Wireless wake-up sensor network for structural health monitoring of large-scale highway bridges

To realize in-situ structural health monitoring of critical infrastructure such as bridges, we present a powerful, but also low power and flexible, wireless sensor node utilizing a wake-up transceiver. The sensor node is equipped with several kinds of sensors, such as temperature, pressure and acceleration for in-situ monitoring of critical infrastructure. In addition to these commonly used sensors in wireless sensor networks, some nodes are equipped with global navigation satellite system receivers (GNSS) and others with tilt and acceleration sensors of very high accuracy that were developed by Nothrop Grumman LITEF GmbH. We present a low power wakeup multi-hop routing protocol that is able to transmit data with little overhead by supporting the use of wake-up receivers in combination with long-range communication radios. The wireless sensor nodes and the routing protocol are tested at a large-scale highway bridge in south-west Germany, where a prototype network was installed in June 2015 following a first test installation earlier in June at the same bridge. A gateway node equipped with a Global System for Mobile Communications (GSM) modem transfers the network data to a remote server located at the University of Freiburg

Economia da produção de pimenta vermelha no município de Turuçu-RS.

bitstream/item/30264/1/boletim-19.pd

Pair Production Absorption Troughs in Gamma-Ray Burst Spectra: A Potential Distance Discriminator

Relativistic bulk motion with large Lorentz factors has recently been inferred for gamma-ray bursts regardless of whether they are of galactic or cosmological origin. This conclusion results from calculations of internal pair production transparency in bursts that usually assume an infinite power-law source spectrum for simplicity, an approximation that is quite adequate for some bursts detected by EGRET. However, for a given bulk Lorentz factor \teq{\Gamma}, photons above the EGRET range can potentially interact with sub-MeV photons in such calculations. Hence it is essential to accurately address the spectral curvature in bursts seen by BATSE. In this paper we present the major properties induced in photon-photon opacity considerations by such spectral curvature. The observed spectral breaks around 1 MeV turn out to be irrelevant to opacity in cosmological bursts, but are crucial to estimates of source transparency in the 1 GeV -- 1 TeV range for sources located in the galactic halo. We find that broad absorption troughs can arise at these energies for suitable bulk motion parameters \teq{\Gamma}. Such troughs are probably an unambiguous signature of a galactic halo population, and if observed by experiments such as Whipple, MILAGRO and GLAST, would provide powerful evidence that such bursts are not at cosmological distances.Comment: 10 pages, AASTeX format, including 2 eps figures, ApJLett in pres

EGRET Spectral Index and the Low-Energy Peak Position in the Spectral Energy Distribution of EGRET-Detected Blazars

In current theoretical models of the blazar subclass of active galaxies, the broadband emission consists of two components: a low-frequency synchrotron component with a peak in the IR to X-ray band, and a high-frequency inverse Compton component with a peak in the gamma-ray band. In such models, the gamma-ray spectral index should be correlated with the location of the low-energy peak, with flatter gamma-ray spectra expected for blazars with synchrotron peaks at higher photon energies and vice versa. Using the EGRET-detected blazars as a sample, we examine this correlation and possible uncertainties in its construction.Comment: 17 pages including 1 figure, accepted for publication in The Astrophysical Journa

The high-energy gamma-ray fluence and energy spectrum of GRB 970417a from observations with Milagrito

Evidence of TeV emission from GRB970417a has been previously reported using data from the Milagrito detector. Constraints on the TeV fluence and the energy spectrum are now derived using additional data from a scaler system that recorded the rate of signals from the Milagrito photomultipliers. This analysis shows that if emission from GRB970417a has been observed, it must contain photons with energies above 650 GeV. Some consequences of this observation are discussed.Comment: Submitted to the Astrophysical Journa

Search for Sub-TeV Gamma Rays Coincident with BATSE Gamma Ray Bursts

Project GRAND is a 100m x 100m air shower array of proportional wire chambers (PWCs). There are 64 stations each with eight 1.29 m^2 PWC planes arranged in four orthogonal pairs placed vertically above one another to geometrically measure the angles of charged secondaries. A steel plate above the bottom pair of PWCs differentiates muons (which pass undeflected through the steel) from non-penetrating particles. FLUKA Monte Carlo studies show that a TeV gamma ray striking the atmosphere at normal incidence produces 0.23 muons which reach ground level where their angles and identities are measured. Thus, paradoxically, secondary muons are used as a signature for gamma ray primaries. The data are examined for possible angular and time coincidences with eight gamma ray bursts (GRBs) detected by BATSE. Seven of the GRBs were selected because of their good acceptance by GRAND and high BATSE Fluence. The eighth GRB was added due to its possible coincident detection by Milagrito. For each of the eight candidate GRBs, the number of excess counts during the BATSE T90 time interval and within plus or minus five degrees of BATSE's direction was obtained. The highest statistical significance reported in this paper (2.7 sigma) is for the event that was predicted to be the most likely to be observed (GRB 971110).Comment: To be presented at the XXVIII International Cosmic Ray Conference, Tsukuba, Japa

United classification of cosmic gamma-ray bursts and their counterparts

United classification of gamma-ray bursts and their counterparts is established on the basis of measured characteristics: photon energy E and emission duration T. The founded interrelation between the mentioned characteristics of events consists in that, as the energy increases, the duration decreases (and vice versa). The given interrelation reflects the nature of the phenomenon and forms the E-T diagram, which represents a natural classification of all observed events in the energy range from 10E9 to 10E-6 eV and in the corresponding interval of durations from about 10E-2 up to 10E8 s. The proposed classification results in the consequences, which are principal for the theory and practical study of the phenomenon.Comment: Keywords Gamma rays: burst

Quality of Pharmaceutical Industry Press Releases Based on Original Research

Background: Press releases are a popular vehicle to disseminate health information to the lay media. While the quality of press releases issued by scientific conferences and medical journals has been questioned, no efforts to assess pharmaceutical industry press releases have been made. Therefore, we sought to systematically examine pharmaceutical company press releases about original research for measures of quality. Methodolgy/Principal Findings: Press releases issued by the ten top selling, international pharmaceutical companies in the year 2005 were selected for evaluation. A total of 1028 electronic press releases were issued and 235 were based on original research. More than half (59%) reported results presented at a scientific meeting. Twenty-one percent of releases were not explicit about the source of original data. While harms or adverse events were commonly cited (76%), study limitations were rarely noted (6%). Almost one-third (29%) of releases did not quantify study results. Studies presented in abstract form were subsequently published within at least 20 months in 53 % of cases. Conclusions: Pharmaceutical company press releases frequently report basic study details. However, readers should be cautioned by the preliminary nature of the data and lack of identified limitations. Methods to improve the reporting and interpretation of drug company press releases are desirable to prevent misleading media coverage

The Escape of High-Energy Photons from Gamma-Ray Bursts

Eleven bright gamma-ray bursts (GRBs) detected by BATSE have also been seen at much higher energies by EGRET, six at energies above 10 MeV. Such observations imply that these bursts are optically thin to photon-photon pair production at all observed energies. For bursts more than about 30pc away, internal transparency can be achieved only if the source is moving with a relativistic bulk Lorentz factor $\Gamma\gg 1$, or if the radiation is highly beamed. Early calculations of $\gamma\gamma\to e^+e^-$ considerations for GRBs were limited to cases of a beam with opening half-angle \Thetab\sim 1/\Gamma, or expansions of infinitely thin spherical shells. This paper presents our extension of pair production optical depth calculations in relativistically expanding sources to more general geometries, including shells of finite thickness and arbitrary opening angle. The problem is reduced analytically to a single integral in the broadly applicable case of observing photons along the axis of the expansion. We find that the minimum bulk Lorentz factor for the EGRET sources to be optically thin is only moderately dependent on the shell thickness and virtually independent of its opening solid angle if \Thetab\gtrsim 1/\Gamma. This insensitivity to \Thetab relieves the commonly-perceived number problem for non-repeating sources at cosmological distances, i.e. it is not necessary to invoke small \Thetab to effect photon escape.Comment: 51 pages, including 8 eps figures, to appear in ApJ, December 20 199