Very high energy gamma rays from the direction of Sagittarius A*.

We report the detection of a point-like source of very high energy (VHE) -rays coincident within 1' of Sgr A *, obtained with the HESS array of Cherenkov telescopes. The -rays exhibit a power-law energy spectrum with a spectral index of and a flux above the 165 GeV threshold of m -2 s -1. The measured flux and spectrum differ substantially from recent results reported in particular by the CANGAROO collaboration

Security, ethnicity, nationalism

In this article, I ask which aspects of ethnicity and nationalism that may be brought into sharper focus if we read these two phenomena with a view to how they have been shaped by security concerns. The first part of the article clears up some problems inherent in such exercises in diachronic concept analysis, and establishes the temporal area of validity for the analysis. The second part argues that the very emergence of the concept of ethnos (and its Roman translation, gens) was immersed in security thinking. It emerged as a way in which Greeks and Romans imposed order on what was outside that was not there before. Ethnic groups became ethnic by being interpellated by a stronger polity, and the process was driven first and foremost by security concerns. The third part illustrates this with a case study of the emergence of Slavic ethnicity. The fourth part of the article discusses how, with the advent of nationalism, there is an inversion. If ethnicity was imposed on subaltern groups, then European empires attempted to deny nationalism to such groups by insisting that they did not have the history to deserve it. Once again, security concerns played a key role, for as rightly seen by empires, nationhood could be an important anti-colonial resource. The paper ends by noting how nationalism invariably underlines the vitality of the Self, and juxtaposes it with the decrepitude of Others. With reference to present-day Russia, I note how the use of such organic metaphors in and of themselves securitize the relationship between nations, for the implication is that the old should disappear for the new to live, and that highlights security concerns on both sides of the relationship

Rapid Identification of Bio-Molecules Applied for Detection of Biosecurity Agents Using Rolling Circle Amplification

Detection and identification of pathogens in environmental samples for biosecurity applications are challenging due to the strict requirements on specificity, sensitivity and time. We have developed a concept for quick, specific and sensitive pathogen identification in environmental samples. Target identification is realized by padlock- and proximity probing, and reacted probes are amplified by RCA (rolling-circle amplification). The individual RCA products are labeled by fluorescence and enumerated by an instrument, developed for sensitive and rapid digital analysis. The concept is demonstrated by identification of simili biowarfare agents for bacteria (Escherichia coli and Pantoea agglomerans) and spores (Bacillus atrophaeus) released in field

The chemistry and biological activity of the Hyacinthaceae

Covering: 1914 to 2012The Hyacinthaceae (sensu APGII), with approximately 900 species in about 70 genera, can be divided into three main subfamilies, the Hyacinthoideae, the Urgineoideae and the Ornithogaloideae, with a small fourth subfamily the Oziroëoideae, restricted to South America. The plants included in this family have long been used in traditional medicine for a wide range of medicinal applications. This, together with some significant toxicity to livestock has led to the chemical composition of many of the species being investigated. The compounds found are, for the most part, subfamily-restricted, with homoisoflavanones and spirocyclic nortriterpenoids characterising the Hyacinthoideae, bufadienolides characterising the Urgineoideae, and cardenolides and steroidal glycosides characterising the Ornithogaloideae. The phytochemical profiles of 38 genera of the Hyacinthaceae will be discussed as well as any biological activity associated with both crude extracts and compounds isolated. The Hyacinthaceae of southern Africa were last reviewed in 2000 (T. S. Pohl, N. R. Crouch and D. A. Mulholland, Curr. Org. Chem., 2000, 4, 1287-1324; ); the current contribution considers the family at a global level

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments

H.E.S.S. observations of PKS 2155-304

The high-frequency peaked BL Lac PKS 2155-304 at redshift z = 0.117 has been detected with high significance (∼45σ) at energies greater than 160 GeV, using the H.E.S.S. stereoscopic array of imaging air-Cherenkov telescopes in Namibia. A strong signal is found in each of the data sets corresponding to the dark periods of July and October, 2002, and June-September, 2003. The observed flux of VHE gamma rays shows variability on time scales of months, days, and hours. The monthly-averaged integral flux above 300 GeV varies between 10% and 60% of the flux observed from the Crab Nebula. Energy spectra are measured for these individual periods of data taking and are characterized by a steep power law with a time-averaged photon index of Γ = 3.32 ± 0.06. An improved x2 per degree of freedom is found when either a power law with an exponential cutoff energy or a broken power law are fit to the time-averaged energy spectrum. However, the significance of the improvement is marginal (∼2σ). The suggested presence of features in the energy spectrum may be intrinsic to the emission from the blazar, or an indication of absorption of TeV gamma rays by the extragalactic infrared background light.F. Aharonian, A. G. Akhperjanian, K.-M. Aye, A. R. Bazer-Bachi, M. Beilicke, W. Benbow, D. Berge, P. Berghaus, K. Bernlöhr, O. Bolz, C. Boisson, C. Borgmeier, F. Breitling, A. M. Brown, J. Bussons Gordo, P. M. Chadwick, V. R. Chitnis, L.-M. Chounet, R. Cornils, L. Costamante, B. Degrange, A. Djannati-Ataï, L.O'C. Drury, T. Ergin, P. Espigat, F. Feinstein, P. Fleury, G. Fontaine, S. Funk, Y. A. Gallant, B. Giebels, S. Gillessen, P. Goret, J. Guy, C. Hadjichristidis, M. Hauser, G. Heinzelmann, G. Henri, G. Hermann, J. A. Hinton, W. Hofmann, M. Holleran, D. Horns, O. C. de Jager, I. Jung, B. Khélifi, Nu. Komin, A. Konopelko, I. J. Latham, R. Le Gallou, M. Lemoine, A. Lemière, N. Leroy, T. Lohse, A. Marcowith, C. Masterson, T. J. L. McComb, M. de Naurois, S. J. Nolan, A. Noutsos, K. J. Orford, J. L. Osborne, M. Ouchrif, M. Panter, G. Pelletier, S. Pita, M. Pohl, G. Pühlhofer, M. Punch, B. C. Raubenheimer, M. Raue, J. Raux, S. M. Rayner, I. Redondo, A. Reimer, O. Reimer, J. Ripken, M. Rivoal, L. Rob, L. Rolland, G. Rowell, V. Sahakian, L. Saugé, S. Schlenker, R. Schlickeiser, C. Schuster, U. Schwanke, M. Siewert, H. Sol, R. Steenkamp, C. Stegmann, J.-P. Tavernet, C. G. Théoret, M. Tluczykont, D. J. van der Walt, G. Vasileiadis, P. Vincent, B. Visser, H. J. Völk and S. J. Wagne

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

External habit: Anything goes

This paper explores the expressive ability of the external habit mechanism. I show that whenever the stochastic discount factor (SDF) is a function of aggregate consumption, there exists a representative agent external habit model that replicates that SDF. I also show that within this framework the other utility function parameters become indeterminate, in that a different choice of power utility can lead to the exact same SDF. The indeterminacy arises from an ambiguity in the SDF between the externality and individual consumption