WorldWideScience

Sample records for adjacent point sources

  1. Identification of Metal Emissions from Adjacent Point Sources in Northern Norway Using Moss Biomonitoring and Factor Analysis

    Atmospheric deposition of 34 trace elements around an iron smelter complex in a town in northern Norway was studied in 2000 and 2005 using neutron activation analysis of naturally growing moss. Specific contributions from two adjacent but distinct smelters and changes in operation that had occurred between the two sampling years were identified by factor analysis, and relative contributions from the two sources at different sampling sites were demonstrated by means of the factor scores. In 2000 emission from a ferroalloy smelter (Smelter I) caused substantial deposition of Cr and Fe, and this smelter was also the main source of Al, V, Co, Ni, As, Mo, and W. Another nearby plant (Smelter II) recovering metals from used materials caused considerable deposition of Mn and Zn and was also the main source of Sb and W deposition. Following a transition from ferrochrome to ferromanganese production Smelter I in 2005 showed substantial deposition of Mn. This smelter also still was the main source of Cr, Co, Ni, As, and Mo. Smelter II maintained a considerable Zn deposition and showed increased emissions of Sb and W. In most of the urban area the contribution from Smelter I was dominant. (authors)

  2. Identification of metal emissions from adjacent point sources in Northern Norway using moss biomonitoring and factor analysis

    Atmospheric deposition of 34 trace metals around an iron-smelter complex in a town in Northern Norway was studied in 2000 and 2005 using neutron activation analysis of naturally growing moss. Specific contributions from two adjacent but distinct smelters and changes in operation that had occurred between the two sampling years were identified by factor analysis, and relative contributions from the two sources at different sampling sites were demonstrated by means of the factor scores. In 2000, emission from a ferroalloy smelter (Smelter I) caused substantial deposition of Cr and Fe, and this smelter was also the main source of Al, V, Co, Ni, As, Mo, and W. Another nearby plant (Smelter II) recovering metals from used materials caused considerable deposition of Mn and Zn and was also the main source of Sb and W deposition. Following a transition from ferrochrome to ferromanganese production, Smelter I in 2005 showed substantial deposition of Mn. This smelter was also still the main source of Cr, Co, Ni, As, and Mo. Smelter II maintained a considerable Zn deposition and showed increased emissions of Sb and W. In most of the urban area the contribution from Smelter I was dominant. An exception was two sites in the north-east direction from the industries, where emissions from Smelter II dominated in 2000 as well as in 2005

  3. Microbial Source Tracking in Adjacent Karst Springs.

    Ohad, Shoshanit; Vaizel-Ohayon, Dalit; Rom, Meir; Guttman, Joseph; Berger, Diego; Kravitz, Valeria; Pilo, Shlomo; Huberman, Zohar; Kashi, Yechezkel; Rorman, Efrat

    2015-08-01

    Modern man-made environments, including urban, agricultural, and industrial environments, have complex ecological interactions among themselves and with the natural surroundings. Microbial source tracking (MST) offers advanced tools to resolve the host source of fecal contamination beyond indicator monitoring. This study was intended to assess karst spring susceptibilities to different fecal sources using MST quantitative PCR (qPCR) assays targeting human, bovine, and swine markers. It involved a dual-time monitoring frame: (i) monthly throughout the calendar year and (ii) daily during a rainfall event. Data integration was taken from both monthly and daily MST profile monitoring and improved identification of spring susceptibility to host fecal contamination; three springs located in close geographic proximity revealed different MST profiles. The Giach spring showed moderate fluctuations of MST marker quantities amid wet and dry samplings, while the Zuf spring had the highest rise of the GenBac3 marker during the wet event, which was mirrored in other markers as well. The revelation of human fecal contamination during the dry season not connected to incidents of raining leachates suggests a continuous and direct exposure to septic systems. Pigpens were identified in the watersheds of Zuf, Shefa, and Giach springs and on the border of the Gaaton spring watershed. Their impact was correlated with partial detection of the Pig-2-Bac marker in Gaaton spring, which was lower than detection levels in all three of the other springs. Ruminant and swine markers were detected intermittently, and their contamination potential during the wet samplings was exposed. These results emphasized the importance of sampling design to utilize the MST approach to delineate subtleties of fecal contamination in the environment. PMID:26002893

  4. Point Pollution Sources Dimensioning

    Georgeta CUCULEANU

    2011-06-01

    Full Text Available In this paper a method for determining the main physical characteristics of the point pollution sources is presented. It can be used to find the main physical characteristics of them. The main physical characteristics of these sources are top inside source diameter and physical height. The top inside source diameter is calculated from gas flow-rate. For reckoning the physical height of the source one takes into account the relation given by the proportionality factor, defined as ratio between the plume rise and physical height of the source. The plume rise depends on the gas exit velocity and gas temperature. That relation is necessary for diminishing the environmental pollution when the production capacity of the plant varies, in comparison with the nominal one.

  5. SPIRE Point Source Photometry

    Pearson, Chris; North, Chris; Bendo, George; Conversi, Luca; Dowell, Darren; Griffin, Matt; Jin, Terry; Laporte, Nicolas; Papageorgiou, Andreas; Schulz, Bernhard; Shupe, Dave; Smith, Anthony J; Xu, Kevin

    2014-01-01

    The different algorithms appropriate for point source photometry on data from the SPIRE instrument on-board the Herschel Space Observatory, within the Herschel Interactive Processing Environment (HIPE) are compared. Point source photometry of a large ensemble of standard calibration stars and dark sky observations is carried out using the 4 major methods within HIPE: SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture Photometry. Colour corrections and effective beam areas as a function of the assumed source spectral index are also included to produce a large number of photometric measurements per individual target, in each of the 3 SPIRE bands (250, 350, 500um), to examine both the accuracy and repeatability of each of the 4 algorithms. It is concluded that for flux densities down to the level of 30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least in the 250 and 350um bands, all 4 methods provide photometric repeatability better than a few percent down to at appr...

  6. The Herschel Point Source Catalogue

    Marton, Gábor; Altieri, Bruno; Calzoletti, Luca; Kiss, Csaba; Lim, Tanya; Lu, Nanyao; Paladini, Roberta; Papageorgiou, Andreas; Pearson, Chris; Rector, John; Shupe, David; Valtchanov, Ivan; Varga-Verebélyi, Erika; Xu, Kevin

    2015-01-01

    The Herschel Space Observatory was the fourth cornerstone mission in the European Space Agency (ESA) science programme with excellent broad band imaging capabilities in the sub-mm and far-infrared part of the spectrum. Although the spacecraft finished its observations in 2013, it left a large legacy dataset that is far from having been fully scrutinised and still has a large potential for new scientific discoveries. This is specifically true for the photometric observations of the PACS and SPIRE instruments. Some source catalogues have already been produced by individual observing programs, but there are many observations that risk to remain unexplored. To maximise the science return of the SPIRE and PACS data sets, we are in the process of building the Herschel Point Source Catalogue (HPSC) from all primary and parallel mode observations. Our homogeneous source extraction enables a systematic and unbiased comparison of sensitivity across the different Herschel fields that single programs will generally not b...

  7. The Herschel Point Source Catalogue

    Marton, Gabor; Schulz, Bernhard; Altieri, Bruno; Calzoletti, Luca; Kiss, Csaba; Lim, Tanya; Lu, Nanyao; Paladini, Roberta; Papageorgiou, Andreas; Pearson, Chris; Rector, John; Shupe, David; Valtchanov, Ivan; Verebélyi, Erika; Xu, Kevin

    2015-08-01

    The Herschel Space Observatory was the fourth cornerstone mission in the European Space Agency (ESA) science programme with excellent broad band imaging capabilities in the submillimetre and far-infrared part of the spectrum. Although the spacecraft finished its observations in 2013, it left a large legacy dataset that is far from having been fully scrutinized and still has potential for new scientific discoveries. This is specifically true for the photometric observations of the PACS and SPIRE instruments that scanned >10% of the sky at 70, 100, 160, 250, 350 and 500 microns. Some source catalogs have already been produced by individual observing programs, but there are many observations that would never be analyzed for their full source content. To maximize the science return of the SPIRE and PACS data sets, our international team of instrument experts is in the process of building the Herschel Point Source Catalog (HPSC) from all scan map observations. Our homogeneous source extraction enables a systematic and unbiased comparison of sensitivity across the different Herschel fields that single programs will generally not be able to provide. The extracted point sources will contain individual YSOs of our Galaxy, unresolved YSO clusters in resolved nearby galaxies and unresolved galaxies of the local and distant Universe that are related to star formation. Such a huge dataset will help scientists better understand the evolution from interstellar clouds to individual stars. Furthermore the analysis of stellar clusters and the star formation on galactic scales will add more details to the understanding of star formation laws through time.We present our findings on comparison of different source detection and photometric tools. First results of the extractions are shown along with the description of our pipelines and catalogue entries. We also provide an additional science product, the structure noise map, that is used for the quality assessment of the catalogue in

  8. Pollution parameters determination in water coast dispersion adjacent Carretas Point sub aquatic emissary

    It describes some results about transport processes, tracer techniques in Carretas Point sub aquatic emissary, discharge plume and emissary adjacent water coast in summer season. An overtaking and stability plume was verified. A contaminant unexpected and effusion localized was simulated. Scale effect near one coefficient was obtain Longitudinal dispersion coefficients and 1m2/seg and 0,02m2/seg transversal was estimated. The possibility to obtain information from first stages of transport analyzing fluorescence trace stain videos through geometric tools is discussed

  9. Interaction between two adjacent grounded sources in frequency domain semi-airborne electromagnetic survey

    Zhou, Haigen; Lin, Jun; Liu, Changsheng; Kang, Lili; Li, Gang; Zeng, Xinsen

    2016-03-01

    Multi-source and multi-frequency emission method can make full use of the valuable and short flight time in frequency domain semi-airborne electromagnetic (FSAEM) exploration, which has potential to investigate the deep earth structure in complex terrain region. Because several sources are adjacent in multi-source emission method, the interaction of different sources should be considered carefully. An equivalent circuit model of dual-source is established in this paper to assess the interaction between two individual sources, where the parameters are given with the typical values based on the practical instrument system and its application. By simulating the output current of two sources in different cases, the influence from the adjacent source is observed clearly. The current waveforms show that the mutual resistance causes the fluctuation and drift in another source and that the mutual inductance causes transient peaks. A field test with dual-source was conducted to certify the existence of interaction between adjacent sources. The simulation of output current also shows that current errors at low frequency are mainly caused by the mutual resistance while those at high frequency are mainly due to the mutual inductance. Increasing the distance between neighboring sources is a proposed measure to reduce the emission signal errors with designed ones. The feasible distance is discussed in the end. This study gives a useful guidance to lay multi sources to meet the requirement of measurement accuracy in FSAEM survey.

  10. Calcareous Fens - Source Feature Points

    Minnesota Department of Natural Resources — Pursuant to the provisions of Minnesota Statutes, section 103G.223, this database contains points that represent calcareous fens as defined in Minnesota Rules, part...

  11. Γ-source Neutral Point Clamped Inverter

    Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

    Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress and...... better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

  12. Point-defect sources and sinks

    The role played by sources and sinks of point defects is of importance in understanding a wide range of physical phenomena. The problem of the efficiency (eta) of a sink (or sources) and its relationship to the super (or sub) saturation of point defects which drives the process is considered. A qualitative discussion is given of the atomic mechanisms by which the following defects act as sources and sinks: (a) the free surface; (b) voids; (c) dislocation loops; and (d) grain boundaries. Examples of specific values of eta are given for different experimental situations

  13. Imaging of small radioactive point source displacement

    A new technique for three dimensional recording of a patient mandibular movement is described. A small and harmless radioactive source is fixed at the point of interest. Using proper collimation, the motion of the point source is recorded via a gamma camera and minicomputer. Image enhancement techniques are used and physiological displacement is reproduced. We measured the vertical, lateral and protrusive envelopes of motion of a point on a tooth from a full denture set mounted on a semiadjustable articulator. All displacements were calibrated. Multiple sources in a single experiment may be recorded to describe the displacement of several points of interest. First experiments were run on patients. This method, derived from Nuclear Medicine techniques, offers a powerful tool of general interest for the tracking of dynamic events in many fields of Dental Medicine, for instance temporo-mandibular joint disfunction as well as Prosthetics. (author)

  14. Will point sources spoil 21 cm tomography?

    Liu, Adrian; Zaldarriaga, Matias

    2008-01-01

    21 cm tomography is emerging as a promising probe of the cosmological dark ages and the epoch of reionization, as well as a tool for observational cosmology in general. However, serious sources of foreground contamination must be subtracted for experimental efforts to be viable. In this paper, we focus on the removal of unresolved extragalactic point sources with smooth spectra, and evaluate how the residual foreground contamination after cleaning depends on instrumental and algorithmic parameters. A crucial but often ignored complication is that the synthesized beam of an interferometer array shrinks towards higher frequency, causing complicated frequency structure in each sky pixel as "frizz" far from the beam center contracts across unresolved radio sources. We find that current-generation experiments should nonetheless be able to clean out this points source contamination adequately, and quantify the instrumental and algorithmic design specifications required to meet this foreground challenge.

  15. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    S. Bouillon

    2004-01-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1cm typically showed more enriched δ13C values than deeper (up to 10cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the simplifying assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on the results of this study and a compilation of literature data, we suggest that trapping of allochtonous C is a common feature in seagrass beds and often represents a significant source of C for sediment bacteria - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that data on community respiration rates systematically overestimate the role of in situ mineralization as a fate of seagrass production.

  16. Pseudo-dynamic source modelling with 1-point and 2-point statistics of earthquake source parameters

    Song, S. G.

    2013-12-24

    Ground motion prediction is an essential element in seismic hazard and risk analysis. Empirical ground motion prediction approaches have been widely used in the community, but efficient simulation-based ground motion prediction methods are needed to complement empirical approaches, especially in the regions with limited data constraints. Recently, dynamic rupture modelling has been successfully adopted in physics-based source and ground motion modelling, but it is still computationally demanding and many input parameters are not well constrained by observational data. Pseudo-dynamic source modelling keeps the form of kinematic modelling with its computational efficiency, but also tries to emulate the physics of source process. In this paper, we develop a statistical framework that governs the finite-fault rupture process with 1-point and 2-point statistics of source parameters in order to quantify the variability of finite source models for future scenario events. We test this method by extracting 1-point and 2-point statistics from dynamically derived source models and simulating a number of rupture scenarios, given target 1-point and 2-point statistics. We propose a new rupture model generator for stochastic source modelling with the covariance matrix constructed from target 2-point statistics, that is, auto- and cross-correlations. Our sensitivity analysis of near-source ground motions to 1-point and 2-point statistics of source parameters provides insights into relations between statistical rupture properties and ground motions. We observe that larger standard deviation and stronger correlation produce stronger peak ground motions in general. The proposed new source modelling approach will contribute to understanding the effect of earthquake source on near-source ground motion characteristics in a more quantitative and systematic way.

  17. Non-Gaussianity from extragalactic point sources

    We have described briefly the population of compact sources appearing at CMB frequencies, and studied their non-Gaussianity using publicly available full-sky simulations. Introducing a parametrization permitting to visualise efficiently the bispectrum, we have described the configuration and scale dependence of the bispectrum of radio and IR point sources, as well as its frequency dependence, and shown that it is well fitted by an analytical prescription. We have shown further that the clustering of IR sources increases their non-Gaussianity by several orders of magnitude, and that their bispectrum peaks in the squeezed triangles. Examining the impact of these sources on primordial non-Gaussianity estimation, we have found that the radio sources yield an important positive bias to local fNL estimation at low frequencies, but this bias is efficiently reduced by masking detectable sources. On the other hand, IR sources produce a negative bias at high frequencies, which is not dimmed by the masking, as their clustering is dominated by faint sources

  18. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    F. Dehairs

    2004-08-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1 cm typically showed more enriched δ13C values than deeper (up to 10 cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on these results and a compilation of literature data, we suggest that allochtonous carbon trapped in seagrass beds may often represent a significant fraction of the substrate for benthic mineralization - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that community respiration data systematically overestimate the role of mineralization in the overall seagrass C budget.

  19. Diffractive triangulation of radiative point sources

    Vespucci, Stefano; Maneuski, Dzmitry; O'Shea, Val; Winkelmann, Aimo

    2016-01-01

    We describe a general method to determine the location of a point source of waves relative to a two-dimensional active pixel detector. Based on the inherent structural sensitivity of crystalline sensor materials, characteristic detector diffraction patterns can be used to triangulate the location of a wave emitter. As a practical application of the wide-ranging principle, a digital hybrid pixel detector is used to localize a source of electrons for Kikuchi diffraction pattern measurements in the scanning electron microscope. This provides a method to calibrate Kikuchi diffraction patterns for accurate measurements of microstructural crystal orientations, strains, and phase distributions.

  20. Isotropic irradiation of detectors from point sources

    Aage, Helle Karina

    1997-01-01

    NaI(Tl) scintillator detectors have been exposed to gamma rays from 8 different point sources from different directions. Background and backscatter of gamma-rays from the surroundings have been subtracted in order to produce clean spectra. By adding spectra obtained from exposures from different ...... directions it is possible to generate the detector response to any radiation field. The obtained results are to be used for determing the dose or kerma rates equivalent to measured gamma ray spectra.......NaI(Tl) scintillator detectors have been exposed to gamma rays from 8 different point sources from different directions. Background and backscatter of gamma-rays from the surroundings have been subtracted in order to produce clean spectra. By adding spectra obtained from exposures from different...

  1. Upstream to downstream: a multiple-assessment-point approach for targeting non-point-source priority management areas at large watershed scale

    Chen, L.; Zhong, Y.; Wei, G; Shen, Z.

    2014-01-01

    The identification of priority management areas (PMAs) is essential for the control of non-point-source (NPS) pollution, especially for a large-scale watershed. However, previous studies have typically focused on small-scale catchments adjacent to specific assessment points; thus, the interactions between multiple river points remain poorly understood. In this study, a multiple-assessment-point PMA (MAP-PMA) framework was proposed by integrating the upstream sources and the ...

  2. Isotopic study of mercury sources and transfer between a freshwater lake and adjacent forest food web

    Studies of monomethylmercury (MMHg) sources and biogeochemical pathways have been extensive in aquatic ecosystems, but limited in forest ecosystems. Increasing evidence suggests that there is significant mercury (Hg) exchange between aquatic and forest ecosystems. We use Hg stable isotope ratios (δ202Hg and Δ199Hg) to investigate the relative importance of MMHg sources and assess Hg transfer pathways between Douglas Lake and adjacent forests located at the University of Michigan Biological Station, USA. We characterize Hg isotopic compositions of basal resources and use linear regression of % MMHg versus δ202Hg and Δ199Hg to estimate Hg isotope values for inorganic mercury (IHg) and MMHg in the aquatic and adjacent forest food webs. In the aquatic ecosystem, we found that lake sediment represents a mixture of IHg pools deposited via watershed runoff and precipitation. The δ202Hg and Δ199Hg values estimated for IHg are consistent with other studies that measured forest floor in temperate forests. The Δ199Hg value estimated for MMHg in the aquatic food web indicates that MMHg is subjected to ~ 20% photochemical degradation prior to bioaccumulation. In the forest ecosystem, we found a significant negative relationship between total Hg and δ202Hg and Δ199Hg of soil collected at multiple distances from the lakeshore and lake sediment. This suggests that IHg input from watershed runoff provides an important Hg transfer pathway between the forest and aquatic ecosystems. We measured Δ199Hg values for high trophic level insects and compared these insects at multiple distances perpendicular to the lake shoreline. The Δ199Hg values correspond to the % canopy cover suggesting that forest MMHg is subjected to varying extents of photochemical degradation and the extent may be controlled by sunlight. Our study demonstrates that the use of Hg isotopes adds important new insight into the relative importance of MMHg sources and complex Hg transfer pathways across

  3. Isotopic study of mercury sources and transfer between a freshwater lake and adjacent forest food web

    Kwon, Sae Yun, E-mail: saeyunk@umich.edu [Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave, Ann Arbor, MI 48109 (United States); Blum, Joel D. [Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave, Ann Arbor, MI 48109 (United States); Department of Ecology and Evolutionary Biology, University of Michigan, 830 N. University Ave, Ann Arbor, MI 48109 (United States); Nadelhoffer, Knute J. [Department of Ecology and Evolutionary Biology, University of Michigan, 830 N. University Ave, Ann Arbor, MI 48109 (United States); Timothy Dvonch, J. [Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Tsui, Martin Tsz-Ki [Department of Biology, University of North Carolina at Greensboro, 321 McIver Street, Greensboro, NC 27402 (United States)

    2015-11-01

    Studies of monomethylmercury (MMHg) sources and biogeochemical pathways have been extensive in aquatic ecosystems, but limited in forest ecosystems. Increasing evidence suggests that there is significant mercury (Hg) exchange between aquatic and forest ecosystems. We use Hg stable isotope ratios (δ{sup 202}Hg and Δ{sup 199}Hg) to investigate the relative importance of MMHg sources and assess Hg transfer pathways between Douglas Lake and adjacent forests located at the University of Michigan Biological Station, USA. We characterize Hg isotopic compositions of basal resources and use linear regression of % MMHg versus δ{sup 202}Hg and Δ{sup 199}Hg to estimate Hg isotope values for inorganic mercury (IHg) and MMHg in the aquatic and adjacent forest food webs. In the aquatic ecosystem, we found that lake sediment represents a mixture of IHg pools deposited via watershed runoff and precipitation. The δ{sup 202}Hg and Δ{sup 199}Hg values estimated for IHg are consistent with other studies that measured forest floor in temperate forests. The Δ{sup 199}Hg value estimated for MMHg in the aquatic food web indicates that MMHg is subjected to ~ 20% photochemical degradation prior to bioaccumulation. In the forest ecosystem, we found a significant negative relationship between total Hg and δ{sup 202}Hg and Δ{sup 199}Hg of soil collected at multiple distances from the lakeshore and lake sediment. This suggests that IHg input from watershed runoff provides an important Hg transfer pathway between the forest and aquatic ecosystems. We measured Δ{sup 199}Hg values for high trophic level insects and compared these insects at multiple distances perpendicular to the lake shoreline. The Δ{sup 199}Hg values correspond to the % canopy cover suggesting that forest MMHg is subjected to varying extents of photochemical degradation and the extent may be controlled by sunlight. Our study demonstrates that the use of Hg isotopes adds important new insight into the relative

  4. Investigation of Threshold Voltage Disturbance Caused by Programmed Adjacent Cell in Virtual Source/Drain NAND Flash Memory

    Kim, Wandong; Kwon, Dae Woong; Ji, Jung Hwan; Lee, Jung Hoon; Lee, Jong-Ho; Shin, Hyungcheol; Park, Byung-Gook

    2011-04-01

    In this paper, we investigate the threshold voltage disturbance caused by programmed adjacent cells in virtual source/drain (VSD) NAND flash memory device. The fringing field induced by charge in an adjacent memory node inhibits the inversion of virtual source/drain region. So, it increases the threshold voltage of the read cell. This is a drawback for the multi-level cell (MLC) operation. The device simulation and measurement data of fabricated devices show that the disturbance increases as the cell gate length and VSD length decreases. It can be minimized by the electric field concentration induced by the arch shape structure.

  5. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya)

    BOUILLON, S; Moens, T.; F. Dehairs

    2004-01-01

    The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya) by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids) and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC) and δ13CTOC data. PLFA δ13C data indicate tha...

  6. Sources of Heavy Metals in Surface Sediments and an Ecological Risk Assessment from Two Adjacent Plateau Reservoirs

    Wu, Binbin; Wang, Guoqiang; Wu, Jin; Fu, Qing; Liu, Changming

    2014-01-01

    The concentrations of heavy metals (mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu) and arsenic (As)) in surface water and sediments were investigated in two adjacent drinking water reservoirs (Hongfeng and Baihua Reservoirs) on the Yunnan-Guizhou Plateau in Southwest China. Possible pollution sources were identified by spatial and statistical analyses. For both reservoirs, Cd was most likely from industrial activities, and As was from lithogenic sources. For the Hongfeng Re...

  7. Three-dimensional locating of paraxial point source with axicon

    Snoeyink, Craig; Wereley, Steven

    2012-01-01

    This Letter presents a theoretical and experimental study of an axicon illuminated by an off-axis paraxial point source. The Fresnel diffraction integral is applied to show that a paraxial point source produces a Bessel beam. A simple analytical relationship is demonstrated between the location of the point source and the spatial frequency and the center of the resulting Bessel beam in the image plane of a camera. Finally, experimental verification is given by translating a point source of li...

  8. Investigation and Analysis of Guangzhou Nansha Coast Park Point Source Pollution and Non-point Source Pollution

    Yang, Ruijie; Zeng, Huanghuang; Chen, Budan; Chen, Fang; Wu, Shikai

    2014-01-01

    [Objective]To find out the situation of Nansha Coast Park point and non-point source pollution. [Method] By investigating the park water environment analysis of point and non-point source pollutants contribution rate, setting up water quality monitoring sites for basic data related indicators and then using national water quality standards to evaluate water quality.[Result]The Coast Park point source pollution mainly comes from the campus greeting fertilizer spraying. The COD of lakes and riv...

  9. Virtual point source efficiency calibration method for voluminous sample of radio-xenon based on efficiency function of point source

    A virtual point source calibration method is developed to finish the calibration of voluminous sample. We used a mixed point source to get the parameters of efficiency function, obtaining the virtual position of voluminous sample. So, the detection efficiency of xenon samples and standard soil samples were calibrated by placing the point source at their virtual position. The Monte Carlo method was also used to simulate the detector efficiency of xenon samples. Deviations between the virtual source method and Monte Carlo simulation are within 2.2 % for xenon samples. Thus, we have developed two robust efficiency calibration methods based on Monte Carlo simulations and virtual point source, respectively. (author)

  10. A statistical test of emission from unresolved point sources

    Slatyer, Tracy R.; Finkbeiner, Douglas P.

    2009-01-01

    We describe a simple test of the spatial uniformity of an ensemble of discrete events. Given an estimate for the point source luminosity function and an instrumental point spread function (PSF), a robust upper bound on the fractional point source contribution to a diffuse signal can be found. We verify with Monte Carlo tests that the statistic has advantages over the two-point correlation function for this purpose, and derive analytic estimates of the statistic's mean and variance as a functi...

  11. Global Sourcing if Contracts are Reference Points

    Kukharskyy, Bohdan

    2012-01-01

    This paper presents econometric evidence for a link between a country’s level of egalitarianism and its inward foreign direct investment. In order to provide a theoretical rationale for this relationship, I embed Hart and Moore’s (2008) novel contractual foundation into a simple model of global sourcing with culturally dissimilar countries. Entrepreneurs can cooperate with foreign suppliers under two contractual modes: rigid and flexible. If suppliers consider original contracts as reference ...

  12. Three-dimensional locating of paraxial point source with axicon.

    Snoeyink, Craig; Wereley, Steve

    2012-06-01

    This Letter presents a theoretical and experimental study of an axicon illuminated by an off-axis paraxial point source. The Fresnel diffraction integral is applied to show that a paraxial point source produces a Bessel beam. A simple analytical relationship is demonstrated between the location of the point source and the spatial frequency and the center of the resulting Bessel beam in the image plane of a camera. Finally, experimental verification is given by translating a point source of light along the optical axis of an axicon and comparing the resulting predicted and recorded beam intensity profiles. The resulting images are then analyzed to predict the location of the point source with excellent accuracy. PMID:22660120

  13. Transactions Costs and Point-Nonpoint Source Water Pollution Trading

    Nguyen, Nga; Shortle, James S.

    2006-01-01

    The implications of transactions costs for the performance of water pollution trading involving point and nonpoint sources are examined. The analysis focuses on the impacts of transaction costs on different classes of trading partners and its consequence on the trading equilibrium. The model of point-nonpoint water pollution trading in the context of the total maximum daily loads explicitly incorporates transactions costs for both buying and selling exchanges of nonpoint source and point sour...

  14. Sources of heavy metals in surface sediments and an ecological risk assessment from two adjacent Plateau reservoirs.

    Binbin Wu

    Full Text Available The concentrations of heavy metals (mercury (Hg, cadmium (Cd, lead (Pb, chromium (Cr, copper (Cu and arsenic (As in surface water and sediments were investigated in two adjacent drinking water reservoirs (Hongfeng and Baihua Reservoirs on the Yunnan-Guizhou Plateau in Southwest China. Possible pollution sources were identified by spatial and statistical analyses. For both reservoirs, Cd was most likely from industrial activities, and As was from lithogenic sources. For the Hongfeng Reservoir, Pb, Cr and Cu might have originated from mixed sources (traffic pollution and residual effect of former industrial practices, and the sources of Hg included the inflows, which were different for the North (industrial activities and South (lithogenic origin Lakes, and atmospheric deposition resulting from coal combustion. For the Baihua Reservoir, the Hg, Cr and Cu were primarily derived from industrial activities, and the Pb originated from traffic pollution. The Hg in the Baihua Reservoir might also have been associated with coal combustion pollution. An analysis of ecological risk using sediment quality guidelines showed that there were moderate toxicological risks for sediment-dwelling organisms in both reservoirs, mainly from Hg and Cr. Ecological risk analysis using the Hakanson index suggested that there was a potential moderate to very high ecological risk to humans from fish in both reservoirs, mainly because of elevated levels of Hg and Cd. The upstream Hongfeng Reservoir acts as a buffer, but remains an important source of Cd, Cu and Pb and a moderately important source of Cr, for the downstream Baihua Reservoir. This study provides a replicable method for assessing aquatic ecosystem health in adjacent plateau reservoirs.

  15. Improved Dijkstra Algorithm Based on the Adjacent Point in Shortest Path%基于邻接点算法的Dijkstra优化研究

    王华

    2013-01-01

    Abstract the urban road into network diagram and definition of data structures for road and site. Improve the Dijkstra by adjacent point algorithm, the method build the adjacency matrix and the initial judgment matrix and get the shortest path between two points in the network diagram. The efficiency of the algorithm is apparent when there are more points. Experiments show that adjacent point algorithm not only saves storage space, but also improves the efficiency of operations.%在将城市道路实体抽象为图论理论中的网络图,对道路和站点数据结构进行定义的基础上,利用邻接点算法对Dijkstra算法进行改进,通过构建邻接矩阵和初始判断矩阵,得出网络图中任意两点间的最短路径.当点数越多时改进算法的效率就显现出来,结果表明邻接点算法在一定程度上既节省了存储空间,又提高了运算效率.

  16. Focal Mechanism Analysis for Determination of Potential Source Zones in South China and Its Adjacent Regions

    Zheng Yuejun; Zhang Shimin; Cui Xiaofeng; Huang Zhongxian

    2006-01-01

    Based on the results of focal mechanism solutions in southeastern areas of China (south of 34°N and east of 105°E), this article analyzes the correlation of focal mechanism solutions with seismogenic structures of moderate strong earthquakes and the direction of potential source zones. The data show that the nodal planes of focal mechanism solutions and the principle stresses in southern China are of predominantly similar directions, most of the solutions for M ≥4.0 earthquakes correspond to the main structure directions as well as the directions of potential source zones. The statistical results of multiple small earthquakes concerning nodal planes and main stress axes are also reliable for determining the direction of potential source zones. According to the analysis of focal mechanism solutions, long-axis direction of isoseismais distribution of aftershocks, geologic structures, and seismic activity in two areas of the Ms6.1earthquake in the south Yellow Sea in 1996 and the Ms5.2 earthquake in Fujian in 1997, the potential source zone division is discussed.

  17. Types of water pollution: point source and nonpoint source

    Oana V. Viman; Ioan Oroian; Andrei Fleșeriu

    2010-01-01

    Water is an important element to human life, this is why around water sources humansettlements have been built which led to the development of these specific areas. One person needs aminimum of 5 L water per day, out of which 1.5-2 L are consumed as know and the rest is beingretained from food (Ghidra 2004). Due to this water pollution has a negative impact on human andanimal health and it also affects the surrounding environment. Water pollution means changes on itsnatural qualities and the ...

  18. Types of water pollution: point source and nonpoint source

    Oana V. Viman

    2010-12-01

    Full Text Available Water is an important element to human life, this is why around water sources humansettlements have been built which led to the development of these specific areas. One person needs aminimum of 5 L water per day, out of which 1.5-2 L are consumed as know and the rest is beingretained from food (Ghidra 2004. Due to this water pollution has a negative impact on human andanimal health and it also affects the surrounding environment. Water pollution means changes on itsnatural qualities and the inclusion of foreign elements, resulted from a series of natural and artificialphenomena, making it unsuitable for the previously mentioned aims. Water pollution can be natural orartificial and it can have permanent, irregular or accidental effects.

  19. Tracing sources of organic matter in adjacent urban streams having different degrees of channel modification.

    Duan, Shuiwang; Amon, Rainer M W; Brinkmeyer, Robin L

    2014-07-01

    Urbanization and stream-channel modifications affect organic matter concentrations and quality in streams, by altering allochthonous organic matter input and in-stream transformation. This study uses multiple tracers (δ(13)C, δ(15)N, C/N ratio, and chlorophyll-a) to track sources of organic matter in two highly urbanized bayous in Houston (Texas, USA). Wastewater treatment plants (WWTPs) are located in headwaters of both bayous and contribute more than 75% to water flow. Low isotopic relatedness to natural end-members and enriched δ(15)N values suggest the influence of WWTPs on the composition of all organic matter fractions. The two bayous differ in degree of channel improvement resulting in different responses to hydrological conditions. During high flow conditions, the influence of terrestrial organic matter and sediment resuspension was much more pronounced in the Buffalo Bayou than in the concrete-lined White Oak Bayou. Particulate organic matter (POM) in White Oak Bayou had similar values of enriched δ(15)N in all subsegments, whereas in Buffalo Bayou, the degree of δ(15)N enrichment was less in the subsegments of the lower watershed. The difference in riparian zone contributions and interactions with sediments/soils was likely responsible for the compositional differences between the two bayous. Phytoplankton inputs were significantly higher in the bayous, especially in slow-flowing sections, relative to the reference sites, and elevated phytoplankton inputs accounted for the observed stable C isotope differences between FPOM and high molecular weight dissolved organic matter (HMW DOM). Relative to POM, HMW DOM in the bayous was similar to WWTP effluents and showed minor longitudinal variability in both streams suggesting that WWTPs contribute much of the DOM in the systems. Urbanization has a major influence on organic matter sources and quality in these urban water bodies and these changes seem further enhanced by stream channel modifications. PMID

  20. Collective liability in non-point source pollution

    Ali, Mourad; Rio, Patrick; Martin-Luther University Halle-Wittenberg

    2006-01-01

    Non point source pollution is characterized by the fact that individual emissions are not observable at a reasonable cost. This constitutes a moral hazard problem. Furthermore, we explicitly consider adverse selection, a second type of asymmetric information that arises because of the difficulty to differentiate the polluters with respect to their type (marginal benefit of polluting). In this paper, we design a tradable permits market between non point sources of pollution. In order to involv...

  1. 2011 Radioactive Materials Usage Survey for Unmonitored Point Sources

    Sturgeon, Richard W. [Los Alamos National Laboratory

    2012-06-27

    This report provides the results of the 2011 Radioactive Materials Usage Survey for Unmonitored Point Sources (RMUS), which was updated by the Environmental Protection (ENV) Division's Environmental Stewardship (ES) at Los Alamos National Laboratory (LANL). ES classifies LANL emission sources into one of four Tiers, based on the potential effective dose equivalent (PEDE) calculated for each point source. Detailed descriptions of these tiers are provided in Section 3. The usage survey is conducted annually; in odd-numbered years the survey addresses all monitored and unmonitored point sources and in even-numbered years it addresses all Tier III and various selected other sources. This graded approach was designed to ensure that the appropriate emphasis is placed on point sources that have higher potential emissions to the environment. For calendar year (CY) 2011, ES has divided the usage survey into two distinct reports, one covering the monitored point sources (to be completed later this year) and this report covering all unmonitored point sources. This usage survey includes the following release points: (1) all unmonitored sources identified in the 2010 usage survey, (2) any new release points identified through the new project review (NPR) process, and (3) other release points as designated by the Rad-NESHAP Team Leader. Data for all unmonitored point sources at LANL is stored in the survey files at ES. LANL uses this survey data to help demonstrate compliance with Clean Air Act radioactive air emissions regulations (40 CFR 61, Subpart H). The remainder of this introduction provides a brief description of the information contained in each section. Section 2 of this report describes the methods that were employed for gathering usage survey data and for calculating usage, emissions, and dose for these point sources. It also references the appropriate ES procedures for further information. Section 3 describes the RMUS and explains how the survey results are

  2. Semiclassical Theory of Superresolution for Two Incoherent Optical Point Sources

    Tsang, Mankei; Lu, Xiao-Ming

    2016-01-01

    Using a semiclassical model of photodetection with Poissonian noise and insights from quantum metrology, we prove that linear optics and photon counting can optimally estimate the separation between two incoherent point sources without regard to Rayleigh's criterion. The model is applicable to weak thermal or fluorescent sources as well as lasers.

  3. The Economics of Non-Point-Source Pollution

    Anastasios Xepapadeas

    2011-01-01

    Non-point-source (NPS) pollution refers to a form of pollution in which neither the source nor the size of specific emissions can be observed or identified with sufficient accuracy. In NPS pollution the ambient concentration of pollutants associated with the individually unobserved emissions is typically observed. NPS pollution due to agricultural runoff is a major source of water pollution, eutrophication, and hypoxia. Due to informational asymmetries and stochastic effects, the use of tradi...

  4. A modern analog for carbonate source-to-sink sedimentary systems: the Glorieuses archipelago and adjacent basin (SW Indian Ocean)

    Jorry, S.; Jouet, G.; Prat, S.; Courgeon, S.; Le Roy, P.; Camoin, G.; Caline, B.

    2014-12-01

    This study presents the geomorphological and sedimentological analysis of a modern carbonate source-to-sink system located north of Madagascar (SW Indian Ocean). The sedimentary system is composed of an isolated carbonate platform sited on top of a seamount rising steeply from the seabed located at 3000 m water depth. The slope of the seamount is incised by canyons, and meandering channels occur above lobbed sedimentary bodies at the foot of the slope. The dataset consists of dredges, sediment piston cores, swath bathymetry and seismic (sparker and 2D high-resolution) lines collected from inner platform (less than 5 m deep) to the adjacent deep sedimentary basin. Particle size analysis and composition of carbonate grains are used to characterize the distribution and heterogeneity of sands accumulated on the archipelago. Main results show that composition of carbonate sediments is dominated by segments of Halimeda, large benthic foraminifera, coral debris, molluscs, echinoderms, bryozoans and sponges. According to the shape and the position of sandwaves and intertidal sandbars developed in the back-barrier reef, the present organization of these well-sorted fine-sand accumulations appears to be strongly influenced by flood tidal currents. Seismic lines acquired from semi-enclosed to open lagoon demonstrate that most of the sediment is exported and accumulated along the leeward margin of the platform, which is connected to a canyon network incising the outer slope. Following the concept of highstand shedding of carbonate platforms (Schlager et al., 1994), excess sediment is exported by plumes and gravity flows to the adjacent deep sea where it feeds a carbonate deep-sea fan. Combined observations from platform to basin allow to explain how the Glorieuses carbonate source to sink system has evolved under the influence of climate and of relative sea-level changes since the last interglacial.

  5. Benthic faunal sampling adjacent to the Barbers Point ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900098)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size...

  6. Non-Gaussianity from extragalactic point-sources

    Lacasa, Fabien

    2012-01-01

    The population of compact extragalactic sources contribute to the non-Gaussianity at Cosmic Microwave Background frequencies. We study their non-Gaussianity using publicly available full-sky simulations. We introduce a parametrisation to visualise efficiently the bispectrum and we describe the scale and frequency dependences of the bispectrum of radio and IR point-sources. We show that the bispectrum is well fitted by an analytical prescription. We find that the clustering of IR sources enhances their non-Gaussianity by several orders of magnitude, and that their bispectrum peaks in the squeezed triangles. Examining the impact of these sources on primordial non-Gaussianity estimation, we find that radio sources yield an important positive bias to local fNL at low frequencies but this bias is efficiently reduced by masking detectable sources. IR sources produce a negative bias at high frequencies, which is not dimmed by the masking, as their clustering is dominated by faint sources.

  7. X pinch a point x-ray source

    X ray emission from an X pinch, a point x-ray source has been studied using a pin-hole camera by a 30 kV, 7.2 μ F capacitor bank. The wires of different material like W, Mo, Cu, S.S.(stainless steel) and Ti were used. Molybdenum pinch gives the most intense x-rays and stainless steel gives the minimum intensity x-rays for same bank energy (∼ 3.2 kJ). Point x-ray source of size (≤ 0.5 mm) was observed using pin hole camera. The size of the source is limited by the size of the pin hole camera. The peak current in the load is approximately 150 kA. The point x-ray source could be useful in many fields like micro lithography, medicine and to study the basic physics of high Z plasmas. (author). 4 refs., 3 figs

  8. Trans-Z-source Neutral Point Clamped inverter

    Mo, W.; Loh, P. C.; Li, D.;

    2012-01-01

    Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used for...... buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper...... modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed...

  9. Investigation and Analysis of Guangzhou Nansha Coast Park Point Source Pollution and Non-point Source Pollution

    Ruijie; YANG; Huanghuang; ZENG; Budan; CHEN; Fang; CHEN; Shikai; WU

    2014-01-01

    [Objective]To find out the situation of Nansha Coast Park point and non-point source pollution.[Method]By investigating the park water environment,analysis of point and non-point source pollutants contribution rate,setting up water quality monitoring sites for basic data related indicators and then using national water quality standards to evaluate water quality.[Result]The Coast Park point source pollution mainly comes from the campus greeting fertilizer spraying.The COD of lakes and river outside the park and ammonia mean concentration belong to grade III.The total nitrogen of lake belongs to grade III.The total phosphorus belongs to grade IV.The total nitrogen of river is the worst.The total phosphorus is grade V.[Conclusion] The lake water quality is highly affected by the point and non-point source pollution,the quality of the river is worse than that of the lake in the park,and it needs powerful governance.

  10. Search for cosmic-ray point sources with KASCADE

    Antoni, T; Badea, A F; Bekk, K; Bercuci, A; Blümer, H; Bozdog, H; Brancus, I M; Büttner, C; Daumiller, K; Doll, P; Engel, R; Engler, J; Fessler, F; Gils, H J; Glasstetter, R; Haungs, A; Heck, D; Hörandel, J R; Kampert, K H; Klages, H O; Maier, G; Mathes, H J; Mayer, H J; Milke, J; Müller, M; Obenland, R; Oehlschläger, J; Ostapchenko, S; Petcu, M; Rebel, H; Risse, A; Risse, M; Roth, M; Schatz, G; Schieler, H; Scholz, J; Thouw, T; Ulrich, H; Van, J; Buren; Vardanyan, A; Weindl, A; Wochele, J; Zabierowski, J

    2004-01-01

    A survey of the northern hemisphere for astrophysical point sources with continuous emission of high-energy cosmic rays is presented. Around 47 Mio extensive air showers with primary energies above $\\approx$ 300 TeV measured by the KASCADE detector field are selected for this analysis. Besides the sky survey, a search for signal excess in the region of the galactic plane and of selected point source candidates has been performed. There is no evidence for any significant excess. This is valid for an analysis of all recorded showers as well as for a data set enhanced in gamma-ray induced showers. An upper flux limit of around $3\\times 10^{-10}$ m$^{-2}$s$^{-1}$ for a steady point source that transits the zenith is obtained. Additionally, the distribution of the arrival directions of extensive air showers with energies above 80 PeV were studied by an autocorrelation analysis.

  11. On the point-source approximation of earthquake dynamics

    Andrea Bizzarri

    2014-06-01

    Full Text Available The focus on the present study is on the point-source approximation of a seismic source. First, we compare the synthetic motions on the free surface resulting from different analytical evolutions of the seismic source (the Gabor signal (G, the Bouchon ramp (B, the Cotton and Campillo ramp (CC, the Yoffe function (Y and the Liu and Archuleta function (LA. Our numerical experiments indicate that the CC and the Y functions produce synthetics with larger oscillations and correspondingly they have a higher frequency content. Moreover, the CC and the Y functions tend to produce higher peaks in the ground velocity (roughly of a factor of two. We have also found that the falloff at high frequencies is quite different: it roughly follows ω−2 in the case of G and LA functions, it decays more faster than ω−2 for the B function, while it is slow than ω−1 for both the CC and the Y solutions. Then we perform a comparison of seismic waves resulting from 3-D extended ruptures (both supershear and subshear obeying to different governing laws against those from a single point-source having the same features. It is shown that the point-source models tend to overestimate the ground motions and that they completely miss the Mach fronts emerging from the supershear transition process. When we compare the extended fault solutions against a multiple point-sources model the agreement becomes more significant, although relevant discrepancies still persist. Our results confirm that, and more importantly quantify how, the point-source approximation is unable to adequately describe the radiation emitted during a real world earthquake, even in the most idealized case of planar fault with homogeneous properties and embedded in a homogeneous, perfectly elastic medium.

  12. Ultimate quantum limit on resolution of two thermal point sources

    Nair, Ranjith

    2016-01-01

    We obtain the fundamental quantum limit for resolving two thermal point sources using an imaging system with limited spatial bandwidth. Using the quantum Cram\\'er-Rao bound, we show that the standard Rayleigh limit is not fundamental and can be surpassed by concrete coherent measurement techniques. Our results are valid for all values of the source strength, all ranges of the electromagnetic spectrum, and for any imaging system with an inversion-symmetric point-spread function. Our findings have applications to many areas of metrology including microscopy, astronomy, and standoff target sensing.

  13. On the point source approximation of nearby cosmic-ray sources

    Thoudam, S.; Hörandel, J. R.

    2012-01-01

    In this paper, we check in detail the validity of the widely adopted point source approximation for nearby cosmic-ray (CR) sources. Under an energy independent escape model for CRs from the sources, we show that for young nearby sources, the point source approximation breaks down at lower energies and the CR spectrum depends on the size and the morphology of the source. When applied to the nearby supernova remnants (SNRs), we find that the approximation breaks down for some of the individual ...

  14. Search for high energy cosmic neutrino point sources with ANTARES

    The aim of this thesis is the search for high energy cosmic neutrinos emitted by point sources with the ANTARES neutrino telescope. The detection of high energy cosmic neutrinos can bring answers to important questions such as the origin of cosmic rays and the γ-rays emission processes. In the first part of the thesis, the neutrino flux emitted by galactic and extragalactic sources and the number of events which can be detected by ANTARES are estimated. This study uses the measured γ-ray spectra of known sources taking into account the γ-ray absorption by the extragalactic background light. In the second part of the thesis, the absolute pointing of the ANTARES telescope is evaluated. Being located at a depth of 2475 m in sea water, the orientation of the detector is determined by an acoustic positioning system which relies on low and high frequency acoustic waves measurements between the sea surface and the bottom. The third part of the thesis is a search for neutrino point sources in the ANTARES data. The search algorithm is based on a likelihood ratio maximization method. It is used in two search strategies; 'the candidate sources list strategy' and 'the all sky search strategy'. Analysing 2007+2008 data, no discovery is made and the world's best upper limits on neutrino fluxes from various sources in the Southern sky are established. (author)

  15. Identifying populations at risk from environmental contamination from point sources

    Williams, F; Ogston, S

    2002-01-01

    Objectives: To compare methods for defining the population at risk from a point source of air pollution. A major challenge for environmental epidemiology lies in correctly identifying populations at risk from exposure to environmental pollutants. The complexity of today's environment makes it essential that the methods chosen are accurate and sensitive.

  16. POINT-NONPOINT SOURCE POLLUTION TRADING USING COLLECTIVE PERFORMANCE INCENTIVES

    Taylor, Michael A.; Randall, Alan; Sohngen, Brent

    2001-01-01

    Point-nonpoint trading markets must accommodate the problem of monitoring individual nonpoint source discharges (NPS). A permit trading market that allows the regulator to monitor noncompliance based on observable aggregate NPS pollution levels, through the use of a collective enforcement mechanism, may be more efficient than traditional technology-based trading.

  17. Source point calibration from an arbitrary electron backscattering pattern

    Lassen, Niels Christian Krieger

    1999-01-01

    Precise knowledge of the position of the source point is a requirement if electron backscattering patterns (EBSPs) are to be used for crystal orientation measurements or other types of measurements which demand a geometrical analysis of the patterns. Today, possibly the most popular method for...

  18. Open Source Software Reliability Growth Model by Considering Change- Point

    Mashaallah Basirzadeh

    2012-01-01

    Full Text Available The modeling technique for Software Reliability is reaching its prosperity. Software reliability growth models have been used extensively for closed source software. The design and development of open source software (OSS is different from closed source software. We observed some basic characteristics for open source software like (i more instructions execution and code coverage taking place with respect to time, (ii release early, release often (iii frequent addition of patches (iv heterogeneity in fault density and effort expenditure (v Frequent release activities seem to have changed the bug dynamics significantly (vi Bug reporting on bug tracking system drastically increases and decreases. Due to this reason bug reported on bug tracking system keeps an irregular state and fluctuations. Therefore, fault detection/removal process can not be smooth and may be changed at some time point called change-point. In this paper, an instructions executed dependent software reliability growth model has been developed by considering change-point in order to cater diverse and huge user profile, irregular state of bug tracking system and heterogeneity in fault distribution. We have analyzed actual software failure count data to show numerical examples of software reliability assessment for the OSS. We also compare our model with the conventional in terms of goodness-of-fit for actual data. We have shown that the proposed model can assist improvement of quality for OSS systems developed under the open source project.

  19. COMPTEL Time-Averaged All-Sky Point Source Analysis

    Collmar, W; Strong, A W; Blömen, H; Hermsen, W; McConnell, M; Ryan, J; Bennett, K

    1999-01-01

    We use all COMPTEL data from the beginning of the CGRO mission (April '91) upto the end of CGRO Cycle 6 (November '97) to carry out all-sky point sourceanalyses in the four standard COMPTEL energy bands for different time periods.We apply our standard maximum-likelihood method to generate all-skysignificance and flux maps for point sources by subtracting off the diffuseemission components via model fitting. In addition, fluxes of known sourceshave been determined for individual CGRO Phases/Cycles to generate lightcurveswith a time resolution of the order of one year. The goal of the analysis is toderive quantitative results -- significances, fluxes, light curves -- of ourbrightest and most significant sources such as 3C 273, and to search foradditional new COMPTEL sources, showing up in time-averaged maps only.

  20. From an instantaneous point source to a continuous volume source. Calculation of pollutant concentrations

    The diffusion of pollutants in gaseous or liquid media is investigated. At first, the molecular diffusion is studied using the continuous point source model. Pollutant concentration is determined by means of Green's function. Then follows the investigation of turbulent diffusion in a flowing medium. The K-theory is applied in order to calculate the pollutant concentrations for short-time or continuous point source, line source, large-area source, or volume source in a flow field of an anisotropic medium. The extensive differential equations and their analytical solutions are explained in detail. (KW)

  1. Search for point sources of high energy neutrinos with Amanda

    Report of search for likely point sources for neutrinos observed by the Amanda detector. Places intensity limits on observable point sources. This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes, used for the detection of Cherenkov light from upward traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cherenkov telescope and the SPASE extensive air shower array. Using data collected from April to October of 1997 (130.1 days of livetime), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the Northern sky, the effective detection area exceeds 10,000 m2 for Eμ ∼ 10 TeV. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to Eν-2 and declination larger than +40o, we obtain E2 (dNν/dE) (le) 10-6 GeV cm-2 s-1 for an energy threshold of 10 GeV

  2. A new inventory for middle east dust source points.

    Moridnejad, Ali; Karimi, Neamat; Ariya, Parisa A

    2015-09-01

    We use the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on both Terra and Aqua satellites to present new high-resolution mapping of major atmospheric dust source points in the Middle East region on the basis of the improved version of the recently developed Middle East Dust Index (MEDI) applied to 70 dust storms, which occurred during the period between 2001 and 2012. Results indicate that 247 different source points have participated in dust storm generation in the Middle East region in which Iraq and Syria are the highest efficient sites for dust storm generation in this region, respectively. Using extracted indices for Deep Blue algorithm, identified dust sources were classified into three levels of intensity. The frequency of occurrence approach, the relationship between high atmospheric dust content and its number of occurrences, is also used to identify sensitive source points. High-intensity dust storms are mainly located west of Iraq and the border of Iraq and Syria. We will discuss the implications of our results in understanding the global dust cycle. PMID:26297415

  3. Super-resolution for a point source using positive refraction

    Miñano Dominguez, Juan Carlos; Benitez Gimenez, Pablo; Gonzalez Lopez, Juan Carlos; Grabovičkić, Dejan; Ahmadpanahi, Hammed

    2012-01-01

    Leonhardt demonstrated (2009) that the 2D Maxwell Fish Eye lens (MFE) can focus perfectly 2D Helmholtz waves of arbitrary frequency, i.e., it can transport perfectly an outward (monopole) 2D Helmholtz wave field, generated by a point source, towards a receptor called "perfect drain" (PD) located at the corresponding MFE image point. The PD has the property of absorbing the complete radiation without radiation or scattering and it has been claimed as necessary to obtain super-resolution (SR) i...

  4. Point sources and multipoles in inverse scattering theory

    Potthast, Roland

    2001-01-01

    Over the last twenty years, the growing availability of computing power has had an enormous impact on the classical fields of direct and inverse scattering. The study of inverse scattering, in particular, has developed rapidly with the ability to perform computational simulations of scattering processes and led to remarkable advances in a range of applications, from medical imaging and radar to remote sensing and seismic exploration. Point Sources and Multipoles in Inverse Scattering Theory provides a survey of recent developments in inverse acoustic and electromagnetic scattering theory. Focusing on methods developed over the last six years by Colton, Kirsch, and the author, this treatment uses point sources combined with several far-reaching techniques to obtain qualitative reconstruction methods. The author addresses questions of uniqueness, stability, and reconstructions for both two-and three-dimensional problems.With interest in extracting information about an object through scattered waves at an all-ti...

  5. ABSTRACT OF CONTRACTING FOR NON-POINT-SOURCE POLLUTION ABATEMENT

    Olof BYSTROM; Bromley, Daniel W

    1996-01-01

    This paper presents an incentive scheme to control agricultural non-point-source pollution. The analysis is based on a nested agent framework with three parties; farmers, a country's government, and the governments of all countries that affect each other's environmental quality. Unlike previous analysis of incentive schemes to control agricultural pollution, we suggest non-individual contracts between farmers and a regulating authority as a solution to the domestic pollution problem. Our ince...

  6. Atmospheric Verification of Point Source Fossil Fuel CO2 Emissions

    Turnbull, J. C.; Keller, E. D.; Norris, M. W.; Wiltshire, R.; Baisden, W. T.; Brailsford, G. W.; Bromley, T.

    2015-12-01

    Large point sources (electricity generation and large-scale industry) make up roughly one third of all fossil fuel CO2 (CO2ff) emissions. Currently, these emissions are determined from self-reported inventory data, and sometimes from smokestack emissions monitoring, and the uncertainty in emissions from individual power plants is about 20%. We examine the utility of atmospheric 14C measurements combined with atmospheric transport modelling as a tool for independently quantifying point source CO2ff emissions, to both improve the accuracy of the reported emissions and for verification as we move towards a regulatory environment. We use the Kapuni Gas Treatment Facility as a test case. It is located in rural New Zealand with no other significant fossil fuel CO2 sources nearby, and emits CO2ff at ~0.1 Tg carbon per year. We use several different sampling methods to determine the 14C and hence the CO2ff content downwind of the emission source: grab flask samples of whole air; absorption of CO2 into sodium hydroxide integrated over many hours; and plant material which faithfully records the 14C content of assimilated CO2. We use a plume dispersion model to compare the reported emissions with our observed CO2ff mole fractions. We show that the short-term variability in plume dispersion makes it difficult to interpret the grab flask sample results, whereas the variability is averaged out in the integrated samples and we obtain excellent agreement between the reported and observed emissions, indicating that the 14C method can reliably be used to evaluated point source emissions.

  7. Inhomogeneous point kinetics equations and the source contribution

    Inhomogeneous point reactor kinetics equations with one-group of delayed neutrons are solved analytically for linear reactivity insertion as well as for step reactivity insertion in the presence of external neutron source using the prompt jump approximation. The solution is obtained as an infinite series. The methodology is found to be a promising tool for analyzing nuclear reactor kinetics with positive or negative ramp reactivity insertion on a sub-critical or a zero power delayed critical reactor, where the temperature reactivity feedback is negligibly small. To check the consistency and the accuracy of the analytical solution, the results are compared with the numerical solution for different sub-critical and delayed critical states. The comparison is found to be good for all kinds of positive and negative step and ramp reactivity insertions. The analytical solution is arranged into two terms, one as a function of source contribution the other without that. Using the newly rearranged solution, the importance of the source term and the contribution to the error while neglecting source term to the reactor kinetics analysis, can be realized. Contribution to the error is small (less than 0.1%) when the equilibrium power is more than about one megawatt for a medium sized LMFBR. Similarly, the importance of source contribution to the total reactor period as a function of initial equilibrium power is also realized with the newly rearranged analytical solution. The total reactor period is over predicted (larger period in place of smaller period) which is not conservative, if the source contribution is not considered, for considerably small initial equilibrium power. The percentage of error in not considering the source term in period calculation varies as a function of net reactivity and ramp rate. The percentage of error in period determination without considering the source is comparatively high for small ramp rates.

  8. A novel phase noise suppression method for coherent detection by utilizing two adjacent longitudinal modes generated from a supercontinuum multi-wavelength source

    Pan, D; Ke, C J; Zhu, X H; Liu, D M, E-mail: cjke@mail.hust.edu.cn [College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China)

    2011-02-01

    A novel phase noise suppression method for coherent detection is proposed. It uses two adjacent longitudinal modes of a multi-wavelength source, as signal light and coherent light respectively, which are both launched into the optical fiber. And heterodyne synchronous demodulation structure is used in the receiver. The performance of a back-to-back system with 100 Gbit/s NRZ-QPSK utilizing this novel method is investigated by VPI. The simulation results show that phase noise in this coherent detection scheme is suppressed significantly, which is resulted from the correlating phase and fixed frequency spacing of adjacent longitudinal modes.

  9. The Chandra COSMOS Survey, I: Overview and Point Source Catalog

    Elvis, Martin; Vignali, Cristian; Puccetti, Simonetta; Fiore, Fabrizio; Cappelluti, Nico; Aldcroft, T L; Fruscione, Antonella; Zamorani, G; Comastri, Andrea; Brusa, Marcella; Gilli, Roberto; Miyaji, Takamitsu; Koekemoer, Francesco Damiani Anton; Finoguenov, Alexis; Brunner, Hermann; Urry, C M; Silverman, John; Mainieri, Vincenzo; Hasinger, Guenther; Griffiths, Richard; Carollo, Marcella; Hao, Heng; Guzzo, Luigi; Blain, Andrew; Calzetti, Daniela; Carilli, C; Capak, Peter; Ettori, Stefano; Fabbiano, Giuseppina; Impey, Chris; Lilly, Simon; Mobasher, Bahram; Rich, Michael; Salvato, Mara; Sanders, D B; Schinnerer, Eva; Scoville, N; Shopbell, Patrick; Taylor, James E; Taniguchi, Yoshiaki; Volonteri, Marta

    2009-01-01

    The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h, +02deg) with an effective exposure of ~160ksec, and an outer 0.4sq.deg. area with an effective exposure of ~80ksec. The limiting source detection depths are 1.9e-16 erg cm^-2 s$-1 in the Soft (0.5-2 keV) band, 7.3e^-16 erg cm^-2 s^-1 in the Hard (2-10 keV) band, and 5.7e^-16 erg cm^-2 s^-1 in the Full (0.5-10 keV) band. Here we describe the strategy, design and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2e^-5 (1655 in the Full, 1340 in the Soft, and 1017 in the Hard bands). By using a grid of 36 heavily (~50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (to 12%) exposure across the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower flux limit. The widely different PSFs obtained in each exposure at each point in the field r...

  10. WMAP extragalactic point sources as potential Space VLBI calibrators

    Gereb, K; 10.1016/j.asr.2011.03.038

    2011-01-01

    The point source list of the Wilkinson Microwave Anisotropy Probe (WMAP) is a uniform, all-sky catalogue of bright sources with flux density measurements at high (up to 94 GHz) radio frequencies. We investigated the five-year WMAP list to compile a new catalogue of bright and compact extragalactic radio sources to be potentially studied with Very Long Baseline Interferometry at millimeter wavelengths (mm-VLBI) and Space VLBI (SVLBI). After comparing the WMAP data with the existing mm-VLBI catalogues, we sorted out the yet unexplored sources. Using the 41, 61 and 94 GHz WMAP flux densities, we calculated the spectral indices. By collecting optical identifications, lower-frequency radio flux densities and VLBI images from the literature, we created a list of objects which have not been investigated with VLBI at 86 GHz before. With total flux density at least 1 Jy and declination above -40 degree, we found 37 suitable new targets. It is a nearly 25% addition to the known mm-VLBI sources. Such objects are also po...

  11. The Chandra COSMOS Legacy survey: overview and point source catalog

    Civano, F; Comastri, A; Urry, M C; Elvis, M; Cappelluti, N; Puccetti, S; Brusa, M; Zamorani, G; Hasinger, G; Aldcroft, T; Alexander, D M; Allevato, V; Brunner, H; Capak, P; Finoguenov, A; Fiore, F; Fruscione, A; Gilli, R; Glotfelty, K; Griffiths, R E; Hao, H; Harrison, F A; Jahnke, K; Kartaltepe, J; Karim, A; LaMassa, S M; Lanzuisi, G; Miyaji, T; Ranalli, P; Salvato, M; Sargent, M; Scoville, N J; Schawinski, K; Schinnerer, E; Silverman, J; Smolcic, V; Stern, D; Toft, S; Trakhenbrot, B; Treister, E; Vignali, C

    2016-01-01

    The COSMOS-Legacy survey is a 4.6 Ms Chandra program that has imaged 2.2 deg$^2$ of the COSMOS field with an effective exposure of $\\simeq$160 ks over the central 1.5 deg$^2$ and of $\\simeq$80 ks in the remaining area. The survey is the combination of 56 new observations, obtained as an X-ray Visionary Project, with the previous C-COSMOS survey. We describe the reduction and analysis of the new observations and the properties of 2273 point sources detected above a spurious probability of 2$\\times 10^{-5}$. We also present the updated properties of the C-COSMOS sources detected in the new data. The whole survey includes 4016 point sources (3814, 2920 and 2440 in the full, soft and hard band). The limiting depths are 2.2 $\\times$ 10$^{-16}$, 1.5 $\\times$ 10$^{-15}$ and 8.9$\\times$ 10$^{-16}$ ${\\rm erg~cm}^{-2}~{\\rm s}^{-1}$ in the 0.5-2, 2-10 and 0.5-10 keV bands, respectively. The observed fraction of obscured AGN with column density $> 10^{22}$ cm$^{-2}$ from the hardness ratio (HR) is $\\sim$50$^{+17}_{-16}$%...

  12. Limitation of point source pesticide pollution: results of bioremediation system.

    Spanoghe, P; Maes, A; Steurbaut, W

    2004-01-01

    Groundwater and surface water is at risk of contamination from the use of some agricultural pesticides. In many circumstances pesticide contamination of water resources is more likely to result from point sources than from diffuse sources following approved application to crops in the field. Such point sources include areas on farms where pesticides are handled, filled into sprayers or where sprayers are washed down. To overcome this way of contamination different kind of bio-remediation systems are nowadays in development. In Flanders, Belgium two pilot plants of bioremediation systems for the in situ retention and/or degradation of pesticides were installed. Both systems were based on the Phytobac concept, a watertight excavation filled with straw, peat, compost and soil. The channel was made in the bottom from plastic foil. All kinds of spray rests were captured by the phytobacs. This study focuses on what level pesticides leach, bio-degrade or are retained by the filling of the phytobac. The soil-properties of the filling were investigated. Pesticide tracers were added for monitoring to both phytobacs. Soil and water samples were taken during one year. Pesticides are retained at least for one month by the filling of the phytobac. Almost no pesticide leached out. In winter hardly any pesticide degradation was observed in the filling of the phytobac. In summer no detectable pesticides were still left in the phytobacs. PMID:15756863

  13. Controlling Non-Point Source Pollution in Australian Agricultural Systems

    C. GOURLEY; A. RIDLEY

    2005-01-01

    The Australian farming sector is continuing to intensify, particularly within 300 km of the east and southern coastlines.In the future there will be fewer and larger farms, which will use more fertilizer, support more stock, grow more monoculture crops, and utilise more marginal soils. This is likely to increase the major environmental impacts of soil degradation, salt,nutrient and sediment contamination of waterways, and greenhouse gas emissions. Australian national water policy continues to focus on land, stream and groundwater salinity issues, although there is now a greater recognition of the importance of nitrogen and phosphorus losses from agriculture. The general philosophy of policy for dealing with nonpoint source pollution has been towards a voluntary rather than regulatory approach, with state and national governments supporting a range of programs to encourage sustainable agricultural practices. A catchment (watershed) based approach,through the use of integrated catchment management plans, is the primary way that non-point source pollution is addressed at the farm and local level. At an industry level, cotton, grains, meat, sugarcane and dairy amongst others, as well as the Australian fertilizer industry, have responded to non-point source issues by investing in research and development, and developing codes of practice aimed at abating these environmental impacts. Understanding the economic, social, political and cultural contexts of farming as well as the environmental impacts of agriculture are very important in determining the appropriateness of policy responses for Australian farming systems.

  14. A search for point sources of EeV photons

    Aab, A; Aglietta, M; Ahlers, M; Ahn, E J; Samarai, I Al; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muñiz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Badescu, A M; Barber, K B; Bäuml, J; Baus, C; Beatty, J J; Becker, K H; Bellido, J A; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chavez, A G; Cheng, S H; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Collica, L; Coluccia, M R; Conceição, R; Contreras, F; Cooper, M J; Coutu, S; Covault, C E; Criss, A; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; de Jong, S J; Neto, J R T de Mello; De Mitri, I; de Oliveira, J; de Souza, V; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Di Matteo, A; Diaz, J C; Castro, M L Díaz; Diep, P N; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Hasankiadeh, Q Dorosti; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Erfani, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filipčič, A; Fox, B D; Fratu, O; Fröhlich, U; Fuchs, B; Fuji, T; Gaior, R; García, B; Roca, S T Garcia; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Bravo, A Gascon; Gate, F; Gemmeke, H; Ghia, P L; Giaccari, U; Giammarchi, M; Giller, M; Glaser, C; Glass, H; Albarracin, F Gomez; Berisso, M Gómez; Vitale, P F Gómez; Gonçalves, P; Gonzalez, J G; Gookin, B; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guardincerri, Y; Guarino, F; Guedes, G P; Hansen, P; Harari, D; Harrison, T A; Hartmann, S; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Heimann, P; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Holt, E; Homola, P; Hörandel, J R; Horvath, P; Hrabovský, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Islo, K; Jandt, I; Jansen, S; Jarne, C; Josebachuili, M; Kääpä, A; Kambeitz, O; Kampert, K H; Kasper, P; Katkov, I; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; La Rosa, G; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Leão, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Malacari, M; Maldera, S; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mariş, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Martraire, D; Meza, J J Masías; Mathes, H J; Mathys, S; Matthews, A J; Matthews, J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Messina, S; Meyhandan, R; Mićanović, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morello, C; Moreno, J C; Mostafá, M; Moura, C A; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novotny, V; Nožka, L; Ochilo, L; Olinto, A; Oliveira, M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Papenbreer, P; Parente, G; Parra, A; Pastor, S; Paul, T; Pech, M; Pękala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Peters, C; Petrera, S; Petrolini, A; Petrov, Y; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Porcelli, A; Porowski, C; Privitera, P; Prouza, M; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; Roberts, J; de Carvalho, W Rodrigues; Cabo, I Rodriguez; Fernandez, G Rodriguez; Rojo, J Rodriguez; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Roulet, E; Rovero, A C; Rühle, C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Greus, F Salesa; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Scholten, O; Schoorlemmer, H; Schovánek, P; Schulz, A; Schulz, J; Sciutto, S J; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Sima, O; Śmiałkowski, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Squartini, R; Srivastava, Y N; Stanič, S; Stapleton, J; Stasielak, J; Stephan, M; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Taborda, O A; Tapia, A; Tartare, M; Thao, N T; Theodoro, V M; Tiffenberg, J; Timmermans, C; Peixoto, C J Todero; Toma, G; Tomankova, L; Tomé, B; Tonachini, A; Elipe, G Torralba; Machado, D Torres; Travnicek, P; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; van Aar, G; Berg, A M van den; van Velzen, S; van Vliet, A; Varela, E; Cárdenas, B Vargas; Varner, G; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Vlcek, B; Vorobiov, S; Wahlberg, H; Wainberg, O; Walz, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Werner, F; Whelan, B J; Widom, A; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Wittkowski, D; Wundheiler, B; Wykes, S; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Zhou, J; Zhu, Y; Silva, M Zimbres; Ziolkowski, M

    2014-01-01

    Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85{\\deg} to +20{\\deg}, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.

  15. Transition of Benthic Nutrient Sources after Engineered Levee Breaches Adjacent to Upper Klamath and Agency Lakes, Oregon

    Kuwabara, J. S.; Topping, B. R.; Carter, J. L.; Parchaso, F.; Cameron, J. M.; Asbill, J. R.; Carlson, R. A.; Fend, S. V.; Engelstad, A. C.

    2010-12-01

    Nonmetallic pore-water profilers were deployed during four sampling trips between November 2007 and July 2009 after engineered levee breaches on 30 October 2007, hydrologically reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. Centimeter-scale measurements of the vertical dissolved-nutrient concentration gradients from the profilers served as the basis for diffusive-flux determinations. Wetland areas undergoing restoration and those being used for water storage around these lakes function very differently than nearby established wetlands within the Upper Klamath National Wildlife Refuge. Consistent with previous results from Upper Klamath Lake, benthic flux of soluble reactive phosphorus (SRP) in the wetlands was consistently positive, and when areally and seasonally averaged over the 13 km2 newly restored wetlands, an SRP flux to the overlying water column (~87,000 kg over the 3-month cyanophyte bloom of Aphanizomenon flos-aquae (AFA)) exceeded the magnitude of riverine inputs (42,000 kg for that season). SRP benthic flux at a site within the restored wetland area ~0.5 km from the breach was elevated relative to all other lake and wetland sites (including another wetland site sampling period, generating a toxicological concern for endangered fish populations at elevated summer pH. Soluble reactive phosphorus (SRP) concentrations were lower than detection limits (sampling trips indicated higher concentrations at the end of the annual AFA bloom relative to its beginning, suggesting a limiting factor or factors other than SRP. Our results indicated that benthic flux of iron and manganese may serve as a significant source of these essential micronutrients to the lake water column. However, for other trace metals, including those that could retard algal growth (for example, dissolved copper and zinc), water-column and porewater concentrations were low and relatively constant across the sediment-water interface. The lake and wetland

  16. Rainfall Deduction Method for Estimating Non-Point Source Pollution Load for Watershed

    Ming CAI; Li, Huai-en; KAWAKAMI, Yoji

    2004-01-01

    The water pollution can be divided into point source pollution (PSP) and non-point source pollution (NSP). Since the point source pollution has been controlled, the non-point source pollution is becoming the main pollution source. The prediction of NSP load is being increasingly important in water pollution controlling and planning in watershed. Considering the monitoring data shortage of NPS in China, a practical estimation method of non-point source pollution load --- rainfall deduction met...

  17. Using Soluble Reactive Phosphorus and Ammonia to Identify Point Source Discharge from Large Livestock Facilities

    Borrello, M. C.; Scribner, M.; Chessin, K.

    2013-12-01

    A growing body of research draws attention to the negative environmental impacts on surface water from large livestock facilities. These impacts are mostly in the form of excessive nutrient loading resulting in significantly decreased oxygen levels. Over-application of animal waste on fields as well as direct discharge into surface water from facilities themselves has been identified as the main contributor to the development of hypoxic zones in Lake Erie, Chesapeake Bay and the Gulf of Mexico. Some regulators claim enforcement of water quality laws is problematic because of the nature and pervasiveness of non-point source impacts. Any direct discharge by a facility is a violation of permits governed by the Clean Water Act, unless the facility has special dispensation for discharge. Previous research by the principal author and others has shown runoff and underdrain transport are the main mechanisms by which nutrients enter surface water. This study utilized previous work to determine if the effects of non-point source discharge can be distinguished from direct (point-source) discharge using simple nutrient analysis and dissolved oxygen (DO) parameters. Nutrient and DO parameters were measured from three sites: 1. A stream adjacent to a field receiving manure, upstream of a large livestock facility with a history of direct discharge, 2. The same stream downstream of the facility and 3. A stream in an area relatively unimpacted by large-scale agriculture (control site). Results show that calculating a simple Pearson correlation coefficient (r) of soluble reactive phosphorus (SRP) and ammonia over time as well as temperature and DO, distinguishes non-point source from point source discharge into surface water. The r value for SRP and ammonia for the upstream site was 0.01 while the r value for the downstream site was 0.92. The control site had an r value of 0.20. Likewise, r values were calculated on temperature and DO for each site. High negative correlations

  18. Low-energy point source searches with IceCube

    Euler Sebastian

    2016-01-01

    Full Text Available Due to the overwhelming background of atmospheric muons, the traditional IceCube point source search in the Southern Hemisphere is mainly sensitive to neutrinos with energies above 100TeV. A new approach focuses on events starting inside the instrumented volume. By utilizing different veto techniques we are able to significantly reduce the energy threshold and can now for the first time explore the entire Southern Hemisphere at neutrino energies as low as 100GeV. We present the results of two analyses targeting slightly different energy ranges. Both use one year of data taken with the completed IceCube detector in 2011/12.

  19. Polarized positron source with a Compton multiple interaction point line

    Chaikovska, I; Dadoun, O; Lepercq, P; Variola, A

    2014-01-01

    Positron sources are critical components of the future linear collider projects. This is essentially due to the high luminosity required, orders of magnitude higher than existing ones. In addition, polarization of the positron beam rather expands the physics research potential of the machine. In this framework, the Compton sources for polarized positron production are taken into account where the high energy gamma rays are produced by the Compton scattering and subsequently converted into the polarized electron-positron pairs in a target-converter. The Compton multiple Interaction Point (IP) line is proposed as one of the solutions to increase the number of the positrons produced. The gamma ray production with the Compton multiple IP line is simulated and used for polarized positron generation. Later, a capture section based on an adiabatic matching device (AMD) followed by a pre-injector linac is simulated to capture and accelerate the positron beam.

  20. Reducing non-point source pollution with enhancing infiltration

    MU Huan-zhen; ZHENG Tao; HUANG Yan-chu; ZHANG Chun-ping; LIU Chen

    2006-01-01

    The rainfall system was set up on a slope land, which was used with some materials to enhance soil infiltration. The results showed that it was effective to enhance the infiltration of rainwater in soil and reduce the pollutants of surface runoff. After the soil meliorated by the lignin polymer and zeolite, runoff was delayed about 10 min and reduced by 44.40%-50.00%, synchronously, the pollutant loads, such as total suspended solids (TSS), chemical oxygen demand by ditromate (CODCr), total nitroger (TN) and total phosphorus (TP), were reduced on averages by 44.58%, 37.80%, 51.62% and 44.11%, respectively. It is an available technique to control the pollution of non-point source from sources.

  1. On the point source approximation of nearby cosmic-ray sources

    Thoudam, Satyendra

    2011-01-01

    In this paper, we check in detail the validity of the widely adopted point source approximation for nearby cosmic-ray (CR) sources. Under an energy independent escape model for CRs from the sources, we show that for young nearby sources, the point source approximation breaks down at lower energies and the CR spectrum depends on the size and the morphology of the source. When applied to the nearby supernova remnants (SNRs), we find that the approximation breaks down for some of the individual remnants like the Vela, but interestingly it still holds good for their combined total spectrum at the Earth. Moreover, we also find that the results obtained under this simple approximation are quite different from those calculated under an energy dependent escape model which is favored by diffusive shock acceleration models inside SNRs. Our study suggests that if SNRs are the main sources of CRs in our Galaxy, then the commonly adopted point source model (with an energy independent escape scenario) appears flawed for CR...

  2. The Chandra Cosmos Legacy Survey: Overview and Point Source Catalog

    Civano, F.; Marchesi, S.; Comastri, A.; Urry, M. C.; Elvis, M.; Cappelluti, N.; Puccetti, S.; Brusa, M.; Zamorani, G.; Hasinger, G.; Aldcroft, T.; Alexander, D. M.; Allevato, V.; Brunner, H.; Capak, P.; Finoguenov, A.; Fiore, F.; Fruscione, A.; Gilli, R.; Glotfelty, K.; Griffiths, R. E.; Hao, H.; Harrison, F. A.; Jahnke, K.; Kartaltepe, J.; Karim, A.; LaMassa, S. M.; Lanzuisi, G.; Miyaji, T.; Ranalli, P.; Salvato, M.; Sargent, M.; Scoville, N. J.; Schawinski, K.; Schinnerer, E.; Silverman, J.; Smolcic, V.; Stern, D.; Toft, S.; Trakhtenbrot, B.; Treister, E.; Vignali, C.

    2016-03-01

    The COSMOS-Legacy survey is a 4.6 Ms Chandra program that has imaged 2.2 deg2 of the COSMOS field with an effective exposure of ≃ 160 ks over the central 1.5 deg2 and of ≃ 80 ks in the remaining area. The survey is the combination of 56 new observations obtained as an X-ray Visionary Project with the previous C-COSMOS survey. We describe the reduction and analysis of the new observations and the properties of 2273 point sources detected above a spurious probability of 2 × 10-5. We also present the updated properties of the C-COSMOS sources detected in the new data. The whole survey includes 4016 point sources (3814, 2920 and 2440 in the full, soft, and hard band). The limiting depths are 2.2 × 10-16, 1.5 × 10-15, and 8.9 × 10-16 {\\text{erg cm}}-2 {{{s}}}-1 in the 0.5-2, 2-10, and 0.5-10 keV bands, respectively. The observed fraction of obscured active galactic nuclei with a column density >1022 cm-2 from the hardness ratio (HR) is ˜50{}-16+17%. Given the large sample we compute source number counts in the hard and soft bands, significantly reducing the uncertainties of 5%-10%. For the first time we compute number counts for obscured (HR > -0.2) and unobscured (HR Legacy area is three times larger than surveys at similar depths and its depth is three times fainter than surveys covering similar areas. The area-flux region occupied by COSMOS-Legacy is likely to remain unsurpassed for years to come.

  3. Investigating the usage of point spread functions in point source and microsphere localization

    Chao, Jerry; Ram, Sripad; Ward, E. Sally; Ober, Raimund J.

    2016-03-01

    Using a point spread function (PSF) to localize a point-like object, such as a fluorescent molecule or microsphere, represents a common task in single molecule microscopy image data analysis. The localization may differ in purpose depending on the application or experiment, but a unifying theme is the importance of being able to closely recover the true location of the point-like object with high accuracy. We present two simulation studies, both relating to the performance of object localization via the maximum likelihood fitting of a PSF to the object's image. In the first study, we investigate the integration of the PSF over an image pixel, which represents a critical part of the localization algorithm. Specifically, we explore how the fineness of the integration affects how well a point source can be localized, and find the use of too coarse a step size to produce location estimates that are far from the true location, especially when the images are acquired at relatively low magnifications. We also propose a method for selecting an appropriate step size. In the second study, we investigate the suitability of the common practice of using a PSF to localize a microsphere, despite the mismatch between the microsphere's image and the fitted PSF. Using criteria based on the standard errors of the mean and variance, we find the method suitable for microspheres up to 1 μm and 100 nm in diameter, when the localization is performed, respectively, with and without the simultaneous estimation of the width of the PSF.

  4. A Note on the Overall Magnification of a Gravitational Point-Source-Point-Lens System

    Walters, S J

    2015-01-01

    The total magnification due to a point lens has been of particular interest as the theorem that gravitational lensing results in light amplification for all observers appears to contradict the conservation of photon number. This has been discussed several times, and various resolutions have been offered. In this note, we use a kinematic approach to provide a formula for the magnification factor for the primary image accurate to first order and valid for rays leaving the source at any trajectory. We thus determine the magnification over a sphere surrounding the system. A new result found is that while the magnification dips below unity far from the optical axis as noted by others, it returns to unity directly behind the source.

  5. The peak efficiency calibration of volume source using 152Eu point source in computer

    The author describes the method of the peak efficiency calibration of volume source by means of 152Eu point source for HPGe γ spectrometer. The peak efficiency can be computed by Monte Carlo simulation, after inputting parameter of detector. The computation results are in agreement with the experimental results with an error of +-3.8%, with an exception one is about +-7.4%

  6. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    Full Text Available The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of "Substances Requiring Priority Action" published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 μg/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT that estimates the

  7. Discretized energy minimization in a wave guide with point sources

    Propst, G.

    1994-01-01

    An anti-noise problem on a finite time interval is solved by minimization of a quadratic functional on the Hilbert space of square integrable controls. To this end, the one-dimensional wave equation with point sources and pointwise reflecting boundary conditions is decomposed into a system for the two propagating components of waves. Wellposedness of this system is proved for a class of data that includes piecewise linear initial conditions and piecewise constant forcing functions. It is shown that for such data the optimal piecewise constant control is the solution of a sparse linear system. Methods for its computational treatment are presented as well as examples of their applicability. The convergence of discrete approximations to the general optimization problem is demonstrated by finite element methods.

  8. Trans-Z-source and Γ-Z-source neutral-point-clamped inverters

    Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede;

    2015-01-01

    Z-source neutral-point-clamped (NPC) inverters are earlier proposed for obtaining voltage buck-boost and three-level switching simultaneously. Their performances are, however, constrained by a trade-off between their input-to-output gain and modulation ratio. This trade-off can lead to high...

  9. POWER-LAW TEMPLATE FOR INFRARED POINT-SOURCE CLUSTERING

    We perform a combined fit to angular power spectra of unresolved infrared (IR) point sources from the Planck satellite (at 217, 353, 545, and 857 GHz, over angular scales 100 ∼clustl∝l–n with n = 1.25 ± 0.06. While the IR sources are understood to lie at a range of redshifts, with a variety of dust properties, we find that the frequency dependence of the clustering power can be described by the square of a modified blackbody, νβ B(ν, Teff), with a single emissivity index β = 2.20 ± 0.07 and effective temperature Teff = 9.7 K. Our predictions for the clustering amplitude are consistent with existing ACT and South Pole Telescope results at around 150 and 220 GHz, as is our prediction for the effective dust spectral index, which we find to be α150-220 = 3.68 ± 0.07 between 150 and 220 GHz. Our constraints on the clustering shape and frequency dependence can be used to model the IR clustering as a contaminant in cosmic microwave background anisotropy measurements. The combined Planck and BLAST data also rule out a linear bias clustering model.

  10. Power-Law Template for Infrared Point-Source Clustering

    Addison, Graeme E; Dunkley, Joanna; Hajian, Amir; Viero, Marco; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Halpern, Mark; Hincks, Adam D; Hlozek, Renee; Marriage, Tobias A.; Moodley, Kavilan; Page, Lyman A.; Reese, Erik D.; Scott, Douglas; Spergel, David N.; Staggs, Suzanne T.; Wollack, Edward

    2012-01-01

    We perform a combined fit to angular power spectra of unresolved infrared (IR) point sources from the Planck satellite (at 217, 353, 545, and 857 GHz, over angular scales 100 approx sub l) varies as l (sub -n) with n = 1.25 +/- 0.06. While the IR sources are understood to lie at a range of redshifts, with a variety of dust properties, we find that the frequency dependence of the clustering power can be described by the square of a modified blackbody, ?(sup Beta)B(?, T(sub eff) ), with a single emissivity index Beta = 2.20 +/- 0.07 and effective temperature T(sub eff) = 9.7 K. Our predictions for the clustering amplitude are consistent with existing ACT and South Pole Telescope results at around 150 and 220 GHz, as is our prediction for the effective dust spectral index, which we find to be alpha(sub 150-220) = 3.68 +/- 0.07 between 150 and 220 GHz. Our constraints on the clustering shape and frequency dependence can be used to model the IR clustering as a contaminant in cosmic microwave background anisotropy measurements. The combined Planck and BLAST data also rule out a linear bias clustering model.

  11. Power-Law Template for IR Point Source Clustering

    Addison, Graeme E.; Dunkley, Joanna; Hajian, Amir; Viero, Marco; Bond, J. Richard; Das, Sudeep; Devlin, Mark; Halpern, Mark; Hincks, Adam; Hlozek, Renee; Marriage, Tobias A.; Moodley, Kavilan; Page, Lyman A.; Reese, Erik D.; Scott, Douglass; Spergel, David N.; Staggs,Suzanne T.; Wollack, Edward

    2011-01-01

    We perform a combined fit to angular power spectra of unresolved infrared (IR) point sources from the Planck satellite (at 217,353,545 and 857 GHz, over angular scales 100 law of the form C_l\\propto I(sup -n) with n = 1.25 +/- 0.06. While the IR sources are understood to lie at a range of redshifts, with a variety of dust properties, we find that the frequency dependence of the clustering power can be described by the square of a modified blackbody, nu(sup beta) B(nu,T_eff), with a single emissivity index beta = 2.20 +/- 0.07 and effective temperature T_eff= 9.7 K. Our predictions for the clustering amplitude are consistent with existing ACT and South Pole Telescope results at around 150 and 220 GHz, as is our prediction for the effective dust spectral index, which we find to be alpha_150-220 = 3.68 +/- 0.07 between 150 and 220 GHz. Our constraints on the clustering shape and frequency dependence can be used to model the IR clustering as a contaminant in Cosmic Microwave Background anisotropy measurements. The combined Planck and BLAST data also rule out a linear bias clustering model.

  12. POWER-LAW TEMPLATE FOR INFRARED POINT-SOURCE CLUSTERING

    Addison, Graeme E.; Dunkley, Joanna [Sub-department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Hajian, Amir; Das, Sudeep; Hincks, Adam D.; Page, Lyman A.; Staggs, Suzanne T. [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States); Viero, Marco [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Bond, J. Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Devlin, Mark J.; Reese, Erik D. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Halpern, Mark; Scott, Douglas [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada); Hlozek, Renee; Marriage, Tobias A.; Spergel, David N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Moodley, Kavilan [Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban 4041 (South Africa); Wollack, Edward [NASA/Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)

    2012-06-20

    We perform a combined fit to angular power spectra of unresolved infrared (IR) point sources from the Planck satellite (at 217, 353, 545, and 857 GHz, over angular scales 100 {approx}< l {approx}< 2200), the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST; 250, 350, and 500 {mu}m; 1000 {approx}< l {approx}< 9000), and from correlating BLAST and Atacama Cosmology Telescope (ACT; 148 and 218 GHz) maps. We find that the clustered power over the range of angular scales and frequencies considered is well fitted by a simple power law of the form C{sup clust}{sub l}{proportional_to}l{sup -n} with n = 1.25 {+-} 0.06. While the IR sources are understood to lie at a range of redshifts, with a variety of dust properties, we find that the frequency dependence of the clustering power can be described by the square of a modified blackbody, {nu}{sup {beta}} B({nu}, T{sub eff}), with a single emissivity index {beta} = 2.20 {+-} 0.07 and effective temperature T{sub eff} = 9.7 K. Our predictions for the clustering amplitude are consistent with existing ACT and South Pole Telescope results at around 150 and 220 GHz, as is our prediction for the effective dust spectral index, which we find to be {alpha}{sub 150-220} = 3.68 {+-} 0.07 between 150 and 220 GHz. Our constraints on the clustering shape and frequency dependence can be used to model the IR clustering as a contaminant in cosmic microwave background anisotropy measurements. The combined Planck and BLAST data also rule out a linear bias clustering model.

  13. Anthropogenic point-source and non-point-source nitrogen inputs into Huai River basin and their impacts on riverine ammonia-nitrogen flux

    Zhang, W. S.; Swaney, D. P.; Li, X. Y.; Hong, B.; Howarth, R. W.; Ding, S. H.

    2015-07-01

    This study provides a new approach to estimate both anthropogenic non-point-source and point-source nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia-nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our study site is Huai River basin of China, a water-shed with one of the highest levels of N input in the world. Multi-year average (2003-2010) inputs of N to the watershed are 27 200 ± 1100 kg N km-2 yr-1. Non-point sources comprised about 98 % of total N input, and only 2 % of inputs are directly added to the aquatic ecosystem as point sources. Fertilizer application was the largest non-point source of new N to the Huai River basin (69 % of net anthropogenic N inputs), followed by atmospheric deposition (20 %), N fixation in croplands (7 %), and N content of imported food and feed (2 %). High N inputs showed impacts on riverine AN flux: fertilizer application, point-source N input, and atmospheric N deposition were proved as more direct sources to riverine AN flux. Modes of N delivery and losses associated with biological denitrification in rivers, water consumption, interception by dams may influence the extent of export of riverine AN flux from N sources. Our findings highlight the importance of anthropogenic N inputs from both point sources and non-point sources in heavily polluted watersheds, and provide some implications for AN prediction and management.

  14. Trans-Z-source and Γ-Z-source neutral-point-clamped inverters

    Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede; Wang, Peng

    2015-01-01

    Z-source neutral-point-clamped (NPC) inverters are earlier proposed for obtaining voltage buck-boost and three-level switching simultaneously. Their performances are, however, constrained by a trade-off between their input-to-output gain and modulation ratio. This trade-off can lead to high-voltage...... stress across the inverter bridge and poor output voltage spectrum. As alternatives with improved performances, two transformer-based Z-source NPC inverters are proposed, whose gain can be adjusted by varying the transformer turns ratio, and is hence less dependent on the inverter modulation ratio...

  15. High-frequency incremental methods for electromagnetic complex source points

    Canta, Stefano Mihai

    This dissertation advances knowledge in field-based High-Frequency (HF) incremental methods for electromagnetic Complex Source Points (CSP), and its most immediate impact is a significantly faster analysis and design of reflector antennas. HF incremental methods overcome many difficulties encountered in other ray-tracing techniques, mostly when crossing shadow boundaries in the electromagnetic (EM) field predictions. The combination of HF methods with CSPs allows to speed up EM computations. CSPs are obtained by locating real electric or magnetic dipole sources in complex space. EM field patterns are derived through analytical continuation of the geometrical quantities associated with the source position; the continuation provides an exact Maxwellian description of a Gaussian Beam. When CSPs are used as basis functions, they can represent any radiated field pattern. Then, by truncating negligible beams in the direction of observation, computations are sped up compared to a plane- or spherical-wave based expansion. Because of these facts, CSPs can be used with Physical Optics (PO) based HF methods for the efficient analysis of electrically large reflectors. However, PO does not always provide accurate field predictions, especially in regions of greatest shadowing or at grazing incidence. Therefore, I developed a HF Incremental Fringe Formulation (IFF) for CSPs to provide a correction term for PO that, when added to the total PO field, recovers an accurate estimate of the scattered field at the first asymptotic order. In addition, since PO does not have caustic problems, the new fringe asymptotic recovery is free of caustics for any geometrical configuration, too. Moreover, I also introduced a double diffraction formulation for CSPs, using the Incremental Theory of Diffraction, yielding simulation results very close to those obtained with a Method of Moments (MoM) approach. Unlike ray-based methods, no tracing in complex space is necessary, and no caustics are

  16. Development of point source method and its practical significance

    Bidya Sagar PANI

    2009-01-01

    The advantages of Reichardt's hypothesis in dealing with single and multiple circular jets in a stagnant environment are highlighted. The stages involved in the development of the point source method, an offshoot of the new hypothesis, are presented. Previous results of experiments on multiple circular jets in a stagnant environment justify the method of superposition. As a prelude to discussion of multiple jets in a co-flowing stream, results on the excess-velocity decay, the growth of the shear layer, and the dilutions for a single jet based on Reichardt's hypothesis are presented. The spreading hypothesis is generalized by introducing a link factor k1 to account for the co-flowing stream. The distribution of excess-momentum flux uAu is shown to be Gaussian in nature. Based on the principle of superposition, the decay of the maximum excess velocity and the dilution are predicted for odd and even numbers of jets in an array. The predictions seem to be in good agreement with observed data.

  17. Point-source imbibition into dry aqueous foams

    Mensire, Rémy; Ault, Jesse T.; Lorenceau, Elise; Stone, Howard A.

    2016-02-01

    We use experiments, modeling and numerics to study the imbibition dynamics from a point source into a homogeneous dry aqueous foam. A distinctive feature of foams compared to solid porous material is that imbibition occurs in the liquid microchannels of the foam called Plateau borders, which have a volume varying in space and time. Dynamics is driven by the capillary pressure and resisted by the viscous and gravity forces in the liquid microchannels. Assuming a constant pressure in the imbibing liquid reservoir, we show that the imbibition front advances and flattens out in time due to gravity, the effect of which is quantified by introducing the Bond number B, which compares the gravitational effects to the capillary pressure using the mean bubble radius as the characteristic length. This evolution describes both miscible and immiscible imbibing liquids. For the latter, we introduce the idea of an effective interfacial tension γ\\textit{eff} to take the oil-water interfacial energy into account. The details of the imbibition process are confirmed by experiments and numerics using foams with tangentially immobile interfaces in the channel-dominated model.

  18. Low energy electron point source microscopy: beyond imaging

    Beyer, Andre; Goelzhaeuser, Armin [Physics of Supramolecular Systems and Surfaces, University of Bielefeld, Postfach 100131, 33501 Bielefeld (Germany)

    2010-09-01

    Low energy electron point source (LEEPS) microscopy has the capability to record in-line holograms at very high magnifications with a fairly simple set-up. After the holograms are numerically reconstructed, structural features with the size of about 2 nm can be resolved. The achievement of an even higher resolution has been predicted. However, a number of obstacles are known to impede the realization of this goal, for example the presence of electric fields around the imaged object, electrostatic charging or radiation induced processes. This topical review gives an overview of the achievements as well as the difficulties in the efforts to shift the resolution limit of LEEPS microscopy towards the atomic level. A special emphasis is laid on the high sensitivity of low energy electrons to electrical fields, which limits the structural determination of the imaged objects. On the other hand, the investigation of the electrical field around objects of known structure is very useful for other tasks and LEEPS microscopy can be extended beyond the task of imaging. The determination of the electrical resistance of individual nanowires can be achieved by a proper analysis of the corresponding LEEPS micrographs. This conductivity imaging may be a very useful application for LEEPS microscopes. (topical review)

  19. Open source wireless access point with cloud user interface

    Blomqvist, Tuomas

    2016-01-01

    Wireless access points exist in almost every home and office. A large installation base of wireless access points has problems concerning security, scalability and usability. Some of these issues arise from the fact that the devices are usually managed and configured by untrained users via an on-device HTTP interface and the manufacturers have no control over them. Centralized management of access points solves some of these problems. A new trend is to move control of embedded devices to...

  20. Mixed convection from a discrete heat source in enclosures with two adjacent moving walls and filled with micropolar nanofluids

    Sameh E. Ahmed

    2016-03-01

    Full Text Available This paper examines numerically the thermal and flow field characteristics of the laminar steady mixed convection flow in a square lid-driven enclosure filled with water-based micropolar nanofluids by using the finite volume method. While a uniform heat source is located on a part of the bottom of the enclosure, both the right and left sidewalls are considered adiabatic together with the remaining parts of the bottom wall. The upper wall is maintained at a relatively low temperature. Both the upper and left sidewalls move at a uniform lid-driven velocity and four different cases of the moving lid ordinations are considered. The fluid inside the enclosure is a water based micropolar nanofluid containing different types of solid spherical nanoparticles: Cu, Ag, Al2O3, and TiO2. Based on the numerical results, the effects of the dominant parameters such as Richardson number, nanofluid type, length and location of the heat source, solid volume fractions, moving lid orientations and dimensionless viscosity are examined. Comparisons with previously numerical works are performed and good agreements between the results are observed. It is found that the average Nusselt number along the heat source decreases as the heat source length increases while it increases when the solid volume fraction increases. Also, the results of the present study indicate that both the local and the average Nusselt numbers along the heat source have the highest value for the fourth case (C4. Moreover, it is observed that both the Richardson number and moving lid ordinations have a significant effect on the flow and thermal fields in the enclosure.

  1. Impact of point source pollution on groundwater quality

    The management of point source pollution (municipal and industrial waste water) is an important item on Brown Agenda confronting urban planners and policy makers. The industrial concerns and households produce enormous amount of waste water, which has to be disposed of through the municipal sewage system. Generally, municipal wastewater management is done on non-scientific lines, resulting in considerable social and economic loss and gradual degradation of the natural resources. The present study highlights that how the poor management practices, lack of infrastructure, and poor disposal system-comprising of mostly open, un-walled or partially lined drains, affect the groundwater quality and render it unfit for human consumption. Satiana Road sludge carrier at Faisalabad city, receiving effluents of about 67 textile units, 4 oil mills, 2 ice factories, 3 laundris and domestic waste water of Peoples Colony No.1, Maqbool Road and Ghulam Rasool Nagar was selected to derive quantitative and qualitative estimates of TDS, Na, Cl and heavy metals namely Fe, Cu and Pb of the waste water and their leaching around the sludge carrier. The measurement of leaching of TDS, Na/sup +/, and Cl/sup -1/ per 1000 m basis in lined section was 818, 550 and 228 tons, respectively. Where as in the unlined section, annual increase of TDS, Na/sup /+, and Cl/sup -/ was 2404,1615 and 669 tons per 1000 m respectively. In case of leaching of metals through the sludge carrier, Cu was at the top with 8.4 tons per annum per 1000 m followed by Fe and Pb with 6.66 and 1.2 tons per annum per 1000 m respectively. The concentration of all the salts/metals studied were higher in groundwater near the sludge carrier which decreased with increase in distance. The groundwater contamination in unlined portions is greater than lined portions, which might be due to higher seepage losses in unlined portions of the sludge carrier (4.9 % per 1000 m) as compared to relatively low seepage losses in lined portion of

  2. Fluorescent Microspheres as Point Sources: A Localization Study

    Chao, Jerry; Lee, Taiyoon; Ward, E Sally; Ober, Raimund J.

    2015-01-01

    The localization of fluorescent microspheres is often employed for drift correction and image registration in single molecule microscopy, and is commonly carried out by fitting a point spread function to the image of the given microsphere. The mismatch between the point spread function and the image of the microsphere, however, calls into question the suitability of this localization approach. To investigate this issue, we subject both simulated and experimental microsphere image data to a ma...

  3. Point-source effects on N and P uptake in a forested and an agricultural Mediterranean streams.

    Merseburger, Gora; Martí, Eugènia; Sabater, Francesc; Ortiz, Jesús D

    2011-02-01

    We examined the effect of point-source inputs from wastewater treatment plants (WWTP) on in-stream uptake of ammonium, nitrate and phosphate and compared it between two streams draining catchments with contrasting land use. The selected streams were La Tordera and Gurri (NE Spain), draining a forest- and an agriculture-dominated catchment, respectively. In each stream, we compared nutrient uptake metrics, estimated from nutrient additions, between two reaches located upstream and downstream of a WWTP input. Measurements were done on 8-9 dates during 2002-2003. In La Tordera, the point-source increased concentrations of all studied nutrients; whereas in Gurri, this effect was less evident. Point-source effects on nutrient uptake differed between the two streams, and among solutes. In La Tordera, uptake lengths (S(w)) of ammonium and phosphate averaged hundreds of meters above the point-source, and increased (i.e., decreased uptake efficiency) 4 and 5 times, respectively, below the point-source. S(w) of nitrate was ≥2km regardless of reach location. In Gurri, S(w) of all studied nutrients was within the km range in the two reaches. In this stream, diffuse nutrient inputs from adjacent fields may overwhelm the local effect of the point-source input. Uptake velocities (v(f)) of the studied nutrients ranged between 10EXP(-6) and 10EXP(-4)m/s in the two streams, and were similar between the two reaches in each stream. However, phosphate v(f) decreased under increasing concentrations following a power function. This trend remained significant when combining our results with those compiled from literature, suggesting the efficiency loss response may be a general trend for phosphate across streams. The relative increases in uptake rates (U) below the point-source were proportional to the relative point-source contribution to downstream nutrient loads, especially for ammonium and nitrate. However, the increases in U were not enough to compensate for the increases in

  4. Sources of dissolved inorganic nitrogen in a coastal lagoon adjacent to a major metropolitan area, Miami Florida (USA)

    Highlights: • A range of biota (algae and sea grasses) shows enriched δ15N close to the coast. • Enriched signals are evident in the particulate and sedimentary organic material. • δ15N signals are correlated with high inputs of dissolved inorganic matter. • The enriched values support the presence of a sewage related component. • The δ15N could arise from the local landfill, injected wastewater, or septic systems. - Abstract: Between 2006 and 2007, a study was carried out to determine the relative importance of natural and anthropogenic input of nitrogen into Biscayne Bay (South Florida, USA) using δ13C and δ15N values of algae, seagrasses, and particulate organic material, δ18O and δ15N of the NO3- and δ13C of the dissolved inorganic carbon. The δ15N values of all components showed a strong east to west gradient approaching more positive values (+7 to +10‰) close to the land-sea interface. The nitrogen could have emanated from the local waste water treatment plant, septic systems within the region, or nitrogen which had been affected by denitrification and leached from the local landfill, wastewater which had been injected into the Floridan aquifer and leaked back to the surface, and/or some other as yet unidentified source. The measured NO3- δ15N and δ18O values indicated that the dissolved nitrate originated from anthropogenic sources and was fractionated during assimilation

  5. LAT 2-year Point Source Catalog Aperture Photometry Lightcurves

    National Aeronautics and Space Administration — Due to a glitch in the analysis pipeline there are apparent increases in flux around MJD 56810 for many sources. These increases are not real and should be...

  6. LAT 2-year Point Source Catalog Aperture Photometry Lightcurves Flares

    National Aeronautics and Space Administration — Due to a glitch in the analysis pipeline there are apparent increases in flux around MJD 56810 for many sources. These increases are not real and should be...

  7. High-frequency radio polarization measurements of WMAP point sources

    Jackson, N; Battye, R A; Gabuzda, D; Taylor, A C

    2009-01-01

    We present polarization measurements at 8.4, 22, and 43 GHz made with the VLA of a complete sample of extragalactic sources stronger than 1 Jy in the 5-year WMAP catalogue and with declinations north of -34 degrees. The observations were motivated by the need to know the polarization properties of radio sources at frequencies of tens of GHz in order to subtract polarized foregrounds for future sensitive Cosmic Microwave Background (CMB) experiments. The total intensity and polarization measurements are generally consistent with comparable VLA calibration measurements for less-variable sources, and within a similar range to WMAP fluxes for unresolved sources. A further paper will present correlations between measured parameters and derive implications for CMB measurements.

  8. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environm...

  9. OPTIMAL MANAGEMENT OF NON-POINT SOURCE POLLUTION FROM AGRICULTURE: AN APPLICATION OF DYNAMIC PROGRAMMING

    Agricultural non-point source pollution is a major source of water quality impairment. When considering responses to non-point source pollution, several policy options have been considered historically, including reducing inputs (e.g. fertilizers) altering technologies on the landscape (e.g. conserv...

  10. Point Cloud Visualization in AN Open Source 3d Globe

    De La Calle, M.; Gómez-Deck, D.; Koehler, O.; Pulido, F.

    2011-09-01

    During the last years the usage of 3D applications in GIS is becoming more popular. Since the appearance of Google Earth, users are familiarized with 3D environments. On the other hand, nowadays computers with 3D acceleration are common, broadband access is widespread and the public information that can be used in GIS clients that are able to use data from the Internet is constantly increasing. There are currently several libraries suitable for this kind of applications. Based on these facts, and using libraries that are already developed and connected to our own developments, we are working on the implementation of a real 3D GIS with analysis capabilities. Since a 3D GIS such as this can be very interesting for tasks like LiDAR or Laser Scanner point clouds rendering and analysis, special attention is given to get an optimal handling of very large data sets. Glob3 will be a multidimensional GIS in which 3D point clouds could be explored and analysed, even if they are consist of several million points.The latest addition to our visualization libraries is the development of a points cloud server that works regardless of the cloud's size. The server receives and processes petitions from a 3d client (for example glob3, but could be any other, such as one based on WebGL) and delivers the data in the form of pre-processed tiles, depending on the required level of detail.

  11. POINT CLOUD VISUALIZATION IN AN OPEN SOURCE 3D GLOBE

    M. De La Calle

    2012-09-01

    Full Text Available During the last years the usage of 3D applications in GIS is becoming more popular. Since the appearance of Google Earth, users are familiarized with 3D environments. On the other hand, nowadays computers with 3D acceleration are common, broadband access is widespread and the public information that can be used in GIS clients that are able to use data from the Internet is constantly increasing. There are currently several libraries suitable for this kind of applications. Based on these facts, and using libraries that are already developed and connected to our own developments, we are working on the implementation of a real 3D GIS with analysis capabilities. Since a 3D GIS such as this can be very interesting for tasks like LiDAR or Laser Scanner point clouds rendering and analysis, special attention is given to get an optimal handling of very large data sets. Glob3 will be a multidimensional GIS in which 3D point clouds could be explored and analysed, even if they are consist of several million points.The latest addition to our visualization libraries is the development of a points cloud server that works regardless of the cloud's size. The server receives and processes petitions from a 3d client (for example glob3, but could be any other, such as one based on WebGL and delivers the data in the form of pre-processed tiles, depending on the required level of detail.

  12. Analysis of non-point and point source pollution in China: case study in Shima Watershed in Guangdong Province

    Fang, Huaiyang; Lu, Qingshui; Gao, Zhiqiang; Shi, Runhe; Gao, Wei

    2013-09-01

    China economy has been rapidly increased since 1978. Rapid economic growth led to fast growth of fertilizer and pesticide consumption. A significant portion of fertilizers and pesticides entered the water and caused water quality degradation. At the same time, rapid economic growth also caused more and more point source pollution discharge into the water. Eutrophication has become a major threat to the water bodies. Worsening environment problems forced governments to take measures to control water pollution. We extracted land cover from Landsat TM images; calculated point source pollution with export coefficient method; then SWAT model was run to simulate non-point source pollution. We found that the annual TP loads from industry pollution into rivers are 115.0 t in the entire watershed. Average annual TP loads from each sub-basin ranged from 0 to 189.4 ton. Higher TP loads of each basin from livestock and human living mainly occurs in the areas where they are far from large towns or cities and the TP loads from industry are relatively low. Mean annual TP loads that delivered to the streams was 246.4 tons and the highest TP loads occurred in north part of this area, and the lowest TP loads is mainly distributed in middle part. Therefore, point source pollution has much high proportion in this area and governments should take measures to control point source pollution.

  13. Radon concentration in drinking water sources of the region adjacent to a tectonically active Karak Thrust, southern Kohat Plateau, Khyber Pakhtunkhwa, Pakistan

    A total of 84 drinking water samples from tube wells, natural springs, hand pumps and open wells in the region adjacent to a tectonically active Karak Thrust, Pakistan, were analyzed for radon content determination. These samples have a mean, maximum and minimum radon values of 9.4 ± 0.4, 25.1 ± 0.9, and 1.1 ± 0.2 Bq l-1, respectively. This study indicates that 24 % of samples from tube wells, 44 % from springs, and 50 % from hand pumps have radon levels in excess of the EPA recommended maximum contaminant level of 11.1 Bq l-1. The mean annual effective doses of all the samples are lower than the reference level of 0.1 mSv a-1. Drinking water from majority of the sources within the region is generally safe as far as radon related health hazards are concerned with exception of few isolated cases. (author)

  14. Modelling of point and non-point source pollution of nitrate with SWAT in the river Dill, Germany

    T. Pohlert

    2005-01-01

    Full Text Available We used the Soil and Water Assessment Tool (SWAT to simulate point and non-point source pollution of nitrate in a mesoscale mountainous catchment. The results show that the model efficiency for daily discharge is 0.81 for the calibration period (November 1990 to December 1993 and 0.56 for the validation period (April 2000 to January 2003. The model efficiency for monthly nitrate load is 0.66 and 0.77 for the calibration period (April 2000 to March 2002 and validation period (April 2002 to January 2003, respectively. However, the model efficiency for daily loads is low (0.15, which cannot only be attributed to the quality of input data of point source effluents. An analysis of the internal fluxes and cycles of nitrogen pointed out considerable weaknesses in the models conceptualisation of the nitrogen modules which will be improved in future research.

  15. Lowering IceCube's Energy Threshold for Point Source Searches in the Southern Sky

    Aartsen, M G; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Ahrens, M; Altmann, D; Andeen, K; Anderson, T; Ansseau, I; Anton, G; Archinger, M; Arguelles, C; Arlen, T C; Auffenberg, J; Axani, S; Bai, X; Barwick, S W; Baum, V; Bay, R; Beatty, J J; Tjus, J Becker; Becker, K -H; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blot, S; Boersma, D J; Bohm, C; Börner, M; Bos, F; Bose, D; Böser, S; Botner, O; Braun, J; Brayeur, L; Bretz, H -P; Burgman, A; Buzinsky, N; Casey, J; Casier, M; Cheung, E; Chirkin, D; Christov, A; Clark, K; Classen, L; Coenders, S; Collin, G H; Conrad, J M; Cowen, D F; Silva, A H Cruz; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; Rosendo, E del Pino; Dembinski, H; De Ridder, S; Desiati, P; de Vries, K D; de Wasseige, G; de With, M; DeYoung, T; Díaz-Vélez, J C; di Lorenzo, V; Dujmovic, H; Dumm, J P; Dunkman, M; Eberhardt, B; Ehrhardt, T; Eichmann, B; Euler, S; Evenson, P A; Fahey, S; Fazely, A R; Feintzeig, J; Felde, J; Filimonov, K; Finley, C; Flis, S; Fösig, C -C; Fuchs, T; Gaisser, T K; Gaior, R; Gallagher, J; Gerhardt, L; Ghorbani, K; Gladstone, L; Glagla, M; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Góra, D; Grant, D; Griffith, Z; Ha, C; Haack, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hansen, E; Hansmann, B; Hansmann, T; Hanson, K; Hebecker, D; Heereman, D; Helbing, K; Hellauer, R; Hickford, S; Hignight, J; Hill, G C; Hoffman, K D; Hoffmann, R; Holzapfel, K; Homeier, A; Hoshina, K; Huang, F; Huber, M; Huelsnitz, W; Hultqvist, K; In, S; Ishihara, A; Jacobi, E; Japaridze, G S; Jeong, M; Jero, K; Jones, B J P; Jurkovic, M; Kappes, A; Karg, T; Karle, A; Katz, U; Kauer, M; Keivani, A; Kelley, J L; Kemp, J; Kheirandish, A; Kim, M; Kintscher, T; Kiryluk, J; Klein, S R; Kohnen, G; Koirala, R; Kolanoski, H; Konietz, R; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krings, K; Kroll, M; Krückl, G; Krüger, C; Kunnen, J; Kunwar, S; Kurahashi, N; Kuwabara, T; Labare, M; Lanfranchi, J L; Larson, M J; Lennarz, D; Lesiak-Bzdak, M; Leuermann, M; Leuner, J; Lu, L; Lünemann, J; Madsen, J; Maggi, G; Mahn, K B M; Mancina, S; Mandelartz, M; Maruyama, R; Mase, K; Matis, H S; Maunu, R; McNally, F; Meagher, K; Medici, M; Meier, M; Meli, A; Menne, T; Merino, G; Meures, T; Miarecki, S; Middell, E; Mohrmann, L; Montaruli, T; Moulai, M; Nahnhauer, R; Naumann, U; Neer, G; Niederhausen, H; Nowicki, S C; Nygren, D R; Pollmann, A Obertacke; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Pandya, H; Pankova, D V; Penek, Ö; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Quinnan, M; Raab, C; Rädel, L; Rameez, M; Rawlins, K; Reimann, R; Relich, M; Resconi, E; Rhode, W; Richman, M; Riedel, B; Robertson, S; Rongen, M; Rott, C; Ruhe, T; Ryckbosch, D; Rysewyk, D; Sabbatini, L; Sandrock, A; Sandroos, J; Sarkar, S; Satalecka, K; Schimp, M; Schlunder, P; Schmidt, T; Schoenen, S; Schöneberg, S; Schönwald, A; Schumacher, L; Seckel, D; Seunarine, S; Soldin, D; Song, M; Spiczak, G M; Spiering, C; Stahlberg, M; Stamatikos, M; Stanev, T; Stasik, A; Steuer, A; Stezelberger, T; Stokstad, R G; Stößl, A; Ström, R; Strotjohann, N L; Sullivan, G W; Sutherland, M; Taavola, H; Taboada, I; Tatar, J; Ter-Antonyan, S; Terliuk, A; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Toscano, S; Tosi, D; Tselengidou, M; Turcati, A; Unger, E; Usner, M; Vallecorsa, S; Vandenbroucke, J; van Eijndhoven, N; Vanheule, S; van Rossem, M; van Santen, J; Veenkamp, J; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Wallace, A; Wallraff, M; Wandkowsky, N; Weaver, Ch; Wendt, C; Westerhoff, S; Whelan, B J; Wickmann, S; Wiebe, K; Wiebusch, C H; Wille, L; Williams, D R; Wills, L; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Xu, Y; Yanez, J P; Yodh, G; Yoshida, S; Zoll, M

    2016-01-01

    Observation of a point source of astrophysical neutrinos would be a "smoking gun" signature of a cosmic-ray accelerator. While IceCube has recently discovered a diffuse flux of astrophysical neutrinos, no localized point source has been observed. Previous IceCube searches for point sources in the southern sky were restricted by either an energy threshold above a few hundred TeV or poor neutrino angular resolution. Here we present a search for southern sky point sources with greatly improved sensitivities to neutrinos with energies below 100 TeV. By selecting charged-current $\

  16. The Roles of Countrywomen in Controlling Non-point Source Pollution

    Jiang Dongmei; Zhou Yuanfang; Lu Genfa

    2006-01-01

    The main causes of non-point source pollution in Taihu Lake are the improper ways of crop production, animal husbandry, and daily runoff. The paper discusses the relationship between countrywomen and non-point source pollution control by 731 questionnaires in Weidu village and 466 questionnaires in Dapu Town. The roles of countrywomen have changed in families and they have close relationship with non-point source pollution. Furthermore, we discuss the possibility and methods of organizing countrywomen in non-point source pollution control.

  17. Comparing stochastic point-source and finite-source ground-motion simulations: SMSIM and EXSIM

    Boore, D.M.

    2009-01-01

    Comparisons of ground motions from two widely used point-source and finite-source ground-motion simulation programs (SMSIM and EXSIM) show that the following simple modifications in EXSIM will produce agreement in the motions from a small earthquake at a large distance for the two programs: (1) base the scaling of high frequencies on the integral of the squared Fourier acceleration spectrum; (2) do not truncate the time series from each subfault; (3) use the inverse of the subfault corner frequency for the duration of motions from each subfault; and (4) use a filter function to boost spectral amplitudes at frequencies near and less than the subfault corner frequencies. In addition, for SMSIM an effective distance is defined that accounts for geometrical spreading and anelastic attenuation from various parts of a finite fault. With these modifications, the Fourier and response spectra from SMSIM and EXSIM are similar to one another, even close to a large earthquake (M 7), when the motions are averaged over a random distribution of hypocenters. The modifications to EXSIM remove most of the differences in the Fourier spectra from simulations using pulsing and static subfaults; they also essentially eliminate any dependence of the EXSIM simulations on the number of subfaults. Simulations with the revised programs suggest that the results of Atkinson and Boore (2006), computed using an average stress parameter of 140 bars and the original version of EXSIM, are consistent with the revised EXSIM with a stress parameter near 250 bars.

  18. GALEX Catalog of UV Point Sources in M33

    Mudd, Dale

    2014-01-01

    The hottest stars ($>$10,000 K), and by extension typically the most massive ones, are those that will be prevalent in the ultraviolet (UV) portion of the electromagnetic spectrum, and we expect numerous B, O, and Wolf-Rayet stars to be bright in UV data. In this paper, we update the previous UV catalog of M33, created using the Ultraviolet Imaging Telescope (UIT), using data from the Galaxy Evolution Explorer (GALEX). We utilize PSF photometry to better handle the crowded regions in the galaxy, and benefit from GALEX's increased sensitivity compared to UIT. We match our detections with data from the Local Group Galaxies Survey (LGGS) to create a catalog with photometry spanning from the far-UV through the optical for a final list of 24738 sources. All of these sources have far-UV (FUV; 1516A), near-UV (NUV; 2267A), and V data, and a significant fraction also have U, B, R, and I data as well. We compare these sources to a catalog of known Wolf-Rayet stars in M33 and find that we recover 114 of 206 stars with ...

  19. Point-like sources and the scale of quantum gravity

    We review the General Relativistic model of a (quasi) point-like particle represented by a massive shell of neutral matter which has vanishing total energy in the small-volume limit. We then show that, by assuming a Generalised Uncertainty Principle, which implies the existence of a minimum length of the order of the Planck scale, the total energy instead remains finite and equal to the shell's proper mass both for very heavy and very light particles. This suggests that the quantum structure of space-time might be related to the classical Equivalence Principle and possible implications for the late stage of evaporating black holes are briefly mentioned.

  20. Pulsewidth-modulated 2-source neutral-point-clamped inverter

    Blaabjerg, Frede; Loh, Poh Chang; Gao, Feng;

    2007-01-01

    -shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting its AC output voltage. Through the design of an appropriate pulsewidth-modulation (PWM) algorithm, the two impedance networks can be short......-circuited sequentially (without shooting through the inverter full DC link) for implementing the ldquonearest-three-vectorrdquo modulation principle with minimized harmonic distortion and device commutations per half carrier cycle while performing voltage boosting. With only a slight modification to the inverter PWM...

  1. Autonomous Onboard Point Source Detection by Small Exploration Spacecraft

    Huffman, W.; Thompson, D. R.; Bue, B.; Castillo-Rogez, J.; Boland, J.

    2015-12-01

    Small spacecraft platforms are a promising low-cost approach to accelerate exploration of small bodies, addressing the space community's interest in origin science, planetary resources, and planetary defense. However, they can be challenging platforms for detecting and imaging low brightness targets. Difficulties include constrained bandwidth, which limits the volume of data that can be downlinked; attitude instability, which limits exposure time; small instrument apertures, which reduce sensitivity; and cosmic ray contamination, which creates illusory sources. Mission designers can address all these problems simultaneously by shifting image analysis across the communications gap. Spacecraft can use onboard data analysis to detect sources directly, or downlink parsimonious summary products for detection on the ground. One promising approach is to acquire stacks of short consecutive exposures, and then coregister and coadd them onboard. This work analyzes a coaddition algorithm that is designed to be robust against small spacecraft challenges. We evaluate factors affecting performance, such as attitude control and camera noise systematics, in regimes typical of small spacecraft missions. We motivate the algorithm design by considering its application to NEAScout, a mission representing a new generation of small (sub-50 kg) exploration spacecraft having very small instrument apertures and data rates below 1 kbyte s-1. Here, onboard analysis allows detection and rendezvous with far smaller and fainter objects, dramatically reducing the cost and complexity of primitive bodies exploration.

  2. Electronic Ghost Images Around Soft ROSAT Point Sources

    Lesser, A.; Nousek, J.

    1992-12-01

    The PSPC can not always properly position X-ray events with very low energy. This results in apparent `ghost images', as named in MPE calibration reports. We study this effect using the bright, ultra-soft X-ray source H1504+65 and find that as many as 1/2 of the total events in the lowest two channels are displaced into 8 satellite ghost images. We display the appearance of the images, supply quantitative estimates of the effect, and suggest the kind of scientific inquiries likely to be adversely affected. This research was performed as part of the Penn State Site of the National Science Foundation's Research Experiences for Undergraduates.

  3. High frequency analysis of Helmholtz equations: case of two point sources

    Fouassier, Elise

    2005-01-01

    We derive the high frequency limit of the Helmholtz equation with source term when the source is the sum of two point sources. We study it in terms of Wigner measures (quadratic observables). We prove that the Wigner measure associated with the solution satisfies a Liouville equation with, as source term, the sum of the source terms that would be created by each of the two point sources taken separately. The first step, and main difficulty, in our study is the obtention of uniform estimates o...

  4. Sediment Monitoring and Benthic Faunal Sampling Adjacent to the Barbers Point Ocean Outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900098)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2010. To assess the environmental quality,...

  5. Assessing Urban Non-Point Source pollutants at the Virginia Tech Extended Dry Detention Pond

    Hodges, Kimberly Jean

    1997-01-01

    With a growing concern for the environment and increasing urbanization of rural areas, understanding the characteristics of urban non-point source pollution has become a focus for water quality investigators. Once thought to be a small contributor to the pollution problem, urban non-point sources are now responsible for transporting over 50% of all pollutants into natural waterways. Assessing ...

  6. Identification and Quantification of Non-Point Sources of pollution to Sabarmati River, Ahmedabad

    Monika H. Panchani, Prof. M. J. Pandya

    2013-01-01

    “Whatever can be measure, can be control”.Non-point pollution sources(NPS) account for more than 50% of the total water quality problem, and they are being recognized and investigated nationally and internationally. In many areas, non-point pollution, such as runoff from crop land, urban storm water, strip mining and runoff from construction sites are becoming major water quality problems.To identify and quantify Non-point sources of pollution the selected stud...

  7. Anthropogenic point-source and non-point-source nitrogen inputs into Huai River basin and their impacts on riverine ammonia–nitrogen flux

    W. S. Zhang; D. P. Swaney; Li, X.Y.; Hong, B.; Howarth, R. W.; Ding, S. H.

    2015-01-01

    This study provides a new approach to estimate both anthropogenic non-point-source and point-source nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia–nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our study site is Huai River basin of China, a water–shed with one of the highest levels of N input in the world. Multi-year average (2003–2010) inputs of N to the watershed are 27 ...

  8. Using SPARROW to Model Total Nitrogen Sources, and Transport in Rivers and Streams of California and Adjacent States, U.S.A

    Saleh, D.; Domagalski, J. L.

    2012-12-01

    Sources and factors affecting the transport of total nitrogen are being evaluated for a study area that covers most of California and some areas in Oregon and Nevada, by using the SPARROW model (SPAtially Referenced Regression On Watershed attributes) developed by the U.S. Geological Survey. Mass loads of total nitrogen calculated for monitoring sites at stream gauging stations are regressed against land-use factors affecting nitrogen transport, including fertilizer use, recharge, atmospheric deposition, stream characteristics, and other factors to understand how total nitrogen is transported under average conditions. SPARROW models have been used successfully in other parts of the country to understand how nutrients are transported, and how management strategies can be formulated, such as with Total Maximum Daily Load (TMDL) assessments. Fertilizer use, atmospheric deposition, and climatic data were obtained for 2002, and loads for that year were calculated for monitored streams and point sources (mostly from wastewater treatment plants). The stream loads were calculated by using the adjusted maximum likelihood estimation method (AMLE). River discharge and nitrogen concentrations were de-trended in these calculations in order eliminate the effect of temporal changes on stream load. Effluent discharge information as well as total nitrogen concentrations from point sources were obtained from USEPA databases and from facility records. The model indicates that atmospheric deposition and fertilizer use account for a large percentage of the total nitrogen load in many of the larger watersheds throughout the study area. Point sources, on the other hand, are generally localized around large cities, are considered insignificant sources, and account for a small percentage of the total nitrogen loads throughout the study area.

  9. Optical identifications of IRAS point sources: the Fornax, Hydra I and Coma clusters

    We present optical identifications for 66 IRAS point sources in the region of the Fornax cluster of galaxies, 106 IRAS point sources in the region of the Hydra I cluster of galaxies (Abell 1060) and 59 IRAS point sources in the region of the Coma cluster of galaxies (Abell 1656). Eight other sources in Hydra I do not have optical counterparts and are very probably due to infrared cirrus. Twenty-three (35 per cent) of the Fornax sources are associated with stars and 43 (65 per cent) with galaxies; 48 (42 per cent) of the Hydra I sources are associated with stars and 58 (51 per cent) with galaxies; 18 (31 per cent) of the Coma sources are associated with stars and 41 (69 per cent) with galaxies. The stellar and infrared cirrus surface density is consistent with the galactic latitude of each field. (author)

  10. Optical identifications of IRAS point sources: the Fornax, Hydra I and Coma clusters

    Wang, G.; Leggett, S.K. (Edinburgh Univ. (UK). Dept. of Astronomy); Clowes, R.G.; MacGillivray, H.T. (Royal Observatory, Edinburgh (UK)); Savage, A. (Anglo-Australian Observatory, Coonabarabran, NSW (Australia). UK Schmidt Telescope)

    1991-01-01

    We present optical identifications for 66 IRAS point sources in the region of the Fornax cluster of galaxies, 106 IRAS point sources in the region of the Hydra I cluster of galaxies (Abell 1060) and 59 IRAS point sources in the region of the Coma cluster of galaxies (Abell 1656). Eight other sources in Hydra I do not have optical counterparts and are very probably due to infrared cirrus. Twenty-three (35 per cent) of the Fornax sources are associated with stars and 43 (65 per cent) with galaxies; 48 (42 per cent) of the Hydra I sources are associated with stars and 58 (51 per cent) with galaxies; 18 (31 per cent) of the Coma sources are associated with stars and 41 (69 per cent) with galaxies. The stellar and infrared cirrus surface density is consistent with the galactic latitude of each field. (author).

  11. Search for an Near-IR Counterpart to the Cas A X-ray Point Source

    Kaplan, D.L.; Kulkarni, S. R.; Murray, S. S.

    2001-01-01

    We report deep near-infrared and optical observations of the X-ray point source in the Cassiopeia A supernova remnant, CXO J232327.9+584842. We have identified a J=21.4 +/- 0.3 mag and Ks=20.5 +/- 0.3 mag source within the 1-sigma error circle, but we believe this source is a foreground Pop II star with Teff=2600-2800 K at a distance of ~2 kpc, which could not be the X-ray point source. We do not detect any sources in this direction at the distance of Cas A, and therefore place 3-sigma limits...

  12. Modelling of point and non-point source pollution of nitrate with SWAT in the river Dill, Germany

    Pohlert, T.; J. A. Huisman; L. Breuer; H.-G. Frede

    2005-01-01

    We used the Soil and Water Assessment Tool (SWAT) to simulate point and non-point source pollution of nitrate in a mesoscale mountainous catchment. The results show that the model efficiency for daily discharge is 0.81 for the calibration period (November 1990 to December 1993) and 0.56 for the validation period (April 2000 to January 2003). The model efficiency for monthly nitrate load is 0.66 and 0.77 for the calibration period (April 2000 to March 2002) and validation period (April 2002 to...

  13. Modelling of point and non-point source pollution of nitrate with SWAT in the river Dill, Germany

    Pohlert, T.; Huisman, J.A.; Breuer, L. (Ludwig Maximilian); Frede, H.-G.

    2005-01-01

    International audience We used the Soil and Water Assessment Tool (SWAT) to simulate point and non-point source pollution of nitrate in a mesoscale mountainous catchment. The results show that the model efficiency for daily discharge is 0.81 for the calibration period (November 1990 to December 1993) and 0.56 for the validation period (April 2000 to January 2003). The model efficiency for monthly nitrate load is 0.66 and 0.77 for the calibration period (April 2000 to March 2002) and valida...

  14. Spatiotemporal Distribution, Sources, and Photobleaching Imprint of Dissolved Organic Matter in the Yangtze Estuary and Its Adjacent Sea Using Fluorescence and Parallel Factor Analysis.

    Penghui Li

    Full Text Available To investigate the seasonal and interannual dynamics of dissolved organic matter (DOM in the Yangtze Estuary, surface and bottom water samples in the Yangtze Estuary and its adjacent sea were collected and characterized using fluorescence excitation-emission matrices (EEMs and parallel factor analysis (PARAFAC in both dry and wet seasons in 2012 and 2013. Two protein-like components and three humic-like components were identified. Three humic-like components decreased linearly with increasing salinity (r>0.90, p<0.001, suggesting their distribution could primarily be controlled by physical mixing. By contrast, two protein-like components fell below the theoretical mixing line, largely due to microbial degradation and removal during mixing. Higher concentrations of humic-like components found in 2012 could be attributed to higher freshwater discharge relative to 2013. There was a lack of systematic patterns for three humic-like components between seasons and years, probably due to variations of other factors such as sources and characteristics. Highest concentrations of fluorescent components, observed in estuarine turbidity maximum (ETM region, could be attributed to sediment resuspension and subsequent release of DOM, supported by higher concentrations of fluorescent components in bottom water than in surface water at two stations where sediments probably resuspended. Meanwhile, photobleaching could be reflected from the changes in the ratios between fluorescence intensity (Fmax of humic-like components and chromophoric DOM (CDOM absorption coefficient (a355 along the salinity gradient. This study demonstrates the abundance and composition of DOM in estuaries are controlled not only by hydrological conditions, but also by its sources, characteristics and related estuarine biogeochemical processes.

  15. Search for astrophysical point sources with IceCube using a multipole analysis

    The search for astrophysical point sources of high energy neutrinos is one of the key tasks the IceCube Neutrino Observatory was set up for. Beside the direct search looking for temporal or spatial clustering of measured neutrino directions, a multipole analysis is another promising method to detect a point source signal. Therefor, the sky map of arrival directions is expanded in spherical harmonics. A large number of point sources, which individually are too weak to be detected, would leave a characteristic imprint on the spectrum of observed expansion coefficients. This talk presents the application of this analysis to the data taken with IceCube in its 79-string configuration.

  16. Assessment of Economic Loss Caused by Agricultural Non-point Source Nutrient Loss

    Fan, Liang-qian; Chen, Feng-hui

    2012-01-01

    Taking Zhejiang Province as an example, we use the JOHNES export coefficient model to estimate the total nitrogen (TN) and total phosphorus (TP) load of agricultural planting, livestock and poultry breeding and rural living non-point source in 2009. Based on the protection cost method in environmental economics, we quantitatively assess the economic loss caused by these three types of non-point source nutrient loss. The results show that in TN non-point source load, the load of land for plant...

  17. Mapping Correlation of Two Point Sources in the Gamma-Ray Sky

    Gibson, Alexander [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    The Fermi Gamma-Ray Space Telescope has been taking data on high energy photons or γ rays since June 11th, 2008, and people have been cataloging and profiling point sources of these γ rays ever since. After roughly one year of being in operation over 1400 sources were cataloged. Now, in 2015 we have 3033 sources cataloged. With the increasing amount of sources it’s important to think about the limitations of likelihood analysis for highly correlated sources. In this paper I will present the problems of using likelihood analysis for sources that are highly correlated as well as show under what circumstances sources can be considered highly correlated. Dark matter over densities may show up as a point source, so it is a necessary step to learn how the two signals will interact to allow for a proper search for dark matter.

  18. Simulation of Non-point Source Pollution in the Songhua River Basin Using GBNP Model

    Pan, J.; Tang, L.; Chen, Y. D.

    2015-12-01

    China is facing increasingly severe water pollution issue with rapid socio-economic development. Non-point source pollution, which is rarely monitored, has become the main forms of water pollution in China. In this study, the Geomorphology-Based Non-point source Pollution (GBNP) model was used to simulate the processes of rain-runoff, soil erosion, sediment routing and pollutant transport in the Songhua River basin from 2001 to 2010. The spatio-temporal variation of non-point source pollution and river water quality were analyzed based on the simulation outputs. In the entire basin, the annual mean loading of TN, TP and soil erosion are 270,000 ton/a, 42,200 ton/a and 55,900,000 ton/a, respectively. The point and non-point source pollution respectively account for 44.9% and 55.1% in TN loading. For TP loading, the proportions of point and non-point source pollution are 14.4% and 85.6%, respectively. It suggests that the non-point source pollution control and treatments should be paid more attention in the Songhua River basin. The inter-annual and intra-annual variations of non-point source pollution components and potential driving mechanisms are further examined. The annual loading of soil erosion, TN and TP are highly correlated with annual runoff, with the correlation coefficients of 0.75, 0.91 and 0.92, respectively, which implies that rain-runoff could be the main driving force of non-point pollution. The monthly sediment concentration in the watercourse is high in flood season and low in non-flood season, which agrees well with the seasonality of monthly runoff. By contrast, the concentrations of TN and TP in watercourse show the opposite features.

  19. Assessment of Economic Loss Caused by Agricultural Non-point Source Nutrient Loss

    FAN Liang-qian; CHEN Feng-hui

    2012-01-01

    Taking Zhejiang Province as an example, we use the JOHNES export coefficient model to estimate the total nitrogen (TN) and total phosphorus (TP) load of agricultural planting, livestock and poultry breeding and rural living non-point source in 2009. Based on the protection cost method in environmental economics, we quantitatively assess the economic loss caused by these three types of non-point source nutrient loss. The results show that in TN non-point source load, the load of land for planting accounts for 57.48%, the load of rural living accounts for 30.22%, and the load of livestock and poultry breeding accounts for 12.30%; in TP non-point source load, the load of rural living accounts for 46.18%, the load of livestock and poultry breeding accounts for 29.00%, and the load of land for planting accounts for 24.82%. The economic loss arising from the agricultural non-point source nutrient loss is equivalent to 2.329 424 7 billion yuan per year (the loss from land for planting accounts for 55.46%; the loss from rural living accounts for 31.21%; the loss from livestock and poultry breeding accounts for 13.33%). It indicates that in order to reduce the loss arising from agricultural non-point source nutrient loss, we should pay attention to controlling the land for planting and rural living source.

  20. Lowering IceCube's Energy Threshold for Point Source Searches in the Southern Sky

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Andeen, K.; Anderson, T.; Ansseau, I.; Anton, G.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blot, S.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Burgman, A.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Collin, G. H.; Conrad, J. M.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dujmovic, H.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hansmann, T.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jones, B. J. P.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Katz, U.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kim, M.; Kintscher, T.; Kiryluk, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, M.; Krückl, G.; Krüger, C.; Kunnen, J.; Kunwar, S.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lennarz, D.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mancina, S.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meier, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Penek, Ö.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Satalecka, K.; Schimp, M.; Schlunder, P.; Schmidt, T.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Rossem, M.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Whitehorn, N.; Wickmann, S.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wills, L.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.; IceCube Collaboration

    2016-06-01

    Observation of a point source of astrophysical neutrinos would be a “smoking gun” signature of a cosmic-ray accelerator. While IceCube has recently discovered a diffuse flux of astrophysical neutrinos, no localized point source has been observed. Previous IceCube searches for point sources in the southern sky were restricted by either an energy threshold above a few hundred TeV or poor neutrino angular resolution. Here we present a search for southern sky point sources with greatly improved sensitivities to neutrinos with energies below 100 TeV. By selecting charged-current ν μ interacting inside the detector, we reduce the atmospheric background while retaining efficiency for astrophysical neutrino-induced events reconstructed with sub-degree angular resolution. The new event sample covers three years of detector data and leads to a factor of 10 improvement in sensitivity to point sources emitting below 100 TeV in the southern sky. No statistically significant evidence of point sources was found, and upper limits are set on neutrino emission from individual sources. A posteriori analysis of the highest-energy (∼100 TeV) starting event in the sample found that this event alone represents a 2.8σ deviation from the hypothesis that the data consists only of atmospheric background.

  1. Risk-based prioritisation of point sources through assessment of the impact on a water supply

    Overheu, Niels D.; Tuxen, Nina; Troldborg, Mads;

    2011-01-01

    A large number of point sources threaten groundwater resources. A tool is presented which enables a uniform and transparent risk assessment and prioritisation of these point sources at the catchment scale with respect to the needs of further investigation or remediation. The tool integrates aquifer...... vulnerability mapping, site-specific mass flux estimates on a local scale from all the sources, and 3-D catchment-scale fate and transport modelling. It handles sources at various knowledge levels and accounts for uncertainties. The tool estimates the impacts on the water supply in the catchment and provides an...

  2. The Central Point Source in G76.9+1.0

    V. R. Marthi; J. N. Chengalur; Y. Gupta; G. C. Dewangan; D. Bhattacharya

    2011-12-01

    We describe the serendipitous discovery of a very steep-spectrum radio point source in low-frequency Giant Metrewave Radio Telescope (GMRT) images of the supernova remnant (SNR) G76.9+1.0. The steep spectrum, as well as the location of the point source near the centre of this SNR confirm that this indeed is the pulsar J2022+3842. Archival Chandra X-ray data shows a point source coincident with the radio point source. However, no pulsed radio emission was detected despite deep searches at 610 MHz and 1160 MHz – which can be understood to be due to temporal broadening of the pulses. Weak pulsed emission has indeed been seen at 2 GHz with the Green Bank Telescope (GBT), establishing the fact that scattering is responsible for its non-detection at low radio frequencies. We underline the usefulness of low-frequency radio imaging as a good technique to prospect for pulsar candidates.

  3. A guide to differences between stochastic point-source and stochastic finite-fault simulations

    Atkinson, G.M.; Assatourians, K.; Boore, D.M.; Campbell, K.; Motazedian, D.

    2009-01-01

    Why do stochastic point-source and finite-fault simulation models not agree on the predicted ground motions for moderate earthquakes at large distances? This question was posed by Ken Campbell, who attempted to reproduce the Atkinson and Boore (2006) ground-motion prediction equations for eastern North America using the stochastic point-source program SMSIM (Boore, 2005) in place of the finite-source stochastic program EXSIM (Motazedian and Atkinson, 2005) that was used by Atkinson and Boore (2006) in their model. His comparisons suggested that a higher stress drop is needed in the context of SMSIM to produce an average match, at larger distances, with the model predictions of Atkinson and Boore (2006) based on EXSIM; this is so even for moderate magnitudes, which should be well-represented by a point-source model. Why? The answer to this question is rooted in significant differences between point-source and finite-source stochastic simulation methodologies, specifically as implemented in SMSIM (Boore, 2005) and EXSIM (Motazedian and Atkinson, 2005) to date. Point-source and finite-fault methodologies differ in general in several important ways: (1) the geometry of the source; (2) the definition and application of duration; and (3) the normalization of finite-source subsource summations. Furthermore, the specific implementation of the methods may differ in their details. The purpose of this article is to provide a brief overview of these differences, their origins, and implications. This sets the stage for a more detailed companion article, "Comparing Stochastic Point-Source and Finite-Source Ground-Motion Simulations: SMSIM and EXSIM," in which Boore (2009) provides modifications and improvements in the implementations of both programs that narrow the gap and result in closer agreement. These issues are important because both SMSIM and EXSIM have been widely used in the development of ground-motion prediction equations and in modeling the parameters that control

  4. A Fast Algorithm for Finding Point Sources in the Fermi Data Stream: FermiFAST

    Ashathaman, Asha; Heyl, Jeremy S

    2016-01-01

    This paper presents a new and efficient algorithm for finding point sources in the photon event data stream from the Fermi Gamma-Ray Space Telescope. It can rapidly construct about most significant half of the Fermi Third Point Source catalogue (3FGL) with nearly 80% purity from the four years of data used to construct the catalogue. If a higher purity sample is desirable, one can achieve a sample that includes the most significant third of the Fermi 3FGL with only five percent of the sources unassociated with Fermi sources. Outside the galaxy plane, the contamination is essentially negligible. This software allows for rapid exploration of the Fermi data, simulation of the source detection to calculate the selection function of various sources and the errors in the obtained parameters of the sources detected.

  5. CHANDRA OBSERVATIONS OF THE X-RAY POINT SOURCE POPULATION IN NGC 4636

    We present the X-ray point-source population in the nearby Virgo elliptical galaxy NGC 4636 from three Chandra X-ray observations. These observations, totaling ∼193 ks after time filtering, were taken with the Advanced CCD Imaging Camera (ACIS) over a three-year period. Using a wavelet decomposition detection algorithm, we detect 318 individual point sources. For our analysis, we use a subset of 277 detections with ≥ net 10 counts (a limiting luminosity of approximately 1.2 x 1037 erg s-1 in the 0.5-2 keV band, outside the central 1.'5 bright galaxy core). We present a radial distribution of the point sources. Between 1.'5 and 6' from the center, 25% of our sources are likely to be background sources (active galactic nuclei (AGNs)) and 75% are low-mass X-ray binaries (LMXBs) within the galaxy, while at radial distances greater than 6', background sources (AGN) will dominate the point sources. We explore short and long-term variability (over timescales of 1 day to three years) for X-ray point sources in this elliptical galaxy. 54 sources (24%) in the common ACIS fields of view show significant variability between observations. Of these, 37 are detected with at least 10 net counts in only one observation and thus may be 'transient'. In addition, ∼10% of the sources in each observation show significant short-term variability; we present an example light curve for a variable bright source. The cumulative luminosity function (LF) for the point sources in NGC 4636 can be represented as a power law of slope α = 1.14 ± 0.03. We do not detect, but estimate an upper limit of ∼4.5 x 1037 erg s-1 to the current X-ray luminosity of the historical supernova SN1939A. We find 77 matches between X-ray point sources and globular cluster (GC) candidates found in deep optical images of NGC 4636. In the annulus from 1.'5 to 6' of the galaxy center, 48 of the 129 X-ray point sources (37%) with ≥10 net counts are matched with GC candidates. Since we expect 25% of these

  6. Identification and quantification of point sources of surface water contamination in fruit culture in the Netherlands

    Wenneker, M.; Beltman, W.H.J.; Werd, de, H.A.E.; Zande, van der, W.J.

    2008-01-01

    Measurements of pesticide concentrations in surface water by the water boards show that they have decreased less than was expected from model calculations. Possibly, the implementation of spray drift reducing techniques is overestimated in the model calculation. The impact of point sources is probably underestimated. A project was initiated for the quantification and qualification of possible point sources in Dutch fruit culture. From a survey it was concluded that the majority of fruit growe...

  7. Shape from Two Images under Point Light Source Illumination and Perspective Projection

    岩堀, 祐之||イワホリ, ユウジ||Iwahori, Yuji; 藤吉, 弘亘||フジヨシ, ヒロノブ||Fujiyoshi, Hironobu; 福井, 真二 ||フクイ, シンジ||Shinji, Fukui; 河中, 治樹||カワナカ, ハルキ||Kawanaka, Haruki

    2011-01-01

    This paper introduces one of the advanced researches of the research project 53-(b) in Information Science Research Institute, Chubu University. As a method to recover 3-D shape from shading images, Light Fall-off Stereo (LFS) has been proposed using the inverse square law for illuminance with point light source illumination. This paper extends the principle of light fall-off stereo and proposes a new approach under the assumption of both point light source illumination and perspective projec...

  8. Non point source pollution modelling in the watershed managed by Integrated Conctructed Wetlands: A GIS approach.

    Vyavahare, Nilesh

    2008-01-01

    The non-point source pollution has been recognised as main cause of eutrophication in Ireland (EPA Ireland, 2001). Integrated Constructed Wetland (ICW) is a management practice adopted in Annestown stream watershed, located in the south county of Waterford in Ireland, used to cleanse farmyard runoff. Present study forms the annual pollution budget for the Annestown stream watershed. The amount of pollution from non-point sources flowing into the stream was simulated by using GIS techniques; u...

  9. Negotiating the initial permits allocation as a revelation mechanism in non point source pollution

    Ali, Mourad; Rio, Patrick; European Association of Environmental and Resource Economists; Groupe d'Etudes et de Recherche en Analyse des Décisions

    2007-01-01

    Non point source pollution is characterized by the fact that individual emissions are not observable at a reasonable cost. This constitutes a moral hazard problem. Furthermore, we explicitly consider adverse selection, a second type of asymmetric information that arises because of the difficulty to differentiate the polluters with respect to their type (marginal benefit of polluting). In this paper, we design a tradable permits market between non point sources of pollution in the vein of Tayl...

  10. Regulation of Heterogenous Non-Point Sources of Pollution Under Imperfect Information, The

    Richard Cabe; Herriges, Joseph A.

    1990-01-01

    This paper discusses the rose of information structure (i.e., information cost, reliability, and distribution among agents) in the design of a regulatory mechanism for controlling non-point source pollution. An ambient concentration tax mechanism is examined for non-point source pollution with spatial transport among multiple zones. Imposition of the tax requires costly measurement of ambient concentrations in selected zones, and the selection of zones for measurement must be undertaken witho...

  11. Evaluation of the Agricultural Non-point Source Pollution in Chongqing Based on PSR Model

    Zhang, Hanwen; MOU, Xinli; Xie, Hui; Lu, Hong; YAN, Xingyun

    2014-01-01

    Through a series of exploration based on PSR framework model, for the purpose of building a suitable Chongqing agricultural non-point source pollution evaluation index system model framework, combined with the presence of Chongqing specific agro-environmental issues, we build a agricultural non-point source pollution assessment index system, and then study the agricultural system pressure, agro-environmental status and human response in total 3 major categories, develope an agricultural non-p...

  12. Game Analysis and Strategy Research of Farmers Involving in the Agricultural Non-Point Source Pollution Prevention and Control

    Zhou Zaohong

    2013-06-01

    Full Text Available This thesis applies game theory to make a quantitative analysis of the outward problem of the agricultural non-point source pollution and discusses the basic starting point to study the agricultural non-point source pollution prevention and control and furthermore researches the measures and recommendations of agricultural non-point source pollution prevention and control.

  13. Game Analysis and Strategy Research of Farmers Involving in the Agricultural Non-Point Source Pollution Prevention and Control

    Zhou Zaohong

    2013-01-01

    This thesis applies game theory to make a quantitative analysis of the outward problem of the agricultural non-point source pollution and discusses the basic starting point to study the agricultural non-point source pollution prevention and control and furthermore researches the measures and recommendations of agricultural non-point source pollution prevention and control.

  14. Resolution of point sources of light as analyzed by quantum detection theory.

    Helstrom, C. W.

    1973-01-01

    The resolvability of point sources of incoherent thermal light is analyzed by quantum detection theory in terms of two hypothesis-testing problems. In the first, the observer must decide whether there are two sources of equal radiant power at given locations, or whether there is only one source of twice the power located midway between them. In the second problem, either one, but not both, of two point sources is radiating, and the observer must decide which it is. The decisions are based on optimum processing of the electromagnetic field at the aperture of an optical instrument. In both problems the density operators of the field under the two hypotheses do not commute. The error probabilities, determined as functions of the separation of the points and the mean number of received photons, characterize the ultimate resolvability of the sources.

  15. The resolution of point sources of light as analyzed by quantum detection theory

    Helstrom, C. W.

    1972-01-01

    The resolvability of point sources of incoherent light is analyzed by quantum detection theory in terms of two hypothesis-testing problems. In the first, the observer must decide whether there are two sources of equal radiant power at given locations, or whether there is only one source of twice the power located midway between them. In the second problem, either one, but not both, of two point sources is radiating, and the observer must decide which it is. The decisions are based on optimum processing of the electromagnetic field at the aperture of an optical instrument. In both problems the density operators of the field under the two hypotheses do not commute. The error probabilities, determined as functions of the separation of the points and the mean number of received photons, characterize the ultimate resolvability of the sources.

  16. A New Method for Finding Point Sources in High-energy Neutrino Data

    Fang, Ke

    2016-01-01

    The IceCube collaboration has reported the first detection of high-energy astrophysical neutrinos including $\\sim 50$ high-energy starting events, but no individual sources have been identified. It is therefore important to develop the most sensitive and efficient possible algorithms to identify point sources of these neutrinos. The most popular current method works by exploring a dense grid of possible directions to individual sources, and identifying the single direction with the maximum probability of having produced multiple detected neutrinos. This method has numerous strengths, but it is computationally intensive and, because it focuses on the single best location for a point source, additional point sources are not included in the evidence. We propose a new maximum likelihood method that uses the angular separations between all pairs of neutrinos in the data. Unlike existing autocorrelation methods for this type of analysis, which also use angular separations between neutrino pairs, our method incorpor...

  17. CHANDRA ACIS Survey of X-Ray Point Sources: The Source Catalog

    Wang, Song; Liu, Jifeng; Qiu, Yanli; Bai, Yu; Yang, Huiqin; Guo, Jincheng; Zhang, Peng

    2016-06-01

    The Chandra archival data is a valuable resource for various studies on different X-ray astronomy topics. In this paper, we utilize this wealth of information and present a uniformly processed data set, which can be used to address a wide range of scientific questions. The data analysis procedures are applied to 10,029 Advanced CCD Imaging Spectrometer observations, which produces 363,530 source detections belonging to 217,828 distinct X-ray sources. This number is twice the size of the Chandra Source Catalog (Version 1.1). The catalogs in this paper provide abundant estimates of the detected X-ray source properties, including source positions, counts, colors, fluxes, luminosities, variability statistics, etc. Cross-correlation of these objects with galaxies shows that 17,828 sources are located within the D 25 isophotes of 1110 galaxies, and 7504 sources are located between the D 25 and 2D 25 isophotes of 910 galaxies. Contamination analysis with the log N–log S relation indicates that 51.3% of objects within 2D 25 isophotes are truly relevant to galaxies, and the “net” source fraction increases to 58.9%, 67.3%, and 69.1% for sources with luminosities above 1037, 1038, and 1039 erg s‑1, respectively. Among the possible scientific uses of this catalog, we discuss the possibility of studying intra-observation variability, inter-observation variability, and supersoft sources (SSSs). About 17,092 detected sources above 10 counts are classified as variable in individual observation with the Kolmogorov–Smirnov (K–S) criterion (P K–S sources observed more than once and 11,843 sources observed 10 times or more, offering us a wealth of data with which to explore the long-term variability. There are 1638 individual objects (∼2350 detections) classified as SSSs. As a quite interesting subclass, detailed studies on X-ray spectra and optical spectroscopic follow-up are needed to categorize these SSSs and pinpoint their properties. In addition, this survey can

  18. Temporal-spatial distribution of non-point source pollution in a drinking water source reservoir watershed based on SWAT

    Wang, M; Cheng, W.; Yu, B.-S.; Fang, Y.

    2015-01-01

    The conservation of drinking water source reservoirs has a close relationship between regional economic development and people’s livelihood. Research on the non-point pollution characteristics in its watershed is crucial for reservoir security. Tang Pu Reservoir watershed was selected as the study area. The non-point pollution model of Tang Pu Reservoir was established based on the SWAT (Soil and Water Assessment Tool) model. The model was adjusted to analyse the temporal-spatial distribution...

  19. Chandra ACIS Survey of X-ray Point Sources: The Source Catalog

    Wang, Song; Qiu, Yanli; Bai, Yu; Yang, Huiqin; Guo, Jincheng; Zhang, Peng

    2016-01-01

    The $Chandra$ archival data is a valuable resource for various studies on different topics of X-ray astronomy. In this paper, we utilize this wealth and present a uniformly processed data set, which can be used to address a wide range of scientific questions. The data analysis procedures are applied to 10,029 ACIS observations, which produces 363,530 source detections, belonging to 217,828 distinct X-ray sources. This number is twice the size of the $Chandra$ Source Catalog (Version 1.1). The catalogs in this paper provide abundant estimates of the detected X-ray source properties, including source positions, counts, colors, fluxes, luminosities, variability statistics, etc. Cross-correlation of these objects with galaxies shows 17,828 sources are located within the $D_{25}$ isophotes of 1110 galaxies, and 7504 sources are located between the $D_{25}$ and 2$D_{25}$ isophotes of 910 galaxies. Contamination analysis with the log$N$--log$S$ relation indicates that 51.3\\% of objects within 2$D_{25}$ isophotes are...

  20. Mapping correlation of a simulated dark matter source and a point source in the gamma-ray sky - Oral Presentation

    Gibson, Alexander [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-23

    In my research, I analyzed how two gamma-ray source models interact with one another when optimizing to fit data. This is important because it becomes hard to distinguish between the two point sources when they are close together or looking at low energy photons. The reason for the first is obvious, the reason why they become harder to distinguish at lower photon energies is the resolving power of the Fermi Gamma-Ray Space Telescope gets worse at lower energies. When the two point sources are highly correlated (hard to distinguish between), we need to change our method of statistical analysis. What I did was show that highly correlated sources have larger uncertainties associated with them, caused by an optimizer not knowing which point source’s parameters to optimize. I also mapped out where their is high correlation for 2 different theoretical mass dark matter point sources so that people analyzing them in the future knew where they had to use more sophisticated statistical analysis.

  1. Sensitivity of the Baikal neutrino telescope NT-200 to point sources of very high energy neutrinos

    The sensitivity of the deep underwater muon and neutrino detector 'NT-200' in lake Baikal to point sources of extraterrestrial neutrinos is calculated. Results are given for different assumptions on the neutrino source spectrum and the reconstruction capabilities of the detector. (orig.)

  2. On transient waves in dispersive media produced by moving point sources

    A solution for the inhomogeneous telegraph equation for a point source moving with the velocity of light is constructed. We find relations describing both the transient and steady-state wave processes. The solutions obtained are used to define electromagnetic waves in a conductive medium. The case of a source moving faster than light is also given. (author)

  3. Search for Point Sources of High Energy Neutrinos with Final Data from AMANDA-II

    Abbasi, R; Adams, J; Ahlers, M; Ahrens, J; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Baret, B; Barwick, S W; Bay, R; Bazo Alba, J L; Beattie, K; Becka, T; Becker, J K; Becker, K H; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Blaufuss, E; Boersma, D J; Bohm, C; Bolmont, J; Boser, S; Botner, O; Braun, J; Breder, D; Burgess, T; Castermans, T; Chirkin, D; Christy, B; Clem, J; Cowen, D F; D'Agostino, M V; Danninger, M; Davour, A; Day, C T; Depaepe, O; De Clercq, C; Demirors, L; Descamps, F; Desiati, P; De Vries-Uiterweerd, G; De Young, T; Díaz-Veléz, J C; Dreyer, J; Dumm, J P; Duvoort, M R; Edwards, W R; Ehrlich, R; Eisch, J; Ellsworth, R W; Engdegard, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Filimonov, K; Finley, C; Foerster, M M; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Ganugapati, R; Gerhardt, L; Gladstone, L; Goldschmidt, A; Goodman, J A; Gozzini, R; Grant, D; Griesel, T; Gro, A; Grullon, S; Gunasingha, R M; Gurtner, M; Ha, C; Hallgren, A; Halzen, F; Han, K; Hanson, K; Hardtke, R; Hasegawa, Y; Heise, J; Helbing, K; Hellwig, M; Herquet, P; Hickford, S; Hill, G C; Hodges, J; Hoffman, K D; Hoshina, K; Hubert, D; Huelsnitz, W; Hughey, B; Hul, J P; Hulth, P O; Hultqvist, K; Hundertmark, S; Hussain, S; Imlay, R L; Inaba, M; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Joseph, J M; Kampert, K H; Kappes, A; Karg, T; Karle, A; Kawai, H; Kelley, J L; Kiryluk, J; Kislat, F; Klein, S R; Klepser, S; Kohnen, G; Kolanoski, H; Köpke, L; Kowalski, M; Kowarik, T; Krasberg, M; Kühn, K; Kuwabara, T; Labare, M; Laihem, K; Landsman, H; Lauer, R; Leich, H; Leier, D; Lewis, C; Lucke, A; Lundberg, J; Lunemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McParland, C P; Meagher, K; Meli, A; Merck, M; Messarius, T; Mészáros, P; Miyamoto, H; Mohr, A; Montaruli, T; Morse, R; Movit, S M; Munich, K; Nahnhauer, R; Nam, J W; Nieen, P; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; Ono, M; Panknin, S; Patton, S; Pérez de los Heros, C; Petrovic, J; Piegsa, A; Pieloth, D; Pohl, A C; Porrata, R; Potthoff, N; Pretz, J; Price, P B; Przybylski, G T; Rawlins, K; Razzaque, S; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Robbins, W J; Rodríguez, J; Roth, P; Rothmaier, F; Rott, C; Roucelle, C; Rutledge, D; Ryckbosch, D; Sander, H G; Sarkar, S; Satalecka, K; Schlenstedt, S; Schmidt, T; Schneider, D; Schultz, O; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Smith, A J; Song, C; Spiczak, G M; Spiering, C; Stanev, T; Stezelberger, T; Stokstad, R G; Stoufer, M C; Stoyanov, S; Strahler, E A; Straszheim, T; Sulanke, K H; Sullivan, G W; Swillens, Q; Taboada, I; Tarasova, O; Tepe, A; Ter-Antonyan, S; Tilav, S; Tluczykont, M; Toale, P A; Tosi, D; Turcan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; Viscomi, V; Vogt, C; Voigt, B; Walck, C; Waldenmaier, T; Walter, M; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebusch, C H; Wiedemann, C; Wikström, G; Williams, D R; Wischnewski, R; Wissing, H; Woschnagg, K; Xu, X W; Yodh, G; Yoshida, S

    2008-01-01

    We present a search for point sources of high energy neutrinos using 3.8 years of data recorded by the AMANDA-II neutrino telescope during 2000-2006. Applying muon track reconstruction and quality criteria, we select 6595 candidate events, predominantly from atmospheric neutrinos. Our search reveals no indications of a neutrino point source. We place the most stringent limits to date on E$^{-2}$ neutrino fluxes from points in the Northern Sky, with an average upper limit of E$^{2}\\Phi_{\

  4. Identification and Quantification of Non-Point Sources of pollution to Sabarmati River, Ahmedabad

    Monika H. Panchani; Prof. M. J. Pandya

    2013-01-01

    “Whatever can be measure, can be control”.Non-point pollution sources(NPS) account for more than 50% of the total water quality problem, and they are being recognized and investigated nationally and internationally. In many areas, non-point pollution, such as runoff from crop land, urban storm water, strip mining and runoff from construction sites are becoming major water quality problems.To identify and quantify Non-point sources of pollution the selected study area is the stretch of the Sab...

  5. Point Source Detection with Wavelets applied on Cosmic Microwave Radiation Maps

    2008-01-01

    In between the Cosmic Microwave Background (CMB) and the instrument there are other sources of radiation, called foregrounds. The foregrounds radiate in the same frequency bands as the background, and cause contamination in the signal of the CMB. To ensure no wrong estimations of the power spectrum, these contaminants must be removed. There are several classes of contaminants, and this thesis has investigated techniques of removing the point sources (class of extragalactic sources), which occ...

  6. Inference of Unresolved Point Sources At High Galactic Latitudes Using Probabilistic Catalogs

    Daylan, Tansu; Finkbeiner, Douglas P

    2016-01-01

    We construct a Bayesian framework to perform inference of dim or overlapping point sources. The method involves probabilistic cataloging, where samples are taken from the posterior probability distribution of catalogs consistent with an observed photon count map. By implementing across-model jumps between point source models of different dimensionality, we collect a representative ensemble of catalogs consistent with the image. In order to validate our method we sample random catalogs of the gamma-ray sky in the direction of the North Galactic Pole (NGP) by binning the data in energy and PSF (Point Spread Function) classes. Using three energy bins between $0.3 - 1$, $1 - 3$ and $3 - 10$ GeV, we identify $270\\substack{+30 -10}$ point sources inside a $40^\\circ \\times 40^\\circ$ region around the NGP above our point-source inclusion limit of $3 \\times 10^{-11}$/cm$^2$/s/sr/GeV at the $1-3$ GeV energy bin. Most of these point sources are time-variable blazars. Modeling the flux distribution as a single power law,...

  7. Miniature x-ray point source for alignment and calibration of x-ray optics

    A miniature x-ray point source of high brightness similar to that of Rovinsky, et al. is described. One version of the x-ray source is used to align the x-ray optics on the Argus and Shiva laser systems. A second version is used to determine the spatial and spectral transmission functions of the x-ray optics. The spatial and spectral characteristics of the x-ray emission from the x-ray point source are described. The physical constraints including size, intensity and thermal limitations, and useful lifetime are discussed. The alignment and calibration techniques for various x-ray optics and detector combinations are described

  8. A New Method for Finding Point Sources in High-energy Neutrino Data

    Fang, Ke; Miller, M. Coleman

    2016-08-01

    The IceCube collaboration has reported the first detection of high-energy astrophysical neutrinos, including ∼50 high-energy starting events, but no individual sources have been identified. It is therefore important to develop the most sensitive and efficient possible algorithms to identify the point sources of these neutrinos. The most popular current method works by exploring a dense grid of possible directions to individual sources, and identifying the single direction with the maximum probability of having produced multiple detected neutrinos. This method has numerous strengths, but it is computationally intensive and because it focuses on the single best location for a point source, additional point sources are not included in the evidence. We propose a new maximum likelihood method that uses the angular separations between all pairs of neutrinos in the data. Unlike existing autocorrelation methods for this type of analysis, which also use angular separations between neutrino pairs, our method incorporates information about the point-spread function and can identify individual point sources. We find that if the angular resolution is a few degrees or better, then this approach reduces both false positive and false negative errors compared to the current method, and is also more computationally efficient up to, potentially, hundreds of thousands of detected neutrinos.

  9. Models and key points of review for airborne radioactive source terms in nuclear power plants

    Background: The calculation model of airborne radioactive source term in Nuclear Power Plants is one of the key points of safety review. However, in most safety analysis reports, a general simplified model of airborne radioactive source terms has been used, which is not applicable for all cases. Purpose: The aim is to complete the review calculations quickly and accurately. Methods: The model was based on the physical diffusion mechanism of radionuclides and their diffusion behavior in different spaces. Results: We proposed three models which could be respectively used for airborne radioactive source terms in reactor building, fuel element building and auxiliary building. Meanwhile, the key points in review of airborne radioactive source terms were put forward. Conclusion: Three models were proposed and their corresponding review key points will play a significant role in review calculations. (authors)

  10. Tackling non-point source water pollution in British Columbia: An action plan

    1998-01-01

    Efforts to protect British Columbia water quality by regulating point discharges from municipal and industrial sources have generally been successful, and it is recognized that the major remaining cause of water pollution in the province is from non-point sources. These sources are largely unregulated and associated with urbanization, agriculture, and other forms of land development. The first part of this report reviews the provincial commitment to clean water, the effects of non-point-source (NPS) pollution, and the management of NPS in the province. Part 2 describes the main causes of NPS in British Columbia: Land development, agriculture, stormwater runoff, on-site sewage systems, forestry and range activities, atmospheric deposition, and boating/marine activities. Finally, it presents key components of the province's NPS action plan: Education and training, prevention at site, land use planning and co-ordination, assessment and reporting, economic incentives, legislation and regulation, and implementation.

  11. Long Term Temporal and Spectral Evolution of Point Sources in Nearby Elliptical Galaxies

    Durmus, D.; G"uver, T.; H"udaverdi, M.; Sert, H.

    2016-06-01

    We present the results of an archival study of all the point sources detected in the lines of sight of the elliptical galaxies NGC 4472, NGC 4552, NGC 4649, M32, Maffei 1, NGC 3379, IC 1101, M87, NGC 4477, NGC 4621, and NGC 5128, with both the Chandra and XMM-Newton observatories. Specifically, we studied the temporal and spectral evolution of these point sources over the course of the observations of the galaxies, mostly covering the 2000 - 2015 period. In this poster we present the first results of this study, which allows us to further constrain the X-ray source population in nearby elliptical galaxies and also better understand the nature of individual point sources.

  12. Evaluation of the Agricultural Non-point Source Pollution in Chongqing Based on PSR Model

    Hanwen; ZHANG; Xinli; MOU; Hui; XIE; Hong; LU; Xingyun; YAN

    2014-01-01

    Through a series of exploration based on PSR framework model,for the purpose of building a suitable Chongqing agricultural nonpoint source pollution evaluation index system model framework,combined with the presence of Chongqing specific agro-environmental issues,we build a agricultural non-point source pollution assessment index system,and then study the agricultural system pressure,agro-environmental status and human response in total 3 major categories,develope an agricultural non-point source pollution evaluation index consisting of 3 criteria indicators and 19 indicators. As can be seen from the analysis,pressures and responses tend to increase and decrease linearly,state and complex have large fluctuations,and their fluctuations are similar mainly due to the elimination of pressures and impact,increasing the impact for agricultural non-point source pollution.

  13. The Herschel Virgo Cluster Survey. XVII. SPIRE point-source catalogs and number counts

    Pappalardo, Ciro; Bianchi, Simone; Hunt, Leslie; Zibetti, Stefano; Corbelli, Edvige; Alighieri, Sperello di Serego; Grossi, Marco; Davies, Jonathan; Baes, Maarten; De Looze, Ilse; Fritz, Jacopo; Pohlen, Michael; Smith, Matthew W L; Verstappen, Joris; Boquien, Mederic; Boselli, Alessandro; Cortese, Luca; Hughes, Thomas; Viaene, Sebastien; Bizzocchi, Luca; Clemens, Marcel

    2014-01-01

    We present three independent catalogs of point-sources extracted from SPIRE images at 250, 350, and 500 micron as a part of the Herschel Virgo Cluster Survey (HeViCS). The source positions are determined by estimating the likelihood to be a real source for each peak on the maps and the flux densities are estimated using the sourceExtractorTimeline, a timeline-based point source fitter. Afterwards, each source is subtracted from the maps, removing a Gaussian function in every position with the full width half maximum equal to that estimated in sourceExtractorTimeline. This procedure improves the robustness of our algorithm in terms of source identification. The HeViCS catalogs contain about 52000, 42200, and 18700 sources selected at 250, 350, and 500 micron above 3sigma and are ~ 75%, 62%, and 50% complete at flux densities of 20 mJy at 250, 350, 500 micron, respectively. We then measured source number counts at 250, 350, and 500 micron and we also cross-correlated the catalogs with the Sloan Digital Sky Surv...

  14. High-frequency radio properties of sources in the Fermi-LAT 1-year Point Source Catalogue

    Mahony, Elizabeth K; Murphy, Tara; Ekers, Ronald D; Edwards, Philip G; Massardi, Marcella

    2010-01-01

    The high-frequency radio sky, like the gamma-ray sky surveyed by the Fermi satellite, is dominated by flat-spectrum radio quasars and BL-Lac objects at bright flux levels. To investigate the relationship between radio and gamma-ray emission in extragalactic sources, we have crossmatched the Australia Telescope 20 GHz survey catalogue (AT20G; Murphy et al. 2010) with the Fermi-LAT 1-year Point Source Catalogue (1FGL; Abdo et al. 2010a). The 6.0 sr of sky covered by both catalogues (delta<0 deg, |b|<1.5 deg) contains 5890 AT20G radio sources and 604 1FGL gamma-ray sources. The AT20G source positions are accurate to within ~1 arcsec and, after excluding known Galactic sources, 43% of Fermi 1FGL sources have an AT20G source within the 95% Fermi confidence ellipse. Monte Carlo tests imply that at least 95% of these matches are genuine associations. Only five gamma-ray sources (1% of the Fermi catalogue) have more than one AT20G counterpart in the Fermi error box. The AT20G matches also generally support the ...

  15. Euromet action 428: transfer of ge detectors efficiency calibration from point source geometry to other geometries

    The EUROMET project 428 examines efficiency transfer computation for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry in the 60 keV to 2 MeV energy range. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy. For carefully examining these results and trying to derive information for improving the computation codes, this study was limited to a few simple cases, from an experimental efficiency calibration for point source at 10-cm source-to-detector distance. The first part concerns the simplest case of geometry transfer, i.e., using point sources for 3 source-to-detector distances: 2,5 and 20 cm; the second part deals with transfer from point source geometry to cylindrical geometry with three different matrices. The general results show that the deviations between the computed results and the measured efficiencies are for the most part within 10%. The quality of the results is rather inhomogeneous and shows that these codes cannot be used directly for metrological purposes. However, most of them are operational for routine measurements when efficiency uncertainties of 5-10% can be sufficient. (author)

  16. mpacts of Agricultural Non-point Pollution on Water-source Area in Songhua Dam

    2012-01-01

    [Objective] The aim was to research impacts of agricultural non-point pol- lution on water-source region in Songhua Dam, laying foundation for control of water pollution and scientific protection of water-source region. [Method] Water in Muyang River, lengshui River and Zizania aquatica region were sampled to measure content of pollutants in water and conclude relation between water contamination and agri- cultural non-point pollution to find the major cause of pollution. [Result] Organic pollu- tant in Muyang River was higher; N and P contents in Lengshui River were higher; the measured indices in Zizania aquatica region excessively exceeded related stan- dard. [Conclusion] The chemical fertilizers and pesticides are the toxic materials lead- ing to water contamination and constitute a major cause of pollution in Songhua Dam water-source region. Agricultural non-point pollution should be controlled in a scientific way.

  17. A Free, Open-Source Tool for Identifying Urban Agglomerations Using Point Data

    Day, Jennifer; Chen, Yiqun; Ellis, Peter; Roberts, Mark

    2015-01-01

    This paper describes a software tool for identifying urban agglomerations in low-information settings. The framework outlined in this paper is designed to work using point data. Our tool and all required data are provided free and in open-source format. This paper describes the advantages and disadvantages of using point-based geographies in regional analysis, discusses the practical and ethical challenges of distinguishing urban from rural regions, details the function of our software, and d...

  18. Applicability of a desiccant dew-point cooling system independent of external water sources

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin;

    2015-01-01

    The applicability of a technical solution for making desiccant cooling systems independent of external water sources is investigated. Water is produced by condensing the desorbed water vapour in a closed regeneration circuit. Desorbed water recovery is applied to a desiccant dew-point cooling...... system, which includes a desiccant wheel and a dew point cooler. The system is simulated during the summer period in the Mediterranean climate of Rome and it results completely independent of external water sources. The seasonal thermal COP drops 8% in comparison to the open regeneration circuit solution...

  19. Method for calculating non-point source pollution distribution in plain rivers

    Long-xi HAN; Huo, Fei; Sun, Juan

    2011-01-01

    The land area in river network is divided into some foursquare cells with certain scale for the demand of precision, proceeding from the physical mechanism of the rainfall-runoff and runoff pollution, the non-point source pollution from cells are estimated using the export coefficient of different land use types. According to the terrain of plain river network area and the positions of land cells and river network’s reaches, a principle is advanced which indicates that the non-point source po...

  20. Point Sources from a Spitzer IRAC Survey of the Galactic Center

    Ramirez, Solange V; Sellgren, Kris; Stolovy, Susan R; Cotera, Angela; Smith, Howard A; Yusef-Zadeh, Farhad

    2007-01-01

    We have obtained Spitzer/IRAC observations of the central 2.0 x 1.4 degrees (~280 x 200 pc) of the Galaxy at 3.6-8.0 microns. A point source catalog of 1,065,565 objects is presented. The catalog includes magnitudes for the point sources at 3.6, 4.5, 5.8, and 8.0 microns, as well as JHK photometry from 2MASS. The point source catalog is confusion limited with average limits of 12.4, 12.1, 11.7, and 11.2 magnitudes for [3.6], [4.5], [5.8], and [8.0], respectively. We find that the confusion limits are spatially variable because of stellar surface density, background surface brightness level, and extinction variations across the survey region. The overall distribution of point source density with Galactic latitude and longitude is essentially constant, but structure does appear when sources of different magnitude ranges are selected. Bright stars show a steep decreasing gradient with Galactic latitude, and a slow decreasing gradient with Galactic longitude, with a peak at the position of the Galactic center. Fr...

  1. ALLOCATIVE IMPLICATIONS OF COMPARISONS BETWEEN THE MARGINAL COSTS OF POINT AND NONPOINT SOURCE POLLUTION ABATEMENT

    Shortle, James S.

    1987-01-01

    This paper examines the possible use of information on the relative marginal costs of point and nonpoint source water pollution abatement to assess the efficiency implications of shifting a greater portion of the burden for water quality protection to nonpoint sources. The inherent uncertainty about the effects of changes in resource allocation for nonpoint pollution abatement on nonpoint pollution loads is recognized in the analysis. This uncertainty is shown to result in significant limitat...

  2. An international point source outbreak of typhoid fever: a European collaborative investigation*

    Stanwell-Smith, R E; Ward, L. R.

    1986-01-01

    A point source outbreak of Salmonella typhi, degraded Vi-strain 22, affecting 32 British visitors to Kos, Greece, in 1983 was attributed by a case—control study to the consumption of a salad at one hotel. This represents the first major outbreak of typhoid fever in which a salad has been identified as the vehicle. The source of the infection was probably a carrier in the hotel staff. The investigation demonstrates the importance of national surveillance, international cooperation, and epidemi...

  3. Global Pollution of Surface Waters from Point and Nonpoint Sources of Nitrogen

    van Drecht, G.; A.F. Bouwman; J.M. Knoop; Meinardi, C.; Beusen, A.

    2001-01-01

    Global 0.5- by 0.5-degree resolution estimates are presented on the fate of nitrogen (N) stemming from point and nonpoint sources, including plant uptake, denitrification, leaching from the rooting zone, rapid flow through shallow groundwater, and slow flow through deep groundwater to riverine systems. Historical N inputs are used to describe the N flows in groundwater. For nonpoint N sources (agricultural and natural ecosystems), calculations are based on local hydrology, climate, geology, s...

  4. Cancer clustering around point sources of pollution: assessment by a case-control methodology

    The case-control method is proposed to test clustering of cancers near point sources of air pollution. The techniques for applying the method are described and applied to two sources of pollution: a coke oven associated with a steel mill, and a large uranium tailing dump. In neither situation was a significant excess of the cancer of interest found when compared to control cancers, though a slight excess of lung cancer was found near the coke ovens

  5. The Unicellular State as a Point Source in a Quantum Biological System

    John S. Torday

    2016-05-01

    Full Text Available A point source is the central and most important point or place for any group of cohering phenomena. Evolutionary development presumes that biological processes are sequentially linked, but neither directed from, nor centralized within, any specific biologic structure or stage. However, such an epigenomic entity exists and its transforming effects can be understood through the obligatory recapitulation of all eukaryotic lifeforms through a zygotic unicellular phase. This requisite biological conjunction can now be properly assessed as the focal point of reconciliation between biology and quantum phenomena, illustrated by deconvoluting complex physiologic traits back to their unicellular origins.

  6. VERITAS Observations of the Unidentified Point Source HESS J1943+213

    ,

    2015-01-01

    The H.E.S.S. Galactic plane scan has revealed a large population of Galactic very high energy (VHE; E > 100 GeV) emitters. The majority of the galactic sources are extended and can typically be associated with pulsar wind nebulae (35%) and supernova remnants (21%), while some of the sources remain unidentified (31%). A much smaller fraction of point-like sources (5 in total, corresponding to 4%) are identified as gamma-ray binaries. Active galactic nuclei located behind the Galactic plane are also a potential source class. An active galaxy could be identified in the VHE regime by a point like extension, a high variability amplitude (up to a factor of 100) and a typically soft spectrum (due to absorption by the extra-galactic background light). Here we report on VERITAS observations of HESS J1943+213, an unidentified point source discovered to emit above 470 GeV during the extended H.E.S.S. Galactic plane scan. This source is thought to be a distant BL Lac object behind the Galactic plane and, though it exhibi...

  7. HerMES: Point source catalogues from Herschel-SPIRE observations II

    Wang, L; Clarke, C; Bock, J; Buat, V; Conley, A; Farrah, D; Heinis, S; Magdis, G; Marchetti, L; Marsden, G; Norberg, P; Oliver, S J; Roehlly, Y; Roseboom, I G; Schulz, B; Smith, A J; Vaccari, M; Zemcov, M

    2013-01-01

    The Herschel Multi-tiered Extragalactic Survey (HerMES) is the largest Guaranteed Time Key Programme on the Herschel Space Observatory. With a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling ~380 deg^2. In this paper, we present deep point source catalogues extracted from Herschel-SPIRE observations of all HerMES fields, except for the later addition of the 270 deg^2 HeLMS field. These catalogues constitute the second Data Release (DR2) made in October 2013. A subset of these catalogues, which consists of bright sources extracted from Herschel-SPIRE observations completed by May 1, 2010 (covering ~ 74 deg^2) were released earlier in the first extensive Data Release (DR1) in March 2012. Two different methods are used to generate the point source catalogues, the SUSSEXtractor (SXT) point source extractor used in two earlier data releases (EDR and EDR2) and a new source detection and photometry method. The latter combines an iterative source detection algorithm, S...

  8. Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly accomplished by cold biasing the reservoir and using electrical heaters to provide the required control power. Using this method, the loop operating temperature can be controlled within +/- 0.5K. However, because of the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP has been carried out to investigate the effects on the LHP operation when the control temperature sensor is placed on the heat source instead of the reservoir. In these tests, the LHP reservoir is cold-biased and is heated by a control heater. Tests results show that it is feasible to use the heat source temperature for feedback control of the LHP operation. Using this method, the heat source temperature can be maintained within a tight range for moderate and high powers. At low powers, however, temperature oscillations may occur due to interactions among the reservoir control heater power, the heat source mass, and the heat output from the heat source. In addition, the heat source temperature could temporarily deviate from its set point during fast thermal transients. The implication is that more sophisticated feedback control algorithms need to be implemented for LHP transient operation when the heat source temperature is used for feedback control.

  9. Electromagnetic field generated by a modulated moving point source in a planarly layered waveguide

    Barrera-Figueroa, V.; Rabinovich, V. S.

    2016-04-01

    In the present work, we consider a modulated point source in an arbitrary motion in an isotropic planarly layered waveguide. The radiation field generated by this source is represented in the form of double oscillatory integrals in terms of the time and the frequency, depending on the large parameter λ. By means of the stationary phase method, we analyze, in the waveguide, the Doppler effect, the retarded time, and the Vavilov-Cherenkov radiation. Numerically, the problem of the moving source is approached by the method of spectral parameter power series.

  10. Calculation of dose decrease in a finite phantom of a 192Ir point source

    The purpose of this study was to calculate the dose decrease in a finite phantom of a 192Ir-point source by using a new algorithm based on field theory. The methods used included the phenomenological application of the principle ''mirror image of an electric point source in front of a dielectric semi-plateau'' to a radioactive source in a finite phantom results in a function to calculate the dose decrease near the surface. Measurements were done in a water phantom in three different experimental setups. To verify the calculated results Monte Carlo (MC) simulations of dose distribution of a 192Ir point source in 34x40x40 cm3 water were carried out. The strength of mirror source was found -0.103 of the real source. A lack scatter function was necessary to handle the dose decrease very close to surface. The measured and calculated dose values differed less than 0.9%. Both MC simulations and the new algorithm show the dose decrease near phantom surface with differences less than 2% between each other. The new algorithm based on field theory calculated the dose decrease of a 192Ir point source in a finite phantom with a very good agreement to measured and simulated data. A clinical example, which affects only a single planar boundary, is given by using molds in the treatment of skin tumors. This was calculated with the new algorithm presented in this article. The comparison with the common algorithm demonstrates the differences that might cause an overestimation of the dose, which probably leads an underdosing of the tumor. The general use of the new algorithm in brachytherapy where a variety of boundary shapes are encountered has to be verified seriously

  11. HerMES: point source catalogues from Herschel-SPIRE observations II

    Wang, L.; Viero, M.; Clarke, C.; Bock, J.; Buat, V.; Conley, A.; Farrah, D.; Guo, K.; Heinis, S.; Magdis, G.; Marchetti, L.; Marsden, G.; Norberg, P.; Oliver, S. J.; Page, M. J.; Roehlly, Y.; Roseboom, I. G.; Schulz, B.; Smith, A. J.; Vaccari, M.; Zemcov, M.

    2014-11-01

    The Herschel Multi-tiered Extragalactic Survey (HerMES) is the largest Guaranteed Time Key Programme on the Herschel Space Observatory. With a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling ˜380 deg2. In this paper, we present deep point source catalogues extracted from Herschel-Spectral and Photometric Imaging Receiver (SPIRE) observations of all HerMES fields, except for the later addition of the 270 deg2 HerMES Large-Mode Survey (HeLMS) field. These catalogues constitute the second Data Release (DR2) made in 2013 October. A sub-set of these catalogues, which consists of bright sources extracted from Herschel-SPIRE observations completed by 2010 May 1 (covering ˜74 deg2) were released earlier in the first extensive data release in 2012 March. Two different methods are used to generate the point source catalogues, the SUSSEXTRACTOR point source extractor used in two earlier data releases (EDR and EDR2) and a new source detection and photometry method. The latter combines an iterative source detection algorithm, STARFINDER, and a De-blended SPIRE Photometry algorithm. We use end-to-end Herschel-SPIRE simulations with realistic number counts and clustering properties to characterize basic properties of the point source catalogues, such as the completeness, reliability, photometric and positional accuracy. Over 500 000 catalogue entries in HerMES fields (except HeLMS) are released to the public through the HeDAM (Herschel Database in Marseille) website (http://hedam.lam.fr/HerMES).

  12. Point spread functions for earthquake source imaging: An interpretation based on seismic interferometry

    Nakahara, Hisashi; Haney, Matt

    2015-01-01

    Recently, various methods have been proposed and applied for earthquake source imaging, and theoretical relationships among the methods have been studied. In this study, we make a follow-up theoretical study to better understand the meanings of earthquake source imaging. For imaging problems, the point spread function (PSF) is used to describe the degree of blurring and degradation in an obtained image of a target object as a response of an imaging system. In this study, we formulate PSFs for earthquake source imaging. By calculating the PSFs, we find that waveform source inversion methods remove the effect of the PSF and are free from artifacts. However, the other source imaging methods are affected by the PSF and suffer from the effect of blurring and degradation due to the restricted distribution of receivers. Consequently, careful treatment of the effect is necessary when using the source imaging methods other than waveform inversions. Moreover, the PSF for source imaging is found to have a link with seismic interferometry with the help of the source-receiver reciprocity of Green’s functions. In particular, the PSF can be related to Green’s function for cases in which receivers are distributed so as to completely surround the sources. Furthermore, the PSF acts as a low-pass filter. Given these considerations, the PSF is quite useful for understanding the physical meaning of earthquake source imaging.

  13. Estimation of Non-point Source Pollution Loads Under Uncertain Information

    LI Ruzhong

    2008-01-01

    Many kinds of uncertainties are involved, such as random, fuzzy, grey, unascertained property and so on, in soil erosion process. To exactly predict the non-point source pollution loads, some uncertainties should be taken into consideration. Aiming at the deficiency of present blind number theory being helpless for fuzziness, a novel blind number, i.e. extended-blind number, was introduced by substituting a set of triangular fuzzy numbers (TFNs), ex-pressed as α-cuts, for interval values in present blind number, and the expected value of extended-blind number was also brought forward by referring to the current blind number theory. On the basis of denoting the parameters of Uni-versal Soil Loss Equation (USLE) as extended-blind parameters, a novel USLE model was established for quantita-tively evaluating soil erosion loss and non-point source pollution loads. As a case, the uncertain USLE was employed for predicting the soil erosion loss and non-point source pollution loads of absorbed nitrogen and phosphorus in a dis-trict in the Hangbu-Fengle River basin, in the upstream of Chaohu Lake watershed. The results show that it is feasible in theory to extend blind number into fuzzy environment and reliable on conclusion to apply extended-blind number theory for predicting non-point source pollution loads.

  14. The radiance from an isotropic point source in a multiple scattering medium

    Starting from the general solution of the equation of radiative transfer in the small-angle scattering approximation expressions are derived for the radiance and irradiance from an isotropically radiating point source in a multiple scattering medium. These expressions are exact and comparatively simple to evaluate numerically. Comparisons are made with the corresponding results obtained with an approximate theory. (author)

  15. Search for Cosmic Neutrino Point Sources with Four Year Data of the ANTARES Telescope

    Adrián-Martínez, S; Albert, A; André, M; Anghinolfi, M; Anton, G; Anvar, S; Ardid, M; Astraatmadja, T; Aubert, J -J; Baret, B; Basa, S; Bertin, V; Biagi, S; Bigongiari, C; Bogazzi, C; Bou-Cabo, M; Bouhou, B; Bouwhuis, M C; Brunner, J; Busto, J; Capone, A; Carloganu, C; Carr, J; Cecchini, S; Charif, Z; Charvis, Ph; Chiarusi, T; Circella, M; Coniglione, R; Core, L; Costantini, H; Coyle, P; Creusot, A; Curtil, C; De Bonis, G; Decowski, M P; Dekeyser, I; Deschamps, A; Distefano, C; Donzaud, C; Dornic, D; Dorosti, Q; Drouhin, D; Eberl, T; Emanuele, U; Enzenhöfer, A; Ernenwein, J -P; Escoffier, S; Fehn, K; Fermani, P; Ferri, M; Ferry, S; Flaminio, V; Folger, F; Fritsch, U; Fuda, J -L; Galatà, S; Gay, P; Geyer, K; Giacomelli, G; Giordano, V; Gleixner, A; Gómez-González, J P; Graf, K; Guillard, G; Hallewell, G; Hamal, M; van Haren, H; Heijboer, A J; Hello, Y; Hernández-Rey, J J; Herold, B; Hößl, J; Hsu, C C; de Jong, M; Kadler, M; Kalekin, O; Kappes, A; Katz, U; Kavatsyuk, O; Kooijman, P; Kopper, C; Kouchner, A; Kreykenbohm, I; Kulikovskiy, V; Lahmann, R; Lambard, G; Larosa, G; Lattuada, D; Leonora, E; Lefèvre, D; Lim, G; Presti, D Lo; Loehner, H; Loucatos, S; Louis, F; Mangano, S; Marcelin, M; Margiotta, A; Martínez-Mora, J A; Meli, A; Montaruli, T; Morganti, M; Motz, H; Neff, M; Nezri, E; Palioselitis, D; Păvălaş, G E; Payet, K; Petrovic, J; Piattelli, P; Popa, V; Pradier, T; Presani, E; Racca, C; Reed, C; Riccobene, G; Richter, R; Rivière, C; Robert, A; Roensch, K; Rostovtsev, A; Ruiz-Rivas, J; Rujoiu, M; Samtleben, D F E; Sapienza, P; Schmid, J; Schnabel, J; Schuller, J -P; Schüssler, F; Seitz, T; Shanidze, R; Simeone, F; Spies, A; Spurio, M; Steijger, J J M; Stolarczyk, Th; Sánchez-Losa, A; Taiuti, M; Tamburini, C; Trovato, A; Vallage, B; Vallée, C; Van Elewyck, V; Vecchi, M; Vernin, P; Visser, E; Wagner, S; Wijnker, G; Wilms, J; de Wolf, E; Yepes, H; Zaborov, D; Zornoza, J D; Zúñiga, J

    2012-01-01

    In this paper, a time integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an $E_{\

  16. Impacts by point and diffuse micropollutant sources on the stream water quality at catchment scale

    Petersen, Mette Fjendbo; Eriksson, Eva; Binning, Philip John;

    2012-01-01

    The water quality of surface waters is threatened by multiple anthropogenic pollutants and the large variety of pollutants challenges the monitoring and assessment of the water quality. The aim of this study was to characterize and quantify both point and diffuse sources of micropollutants...

  17. CPS: a continuous-point-source computer code for plume dispersion and deposition calculations

    Peterson, K.R.; Crawford, T.V.; Lawson, L.A.

    1976-05-21

    The continuous-point-source computer code calculates concentrations and surface deposition of radioactive and chemical pollutants at distances from 0.1 to 100 km, assuming a Gaussian plume. The basic input is atmospheric stability category and wind speed, but a number of refinements are also included.

  18. Effect of tissue inhomogeneity on dose distribution of point sources of low-energy electrons

    Perturbation in dose distributions of point sources of low-energy electrons at planar interfaces of cortical bone (CB) and red marrow (RM) was investigated experimentally and by Monte Carlo codes EGS and the TIGER series. Ultrathin LiF thermoluminescent dosimeters were used to measure the dose distributions of point sources of 204Tl and 147Pm in RM. When the point sources were at 12 mg/cm2 from a planar interface of CB and RM equivalent plastics, dose enhancement ratios in RM averaged over the region 0--12 mg/cm2 from the interface were measured to be 1.08±0.03 (SE) and 1.03±0.03 (SE) for 204Tl and 147Pm, respectively. The Monte Carlo codes predicted 1.05±0.02 and 1.01±0.02 for the two nuclides, respectively. However, EGS gave consistently 3% higher dose in the dose scoring region than the TIGER series when point sources of monoenergetic electrons up to 0.75 MeV energy were considered in the homogeneous RM situation or in the CB and RM heterogeneous situation. By means of the TIGER series, it was demonstrated that aluminum, which is normally assumed to be equivalent to CB in radiation dosimetry, leads to an overestimation of backscattering of low-energy electrons in soft tissue at a CB--soft-tissue interface by as much as a factor of 2

  19. Detection potential to point-like neutrino sources with the NEMO-km3 telescope

    Distefano, C.

    2006-01-01

    The NEMO Collaboration is conducting an R&D activity towards the construction of a Mediterranean km3 neutrino telescope. In this work, we present the results of Monte Carlo simulation studies on the capability of the proposed NEMO telescope to detect and identify point-like sources of high energy muon neutrinos.

  20. Another Look at the Income Elasticity of Non-Point Source Air Pollutants: A Semiparametric Approach

    Nilanjana Roy; G. Cornelis van Kooten

    2004-01-01

    In this paper, a semiparametric model is used to examine the relationship between pollution and income for three non-point source pollutants. Statistical tests reject the quadratic specification in favor of the semiparametric model in all cases. However, the results do not support the inverted-U hypothesis for the pollution-income relationship.

  1. Another Look at the Income Elasticity of Non-point Source Air Pollutants: A Semiparametric Approach

    Roy, N.; Kooten, van G.C.

    2004-01-01

    In this paper, a semiparametric model is used to examine the relationship between pollution and income for three non-point source pollutants. Statistical tests reject the quadratic specification in favor of the semiparametric model in all cases. However, the results do not support the inverted-U hyp

  2. Method for calculating non-point source pollution distribution in plain rivers

    Long-xi HAN

    2011-03-01

    Full Text Available The land area in river network is divided into some foursquare cells with certain scale for the demand of precision, proceeding from the physical mechanism of the rainfall-runoff and runoff pollution, the non-point source pollution from cells are estimated using the export coefficient of different land use types. According to the terrain of plain river network area and the positions of land cells and river network’s reaches, a principle is advanced which indicates that the non-point source pollution from a land cell should all get into its closest reach. A corresponding relationship between a single land cell and its pollution receiving reach can be obtained under the principle. In view of the above, a spatial distribution model of the rainfall-runoff and non-point source pollution in reaches of plain river network area is established. The method can provide a technological support for the further research on the dynamic effect on water quality which is caused by non-point source pollution.

  3. Impacts of DEM uncertainties on critical source areas identification for non-point source pollution control based on SWAT model

    Xu, Fei; Dong, Guangxia; Wang, Qingrui; Liu, Lumeng; Yu, Wenwen; Men, Cong; Liu, Ruimin

    2016-09-01

    The impacts of different digital elevation model (DEM) resolutions, sources and resampling techniques on nutrient simulations using the Soil and Water Assessment Tool (SWAT) model have not been well studied. The objective of this study was to evaluate the sensitivities of DEM resolutions (from 30 m to 1000 m), sources (ASTER GDEM2, SRTM and Topo-DEM) and resampling techniques (nearest neighbor, bilinear interpolation, cubic convolution and majority) to identification of non-point source (NPS) critical source area (CSA) based on nutrient loads using the SWAT model. The Xiangxi River, one of the main tributaries of Three Gorges Reservoir in China, was selected as the study area. The following findings were obtained: (1) Elevation and slope extracted from the DEMs were more sensitive to DEM resolution changes. Compared with the results of the 30 m DEM, 1000 m DEM underestimated the elevation and slope by 104 m and 41.57°, respectively; (2) The numbers of subwatersheds and hydrologic response units (HRUs) were considerably influenced by DEM resolutions, but the total nitrogen (TN) and total phosphorus (TP) loads of each subwatershed showed higher correlations with different DEM sources; (3) DEM resolutions and sources had larger effects on CSAs identifications, while TN and TP CSAs showed different response to DEM uncertainties. TN CSAs were more sensitive to resolution changes, exhibiting six distribution patterns at all DEM resolutions. TP CSAs were sensitive to source and resampling technique changes, exhibiting three distribution patterns for DEM sources and two distribution patterns for DEM resampling techniques. DEM resolutions and sources are the two most sensitive SWAT model DEM parameters that must be considered when nutrient CSAs are identified.

  4. Reprint of : Dynamics of a quantum wave emitted by a decaying and evanescent point source

    Delgado, F.; Muga, J. G.

    2016-08-01

    We put forward a model that describes a decaying and evanescent point source of non-interacting quantum waves in 1D. This point-source assumption allows for a simple description that captures the essential aspects of the dynamics of a wave traveling through a classically forbidden region without the need to specify the details of the inner region. The dynamics of the resulting wave is examined and several characteristic times are identified. One of them generalizes the tunneling time-scale introduced by Büttiker and Landauer and it characterizes the arrival of the maximum of the wave function. Diffraction in time and deviations from exponential decay are also studied. Here we show that there exists an optimal injection frequency and detection point for the observation of these two quantum phenomena.

  5. The Geometric Calibration of the Planck satellite using point-source observations

    Harrison, D L

    2005-01-01

    The geometric calibration of the Planck satellite is investigated, specifically those parameters which require the use of the science data for their extraction. Methods for the recovery of these geometric-calibration parameters from point source detections in the science data are presented, together with the accuracies which may be achieved. These methods apply to the a posteriori evaluation of these parameters using all the mission data, and may be incorporated into the initial stages of the construction of the Planck final compact source catalogue. It is found that this process achieves the pointing requirements, provided that the geometric-calibration parameters vary only slowly in time. Indeed the errors in the pointing reconstruction due to the geometric calibration parameters may be seen to approach those due to the star tracker.

  6. Comparative Evaluation of Pulsewidth Modulation Strategies for Z-Source Neutral-Point-Clamped Inverter

    Loh, P.C.; Blaabjerg, Frede; Wong, C.P.

    2007-01-01

    modulation (PWM) strategies for controlling the Z-source NPC inverter. While developing the PWM techniques, attention has been devoted to carefully derive them from a common generic basis for improved portability, easier implementation, and most importantly, assisting readers in understanding all concepts......Z-source neutral-point-clamped (NPC) inverter has recently been proposed as an alternative three-level buck-boost power conversion solution with an improved output waveform quality. In principle, the designed Z-source inverter functions by selectively "shooting through" its power sources, coupled...... to the inverter using two unique Z-source impedance networks, to boost the inverter three-level output waveform. Proper modulation of the new inverter would therefore require careful integration of the selective shoot-through process to the basic switching concepts to achieve maximal voltage...

  7. A spatial model to aggregate point-source and nonpoint-source water-quality data for large areas

    White, D.A.; Smith, R.A.; Price, C.V.; Alexander, R.B.; Robinson, K.W.

    1992-01-01

    More objective and consistent methods are needed to assess water quality for large areas. A spatial model, one that capitalizes on the topologic relationships among spatial entities, to aggregate pollution sources from upstream drainage areas is described that can be implemented on land surfaces having heterogeneous water-pollution effects. An infrastructure of stream networks and drainage basins, derived from 1:250,000-scale digital-elevation models, define the hydrologic system in this spatial model. The spatial relationships between point- and nonpoint pollution sources and measurement locations are referenced to the hydrologic infrastructure with the aid of a geographic information system. A maximum-branching algorithm has been developed to simulate the effects of distance from a pollutant source to an arbitrary downstream location, a function traditionally employed in deterministic water quality models. ?? 1992.

  8. Radiant fluxes from various off-axis point sources incident on a circular disk.

    Tryka, Stanislaw

    2013-09-20

    A general multidomain integral formula is presented for calculating fluxes of radiation striking a circular disk from various off-axis point source types embedded in an attenuating or nonattenuating medium. This formula is expressed by double line integrals of radiant intensity and sine functions with respect to the polar and horizontal angles determining the angular distribution of the emitted radiation. The formula reduces to single line integral expressions when radiation does not depend on the horizontal angle and is directly applicable for calculating fluxes of revolutional symmetry around the optical axis of the source perpendicular to the disk. The applicability of this reduced formula is tested by computing radiant fluxes from Lambertian and Gaussian point sources using a simple numerical procedure for single integrals. The computed data are illustrated graphically, tabulated, and validated using OSLO. Finally, the accuracy, similarity, and applicability of the results provided by the integral formula and the OSLO program are analyzed. Numerical results have shown the effectiveness of the presented formulas for calculating radiant fluxes from various on- and off-axis point sources passing through a nonattenuating or attenuating homogeneous isotropic media and incident on a circular disk perpendicular to optical axes of these sources. Practical applications of these formulas include optical sensing and metrology, optical coupling, fiber optic for biomedical measurements, and creative lighting design. PMID:24085174

  9. Detection of point sources on two-dimensional images based on peaks

    Lopez-Caniego, M; Sanz, J L; Barreiro, R B

    2005-01-01

    This article considers the detection of point sources in two dimensional astronomical images. The detection scheme we propose is based on peak statistics. We discuss the example of the detection of far galaxies in Cosmic Microwave Background experiments throughout the paper, although the method we present is totally general and can be used in many other fields of data analysis. We assume sources with a Gaussian profile --that is a fair approximation of the profile of a point source convolved with the detector beam in microwave experiments-- on a background modeled by a homogeneous and isotropic Gaussian random field characterized by a scale-free power spectrum. Point sources are enhanced with respect to the background by means of linear filters. After filtering, we identify local maxima and apply our detection scheme, a Neyman-Pearson detector that defines our region of acceptance based on the a priori pdf of the sources and the ratio of number densities. We study the different performances of some linear fil...

  10. HerMES: point source catalogues from deep Herschel-SPIRE observations

    Smith, A J; Oliver, S J; Auld, R; Bock, J; Brisbin, D; Burgarella, D; Chanial, P; Chapin, E; Clements, D L; Conversi, L; Cooray, A; Dowell, C D; Eales, S; Farrah, D; Franceschini, A; Glenn, J; Griffin, M; Ivison, R J; Mortier, A M J; Page, M J; Papageorgiou, A; Pearson, C P; Pérez-Fournon, I; Pohlen, M; Rawlings, J I; Raymond, G; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Savage, R; Scott, Douglas; Seymour, N; Symeonidis, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Vigroux, L; Ward, R; Wright, G; Zemcov, M

    2011-01-01

    We describe the generation of single-band point source catalogues from submillimetre Herschel-SPIRE observations taken as part of the Science Demonstration Phase of the Herschel Multi-tiered Extragalactic Survey (HerMES). Flux densities are found by means of peak-finding and the fitting of a Gaussian point-response function. With highly-confused images, careful checks must be made on the completeness and flux density accuracy of the detected sources. This is done by injecting artificial sources into the images and analysing the resulting catalogues. Measured flux densities at which 50 per cent of injected sources result in good detections at (250, 350, 500) {\\mu}m range from (11.6, 13.2, 13.1) mJy to (25.7, 27.1, 35.8) mJy, depending on the depth of the observation (where a `good' detection is taken to be one with positional offset less than one full-width half-maximum of the point-response function, and with the measured flux density within a factor of 2 of the flux density of the injected source). This pape...

  11. Tackling non-point source water pollution in British Columbia : an action plan

    NONE

    1999-03-01

    British Columbia`s approach to water quality management is discussed. The BC efforts include regulating `end of pipe` point discharges from industrial and municipal outfalls. The major remaining cause of water pollution is from non-point sources (NPS). NPS water pollution is caused by the release of pollutants from different and diffuse sources, mostly unregulated and associated with urbanization, agriculture and other forms of land development. The importance of dealing with such problems on an immediate basis to avoid a decline in water quality in the province is emphasized. Major sources of water pollution in British Columbia include: land development, agriculture, storm water runoff, onsite sewage systems, forestry, atmospheric deposition, and marine activities. 3 tabs.

  12. Quantum limit for two-dimensional resolution of two incoherent optical point sources

    Ang, Shan Zheng; Tsang, Mankei

    2016-01-01

    We obtain the multiple-parameter quantum Cram\\'er-Rao bound for estimating the Cartesian components of the centroid and separation of two incoherent optical point sources using an imaging system with finite spatial bandwidth. Under quite general and realistic assumptions on the point-spread function of the imaging system, and for weak source strengths, we show that the Cram\\'er-Rao bounds for the x and y components of the separation are independent of the values of those components, which may be well-below the conventional Rayleigh resolution limit. We also propose two linear optics-based measurement methods that approach the quantum bound for the estimation of the Cartesian components of the separation once the centroid has been located. One of the methods is an interferometric scheme that approaches the quantum bound for sub-Rayleigh separations. The other method uses fiber coupling to attain the bound regardless of the distance between the two sources.

  13. Point source detection performance of Hard X-ray Modulation Telescope imaging observation

    Huo, Zhuoxi; Li, Xiaobo; Zhou, Jianfeng

    2015-01-01

    The Hard X-ray Modulation Telescope (HXMT) will perform an all-sky survey in hard X-ray band as well as deep imaging of a series of small sky regions. We expect various compact objects to be detected in these imaging observations. Point source detection performance of HXMT imaging observation depends not only on the instrument but also on its data analysis since images are reconstructed from HXMT observed data with numeric methods. Denoising technique plays an import part in HXMT imaging data analysis pipeline alongside with demodulation and source detection. In this paper we have implemented several methods for denoising HXMT data and evaluated the point source detection performances in terms of sensitivities and location accuracies. The results show that direct demodulation with 1-fold cross correlation should be the default reconstruction and regularization methods, although both sensitivity and location accuracy could be further imporved by selecting and tuning numerical methods in data analysis of HXMT i...

  14. The use of molecular sieves to produce point sources of radioactivity

    We have used commercially available molecular sieves (zeolites) to adsorb radioactivity onto small (∼2.1 mm diameter) beads for use in various applications in nuclear medicine. Soaking the beads in [99mTc]-NaTcO4 solution of ∼3 GBq ml-1 for 1-2 min can produce point sources containing 3-6 MBq total. Radioactive uptake was strongly dependent on bead size. We have employed the sources for gamma camera uniformity and as point source markers for interactive identification of anatomical landmarks. Due to their small size, relatively high uptake and negligible scattering contribution they provide excellent devices with which to measure spatial resolution, detector uniformity and energy resolution. The molecular sieves are inexpensive and readily usable with both single photon and positron emitting radionuclides. (note)

  15. Long term optical variability of bright X-ray point sources in elliptical galaxies

    We present long term optical variability studies of bright X-ray sources in four nearby elliptical galaxies with the Chandra Advanced CCD Imaging Spectrometer array (ACIS-S) and observations from the Hubble Space Telescope (HST) Advanced Camera for Surveys. Out of the 46 bright (X-ray counts > 60) sources that are in the common field of view of the Chandra and HST observations, 34 of them have potential optical counterparts, while the rest of them are optically dark. After taking into account systematic errors, estimated using optical sources in the field as a reference, we find that four of the X-ray sources (three in NGC 1399 and one in NGC 1427) have variable optical counterparts at a high level of significance. The X-ray luminosities of these sources are ∼ 1038 erg s−1 and are also variable on similar time scales. The optical variability implies that the optical emission is associated with the X-ray source itself rather than being the integrated light from a host globular cluster. For one source, the change in optical magnitude is > 0.3, which is one of the highest reported for this class of X-ray sources and this suggests that the optical variability is induced by the X-ray activity. However, the optically variable sources in NGC 1399 have been reported to have blue colors (g — z > 1). All four sources have been detected in the infrared (IR) by Spitzer as point sources, and their ratios of 5.8 to 3.6 μm flux are > 0.63, indicating that their IR spectra are like those of Active Galactic Nuclei (AGNs). While spectroscopic confirmation is required, it is likely that all four sources are background AGNs. We find none of the X-ray sources having optical/IR colors different from AGNs to be optically variable

  16. Adjacent segment disease.

    Virk, Sohrab S; Niedermeier, Steven; Yu, Elizabeth; Khan, Safdar N

    2014-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Understand the forces that predispose adjacent cervical segments to degeneration. 2. Understand the challenges of radiographic evaluation in the diagnosis of cervical and lumbar adjacent segment disease. 3. Describe the changes in biomechanical forces applied to adjacent segments of lumbar vertebrae with fusion. 4. Know the risk factors for adjacent segment disease in spinal fusion. Adjacent segment disease (ASD) is a broad term encompassing many complications of spinal fusion, including listhesis, instability, herniated nucleus pulposus, stenosis, hypertrophic facet arthritis, scoliosis, and vertebral compression fracture. The area of the cervical spine where most fusions occur (C3-C7) is adjacent to a highly mobile upper cervical region, and this contributes to the biomechanical stress put on the adjacent cervical segments postfusion. Studies have shown that after fusion surgery, there is increased load on adjacent segments. Definitive treatment of ASD is a topic of continuing research, but in general, treatment choices are dictated by patient age and degree of debilitation. Investigators have also studied the risk factors associated with spinal fusion that may predispose certain patients to ASD postfusion, and these data are invaluable for properly counseling patients considering spinal fusion surgery. Biomechanical studies have confirmed the added stress on adjacent segments in the cervical and lumbar spine. The diagnosis of cervical ASD is complicated given the imprecise correlation of radiographic and clinical findings. Although radiological and clinical diagnoses do not always correlate, radiographs and clinical examination dictate how a patient with prolonged pain is treated. Options for both cervical and lumbar spine ASD include fusion and/or decompression. Current studies are encouraging regarding the adoption of arthroplasty in spinal surgery, but more long

  17. A 24 Micron Point Source Catalog of the Galactic Plane from Spitzer/MIPSGAL

    Gutermuth, Robert A

    2014-01-01

    In this contribution, we describe the applied methods to construct a 24 micron based point source catalog derived from the image data of the MIPSGAL 24 micron Galactic Plane Survey and the corresponding data products. The high quality catalog product contains 933,818 sources, with a total of 1,353,228 in the full archive catalog. The source tables include positional and photometric informa- tion derived from the 24 micron images, source quality and confusion flags and coun- terpart photometry from matched 2MASS, GLIMPSE, and WISE point sources. Completeness decay data cubes are constructed at 1 arcminute angular resolution that describe the varying background levels over the MIPSGAL field and the ability to extract sources of a given magnitude from this background. The completeness decay cubes are included in the set of data products. We present the results of our efforts to verify the astrometric and photometric calibration of the catalog, and present several analyses of minor anomalies in these measurements...

  18. Color and Variability Characteristics of Point Sources in the Faint Sky Variability Survey

    Huber, M E; Everett, M E; Howell, S B

    2005-03-07

    The authors present an analysis of the color and variability characteristics for point sources in the Faint Sky Variability Survey (FSVS). The FSVS cataloged {approx} 23 square degrees in BVI filters from {approx} 16-24 mag to investigate variability in faint sources at moderate to high Galactic latitudes. Point source completeness is found to be >83% for a selected representative sample (V - 17.5-22.0 mag, B-V = 0.0-1.5) containing both photometric B, V detections and 80% of the time-sampled V data available compared to a basic internal source completeness of 99%. Multi-epoch (10-30) observations in V spanning minutes to years modeled by light curve simulations reveal amplitude sensitivities to {approx} 0.015-0.075 mag over a representative V = 18-22 mag range. Periodicity determinations appear viable to time-scales of an order 1 day or less using the most sampled fields ({approx} 30 epochs). The fraction of point sources is found to be generally variable at 5-8% over V = 17.5-22.0 mag. For V brighter than 19 mag, the variable population is dominated by low amplitude (< 0.05 mag) and blue (B-V < 0.35) sources, possibly representing a population of {gamma} Doradus stars. Overall, the dominant population of variable sources are bluer than B-V = 0.65 and have Main Sequence colors, likely reflecting larger populations of RR Lyrae, SX Phe, {gamma} Doradus, and W UMa variables.

  19. A Statistical Analysis of Point-like Sources in the Chandra Galactic Center Survey

    J.F.Wu; S.N.Zhang; F.J.Lu; Y.K.Jin

    2007-01-01

    The Chandra Galactic Center Survey detected ~ 800 X-ray point-like sources in the 2°× 0.8° sky region around the Galactic Center. We study the spatial and luminosity distributions of these sources according to their spectral properties. Fourteen bright sources detected are used to fit jointly an absorbed power-law model, from which the power-law photon index is determined to be ~2.5. Assuming that all other sources have the same power-law form, the relation between hardness ratio and HI column density NH is used to estimate the NH values for all sources. Monte Carlo simulations show that these sources are more likely concentrated in the Galactic center region, rather than distributed throughout the Galactic disk. We also find that the luminosities of the sources are positively correlated with their HI column densities, i.e., a more luminous source has a higher HI column density. From this relation, we suggest that the X-ray luminosity comes from the interaction between an isolated old neutron star and interstellar medium (mainly dense molecular clouds). Using the standard Bondi accretion theory and the statistical information of molecular clouds in the Galactic center, we confirm this positive correlation and calculate the luminosity range in this scenario,which is consistent with the observation (1032 - 1035 erg s-1).

  20. Overview of on-farm bioremediation systems to reduce the occurrence of point source contamination.

    De Wilde, Tineke; Spanoghe, Pieter; Debaer, Christof; Ryckeboer, Jaak; Springael, Dirk; Jaeken, Peter

    2007-02-01

    Contamination of ground and surface water puts pressure on the use of pesticides. Pesticide contamination of water can often be linked to point sources rather than to diffuse sources. Examples of such point sources are areas on farms where pesticides are handled and filled into sprayers, and where sprayers are cleaned. To reduce contamination from these point sources, different kinds of bioremediation system are being researched in various member states of the EU. Bioremediation is the use of living organisms, primarily microorganisms, to degrade the environmental contaminants into less toxic forms. The systems available for biocleaning of pesticides vary according to their shape and design. Up till now, three systems have been extensively described and reported: the biobed, the Phytobac and the biofilter. Most of these constructions are excavations or different sizes of container filled with biological material. Typical overall clean-up efficiency exceeds 95%, realising even more than 99% in many cases. This paper provides an overview of the state of the art of these bioremediation systems and discusses their construction, efficiency and drawbacks. PMID:17199234

  1. The impact of point source subtraction residuals on 21 cm Epoch of Reionization estimation

    Trott, Cathryn M; Tingay, Steven J

    2012-01-01

    Precise subtraction of foreground sources is crucial for detecting and estimating 21cm HI signals from the Epoch of Reionization (EoR). We quantify how imperfect point source subtraction due to limitations of the measurement dataset yields structured residual signal in the dataset. We use the Cramer-Rao lower bound, as a metric for quantifying the precision with which a parameter may be measured, to estimate the residual signal in a visibility dataset due to imperfect point source subtraction. We then propagate these residuals into two metrics of interest for 21cm EoR experiments - the angular and two-dimensional power spectrum - using a combination of full analytic covariant derivation, analytic variant derivation, and covariant Monte Carlo simulations. This methodology differs from previous work in two ways: (1) it uses information theory to set the point source position error, rather than assuming a global root-mean-square error, and (2) it describes a method for propagating the errors analytically, thereb...

  2. Global Pollution of Surface Waters from Point and Nonpoint Sources of Nitrogen

    G. van Drecht

    2001-01-01

    Full Text Available Global 0.5- by 0.5-degree resolution estimates are presented on the fate of nitrogen (N stemming from point and nonpoint sources, including plant uptake, denitrification, leaching from the rooting zone, rapid flow through shallow groundwater, and slow flow through deep groundwater to riverine systems. Historical N inputs are used to describe the N flows in groundwater. For nonpoint N sources (agricultural and natural ecosystems, calculations are based on local hydrology, climate, geology, soils, climate and land use combined with data for 1995 on crop production, N inputs from N fertilizers and animal manure, and estimates for ammonia emissions, biological N fixation, and N deposition. For point sources, our estimates are based on population densities and human N emissions, sanitation, and treatment. The results provide a first insight into the magnitude of the N losses from soil-plant systems and point sources in various parts of the world, and the fate of N during transport in atmosphere, groundwater, and surface water. The contribution to the river N load by anthropogenic N pollution is dominant in many river basins in Europe, Asia, and North Africa. Our model results explain much of the variation in measured N export from different world river basins.

  3. Induction heating pure vapor source of high temperature melting point materials on electron cyclotron resonance ion source

    Multicharged ions that are needed are produced from solid pure material with high melting point in an electron cyclotron resonance ion source. We develop an evaporator by using induction heating (IH) with multilayer induction coil, which is made from bare molybdenum or tungsten wire without water cooling and surrounding the pure vaporized material. We optimize the shapes of induction coil and vaporized materials and operation of rf power supply. We conduct experiment to investigate the reproducibility and stability in the operation and heating efficiency. IH evaporator produces pure material vapor because materials directly heated by eddy currents have no contact with insulated materials, which are usually impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10-4-10-3 Pa. We measure the temperature of the vaporized materials with different shapes, and compare them with the result of modeling. We estimate the efficiency of the IH vapor source. We are aiming at the evaporator's higher melting point material than that of iron.

  4. Model Predictive Control of Z-source Neutral Point Clamped Inverter

    Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

    2011-01-01

    inductor current, capacitor voltage as well as switching frequency, transient response are all regulated as subjecting to constraints of this control method. The quality of output waveform, stability of impedance-network, level constraint of variable switching frequency as well as robustness of transient......This paper presents Model Predictive Control (MPC) of Z-source Neutral Point Clamped (NPC) inverter. For illustration, current control of Z-source NPC grid-connected inverter is analyzed and simulated. With MPC’s advantage of easily including system constraints, load current, impedance network...... response are obtained at the same time with a formulated Z-source NPC inverter network model. Operation steady state and transient state simulation results of MPC are going to be presented, which shows good reference tracking ability of this method. It provides new control method for Z-source NPC inverter...

  5. An updated list of AGILE bright γ-ray sources and their variability in pointing mode

    Verrecchia, F.; Pittori, C.; Chen, A. W.; Bulgarelli, A.; Tavani, M.; Lucarelli, F.; Giommi, P.; Vercellone, S.; Pellizzoni, A.; Giuliani, A.; Longo, F.; Barbiellini, G.; Trifoglio, M.; Gianotti, F.; Argan, A.; Antonelli, L. A.; Caraveo, P.; Cardillo, M.; Cattaneo, P. W.; Cocco, V.; Colafrancesco, S.; Contessi, T.; Costa, E.; Del Monte, E.; De Paris, G.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Evangelista, Y.; Fanari, G.; Feroci, M.; Ferrari, A.; Fiorini, M.; Fornari, F.; Fuschino, F.; Froysland, T.; Frutti, M.; Galli, M.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Liello, F.; Lipari, P.; Mattaini, E.; Marisaldi, M.; Mastropietro, M.; Mauri, A.; Mauri, F.; Mereghetti, S.; Morelli, E.; Moretti, E.; Morselli, A.; Pacciani, L.; Perotti, F.; Piano, G.; Picozza, P.; Pilia, M.; Pontoni, C.; Porrovecchio, G.; Prest, M.; Primavera, R.; Pucella, G.; Rapisarda, M.; Rappoldi, A.; Rossi, E.; Rubini, A.; Sabatini, S.; Santolamazza, P.; Soffitta, P.; Stellato, S.; Striani, E.; Tamburelli, F.; Traci, A.; Trois, A.; Vallazza, E.; Vittorini, V.; Zanello, D.; Salotti, L.; Valentini, G.

    2013-10-01

    Aims: We present a variability study of a sample of bright γ-ray(30 Mev-50 Gev) sources. This sample is an extension of the first AGILE catalogue of γ-ray sources (1AGL), obtained using the complete set of AGILE observations in pointing mode performed during a 2.3 year period from July 9, 2007 until October 30, 2009. Methods: The dataset of AGILE pointed observations covers a long time interval and its γ-ray data archive is useful for monitoring studies of medium-to-high brightness γ-ray sources. In the analysis reported here, we used data obtained with an improved event filter that covers a wider field of view, on a much larger (about 27.5 months) dataset, integrating data on observation block time scales, which mostly range from a few days to thirty days. Results: The data processing resulted in a better characterized source list than 1AGL was, and includes 54 sources, 7 of which are new high galactic latitude (|BII| ≥ 5) sources, 8 are new sources on the galactic plane, and 20 sources from the previous catalogue with revised positions. Eight 1AGL sources (2 high-latitude and 6 on the galactic plane) were not detected in the final processing either because of low OB exposure and/or due to their position in complex galactic regions. We report the results in a catalogue of all the detections obtained in each single OB, including the variability results for each of these sources. In particular, we found that 12 sources out of 42 or 11 out of 53 are variable, depending on the variability index used, where 42 and 53 are the number of sources for which these indices could be calculated. Seven of the 11 variable sources are blazars, the others are Crab pulsar+nebula, LS I +61°303, Cyg X-3, and 1AGLR J2021+4030. Table 5 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A137

  6. Detection of trace gas emissions from point sources using shortwave infrared imaging spectrometry

    Thorpe, A. K.; Roberts, D. A.; Dennison, P. E.; Bradley, E. S.; Funk, C. C.

    2011-12-01

    Existing spaceborne remote sensing provides an effective means of detecting continental-scale variation in trace gas concentrations, but does not permit mapping of local emissions from point sources. Point source emissions of methane (CH4), nitrous oxide (N2O) and particulates, often associated with combustion and carbon dioxide (CO2) emissions, have significant impacts on air quality. Using Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) data and a cluster-tuned matched filter technique, we have mapped local CH4, N2O and CO2 emissions from terrestrial sources in the Los Angeles basin. CH4 anomalies were in close proximity to known and probable emission sources, including hydrocarbon storage tanks and gas flares. Multiple N2O and CH4 anomalies were detected at a wastewater treatment facility, while CH4 and CO2 anomalies were also identified at a large oil refinery. We discuss ongoing efforts to estimate CH4 concentrations using radiative transfer modeling and potential application of this technique to additional trace gasses with distinct absorption features. This method could be applied to data from existing airborne sensors and planned satellite missions like HyspIRI, thereby improving high resolution mapping of trace gasses and better constraining local sources.

  7. Quantification of bioluminescence images of point source objects using diffusion theory models

    A simple approach for estimating the location and power of a bioluminescent point source inside tissue is reported. The strategy consists of using a diffuse reflectance image at the emission wavelength to determine the optical properties of the tissue. Following this, bioluminescence images are modelled using a single point source and the optical properties from the reflectance image, and the depth and power are iteratively adjusted to find the best agreement with the experimental image. The forward models for light propagation are based on the diffusion approximation, with appropriate boundary conditions. The method was tested using Monte Carlo simulations, Intralipid tissue-simulating phantoms and ex vivo chicken muscle. Monte Carlo data showed that depth could be recovered within 6% for depth 4-12 mm, and the corresponding relative source power within 12%. In Intralipid, the depth could be estimated within 8% for depth 4-12 mm, and the relative source power, within 20%. For ex vivo tissue samples, source depths of 4.5 and 10 mm and their relative powers were correctly identified

  8. H2O and CO emission towards IRAS point sources in regions of star formation.

    Fiegle, K.; Wouterloot, J. G. A.; Brand, J.

    H2O masers are good indicators for the presence of star formation in molecular clouds. Wouterloot and Walmsley (1986) showed that all H2O maser sources in regions of star formation are associated with IRAS point sources with specific colours, so that the IRAS Point Source Catalog can be used to select maser candidates. The authors have searched for 22 GHz H2O maser emission using the 100-m radiotelescope in Effelsberg and the 32-m radiotelescope in Medicina, Italy. The total sample of sources consists of 1390 objects, selected according to their IRAS colour indices. Spectra and line parameters are given in Wouterloot et al. (1993). The H2O data are compared with results of observations of 12CO (1-0) (and of 12CO (2-1) and 12CO(3-2) in some cases) towards a large fraction of these sources, made with the 30-m IRAM, 15-m SEST, or 3-m KOSMA telescopes.

  9. Outdoor air pollution in close proximity to a continuous point source

    Klepeis, Neil E.; Gabel, Etienne B.; Ott, Wayne R.; Switzer, Paul

    Data are lacking on human exposure to air pollutants occurring in ground-level outdoor environments within a few meters of point sources. To better understand outdoor exposure to tobacco smoke from cigarettes or cigars, and exposure to other types of outdoor point sources, we performed more than 100 controlled outdoor monitoring experiments on a backyard residential patio in which we released pure carbon monoxide (CO) as a tracer gas for continuous time periods lasting 0.5-2 h. The CO was emitted from a single outlet at a fixed per-experiment rate of 120-400 cc min -1 (˜140-450 mg min -1). We measured CO concentrations every 15 s at up to 36 points around the source along orthogonal axes. The CO sensors were positioned at standing or sitting breathing heights of 2-5 ft (up to 1.5 ft above and below the source) and at horizontal distances of 0.25-2 m. We simultaneously measured real-time air speed, wind direction, relative humidity, and temperature at single points on the patio. The ground-level air speeds on the patio were similar to those we measured during a survey of 26 outdoor patio locations in 5 nearby towns. The CO data exhibited a well-defined proximity effect similar to the indoor proximity effect reported in the literature. Average concentrations were approximately inversely proportional to distance. Average CO levels were approximately proportional to source strength, supporting generalization of our results to different source strengths. For example, we predict a cigarette smoker would cause average fine particle levels of approximately 70-110 μg m -3 at horizontal distances of 0.25-0.5 m. We also found that average CO concentrations rose significantly as average air speed decreased. We fit a multiplicative regression model to the empirical data that predicts outdoor concentrations as a function of source emission rate, source-receptor distance, air speed and wind direction. The model described the data reasonably well, accounting for ˜50% of the log

  10. SEARCH FOR COSMIC NEUTRINO POINT SOURCES WITH FOUR YEARS OF DATA FROM THE ANTARES TELESCOPE

    In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E –2ν spectrum, these flux limits are at 1-10 ×10–8 GeV cm–2 s–1 for declinations ranging from –90° to 40°. Limits for specific models of RX J1713.7–3946 and Vela X, which include information on the source morphology and spectrum, are also given.

  11. X-Rays Beware: The Deepest Chandra Catalogue of Point Sources in M31

    Vulic, N; Barmby, P

    2016-01-01

    This study represents the most sensitive Chandra X-ray point source catalogue of M31. Using 133 publicly available Chandra ACIS-I/S observations totalling ~1 Ms, we detected 795 X-ray sources in the bulge, northeast, and southwest fields of M31, covering an area of approximately 0.6 deg$^{2}$, to a limiting unabsorbed 0.5-8.0 keV luminosity of $10^{34}$ erg/s. In the inner bulge, where exposure is approximately constant, X-ray fluxes represent average values because they were determined from many observations over a long period of time. Similarly, our catalogue is more complete in the bulge fields since monitoring allowed more transient sources to be detected. The catalogue was cross-correlated with a previous XMM-Newton catalogue of M31's $D_{25}$ isophote consisting of 1948 X-ray sources, with only 979 within the field of view of our survey. We found 387 (49%) of our Chandra sources (352 or 44% unique sources) matched to within 5 arcsec of 352 XMM-Newton sources. Combining this result with matching done to ...

  12. A proton point source produced by laser interaction with cone-top-end target

    In this paper, we propose a proton point source by the interaction of laser and cone-top-end target and investigate it by two-dimensional particle-in-cell (2D-PIC) simulations as the proton point sources are well known for higher spatial resolution of proton radiography. Our results show that the relativistic electrons are guided to the rear of the cone-top-end target by the electrostatic charge-separation field and self-generated magnetic field along the profile of the target. As a result, the peak magnitude of sheath field at the rear surface of cone-top-end target is higher compared to common cone target. We test this scheme by 2D-PIC simulation and find the result has a diameter of 0.79λ0, an average energy of 9.1 MeV and energy spread less than 35%.

  13. Simulation of ultrasonic surface waves with multi-Gaussian and point source beam models

    Zhao, Xinyu [Center for NDE, Iowa State University, Ames, IA, 50011, USA and Dept. of Mechanical Eng., Beijing Institute of Technology, Beijing, 100081 (China); Schmerr, Lester W. Jr.; Li, Xiongbing [Center for NDE, Iowa State University, Ames, IA, 50011 (United States); Sedov, Alexander [Dept. of Mechanical Eng., Lakehead University, Thunder Bay, ON (Canada)

    2014-02-18

    In the past decade, multi-Gaussian beam models have been developed to solve many complicated bulk wave propagation problems. However, to date those models have not been extended to simulate the generation of Rayleigh waves. Here we will combine Gaussian beams with an explicit high frequency expression for the Rayleigh wave Green function to produce a three-dimensional multi-Gaussian beam model for the fields radiated from an angle beam transducer mounted on a solid wedge. Simulation results obtained with this model are compared to those of a point source model. It is shown that the multi-Gaussian surface wave beam model agrees well with the point source model while being computationally much more efficient.

  14. Spitzer Infrared Spectrographic point source classification in the Small Magellanic Cloud

    Ruffle, Paul M E; Jones, O C; Sloan, G C; Kraemer, K E; Woods, Paul M; Boyer, M L; Srinivasan, S; Antoniou, V; Lagadec, E; Matsuura, M; McDonald, I; Oliveira, J M; Sargent, B A; Sewilo, M; Szczerba, R; van Loon, J Th; Volk, K; Zijlstra, A A

    2015-01-01

    The Magellanic clouds are uniquely placed to study the stellar contribution to dust emission. Individual stars can be resolved in these systems even in the mid-infrared, and they are close enough to allow detection of infrared excess caused by dust.We have searched the Spitzer Space Telescope data archive for all Infrared Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) and found that 209 Infrared Array Camera (IRAC) point sources within the footprint of the Surveying the Agents of Galaxy Evolution in the Small Magellanic Cloud (SAGE-SMC) Spitzer Legacy programme were targeted, within a total of 311 staring mode observations. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information. We find 58 asymptotic giant branch (AGB) stars, 51 young stellar objects (YSOs), 4 post-AGB objects, 22 Red Super...

  15. VizieR Online Data Catalog: LMC point source classification in SAGE-Spec (Woods+, 2011)

    Woods, P. M.; Oliveira, J. M.; Kemper, F.; van Loon, J. T.; Sargent, B. A.; Matsuura, M.; Szczerba, R.; Volk, K.; Zijlstra, A. A.; Sloan, G. C.; Lagadec, E.; McDonald, I.; Jones, O.; Gorjian, V.; Kraemer, K. E.; Gielen, C.; Meixner, M.; Blum, R. D.; Sewilo, M.; Riebel, D.; Shiao, B.; Chen, C.-H. R.; Boyer, M. L.; Indebetouw, R.; Antoniou, V.; Bernard, J.-P.; Cohen, M.; Dijkstra, C.; Galametz, M.; Galliano, F.; Gordon, K. D.; Harris, J.; Hony, S.; Hora, J. L.; Kawamura, A.; Lawton, B.; Leisenring, J. M.; Madden, S.; Marengo, M.; McGuire, C.; Mulia, A. J.; O'Halloran, B.; Olsen, K.; Paladini, R.; Paradis, D.; Reach, W. T.; Rubin, D.; Sandstrom, K.; Soszynski, I.; Speck, A. K.; Srinivasan, S.; Tielens, A. G. G. M.; van Aarle, E.; van Dyk, S. D.; van Winckel, H.; Vijh, U. P.; Whitney, B.; Wilkins, A. N.

    2011-09-01

    We present the classification of 197 point sources observed with the Infrared Spectrograph in the SAGE-Spec Legacy programme on the Spitzer Space Telescope. We introduce a decision-tree method of object classification based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information, which is used to classify the SAGE-Spec sample of point sources. The decision tree has a broad application to mid-infrared spectroscopic surveys, where supporting photometry and variability information are available. We use these classifications to make deductions about the stellar populations of the Large Magellanic Cloud and the success of photometric classification methods. We find 90 asymptotic giant branch (AGB) stars, 29 young stellar objects, 23 post-AGB objects, 19 red supergiants, eight stellar photospheres, seven background galaxies, seven planetary nebulae, two HII regions and 12 other objects, seven of which remain unclassified. (1 data file).

  16. Point Source Scatter Contributions From Finite Size Objects In Radioisotope Imaging

    Bieszk, J. A.; Lim, C. B.

    1982-11-01

    A Monte Carlo simulation was developed to study scatter contributions from a 140 keV point source at various depths and for different energy windows in finite water phantoms. Photoelectric and Compton interactions were considered. Scatter fractions, energy spectra, and radial spread functions of three approximately patientsized phantoms (rectangular prism, elliptical cylinder, and a sphere) were examined as a function of point-source depth and detector energy-window width. For a 100% energy window, energy spectra are characterized by a high energy region, a backscatter peak region, and a low energy, multi-scatter region. Depth dependent spatial limitations to the radial spread functions occur with decreasing window width. Scatter fractions for the sphere are much smaller than those of the other two phantoms, but approach their values as the size of the energy window decreases.

  17. Optimization of point sources on thin films using a statistical design approach. Application to 60Co sources

    Radioactive point sources prepared by depositing weighed drops on thin membranes are commonly used in ionizing radiation metrology for 47πβ-γ coincidence counting or for low energy electrons spectrometry. The present study deals with the preparation of good quality sources having high detection yields. Some influential parameters on the source quality are studied using 60Co as radioactive tracer. An approach based on experimental statistical designs has been chosen. This approach allows us to obtain reliable results with a number of experiences lower than in the case of a systematic approach. Homogeneous 60Co sources with high metrological qualifies (Rβ> 96 %) can be prepared using a direct deposit of ∼ 5 mg drops of 60Co solution ([Co] = 12 μg/g), [HCl] = 0,5 mol/I) and dried at 60 deg C. The support of the radioactive spot is constituted with a gold coated (130 μg/cm2 of Au) Vyns films (thickness 45 μg/cm2) on which a pad (diameter = 7 - 8 mm) of polystyrene microspheres (Estapor K-007) is prepared by an electro-spraying technique under 7,5 kV during 10 minutes. The alcoholic solution used for the electro-spraying step has the following chemical composition [Estapor K-007] 2.5 10-2 wt % and [Tween 20] = 2.7 10-2 wt %. (authors)

  18. Simulations of HXR Foot-point Source Sizes for Modified Thick-target Models

    Moravec, Z.; Varady, Michal; Karlický, Marian; Kašparová, Jana

    2013-01-01

    Roč. 37, č. 2 (2013), s. 535-540. ISSN 1845-8319. [Hvar Astrophysical Colloquium /12./. Hvar, 03.09.2012-07.09.2012] R&D Projects: GA ČR GAP209/10/1680; GA ČR GAP209/12/0103 Institutional support: RVO:67985815 Keywords : solar flares * hard X-rays * foot -point sources Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  19. Using sorbent waste materials to enhance treatment of micro-point source effluents by constructed wetlands

    Green, Verity; Surridge, Ben; Quinton, John; Matthews, Mike

    2014-01-01

    Sorbent materials are widely used in environmental settings as a means of = enhancing pollution remediation. A key area of environmental concern is that of water pollution, including the need to treat micro-point sources of wastewater pollution, such as from caravan sites or visitor centres. Constructed wetlands (CWs) represent one means for effective treatment of wastewater from small wastewater producers, in part because they are believed to be economically viable and environmentally sustai...

  20. Gamma Rays from the Inner Milky Way: Dark Matter or Point Sources?

    CERN. Geneva

    2015-01-01

    Studies of data from the Fermi Gamma-Ray Space Telescope have revealed bright gamma-ray emission from the central regions of our galaxy, with a spatial and spectral profile consistent with annihilating dark matter. I will present a new model-independent analysis that suggests that rather than originating from dark matter, the GeV excess may arise from a surprising new population of as-yet-unresolved gamma-ray point sources in the heart of the Milky Way.

  1. Decomposition Of Continuum GAMMA Ray Spectra For Point Sources By Using Gold Algorithm

    In this work, we try for decomposition of continuum gamma ray spectra using Gold algorithm. The problem is applied for the gamma spectra of Co-60, Cs-137 and Eu-152 point source for HPGe GC2018 gamma spectroscopy. The results show that the convergence speed is faster than results for using MLEM algorithm and the largest difference of the peak area ratios before and after unfolding from P/T values decreases 15%. (author)

  2. Discriminating between unresolved point sources and "negative" SZ clusters in CMB maps

    Rubino-Martin, J. A.; Sunyaev, R. A.

    2002-01-01

    Clusters of galaxies produce negative features at wavelengths $\\lambda > 1.25$ mm in CMB maps, by means of the thermal SZ effect, while point radio sources produce positive peaks. This fact implies that a distribution of unresolved SZ clusters could be detected using the negative asymmetry introduced in the odd-moments of the brightness map (skewness and higher), or in the probability distribution function (PDF) for the fluctuations, once the map has been filtered in order to remove the contr...

  3. Monitoring of Non-Point Source Pollutions from an Agriculture Watershed in South China

    Haiying Hu; Guoru Huang

    2014-01-01

    Understanding the characteristics of non-point sources (NPS) pollutions can provide theoretical support for improving water quality. Siheshui watershed located in south China was selected to explore the characteristics of NPS pollutions in rainfall-runoff process. In this small agricultural watershed, five flood events and one non-flood event were monitored, and the water quantity and quality constituents were measured. The event mean concentrations (EMCs) of pollutant constituents in runoff ...

  4. A Laboratory Study of Auctions for Reducing Non-Point Source Pollution

    Cason, Timothy N.; Gangadharan, Lata; Duke, Charlotte

    2002-01-01

    Non-point source pollution, such as nutrient runoff to waterways from agricultural production, is an environmental problem that typically involves asymmetric information. Land use changes to reduce pollution incur opportunity costs that are privately known to landholders, but these changes provide environmental benefits that may be more accurately estimated by regulators. This paper reports a testbed laboratory experiment in which landholder/sellers in multi-round, sealed-offer auctions compe...

  5. Agricultural Non-Point Source Pollution in China: Causes and Mitigation Measures

    Sun, Bo; Zhang, Linxiu; Yang, Linzhang; Zhang, Fusuo; Norse, David; ZHU Zhaoliang

    2012-01-01

    Non-point source (NPS) pollution has been increasingly serious in China since the 1990s. The increases of agricultural NPS pollution in China is evaluated for the period 2000−2008 by surveying the literature on water and soil pollution from fertilizers and pesticides, and assessing the surplus nitrogen balance within provinces. The main causes for NPS pollution were excessive inputs of nitrogen fertilizer and pesticides, which were partly the result of the inadequate agricultural extension se...

  6. Quantifying the Potential for Non-Point Source Pollution in Model Urban Landscapes

    Wolyniak, Brian John

    2005-01-01

    The contribution of non-point source pollution to degrading surface water quality is considerable throughout Virginia and beyond. While research on agricultural best management practices in nutrient management and nutrient and soil stabilization has made progress in reducing agricultural contributions to nutrient and sediment loading of watersheds, little is known about how land covers of different vegetation representative of urban areas (e.g., bare soil versus turfgrass lawns versus urban ...

  7. THE METHOD OF CAR HEADLIGHTS LUMINOUS INTENSITY MEASURING FOR NON-POINT SOURCES OF LIGHT

    A. Kupko

    2015-12-01

    Full Text Available It is shown that the measurements of luminous intensity of car headlights luminous intensity for non-point sources have pecularities. A simplified method for correction the luminous intensity at various distances is developed. The applicability of the given method with possible measurement errors is studied. The results were obtained, using a stand of the National Scientific Center “Institute of Metroligy”.

  8. CO2 point sources and subsurface storage capacities for CO2 in aquifers in Norway

    The GESTCO project comprises a study of the distribution and coincidence of thermal CO2 emission sources and location/quality of geological storage capacity in Europe. Four of the most promising types of geological storage are being studied. 1. Onshore/offshore saline aquifers with or without lateral seal. 2. Low entalpy geothermal reservoirs. 3. Deep methane-bearing coal beds and abandoned coal and salt mines. 4. Exhausted or near exhausted hydrocarbon structures. In this report we present an inventory of CO2 point sources in Norway (1999) and the results of the work within Study Area C: Deep saline aquifers offshore/near shore Northern and Central Norway. Also offshore/near shore Southern Norway has been included while the Barents Sea is not described in any detail. The most detailed studies are on the Tilje and Aare Formations on the Troendelag Platform off Mid-Norway and on the Sognefjord, Fensfjord and Krossfjord Formations, southeast of the Troll Field off Western Norway. The Tilje Formation has been chosen as one of the cases to be studied in greater detail (numerical modelling) in the project. This report shows that offshore Norway, there are concentrations of large CO2 point sources in the Haltenbanken, the Viking Graben/Tampen Spur area, the Southern Viking Graben and the central Trough, while onshore Norway there are concentrations of point sources in the Oslofjord/Porsgrund area, along the coast of western Norway and in the Troendelag. A number of aquifers with large theoretical CO2 storage potential are pointed out in the North Sea, the Norwegian Sea and in the Southern Barents Sea. The storage capacity in the depth interval 0.8 - 4 km below sea level is estimated to be ca. 13 Gt (13000000000 tonnes) CO2 in geological traps (outside hydrocarbon fields), while the storage capacity in aquifers not confined to traps is estimated to be at least 280 Gt CO2. (Author)

  9. The 21-cm emission from the reionization epoch: extended and point source foregrounds

    Di Matteo, Tiziana; Ciardi, Benedetta; Miniati, Francesco

    2004-12-01

    Fluctuations in the redshifted 21-cm emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources (both extended and point-like). We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio haloes and relics and free-free emission from the interstellar and intergalactic medium at the frequencies and angular scales relevant for the proposed 21-cm tomography. In accord with previous findings, the brightness temperature fluctuations due to foreground sources are much larger than those from the primary 21-cm signal at all scales. In particular, diffuse cluster radio emission, which has been previously neglected, provides the most significant foreground contamination. However, we show that the contribution to the angular fluctuations at scales θ>~ 1 arcmin is dominated by the spatial clustering of bright foreground sources. This excess can be removed if sources above flux levels S>~ 0.1 mJy (out to redshifts of z~ 1 and z~ 2 for diffuse and point sources, respectively) are detected and removed. Hence, efficient source removal may be sufficient to allow the detection of angular fluctuations in the 21-cm emission free of extragalactic foregrounds at θ>~ 1 arcmin. In addition, the removal of sources above S= 0.1 mJy also reduces the foreground fluctuations to roughly the same level as the 21-cm signal at scales θ<~ 1 arcmin. This should allow the substraction of the foreground components in frequency space, making it possible to observe in detail the topology and history of reionization.

  10. Normalized Point Source Sensitivity for Off-Axis Optical Performance Evaluation of the Thirty Meter Telescope

    Seo, Byoung-Joon; Nissly, Carl; Troy, Mitchell; Angeli, George

    2010-01-01

    The Normalized Point Source Sensitivity (PSSN) has previously been defined and analyzed as an On-Axis seeing-limited telescope performance metric. In this paper, we expand the scope of the PSSN definition to include Off-Axis field of view (FoV) points and apply this generalized metric for performance evaluation of the Thirty Meter Telescope (TMT). We first propose various possible choices for the PSSN definition and select one as our baseline. We show that our baseline metric has useful properties including the multiplicative feature even when considering Off-Axis FoV points, which has proven to be useful for optimizing the telescope error budget. Various TMT optical errors are considered for the performance evaluation including segment alignment and phasing, segment surface figures, temperature, and gravity, whose On-Axis PSSN values have previously been published by our group.

  11. FIRST NEUTRINO POINT-SOURCE RESULTS FROM THE 22-STRING ICECUBE DETECTOR

    IceCube Collaboration; Klein, Spencer

    2009-05-14

    We present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-08 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of livetime. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2 {sigma} after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E{sup -2} spectrum is E{sup 2} {Phi}{sub {nu}{sub {mu}}} < 1.4 x 10{sup -1} TeV cm{sup -2}s{sup -1}, in the energy range from 3 TeV to 3 PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of two.

  12. Back-projection source reconstruction in the presence of point scatterers

    Solimene, Raffaele; Cuccaro, Antonio; Pierri, Rocco

    2016-06-01

    Inverse source and inverse scattering problems can benefit from multipath due to a scattering environment. At the same time, multipath can be source of artefacts in the reconstructions. In this paper the aim is to understand when and how multipath manifests its positive or negative effects. To this end, a simple scenario is considered. First of all, the problem is cast within a 2D scalar setting where multipath is assumed due to known ‘extra’ point-like scatterers. In order to make the study easier, the inverse source problem is dealt with. This allows us to handle a modelling operator with fewer terms than inverse scattering and hence it makes the study less tedious. A back-projection inversion method based on the adjoint of the radiation operator is exploited. This allows us to easily compute the model resolution kernels, i.e. the point spread function, whose dominant contributions are determined by phase stationary arguments. The role played by the point scatterers and how they contribute to an improvement of the achievable resolution is highlighted.

  13. [Transformation of Non-point Source Soluble Nitrogen in Simulated Drainage Ditch].

    Li, Qiang-kun; Song, Chang-ji; Hu, Ya-wei; Peng, Cong; Ma, Qiang; Jiang, Zheng-xi; Ju, Yi-rheng

    2016-02-15

    The drainage ditch has a compound ecosystem structure consisting of water, sediment and plants. Migration and transformation of the non-point source solute is important to study interception, control and management of agricultural non-point source pollution in the drainage ditch. Based on the experiment on static simulation of drainage ditches, the article used typical non-point source soluble nitrogen as an example to analyze the changing process of nitrogen content in water, sediment and reeds, and to study the effects of the sediment adsorption and desorption, reeds growth and death in different periods on nitrogen concentration in water. The article discussed nitrogen migration in water-sediment-reeds compound ecosystem and its influence on nitrogen concentration in water. The results showed that both adsorption and desorption in sediment and absorption and assimilation of reeds growth had effect on nitrogen concentration in water. The effect before October was reducing the nitrogen concentration in water, which was the process of nitrogen purification in water. After October, the nitrogen concentration in water increased and made it easy to form secondary nitrogen pollution. Meanwhile, the migration in the water-sediment-seeds ecosystem in simulated drainage ditch had close ties, any migration and transformation of nitrogen in a single medium or between different mediums would cause adjustment of nitrogen concentration in water. PMID:27363139

  14. A scanning point source for quality control of FOV uniformity in GC-PET imaging

    Aim: PET imaging with coincidence cameras (GC-PET) requires additional quality control procedures to check the function of coincidence circuitry and detector zoning. In particular, the uniformity response over the field of view needs special attention since it is known that coincidence counting mode may suffer from non-uniformity effects not present in single photon mode. Materials and methods: An inexpensive linear scanner with a stepper motor and a digital interface to a PC with software allowing versatile scanning modes was developed. The scanner is used with a source holder containing a Sodium-22 point source. While moving the source along the axis of rotation of the GC-PET system, a tomographic acquisition takes place. The scan covers the full axial field of view of the 2-D or 3-D scatter frame. Depending on the acquisition software, point source scanning takes place continuously while only one projection is acquired or is done in step-and-shoot mode with the number of positions equal to the number of gantry steps. Special software was developed to analyse the resulting list mode acquisition files and to produce an image of the recorded coincidence events of each head. Results: Uniformity images of coincidence events were obtained after further correction for systematic sensitivity variations caused by acquisition geometry. The resulting images are analysed visually and by calculating NEMA uniformity indices as for a planar flood field. The method has been applied successfully to two different brands of GC-PET capable gamma cameras. Conclusion: Uniformity of GC-PET can be tested quickly and accurately with a routine QC procedure, using a Sodium-22 scanning point source and an inexpensive mechanical scanning device. The method can be used for both 2-D and 3-D acquisition modes and fills an important gap in the quality control system for GC-PET

  15. Temporal-spatial distribution of non-point source pollution in a drinking water source reservoir watershed based on SWAT

    Wang, M.; Cheng, W.; Yu, B.-S.; Fang, Y.

    2015-05-01

    The conservation of drinking water source reservoirs has a close relationship between regional economic development and people's livelihood. Research on the non-point pollution characteristics in its watershed is crucial for reservoir security. Tang Pu Reservoir watershed was selected as the study area. The non-point pollution model of Tang Pu Reservoir was established based on the SWAT (Soil and Water Assessment Tool) model. The model was adjusted to analyse the temporal-spatial distribution patterns of total nitrogen (TN) and total phosphorus (TP). The results showed that the loss of TN and TP in the reservoir watershed were related to precipitation in flood season. And the annual changes showed an "M" shape. It was found that the contribution of loss of TN and TP accounted for 84.5% and 85.3% in high flow years, and for 70.3% and 69.7% in low flow years, respectively. The contributions in normal flow years were 62.9% and 63.3%, respectively. The TN and TP mainly arise from Wangtan town, Gulai town, and Wangyuan town, etc. In addition, it was found that the source of TN and TP showed consistency in space.

  16. Analytical calculation of the solid angle defined by a cylindrical detector and a point cosine source with orthogonal axes

    We derive analytical expressions for the solid angle subtended by a right circular cylinder at a point source with cosine angular distribution in the case where the source and the cylinder axes are mutually orthogonal

  17. ASTRO-F\\/FIS Observing Simulation I. Detection Limits for Point Sources

    Jeong, W S; Lee, H M; Nakagawa, T; Sohn, J; Ahn, I; Yamamura, I; Watanabe, M; Kawada, M K; Shibai, H; Jeong, Woong-Seob; Pak, Soojong; Lee, Hyung Mok; Nakagawa, Takao; Sohn, Jungjoo; Ahn, Insun; Yamamura, Issei; Watanabe, Masaru; Kawada, Mitsunobu; Shibai, Hiroshi

    2002-01-01

    We describe the observing simulation software FISVI (FIS Virtual Instrument), which was developed for the Far-Infrared Surveyor (FIS) that will be on the Japanese infrared astronomy mission ASTRO-F. The FISVI has two purposes: one is to check the specifications and performances of the ASTRO-F/FIS as a whole, and the other is to prepare input data sets for the data analysis softwares prior to launch. In the FISVI, a special care was taken by introducing the `Compiled PSF (Point Spread Function)' to optimise inevitable but time-consuming convolution processes. With the Compiled PSF, we reduce the computation time by an order of magnitude. The photon and readout noises are included in the simulations. We estimate the detection limits for point sources from the simulation of virtual patches of the sky mostly consisting of distant galaxies. We studied the importance of the source confusion for simple power-law models for N(>S), the number of sources brighter than S. We found that source confusion plays a dominant ...

  18. Extended-Source Effect and Chromaticity in Two-Point-Mass Microlensing

    Pejcha, Ondrej

    2007-01-01

    We explore the sensitivity of two-point-mass gravitational microlensing to the extended nature of the source star and the related sensitivity to its limb darkening. We demonstrate that the sensitive region, usually considered to be limited to a source-diameter-wide band along the caustic, is strongly expanded near cusps, most prominently along their outer axis. In the case of multi-component caustics, facing cusps may form a region with a non-negligible extended-source effect spanning the gap between them. We demonstrate that for smaller sources the size of the sensitive region extending from a cusp measured in units of source radii increases, scaling as the inverse cube root of the radius. Taking into account the extent of different sensitivity contours, we show that for a Galactic Bulge giant and a lens with a multi-component caustic the probability of encountering at least a 1% extended-source effect may be more than two times higher than the probability of caustic crossing. We derive analytical expression...

  19. IceCube point source searches using through-going muon tracks

    The IceCube neutrino observatory located at the South Pole is the current largest neutrino telescope. Using through-going muon tracks, IceCube records approximately 130,000 events per year with reconstruction accuracy as low as 0.7 deg for energies of 10 TeV. Having analysed an integrated time-scale of 4 years, no sources of neutrinos have yet been observed. This talk deals with the current progress in point-source searches, adding another two years of data recorded in the years 2012 and 2013. In a combined search with starting events, sources of hard and soft spectra with- and with-out cut-offs are characterised.

  20. Weighted average source points and distances for consumption origin-tools for environmental impact analysis?

    This paper presents two methods to quickly assess how local people's consumption is dependant on sources other than local or domestic. Weighted average source points (WASPs) or weighted average source distances (WASDs) for consumption origin are calculated and used to illustrate the extent to which the goods consumed come from places other than where the consumer lives. Two case-studies show the practicability of the methods. The first is a comparison between the consumption origins of tomatoes and carrots and the second a comparison between grape consumption origins in 1965 and 1992. Both the WASP and the WASD methods are easy to use and the results can be communicated in illustrative ways. These methods, however, give only an estimate of possible environmental impacts

  1. Evaluation of single frequency GPS precise point positioning assisted with external ionosphere sources

    Ghoddousi-Fard, Reza; Lahaye, François

    2016-05-01

    Single frequency code and single frequency code and phase GPS precise point positioning scenarios using various ionospheric sources are evaluated by assessing their performances with respect to dual frequency solutions. These include Canadian regional and global vertical total electron content (VTEC) maps produced by Natural Resources Canada and different International GNSS Service (IGS) coordination or analysis centres. Furthermore, two of the most commonly used single layer ionospheric mapping functions applied for conversion of VTEC to slant TEC are evaluated with each and every one of the ionospheric VTEC sources. Results show that the quality of code only solutions depends on ionospheric activity level, and the TEC map and mapping function selected. Code and phase single frequency solutions are also improved when assisted with an external ionosphere source.

  2. Lessons Learned from OMI Observations of Point Source SO2 Pollution

    Krotkov, N.; Fioletov, V.; McLinden, Chris

    2011-01-01

    The Ozone Monitoring Instrument (OMI) on NASA Aura satellite makes global daily measurements of the total column of sulfur dioxide (SO2), a short-lived trace gas produced by fossil fuel combustion, smelting, and volcanoes. Although anthropogenic SO2 signals may not be detectable in a single OMI pixel, it is possible to see the source and determine its exact location by averaging a large number of individual measurements. We describe new techniques for spatial and temporal averaging that have been applied to the OMI SO2 data to determine the spatial distributions or "fingerprints" of SO2 burdens from top 100 pollution sources in North America. The technique requires averaging of several years of OMI daily measurements to observe SO2 pollution from typical anthropogenic sources. We found that the largest point sources of SO2 in the U.S. produce elevated SO2 values over a relatively small area - within 20-30 km radius. Therefore, one needs higher than OMI spatial resolution to monitor typical SO2 sources. TROPOMI instrument on the ESA Sentinel 5 precursor mission will have improved ground resolution (approximately 7 km at nadir), but is limited to once a day measurement. A pointable geostationary UVB spectrometer with variable spatial resolution and flexible sampling frequency could potentially achieve the goal of daily monitoring of SO2 point sources and resolve downwind plumes. This concept of taking the measurements at high frequency to enhance weak signals needs to be demonstrated with a GEOCAPE precursor mission before 2020, which will help formulating GEOCAPE measurement requirements.

  3. Identification and Quantification of Non-Point Sources of pollution to Sabarmati River, Ahmedabad

    Monika H. Panchani, Prof. M. J. Pandya

    2013-04-01

    Full Text Available “Whatever can be measure, can be control”.Non-point pollution sources(NPS account for more than 50% of the total water quality problem, and they are being recognized and investigated nationally and internationally. In many areas, non-point pollution, such as runoff from crop land, urban storm water, strip mining and runoff from construction sites are becoming major water quality problems.To identify and quantify Non-point sources of pollution the selected study area is the stretch of the Sabarmati river from gandhinagar to Ahmedabad city. The selected study area is divided into two parts. 1. The upstream of Ahmedabad city. 2. Ahmedabad city. Identification of NPS is done by literature survey and field visit of study area. Quantification can be done by using different runoff calculation methods. Because of limitations of all method, the appropriate one has been chosen for analysis. By quantifying it is observed that the NPS contribute the large amounts of pollution load which can not be underestimated

  4. On the linear filters for point source extraction of the Planck mission

    Chiang, L Y; Chiang, Lung-Yih; Naselsky, Pavel

    2003-01-01

    The manifestation of point sources in the upcoming PLANCK maps is a direct reflection of the properties of the pixelized antenna beam shape for each frequency, which is related to the scan strategy, pointing accuracy, noise properties and map-making algorithm. In this paper we firstly compare analytically the three filters for the PLANCK point source extraction, namely, the adaptive top-hat filter (ATHF), the theoretically-optimal filter (TOF), and the so-called pseudo-filter based on wavelet technique. Our analyses are based on the premise that the experiment parameters the TOF and the pseudo-filter assume and require are already known: the CMB and noise power spectrum and a circular Gaussian beam shape and size, whereas the ATHF does not need any a priori knowledge. The analyses show that the TOF is optimal of them all in terms of the gain after the parameter inputs. On the other hand, the wavelet technique is only asymptotic to the TOF. We simulate the PLANCK HFI 100 GHz channel with elliptical beam in rot...

  5. Gordian adjacency for torus knots

    Feller, Peter

    2013-01-01

    A knot K is called Gordian adjacent to a knot L if there exists an unknotting sequence for L containing K. We provide a sufficient condition for Gordian adjacency of torus knots via the study of knots in the thickened torus. We also completely describe Gordian adjacency for torus knots of index 2 and 3 using Levine-Tristram signatures as obstructions to Gordian adjacency. Finally, Gordian adjacency for torus knots is compared to the notion of adjacency for plane curve singularities.

  6. OBJECT X: THE BRIGHTEST MID-INFRARED POINT SOURCE IN M33

    We discuss the nature of the brightest mid-IR point source (which we dub Object X) in the nearby galaxy M33. Although multi-wavelength data on this object have existed in the literature for some time, it had not previously been recognized as the most luminous mid-IR object in M33 because it is entirely unremarkable in both optical and near-IR light. In the Local Group Galaxies Survey, Object X is a faint red source visible in VRI and Hα but not U or B. It was easily seen at JHKs in the Two Micron All Sky Survey. It is the brightest point source in all four Spitzer IRAC bands and is also visible in the MIPS 24 μm band. Its bolometric luminosity is ∼5 x 105 Lsun. The source is optically variable on short timescales (tens of days) and is also slightly variable in the mid-IR, indicating that it is a star. Archival photographic plates (from 1949 and 1991) show no optical source, so the star has been obscured for at least half a century. Its properties are similar to those of the Galactic OH/IR star IRC+10420, which has a complex dusty circumstellar structure resulting from episodic low-velocity mass ejections. We propose that Object X is an M ∼> 30 Msun evolved star obscured in its own dust ejected during episodic mass-loss events over at least ∼half a century. It may emerge from its current ultra-short evolutionary phase as a hotter post-red-supergiant star analogous to M33 Var A. The existence and rarity of such objects can be an important probe of a very brief yet eventful stellar evolutionary phase.

  7. Point source pollution and variability of nitrate concentrations in water from shallow aquifers

    Nemčić-Jurec, Jasna; Jazbec, Anamarija

    2016-01-01

    Agriculture is one of the several major sources of nitrate pollution, and therefore the EU Nitrate Directive, designed to decrease pollution, has been implemented. Point sources like septic systems and broken sewage systems also contribute to water pollution. Pollution of groundwater by nitrate from 19 shallow wells was studied in a typical agricultural region, middle Podravina, in northwest Croatia. The concentration of nitrate ranged from R6, there was no statistically significant difference in nitrate concentrations (F = 1.98; p = 0.15) during the years 2002-2007. Average concentrations of nitrate in all 19 wells for all the analyzed years were between recommended limit value of 25 mg/l (RLV) and MAV except in 2002 (concentration was under RLV). The results of the repeated measures ANOVA showed statistically significant differences between the wells at the point source distance (proximity) of 20 m (F = 10.6; p < 0.001). Average annual concentrations of nitrate during the years studied are not statistically different, but interaction between proximity and years is statistically significant (F = 2.07; p = 0.04). Results of k-means clustering confirmed division into four clusters according to the pollution. Principal component analysis showed that there is only one significant factor, proximity, which explains 91.6 % of the total variability of nitrate. Differences in water quality were found as a result of different environmental factors. These results will contribute to the implementation of the Nitrate Directive in Croatia and the EU.

  8. The seven year Swift-XRT point source catalog (1SWXRT)

    D'Elia, V; Puccetti, S; Capalbi, M; Giommi, P; Burrows, D N; Campana, S; Tagliaferri, G; Cusumano, G; Evans, P; Gehrels, N; Kennea, J; Moretti, A; Nousek, J A; Osborne, J P; Romano, P; Stratta, G

    2013-01-01

    Swift is a multi-wavelength observatory specifically designed for gamma-ray burst (GRB) astronomy that is operational since 2004. Swift is also a very flexible multi-purpose facility that supports a wide range of scientific fields such as active galactic nuclei, supernovae, cataclysmic variables, Galactic transients, active stars and comets. The Swift X-ray Telescope (XRT) has collected more than 150 Ms of observations in its first seven years of operations. We present the list of all the X-ray point sources detected in XRT imaging data taken in photon counting mode during the first seven years of Swift operations. All these point-like sources, excluding the Gamma-Ray Bursts (GRB), will be stored in a catalog publicly available (1SWXRT). We consider all XRT observations with exposure time > 500 s taken in the period 2005-2011. Data were reduced and analyzed with standard techniques and a list of detected sources for each observation was produced. A careful visual inspection was performed to remove extended, s...

  9. Characteristics of Non-Point Source Pollution in the Watershed of Miyun Reservoir, Beijing, China

    王晓燕; 王一峋; 李庭芳; 贺伟; 胡秋菊; 张弘芬

    2002-01-01

    Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir, a very important drinking water source of Beijing, China, and they are mainly from non-point sources. The watershed in Miyun County was selected as the study region with a total area of 1400 km2. Four typical monitoring catchments and two experimental units were used to monitor the precipitation, runoff, sediment yield and pollutant loading related to various land uses in the meantime. The results show that the total nutrient loss amounts of TN and TP are 898.07 t/a, and 40.70 t/a, respectively, in which nutrients N and P carried by runoff are 91.3 % and 77.3 %, respectively. There is relatively heavier soil erosion in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir. Different land uses would influence the loss amounts of non-point source pollutants. The amount of nutrient loss from the agricultural land per unit is highest, that from forestry comes next and that from grassland is lowest. However, due to the variability of land use areas, agricultural land contributes a lot to TP and forestry lands to TN.

  10. Characteristics of Non—Point Source Pollution in the Watershed of Miyun Reservoir,Beijing,China

    王晓燕; 贺伟; 等

    2002-01-01

    Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN.

  11. Mercury exposure in terrestrial birds far downstream of an historical point source

    Jackson, Allyson K., E-mail: allyson.jackson@briloon.org [Biodiversity Research Institute, 19 Flaggy Meadow Road, Gorham, ME 04038 (United States); Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, VA 23187 (United States); Evers, David C.; Folsom, Sarah B. [Biodiversity Research Institute, 19 Flaggy Meadow Road, Gorham, ME 04038 (United States); Condon, Anne M. [U.S. Fish and Wildlife Service, 6669 Short Lane, Gloucester, VA 23061 (United States); Diener, John; Goodrick, Lizzie F. [Biodiversity Research Institute, 19 Flaggy Meadow Road, Gorham, ME 04038 (United States); McGann, Andrew J. [Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, VA 23187 (United States); Schmerfeld, John [U.S. Fish and Wildlife Service, 6669 Short Lane, Gloucester, VA 23061 (United States); Cristol, Daniel A. [Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, VA 23187 (United States)

    2011-12-15

    Mercury (Hg) is a persistent environmental contaminant found in many freshwater and marine ecosystems. Historical Hg contamination in rivers can impact the surrounding terrestrial ecosystem, but there is little known about how far downstream this contamination persists. In 2009, we sampled terrestrial forest songbirds at five floodplain sites up to 137 km downstream of an historical source of Hg along the South and South Fork Shenandoah Rivers (Virginia, USA). We found that blood total Hg concentrations remained elevated over the entire sampling area and there was little evidence of decline with distance. While it is well known that Hg is a pervasive and long-lasting aquatic contaminant, it has only been recently recognized that it also biomagnifies effectively in floodplain forest food webs. This study extends the area of concern for terrestrial habitats near contaminated rivers for more than 100 km downstream from a waterborne Hg point source. - Highlights: > We report blood mercury levels for terrestrial songbirds downstream of contamination. > Blood mercury levels remain elevated above reference for at least 137 km downstream. > Trends vary based on foraging guild and migration strategy. > Mercury affects terrestrial biota farther downstream than previously documented. - Blood mercury levels of forest songbirds remain elevated above reference levels for at least 137 km downstream of historical point source.

  12. The XXL Survey: VI. The 1000 brightest X-ray point sources

    Fotopoulou, S; Paltani, S; Ranalli, P; Ramos-Ceja, M E; Faccioli, L; Plionis, M; Adami, C; Bongiorno, A; Brusa, M; Chiappetti, L; Desai, S; Elyiv, A; Lidman, C; Melnyk, O; Pierre, M; Piconcelli, E; Vignali, C; Alis, S; Ardila, F; Arnouts, S; Baldry, I; Bremer, M; Eckert, D; Guennou, L; Horellou, C; Iovino, A; Koulouridis, E; Liske, J; Maurogordato, S; Menanteau, F; Mohr, J J; Owers, M; Poggianti, B; Pompei, E; Sadibekova, T; Stanford, A; Tuffs, R; Willis, J

    2016-01-01

    X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). The XXL Survey spans two fields of a combined 50 $deg^2$ observed for more than 6Ms with XMM-Newton, occupying the parameter space between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. This paper marks the first release of the XXL point source catalogue selected in the 2-10 keV energy band with limiting flux $F_{2-10keV}=4.8\\cdot10^{-14}\\rm{erg\\,s^{-1}\\,cm^{-2}}$. We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources and improved upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift model library. We also assign a probability to each source to be a star or an outlier. We model with Bayesian analysis the X-ray spectra assuming a power-law model with the presence of an...

  13. Natural Wetlands Mediate Non-point Source Water Pollution From Irrigated Pastures

    Knox, K.; Dahlgren, R. A.; Tate, K. W.

    2005-12-01

    Non-point source discharge from grazed pastures may be high in nutrients, sediment, and pathogens, three major contributors to water quality impairment in California. Intercepting pollution at its source and managing water quality within the landscape are essential to maintaining healthy downstream waters. We investigated the efficacy of flow-through wetlands interspersed throughout the agricultural landscape to reduce non-point source pollution of tailwater from cattle-grazed, irrigated pastures in the Sierra Nevada Foothills of California. Wetlands are known to positively impact water quality through ecological processes such as filtration, sedimentation, microbial transformations and plant uptake of nutrients. Influent and effluent water of small (0.25 ha), natural wetlands located downstream from flood irrigated pastures was analyzed for Escherichia coli, NO3-N, total N, total suspended solids (TSS), total P, and dissolved organic carbon (DOC) throughout two summer irrigation seasons (June to October). We compared reductions of sediment, nutrients and E. coli provided by a healthy, non-degraded wetland with reductions from flow through a channelized, degraded wetland. Large reductions in E. coli (>75%) and TSS (>50%) were observed in water exiting the healthy wetland while nutrient and DOC (~ 20%) concentrations were less affected by flow through the wetland. The channelized wetland provided smaller reductions in all constituents than did the non-degraded wetland. Results from this study demonstrate that small flow-through wetlands can improve water quality through the attenuation of E. coli and suspended sediments, and to a lesser degree DOC and nutrients.

  14. Localising the H.E.S.S. Galactic Centre point source

    Van Eldik, C; Braun, I; Hermann, G; Hinton, J; Hofmann, W

    2007-01-01

    Observations by the H.E.S.S. system of imaging atmospheric Cherenkov telescopes provide the most sensitive measurements of the Galactic Centre region in the energy range 150 GeV - 30 TeV. The vicinity of the kinetic centre of our galaxy harbours numerous objects which could potentially accelerate particles to very high energies (VHE, > 100 GeV) and thus produce the Gamma-ray flux observed. Within statistical and systematic errors, the centroid of the point-like emission measured by H.E.S.S. was found to be in good agreement with the position of the supermassive black hole Sgr A* and the recently discovered PWN candidate G359.95-0.04. Given a systematic pointing error of about 30'', a possible association with the SNR Sgr A East could not be ruled out with the 2004 H.E.S.S. data. In this contribution an update is given on the position of the H.E.S.S. Galactic Centre source using 2005/2006 data. The systematic pointing error is reduced to 6'' per axis using guiding telescopes for pointing corrections, making it...

  15. A systematic analysis of the Braitenberg vehicle 2b for point-like stimulus sources

    Braitenberg vehicles have been used experimentally for decades in robotics with limited empirical understanding. This paper presents the first mathematical model of the vehicle 2b, displaying so-called aggression behaviour, and analyses the possible trajectories for point-like smooth stimulus sources. This sensory-motor steering control mechanism is used to implement biologically grounded target approach, target-seeking or obstacle-avoidance behaviour. However, the analysis of the resulting model reveals that complex and unexpected trajectories can result even for point-like stimuli. We also prove how the implementation of the controller and the vehicle morphology interact to affect the behaviour of the vehicle. This work provides a better understanding of Braitenberg vehicle 2b, explains experimental results and paves the way for a formally grounded application on robotics as well as for a new way of understanding target seeking in biology. (paper)

  16. Potential of KM3NeT to observe galactic neutrino point-like sources

    Trovato, Agata

    2016-07-01

    KM3NeT (http://www.km3net.org">http://www.km3net.org) will be the next-generation cubic-kilometre-scale neutrino telescope to be installed in the depths of the Mediterranean Sea. This location will allow for surveying the Galactic Centre, most of the Galactic Plane as well as a large part of the sky. We report KM3NeT discovery potential for the SNR RXJ1713.7-3946 and the PWN Vela X and its sensitivity to point-like sources with an E-2 spectrum.

  17. Photon Conserving Radiative Transfer around Point Sources in multi-dimensional Numerical Cosmology

    Abel, T; Madau, P; Abel, Tom; Norman, Michael L.; Madau, Piero

    1998-01-01

    Many questions in physical cosmology regarding the thermal and ionization history of the intergalactic medium are now successfully studied with the help of cosmological hydrodynamical simulations. Here we present a numerical method that solves the radiative transfer around point sources within a three dimensional cartesian grid. The method is energy conserving independently of resolution: this ensures the correct propagation speeds of ionization fronts. We describe the details of the algorithm, and compute as first numerical application the ionized region surrounding a mini-quasar in a cosmological density field at z=7.

  18. Analytical Dispersion Formula for a Point Source by Using Spherical Coordinate on Gaussian Plume Model

    The objective of this work is provide analytical formula of the dispersion parameters to describe the polluted point source in space release to the atmosphere. The Gaussian Plume Model (GPM) choice as appropriates framework to illustrate this work. The analytical formula of the Gaussian Plume Model dispersion parameters in spherical coordinate was written. These parameters were calculated at different azimuth and polar angle and with different stability index and plotted in family of curves. This curves show a symmetrical distribution of the vertical and horizontal dispersion parameters around the polar angleπ /2

  19. FLOW PROPERTIES OF A DUSTY-GAS POINT SOURCE IN A SUPERSONIC FREE STREAM

    WANG Bo-yi(王柏懿); Alexander N.Osiptsov; Misha A.Teverovshii

    2003-01-01

    By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained. It is demonstrated that fairly inertial particles travel along oscillating and intersecting trajectories between the bow and termination shock waves. In this region,formation of "multi-layer structure" in particle distribution with alternating low- and highdensity layers is revealed. Moreover, sharp accumulation of particles occurs near the envelopes of particle trajectories.

  20. Atmospheric Modeling and Verification of Point Source Fossil Fuel CO2 Emissions

    Keller, E. D.; Turnbull, J. C.; Baisden, W. T.; Brailsford, G. W.; Bromley, T.; Norris, M. W.; Zondervan, A.

    2014-12-01

    Emissions from large point sources (electricity generation and large-scale industry) of fossil fuel CO2 (CO2ff) emissions are currently determined from self-reported "bottom-up" inventory data, with an uncertainty of about 20% for individual power plants. As the world moves towards a regulatory environment, there is a need for independent, objective measurements of these emissions both to improve the accuracy of and to verify the reported amounts. "Top-down" atmospheric methods have the potential to independently constrain point source emissions, combining observations with atmospheric transport modeling to derive emission estimates. We use the Kapuni Gas Treatment Plant to examine methodologies and model sensitivities for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes and vents CO2 from locally extracted natural gas at a rate of ~0.1 Tg carbon per year. We measured the CO2ff content in three different types of observations: air samples collected in flasks over a period of a few minutes, sodium hydroxide solution exposed the atmosphere, and grass samples from the surrounding farmland, the latter two representing ~1 week integrated averages. We use the WindTrax Lagrangian plume dispersion model to compare these atmospheric observations with "expected" values given the emissions reported by the Kapuni plant. The model has difficulty accurately capturing the short-term variability in the flask samples but does well in representing the longer-term averages from grass samples, suggesting that passive integrated-sampling methods have the potential to monitor long-term emissions. Our results indicate that using this method, point source emissions can be verified to within about 30%. Further improvements in atmospheric transport modelling are needed to reduce uncertainties. In view of this, we discuss model strengths and weaknesses and explore model sensitivity to meteorological conditions

  1. Solid angle subtended by a cylindrical detector at a point source in terms of elliptic integrals

    Prata, M. J.

    2002-01-01

    The solid angle subtended by a right circular cylinder at a point source located at an arbitrary position generally consists of a sum of two terms: that defined by the cylindrical surface ($\\Omega_{cyl}$) and the other by either of the end circles ($\\Omega_{circ}$). We derive an expression for $\\Omega_{cyl}$ in terms of elliptic integrals of the first and third kinds and give similar expressions for $\\Omega_{circ}$ using integrals of the first and second kinds. These latter can be used altern...

  2. A large gamma-ray telescope for point source studies above 1 GeV

    A large γ-ray telescope is described which is devoted to the observation of γ-ray point sources in the 1-100 GeV range. The principle of detection is based on imaging the Cerenkov light produced in a gas by the e+-e- conversion pair. The angular resolution for individual γ-rays is about 5 arcmin rms at 10 GeV. With a detection area of 7m2 and a 30% pair conversion efficiency the effective sensitive area is about 2x104 cm2 i.e. one order of magnitude larger than GAMMA 1 or EGRET

  3. Intermediate mass black holes and nearby dark matter point sources: a critical reassessment.

    Bringmann, Torsten; Lavalle, Julien; Salati, Pierre

    2009-10-16

    Dark matter (DM) "minispikes" around intermediate mass black holes are sometimes quoted as one of the most promising targets for indirect DM searches. Here, we stress that existing cosmic ray data place severe constraints on the possibility to detect DM annihilation signals from these objects in gamma rays; observational prospects for neutrinos or charged cosmic rays seem even worse. Similar bounds severely constrain the possibility that the excess in the cosmic ray positron or electron flux recently reported by PAMELA/ATIC could be due to a nearby point source like a DM clump or minispike. PMID:19905686

  4. Solid angle subtended by a cylindrical detector at a point source in terms of elliptic integrals

    The solid angle subtended by a right circular cylinder at a point source located at an arbitrary position generally consists of a sum of two terms: that defined by the cylindrical surface (Ωcyl) and the other by either of the end circles (Ωcirc). We derive an expression for Ωcyl in terms of elliptic integrals of the first and third kinds and give similar expressions for Ωcirc using integrals of the first and second kinds. These latter can be used alternatively to an expression also in terms of elliptic integrals, due to Philip A. Macklin and included as a footnote in Masket (Rev. Sci. Instrum. 28 (3) (1957) 191). The solid angle subtended by the whole cylinder when the source is located at an arbitrary location can then be calculated using elliptic integrals

  5. SEARCH FOR COSMIC NEUTRINO POINT SOURCES WITH FOUR YEARS OF DATA FROM THE ANTARES TELESCOPE

    Adrian-Martinez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigacio per a la Gestio Integrada de les Zones Costaneres (IGIC) - Universitat Politecnica de Valencia. C/Paranimf 1, E-46730 Gandia (Spain); Al Samarai, I.; Aubert, J-J.; Bertin, V.; Brunner, J. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit, BP 50568 - 68008 Colmar (France); Andre, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposicio, E-08800 Vilanova i la Geltru, Barcelona (Spain); Anghinolfi, M. [INFN - Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Anton, G. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Anvar, S. [Direction des Sciences de la Matiere - Institut de recherche sur les lois fondamentales de l' Univers - Service d' Electronique des Detecteurs et d' Informatique, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Astraatmadja, T.; Bogazzi, C.; Bouwhuis, M. C. [Nikhef, Science Park, Amsterdam (Netherlands); Baret, B.; Bouhou, B. [APC - Laboratoire AstroParticule et Cosmologie, UMR 7164 (CNRS, Universite Paris 7 Diderot, CEA, Observatoire de Paris) 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Basa, S. [LAM - Laboratoire d' Astrophysique de Marseille, Pole de l' Etoile Site de Chateau-Gombert, rue Frederic Joliot-Curie 38, F-13388 Marseille Cedex 13 (France); Biagi, S. [INFN - Sezione di Bologna, Viale Berti-Pichat 6/2, I-40127 Bologna (Italy); Bigongiari, C. [IFIC - Instituto de Fisica Corpuscular, Edificios Investigacion de Paterna, CSIC - Universitat de Valencia, Apdo. de Correos 22085, E-46071 Valencia (Spain); and others

    2012-11-20

    In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E {sup -2} {sub {nu}} spectrum, these flux limits are at 1-10 Multiplication-Sign 10{sup -8} GeV cm{sup -2} s{sup -1} for declinations ranging from -90 Degree-Sign to 40 Degree-Sign . Limits for specific models of RX J1713.7-3946 and Vela X, which include information on the source morphology and spectrum, are also given.

  6. Magnetic point sources in three dimensional Brans-Dicke gravity theories

    Dias, O J C; Dias, Oscar J. C.; Lemos, Jose' P. S.

    2002-01-01

    We obtain geodesically complete spacetimes generated by static and rotating magnetic point sources in an Einstein-Maxwell-Dilaton theory of the Brans-Dicke type in three dimensions (3D). The theory is specified by three fields, the dilaton, the graviton and the electromagnetic field, and two parameters, the cosmological constant and the Brans-Dicke parameter, w. When the Brans-Dicke parameter is infinity, our solution reduces to the magnetic counterpart of the BTZ solution, while the w=0 case is equivalent to 4D general relativity with one Killing vector. The source for the magnetic field can be interpreted as composed by a system of two symmetric and superposed electric charges. One of the electric charges is at rest and the other is spinning.

  7. Development of uniform hazard response spectra for rock sites considering line and point sources of earthquakes

    Traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to computed for PGA only. It is shown that the MRI associated with such response spectra are not the same at all frequencies. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for line and point sources of earthquakes by using a large number of strong motion accelerograms recorded on rock sites. Sensitivity of the number of the results to the changes in various parameters has also been presented. This work is an extension of an earlier work for aerial sources of earthquakes. These results will help to determine the seismic hazard at a given site and the associated uncertainities. (author)

  8. An Analytical Simple Formula for the Ground Level Concentration from a Point Source

    Daniela Buske

    2011-03-01

    Full Text Available The Advection-Diffusion Equation is solved for a constant pollutant emission from a point-like source placed inside an unstable Atmospheric Boundary Layer. The solution is obtained adopting the novel analytical approach: Generalized Integral Laplace Transform Technique. The concentration solution of the equation is expressed through an infinite series expansion. After setting a realistic scenario through the wind and diffusivity parameterizations, the Ground Level Concentration (GLC is determined, and an explicit approximate expression is provided for it, allowing an analytically simple expression for the position and value of the maximum. Remarks arise regarding the ability to express value and position of the GLC as explicit functions of the parameters defining the Atmospheric Boundary Layer scenario and the source height.

  9. Search for neutrino point sources with ANTARES 2007-2012 data

    Neutrinos are unique probes to study the high energy Universe, since they are neutral, only interact weakly and are stable. Furthermore, they can provide key information about several fundamental questions in Physics like the origin of cosmic rays and the nature of dark matter. The ANTARES neutrino telescope, installed in the Mediterranean Sea, has been taking data since 2007. In this paper we review the results concerning the search for point sources of cosmic neutrinos, using data of 2007–2012. Two main strategies have been followed: to look towards the direction of sources candidate to emmit neutrinos and to make an all-sky scan. Although no significant cluster has been found above the background, flux limits have been set at the level of E2φν90CL∼1–2×10−8 GeV cm−2s−1

  10. A method for untriggered time-dependent searches for multiple flares from neutrino point sources

    A method for a time-dependent search for flaring astrophysical sources which can be potentially detected by large neutrino experiments is presented. The method uses a time-clustering algorithm combined with an unbinned likelihood procedure. By including in the likelihood function a signal term which describes the contribution of many small clusters of signal-like events, this method provides an effective way for looking for weak neutrino flares over different time-scales. The method is sensitive to an overall excess of events distributed over several flares which are not individually detectable. For standard cases (one flare) the discovery potential of the method is worse than a standard time-dependent point source analysis with unknown duration of the flare by a factor depending on the signal-to-background level. However, for flares sufficiently shorter than the total observation period, the method is more sensitive than a time-integrated analysis. (orig.)

  11. Spherical earth gravity and magnetic anomaly analysis by equivalent point source inversion

    Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.

    1981-01-01

    To facilitate geologic interpretation of satellite elevation potential field data, analysis techniques are developed and verified in the spherical domain that are commensurate with conventional flat earth methods of potential field interpretation. A powerful approach to the spherical earth problem relates potential field anomalies to a distribution of equivalent point sources by least squares matrix inversion. Linear transformations of the equivalent source field lead to corresponding geoidal anomalies, pseudo-anomalies, vector anomaly components, spatial derivatives, continuations, and differential magnetic pole reductions. A number of examples using 1 deg-averaged surface free-air gravity anomalies of POGO satellite magnetometer data for the United States, Mexico, and Central America illustrate the capabilities of the method.

  12. Identifying non-point source critical source areas based on multi-factors at a basin scale with SWAT

    Liu, Ruimin; Xu, Fei; Zhang, Peipei; Yu, Wenwen; Men, Cong

    2016-02-01

    The identification of critical source areas (CSAs) is a precondition for non-point source (NPS) pollution control at a basin scale, especially in areas with limited resources. Based on the Soil and Water Assessment Tool (SWAT), nutrient loads coupled with population density and water quality requirements are regarded as multi-factors for CSAs identification in Xiangxi river watershed, the first tributary of the Yangtze River. The results based on the calibrated model found that the subbasins heavily and seriously polluted by nutrient loads were different from the subbasins identified as CSAs, demonstrating integrating socio-economic factors like population density and water quality requirements to identify CSAs is of much necessity. The CSAs occupied 19.7% of the total subbasins, and accounted for 53% total nitrogen loads, 54% total phosphorus loads and 36% of the total population. Considering the model calibration and validation will take a long time as well as data deficiency in some subbasins, the influence of uncalibrated SWAT on CSAs identifications was discussed. The comparative results between CSAs identification with calibrated and uncalibrated SWAT model revealed that model calibration had little effect on nutrients distribution and CSAs locations in the study area. Uncalibrated SWAT model may be applied when the research objective is less related to model calibration. The results will be greatly effective for CSAs identification and NPS pollution control at a basin scale.

  13. Bioluminescence imaging of point sources implanted in small animals post mortem: evaluation of a method for estimating source strength and depth

    The performance of a simple approach for the in vivo reconstruction of bioluminescent point sources in small animals was evaluated. The method uses the diffusion approximation as a forward model of light propagation from a point source in a homogeneous tissue to find the source depth and power. The optical properties of the tissue are estimated from reflectance images obtained at the same location on the animal. It was possible to localize point sources implanted in mice, 2-8 mm deep, to within 1 mm. The same performance was achieved for sources implanted in rat abdomens when the effects of tissue surface curvature were eliminated. The source power was reconstructed within a factor of 2 of the true power for the given range of depths, even though the apparent brightness of the source varied by several orders of magnitude. The study also showed that reconstructions using optical properties measured in situ were superior to those based on data in the literature

  14. CENTAURUS A AS A POINT SOURCE OF ULTRAHIGH ENERGY COSMIC RAYS

    We probe the possibility that Centaurus A (Cen A) is a point source of ultrahigh energy cosmic rays (UHECRs) observed by Pierre Auger Observatory (PAO), through the statistical analysis of the arrival direction distribution. For this purpose, we set up the Cen A dominance model for the UHECR sources, in which Cen A contributes the fraction f C of the whole UHECR with energy above 5.5 × 1019 eV and the isotropic background contributes the remaining 1 – f C fraction. The effect of the intergalactic magnetic fields on the bending of the trajectory of Cen A originated UHECRs is parameterized by the Gaussian smearing angle θ s. For the statistical analysis, we adopted the correlational angular distance distribution (CADD) for the reduction of the arrival direction distribution and the Kuiper test to compare the observed and the expected CADDs. We identify the excess of UHECRs in the Cen A direction and fit the CADD of the observed PAO data by varying two parameters f C and θ s of the Cen A dominance model. The best-fit parameter values are f C ≈ 0.1 (the corresponding Cen A fraction observed at PAO is f C,PAO ≈ 0.15, that is, about 10 out of 69 UHECRs) and θ s = 5° with the maximum likelihood L max = 0.29. This result supports the existence of a point source smeared by the intergalactic magnetic fields in the direction of Cen A. If Cen A is actually the source responsible for the observed excess of UHECRs, the rms deflection angle of the excess UHECRs implies the order of 10 nG intergalactic magnetic field in the vicinity of Cen A.

  15. Modeling of emissive properties and electron-optical parameters of ultrahigh brightness pointed field electron sources

    Full text: lt is well known that high brightness field electron sources are widely used in various electron probe analytical instruments and technological units. The reduced brightness (B) of electron probes formed by electron-optical systems (EOS) of those instruments and units may reach very high values (up to ∼ 108 A/(m2 sr V)). However, the known traditional applications do not exhaust the potentials of field (and thermal field) emission sources. Specifically, of considerable interest are the prospects for creating ultrahigh brightness electron beams. Forming electron beams with B >> 108 A/(m2 sr V) would make feasible development of a new class of electron probe instruments which will help to solve a number of current scientific and technological problems including those of micromechanics and microelectromechanics. Note that the main functional feature of such instruments is the possibility of in-depth analysis and surface modification of condensed matter exposed to an electronic beam whose power density (P) exceeds a threshold level necessary for the initiation of electron ablation. Since P ∞ B ∞ Bs, where Bs is the brightness of the electron source of EOS, the purpose of the present work was to study physical and technological aspects of the development of ultrahigh brightness pointed field electron sources. To solve the problem stated, one should first find an answer to the basic question, namely, whether Bs levels reached so far are maximum possible (or approach the physical limit for Bs) and, if not, how can we increase Bs of field emitters? To answer the above question, we studied emissive and electron-optical characteristics of various emitters in various modes of field emission, which include the following characteristic types of processes: Extended Schottky Emission, Thermal Field Emission (TFE), and finally ('pure') Field Emission. The numerical modeling of the electrostatic field potential distribution for a conventional electrode geometry in

  16. Semi analytical solution of point kinetic equation with source from cold start up to delayed critical

    Point kinetics equations (P. K. E) are system of differential equations, which is solved simultaneously to get the neutron density as a function of time for a given reactivity input. P. K. E are stiff differential equations, computational solution through the conventional explicit method will give a stable consistent result only for smaller time steps. Analytical solutions are available either with step or ramp reactivity insertion without considering the source power contribution. When a reactor operates at low power, the neutron source gives a considerable contribution to the net reactor power. Similarly, when the reactor is brought to delayed critical with the presence of external source, the sub critical reactor kinetics studies with source power are important to understand the power behavior as a function of reactivity insertion rate with respect to the initial reactivity. In the present work, P.K.E with one group delayed neutron are solved analytically to determine the reactor power as a function of reactivity insertion rate in the presence of neutron source. The analytical solution is a combination of converging two infinite series. Truncated infinite series is the analytical solution of P.K E. A general formulation is made by Combining both the ramp reactivity and step reactivity solution. So that the analytical solution could be useful in analyzing either step and ramp reactivity insertion exclusively or the combination of both. This general formulation could be useful in analyzing many reactor operations, like the air bubble passing through the core, stuck rod conditions, uncontrolled withdrawal of controlled rod, discontinuous lifting of control rod, lowering of rod and etc. Results of analytical solutions are compared against the results of numerical solution which is developed based on Cohen's method. The comparisons are found to be good for all kind of positive and negative ramp reactivity insertions, with or without the combination of step reactivity

  17. Data library of gamma-ray buildup factors for point isotropic source

    Gamma-ray buildup factors for a point isotropic source have been calculated as a function of atomic number of heavy elements and source energies over an energy range from 0.015 MeV to 15 MeV, for penetration depths up to 40 mfp, bu the PALLAS-PL,SP-Br code. These data include the contribution of bremsstrahlung, annihilation radiation and fluorescence X-ray. The calculated absorbed-dose, exposure and dose-equivalent buildup factors are tabulated for molybdenum, tin, tungsten, lead and uranium, which are practical interest shield materials, lanthanum and gadolinium which are important materials for obtaining buildup factors by interpolation with the atomic number. In the case of high atomic number materials, inclusion of brems-strahlung source has great influence on the buildup factors for high source energies and that of fluorescence X-ray gives spectracular effects on those for low energies close to the K edge of attenuation cross section. Furthermore, the geometrical-progression (G-P) parameters have been determined for these buildup factors in order to obtain the values of buildup factors at arbitrary distances and energies. (author)

  18. Seasonal and spatial variation of diffuse (non-point) source zinc pollution in a historically metal mined river catchment, UK

    Quantifying diffuse sources of pollution is becoming increasingly important when characterising river catchments in entirety - a prerequisite for environmental management. This study examines both low and high flow events, as well as spatial variability, in order to assess point and diffuse components of zinc pollution within the River West Allen catchment, which lies within the northern England lead-zinc Orefield. Zinc levels in the river are elevated under all flow regimes, and are of environmental concern. Diffuse components are of little importance at low flow, with point source mine water discharges dominating instream zinc concentration and load. During higher river flows 90% of the instream zinc load is attributed to diffuse sources, where inputs from resuspension of metal-rich sediments, and groundwater influx are likely to be more dominant. Remediating point mine water discharges should significantly improve water quality at lower flows, but contribution from diffuse sources will continue to elevate zinc flux at higher flows. - Highlights: → Zinc concentrations breach EU quality thresholds under all river flow conditions. → Contributions from point sources dominate instream zinc dynamics in low flow. → Contributions from diffuse sources dominate instream zinc dynamics in high flow. → Important diffuse sources include river-bed sediment resuspension and groundwater influx. → Diffuse sources would still create significant instream pollution, even with point source treatment. - Diffuse zinc sources are an important source of instream contamination to mine-impacted rivers under varying flow conditions.

  19. NUMERICAL SIMULATION OF SUMMER CIRCULATION IN THE EAST CHINA SEA AND ITS APPLICATION IN ESTIMATING THE SOURCES OF RED TIDES IN THE YANGTZE RIVER ESTUARY AND ADJACENT SEA AREAS

    CHEN Xiu-hua; ZHU Liang-sheng; ZHANG Hong-sheng

    2007-01-01

    Based on the COHERENS (a Coupled Hydrodynamical Ecological model for Regional Shelf seas), a three-dimensional baroclinic model for the summer of East China Sea (ECS) was established with the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. The circulation patterns of the Kuroshio Current, the Taiwan Warm Current (TWC), the Tsushima Current and the Yangtze Diluted Water (YDW) were successfully simulated with this model. The calculated results are fairly consistent with previous observations and studies. Based on this baroclinic current field, the Lagranian particles tracking was simulated to estimate the possible origins of the red tides frequently occurring in the Yangtze River estuary and its adjacent sea areas. If there are "seeds" (cysts) of the red tide algae at the seabed of the Taiwan Strait, the offshore of Fujian and Zhejiang Provinces and the northeast Taiwan Island, those are extremely possible sources of the red tides in the Yangtze River estuary and its adjacent sea areas. Field data are needed to confirm it. Numerical simulation to estimate the source of the red tides is a new application of the Lagrangian transport in the marine ecology.

  20. Discriminating between point and non-point sources of atrazine contamination of a sandy aquifer. Sci. Total Environ.

    Leterme, Bertrand

    2006-01-01

    This study analyses the sources of atrazine contamination in the Brusselian sandy aquifer of central Belgium. Atrazine has in the past been used for both agricultural and non-agricultural applications, but it is difficult to distinguish the contamination originating from these two sources. The spatial and temporal covariance of atrazine concentrations was studied by fitting semi-variogram models to monitoring data. Correlation ranges were found to be 600 m and 600-700 days, respectively. The ...

  1. Analytical approximation of the dose distribution from point beta-sources

    A new method for analytical calculation of the beta-ray dose from point sources which accounts for the total beta-spectrum shape are presented and the results are compared to calculations of Loevinger and the Monte-Carlo groups. The most important feature is that it can be used for the resultant sum of several spectra and also for distorted or experimentally measured spectra. The method uses tabulated values for the specific energy lost and calculated or measured values for the shape of the total spectrum from nuclide or mixture of nuclides. The approach have been tested with isotopes with different beta-ray shapes(90Sr, 90Y) and in the presence of conversion electrons - 137Cs. 106Rh is included because of high Emax = 3.54 MeV. The agreement of the proposed method with the Monte-Carlo simulations is very good. The chosen spectra are with very different initial shape, which confirms the applicability of the approach. The major deviation is for the large distances due to the limited accuracy of the Loevinger method. The approach can be used for the soft biological tissue and for other than point sources. For the skin contamination it is necessary the backscattering electrons to be taken into account. An initial version of the approach has been used for calculations of beta-ray doses due to hot particles after the Chernobyl accident

  2. Fast and mechanistic ultrasound simulation using a point source/receiver approach.

    Aguilar, Luis A; Cobbold, Richard S C; Steinman, David A

    2013-11-01

    Ultrasound simulators relying on impulse response methods are faithful to the mechanisms of image formation from the underlying radio-frequency signals, but as a result tend to be relatively slow. At the other extreme are fast techniques, often motivated by the development of teaching and training simulators, which approximate the image formation processes rather than rigorously modeling the underlying physics. Previously, we have shown that transmit field distributions from linear phased-array transducers can be modeled accurately and efficiently using arrays of point sources. This approach is now extended to point sources/receivers, which allows for simulation of the transmit/receive fields, and thus the physical processes underlying ultrasound image formation. Field distributions and fast-time signals are shown to compare favorably to those obtained using the impulse response method. Doppler spectrogram and B-mode images derived from these signals also show excellent agreement with the results obtained using the impulse response method, but with a computational savings of nearly two orders of magnitude. Because of the inherent simplicity of our Fast and Mechanistic Ultrasound Simulation (FAMUS) approach, CPU parallelization was readily achieved, and further orders of magnitude speed improvements, and thus real-time performance, can be anticipated via extension to modern graphics processing units. PMID:24158289

  3. Spitzer infrared spectrograph point source classification in the Small Magellanic Cloud

    Ruffle, Paul M. E.; Kemper, F.; Jones, O. C.; Sloan, G. C.; Kraemer, K. E.; Woods, Paul M.; Boyer, M. L.; Srinivasan, S.; Antoniou, V.; Lagadec, E.; Matsuura, M.; McDonald, I.; Oliveira, J. M.; Sargent, B. A.; Sewiło, M.; Szczerba, R.; van Loon, J. Th.; Volk, K.; Zijlstra, A. A.

    2015-08-01

    The Magellanic Clouds are uniquely placed to study the stellar contribution to dust emission. Individual stars can be resolved in these systems even in the mid-infrared, and they are close enough to allow detection of infrared excess caused by dust. We have searched the Spitzer Space Telescope data archive for all Infrared Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) and found that 209 Infrared Array Camera (IRAC) point sources within the footprint of the Surveying the Agents of Galaxy Evolution in the Small Magellanic Cloud (SAGE-SMC) Spitzer Legacy programme were targeted, within a total of 311 staring-mode observations. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information. We find 58 asymptotic giant branch (AGB) stars, 51 young stellar objects, 4 post-AGB objects, 22 red supergiants, 27 stars (of which 23 are dusty OB stars), 24 planetary nebulae (PNe), 10 Wolf-Rayet stars, 3 H II regions, 3 R Coronae Borealis stars, 1 Blue Supergiant and 6 other objects, including 2 foreground AGB stars. We use these classifications to evaluate the success of photometric classification methods reported in the literature.

  4. AKARI Infrared Camera Survey of the Large Magellanic Cloud. I. Point Source Catalog

    Kato, Daisuke; Onaka, Takashi; Tanabe, Toshihiko; Shimonishi, Takashi; Sakon, Itsuki; Kaneda, Hidehiro; Kawamura, Akiko; Wada, Takehiko; Usui, Fumihiko; Koo, Bon-Chul; Matsuura, Mikako; Takahashi, Hidenori

    2012-01-01

    We present a near- to mid-infrared point source catalog of 5 photometric bands at 3.2, 7, 11, 15 and 24 um for a 10 deg2 area of the Large Magellanic Cloud (LMC) obtained with the Infrared Camera (IRC) onboard the AKARI satellite. To cover the survey area the observations were carried out at 3 separate seasons from 2006 May to June, 2006 October to December, and 2007 March to July. The 10-sigma limiting magnitudes of the present survey are 17.9, 13.8, 12.4, 9.9, and 8.6 mag at 3.2, 7, 11, 15 and 24 um, respectively. The photometric accuracy is estimated to be about 0.1 mag at 3.2 um and 0.06--0.07 mag in the other bands. The position accuracy is 0.3" at 3.2, 7 and 11um and 1.0" at 15 and 24 um. The sensitivities at 3.2, 7, and 24 um are roughly comparable to those of the Spitzer SAGE LMC point source catalog, while the AKARI catalog provides the data at 11 and 15 um, covering the mid-infrared spectral range contiguously. Two types of catalog are provided: a Catalog and an Archive. The Archive contains all the...

  5. Estimation of Methane Emissions from Municipal Solid Waste Landfills in China Based on Point Emission Sources

    CAI Bo-Feng; LIU Jian-Guo; GAO Qing-Xian; NIE Xiao-Qin; CAO Dong; LIU Lan-Cui; ZHOU Ying; ZHANG Zhan-Sheng

    2014-01-01

    The methane (CH4) emissions from municipal solid waste (MSW) landfills in China in 2007 were estimated based on database of the three-dimensional emission factors matrix and point sources, by an IPCC recommended FOD (first-order decay) model. The location, capacity and age of landfills constitute the three dimensions of the emission factors matrix, which were obtained by laboratory analysis and in situ investigation. Key parameters such as waste composition, degradable organic carbon ratio, CH4 correction factor, oxidation factor and recovery rate, were carefully analyzed in terms of these three dimensions. The point sources database consists of 2,107 MSW landfills in cities and towns of China in 2007. The results show that the CH4 emissions from MSW landfills were 1.186 Mt in 2007. Compared with the CH4 emissions of 2.20 Mt in 2005, the significant discrepancy mainly comes from statistical data of landfills, e.g., number of landfills and amount of waste disposed in landfills. CH4 emissions were lower than 700 t for most of the landfills, whereas there were 279 landfills with emissions larger than 1,000 t, and only 10 landfills with emissions larger than 10,000 t. Jiangsu province ranks the largest emitter with 98,700 t while Tibet is the smallest emitter with 2,100 t. In general, the emissions from eastern provinces, such as Jiangsu, Guangdong and Zhejiang, were larger than those from western provinces, such as Ningxia, Tibet and Qinghai.

  6. Current status of agricultural and rural non-point source Pollution assessment in China

    Estimates of non-point source (NPS) contribution to total water pollution in China range up to 81% for nitrogen and to 93% for phosphorus. We believe these values are too high, reflecting (a) misuse of estimation techniques that were developed in America under very different conditions and (b) lack of specificity on what is included as NPS. We compare primary methods used for NPS estimation in China with their use in America. Two observations are especially notable: empirical research is limited and does not provide an adequate basis for calibrating models nor for deriving export coefficients; the Chinese agricultural situation is so different than that of the United States that empirical data produced in America, as a basis for applying estimation techniques to rural NPS in China, often do not apply. We propose a set of national research and policy initiatives for future NPS research in China. - Estimation techniques used in China for non-point source pollution are evaluated as a basis for recommending future policies and research in NPS studies in China.

  7. Guided wave radiation from a point source in the proximity of a pipe bend

    Throughout the oil and gas industry corrosion and erosion damage monitoring play a central role in managing asset integrity. Recently, the use of guided wave technology in conjunction with tomography techniques has provided the possibility of obtaining point-by-point maps of wall thickness loss over the entire volume of a pipeline section between two ring arrays of ultrasonic transducers. However, current research has focused on straight pipes while little work has been done on pipe bends which are also the most susceptible to developing damage. Tomography of the bend is challenging due to the complexity and computational cost of the 3-D elastic model required to accurately describe guided wave propagation. To overcome this limitation, we introduce a 2-D anisotropic inhomogeneous acoustic model which represents a generalization of the conventional unwrapping used for straight pipes. The shortest-path ray-tracing method is then applied to the 2-D model to compute ray paths and predict the arrival times of the fundamental flexural mode, A0, excited by a point source on the straight section of pipe entering the bend and detected on the opposite side. Good agreement is found between predictions and experiments performed on an 8” diameter (D) pipe with 1.5 D bend radius. The 2-D model also reveals the existence of an acoustic lensing effect which leads to a focusing phenomenon also confirmed by the experiments. The computational efficiency of the 2-D model makes it ideally suited for tomography algorithms

  8. plas.io: Open Source, Browser-based WebGL Point Cloud Visualization

    Butler, H.; Finnegan, D. C.; Gadomski, P. J.; Verma, U. K.

    2014-12-01

    Point cloud data, in the form of Light Detection and Ranging (LiDAR), RADAR, or semi-global matching (SGM) image processing, are rapidly becoming a foundational data type to quantify and characterize geospatial processes. Visualization of these data, due to overall volume and irregular arrangement, is often difficult. Technological advancement in web browsers, in the form of WebGL and HTML5, have made interactivity and visualization capabilities ubiquitously available which once only existed in desktop software. plas.io is an open source JavaScript application that provides point cloud visualization, exploitation, and compression features in a web-browser platform, reducing the reliance for client-based desktop applications. The wide reach of WebGL and browser-based technologies mean plas.io's capabilities can be delivered to a diverse list of devices -- from phones and tablets to high-end workstations -- with very little custom software development. These properties make plas.io an ideal open platform for researchers and software developers to communicate visualizations of complex and rich point cloud data to devices to which everyone has easy access.

  9. Uncertainty Analysis of non-point source pollution control facilities design techniques in Korea

    Lee, J.; Okjeong, L.; Gyeong, C. B.; Park, M. W.; Kim, S.

    2015-12-01

    The design of non-point sources control facilities in Korea is divided largely by the stormwater capture ratio, the stormwater load capture ratio, and the pollutant reduction efficiency of the facility. The stormwater capture ratio is given by a design formula as a function of the water quality treatment capacity, the greater the capacity, the more the amount of stormwater intercepted by the facility. The stormwater load capture ratio is defined as the ratio of the load entering the facility of the total pollutant load generated in the target catchment, and is given as a design formula represented by a function of the stormwater capture ratio. In order to estimate the stormwater capture ratio and load capture ratio, a lot of quantitative analysis of hydrologic processes acted in pollutant emission is required, but these formulas have been applied without any verification. Since systematic monitoring programs were insufficient, verification of these formulas was fundamentally impossible. However, recently the Korean ministry of Environment has conducted an long-term systematic monitoring project, and thus the verification of the formulas became possible. In this presentation, the stormwater capture ratio and load capture ratio are re-estimated using actual TP data obtained from long-term monitoring program at Noksan industrial complex located in Busan, Korea. Through the re-estimated process, the uncertainty included in the design process that has been applied until now will be shown in a quantitative extent. In addition, each uncertainty included in the stormwater capture ratio estimation and in the stormwater load capture ratio estimation will be expressed to quantify the relative impact on the overall non-point pollutant control facilities design process. Finally, the SWMM-Matlab interlocking module for model parameters estimation will be introduced. Acknowledgement This subject is supported by Korea Ministry of Environment as "The Eco Innovation Project : Non-point

  10. Effects of point-source PCB contamination on breeding performance and post-fledging survival in the dipper Cinclus cinclus.

    Ormerod, S J; Tyler, S J; Jüttner, I

    2000-12-01

    Despite widespread information on the incidence and biochemical effects of polychlorinated biphenyls (PCBs) in birds, field studies of effects on population processes are still scarce. This is particularly so in passerines. We therefore assessed breeding performance and post-fledging survival in dippers, Cinclus cinclus, breeding along the Afon Mule, a Welsh river where previous work indicated locally elevated PCB concentrations. We hypothesised that marked toxicological effects, including endocrine disruption, would be detectable as altered clutch-size, hatching success, nest success, brood-size, post-fledging survival or recruitment to the breeding population. Congener-specific analysis of PCBs in failed and deserted dipper eggs during 1990-93 revealed that geometric mean concentrations were four to 20 times higher along the Mule than elsewhere in Wales, UK. PCB signatures also varied highly significantly from other locations, with congeners 138, 153 and 180 dominant at the contaminated site, but 118 or 170 more frequent in eggs elsewhere. Subsequent analysis of surface runoff confirmed a small breaker's yard as a point source. Neither laying dates, clutch-sizes, brood-sizes, nest failure nor hatching failure along the contaminated Mule (n=46 breeding attempts and 218 eggs) differed significantly from dippers along adjacent reference rivers (n=82 breeding attempts and 315 eggs) or Welsh rivers as a whole (n=332 breeding attempts and 1534 eggs). Subsequent recaptures of breeding dippers ringed initially as nestlings were nearly identical between the Mule (7.7% of 182 nestlings), the reference set (7.5% of 323 nestlings) and all other Welsh rivers (7.3% of 2821 nestlings). These data illustrate the value of congener-specific analysis of bird's eggs in indicating local PCB sources. The data show also that PCBs can occur in dipper eggs at total concentrations of 0.49 (geometric mean)-1.29 (upper quartile) microg g(-1) wet mass without effects on breeding performance

  11. The Degree of Farmers’ Cognition on Non-point Source Pollution:Based on the Statistical Analysis of 453 Farmers

    Qian; BI; Huaiye; WANG; Jue; PENG

    2014-01-01

    With the rapid development of modern agriculture,agricultural non-point source pollution becomes increasingly serious in China,improving farmers’ environmental protection consciousness plays a very important role in the reduction of agricultural non-point source pollution.Therefore,this investigation and study chooses rural areas of five counties from Chongqing city and Zhejiang province as our samples,our investigation and statistical analysis includes the following four aspects:farmers’ cognition on non-point source pollution concept,farmers’ cognition to rural environment satisfaction,farmers’ cognition on non-point source pollution in agricultural production and farmers’ cognition on the consequences of agricultural non-point source pollution and the effects on ecological environment.The analysis and conclusions of farmers’ consciousness cognition on agricultural non-point source pollution,provides the supports in theory and practice for optimizing the behavior of farmers,promoting the management of agricultural non-point source pollution and implementing new rural construction goal.

  12. Validation of Point Source Emissions of SO2 Using Aircraft Data

    Fiddler, M. N.; Green, J. R.; Bililign, S.; McDuffie, E.; Fibiger, D. L.; Brown, S. S.; Jaegle, L.; Weinheimer, A. J.; Thornton, J. A.; Campos, T. L.; Shah, V.; Lopez-Hilfiker, F.; Lee, B. H.; Haskins, J.; Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Cohen, R. C.; Veres, P. R.; Dibb, J. E.; Schroder, J. C.; Campuzano-Jost, P.; Day, D. A.; Jimenez, J. L.; Sullivan, A.; Guo, H.; Weber, R. J.; Leen, J. B.; DiGangi, J. P.; Wolfe, G. M.

    2015-12-01

    Emissions inventories of SO2 in the Eastern United States have largely relied on point source measurements from power plants. A comparison will be made between these source measurements and in situ measurements using the TECO 43C SO2 analyzer a CO/CO2 analyzer during an airborne platform aboard the NCAR C-130 plane during wintertime conditions, which was part of a suite of measurements taken during the Wintertime Investigation of Transport, Emission, and Reactivity (WINTER) 2015 field campaign. The data obtained originates from a series of survey night and day flights that occurred from Feb 3 to Mar 13, 2015 over the Eastern coastal region of the United States ranging from New York to Florida. SO2/CO2 mixing ratios will be compared from three sources: power plant emission values (taking into account dispersion), chemical forecast predictions, and aircraft data. During the winter the removal processes for gaseous SO2 are slower, which results in a measurably longer atmospheric lifetime. Loss, emission, and dispersion rates will be discussed.

  13. Evidence for Unresolved γ-Ray Point Sources in the Inner Galaxy.

    Lee, Samuel K; Lisanti, Mariangela; Safdi, Benjamin R; Slatyer, Tracy R; Xue, Wei

    2016-02-01

    We present a new method to characterize unresolved point sources (PSs) generalizing traditional template fits to account for non-Poissonian photon statistics. We apply this method to Fermi Large Area Telescope γ-ray data to characterize PS populations at high latitudes and in the Inner Galaxy. We find that PSs (resolved and unresolved) account for ∼50% of the total extragalactic γ-ray background in the energy range ∼1.9 to 11.9 GeV. Within 10° of the Galactic Center with |b|≥2°, we find that ∼5%-10% of the flux can be accounted for by a population of unresolved PSs distributed consistently with the observed ∼GeV γ-ray excess in this region. The excess is fully absorbed by such a population, in preference to dark-matter annihilation. The inferred source population is dominated by near-threshold sources, which may be detectable in future searches. PMID:26894697

  14. Analytical dispersion model for the chain of primary and secondary air pollutants released from point source

    Juodis, Laurynas; Filistovič, Vitold; Maceika, Evaldas; Remeikis, Vidmantas

    2016-03-01

    An analytical model for dispersion of air pollutants released from a point source forming a secondary pollutant (e.g. chemical transformation or parent-daughter radionuclide chain) is formulated considering the constant wind speed and eddy diffusivities as an explicit function of downwind distance from the source in Cauchy (reflection-deposition type) boundary conditions. The dispersion of pollutants has been investigated by using the Gaussian plume dispersion parameters σy and σz instead of the diffusivity parameters Ky and Kz. For primary pollutant it was proposed to use the derived dry deposition factor instead of the source depletion alternative. An analytical solution for steady-state two-dimensional pollutant transport in the atmosphere is presented. Derived formulas include dependency from effective release height, gravitational and dry deposition velocities of primary and secondary pollutants, advection, surface roughness length and empirical dispersion parameters σy and σz. Demonstration of analytical solution application is provided by calculation of 135Xe and 135C air activity concentrations and the applicability of the model for the solution of atmospheric pollution transport problems.

  15. The precipitation driven correlation based mapping method (PCM) for identifying the critical source areas of non-point source pollution

    Huang, Jinhui Jeanne; Lin, Xiaojuan; Wang, Jianhua; Wang, Hao

    2015-05-01

    Critical source areas (CSAs) are the areas that are relatively more erosion-prone and contribute significantly more pollutants per unit area. They have been widely recognized as optimal locations for the control of non-point source (NPS) pollution. Modeling approach has been frequently used to identify the CSAs of NPS pollution on a basin scale. In previous studies, CSAs were identified based on the simulated average annual nutrient yields for the simulation period at the levels of sub-basin or hydrologic response unit (HRU). However, this method did not consider the impact of uneven spatial distribution of precipitation, which is considered to be the driven force of NPS pollution. In many cases, due to limited length of qualified monitoring data collected, the simulation period may not cover a full spectrum of the precipitation characteristics so that some potential CSAs may be missed. In the present study, the precipitation driven correlation based mapping method (PCM) was proposed, which can reduce the impact of uncertain spatial-temporal distribution of precipitation and identify the CSAs of NPS pollution with a better coverage. This method was applied to the Zhang River Basin, a watershed in North China that occupies an area of 18,072 km2. The SWAT (Soil and Water Assessment Tool) was used for simulation purposes. By using PCM, the maps of CSAs for controlling total nitrogen (TN) and total phosphorus (TP) were produced. This study has found that the monthly precipitation is highly correlated with the TN and TP yields. It was observed that TN yields have slightly higher correlation value with the precipitation than TP yields. Hence, the precipitation has more impacts on TN yields than TP yields. The impact is more substantial in urban areas than other areas.

  16. The XXL Survey. VI. The 1000 brightest X-ray point sources

    Fotopoulou, S.; Pacaud, F.; Paltani, S.; Ranalli, P.; Ramos-Ceja, M. E.; Faccioli, L.; Plionis, M.; Adami, C.; Bongiorno, A.; Brusa, M.; Chiappetti, L.; Desai, S.; Elyiv, A.; Lidman, C.; Melnyk, O.; Pierre, M.; Piconcelli, E.; Vignali, C.; Alis, S.; Ardila, F.; Arnouts, S.; Baldry, I.; Bremer, M.; Eckert, D.; Guennou, L.; Horellou, C.; Iovino, A.; Koulouridis, E.; Liske, J.; Maurogordato, S.; Menanteau, F.; Mohr, J. J.; Owers, M.; Poggianti, B.; Pompei, E.; Sadibekova, T.; Stanford, A.; Tuffs, R.; Willis, J.

    2016-06-01

    Context. X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). Usually, a combination of deep and wide surveys is necessary to create a complete picture of the population. Deep X-ray surveys provide the faint population at high redshift, while wide surveys provide the rare bright sources. Nevertheless, very wide area surveys often lack the ancillary information available for modern deep surveys. The XXL survey spans two fields of a combined 50 deg2 observed for more than 6Ms with XMM-Newton, occupying the parameter space that lies between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. Aims: This paper marks the first release of the XXL point source catalogue including four optical photometry bands and redshift estimates. Our sample is selected in the 2 - 10 keV energy band with the goal of providing a sizable sample useful for AGN studies. The limiting flux is F2 - 10 keV = 4.8 × 10-14 erg s-1 cm-2. Methods: We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources by means of a likelihood ratio test. We improve upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift category (passive, star forming, starburst, AGN, quasi-stellar objects (QSO)). Additionally, we assign a probability to each source that indicates whether it might be a star or an outlier. We apply Bayesian analysis to model the X-ray spectra assuming a power-law model with the presence of an absorbing medium. Results: We find that the average unabsorbed photon index is ⟨Γ⟩ = 1.85 ± 0.40 while the average hydrogen column density is log ⟨NH⟩ = 21.07 ± 1.2 cm-2. We find no trend of Γ or NH with redshift and a fraction of 26% absorbed sources (log NH> 22) consistent with the literature on bright sources (log

  17. Analytical calculation of the solid angle defined by a cylindrical detector and a point cosine source with parallel axes

    We derive analytical expressions for the solid angle subtended by a right finite circular cylinder at a point source with cosine angular distribution in the case where the source direction is parallel to the cylinder axis. As a subsidiary result, an expression for the solid angle subtended by a disc detector at a spread disc source is also provided, in the case where the two discs have a common symmetry axis which is also coincident with the source direction

  18. Quantitative Analysis of VIIRS DNB Nightlight Point Source for Light Power Estimation and Stability Monitoring

    Changyong Cao

    2014-12-01

    Full Text Available The high sensitivity and advanced onboard calibration on the Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band (DNB enables accurate measurements of low light radiances which leads to enhanced quantitative applications at night. The finer spatial resolution of DNB also allows users to examine social economic activities at urban scales. Given the growing interest in the use of the DNB data, there is a pressing need for better understanding of the calibration stability and absolute accuracy of the DNB at low radiances. The low light calibration accuracy was previously estimated at a moderate 15% using extended sources while the long-term stability has yet to be characterized. There are also several science related questions to be answered, for example, how the Earth’s atmosphere and surface variability contribute to the stability of the DNB measured radiances; how to separate them from instrument calibration stability; whether or not SI (International System of Units traceable active light sources can be designed and installed at selected sites to monitor the calibration stability, radiometric and geolocation accuracy, and point spread functions of the DNB; furthermore, whether or not such active light sources can be used for detecting environmental changes, such as aerosols. This paper explores the quantitative analysis of nightlight point sources, such as those from fishing vessels, bridges, and cities, using fundamental radiometry and radiative transfer, which would be useful for a number of applications including search and rescue in severe weather events, as well as calibration/validation of the DNB. Time series of the bridge light data are used to assess the stability of the light measurements and the calibration of VIIRS DNB. It was found that the light radiant power computed from the VIIRS DNB data matched relatively well with independent assessments based on the in situ light installations, although estimates have to be

  19. Impacts by point and diffuse micropollutant sources on the stream water quality at catchment scale

    Petersen, M. F.; Eriksson, E.; Binning, P. J.; Bjerg, P. L.

    2012-04-01

    The water quality of surface waters is threatened by multiple anthropogenic pollutants and the large variety of pollutants challenges the monitoring and assessment of the water quality. The aim of this study was to characterize and quantify both point and diffuse sources of micropollutants impacting the water quality of a stream at catchment scale. Grindsted stream in western Jutland, Denmark was used as a study site. The stream passes both urban and agricultural areas and is impacted by severe groundwater contamination in Grindsted city. Along a 12 km reach of Grindsted stream, the potential pollution sources were identified including a pharmaceutical factory site with a contaminated old drainage ditch, two waste deposits, a wastewater treatment plant, overflow structures, fish farms, industrial discharges and diffuse agricultural and urban sources. Six water samples were collected along the stream and analyzed for general water quality parameters, inorganic constituents, pesticides, sulfonamides, chlorinated solvents, BTEXs, and paracetamol and ibuprofen. The latter two groups were not detected. The general water quality showed typical conditions for a stream in western Jutland. Minor impacts by releases of organic matter and nutrients were found after the fish farms and the waste water treatment plant. Nickel was found at concentrations 5.8 - 8.8 μg/l. Nine pesticides and metabolites of both agricultural and urban use were detected along the stream; among these were the two most frequently detected and some rarely detected pesticides in Danish water courses. The concentrations were generally consistent with other findings in Danish streams and in the range 0.01 - 0.09 μg/l; except for metribuzin-diketo that showed high concentrations up to 0.74 μg/l. The groundwater contamination at the pharmaceutical factory site, the drainage ditch and the waste deposits is similar in composition containing among others sulfonamides and chlorinated solvents (including vinyl

  20. Observation of MWCNTs with low-energy electron point source microscope

    Yu Jie; Bai Xin; Zhang Zhao-Xiang; Zhang Geng-Min; Guo Deng-Zhu; Xue Zeng-Quan

    2006-01-01

    The low-energy electron point source (LEEPS) microscope, which creates enlarged projection images with lowenergy field emission electron beams, can be used to observe the projection image of nano-scale samples and to characterize the coherence of the field emission beam. In this paper we report the design and test operation performance of a home-made LEEPS microscope. Multi-walled carbon nanotubes (MWCNTs) synthesized by the CVD method were observed by LEEPS microscope using a conventional tungsten tip, and projection images with the magnification of up to 104 was obtained. The resolution of the acquired images is ~10 nm. A higher resolution and a larger magnification can be expected when the AC magnetic field inside the equipment is shielded and the vibration of the instrument reduced.

  1. Isotopic Tracers for Delineating Non-Point Source Pollutants in Surface Water

    Davisson, M L

    2001-03-01

    This study tested whether isotope measurements of surface water and dissolved constituents in surface water could be used as tracers of non-point source pollution. Oxygen-18 was used as a water tracer, while carbon-14, carbon-13, and deuterium were tested as tracers of DOC. Carbon-14 and carbon-13 were also used as tracers of dissolved inorganic carbon, and chlorine-36 and uranium isotopes were tested as tracers of other dissolved salts. In addition, large databases of water quality measurements were assembled for the Missouri River at St. Louis and the Sacramento-San Joaquin Delta in California to enhance interpretive results of the isotope measurements. Much of the water quality data has been under-interpreted and provides a valuable resource to investigative research, for which this report exploits and integrates with the isotope measurements.

  2. Modeling a point-source release of 1,1,1-trichloroethane using EPA's SCREEN model

    Using data from the Environmental Protection Agency's Toxic Release Inventory 1988 (EPA TRI88), pollutant concentration estimates were modeled for a point source air release of 1,1,1-trichloroethane at the Savannah River Plant located in Aiken, South Carolina. Estimates were calculating using the EPA's SCREEN model utilizing typical meteorological conditions to determine maximum impact of the plume under different mixing conditions for locations within 100 meters of the stack. Input data for the SCREEN model were then manipulated to simulate the impact of the release under urban conditions (for the purpose of assessing future landuse considerations) and under flare release options to determine if these parameters lessen or increase the probability of human or wildlife exposure to significant concentrations. The results were then compared to EPA reference concentrations (RfC) in order to assess the size of the buffer around the stack which may potentially have levels that exceed this level of safety

  3. The point-source method for 3D reconstructions for the Helmholtz and Maxwell equations

    Ben Hassen, M. F.; Erhard, K.; Potthast, R.

    2006-02-01

    We use the point-source method (PSM) to reconstruct a scattered field from its associated far field pattern. The reconstruction scheme is described and numerical results are presented for three-dimensional acoustic and electromagnetic scattering problems. We give new proofs of the algorithms, based on the Green and Stratton-Chu formulae, which are more general than with the former use of the reciprocity relation. This allows us to handle the case of limited aperture data and arbitrary incident fields. Both for 3D acoustics and electromagnetics, numerical reconstructions of the field for different settings and with noisy data are shown. For shape reconstruction in acoustics, we develop an appropriate strategy to identify areas with good reconstruction quality and combine different such regions into one joint function. Then, we show how shapes of unknown sound-soft scatterers are found as level curves of the total reconstructed field.

  4. MHD Evolution in Point-Source Helicity Injection Driven Plasmas on Pegasus

    Barr, J. L.; Bongard, M. W.; Burke, M. G.; Fonck, R. J.; Hinson, E. T.; Redd, A. J.

    2011-10-01

    Point-source helicity injection for non-solenoidal startup on PEGASUS produces plasmas with Ip = 10 V to <= 2 V. Supplemental loop voltage from poloidal field induction is used to obtain higher plasma current. Ip growth is accompanied by bursts of n = 1 magnetic activity with frequencies between 10-150 kHz, abrupt inward motion of the plasma, and a drop in internal inductance. This magnetic activity persists during helicity injection. Afterward, MHD quiescence is obtained and persists in discharges subsequently sustained by ohmic induction. The spectral content of these magnetic fluctuations measured with a scanning Mirnov probe does not differ significantly with distance from the plasma edge. Work supported by US DOE Grant DE-FG02-96ER54375.

  5. Modified Weighting for Calculating the Average Concentration of Non-Point Source Pollutant

    牟瑞芳

    2004-01-01

    The concentration of runoff depends upon that of soil loss and the latter is assumed to be linear to the value of EI that equals the product of total storm energy E times the maximum 30-min intensity I30 for a given rainstorm. Usually, the maximum accumulative amount of rain for a rainstorm might bring on the maximum amount of runoff, but it does not equal the maximum erosion and not always lead the maximum concentration. Thus, the average concentration weighted by amount of runoff is somewhat unreasonable. An improvement for the calculation method of non-point source pollution load put forward by professor Li Huaien is proposed. In replacement of the weight of runoff, EI value of a single rainstorm is introduced as a new weight. An example of Fujing River watershed shows that its application is effective.

  6. Risk-based prioritization of ground water threatening point sources at catchment and regional scales

    Overheu, Niels Døssing; Tuxen, Nina; Flyvbjerg, John;

    2014-01-01

    framework has been developed to enable a systematic and transparent risk assessment and prioritization of contaminant point sources, considering the local, catchment, or regional scales (Danish EPA, 2011, 2012). The framework has been tested in several catchments in Denmark with different challenges and...... needs, and two of these are presented. Based on the lessons learned, the Danish EPA has prepared a handbook to guide the user through the steps in a risk-based prioritization (Danish EPA, 2012). It provides guidance on prioritization both in an administratively defined area such as a Danish Region, and...... results are presented using the case studies as examples. The methodology was developed by a broad industry group including the Danish EPA, the Danish Regions, the Danish Nature Agency, the Technical University of Denmark, and consultants — and the framework has been widely accepted by the professional...

  7. Discriminating between unresolved point sources and "negative" SZ clusters in CMB maps

    Rubiño-Martín, J A

    2003-01-01

    Clusters of galaxies produce negative features at wavelengths $\\lambda > 1.25$ mm in CMB maps, by means of the thermal SZ effect, while point radio sources produce positive peaks. This fact implies that a distribution of unresolved SZ clusters could be detected using the negative asymmetry introduced in the odd-moments of the brightness map (skewness and higher), or in the probability distribution function (PDF) for the fluctuations. This property provides a consistency check to the recent detections from CBI and BIMA experiments of an excess of power at small angular scales, in order to confirm that they are produced by a distribution of unresolved SZ clusters. However it will require at least 1.5 - 2 times more observing time than detection of corresponding power signal. This approach could also be used with the data of the planned SZ experiments (e.g. AMI, AMIBA, APEX, 8 m South Pole telescope).

  8. Field-scale operation of methane biofiltration systems to mitigate point source methane emissions

    Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH4). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH4 to carbon dioxide (CO2) and water (H2O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH4 emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH4 oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH4 oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH4 oxidation efficiencies under various operating conditions, including different filter bed depths and CH4 flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation. - Highlights: → One-dimensional version of the model was used as a guiding tool for designing and operating the MBF. → Mathematical model predicted CH4 oxidation behaviors of the field MBF with high accuracy i.e. (> 80 %). → Performance of MBF is dependent on ambient temperature and precipitation. - The developed numerical model simulations and field observations for estimating CH4 oxidation efficiencies under various operating conditions indicate that the long-term performance of MBFs is strongly dependent on

  9. Monitoring and source tracking of tetracycline resistance genes in lagoons and groundwater adjacent to swine production facilities over a 3-year period

    Koike, S.; Krapac, I.G.; Oliver, H.D.; Yannarell, A.C.; Chee-Sanford, J. C.; Aminov, R.I.; Mackie, R.I.

    2007-01-01

    To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tcr) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tcr genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tcr genes was quantified by real-time quantitative PCR. To confirm the Tcr gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tcr genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tcr genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool. Copyright ?? 2007, American Society for Microbiology. All Rights Reserved.

  10. Astronomers Detect Powerful Bursting Radio Source Discovery Points to New Class of Astronomical Objects

    2005-03-01

    Astronomers at Sweet Briar College and the Naval Research Laboratory (NRL) have detected a powerful new bursting radio source whose unique properties suggest the discovery of a new class of astronomical objects. The researchers have monitored the center of the Milky Way Galaxy for several years and reveal their findings in the March 3, 2005 edition of the journal, “Nature”. This radio image of the central region of the Milky Way Galaxy holds a new radio source, GCRT J1745-3009. The arrow points to an expanding ring of debris expelled by a supernova. CREDIT: N.E. Kassim et al., Naval Research Laboratory, NRAO/AUI/NSF Principal investigator, Dr. Scott Hyman, professor of physics at Sweet Briar College, said the discovery came after analyzing some additional observations from 2002 provided by researchers at Northwestern University. “"We hit the jackpot!” Hyman said referring to the observations. “An image of the Galactic center, made by collecting radio waves of about 1-meter in wavelength, revealed multiple bursts from the source during a seven-hour period from Sept. 30 to Oct. 1, 2002 — five bursts in fact, and repeating at remarkably constant intervals.” Hyman, four Sweet Briar students, and his NRL collaborators, Drs. Namir Kassim and Joseph Lazio, happened upon transient emission from two radio sources while studying the Galactic center in 1998. This prompted the team to propose an ongoing monitoring program using the National Science Foundation’s Very Large Array (VLA) radio telescope in New Mexico. The National Radio Astronomy Observatory, which operates the VLA, approved the program. The data collected, laid the groundwork for the detection of the new radio source. “Amazingly, even though the sky is known to be full of transient objects emitting at X- and gamma-ray wavelengths,” NRL astronomer Dr. Joseph Lazio pointed out, “very little has been done to look for radio bursts, which are often easier for astronomical objects to produce

  11. Aircraft-Based Measurements of Point Source Methane Emissions in the Barnett Shale Basin.

    Lavoie, Tegan N; Shepson, Paul B; Cambaliza, Maria O L; Stirm, Brian H; Karion, Anna; Sweeney, Colm; Yacovitch, Tara I; Herndon, Scott C; Lan, Xin; Lyon, David

    2015-07-01

    We report measurements of methane (CH4) emission rates observed at eight different high-emitting point sources in the Barnett Shale, Texas, using aircraft-based methods performed as part of the Barnett Coordinated Campaign. We quantified CH4 emission rates from four gas processing plants, one compressor station, and three landfills during five flights conducted in October 2013. Results are compared to other aircraft- and surface-based measurements of the same facilities, and to estimates based on a national study of gathering and processing facilities emissions and 2013 annual average emissions reported to the U.S. EPA Greenhouse Gas Reporting Program (GHGRP). For the eight sources, CH4 emission measurements from the aircraft-based mass balance approach were a factor of 3.2-5.8 greater than the GHGRP-based estimates. Summed emissions totaled 7022 ± 2000 kg hr(-1), roughly 9% of the entire basin-wide CH4 emissions estimated from regional mass balance flights during the campaign. Emission measurements from five natural gas management facilities were 1.2-4.6 times larger than emissions based on the national study. Results from this study were used to represent "super-emitters" in a newly formulated Barnett Shale Inventory, demonstrating the importance of targeted sampling of "super-emitters" that may be missed by random sampling of a subset of the total. PMID:26148549

  12. Strains of scattering of near-field of a point source

    M D Sharma

    2004-06-01

    Three dimensional scattering of near-field is studied for dilatation and rotation in the time domain. The perturbation method is applied to solve the equation of motion for the first order scattering from a weak inhomogeneity in an otherwise homogeneous medium. The inhomogeneity is assumed close enough to the point source so that the near-field intermediate wave is dominating over the far-field spherical and pulses. The integral expressions are derived to relate dilatation and rotation of scattering to the radial fluctuations of velocities and density in the inhomogeneity. These integrals are solved to calculate the strains of scattering from (a part of) an inhomogeneous spherical shell of arbitrary curvature. Variable curvature may allow the shape of inhomogeneity volume element to change uniformly from spherical to rectangular. Rotation of scattering from a spherical shell is independent of wave velocity inhomogeneity. Dilatation of scattering does not involve wave velocity inhomogeneity but its gradient. The back scattering results are obtained as a special case. Strains are computed numerically, for hypothetical models to study the effects of various parameters viz., velocity inhomogeneity, distance of source from inhomogeneity and from receiver, and thickness of inhomogeneity. The curvature of the spherical shell is varied to study the effects of the shape of inhomogeneous volume element on scattering.

  13. The energy sources and nuclear energy - The point of view of the Belgian Catholic Church

    The problems related to the environment are reported regularly to the public by means of the newspapers, on radio and television. The story is the product of a journalistic process and in general does not bear much resemblance to the original event. The rate and type of reportage depend not only on the body of data available to the journalist but on the information sources the journalist chosen to use. The same story is reported in a positive or negative way. Finally people are overwhelmed by contradictory information and became uncertain or frightened. In order to provide the general public with objective information about nuclear energy in particular and to made a statement about the position of the Belgian Catholic Church concerning this matter, the results of the study were published in Dutch under the form of a book with the title 'The Energy Sources and Nuclear Energy - Comparative analysis and ethical thoughts written the same author. Thia paper is a short survey of the results of the study and to present the point of view of the Belgian Catholic Church in the energy debate

  14. An ultrabright and monochromatic electron point source made of a LaB6 nanowire.

    Zhang, Han; Tang, Jie; Yuan, Jinshi; Yamauchi, Yasushi; Suzuki, Taku T; Shinya, Norio; Nakajima, Kiyomi; Qin, Lu-Chang

    2016-03-01

    Electron sources in the form of one-dimensional nanotubes and nanowires are an essential tool for investigations in a variety of fields, such as X-ray computed tomography, flexible displays, chemical sensors and electron optics applications. However, field emission instability and the need to work under high-vacuum or high-temperature conditions have imposed stringent requirements that are currently limiting the range of application of electron sources. Here we report the fabrication of a LaB6 nanowire with only a few La atoms bonded on the tip that emits collimated electrons from a single point with high monochromaticity. The nanostructured tip has a low work function of 2.07 eV (lower than that of Cs) while remaining chemically inert, two properties usually regarded as mutually exclusive. Installed in a scanning electron microscope (SEM) field emission gun, our tip shows a current density gain that is about 1,000 times greater than that achievable with W(310) tips, and no emission decay for tens of hours of operation. Using this new SEM, we acquired very low-noise, high-resolution images together with rapid chemical compositional mapping using a tip operated at room temperature and at 10-times higher residual gas pressure than that required for W tips. PMID:26619151

  15. Analysis of ultrasonically rotating droplet using moving particle semi-implicit and distributed point source methods

    Wada, Yuji; Yuge, Kohei; Tanaka, Hiroki; Nakamura, Kentaro

    2016-07-01

    Numerical analysis of the rotation of an ultrasonically levitated droplet with a free surface boundary is discussed. The ultrasonically levitated droplet is often reported to rotate owing to the surface tangential component of acoustic radiation force. To observe the torque from an acoustic wave and clarify the mechanism underlying the phenomena, it is effective to take advantage of numerical simulation using the distributed point source method (DPSM) and moving particle semi-implicit (MPS) method, both of which do not require a calculation grid or mesh. In this paper, the numerical treatment of the viscoacoustic torque, which emerges from the viscous boundary layer and governs the acoustical droplet rotation, is discussed. The Reynolds stress traction force is calculated from the DPSM result using the idea of effective normal particle velocity through the boundary layer and input to the MPS surface particles. A droplet levitated in an acoustic chamber is simulated using the proposed calculation method. The droplet is vertically supported by a plane standing wave from an ultrasonic driver and subjected to a rotating sound field excited by two acoustic sources on the side wall with different phases. The rotation of the droplet is successfully reproduced numerically and its acceleration is discussed and compared with those in the literature.

  16. NOx emissions from large point sources: variability in ozone production, resulting health damages and economic costs

    We present a proof-of-concept analysis of the measurement of the health damage of ozone (O3) produced from nitrogen oxides (NOx=NO+NO2) emitted by individual large point sources in the eastern United States. We use a regional atmospheric model of the eastern United States, the Comprehensive Air quality Model with Extensions (CAMx), to quantify the variable impact that a fixed quantity of NOx emitted from individual sources can have on the downwind concentration of surface O3, depending on temperature and local biogenic hydrocarbon emissions. We also examine the dependence of resulting O3-related health damages on the size of the exposed population. The investigation is relevant to the increasingly widely used 'cap and trade' approach to NOx regulation, which presumes that shifts of emission over time and space, holding the total fixed over the course of the summer O3 season, will have minimal effect on the environmental outcome. By contrast, we show that a shift of a unit of NOx emissions from one place or time to another could result in large changes in resulting health effects due to O3 formation and exposure. We indicate how the type of modeling carried out here might be used to attach externality-correcting prices to emissions. Charging emitters fees that are commensurate with the damage caused by their NOx emissions would create an incentive for emitters to reduce emissions at times and in locations where they cause the largest damage. (author)

  17. Luminosity distribution in the central regions of Messier 87: Isothermal core, point source, or black hole

    A combination of photographic and photoelectric photometry with the McDonald 2 m reflector is used to derive a precise mean luminosity profile μ/sub B/(r*) of M87 (jet excluded) at approx.0''.6 resolution out to r*=70''. Within 8'' from the center the luminosity is less than predicted by extrapolation of the r/sup 1/4/ law defined by the main body of the galaxy (8''0=30.5) the structural length of the underlying isothermal is α=2''.78=170 pc, the mass of the ''black hole'' M0 =1.7.109M/sub sun/ and the luminosity of the point source (B0 =16.95, M0=-13.55) equals 4.2% of the integrated luminosity B (6'') =13.52 of the galaxy within r*=6''. These results agree closely with and confirm the work of the Hale team. Comparison of the McDonald and Hale data suggests that the central source may have been slightly brighter (approx.0.5 mag) in 1964 than in 1975--1977

  18. An Efficient Single Impedance Network Three Level Z-Source Neutral Point Clamped Inverter

    C.L.Kuppuswamy

    2012-07-01

    Full Text Available A multilevel inverter can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. Although the multilevel inverter structure was initially introduced as a means of reducing the output waveform harmonic content, it was found that the dc bus voltage could be increased beyond the voltage rating of an individual power device by the use of a voltage clamping network consisting of diodes. By using voltage clamping techniques, the system KV rating can be extended beyond limits of an individual device. This paper presents Impedance (Z Source Neutral Point Clamped (NPC three level inverter with reduced number of impedance source networks and clamping diodes for non-linear loads. Earlier for a three level NPC inverter two separate impedance networks were used. But to reduce the circuit complexity without compromising with output requirement; only one impedance network is used and to substantiate this, the simulation of proposed circuit is carried out using MATLAB/Simulink for a 48 V input supply. A prototype is developed for an input voltage of 26V and the experimental results for the same are presented in this paper.

  19. Loss coefficient of nitrogenous non-point source pollution under various precipitation conditions

    2008-01-01

    In this study,calibrations of non-point source (NPS) pollution models are performed based on Black River basin historical real-time runoff data,sedimentation record data,and NPS sources survey information.The concept of NPS loss coefficient for the watershed or the loss coefficients (LC) for simplicity is brought up by examining NPS build-up and migration processes along riverbanks in natural river systems.The historical data is used for determining the nitrogenous NPS loss coefficient for five land use types including farmland,urban land,grassland,shrub land,and forest under different precipitation conditions.The comparison of outputs from Soil and Water Assessment Tool (SWAT) model and coefficient export method showed that both methods could obtain reasonable LC.The high Pearson correlation coefficient (0.94722) between those two sets of calculation results justified the consistency of those two models.Another result in the study is that different combinations of precipitation condition and land use types could significantly affect the calculated loss coefficient.As for the adsorptive nitrogen,the order of impact on LC for different land use types can be sorted as:farm land > urban land > grassland > shrub land > forest while the order was farmland > grass land > shrub land > forest > urban land for soluble nitrogen.

  20. Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources

    R. Felber

    2015-02-01

    Full Text Available Methane (CH4 from ruminants contributes one third to global agricultural greenhouse gas emissions. Eddy covariance (EC technique has been extensively used at various flux sites to investigate carbon dioxide exchange of ecosystems. Since the development of fast CH4 analysers the instrumentation at many flux sites have been amended for these gases. However the application of EC over pastures is challenging due to the spatial and temporal uneven distribution of CH4 point sources induced by the grazing animals. We applied EC measurements during one grazing season over a pasture with 20 dairy cows (mean milk yield: 22.7 kg d−1 managed in a rotational grazing system. Individual cow positions were recorded by GPS trackers to attribute fluxes to animal emissions using a footprint model. Methane fluxes with cows in the footprint were up to two orders of magnitude higher than ecosystem fluxes without cows. Mean cow emissions of 423 ± 24 g CH4 head−1 d−1 (best guess of this study correspond well to animal respiration chamber measurements reported in the literature. However a systematic effect of the distance between source and EC tower on cow emissions was found which is attributed to the analytical footprint model used. We show that the EC method allows to determine CH4 emissions of grazing cows if the data evaluation is adjusted for this purpose and if some cow distribution information is available.

  1. An ultrabright and monochromatic electron point source made of a LaB6 nanowire

    Zhang, Han; Tang, Jie; Yuan, Jinshi; Yamauchi, Yasushi; Suzuki, Taku T.; Shinya, Norio; Nakajima, Kiyomi; Qin, Lu-Chang

    2016-03-01

    Electron sources in the form of one-dimensional nanotubes and nanowires are an essential tool for investigations in a variety of fields, such as X-ray computed tomography, flexible displays, chemical sensors and electron optics applications. However, field emission instability and the need to work under high-vacuum or high-temperature conditions have imposed stringent requirements that are currently limiting the range of application of electron sources. Here we report the fabrication of a LaB6 nanowire with only a few La atoms bonded on the tip that emits collimated electrons from a single point with high monochromaticity. The nanostructured tip has a low work function of 2.07 eV (lower than that of Cs) while remaining chemically inert, two properties usually regarded as mutually exclusive. Installed in a scanning electron microscope (SEM) field emission gun, our tip shows a current density gain that is about 1,000 times greater than that achievable with W(310) tips, and no emission decay for tens of hours of operation. Using this new SEM, we acquired very low-noise, high-resolution images together with rapid chemical compositional mapping using a tip operated at room temperature and at 10-times higher residual gas pressure than that required for W tips.

  2. Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources

    Felber, R.; Münger, A.; Neftel, A.; Ammann, C.

    2015-06-01

    Methane (CH4) from ruminants contributes one-third of global agricultural greenhouse gas emissions. Eddy covariance (EC) technique has been extensively used at various flux sites to investigate carbon dioxide exchange of ecosystems. Since the development of fast CH4 analyzers, the instrumentation at many flux sites has been amended for these gases. However, the application of EC over pastures is challenging due to the spatially and temporally uneven distribution of CH4 point sources induced by the grazing animals. We applied EC measurements during one grazing season over a pasture with 20 dairy cows (mean milk yield: 22.7 kg d-1) managed in a rotational grazing system. Individual cow positions were recorded by GPS trackers to attribute fluxes to animal emissions using a footprint model. Methane fluxes with cows in the footprint were up to 2 orders of magnitude higher than ecosystem fluxes without cows. Mean cow emissions of 423 ± 24 g CH4 head-1 d-1 (best estimate from this study) correspond well to animal respiration chamber measurements reported in the literature. However, a systematic effect of the distance between source and EC tower on cow emissions was found, which is attributed to the analytical footprint model used. We show that the EC method allows one to determine CH4 emissions of cows on a pasture if the data evaluation is adjusted for this purpose and if some cow distribution information is available.

  3. The recovery of a time-dependent point source in a linear transport equation: application to surface water pollution

    The aim of this paper is to localize the position of a point source and recover the history of its time-dependent intensity function that is both unknown and constitutes the right-hand side of a 1D linear transport equation. Assuming that the source intensity function vanishes before reaching the final control time, we prove that recording the state with respect to the time at two observation points framing the source region leads to the identification of the source position and the recovery of its intensity function in a unique manner. Note that at least one of the two observation points should be strategic. We establish an identification method that determines quasi-explicitly the source position and transforms the task of recovering its intensity function into solving directly a well-conditioned linear system. Some numerical experiments done on a variant of the water pollution BOD model are presented

  4. Anthropogenic Methane Emissions in California's San Joaquin Valley: Characterizing Large Point Source Emitters

    Hopkins, F. M.; Duren, R. M.; Miller, C. E.; Aubrey, A. D.; Falk, M.; Holland, L.; Hook, S. J.; Hulley, G. C.; Johnson, W. R.; Kuai, L.; Kuwayama, T.; Lin, J. C.; Thorpe, A. K.; Worden, J. R.; Lauvaux, T.; Jeong, S.; Fischer, M. L.

    2015-12-01

    Methane is an important atmospheric pollutant that contributes to global warming and tropospheric ozone production. Methane mitigation could reduce near term climate change and improve air quality, but is hindered by a lack of knowledge of anthropogenic methane sources. Recent work has shown that methane emissions are not evenly distributed in space, or across emission sources, suggesting that a large fraction of anthropogenic methane comes from a few "super-emitters." We studied the distribution of super-emitters in California's southern San Joaquin Valley, where elevated levels of atmospheric CH4 have also been observed from space. Here, we define super-emitters as methane plumes that could be reliably detected (i.e., plume observed more than once in the same location) under varying wind conditions by airborne thermal infrared remote sensing. The detection limit for this technique was determined to be 4.5 kg CH4 h-1 by a controlled release experiment, corresponding to column methane enhancement at the point of emissions greater than 20% above local background levels. We surveyed a major oil production field, and an area with a high concentration of large dairies using a variety of airborne and ground-based measurements. Repeated airborne surveys (n=4) with the Hyperspectral Thermal Emission Spectrometer revealed 28 persistent methane plumes emanating from oil field infrastructure, including tanks, wells, and processing facilities. The likelihood that a given source type was a super-emitter varied from roughly 1/3 for processing facilities to 1/3000 for oil wells. 11 persistent plumes were detected in the dairy area, and all were associated with wet manure management. The majority (11/14) of manure lagoons in the study area were super-emitters. Comparing to a California methane emissions inventory for the surveyed areas, we estimate that super-emitters comprise a minimum of 9% of inventoried dairy emissions, and 13% of inventoried oil emissions in this region.

  5. A land use regression model incorporating data on industrial point source pollution

    Li Chen; Yuming Wang; Peiwu Li; Yaqin Ji; Shaofei Kong; Zhiyong Li; Zhipeng Bai

    2012-01-01

    Advancing the understanding of the spatial aspects of air pollution in the city regional environment is an area where improved methods can be of great benefit to exposure assessment and polcy support.We created land use regression (LUR) models for SO2,NO2 and PM10for Tianjin,China.Traffic volumes,road networks,land use data,population density,meteorological conditions,physical conditions and satellite-derived greenness,brightness and wetness were used for predicting SO2,NO2 and PM10 concentrations.We incorporated data on industrial point sources to improve LUR model performance.In order to consider the impact of different sources,we calculated the PSIndex,LSIndex and area of different land use types (agricultural land,industrial land,commercial land,residential land,green space and water area) within different buffer radii (1 to 20 km).This method makes up for the lack of consideration of source impact based on the LUR model.Remote sensing-derived variables were significantly correlated with gaseous pollutant concentrations such as SO2 and NO2.R2 values of the multiple linear regression equations for SO2,NO2 and PM10 were 0.78,0.89 and 0.84,respectively,and the RMSE values were 0.32,0.18 and 0.21,respectively.Model predictions at validation monitoring sites went well with predictions generally within 15% of measured values.Compared to the relationship between dependent variables and simple variables (such as traffic variables or meteorological condition variables),the relationship between dependent variables and integrated variables was more consistent with a linear relationship.Such integration has a discernable influence on both the overall model prediction and health effects assessment on the spatial distribution of air pollution in the city region.

  6. Using sorbent waste materials to enhance treatment of micro-point source effluents by constructed wetlands

    Green, Verity; Surridge, Ben; Quinton, John; Matthews, Mike

    2014-05-01

    Sorbent materials are widely used in environmental settings as a means of enhancing pollution remediation. A key area of environmental concern is that of water pollution, including the need to treat micro-point sources of wastewater pollution, such as from caravan sites or visitor centres. Constructed wetlands (CWs) represent one means for effective treatment of wastewater from small wastewater producers, in part because they are believed to be economically viable and environmentally sustainable. Constructed wetlands have the potential to remove a range of pollutants found in wastewater, including nitrogen (N), phosphorus (P), biochemical oxygen demand (BOD) and carbon (C), whilst also reducing the total suspended solids (TSS) concentration in effluents. However, there remain particular challenges for P and N removal from wastewater in CWs, as well as the sometimes limited BOD removal within these treatment systems, particularly for micro-point sources of wastewater. It has been hypothesised that the amendment of CWs with sorbent materials can enhance their potential to treat wastewater, particularly through enhancing the removal of N and P. This paper focuses on data from batch and mesocosm studies that were conducted to identify and assess sorbent materials suitable for use within CWs. The aim in using sorbent material was to enhance the combined removal of phosphate (PO4-P) and ammonium (NH4-N). The key selection criteria for the sorbent materials were that they possess effective PO4-P, NH4-N or combined pollutant removal, come from low cost and sustainable sources, have potential for reuse, for example as a fertiliser or soil conditioner, and show limited potential for re-release of adsorbed nutrients. The sorbent materials selected for testing were alum sludge from water treatment works, ochre derived from minewater treatment, biochar derived from various feedstocks, plasterboard and zeolite. The performance of the individual sorbents was assessed through

  7. Point sources of emerging contaminants along the Colorado River Basin: source water for the arid Southwestern United States.

    Jones-Lepp, Tammy L; Sanchez, Charles; Alvarez, David A; Wilson, Doyle C; Taniguchi-Fu, Randi-Laurant

    2012-07-15

    Emerging contaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the United States. The objective of this study was to evaluate point sources of ECs along the Colorado River, from the headwaters in Colorado to the Gulf of California. At selected locations in the Colorado River Basin (sites in Colorado, Utah, Nevada, Arizona, and California), waste stream tributaries and receiving surface waters were sampled using either grab sampling or polar organic chemical integrative samplers (POCIS). The grab samples were extracted using solid-phase cartridge extraction (SPE), and the POCIS sorbents were transferred into empty SPEs and eluted with methanol. All extracts were prepared for, and analyzed by, liquid chromatography-electrospray-ion trap mass spectrometry (LC-ESI-ITMS). Log D(OW) values were calculated for all ECs in the study and compared to the empirical data collected. POCIS extracts were screened for the presence of estrogenic chemicals using the yeast estrogen screen (YES) assay. Extracts from the 2008 POCIS deployment in the Las Vegas Wash showed the second highest estrogenicity response. In the grab samples, azithromycin (an antibiotic) was detected in all but one urban waste stream, with concentrations ranging from 30ng/L to 2800ng/L. Concentration levels of azithromycin, methamphetamine and pseudoephedrine showed temporal variation from the Tucson WWTP. Those ECs that were detected in the main surface water channels (those that are diverted for urban use and irrigation along the Colorado River) were in the region of the limit-of-detection (e.g., 10ng/L), but most were below detection limits. PMID:22684090

  8. Reducing future non-point source sediment and phosphorus loading under intensifying agricultural production in the Ethiopian highlands

    Mogus, Mamaru; Schmitter, Petra; Tilahun, Seifu; Steenhuise, Tammo

    2016-04-01

    Intensification of agriculture will bring along non-point source pollution in the Ethiopian highlands resulting in eutrophication of lakes. The first signs of eutrophication have been observed already in Lake Tana. The lake it supports the lives of millions in the surrounding through fishing, tourism, transportation and hydropower.Presently, information on non-point source pollution is lacking in the Ethiopian highlands. There are few studies carried out in the highlands on the extent and the source areas of pollution, and models are not available for predicting sediment and phosphorus loading other than those developed for temperate climates. The objective of this chapter is to review existing non-point source studies, report on our findings of sediment and phosphorus sources that are related the non-point source pollution of Lake Tana and to present a non-point source model for the Ethiopian highland based on the Parameter Efficient Semi-distributed Watershed Hydrology Model (PED-WHM).In our research we have found that the saturation excess runoff from valley bottoms and from degraded lands are prevalent in the Ethiopia highlands. The periodically runoff source areas are also the sources for the non-point source pollution and by concentrating best management practices in these source areas we expect that we can reduce pollution without affecting the profitability of the existing farms. The water balance component of the non-point source model has been performing well in predicting both the discharge and the location of the runoff source areas. Sediment and phosphorus prediction models have been developed and are currently being tested for the 7km2Awramba watershed and the 1350 km2Gumara basin. Initial results indicate that 11.2 ton/ha/year sediment load and an accumulation rate of 17.3 mg/kg/year of dissolved phosphorus from Gumara watershed joining the lake. By developing best management practices at this time before non-point source pollution is rampant and

  9. Identification and cross-checking of large point source SO2 emissions in Europe using OMI retrievals

    Gon, H.D. van der; Visschedijk, A.; McLinden, C.; Fioletov, V.; Wal, L. van der

    2013-01-01

    European SO2 emissions from large points sources (LPS) were cross-checked with satellite S2 measurements from the Ozone Monitoring Instrument (OMI) on NASA's EOS-Aura satellite, averaged over a period of several years. Coordinates of the top-100 individual LPS in Europe were taken from the TNO point

  10. The XMM-Newton survey of the Small Magellanic Cloud: The X-ray point-source catalogue

    Sturm, R; Pietsch, W; Ballet, J; Hatzidimitriou, D; Buckley, D A H; Coe, M; Ehle, M; Filipovic, M D; La Palombara, N; Tiengo, A

    2013-01-01

    Local-Group galaxies provide access to samples of X-ray source populations of whole galaxies. The XMM-Newton survey of the Small Magellanic Cloud (SMC) completely covers the bar and eastern wing with a 5.6 deg^2 area in the (0.2-12.0) keV band. To characterise the X-ray sources in the SMC field, we created a catalogue of point sources and sources with moderate extent. Sources with high extent (>40") have been presented in a companion paper. We searched for point sources in the EPIC images using sliding-box and maximum-likelihood techniques and classified the sources using hardness ratios, X-ray variability, and their multi-wavelength properties. The catalogue comprises 3053 unique X-ray sources with a median position uncertainty of 1.3" down to a flux limit for point sources of ~10^-14 erg cm^-2 s^-1 in the (0.2-4.5) keV band, corresponding to 5x10^33 erg s^-1 for sources in the SMC. We discuss statistical properties, like the spatial distribution, X-ray colour diagrams, luminosity functions, and time variabi...

  11. Field-scale operation of methane biofiltration systems to mitigate point source methane emissions

    Hettiarachchi, Vijayamala C. [Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Hettiaratchi, Patrick J., E-mail: jhettiar@ucalgary.ca [Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Mehrotra, Anil K. [Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Kumar, Sunil, E-mail: sunil_neeri@yahoo.co.in [Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada)

    2011-06-15

    Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH{sub 4}). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH{sub 4} to carbon dioxide (CO{sub 2}) and water (H{sub 2}O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH{sub 4} emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH{sub 4} oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH{sub 4} oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH{sub 4} oxidation efficiencies under various operating conditions, including different filter bed depths and CH{sub 4} flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation. - Highlights: > One-dimensional version of the model was used as a guiding tool for designing and operating the MBF. > Mathematical model predicted CH{sub 4} oxidation behaviors of the field MBF with high accuracy i.e. (> 80 %). > Performance of MBF is dependent on ambient temperature and precipitation. - The developed numerical model simulations and field observations for estimating CH{sub 4} oxidation efficiencies under various operating conditions indicate that

  12. THE CHANDRA COSMOS SURVEY. III. OPTICAL AND INFRARED IDENTIFICATION OF X-RAY POINT SOURCES

    The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that has imaged the central 0.9 deg2 of the COSMOS field down to limiting depths of 1.9 × 10–16 erg cm–2 s–1 in the soft (0.5-2 keV) band, 7.3 × 10–16 erg cm–2 s–1 in the hard (2-10 keV) band, and 5.7 × 10–16 erg cm–2 s–1 in the full (0.5-10 keV) band. In this paper we report the i, K, and 3.6 μm identifications of the 1761 X-ray point sources. We use the likelihood ratio technique to derive the association of optical/infrared counterparts for 97% of the X-ray sources. For most of the remaining 3%, the presence of multiple counterparts or the faintness of the possible counterpart prevented a unique association. For only 10 X-ray sources we were not able to associate a counterpart, mostly due to the presence of a very bright field source close by. Only two sources are truly empty fields. The full catalog, including spectroscopic and photometric redshifts and classification described here in detail, is available online. Making use of the large number of X-ray sources, we update the 'classic locus' of active galactic nuclei (AGNs) defined 20 years ago in soft X-ray surveys and define a new locus containing 90% of the AGNs in the survey with full-band luminosity >1042 erg s–1. We present the linear fit between the total i-band magnitude and the X-ray flux in the soft and hard bands, drawn over two orders of magnitude in X-ray flux, obtained using the combined C-COSMOS and XMM-COSMOS samples. We focus on the X-ray to optical flux ratio (X/O) and we test its known correlation with redshift and luminosity, and a recently introduced anti-correlation with the concentration index (C). We find a strong anti-correlation (though the dispersion is of the order of 0.5 dex) between X/O computed in the hard band and C and that 90% of the obscured AGNs in the sample with morphological information live in galaxies with regular morphology (bulgy and disky/spiral), suggesting that secular

  13. User's Guide for the Agricultural Non-Point Source (AGNPS) Pollution Model Data Generator

    Finn, Michael P.; Scheidt, Douglas J.; Jaromack, Gregory M.

    2003-01-01

    BACKGROUND Throughout this user guide, we refer to datasets that we used in conjunction with developing of this software for supporting cartographic research and producing the datasets to conduct research. However, this software can be used with these datasets or with more 'generic' versions of data of the appropriate type. For example, throughout the guide, we refer to national land cover data (NLCD) and digital elevation model (DEM) data from the U.S. Geological Survey (USGS) at a 30-m resolution, but any digital terrain model or land cover data at any appropriate resolution will produce results. Another key point to keep in mind is to use a consistent data resolution for all the datasets per model run. The U.S. Department of Agriculture (USDA) developed the Agricultural Nonpoint Source (AGNPS) pollution model of watershed hydrology in response to the complex problem of managing nonpoint sources of pollution. AGNPS simulates the behavior of runoff, sediment, and nutrient transport from watersheds that have agriculture as their prime use. The model operates on a cell basis and is a distributed parameter, event-based model. The model requires 22 input parameters. Output parameters are grouped primarily by hydrology, sediment, and chemical output (Young and others, 1995.) Elevation, land cover, and soil are the base data from which to extract the 22 input parameters required by the AGNPS. For automatic parameter extraction, follow the general process described in this guide of extraction from the geospatial data through the AGNPS Data Generator to generate input parameters required by the pollution model (Finn and others, 2002.)

  14. Estimation of the skull insertion loss using an optoacoustic point source

    Estrada, Héctor; Rebling, Johannes; Turner, Jake; Kneipp, Moritz; Shoham, Shy; Razansky, Daniel

    2016-03-01

    The acoustically-mismatched skull bone poses significant challenges for the application of ultrasonic and optical techniques in neuroimaging, still typically requiring invasive approaches using craniotomy or skull thinning. Optoacoustic imaging partially circumvents the acoustic distortions due to the skull because the induced wave is transmitted only once as opposed to the round trip in pulse-echo ultrasonography. To this end, the mouse brain has been successfully imaged transcranially by optoacoustic scanning microscopy. Yet, the skull may adversely affect the lateral and axial resolution of transcranial brain images. In order to accurately characterize the complex behavior of the optoacoustic signal as it traverses through the skull, one needs to consider the ultrawideband nature of the optoacoustic signals. Here the insertion loss of murine skull has been measured by means of a hybrid optoacoustic-ultrasound scanning microscope having a spherically focused PVDF transducer and pulsed laser excitation at 532 nm of a 20 μm diameter absorbing microsphere acting as an optoacoustic point source. Accurate modeling of the acoustic transmission through the skull is further performed using a Fourier-domain expansion of a solid-plate model, based on the simultaneously acquired pulse-echo ultrasound image providing precise information about the skull's position and its orientation relative to the optoacoustic source. Good qualitative agreement has been found between the a solid-plate model and experimental measurements. The presented strategy might pave the way for modeling skull effects and deriving efficient correction schemes to account for acoustic distortions introduced by an adult murine skull, thus improving the spatial resolution, effective penetration depth and overall image quality of transcranial optoacoustic brain microscopy.

  15. Sulfate formation in point source plumes: A review of recent field studies

    Wilson, William E.

    Data in twelve power plant and smelter plumes reported by eight different organizations have been reviewed in an attempt to establish the existence of recognizable patterns concerning the extent and rates of sulfate formation. The data reviewed here were collected in Australia, Canada and the U.S., during warm as well as cold seasons, and during day and night. The primary variables examined and compared are Sp/ ST, the paniculate fraction of excess sulfur sampled in the plume, and the corresponding plume age. The variation of the extent of sulfate formation ( Sp/ ST) is also examined in terms of plume exposure to solar radiation dose during transport. In spite of wide geographical, seasonal, background and source variations, a distinct difference is observed in day and night sulfate formation. During the daytime, there exists a substantial variability in sulfate formation rates (typically 0-5% h -1) and extent (typically up to 25%) for any given physical plume age. This variability is significantly less for plumes with similar exposure to sunlight dose, showing that environmental factors linked to solar radiation strongly influence the rate and extent of sulfate formation in point-source plumes. The diurnal and seasonal co-variance of all insolation-related factors makes it difficult to distinguish the roles of specific environmental factors or conversion mechanisms. Night-time data show that Sp/ ST seldom exceeds 3% even after 5-10 h of plume transport. A surprising result is observed related to geographical variability of the conversion rate. Except in the case of the data of the Navajo coal-fired power plant plume collected as part of the VISTTA study, all other data fall within an identifiable envelope ranging over 15-30% sulfate formation ( Sp/ ST) corresponding to solar dose equivalent to one July day in St. Louis. The Navajo data yield about an order of magnitude lower conversion. Evidently, factors other than those related to insolation are also important.

  16. Model testing and intercomparison of model predictions for a hypothetical point source discharge

    Full text: The NORM working group within the International Atomic Energy Agency's EMRAS program was established to examine the development and testing of scenarios and computer models for simulating environmental transport of naturally occurring radionuclides. One of the early problems encountered by the NORM working group was the difficulty of obtaining comprehensive, well-validated data sites for real situations. However, it was pointed out that this modelling work can be facilitated by the use of hypothetical discharge scenarios. This paper describes the development and testing of a hypothetical point source discharge scenario. This type of scenario is usually associated with chimney stack discharges from power stations, processing plants, factories, etc. The principal mechanism by which material is dispersed into the environment following discharge from a chimney stack is atmospheric dispersion. However, once any contaminant settles on the ground surface, other mechanisms such as surface water transport, migration of radionuclides in soil, groundwater transport, resuspension and uptake into the food chain become important. The radionuclides of interest in this exercise are 210Po, 210Pb and 222Rn.This hypothetical scenario has been investigated through the use of three computer models (PC-CREAM, COMPLY and CROM) to model the dispersion of the discharged radionuclides. The scenario description and the input data required (stack height, wind rose, atmospheric stability, deposition velocities, dietary and occupancy habits, etc.) are presented, together with the results of calculations made with the different models. The models used in this work are very different in purpose and complexity. PC-CREAM is a detailed impact assessment model, whereas COMPLY and CROM were developed as screening models. These differences in the models mean that the input data required for each model are different, with the more complex model requiring considerably more input data. One of

  17. Five years of searches for point sources of astrophysical neutrinos with the AMANDA-II neutrino telescope

    Achterberg, A; Adams, J; Ahrens, J; Andeen, K; Atlee, D W; Bahcall, J N; Bai, X; Baret, B; Barwick, S W; Bay, R; Beattie, K; Becka, T; Becker, J K; Becker, K H; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Blaufuss, E; Boersma, D J; Bohm, C; Bolmont, J; Boser, S; Botner, O; Bouchta, A; Braun, J; Burgess, C; Burgess, T; Castermans, T; Chirkin, D; Christy, B; Clem, J; Cowen, D F; D'Agostino, M V; Davour, A; Day, C T; De Clercq, C; Demirors, L; Descamps, F; Desiati, P; De Young, T; Díaz-Veléz, J C; Dreyer, J; Dumm, J P; Duvoort, M R; Edwards, W R; Ehrlich, R; Eisch, J; Ellsworth, R W; Evenson, P A; Fadiran, O; Fazely, A R; Feser, T; Filimonov, K; Fox, B D; Gaisser, T K; Gallagher, J; Ganugapati, R; Geenen, H; Gerhardt, L; Goldschmidt, A; Goodman, J A; Gozzini, R; Grullon, S; Gross, A; Gunasingha, R M; Gurtner, M; Hallgren, A; Halzen, F; Han, K; Hanson, K; Hardtke, D; Hardtke, R; Harenberg, T; Hart, J E; Hauschildt, T; Hays, D; Heise, J; Helbing, K; Hellwig, M; Herquet, P; Hill, G C; Hodges, J; Hoffman, K D; Hommez, B; Hoshina, K; Hubert, D; Hughey, B; Hulth, P O; Hultqvist, K; Hundertmark, S; Hulss, J P; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Jones, A; Joseph, J M; Kampert, K H; Karle, A; Kawai, H; Kelley, J L; Kestel, M; Kitamura, N; Klein, S R; Klepser, S; Kohnen, G; Kolanoski, H; Kowalski, M; Köpke, L; Krasberg, M; Kühn, K; Landsman, H; Leich, H; Leier, D; Leuthold, M; Liubarsky, I; Lundberg, J; Lunemann, J; Madsen, J; Mase, K; Matis, H S; McCauley, T; McParland, C P; Meli, A; Messarius, T; Mészáros, P; Miyamoto, H; Mokhtarani, A; Montaruli, T; Morey, A; Morse, R; Movit, S M; Munich, K; Nahnhauer, R; Nam, J W; Niessen, P; Nygren, D R; Ogelman, H; Olivas, A; Patton, S; Peña-Garay, C; Pérez de los Heros, C; Piegsa, A; Pieloth, D; Pohl, A C; Porrata, R; Pretz, J; Price, P B; Przybylski, G T; Rawlins, K; Razzaque, S; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Robbins, S; Roth, P; Rott, C; Rutledge, D; Ryckbosch, D; Sander, H G; Sarkar, S; Schlenstedt, S; Schmidt, T; Schneider, D; Seckel, D; Seo, S H; Seunarine, S; Silvestri, A; Smith, A J; Solarz, M; Song, C; Sopher, J E; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Steffen, P; Stezelberger, T; Stokstad, R G; Stoufer, M C; Stoyanov, S; Strahler, E A; Straszheim, T; Sulanke, K H; Sullivan, G W; Sumner, T J; Taboada, I; Tarasova, O; Tepe, A; Thollander, L; Tilav, S; Tluczykont, M; Toale, P A; Turcan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; Voigt, B; Wagner, W; Walck, C; Waldmann, H; Walter, M; Wang, Y R; Wendt, C; Wiebusch, C; Wikström, G; Williams, D R; Wischnewski, R; Wissing, H; Woschnagg, K; Xu, X W; Yodh, G; Yoshida, S; De Dios-Zornoza-Gomez, Juan

    2006-01-01

    We report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live-time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selected sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit \\Phi^{0}=(E/TeV)^\\gamma d\\Phi/dE to a point source flux of muon and tau neutrino (detected as muons arising from taus) is \\Phi_{\

  18. Estimation of point source fugitive emission rates from a single sensor time series: A conditionally-sampled Gaussian plume reconstruction

    Foster-Wittig, Tierney A.; Thoma, Eben D.; Albertson, John D.

    2015-08-01

    Emerging mobile fugitive emissions detection and measurement approaches require robust inverse source algorithms to be effective. Two Gaussian plume inverse approaches are described for estimating emission rates from ground-level point sources observed from remote vantage points. The techniques were tested using data from 41 controlled methane release experiments (14 studies) and further investigated using 7 field studies executed downwind of oil and gas well pads in Wyoming. Analyzed measurements were acquired from stationary observation locations 18-106 m downwind of the emission sources. From the fluctuating wind direction, the lateral plume geometry is reconstructed using a derived relationship between the wind direction and crosswind plume position. The crosswind plume spread is determined with both modeled and reconstructed Gaussian plume approaches and estimates of source emission rates are found through inversion. The source emission rates were compared to a simple point source Gaussian emission estimation approach that is part of Draft EPA Method OTM 33A. Compared to the known release rates, the modeled, reconstructed, and point source Gaussian controlled release results yield average percent errors of -5%, -2%, and 6% with standard deviations of 29%, 25%, and 37%, respectively. Compared to each other, the three methods agree within 30% for 78% of all 48 observations (41 CR and 7 Wyoming).

  19. Point source influence on observed extreme pollution levels in a monitoring network

    Ensor, Katherine B.; Ray, Bonnie K.; Charlton, Sarah J.

    2014-08-01

    This paper presents a strategy to quantify the influence major point sources in a region have on extreme pollution values observed at each of the monitors in the network. We focus on the number of hours in a day the levels at a monitor exceed a specified health threshold. The number of daily exceedances are modeled using observation-driven negative binomial time series regression models, allowing for a zero-inflation component to characterize the probability of no exceedances in a particular day. The spatial nature of the problem is addressed through the use of a Gaussian plume model for atmospheric dispersion computed at locations of known emissions, creating covariates that impact exceedances. In order to isolate the influence of emitters at individual monitors, we fit separate regression models to the series of counts from each monitor. We apply a final model clustering step to group monitor series that exhibit similar behavior with respect to mean, variability, and common contributors to support policy decision making. The methodology is applied to eight benzene pollution series measured at air quality monitors around the Houston ship channel, a major industrial port.

  20. Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes.

    Seo, Byoung-Joon; Nissly, Carl; Troy, Mitchell; Angeli, George; Bernier, Robert; Stepp, Larry; Williams, Eric

    2013-06-20

    We present a method which estimates the normalized point-source sensitivity (PSSN) of a segmented telescope when only information from a single segment surface is known. The estimation principle is based on a statistical approach with an assumption that all segment surfaces have the same power spectral density (PSD) as the given segment surface. As presented in this paper, the PSSN based on this statistical approach represents a worst-case scenario among statistical random realizations of telescopes when all segment surfaces have the same PSD. Therefore, this method, which we call the vendor table, is expected to be useful for individual segment specification such as the segment polishing specification. The specification based on the vendor table can be directly related to a science metric such as PSSN and provides the mirror vendors significant flexibility by specifying a single overall PSSN value for them to meet. We build a vendor table for the Thirty Meter Telescope (TMT) and test it using multiple mirror samples from various mirror vendors to prove its practical utility. Accordingly, TMT has a plan to adopt this vendor table for its M1 segment final mirror polishing requirement. PMID:23842151

  1. Novel Remarks on Point Mass Sources, Firewalls, Null Singularities and Gravitational Entropy

    Perelman, Carlos Castro

    2016-01-01

    A continuous family of static spherically symmetric solutions of Einstein's vacuum field equations with a spatial singularity at the origin r = 0 is found. These solutions are parametrized by a real valued parameter λ (ranging from 0 to 1) and such that the radial horizon's location is displaced continuously towards the singularity ( r = 0 ) as λ increases. In the extreme limit λ = 1, the location of the singularity and horizon merges leading to a null singularity. In this extreme case, any infalling observer hits the null singularity at the very moment he/she crosses the horizon. This fact may have important consequences for the resolution of the fire wall problem and the complementarity controversy in black holes. An heuristic argument is provided how one might avoid the Hawking particle emission process in this extreme case when the singularity and horizon merges. The field equations due to a delta-function point-mass source at r = 0 are solved and the Euclidean gravitational action corresponding to those solutions is evaluated explicitly. It is found that the Euclidean action is precisely equal to the black hole entropy (in Planck area units). This result holds in any dimensions D ≥ 3.

  2. Pollution of surface waters by metalaxyl and nitrate from non-point sources.

    Bermúdez-Couso, Alipio; Fernández-Calviño, David; Álvarez-Enjo, Manuel Ali; Simal-Gándara, Jesús; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2013-09-01

    The mobility of contaminants in soil is highly dependent upon the characteristics of the contaminant chemical and the properties of the soil. In order to explore these relationships, the district of A Limia (Galicia, NW Spain) was selected as the study area--a cropland devoted to growing potatoes, where the soil had been managed intensively over the last 50 years. The soil was characterised by low slopes with the water table located very close to the soil surface. Our aim was to study the influence of high and intensive crop production on the water bodies and non-point source contamination, with a particular focus on metalaxyl and nitrate. The highest concentrations of metalaxyl occurred when rainfalls were low and in zones of the study area where natural hydrology was significantly altered by numerous drainage canals. The spatial and temporal distributions of the nitrate also showed a high variability, with the interaction between seasons and sampling area being the most significant factor in explaining the levels found. PMID:23738984

  3. Economic-environmental modeling of point source pollution in Jefferson County, Alabama, USA.

    Kebede, Ellene; Schreiner, Dean F; Huluka, Gobena

    2002-05-01

    This paper uses an integrated economic-environmental model to assess the point source pollution from major industries in Jefferson County, Northern Alabama. Industrial expansion generates employment, income, and tax revenue for the public sector; however, it is also often associated with the discharge of chemical pollutants. Jefferson County is one of the largest industrial counties in Alabama that experienced smog warnings and ambient ozone concentration, 1996-1999. Past studies of chemical discharge from industries have used models to assess the pollution impact of individual plants. This study, however, uses an extended Input-Output (I-O) economic model with pollution emission coefficients to assess direct and indirect pollutant emission for several major industries in Jefferson County. The major findings of the study are: (a) the principal emission by the selected industries are volatile organic compounds (VOC) and these contribute to the ambient ozone concentration; (b) the direct and indirect emissions are significantly higher than the direct emission by some industries, indicating that an isolated analysis will underestimate the emission by an industry; (c) while low emission coefficient industries may suggest industry choice they may also emit the most hazardous chemicals. This study is limited by the assumptions made, and the data availability, however it provides a useful analytical tool for direct and cumulative emission estimation and generates insights on the complexity in choice of industries. PMID:12173425

  4. Using a dynamic point-source percolation model to simulate bubble growth

    Accurate modeling of nucleation, growth and clustering of helium bubbles within metal tritide alloys is of high scientific and technological importance. Of interest is the ability to predict both the distribution of these bubbles and the manner in which these bubbles interact at a critical concentration of helium-to-metal atoms to produce an accelerated release of helium gas. One technique that has been used in the past to model these materials, and again revisited in this research, is percolation theory. Previous efforts have used classical percolation theory to qualitatively and quantitatively model the behavior of interstitial helium atoms in a metal tritide lattice; however, higher fidelity models are needed to predict the distribution of helium bubbles and include features that capture the underlying physical mechanisms present in these materials. In this work, we enhance classical percolation theory by developing the dynamic point-source percolation model. This model alters the traditionally binary character of site occupation probabilities by enabling them to vary depending on proximity to existing occupied sites, i.e. nucleated bubbles. This revised model produces characteristics for one and two dimensional systems that are extremely comparable with measurements from three dimensional physical samples. Future directions for continued development of the dynamic model are also outlined

  5. Using a dynamic point-source percolation model to simulate bubble growth.

    Zimmerman, Jonathan A.; Zeigler, David A.; Cowgill, Donald F.

    2004-05-01

    Accurate modeling of nucleation, growth and clustering of helium bubbles within metal tritide alloys is of high scientific and technological importance. Of interest is the ability to predict both the distribution of these bubbles and the manner in which these bubbles interact at a critical concentration of helium-to-metal atoms to produce an accelerated release of helium gas. One technique that has been used in the past to model these materials, and again revisited in this research, is percolation theory. Previous efforts have used classical percolation theory to qualitatively and quantitatively model the behavior of interstitial helium atoms in a metal tritide lattice; however, higher fidelity models are needed to predict the distribution of helium bubbles and include features that capture the underlying physical mechanisms present in these materials. In this work, we enhance classical percolation theory by developing the dynamic point-source percolation model. This model alters the traditionally binary character of site occupation probabilities by enabling them to vary depending on proximity to existing occupied sites, i.e. nucleated bubbles. This revised model produces characteristics for one and two dimensional systems that are extremely comparable with measurements from three dimensional physical samples. Future directions for continued development of the dynamic model are also outlined.

  6. Realtime Gas Emission Monitoring at Hazardous Sites Using a Distributed Point-Source Sensing Infrastructure.

    Manes, Gianfranco; Collodi, Giovanni; Gelpi, Leonardo; Fusco, Rosanna; Ricci, Giuseppe; Manes, Antonio; Passafiume, Marco

    2016-01-01

    This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant's critical areas; each sub-net includes a gateway unit wirelessly connected to the WSN nodes, hence providing an easily deployable, stand-alone infrastructure featuring a high degree of scalability and reconfigurability. Furthermore, the system provides automated calibration routines which can be accomplished by non-specialized maintenance operators without system reliability reduction issues. Internet connectivity is provided via TCP/IP over GPRS (Internet standard protocols over mobile networks) gateways at a one-minute sampling rate. Environmental and process data are forwarded to a remote server and made available to authenticated users through a user interface that provides data rendering in various formats and multi-sensor data fusion. The platform is able to provide real-time plant management with an effective; accurate tool for immediate warning in case of critical events. PMID:26805832

  7. Experimental properties of gluon and quark jets from a point source

    Abbiendi, G; Alexander, Gideon; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bellerive, A; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Blobel, Volker; Bloodworth, Ian J; Bock, P; Böhme, J; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brigliadori, L; Brown, R M; Burckhart, Helfried J; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Davis, R; De Jong, S; de Roeck, A; Dervan, P J; Desch, Klaus; Dienes, B; Dixit, M S; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Estabrooks, P G; Etzion, E; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fleck, I; Folman, R; Frey, A; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Graham, K; Gross, E; Grunhaus, Jacob; Gruwé, M; Hanson, G G; Hansroul, M; Hapke, M; Harder, K; Harel, A; Hargrove, C K; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hobson, P R; Hoch, M; Höcker, Andreas; Hoffman, K; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Jones, C R; Jovanovic, P; Junk, T R; Kanzaki, J I; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Kim, D H; Klier, A; Kobayashi, T; Kobel, M; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kühl, T; Kyberd, P; Lafferty, G D; Landsman, Hagar Yaël; Lanske, D; Lauber, J; Lautenschlager, S R; Lawson, I; Layter, J G; Lee, A M; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Lü, J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mader, W F; Mannelli, M; Marcellini, S; Markopoulos, C; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Menke, S; Merritt, F S; Mes, H; Meyer, J; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mir, R; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rosati, S; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharff-Hansen, P; Schieck, J; Schmitt, S; Schöning, A; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Spagnolo, S; Sproston, M; Stahl, A; Stephens, K; Steuerer, J; Stoll, K; Strom, D; Ströhmer, R; Surrow, B; Talbot, S D; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomas, J; Thomson, M A; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Ueda, I; Van Kooten, R; Vannerem, P; Verzocchi, M; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D

    1999-01-01

    Gluon jets are identified in hadronic Z0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large transverse momentum, we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29 +- 0.09 +- 0.15 in agreement with the prediction that this ratio should ap...

  8. Vacuum local and global electromagnetic self-energies for a point-like and an extended field source

    Passante, Roberto; Spagnolo, Salvatore

    2012-01-01

    We consider vacuum electric and magnetic energy densities (or equivalently field fluctuations) in the space around a point-like or an extended ground-state field source, and discuss the problem of their singular behavior at the source's position. We show that the assumption of point-like source leads to a divergence of the renormalized energy densities at the position of the source and analyze in detail the structure of such singularity in terms of a delta function and its derivatives. We then consider the case of an extended source, smeared out over a finite volume and described by an appropriate form factor, and show that in this case all divergences in the local energy densities are removed. Our results for the structure of the divergences in the field energy densities also resolve an apparent inconsistency between the vacuum expectation value of the field Hamiltonian and of the field energy densities integrated over all space.

  9. Comparison of 3.6 - 8.0 Micron Spitzer/IRAC Galactic Center Survey Point Sources with Chandra X-Ray Point Sources in the Central 40x40 Parsecs

    Arendt, R G; Stolovy, S R; Sellgren, K; Smith, R; Ramírez, S V; Yusef-Zadeh, F; Law, C J; Smith, H A; Cotera, A S; Moseley, S H

    2008-01-01

    We have studied the correlation between 2357 Chandra X-ray point sources in a 40 x 40 parsec field and ~20,000 infrared sources we observed in the corresponding subset of our 2 x 1.4 degree Spitzer/IRAC Galactic Center Survey at 3.6-8.0 um, using various spatial and X-ray hardness thresholds. The correlation was determined for source separations of less than 0.5", 1" or 2". Only the soft X-ray sources show any correlation with infrared point sources on these scales, and that correlation is very weak. The upper limit on hard X-ray sources that have infrared counterparts is <1.7% (3 sigma). However, because of the confusion limit of the IR catalog, we only detect IR sources with absolute magnitudes < ~1. As a result, a stronger correlation with fainter sources cannot be ruled out. Only one compact infrared source, IRS 13, coincides with any of the dozen prominent X-ray emission features in the 3 x 3 parsec region centered on Sgr A*, and the diffuse X-ray and infrared emission around Sgr A* seems to be ant...

  10. Simulation of germanium detector calibration using the Monte Carlo method: comparison between point and surface source models.

    Ródenas, J; Burgos, M C; Zarza, I; Gallardo, S

    2005-01-01

    Simulation of detector calibration using the Monte Carlo method is very convenient. The computational calibration procedure using the MCNP code was validated by comparing results of the simulation with laboratory measurements. The standard source used for this validation was a disc-shaped filter where fission and activation products were deposited. Some discrepancies between the MCNP results and laboratory measurements were attributed to the point source model adopted. In this paper, the standard source has been simulated using both point and surface source models. Results from both models are compared with each other as well as with experimental measurements. Two variables, namely, the collimator diameter and detector-source distance have been considered in the comparison analysis. The disc model is seen to be a better model as expected. However, the point source model is good for large collimator diameter and also when the distance from detector to source increases, although for smaller sizes of the collimator and lower distances a surface source model is necessary. PMID:16604596

  11. Mitigating Non-Point Source Pollution in the Abbotsford Sumas Aquifer: An Evidence Based Evaluation of the Effectiveness of the BC Action Plan to Tackle Non-Point Source Water Pollution

    Allan, Beverly

    2016-01-01

    At the turn of the 20th century, BC completed its first public status report on the quality of water and found that 10% of the water sources monitored had poor water quality caused primarily by non-point source pollution. The Abbotsford-Sumas Aquifer (ASA) was mentioned in this report and it has had persistent and significant nitrate contamination, primarily from agriculture, for decades despite mitigation efforts. This poses significant public health, ecological and economic risks to the reg...

  12. NuSTAR Hard X-ray Survey of the Galactic Center Region II: X-ray Point Sources

    Hong, JaeSub; Hailey, Charles J; Nynka, Melania; Zhang, Shuo; Gotthelf, Eric; Fornasini, Francesca M; Krivonos, Roman; Bauer, Franz; Perez, Kerstin; Tomsick, John A; Bodaghee, Arash; Chiu, Jeng-Lun; Clavel, Maïca; Stern, Daniel; Grindlay, Jonathan E; Alexander, David M; Aramaki, Tsuguo; Baganoff, Frederick K; Barret, David; Barrière, Nicolas; Boggs, Steven E; Canipe, Alicia M; Christensen, Finn E; Craig, William W; Desai, Meera A; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W; Harrison, Fiona A; Hong, Dooran; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E; Madsen, Kristen K; Mao, Peter H; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J; Puccetti, Simonetta; Rana, Vikram; Westergaard, Niels J; Zhang, William W; Zoglauer, Andreas

    2016-01-01

    We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg^2 region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. We identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ~4 x and ~8 x 10^32 erg s^-1 at the GC (8 kpc) in the 3-10 and 10-40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources ...

  13. Instream Biological Assessment of NPDES Point Source Discharges at the Savannah River Site, 2000

    The Savannah River Site (SRS) currently has 31 NPDES outfalls that have been permitted by the South Carolina Department of Health and Environmental Control (SCDHEC) to discharge to SRS streams and the Savannah River. In order to determine the cumulative impacts of these discharges to the receiving streams, a study plan was developed to perform in-stream assessments of the fish assemblages, macroinvertebrate assemblages, and habitats of the receiving streams. These studies were designed to detect biological impacts due to point source discharges. Sampling was initially conducted between November 1997 and July 1998 and was repeated in the summer and fall of 2000. A total of 18 locations were sampled (Table 1, Figure 1). Sampling locations for fish and macroinvertebrates were generally the same. However, different locations were sampled for fish (Road A-2) and macroinvertebrates (Road C) in the lower portion of Upper Three Runs, to avoid interference with ongoing fisheries studies at Road C. Also, fish were sampled in Fourmile Branch at Road 4 rather than at Road F because the stream at Road F was too narrow and shallow to support many fish. Sampling locations and parameters are detailed in Sections 2 and 3 of this report. In general, sampling locations were selected that would permit comparisons upstream and downstream of NPDES outfalls. In instances where this approach was not feasible because effluents discharge into the headwaters of a stream, appropriate unimpacted reference were used for comparison purposes. This report summarizes the results of the sampling that was conducted in 2000 and also compares these data to the data that were collected in 1997 and 1998

  14. Watershed-based point sources permitting strategy and dynamic permit-trading analysis.

    Ning, Shu-Kuang; Chang, Ni-Bin

    2007-09-01

    Permit-trading policy in a total maximum daily load (TMDL) program may provide an additional avenue to produce environmental benefit, which closely approximates what would be achieved through a command and control approach, with relatively lower costs. One of the important considerations that might affect the effective trading mechanism is to determine the dynamic transaction prices and trading ratios in response to seasonal changes of assimilative capacity in the river. Advanced studies associated with multi-temporal spatially varied trading ratios among point sources to manage water pollution hold considerable potential for industries and policy makers alike. This paper aims to present an integrated simulation and optimization analysis for generating spatially varied trading ratios and evaluating seasonal transaction prices accordingly. It is designed to configure a permit-trading structure basin-wide and provide decision makers with a wealth of cost-effective, technology-oriented, risk-informed, and community-based management strategies. The case study, seamlessly integrating a QUAL2E simulation model with an optimal waste load allocation (WLA) scheme in a designated TMDL study area, helps understand the complexity of varying environmental resources values over space and time. The pollutants of concern in this region, which are eligible for trading, mainly include both biochemical oxygen demand (BOD) and ammonia-nitrogen (NH3-N). The problem solution, as a consequence, suggests an array of waste load reduction targets in a well-defined WLA scheme and exhibits a dynamic permit-trading framework among different sub-watersheds in the study area. Research findings gained in this paper may extend to any transferable dynamic-discharge permit (TDDP) program worldwide. PMID:16930806

  15. Relationship Between Non-Point Source Pollution and Korean Green Factor

    Seung Chul Lee

    2015-01-01

    Full Text Available In determining the relationship between the rational event mean concentration (REMC which is a volume-weighted mean of event mean concentrations (EMCs as a non-point source (NPS pollution indicator and the green factor (GF as a low impact development (LID land use planning indicator, we constructed at runoff database containing 1483 rainfall events collected from 107 different experimental catchments from 19 references in Korea. The collected data showed that EMCs were not correlated with storm factors whereas they showed significant differences according to the land use types. The calculated REMCs for BOD, COD, TSS, TN, and TP showed negative correlations with the GFs. However, even though the GFs of the agricultural area were concentrated in values of 80 like the green areas, the REMCs for TSS, TN, and TP were especially high. There were few differences in REMC runoff characteristics according to the GFs such as recreational facilities areas in suburbs and highways and trunk roads that connect to major roads between major cities. Except for those areas, the REMCs for BOD and COD were significantly related to the GFs. The REMCs for BOD and COD decreased when the rate of natural green area increased. On the other hand, some of the REMCs for TSS, TN, and TP were still high where the catchments encountered mixed land use patterns, especially public facility areas with bare ground and artificial grassland areas. The GF could therefore be used as a major planning indicator when establishing land use planning aimed at sustainable development with NPS management in urban areas if the weighted GF values will be improved.

  16. Evaluation of a non-point source pollution model, AnnAGNPS, in a tropical watershed

    Polyakov, V.; Fares, A.; Kubo, D.; Jacobi, J.; Smith, C.

    2007-01-01

    Impaired water quality caused by human activity and the spread of invasive plant and animal species has been identified as a major factor of degradation of coastal ecosystems in the tropics. The main goal of this study was to evaluate the performance of AnnAGNPS (Annualized Non-Point Source Pollution Model), in simulating runoff and soil erosion in a 48 km2 watershed located on the Island of Kauai, Hawaii. The model was calibrated and validated using 2 years of observed stream flow and sediment load data. Alternative scenarios of spatial rainfall distribution and canopy interception were evaluated. Monthly runoff volumes predicted by AnnAGNPS compared well with the measured data (R2 = 0.90, P < 0.05); however, up to 60% difference between the actual and simulated runoff were observed during the driest months (May and July). Prediction of daily runoff was less accurate (R2 = 0.55, P < 0.05). Predicted and observed sediment yield on a daily basis was poorly correlated (R2 = 0.5, P < 0.05). For the events of small magnitude, the model generally overestimated sediment yield, while the opposite was true for larger events. Total monthly sediment yield varied within 50% of the observed values, except for May 2004. Among the input parameters the model was most sensitive to the values of ground residue cover and canopy cover. It was found that approximately one third of the watershed area had low sediment yield (0-1 t ha-1 y-1), and presented limited erosion threat. However, 5% of the area had sediment yields in excess of 5 t ha-1 y-1. Overall, the model performed reasonably well, and it can be used as a management tool on tropical watersheds to estimate and compare sediment loads, and identify "hot spots" on the landscape. ?? 2007 Elsevier Ltd. All rights reserved.

  17. New 20-cm radio-continuum study of the Small Magellanic Cloud, part II: Point sources

    Wong G.F.

    2011-01-01

    Full Text Available We present a new catalogue of radio-continuum sources in the field of the Small Magellanic Cloud (SMC. This catalogue contains sources previously not found in 2370 MHz (λ=13 cm with sources found at 1400 MHz (λ=20 cm and 843 MHz (λ=36 cm. 45 sources have been detected at 13 cm, with 1560 sources at 20 cm created from new high sensitivity and resolution radio-continuum images of the SMC at 20 cm from paper I. We also created a 36 cm catalogue to which we listed 1689 radio-continuum sources.

  18. Identifying and characterizing major emission point sources as a basis for geospatial distribution of mercury emissions inventories

    Steenhuisen, Frits; Wilson, Simon J.

    2015-07-01

    Mercury is a global pollutant that poses threats to ecosystem and human health. Due to its global transport, mercury contamination is found in regions of the Earth that are remote from major emissions areas, including the Polar regions. Global anthropogenic emission inventories identify important sectors and industries responsible for emissions at a national level; however, to be useful for air transport modelling, more precise information on the locations of emission is required. This paper describes the methodology applied, and the results of work that was conducted to assign anthropogenic mercury emissions to point sources as part of geospatial mapping of the 2010 global anthropogenic mercury emissions inventory prepared by AMAP/UNEP. Major point-source emission sectors addressed in this work account for about 850 tonnes of the emissions included in the 2010 inventory. This work allocated more than 90% of these emissions to some 4600 identified point source locations, including significantly more point source locations in Africa, Asia, Australia and South America than had been identified during previous work to geospatially-distribute the 2005 global inventory. The results demonstrate the utility and the limitations of using existing, mainly public domain resources to accomplish this work. Assumptions necessary to make use of selected online resources are discussed, as are artefacts that can arise when these assumptions are applied to assign (national-sector) emissions estimates to point sources in various countries and regions. Notwithstanding the limitations of the available information, the value of this procedure over alternative methods commonly used to geo-spatially distribute emissions, such as use of 'proxy' datasets to represent emissions patterns, is illustrated. Improvements in information that would facilitate greater use of these methods in future work to assign emissions to point-sources are discussed. These include improvements to both national

  19. The Chandra Galactic Bulge Survey: optical catalogue and point-source counterparts to X-ray sources

    Wevers, T.; Hodgkin, S. T.; Jonker, P. G.; Bassa, C.; Nelemans, G.; van Grunsven, T.; Gonzalez-Solares, E. A.; Torres, M. A. P.; Heinke, C.; Steeghs, D.; Maccarone, T. J.; Britt, C.; Hynes, R. I.; Johnson, C.; Wu, Jianfeng

    2016-06-01

    As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue of optical sources in the GBS footprint. This consists of two regions centred at Galactic latitude b = 1.5° above and below the Galactic Centre, spanning (l × b) = (6° × 1°). The catalogue consists of two or more epochs of observations for each line of sight in r', i' and H α filters. The catalogue is complete down to r' = 20.2 and i' = 19.2 mag; the mean 5σ depth is r' = 22.5 and i' = 21.1 mag. The mean root-mean-square residuals of the astrometric solutions is 0.04 arcsec. We cross-correlate this optical catalogue with the 1640 unique X-ray sources detected in Chandra observations of the GBS area, and find candidate optical counterparts to 1480 X-ray sources. We use a false alarm probability analysis to estimate the contamination by interlopers, and expect ˜10 per cent of optical counterparts to be chance alignments. To determine the most likely counterpart for each X-ray source, we compute the likelihood ratio for all optical sources within the 4σ X-ray error circle. This analysis yields 1480 potential counterparts (˜90 per cent of the sample). 584 counterparts have saturated photometry (r' ≤ 17, i' ≤ 16), indicating these objects are likely foreground sources and the real counterparts. 171 candidate counterparts are detected only in the i' band. These sources are good qLMXB and CV candidates as they are X-ray bright and likely located in the Bulge.

  20. Role of rural solid waste management in non-point source pollution control of Dianchi Lake catchments, China

    Wenjing LU; Hongtao WANG

    2008-01-01

    In recent years, with control of the main municipal and industrial point pollution sources and implementation of cleaning for some inner pollution sources in the water body, the discharge of point source pollution decreased gradually, while non-point source pollution has become increasingly distressing in Dianchi Lake catchments. As one of the major targets in non-point source pollution control, an integrated solid waste controlling strategy combined with a technological solution and management system was proposed and implemented based on the waste disposal situation and characteristics of rural solid waste in the demonstration area. As the key technoogy in rural solid waste treatment, both centralized plantscale composting and a dispersed farmer-operated waste treating system showed promise in rendering timely benefits in efficiency, large handling capacity, high quality of the end product, as well as good economic return. Problems encountered during multi-substrates co-com-posting such as pathogens, high moisture content, asyn-chronism in the decomposition of different substrates, and low quality of the end product can all be tackled. 92.5% of solid waste was collected in the demonstration area, while the treating and recycling ratio reached 87.9%, which pre-vented 32.2 t nitrogen and 3.9 t phosphorus per year from entering the water body of Dianchi Lake after imple-mentation of the project.

  1. The BEACHES Study: health effects and exposures from non-point source microbial contaminants in subtropical recreational marine waters

    Fleisher, Jay M.; Fleming, Lora E; Solo-Gabriele, Helena M.; Jonathan K. Kish; Sinigalliano, Christopher D; Plano, Lisa; Elmir, Samir M.; Wang, John D.; Withum, Kelly; Shibata, Tomoyuki; Gidley, Maribeth L.; Abdelzaher, Amir; He, Guoqing; Ortega, Cristina; Zhu, Xiaofang

    2010-01-01

    Background Microbial water-quality indicators, in high concentrations in sewage, are used to determine whether water is safe for recreational purposes. Recently, the use of these indicators to regulate recreational water bodies, particularly in sub/tropical recreational marine waters without known sources of sewage, has been questioned. The objectives of this study were to evaluate the risk to humans from exposure to subtropical recreational marine waters with no known point source, and the p...

  2. Monitoring and Modeling Non-Point Source Contributions of Host-Specific Fecal Contamination in San Pablo Bay

    Wuertz, Stefan; Bombardelli, Fabian A; Sirikanchana, Kwanrawee; Wang, Dan

    2009-01-01

    Fecal contamination from non-point sources in coastal and estuarine water bodies is a problem of increasing concern. Water monitoring alone is sometimes insufficient in providing a clear picture of the fecal contamination of a water body. Well-formulated and developed mathematical and numerical transport models, on the contrary, predict continuous concentrations of microbial indicators under diverse scenarios of interest, and they can quantify fecal source contributions on a land use basis (h...

  3. Search of MeV-GeV counterparts of TeV sources with AGILE in pointing mode

    Rappoldi, A.; Lucarelli, F.; Pittori, C.; Longo, F.; Cattaneo, P. W.; Verrecchia, F.; Tavani, M.; Bulgarelli, A.; Chen, A. W.; Colafrancesco, S.; Donnarumma, I.; Giuliani, A.; Morselli, A.; Sabatini, S.; Vercellone, S.

    2016-03-01

    Context. Known TeV sources detected by major Čerenkov telescopes are investigated to identify possible MeV-GeV γ-ray counterparts. Aims: A systematic study of the known sources in the web-based TeVCat catalog has been performed to search for possible γ-ray counterparts on the AGILE data collected during the first period of operations in observing pointing mode. Methods: For each TeV source, a search for a possible γ-ray counterpart that is based on a multi-source maximum likelihood algorithm is performed on the AGILE data taken with the GRID instrument from July 2007 to October 2009. Results: In the case of high-significance detection, the average γ-ray flux is estimated. For cases of low-significance detection the 95% confidence level (CL) flux upper limit is given. 52 TeV sources out of 152 (corresponding to ~34% of the analysed sample) show a significant excess in the AGILE data covering the pointing observation period. Conclusions: This analysis found 26 new AGILE sources with respect to the AGILE reference catalogs, 15 of which are galactic, 7 are extragalactic and 4 are unidentified. Detailed tables with all available information on the analysed sources are presented. An interactive online version of the considered source list including all the analysis results is also available at the website http://www.asdc.asi.it/agiletevcat/

  4. A modified likelihood-method to search for point-sources in the diffuse astrophysical neutrino-flux in IceCube

    IceCube, a cubic-kilometer sized neutrino detector at the geographical South Pole, has recently measured a flux of high-energy astrophysical neutrinos. Although this flux has now been observed in multiple analyses, no point sources or source classes could be identified yet. Standard point source searches test many points in the sky for a point source of astrophysical neutrinos individually and therefore produce many trials. Our approach is to additionally use the measured diffuse spectrum to constrain the number of possible point sources and their properties. Initial studies of the method performance are shown.

  5. [Multiple time scales analysis of spatial differentiation characteristics of non-point source nitrogen loss within watershed].

    Liu, Mei-bing; Chen, Xing-wei; Chen, Ying

    2015-07-01

    Identification of the critical source areas of non-point source pollution is an important means to control the non-point source pollution within the watershed. In order to further reveal the impact of multiple time scales on the spatial differentiation characteristics of non-point source nitrogen loss, a SWAT model of Shanmei Reservoir watershed was developed. Based on the simulation of total nitrogen (TN) loss intensity of all 38 subbasins, spatial distribution characteristics of nitrogen loss and critical source areas were analyzed at three time scales of yearly average, monthly average and rainstorms flood process, respectively. Furthermore, multiple linear correlation analysis was conducted to analyze the contribution of natural environment and anthropogenic disturbance on nitrogen loss. The results showed that there were significant spatial differences of TN loss in Shanmei Reservoir watershed at different time scales, and the spatial differentiation degree of nitrogen loss was in the order of monthly average > yearly average > rainstorms flood process. TN loss load mainly came from upland Taoxi subbasin, which was identified as the critical source area. At different time scales, land use types (such as farmland and forest) were always the dominant factor affecting the spatial distribution of nitrogen loss, while the effect of precipitation and runoff on the nitrogen loss was only taken in no fertilization month and several processes of storm flood at no fertilization date. This was mainly due to the significant spatial variation of land use and fertilization, as well as the low spatial variability of precipitation and runoff. PMID:26710649

  6. Five-Level Z-Source Neutral Point-Clamped Inverter

    Gao, F.; Loh, P.C.; Blaabjerg, Frede;

    2007-01-01

    This paper proposes a five-level Z-source neutralpoint- clamped (NPC) inverter with two Z-source networks functioning as intermediate energy storages coupled between dc sources and NPC inverter circuitry. Analyzing the operational principles of Z-source network with partial dclink shoot......-through scheme reveals the hidden theories in the five-level Z-source NPC inverter unlike the operational principle appeared in the general two-level Z-source inverter, so that the five-level Z-source NPC inverter can be designed with the modulation of carrier-based phase disposition (PD) or alternative phase...... opposite disposition (APOD) technique. To verify the theoretical findings and practical issues, a scaled down laboratory prototype was constructed and tested with a 1.3 kw induction motor load....

  7. The Chandra Galactic Bulge Survey: optical catalogue and point-source counterparts to X-ray sources

    Wevers, T; Jonker, P G; Bassa, C; Nelemans, G; van Grunsven, T; Gonzalez-Solares, E A; Torres, M A P; Heinke, C; Steeghs, D; Maccarone, T J; Britt, C; Hynes, R I; Johnson, C; Wu, Jianfeng

    2016-01-01

    As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue of optical sources in the GBS footprint. This consists of two regions centered at Galactic latitude b = 1.5 degrees above and below the Galactic Centre, spanning (l x b) = (6x1) degrees. The catalogue consists of 2 or more epochs of observations for each line of sight in r', i' and H{\\alpha} filters. It is complete down to r' = 20.2 and i' = 19.2 mag; the mean 5{\\sigma} depth is r' = 22.5 and i' = 21.1 mag. The mean root-mean-square residuals of the astrometric solutions is 0.04 arcsec. We cross-correlate this optical catalogue with the 1640 unique X-ray sources detected in Chandra observations of the GBS area, and find candidate optical counterparts to 1480 X-ray sources. We use a false alarm probability analysis to estimate the contamination by interlopers, and expect ~ 10 per cent of optical counterparts to be chance alignments. To determine the most likely counterpart for each X-ray source, we compute the likelihood ratio for all o...

  8. A Bayesian geostatistical approach for evaluating the uncertainty of contaminant mass discharges from point sources

    Troldborg, M.; Nowak, W.; Binning, P. J.; Bjerg, P. L.

    2012-12-01

    Estimates of mass discharge (mass/time) are increasingly being used when assessing risks of groundwater contamination and designing remedial systems at contaminated sites. Mass discharge estimates are, however, prone to rather large uncertainties as they integrate uncertain spatial distributions of both concentration and groundwater flow velocities. For risk assessments or any other decisions that are being based on mass discharge estimates, it is essential to address these uncertainties. We present a novel Bayesian geostatistical approach for quantifying the uncertainty of the mass discharge across a multilevel control plane. The method decouples the flow and transport simulation and has the advantage of avoiding the heavy computational burden of three-dimensional numerical flow and transport simulation coupled with geostatistical inversion. It may therefore be of practical relevance to practitioners compared to existing methods that are either too simple or computationally demanding. The method is based on conditional geostatistical simulation and accounts for i) heterogeneity of both the flow field and the concentration distribution through Bayesian geostatistics (including the uncertainty in covariance functions), ii) measurement uncertainty, and iii) uncertain source zone geometry and transport parameters. The method generates multiple equally likely realizations of the spatial flow and concentration distribution, which all honour the measured data at the control plane. The flow realizations are generated by analytical co-simulation of the hydraulic conductivity and the hydraulic gradient across the control plane. These realizations are made consistent with measurements of both hydraulic conductivity and head at the site. An analytical macro-dispersive transport solution is employed to simulate the mean concentration distribution across the control plane, and a geostatistical model of the Box-Cox transformed concentration data is used to simulate observed

  9. Analytical calculation of the solid angle subtended by a circular disc detector at a point cosine source

    We derive analytical expressions for the solid angle subtended by a circular disc at a point source with cosine angular distribution (f(μ)=μ/π) under the sole condition that the disc lies in the half-space illuminated by the source (μ≥0). The expressions are given with reference to two alternative coordinate systems (S and S'), S being such that the z-axis is parallel to the symmetry axis of the disc and S' such that the z'-axis is aligned with the source direction. Sample plots of the expressions are presented

  10. Inversion for slip on a finite fault and fast estimation of seismic parameters in the point source case

    Gallo, Antonella

    2012-01-01

    ABSTRACT One of the principal goals of seismology is to infer the nature of an earthquake source from observations of seismic ground motion. This work shall discuss the seismic source both in the 2D finite-fault and in the point-source approximation. By inverting 3-component accelerograms the rupture history and the slip distribution for the Mw 6.3 earthquake occurred in central Italy on April 6, 2009 are determined. The method of linear programming is used for the inversion and the si...

  11. Searches for Extended and Point-like Neutrino Sources with Four Years of IceCube Data

    Aartsen, M.G.; Ackermann, M.; Adams, J.; Aguilar, J.A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Arguelles, C.; Sarkar, Subir; Koskinen, David Jason; Medici, Morten Ankersen

    2014-01-01

    introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of......We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the combined data set is 1373 days. For an E –2 spectrum, the observed 90% C.L. flux upper limits are...

  12. A Northern Sky Survey for Steady TeV Gamma-Ray Point Sources Using the Tibet Air Shower Array

    Amenomori, M; Cui, S W; Danzengluobu; Ding, L K; Ding, X H; Feng Cun Feng; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Haibing, H; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, J Y; Lü, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saitô, T; Sakata, M; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takashima, M; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Utsugi, T; Wang, H; Wang, X; Wang, Y G; Wu, H R; Xue Liang; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S I; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Yi Zhang; Zhang, Y; Zhaxi Sang Zhu; Zhou, X X

    2005-01-01

    Results on TeV gamma-ray point source search using data taken from the Tibet HD (Feb. 1997 -- Sep. 1999) and Tibet III (Nov. 1999 -- Oct. 2001) arrays are presented. From 0 degree to 60 degree in declination (Dec), significan t excesses from the well-known steady source Crab Nebula and the high state of the flare type source Markarian 421 ar e observed. Because the levels of significance from other positions are not sufficiently high, a 90% confidence leve l (CL) upper limit on the flux is set assuming a Crab like energy spectrum. To allow cross-checking, two independentl y developed analyses are used in this work.

  13. Impact of Point and Non-point Source Pollution on Coral Reef Ecosystems In Mamala Bay, Oahu, Hawaii based on Water Quality Measurements and Benthic Surveys in 1993-1994 (NODC Accession 0001172)

    National Oceanic and Atmospheric Administration, Department of Commerce — The effects of both point and non-point sources of pollution on coral reef ecosystems in Mamala Bay were studied at three levels of biological organization; the...

  14. Cost-Effectiveness of Alternative Environmental Policies for Reducing Non-Point Source Pollution in Public Water Supplies

    Mafoua, Edouard; Hornbaker, Robert H.

    2006-01-01

    This study predicts farmers' response to policy alternatives aimed at alleviating non-point source pollution problems in a municipal water supply in Pike County, Illinois. The framework integrated simulation models with optimization models of the watershed to assess environmental policies. Results show how farmers are likely to alter agricultural management practices.

  15. Long-term vegetation landscape pattern with non-point source nutrient pollution in upper stream of Yellow River basin

    Ouyang, W.; Skidmore, A.K.; Toxopeus, A.G.; Hao, F.

    2010-01-01

    Grassland, forest, and farmland are the dominant land covers in upper catchments of the Yellow River and their landscape status has direct connection with dynamics of non-point source (NPS) pollution. Understanding the correlations between landscape variables and different formats of NPS nutrients p

  16. The analytical calculation of the radiance distribution inside and outside a layered sphere or cylinder generated by a point source.

    Hoenders, BJ; Benaron, DA; Chance, B; Ferrari, M; Katzir, A

    1998-01-01

    We consider an anisotropically scattering layered cylinder or sphere illuminated by a point source. The scattered field generated by these bodies is calculated in terms of the appropriate mode decomposition of the radiance. This leads to mode-expansions for the radiance which are very similar to the

  17. A planar circular detector based on multiple point chemi- or bio-luminescent source within a coaxial cylindrical reactor

    An analytical method was proposed for calculating radiative fluxes incident on a planar circular detector from a volume multiple point chemi- or bio-luminescent source inside a coaxial cylindrical reactor. The method was designed for a cylindrical reactor when the surface reflections were neglected and when chemi- or bio-luminescence reaches a detector embedded in the same homogeneous optical medium as the point emitters of the volume multiple point source model. The radiative fluxes from arbitrarily distributed point emitters were expressed by one generalized quadruple-integral formula. Then some double- and single-integral formulas were obtained for calculating radiative fluxes from identically radiating point emitters uniformly distributed within the reactor. Selected results were computed and illustrated graphically. The obtained formulas are suitable for optimizing and/or calibrating the considered source-detectors systems (optical radiometers or luminometers) and determining radiative fluxes generated by chemical, biological, and physical processes leading to chemi-, bio-, radio-, and sono-luminescence for example.

  18. Conditions for perfect focusing multiple point sources with the SMS design method

    Benítez, P.; Miñano, Juan C.; Nikolic, Milena; Liu, Jiayao; Infante, Jose; Duerr, Fabian

    2014-09-01

    In this work, we demonstrate how it is possible to sharply image multiple object points. The Simultaneous Multiple Surface (SMS) design method has usually been presented as a method to couple N wave-front pairs with N surfaces, but recent findings show that when using N surfaces, we can obtain M image points when NSMS method, from its basics, to imaging two object points through one surface, the transition from two to three objet points obtained by increasing the parallelism, and getting to the designs of six surfaces imaging up to eight object points. These designs are limited with the condition that the surfaces cannot be placed at the aperture stop. In the process of maximizing the object points to sharp image, we try to exhaust the degrees of freedom of aspherics and free-forms. We conjecture that maximal SMS designs are very close to a good solution, hence using them as a starting point for the optimization will lead us faster to a final optical system. We suggest here different optimization strategies which combined with the SMS method are proven to give the best solution. Through the example of imaging with the high aspect ratio, we compare the results obtained optimizing the rotational lens and using a combination of SMS method and optimization, showing that the second approach is giving significantly smaller value of overall RMS spot diameter.

  19. X-Ray Properties of the Point Source Population in the Spiral Galaxy NGC 5055 (M63) with Chandra

    Luo, B; Zhang, Z; Wang, Y; Wang, J; Xu, H; Luo, Bing; Chen, Jiyao; Zhang, Zhongli; Wang, Yu; Wang, Jingying; Xu, Haiguang

    2007-01-01

    By analyzing the Chandra ACIS S3 data we studied the X-ray properties of the low-mass and high-mass X-ray binary populations in the nearby spiral galaxy NGC 5055. A total of 43 X-ray point sources were detected within the 2 effective radii, with 31 sources located on the disk and the rest 12 sources in the bulge. The resolved point sources dominate the total X-ray emission of the galaxy by accounting for about 80% of the total counts in 0.3--10 keV. By carrying out the spectral fittings we calculated the 0.3--10.0 keV luminosities of all the detected X-ray point sources and found that they span a wide range from a few 10^{37} erg s^{-1} to over 10^{39} erg s^{-1}. After compensating for the incompleteness at the low luminosity end, we find that the corrected XLF of the bulge population is well fitted with a broken power-law model with a break at 1.57^{+0.21}_{-0.20}\\times 10^{38} erg s^{-1}, while the profile of the disk population's XLF agrees with a single power-law distribution with a slope of 0.93^{+0.07}...

  20. The 100 Strongest Radio Point Sources in the Field of the Large Magellanic Cloud at 1.4 GHz

    Payne, J. L.

    2009-06-01

    Full Text Available We present the 100 strongest 1.4~GHz point sources from a new mosaicimage in the direction of the Large Magellanic Cloud (LMC. The observationsmaking up the mosaic were made using Australia Telescope Compact Array (ATCAover a ten year period and were combined with Parkes single dish data at 1.4 GHz to complete the image for short spacing. An initial list of co-identifications within 10arcsec at 0.843, 4.8 and 8.6 GHz consisted of 2682 sources. Elimination of extended objects and artifact noise allowed the creation of a refined list containing 1988 point sources. Most of these are presumed to be background objects seen through the LMC; a small portion may represent compact HII regions, young SNRs and radio planetary nebulae. For the 1988 point sources we find a preliminary average spectral index ($alpha$ of -0.53 and present a 1.4 GHz image showing source locationin the direction of the LMC.

  1. The Concept of ''Gramme-Equivalent-of-Radium'' for Non-Point Isotopic γ-Ray Sources

    It is very useful to use the concept of 'gramme-equivalent-of-radium' (gRa) in industrial radiography and in teletherapy to express the activity of an isotopic γ-ray source. This concept, while giving an idea of the activity of the source, permits at the same time to determine dose-rates in r/h to be expected at any distance from the source. There exists a difference of opinion as to the concept itself of the gramme- equivalent-of-radium. This occurs especially for γ-ray sources of higher activities and dimensions; when due to autoabsorption the sources cannot be regarded as point-sources. According to the existing one point of view the concept of gRa is connected directly to the isotope itself. For any particular isotope one can determine the gRa value from the ionization constant Kγ of the isotope. The other point of view attaches the gRa concept to any particular source of γ radiation. For this particular source the gRa value is determined by measuring its dose-rate in r/h at 1 m distance. For γ-ray sources of higher activities and dimensions the gRa values calculated by the two methods can differ considerably. Therefore there is a need to clarify the opinions about the gRa concept so as to be able definitively to formulate this radiologic unit. Besides it is advisable to determine standard measuring methods of the gRa unit. Sometimes, instead of the s or gRa values, one gives the ''rhm'' value (r/h at 1 m distance from the source). This value, pertaining to the source itself, is equivalent to the second concept of gRa. However, it does not give immediate information as to the activity of the source, which for many years has always been compared with radium standards. While presenting all the above mentioned aspects of the problem the authors propose, that after clarifying of misunderstandings , it shall be re- commanded to use the gRa unit for radioisotopic γ-ray sources as used in industrial radiography and teletherapy. (author)

  2. A method to analyze “source–sink” structure of non-point source pollution based on remote sensing technology

    With the purpose of providing scientific basis for environmental planning about non-point source pollution prevention and control, and improving the pollution regulating efficiency, this paper established the Grid Landscape Contrast Index based on Location-weighted Landscape Contrast Index according to the “source–sink” theory. The spatial distribution of non-point source pollution caused by Jiulongjiang Estuary could be worked out by utilizing high resolution remote sensing images. The results showed that, the area of “source” of nitrogen and phosphorus in Jiulongjiang Estuary was 534.42 km2 in 2008, and the “sink” was 172.06 km2. The “source” of non-point source pollution was distributed mainly over Xiamen island, most of Haicang, east of Jiaomei and river bank of Gangwei and Shima; and the “sink” was distributed over southwest of Xiamen island and west of Shima. Generally speaking, the intensity of “source” gets weaker along with the distance from the seas boundary increase, while “sink” gets stronger. -- Highlights: •We built an index to study the “source–sink” structure of NSP in a space scale. •The Index was applied in Jiulongjiang estuary and got a well result. •The study is beneficial to discern the high load area of non-point source pollution. -- “Source–Sink” Structure of non-point source nitrogen and phosphorus pollution in Jiulongjiang estuary in China was worked out by the Grid Landscape Contrast Index

  3. A Computer Application for Visualization of the Gas Concentration Patterns from Instant Point Source in Fluid Static and Anisotropy Medium

    The computer application for visualization of the gas concentration patterns the effect from gas leakage for example the pipe leakage of the fuel gas drilling, has been done. The application developed to assist one of the components in environmental control system in industrial area or mining area, I.e. in order to forecasting of an area contaminated the effect from pipe leakage available. The model used of unsteady state diffusion model from instant point source in fluid static and diffusion model from instant point source in anisotropy medium. The gas concentration illustrate to come from pipe leakage source is a Gauss distribution curve. The model of this computer application is simulation model with data input facilities and the simulation result is three and two dimension graph. For developed of the computer program used Matlab 6.1. By varying in inputs, the computer application produces numerous concentration gas predictions as 2-dimension, 3-dimension and contour patterns. (author)

  4. SPATIAL ANALYSIS OF SOIL EROSION AND NON-POINT SOURCE POLLUTION BASED ON GIS IN ERLONG LAKE WATERSHED, JILIN PROVINCE

    WANG Ning; ZHANG Hong-yan; WANG Hui-lian; ZHANG Zheng-xiang

    2004-01-01

    Data collection, factor composition, nappe analysis and integrative simulation of natural geographical factors in Erlong Lake watershed have been carried out based on GIS. The risk areas where non-point source pollution may occur were compartmentalized and assessed, and the total soil erosion and the runoffs of N and P with rainfall in this valley were worked out by experiment and GIS mapping. The study indicated that the main type of soil in dry land with variable slope east of the lake and the middle-south parts of steep slope mountainous region (erosion source pollution (NSP) of nitrogen and phosphorus loss was corresponded with the soil erosion. Spatial distribution and the reasons of the distribution difference have been presented and it was emphasized that the human activities among the influence factors was the most important. It surely offers a scientific basis to control and prevent non-point source pollution in the watershed.

  5. Generation of multi-keV monochromatic twin x-ray point sources based on laser-driven vacuum diode

    A simple method of generating multi-keV, monochromatic, twin x-ray point sources based on laser-driven vacuum diode is presented. Electrons from a laser-produced aluminum plasma cathode were accelerated towards two point-tip titanium anodes placed symmetrically with respect to the cathode. Temporal and spatial characterizations of the K-shell x-ray emission from the twin anodes are carried out. Each source (∼300 μm diameter) emits ∼109 Ti Kα (hν≅4.51 keV) photons in a pulse of ∼20 ns duration with a peak brightness of ∼4x1018 photons/cm2 s sr. Single-shot twin x-ray shadowgrams of physical objects were recorded at a distance of several centimeters from the two sources. Such a system may be useful for single-shot stereoradiography for differential imaging in the multi-keV energy region

  6. Point source data (drill locations) for coal in the Kaiparowits Plateau study area, southern Utah (kaiptg)

    U.S. Geological Survey, Department of the Interior — This is a point file that contains data for coal and other stratigraphic horizons in in the Calico and A-sequences of the Straight Cliffs Formation (Upper...

  7. THERMAL NEUTRON INTENSITIES IN SOILS IRRADIATED BY FAST NEUTRONS FROM POINT SOURCES. (R825549C054)

    Thermal-neutron fluences in soil are reported for selected fast-neutron sources, selected soil types, and selected irradiation geometries. Sources include 14 MeV neutrons from accelerators, neutrons from spontaneously fissioning 252Cf, and neutrons produced from alp...

  8. Multiple window spatial registration error of a gamma camera: 133Ba point source as a replacement of the NEMA procedure

    The accuracy of multiple window spatial resolution characterises the performance of a gamma camera for dual isotope imaging. In the present study we investigate an alternative method to the standard NEMA procedure for measuring this performance parameter. A long-lived 133Ba point source with gamma energies close to 67Ga and a single bore lead collimator were used to measure the multiple window spatial registration error. Calculation of the positions of the point source in the images used the NEMA algorithm. The results were validated against the values obtained by the standard NEMA procedure which uses a liquid 67Ga source with collimation. Of the source-collimator configurations under investigation an optimum collimator geometry, consisting of a 5 mm thick lead disk with a diameter of 46 mm and a 5 mm central bore, was selected. The multiple window spatial registration errors obtained by the 133Ba method showed excellent reproducibility (standard deviation < 0.07 mm). The values were compared with the results from the NEMA procedure obtained at the same locations and showed small differences with a correlation coefficient of 0.51 (p < 0.05). In addition, the 133Ba point source method proved to be much easier to use. A Bland-Altman analysis showed that the 133Ba and the 67Ga Method can be used interchangeably. The 133Ba point source method measures the multiple window spatial registration error with essentially the same accuracy as the NEMA-recommended procedure, but is easier and safer to use and has the potential to replace the current standard procedure

  9. The Chandra Galactic Bulge Survey: optical catalogue and point-source counterparts to X-ray sources

    Wevers, T.; Hodgkin, S. T.; Jonker, P. G.; Bassa, C.; Nelemans, G.; van Grunsven, T.; Gonzalez-Solares, E. A.; Torres, M. A. P.; Heinke, C.; Steeghs, D.; Maccarone, T.J.; Britt, C.; Hynes, R.I.; Johnson, C; Wu, Jianfeng

    2016-01-01

    As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue of optical sources in the GBS footprint. This consists of two regions centered at Galactic latitude b = 1.5 degrees above and below the Galactic Centre, spanning (l x b) = (6x1) degrees. The catalogue consists of 2 or more epochs of observations for each line of sight in r', i' and H{\\alpha} filters. It is complete down to r' = 20.2 and i' = 19.2 mag; the mean 5{\\sigma} depth is r' = 22.5 and i' = 21.1 mag. The mean ro...

  10. Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere.

    Ma, Denglong; Zhang, Zaoxiao

    2016-07-01

    Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem. PMID:27035273

  11. Search of MeV-GeV counterparts of TeV sources with AGILE in pointing mode

    Rappoldi, A; Pittori, C; Longo, F; Cattaneo, P W; Verrecchia, F; Tavani, M; Bulgarelli, A; Chen, A W; Colafrancesco, S; Donnarumma, I; Giuliani, A; Morselli, A; Sabatini, S; Vercellone, S

    2015-01-01

    Context. Known TeV sources detected by major Cerenkov telescopes are investigated to identify possible MeV-GeV gamma-ray counterparts. Aims. A systematic study of the known sources in the web-based TeVCat Catalog has been performed to search for possible gamma-ray counterpart on the AGILE data collected during the first period of operations in observing pointing mode. Methods. For each TeV source, a search for a possible gamma-ray counterpart based on a multi-source Maximum Likelihood algorithm is performed on the AGILE data taken with the GRID instrument from July 2007 to October 2009. Results. In case of high-significance detection, the average gamma-ray flux is estimated. For the cases of low-significance detection the 95 % Confidence Level (C.L.) flux upper limit is given. 52 TeV sources out of 152 (corresponding to ~34 % of the analysed sample) show a significant excess in the AGILE data covering the pointing observation period. Conclusions. This analysis found 26 new AGILE sources with respect to the AG...

  12. 1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra

    Evans, P A; Beardmore, A P; Page, K L; Willingale, R; Mountford, C J; Pagani, C; Burrows, D N; Kennea, J A; Perri, M; Tagliaferri, G; Gehrels, N

    2013-01-01

    We present the 1SXPS (Swift-XRT Point Source) catalog of 151,524 X-ray point-sources detected by the Swift-XRT in 8 years of operation. The catalog covers 1905 square degrees distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ~3e-13 erg/cm2/s (0.3--10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ~9e-14 erg/cm2/s (0.3--10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5 less sensitive. The median position error is 5.5" (90% confidence), including systematics. Our source detection method improves on that used in previous XRT catalogs and we report >68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ~30,000 variable objects in our catalog. For every source we give position...

  13. A THEORETICAL ANALYSIS OF KEY POINTS WHEN CHOOSING OPEN SOURCE ERP SYSTEMS

    Fernando Gustavo Dos Santos Gripe; Ildeberto Aparecido Rodello

    2011-01-01

    The present work is aimed at presenting a theoretical analysis of the main features of Open Source ERP systems, herein identified as success technical factors, in order to contribute to the establishment of parameters to be used in decision-making processes when choosing a system which fulfills the organization´s needs. Initially, the life cycle of ERP systems is contextualized, highlighting the features of Open Source ERP systems. As a result, it was verified that, when carefully analyzed, t...

  14. An investigation of approaches and analytical tools to disentangle point and diffuse sources of nitrate contamination

    Fenech, Cecilia

    2013-01-01

    Environmental forensics studies for nitrate source determination (NSD) have seen increased interest in recent years. However, the numerous approaches that have been suggested do not differentiate sewage and manure sources in surface waters. This differentiation is especially important as human-health risks are higher from human, than animal, faecal contamination. Therefore, human and veterinary pharmaceuticals were exploited as co-occurring sewage and manure markers. Through an understanding ...

  15. Continuum limit of amorphous elastic bodies (II): Response to a point source

    Leonforte, F.; Tanguy, Arnaud; Wittmer, J.P.; Barrat, J. -L.

    2004-01-01

    The linear response of two-dimensional amorphous elastic bodies to an external delta force is determined in analogy with recent experiments on granular aggregates. For the generated forces, stress and displacement fields, we find strong relative fluctuations of order one close to the source, which, however, average out readily to the classical predictions of isotropic continuum elasticity. The stress fluctuations decay (essentially) exponentially with distance from the source. Only beyond a s...

  16. Near-Infrared Spectroscopy of Faint Discrete X-ray Point Sources Constituting the Galactic Ridge X-ray Emission

    Morihana, Kumiko; Dubath, Pierre; Yoshida, Tessei; Suzuki, Kensuke; Ebisawa, Ken

    2016-01-01

    The Galactic Ridge X-ray Emission (GRXE) is apparently extended X-ray emission along the Galactic Plane. The X-ray spectrum is characterized by hard continuum with a strong Fe K emission feature in the 6-7 keV band. A substantial fraction (~80%) of the GRXE in the Fe band was resolved into point sources by deep Chandra imaging observations, thus GRXE is mostly composed of dim Galactic X-ray point sources at least in this energy band. To investigate the populations of these dim X-ray point sources, we carried out Near-Infrared (NIR) follow-up spectroscopic observations in two deep Chandra fields located in the Galactic plane at (l,b)=(0.1{\\arcdeg}, -1.4{\\arcdeg}) and (28.5{\\arcdeg}, 0.0{\\arcdeg}) using NTT/SofI and Subaru/MOIRCS. We obtained well-exposed NIR spectra from 65 objects and found that there are three main classes of Galactic sources based on the X-ray color and NIR spectral features: those having (A) hard X-ray spectra and NIR emission features such as HI(Br{\\gamma}), HeI, and HeII (2 objects), (B)...

  17. A Targeted Search for Point Sources of EeV Neutrons

    Aab, A; Aglietta, M; Ahlers, M; Ahn, E J; Samarai, I Al; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muñiz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Badescu, A M; Barber, K B; Bäuml, J; Baus, C; Beatty, J J; Becker, K H; Bellido, J A; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chavez, A G; Cheng, S H; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Collica, L; Coluccia, M R; Conceição, R; Contreras, F; Cooper, M J; Coutu, S; Covault, C E; Criss, A; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; de Jong, S J; Neto, J R T de Mello; De Mitri, I; de Oliveira, J; de Souza, V; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Di Matteo, A; Diaz, J C; Castro, M L Díaz; Diep, P N; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Erfani, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filipčič, A; Fox, B D; Fratu, O; Fröhlich, U; Fuchs, B; Fuji, T; Gaior, R; García, B; Roca, S T Garcia; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Bravo, A Gascon; Gate, F; Gemmeke, H; Ghia, P L; Giaccari, U; Giammarchi, M; Giller, M; Glaser, C; Glass, H; Albarracin, F Gomez; Berisso, M Gómez; Vitale, P F Gómez; Gonçalves, P; Gonzalez, J G; Gookin, B; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guardincerri, Y; Guarino, F; Guedes, G P; Hansen, P; Harari, D; Harrison, T A; Harton, J L; Hasankiadeh, Q D; Haungs, A; Hebbeker, T; Heck, D; Heimann, P; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Holt, E; Homola, P; Hörandel, J R; Horvath, P; Hrabovský, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Islo, K; Jandt, I; Jansen, S; Jarne, C; Josebachuili, M; Kääpä, A; Kambeitz, O; Kampert, K H; Kasper, P; Katkov, I; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; La Rosa, G; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Leão, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Malacari, M; Maldera, S; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mariş, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Martraire, D; Meza, J J Masías; Mathes, H J; Mathys, S; Matthews, A J; Matthews, J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Messina, S; Meyhandan, R; Mićanović, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morello, C; Moreno, J C; Mostafá, M; Moura, C A; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novotny, V; Nožka, L; Ochilo, L; Olinto, A; Oliveira, M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Papenbreer, P; Parente, G; Parra, A; Pastor, S; Paul, T; Pech, M; Pȩkala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Peters, C; Petrera, S; Petrolini, A; Petrov, Y; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Porcelli, A; Porowski, C; Privitera, P; Prouza, M; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; Roberts, J; de Carvalho, W Rodrigues; Cabo, I Rodriguez; Fernandez, G Rodriguez; Rojo, J Rodriguez; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Roulet, E; Rovero, A C; Rühle, C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Greus, F Salesa; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A; Scholten, O; Schoorlemmer, H; Schovánek, P; Schulz, A; Schulz, J; Sciutto, S J; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Sima, O; Śmiałkowski, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Squartini, R; Srivastava, Y N; Stanič, S; Stapleton, J; Stasielak, J; Stephan, M; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Taborda, O A; Tapia, A; Tartare, M; Thao, N T; Theodoro, V M; Tiffenberg, J; Timmermans, C; Peixoto, C J Todero; Toma, G; Tomankova, L; Tomé, B; Tonachini, A; Elipe, G Torralba; Machado, D Torres; Travnicek, P; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; van Aar, G; Berg, A M van den; van Velzen, S; van Vliet, A; Varela, E; Cárdenas, B Vargas; Varner, G; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Vlcek, B; Wahlberg, H; Wainberg, O; Walz, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Werner, F; Whelan, B J; Widom, A; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Wittkowski, D; Wundheiler, B; Wykes, S; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Zhou, J; Zhu, Y; Silva, M Zimbres; Ziolkowski, M

    2014-01-01

    A flux of neutrons from an astrophysical source in the Galaxy can be detected in the Pierre Auger Observatory as an excess of cosmic-ray air showers arriving from the direction of the source. To avoid the statistical penalty for making many trials, classes of objects are tested in combinations as nine "target sets", in addition to the search for a neutron flux from the Galactic Center or from the Galactic Plane. Within a target set, each candidate source is weighted in proportion to its electromagnetic flux, its exposure to the Auger Observatory, and its flux attenuation factor due to neutron decay. These searches do not find evidence for a neutron flux from any class of candidate sources. Tabulated results give the combined p-value for each class, with and without the weights, and also the flux upper limit for the most significant candidate source within each class. These limits on fluxes of neutrons significantly constrain models of EeV proton emission from non-transient discrete sources in the Galaxy.

  18. Is the zero-point energy a source of the cosmological constant?

    Fujii, Yasunori

    2014-01-01

    We discuss how we remove a huge discrepancy between the theory of a cosmological constant, due to the zero-point energies of matter fields, and the observation. The technique of dimensional regularization plays a decisive role. We eventually reach the desired behavior of the vacuum densities falling off like t^{-2}, allowing us to understand how an extremely small result comes about naturally. As a price, however, the zero-point energy vacuum fails to act as a true cosmological constant. Its expected role responsible for the observed accelerating universe is then to be inherited by the gravitational scalar field, dark energy, as we suggest in the scalar-tensor theory.

  19. [Spatial discharge characteristics and total load control of non-point source pollutants based on the catchment scale].

    Wang, Xia-Hui; Lu, Jun; Zhang, Qing-Zhong; Wang, Bo; Yao, Rui-Hua; Zhang, Hui-Yuan; Huang, Feng

    2011-09-01

    Agricultural non-point source pollution is one of the major causes of water quality deterioration. Based on the analysis of the spatial discharge characteristics and intensity of major pollutants from the agricultural pollution source, the establishment of spatial management subzones for controlling agricultural non-point pollution and a design of a plan for total load control of pollutants from each subzone is an important way to improve the efficiency of control measures. In this paper the Four Lake basin in Hubei Province is adopted as the research case region and a systematic research of the control countermeasures of agricultural non-point pollution based on the catchment scale is carried out. The results shows that in the Four Lake basin, the COD, total nitrogen, total phosphorus and ammonia nitrogen load of the water environment are mainly caused by agricultural non-point pollution. These four kinds of non-point source pollutants respectively account for 67.6%, 82.2%, 84.7% and 50.9% of the total pollutant discharge amount in the basin. The analysis of the spatial discharge characteristics of non-point source pollutants in the Four Lake basin shows that the major contributor source regions of non-point source pollutant in the basin are the four counties, including Honghu, Jianli, Qianjiang and Shayang where the aquatic and livestock production are relatively developed. According to the spatial discharge characteristics of the pollutants and the evaluation of the discharge intensity of pollutants, the Four Lake basin is divided into three agricultural non-point pollution management subzones, which including Changhu upstream aquatic and livestock production pollution control subzone, Four-lake trunk canal rural non-point source pollution control subzone and Honghu aquatic production pollution control subzone. Specific pollution control measures are put forward for each subzone. With a comprehensive consideration of the water quality amelioration and the

  20. A novel approach to control atmospheric methane emissions from low-volume point sources and diffused area sources

    Hettiaratchi, J.P.A.; Pokhrel, D.; Chandrakanthi, M. [Calgary Univ., AB (Canada)

    2003-07-01

    Over the past one hundred years, the atmospheric concentration of methane has significantly increased. The search for inexpensive techniques for reducing anthropogenic methane gas emissions into the atmosphere have led the authors to propose a technique called methanobiofiltration (MBF), which utilizes a naturally occurring bacterium to convert methane into carbon dioxide. It was shown that this method can be applied where conventional methods to extract methane for energy recovery may not be viable, such as controlling methane emissions from low volume, but numerous, or spatially diffused sources. A long-term research program, which involved laboratory based experimental studies, pilot-scale field studies and mathematical modeling was carried out. Several filter media were tested using passively aerated biofilter columns. The highest oxidation rate was obtained with compost. A decrease in the rate of oxidation was noted after reaching a maximum value within 100 days of continuous operation. Passively aerated biofilter columns did not perform as well as actively aerated columns. The authors presented the preliminary results obtained from two passively aerated pilot-scale field MBFs. The MBF design curves were developed using a series of 480 model simulations performed under a one-dimensional reactive transport model. 5 refs., 10 figs.

  1. An Analysis of Air Pollution in Makkah - a View Point of Source Identification

    Turki M. Habeebullah

    2013-07-01

    Full Text Available Makkah is one of the busiest cities in Saudi Arabia and remains busy all year around, especially during the season of Hajj and the month of Ramadan when millions of people visit this city. This emphasizes the importance of clean air and of understanding the sources of various air pollutants, which is vital for the management and advanced modeling of air pollution. This study intends to identify the major sources of air pollutants in Makkah, near the Holy Mosque (Al-Haram using a graphical approach. Air pollutants considered in this study are nitrogen oxides (NOx, nitrogen dioxide (NO2, nitric oxide (NO, carbon monoxide (CO, sulphur dioxide (SO2, ozone (O3 and particulate matter with aero-dynamic diameter of 10 um or less (PM10. Polar plots, time variation plots and correlation analysis are used to analyse the data and identify the major sources of emissions. Most of the pollutants demonstrate high concentrations during the morning traffic peak hours, suggesting road traffic as the main source of emission. The main sources of pollutant emissions identified in Makkahwere road traffic, re-suspended and windblown dust and sand particles. Further investigation on detailedsource apportionment is required, which is part of the ongoing project.

  2. 20cm VLA radio-continuum study of M31: Images and point source catalogues

    Galvin T.J.

    2012-01-01

    Full Text Available We present a series of new high-sensitivity and high-resolution radio-continuum images of M31 at λ=20 cm (ν=1.4 GHz. These new images were produced by merging archived 20 cm radio-continuum observations from the Very Large Array (VLA telescope. Images presented here are sensitive to rms=60 μJy and feature high angular resolution (<10’’. A complete sample of discrete radio sources have been catalogued and analyzed across 17 individual VLA projects. We identified a total of 864 unique discrete radio sources across the field of M31. One of the most prominent regions in M31 is the ring feature for which we estimated total integrated flux of 706 mJy at λ=20 cm. We compare here detected sources to those listed in Gelfand et al. (2004 at λ=92 cm and find 118 sources in common to both surveys. The majority (61% of these sources exhibit a spectral index of α <-0.6 indicating that their emission is predominantly non-thermal in nature, that is more typical for background objects.

  3. A Single Phase Doubly Grounded Semi-Z-Source Inverter for Photovoltaic (PV) Systems with Maximum Power Point Tracking (MPPT)

    Tofael Ahmed; Tey Kok Soon; Saad Mekhilef

    2014-01-01

    In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT) is proposed for photovoltaic (PV) systems. This proposed system utilizes a single-ended primary inductor (SEPIC) converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximu...

  4. A THEORETICAL ANALYSIS OF KEY POINTS WHEN CHOOSING OPEN SOURCE ERP SYSTEMS

    Fernando Gustavo Dos Santos Gripe

    2011-08-01

    Full Text Available The present work is aimed at presenting a theoretical analysis of the main features of Open Source ERP systems, herein identified as success technical factors, in order to contribute to the establishment of parameters to be used in decision-making processes when choosing a system which fulfills the organization´s needs. Initially, the life cycle of ERP systems is contextualized, highlighting the features of Open Source ERP systems. As a result, it was verified that, when carefully analyzed, these systems need further attention regarding issues of project continuity and maturity, structure, transparency, updating frequency, and support, all of which are inherent to the reality of this type of software. Nevertheless, advantages were observed in what concerns flexibility, costs, and non-discontinuity as benefits. The main goal is to broaden the discussion about the adoption of Open Source ERP systems.

  5. The 21 centimeter emission from the reionization epoch: extended and point source foregrounds

    Matteo, T D; Miniati, F; Matteo, Tiziana Di; Ciardi, Benedetta; Miniati, Francesco

    2004-01-01

    Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources. We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio halos and relics and free-free emission from the interstellar and intergalactic medium at the frequencies and angular scales relevant for the proposed 21cm tomography. In accord with previous findings, the brightness temperature fluctuations due to foreground sources are much larger than those from the primary 21cm signal at all scales. In particular, diffuse cluster radio emission, which has been previously neglected, provides the most significant foreground contamination. However, we show that the contribution to the angular fluctuations at scales \\theta > 1' is dominated by the spatial clustering of bright foreground sources. This excess can be remove...

  6. Clusters of Black Holes as Point-Like Gamma-ray Sources

    Belotsky, K. M.; Berkov, A. V.; Kirillov, A. A.; Rubin, S. G.

    2012-01-01

    The possibility of identifying some of Galactic gamma-ray sources as clusters of primordial black holes is discussed. The known scenarios of supermassive black hole formation indicate the multiple formation of lower-mass black holes. Our analysis demonstrates that due to Hawking evaporation the cluster of black holes with masses about $10^{15}$ g could be observed as a gamma-ray source. The total mass of typical cluster is $\\sim 10 M_\\odot$. Detailed calculations have been performed on the ba...

  7. A 95 GHz Class I Methanol Maser Survey Toward A Sample of GLIMPSE Point Sources Associated with BGPS Clumps

    Chen, Xi; He, Jin-Hua; Xu, Ye; Gan, Cong-Gui; Shen, Zhi-Qiang; An, Tao; Sun, Yan; Ju, Bing-Gang

    2012-01-01

    We report a survey with the Purple Mountain Observatory (PMO) 13.7-m radio telescope for class I methanol masers from the 95 GHz (8_0 - 7_1 A^+) transition. The 214 target sources were selected by combining information from both the Spitzer GLIMPSE and 1.1 mm BGPS survey catalogs. The observed sources satisfy both the GLIMPSE mid-IR criteria of [3.6]-[4.5]>1.3, [3.6]-[5.8]>2.5, [3.6]-[8.0]>2.5 and 8.0 um magnitude less than 10, and also have an associated 1.1 mm BGPS source. Class I methanol maser emission was detected in 63 sources, corresponding to a detection rate of 29% for this survey. For the majority of detections (43), this is the first identification of a class I methanol maser associated with these sources. We show that the intensity of the class I methanol maser emission is not closely related to mid-IR intensity or the colors of the GLIMPSE point sources, however, it is closely correlated with properties (mass and beam-averaged column density) of the BGPS sources. Comparison of measures of star fo...

  8. XID Cross-Association of ROSAT/Bright Source Catalog X-ray Sources with USNO A2 Optical Point Sources

    Rutledge, R E; Prince, T A; Lonsdale, C; Rutledge, Robert E.; Brunner, Robert J.; Prince, Thomas A.; Lonsdale, Carol

    2000-01-01

    We quantitatively cross-associate the 18811 ROSAT Bright Source Catalog (RASS/BSC) X-ray sources with optical sources in the USNO-A2 catalog, calculating the the probability of unique association (Pid) between each candidate within 75 arcsec of the X-ray source position, on the basis of optical magnitude and proximity. We present catalogs of RASS/BSC sources for which the probability of association is >98%, >90%, and >50%, which contain 2705, 5492, and 11301 unique USNO-A2 optical counterparts respectively down to the stated level of significance. We include in this catalog a list of objects in the SIMBAD database within 10 arcsec of the USNO position, as an aid to identification and source classification. The catalog is more useful than previous catalogs which either rely on plausibility arguments for association, or do not aid in selecting a counterpart between multiple off-band sources in the field. We find that a fraction ~65.8% of RASS/BSC sources have an identifiable optical counterpart, down to the mag...

  9. ENVIRONMENTAL EFFICIENCY, SEPARABILITY AND ABATEMENT COSTS OF NON-POINT SOURCE POLLUTION

    Wossink, Ada; Denaux, Zulal Sogutlu

    2002-01-01

    This paper presents a new framework for analyzing abatement costs of nonpoint-source pollution. Unlike previous studies, this framework treats production and pollution as non-separable and also recognizes that production inefficiency is a fundamental cause of pollution. The implications of this approach are illustrated using an empirical analysis for cotton producers.

  10. Analytical formulae to calculate the solid angle subtended at an arbitrarily positioned point source by an elliptical radiation detector

    In this article, we introduce a direct analytical mathematical method for calculating the solid angle, Ω, subtended at a point by closed elliptical contours. The solid angle is required in many areas of optical and nuclear physics to estimate the flux of particle beam of radiation and to determine the activity of a radioactive source. The validity of the derived analytical expressions was successfully confirmed by the comparison with some published data (Numerical Method)

  11. In vivo dosimetry HDR brachytherapy prostate with source CO-60: Results of measures in a point urethra

    In this study we present and analyze the results of the in vivo dosimetry made a point of urethra with a group of 30 patients treated with brachytherapy prostate high rate with Co-60 source. Taking into account the uncertainties, the results and integration, globally evaluate this system DIV. This DIV system, due to its ease of calibration and use, and provides a relatively simple integration way to avoid serious errors in administering treatment. (Author)

  12. The statistical distributed source boundary point method to calculate the acoustic radiation from the random vibrating body

    WANGXiufeng; CHENXinzhao; LIUZhao

    2003-01-01

    The statistical distributed source boundary point method (SDSBPM) put forward is applied to calculate the acoustic radiation from the random vibrating body. A detailed description of this method is presented. A test for the SDSBPM is carried out through the random vibrating sphere and the random vibrating cuboid. An experiment on the exterior acoustic radiation of a random vibrating simulation axial box of the lathe tool is performed in a semi-anechoic chamber.

  13. The Non-point Source Pollution Effects of Pesticides Based on the Survey of 340 Farmers in Chongqing City

    YU, Lianchao; GU, Limeng; Bi, Qian

    2015-01-01

    Using the survey data on 340 farmers in Chongqing City, this paper performs an empirical analysis of the factors influencing the non-point source pollution of pesticides. The results show that the older householders will apply more pesticides, which may be due to the weak physical strength and weak ability to accept the concept of advanced cultivation; the householders with high level of education will choose to use less pesticides; the pesticide application rate is negatively correlated with...

  14. Synoptic monitoring as an approach to discriminating between point and diffuse source contributions to zinc loads in mining impacted catchments

    Banks, V.J.; B. Palumbo-Roe

    2010-01-01

    One of the global legacies of industrialisation is the environmental impacts of historic 9 mineral exploitation. Recent national initiatives to manage the impacts on ground and 10 surface waters have driven the need to develop better techniques for assessing 11 understanding of the catchment-scale distribution and characterisation of the relative 12 contribution of point and diffuse contaminant sources. The benefits of a detailed, 13 multidisciplinary investigation are highlighted through a c...

  15. Search for correlations of the arrival directions of ultra-high energy cosmic rays with specific point source candidates

    A search has been made for correlations between the arrival directions of cosmic rays above 1019 eV and various classes of galactic and extragalactic point source candidates. The effects that the galactic and intergalactic magnetic fields would have on their arrival directions and times of flight have been considered. Although some statistical indications for directional correlations have been found, none is significant enough to give strong support to any specific model of the origin of high energy cosmic rays. (orig.)

  16. A Dirichlet-integral based dual-access collocation-kernel approach to point-source gravity-field modleing

    Rufty, Alan

    2006-01-01

    Problems in $\\mathbb{R}^3$ are addressed where the scalar potential of an associated vector field satisfies Laplace's equation in some unbounded external region and is to be approximated by unknown (point) sources contained in the complimentary subregion. Two specific field geometries are considered: $\\mathbb{R}^3$ half-space and the exterior of an $\\mathbb{R}^3$ sphere, which are the two standard settings for geophysical and geoexploration gravitational problems. For these geometries it is s...

  17. Farmers’ Willingness to Pay (WTP) for Reducing Agricultural Non-point Source Pollution: Based on the Empirical Analysis of 453 Farmers

    Bi, Qian; Wang, Huaiye; Zuo, Yongyan

    2014-01-01

    With the rapid development of modern agriculture, agricultural non-point source pollution becomes increasingly serious in China, improving farmers’ environmental protection consciousness plays a very important role in the reduction of agricultural non-point source pollution, and the WTP of Farmers for controlling agricultural non-point source pollution strongly reflects the strength of their environmental protection consciousness. Therefore, this investigation and study choose rural areas o...

  18. Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources

    R. Felber; A. Münger; A. Neftel; C. Ammann

    2015-01-01

    Methane (CH4) from ruminants contributes one-third of global agricultural greenhouse gas emissions. Eddy covariance (EC) technique has been extensively used at various flux sites to investigate carbon dioxide exchange of ecosystems. Since the development of fast CH4 analyzers, the instrumentation at many flux sites has been amended for these gases. However, the application of EC over pastures is challenging due to the spatially and temporally uneven distribution of CH4 point...

  19. Near-infrared spectroscopy of faint discrete X-ray point sources constituting the Galactic ridge X-ray emission

    Morihana, Kumiko; Tsujimoto, Masahiro; Dubath, Pierre; Yoshida, Tessei; Suzuki, Kensuke; Ebisawa, Ken

    2016-08-01

    The Galactic Ridge X-ray Emission (GRXE) is an apparently extended X-ray emission along the Galactic plane. The X-ray spectrum is characterized by a hard continuum with a strong Fe K emission feature in the 6-7 keV band. A substantial fraction (˜80%) of the GRXE in the Fe band was resolved into point sources by deep Chandra imaging observations; thus GRXE is mostly composed of dim Galactic X-ray point sources, at least in this energy band. To investigate the populations of these dim X-ray point sources, we carried out near-infrared (NIR) follow-up spectroscopic observations in two deep Chandra fields located in the Galactic plane at (l, b) = (0.1°, -1.4°) and (28.5°, 0.0°) using NTT/SofI and Subaru/MOIRCS. We obtained well-exposed NIR spectra from 65 objects and found that there are three main classes of Galactic sources based on the X-ray color and NIR spectral features: those having (A) hard X-ray spectra and NIR emission features such as H I (Brγ), He I, and He II (2 objects), (B) soft X-ray spectra and NIR absorption features such as H I, Na I, Ca I, and CO (46 objects), and (C) hard X-ray spectra and NIR absorption features such as H I, Na I, Ca I, and CO (17 objects). From these features, we argue that class A sources are cataclysmic variables (CVs), and class B sources are late-type stars with enhanced coronal activity, which is in agreement with current knowledge. Class C sources possibly belong to a new group of objects, which has been poorly studied so far. We argue that the candidate sources for class C are the binary systems hosting white dwarfs and late-type companions with very low accretion rates. It is likely that this newly recognized class of sources contribute to a non-negligible fraction of the GRXE, especially in the Fe K band.

  20. 1SXPS: A Deep Swift X-Ray Telescope Point Source Catalog with Light Curves and Spectra

    Evans, P. A.; Osborne, J. P.; Beardmore, A. P.; Page, K. L.; Willingale, R.; Mountford, C. J.; Pagani, C.; Burrows, D. N.; Kennea, J. A.; Perri, M.; Tagliaferri, G.; Gehrels, N.

    2013-01-01

    We present the 1SXPS (Swift-XRT point source) catalog of 151,524 X-ray point sources detected by the Swift-XRT in 8 yr of operation. The catalog covers 1905 sq deg distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of approximately 3 × 10(exp -13) erg cm(exp -2) s(exp -1) (0.3-10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of approximately 9 × 10(exp -14) erg cm(exp -2) s(exp -1) (0.3-10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of approximately 1.5 less sensitive. The median position error is 5.5 (90% confidence), including systematics. Our source detection method improves on that used in previous X-ray Telescope (XRT) catalogs and we report greater than 68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find approximately 30,000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales.

  1. 1SXPS: A DEEP SWIFT X-RAY TELESCOPE POINT SOURCE CATALOG WITH LIGHT CURVES AND SPECTRA

    We present the 1SXPS (Swift-XRT point source) catalog of 151,524 X-ray point sources detected by the Swift-XRT in 8 yr of operation. The catalog covers 1905 deg2 distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ∼3 × 10–13 erg cm–2 s–1 (0.3-10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ∼9 × 10–14 erg cm–2 s–1 (0.3-10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ∼1.5 less sensitive. The median position error is 5.''5 (90% confidence), including systematics. Our source detection method improves on that used in previous X-ray Telescope (XRT) catalogs and we report >68, 000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ∼30, 000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales

  2. A Spatial and Temporal Assessment of Non-Point Groundwater Pollution Sources, Tutuila Island, American Samoa

    Shuler, C. K.; El-Kadi, A. I.; Dulaiova, H.; Glenn, C. R.; Fackrell, J.

    2015-12-01

    The quality of municipal groundwater supplies on Tutuila, the main island in American Samoa, is currently in question. A high vulnerability for contamination from surface activities has been recognized, and there exists a strong need to clearly identify anthropogenic sources of pollution and quantify their influence on the aquifer. This study examines spatial relationships and time series measurements of nutrients and other tracers to identify predominant pollution sources and determine the water quality impacts of the island's diverse land uses. Elevated groundwater nitrate concentrations are correlated with areas of human development, however, the mixture of residential and agricultural land use in this unique village based agrarian setting makes specific source identification difficult using traditional geospatial analysis. Spatial variation in anthropogenic impact was assessed by linking NO3- concentrations and δ15N(NO3) from an extensive groundwater survey to land-use types within well capture zones and groundwater flow-paths developed with MODFLOW, a numerical groundwater model. Land use types were obtained from high-resolution GIS data and compared to water quality results with multiple-regression analysis to quantify the impact that different land uses have on water quality. In addition, historical water quality data and new analyses of δD and δ18O in precipitation, groundwater, and mountain-front recharge waters were used to constrain the sources and mechanisms of contamination. Our analyses indicate that groundwater nutrient levels on Tutuila are controlled primarily by residential, not agricultural activity. Also a lack of temporal variation suggests that episodic pollution events are limited to individual water sources as opposed to the entire aquifer. These results are not only valuable for water quality management on Tutuila, but also provide insight into the sustainability of groundwater supplies on other islands with similar hydrogeology and land

  3. Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data

    Aartsen, M G; Adams, J; Aguilar, J A; Ahlers, M; Ahrens, M; Altmann, D; Anderson, T; Arguelles, C; Arlen, T C; Auffenberg, J; Bai, X; Barwick, S W; Baum, V; Beatty, J J; Tjus, J Becker; Becker, K -H; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bos, F; Bose, D; Böser, S; Botner, O; Brayeur, L; Bretz, H -P; Brown, A M; Casey, J; Casier, M; Cheung, E; Chirkin, D; Christov, A; Christy, B; Clark, K; Classen, L; Clevermann, F; Coenders, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; De Ridder, S; Desiati, P; de Vries, K D; de With, M; DeYoung, T; Díaz-Vélez, J C; Dunkman, M; Eagan, R; Eberhardt, B; Eichmann, B; Eisch, J; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Felde, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Frantzen, K; Fuchs, T; Gaisser, T K; Gaior, R; Gallagher, J; Gerhardt, L; Gier, D; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Goodman, J A; Góra, D; Grant, D; Gretskov, P; Groh, J C; Groß, A; Ha, C; Haack, C; Ismail, A Haj; Hallen, P; Hallgren, A; Halzen, F; Hanson, K; Hebecker, D; Heereman, D; Heinen, D; Helbing, K; Hellauer, R; Hellwig, D; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huang, F; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Jagielski, K; Japaridze, G S; Jero, K; Jlelati, O; Jurkovic, M; Kaminsky, B; Kappes, A; Karg, T; Karle, A; Kauer, M; Kelley, J L; Kheirandish, A; Kiryluk, J; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Koob, A; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Kriesten, A; Krings, K; Kroll, G; Kroll, M; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Larsen, D T; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Leute, J; Lünemann, J; Madsen, J; Maggi, G; Maruyama, R; Mase, K; Matis, H S; Maunu, R; McNally, F; Meagher, K; Medici, M; Meli, A; Meures, T; Miarecki, S; Middell, E; Middlemas, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Paul, L; Penek, Ö; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Pütz, J; Quinnan, M; Rädel, L; Rameez, M; Rawlins, K; Redl, P; Rees, I; Reimann, R; Relich, M; Resconi, E; Rhode, W; Richman, M; Riedel, B; Robertson, S; Rodrigues, J P; Rongen, M; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Sander, H -G; Sandroos, J; Santander, M; Sarkar, S; Schatto, K; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Sestayo, Y; Seunarine, S; Shanidze, R; Smith, M W E; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stanisha, N A; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Strotjohann, N L; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Terliuk, A; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Tosi, D; Tselengidou, M; Unger, E; Usner, M; Vallecorsa, S; van Eijndhoven, N; Vandenbroucke, J; van Santen, J; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Wallraff, M; Weaver, Ch; Wellons, M; Wendt, C; Westerhoff, S; Whelan, B J; Whitehorn, N; Wichary, C; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zoll, M

    2014-01-01

    Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of $60\\,\\mathrm{TeV}$ to the $\\mathrm{PeV}$-scale. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years of IceCube data, taken between 2008 and 2011. The first method is an autocorrelation test, applied separately to the northern and southern sky. The second method is a multipole analysis, which expands the measured data in the northern hemisphere into spherical harmonics and uses the resulting expansion coefficients to separa...

  4. Approximating model for multilayer gamma-ray buildup factors by transmission matrix method: Application to point isotropic source geometry

    An approximating formula recently proposed by the authors for gamma-ray buildup factors of multilayered shields is applied to point isotropic source problems. The formula, which is formulated in vector form with a four-group approximation, handles the gamma-ray energy spectrum directly and uses the transmission and albedo matrices to take gamma-ray transmission and backscattering effects into consideration. The gamma-ray transmission and back-scattering probabilities through a 1-mean-free-path- (mfp-) thick shell depend on the shell curvature. This phenomenon plays an important role in simulating the gamma-ray buildup factor in point isotropic source geometry. In this model, the dependence is described by simplified expressions. The feasibility of the formula for systematically describing the point isotropic buildup factors was tested by using buildup factors calculated by the Monte Carlo method as reference data. The materials used in the tests were water, iron, and lead, and the source energies assumed were 0.5, 1, and 10 MeV. Through the tests, the method was found to reproduce the reference data of double-layered shields of these materials very well. With the same parameters, the buildup factors of three-layered shields are also reproducible. Buildup factors computed with two different group structures were examined to test the adequacy of the energy group structure adopted. The group structure previously adopted was found to be adequate in the energy range of 0.5 to 10 MeV

  5. Organochlorine pesticides and metabolites in young leaves of Mangifera indica from sites near a point source in Coast region, Tanzania.

    Marco, John A Mahugija; Kishimba, Michael A

    2007-06-01

    Young leaves of Mangifera indica (mango tree) from nine sites were used as bioindicators of local atmospheric contamination by organochlorine pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. Sample extracts were analysed by GC-ECD and GC-MS. The concentrations ranged 2.7-649 ng g(-1)p,p'-DDT, below detection limit (bdl)-290 ng g(-1) o,p'-DDT, 0.4-13 ng g(-1) p,p'-DDE, bdl to 4 ng g(-1) o,p'-DDE, 1-231 ng g(-1) p,p'-DDD and 0.5-55 ng g(-1) o,p'-DDD. The concentrations of other compounds were up to 3.9 ng g(-1) pentachloroanisole, 1.3 ng g(-1) alpha-HCH, 12 ng g(-1) beta-HCH and 2 ng g(-1) gamma-HCH, on fresh weight basis. The compounds p,p'-DDT, p,p'-DDE, p,p'DDD and o,p'-DDD were found in 100% of the samples, while pentachloroanisole, o,p'-DDT and o,p'-DDE were detected in 78%, 56% and 67% of the samples, respectively. The low DDE/DDT ratios (0.01-0.20) in all samples indicate recent input of significantly non-degraded DDT from the point source. The low alpha-/gamma-HCH ratios (contaminants from a point source. PMID:17395245

  6. A Northern Sky Survey for Point-Like Sources of EeV Neutral Particles with the Telescope Array Experiment

    Abbasi, R U; Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Chae, M J; Cheon, B G; Chiba, J; Chikawa, M; Cho, W R; Fujii, T; Fukushima, M; Goto, T; Hanlon, W; Hayashi, Y; Hayashida, N; Hibino, K; Honda, K; Ikeda, D; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kawata, K; Kido, E; Kim, H B; Kim, J H; Kitamura, S; Kitamura, Y; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, K; Martens, K; Matsuda, T; Matsuyama, T; Matthews, J N; Minamino, M; Mukai, K; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nonaka, T; Nozato, A; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Suzawa, T; Takamura, M; Takeda, M; Takeishi, R; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Uchihori, Y; Udo, S; Urban, F; Vasiloff, G; Wong, T; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yashiro, K; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2014-01-01

    We report on the search for steady point-like sources of neutral particles around 10$^{18}$ eV between 2008 May and 2013 May with the surface detector of the Telescope Array experiment. We found overall no significant point-like excess above 0.5 EeV in the northern sky. Subsequently, we also searched for coincidence with the Fermi bright Galactic sources. No significant coincidence was found within the statistical error. Hence, we set an upper limit at the 95% confidence level on the neutron flux that corresponds to an averaged flux of 0.07 km$^{-2}$ yr$^{-1}$ above 1 EeV in the northern sky. This is the most stringent flux upper limit in a northern sky survey assuming point-like sources. The upper limit at the 95% confidence level on the neutron flux from Cygnus X-3 is also set to 0.2 km$^{-2}$ yr$^{-1}$ above 0.5 EeV. This is an order of magnitude smaller than previous flux measurements.

  7. Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste

    The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta's sediment surface had MMHg concentrations ranging from 7.5 to 31.5 ng/g, and the top 1 cm of sediment directly under the mats had two times greater MMHg concentrations compared to adjacent locations without algal covering. Spatial trends in resident biota reflect enhanced MMHg uptake at the delta compared to other bay locations. Eighteen sediment cores, 1 to 2 m deep, collected from the 1.2 km2 delta provide an estimate of a total mercury (Hg) inventory of 2500 ± 500 kg. Sediment Hg concentrations ranged from pre-mining background conditions of approximately 0.1 μg/g to a post-mining maximum of 5 μg/g. Sediment accumulation rates were determined from three sediment cores using measured differences of 137Cs activity. We estimate a pre-mining Hg accumulation of less than 20 kg/yr, and a period of maximum Hg accumulation in the 1970s and 1980s with loading rates greater than 50 kg/yr, corresponding to the failure of a tailings dam at the mine site. At the time of sampling (2003) over 40 kg/yr of Hg was still accumulating at the delta, indicating limited recovery. We attribute observed spatial evolution of elevated Hg levels to ongoing inputs and sediment re-working, and estimate the inventory of the anthropogenic fraction of total Hg to be at least 1500 ± 300 kg. We suggest ongoing sediment inputs and methylation at the deltaic surface support enhanced mercury levels for resident biota and transfer to higher trophic levels throughout the Bay.

  8. FIRST SEARCH FOR POINT SOURCES OF HIGH-ENERGY COSMIC NEUTRINOS WITH THE ANTARES NEUTRINO TELESCOPE

    Adrian-Martinez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigacio per a la Gestio Integrada de les Zones Costaneres (IGIC), Universitat Politecnica de Valencia, C/Paranimf 1, 46730 Gandia (Spain); Aguilar, J. A.; Bigongiari, C. [IFIC-Instituto de Fisica Corpuscular, Edificios Investigacion de Paterna, CSIC, Universitat de Valencia, Apdo. de Correos 22085, 46071 Valencia (Spain); Al Samarai, I.; Aubert, J.-J.; Bertin, V. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Albert, A. [GRPHE-Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568-68008 Colmar (France); Andre, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposicio, 08800 Vilanova i la Geltru, Barcelona (Spain); Anghinolfi, M. [INFN-Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Anton, G. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Anvar, S. [Direction des Sciences de la Matiere, Institut de recherche sur les lois fondamentales de l' Univers, Service d' Electronique des Detecteurs et d' Informatique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Assis Jesus, A. C.; Astraatmadja, T.; Bogazzi, C. [Nikhef, Science Park, Amsterdam (Netherlands); Baret, B. [APC-Laboratoire AstroParticule et Cosmologie, UMR 7164 (CNRS, Universite Paris 7 Diderot, CEA, Observatoire de Paris) 10, rue Alice Domon et Leonie Duquet 75205 Paris Cedex 13 (France); Basa, S. [LAM-Laboratoire d' Astrophysique de Marseille, Pole de l' Etoile Site de Chateau-Gombert, rue Frederic Joliot-Curie 38, 13388 Marseille Cedex 13 (France); Biagi, S. [INFN-Sezione di Bologna, Viale C. Berti-Pichat 6/2, 40127 Bologna (Italy); Bigi, A. [INFN-Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); and others

    2011-12-10

    Results are presented of a search for cosmic sources of high-energy neutrinos with the ANTARES neutrino telescope. The data were collected during 2007 and 2008 using detector configurations containing between 5 and 12 detection lines. The integrated live time of the analyzed data is 304 days. Muon tracks are reconstructed using a likelihood-based algorithm. Studies of the detector timing indicate a median angular resolution of 0.5 {+-} 0.1 deg. The neutrino flux sensitivity is 7.5 Multiplication-Sign 10{sup -8}(E{sub {nu}}/ GeV){sup -2} GeV{sup -1} s{sup -1} cm{sup -2} for the part of the sky that is always visible ({delta} < -48 deg), which is better than limits obtained by previous experiments. No cosmic neutrino sources have been observed.

  9. FIRST SEARCH FOR POINT SOURCES OF HIGH-ENERGY COSMIC NEUTRINOS WITH THE ANTARES NEUTRINO TELESCOPE

    Results are presented of a search for cosmic sources of high-energy neutrinos with the ANTARES neutrino telescope. The data were collected during 2007 and 2008 using detector configurations containing between 5 and 12 detection lines. The integrated live time of the analyzed data is 304 days. Muon tracks are reconstructed using a likelihood-based algorithm. Studies of the detector timing indicate a median angular resolution of 0.5 ± 0.1 deg. The neutrino flux sensitivity is 7.5 × 10–8(Eν/ GeV)–2 GeV–1 s–1 cm–2 for the part of the sky that is always visible (δ < –48 deg), which is better than limits obtained by previous experiments. No cosmic neutrino sources have been observed.

  10. A rotating modulation imager for locating mid-range point sources

    Rotating modulation collimators (RMC) are relatively simple indirect imaging devices that have proven useful in gamma ray astronomy (far field) and have more recently been studied for medical imaging (very near field). At the University of Michigan a RMC has been built to study the performance for homeland security applications. This research highlights the imaging performance of this system and focuses on three distinct regions in the RMC field of view that can impact the search for hidden sources. These regions are a blind zone around the axis of rotation, a two mask image zone that extends from the blind zone to the edge of the field of view, and a single mask image zone that occurs when sources fall outside the field of view of both masks. By considering the extent and impact of these zones, the size of the two mask region can be optimized for the best system performance.

  11. The 21 centimeter emission from the reionization epoch: extended and point source foregrounds

    Di Matteo, Tiziana; Ciardi, Benedetta; Miniati, Francesco

    2004-01-01

    Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources. We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio halos and relics and free-free emission from the interstellar and intergalactic medium at the frequencies and angular scales relevant f...

  12. Diverse origins of Arctic and Subarctic methane point source emissions identified with multiply-substituted isotopologues

    Douglas, P. M. J.; Stolper, D. A.; Smith, D. A.; Anthony, K. M. Walter; Paull, C. K.; Dallimore, S.; Wik, M.; Crill, P. M.; Winterdahl, M; Eiler, J. M.; Sessions, A.L.

    2016-01-01

    Methane is a potent greenhouse gas, and there are concerns that its natural emissions from the Arctic could act as a substantial positive feedback to anthropogenic global warming. Determining the sources of methane emissions and the biogeochemical processes controlling them is important for understanding present and future Arctic contributions to atmospheric methane budgets. Here we apply measurements of multiply-substituted isotopologues, or clumped isotopes, of methane as a new tool to iden...

  13. Stochastic Analysis of Non Point Source Loading of Fecal Bacteria in a Shallow Heterogeneous Aquifer

    Cook, S. J.; Li, X.; Atwill, R.; Packman, A. I.; Harter, T.

    2011-12-01

    Manure and wastewater irrigation (MWI) presents a microbiological risk to shallow groundwater quality. Particularly vulnerable are domestic wells in rural areas where treatment systems may be limited or unreliable. However, despite multiple and persistent sources of fecal contamination, cross sectional monitoring of fecal bacteria in groundwater indicates a high degree of variability in both prevalence and measured concentrations. Apparently random variation occurs both between wells and samples at individual wells. In contrast, deliberate longitudinal studies of MWIs, particularly in the laboratory, tend to exhibit relatively smooth breakthrough curves consistent with colloid filtration theory. To better characterize potential sources of variability in observed field data, a 3D stochastic groundwater modeling approach representative of irrigation applications to vulnerable alluvial aquifers was developed. Heterogeniety is assessed by incorporating multiple loading functions and hydrostratigraphic representations of a heterogeneous alluvial aquifer. Simulations indicate that irrigation water breakthroughs to wells are generally limited to shallow depths, suggesting limited risk to domestic wells screened several tens of meters below the water table. Whilst the presence of aquifer heterogeneity significantly extends the transport distance and tailing of breakthrough curves, owing to macro-dispersion and in-well mixing, simulated breakthrough curves are relatively smooth and consistent with observed longitudinal studies. This suggests that the highly erratic and variable nature of microorganism detection may be due to highly transient processes, including but not limited to spatio-temporal variations in source variability and limitations in infrequent monitoring programs to properly determine variability.

  14. Discrete-continuous reaction-diffusion model with mobile point-like sources and sinks.

    Kondrat, Svyatoslav; Zimmermann, Olav; Wiechert, Wolfgang; von Lieres, Eric

    2016-01-01

    In many applications in soft and biological physics, there are multiple time and length scales involved but often with a distinct separation between them. For instance, in enzyme kinetics, enzymes are relatively large, move slowly and their copy numbers are typically small, while the metabolites (being transformed by these enzymes) are often present in abundance, are small in size and diffuse fast. It seems thus natural to apply different techniques to different time and length levels and couple them. Here we explore this possibility by constructing a stochastic-deterministic discrete-continuous reaction-diffusion model with mobile sources and sinks. Such an approach allows in particular to separate different sources of stochasticity. We demonstrate its application by modelling enzyme-catalysed reactions with freely diffusing enzymes and a heterogeneous source of metabolites. Our calculations suggest that using a higher amount of less active enzymes, as compared to fewer more active enzymes, reduces the metabolite pool size and correspondingly the lag time, giving rise to a faster response to external stimuli. The methodology presented can be extended to more complex systems and offers exciting possibilities for studying problems where spatial heterogeneities, stochasticity or discreteness play a role. PMID:26830760

  15. Reconstruction algorithm for point source neutron imaging through finite thickness scintillator

    A new inversion algorithm based on the maximum entropy method (MEM) is proposed to remove unwanted effects in fast neutron imaging which result from an uncollimated source interacting with a finitely thick scintillator. The algorithm takes as an input the image from the thick scintillator (TS) and the radiography setup geometry. The algorithm then outputs a restored image which appears as if taken with an infinitesimally thin scintillator (ITS). The inversion is accomplished by numerically generating a probabilistic model relating the ITS image to the TS image and then inverting this model on the TS image through MEM. Algorithm details as well as numerical results using MCNP simulated images are presented. This reconstruction technique can reduce the exposure time or the required source intensity without undesirable object blurring on the image by allowing the use of both thicker scintillators with higher efficiencies and closer source-to-detector distances to maximize incident radiation flux. The technique should also be applicable to high energy gamma or x-ray radiography using thick scintillators.

  16. SEARCHES FOR POINT-LIKE AND EXTENDED NEUTRINO SOURCES CLOSE TO THE GALACTIC CENTER USING THE ANTARES NEUTRINO TELESCOPE

    A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. = –46.°8 and decl. = –64.°9 and corresponds to a 2.2σ background fluctuation. In addition, upper limits on the flux normalization of an E –2 muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close to the Galactic Center in the recently reported neutrino sample of the IceCube telescope, a search for point sources in a broad region around this accumulation has been carried out. No indication of a neutrino signal has been found in the ANTARES data and upper limits on the flux normalization of an E –2 energy spectrum of neutrinos from point sources in that region have been set. The 90% confidence level upper limits on the muon neutrino flux normalization vary between 3.5 and 5.1 × 10–8 GeV cm–2 s–1, depending on the exact location of the source

  17. SEARCHES FOR POINT-LIKE AND EXTENDED NEUTRINO SOURCES CLOSE TO THE GALACTIC CENTER USING THE ANTARES NEUTRINO TELESCOPE

    Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC) - Universitat Politècnica de València. C/Paranimf 1, E-46730 Gandia (Spain); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568, F-68008 Colmar (France); André, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, E-08800 Vilanova i la Geltrú, Barcelona (Spain); Anghinolfi, M. [INFN - Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Anton, G. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Aubert, J.-J.; Bertin, V.; Brunner, J.; Busto, J. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Baret, B. [APC, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, F-75205 Paris (France); Barrios-Martí, J. [IFIC - Instituto de Física Corpuscular, Edificios Investigación de Paterna, CSIC - Universitat de València, Apdo. de Correos 22085, E-46071 Valencia (Spain); Basa, S. [LAM - Laboratoire d' Astrophysique de Marseille, Pôle de l' Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, F-13388 Marseille Cedex 13 (France); Biagi, S. [INFN - Sezione di Bologna, Viale Berti-Pichat 6/2, I-40127 Bologna (Italy); Bogazzi, C.; Bormuth, R.; Bouwhuis, M. C.; Bruijn, R. [Nikhef, Science Park, Amsterdam (Netherlands); Capone, A. [INFN -Sezione di Roma, P.le Aldo Moro 2, I-00185 Roma (Italy); and others

    2014-05-01

    A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. = –46.°8 and decl. = –64.°9 and corresponds to a 2.2σ background fluctuation. In addition, upper limits on the flux normalization of an E {sup –2} muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close to the Galactic Center in the recently reported neutrino sample of the IceCube telescope, a search for point sources in a broad region around this accumulation has been carried out. No indication of a neutrino signal has been found in the ANTARES data and upper limits on the flux normalization of an E {sup –2} energy spectrum of neutrinos from point sources in that region have been set. The 90% confidence level upper limits on the muon neutrino flux normalization vary between 3.5 and 5.1 × 10{sup –8} GeV cm{sup –2} s{sup –1}, depending on the exact location of the source.

  18. Generation of phase - matched coherent point source in plasma media by propagated X-ray laser seeded beam

    Pikuz, T.; Faenov, A.; Magnitskiy, S.; Nagorskiy, N.; Tanaka, M.; Ishino, M.; Nishikino, M.; Kando, M.; Kato, Y.; Kawachi, T.

    2016-03-01

    There is a significant interest in developing the coherent table-top X-ray lasers. Advent of plasma-based transient collisional excitation x-ray laser and particular, injection of coherent seeded beam, especially high-order harmonics, has tremendously improved the spatial coherence of such lasers, what allowed them to be the same widely used as synchrotron sources. Here we report experimental founding of unknown interference structure in a spatial profile of the output beam of the two-stage plasma X-ray laser. That allowed us experimental and theoretical discovering a new phenomenon consisted in a generation of phase-matched coherent point source in a laser plasma media by propagated X-ray laser seeded beam. This phenomenon could extend the applications of such x-ray lasers. For explanation of the observed phenomenon a new method of solving the standard system of Maxwell-Bloch equations has been developed. It was found that the interference pattern in the output laser beam was formed due to an emergence of phase-matched coherent virtual point source in the XRL amplifier and could be treated as the first observation of mirage phenomenon, analogous to the optical mirage, but in X-rays. The obtained results bring new comprehension into the physical nature of amplification of X-ray radiation in laser-induced plasma amplifiers and opening new opportunities for X-ray interferometry, holography and other applications, which requiring multiple rigidly phased sources of coherent radiation.

  19. Location and release time identification of pollution point source in river networks based on the Backward Probability Method.

    Ghane, Alireza; Mazaheri, Mehdi; Mohammad Vali Samani, Jamal

    2016-09-15

    The pollution of rivers due to accidental spills is a major threat to environment and human health. To protect river systems from accidental spills, it is essential to introduce a reliable tool for identification process. Backward Probability Method (BPM) is one of the most recommended tools that is able to introduce information related to the prior location and the release time of the pollution. This method was originally developed and employed in groundwater pollution source identification problems. One of the objectives of this study is to apply this method in identifying the pollution source location and release time in surface waters, mainly in rivers. To accomplish this task, a numerical model is developed based on the adjoint analysis. Then the developed model is verified using analytical solution and some real data. The second objective of this study is to extend the method to pollution source identification in river networks. In this regard, a hypothetical test case is considered. In the later simulations, all of the suspected points are identified, using only one backward simulation. The results demonstrated that all suspected points, determined by the BPM could be a possible pollution source. The proposed approach is accurate and computationally efficient and does not need any simplification in river geometry and flow. Due to this simplicity, it is highly recommended for practical purposes. PMID:27219462

  20. Source to point of use drinking water changes and knowledge, attitude and practices in Katsina State, Northern Nigeria

    Onabolu, B.; Jimoh, O. D.; Igboro, S. B.; Sridhar, M. K. C.; Onyilo, G.; Gege, A.; Ilya, R.

    In many Sub-Saharan countries such as Nigeria, inadequate access to safe drinking water is a serious problem with 37% in the region and 58% of rural Nigeria using unimproved sources. The global challenge to measuring household water quality as a determinant of safety is further compounded in Nigeria by the possibility of deterioration from source to point of use. This is associated with the use of decentralised water supply systems in rural areas which are not fully reticulated to the household taps, creating a need for an integrated water quality monitoring system. As an initial step towards establishing the system in the north west and north central zones of Nigeria, The Katsina State Rural Water and Sanitation Agency, responsible for ensuring access to safe water and adequate sanitation to about 6 million people carried out a three pronged study with the support of UNICEF Nigeria. Part 1 was an assessment of the legislative and policy framework, institutional arrangements and capacity for drinking water quality monitoring through desk top reviews and Key Informant Interviews (KII) to ascertain the institutional capacity requirements for developing the water quality monitoring system. Part II was a water quality study in 700 households of 23 communities in four local government areas. The objectives were to assess the safety of drinking water, compare the safety at source and household level and assess the possible contributory role of end users’ Knowledge Attitudes and Practices. These were achieved through water analysis, household water quality tracking, KII and questionnaires. Part III was the production of a visual documentary as an advocacy tool to increase awareness of the policy makers of the linkages between source management, treatment and end user water quality. The results indicate that except for pH, conductivity and manganese, the improved water sources were safe at source. However there was a deterioration in water quality between source and

  1. Investigating the effects of point source and nonpoint source pollution on the water quality of the East River (Dongjiang) in South China

    Wu, Yiping; Chen, Ji

    2013-01-01

    Understanding the physical processes of point source (PS) and nonpoint source (NPS) pollution is critical to evaluate river water quality and identify major pollutant sources in a watershed. In this study, we used the physically-based hydrological/water quality model, Soil and Water Assessment Tool, to investigate the influence of PS and NPS pollution on the water quality of the East River (Dongjiang in Chinese) in southern China. Our results indicate that NPS pollution was the dominant contribution (>94%) to nutrient loads except for mineral phosphorus (50%). A comprehensive Water Quality Index (WQI) computed using eight key water quality variables demonstrates that water quality is better upstream than downstream despite the higher level of ammonium nitrogen found in upstream waters. Also, the temporal (seasonal) and spatial distributions of nutrient loads clearly indicate the critical time period (from late dry season to early wet season) and pollution source areas within the basin (middle and downstream agricultural lands), which resource managers can use to accomplish substantial reduction of NPS pollutant loadings. Overall, this study helps our understanding of the relationship between human activities and pollutant loads and further contributes to decision support for local watershed managers to protect water quality in this region. In particular, the methods presented such as integrating WQI with watershed modeling and identifying the critical time period and pollutions source areas can be valuable for other researchers worldwide.

  2. Energy demand modelling: pointing out alternative energy sources. The example of industry in OECD countries

    This thesis studies energy demand and alternative energy sources in OECD countries. In the first part, the principle models usually used for energy demand modelling. In the second part, the author studies the flexible functional forms (translog, generalized Leontief, generalized quadratic, Fourier) to obtain an estimation of the production function. In the third part, several examples are given, chosen in seven countries (Usa, Japan, Federal Republic of Germany, France, United Kingdom, Italy, Canada). Energy systems analysis in these countries, can help to choose models and gives informations on alternative energies. 246 refs., 24 figs., 27 tabs

  3. Millimeter Transient Point Sources in the SPTpol 100 Square Degree Survey

    Whitehorn, N; Ade, P A R; Austermann, J E; Beall, J A; Bender, A N; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Chiang, H C; Cho, H-M; Citron, R; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; Everett, W; Gallicchio, J; George, E M; Gilbert, A; Halverson, N W; Harrington, N; Henning, J W; Hilton, G C; Holder, G P; Holzapfel, W L; Hoover, S; Hou, Z; Hrubes, J D; Huang, N; Hubmayr, J; Irwin, K D; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Li, D; McMahon, J J; Meyer, S S; Mocanu, L; Nibarger, J P; Novosad, V; Padin, S; Pryke, C; Reichardt, C L; Ruhl, J E; Saliwanchik, B R; Sayre, J T; Schaffer, K K; Smecher, G; Stark, A A; Story, K T; Tucker, C; Vanderlinde, K; Vieira, J D; Wang, G; Yefremenko, V

    2016-01-01

    The millimeter transient sky is largely unexplored, with measurements limited to follow-up of objects detected at other wavelengths. High-angular-resolution telescopes designed for measurement of the cosmic microwave background offer the possibility to discover new, unknown transient sources in this band, particularly the afterglows of unobserved gamma-ray bursts. Here we use the 10-meter millimeter-wave South Pole Telescope, designed for the primary purpose of observing the cosmic microwave background at arcminute and larger angular scales, to conduct a search for such objects. During the 2012-2013 season, the telescope was used to continuously observe a 100 square degree patch of sky centered at RA 23h30m and declination -55 degrees using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz. These 6000 hours of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level. One candidate object was observed with propertie...

  4. Millimeter Transient Point Sources in the SPTpol 100 Square Degree Survey

    Whitehorn, N.; et al.

    2016-04-12

    The millimeter transient sky is largely unexplored, with measurements limited to follow-up of objects detected at other wavelengths. High-angular-resolution telescopes designed for measurement of the cosmic microwave background offer the possibility to discover new, unknown transient sources in this band, particularly the afterglows of unobserved gamma-ray bursts. Here we use the 10-meter millimeter-wave South Pole Telescope, designed for the primary purpose of observing the cosmic microwave background at arcminute and larger angular scales, to conduct a search for such objects. During the 2012-2013 season, the telescope was used to continuously observe a 100 square degree patch of sky centered at RA $23^h 30^m$ and declination -55 degrees using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz. These 6000 hours of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level. One candidate object was observed with properties broadly consistent with a gamma-ray burst afterglow, but at a statistical significance too low (p=0.01) to confirm detection.

  5. Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

    Tohme, Michel S; Qi Jinyi [Department of Biomedical Engineering, University of California, Davis, CA 95616 (United States)], E-mail: qi@ucdavis.edu

    2009-06-21

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 x 3 line phantom, an ultra-micro resolution phantom and a {sup 22}Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  6. Iterative Image Reconstruction for Positron Emission Tomography Based on Detector Response Function Estimated from Point Source Measurements

    Tohme, Michel S.; Qi, Jinyi

    2009-01-01

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can be easily applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2-D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3-by-3 line phantom, an ultra-micro resolution phantom, and a 22Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  7. Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

    Tohme, Michel S.; Qi, Jinyi

    2009-06-01

    The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 × 3 line phantom, an ultra-micro resolution phantom and a 22Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

  8. A Dirichlet-integral based dual-access collocation-kernel approach to point-source gravity-field modleing

    Rufty, A

    2006-01-01

    Problems in $\\mathbb{R}^3$ are addressed where the scalar potential of an associated vector field satisfies Laplace's equation in some unbounded external region and is to be approximated by unknown (point) sources contained in the complimentary subregion. Two specific field geometries are considered: $\\mathbb{R}^3$ half-space and the exterior of an $\\mathbb{R}^3$ sphere, which are the two standard settings for geophysical and geoexploration gravitational problems. For these geometries it is shown that a new type of kernel space exists, which is labeled a Dirichlet-integral dual-access collocation-kernel space (DIDACKS) and that is well suited for many applications. The DIDACKS examples studied are related to reproducing kernel Hilbert spaces and they have a replicating kernel (as opposed to a reproducing kernel) that has the ubiquitous form of the inverse of the distance between a field point and a corresponding source point. Underpinning this approach are three basic mathematical relationships of general int...

  9. Effects of point source atmospheric pollution on boreal forest vegetation of northwestern Siberia

    Atmospheric pollution from the Noril'sk Mining-Metallurgical Complex, in the form of heavy metals and sulfur components, has resulted in damage to plant communities in the area. Vegetation on over 550,000 ha has been detrimentally affected by the pollution fallout, primarily sulfur dioxide. Forests (mainly Larix sibirica) and most lichens have been killed within a 300,000-ha zone around Noril'sk and extending about 50 km to the south and southeast. Less severe damage to lichens and vascular plants extends 170 km to the south and 80 km to the east of the pollution source consistent with prevailing winds during the period of plant growth. Terricolous lichens are particularly vulnerable to the pollution products and among vascular plants Larix gmelinii, Picea obovata, Ledum palustre, Calamagrostis sp., and Salix lanata show least resistance

  10. A bright point source of ultrashort hard x-rays from laser bioplasmas

    Krishnamurthy, M; Lad, Amit D; Ahmad, Saima; Narayanan, V; Rajeev, R; Kundu, M; Kumar, G Ravindra; Ray, Krishanu

    2010-01-01

    Micro and nano structures scatter light and amplify local electric fields very effectively. Energy incident as intense ultrashort laser pulses can be converted to x-rays and hot electrons more efficiently with a substrate that suitably modifies the local fields. Here we demonstrate that coating a plain glass surface with a few micron thick layer of an ubiquitous microbe, {\\it Escherichia coli}, catapults the brightness of hard x-ray bremsstrahlung emission (up to 300 keV) by more than two orders of magnitude at an incident laser intensity of 10$^{16}$ W cm$^{-2}$. This increased yield is attributed to the local enhancement of electric fields around individual {\\it E. coli} cells and is reproduced by detailed particle-in-cell (PIC) simulations. This combination of laser plasmas and biological targets can lead to turnkey, multi-kilohertz and environmentally safe sources of hard x-rays.

  11. The intraplate Mw 7 Machaze earthquake in Mozambique: Improved point source model, stress drop, and geodynamic implications

    Attanayake, Januka; Fonseca, João F. B. D.

    2016-05-01

    The February 22nd 2006 Mw = 7 Machaze earthquake is one of the largest, if not the largest, earthquakes reported since 1900 within Continental Africa. This large continental intraplate event has important implications to our understanding of tectonics and strong ground motion prediction locally and in the global context. Thus, accurate estimates of source parameters of this earthquake are important. In this study, we inverted the complete azimuthally distributed high frequency (0.05-2 Hz) P waveform dataset available for a best-fitting point source model and obtained stress drop estimates assuming different theoretical rupture models from spectral fitting. Our best-fitting point source model confirms steep normal faulting, has strike = 173° (309°), dip = 73° (23°), rake = -72° (-132°), and shows a 12%-4% improvement in waveform fit compared to previous models, which translates into an error minimization. We attribute this improvement to higher order reverberations near the source region that we took in to account and the excellent azimuthal coverage of the dataset. Preferred stress drop estimates assuming a rupture velocity = 0.9 x shear wave velocity (Vs) are between 11 and 15 MPa though, even higher stress drop estimates are possible for rupture velocities lower than 0.9Vs. The estimated stress drop is significantly higher than the global stress drop average of intraplate earthquakes, but is consistent with stress drop estimated for some intra-continental earthquakes elsewhere. The detection of a new active structure that appears to terminate in Machaze, its step-like geometry, and lithospheric strength all favors a hypothesis of stress concentration in the source region, which is likely the cause of this event and the higher than average stress drop.

  12. Diverse origins of Arctic and Subarctic methane point source emissions identified with multiply-substituted isotopologues

    Douglas, P. M. J.; Stolper, D. A.; Smith, D. A.; Walter Anthony, K. M.; Paull, C. K.; Dallimore, S.; Wik, M.; Crill, P. M.; Winterdahl, M.; Eiler, J. M.; Sessions, A. L.

    2016-09-01

    Methane is a potent greenhouse gas, and there are concerns that its natural emissions from the Arctic could act as a substantial positive feedback to anthropogenic global warming. Determining the sources of methane emissions and the biogeochemical processes controlling them is important for understanding present and future Arctic contributions to atmospheric methane budgets. Here we apply measurements of multiply-substituted isotopologues, or clumped isotopes, of methane as a new tool to identify the origins of ebullitive fluxes in Alaska, Sweden and the Arctic Ocean. When methane forms in isotopic equilibrium, clumped isotope measurements indicate the formation temperature. In some microbial methane, however, non-equilibrium isotope effects, probably related to the kinetics of methanogenesis, lead to low clumped isotope values. We identify four categories of emissions in the studied samples: thermogenic methane, deep subsurface or marine microbial methane formed in isotopic equilibrium, freshwater microbial methane with non-equilibrium clumped isotope values, and mixtures of deep and shallow methane (i.e., combinations of the first three end members). Mixing between deep and shallow methane sources produces a non-linear variation in clumped isotope values with mixing proportion that provides new constraints for the formation environment of the mixing end-members. Analyses of microbial methane emitted from lakes, as well as a methanol-consuming methanogen pure culture, support the hypothesis that non-equilibrium clumped isotope values are controlled, in part, by kinetic isotope effects induced during enzymatic reactions involved in methanogenesis. Our results indicate that these kinetic isotope effects vary widely in microbial methane produced in Arctic lake sediments, with non-equilibrium Δ18 values spanning a range of more than 5‰.

  13. Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

    Woronowicz, Michael S.

    2016-01-01

    Analytical expressions for column number density (CND) are developed for optical line of sight paths through a variety of steady free molecule point source models including directionally-constrained effusion (Mach number M = 0) and flow from a sonic orifice (M 1). Sonic orifice solutions are approximate, developed using a fair simulacrum fitted to the free molecule solution. Expressions are also developed for a spherically-symmetric thermal expansion (M = 0). CND solutions are found for the most general paths relative to these sources and briefly explored. It is determined that the maximum CND from a distant location through directed effusion and sonic orifice cases occurs along the path parallel to the source plane that intersects the plume axis. For the effusive case this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plumes axis. For sonic plumes this ratio is reduced to about 43. For high Mach number cases the maximum CND will be found along the axial centerline path.

  14. A Single Phase Doubly Grounded Semi-Z-Source Inverter for Photovoltaic (PV Systems with Maximum Power Point Tracking (MPPT

    Tofael Ahmed

    2014-06-01

    Full Text Available In this paper, a single phase doubly grounded semi-Z-source inverter with maximum power point tracking (MPPT is proposed for photovoltaic (PV systems. This proposed system utilizes a single-ended primary inductor (SEPIC converter as DC-DC converter to implement the MPPT algorithm for tracking the maximum power from a PV array and a single phase semi-Z-source inverter for integrating the PV with AC power utilities. The MPPT controller utilizes a fast-converging algorithm to track the maximum power point (MPP and the semi-Z-source inverter utilizes a nonlinear SPWM to produce sinusoidal voltage at the output. The proposed system is able to track the MPP of PV arrays and produce an AC voltage at its output by utilizing only three switches. Experimental results show that the fast-converging MPPT algorithm has fast tracking response with appreciable MPP efficiency. In addition, the inverter shows the minimization of common mode leakage current with its ground sharing feature and reduction of the THD as well as DC current components at the output during DC-AC conversion.

  15. Study of the distribution of non-point source pollution in the watershed of the Miyun Reservoir, Beijing, China.

    Wang, X; Li, T; Xu, A; He, W

    2001-01-01

    Nitrogen and phosphorus are major nutrients to cause eutrophication to degrade the water quality of the Miyun Reservoir, a very important drinking water source of Beijing in China. These are mainly from non-point sources. The watershed in Miyun County is selected as the study region with a total area of 1400 km2. Four typical monitoring catchments and two experimental units were used to monitor the precipitation, runoff, sediment yield and pollutant loading related to various land uses in the meantime. The results show that the total nutrient loss amount of TN and TP is 898.07 t/a, and 40.70 t/a, respectively, in which nutrient N and P carried by runoff is 91.3% and 77.3%, respectively. There is relatively heavier soil erosion at the northern mountain area whereas the main nutrient loss occurs near the northeast rim of the reservoir. Different land uses influence the loss of non-point source pollutants. The amount of nutrient loss from agricultural land per unit is the highest, nutrient loss from forestry is the second highest and that from grassland is the lowest. However, due to the variability of land use areas, agricultural land contributes the greatest amount of TP and forestry lands the greatest amount of TN. PMID:11724492

  16. Loop Heat Pipe Transient Behavior Using Heat Source Temperature for Set Point Control with Thermoelectric Converter on Reservoir

    Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

    2011-01-01

    The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly done by cold biasing the reservoir and using electrical heaters to provide the required control power. With this method, the loop operating temperature can be controlled within 0.5K or better. However, because the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if the LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP was carried out to investigate the effects on the LHP operation when the control temperature sensor was placed on the heat source instead of the reservoir. In these tests, the LHP reservoir was cold-biased and was heated by a control heater. Test results show that it was feasible to use the heat source temperature for feedback control of the LHP operation. In particular, when a thermoelectric converter was used as the reservoir control heater, the heat source temperature could be maintained within a tight range using a proportional-integral-derivative or on/off control algorithm. Moreover, because the TEC could provide both heating and cooling to the reservoir, temperature oscillations during fast transients such as loop startup could be eliminated or substantially reduced when compared to using an electrical heater as the control heater.

  17. Occurrence and point source characterization of perfluoroalkyl acids in sewage sludge.

    Alder, Alfredo C; van der Voet, Juergen

    2015-06-01

    The occurrence and levels of perfluoroalkyl acids (PFAAs) emitted from specific pollution sources into the aquatic environment in Switzerland were studied using digested sewage sludges from 45 wastewater treatment plants in catchments containing a wide range of potential industrial emitters. Concentrations of individual PFAAs show a high spatial and temporal variability, which infers different contributions from industrial technologies and activities. Perfluorooctane sulfonic acid (PFOS) was generally the predominant PFAA with concentrations varying between 4 and 2440μgkg(-1) (median 75μgkg(-1)). Elevated emissions were especially observed in catchments capturing discharges from metal plating industries (median 82μgkg(-1)), aqueous firefighting foams (median 215μgkg(-1)) and landfill leachates (median 107μgkg(-1)). Some elevated perfluoroalkyl carboxylic acids (PFCAs) levels could be attributed to emissions from textile finishing industries with concentrations up to 233μgkg(-1) in sewage sludge. Assuming sorption to sludge for PFOS and PFCAs of 15% and 2%, respectively, concentrations in wastewater effluents up to the low μgL(-1) level were estimated. Even if wastewater may be expected to be diluted between 10 and 100 times by the receiving waters, elevated concentrations may be reached at specific locations. Although sewage sludge is a minor compartment for PFAAs in WWTPs, these investigations are helpful for the identification of hot-spots from industrial emitters as well as to estimate monthly average concentrations in wastewater. PMID:25176581

  18. Identifying potential pollutant point sources in an area of high ground water consumption

    The Commonwealth of Pennsylvania relies heavily upon its ground water resources for drinking water. The US Environmental Protection Agency, Region 3, is responsible for regulating the discharge of waste to the subsurface through injection wells within Pennsylvania. To facilitate identification of industrial facilities unregulated by EPA that may be contaminating ground water through industrial water and waste water discharge wells, a screening procedure was devised utilizing a Geographic Information System (GIS). This procedure involved cross-referencing locations of industrial sites to maps of municipal sewer systems. The effectiveness of this GIS screening procedure was investigated in seven counties in southeastern Pennsylvania. Facilities identified by the procedure were inspected for possible violations of Underground Injection Control (UIC) program regulations. As a result of these inspections, many facilities were found to be illegally discharging waste into ground water. In addition, other EPA program violations were identified. The project demonstrated that the GIS screening procedure can be an effective tool to locate sources of pollution of ground water

  19. Event-based motion correction for PET transmission measurements with a rotating point source

    Accurate attenuation correction is important for quantitative positron emission tomography (PET) studies. When performing transmission measurements using an external rotating radioactive source, object motion during the transmission scan can distort the attenuation correction factors computed as the ratio of the blank to transmission counts, and cause errors and artefacts in reconstructed PET images. In this paper we report a compensation method for rigid body motion during PET transmission measurements, in which list mode transmission data are motion corrected event-by-event, based on known motion, to ensure that all events which traverse the same path through the object are recorded on a common line of response (LOR). As a result, the motion-corrected transmission LOR may record a combination of events originally detected on different LORs. To ensure that the corresponding blank LOR records events from the same combination of contributing LORs, the list mode blank data are spatially transformed event-by-event based on the same motion information. The number of counts recorded on the resulting blank LOR is then equivalent to the number of counts that would have been recorded on the corresponding motion-corrected transmission LOR in the absence of any attenuating object. The proposed method has been verified in phantom studies with both stepwise movements and continuous motion. We found that attenuation maps derived from motion-corrected transmission and blank data agree well with those of the stationary phantom and are significantly better than uncorrected attenuation data.

  20. Identifying non-point sources of endocrine active compounds and their biological impacts in freshwater lakes.

    Baker, Beth H; Martinovic-Weigelt, Dalma; Ferrey, Mark; Barber, Larry B; Writer, Jeffery H; Rosenberry, Donald O; Kiesling, Richard L; Lundy, James R; Schoenfuss, Heiko L

    2014-10-01

    Contaminants of emerging concern, particularly endocrine active compounds (EACs), have been identified as a threat to aquatic wildlife. However, little is known about the impact of EACs on lakes through groundwater from onsite wastewater treatment systems (OWTS). This study aims to identify specific contributions of OWTS to Sullivan Lake, Minnesota, USA. Lake hydrology, water chemistry, caged bluegill sunfish (Lepomis macrochirus), and larval fathead minnow (Pimephales promelas) exposures were used to assess whether EACs entered the lake through OWTS inflow and the resultant biological impact on fish. Study areas included two OWTS-influenced near-shore sites with native bluegill spawning habitats and two in-lake control sites without nearby EAC sources. Caged bluegill sunfish were analyzed for plasma vitellogenin concentrations, organosomatic indices, and histological pathologies. Surface and porewater was collected from each site and analyzed for EACs. Porewater was also collected for laboratory exposure of larval fathead minnow, before analysis of predator escape performance and gene expression profiles. Chemical analysis showed EACs present at low concentrations at each study site, whereas discrete variations were reported between sites and between summer and fall samplings. Body condition index and liver vacuolization of sunfish were found to differ among study sites as did gene expression in exposed larval fathead minnows. Interestingly, biological exposure data and water chemistry did not match. Therefore, although results highlight the potential impacts of seepage from OWTS, further investigation of mixture effects and life history factor as well as chemical fate is warranted. PMID:24974177

  1. Entropy-Weighted Instance Matching Between Different Sourcing Points of Interest

    Lin Li

    2016-01-01

    Full Text Available The crucial problem for integrating geospatial data is finding the corresponding objects (the counterpart from different sources. Most current studies focus on object matching with individual attributes such as spatial, name, or other attributes, which avoids the difficulty of integrating those attributes, but at the cost of an ineffective matching. In this study, we propose an approach for matching instances by integrating heterogeneous attributes with the allocation of suitable attribute weights via information entropy. First, a normalized similarity formula is developed, which can simplify the calculation of spatial attribute similarity. Second, sound-based and word segmentation-based methods are adopted to eliminate the semantic ambiguity when there is a lack of a normative coding standard in geospatial data to express the name attribute. Third, category mapping is established to address the heterogeneity among different classifications. Finally, to address the non-linear characteristic of attribute similarity, the weights of the attributes are calculated by the entropy of the attributes. Experiments demonstrate that the Entropy-Weighted Approach (EWA has good performance both in terms of precision and recall for instance matching from different data sets.

  2. Detecting long-term changes in point-source fossil CO2 emissions with tree ring archives

    Keller, Elizabeth D.; Turnbull, Jocelyn C.; Norris, Margaret W.

    2016-05-01

    We examine the utility of tree ring 14C archives for detecting long-term changes in fossil CO2 emissions from a point source. Trees assimilate carbon from the atmosphere during photosynthesis, in the process faithfully recording the average atmospheric 14C content in each new annual tree ring. Using 14C as a proxy for fossil CO2, we examine interannual variability over six years of fossil CO2 observations between 2004-2005 and 2011-2012 from two trees growing near the Kapuni Gas Treatment Plant in rural Taranaki, New Zealand. We quantify the amount of variability that can be attributed to transport and meteorology by simulating constant point-source fossil CO2 emissions over the observation period with the atmospheric transport model WindTrax. We compare model simulation results to observations and calculate the amount of change in emissions that we can detect with new observations over annual or multi-year time periods, given both the measurement uncertainty of 1ppm and the modelled variation in transport. In particular, we ask, what is the minimum amount of change in emissions that we can detect using this method, given a reference period of six years? We find that changes of 42 % or more could be detected in a new sample from one year at the same observation location or 22 % in the case of four years of new samples. This threshold is reduced and the method becomes more practical the more the size of the signal increases. For point sources 10 times larger than the Kapuni plant (a more typical size for power plants worldwide), it would be possible to detect sustained emissions changes on the order of 10 %, given suitable meteorology and observations.

  3. Field methods for determining point source pollution impacts in rivers: A case study of the Grindsted stream

    McKnight, Ursula S.; Sonne, Anne Thobo; Fjordbøge, Annika Sidelmann;

    2013-01-01

    , affected by two major polluting point sources, Grindsted factory and Grindsted landfill, representing two of the 43 large-scale contaminated sites in Denmark. Our overall aim was therefore to (i) test the applicability of different methods for mapping groundwater pollution as it enters streams at a complex...... waters. Transects placed perpendicular to stream flow in the contact zones allowed us to effectively localize the Grindsted factory plume using samples containing a unique compositional footprint consisting of chlorinated solvents, barbiturates, sulfonamides, sulfanilic acid and bromide specific for the...

  4. Estimating SO2 emissions from a large point source using 10 year OMI SO2 observations: Afsin Elbistan Power Plant

    Kaynak Tezel, Burcak; Firatli, Ertug

    2016-04-01

    SO2 pollution has still been a problem for parts of Turkey, especially regions with large scale coal power plants. In this study, 10 year Ozone Monitoring Instrument (OMI) SO2 observations are used for estimating SO2 emissions from large point sources in Turkey. We aim to estimate SO2 emissions from coal power plants where no online monitoring is available and improve the emissions given in current emission inventories with these top-down estimates. High-resolution yearly averaged maps are created on a domain over large point sources by oversampling SO2 columns for each grid for the years 2005-2014. This method reduced the noise and resulted in a better signal from large point sources and it was used for coal power plants in U.S and India, previously. The SO2 signal over selected power plants are observed with this method, and the spatiotemporal changes of SO2 signal are analyzed. With the assumption that OMI SO2 observations are correlating with emissions, long-term OMI SO2 observation averages can be used to estimate emission levels of significant point sources. Two-dimensional Gaussian function is used for explaining the relationships between OMI SO2 observations and emissions. Afsin Elbistan Power Plant, which is the largest capacity coal power plant in Turkey, is investigated in detail as a case study. The satellite scans within 50 km of the power plant are selected and averaged over a 2 x 2 km2 gridded domain by smoothing method for 2005-2014. The yearly averages of OMI SO2 are calculated to investigate the magnitude and the impact area of the SO2 emissions of the power plant. A significant increase in OMI SO2 observations over Afsin Elbistan from 2005 to 2009 was observed (over 2 times) possibly due to the capacity increase from 1715 to 2795 MW in 2006. Comparison between the yearly gross electricity production of the plant and OMI SO2 observations indicated consistency until 2009, but OMI SO2 observations indicated a rapid increase while gross electricity

  5. Two-dimensional complex source point solutions: application to propagationally invariant beams, optical fiber modes, planar waveguides, and plasmonic devices.

    Sheppard, Colin J R; Kou, Shan S; Lin, Jiao

    2014-12-01

    Highly convergent beam modes in two dimensions are considered based on rigorous solutions of the scalar wave (Helmholtz) equation, using the complex source point formalism. The modes are applicable to planar waveguide or surface plasmonic structures and nearly concentric microcavity resonator modes in two dimensions. A novel solution is that of a vortex beam, where the direction of propagation is in the plane of the vortex. The modes also can be used as a basis for the cross section of propagationally invariant beams in three dimensions and bow-tie-shaped optical fiber modes. PMID:25606756

  6. Instantaneous and time-averaged dispersion and measurement models for estimation theory applications with elevated point source plumes

    Diamante, J. M.; Englar, T. S., Jr.; Jazwinski, A. H.

    1977-01-01

    Estimation theory, which originated in guidance and control research, is applied to the analysis of air quality measurements and atmospheric dispersion models to provide reliable area-wide air quality estimates. A method for low dimensional modeling (in terms of the estimation state vector) of the instantaneous and time-average pollutant distributions is discussed. In particular, the fluctuating plume model of Gifford (1959) is extended to provide an expression for the instantaneous concentration due to an elevated point source. Individual models are also developed for all parameters in the instantaneous and the time-average plume equations, including the stochastic properties of the instantaneous fluctuating plume.

  7. Thermal stresses induced by a point heat source in a circular plate by quasi-static approach

    2011-01-01

    The present paper deals with the determination of quasi-static thermal stresses due to an instantaneous point heat source of strength g_(pi) situated at certain circle along the radial direction of the circular plate and releasing its heat spontaneously at time t=τ.A circular plate is considered having arbitrary initial temperature and subjected to time dependent heat flux at the fixed circular boundary of r=b.The governing heat conduction equation is solved by using the integral transform method,and res...

  8. Square Grid Points Coveraged by Connected Sources With Coverage Radius of One on a Two-Dimensional Grid

    Pattama Longani,

    2014-08-01

    Full Text Available W e take some parts of a theoretical mobility model in a two - dimension grid proposed by Greenlaw and Kantabutra to be our model. T he model has eight necessary factors that we commonly use in a mobile wireless network: sources or wireless signal p roviders, the directions that a source can move, users or mobile devices, the given directions which define a user’s movement, the given directions which defi ne a source’s movement, source’s velocity, source’s coverage, and obstacles. However, we include o nly the sources, source’s coverage, and the obstacles in our model. W e define S QUARE G RID P OINTS C OVERAGE (SGPC problem to minimize number of sources with coverage radius of one to cover a square grid point size of p with the restriction that all the sour ces must be communicable and proof th at SGPC is in NP - complete class. We also give an A PPROX - S QUARE - G RID - C OVERAGE (ASGC algorithm to compute the approximate solution of SGPC. ASGC use s the rule that any number can be obtained from the addition of 3, 4 and 5 and then combine s 3 - gadgets, 4 - gadgets and 5 - gadgets to specify the position of sources to cover a square grid point size of p . We find that the algorithm achieves an approximation ratio of 2 10 2 1 2 p p . Moreover, w e state about the extension usa ge of our algorithm and show some examples. We show that if we use ASPC on a square grid size of p and if sources can be moved, the area under the square grid can be covered in eight - time - steps movement. We also prove that i f we extend o ur source cover age radius to 1.59 , without any movement the area under the square gird will also be covered. Further studies are also discussed and a list of some tentative problems is given in the conclusion

  9. Geometrical and total efficiencies of CdZnTe rectangular parallelepiped detector using arbitrary positioned point, plane, and volumetric sources

    Hamzawy, A.; Badawi, Mohamed S.; Thabet, Abouzeid A.; Gouda, Mona M.; El-Khatib, Ahmed M.; Abbas, Mahmoud I.

    2016-02-01

    Gamma-ray detectors are widely used in many fields like environmental measurements, medicine, space science, and industry, where the detector geometrical, total, photopeak efficiencies and peak-to-total ratio could be required. The calculation of the detector efficiency depends mainly on the value of the geometrical efficiency, which depends on the solid angle subtended by the source-detector system. The present work introduces a direct analytical method to calculate the geometrical and total efficiencies of CdZnTe gamma-ray detector using off-axis isotropic radiating γ-ray [point, disk, and cylindrical] sources. To test the validity of the present work, the results are compared with some published data and also to prove how much it is important to determine the efficiency of difficult gamma-ray detection arrangement.

  10. Considering a point-source in a regional air pollution model; Prise en compte d`une source ponctuelle dans un modele regional de pollution atmospherique

    Lipphardt, M.

    1997-06-19

    This thesis deals with the development and validation of a point-source plume model, with the aim to refine the representation of intensive point-source emissions in regional-scale air quality models. The plume is modelled at four levels of increasing complexity, from a modified Gaussian plume model to the Freiberg and Lusis ring model. Plume elevation is determined by Netterville`s plume rise model, using turbulence and atmospheric stability parameters. A model for the effect of a fine-scale turbulence on the mean concentrations in the plume is developed and integrated in the ring model. A comparison between results with and without considering micro-mixing shows the importance of this effect in a chemically reactive plume. The plume model is integrated into the Eulerian transport/chemistry model AIRQUAL, using an interface between Airqual and the sub-model, and interactions between the two scales are described. A simulation of an air pollution episode over Paris is carried out, showing that the utilization of such a sub-scale model improves the accuracy of the air quality model

  11. Transformer-based asymmetrical embedded Z-source neutral point clamped inverters with continuous input current and enhanced voltage boost capability

    Mo, W.; Loh, Poh Chiang; Blaabjerg, Frede

    Z-source Neutral Point Clamped (NPC) inverters were introduced to integrate both the advantages of Z-source inverters and NPC inverters. However, traditional Z-source inverters suffer from high voltage stress and chopping input current. This paper proposes six types transformer-based impedance......-source NPC inverters which have enhanced voltage boost capability and continuous input current by utilizing of transformer and embedded dc source configuration. Experimental results are presented to verify the theory validation....

  12. Identification of a time-varying point source in a system of two coupled linear diffusion-advection- reaction equations: application to surface water pollution

    This paper deals with the identification of a point source (localization of its position and recovering the history of its time-varying intensity function) that constitutes the right-hand side of the first equation in a system of two coupled 1D linear transport equations. Assuming that the source intensity function vanishes before reaching the final control time, we prove the identifiability of the sought point source from recording the state relative to the second coupled transport equation at two observation points framing the source region. Note that at least one of the two observation points should be strategic. We establish an identification method that uses these records to identify the source position as the root of a continuous and strictly monotonic function. Whereas the source intensity function is recovered using a recursive formula without any need of an iterative process. Some numerical experiments on a variant of the surface water pollution BOD–OD coupled model are presented

  13. Analysis of point source pollution and water environmental quality variation trends in the Nansi Lake basin from 2002 to 2012.

    Wang, Weiliang; Liu, Xiaohui; Wang, Yufan; Guo, Xiaochun; Lu, Shaoyong

    2016-03-01

    Based on the data analysis of the water environmental quality and economic development from 2002 to 2012 in the Nansi Lake basin, the correlation and change between the water environmental quality and economic development were studied. Results showed that the GDP and wastewater emissions of point source in the Nansi Lake basin had an average annual growth of 7.30 and 7.68 %, respectively, from 2002 to 2012. The emissions of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) had the average annual decrease of 7.69 and 6.79 % in 2012, respectively, compared to 2002. Basin water quality overall improved, reaching the Class III of the "Environmental quality standards for surface water (GB3838-2002)," in which the main reason was that sewage treatment rate increased gradually and was above 90 % in 2012 (an increase of 10 % compared to 2002) with the progress of pollution abatement technology and the implementation of relevant policies and regulations. The contribution of water environmental pollution was analyzed from related cities (Ji'ning, Zaozhuang, Heze). Results indicated that Ji'ning had the largest contribution to water pollution of the Nansi Lake basin, and the pollutant from domestic sources accounted for a higher percentage compared to industrial sources. The wastewater, COD, and NH3-N mainly came from mining and washing of coal, manufacture of raw chemical materials and chemical products, papermaking industry, and food processing industry. According to the water pollution characteristics of the Nansi Lake basin, the basin pollution treatment strategy and prevention and treatment system were dissected to provide a scientific basis for prevention and control of lakeside point source pollution along the Nansi Lake. PMID:26545892

  14. Atmospheric observations for quantifying emissions of point-source synthetic greenhouse gases (CF4, NF3 and HFC-23)

    Arnold, Tim; Manning, Alistair J.; Li, Shanlan; Kim, Jooil; Park, Sunyoung; Fraser, Paul J.; Mitrevski, Blagoj; Steele, L. Paul; Krummel, Paul B.; Mühle, Jens; Weiss, Ray F.

    2016-04-01

    The fluorinated species carbon tetrafluoride (CF4; PFC-14), nitrogen trifluoride (NF3) and trifluoromethane (CHF3; HFC-23) are potent greenhouse gases with 100-year global warming potentials of 6,630, 16,100 and 12,400, respectively. Unlike the majority of CFC-replacement compounds that are emitted from fugitive and mobile emission sources, these gases are largely emitted from large single point sources - semiconductor manufacturing facilities (all three), aluminium smelting plants (CF4) and chlorodifluoromethane factories (HFC-23). In this work we show the potential for atmospheric measurements to understand regional sources of these gases and to highlight emission 'hotspots'. We target our analysis on measurements from two Advanced Global Atmospheric Gases Experiment (AGAGE) long term monitoring sites that are particularly sensitive to regional emissions of these gases: Gosan on Jeju Island in the Republic of Korea and Cape Grim on Tasmania in Australia. These sites measure CF4, NF3 and HFC-23 alongside a suite of greenhouse and stratospheric ozone depleting gases every two hours using automated in situ gas-chromatography mass-spectrometry instrumentation. We couple each measurement to an analysis of air history using the regional atmospheric transport model NAME (Numerical Atmospheric dispersion Modelling Environment) driven by 3D meteorology from the Met Office's Unified Model, and use a Bayesian inverse method (InTEM - Inversion Technique for Emission Modelling) to calculate yearly emission changes over a decade (2005-2015) at high spatial resolution. At present these gases make a small contribution to global radiative forcing, however, given that their impact could rise significantly and that point sources of such gases can be mitigated, atmospheric monitoring could be an important tool for aiding emissions reduction policy.

  15. Searches for extended and point-like neutrino sources with four years of IceCube data

    We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the combined data set is 1373 days. For an E –2 spectrum, the observed 90% C.L. flux upper limits are ∼10–12 TeV–1 cm–2 s–1 for energies between 1 TeV and 1 PeV in the northern sky and ∼10–11 TeV–1 cm–2 s–1 for energies between 100 TeV and 100 PeV in the southern sky. This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.

  16. Searches for extended and point-like neutrino sources with four years of IceCube data

    Aartsen, M. G. [School of Chemistry and Physics, University of Adelaide, Adelaide SA, 5005 Australia (Australia); Ackermann, M.; Berghaus, P. [DESY, D-15735 Zeuthen (Germany); Adams, J. [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Aguilar, J. A. [Département de physique Nucléaire et Corpusculaire, Université de Genève, CH-1211 Genève (Switzerland); Ahlers, M.; Arguelles, C.; BenZvi, S. [Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, WI 53706 (United States); Ahrens, M. [Oskar Klein Centre and Department of Physics, Stockholm University, SE-10691 Stockholm (Sweden); Altmann, D. [Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen (Germany); Anderson, T.; Arlen, T. C. [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Auffenberg, J. [III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen (Germany); Bai, X. [Physics Department, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Barwick, S. W. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Baum, V. [Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099 Mainz (Germany); Beatty, J. J. [Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Tjus, J. Becker [Fakultät für Physik and Astronomie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Becker, K.-H. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Berley, D. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Collaboration: IceCube Collaboration; and others

    2014-12-01

    We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the combined data set is 1373 days. For an E {sup –2} spectrum, the observed 90% C.L. flux upper limits are ∼10{sup –12} TeV{sup –1} cm{sup –2} s{sup –1} for energies between 1 TeV and 1 PeV in the northern sky and ∼10{sup –11} TeV{sup –1} cm{sup –2} s{sup –1} for energies between 100 TeV and 100 PeV in the southern sky. This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.

  17. The speciation of marine particulate iron adjacent to active and passive continental margins

    Lam, Phoebe J.; Ohnemus, Daniel C.; Marcus, Matthew A.

    2012-03-01

    We use synchrotron-based chemical-species mapping techniques to compare the speciation of suspended (1-51 μm) marine particulate iron collected in two open ocean environments adjacent to active and passive continental margins. Chemical-species mapping provides speciation information for heterogeneous environmental samples, and is especially good for detecting spectroscopically distinct trace minerals and species that could not be detectable by other methods. The average oxidation state of marine particulate iron determined by chemical-species mapping is comparable to that determined by standard bulk X-ray Absorption Near Edge Structure spectroscopy. Using chemical-species mapping, we find that up to 43% of particulate Fe in the Northwest Pacific at the depth of the adjacent active continental margin is in the Fe(II) state, with the balance Fe(III). In contrast, particulate iron in the eastern tropical North Atlantic, which receives the highest dust deposition on Earth and is adjacent to a passive margin, is dominated by weathered and oxidized Fe compounds, with Fe(III) contributing 90% of total iron. The balance is composed primarily of Fe(II)-containing species, but we detected individual pyrite particles in some samples within an oxygen minimum zone in the upper thermocline. Several lines of evidence point to the adjacent Mauritanian continental shelf as the source of pyrite to the water column. The speciation of suspended marine particulate iron reflects the mineralogy of iron from the adjacent continental margins. Since the solubility of particulate iron has been shown to be a function of its speciation, this may have implications for the bioavailability of particulate iron adjacent to passive compared to active continental margins.

  18. Attenuation data of point isotropic neutron sources up to 400MeV in water, ordinary concrete and iron

    Kotegawa, Hiroshi; Tanaka, Shun-ichi; Sakamoto, Yukio; Nakane, Yoshihiro; Nakashima, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1994-08-01

    A comprehensive attenuation data of dose equivalent for point isotropic monoenergetic neutron sources up to 400MeV in infinite shields of water, ordinary concrete and iron has been calculated using the ANISN-JR code and a neutron-photon multigroup macroscopic cross section HIL086R. The attenuation factors were fitted to a 4th order polynomial exponent formula, making possible to use easily for point kernel codes. Additional data in finite shielding geometry was also calculated to correct the effect due to infinite medium, giving the maximum correction of 0.23 in the region for more 400 cm distance from neutron source of 400 MeV in iron shield. Effective attenuation length for monoenergetic neutrons have been studied in detail. Subsequently, it was shown that the attenuation length was strongly dependent upon the penetration length and the Moyer`s formula using a single attenuation length brought large error into the dose estimation behind thick shields for the intermediate energy neutrons up to 400 MeV. Furthermore, it was demonstrated that there was difference more than 50 % in the attenuation length of iron between the calculations with HIL086R and HIL086 because of the self-shielding effect. (author).

  19. Attenuation data of point isotropic neutron sources up to 400MeV in water, ordinary concrete and iron

    A comprehensive attenuation data of dose equivalent for point isotropic monoenergetic neutron sources up to 400MeV in infinite shields of water, ordinary concrete and iron has been calculated using the ANISN-JR code and a neutron-photon multigroup macroscopic cross section HIL086R. The attenuation factors were fitted to a 4th order polynomial exponent formula, making possible to use easily for point kernel codes. Additional data in finite shielding geometry was also calculated to correct the effect due to infinite medium, giving the maximum correction of 0.23 in the region for more 400 cm distance from neutron source of 400 MeV in iron shield. Effective attenuation length for monoenergetic neutrons have been studied in detail. Subsequently, it was shown that the attenuation length was strongly dependent upon the penetration length and the Moyer's formula using a single attenuation length brought large error into the dose estimation behind thick shields for the intermediate energy neutrons up to 400 MeV. Furthermore, it was demonstrated that there was difference more than 50 % in the attenuation length of iron between the calculations with HIL086R and HIL086 because of the self-shielding effect. (author)

  20. Five years of searches for point sources of astrophysical neutrinos with the AMANDA-II neutrino telescope

    Achterberg, A.; Ackermann, M.; Adams, J.; Ahrens, J.; Andeen, K.; Atlee, D. W.; Bahcall, J. N.; Bai, X.; Baret, B.; Barwick, S. W.; Bay, R.; Beattie, K.; Becka, T.; Becker, J. K.; Becker, K.-H.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Bolmont, J.; Böser, S.; Botner, O.; Bouchta, A.; Braun, J.; Burgess, C.; Burgess, T.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cowen, D. F.; D'Agostino, M. V.; Davour, A.; Day, C. T.; de Clercq, C.; Demirörs, L.; Descamps, F.; Desiati, P.; De Young, T.; Diaz-Velez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feser, T.; Filimonov, K.; Fox, B. D.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Geenen, H.; Gerhardt, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Grullon, S.; Groß, A.; Gunasingha, R. M.; Gurtner, M.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hardtke, D.; Hardtke, R.; Harenberg, T.; Hart, J. E.; Hauschildt, T.; Hays, D.; Heise, J.; Helbing, K.; Hellwig, M.; Herquet, P.; Hill, G. C.; Hodges, J.; Hoffman, K. D.; Hommez, B.; Hoshina, K.; Hubert, D.; Hughey, B.; Hulth, P. O.; Hultqvist, K.; Hundertmark, S.; Hülß, J.-P.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Jones, A.; Joseph, J. M.; Kampert, K.-H.; Karle, A.; Kawai, H.; Kelley, J. L.; Kestel, M.; Kitamura, N.; Klein, S. R.; Klepser, S.; Kohnen, G.; Kolanoski, H.; Kowalski, M.; Köpke, L.; Krasberg, M.; Kuehn, K.; Landsman, H.; Leich, H.; Leier, D.; Leuthold, M.; Liubarsky, I.; Lundberg, J.; Lünemann, J.; Madsen, J.; Mase, K.; Matis, H. S.; McCauley, T.; McParland, C. P.; Meli, A.; Messarius, T.; Mészáros, P.; Miyamoto, H.; Mokhtarani, A.; Montaruli, T.; Morey, A.; Morse, R.; Movit, S. M.; Münich, K.; Nahnhauer, R.; Nam, J. W.; Nießen, P.; Nygren, D. R.; Ögelman, H.; Olivas, A.; Patton, S.; Peña-Garay, C.; Pérez de Los Heros, C.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Pretz, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Razzaque, S.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Robbins, S.; Roth, P.; Rott, C.; Rutledge, D.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Seckel, D.; Seo, S. H.; Seunarine, S.; Silvestri, A.; Smith, A. J.; Solarz, M.; Song, C.; Sopher, J. E.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Steffen, P.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sulanke, K.-H.; Sullivan, G. W.; Sumner, T. J.; Taboada, I.; Tarasova, O.; Tepe, A.; Thollander, L.; Tilav, S.; Tluczykont, M.; Toale, P. A.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; Voigt, B.; Wagner, W.; Walck, C.; Waldmann, H.; Walter, M.; Wang, Y.-R.; Wendt, C.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zornoza, J. D.

    2007-05-01

    We report the results of a five-year survey of the northern sky to search for point sources of high energy neutrinos. The search was performed on the data collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with a live time of 1001 days. The sample of selected events consists of 4282 upward going muon tracks with high reconstruction quality and an energy larger than about 100 GeV. We found no indication of point sources of neutrinos and set 90% confidence level flux upper limits for an all-sky search and also for a catalog of 32 selected sources. For the all-sky search, our average (over declination and right ascension) experimentally observed upper limit Φ0=((E)/(1TeV))γ·(dΦ)/(dE) to a point source flux of muon and tau neutrino (detected as muons arising from taus) is Φνμ+ν¯μ0+Φντ+ν¯τ0=11.1×10-11TeV-1cm-2s-1, in the energy range between 1.6 TeV and 2.5 PeV for a flavor ratio Φνμ+ν¯μ0/Φντ+ν¯τ0=1 and assuming a spectral index γ=2. It should be noticed that this is the first time we set upper limits to the flux of muon and tau neutrinos. In previous papers we provided muon neutrino upper limits only neglecting the sensitivity to a signal from tau neutrinos, which improves the limits by 10% to 16%. The value of the average upper limit presented in this work corresponds to twice the limit on the muon neutrino flux Φνμ+ν¯μ0=5.5×10-11TeV-1cm-2s-1. A stacking analysis for preselected active galactic nuclei and a search based on the angular separation of the events were also performed. We report the most stringent flux upper limits to date, including the results of a detailed assessment of systematic uncertainties.