54 research outputs found
The MAGIC Experiment and Its First Results
With its diameter of 17m, the MAGIC telescope is the largest Cherenkov
detector for gamma ray astrophysics. It is sensitive to photons above an energy
of 30 GeV. MAGIC started operations in October 2003 and is currently taking
data. This report summarizes its main characteristics, its rst results and its
potential for physics.Comment: 6 pages, 3 figures, to be published in the Proceedings of the 6th
International Symposium ''Frontiers of Fundamental and Computational
Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200
Evaluation of Microbiome-Host Relationships in the Zebrafish Gastrointestinal System Reveals Adaptive Immunity Is a Target of Bis(2-ethylhexyl) Phthalate (DEHP) Exposure
To improve physical characteristics of plastics such as flexibility and durability, producers enrich materials with phthalates such as di-2-(ethylhexyl) phthalate (DEHP). DEHP is a high production volume chemical associated with metabolic and immune disruption in animals and humans. To reveal mechanisms implicated in phthalate-related disruption in the gastrointestinal system, male and female zebrafish were fed DEHP (3 ppm) daily for two months. At the transcriptome level, DEHP significantly upregulated gene networks in the intestine associated with helper T cells' (Th1, Th2, and Th17) specific pathways. The activation of gene networks associated with adaptive immunity was linked to the suppression of networks for tight junction, gap junctional intercellular communication, and transmembrane transporters, all of which are precursors for impaired gut integrity and performance. On a class level, DEHP exposure increased Bacteroidia and Gammaproteobacteria and decreased Verrucomicrobiae in both the male and female gastrointestinal system. Further, in males there was a relative increase in Fusobacteriia and Betaproteobacteria and a relative decrease in Saccharibacteria. Predictive algorithms revealed that the functional shift in the microbiome community, and the metabolites they produce, act to modulate intestinal adaptive immunity. This finding suggests that the gut microbiota may contribute to the adverse effects of DEHP on the host by altering metabolites sensed by both intestinal and immune Th cells. Our results suggest that the microbiome-gut-immune axis can be modified by DEHP and emphasize the value of multiomics approaches to study microbiome-host interactions following chemical perturbations
MAGIC observations of very high energy gamma-rays from HESS J1813-178
Recently, the HESS collaboration has reported the detection of gamma-ray
emission above a few hundred GeV from eight new sources located close to the
Galactic Plane. The source HESS J1813-178 has sparked particular interest, as
subsequent radio observations imply an association with SNR G12.82-0.02.
Triggered by the detection in VHE gamma-rays, a positionally coincident source
has also been found in INTEGRAL and ASCA data. In this Letter we present MAGIC
observations of HESS J1813-178, resulting in the detection of a differential
gamma-ray flux consistent with a hard-slope power law, described as dN/(dA dt
dE) = (3.3+/-0.5)*10^{-12} (E/TeV)^{-2.1+/-0.2} cm^(-2)s^(-1)TeV^(-1). We
briefly discuss the observational technique used, the procedure implemented for
the data analysis, and put this detection in the perspective of multifrequency
observations.Comment: Accepted by ApJ Letter
Discovery of Very High Energy -Rays from Markarian~180 Triggered by an Optical Outburst
The high-frequency-peaked BL Lacertae object Markarian~180 (Mrk~180) was
observed to have an optical outburst in 2006 March, triggering a Target of
Opportunity observation with the MAGIC telescope. The source was observed for
12.4 hr and very high energy -ray emission was detected with a
significance of 5.5 . An integral flux above 200 GeV of
was measured, corresponding to
11% of the Crab Nebula flux. A rather soft spectrum with a photon index of
has been determined. No significant flux variation was found.Comment: Accepted by ApJ Letters, minor revision
Environmental Emission of Pharmaceuticals from Wastewater Treatment Plants in the USA
The residual drugs, drug bioconjugates, and their metabolites, mostly from human and veterinary usage, are routinely flushed down the drain, and enter wastewater treatment plants (WWTP). Increasing population, excessive use of allopathic medicine, continual introduction of novel drugs, and existing inefficient wastewater treatment processes result in the discharge of large volumes of pharmaceuticals and their metabolites from the WWTPs into the environment. The effluent from the WWTPs globally contaminate ~25% of rivers and the lakes. Pharmaceuticals in the environment, as contaminants of emerging concerns, behave as pseudo-persistent despite their relatively short environmental half-lives in the environment. Therefore, residual levels of pharmaceuticals in the environment not only pose a threat to the wildlife but also affect human health through contaminated food and drinking water. This chapter highlights WWTPs as point-sources of their environmental emissions and various effects on the aquatic and terrestrial ecosystem
Observation of Gamma Rays from the Galactic Center with the MAGIC Telescope
Recently, the Galactic Center has been reported to be a source of very high
energy (VHE) gamma-rays by the VERITAS, CANGAROO and HESS experiments. The
energy spectra as measured by these experiments show substantial differences.
In this Letter we present MAGIC observations of the Galactic Center, resulting
in the detection of a differential gamma-ray flux consistent with a steady,
hard-slope power law, described as dN/(dA dt dE) = (2.9+/-0.6)*10^{-12}
(E/TeV)^{-2.2+/-0.2} cm^{-2}s^{-1}TeV^{-1}. The gamma-ray source is centered at
(Ra, Dec)=(17h 45m 20s, -29deg 2'. This result confirms the previous
measurements by the HESS experiment and indicates a steady source of TeV
gamma-rays. We briefly describe the observational technique used, the procedure
implemented for the data analysis, and discuss the results in the perspective
of different models proposed for the acceleration of the VHE gamma-rays.Comment: ApJL submitte
Observation of VHE gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 using the MAGIC telecope
The MAGIC Cherenkov telescope has observed very high energy (VHE) gamma-ray
emission from the Active Galactic Nucleus 1ES1959+650 during six hours in
September and October 2004. The observations were carried out alternated with
the Crab Nebula, whose data were used as reference source for optimizing
gamma/hadron separation and for flux comparison. The data analysis shows VHE
gamma-ray emission of 1ES1959+650 with ~ 8 sigma significance, at a time of low
activity in both optical and X-ray wavelengths. An integral flux above ~ 180
GeV of about 20% of the Crab was obtained. The light curve, sampled over 7
days, shows no significant variations. The differential energy spectrum between
180 GeV and 2 TeV can be fitted with a power law of index -2.72 +/- 0.14. The
spectrum is consistent with the slightly steeper spectrum seen by HEGRA at
higher energies, also during periods of low X-ray activity.Comment: 16 pages, 6 figure
Variable Very High Energy Gamma-ray Emission from the Microquasar LS I +61 303
Microquasars are binary star systems with relativistic radio-emitting jets.
They are potential sources of cosmic rays and laboratories for elucidating the
physics of relativistic jets. Here we report the detection of variable
gamma-ray emission above 100 gigaelectron volts from the microquasar LS I +61
303. Six orbital cycles were recorded. Several detections occur at a similar
orbital phase, suggesting the emission is periodic. The strongest gamma-ray
emission is not observed when the two stars are closest to one another,
implying a strong orbital modulation of the emission or the absorption
processes.Comment: 11 pages with 4 figure
Variable Very High Energy Gamma-ray Emission from the Microquasar LS I +61 303
Microquasars are binary star systems with relativistic radio-emitting jets.
They are potential sources of cosmic rays and laboratories for elucidating the
physics of relativistic jets. Here we report the detection of variable
gamma-ray emission above 100 gigaelectron volts from the microquasar LS I +61
303. Six orbital cycles were recorded. Several detections occur at a similar
orbital phase, suggesting the emission is periodic. The strongest gamma-ray
emission is not observed when the two stars are closest to one another,
implying a strong orbital modulation of the emission or the absorption
processes.Comment: 11 pages with 4 figure
Observation of VHE Gamma Radiation from HESS J1834-087/W41 with the MAGIC Telescope
Recently, the HESS array has reported the detection of gamma-ray emission
above a few hundred GeV from eight new sources located close to the Galactic
Plane. The source HESS J1834-087 is spatially coincident with SNR G23.3-0.3
(W41). Here we present MAGIC observations of this source, resulting in the
detection of a differential gamma-ray flux consistent with a power law,
described as dN/(dA dt dE) = (3.7 +/- 0.6)*10^(-12) (E/TeV)^(-2.5 +/- 0.2) \
cm^(-2)s^(-1)TeV^(-1). We confirm the extended character of this flux. We
briefly discuss the observational technique used, the procedure implemented for
the data analysis, and put this detection in the perspective of the molecular
environment found in the region of W41. We present 13CO and 12CO emission maps
showing the existence of a massive molecular cloud in spatial superposition
with the MAGIC detection.Comment: Accepted by ApJ Letter
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