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Health survey in high background radiation areas in China
1980-08-22
The radiation level in some regions of Yangjiang County, Guangdong Province, is about three times that in the neighboring control areas, but lower than that in some parts of high background radiation areas in India and Brazil. Results of the health survey carried out between 1972 and 1975, which did not demonstrate any significant difference between inhabitants living in the high-background and control areas, suggest that the size of the population investigated may be not large enough to reveal minor increments of detrimental effects at such a low dose range of ionizing radiation. Further investigation of a larger population is necessary.
2009-01-01
The influence of mesoscale circulations induced by urban-rural differential surface sensible heat flux and roughness on convective boundary-layer (CBL) flow statistics over an isolated urban area has been examined using large-eddy simulation (LES). Results are analyzed when the circulations influence the entire urban area under a zero background wind. For comparison, the CBL flow over an infinite urban area with identical urban surface characteristics under the same background meteorological conditions is generated as a control case (without circulations). The turbulent flow over the isolated urban area exhibits a mix of streaky structure and cellular pattern, while the cellular pattern dominates in the control case. The mixed-layer height varies significantly over the isolated urban area,...
Trachoma Rapid Assessments in Unity and Northern Bahr-el-Ghazal States, Southern Sudan
BackgroundTrachoma is thought to be endemic over large parts of Southern Sudan, but empirical evidence is limited. While some areas east of the Nile have been identified as highly...Full Text Available
The mental health of populations directly and indirectly exposed to violent conflict in Indonesia
BackgroundLarge disasters affect people who live both near and far from the areas in which they occur. The mental health impact is expected to be similar to a ripple effect, where...Full Text Available
BackgroundElevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However,...Full Text Available
BackgroundDespite significant reduction of childhood mortality in Bangladesh, large spatial variations persist. Identification of lower level spatial units with higher concentrations...Full Text Available
CDK-Taverna: an open workflow environment for cheminformatics
BackgroundSmall molecules are of increasing interest for bioinformatics in areas such as metabolomics and drug discovery. The recent release of large open access chemistry databases...Full Text Available
Characterization of large area APDs for the EXO-200 detector
2009-06-16
EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.
A large area CCD X-ray detector for exotic atom spectroscopy
A large area, position and energy sensitive detector has been developed to study the characteristic X-radiation of exotic atoms in the few keV range. The detector, built up from an array of six high-resistivity CCDs, is used as the focal plane of a reflection-type crystal spectrometer. A large detection area is necessary because of the need to detect simultaneously two or more lines close in energy as well as broad structures like fluorescence X-rays from electronic atoms. The fine pixel structure provides accurate determination of the X-ray line position while the excellent background rejection capabilities of the CCD, using both energy and topographical discrimination, are essential in the high background environment of a particle accelerator.
BackgroundThe prevalence of asthma and allergic diseases has increased in industrialised countries, and it is known that rates vary according whether the area is urban or rural and...Full Text Available
Study of Hanford capability for solar energy research and development
The Hanford site provides unique capability for solar energy research and development. The basic attributes include large available land areas; consistent sunshine during much of the year (although not comparable to Arizona and the southwest U. S.); ex- treme temperatures for test purposes (--27 to 115 F); cooling water availability; ecology approximating ecology in some other solar areas; RgD facilities applicable to most solar technology; equipment immediately useful for solar energy programs; technology background in most areas of solar energy; experience with large energy systems, and background in systems analysis. From the solar energy production standpoint, the energy that falls on the 600 square miles at the Hanford site would produce 100,000 megawatts if 33 1/3% efficiency can be achieved. (MCW)n
Technology development for decontamination and decommissioning
1995-12-31
This paper describes the program being developed by the Morgantown Energy Technology Center for the U.S. Department of Energy Office of Technology Development to implement the Decontamination and Decommissioning Focus Area Program. Background information, basic operating principles, and the goals of large-scale demonstration projects are outlined. Ongoing and planned technology development areas for deactivation, decontamination, dismantlement, and disposition and recycle are listed.
Advanced Large Area Plastic Scintillator Project (ALPS): Final Report
2008-02-05
The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.
Large-Scale Compton Imaging for Wide-Area Surveillance
2006-03-01
We study the performance of a large-scale Compton imaging detector placed in a low-flying aircraft, used to search wide areas for rad/nuc threat sources. In this paper we investigate the performance potential of equipping aerial platforms with gamma-ray detectors that have photon sensitivity up to a few MeV. We simulate the detector performance, and present receiver operating characteristics (ROC) curves for a benchmark scenario using a {sup 137}Cs source. The analysis uses a realistic environmental background energy spectrum and includes air attenuation.
1998-11-01
The perturbation of the sulfate surface area density (SAD) in the tropopause region and the lower stratosphere by subsonic and supersonic aircraft fleets is examined. The background aerosol surface area, the conversion of fuel sulfur into new sulfate particles in aircraft plumes, and the plume mixing with ambient air control this perturbation. The background aerosol surface area is enhanced by the addition of ultrafine aerosol particles at cruise altitudes. The study includes recent findings concerning the formation and development of these particles in aircraft plumes. Large-scale SAD enhancements become relevant for background SAD levels below about 10 {mu}m{sup 2}/cm{sup 3}, even for moderate sulfate conversion fractions of 5%. Results from an analytic expression for the surface area changes are presented which contains the dependences on these parameters and can be employed in large-scale atmospheric models. (orig.) 11 refs.
2007-09-28
This report documents the results of preliminary surface geophysical exploration activities performed between October and December 2006 at the B, BX, and BY tank farms (B Complex). The B Complex is located in the 200 East Area of the U. S. Department of Energy's Hanford Site in Washington State. The objective of the preliminary investigation was to collect background characterization information with magnetic gradiometry and electromagnetic induction to understand the spatial distribution of metallic objects that could potentially interfere with the results from high resolution resistivity survey. Results of the background characterization show there are several areas located around the site with large metallic subsurface debris or metallic infrastructure.
Methodological studies for long range environmental gamma rate survey in Brazil
2009-01-01
The objective of this work is to support the establishment of a methodology for gamma radiation survey over large areas in order to estimate public exposure to natural background radiation in Brazil. In a first stage, two different sites close to large water bodies were chosen, Guanabara Bay, RJ and Amazon River close to Santarem, PA. Early results showed similar results for over water surveys despite the type of water body. Dose rates over land are higher than those over water, due to the natural radioactivity on soil, pavements and other building materials. In this study the focus was on variability of measurements performed in the same area and variability for different types of area, including roads and urbanized environments. Several measurements have been performed of several areas, that included roads and towns in Para, Bahia, Rio de Janeiro and Minas Gerais. Measurements ...
The manufacturing technology for large area twisted nematic displays with direct and 1:2 multiplex drive was developed. This includes special technologies for integrating the drives IC's into the front glases of the display. The manufacturing procedures were selected to be directly applicable for automated large quantity series production. Negative displays showing bright (colorless or colored) segments on a dark background were investigated. They require tighter production tolerances but show the brighter images required for car dashboards, test equipment, information boards, military equipment, avionic instrumentation, and medical equipment.
CHASING HIGHLY OBSCURED QSOs IN THE COSMOS FIELD
2009-01-01
A large population of heavily obscured, Compton-thick active galactic nuclei (AGNs) is predicted by AGN synthesis models for the cosmic X-ray background and by the relicsupermassive black hole mass function measured from local bulges. However, even the deepest X-ray surveys are inefficient to search for these elusive AGNs. Alternative selection criteria, combining mid-infrared with near-infrared, and optical photometry, have instead been successful in pinpointing a large population of Compton-thick AGNs. We take advantage of the deep Chandra and Spitzer coverage of a large area (more than 10 times the area covered by the Chandra deep fields, CDFs) in the Cosmic Evolution Survey (COSMOS) field to extend the search of highly obscured, Compton-thick active nuclei to higher luminosity. These sources have low surface density, and therefore large ...
Vision-based threat detection in dynamic environments.
This report addresses the development of automated video-screening technology to assist security forces in protecting our homeland against terrorist threats. A prevailing threat is the covert placement of bombs inside crowded public facilities. Although video-surveillance systems are increasingly common, current systems cannot detect the placement of bombs. It is also unlikely that security personnel could detect a bomb or its placement by observing video from surveillance cameras. The problems lie in the large number of cameras required to monitor large areas, the limited number of security personnel employed to protect these areas, and the intense diligence required to effectively screen live video from even a single camera. Different from existing video-detection systems designed to operate in nearly static environments, we are developing technology to detect changes in the background of dynamic environments: environments where motion and human activities are persistent over long periods. Our goal is to quickly detect background changes, even if the background is visible to the camera less than 5 percent of the time and possibly never free from foreground activity. Our approach employs statistical scene models based on mixture densities. We hypothesized that the background component of the mixture has a small variance compared to foreground components. Experiments demonstrate this hypothesis is true under a wide variety of operating conditions. A major focus involved the development of robust background estimation techniques that exploit this property. We desire estimation algorithms that can rapidly produce accurate background estimates and detection algorithms that can reliably detect background changes with minimal nuisance alarms. Another goal is to recognize unusual activities or foreground conditions that could signal an attack (e.g., large numbers of running people, people falling to the floor, etc.). Detection of background changes and/or unusual foreground activity can be used to alert security forces to the presence and location of potential threats. The results of this research are summarized in several MS Power-point slides included with this report.
Vision-based threat detection in dynamic environments.
2007-08-01
This report addresses the development of automated video-screening technology to assist security forces in protecting our homeland against terrorist threats. A prevailing threat is the covert placement of bombs inside crowded public facilities. Although video-surveillance systems are increasingly common, current systems cannot detect the placement of bombs. It is also unlikely that security personnel could detect a bomb or its placement by observing video from surveillance cameras. The problems lie in the large number of cameras required to monitor large areas, the limited number of security personnel employed to protect these areas, and the intense diligence required to effectively screen live video from even a single camera. Different from existing video-detection systems designed to operate in nearly static environments, we are developing technology to detect changes in the background of dynamic environments: environments where motion and human activities are persistent over long periods. Our goal is to quickly detect background changes, even if the background is visible to the camera less than 5 percent of the time and possibly never free from foreground activity. Our approach employs statistical scene models based on mixture densities. We hypothesized that the background component of the mixture has a small variance compared to foreground components. Experiments demonstrate this hypothesis is true under a wide variety of operating conditions. A major focus involved the development of robust background estimation techniques that exploit this property. We desire estimation algorithms that can rapidly produce accurate background estimates and detection algorithms that can reliably detect background changes with minimal nuisance alarms. Another goal is to recognize unusual activities or foreground conditions that could signal an attack (e.g., large numbers of running people, people falling to the floor, etc.). Detection of background changes and/or unusual foreground activity can be used to alert security forces to the presence and location of potential threats. The results of this research are summarized in several MS Power-point slides included with this report.
Radioactivity in soils of the Sao Paulo State, Brazil
2008-01-01
Full text: For proper management of soil and groundwater quality, background levels of toxic elements in a given ecosystem must be known. The main aim of the present study is to perform a radioactive characterization of representative soils from the Sao Paulo State, in order to determine background levels for some selected radionuclides, which could be used as a quality reference value. Soil types and sampling places were chosen according to their representativeness and spatial distribution in the State geological formations, taking also into account their nearness to large urban areas. Thirty samples were collected in areas presenting low antrophic perturbation - native vegetation or ancient reforestation -, minimizing the chances that selected areas could have sustained antrophic effects in recent past. Activity concentration of U-nat, Th-nat, 228Th, ...
2003-01-01
Cytogenetic investigation of stable type aberrations (translocations) was performed with our improved methods in 6 children and 15 elderly persons in a high background radiation area (HBRA) in China, and in 8 children and 11 elderly persons in a control area. The total numbers of cells analyzed in elderly persons were 68,297 in HBRA and 35,378 in controls and in children were 45,535 in HBRA and 56,198 in controls. On average 5138 cells per subject were analyzed. The variation in the frequencies of translocations per 1000 cells was small in children while it was large in elderly persons. No significant difference was found in the frequencies between HBRA and control (P
2010-01-01
ABSTRACT TeV photons from blazars at relatively large distances, interacting with the optical-infrared cosmic background, are efficiently converted into electron-positron pairs. The produced pairs are extremely relativistic (Lorentz factors of the order of Formula Not Shown ) and promptly lose their energy through inverse Compton scatterings with the photons of the microwave cosmic background, producing emission in the GeV band. The spectrum and the flux level of this reprocessed emission are critically dependent on the intensity of the intergalactic magnetic field, B, that can deflect the pairs diluting the intrinsic emission over a large solid angle. We derive a simple relation for the reprocessed spectrum expected from a steady source. We apply this treatment to the blazar 1ES 0229+200,...
Optical SETI with Imaging Cherenkov Telescopes
2005-06-30
The idea of searching for optical signals from extraterrestrial civilizations has become increasingly popular over the last five years, with dedicated projects at a number of observatories. The method relies on the detection of a brief (few ns), intense light pulse with fast photon detectors. Ground-based gamma-ray telescopes such as the Whipple 10m, providing a large mirror area and equipped with an array of photomultiplier tubes (PMTs), are ideal instruments for this kind of observation if the background of cosmic-ray events can be rejected. We report here on a method for searching for optical SETI pulses, using background discrimination techniques based on the image shape.
Report on the performance of a large-area, gamma-ray imager for search
2005-10-07
We are currently constructing a prototype, large-area, gamma-ray detector for conducting vehicle-mounted, mobile-search operations. The system is unique in that it relies on imaging to discriminate point sources of interest from the natural background variations. In a non-imaging instrument the background fluctuations mimic the signature seen from real sources at a distance and one is limited in sensitivity to detecting only those sources that overwhelm the local background variations --not just the counting statistics associated with a given measurement. The net result is that a larger detector is generally not more sensitive to detecting sources in the world at large. [1, 2] In a previous publication [3] we reported on the detection of a 1-mCi source at more than 80 meters from the detector using a proof-of-principle instrument (see Fig. 1) constructed to demonstrate how imaging removes the size limit on search instruments. In this report we document a systematic effort using the same detector to demonstrate that imaging detectors can reliably detect weak radiation sources at many 10's of meters. Specifically, we collected data on a 1-mCi {sup 137}Cs source 65 m from the path of the search instrument.
2009-01-01
The present work studied how much the meteorological parameters and the emission sources can influence the particulate polycyclic aromatic hydrocarbons (Invalid Journal Information PAHs) concentrations in two areas located in Southern Italy (Bari and Taranto). It was found that when the vehicular traffic is the main source of PAHs, there is a negative correlation between ambient temperature, wind speed and PAHs concentration (Bari). This is because these parameters are generally correlated with the dispersion capacity of the atmosphere. In the presence of a large industrial area, the wind direction becomes an important parameter able to determinate large changes in PAHs concentrations. This happened in Taranto where PAHs concentrations are exceptionally high. During the study the seasonal ...
A bibliography containing 1,212 references is presented with its focus on the general problem of reducing human exposure to the radionuclides contained in the tailings from the milling of uranium ore. The references are divided into seven broad categories: uranium tailings pile (problems and perspectives), standards and philosophy, etiology of radiation effects, internal dosimetry and metabolism, environmental transport, background sources of tailings radionuclides, and large-area decontamination. (JSR)
Roles of scattered radiation in SRIXE
1988-01-01
The scattering of x-rays is the major source of background and hence is a limiting factor in the minimum detectable limits available with SRIXE measurements. The scattering can be utilized for normalizing the net peak areas to fluctuations in sample thickness or mass on a relative basis or on a comparative basis. Even then measurement of the scattered x-rays should be made at backward angles. Measurement at forward angles should be avoided because of diffraction problems. The uncertainties in the measurement of an absolute intensity of the x-rays can be extremely large.
BackgroundMalaria control in Africa is most tractable in urban settlements yet most research has focused on rural settings. Elimination of malaria transmission from urban areas may...Full Text Available
Measuring velocites using the CMB & LSS
2006-07-01
Here is discussed various ways by which the cosmic microwave background (CMB) radiation can be use to measure the velocities of matter in the universe. We include some new statistical techniques for using the kinetic Sunyaev-Zel'dovich (kSZ) effect and integrated Sachs-Wolfe (ISW) effect to determine velocities by correlating wide area CMB maps with overlapping large-scale structure (LSS) surveys.
BackgroundDue to its history, with a high number of migration events, the Mediterranean basin represents a challenging area for population genetic studies. A large number of genetic...Full Text Available
Roles of scattered radiation in SRIXE
The scattering of x-rays is the major source of background and hence is a limiting factor in the minimum detectable limits available with SRIXE measurements. The scattering can be utilized for normalizing the net peak areas to fluctuations in sample thickness or mass on a relative basis or on a comparative basis. Even then measurement of the scattered x-rays should be made at backward angles. Measurement at forward angles should be avoided because of diffraction problems. The uncertainties in the measurement of an absolute intensity of the x-rays can be extremely large.
Plant life extension and acid rain control legislation
1987-01-01
The author discusses the control type of acid rain proposal. This type of bill calls for large scale reductions of sulfur dioxide emissions. The author discusses the specifics of the leading proposals later and gives some background on the acid rain debate. Other areas of the Clear Air Act (CAA) which deal with plant life extension are also discussed.
Full Text Available.BackgroundThe Firth of Clyde is a large inlet of the sea that extends over 100 km into Scotland's west coast.MethodsWe compiled detailed fisheries landings data for this area and combined them with historical accounts to build a picture of change due to fishing activity over the last 200 years.FindingsIn the early 19
PICO-LON Project for WIMPs search
2007-11-21
Highly segmented inorganic crystal has been shown to have good performance for dark matter search. The energy resolution of ultra thin and large area NaI(Tl) scintillator has been developed. The estimated sensitivity for spin-dependent excitation of 127I was discussed. The recent status of low background measurement at Oto Cosmo Observatory is reported
Measuring velocites using the CMB & LSS
Here is discussed various ways by which the cosmic microwave background (CMB) radiation can be use to measure the velocities of matter in the universe. We include some new statistical techniques for using the kinetic Sunyaev-Zel'dovich (kSZ) effect and integrated Sachs-Wolfe (ISW) effect to determine velocities by correlating wide area CMB maps with overlapping large-scale structure (LSS) surveys.
2009-01-01
Background, aim and scope In a gradualist approach to the introduction of crop biotechnology, the findings of experimentation at one scale are used to predict the outcome of moving to a higher scale of deployment. Movement through scales had occurred for certain genetically modified herbicide-tolerant (GMHT) crops in the UK as far as large-scale field trials. However, the land area occupied by these trials was still
Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
2008-06-19
We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) to indirectly detect weakly interacting massive particles (WIMPs) through the $\\gamma$-ray signal that their pair annihilation produces. WIMPs are among the favorite candidates to explain the compelling evidence that about 80% of the mass in the Universe is non-baryonic dark matter (DM). They are serendipitously motivated by various extensions of the standard model of particle physics such as Supersymmetry and Universal Extra Dimensions (UED). With its unprecedented sensitivity and its very large energy range (20 MeV to more than 300 GeV) the main instrument on board the GLAST satellite, the Large Area Telescope (LAT), will open a new window of discovery. As our estimates show, the LAT will be able to detect an indirect DM signature for a large class of WIMP models given a cuspy profile for the DM distribution. Using the current state of the art Monte Carlo and event reconstruction software developed within the LAT collaboration, we present preliminary sensitivity studies for several possible sources inside and outside the Galaxy. We also discuss the potential of the LAT to detect UED via the electron/positron channel. Diffuse background modeling and other background issues that will be important in setting limits or seeing a signal are presented.
1991-11-01
This report summarizes background and experiences from forest soil treatments in southern Germany, where large areas have been treated with limestone and fertilized with phosphorus and potassium. Comparisons is made with air pollution exposed forest areas in southern Sweden, and the need for remedial actions is discussed from different viewpoints regarding soil treatments: * To prevent further soil acidification, * Soil restoration regarding base cations and other nutrients, * Remedy existing or expected nutrient shortages in forest stands, and * Compensate for biomass harvesting. 18 refs.
2009-01-01
The Gamma Ray Large Area Space Telescope (GLAST) is a space mission that will detect photons from the gamma ray sky, in the rich yet poorly explored high energy band between 20MeV and 1TeV. Main instrument on board is the Large Area Telescope (LAT), a gamma-ray pair-conversion telescope, that will measure direction and energy of incoming photons by means of a very large (11.000 sensors), low pitch (228 (micro)m) Silicon strip Tracker and an imaging CsI e.m. calorimeter, supported in the rejection of charged particles background by an outer, segmented Anti-Coincidence Detector built with plastic scintillators. The superior angular resolution of the LAT, coupled to its very large field of view, results in a sensitivity advance of a factor 30 or more with respect to previously flown instruments. This will allow GLAST to locate currently unresolved gamma ray sources and to detect ...
Zone-wise variation of indoor radon levels in urban Hyderabad: a case study
2006-01-01
Hyderabad, the capital of Andhra Pradesh, is the fifth biggest city in the country with a population of about 6 million and spanning over an area of approximately 1000 sq. km. This area forming a part of peninsular gneissic complex is designated as unclassified crystalline strata, consisting of pink and gray granites, granitic banded gneisses, pegmatites, quartz veins and dolerite dykes. Previous sample studies in India based on geology and TLDs, presented a relatively higher background radiation levels and higher concentrations of radioactive elements such as uranium, thorium and potassium in the study area. With these interesting results, a detailed study on radon and its progeny levels was made in the urban Hyderabad area. The measured indoor radon and its progeny levels were found to vary from 17 to 311 Bq. m-3 and 0.1 to 20 mW, respectively. Such a large ...
Regional background assessment of groundwater wells in the Greater Hudson Hope Area
2003-01-01
The initial exploration activities for coalbed methane (CBM) development in the Hudson Hope area of British Columbia (BC) have now begun. This baseline survey of water resources was conducted as a result of concerns over the impacts of CBM development on water quality and quantity. Eight environmental monitoring sites were located and water samples were collected to analyze potability, dissolved metals, and extractable petroleum hydrocarbons. Quantity data were collected to measure static water levels as well as to obtain flow measurements on springs and creeks. The study also included a review of surficial and bedrock geology in order to identify aquifers. Risk areas were identified in order to increase monitoring activities at sites requiring higher levels of protection. Risk areas included the Peace River Terrace, which has a large fluvial deposit of gravels and sands ...
Identification of sources of environmental lead in South Africa from surface soil geochemical maps
2010-01-01
The bioavailability of lead in soil is of considerable importance to human and animal health. Although selective extraction has been explored as a more appropriate technique than total heavy metal analysis in environmental pollution assessments, such studies remain scarce globally and are almost non-existent in developing countries. Results for a large-scale study of extractable lead levels in undisturbed soil samples in South Africa identify several geographic areas of concern. Lead levels are considerably elevated relative to background levels in the Johannesburg urban and industrial area. Areas of active lead mining also exhibit higher surface soil values. Interestingly, areas of active and intensive coal mining activity display relatively low soil Pb values, possibly attributable to th...
2009-01-01
In this study, the natural Cu background concentration and Cu natural and anthropogenic contamination in soil, water and crop were investigated systematically in Huangshi area. The results show that regional geology is the dominant factor controlling the natural Cu background concentration in soil and water, and that pH is important to control the vertical distribution of Cu in soil under the same geographical and climatic conditions. The mineralization of rock bodies causes the natural Cu increase in soil and water, whereas, a large number of mining-smelting plants and chemical works are the main sources of Cu anthropogenic contamination. Cu in naturally and anthropogenically polluted soil displays differences in total and available contents, vertical distribution patterns and physico-chemical properties, the same happens in water. - Consider the ...
2006-01-01
Scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces a polarization signal proportional to the CMB quadrupole anisotropy at the cluster's location and lookback time. A survey of such remote quadrupole measurements provides information about large-scale cosmological perturbations. This paper presents a formalism for calculating the correlation function of remote quadrupole measurements in spherical harmonic space. The number of independent modes probed by both single-redshift and volume-limited surveys is presented, along with the length scales probed by these modes. In a remote quadrupole survey sparsely covering a large area of sky, the largest-scale modes probe the same-length scales as the quadrupole but with much narrower Fourier-space window functions. The largest-scale modes are significantly correlated with the local ...
UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION
A phoswich radiation detector is comprised of a phosphor sandwich in which several different phosphors are viewed by a common photomultiplier. By selecting the appropriate phosphors, this system can be used to simultaneously measure multiple radiation types (alpha, beta, gamma and/or neutron) with a single detector. Differentiation between the signals from the different phosphors is accomplished using digital pulse shape discrimination techniques. This method has been shown to result in accurate discrimination with highly reliable and versatile digital systems. This system also requires minimal component count (i.e. only the detector and a computer for signal processing). A variety of detectors of this type have been built and tested including: (1) a triple phoswich system for alpha/beta/gamma swipe counting, (2) two well-type detectors for measuring low levels of low energy photons in the presence of a high energy background, (3) a large area detector for measuring beta contamination in the presence of a photon background, (4) another large area detector for measuring low energy photons from radioactive elements such as uranium in the presence of a photon background. An annular geometry, triple phoswich system optimized for measuring alpha/beta/gamma radiation in liquid waste processing streams is currently being designed.
UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION
2003-04-15
A phoswich radiation detector is comprised of a phosphor sandwich in which several different phosphors are viewed by a common photomultiplier. By selecting the appropriate phosphors, this system can be used to simultaneously measure multiple radiation types (alpha, beta, gamma and/or neutron) with a single detector. Differentiation between the signals from the different phosphors is accomplished using digital pulse shape discrimination techniques. This method has been shown to result in accurate discrimination with highly reliable and versatile digital systems. This system also requires minimal component count (i.e. only the detector and a computer for signal processing). A variety of detectors of this type have been built and tested including: (1) a triple phoswich system for alpha/beta/gamma swipe counting, (2) two well-type detectors for measuring low levels of low energy photons in the presence of a high energy background, (3) a large area detector for measuring beta contamination in the presence of a photon background, (4) another large area detector for measuring low energy photons from radioactive elements such as uranium in the presence of a photon background. An annular geometry, triple phoswich system optimized for measuring alpha/beta/gamma radiation in liquid waste processing streams is currently being designed.
2010-06-24
Incoherent background can create an intrinsic problem for standard small angle neutron scattering measurements. Biological samples contain hydrogen which is a strong incoherent scatterer thus creating an intrinsic source of background that makes determination of the coherent scattering parameters difficult in special situations. This can especially be true for the Q-range from around 0.1-0.5 \\AA^-1 where improper knowledge of the background level can lead to ambiguity in determination of the samples structure parameters. Polarization analysis is a way of removing this ambiguity by allowing one to distinguish the coherent from incoherent scattering, even when the coherent scattering is only a small fraction of the total scattered intensity. ^3He spin filters are ideal for accomplishing this task because they permit the analysis of large area and large divergence scattered neutron beams without adding to detector background or changing the prorogation of the scattered neutron beam. This rapid note describes the application of ^3He neutron spin filters, polarized using the spin-exchange optical pumping method, for polarization analysis on a protein sample to unambiguously extract the coherent scattered intensity.
2002-01-01
This report compiles background information that can be used in planning appropriate countermeasures for forest and park areas in Denmark, Sweden, Finland and Norway, in case a nuclear accident results in large-scale contamination of forests. The information is formulated to inform the forestry sector and radiation protection experts about the practicality of both forest management techniques and mechanical cleanup methods, for use in their planning of specific strategies that can lead to an optimal use of contaminated forests. Decisions will depend on the site and the actual situation after radioactive deposition to forested areas, but the report provides background information from investigations performed before an accident occurs that will make the process more effective. The report also discusses the radiological consequences of producing energy from biomass contaminated by a major nuclear accident, both in the context of normal bio-fuel energy production and as a means of reducing potentially severe environmental problems in the forest by firing power plants with highly contaminated forest biomass. (au)
1978-01-01
Construction and properties of a gridded ionization chamber for alpha-paricle spectrometry of low-level large-area samples are presented. Great importance was attached to high spectrometric resolution, low background, long-term stability, simple construction and operation, and easy decontamination if necessary. Using modern charge-sensitive preamplifiers spectrometric resolution is 20,6 keV FWHM (0,4%) at 5,30 MeV over the total effective area of 300 m2. Counting gas is an argon-methane mixture (P-10 gas) at atmospheric pressure. Background is 13 cph in the energy interval from 4 to 6 MeV and minimum detectable activity is 0.01 pCi Pu-239 at 1000 min measuring time. Ionization chambers of this type are used for direct alpha-spectrometric surveillance of long-lived alpha-emitting nuclides in the atmosphere ...
The Anti-Coincidence Detector for the GLAST Large Area Telescope
2007-03-23
This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.
The Anti-Coincidence Detector for the GLAST Large Area Telescope
2007-02-21
This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of ~8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.
The Anti-Coincidence Detector for the GLAST Large Area Telescope
This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.
Mathematical modeling as a tool for planning anticancer therapy
2009-01-01
We review a large volume of literature concerning mathematical models of cancer therapy, oriented towards optimization of treatment protocols. The review, although partly idiosyncratic, covers such major areas of therapy optimization as phase-specific chemotherapy, antiangiogenic therapy and therapy under drug resistance. We start from early cell cycle progression models, very simple but admitting explicit mathematical solutions, based on methods of control theory. We continue with more complex models involving evolution of drug resistance and pharmacokinetic and pharmacodynamic effects. Then, we consider two more recent areas: angiogenesis of tumors and molecular signaling within and among cells. We discuss biological background and mathematical techniques of this field, which has a large...
2010-01-01
Precise calibration of monitors and dosimeters for use with high energy neutrons necessitates reliable and accurate neutron fluences being evaluated with use of a reference point. A highly efficient Proton Recoil counter Telescope (PRT) to make absolute measurements with use of a reference point was developed to evaluate neutron fluences in quasi-monoenergetic neutron fields. The relatively large design of the PRT componentry and relatively thick, approximately 2 mm, polyethylene converter contributed to high detection efficiency at the reference point over a large irradiation area at a long distance from the target. The polyethylene converter thickness was adjusted to maintain the same carbon density per unit area as the graphite converter for easy background subtraction. The high detection efficiency and thickness adjustment resulted in efficient absolute ...
2010-01-01
Precise calibration of monitors and dosimeters for use with high energy neutrons necessitates reliable and accurate neutron fluences being evaluated with use of a reference point. A highly efficient Proton Recoil counter Telescope (PRT) to make absolute measurements with use of a reference point was developed to evaluate neutron fluences in quasi-monoenergetic neutron fields. The relatively large design of the PRT componentry and relatively thick, approximately 2mm, polyethylene converter contributed to high detection efficiency at the reference point over a large irradiation area at a long distance from the target. The polyethylene converter thickness was adjusted to maintain the same carbon density per unit area as the graphite converter for easy background subtraction. The high detectio...
2009-01-01
Background: To assess the participation rate and results of cytological assessment in the context of cervical cancer screening activities in an area of Barcelona (Spain) with a large immigrant population. Methods: Descriptive retrospective study of cytologies performed between 2001 and 2006 in women ≥14 years of age living in 2 out of 10 districts of Barcelona (n = 129 327) and participating in cervical cancer screening activities within a sexual and reproductive health care programme. Results: Between 2001 and 2006, overall participation among women aged 20- to 64-years old was 50.7%, with higher participation among women aged 20-34 years than among those aged 50-64 years (63.8 and 36.0%, respectively; P
Occurrence and sources of selected phenolic endocrine disruptors in Ria de Aveiro, Portugal
2010-01-01
Background, aim and scope Ria de Aveiro (Portugal) is a shallow coastal lagoon of high economic and ecological importance. Hardly any data on its chemical pollution by polar organic pollutants are available in literature. This study focused on the presence and sources of a series of phenolic endocrine-disrupting compounds (EDCs) in this area, including parabens, alkylphenolic compounds and bisphenol-A (BPA). A number of possible sources of pollution are present in the area, including the large harbours present in the lagoon, the city of Aveiro and the rivers discharging into the area. A recently constructed submarine wastewater outfall, located a few kilometres from the lagoon inlet has also been suggested as a possible source of pollution to Ria de Aveiro in several publications. The aim ...
2004-12-01
This report describes a data-base that covers entire Sweden with regard to various geographical parameters with implications to simulation of groundwater circulation on a regional and continental scale. The data-base include topography, stream network properties, and-use and water chemistry for limited areas. Furthermore, the report describes a computational (finite difference) code that solves the continuum equation for laminar, stationary and isotropic groundwater flow. The formulation accounts for a free groundwater surface except where the groundwater recharge into the stream network and lake bottoms. The theoretical background of the model is provided and the codes are described. The report also contain a simple user manual in a Matlab environment and provides and example calculation for the Forsmark area, Uppland, Sweden.
The geothermal resources of the Green River basin were investigated. Oil-well bottom-hole temperatures, thermal logs of wells, and heat flow data have been interpreted within a framework of geologic and hydrologic constraints. Basic thermal data, which includes the background thermal gradient and the highest recorded temperature and corresponding depth is tabulated. It was concluded that large areas are underlain by water at temperatures greater than 120/sup 0/F. Although much of this water is too deep to be economically tapped solely for geothermal use, oil and gas wells presently provide access to this significant geothermal resource. Isolated areas with high temperature gradients exist. These areas - many revealed by hot springs - represent geothermal systems which might presently be developed economically. 34 refs., 11 figs., 8 tabs. (ACR)
1985-01-01
The geothermal resources of the Green River basin were investigated. Oil-well bottom-hole temperatures, thermal logs of wells, and heat flow data have been interpreted within a framework of geologic and hydrologic constraints. Basic thermal data, which includes the background thermal gradient and the highest recorded temperature and corresponding depth is tabulated. It was concluded that large areas are underlain by water at temperatures greater than 120/sup 0/F. Although much of this water is too deep to be economically tapped solely for geothermal use, oil and gas wells presently provide access to this significant geothermal resource. Isolated areas with high temperature gradients exist. These areas - many revealed by hot springs - represent geothermal systems which might presently be developed economically. 34 refs., 11 figs., 8 tabs. (ACR)
Energy requirements for rural development
This study on the role of energy in the development of rural areas was originally conducted in the spring and summer of 1985. It was intended to serve as a background paper for the preparation of a program plan for the Office of Energy of the United States Agency for International Development. As such it begins with a brief overview of how rural development fits into national development, then offers a comprehensive framework for thinking about rural development in particular and the energy implications of the various components of rural development. Agriculture naturally comes to mind when rural areas are mentioned, but industry is an important component of rural activity as well. Consequently, both agricultural and nonagricultural energy use is discussed. Modernization of rural areas will change household, as well as production, energy use. However, household energy use is a veritable subject in its own right, with a large literature. Consequently, that topic is discussed in less detail than the production energy topics.
Energy requirements for rural development
1988-06-01
This study on the role of energy in the development of rural areas was originally conducted in the spring and summer of 1985. It was intended to serve as a background paper for the preparation of a program plan for the Office of Energy of the United States Agency for International Development. As such it begins with a brief overview of how rural development fits into national development, then offers a comprehensive framework for thinking about rural development in particular and the energy implications of the various components of rural development. Agriculture naturally comes to mind when rural areas are mentioned, but industry is an important component of rural activity as well. Consequently, both agricultural and nonagricultural energy use is discussed. Modernization of rural areas will change household, as well as production, energy use. However, household energy use is a veritable subject in its own right, with a large literature. Consequently, that topic is discussed in less detail than the production energy topics.
2010-01-01
The diversity of soils within the specially protected natural territory of Pokrovskoe-Streshnevo in Moscow is discussed. The soils of this large park are not affected by the modern construction activities that delete the features inherited from the early stages of the anthropogenic transformation of soils in Moscow. They are characterized by the book-like type of soil memory, which makes it possible to trace several sequences of the anthropogenic soil transformation. The background natural soils-rzhavozems (Chromic Cambisols)have been transformed into agrogenic soils (agrosols) and postagrogenic soils (postagrosols) under abandoned plowlands, into urbo-soils and urbanozems in the areas of former or modern settlements, and into techno-soils in the areas of active excavation works and eng...
Anthropogenic radionuclides in seawater of the Far Eastern Seas
1999-09-30
Large quantities of radioactive wastes have been dumped in the Far Eastern Seas by the former Soviet Union and the Russian Federation, and small amounts of radioactive wastes have been dumped by Japan and the Republic of Korea. In order to investigate the concentrations of anthropogenic radionuclides in the nine dumping areas, a second expedition was conducted in 1995 by Japan, the Republic of Korea, the Russian Federation and IAEA, following the first expedition in 1994. The results show that 137Cs, 90Sr and 239+240Pu concentrations in surface and bottom waters at dumping areas do not significantly differ from the values observed in background areas, and from historical values. There is no clear effect of possible contamination due to radioactive waste dumping. The concentrations and water column inventories of 137Cs, 90Sr and 239+240Pu in the Far Eastern seas are controlled by physical oceanic processes such as horizontal transport and biogeochemical processes such as scavenging.
A mobile high resolution gamma ray spectrometry system for radiological surveys. Final report
1998-01-01
Magnox Electric has developed a mobile large area radiological survey system designed to produce a rapid and cost effective characterization of outdoor land areas. The system combines the technique of high resolution gamma ray spectrometry, which is capable of rapidly identifying and quantifying specific radionuclides at levels well below those normally associated with natural background radiation, with modern automated surveying techniques that facilitate navigation and provide assurance as to the location of contamination. A dedicated software system supports survey operations, providing real time displays detailing spectrometry and navigational data capture, and enabling seamless remote switching between positioning methods. In open areas with an unrestricted line of sight to satellites Differential Global Positioning System (DGPS) technology ...
Improvement in human vision under bright light: grain or gain?
1987-12-01
Full Text Available.1. The factor by which increment threshold changes with changing background intensity is less if the test flash is small than if it is large. This is commonly attributed to a reduction of the area over which visual signals are integrated as light adaptation increases. 2. We propose and test an alternative hypothesis that the change in slope is the result of purely local processes: if it is assumed that increasing the background intensity increases the exponent of the local response function, but does not alter the extent of spatial integration, then the threshold of the small test flash will rise more slowly than the threshold of the large test flash simply because the small test flash is of a higher intensity than the large and therefore evokes a correspondingly greater local response. 3. We measured small and large test field increment thresholds and dichoptic brightness matches as a function of background intensity. 4. The log-log slopes of the small and large field increment threshold functions differed by not more than about 20%, suggesting that even under the conventional interpretation of such data, the change of spatial integration is less than is usually supposed. 5. The intensity of a large (2.3 deg) suprathreshold test field matched to a standard in the other eye varies with increasing background intensity with the same shallow slope as the small test (2.6 min) threshold versus intensity function; this is in agreement with the predictions of the local non-linearity hypothesis and suggests that there is no substantial change in spatial integration during light adaptation.
Regionalization of organic pollutants in Bavarian soils: The performance of Indicator Kriging
2010-01-01
The evaluation of the impact of additional soil pollutants has to be contrasted against the naturally occurring pollutant concentration, i.e., the background concentration. Because background concentrations have to represent areal entities, point information has to be extrapolated into the area using interpolation methods. Thus, the accuracy of the interpolation method is crucial for the correct designation of background values to the areas. For the area of Bavaria (SE Germany), the actual background values of organic and inorganic soil pollutants were derived from
Body Fixed Frame, Rigid Gauge Rotations and Large N Random Fields in QCD
The "body fixed frame" with respect to local gauge transformations is introduced. Rigid gauge "rotations" in QCD and their \\Sch equation are studied for static and dynamic quarks. Possible choices of the rigid gauge field configuration corresponding to a nonvanishing static colormagnetic field in the "body fixed" frame are discussed. A gauge invariant variational equation is derived in this frame. For large number N of colors the rigid gauge field configuration is regarded as random with maximally random probability distribution under constraints on macroscopic--like quantities. For the uniform magnetic field the joint probability distribution of the field components is determined by maximizing the appropriate entropy under the area law constraint for the Wilson loop. In the quark sector the gauge invariance requires the rigid gauge field configuration to appear not only as a background but also as inducing an instantaneous quark-quark interaction. Both are random in the large N limit.
2009-02-09
For several decades now, wide-field coded mask cameras have been used with success to localise Gamma-ray bursts (GRBs). In these instruments, the event count rate is dominated by the photon background due to their large field of view and large effective area. It is therefore essential to estimate the instrument background expected in orbit during the early phases of the instrument design in order to optimise the scientific performances of the mission. We present here a detailed study of the instrument background and sensitivity of the coded-mask camera for X- and Gamma-rays (CXG) to be used in the detection and localisation of high-redshift GRBs on-board the international GRB mission SVOM. To compute the background spectrum, a Monte-Carlo approach was used to simulate the primary and secondary interactions between particles from the main components of the space environment that SVOM will encounter along its Low Earth Orbit (LEO) (with an altitude of 600 km and an inclination of ~ 30 deg) and the body of the CXG. We consider the detailed mass model of the CXG in its latest design. According to our results, i) the design of the passive shield of the camera ensures that in the 4-50 keV imaging band the cosmic X-Gamma-ray background is dominant whilst the internal background should start to become dominant above 70-90 keV; ii) the current camera design ensures that the CXG camera will be more sensitive to high-redshift GRBs than th e Swift Burst Alert Telescope thanks to a low-energy threshold of 4 keV.
Earth occultation technique with EGRET calorimeter data above 1 MeV
1997-01-01
The technique of earth occultation has produced many exciting results from the BATSE data. We examine the possibility of using this technique on the Total Absorption Shower Calorimeter (TASC) of EGRET. The TASC has an effective area of a few 1000 cm2 and is 8 radiation lengths deep. Spectra from 1-200 MeV are collected every 33 sec and the rate at 4 energies is monitored every 2 sec. The detector is unshielded and uncollimated so the background is large. The statistical error on the background measurements require several days of exposure to detect the Crab at the lowest energies. Longer exposures would be needed due to systematic errors in determining the background. However, the wide field of view (the effective area is nearly 1000 cm2 even through the back of the spacecraft) could be used to monitor variability and confirm fluxes of sources such as the black ...
The GLAST Large Area Telescope Detector Performance Monitoring
2007-10-16
The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration & Test and Commissioning of the instrument on ground.
Search for Gamma-rays from Lightest Kaluza-Klein ParticleDark Matter with GLAST
The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT), GLAST main instrument, has a wide field of view (> 2 sr), a large effective area and a 20 MeV-300 GeV energy range. It provides excellent high-energy gamma-ray observations for Dark-Matter searches. Here we study the possibility to detect gamma-rays coming from Lightest Kaluza-Klein Particle (LKP) annihilations in the context of the minimal Universal Extra Dimensions (UED) models. We perform the analysis for different LKP masses and for a Galactic Center (GC) Navarro, Frenk and White (NFW) halo model modified by a boost factor parameter. Finally we give an estimate of the background to obtain the expected total gamma-ray flux and the corresponding expected GLAST sensitivity.
Search for Gamma-rays from Lightest Kaluza-Klein ParticleDark Matter with GLAST
The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT), GLAST main instrument, has a wide field of view (> 2 sr), a large effective area and a 20 MeV-300 GeV energy range. It provides excellent high-energy gamma-ray observations for Dark-Matter searches. Here we study the possibility to detect gamma-rays coming from Lightest Kaluza-Klein Particle (LKP) annihilations in the context of the minimal Universal Extra Dimensions (UED) models. We perform the analysis for different LKP masses and for a Galactic Center (GC) Navarro, Frenk and White (NFW) halo model modified by a boost factor parameter. Finally we give an estimate of the background to obtain the expected total gamma-ray flux and the corresponding expected GLAST sensitivity.
Search for Gamma-rays from Lightest Kaluza-Klein ParticleDark Matter with GLAST
2006-05-16
The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT), GLAST main instrument, has a wide field of view (> 2 sr), a large effective area and a 20 MeV-300 GeV energy range. It provides excellent high-energy gamma-ray observations for Dark-Matter searches. Here we study the possibility to detect gamma-rays coming from Lightest Kaluza-Klein Particle (LKP) annihilations in the context of the minimal Universal Extra Dimensions (UED) models. We perform the analysis for different LKP masses and for a Galactic Center (GC) Navarro, Frenk and White (NFW) halo model modified by a boost factor parameter. Finally we give an estimate of the background to obtain the expected total gamma-ray flux and the corresponding expected GLAST sensitivity.
Large Area Imaging Detector for Long-Range, Passive Detection of Fissile Material
Recent events highlight the increased risk of a terrorist attack using either a nuclear or a radiological weapon. One of the key needs to counter such a threat is long-range detection of nuclear material. Theoretically, gamma-ray emissions from such material should allow passive detection to distances greater than 100 m. However, detection at this range has long been thought impractical due to fluctuating levels of natural background radiation. These fluctuations are the major source of uncertainty in detection and mean that sensitivity cannot be increased simply by increasing detector size. Recent work has shown that this problem can be overcome through the use of imaging techniques. In this paper we describe the background problems, the advantages of imaging and the construction of a prototype, large-area (0.57 m{sup 2}) gamma-ray imager to detect nuclear materials at distances of {approx}100 m.
Large Area Imaging Detector for Long-Range, Passive Detection of Fissile Material
2003-10-29
Recent events highlight the increased risk of a terrorist attack using either a nuclear or a radiological weapon. One of the key needs to counter such a threat is long-range detection of nuclear material. Theoretically, gamma-ray emissions from such material should allow passive detection to distances greater than 100 m. However, detection at this range has long been thought impractical due to fluctuating levels of natural background radiation. These fluctuations are the major source of uncertainty in detection and mean that sensitivity cannot be increased simply by increasing detector size. Recent work has shown that this problem can be overcome through the use of imaging techniques. In this paper we describe the background problems, the advantages of imaging and the construction of a prototype, large-area (0.57 m{sup 2}) gamma-ray imager to detect nuclear materials at distances of {approx}100 m.
Large Area Imaging Detector for Long-Range, Passive Detection Of Fissile Material
Recent events highlight the increased risk of a terrorist attack using either a nuclear or a radiological weapon. One of the key needs to counter such a threat is long-range detection of nuclear material. Theoretically, gamma-ray emissions from such material should allow passive detection to distances greater than 100 m. However, detection at this range has long been thought impractical due to fluctuating levels of natural background radiation. These fluctuations are the major source of uncertainty in detection and mean that sensitivity cannot be increased simply by increasing detector size. Recent work has shown that this problem can be overcome through the use of imaging techniques. In this paper we describe the background problems, the advantages of imaging and the construction of a prototype, large-area (0.57 m{sup 2}) gamma-ray imager to detect nuclear materials at distances of {approx}100 m.
Large Area Imaging Detector for Long-Range, Passive Detection Of Fissile Material
2004-07-30
Recent events highlight the increased risk of a terrorist attack using either a nuclear or a radiological weapon. One of the key needs to counter such a threat is long-range detection of nuclear material. Theoretically, gamma-ray emissions from such material should allow passive detection to distances greater than 100 m. However, detection at this range has long been thought impractical due to fluctuating levels of natural background radiation. These fluctuations are the major source of uncertainty in detection and mean that sensitivity cannot be increased simply by increasing detector size. Recent work has shown that this problem can be overcome through the use of imaging techniques. In this paper we describe the background problems, the advantages of imaging and the construction of a prototype, large-area (0.57 m{sup 2}) gamma-ray imager to detect nuclear materials at distances of {approx}100 m.
Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Data Handling Overview
The GLAST Balloon Flight Engineering Model (BFEM) represents one of 16 towers that constitute the Large Area Telescope (LAT), a high-energy (>20 MeV) gamma-ray pair-production telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006. The prototype tower consists of a Pb/Si pair-conversion tracker (TKR), a CsI hodoscopic calorimeter (CAL), an anti-coincidence detector (ACD) and an autonomous data acquisition system (DAQ). The self-triggering capabilities and performance of the detector elements have been previously characterized using positron, photon and hadron beams. External target scintillators were placed above the instrument to act as sources of hadronic showers. This paper provides a comprehensive description of the BFEM data-reduction process, from receipt of the flight data from telemetry through event reconstruction and background rejection cuts. The goals of the ground analysis presented here are to verify the functioning of the instrument and to validate the reconstruction software and the background-rejection scheme.
2004-01-01
Cosmic-ray background fluxes were modeled based on existing measurements and theories and are presented here. The model, originally developed for the Gamma-ray Large Area Space Telescope (GLAST) Balloon Experiment, covers the entire solid angle (${\\rm 4\\pi sr}$), the sensitive energy range of the instrument (${\\rm \\sim 10 MeV to 100 GeV}$) and abundant components (proton, alpha, $e^{-}$, $e^{+}$, $\\mu^{-}$, $\\mu^{+}$ and gamma). It is expressed in analytic functions in which modulations due to the solar activity and the Earth geomagnetism are parameterized. Although the model is intended to be used primarily for the GLAST Balloon Experiment, model functions in low-Earth orbit are also presented and can be used for other high energy astrophysical missions. The model has been validated via comparison with the data of the GLAST Balloon Experiment.
Surface morphology and evolution of amorphous carbon thin films
2007-01-01
The surface morphology of disordered carbon films grown by nanosecond pulsed laser ablation of graphite is reviewed. It is shown that the presence of a background gas can have a profound effect on the plume of material ejected during ablation. At low pressures smooth films are produced but at higher pressures rough films with an evolution from a nodular morphology to a large area cluster-assembled morphology occurs. The surface morphology changes with increasing background pressure as a result of collisions, which reduce the kinetic energy of the ejected material and allow for cluster formation within the plume. It is shown that the energy of some of the carbon ablated species in vacuum can exceed 100eV. The nature of the species present in the plume is discussed in terms of electroni...
1981-01-01
A combination of natural processes and man's activities has increased subsidence rates and faulting in several areas of coastal Louisiana and Texas. Subsurface stress caused by the withdrawal of large volumes of fluid has been shown to accelerate subsidence and fault movement in some cases. To evaluate the effects of geopressured-geothermal fluid withdrawals, background rates of ground movement must be determined and compared with rates of movement during and after fluid production. A program for monitoring subsidence and faulting, which is based on microseismic monitoring, tiltmeter monitoring, and repeated leveling surveys, is underway at the geopressured-geothermal test well sites in Louisiana and Texas. Changes in subsidence rates and fault activity which can be attributed to geopressured-geothermal fluid withdrawal must be of sufficient magnitude to be distinguished from background activity.
Isotropic Gamma-Ray Background: Cosmic-Ray Induced Albedo from Debris in the Solar System?
2009-01-06
We calculate the gamma-ray albedo due to cosmic-ray interactions with debris (small rocks, dust, and grains) in the Oort Cloud. We show that under reasonable assumptions a significant proportion of what is called the "extragalactic gamma-ray background" could be produced at the outer frontier of the solar system and may be detectable by the Large Area Telescope, the primary instrument on the Fermi Gamma-Ray Space Telescope. If detected it could provide unique direct information about the total column density of material in the Oort Cloud that is difficult to access by any other method. The same gamma ray production process takes place in other populations of small solar system bodies such as Main Belt asteroids, Jovian and Neptunian Trojans, and Kuiper Belt objects. Their detection can be used to constrain the total mass of debris in these systems.
2009-01-01
A high performance digital architecture for the implementation of a non-linear image enhancement technique is proposed in this paper. The image enhancement is based on a luminance dependent non-linear enhancement algorithm which achieves simultaneous dynamic range compression, colour consistency and lightness rendition. The algorithm provides better colour fidelity, enhances less noise, prevents the unwanted luminance drop at the uniform luminance areas, keeps the `bright' background unaffected, and enhances the `dark' objects in `bright' background. The algorithm contains a large number of complex computations and thus it requires specialized hardware implementation for real-time applications. Systolic, pipelined and parallel design techniques are utilized effectively in the proposed FPGA...
ATLAS MDT chamber behaviour after neutron irradiation and in a high rate background
2007-01-01
Many of the physics processes of interest at the Large Hadron Collider (LHC) will involve muon production in the final state. The Monitored Drift Tube (MDT) chambers, the precision tracking elements of the ATLAS muon spectrometer, are the main tools for the muon identification and measurement. They will operate in the harsh LHC background environment, mainly due to low energy photons and neutrons which will dominate the counting rate in most areas of the spectrometer, where an overall maximum counting rate of Formula Not Shown is expected. The upgrade to Super-LHC will involve fluxes ten times higher. To study the behaviour of MDT chambers under massive neutron irradiation at the level of Super-LHC, a test was performed at the "Tapiro" Neutron Facility of the ENEA "La Casaccia" Research Ce...
2009-01-01
We develop an algorithm of separating the E and B modes of the cosmic microwave background (CMB) polarization from the noisy and discretized maps of Stokes parameters Q and U in a finite area. A key step of the algorithm is to take a wavelet-Galerkin discretization of the differential relation between the E, B and Q, U fields. This discretization allows derivative operator to be represented by a matrix, which is exactly diagonal in scale space, and narrowly banded in spatial space. We show that the effect of boundary can be eliminated by dropping a few discrete wavelet transform modes, located on or nearby the boundary. This method reveals that the derivative operators will cause large errors in the E and B power spectra on small scales if the Q and U maps contain Gaussian noise. It also reveals that if the Q and U maps are random, these fields lead to the mixing of E and B modes. Consequently, ...
2010-01-01
Full Text Available.BackgroundIdentifying and understanding the early molecular events that underscore mineral pathogenicity using in vitro screening tests is imperative, especially given the large number of synthetic and natural fibers and particles being introduced into the environment. The purpose of the work described here was to examine the ability of gene profiling (Affymetrix microarrays) to predict the pathogenicity of various materials in a human mesothelial cell line (LP9/TERT-1) exposed to equal surface area concentrations (15×10
2010-07-01
After lengthy deliberations several European countries now gathered to build spallation source ESS (European Spallation Source). This is by far the world's most powerful neutron source, and a very useful tool in a range of scientific disciplines. After strong competing last year between the two strongest candidates, Bilbao in Spain and Lund in Sweden, the final choice fell on Lund on the 28th of May 2009. This decision has, among other things, its background in the extensive cooperation between the Scandinavian countries in this area. (AG)
SONTRAC--A low background, large area solar neutron spectrometer
1998-01-01
SONTRAC is a scintillating fiber neutron detector designed to measure solar flare neutrons from a balloon or spacecraft platform. The instrument is comprised of alternating orthogonal planes of scintillator fibers viewed by photomultiplier tubes and image intensifier/CCD camera optics. It operates by tracking the paths of recoil protons from the double scatter of 20 to 200 MeV neutrons off hydrogen in the plastic scintillator, thereby providing the necessary information to determine the incident neutron direction and energy. SONTRAC is also capable of detecting and measuring high-energy gamma rays
2009-07-01
Reduction of the emission of CO{sub 2} is high on the political agenda in Denmark and internationally. One of the possibilities to reduce CO{sub 2} emission from large point sources is to use carbon capture and storage (CCS). The Danish subsurface has a high potential to store CO{sub 2}, and structures such as the Vedsted structure in northern Jylland could be among the first dozen storage facilities utilised in Europe, and thereby become a key area for detailed research and monitoring for many years to come. The background for CCS and geological possibilities in Denmark are described.
A STUDY OF THE K0(L) STRONG INTERACTIONS IN THE MOMENTUM REGION 60-360 GeV/c
1974-10-01
We propose to design, build and use a tertiary K{sub L}{sup 0} beam produced using the high intensity pion beam being built in the proton area. The main advantage of this beam over previous beam is the low neutron background (K{sub L}/n > 3). We propose to study the large transverse momentum dependence of the particles produced in the strong interactions of a K{sub L}{sup 0} beam, and also the production of leptons, and lepton pairs.
Environmental resources of selected areas of Hawaii: Socioeconomics
1995-03-01
This report has been prepared to make available and archive the background information on socioeconomic resources collected during the preparation of the environmental impact statement (EIS) for Phases 3--4 of the Hawaii Geothermal Project (HGP) as defined by the state of Hawaii in its April 1989 proposal to Congress. The USDOE published a notice withdrawing its Notice of Intent to prepare the HGP EIS. Since the state of Hawaii is no longer pursuing or planning to pursue the HGP, DOE considers the project to be terminated. This document provides background information on socioeconomic resources in Hawaii County, with particular emphasis on the Puna District. Information is being made available for use by others in conducting future socioeconomic impact assessments in this area. this report describes existing socioeconomic resources in the areas studied and does not represent an assessment of environmental impacts. The socioeconomic resources described are primarily those that would be affected by employment and population growth associated with any future large-scale development. These resource categories are population, housing, land use, economic structure, infrastructure and public services, local government revenues and expenditures, and tourism and recreation.
2003-01-01
In a joint project covering the main tributaries of the Elbe river, heavy metal concentrations in recent river sediments of the Saale river were measured. Apart from the most relevant pollutants (Cd, Zn, Pb, Cu, Cr, Ni, Hg, As), further metals and Se were also measured. The results provided information on the volumes, distribution, sources and regional distribution of heavy metal pollution as well as on the development of pollution with time since 1991. Natural (geogenic) metal concentrations are an issue as renaturing plans are being developed. In order to avoid unrealistic sanitation goals, an attempt was made to assess the distribution of the geogenic background values of fine-grained river sediments in part catchment areas of a large river catchment area (here: the Saale river) in order to obtain a standard regional geogenic background value for each element
Background'' soil concentration of polycyclic aromatic hydrocarbons from Burlington, Vermont
1993-03-01
Polycyclic Aromatic Hydrocarbons (PAH's) were identified in soils from waterfront industrial land in Burlington prior to conversion to a park. PAH's ranged from 2,457 to 16,005 ppb. As a result, this area was placed on the Vt. DEC list of active'' hazardous sites. The few studies available regarding background concentrations of PAH's (i.e. ATSDR, 1990), suggested that the waterfront PAH values were low for urban soils. To provide a context for evaluating the waterfront PAH concentrations, a background study of soils in the City of Burlington was conducted. Twelve composite soil samples were collected from within a 1-mile radius of the proposed park; an area that encompasses a large portion of the City. To correlate PAH concentrations with land-uses, three samples were collected from each of four zones: industrial, mixed commercial-residential, residential and recreational. Samples (and one field blank) were analyzed via EPA method 8100. Total PAH's from the study ranged from 105.7 to 122,035 ppb. The minimum value was from a baseball field; the maximum value from a residential lawn. The arithmetic mean for the Burlington study was 19,380 ppb (compared to 10,530 ppb for the waterfront). The background'' values indicate that the waterfront park soils are below the study background'' mean. It is difficult to assess the origin of the elevated PAH values because of the numerous contributors of environmental PAH. One common element that appears to characterize soils with the highest background'' PAH values is linkage to recent or historic building fires. In many instances building combustion may be a dominant local source of soil PAH's.
2010-04-09
TeV photons from blazars at relatively large distances, interacting with the optical-IR cosmic background, are efficiently converted into electron-positron pairs. The produced pairs are extremely relativistic (Lorentz factors of the order of 1e6 1e7 and promptly loose their energy through inverse Compton scatterings with the photons of the microwave cosmic background, producing emission in the GeV band. The spectrum and the flux level of this reprocessed emission is critically dependent on the intensity of the intergalactic magnetic field, B, that can deflect the pairs diluting the intrinsic emission over a large solid angle. We derive a simple relation for the reprocessed spectrum expected from a steady source. We apply this treatment to the blazar 1ES 0229+200, whose intrinsic very hard TeV spectrum is expected to be approximately steady. Comparing the predicted reprocessed emission with the upper limits measured by the Fermi/Large Area Telescope, we constrain the value of the intergalactic magnetic field to be larger than B ~5e-15 Gauss.
The hot dry rock geothermal potential of the Susanville (CA) area
A portion of northeastern California that lies within the Basin and Range Province represents a large, untapped geothermal energy resource in the form of hot, but essential impermeable, rock. If a means of developing sufficient permeability in the deep, granitic basement can be demonstrated, the electric power generation potential would be considerable. The objective of this study is to look at the specific geographical region extending from northeast to southeast of the village of Litchfield to the Nevada border as a target area for the first commercial application of Hot Dry Rock reservoir stimulation techniques. The ultimate goal is to provide background information that could lead to the creation of a commercial-scale, engineered geothermal reservoir in granitic basement rock of low permeability.
The hot dry rock geothermal potential of the Susanville (CA) area
1996-12-31
That portion of northeastern California that lies within the Basin and Range Province represents a large, untapped geothermal energy resource in the form of hot, but essentially impermeable, rock at depth. If a means of developing sufficient permeability in the deep, granitic basement in this corner of California can be demonstrated, the electric power generation potential would be considerable. The objective of this study is to look at the specific geographical region extending from northeast to southeast of the village of Litchfield (13 miles east of Susanville) to the Nevada border as a target area for the first commercial application of Hot Dry Rock (HDR) reservoir stimulation techniques. The ultimate goal is to provide background information that could lead to the creation of a commercial-scale, engineered geothermal reservoir in granitic basement rock of low permeability.
The hot dry rock geothermal potential of the Susanville (CA) area
1996-10-01
A portion of northeastern California that lies within the Basin and Range Province represents a large, untapped geothermal energy resource in the form of hot, but essential impermeable, rock. If a means of developing sufficient permeability in the deep, granitic basement can be demonstrated, the electric power generation potential would be considerable. The objective of this study is to look at the specific geographical region extending from northeast to southeast of the village of Litchfield to the Nevada border as a target area for the first commercial application of Hot Dry Rock reservoir stimulation techniques. The ultimate goal is to provide background information that could lead to the creation of a commercial-scale, engineered geothermal reservoir in granitic basement rock of low permeability.
Sustainable strategies for flood mitigation
2005-03-30
SummaryIntended Outputs: Provision of sustainable strategies for flood preparedness, warning, and emergency response.ObjectivesTo help protect and sustain livelihoods of flood plain populations during flood emergencies.DescriptionProject Background: Millions of people in sub-Saharan Africa live in poverty, which is the greatest impediment to development in the region. These conditions are triggered by recurrent droughts that cause large-scale migration to less vulnerable areas including the floodplains of major rivers. Here they are subject to the consequences of severe, widespread floods that in turn result in high loss of life, livelihoods and possessions. Many of the affected communities flee to urban areas where th [continued...]
Simulation of foot-and-mouth disease spread within an integrated livestock system in Texas, USA
2009-01-01
We used a simulation study to assess the impact of an incursion of foot-and-mouth disease (FMD) virus on the livestock industries in an 8-county area of the Panhandle region of Texas, USA. The study was conducted in a high-density livestock area, with an estimated number of cattle on-feed of approximately 1.8 million. We modified an existing stochastic, spatial simulation model to simulate 64 scenarios for planning and decision-making. Our scenarios simulated four different herd types for the index herd (company feedlot, backgrounder feedlot, large beef, backyard) and variations in three mitigation strategies (time-of-detection, vaccine availability, and surveillance during disease control). Under our assumptions about availability of resources to manage an outbreak, median epidemic length...
Predictors of Breast and Cervical Cancer Screening in a Spanish Metropolitan Area
2010-01-01
Abstract Background: Gynecological cancers are an important cause of morbidity and mortality. Screening with mammography and Pap smear reduces breast and cervical cancer mortality. Neverthless, high participation rates are needed to ensure their effectiveness. We sought to assess the use of mammography and Pap smear and analyzed predictors of attendance at these cancer screenings in a large metropolitan area in Spain. Methods: We included women surveyed in the Madrid City Health Survey 2005. Cancer screening included mammography in the last 2 years and Pap smear in the last 3 years. Independent variables included sociodemographics, chronic diseases, and lifestyles. Predictors of mammography or Pap smear attendance were explored using logistic regression. Results: The number of women eligib...
Full Text Available.BackgroundThe northern fur seal (Callorhinus ursinus; NFS) is a widely distributed pinniped that has been shown to exhibit a high degree of philopatry to islands, breeding areas on an island, and even to specific segments of breeding areas. This level of philopatry could conceivably lead to highly genetically divergent populations. However, northern fur seals have the potential for dispersal across large distances and have experienced repeated rapid population expansions following glacial retreat and the more recent cessation of intensive harvest pressure.Methodology/Principal FindingsUsing microsatellite and mitochondrial loci, we examined population structure in NFS throughout their range. We found only weak population genetic structure among breeding islands including significant F
1986-01-01
For the measurement of low energy X rays emitted by CRT devices at dose rate levels of 1 nSv.h/sup -1/, two different techniques have been used: a phoswich detector inside a steel-shielded room, and a large-area xenon proportional counter for in situ surveys in the workplace. Using a detector-to-screen distance of 5 cm, the area doe rate has been converted into effective dose equivalent. A survey program of 44 VDTs and 65 colour TV sets results in annual dose values of 12 nSv for VDT operators and 3.3 nSv for TVs, which is nearly five orders of magnitude below the exposure due to natural radiation background.
2007-01-01
This paper presents the background information, test results, analysis, and conclusions relating to the testing of two model bridge stringcourses subject to simulated parapet impact loading. Mott MacDonald Area 3 were appointed in 2002 by the Highways Agency to undertake the upgrade and replacement of all substandard BACO parapets fixed to existing structures. Area 3 in Southern England has a particularly large number of parapets that do not meet current design standards for normal containment. In many cases a combination of stringcourse geometry and a low assessment of in situ strength based upon a conservative model of load dispersal precluded the simple substitution and replacement of the parapet. Design of the test programme was based upon the composite characteristics of the five weak...
Heavy metal contamination in the vicinity of an industrial area near Bucharest
2009-01-01
Background, aim, and scope Heavy metals such as lead are well known to cause harmful health effects. Especially children are particularly susceptible to increased levels of lead in their blood. It is also a fact that lead concentration is increasing in the environment due to increased anthropogenic activity. The risk of heavy metal contamination is pronounced in the environment adjacent to large industrial complexes. In a combined case study, the environmental pollution by heavy metals was related to childrens health in the vicinity of an industrial area located 4km south-east from Bucharest about 2km east from the nearest townPantelimon. This site includes companies processing different, nonferrous solid wastes for recovery of heavy metals and producing different nonferrous allo...
Atmospheric heavy metal deposition in Europe estimated by moss analysis
1995-12-31
Atmospheric heavy metal deposition in Europe including 21 countries was monitored in 1990-1992 by the moss technique. This technique is based on the fact that the concentrations of heavy metals in moss are closely correlated to atmospheric deposition. This was the first attempt to map heavy metal deposition in this large area. The objectives of the project were to characterise qualitatively and quantitatively the regional atmospheric deposition pattern of heavy metals in background areas in Europe, to indicate the location of important heavy metal pollution sources and to allow retrospective comparisons with similar studies. The present survey is a follow-up of a joint Danish and Swedish project in 1980 and an extended survey in 1985 within the framework of the Nordic Council of Ministers. In Sweden, heavy-metal deposition was first mapped on a nation-wide scale in 1968-1971 and 1975. (author)
2002-01-28
The detection of low intensity sources of radiation in containers is of particular interest for arms control, non-proliferation and nuclear smuggling activities. Attempts to procure and smuggle nuclear materials that could be used in terrorist activities have been well documented in recent years. These incidents have included fissile materials such, as plutonium and uranium, as well as medical and industrial isotopes that could be used in a Radiation Dispersal Device. The vast majority of these incidents have been discovered through human intelligence work due to the difficulty of using radiation monitoring. The detection of radiation sources in well-shielded containers presents a difficult technological challenge. Few neutrons and gamma rays may escape from the container and these may be obscured by the naturally occurring background. The world in general is a radioactive environment. Many elements in the earth's crust, as well as in common plants and building materials, emit a constant stream of radiation. In fact the ultimate limit on the detection of hidden sources is often the background level at the location of interest. It has long been understood that knowledge of the directionality of this background can be used to improve the signal/noise ratio in detectors used for these measurements. Imaging detectors are one method of reducing the effect of the background, but this reduction comes at the expensive of a huge increase in detector complexity. Hence these systems, while important in some specific applications, are probably not suited for the deployment of many detectors over a large area. There may be another way of reducing the effect of backgrounds on monitoring measurements. This method consists of using knowledge of the directional dependence of the background flux to help reduce its effect on the detectors in question. An accurate knowledge of this angular distribution allows one to develop better shielding designs for the detectors.
2007-09-15
Coal exploitation inevitably damages the natural ecological environment through large scale underground exploitation which exhausts the surrounding areas and is the cause of surface subsidence and cracks. These types of damage seriously lower the underground water table. Deterioration of the environment has certainly an impact on and limits growth of vegetation, which is a very important indicator of a healthy ecological system. Dynamically monitoring vegetation growth under coal exploitation stress by remote sensing technology provides advantages such as large scale coverage, high accuracy and abundant information. A scatter plot was built by a TM (Thematic Mapper) infrared and red bands. A detailed analysis of the distributional characteristics of vegetation pixels has been carried out. Results show that vegetation pixels are affected by soil background pixels, while the distribution of soil pixels presents a linear pattern. Soil line equations were obtained mainly by linear regression. A new band, reflecting vegetation growth, has been obtained based on the elimination of the soil background. A grading of vegetation images was extracted by means of a density slice method. Our analysis indicates that before the exploitation of the Bulianta coal mining area, vegetation growth had gradually reduced; especially intermediate growth vegetation had been transformed into low vegetation. It may have been caused by the deterioration of the brittle environment in the western part of the mining area. All the same, after the start of coal production, vegetation growth has gradually improved, probably due to large scale aerial seeding. Remote sensing interpretation results proved to be consistent with the actual situation on the ground. From our research results we can not conclude that coal exploitation stress has no impact on the growth of vegetation. More detailed research on vegetation growth needs to be analyzed. 19 refs., 3 figs.
Wilderness event medicine: planning for mass gatherings in remote areas
2005-01-01
SummaryBackgroundAn increasing number of large recreational events are taking place in remote environments where medical care is far away. Such events include adventure races and large outdoor trips. Wilderness event medicine (WEM) has been previously defined as the healthcare response at any discrete event with more than 200 persons located more than 1h from hospital treatment. However, there is little literature describing the steps for providing medical care at such events.MethodsThis article provides a framework for planning and executing WEM. It reviews the published data on wilderness injury and illness rates and describes the nature of injuries as they relate to specific activities. The article then discusses the three stages of WEM: pre-event planning, medical treatment at the even...
2010-01-01
Abstract Large populations, seemingly not at risk of extinction, can decline rapidly due to alteration of habitat. This appears to be the case of the butterfly Chazara briseis, which is declining in all of Central and Eastern Europe, even from apparently large areas of its steppe grassland habitats. We combined mark-recapture, allozyme electrophoresis and adult behaviour observation to study the last remaining metapopulation of this once-widespread butterfly in the Czech Republic. The total population estimate was 1300 males and 1050 females in 10 colonies within a 70 km2 landscape. Adults were long-lived, and inseminated females required several weeks before they started ovipositing. Models using realistic lengths of the preoviposition period estimated that due to background mortality, on...
2010-01-01
The Landscape Reconstruction Algorithm (LRA) overcomes some of the fundamental problems in pollen analysis for quantitative reconstruction of vegetation. LRA first uses the REVEALS model to estimate regional vegetation using pollen data from large sites and then the LOVE model to estimate vegetation composition within the relevant source area of pollen (RSAP) at small sites by subtracting the background pollen estimated from the regional vegetation composition. This study tests LRA using training data from forest hollows in northern Michigan (35 sites) and northwestern Wisconsin (43 sites). In northern Michigan, surface pollen from 152-ha and 332-ha lakes is used for REVEALS. Because of the lack of pollen data from large lakes in northwestern Wisconsin, we use pollen from 21 hollows random...
Full Text Available.BackgroundAcute necrotising fasciitis is a life-threatening condition, which requires urgent surgical intervention. Surgical debridement is invariably associated with large areas of tissue loss.Case presentationWe present a 58-year old woman with a past history of cervical carcinoma who presented with necrotising fasciitis of the perineum and upper thighs with associated pubic bone osteomyelitis. Following extensive debridement, a Vacuum Assisted Closure (VAC) system was applied to the large residual defect to facilitate skin graft application and optimise wound healing.ConclusionThis case demonstrates the successful management of a complex and potentially lethal wound of the perineum with debridement, skin grafting and the VAC system.
Relativistic cosmology and large-scale structure
2007-05-31
General relativity marked the beginning of modern cosmology and it has been at the centre of many of the key developments in this field. In the present review, we discuss the general-relativistic dynamics and perturbations of the standard cosmological model, the Friedmann-Lemaitre universe, and how these can explain and predict the properties of the observable universe. Our aim is to provide an overview of the progress made in several major research areas, such as linear and non-linear cosmological perturbations, large-scale structure formation and the physics of the cosmic microwave background radiation, in view of current and upcoming observations. We do this by using a single formalism throughout the review, the 1+3 covariant approach to cosmology, which allows for a uniform and balanced presentation of technical information and physical insight.
Overview of particulate exposures in the US trucking industry
2006-01-01
As part of a large epidemiologic study of lung cancer, 55 000 subjects, we have conducted a nation-wide survey of particulate exposures in the US trucking industry. The goal is to differentiate the risks from various types of particulate exposures, such as traffic emissions and general air pollution. We hypothesize that exposures defined by job and work site characteristics can be linked with subjects using their personal job histories. This report covers exposures at 36 randomly chosen large truck freight terminals in the US. Measurements were made of PM2.5, elemental carbon (EC), and organic carbon (OC) upwind of the terminal (background) and in work areas, and by personal samples. Significant differences in exposure intensity, mg m-3, were found for work locations and jobs relative to b...
Optical sensor with large area photomultiplier for DUMAND project
1979-01-01
The possibility of using large photocathode direct-view detectors as optical sensors for DUMAND is examined in light of the present unavailability of light-trapping detectors. The proposed sensor consists of two hemispherical high-sensitivity photomultipliers contained within an envelope capable of withstanding pressures at a depth of 5 km. An expression for the average number of photoelectrons detected as a function of distance from a muon track of minimum ionization is presented for various instrument quantum efficiencies and light attenuation coefficients. An event threshold of three photoelectrons for a billion-ton installation is then determined from considerations of the background of photon flux from K-40 decay, and this value is used to obtain an estimated requirement for 16,250 detector modules spaced 38.4 m apart
2007-04-17
A large fraction of the anticipated source detections by the Gamma-ray Large Area Space Telescope (GLAST-LAT) will initially be unidentified. We argue that traditional approaches to identify individuals and/or populations of gamma ray sources will encounter procedural limitations. Those limitations are discussed on the background of source identifications from EGRET observations. Generally, our ability to classify (faint) source populations in the anticipated GLAST dataset with the required degree of statistical confidence will be hampered by sheer source wealth. A new paradigm for achieving the classification of gamma ray source populations is discussed.
Dynamic resource planning applied to distribution transformers
1997-12-31
The large number of currently installed distribution transformers in Iberdrola - nearly 90,000 units - and the wide range of output rates, primary voltages, secondary voltages, types of dielectric, class of cover-passes, etc. into which these transformers can be subdivided, has to date made it very difficult to optimise the number of standby transformers and procurement of new units. This situation is further complicated by the large land area covered by the distribution grid - 28 provinces in Spain and nearly 50 stores. With this background a System to Aid Decision Making in the Assignment of Transformers (the SADMAT) has been drawn up which will help in the procurement of transformers from outside sources. The purpose of the proposed system is to re-size the stock of standby transformers and transformers in free availability stock, in such a way as to satisfy coverage requirements to existing transformers and the demand requirements of new transformers. (author)
Development of regional characterization factors for aquatic eutrophication
2010-01-01
Background, aim, and scope Life cycle assessment (LCA) has traditionally been considered a site-independent tool, but nowadays, there is a trend towards making LCA more site-dependent. Site-dependent characterization factors have been calculated for regional impact categories such as acidification, terrestrial and aquatic eutrophication, and smog. Specifically, for aquatic eutrophication, characterization factors have been proposed for large geographical areas (mainly European and North American countries). Those factors are not detailed enough for countries which present large geographical, climatic, and economical variability such as Spain. Therefore, this work aims to calculate the characterization factors and the normalization reference for aquatic eutrophication at a regional level, u...
Comprehensive applications of the gas flow proportional counters for radiological surveillance
2008-01-01
Gas Flow Proportional Counters (GFPC) have been developed indigenously for various radiation protection applications. These detectors can be fabricated for 2 inches diameter filter paper sample counting applications to large area (approx1500 cm2) detectors for surface contamination applications. Thin entrance windows allow non penetrating type of radiations like alpha and low energy beta particles, Efficiencies (for alpha and beta radiations) are comparable to conventional detectors used to measure these radiations. Poor gamma efficiency (approx30% beta efficiency provides a large beta2/gamma ratio, a high figure of merit and enables efficient gamma background rejection. These detectors are quite suitable for Indian environmental conditions. Three systems have ...
The Empire Knight: Patterns of mercury contamination in sediment and biota at a marine site
1995-12-31
The Empire Knight, a merchant ship carrying approximately 7.3 metric tons of elemental mercury in its cargo, sank in a storm off the Maine coast in 1 944. Unique attributes of the site include the deep water marine conditions (80 m) and mercury originally in elemental form. Recent evaluations of the site were undertaken to determine environmental risk of the remaining mercury and possible remedial actions. Data collected in 1993 for this risk evaluation included sediment core samples, and a variety of biota samples. Biota were analyzed for total and methylmercury, and the following patterns examined: percent methylmercury, variability between species groups, and spatial patterns related to sediment contamination. Sediment contamination was largely confined to the immediate area near the wreck, with levels decreasing to background within 60 m. Invertebrates within this area had elevated levels of mercury in tissue. Most contamination was in an inorganic form, with percentages of methyl to total mercury below 20%, except for crab and lobster. Most of the residual mercury appears to be largely unavailable to biota, with local invertebrates comprising the main biological receptors. Evidence of bioaccumulation of mercury in higher trophic level organisms was not found, thus mercury did not appear to be a source of contamination beyond the immediate area the wreck.
Safety and benefits of large-volume liposuction: a single center experience
Full Text Available.BackgroundLiposuction is a surgical technique to remove excess fat deposits from specific areas of the body. Purpose of this study is to determine how far large volume liposuction is safe and effective.MethodologyFrom July 2003 to December 2005, 60 female patients had liposuction of different areas of the body as waist, hips, buttocks, thighs, and knees. Their mean age was 30.6 ± 15.4 years old. A standard liposuction technique was done by using a tumescent infiltration formula. The average amount of infusate was 3000 cc, with an average aspirate amount of 6000 cc. Pre-operative anthropometric measurements as weight, height, body mass index, areas to be liposuctioned in addition to pre-operative hematological investigations as complete blood picture, blood sugar, liver function tests, blood urea, serum creatinine, and serum cholesterol were done.ResultsThe results were evaluated with preoperative and postoperative photographs. Postoperative anthropometric measurements and hematological investigations were done at 6
Quantitation of mast cells and collagen fibers in skin tags.
BACKGROUND: Skin tags are common benign skin tumors usually occurring on the neck and major flexors of elder people. AIMS: The aim of this study is to perform quantitation of mast cells and collagen fibers in skin tags and normal skin in diabetics and nondiabetics, to find a possible correlation between mast cells and collagen fibers in the pathogenesis of skin tags. METHODS: Thirty participants with skin tags were divided into two groups (15 diabetic and 15 nondiabetic). Three biopsies were obtained from one anatomical site: A large skin tag, a small skin tag, and adjacent normal skin. Mast cells stained with Bismarck brown were counted manually in ten different fields of each section with magnification x1000 and the average count was correlated with the percentage of mean collagen area in five fields done by the image analyzer. RESULTS: A statistically significant correlation between mast cell count and percentage of collagen mean area was detected in both studied groups (except in large skin tags of the nondiabetic group). CONCLUSION: The positive correlation between mast cell count and percentage of collagen mean area suggests the critical role of mast cells in the etiogenesis of skin tags through its interaction with fibroblasts.
Figaro: an experiment for pulsar and variable source studies in the MeV range
1983-01-01
The paper presents a large area, balloon borne, NaI(Tl) detector for low-energy gamma rays with temporal signature: Figaro. The main detector is a mosaic of 12 NaI(Tl) tiles 22.5 x 15 x 5 cm, for a total geometric area of 4050 sq cm. In the energy band 140 keV-6 MeV, the expected background counting rate at float altitude is in the range of two to three thousand counts per second. For pulsar analysis the expected 3sigma sensitivity for 5 hours exposition time is 2.5 10 to the -4th ph/sq cm.s.MeV (150-500 keV) 1.5 10 to the -4th ph/sq cm.s.MeV (1-6 MeV). This performance, together with the large effective area and the relatively short duration of a balloon flight, make Figaro particularly suitable for the identification of sources by means of temporal analysis. For objectives in the Northern sky, including the Crab pulsar, a transmediterranean flight is planned for the summer of 1982 a ...
Condyloma acuminata in child end laser therapy: a case report
Full Text Available.BackgroundCondyloma acuminata are soft, skin colored, fleshy warts that are caused by the Human Papilloma Virus (HPV). The disease is highly contagious, can appear singly or in groups, small or large. The incubation period may be from 1–6 months. Although anogenital warts are considered to be sexually transmitted in adults, this may not be the case for children. Genital warts in children may result from several modes of transmission: from the maternal genital tract autoinoculation, from finger warts and nonsexual transmission from members/careers.Case presentationThe presented case is a 13-month-old girl. She was hospitalized at the Clinic of Dermatovenerology in 2001 due to papillomatosis changes on the genital area. The changes had started to appear in the sixth month of life, light purple in color, smooth and combined in a tumorous mass, in the vulva and anal areas.ConclusionFrom this case we can come to the conclusion that condyloma acuminate are not only transmitted sexually but through nonsexual ways as well, such is this case, from the infected mother to the infant. Laser therapy is preferred when multiple warts are spread over a large area as though in our case.
Design Issues in Small-Area Studies of Environment and Health
2008-08-01
Full Text Available.BackgroundSmall-area studies are part of the tradition of spatial epidemiology, which is concerned with the analysis of geographic patterns of disease with respect to environmental, demographic, socioeconomic, and other factors. We focus on etiologic research, where the aim is to make inferences about spatially varying environmental factors influencing the risk of disease.Methods and resultsWe illustrate the approach through three exemplars: a) magnetic fields from overhead electric power lines and the occurrence of childhood leukemia, which illustrates the use of geographic information systems to focus on areas with high exposure prevalence; b) drinking-water disinfection by-products and reproductive outcomes, taking advantage of large between- to within-area variability in exposures from the water supply; and c) chronic exposure to air pollutants and cardiorespiratory health, where issues of socioeconomic confounding are particularly important.DiscussionThe small-area epidemiologic approach assigns exposure estimates to individuals based on location of residence or other geographic variables such as workplace or school. In this way, large populations can be studied, increasing the ability to investigate rare exposures or rare diseases. The approach is most effective when there is well-defined exposure variation across geographic units, limited within-area variation, and good control for potential confounding across areas.ConclusionsIn conjunction with traditional individual-based approaches, small-area studies offer a valuable addition to the armamentarium of the environmental epidemiologist. Modeling of exposure patterns coupled with collection of individual-level data on subsamples of the population should lead to improved risk estimates (i.e., less potential for bias) and help strengthen etiologic inference.
Resistive plate chambers in high energy experiments
The resistive plate chamber (hereafter referred to as RPC) has been first developed by R. Santonico and his groups since the late seventies. They have been employed in several experiments at nuclear reactors, fixed target accelerators, colliders, as well as in cosmic rays. In order to properly perform their functions, RPC's have to undergo a series of restricting working conditions, mostly connected to the severe radiation background environment in which they are designed to work. The RPC is a very successful wireless detector which is able to ensure both a high efficiency and a fast response. The absence of wire technologies and the cheap material employed makes the cost production very low so that it can be used to build very large area detectors. A large RPC can have a sensitive area as large as 2 m * 2.5 m. In addition it can be operated in a low gas gain regime, providing a high rate capability. Finally it can provide time of flight measurements as well as position measurements.
Large water management projects and Schistosomiasis control, Dongting Lake region, China
2007-01-01
Construction of the Three Gorges Dam across the Yangtze River will substantially change the ecology of the Dongting Lake in southern China. In addition, the Chinese Central and Hunan Provinces' governmental authorities have instigated a Return Land to Lake Program that will extend the Dongting Lake surface area from the current 2,681 km(2) to 4,350 km(2) The previous construction of embankments and the large silt deposits made by the Yangtze River and other connecting rivers have contributed to frequent disastrous flooding. As a consequence of the 2 water projects, >2 million persons and their domestic animals are being resettled. This article provides an overview of the historical background of these 2 large water management projects, the associated population movement, and their impact on future transmission and control of schistosomiasis in the Dongting Lake area. The dam will likely substantially extend the range of the snail habitats and increase schistosome transmission and schistosomiasis cases. Publisher: National Center for Infectious Diseases Contributor: Korach, K. S.; Drotman, D. P. Coverage: 2007-07-01T00:00:00Z
Tenorm material with high content of radium isotopes in the environment
2006-07-01
Full text: In the oil and natural gas industry a large amount of water is extracted together with the useful material. This water should contain significant concentration of natural radioactive elements (usually radium isotopes with corresponding daughters). If the extraction water reaches the surface environment there is the possibility to appear contaminated areas with natural radioactive elements. In 1994, due to a malfunction at a gas -water separation facility, a large amount of extraction water had been discharged on an agricultural land increasing the natural background. There were a significant increase of {sup 226}Ra and {sup 224}Ra (and corresponding daughters) concentration (up to several thousands of Bq kg-1) in the first centimeters of soil. This paper try to present the results of the measurements performed in 1994 and 2002 -2003. Dosimetric maps of the contaminated area and in-depth concentration profiles are presented. The two data sets show a decrease of the radioactivity (both the dose in air and radioactive element concentration) with about one order of magnitude. Concentration profiles taken in 6 sampling point down to 1.5 m show a strong influence of water in the downward migration a contaminant. Two profiles from sampling point placed in agricultural area present lower migration in comparison with the other four profiles from points situated in the bed of an abandoned irrigation channel. From the experimental data results an insignificant role of resuspension in the dispersion of contamination, a clean (at the level of natural background) area have been found at a distance of some tens of meters from the main contaminated area. Equilibrium calculations have been made between the {sup 224}Ra daughters {sup 228}Ac/{sup 212}Pb, {sup 228}Ac/{sup 208}Tl to assess the age of the contamination. The results are in good agreement (an overestimation of about 1 year) with the assumed contamination time. The equilibrium values obtained from the 1994 data suggest an older, unreported contamination situated in about 1986. Finally possible countermeasures are presented. (authors)
Background counting rate in tritium channel of a large volume liquid scintillation counter increased with water content ranged 0 to 50% of liquid scintillator. This phenomenon can be explained as follows: The height of scintillation pulses of Compton electrons induced by background gamma radiation is lowered by chemical quenching and shifts to tritium channel. The background counting rate in tritium channel showed a linear relationship with external standard channel ratio of background samples. This relationship is applicable to determine the correct background counting rate for quenching samples and to achieve higher precision of tritium measurement.
1984-07-01
Background counting rate in tritium channel of a large volume liquid scintillation counter increased with water content ranged 0 to 50% of liquid scintillator. This phenomenon can be explained as follows: The height of scintillation pulses of Compton electrons induced by background gamma radiation is lowered by chemical quenching and shifts to tritium channel. The background counting rate in tritium channel showed a linear relationship with external standard channel ratio of background samples. This relationship is applicable to determine the correct background counting rate for quenching samples and to achieve higher precision of tritium measurement.
Background issues for defensive interceptors
1991-03-01
Mean nuclear backgrounds are large, but are arguably amenable to frame-to-frame subtraction. Striated backgrounds on the sensors for defensive interceptors could, however, cause clutter leak-through, which could make detection and track difficult. Nominal motions and backgrounds give signal to clutter ratios too low to be useful. Clutter leakage due to line-of-sight drift can be reduced by stabilizing the line of sight around the background clutter itself. Current interceptors have detector arrays large enough for operation independent of nuclear backgrounds in their fields of view. 6 refs., 2 figs.
ASSESSMENT OF HYDROCARBON SEEPAGE DETECTION METHODS ON THE FORT PECK RESERVATION, NORTHEAST MONTANA
Surface exploration techniques have been employed in separate study areas on the Fort Peck Reservation in northeastern Montana. Anomalies associated with hydrocarbon seepage are documented in all three areas and a variety of surface exploration techniques can be compared. In a small area with established production, Head Gas and Thermal Desorption methods best match production; other methods also map depletion. In a moderate-size area that has prospects defined by 3D seismic data, Head Gas along with Microbial, Iodine, and Eh soil anomalies are all associated with the best hydrocarbon prospect. In a large area that contains many curvilinear patterns observed on Landsat images, that could represent micro-seepage chimneys, results are inconclusive. Reconnaissance mapping using Magnetic Susceptibility has identified a potential prospect; subsequent Soil Gas and Head Gas surveys suggest hydrocarbon potential. In the final year of this project the principle contractor, the Fort Peck Tribes, completed a second survey in the Wicape 3D Seismic Prospect Area (also known as Area 6 in Phase I of the project) and sampled several Landsat image features contained in the Smoke Creek Aeromag Anomaly Area (also known as Area 1 in Phase II of the project). Methods determined to be most useful in Phases I and II, were employed in this final Phase III of the study. The Southwest Wicape seismic anomaly was only partially confirmed. The abundant curvilinears proposed to be possible hydrocarbon micro-seepage chimneys in the Smoke Creek Area were not conclusively verified as such. Insufficient sampling of background data precludes affirmative identification of these mostly topographic Landsat features as gas induced soil and vegetation anomalies. However relatively higher light gas concentrations were found associated with some of the curvilinears. Based on the findings of this work the Assiniboine & Sioux Tribes of the Fort Peck Reservation intend to utilize surface hydrocarbon exploration techniques for future identification and confirmation of oil and gas prospects.
ASSESSMENT OF HYDROCARBON SEEPAGE DETECTION METHODS ON THE FORT PECK RESERVATION, NORTHEAST MONTANA
2003-06-30
Surface exploration techniques have been employed in separate study areas on the Fort Peck Reservation in northeastern Montana. Anomalies associated with hydrocarbon seepage are documented in all three areas and a variety of surface exploration techniques can be compared. In a small area with established production, Head Gas and Thermal Desorption methods best match production; other methods also map depletion. In a moderate-size area that has prospects defined by 3D seismic data, Head Gas along with Microbial, Iodine, and Eh soil anomalies are all associated with the best hydrocarbon prospect. In a large area that contains many curvilinear patterns observed on Landsat images, that could represent micro-seepage chimneys, results are inconclusive. Reconnaissance mapping using Magnetic Susceptibility has identified a potential prospect; subsequent Soil Gas and Head Gas surveys suggest hydrocarbon potential. In the final year of this project the principle contractor, the Fort Peck Tribes, completed a second survey in the Wicape 3D Seismic Prospect Area (also known as Area 6 in Phase I of the project) and sampled several Landsat image features contained in the Smoke Creek Aeromag Anomaly Area (also known as Area 1 in Phase II of the project). Methods determined to be most useful in Phases I and II, were employed in this final Phase III of the study. The Southwest Wicape seismic anomaly was only partially confirmed. The abundant curvilinears proposed to be possible hydrocarbon micro-seepage chimneys in the Smoke Creek Area were not conclusively verified as such. Insufficient sampling of background data precludes affirmative identification of these mostly topographic Landsat features as gas induced soil and vegetation anomalies. However relatively higher light gas concentrations were found associated with some of the curvilinears. Based on the findings of this work the Assiniboine & Sioux Tribes of the Fort Peck Reservation intend to utilize surface hydrocarbon exploration techniques for future identification and confirmation of oil and gas prospects.
2009-06-23
Deep multicolour surveys are the main tool to explore the formation and evolution of the faint galaxies which are beyond the spectroscopic limit with the present technology. The photometric properties of these faint galaxies are usually compared with current renditions of semianalytical models to provide constraints on the fundamental physical processes involved in galaxy formation and evolution, namely the mass assembly and the star formation. Galaxy counts over large sky areas in the near-UV band are important because they are difficult to obtain given the low efficiency of near-UV instrumentation, even at 8m class telescopes. A large instrumental field of view helps in minimizing the biases due to the cosmic variance. We have obtained deep images in the 360nm U band provided by the blue channel of the Large Binocular Camera at the prime focus of the Large Binocular Telescope. We have derived over an area of ~0.4 sq. deg. the galaxy number counts down to U=27 in the Vega system (corresponding to U=27.86 in the AB system) at a completeness level of 30% reaching the faintest current limit for this wavelength and sky area. The shape of the galaxy counts in the U band can be described by a double power-law, the bright side being consistent with the shape of shallower surveys of comparable or greater areas. The slope bends over significantly at U>23.5 ensuring the convergence of the contribution by star forming galaxies to the EBL in the near-UV band to a value which is more than 70% of the most recent upper limits derived for this band. We have jointly compared our near-UV and K band counts collected from the literature with few selected hierarchical CDM models emphasizing critical issues in the physical description of the galaxy formation and evolution.
Down's syndrome and related abnormalities in an area of high background radiation in coastal Kerala
1976-01-01
It is stated that in a coastal area of Kerala, Southern India, the background radiation is between 1500 and 3000 mR/yr, this being due to the presence of Th-containing monazite mineral in the soil. During an epidemiological study of modular lesions of the thyroid in this area an apparently high prevalence of Down's syndrome and other forms of severe mental retardation was observed. A house-to-house survey of relevant abnormalities in this area was made, and also in a comparable control area without high background radiation. The frequency of chromosome aberrations in a sample of the population in the study and control areas was also investigated. The observations support the view that radiation induces genetic anomalies occur with above average frequency in the population living in the area with high background radiation. Only gross abnormalities evident in clinical ...
Blazar Gamma-Rays, Shock Acceleration, and the Extragalactic Background Light
2007-08-01
The observed spectra of blazars, their intrinsic emission, and the underlying populations of radiating particles are intimately related. The use of these sources as probes of the extragalactic infrared background, a prospect propelled by recent advances in TeV-band telescopes, soon to be augmented by observations by NASA's upcoming Gamma-Ray Large Area Space Telescope (GLAST), has been a topic of great recent interest. Here, it is demonstrated that if particles in blazar jets are accelerated at relativistic shocks, then gamma-ray spectra with indices less than 1.5 can be produced. This, in turn, loosens the upper limits on the near infrared extragalactic background radiation previously proposed. We also show evidence hinting that TeV blazars with flatter spectra have higher intrinsic TeV gamma-ray luminosities and we indicate that there may be a correlation of flatness and luminosity with redshift.
Anisotropies in the Diffuse Gamma-Ray Background from Dark Matter with Fermi LAT: a closer look
2010-05-07
We perform a detailed study of the sensitivity to the anisotropies related to Dark Matter (DM) annihilation in the Isotropic Gamma-Ray Background (IGRB) as measured by the Fermi Large Area Telescope (Fermi-LAT). For the first time, we take into account the effects of the Galactic foregrounds and use a realistic representation of the Fermi-LAT. We consider DM anisotropies of extra-galactic origin and of Galactic origin (which can be generated through annihilation in the Milky Way sub-structures) as opposed to a background of anisotropies generated by sources of astrophysical origin, blazars for example. We find that with statistics from 5 years of observation Fermi is sensitive to a DM contribution at the level of the thermal-relic cross section depending on the DM mass and annihilation mode. The anisotropy method for DM searches has a sensitivity comparable to the usual methods based only on the energy spectrum and thus constitutes an independent and complementary piece of information in the DM puzzle. (abridged)
1985-01-01
In order to find out what caused the differences in incidences of Down's syndrome between the children in high background radiation area and those in control area, investigation and analysis were carried ou in 5 aspects based on the original data and the information from the previous survey. These are: the incidences of congenital malformations in normal areas, the age distribution of children examined, the maternal age, the dates of birth of afflicted children, and the radiation exposure of mothers. The results suggested that the higher incidence of Down's syndrome in high background area might be related to the materal age. Further studies are needed to arrive at a conclusion
2008-01-01
In this paper, the uncertainties of gamma-ray small peak analysis have been examined. As the intensity of a gamma-ray peak approaches its detection decision limit, derived parameters such as centroid channel energy, peak area, peak area uncertainty, baseline determination, and peak significance are statistically sensitive. The intercomparison exercise organized by the CTBTO provided an excellent opportunity for this to be studied. Near background levels, the false-positive and false-negative peak identification frequencies in artificial test spectra have been compared to statistically predictable limiting values. In addition, naturally occurring radon progeny were used to compare observed variance against nominal uncertainties. The results infer that the applied fit algorithms do not always represent the best estimator. Understanding the statistically ...
Linking soil fertility and improved cropping strategies to development interventions
2005-06-30
SummaryIntended Outputs: Community-based scheme for provision of micro-credit for farm inputs developed and promoted and the transaction process for the community-based scheme documented.Means of farmers to make decision on resource management and purchase of farm inputs improved.Opportunities for suppliers to provide better advice to farmers on resource management and purchase of farm inputs.More profitable, diversified and sustainable integrated cropping systems adopted. Ac [continued...]ObjectivesImproved techniques for integrated crop management (ICM) developed and promoted for upland rainfed farmlands in South Western Kenya.DescriptionProject Background: The highlands of western Kenya cover an area of 85,000 sq km, which represents 15% of the total land area of Kenya. They accommodate 8-10 million inhabitants, or around 40%-50% of the total population. Communities in the area are among the poorest in all Kenya, and clearly the poorest among those within the medium to high potential areas. The rural poor depend largely on subsistence agriculture for food production. Annual rainfall within the western highlands ranges bet [continued...]
Ecology and management of rice hispa (Dicladispa armigera) in Bangladesh
2005-01-30
SummaryIntended Outputs: Farmers' perceptions of constraints to, and advantages of, different control strategies understood.Economic cost-benefit comparisons of different strategies for hispa control.Options for institutional frameworks for implementing hispa control defined.Population ecology of rice hispa, and the role of natural enemies and host plant condition elucidated.Dispersal patterns, variation in past and present hispa pest status, and limits of endemic rang [continued...]ObjectivesTo develop an understanding of the natural mortality factors affecting the rice hispa in endemic and outbreak areas of rice affected by the pest in Bangladesh, and of the socio-economic factors associated with the pest and its control. To use this information to develop recommendations for extension workers and farmers, to improve the sustainable control of the pest in rice cropping systems.DescriptionProject Background: Rice production is crucial to the Bangladesh economy. Approximately 75% of the cropped area and 83% of the total irrigated area are devoted to rice cultivation, and an estimated 60-70% of the agricultural labour force is employed in rice production, processing, marketing and its distribtion. Rice yields are low, and there is much potential for yield gains. The land area available for rice production is declining, and large gains in productivity will be needed to sustain [continued...]
2007-12-01
An aerial radiological survey was conducted over the 16 square-mile (~41 square-kilometer) area surrounding the Portsmouth Gaseous Diffusion Plant. The survey was performed in August 2007 utilizing a large array of helicopter mounted sodium iodide detectors. The purpose of the survey was to update the previous radiological survey levels of the environment and surrounding areas of the plant. A search for a missing radium-226 source was also performed. Implied exposure rates, man-made activity, and excess bismuth-214 activity, as calculated from the aerial data are presented in the form of isopleth maps superimposed on imagery of the surveyed area. Ground level and implied aerial exposure rates for nine specific locations are compared. Detected radioisotopes and their associated gamma ray exposure rates were consistent with those expected from normal background emitters. At specific plant locations described in the report, man-made activity was consistent with the operational histories of the location. There was no spectral activity that would indicate the presence of the lost source.
2006-01-01
In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31 15 milli Becquerel per m2 per second (mBq m2 s1). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m2 s1 at an area south of the former pit characterised by a disequilibrium between 226Ra and 238U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m2 s1) and waste rock dump (mean 335 mBq m2 s1). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s1, post-mining radon flux amoun...
2010-01-01
ABSTRACT We use the Spitzer Wide-area InfraRed Extragalactic Legacy Survey (SWIRE) to explore the specific star formation activity of galaxies and their evolution near the peak of the cosmic far-infrared (FIR) background at 70 and 160 mm. We use a stacking analysis to determine the mean FIR properties of well-defined subsets of galaxies at flux levels well below the FIR catalogue detection limits of SWIRE and other Spitzer surveys. We tabulate the contribution of different subsets of galaxies to the FIR background at 70 and 160 mm. These long wavelengths provide a good constraint on the bolometric obscured emission. The large area provides good constraints at low z and in finer redshift bins than previous work. At all redshifts we find that the specific FIR luminosity decreases with increa...
2005-01-01
To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a search instrument deployed as a large-area, coded-mask imager. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to ''hide'' the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using imaging coded-mask methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results
To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a search instrument deployed as a large-area, coded-mask imager. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to ''hide'' the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using imaging coded-mask methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results.
2005-11-10
To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a search instrument deployed as a large-area, coded-mask imager. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to ''hide'' the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using imaging coded-mask methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results.
1982-04-01
Noise levels for horizontal axis turbines whose diameter 75 m and electric power output 2 to 3 MW were predicted. Noise criteria in view of Swedish regulations and the effects of wind dependent background noise are considered. Highest sound pressure levels are recorded downwind, due to source directionality. Wind also introduces downward refraction and extra damping due to prolonged propagation path. Unexpectedly large low frequency noise values can exist where blade passage frequency and natural vortex separation frequency are similar. Problems with unpleasant low frequency noise could be overcome by setting sound level maxima of 40 dBA or 55 dBC in urban areas, 35 dBA or 55 dBC in recreation areas, and by lowering these limits by 5 dB for impulse and tonal noise. Rise in background noise level caused by increased wind speed should be accounted for when setting limits.
2007-08-14
With current near-infrared (NIR) instruments the near-infrared light scattered from interstellar clouds can be mapped over large areas. The surface brightness carries information on the line-of-sight dust column density. Therefore, scattered light could provide an important tool to study mass distribution in quiescent interstellar clouds at a high, even sub-arcsecond resolution. We wish to confirm the assumption that light scattering dominates the surface brightness in all NIR bands. Furthermore, we want to show that scattered light can be used for an accurate estimation of dust column densities in clouds with Av in the range 1-15mag. We have obtained NIR images of a quiescent filament in the Corona Australis molecular cloud. The observations provide maps of diffuse surface brightness in J, H, and Ks bands. Using the assumption that signal is caused by scattered light we convert surface brightness data into a map of dust column density. The same observations provide colour excesses for a large number of background stars. These data are used to derive an extinction map of the cloud. The two, largely independent tracers of the cloud structure are compared. Results. In regions below Av=15m both diffuse surface brightness and background stars lead to similar column density estimates. The existing differences can be explained as a result of normal observational errors and bias in the sampling of extinctions provided by the backgroun d stars. There is no indication that thermal dust emission would have a significant contribution even in the Ks band. The results show that, below Av=15mag, scattered light does provide a reliable way to map cloud structure. Compared with the use of background stars it can also in practice provide a significantly higher spatial resolution.
Composition of ALICE machine induced background at nominal beam energy
The understanding of the background to the LHC experiments induced by the machine is important to maximising the performance of the collider. The background environment is complex, with contributions from beam-gas interactions around the ring, the halo collimation system and cross talk from one experiment to another. In this note, the background rates for ALICE beam 1 are calculated for nominal beam energy and 1/3 nominal current, including all of the large sources, and the relative background composition discussed.
Performance of the ATLAS precision muon chambers under LHC operating conditions
For the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC), large drift chambers consisting of 6-8 layers of pressurized drift tubes are used for precision tracking covering an active area of 5000 m**2 in the toroidal field of superconducting air-core magnets. The chambers have to provide a spatial resolution of 41 mum with Ar:CO //2 (93:7) gas mixture at an absolute pressure of 3 bar and gas gain of 2 multiplied by 10**4. The environment in which the chambers will be operated is characterized by high neutron and gamma background with counting rates of up to 100 s**-**1 cm**- **2. The resolution and efficiency of a chamber from the serial production for ATLAS has been investigated in a 100 GeV muon beam at photon irradiation rates as expected during LHC operation. A silicon strip detector telescope was used as external reference in the beam. The spatial resolution of a chamber is degraded by 4 mum at the highest background rate. The detection efficiency of the drift tubes is unchanged under irradiation. A tracking efficiency of 98% at the highest rates has been demonstrated. copy 2003 published by Elsivier B.V. 4 Refs.
Life expectancy survey of the inhabitants in high background radiation areas in China
1980-04-01
The results of the investigations on the life expectancy of the inhabitants living in the high background radiation area for many generations are presented. The demographic data from both the high background area and the control area from 1979 to 1980 were obtained by making out registration lists and house-to-house calls. The life expectancy of males and females in both areas were calculated, of which 148,527 person-years were investigated in high background area (males 78,031, females 70,496), and 141,827 person-years in control area (males 72,612, females 69,215), respectively. During this period, 967 deaths (531 males and 436 females) occurred in the high background area, while 920 deaths (478 males and 442 females) in the control area. The inhabitants life expectancy is 66.52 years for males and 69.28 years for females in the high background area and 67.22 years for males and 75.76 years for females in the control area. In both areas life expectancy for females is longer than that for males, which is consistent with ordinary cases. The life expectancy for males and females in the high background area is shorter than that in the control area, whereas that for males over forty years of age in the high background area is longer than that in the control area. In addition, the results of this investigation were analysed, compared with those obtained from previous investigation and discussed.
1979-09-29
The fission product radioactivity detected on lichens in the vicinity of the impact area of the Soviet satellite Cosmos 954 does not exceed the background levels found in the general area as a result of past nuclear explosions.
2004-09-21
HEALPix -- the Hierarchical Equal Area iso-Latitude Pixelization -- is a versatile data structure with an associated library of computational algorithms and visualization software that supports fast scientific applications executable directly on very large volumes of astronomical data and large area surveys in the form of discretized spherical maps. Originally developed to address the data processing and analysis needs of the present generation of cosmic microwave background (CMB) experiments (e.g. BOOMERanG, WMAP), HEALPix can be expanded to meet many of the profound challenges that will arise in confrontation with the observational output of future missions and experiments, including e.g. Planck, Herschel, SAFIR, and the Beyond Einstein CMB polarization probe. In this paper we consider the requirements and constraints to be met in order to implement a sufficient framework for the efficient discretization and fast analysis/synthesis of functions defined on the sphere, and summarise how they are satisfied by HEALPix.
Ethnobotany in the Cumbres de Monterrey National Park, Nuevo León, México
Full Text Available.An ethnobotanical study in the Cumbres de Monterrey National Park (CMNP), Nuevo Leon, Mexico was conducted. In spite of the large area (1,773.7 km2), heterogeneous physiography, contrasting plant communities and high species diversity of the CMNP, very little was previously known about its useful plants. Based on 95 interviews with inhabitants of the region who were 35 years or older, we recorded ethnobotanical data of 240 species (comprising 170 genera and 69 botanical families), and 146 different uses. Most of the cited uses (98) were found to be medicinal ones.BackgroundAn ethnobotanical study in the Cumbres de Monterrey National Park (CMNP), Nuevo Leon, Mexico was conducted. In spite of the large area (1,773.7 km
Development of an array of cooled large area Si(Li) detectors
1985-10-01
A system containing six cooled, 34 mm diam by 7 mm thick, high-resolution Si(Li) detectors designed to maximize the sensitivity for counting x rays in the 10-30 keV range to measure trace radionuclides in soil samples has been successfully fabricated. The detectors were mounted in a paddle-shaped cryostat with a single large beryllium window on each side. This configuration provides for efficient anticoincidence background suppression and effectively doubles the sensitive detector area because x rays can impinge on the detectors from both sides. To maximize detection efficiency, the thickness of the cryostat was held to a bare minimum (25 mm); this caused severe difficulties during fabrication of the system. Cutting down the rim of the detectors reduced to an acceptable level the microphony caused by movement of the beryllium window that faces the lithium-diffused contact of the detectors. Since this system will be used for low level counting. careful testing was performed to select materials having the lowest radioactivity.
Definition of a Twelve-Point Polygonal SAA Boundary for the GLAST Mission
2007-01-01
The Gamma-Ray Large Area Space Telescope (GLAST), set to launch in early 2008, detects gamma rays within a huge energy range of 100 MeV - 300 GeV. Background cosmic radiation interferes with such detection resulting in confusion over distinguishing cosmic from gamma rays encountered. This quandary is resolved by encasing GLAST's Large Area Telescope (LAT) with an Anti-Coincidence Detector (ACD), a device which identifies and vetoes charged particles. The ACD accomplishes this through plastic scintillator tiles. When cosmic rays strike, photons produced induce currents in Photomultiplier Tubes (PMTs) attached to these tiles. However, as GLAST orbits Earth at altitudes approx550km and latitudes between -26 degree and 26 degree, it will confront the South Atlantic Anomaly (SAA), a region of high particle flux caused by trapped radiation in the geomagnetic ...
DESIGN OF A LARGE-AREA FAST NEUTRON DIRECTIONAL DETECTOR.
2006-10-29
A large-area fast-neutron double-scatter directional detector and spectrometer is being constructed using l-meter-long plastic scintillator paddles with photomultiplier tubes at both ends. The scintillators detect fast neutrons by proton recoil and also gamma rays by Compton scattering. The paddles are arranged in two parallel planes so that neutrons can be distinguished from muons and gamma rays by time of flight between the planes. The signal pulses are digitized with a time resolution of one gigasample per second. The location of an event along each paddle can be determined from the relative amplitudes or timing of the signals at the ends. The angle of deflection of a neutron in the first plane can be estimated from the energy deposited by the recoil proton, combined with the scattered neutron time-of-flight energy. Each scattering angle can be back-projected as a cone, and many intersecting cones define the incident neutron direction from a distant point source. Moreover, the total energy of each neutron can be obtained, allowing some regions of a fission source spectrum to be distinguished from background generated by cosmic rays. Monte Carlo calculations will be compared with measurements.
A hard x-ray spectrometer for high angular resolution observations of cosmic sources
LAXRIS (large area x-ray imaging spectrometer) is an experimental, balloon-borne, hard x-ray telescope that consists of a coaligned array of x-ray imaging spectrometer modules capable of obtaining high angular resolution (1--3 arcminutes) with moderate energy resolution in the 20- to 300-keV region. Each spectrometer module consists of a CsI(Na) crystal coupled to a position-sensitive phototube with a crossed-wire, resistive readout. Imaging is provided by a coded aperture mask with a 4-m focal length. The high angular resolution is coupled with rather large area (/approximately/800 cm/sup 2/) to provide good sensitivity. Results are presented on performance and overall design. Sensitivity estimates are derived from a Monte-Carlo code developed to model the LAXRIS response to background encountered at balloon altitudes. We discuss a variety of observations made feasible by high angular resolution. For instance, spatially resolving the nonthermal x-ray emission from clusters of galaxies is suggested as an ideal program for LAXRIS. 15 refs., 5 figs.
A hard x-ray spectrometer for high angular resolution observations of cosmic sources
1988-08-12
LAXRIS (large area x-ray imaging spectrometer) is an experimental, balloon-borne, hard x-ray telescope that consists of a coaligned array of x-ray imaging spectrometer modules capable of obtaining high angular resolution (1--3 arcminutes) with moderate energy resolution in the 20- to 300-keV region. Each spectrometer module consists of a CsI(Na) crystal coupled to a position-sensitive phototube with a crossed-wire, resistive readout. Imaging is provided by a coded aperture mask with a 4-m focal length. The high angular resolution is coupled with rather large area (/approximately/800 cm/sup 2/) to provide good sensitivity. Results are presented on performance and overall design. Sensitivity estimates are derived from a Monte-Carlo code developed to model the LAXRIS response to background encountered at balloon altitudes. We discuss a variety of observations made feasible by high angular resolution. For instance, spatially resolving the nonthermal x-ray emission from clusters of galaxies is suggested as an ideal program for LAXRIS. 15 refs., 5 figs.
A Faraday Rotation Search for Magnetic Fields in Large Scale Structure
Faraday rotation of radio source polarization provides a measure of the integrated magnetic field along the observational lines of sight. We compare a new, large sample of Faraday rotation measures (RMs) of polarized extragalactic sources with galaxy counts in Hercules and Perseus-Pisces, two nearby superclusters. We find that the average of RMs in these two supercluster areas are larger than in control areas in the same galactic latitude range. This is the first RM detection of magnetic fields that pervade a supercluster volume, in which case the fields are at least partially coherent over several megaparsecs. Even the most conservative interpretation of our observations, according to which Milky Way RM variations mimic the background supercluster galaxy overdensities, puts constraints on the IGM magneto-ionic ``strength'' in these two superclusters. We obtain an approximate typical upper limit on the field strength of about 0.3 microGauss l/(500 kpc), when we combine our RM data with fiducial estimates of electron density from the environments of giant radio galaxies, and of the warm-hot intergalactic medium (WHIM).
Phase I Rinal Report: Ultra-Low Background Alpha Activity Counter
2005-07-22
In certain important physics experiments that search for rare-events, such as neutrino or double beta decay detections, it is critical to minimize the number of background events that arise from alpha particle emitted by the natural radioactivity in the materials used to construct the experiment. Similarly, the natural radioactivity in materials used to connect and package silicon microcircuits must also be minimized in order to eliminate ''soft errors'' caused by alpha particles depositing charges within the microcircuits and thereby changing their logic states. For these, and related reasons in the areas of environmental cleanup and nuclear materials tracking, there is a need that is important from commercial, scientific, and national security perspectives to develop an ultra-low background alpha counter that would be capable of measuring materials' alpha particle emissivity at rates well below 0.00001 alpha/cm{sup 2}/hour. This rate, which corresponds to 24 alpha particles per square meter per day, is essentially impossible to achieve with existing commercial instruments because the natural radioactivity of the materials used to construct even the best of these counters produces background rates at the 0.005 alpha/cm{sup 2}/hr level. Our company (XIA) had previously developed an instrument that uses electronic background suppression to operate at the 0.0005 0.005 alpha/cm{sup 2}/hr level. This patented technology sets up an electric field between a large planar sample and a large planar anode, and fills the gap with pure Nitrogen. An alpha particle entering the chamber ionizes the Nitrogen, producing a ''track'' of electrons, which drift to the anode in the electric field. Tracks close to the anode take less than 10 microseconds (us) to be collected, giving a preamplifier signal with a 10 us risetime. Tracks from the sample have to drift across the full anode-sample gap and produce a 35 us risetime signal. By analyzing the preamplifier signals with a digital signal processor we easily distinguish between these two risetimes and thereby count only alpha particles emitted by the sample. Alpha particles emitted from the sample tray are absorbed in the rear of the sample, so the tray's emissivity does not contribute to the background either. Extensions of the method to the counter's sidewalls similarly allow us to reject alpha particles emitted from the sidewalls. We can thus able obtain background rates over a factor of 1000 lower than in conventional instruments without active background rejection. Extending this principle to count at the 0.00001 alpha/cm{sup 2}/hour, level encounters difficulties because there will typically be only 2.4 alpha particles per square meter per day. Since about 6 counts are required to measure activity at the 95% confidence level, large sample areas are required to make measurements in reasonable times. Unfortunately, increasing the counter's anode area to a square meter raises its capacitance so much that the preamplifier noise levels swamp the alpha particle signals and make counting impossible. In this SBIR we worked to solve this dilemma by segmenting the single large area electrode into several smaller, lower capacitance electrodes that could still detect the alpha particles reliably. Each electrode would have its own electronic and we would capture signals from all of them in coincidence (since an alpha track might well deposit charge on more than one electrode), a technique in which XIA is experienced. Therefore, in Phase I we worked to show proof of principle by subdividing our original 1,800 cm{sup 2} electrode into 4 square segments, each 625 cm{sup 2} and demonstrating that signal noise on individual channels reduced as expected. Because the Phase II counter with a 1 m{sup 2} segmented anode would require 16 segments plus a segmented guard as well, we also designed low cost signal processing electronics to instrument it in Phase II. Our Phase I effort met our major proof of principle goals. In particular, reducing the anode size by a factor of 4 in area reduced electronic noise by 3. We also developed an analytical model of signal generation as the charges in the track drift across the counter and showed that the features observed in the real signals closely resembled those predicted by the model. When we captured events where the track charge was indeed collected by two electrodes, we showed that, by summing them, we could recover the preamplifier signal shape appropriate to collection by a single electrode. We thereby showed that we could achieve noise levels that would allow us to analyze our signals with even higher precision than in our current instrument while being able to increase the measured sample area to the values needed to attain the proposed 0.00001 alpha/cm{sup 2}/hour sensitivity.
Oil spill remote sensors: Review, trends and new developments
1997-06-01
Remote-sensors for application to oil spills are assessed, and new developments and trends highlighted. The most common sensor used at this time, is an infrared camera or an IR/UV system. This sensor class can detect oil under a variety of conditions, discriminate oil from some backgrounds and has the lowest cost of any sensor. The inherent weaknesses include the inability to discriminate oil on beaches, among weeds or debris and under certain lighting conditions, oil is not detected. Furthermore, water-in-oil emulsions are sometimes not detected in the infrared. New technology has made IR technology very cheap and practical, so despite its limitations, it will be a very important tool in the future. The laser fluorosensor is an instrument of the future because of its unique capability to identify oil on backgrounds that include water, soil, ice and snow. It is the only sensor that can positively discriminate oil on most backgrounds. Radar offers the only potential for large area searches and foul weather remote sensing. Radar is costly, requires a dedicated aircraft, and is prone to many interferences. False targets can be as high as 95%. Equipment operating in the visible spectrum, such as cameras and scanners, is useful for documentation or providing a basis for the overlay of other data. It is not useful beyond this because oil shows no spectral characteristics in the visible region. Less use will be made of visible equipment in future years. The use of satellite imagery is reviewed. Optical sensors offer only marginal capability to the oil spill worker. Radar satellite imagery may provide useful overviews on known spills and very large spills. One important new trend will be the use of radar satellite for wide-area searching.
On the large-scale cosmic microwave background polarization
2010-01-01
ABSTRACT We discuss the large-scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our Universe. Assuming an eccentricity at decoupling of about Formula Not Shown , we find an average large-scale polarization Formula Not Shown . We suggest that the forthcoming polarization data at large scales from Planck will be able to discriminate between our proposal and the generally accepted re-ionization scenario.
The potential for reducing urban air temperatures and energy consumption through vegetative cooling
A network of 23 weather stations was used to detect existing oases in Southern California. Four stations, separated from one another by 15--25 miles (24--40 km), were closely examined. Data were strongly affected by the distance of the stations from the Pacific Ocean. This and other city-scale effects made the network inadequate for detection of urban oases. We also conducted traverse measurements of temperature and humidity in the Whittier Narrows Recreation Area in Los Angeles County on September 8--10, 1993. Near-surface air temperatures over vegetated areas were 1--2{degrees}C lower than background air temperatures. We estimate that vegetation may lower urban temperatures by 1{degrees}C, while the establishment of vegetative canopies may lower local temperatures by an additional 2{degrees}C. An increase in vegetation in residential neighborhoods may reduce peak loads in the Los Angeles area by 0.3 GW, and reduce energy consumption by 0.2 BkWh/year, saving $20 million annually. Large additional savings would result from regional cooling.
The potential for reducing urban air temperatures and energy consumption through vegetative cooling
A network of 23 weather stations was used to detect existing oases in Southern California. Four stations, separated from one another by 15--25 miles (24--40 km), were closely examined. Data were strongly affected by the distance of the stations from the Pacific Ocean. This and other city-scale effects made the network inadequate for detection of urban oases. We also conducted traverse measurements of temperature and humidity in the Whittier Narrows Recreation Area in Los Angeles County on September 8--10, 1993. Near-surface air temperatures over vegetated areas were 1--2{degrees}C lower than background air temperatures. We estimate that vegetation may lower urban temperatures by 1{degrees}C, while the establishment of vegetative canopies may lower local temperatures by an additional 2{degrees}C. An increase in vegetation in residential neighborhoods may reduce peak loads in the Los Angeles area by 0.3 GW, and reduce energy consumption by 0.2 BkWh/year, saving $20 million annually. Large additional savings would result from regional cooling.
The potential for reducing urban air temperatures and energy consumption through vegetative cooling
1994-05-01
A network of 23 weather stations was used to detect existing oases in Southern California. Four stations, separated from one another by 15--25 miles (24--40 km), were closely examined. Data were strongly affected by the distance of the stations from the Pacific Ocean. This and other city-scale effects made the network inadequate for detection of urban oases. We also conducted traverse measurements of temperature and humidity in the Whittier Narrows Recreation Area in Los Angeles County on September 8--10, 1993. Near-surface air temperatures over vegetated areas were 1--2{degrees}C lower than background air temperatures. We estimate that vegetation may lower urban temperatures by 1{degrees}C, while the establishment of vegetative canopies may lower local temperatures by an additional 2{degrees}C. An increase in vegetation in residential neighborhoods may reduce peak loads in the Los Angeles area by 0.3 GW, and reduce energy consumption by 0.2 BkWh/year, saving $20 million annually. Large additional savings would result from regional cooling.
Promotion of rainfed rabi cropping in rice fallows of eastern India and Nepal: Phase 2
2006-02-28
SummaryIntended Outputs: Technical and social solutions to overcome constraints to rainfed rabi cropping in rice fallows tested, demonstrated and promoted.Income of participating farmers sustainably increased following adoption of rainfed rabi cropping.Awareness of the opportunities for successful rainfed rabi cropping increased. Actual Outputs: NepalFORWARD arranged and/or implemented 841 participatory trials in rice fallow areas of the Nepalese districts of Jhapa, Morang, Sap [continued...]ObjectivesMethods to optimise cropping systems by agronomic means developed and tested.DescriptionProject Background: There are very large areas of rice fallows (land left fallow after harvest of rainfed rice) in S. Asia. The location and extent of, and gross environmental conditions in, these areas have been quantified, using publicly available databases and a GIS approach. These lands constitute an enormous under-utilised resource for poor farmers who are locked into a near subsistence farming situation presenting few opportunities for enterprise and income diversification. They have l [continued...]
Full Text Available.BackgroundAlthough many infections that are transmissible from person to person are acquired through direct contact between individuals, a minority, notably pulmonary tuberculosis (TB), measles and influenza are known to be spread by the airborne route. Airborne infections pose a particular threat to susceptible individuals whenever they are placed together with the index case in confined spaces. With this in mind, waiting areas of healthcare facilities present a particular challenge, since large numbers of people, some of whom may have underlying conditions which predispose them to infection, congregate in such spaces and can be exposed to an individual who may be shedding potentially pathogenic microorganisms. It is therefore important to understand the risks posed by infectious individuals in waiting areas, so that interventions can be developed to minimise the spread of airborne infections.MethodA stochastic Monte Carlo model was constructed to analyse the transmission of airborne infection in a hypothetical 132 m
High Quantum Efficiency Phototubes for Atmospheric Fluorescence Telescopes
2009-07-22
The detection of atmospheric fluorescence light from extensive air showers has become a powerful tool for accurate measurements of the energy and mass of ultra-high energy cosmic ray particles. Employing large area imaging telescopes with mirror areas of 10m2 or more, showers out to distances of 30km and more can be observed. Matrices of low-noise photomultipliers are used to detect the faint light of the air showers against the ambient night-sky background noise. The signal-to-noise ratio of such a system is found to be proportional to the square root of the mirror area times the quantum efficiency of the phototube. Thus, higher quantum efficiencies could potentially improve the quality of the measurement and/or lead to the construction of more compact telescopes. In this paper, we shall discuss such improvements to be expected from high quantum efficiency phototubes that became available on the market only very recently. A series of simulations has been performed with data of different types of commercially available high quantum efficiency phototubes. The results suggest a higher aperture and thus increased statistics for such telescopes. Additionally, the quality of the reconstruction can be improved.
2000-01-01
Recycling of wood-ash from combustion of bio-fuel could in the future become a common practice in Swedish forestry. As a consequence of the Chernobyl radioactive fallout in 1986 large areas in central Sweden became contaminated. There is a risk that addition of wood-ash originating from these contaminated areas will increase the activity of 137Cs in a forests if added to a non-contaminated area. We report here of measurements of 137Cs activity in different coniferous forest compartments from seven field experiments. The activity measurements were made 5-8 years after wood-ash application. The field experiments, in a north-south transect in Sweden, have received a background activity ranging 0 - 40 kBq m-2 as a consequence of the Chernobyl fallout. The applied wood-ash had an activity ranging between 0 - 4.8 kBq kg-1 ...
2010-01-01
Mt. Gongga area in southwest China was impacted by Hg emissions from industrial activities and coal combustion, and annual means of atmospheric TGM and PHg concentrations at a regional background station were 3.98 ng m-3 and 30.7 pg m-3, respectively. This work presents a mass balance study of Hg in an upland forest in this area. Atmospheric deposition was highly elevated in the study area, with the annual mean THg deposition flux of 92.5 mug m-2 yr-1. Total deposition was dominated by dry deposition (71.8%), and wet deposition accounted for the remaining 28.2%. Forest was a large pool of atmospheric Hg, and nearly 76% of the atmospheric input was stored in forest soil. Volatilization and stream outflow were identified as the two major pathways for THg losses from the forest, which yielded mean output fluxes of 14.0 and ...
1994-07-01
To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km[sup 2] sites as the area-weighted average of the shrub and understory or 'background' reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil-plant 'spectral interaction' term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna
The Capabilities of the GLAST Large Area Telescope for Blazar Variability Studies
One of the more notable features of the Large Area Telescope (LAT) on GLAST is its extremely large field of view, which covers more than 20 of the sky at any instant. In survey mode the LAT will be rocked about the orbital ...
Searching for an EBL attenuation signature in the Fermi/LAT 1st year catalog data
2010-08-26
Observations of distant sources of high-energy (HE) gamma-rays are affected by attenuation resulting from the interaction of the gamma-rays with low energy photons from the diffuse meta-galactic radiation fields at ultraviolet (UV) to infrared (IR) wavelengths (Extragalactic Background Light; EBL). Recently, a large data-set of HE observations from the 1st year survey of the Large Area Telescope (LAT) instrument on-board of the Fermi satellite became available, covering an energy range from 100 MeV up to 100 GeV. In this paper, the potential of such large HE data-sets to probe the density of the EBL - especially in the UV to optical - is explored. The data from the catalog is investigated for an attenuation signature in the energy range 10-100 GeV and the results are compared with the predictions from EBL model calculations. No clear signature is found. The statistics are still limited by (1) the sensitivity of Fermi/LAT to detect sources above 10 GeV, (2) the number of firmly identified sources with known redshift, both which will improve over the coming years.
Search for large-scale coincidences in network observation of cosmic ray air showers
The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) since 1996 in Japan. Eight compact EAS arrays (ten in the near future) are operating simultaneously and independently at distant stations (up to approx 1000 km), constituting a gigantic detector system as a whole. Using five stations' datasets, large-scale coincidences of EAS have been searched for with the aim of detecting signals from extremely short bursts in the universe. By comparing arrival times and arrival directions of all registered EAS, three coincident and parallel EAS pairs were extracted out of a sea of background cosmic rays. One of them was observed almost from the direction of the Crab Nebula, a previously reported ultra-high-energy gamma-ray source. The first application reported here allows the analysis techniques to be tested and demonstrates the potential of observations with the full operation of the network detector system.
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