Evidence for X-ray synchrotron emission from simultaneous mid-IR to X-ray observations of a strong Sgr A* flare

This paper reports measurements of Sgr A* made with NACO in L' -band (3.80 um), Ks-band (2.12 um) and H-band (1.66 um) and with VISIR in N-band (11.88 um) at the ESO VLT, as well as with XMM-Newton at X-ray (2-10 keV) wavelengths. On 4 April, 2007, a very bright flare was observed from Sgr A* simultaneously at L'-band and X-ray wavelengths. No emission was detected using VISIR. The resulting SED has a blue slope (beta > 0 for nuL_nu ~ nu^beta, consistent with nuL_nu ~ nu^0.4) between 12 micron and 3.8 micron. For the first time our high quality data allow a detailed comparison of infrared and X-ray light curves with a resolution of a few minutes. The IR and X-ray flares are simultaneous to within 3 minutes. However the IR flare lasts significantly longer than the X-ray flare (both before and after the X-ray peak) and prominent substructures in the 3.8 micron light curve are clearly not seen in the X-ray data. From the shortest timescale variations in the L'-band lightcurve we find that the flaring region must be no more than 1.2 R_S in size. The high X-ray to infrared flux ratio, blue nuL_nu slope MIR to L' -band, and the soft nuL_nu spectral index of the X-ray flare together place strong constraints on possible flare emission mechanisms. We find that it is quantitatively difficult to explain this bright X-ray flare with inverse Compton processes. A synchrotron emission scenario from an electron distribution with a cooling break is a more viable scenario.Comment: ApJ, 49 pages, 9 figure

An extremely top-heavy initial mass function in the galactic center stellar disks

Composite armors, having two or more different materials, contain a ceramic layer in the front face and a metallic or polymer matrix composite as support on the back side backing. The function of the ceramic layer is to erode and break up the projectile and to increase the contact surface of the metallic plate by forming a hard cone. The role of the metallic backing layer is to absorb the kinetic energy of the projectile and support the fragmented ceramic. The most impportant advantage of these materials over monolithic metallic armors is to reduce the thickness by using the ceramic layer in front of the metallic layer. This provides reducing the weight of armor. In this study, experiments have been conducted to describe ballistic performance of polymer matrix composites having different geometrical shapes. To do these experiments, aramid and polyethilen composite specimens were first fabricated as laminates in different geometrical shapes. Then, these composite plates at charpy harms were investigeted in varios speed bullet to cover the impact damageKompozit zırhlar iki veya daha fazla farklı malzemeden oluşan, yüzeyde seramik katman ile arkada metal veya polimer matrisli kompozit destek içeren malzemelerdir. Seramik katmanın işlevi mermiyi aşındırma ve parçalamanın yanısıra sert koni oluşturarak metal katmanın temas yüzeyini artırmaktır. Metal destek katmanının görevi ise merminin kinetik enerjisini emmek ve darbe sonrası oluşacak seramik parçaları tutmaktır. Bu malzemelerin, tamamen metalik olan zırhlara göre en önemli avantajı, metalik katmandan önce seramik katmanın kullanılması yoluyla zırh kalınlığının, dolayısı ile zırhın ağırlığının azalmasını sağlamaktadır. Bu çalışmada değişik geometriye sahip, polimer matrisli kompozitlerin, balistik performansını ölçmek için deneyler yapılmıştır. Bunun için önce Aramid ve polietilen numuneler düz, iki değişik çapta silindirik ve küre plakalar halinde üretilmiştir. Bu kompozit plakalara atış poligonunda atışlar yapılmış ve oluşan darbe hasarları incelenmiştir

Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair

Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base

Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of e290 tera-electron volts. Its arrival direction was consistent with the location of a known g-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to g-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy g-rays. This observation of a neutrino in spatial coincidence with a g-ray-emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

In Vitro Evaluation of 231Bi-Rituximab versus External Gamma Irradiation for the Treatment of B-CLL Patients: Relative Biological Efficacy with Respect to Apoptosis Induction and Chromosomal Damage.

Abstract not availableJRC.E-Institute for Transuranium Elements (Karlsruhe

The Hubble Space Telescope Survey of M31 Satellite Galaxies. II. The Star Formation Histories of Ultrafaint Dwarf Galaxies

We present the lifetime star formation histories (SFHs) for six ultrafaint dwarf (UFD; M V > − 7.0, 4.9 < log 10 ( M * ( z = 0 ) / M ⊙ ) < 5.5 ) satellite galaxies of M31 based on deep color-magnitude diagrams constructed from Hubble Space Telescope imaging. These are the first SFHs obtained from the oldest main-sequence turnoff of UFDs outside the halo of the Milky Way (MW). We find that five UFDs formed at least 50% of their stellar mass by z = 5 (12.6 Gyr ago), similar to known UFDs around the MW, but that 10%-40% of their stellar mass formed at later times. We uncover one remarkable UFD, And xiii, which formed only 10% of its stellar mass by z = 5, and 75% in a rapid burst at z ∼ 2-3, a result that is robust to choices of underlying stellar model and is consistent with its predominantly red horizontal branch. This “young” UFD is the first of its kind and indicates that not all UFDs are necessarily quenched by reionization, which is consistent with predictions from several cosmological simulations of faint dwarf galaxies. SFHs of the combined MW and M31 samples suggest reionization did not homogeneously quench UFDs. We find that the least-massive MW UFDs (M *(z = 5) ≲ 5 × 104 M ⊙) are likely quenched by reionization, whereas more-massive M31 UFDs (M *(z = 5) ≳ 105 M ⊙) may only have their star formation suppressed by reionization and quench at a later time. We discuss these findings in the context of the evolution and quenching of UFDs. © 2023. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]