2,603 research outputs found

    Pioneer Anomaly: Evaluating Newly Recovered Data

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    The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data received from the distances between 20--70 astronomical units from the Sun consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue frequency shift that can be interpreted as a sunward acceleration of a_P = (8.74 +/- 1.33) x 10^(-10) m/s^2 for each particular spacecraft. This signal has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. New Pioneer 10 and 11 radio-metric Doppler data recently became available. The much extended set of Pioneer Doppler data is the primary source for new upcoming investigation of the anomaly. We also have almost entire records of flight telemetry files received from the the Pioneers. Together with original project documentation and newly developed software tools, this additional information is now used to reconstruct the engineering history of both spacecraft. To that extent, a thermal model of the Pioneer vehicles is being developed to study possible contribution of thermal recoil force acting on the two spacecraft. In addition, to improve the accuracy of orbital reconstruction, we developed a new approach that uses actual flight telemetry data during trajectory analysis of radio-metric Doppler files. The ultimate goal of these efforts is to investigate possible contributions of the thermal recoil force to the detected anomalous acceleration.Comment: 12 pages, 15 figures, invited talk at the "III Mexican Meeting on Mathematical and Experimental Physics," Mexico City, Mexico, 10-14 September 200

    A Novel Use of Light Guides and Wavelength Shifting Plates for the Detection of Scintillation Photons in Large Liquid Argon Detectors

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    Scintillation light generated as charged particles traverse large liquid argon detectors adds valuable information to studies of weakly-interacting particles. This paper uses both laboratory measurements and cosmic ray data from the Blanche dewar facility at Fermilab to characterize the efficiency of the photon detector technology developed at Indiana University for the single phase far detector of DUNE. The efficiency of this technology was found to be 0.48% at the readout end when the detector components were characterized with laboratory measurements. A second determination of the efficiency using cosmic ray tracks is in reasonable agreement with the laboratory determination. The agreement of these two efficiency determinations supports the result that minimum ionizing muons generate Nphot=40,000{\mathcal N}_{phot} = 40,000 photons/MeV as they cross the LAr volume.Comment: Accepted version (without final editorial corrections

    Image Management in a Touristic Destination: A Qualitative Approach Analysis of the Border City of Ciudad Juarez, Mexico

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    This paper summarizes an academic experience. It has been made by the contributions of a group of experts from a Mexican university participating in a discussion panel called "Image of a Touristic Destination". This was done within the framework of the activities carried out during the 8va. Catedra Patrimonial "Sergio Molina" on October 19-21, 2016. The purpose of this paper is to analyze the process of image management of a border touristic destination through the experience of Ciudad Juárez, in order to obtain an improvement in it. The concept of image is analyzed from its components of responsibility and participation in management between Government (message), Society (context), and Universities (management). The methodological approach selected was exploratory. The grounded theory method was selected and thematic analysis with the support of the Atlas-ti software was made. Suggestions are offered for actions which seek to highlight the positive aspects of the city as a touristic destination. The importance of generating responsibility and participation within a social network was highlighted. It was recommended to take advantage of the economic and intellectual resources in education of the Juarez society so that they can know their culture and history

    Occurrence of bovine hydatidosis and evaluation of its risk to humans in traditional communities of Southern Region of Ethiopia

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    Background: Cystic Echinococcosis/ Hydatid Disease, is an infection caused by the larval stage of the tapeworm Echinococcus granulosus, one of the most widespread parasitic zoonoses.Objective: To determine the occurrence, localization and fertility/sterility rates of hydatid cyst in cattle, to determine the prevalence of adult E. granulosus in dogs and asses the risk for human infection in traditional communities.Methods: Postmortem examination, hydatid cyst characterization,  questionnaire survey and dog stool sample examination were carried out.Results: Of the total 320 ruminants examined at backyard slaughtering, 151 (47.2%) were found harboring hydatid cysts. The liver and lungs were the two main infected organs, 34.4% and 52.3%, respectively. The majority of the cysts found were small, 54.3%, and medium, 37.7%. From the total number of cysts found, 70.2% were sterile, while 29.8% were fertile. A questionnaire survey revealed that local people were unaware of the life cycle of E. granulosus and the perpetuation of its life cycle by their cultural and traditional practices. Dogs have intimate contact with humansand other domestic animals, share the same house and also dogs do not have access for veterinary care. Stool samples of 62 dogs were collected and analyzed with a 30% prevalence of taenia infection confirmed to be E. granulosus.Conclusion: Because of the high prevalence of E. granulosus infection in dogs and hydatidosis in cattle as well as common practice of backyard slaughtering, the risk of human infection in traditional communities is suspected to be high and requires immediate attention to study the status of cystic ehinococcosis in the human population of the study area.[Ethiop. J. Health Dev. 2012;26(1):43-48

    Isomorphism between Non-Riemannian gravity and Einstein-Proca-Weyl theories extended to a class of Scalar gravity theories

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    We extend the recently proved relation between certain models of Non-Riemannian gravitation and Einstein- Proca-Weyl theories to a class of Scalar gravity theories. This is used to present a Black-Hole Dilaton solution with non-Riemannian connection.Comment: 13 pages, tex file, accepted in Class. Quant. Gra

    Prospective dark matter annihilation signals from the Sagittarius Dwarf Spheroidal

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    The Sagittarius Dwarf Spheroidal galaxy (Sgr) is investigated as a target for dark matter (DM) annihilation searches utilizing J-factor distributions calculated directly from a high-resolution hydrodynamic simulation of the infall and tidal disruption of Sgr around the Milky Way. In contrast to past studies, the simulation incorporates DM, stellar and gaseous components for both the Milky Way and the Sgr progenitor galaxy. The simulated distributions account for significant tidal disruption affecting the DM density profile. Our estimate of the J-factor value for Sgr, JSgr = 1.48 × 1010 M2☉ kpc−5 (6.46 × 1016 GeV cm−5), is significantly lower than found in prior studies. This value, while formally a lower limit, is likely close to the true J-factor value for Sgr. It implies a DM cross-section incompatibly large in comparison with existing constraints would be required to attribute recently observed gamma-ray emission from Sgr to DM annihilation. We also calculate a J-factor value using a NFW profile fitted to the simulated DM density distribution to facilitate comparison with past studies. This NFW J-factor value supports the conclusion that most past studies have overestimated the dark matter density of Sgr on small scales. This, together with the fact that the Sgr has recently been shown to emit gamma-rays of astrophysical origin, complicate the use of Sgr in indirect DM detection searches

    A high-resolution hydrodynamic-biogeochemical coupled model of the Gulf of Cadiz – Alboran Sea region.

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    The southern Iberia regional seas comprise the Gulf of Cadiz and the Alboran Sea sub-basins connected by the narrow Strait of Gibraltar. Both basins are very different in their hydrological and biological characteristics but are, also, tightly connected to each other. Integrative studies of the whole regional oceanic system are scarce and difficult to perform due to the relative large area to cover and the different relevant time-scales of the main forcings in each sub-basin. Here we propose, for the first time, a fully coupled, 3D, hydrodynamic-biogeochemical model that covers, in a single domain (~2km resolution) both marine basins for a 20 years simulation (1989-2008). Model performance is assessed against available data in terms of spatial and temporal distributions of biological variables. In general, the proposed model is able to represent the climatological distributions of primary and secondary producers and also the main seasonality of primary production in the different sub-regions of the analyzed basins. Potential causes of the observed mismatches between model and data are identified and some solutions are proposed for future model development. We conclude that most of these mismatches could be attributed to the missing tidal forcing in the actual model configuration. This model is a first step to obtain a meaningful tool to study past and future oceanographic conditions in this important marine region constituting the unique connection of the Mediterranean Sea with the open world’s ocean
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