A point of note here is what Lt Col Ron Reid-Daly refers to as "that baboon" in his book - Selous Scout; Top Secret War. Well that baboon, or another one surprisingly similar, is a star attraction in the Pamwe Chete portion of this video - I found it revolting but aspiring bush battlers would probably disagree!</p

Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART

We have found evidence for the presence of two distinct ancient stellar components (both geq 10 Gyr old) in the Sculptor dwarf spheroidal galaxy. We used the ESO Wide Field Imager (WFI) in conjunction with the VLT/FLAMES spectrograph to study the properties of the resolved stellar population of Sculptor out to and beyond the tidal radius. We find that two components are discernible in the spatial distribution of Horizontal Branch stars in our imaging, and in the [Fe/H] and v_hel distributions for our large sample of spectroscopic measurements. They can be generally described as a ``metal-poor'' component ([Fe/H] -1.7). The metal-poor stars are more spatially extended than the metal-rich stars, and they also appear to be kinematically distinct. These results provide an important insight into the formation processes of small systems in the early universe and the conditions found there. Even this simplest of galaxies appears to have had a surprisingly complex early evolution.Comment: accepted for publication in ApJL 12 pages, 4 figure

Linear response theory for magnetic Schroedinger operators in disordered media

We justify the linear response theory for an ergodic Schroedinger operator with magnetic field within the non-interacting particle approximation, and derive a Kubo formula for the electric conductivity tensor. To achieve that, we construct suitable normed spaces of measurable covariant operators where the Liouville equation can be solved uniquely. If the Fermi level falls into a region of localization, we recover the well-known Kubo-Streda formula for the quantum Hall conductivity at zero temperature.Comment: Latex, 68 pages, misprints corrected, formatting change

Very high-energy gamma-ray follow-up program using neutrino triggers from IceCube

We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e. g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015

A search for spectral hysteresis and energy-dependent time lags from x-ray and TeV gamma-ray observations of Mrk 421

Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three " target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e. g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at greater than or similar to 4 x 10(-4) Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies