888 research outputs found
A Pointing Solution for the Medium Size Telescopes for the Cherenkov Telescope Array
An important aspect of the calibration of the Cherenkov Telescope Array is
the pointing, which enables an exact alignment of each telescope and therefore
allows to transform a position in the sky to a point in the plane of the
Cherenkov camera and vice versa. The favoured approach for the pointing
calibration of the medium size telescopes (MST) is the installation of an
optical CCD-camera in the dish of the telescope that captures the position of
the Cherenkov camera and of the stars in the night sky simultaneously during
data taking. The adaption of this approach is presented in this proceeding.Comment: 6 pages, 9 figures, Proceedings of the 6th International Symposium on
High-Energy Gamma-Ray Astronomy (Gamma2016
Series and power series on universally complete complex vector lattices
In this paper we prove an nth root test for series as well as a Cauchy–Hadamard type formula and Abel's' theorem for power series on universally complete Archimedean complex vector lattices. These results are aimed at developing an alternative approach to the classical theory of complex series and power series using the notion of order convergence
The H.E.S.S. central data acquisition system
The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging
Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in
Namibia. It measures cosmic gamma rays of very high energies (VHE; >100 GeV)
using the Earth's atmosphere as a calorimeter. The H.E.S.S. Array entered Phase
II in September 2012 with the inauguration of a fifth telescope that is larger
and more complex than the other four. This paper will give an overview of the
current H.E.S.S. central data acquisition (DAQ) system with particular emphasis
on the upgrades made to integrate the fifth telescope into the array. At first,
the various requirements for the central DAQ are discussed then the general
design principles employed to fulfil these requirements are described. Finally,
the performance, stability and reliability of the H.E.S.S. central DAQ are
presented. One of the major accomplishments is that less than 0.8% of
observation time has been lost due to central DAQ problems since 2009.Comment: 17 pages, 8 figures, published in Astroparticle Physic
H.E.S.S. observations of PSR B1259-63 during its 2014 periastron passage
An extended observation campaign of the gamma-ray binary system PSR
B125963 has been conducted with the H.E.S.S. (High Energy Stereoscopic
System) II 5-telescope array during the system's periastron passage in 2014. We
report on the outcome of this campaign, which consists of more than 85 h of
data covering both pre- and post-periastron orbital phases. The lower energy
threshold of the H.E.S.S. II array allows very-high-energy (VHE; GeV) gamma-ray emission from PSR B125963 to be studied for the first
time down to 200 GeV. The new dataset partly overlaps with and extends in phase
previous H.E.S.S. campaigns on this source in 2004, 2007 and 2011, allowing for
a detailed long-term characterisation of the flux level at VHEs. In addition,
the 2014 campaign reported here includes VHE observations during the exact
periastron time, , as well as data taken simultaneously to the
gamma-ray flare detected with the Fermi-LAT. Our results will be discussed in a
multiwavelength context, thanks to the dense broad-band monitoring campaign
conducted on the system during this last periastron passage.Comment: 8 pages, 5 figures. In Proceedings of the 34th International Cosmic
Ray Conference (ICRC2015), The Hague, The Netherland
Interrelationships of plant population, soil moisture and soil fertility in determining corn yields on Colo clay loam at Ames, Iowa
This investigation included a 6-year study of the effects of irrigation, stand and fertility treatments on com yields on a clay loam soil near Ames, Iowa. The data obtained from 1956 to 1961 indicated that variations in yields were caused by all three variables. Significant yield differences caused by irrigation treatments were greatest in 1956, 1959 and 1960. The highest mean irrigated yields averaged over stand and fertility treatments usually correlated best with the irrigation treatment where the soil moisture was maintained at or above 60 percent of the available moisture content (AMC). The greatest yield response to irrigation occurred in 1956, primarily because of the very dry conditions throughout the entire growing season. In 1956, each inch of water increased yield by 2.7 bushels per acre up to the 60-percent AMC level. Beyond this point, maintaining soil moisture at 90 percent or greater of field capacity reduced yield per increment of added water.
There was not a significant response to irrigation in 1957, 1958 and 1961, primarily because of ample soil moisture storage and good rainfall distribution at critical periods during the growing season
In Situ Structural Study of MnPi Modified BiVO4 Photoanodes by Soft X ray Absorption Spectroscopy
Ethnoveterinary knowledge of the inhabitants of Marajó Island, Eastern Amazonia, Brazil.
Em várias partes do mundo existem relatos etnoveterinários sobre a utilização de plantas em protocolos terapêuticos, entretanto não existem informações disponíveis sobre a etnoveterinária praticada na Amazônia brasileira. Desta forma, objetivou-se documentar o conhecimento etnoveterinário de habitantes da Ilha do Marajó, Amazônia Oriental. Foram realizadas 50 entrevistas individuais com aplicação de questionários semi-estruturados que foram analisados quantitativamente através de estatística descritiva utilizando freqüência de distribuição. O valor de uso foi calculado para determinar as espécies mais importantes. Amostras de plantas com relatos de uso medicinal foram coletadas e identificadas botanicamente. Cinqüenta plantas, distribuídas em 48 gêneros e 34 famílias, foram indicadas para 21 diferentes usos medicinais. A família Asteraceae foi a que teve maior número de espécies citadas e Carapa guianensis Aubl, Crescentia cujete L., Copaifera martii Hayne, Caesalpinia ferrea Mart., Chenopodium ambrosioides L., Jatropha curcas L. e Momordica charantia L. foram as espécies com maiores valor de uso. As partes das plantas mais utilizadas para preparo dos medicamentos etnoveterinários foram folhas (56%), cascas (18%), raizes (14%), sementes (14%) e frutos (8%). Quanto à forma de uso o chá foi citado por 56% dos entrevistados e a maioria das preparações (90,9%) utiliza uma só planta. Além das plantas medicinais, os entrevistados relataram o uso de produtos de origem animal e mineral. Esse trabalho contribui para realização de um inventário das plantas utilizadas na etnoveterinária marajoara que pode servir de base de dados para futuros estudos de validação científica
Status and Plans for the Array Control and Data Acquisition System of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next-generation atmospheric
Cherenkov gamma-ray observatory. CTA will consist of two installations, one in
the northern, and the other in the southern hemisphere, containing tens of
telescopes of different sizes. The CTA performance requirements and the
inherent complexity associated with the operation, control and monitoring of
such a large distributed multi-telescope array leads to new challenges in the
field of the gamma-ray astronomy. The ACTL (array control and data acquisition)
system will consist of the hardware and software that is necessary to control
and monitor the CTA arrays, as well as to time-stamp, read-out, filter and
store -at aggregated rates of few GB/s- the scientific data. The ACTL system
must be flexible enough to permit the simultaneous automatic operation of
multiple sub-arrays of telescopes with a minimum personnel effort on site. One
of the challenges of the system is to provide a reliable integration of the
control of a large and heterogeneous set of devices. Moreover, the system is
required to be ready to adapt the observation schedule, on timescales of a few
tens of seconds, to account for changing environmental conditions or to
prioritize incoming scientific alerts from time-critical transient phenomena
such as gamma ray bursts. This contribution provides a summary of the main
design choices and plans for building the ACTL system.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Modelling adapted to manufacturing aspects of holographic grating structures
The diffraction efficiencies of modified sinusoidal and blazed gratings are investigated in the high spatial frequency regime by rigorous numerical methods and are compared to experimentally manufactured gratings. The introduced modifications take actual technological induced variations of the profile geometries, such as specific corner rounding, into account. The high spatial frequency regime (resonance regime) is characterized by a local grating period, g, to wavelength, λ, ratio of 0.7 ≤ g/λ ≤ 4 and shows an important relevance for applications in spectroscopy and diffractive imaging. The investigations are carried out for both reflection on metallic surfaces and transmission of dielectric structures over a broad range of grating periods and incidence angles. It was found that near the grating resonance, the more simply producible sine gratings can compete in diffraction efficiency with sawtooth structures. Additionally, for certain application conditions, holographically modified sine structures achieve higher efficiencies than the ideal sine profile. It is also shown that holographical sinusoidal-like profiles measured by AFM can be fitted to a super-Gaussian shape, which is then used to inversely reconstruct the structure profiles from efficiency data
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