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Sample records for eastern lau spreading

  1. Origins of chemical diversity of back-arc basin basalts: a segment-scale study of the Eastern Lau Spreading Center

    OpenAIRE

    Bézos, Antoine; Escrig, Stéphane; Langmuir, Charles H.; Michael, Peter J.; Asimow, Paul D.

    2009-01-01

    We report major, trace, and volatile element data on basaltic glasses from the northernmost segment of the Eastern Lau Spreading Center (ELSC1) in the Lau back-arc basin to further test and constrain models of back-arc volcanism. The zero-age samples come from 47 precisely collected stations from an 85 km length spreading center. The chemical data covary similarly to other back-arc systems but with tighter correlations and well-developed spatial systematics. We confirm a correlation between v...

  2. Origins of chemical diversity of back-arc basin basalts: A segment-scale study of the Eastern Lau Spreading Center

    Science.gov (United States)

    BéZos, Antoine; Escrig, StéPhane; Langmuir, Charles H.; Michael, Peter J.; Asimow, Paul D.

    2009-06-01

    We report major, trace, and volatile element data on basaltic glasses from the northernmost segment of the Eastern Lau Spreading Center (ELSC1) in the Lau back-arc basin to further test and constrain models of back-arc volcanism. The zero-age samples come from 47 precisely collected stations from an 85 km length spreading center. The chemical data covary similarly to other back-arc systems but with tighter correlations and well-developed spatial systematics. We confirm a correlation between volatile content and apparent extent of melting of the mantle source but also show that the data cannot be reproduced by the model of isobaric addition of water that has been broadly applied to back-arc basins. The new data also confirm that there is no relationship between mantle temperature and the wet melting productivity. Two distinct magmatic provinces can be identified along the ELSC1 axis, a southern province influenced by a "wet component" with strong affinities to arc volcanism and a northern province influenced by a "damp component" intermediate between enriched mid-ocean ridge basalts (E-MORB) and arc basalts. High-field strength elements and rare earth elements are all mobilized to some extent by the wet component, and the detailed composition of this component is determined. It differs in significant ways from the Mariana component reported by E. Stolper and S. Newman (1994), particularly by having lower abundances of most elements relative to H2O. The differences can be explained if the slab temperature is higher for the Mariana and the source from which the fluid is derived is more enriched. The ELSC1 damp component is best explained by mixing between the wet component and an E-MORB-like component. We propose that mixing between water-rich fluids and low-degree silicate melts occurs at depth in the subduction zone to generate the chemical diversity of the ELSC1 subduction components. These modified sources then rise independently to the surface and melt, and these

  3. The 2008 Puipui eruption and morphology of the Northeast Lau Spreading Center between Maka and Tafu (Invited)

    Science.gov (United States)

    Clague, D. A.; Caress, D. W.; Rubin, K. H.; Paduan, J. B.

    2010-12-01

    An event plume was discovered in the water column between Maka and Tafu volcanoes on the Northeast Lau Spreading Center in Nov. 2008. A Rapid Response cruise in May 2009 found that eruptive activity had ceased after observations on two Jason II ROV dives and one MBARI Mapping AUV survey that mapped most of the axis and flanks at 1.5-m resolution. Jason II located a recent lava flow, which was named Puipui. The small ridge of mounds aligned along two overlapping fissures extend for 1.8 km. The pillow ridge cuts obliquely across the ridge axis. The dive observations show mainly pillow lavas near the NE end and sheet flows near the SE end. A central 340 m portion observed by Jason II as predominantly ponded lobate flows was not mapped by the AUV. The Puipui and prior eruptions produced abundant vesicular angular glass fragments, Pele’s hair, and less abundant limu o Pele pyroclasts that thinly blanket the axial plateau and cascade down the steep flanks, mixing debris from many eruptions. Electron probe analyses of 91 fragments show that 15 Puipui pyroclasts are compositionally variable (normalized 6.5-7.2% MgO, ~49.6% SiO2) and distinct from prior eruptions in the area that have lower TiO2, K2O, Na2O, and K2O; and 52.3-53.7% SiO2. Pyroclasts of all compositions are highly degassed (<0.025% S) prior to eruption. The NE-trending segment, anchored by Maka volcano at the SE end, includes the Puipui flow. The morphology changes dramatically over short distances. The 1 km SW end is characterized by multiple extensional faults that parallel the ridge axis. The AUV survey ends on a sheet flow with drained ponds. To the NE, Maka is a 1.2 km diameter central volcano rising 300 m above the adjacent ridge to a summit at 1515 m. The ridge axis deepens steadily to 2140 m at the NE survey end and 1900 m to the SW. Rift zones on Maka parallel the ridge axis and are constructed of overlapping lava deltas. The NW and SE flanks are smooth like those at actively erupting West Mata

  4. Active Eruptions in the NE Lau Basin

    Science.gov (United States)

    Resing, J. A.; Embley, R. W.

    2009-12-01

    NE Lau Response Team: K Rubin, E Baker, J Lupton, M Lilley, T Shank, S Merle, R Dziak, T Collasius (Jason 2 Expedition Leader), N Buck, T Baumberger, D Butterfield, D Clague, D Conlin, J Cowen, R Davis, L Evans, J Huber, M Keith, N Keller, P Michael, E Podowski, A-L Reysenbach, K Roe, H Thomas, S Walker. During a May 2009 cruise to W Mata volcano in the NE Lau Basin, we made the first observations of an active eruption on the deep-sea floor. The cruise was organized after volcanic activity was detected at two sites (W Mata volcano and NE Lau Spreading Center, NELSC) during a Nov. 2008 NOAA-PMEL expedition. At that time, both sites had elevated H2 concentrations and volcaniclastic shards in the hydrothermal plumes. Moored hydrophone data since Jan 2009 indicate that the activity at W Mata has been continuous between these expeditions. Results of our cruise and other work suggest that the NE Lau Basin hosts an unusually high level of magmatic activity, making it an ideal location to study the effects of magmatic processes on hydrothermal activity and associated ecosystems. W Mata was visited with 5 ROV Jason 2 dives and 2 dives with the MBARI autonomous mapping vehicle in May 2009. It was actively erupting at the 1200 m deep summit during each, so a hydrophone was deployed locally to collect acoustic data. Ship and shore-based analysis of HD video, molten lava, rocks, sediments, hot spring waters, and micro- and macro biological specimens collected by Jason 2 have provided a wealth of data. The eruption itself was characterized by extrusion of red, molten lava, extensive degassing, formation of large magma bubbles, explosive pyroclast ejection, and the active extrusion of pillow lavas. The erupting magmas are boninite, a relatively rare magma type found only at convergent margins. The hydrothermal fluids are generally acidic and all diffuse fluids collected were microbially active, even those at pH 20 yrs the PMEL-Vents and NSF RIDGE programs have sought to observe

  5. Early ceramic sites in southern Lau, Fiji

    International Nuclear Information System (INIS)

    Clark, G.

    2009-01-01

    The Lau Group is a dispersed chain of islands in east Fiji trending north-south on the inactive Lau Ridge remnant volcanic arc, which is part of the convergent margin system comprising the Lau Basin and Tonga Ridge to the east. In the south of the Lau Group are several remote islands that are closer to Tangatapu than they are to the largest islands of Viti Levu and Vanua Levu in the Fiji Group. Two of these islands, Vatoa and Doi islands in the Ono-i-Lau Group, were visited briefly in 2006 after field work on Kabara when the government supply boat 'Sandy' made scheduled stops to unload and collect cargo. Lapita pottery and a fortification were recorded on Doi Island in the Ono Group, and on Vatoa Island a site with plain ware ceramics dating to c. 2000 cal. BP was located. The position of the two remote islands lying between the main islands of Fiji and Tongan archipelago suggests they were particularly subject to influence from population contacts and movements from islands to their east and west in prehistory. In the eighteenth and nineteenth century central and southern Lau were the centre of an important canoe building industry based on the hardwood Instia bijuga (vesi) used to construct large sailing canoes which were the prerogative of Tongan and Fijian chiefs. Archaeological and linguistic studies of the Lau Group suggest a complicated history of population movements earlier during Lapita (2900-2500 BP) and post-Lapita (∼2500-1000 BP) times, which can be examined from the study of ceramic sites in southern Lau. (author). 27 refs., 3 figs

  6. Live pig markets in eastern Indonesia: Trader characteristics, biosecurity and implications for disease spread.

    Science.gov (United States)

    Leslie, Edwina E C; Geong, Maria; Abdurrahman, Muktasam; Ward, Michael P; Toribio, Jenny-Ann L M L

    2016-03-01

    Classical swine fever has been negatively impacting pig production in Nusa Tenggara Timur province in eastern Indonesia since its introduction in the 1990s, with live market trade contributing to disease spread. To understand market trader knowledge and practices regarding pig management, biosecurity, pig movements and pig health (specifically CSF), a repeated survey was conducted with pig sellers and pig buyers at 9 market sites across West Timor and the islands of Flores and Sumba. A total of 292 sellers and 281 buyers were interviewed in 2009 during two periods (rounds), a high-demand month (September) and a low-demand month (November). Information was collected via questionnaire. The majority of traders were male (sellers: 89%; buyers: 87%) with the highest level of completed education being primary school (sellers: 48%; buyers: 41%). The primary occupation of most respondents was farming: 90% of sellers and 87% of buyers were smallholder pig farmers and tended to sell their own home-raised pigs at market (52%). Pigs were sold for monetary gain either for primary (52%) or extra income (44%). Markets tended to be selected based on a good reputation (62%), a location close to residence (62%) and having the desired pig type (59%). Pig sales through markets were reported to be highest from August to October with 31% of sellers trading pigs at two or more markets. Prices at market were significantly higher on Sumba compared to West Timor and cross-bred pigs were significantly more expensive than indigenous pigs. Understanding of CSF and biosecurity was limited: 85% of sellers and 83% of buyers had no prior knowledge of CSF. Fifty-four percent of sellers reported no use of any biosecurity practices at market. Most respondents (88%) were able to recognise at least one clinical sign of a sick pig. Informal pig movements were also identified: 18% of pig buyers purchased pigs directly from other farmers. This study has provided baseline information on market trader

  7. Using the Talbot_Lau_interferometer_parameters Spreadsheet

    Energy Technology Data Exchange (ETDEWEB)

    Kallman, Jeffrey S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-04

    Talbot-Lau interferometers allow incoherent X-ray sources to be used for phase contrast imaging. A spreadsheet for exploring the parameter space of Talbot and Talbot-Lau interferometers has been assembled. This spreadsheet allows the user to examine the consequences of choosing phase grating pitch, source energy, and source location on the overall geometry of a Talbot or Talbot-Lau X-ray interferometer. For the X-ray energies required to penetrate scanned luggage the spacing between gratings is large enough that the mechanical tolerances for amplitude grating positioning are unlikely to be met.

  8. Directionality and spread of shallow water waves along the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Anoop, T.R.

    , at http://www.cdc.noaa.gov/. 4 Results and discussions 4.1 Wave directional spreading For long-crested waves, the value of directional width is 0◦, and as the waves become short-crested, the value increases and the wave directional spreading increases...

  9. Multiple Active Volcanoes in the Northeast Lau Basin

    Science.gov (United States)

    Baker, E. T.; Resing, J. A.; Lupton, J. E.; Walker, S. L.; Embley, R. W.; Rubin, K. H.; Buck, N.; de Ronde, C. E.; Arculus, R. J.

    2010-12-01

    The northeast Lau Basin occupies a complex geological area between the Tafua arc front, the E-W trending Tonga Trench, and the Northeast Lau Spreading Center. These boundaries create multiple zones of extension and thus provide abundant opportunities for magma to invade the crust. The 25-km-long chain of “Mata” volcanoes lies near the center of this area, separated from both the arc front and the spreading ridge. In 2008 we discovered hydrothermal venting on the largest and most southerly of these volcanoes, W and E Mata. In 2010 we visited the 7 smaller volcanoes that form a 15-km-long arcuate sweep to the north from W and E Mata (the “North Matas”). We also revisited W and E Mata. Over each volcano we conducted CTD tows to map plumes and collect water samples. Based on the CTD results, camera tows searched for seafloor sources on three volcanoes. The N Mata volcanoes, extending from Mata Taha (1) in the south to Mata Fitu (7) in the north, lie within a prominent gap in the shallow bathymetry along the southern border of the Tonga trench. Northward from E Mata the Mata volcanoes degrade from large symmetrical cones to smaller and blocky volcanic edifices. Summit depths range from 1165 m (W Mata) to 2670 m (Mata Nima (5)). The most active volcano in the chain is the erupting W Mata, with an intense plume that extended 250 m above the summit. Hydrothermal temperature anomalies (Δθ, corrected for hydrographic masking effects) reached ˜1.7°C, with light-scattering values as high as 2-5 ΔNTU. The 2010 surveys now show that 6 of the 7 N Mata volcanoes are also hydrothermally active. Along the N Matas, Δθ and ΔNTU signals ranged from robust to weak, but distinct oxidation-reduction potential (aka Eh) anomalies confirmed active venting in each case. The most concentrated plumes were found near Mata Ua (2) and Mata Fitu (7), with Δθ and ΔNTU maxima of 0.1-0.17°C and 0.3, respectively. Despite the variability in plume strength, however, ΔNTU/Δθ ratios

  10. The influence of 19th century Dutch Colonial Orientalism in spreading Kubah (Islamic Dome) and Middle-Eastern architectural styles for mosques in Sumatra

    OpenAIRE

    Kemas Ridwan Kurniawan; Ratu Arum Kusumawardhani

    2012-01-01

    This paper researches the possible representation of Orientalism and the spread of Middle Eastern inspired architecture in Indonesia, particularly in Dutch colonial practices in the 19th-century. It challenges the dominant opinion of the people that the Middle Eastern merchants in the East Indies were the only ones that introduced the use of kubah (dome) shape to mosque architecture in Indonesia. Consequently, this paper has two objectives: firstly, by looking at the historical relationship b...

  11. Defining the Lau context : recent findings on Nayau, Lau Islands, Fiji

    International Nuclear Information System (INIS)

    Jones O'Day, S.; O'Day, P.; Steadman, D.W.

    2004-01-01

    We present analyses of reconnaissance surveys, test excavations, stratigraphy, chronology, material culture, and faunal remains from 14 archaeological sites on Nayau, Lau Islands, Fiji. We found Lapita pottery on sand dunes along the southeast coast of the island. Although this site was not stratigraphically excavated or dated, our survey and test excavations of the surrounding area indicate that Lapita-period subsurface deposits are intact and widespread. Elsewhere, we obtained six AMS radiocarbon dates from bones recovered in test excavations at various site types and locations. None of the dated samples is older than ca. 710 cal BP. This chronology, combined with the presence of the Lapita site and survey data, suggests that human occupation of Nayau was continuous since Lapita times. Like Lakeba, Nayau incorporates all ceramic and cultural phases previously defined for Fiji. We suggest that archaeological data from Nayau are critical to understanding patterns of prehistoric contact and change in Lauan and Fijian society. (author). 39 refs., 7 figs., 10 tabs

  12. Extensive young silicic volcanism produces large deep submarine lava flows in the NE Lau Basin

    Science.gov (United States)

    Embley, Robert W.; Rubin, Kenneth H.

    2018-04-01

    New field observations reveal that extensive (up to 402 km2) aphyric, glassy dacite lavas were erupted at multiple sites in the recent past in the NE Lau basin, located about 200 km southwest of Samoa. This discovery of volumetrically significant and widespread submarine dacite lava flows extends the domain for siliceous effusive volcanism into the deep seafloor. Although several lava flow fields were discovered on the flank of a large silicic seamount, Niuatahi, two of the largest lava fields and several smaller ones ("northern lava flow fields") were found well north of the seamount. The most distal portion of the northernmost of these fields is 60 km north of the center of Niuatahi caldera. We estimate that lava flow lengths from probable eruptive vents to the distal ends of flows range from a few km to more than 10 km. Camera tows on the shallower, near-vent areas show complex lava morphology that includes anastomosing tube-like pillow flows and ropey surfaces, endogenous domes and/or ridges, some with "crease-like" extrusion ridges, and inflated lobes with extrusion structures. A 2 × 1.5 km, 30-m deep depression could be an eruption center for one of the lava flow fields. The Lau lava flow fields appear to have erupted at presumptive high effusion rates and possibly reduced viscosity induced by presumptive high magmatic water content and/or a high eruption temperature, consistent with both erupted composition ( 66% SiO2) and glassy low crystallinity groundmass textures. The large areal extent (236 km2) and relatively small range of compositional variation ( σ = 0.60 for wt% Si02%) within the northern lava flow fields imply the existence of large, eruptible batches of differentiated melt in the upper mantle or lower crust of the NE Lau basin. At this site, the volcanism could be controlled by deep crustal fractures caused by the long-term extension in this rear-arc region. Submarine dacite flows exhibiting similar morphology have been described in ancient

  13. The influence of 19th century Dutch Colonial Orientalism in spreading Kubah (Islamic Dome and Middle-Eastern architectural styles for mosques in Sumatra

    Directory of Open Access Journals (Sweden)

    Kemas Ridwan Kurniawan

    2012-12-01

    Full Text Available This paper researches the possible representation of Orientalism and the spread of Middle Eastern inspired architecture in Indonesia, particularly in Dutch colonial practices in the 19th-century. It challenges the dominant opinion of the people that the Middle Eastern merchants in the East Indies were the only ones that introduced the use of kubah (dome shape to mosque architecture in Indonesia. Consequently, this paper has two objectives: firstly, by looking at the historical relationship between religious architecture and colonial politics, especially in the construction of the Baiturrahman Mosque in Aceh and secondly, by considering Orientalism (besides those beliefs existing in Moslem communities to be one of important intellectual agencies for mixing architectural cultural symbols. The socio-political narrative is analyzed in the context of an Indonesian-Islamic building typology and the relationship between space, people, power, and time. The research itself is based on literature searches specifically related to colonialism and orientalism, along with archive studies and field investigations, including interviews with related historical experts. In order to replace 'non-architectural' traditional roofs, which were considered as representing a less-developed civilization, Dutch political interests were instrumental in bringing the universally-styled Middle Eastern architectural elements into mosque architecture of the Netherland Indies. This political motivation ultimately led to the spread of kubah (dome as an architectonic element in Indonesian mosque architecture throughout the archipelago, specifically in Sumatra.

  14. Acoustic Transmission Loss and Prolonged Coda Durations of Seismic Airgunning at Intermediate Ranges in the Lau Back-Arc Basin

    Science.gov (United States)

    Scheip, C.; Bohnenstiehl, D. R.; Matsumoto, H.; Dziak, R. P.; Lau, T. A.; Fowler, M.; Conder, J. A.; Wiens, D. A.

    2010-12-01

    During January-February of 2009, the R/V Marcus G. Langseth carried out an active-source seismic survey in the Lau Back-Arc Basin (20 S, 175 W) [Dunn et al., OS13A-1157, 2009]. Although the survey was designed to image sub-seafloor structures, the acoustic energy also was recorded by an array of seven autonomous underwater hydrophones positioned at a range of 29-416 km. The seismic survey used a 36-gun array with a source depth less than 10 m, and fired approximately 9400 shots. The hydrophone receivers were calibrated omni-directional sensors sampled at 250 Hz and moored at a depth of 1000 m. The acoustic environment of the tropical Lau Basin is unique in that the critical depth of the sound channel lies well below the relatively shallow (2000-2500 m) depth of the seafloor. Consequently, sound channel propagation is everywhere bottom limited. The initial arrival of each airgun pulse shows a short rise time, often less than two seconds from initial arrival to peak amplitude; however the coda duration often exceeds sixty seconds. This can be attributed to multipath propagation and seafloor scattering during multiple reflections from the seafloor. Moreover, received level (rms re 1uPa at 1m) versus range data indicate a transmission loss greater than 20log(range), thus exceeding the prediction for a purely spherical spreading model. This also is explained by strong interaction with the seafloor in this bottom-limited setting. The purpose of this paper is to quantify received signal characteristics of the airgun shots and compare predicted variability from numerical models with the observed variability. The results will improve source level estimates for volcanic and tectonic signals within the Lau Basin. They also will be used to assess the possible environmental impacts of further active-source seismic work in bottom-limited settings.

  15. On the Clarification of Concepts: A Reply to Gallistel (2007) and Lau (2007)

    Science.gov (United States)

    Machado, Armando; Silva, Francisco J.

    2007-01-01

    The authors argue that some of C. R. Gallistel's and H. C. Lau's solutions to the problems raised in the article by A. Machado and F. J. Silva are unlikely, logically inconsistent, or at odds with empirical evidence. In particular, Lau seems not to appreciate the necessity of clear and consistent psychological constructs before trying to map these…

  16. Microbiology of Low Temperature Seafloor Deposits Along a Geochemical Gradient in Lau Basin

    Science.gov (United States)

    sylvan, J. B.; Sia, T. Y.; Haddad, A.; Briscoe, L. J.; Girguis, P. R.; Edwards, K. J.

    2011-12-01

    The East Lau Spreading Center (ELSC) and Valu Fa Ridge comprise a ridge segment in the southwest Pacific Ocean where rapid transitions in the underlying mantle lenses manifest themselves by gradients in seafloor rock geochemistry. At the spreading center in the north, basaltic host rock extrudes while the influence of subduction in the south creates mainly basaltic andesite host rock. A contuous gradient between these two end members exists along the spreading center. We studied the geology and microbial diversity of three silicate rock samples and three inactive sulfide chimney samples collected along the ELSC and Valu Fa Ridge by X-ray diffraction, elemental analysis, thin section analysis and construction of bacterial 16S rRNA clone libraries. Here, we discuss the geological and biological differences between the collected rocks. We found that the bacterial community composition changed as the host rock mineralogy and chemistry changed from north to south. Also, the bacterial community composition on the silicates is distinct from those on the inactive chimneys, and the interior conduit of an inactive chimney hosts a very different community from the exterior. Basalt from the northern end of the ELSC had high proportions of Alphaproteobacteria and Bacteroidetes. These proportions decreased on the silicates collected further south. Epsilonproteobacteria were also present on the basalt, decreased further south and were absent on the basaltic andesite. Conversely, basaltic andesite rocks from the southern end had high proportions of Chloroflexi, which decreased further north and were absent on basalt. The exterior of inactive sulfide structures were dominated by lineages of sulfur oxidizing Gammaproteobacteria and Epsilonproteobacteria and were less diverse than those on the silicates. The interior of one chimney was dominated by sulfate-reducing Deltaproteobacteria and was the least diverse of all samples. These results support the Mantle to Microbe hypothesis in

  17. Forest Plant and Bird Communities in the Lau Group, Fiji

    Science.gov (United States)

    Franklin, Janet; Steadman, David W.

    2010-01-01

    Background We examined species composition of forest and bird communities in relation to environmental and human disturbance gradients on Lakeba (55.9 km2), Nayau (18.4 km2), and Aiwa Levu (1.2 km2), islands in the Lau Group of Fiji, West Polynesia. The unique avifauna of West Polynesia (Fiji, Tonga, Samoa) has been subjected to prehistoric human-caused extinctions but little was previously known about this topic in the Lau Group. We expected that the degree of human disturbance would be a strong determinant of tree species composition and habitat quality for surviving landbirds, while island area would be unrelated to bird diversity. Methodology/Principal Findings All trees >5 cm diameter were measured and identified in 23 forest plots of 500 m2 each. We recognized four forest species assemblages differentiated by composition and structure: coastal forest, dominated by widely distributed species, and three forest types with differences related more to disturbance history (stages of secondary succession following clearing or selective logging) than to environmental gradients (elevation, slope, rockiness). Our point counts (73 locations in 1 or 2 seasons) recorded 18 of the 24 species of landbirds that exist on the three islands. The relative abundance and species richness of birds were greatest in the forested habitats least disturbed by people. These differences were due mostly to increased numbers of columbid frugivores and passerine insectivores in forests on Lakeba and Aiwa Levu. Considering only forested habitats, the relative abundance and species richness of birds were greater on the small but completely forested (and uninhabited) island of Aiwa Levu than on the much larger island of Lakeba. Conclusions/Significance Forest disturbance history is more important than island area in structuring both tree and landbird communities on remote Pacific islands. Even very small islands may be suitable for conservation reserves if they are protected from human

  18. Post-Lau Event (late Ludfordian, Silurian) recovery of conodont faunas of Bohemia

    Czech Academy of Sciences Publication Activity Database

    Slavík, Ladislav; Carls, P.

    2012-01-01

    Roč. 87, č. 4 (2012), s. 815-832 ISSN 1214-1119 R&D Projects: GA ČR GA205/09/0703 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : late Silurian * Ludfordian * post-Lau Event, * conodont recovery * Lau Event, Prague Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.141, year: 2012

  19. Geodynamic implications for zonal and meridional isotopic patterns across the northern Lau and North Fiji Basins

    Science.gov (United States)

    Price, Allison A.; Jackson, Matthew G.; Blichert-Toft, Janne; Kurz, Mark D.; Gill, Jim; Blusztajn, Jerzy; Jenner, Frances; Brens, Raul; Arculus, Richard

    2017-03-01

    We present new Sr-Nd-Pb-Hf-He isotopic data for 65 volcanic samples from the northern Lau and North Fiji Basins. This includes 47 lavas obtained from 40 dredge sites spanning an east-west transect across the Lau and North Fiji basins, 10 ocean island basalt (OIB)-type lavas collected from seven Fijian islands, and eight OIB lavas sampled on Rotuma. For the first time, we are able to map clear north-south and east-west geochemical gradients in 87Sr/86Sr across the northern Lau and North Fiji Basins: lavas with the most geochemically enriched radiogenic isotopic signatures are located in the northeast Lau Basin, while signatures of geochemical enrichment are diminished to the south and west away from the Samoan hot spot. Based on these geochemical patterns and plate reconstructions of the region, these observations are best explained by the addition of Samoa, Rurutu, and Rarotonga hot spot material over the past 4 Ma. We suggest that underplated Samoan material has been advected into the Lau Basin over the past ˜4 Ma. As the slab migrated west (and toward the Samoan plume) via rollback over time, younger and hotter (and therefore less viscous) underplated Samoan plume material was entrained. Thus, entrainment efficiency of underplated plume material was enhanced, and Samoan plume signatures in the Lau Basin became stronger as the trench approached the Samoan hot spot. The addition of subducted volcanoes from the Cook-Austral Volcanic Lineament first from the Rarotonga hot spot, then followed by the Rurutu hot spot, contributes to the extreme geochemical signatures observed in the northeast Lau Basin.

  20. Low temperature geomicrobiology follows host rock composition along a geochemical gradient in Lau Basin

    Directory of Open Access Journals (Sweden)

    Jason B Sylvan

    2013-03-01

    Full Text Available The East Lau Spreading Center (ELSC and Valu Fa Ridge (VFR comprise a ridge segment in the southwest Pacific Ocean where rapid transitions in the underlying mantle chemistry manifest themselves as gradients in seafloor rock geochemistry. We studied the geology and microbial diversity of three silicate rock samples and three inactive sulfide chimney samples collected, from north to south, at the vent fields Kilo Moana, ABE, Tui Malila and Mariner. This is the first study of microbial populations on basaltic andesite, which was sampled at Mariner vent field. Silicate rock geochemistry exhibits clear latitudinal trends that are mirrored by changes in bacterial community composition. α-proteobacteria, ε-proteobacteria and Bacteroidetes are most common on a silicate collected from Kilo Moana and their proportions decrease linearly on silicates collected further south. Conversely, a silicate from Mariner vent field hosts high proportions of a unique lineage of Chloroflexi unrelated (<90% sequence similarity to previously recovered environmental clones or isolates, which decrease at ABE and are absent at Kilo Moana. The exteriors of inactive sulfide structures are dominated by lineages of sulfur oxidizing α-proteobacteria, γ-proteobacteria and ε-proteobacteria while the interior of one chimney is dominated by putative sulfur-reducing δ-proteobacteria. A comparison of bacterial communities on inactive sulfides from this and previous studies reveals the presence of a clade of uncultured Bacteroidetes exclusive to sulfidic environments, and a high degree of heterogeneity in bacterial community composition from one sulfide structure to another. In light of the heterogeneous nature of bacterial communities observed here and in previous studies of both active and inactive hydrothermal sulfide structures, the presence of numerous niches may be detected on these structures in the future by finer scale sampling and analysis.

  1. [INCIDENCE, PREDISPOSING RISK FACTORS FOR THE DEVELOPMENT AND SPREADING OF ACUTE INTESTINAL INFECTIONS IN THE NORTH-EASTERN REGION OF UKRAINE].

    Science.gov (United States)

    Malysh, N G; Chemych, N D; Zaritsky, A M

    2016-01-01

    Using data of the branch statistical reporting of the State Sanitary and Epidemiological Service in Sumy region and Sumy Regional State Laboratory of Veterinary Medicine, the incidence rate, modern risk factors for the development and spreading of acute infectious diarrheas were determined in the North-Eastern region of Ukraine. Under the current conditions incidence rate indices of acute intestinal infections and food toxicoinfections are within the range of 159.8-193.6 per 100 thousands. pop. Seasonal and epidemical rises are associated with a species of the agent. In the etiological structure of acute diarrheal infections there are dominated viruses, of food toxicoinfections--Klebsiellae pneumoniae, Staphylococcus aureus and Enterobacter cloacae (p < 0.05). Predictors of the complication of epidemiological situation of Shigella infections are the gain in the detection of bacterially contaminated samples of milk and dairy products (r = 0.75), for food toxicoinfections caused by Klebsiellae pneumoniae and Enterobacter cloacae--pastry with cream and cooking meat products (r = 0.64; r = 0.75). Epizootic situation in the region affects on the salmonellosis incidence rate of the population (r = 0.89). There were revealed correlations between the selection of E. coli bacteria from swabs taken from the enterprises of catering, in child care centers and the levels of incidence rates of salmonellosis, acute intestinal infections of unknown etiology (r = 0.59; r = 0.60). Timely detection and sanitation of Shigella carriers are a powerful instrument to reduce the incidence rate of shigellosis (r = 0.83).

  2. Uranium disequilibrium dating of phosphate deposits from the Lau Group, Fiji

    International Nuclear Information System (INIS)

    Roe, K.K.; Burnett, W.C.

    1983-01-01

    A determination of the absolute age of two phosphate deposits in the Lau Group, Fiji by uranium-series disequilibrium techniques is reported. These measurements were undertaken in order to assist in the evaluation of their origin in terms of known palaeoclimatic information. (U.K.)

  3. An observation on inappropriate probiotic subgroup classifications in the meta-analysis by Lau and Chamberlain

    Directory of Open Access Journals (Sweden)

    McFarl

    2016-09-01

    Full Text Available Lynne V McFarland Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA I read with great interest the systematic review of meta-analysis assessing probiotics for the prevention of Clostridium difficile-associated diarrhea (CDAD published in the International Journal of General Medicine. These authors pooled 26 randomized controlled trials (RCTs and concluded that Lactobacilli, mixtures, and Saccharomyces probiotics were effective in preventing CDAD. However, the meta-analysis by Lau and Chamberlain is flawed due to improper classification by the types of probiotics. It is important to recognize that the efficacy of probiotics for various diseases has been shown to be strain specific for each probiotic product, and thus the data should only be pooled for probiotics that are of the identical type. In their analysis of probiotic subgroups by various species, the authors have inappropriately merged different types of Lactobacilli into one subgroup “Lactobacilli” and different types of mixtures into one group classified as “Mix”.View the original paper by Lau and Chamberlain. 

  4. Water mass spreading in the warm water sphere of the eastern subtropical North Atlantic. Wassermassenausbreitung in der Warmwassersphaere des subtropischen Nordostatlantiks

    Energy Technology Data Exchange (ETDEWEB)

    Stramma, L

    1984-01-01

    Geostrophic transports in the eastern subtropical North Atlantic computed from historic hydrographic data and recent CTD measurements show a mean transport in the subtropical gyre of 11(+-1.6) x 10/sup 6/m/sup 3/s/sup -1/ in the upper 1000 m between 35/sup 0/W and the African coast. The dynamic method was used in conjunction with a conservation of mass scheme to determine the level of no motion. This level lies at the 1200 m depth near the Azores and drops to 1500 m in the tropics. The main inflow enters south of the Azores as a relatively narrow current, turns southward at the latitude of Madeira and then widens. Three current bands transport the water southward. North of the Cape Verde Islands, the current turns westwards. This part of the North Equatorial Current extends more to the south in the upper 200 m than in the 200-800 m layer. The Portugal current, between the Azores and the Portuguese coast, which is thought by some authors to be strong, is seen here as a relatively weak flow. Maps of potential vorticity derived from smoothed density profiles are consistent with the general pattern of geostrophic transport. At 24/sup 0/N one third of the total geostrophic southward transport of the recirculation and one third of the temperature flux is transported in the eastern Atlantic east of 35/sup 0/W.

  5. Microelement contents and fatty acid compositions of Rhus coriaria L. and Pistacia terebinthus L. fruits spread commonly in the south eastern Anatolia region of Turkey.

    Science.gov (United States)

    Kizil, Suleyman; Turk, Murat

    2010-01-01

    Sumac (Rhus coriaria L.) and terebinth (Pistacia terebinthus L.) are two important spice plants of south eastern Anatolia, Turkey. Nutrients, physical properties including moisture, ash, dry matter, protein, fatty oil and essential oil content, along with Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Na, Ni, Pb, Zn and characteristics of fruit sizes and fatty acid compositions of both plants were determined from ripe fruits. The free fatty acid content was determined in the fruit oil, and the main fatty acids of sumac and terebinth were identified by gas chromatography/mass spectrometry. They included oleic, linoleic, palmitic and stearic acids in a ratio of 37.7% and 34.8%, 27.4% and 17.3%, 21.1% and 21.7% and, 4.7% and 2.5%, respectively. The fruits of both plants were rich in oil, fatty acids and minerals, suggesting that they are valuable for using in food. The data may also be useful for the evaluation of nutritional information.

  6. The use of climatic niches in screening procedures for introduced species to evaluate risk of spread: a case with the American Eastern grey squirrel.

    Directory of Open Access Journals (Sweden)

    Mirko Di Febbraro

    Full Text Available Species introduction represents one of the most serious threats for biodiversity. The realized climatic niche of an invasive species can be used to predict its potential distribution in new areas, providing a basis for screening procedures in the compilation of black and white lists to prevent new introductions. We tested this assertion by modeling the realized climatic niche of the Eastern grey squirrel Sciurus carolinensis. Maxent was used to develop three models: one considering only records from the native range (NRM, a second including records from native and invasive range (NIRM, a third calibrated with invasive occurrences and projected in the native range (RCM. Niche conservatism was tested considering both a niche equivalency and a niche similarity test. NRM failed to predict suitable parts of the currently invaded range in Europe, while RCM underestimated the suitability in the native range. NIRM accurately predicted both the native and invasive range. The niche equivalency hypothesis was rejected due to a significant difference between the grey squirrel's niche in native and invasive ranges. The niche similarity test yielded no significant results. Our analyses support the hypothesis of a shift in the species' climatic niche in the area of introductions. Species Distribution Models (SDMs appear to be a useful tool in the compilation of black lists, allowing identifying areas vulnerable to invasions. We advise caution in the use of SDMs based only on the native range of a species for the compilation of white lists for other geographic areas, due to the significant risk of underestimating its potential invasive range.

  7. A preclinical Talbot-Lau prototype for x-ray dark-field imaging of human-sized objects.

    Science.gov (United States)

    Hauke, C; Bartl, P; Leghissa, M; Ritschl, L; Sutter, S M; Weber, T; Zeidler, J; Freudenberger, J; Mertelmeier, T; Radicke, M; Michel, T; Anton, G; Meinel, F G; Baehr, A; Auweter, S; Bondesson, D; Gaass, T; Dinkel, J; Reiser, M; Hellbach, K

    2018-03-26

    Talbot-Lau x-ray interferometry provides information about the scattering and refractive properties of an object - in addition to the object's attenuation features. Until recently, this method was ineligible for imaging human-sized objects as it is challenging to adapt Talbot-Lau interferometers (TLIs) to the relevant x-ray energy ranges. In this work, we present a preclinical Talbot-Lau prototype capable of imaging human-sized objects with proper image quality at clinically acceptable dose levels. The TLI is designed to match a setup of clinical relevance as closely as possible. The system provides a scan range of 120 × 30 cm 2 by using a scanning beam geometry. Its ultimate load is 100 kg. High aspect ratios and fine grid periods of the gratings ensure a reasonable setup length and clinically relevant image quality. The system is installed in a university hospital and is, therefore, exposed to the external influences of a clinical environment. To demonstrate the system's capabilities, a full-body scan of a euthanized pig was performed. In addition, freshly excised porcine lungs with an extrinsically provoked pneumothorax were mounted into a human thorax phantom and examined with the prototype. Both examination sequences resulted in clinically relevant image quality - even in the case of a skin entrance air kerma of only 0.3 mGy which is in the range of human thoracic imaging. The presented case of a pneumothorax and a reader study showed that the prototype's dark-field images provide added value for pulmonary diagnosis. We demonstrated that a dedicated design of a Talbot-Lau interferometer can be applied to medical imaging by constructing a preclinical Talbot-Lau prototype. We experienced that the system is feasible for imaging human-sized objects and the phase-stepping approach is suitable for clinical practice. Hence, we conclude that Talbot-Lau x-ray imaging has potential for clinical use and enhances the diagnostic power of medical x-ray imaging.

  8. X-ray phase scanning setup for non-destructive testing using Talbot-Lau interferometer

    Science.gov (United States)

    Bachche, S.; Nonoguchi, M.; Kato, K.; Kageyama, M.; Koike, T.; Kuribayashi, M.; Momose, A.

    2016-09-01

    X-ray grating interferometry has a great potential for X-ray phase imaging over conventional X-ray absorption imaging which does not provide significant contrast for weakly absorbing objects and soft biological tissues. X-ray Talbot and Talbot-Lau interferometers which are composed of transmission gratings and measure the differential X-ray phase shifts have gained popularity because they operate with polychromatic beams. In X-ray radiography, especially for nondestructive testing in industrial applications, the feasibility of continuous sample scanning is not yet completely revealed. A scanning setup is frequently advantageous when compared to a direct 2D static image acquisition in terms of field of view, exposure time, illuminating radiation, etc. This paper demonstrates an efficient scanning setup for grating-based Xray phase imaging using laboratory-based X-ray source. An apparatus consisting of an X-ray source that emits X-rays vertically, optical gratings and a photon-counting detector was used with which continuously moving objects across the field of view as that of conveyor belt system can be imaged. The imaging performance of phase scanner was tested by scanning a long continuous moving sample at a speed of 5 mm/s and absorption, differential-phase and visibility images were generated by processing non-uniform moire movie with our specially designed phase measurement algorithm. A brief discussion on the feasibility of phase scanner with scanning setup approach including X-ray phase imaging performance is reported. The successful results suggest a breakthrough for scanning objects those are moving continuously on conveyor belt system non-destructively using the scheme of X-ray phase imaging.

  9. The peptidomimetic Lau-(Lys-βNSpe)6-NH2 antagonizes formyl peptide receptor 2 expressed in mouse neutrophils

    DEFF Research Database (Denmark)

    Skovbakke, Sarah Line; Winther, Malene; Gabl, Michael

    2016-01-01

    /differences between the human and murine FPR family members is required. Compared to FPR1 and FPR2 expressed by human neutrophils, very little is known about agonist/antagonist recognition patterns for their murine orthologues, but now we have identified two potent and selective formylated peptide agonists (f...... to be devoid of effect on their murine orthologues as determined by their inability to inhibit superoxide release from murine neutrophils upon stimulation with receptor-specific agonists. The Boc-FLFLF peptide was found to be a selective antagonist for Fpr1, whereas the lipidated peptidomimetic Lau...

  10. The effectiveness of new austrian tunnelling method (NATM for hydro power plant construction: lau gunung power plant, north sumatera, indonesia

    Directory of Open Access Journals (Sweden)

    Ade Khoir Rizki

    2017-01-01

    Full Text Available Hydro Electric Power Plant is a power generating system using gravity fall of water as the main force to move the turbine and generate electricity. The construction purpose of Lau Gunung hydropower (2×7. 5 MW that is located in Dairi, North Sumatra, is to Supply power to 14,000 house of the surrounding region. The river run-off system, where the water is immediately contained and then flowed through a tunnel considering the discharge flowing river, where it is constant and does not occur in the fluctuating water level. The Lau Gunung river has the minimum flow that can exceed from 15 to 25 m3/s with a high tunnel dimensions of 4 metres long, 3,9 metres wide and a length of 1,6 kilometres. In terms of the analysis of the time effectiveness of the NATM can be saved because of the continuous work of 24 hours, without any obstacles in which the sub methods used include the drilling & blasting. The tunnel then use the form of steel reinforcement rib and Safety shotcrete lining. The general review may show that using NATM result a tremendous savings, also the use of horse shape conduce small displacement which is effective for the construction.

  11. A Win-Win Paradigm for Quality of Work Life and Business Performance. [and] Invited Reaction: Comments on Lau and May's Study.

    Science.gov (United States)

    Lau, R. S. M.; May, Bruce E.; Schurman, Susan J.

    1998-01-01

    Lau and May's study of 58 "best U.S. companies to work for" and 88 top Standard and Poor's companies suggests that companies with high quality of working life can also enjoy exceptional growth and profitability. Schurman's critique notes that their sample does not reflect conditions in the majority of U.S. employers. (SK)

  12. An x-ray backlit Talbot-Lau deflectometer for high-energy-density electron density diagnostics

    Science.gov (United States)

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Theobald, W.; Mileham, C.; Begishev, I. A.; Bromage, J.; Regan, S. P.

    2016-02-01

    X-ray phase-contrast techniques can measure electron density gradients in high-energy-density plasmas through refraction induced phase shifts. An 8 keV Talbot-Lau interferometer consisting of free standing ultrathin gratings was deployed at an ultra-short, high-intensity laser system using K-shell emission from a 1-30 J, 8 ps laser pulse focused on thin Cu foil targets. Grating survival was demonstrated for 30 J, 8 ps laser pulses. The first x-ray deflectometry images obtained under laser backlighting showed up to 25% image contrast and thus enabled detection of electron areal density gradients with a maximum value of 8.1 ± 0.5 × 1023 cm-3 in a low-Z millimeter sized sample. An electron density profile was obtained from refraction measurements with an error of x-ray source-size, similar to conventional radiography.

  13. Lipdub-ak, gizarte-lorpenak erdiesteko lanabes gisara. Quebec, AEB, Katalunia eta Euskal Herrian egindako lau kasu paradigmatikoen azterketa

    Directory of Open Access Journals (Sweden)

    Txema Ramírez de la Piscina Martínez

    2013-01-01

    Full Text Available Artikulu honek laburbiltzen ditu egileak egindako ikerketa baten emaitzak. Berton, lipdub-en fenomenoa aztertu da; zehatzago esanda, nolatan gizarte mugimenduek erabili dezaketen tresna hau gizartean eragin handiagoa lortzeko bidean. Azterketa honetan, autoreak Youtuben inpaktu handia izan duten lau adibide esanguratsu aztertu ditu: “I gotta feeling-UQAM”, Quebec-eko Komunikazioko ikasleek egindakoak (2012ko urtarrilean Internet-en bisita gehien zituen bideoa zen; “The Grand Rapids” (lipdub honek eguneko bisita kopururik handiena zuen orduan; “Lipdub Independència” (lipdub honek orduan lortu zuen parte-hartzaile gehien izatearen mundu-marka, 5.771 pertsonekin eta, azkenik, “Lipdub Kukutza”, Euskal Herrian egindako tipo honetako bideoen artean bisita gehien zituena. Lan honek azpimarratzen du lipdub-ak gizarte mugimenduentzat lanabes garrantzitsuak izan daitezkeela, batetik masa-hedabideetan nagusi diren joerei aurre egiteko eta, bestetik, mugimenduei beraiei komunikabideek sarritan ezartzen dieten ikusezintasuna gainditu ahal izateko.

  14. How Is Mono Spread?

    Science.gov (United States)

    ... How Is Mono Spread? Print My sister has mononucleosis. I drank out of her drink before we ... that I have mono now? – Kyle* Mono, or mononucleosis, is spread through direct contact with saliva. This ...

  15. J. Laužiko edukacinės idėjos tąsa ieškant optimalaus sociopedagoginio poveikio modelių

    OpenAIRE

    Kvieskienė, Giedrė; Merfeldaitė, Odeta

    2003-01-01

    On the basis of J. Laužikas’ ideas of social education at school, the article analyses the model of activity used by a social pedagogical team at school; examines the possibilities for the community of solving social pedagogical problems (interaction between educatees and the team); presents the sociopedagogical team module – interaction and functions of team members; and analyses the role of the main team leader – social pedagogue.

  16. Comment on ‘A new method for fusion, denoising and enhancement of x-ray images retrieved from Talbot–Lau grating interferometry’

    International Nuclear Information System (INIS)

    Scholkmann, Felix; Revol, Vincent; Kaufmann, Rolf; Kottler, Christian

    2015-01-01

    In a recent paper (Scholkamm et al 2014 Phys. Med. Biol. 59 1425–40) we presented a new image denoising, fusion and enhancement framework for combining and optimal visualization of x-ray attenuation contrast, differential phase contrast and dark-field contrast images retrieved from x-ray Talbot–Lau grating interferometry. In this comment we give additional information and report about the application of our framework to breast cancer tissue which we presented in our paper as an example. The applied procedure is suitable for a qualitative comparison of different algorithms. For a quantitative juxtaposition original data would however be needed as an input. (comment and reply)

  17. Paleocene on-spreading-axis hotspot volcanism along the Ninetyeast Ridge: An interaction between the Kerguelen hotspot and the Wharton spreading center

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Gopala Rao, D.; SubbaRaju, L.V.; Chaubey, A.K.; Shcherbakov, V.S.; Pilipenko, A.I.; Murthy, I.V.R.

    with magnetic lineations and abondoned spreading centers of the eastern Indian Ocean and seismic structure and radiometric dates of the Ninetyeast Ridge. Furthermore, it is supported by the occurrence of oceanic andesites at Deep Sea Drilling Project (DSDP) Site...

  18. Optimizing Hybrid Spreading in Metapopulations.

    OpenAIRE

    Zhang, C.; Zhou, S.; Miller, J. C.; Cox, I. J.; Chain, B. M.

    2015-01-01

    Epidemic spreading phenomena are ubiquitous in nature and society. Examples include the spreading of diseases, information, and computer viruses. Epidemics can spread by local spreading, where infected nodes can only infect a limited set of direct target nodes and global spreading, where an infected node can infect every other node. In reality, many epidemics spread using a hybrid mixture of both types of spreading. In this study we develop a theoretical framework for studying hybrid epidemic...

  19. Optimizing Hybrid Spreading in Metapopulations

    OpenAIRE

    Zhang, Changwang; Zhou, Shi; Miller, Joel C.; Cox, Ingemar J.; Chain, Benjamin M.

    2014-01-01

    Epidemic spreading phenomena are ubiquitous in nature and society. Examples include the spreading of diseases, information, and computer viruses. Epidemics can spread by local spreading, where infected nodes can only infect a limited set of direct target nodes and global spreading, where an infected node can infect every other node. In reality, many epidemics spread using a hybrid mixture of both types of spreading. In this study we develop a theoretical framework for studying hybrid epidemic...

  20. Spread effects - methodology

    International Nuclear Information System (INIS)

    2004-01-01

    Diffusion of technology, environmental effects and rebound effects are the principal effects from the funding of renewable energy and energy economising. It is difficult to estimate the impact of the spread effects both prior to the measures are implemented and after the measures are carried out. Statistical methods can be used to estimate the spread effects, but they are insecure and always need to be complemented with qualitative and subjective evaluations. It is more adequate to evaluate potential spread effects from market and market data surveillance for a selection of technologies and parties. Based on this information qualitative indicators for spread effects can be constructed and used both ex ante and ex post (ml)

  1. Ocean, Spreading Centre

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.

    over the global midoceanic ridges have found some explicit relationships between spreading rate, seismic structure, and ridge-axis morphology. Bibliography Detrick, R. S., Buhl, P., Vera, E., Mutter, J., Orcutt, J., Madsen, J., and Brocher, T., 1987...

  2. The VULCANO spreading programme

    Energy Technology Data Exchange (ETDEWEB)

    Cognet, G.; Laffont, G.; Jegou, C.; Journeau, C.; Sudreau, F.; Pierre, J.; Ramacciotti, M. [CEA (Atomic Energy Commission), DRN/DER - Bat. 212, CEA Cadarache, 13108 St. Paul Lez Durance (France)

    1999-07-01

    Among the currently studied core-catcher projects, some of them suppose corium spreading before cooling, in particular the EPR (European Pressurized Reactor) core-catcher concept is based on mixing the corium with a special concrete, spreading the molten mixture on a large multi-layer surface cooled from the bottom and subsequently cooling by flooding with water. Therefore, melt spreading deserves intensive investigation in order to determine and quantify key phenomena which govern the stopping of spreading. In France, for some years, the Nuclear Reactor Division of the Atomic Energy Commission (CEA/DRN) has undertaken a large program to improve knowledge on corium behaviour and coolability. This program is based on experimental and theoretical investigations which are finally gathered in scenario and mechanistic computer codes. In this framework, the real material experimental programme, VULCANO, conducted within an European frame, is currently devoted to the study of corium spreading. In 1997 and 1998, several tests have been performed on dry corium spreading with various composition of melts. Although all the observed phenomena, in particular the differences between simulant and real material melts have not been yet totally explained, these tests have already provided a lot of information about: The behaviour of complex mixtures including refractory oxides, silica, iron oxides and in one case iron metal; Spreading progression, which was never stopped in any of these tests by a crust formation at the front; The structure of spread melts (porosity, crusts,...); Physico-chemical interaction between melt and the refractory substratum which was composed of zirconia bricks. (authors)

  3. The VULCANO spreading programme

    International Nuclear Information System (INIS)

    Cognet, G.; Laffont, G.; Jegou, C.; Journeau, C.; Sudreau, F.; Pierre, J.; Ramacciotti, M.

    1999-01-01

    Among the currently studied core-catcher projects, some of them suppose corium spreading before cooling, in particular the EPR (European Pressurized Reactor) core-catcher concept is based on mixing the corium with a special concrete, spreading the molten mixture on a large multi-layer surface cooled from the bottom and subsequently cooling by flooding with water. Therefore, melt spreading deserves intensive investigation in order to determine and quantify key phenomena which govern the stopping of spreading. In France, for some years, the Nuclear Reactor Division of the Atomic Energy Commission (CEA/DRN) has undertaken a large program to improve knowledge on corium behaviour and coolability. This program is based on experimental and theoretical investigations which are finally gathered in scenario and mechanistic computer codes. In this framework, the real material experimental programme, VULCANO, conducted within an European frame, is currently devoted to the study of corium spreading. In 1997 and 1998, several tests have been performed on dry corium spreading with various composition of melts. Although all the observed phenomena, in particular the differences between simulant and real material melts have not been yet totally explained, these tests have already provided a lot of information about: The behaviour of complex mixtures including refractory oxides, silica, iron oxides and in one case iron metal; Spreading progression, which was never stopped in any of these tests by a crust formation at the front; The structure of spread melts (porosity, crusts,...); Physico-chemical interaction between melt and the refractory substratum which was composed of zirconia bricks. (authors)

  4. Hydrothermal Fe-Si-Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

    International Nuclear Information System (INIS)

    Sun Zhilei; Zhou Huaiyang; Yang Qunhui; Sun Zhixue; Bao Shenxu; Yao Huiqiang

    2011-01-01

    Highlights: → The Fe-Mn crust in the HHF has seawater contribution, whereas the Fe-Si oxide in the MHF is dominated by hydrothermal fluid → The Nd isotope of diffuse flow Fe-Si-Mn deposits indicates the obvious hydrothermal origin. → The Mn/Fe ratio in hydrothermal deposit may be a good indicator of propagating activities of the Valu Fa Ridge. - Abstract: A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe-Si-Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Moessbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe-Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ΣREE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe-Si-Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.

  5. Eastern Europe

    International Nuclear Information System (INIS)

    Baret, J.P.; Corcuff, A.; Jousten, M.; Cherie, J.B.; Gorge, X.; Augustin, X.; Belime, F.

    1999-01-01

    By its economical and political impact, nuclear energy has an important contribution the countries of Eastern Europe that goes beyond simple energy source. The most important challenge is to gain a safety culture. Improvements have been noted but the reactors safety must stay a priority of the international cooperation in Eastern Europe. The plan for the completion and improvement of Mochovce nuclear plant is described, the situation of Chernobyl and how to make the sarcophagus in safe is discussed, the experience of a french P.M.E. ( small and medium size firm) called Corys Tess that has chosen to position itself on the Eastern Europe nuclear market is related. (N.C.)

  6. Knowledge of and misconceptions about the spread and prevention ...

    African Journals Online (AJOL)

    2009-05-27

    May 27, 2009 ... and misconceptions regarding the spread and prevention of HIV in ... personal items, air-borne infection, mosquito bites, HIV testing and AIDS prevention or cure by traditional medicines or .... related stigmatisation, discrimination, isolation and the ... services to the patients living in the central and eastern.

  7. Optimizing hybrid spreading in metapopulations.

    Science.gov (United States)

    Zhang, Changwang; Zhou, Shi; Miller, Joel C; Cox, Ingemar J; Chain, Benjamin M

    2015-04-29

    Epidemic spreading phenomena are ubiquitous in nature and society. Examples include the spreading of diseases, information, and computer viruses. Epidemics can spread by local spreading, where infected nodes can only infect a limited set of direct target nodes and global spreading, where an infected node can infect every other node. In reality, many epidemics spread using a hybrid mixture of both types of spreading. In this study we develop a theoretical framework for studying hybrid epidemics, and examine the optimum balance between spreading mechanisms in terms of achieving the maximum outbreak size. We show the existence of critically hybrid epidemics where neither spreading mechanism alone can cause a noticeable spread but a combination of the two spreading mechanisms would produce an enormous outbreak. Our results provide new strategies for maximising beneficial epidemics and estimating the worst outcome of damaging hybrid epidemics.

  8. Spread of Canine Flu

    Centers for Disease Control (CDC) Podcasts

    2018-04-05

    Dr. Colin Parrish, a Professor of Virology at the College of Veterinary Medicine, Cornell University, discusses the spread of influenza among dogs.  Created: 4/5/2018 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 4/5/2018.

  9. Combinatorics of spreads and parallelisms

    CERN Document Server

    Johnson, Norman

    2010-01-01

    Partitions of Vector Spaces Quasi-Subgeometry Partitions Finite Focal-SpreadsGeneralizing André SpreadsThe Going Up Construction for Focal-SpreadsSubgeometry Partitions Subgeometry and Quasi-Subgeometry Partitions Subgeometries from Focal-SpreadsExtended André SubgeometriesKantor's Flag-Transitive DesignsMaximal Additive Partial SpreadsSubplane Covered Nets and Baer Groups Partial Desarguesian t-Parallelisms Direct Products of Affine PlanesJha-Johnson SL(2,

  10. Animal vectors of eastern dwarf mistletoe of black spruce.

    Science.gov (United States)

    Michael E. Ostry; Thomas H. Nicholls; D.W. French

    1983-01-01

    Describes a study to determine the importance of animals in the spread of eastern dwarf mistletoe of black spruce. Radio telemetry, banding, and color-marking techniques were used to study vectors of this forest pathogen.

  11. Spread spectrum image steganography.

    Science.gov (United States)

    Marvel, L M; Boncelet, C R; Retter, C T

    1999-01-01

    In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.

  12. Development of an x-ray Talbot-Lau moire deflectometer for fast density profile measurements of dense plasmas generated by beam-target interactions

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dan [National Security Technol., LLC, Los Alamos, NM (United States); Berninger, M; Meidinger, A; Stutman, Dan; Valdivia, Maria Pia

    2015-05-01

    For the first time an x-ray Talbot-Lau moire deflectometer is being developed that will use a flash tube source and fast detector for dynamic density gradient measurements. In Talbot-Lau moire deflectometry, an x-ray grating makes an image of itself on a second grating (the Talbot effect) to produce a moire pattern on a detector. The test object is placed between these gratings, with variations in index of refraction changing the pattern. A third grating in front of an incoherent x-ray source produces an array of coherent sources. With a 150 kV x-ray flash tube as the source, the gratings are placed in a glancing angle setup for performance at ~60 keV. The detector is a gated CCD with a fast scintillator for x-ray conversion. This diagnostic, designed for the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT) at Los Alamos National Laboratory, measures the density profile of dense plasma plumes ejected from beam-target interactions. DARHT has two high-current, pulsed, inductive linear electron accelerators with bremsstrahlung targets at the end of each beam line to create 2-D radiographic images of hydrodynamic tests. One multi-pulse accelerator has up to four beam pulses striking the same target within 2 μs. Computer simulations that model target evolution and ejected material between pulses are used to design these targets for optimal radiographic performance; the x-ray deflectometer will directly measure density gradients in the ejected plumes and provide the first experimental constraints to these models. During the first year, currently underway, the diagnostic systems are being designed. In year two, the flash tube and fast detector will be deployed at DARHT for radiographic imaging while the deflectometer is built and tested on the bench with a continuous source. Finally, in year three, the fast deflectometer will be installed on DARHT and density measurements will be performed.

  13. Spreading convulsions, spreading depolarization and epileptogenesis in human cerebral cortex

    DEFF Research Database (Denmark)

    Dreier, Jens P; Major, Sebastian; Pannek, Heinz-Wolfgang

    2012-01-01

    Spreading depolarization of cells in cerebral grey matter is characterized by massive ion translocation, neuronal swelling and large changes in direct current-coupled voltage recording. The near-complete sustained depolarization above the inactivation threshold for action potential generating...... stimulations. Eventually, epileptic field potentials were recorded during the period that had originally seen spreading depression of activity. Such spreading convulsions are characterized by epileptic field potentials on the final shoulder of the large slow potential change of spreading depolarization. We...

  14. Estimation of wave directional spreading

    Digital Repository Service at National Institute of Oceanography (India)

    Deo, M.C.; Gondane, D.S.; SanilKumar, V.

    One of the useful measures of waves directional spreading at a given location is the directional spreading parameter. This paper presents a new approach to arrive at its characteristic value using the computational technique of Artificial Neural...

  15. Illusory spreading of watercolor.

    Science.gov (United States)

    Devinck, Frédéric; Hardy, Joseph L; Delahunt, Peter B; Spillmann, Lothar; Werner, John S

    2006-05-04

    The watercolor effect (WCE) is a phenomenon of long-range color assimilation occurring when a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour; the brighter color spreads into the entire enclosed area. Here, we determined the optimal chromatic parameters and the cone signals supporting the WCE. To that end, we quantified the effect of color assimilation using hue cancellation as a function of hue, colorimetric purity, and cone modulation of inducing contours. When the inner and outer contours had chromaticities that were in opposite directions in color space, a stronger WCE was obtained as compared with other color directions. Additionally, equal colorimetric purity between the outer and inner contours was necessary to obtain a large effect compared with conditions in which the contours differed in colorimetric purity. However, there was no further increase in the magnitude of the effect when the colorimetric purity increased beyond a value corresponding to an equal vector length between the inner and outer contours. Finally, L-M-cone-modulated WCE was perceptually stronger than S-cone-modulated WCE for our conditions. This last result demonstrates that both L-M-cone and S-cone pathways are important for watercolor spreading. Our data suggest that the WCE depends critically upon the particular spatiochromatic arrangement in the display, with the relative chromatic contrast between the inducing contours being particularly important.

  16. Hybrid spread spectrum radio system

    Science.gov (United States)

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  17. Spreading of rock avalanches

    Energy Technology Data Exchange (ETDEWEB)

    Kamis, A.S.; Savage, S.G. [McGill Univ., Dept. of Civil Engineering, Montreal, Quebec (Canada)

    1985-07-01

    Landslides and rockfalls that initiate on a steep slope eventually come to rest after flowing for some runout distance on a flat. Rockfalls of very large masses have been observed to exhibit unexpectedly long runout distances. This problem becomes more significant as the development of resources in mountain regions becomes more intensive. As early as 1881, Albert Heim observed and described the Elm rockfall of Switzerland (quoted by as HsU). This rockfall produced a debris which moved more than 2 Km along a nearly horizontal valley floor and one of its branches surged up the side of the valley to a height of 100 m. From the deposit of the Elm and the eyewitnesses Heim concluded that the debris behaved as a flowing fluid rather than sliding solids. Davies, among others, suggested that the excessive runout distance is volume dependent and the larger the volume of the debris, the longer the relative travel distance. A summary of the numerous hypotheses which have been proposed to explain this puzzling phenomena were also presented by Davies. However, none of these have been completely satisfactory or generally accepted. A simple model of the flow and spreading of a finite mass of cohesionless granular material down incline has been developed as a part of the present preliminary investigation into the mechanics of rockfalls. (author)

  18. Spreading Depression, Spreading Depolarizations, and the Cerebral Vasculature

    DEFF Research Database (Denmark)

    Ayata, Cenk; Lauritzen, Martin

    2015-01-01

    Spreading depression (SD) is a transient wave of near-complete neuronal and glial depolarization associated with massive transmembrane ionic and water shifts. It is evolutionarily conserved in the central nervous systems of a wide variety of species from locust to human. The depolarization spreads...

  19. Heat transfer and fire spread

    Science.gov (United States)

    Hal E. Anderson

    1969-01-01

    Experimental testing of a mathematical model showed that radiant heat transfer accounted for no more than 40% of total heat flux required to maintain rate of spread. A reasonable prediction of spread was possible by assuming a horizontal convective heat transfer coefficient when certain fuel and flame characteristics were known. Fuel particle size had a linear relation...

  20. Information spreading dynamics in hypernetworks

    Science.gov (United States)

    Suo, Qi; Guo, Jin-Li; Shen, Ai-Zhong

    2018-04-01

    Contact pattern and spreading strategy fundamentally influence the spread of information. Current mathematical methods largely assume that contacts between individuals are fixed by networks. In fact, individuals are affected by all his/her neighbors in different social relationships. Here, we develop a mathematical approach to depict the information spreading process in hypernetworks. Each individual is viewed as a node, and each social relationship containing the individual is viewed as a hyperedge. Based on SIS epidemic model, we construct two spreading models. One model is based on global transmission, corresponding to RP strategy. The other is based on local transmission, corresponding to CP strategy. These models can degenerate into complex network models with a special parameter. Thus hypernetwork models extend the traditional models and are more realistic. Further, we discuss the impact of parameters including structure parameters of hypernetwork, spreading rate, recovering rate as well as information seed on the models. Propagation time and density of informed nodes can reveal the overall trend of information dissemination. Comparing these two models, we find out that there is no spreading threshold in RP, while there exists a spreading threshold in CP. The RP strategy induces a broader and faster information spreading process under the same parameters.

  1. Spreading gossip in social networks

    Science.gov (United States)

    Lind, Pedro G.; da Silva, Luciano R.; Andrade, José S., Jr.; Herrmann, Hans J.

    2007-09-01

    We study a simple model of information propagation in social networks, where two quantities are introduced: the spread factor, which measures the average maximal reachability of the neighbors of a given node that interchange information among each other, and the spreading time needed for the information to reach such a fraction of nodes. When the information refers to a particular node at which both quantities are measured, the model can be taken as a model for gossip propagation. In this context, we apply the model to real empirical networks of social acquaintances and compare the underlying spreading dynamics with different types of scale-free and small-world networks. We find that the number of friendship connections strongly influences the probability of being gossiped. Finally, we discuss how the spread factor is able to be applied to other situations.

  2. Spread effects - methodology; Spredningseffekter - metodegrunnlag

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Diffusion of technology, environmental effects and rebound effects are the principal effects from the funding of renewable energy and energy economising. It is difficult to estimate the impact of the spread effects both prior to the measures are implemented and after the measures are carried out. Statistical methods can be used to estimate the spread effects, but they are insecure and always need to be complemented with qualitative and subjective evaluations. It is more adequate to evaluate potential spread effects from market and market data surveillance for a selection of technologies and parties. Based on this information qualitative indicators for spread effects can be constructed and used both ex ante and ex post (ml)

  3. Spreading gossip in social networks.

    Science.gov (United States)

    Lind, Pedro G; da Silva, Luciano R; Andrade, José S; Herrmann, Hans J

    2007-09-01

    We study a simple model of information propagation in social networks, where two quantities are introduced: the spread factor, which measures the average maximal reachability of the neighbors of a given node that interchange information among each other, and the spreading time needed for the information to reach such a fraction of nodes. When the information refers to a particular node at which both quantities are measured, the model can be taken as a model for gossip propagation. In this context, we apply the model to real empirical networks of social acquaintances and compare the underlying spreading dynamics with different types of scale-free and small-world networks. We find that the number of friendship connections strongly influences the probability of being gossiped. Finally, we discuss how the spread factor is able to be applied to other situations.

  4. Colonic motility and enema spreading

    International Nuclear Information System (INIS)

    Hardy, J.G.; Wood, E.; Clark, A.G.; Reynolds, J.R.; Queen's Medical Centre, Nottingham

    1986-01-01

    Radiolabelled enema solution was administered to eight healthy subjects, both in fasted and fed states. Enema spreading was monitored over a 4-h period using gamma scintigraphy and colonic motility was recorded simultaneously using a pressure sensitive radiotelemetry capsule. The rate and extent of enema dispersion were unaffected by eating. Spreading could be correlated with colonic motility and was inhibited by aboral propulsion of the colonic contents. (orig.)

  5. Mobility and the spread of human immunodeficiency virus into rural areas of West Africa

    NARCIS (Netherlands)

    Lagarde, E.; Schim van der Loeff, M.; Enel, C.; Holmgren, B.; Dray-Spira, R.; Pison, G.; Piau, J. P.; Delaunay, V.; M'Boup, S.; Ndoye, I.; Coeuret-Pellicer, M.; Whittle, H.; Aaby, P.

    2003-01-01

    In eastern and southern Africa, the human immunodeficiency virus (HIV) epidemic appeared first in urban centres and then spread to rural areas. Its overall prevalence is lower in West Africa, with the highest levels still found in cities. Rural areas are also threatened, however, because of the

  6. The role of concurrent sexual relationships in the spread of sexually ...

    African Journals Online (AJOL)

    The role of concurrent sexual relationships in the spread of sexually transmitted infections in young South Africans. C Kenyon, M Badri. Abstract. We still do not know why the HIV prevalence in southern and eastern Africa is an order of magnitude higher than anywhere else in the world. An article in this journal in 2007 ...

  7. Prevalence of blood parasites in eastern versus Western house finches: are eastern birds resistant to infection?

    Science.gov (United States)

    Davis, Andrew K; Hood, Wendy R; Hill, Geoffrey E

    2013-09-01

    The rapid spread of the bacterial disease, Mycoplasma gallisepticum (MG), throughout the introduced range of house finches (Carpodacus mexicanus) in eastern North America, compared to its slower spread through the native western range, has puzzled researchers and highlights the need to understand the relative differences in health state of finches from both populations. We conducted a light-microscope survey of hemoparasites in populations of finches from Arizona (within the western range) and from Alabama (within the eastern range), and compared our estimates of prevalence to published reports from house finches sampled in both ranges. Of the 33 Arizona birds examined, we recorded hematozoan infections in 16 (48.5%) individuals, compared to 1 infected Alabama bird out of 30 birds examined (3.3%). Based on independent surveys of seven western North American and five eastern North American populations of house finches the average prevalence of blood parasites in western populations is 38.8% (±17.9 SD), while the average prevalence within the eastern range is only 5.9% (±6.1 SD). The average rate of infection among all songbirds sampled in the east is 34.2% (±4.8 SD). Thus, our surveys of wild birds as well as previously published observations point to eastern house finches having a much lower prevalence of blood parasite infections than their western counterparts. Combined with the fact that eastern finches also tend to have lower rates of avian pox infections than do western birds (based on a literature review), these observations suggest that eastern birds have either strong resistance to these infections or high susceptibility and associated mortality.

  8. Spreading dynamics in complex networks

    Science.gov (United States)

    Pei, Sen; Makse, Hernán A.

    2013-12-01

    Searching for influential spreaders in complex networks is an issue of great significance for applications across various domains, ranging from epidemic control, innovation diffusion, viral marketing, and social movement to idea propagation. In this paper, we first display some of the most important theoretical models that describe spreading processes, and then discuss the problem of locating both the individual and multiple influential spreaders respectively. Recent approaches in these two topics are presented. For the identification of privileged single spreaders, we summarize several widely used centralities, such as degree, betweenness centrality, PageRank, k-shell, etc. We investigate the empirical diffusion data in a large scale online social community—LiveJournal. With this extensive dataset, we find that various measures can convey very distinct information of nodes. Of all the users in the LiveJournal social network, only a small fraction of them are involved in spreading. For the spreading processes in LiveJournal, while degree can locate nodes participating in information diffusion with higher probability, k-shell is more effective in finding nodes with a large influence. Our results should provide useful information for designing efficient spreading strategies in reality.

  9. Spreading dynamics in complex networks

    International Nuclear Information System (INIS)

    Pei, Sen; Makse, Hernán A

    2013-01-01

    Searching for influential spreaders in complex networks is an issue of great significance for applications across various domains, ranging from epidemic control, innovation diffusion, viral marketing, and social movement to idea propagation. In this paper, we first display some of the most important theoretical models that describe spreading processes, and then discuss the problem of locating both the individual and multiple influential spreaders respectively. Recent approaches in these two topics are presented. For the identification of privileged single spreaders, we summarize several widely used centralities, such as degree, betweenness centrality, PageRank, k-shell, etc. We investigate the empirical diffusion data in a large scale online social community—LiveJournal. With this extensive dataset, we find that various measures can convey very distinct information of nodes. Of all the users in the LiveJournal social network, only a small fraction of them are involved in spreading. For the spreading processes in LiveJournal, while degree can locate nodes participating in information diffusion with higher probability, k-shell is more effective in finding nodes with a large influence. Our results should provide useful information for designing efficient spreading strategies in reality. (paper)

  10. Dual polarized, heat spreading rectenna

    Science.gov (United States)

    Epp, Larry W. (Inventor); Khan, Abdur R. (Inventor); Smith, R. Peter (Inventor); Smith, Hugh K. (Inventor)

    1999-01-01

    An aperture coupled patch splits energy from two different polarization components to different locations to spread heat. In addition, there is no physical electrical connection between the slot, patch and circuitry. The circuitry is located under a ground plane which shields against harmonic radiation back to the RF source.

  11. The global spread of HIV-1 subtype B epidemic.

    Science.gov (United States)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G; Lepej, Snjezana J; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie-Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne-Mieke; Paraskevis, Dimitrios

    2016-12-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti to United States. However, the pattern of the subsequent spread still remains poorly understood. Here we analyze a large dataset of globally representative HIV-1 subtype B strains to map their spread around the world over the last 50years and describe significant spread patterns. We show that subtype B travelled from North America to Western Europe in different occasions, while Central/Eastern Europe remained isolated for the most part of the early epidemic. Looking with more detail in European countries we see that the United Kingdom, France and Switzerland exchanged viral isolates with non-European countries than with European ones. The observed pattern is likely to mirror geopolitical landmarks in the post-World War II era, namely the rise and the fall of the Iron Curtain and the European colonialism. In conclusion, HIV-1 spread through specific migration routes which are consistent with geopolitical factors that affected human activities during the last 50years, such as migration, tourism and trade. Our findings support the argument that epidemic control policies should be global and incorporate political and socioeconomic factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  12. Echinococcus multilocularis: An Emerging Pathogen in Hungary and Central Eastern Europe?

    Science.gov (United States)

    Sréter, Tamás; Széll, Zoltán; Egyed, Zsuzsa

    2003-01-01

    Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, is reported for the first time in Red Foxes (Vulpes vulpes) in Hungary. This parasite may be spreading eastward because the population of foxes has increased because of human interventions, and this spread may result in the emergence of alveolar echinococcosis in Central Eastern Europe. PMID:12643838

  13. Spreading of a granular droplet

    Science.gov (United States)

    Clement, Eric; Sanchez, Ivan; Raynaud, Franck; Lanuza, Jose; Andreotti, Bruno; Aranson, Igor

    2008-03-01

    The influence of controlled vibrations on the granular rheology is investigated in a specifically designed experiment in which a granular film spreads under the action of horizontal vibrations. A nonlinear diffusion equation is derived theoretically that describes the evolution of the deposit shape. A self-similar parabolic shape (the``granular droplet'') and a spreading dynamics are predicted that both agree quantitatively with the experimental results. The theoretical analysis is used to extract effective friction coefficients between the base and the granular layer under sustained and controlled vibrations. A shear thickening regime characteristic of dense granular flows is evidenced at low vibration energy, both for glass beads and natural sand. Conversely, shear thinning is observed at high agitation.

  14. Drop Spreading with Random Viscosity

    Science.gov (United States)

    Xu, Feng; Jensen, Oliver

    2016-11-01

    Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.

  15. Slip of Spreading Viscoplastic Droplets.

    Science.gov (United States)

    Jalaal, Maziyar; Balmforth, Neil J; Stoeber, Boris

    2015-11-10

    The spreading of axisymmetric viscoplastic droplets extruded slowly on glass surfaces is studied experimentally using shadowgraphy and swept-field confocal microscopy. The microscopy furnishes vertical profiles of the radial velocity using particle image velocimetry (PIV) with neutrally buoyant tracers seeded in the fluid. Experiments were conducted for two complex fluids: aqueous solutions of Carbopol and xanthan gum. On untreated glass surfaces, PIV demonstrates that both fluids experience a significant amount of effective slip. The experiments were repeated on glass that had been treated to feature positive surface charges, thereby promoting adhesion between the negatively charged polymeric constituents of the fluids and the glass surface. The Carbopol and xanthan gum droplets spread more slowly on the treated surface and to a smaller radial distance. PIV demonstrated that this reduced spreading was associated with a substantial reduction in slip. For Carbopol, the effective slip could be eliminated entirely to within the precision of the PIV measurements; the reduction in slip was less effective for xanthan gum, with a weak slip velocity remaining noticeable.

  16. Modeling potential Emerald Ash Borer spread through GIS/cell-based/gravity models with data bolstered by web-based inputs

    Science.gov (United States)

    Louis R. Iverson; Anantha M. Prasad; Davis Sydnor; Jonathan Bossenbroek; Mark W. Schwartz; Mark W. Schwartz

    2006-01-01

    We model the susceptibility and potential spread of the organism across the eastern United States and especially through Michigan and Ohio using Forest Inventory and Analysis (FIA) data. We are also developing a cell-based model for the potential spread of the organism. We have developed a web-based tool for public agencies and private individuals to enter the...

  17. Reverse preferential spread in complex networks

    Science.gov (United States)

    Toyoizumi, Hiroshi; Tani, Seiichi; Miyoshi, Naoto; Okamoto, Yoshio

    2012-08-01

    Large-degree nodes may have a larger influence on the network, but they can be bottlenecks for spreading information since spreading attempts tend to concentrate on these nodes and become redundant. We discuss that the reverse preferential spread (distributing information inversely proportional to the degree of the receiving node) has an advantage over other spread mechanisms. In large uncorrelated networks, we show that the mean number of nodes that receive information under the reverse preferential spread is an upper bound among any other weight-based spread mechanisms, and this upper bound is indeed a logistic growth independent of the degree distribution.

  18. Eastern Redcedar Seedling Assessment

    Data.gov (United States)

    U.S. Environmental Protection Agency — Eastern redcedar tree seedling growth in response to various soil, nitrogen, and photosynthetic radiation characteristics. This dataset is associated with the...

  19. Plume spread and atmospheric stability

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R O [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The horizontal spread of a plume in atmospheric dispersion can be described by the standard deviation of horizontal direction. The widely used Pasquill-Gifford classes of atmospheric stability have assigned typical values of the standard deviation of horizontal wind direction and of the lapse rate. A measured lapse rate can thus be used to estimate the standard deviation of wind direction. It is examined by means of a large dataset of fast wind measurements how good these estimates are. (author) 1 fig., 2 refs.

  20. Epidemic spreading on interconnected networks.

    Science.gov (United States)

    Saumell-Mendiola, Anna; Serrano, M Ángeles; Boguñá, Marián

    2012-08-01

    Many real networks are not isolated from each other but form networks of networks, often interrelated in nontrivial ways. Here, we analyze an epidemic spreading process taking place on top of two interconnected complex networks. We develop a heterogeneous mean-field approach that allows us to calculate the conditions for the emergence of an endemic state. Interestingly, a global endemic state may arise in the coupled system even though the epidemics is not able to propagate on each network separately and even when the number of coupling connections is small. Our analytic results are successfully confronted against large-scale numerical simulations.

  1. Coding-Spreading Tradeoff in CDMA Systems

    National Research Council Canada - National Science Library

    Bolas, Eduardo

    2002-01-01

    .... Comparing different combinations of coding and spreading with a traditional DS-CDMA, as defined in the IS-95 standard, allows the criteria to be defined for the best coding-spreading tradeoff in CDMA systems...

  2. Lexical Ambiguity: Making a Case against Spread

    Science.gov (United States)

    Kaplan, Jennifer J.; Rogness, Neal T.; Fisher, Diane G.

    2012-01-01

    We argue for decreasing the use of the word "spread" when describing the statistical idea of dispersion or variability in introductory statistics courses. In addition, we argue for increasing the use of the word "variability" as a replacement for "spread."

  3. Gas in Eastern Europe

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    West European gas companies have long recognised the potential for lucrative business within eastern Europe. But they recognise that the region's integration into the west European system will be far from straightforward, with deals between east European gas companies and their western counterparts invariably containing financial mechanisms, such as barter trade, that are designed to cope with the easterners' shortage of hard currency. (author)

  4. Middle Eastern rhinoplasty.

    Science.gov (United States)

    Azizzadeh, Babak; Mashkevich, Grigoriy

    2010-02-01

    The ethnic appearance of the Middle Eastern nose is defined by several unique visual features, particularly a high radix, wide overprojecting dorsum, and an amorphous hanging nasal tip. These external characteristics reflect distinct structural properties of the osseo-cartilaginous nasal framework and skin-soft tissue envelope in patients of Middle Eastern extraction. The goal, and the ultimate challenge, of rhinoplasty on Middle Eastern patients is to achieve balanced aesthetic refinement, while avoiding surgical westernization. Detailed understanding of the ethnic visual harmony in a Middle Eastern nose greatly assists in preserving native nasal-facial relationships during rhinoplasty on Middle Eastern patients. Esthetic alteration of a Middle Eastern nose follows a different set of goals and principles compared with rhinoplasties on white or other ethnic patients. This article highlights the inherent nasal features of the Middle Eastern nose and reviews pertinent concepts of rhinoplasty on Middle Eastern patients. Essential considerations in the process spanning the consultation and surgery are reviewed. Reliable operative techniques that achieve a successful aesthetic outcome are discussed in detail. Copyright 2010 Elsevier Inc. All rights reserved.

  5. Cooperative spreading processes in multiplex networks.

    Science.gov (United States)

    Wei, Xiang; Chen, Shihua; Wu, Xiaoqun; Ning, Di; Lu, Jun-An

    2016-06-01

    This study is concerned with the dynamic behaviors of epidemic spreading in multiplex networks. A model composed of two interacting complex networks is proposed to describe cooperative spreading processes, wherein the virus spreading in one layer can penetrate into the other to promote the spreading process. The global epidemic threshold of the model is smaller than the epidemic thresholds of the corresponding isolated networks. Thus, global epidemic onset arises in the interacting networks even though an epidemic onset does not arise in each isolated network. Simulations verify the analysis results and indicate that cooperative spreading processes in multiplex networks enhance the final infection fraction.

  6. Bank Lending, Housing and Spreads

    DEFF Research Database (Denmark)

    Aslam, Aqib; Santoro, Emiliano

    The framework presented in this paper takes its cue from recent financial events and attempts to develop a tractable framework for policy analysis of macro-linkages, in particular a first attempt at the integration of an independent profit-maximising banking sector that lends to and borrows from...... agents in the economy, and through which changes in the monetary policy rate by the central bank are transmitted. The inter-linkages between housing and the role of the banking sector in the transmission of monetary policy is emphasized. Two competing effects are highlighted: (i) a financial accelerator...... channel, due to the presence of collateralized borrowers, and (ii) a banking attenuator effect, which crucially arises from the spread in interest rates caused by the introduction of monopolistically competitive financial intermediaries. We show how the classical amplification mechanism explored in models...

  7. [Spread of Chinese variolation art to the western world and its influence].

    Science.gov (United States)

    Xie, S; Zhang, D

    2000-07-01

    Smallpox inoculation or variolation is a great invention of medicine in ancient China. In this paper, we introduced the process of spread of smallpox inoculation technique from China to western world (mainly to England), and reviewed the royal experiment of smallpox inoculation on human being and its influence on the prevention of smallpox in western countries. The spread and practice of smallpox inoculation in western world was an important event in the history of intercommunication between eastern and western medicines, which is worth emphasizing and further studying.

  8. Variation in winter survival of the invasive hemlock woolly adelgid (Hemiptera: Adelgidae) across the eastern United States

    Science.gov (United States)

    R. Talbot, III Trotter; Kathleen S. Shields

    2009-01-01

    The hemlock woolly adelgid (Adelges tsugae Annand) is a small, aphid-like insect native to East Asia and western North America. First documented in the eastern United States in Richmond, VA, in 1951, it has spread to at least 17 states, where it causes increased mortality among both eastern and Carolina hemlocks (Tsuga canadensis...

  9. History of Smallpox and Its Spread in Human Populations.

    Science.gov (United States)

    Thèves, Catherine; Crubézy, Eric; Biagini, Philippe

    2016-08-01

    Smallpox is considered among the most devastating of human diseases. Its spread in populations, initiated for thousands of years following a probable transmission from an animal host, was concomitant with movements of people across regions and continents, trade and wars. Literature permitted to retrace the occurrence of epidemics from ancient times to recent human history, smallpox having affected all levels of past society including famous monarchs. The disease was officially declared eradicated in 1979 following intensive vaccination campaigns.Paleomicrobiology dedicated to variola virus is restricted to few studies, most unsuccessful, involving ancient material. Only one recent approach allowed the identification of viral DNA fragments from lung tissue of a 300-year-old body excavated from permafrost in Eastern Siberia; phylogenetic analysis revealed that this ancient strain was distinct from those described during the 20th century.

  10. Perineural spread in head and neck tumors.

    Science.gov (United States)

    Brea Álvarez, B; Tuñón Gómez, M

    2014-01-01

    Perineural spread is the dissemination of some types of head and neck tumors along nervous structures. Perineural spread has negative repercussions on treatment because it requires more extensive resection and larger fields of irradiation. Moreover, perineural spread is associated with increased local recurrence, and it is considered an independent indicator of poor prognosis in the TNM classification for tumor staging. However, perineural spread often goes undetected on imaging studies. In this update, we review the concept of perineural spread, its pathogenesis, and the main pathways and connections among the facial nerves, which are essential to understand this process. Furthermore, we discuss the appropriate techniques for imaging studies, and we describe and illustrate the typical imaging signs that help identify perineural spread on CT and MRI. Finally, we discuss the differential diagnosis with other entities. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

  11. MIMO Based Eigen-Space Spreading

    National Research Council Canada - National Science Library

    Eltawil, Ahmed

    2004-01-01

    .... Combination of this powerful technique with orthogonal frequency division multiplexing (OFDM) based modulation and traditional time and frequency spreading techniques results in a highly secure mode of communications...

  12. COMBINED SURGERY OF SPREAD THYROID CANCER

    Directory of Open Access Journals (Sweden)

    V. Zh. Brzhezovsky

    2014-01-01

    Full Text Available Results of treating of 99 patients with differentiated thyroid cancer spreading beyond the capsule of the organ were analysed. In most cases with spreading the tumor to the tracheal rings performing of organ-preserving operations (from “window-like” tracheal resections to circular tracheal resection with intertracheal anastomosis is possible. Choosing of type of operation to be performed depends on localisation and spread of tumor invasion of trachea, pharynx and esophagus. Using of combined operations in patients with locally-spread thyroid cancer allows to achieve long and stable remission in most of the cases.

  13. Energy Spread Sources in TESLA and TTF

    International Nuclear Information System (INIS)

    Mosnier, A.; Tessier, J.M.

    1995-03-01

    The beam energy spread in the TESLA linac must be small enough to limit the emittance dilution due to the dispersive effects. This report summarizes the major sources of energy spread both for the TESLA linac and the TTF linac, where these estimations will be carefully checked with beam experiments. The first part recalls the intra-bunch energy spread while the second part looks into the bunch-to-bunch energy spread induced by rf field fluctuations within the bunch train and from pulse-to-pulse. (author). 3 refs., 4 figs

  14. Olive oil in food spreads

    Directory of Open Access Journals (Sweden)

    Blanco Muñoz, Miguel A.

    2004-03-01

    Full Text Available Chemical hydrogenation of unsaturated fatty acids is a commonly applied reaction to food industries. The process may imply the movement of double bonds in their positions on the fatty acid carbon chain, producing positional and geometrical isomers ( trans fatty acids. Through hydrogenation, unsaturated oils are converted to margarines and vegetable shortenings. The presence of trans fatty acids in foods is undesirable, as trans fatty acids raise the plasma levels of total and low-density lipoproteins (LDL, while decrease the plasma level of high-density lipoproteins (HDL, among other effects. The use of olive oil to prepare fat spread opens new insights into the commercial development of healthy novel foods with a positive image in terms of consumer appeal.La hidrogenación química de los ácidos grasos insaturados es una reacción que se utiliza con frecuencia en la industria alimentaria. El proceso implica el movimiento de los dobles enlaces en la cadena hidrocarbonada de los ácidos grasos, y la aparición de isómeros posicionales y geométricos (ácidos grasos trans . La ingesta inadecuada de alimentos que pueden contener cantidades significativas de ácidos grasos trans se asocia con el aumento en sangre de colesterol total y LDL, y la disminución de HDL, entre otros efectos. Por lo tanto, el uso de aceite de oliva en la preparación de grasas para untar constituye un importante avance en el desarrollo comercial de nuevos alimentos saludables con una imagen positiva para el consumidor.

  15. Anomalous diffusion spreads its wings

    Energy Technology Data Exchange (ETDEWEB)

    Klafter, J. [School of Chemistry, Tel Aviv University, Tel-Aviv (Israel)]. E-mail: klafter@post.tau.ac.il; Sokolov, I.M. [Institute of Physics, Humboldt University, Berlin (Germany)]. E-mail: igor.sokolov@physik.hu-berlin.de

    2005-08-01

    An increasing number of natural phenomena do not fit into the relatively simple description of diffusion developed by Einstein a century ago. As all of us are no doubt aware, this year has been declared 'world year of physics' to celebrate the three remarkable breakthroughs made by Albert Einstein in 1905. However, it is not so well known that Einstein's work on Brownian motion - the random motion of tiny particles first observed and investigated by the botanist Robert Brown in 1827 - has been cited more times in the scientific literature than his more famous papers on special relativity and the quantum nature of light. In a series of publications that included his doctoral thesis, Einstein derived an equation for Brownian motion from microscopic principles - a feat that ultimately enabled Jean Perrin and others to prove the existence of atoms (see 'Einstein's random walk' Physics World January pp19-22). Einstein was not the only person thinking about this type of problem. The 27 July 1905 issue of Nature contained a letter with the title 'The problem of the random walk' by the British statistician Karl Pearson, who was interested in the way that mosquitoes spread malaria, which he showed was described by the well-known diffusion equation. As such, the displacement of a mosquito from its initial position is proportional to the square root of time, and the distribution of the positions of many such 'random walkers' starting from the same origin is Gaussian in form. The random walk has since turned out to be intimately linked to Einstein's work on Brownian motion, and has become a major tool for understanding diffusive processes in nature. (U.K.)

  16. Molecular phylogenetic analysis of Fasciola flukes from eastern India.

    Science.gov (United States)

    Hayashi, Kei; Ichikawa-Seki, Madoka; Mohanta, Uday Kumar; Singh, T Shantikumar; Shoriki, Takuya; Sugiyama, Hiromu; Itagaki, Tadashi

    2015-10-01

    Fasciola flukes from eastern India were characterized on the basis of spermatogenesis status and nuclear ITS1. Both Fasciola gigantica and aspermic Fasciola flukes were detected in Imphal, Kohima, and Gantoku districts. The sequences of mitochondrial nad1 were analyzed to infer their phylogenetical relationship with neighboring countries. The haplotypes of aspermic Fasciola flukes were identical or showed a single nucleotide substitution compared to those from populations in the neighboring countries, corroborating the previous reports that categorized them in the same lineage. However, the prevalence of aspermic Fasciola flukes in eastern India was lower than those in the neighboring countries, suggesting that they have not dispersed throughout eastern India. In contrast, F. gigantica was predominant and well diversified, and the species was thought to be distributed in the area for a longer time than the aspermic Fasciola flukes. Fasciola gigantica populations from eastern India were categorized into two distinct haplogroups A and B. The level of their genetic diversity suggests that populations belonging to haplogroup A have dispersed from the west side of the Indian subcontinent to eastern India with the artificial movement of domestic cattle, Bos indicus, whereas populations belonging to haplogroup B might have spread from Myanmar to eastern India with domestic buffaloes, Bubalus bubalis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Bovine besnoitiosis emerging in Central-Eastern Europe, Hungary

    OpenAIRE

    Hornok, Sándor; Fedák, András; Baska, Ferenc; Hofmann-Lehmann, Regina; Basso, Walter

    2014-01-01

    BACKGROUND: Besnoitia besnoiti, the cause of bovine besnoitiosis, is a cyst-forming coccidian parasite that has recently been shown to be spreading in several Western and Southern European countries. FINDINGS: Clinical cases of bovine besnoitiosis were confirmed for the first time in Hungary, by histological, serological and PCR analyses. CONCLUSIONS: This is the first report of autochthonous bovine besnoitiosis in Central-Eastern Europe. The emergence of bovine besnoitiosis in this region re...

  18. On entanglement spreading from holography

    Energy Technology Data Exchange (ETDEWEB)

    Mezei, Márk [Princeton Center for Theoretical Science, Princeton University,Princeton, NJ 08544 (United States)

    2017-05-11

    A global quench is an interesting setting where we can study thermalization of subsystems in a pure state. We investigate entanglement entropy (EE) growth in global quenches in holographic field theories and relate some of its aspects to quantities characterizing chaos. More specifically we obtain four key results: We prove holographic bounds on the entanglement velocity v{sub E} and the butterfly effect speed v{sub B} that arises in the study of chaos. We obtain the EE as a function of time for large spherical entangling surfaces analytically. We show that the EE is insensitive to the details of the initial state or quench protocol. In a thermofield double state we determine analytically the two-sided mutual information between two large concentric spheres separated in time. We derive a bound on the rate of growth of EE for arbitrary shapes, and develop an expansion for EE at early times. In a companion paper https://arxiv.org/abs/1608.05101, these results are put in the broader context of EE growth in chaotic systems: we relate EE growth to the chaotic spreading of operators, derive bounds on EE at a given time, and compare the holographic results to spin chain numerics and toy models. In this paper, we perform holographic calculations that provide the basis of arguments presented in that paper. We prove holographic bounds on the entanglement velocity v{sub E} and the butterfly effect speed v{sub B} that arises in the study of chaos. We obtain the EE as a function of time for large spherical entangling surfaces analytically. We show that the EE is insensitive to the details of the initial state or quench protocol. In a thermofield double state we determine analytically the two-sided mutual information between two large concentric spheres separated in time. We derive a bound on the rate of growth of EE for arbitrary shapes, and develop an expansion for EE at early times.

  19. Spreading to localized targets in complex networks

    Science.gov (United States)

    Sun, Ye; Ma, Long; Zeng, An; Wang, Wen-Xu

    2016-12-01

    As an important type of dynamics on complex networks, spreading is widely used to model many real processes such as the epidemic contagion and information propagation. One of the most significant research questions in spreading is to rank the spreading ability of nodes in the network. To this end, substantial effort has been made and a variety of effective methods have been proposed. These methods usually define the spreading ability of a node as the number of finally infected nodes given that the spreading is initialized from the node. However, in many real cases such as advertising and news propagation, the spreading only aims to cover a specific group of nodes. Therefore, it is necessary to study the spreading ability of nodes towards localized targets in complex networks. In this paper, we propose a reversed local path algorithm for this problem. Simulation results show that our method outperforms the existing methods in identifying the influential nodes with respect to these localized targets. Moreover, the influential spreaders identified by our method can effectively avoid infecting the non-target nodes in the spreading process.

  20. Epidemic spreading through direct and indirect interactions.

    Science.gov (United States)

    Ganguly, Niloy; Krueger, Tyll; Mukherjee, Animesh; Saha, Sudipta

    2014-09-01

    In this paper we study the susceptible-infected-susceptible epidemic dynamics, considering a specialized setting where popular places (termed passive entities) are visited by agents (termed active entities). We consider two types of spreading dynamics: direct spreading, where the active entities infect each other while visiting the passive entities, and indirect spreading, where the passive entities act as carriers and the infection is spread via them. We investigate in particular the effect of selection strategy, i.e., the way passive entities are chosen, in the spread of epidemics. We introduce a mathematical framework to study the effect of an arbitrary selection strategy and derive formulas for prevalence, extinction probabilities, and epidemic thresholds for both indirect and direct spreading. We also obtain a very simple relationship between the extinction probability and the prevalence. We pay special attention to preferential selection and derive exact formulas. The analysis reveals that an increase in the diversity in the selection process lowers the epidemic thresholds. Comparing the direct and indirect spreading, we identify regions in the parameter space where the prevalence of the indirect spreading is higher than the direct one.

  1. Fluorescent visualization of a spreading surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Fallest, David W; Lichtenberger, Adele M; Fox, Christopher J; Daniels, Karen E, E-mail: kdaniel@ncsu.ed [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

    2010-07-15

    The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently tagged surfactant. We find that the leading edge of a spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration that trails the leading edge, and a flat, monolayer-scale spreading film that differs from concentration profiles predicted by current models. Both the Marangoni ridge and the surfactant leading edge can be described to spread as R{approx}t{sup {delta}}. We find spreading exponents {delta}{sub H}{approx}0.30 and {delta}{sub {Gamma}}{approx}0.22 for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of {delta}=1/4. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge.

  2. Age, spreading rates, and spreading asymmetry of the world's ocean crust

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The authors present four companion digital models of the age, age uncertainty, spreading rates and spreading asymmetries of the world's ocean basins as geographic...

  3. Spread and Liquidity Issues: A markets comparison

    Directory of Open Access Journals (Sweden)

    Strašek Sebastjan

    2016-03-01

    Full Text Available The financial crises are closely connected with spread changes and liquidity issues. After defining and addressing spread considerations, we research in this paper the topic of liquidity issues in times of economic crisis. We analyse the liquidity effects as recorded on spreads of securities from different markets. We stipulate that higher international risk aversion in times of financial crises coincides with widening security spreads. The paper then introduces liquidity as a risk factor into the standard value-at-risk framework, using GARCH methodology. The comparison of results of these models suggests that the size of the tested markets does not have a strong effect on the models. Thus, we find that spread analysis is an appropriate tool for analysing liquidity issues during a financial crisis.

  4. The Eastern Partnership

    DEFF Research Database (Denmark)

    Nielsen, Kristian L.; Vilson, Maili

    2014-01-01

    When the EU launched the Eastern Partnership (EaP) in 2009, it did so with much rhetoric about projecting its soft power into Eastern Europe. Yet today, the EU's soft power project seems to have stalled, with developments in the region being less than favourable. This article argues that the EaP...... essentially replicated the main weaknesses of the European Neighbourhood Policy, by offering too little incentive and support to the partners, rendering both conditionality and soft power ineffective as tools for milieu shaping. In promoting the EaP as a policy of soft power, the EU has once again forgotten...

  5. Development of Pistachio (Pistacia vera L.) spread.

    Science.gov (United States)

    Shakerardekani, Ahmad; Karim, Roselina; Ghazali, Hasanah Mohd; Chin, Nyuk Ling

    2013-03-01

    Pistachio nut (Pistacia vera L.) is one of the most delicious and nutritious nuts in the world. Pistachio spreads were developed using pistachio paste as the main component, icing sugar, soy protein isolate (SPI), and red palm oil (RPO), at different ratios. The highest mean scores of all the sensory attributes were depicted by spreads that were made without addition of SPI. It was found that the work of shear was 0 to 11.0 kg s for an acceptable spread. Sensory spreadability, overall texture, spreadability, and overall acceptability were negatively correlated (R > 0.83) with the work of shear of spreads. The findings indicated that the presence of RPO had a direct effect on the viscoelastic behavior of the pistachio spreads. The a values, which are related to the green color of the pistachio product ranged from 1.7 to 3.9 for spread without addition of RPO, and 4.0 to 5.3 in the presence of RPO. The development of pistachio spread would potentially increase the food uses of pistachio and introduce consumers with a healthier snack food. © 2013 Institute of Food Technologists®

  6. Credit Spreads Across the Business Cycle

    DEFF Research Database (Denmark)

    Nielsen, Mads Stenbo

    This paper studies how corporate bond spreads vary with the business cycle. I show that both level and slope of empirical credit spread curves are correlated with the state of the economy, and I link this to variation in idiosyncratic jump risk. I develop a structural credit risk model...... that accounts for both business cycle and jump risk, and show by estimation that the model captures the counter-cyclical level and pro-cyclical slope of empirical credit spread curves. In addition, I provide a new procedure for estimation of idiosyncratic jump risk, which is consistent with observed shocks...

  7. Modelling unidirectional liquid spreading on slanted microposts

    DEFF Research Database (Denmark)

    Cavalli, Andrea; Blow, Matthew L.; Yeomans, Julia M.

    2013-01-01

    A lattice Boltzmann algorithm is used to simulate the slow spreading of drops on a surface patterned with slanted micro-posts. Gibb's pinning of the interface on the sides or top of the posts leads to unidirectional spreading over a wide range of contact angles and inclination angles of the posts....... Regimes for spreading in no, one or two directions are identified, and shown to agree well with a two-dimensional theory proposed in Chu, Xiao and Wang. A more detailed numerical analysis of the contact line shapes allows us to understand deviations from the two dimensional model, and to identify...

  8. Eastern Frequency Response Study

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N.W.; Shao, M.; Pajic, S.; D' Aquila, R.

    2013-05-01

    This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

  9. Epidemic spreading in a hierarchical social network.

    Science.gov (United States)

    Grabowski, A; Kosiński, R A

    2004-09-01

    A model of epidemic spreading in a population with a hierarchical structure of interpersonal interactions is described and investigated numerically. The structure of interpersonal connections is based on a scale-free network. Spatial localization of individuals belonging to different social groups, and the mobility of a contemporary community, as well as the effectiveness of different interpersonal interactions, are taken into account. Typical relations characterizing the spreading process, like a range of epidemic and epidemic curves, are discussed. The influence of preventive vaccinations on the spreading process is investigated. The critical value of preventively vaccinated individuals that is sufficient for the suppression of an epidemic is calculated. Our results are compared with solutions of the master equation for the spreading process and good agreement of the character of this process is found.

  10. Heterogeneous incidence and propagation of spreading depolarizations

    Science.gov (United States)

    Kaufmann, Dan; Theriot, Jeremy J; Zyuzin, Jekaterina; Service, C Austin; Chang, Joshua C; Tang, Y Tanye; Bogdanov, Vladimir B; Multon, Sylvie; Schoenen, Jean; Ju, Y Sungtaek

    2016-01-01

    Spreading depolarizations are implicated in a diverse set of neurologic diseases. They are unusual forms of nervous system activity in that they propagate very slowly and approximately concentrically, apparently not respecting the anatomic, synaptic, functional, or vascular architecture of the brain. However, there is evidence that spreading depolarizations are not truly concentric, isotropic, or homogeneous, either in space or in time. Here we present evidence from KCl-induced spreading depolarizations, in mouse and rat, in vivo and in vitro, showing the great variability that these depolarizations can exhibit. This variability can help inform the mechanistic understanding of spreading depolarizations, and it has implications for their phenomenology in neurologic disease. PMID:27562866

  11. Interference management using direct sequence spread spectrum ...

    African Journals Online (AJOL)

    Interference management using direct sequence spread spectrum (DSSS) technique ... Journal of Fundamental and Applied Sciences ... Keywords: DSSS, LTE network; Wi-Fi network; SINR; interference management and interference power.

  12. Flame spread along thermally thick horizontal rods

    Science.gov (United States)

    Higuera, F. J.

    2002-06-01

    An analysis is carried out of the spread of a flame along a horizontal solid fuel rod, for which a weak aiding natural convection flow is established in the underside of the rod by the action of the axial gradient of the pressure variation that gravity generates in the warm gas surrounding the flame. The spread rate is determined in the limit of infinitely fast kinetics, taking into account the effect of radiative losses from the solid surface. The effect of a small inclination of the rod is discussed, pointing out a continuous transition between upward and downward flame spread. Flame spread along flat-bottomed solid cylinders, for which the gradient of the hydrostatically generated pressure drives the flow both along and across the direction of flame propagation, is also analysed.

  13. Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin: New constraints on breakup and early spreading history between India and Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Michael, L.; Bhattacharyya, R.; Majumdar, T.J.

    the anomalies. Since the magnetic anomalies in the western Enderby Basin have lower amplitude, Gaina et al. (2007) could not identify the anomalies with confidence and found difficulty to correlate the spreading history with that of the central and eastern... Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin – new constraints on breakup and early spreading history between India and Antarctica K.S. Krishna*, Laju Michael National Institute of Oceanography, Council...

  14. Spreading paths in partially observed social networks

    OpenAIRE

    Onnela, Jukka-Pekka; Christakis, Nicholas A.

    2012-01-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using a static, s...

  15. Mapping the Spread of Mounted Warfare

    Directory of Open Access Journals (Sweden)

    Peter Turchin

    2016-12-01

    Full Text Available Military technology is one of the most important factors affecting the evolution of complex societies. In particular, mounted warfare, the use of horse-riders in military operations, revolutionized war as it spread to different parts of Eurasia and Africa during the Ancient and Medieval eras, and to the Americas during the Early Modern period. Here we use a variety of sources to map this spread.

  16. Ignition and spread of electrical wire fires

    OpenAIRE

    Huang, Xinyan

    2012-01-01

    Ignition of electrical wires by external heating is investigated in order to gain a better understanding of the initiation of electrical-wire fires. An ignition-to- spread model is developed to systematically explain ignition and the following transition to spread. The model predicts that for a higher-conductance wire it is more difficult to achieve ignition and the weak flame may extinguish during the transition phase because of a large conductive heat loss along the wire core. Wires with tw...

  17. Spreading characteristics of proprietary rectal steroid preparations

    International Nuclear Information System (INIS)

    Hay, D.J.

    1982-01-01

    Three types of rectal steroid preparation were labelled with Technetium 99 or Indium 111, and the extent of spread of each within the bowel was followed, immediately after administration and at 2hrs, using a gamma camera. Patients with ulcerative colitis were compared with controls. Results indicate that 'Colifoam' enema and 'Predsol' suppository act mainly in the rectum, but 'Predsol retention' enema spreads further into the colon, making it more useful for patients with extensive ulcerative colitis. (U.K.)

  18. Dynamical Model about Rumor Spreading with Medium

    Directory of Open Access Journals (Sweden)

    Xiaxia Zhao

    2013-01-01

    Full Text Available Rumor is a kind of social remark, that is untrue, and not be confirmed, and spreads on a large scale in a short time. Usually, it can induce a cloud of pressure, anxiety, and panic. Traditionally, it is propagated by word of mouth. Nowadays, with the emergence of the internet, rumors can be spread by instant messengers, emails, or publishing. With this new pattern of spreading, an ISRW dynamical model considering the medium as a subclass is established. Beside the dynamical analysis of the model, we mainly explore the mechanism of spreading of individuals-to-individuals and medium-to-individual. By numerical simulation, we find that if we want to control the rumor spreading, it will not only need to control the rate of change of the spreader subclass, but also need to control the change of the information about rumor in medium which has larger influence. Moreover, to control the effusion of rumor is more important than deleting existing information about rumor. On the one hand, government should enhance the management of internet. On the other hand, relevant legal institutions for punishing the rumor creator and spreader on internet who can be tracked should be established. Using this way, involved authorities can propose efficient measures to control the rumor spreading to keep the stabilization of society and development of economy.

  19. Gossip spread in social network Models

    Science.gov (United States)

    Johansson, Tobias

    2017-04-01

    Gossip almost inevitably arises in real social networks. In this article we investigate the relationship between the number of friends of a person and limits on how far gossip about that person can spread in the network. How far gossip travels in a network depends on two sets of factors: (a) factors determining gossip transmission from one person to the next and (b) factors determining network topology. For a simple model where gossip is spread among people who know the victim it is known that a standard scale-free network model produces a non-monotonic relationship between number of friends and expected relative spread of gossip, a pattern that is also observed in real networks (Lind et al., 2007). Here, we study gossip spread in two social network models (Toivonen et al., 2006; Vázquez, 2003) by exploring the parameter space of both models and fitting them to a real Facebook data set. Both models can produce the non-monotonic relationship of real networks more accurately than a standard scale-free model while also exhibiting more realistic variability in gossip spread. Of the two models, the one given in Vázquez (2003) best captures both the expected values and variability of gossip spread.

  20. Roles of the spreading scope and effectiveness in spreading dynamics on multiplex networks

    Science.gov (United States)

    Li, Ming; Liu, Run-Ran; Peng, Dan; Jia, Chun-Xiao; Wang, Bing-Hong

    2018-02-01

    Comparing with single networks, the multiplex networks bring two main effects on the spreading process among individuals. First, the pathogen or information can be transmitted to more individuals through different layers at one time, which enlarges the spreading scope. Second, through different layers, an individual can also transmit the pathogen or information to the same individuals more than once at one time, which makes the spreading more effective. To understand the different roles of the spreading scope and effectiveness, we propose an epidemic model on multiplex networks with link overlapping, where the spreading effectiveness of each interaction as well as the variety of channels (spreading scope) can be controlled by the number of overlapping links. We find that for Poisson degree distribution, increasing the epidemic scope (the first effect) is more efficient than enhancing epidemic probability (the second effect) to facilitate the spreading process. However, for power-law degree distribution, the effects of the two factors on the spreading dynamics become complicated. Enhancing epidemic probability makes pathogen or rumor easier to outbreak in a finite system. But after that increasing epidemic scopes is still more effective for a wide spreading. Theoretical results along with reasonable explanation for these phenomena are all given in this paper, which indicates that the epidemic scope could play an important role in the spreading dynamics.

  1. A network model for Ebola spreading.

    Science.gov (United States)

    Rizzo, Alessandro; Pedalino, Biagio; Porfiri, Maurizio

    2016-04-07

    The availability of accurate models for the spreading of infectious diseases has opened a new era in management and containment of epidemics. Models are extensively used to plan for and execute vaccination campaigns, to evaluate the risk of international spreadings and the feasibility of travel bans, and to inform prophylaxis campaigns. Even when no specific therapeutical protocol is available, as for the Ebola Virus Disease (EVD), models of epidemic spreading can provide useful insight to steer interventions in the field and to forecast the trend of the epidemic. Here, we propose a novel mathematical model to describe EVD spreading based on activity driven networks (ADNs). Our approach overcomes the simplifying assumption of homogeneous mixing, which is central to most of the mathematically tractable models of EVD spreading. In our ADN-based model, each individual is not bound to contact every other, and its network of contacts varies in time as a function of an activity potential. Our model contemplates the possibility of non-ideal and time-varying intervention policies, which are critical to accurately describe EVD spreading in afflicted countries. The model is calibrated from field data of the 2014 April-to-December spreading in Liberia. We use the model as a predictive tool, to emulate the dynamics of EVD in Liberia and offer a one-year projection, until December 2015. Our predictions agree with the current vision expressed by professionals in the field, who consider EVD in Liberia at its final stage. The model is also used to perform a what-if analysis to assess the efficacy of timely intervention policies. In particular, we show that an earlier application of the same intervention policy would have greatly reduced the number of EVD cases, the duration of the outbreak, and the infrastructures needed for the implementation of the intervention. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. High-temperature spreading kinetics of metals

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, N.

    2005-05-15

    In this PhD work a drop transfer setup combined with high speed photography has been used to analyze the spreading of Ag on polished polycrystalline Mo and single crystalline Mo (110) and (100) substrates. The objective of this work was to unveil the basic phenomena controlling spreading in metal-metal systems. The observed spreading kinetics were compared with current theories of low and high temperature spreading such as a molecular kinetic model and a fluid flow model. Analyses of the data reveal that the molecular model does describe the fastest velocity data well for all the investigated systems. Therefore, the energy which is dissipated during the spreading process is a dissipation at the triple line rather than dissipation due to the viscosity in the liquid. A comparison of the determined free activation energy for wetting of {delta}G95{approx}145kJ/mol with literature values allows the statement that the rate determining step seems to be a surface diffusion of the Ag atoms along the triple line. In order to investigate possible ridge formation, due to local atomic diffusion of atoms of the substrate at the triple during the spreading process, grooving experiments of the polycrystalline Mo were performed to calculate the surface diffusities that will control ridge evolution. The analyses of this work showed that a ridge formation at the fastest reported wetting velocities was not possible if there is no initial perturbation for a ridge. If there was an initial perturbation for a ridge the ridge had to be much smaller than 1 nm in order to be able to move with the liquid font. Therefore ridge formation does not influence the spreading kinetics for the studied system and the chosen conditions. SEM, AFM and TEM investigations of the triple line showed that ridge formation does also not occur at the end of the wetting experiment when the drop is close to equilibrium and the wetting velocity is slow. (orig.)

  3. Terrestrial spreading centers under Venus conditions - Evaluation of a crustal spreading model for Western Aphrodite Terra

    Science.gov (United States)

    Sotin, C.; Senske, D. A.; Head, J. W.; Parmentier, E. M.

    1989-01-01

    The model of Reid and Jackson (1981) for terrestrial spreading centers is applied to Venus conditions. On the basis of spreading rate, mantle temperature, and surface temperature, the model predicts both isostatic topography and crustal thickness. The model and Pioneer Venus altimetry and gravity data are used to test the hypothesis of Head and Crumpler (1987) that Western Aphrodite Terra is the location of crustal spreading on Venus. It is concluded that a spreading center model for Ovda Regio in Western Aphrodite Terra could account for the observed topography and line-of-sight gravity anomalies found in the Pioneer data.

  4. Biology, spread, and biological control of winter moth in the eastern United States

    Science.gov (United States)

    Joseph Elkinton; George Boettner; Andrew Liebhold; Rodger. Gwiazdowski

    2015-01-01

    The winter moth (Operophtera brumata L.; Lepidoptera: Geometridae) is an inchworm caterpillar that hatches coincident with bud-break on its hosts and feeds on a wide range of deciduous trees. It is one of a group of geometrid species that feed in early spring and then pupate in the top layer of the soil or litter beginning in mid-May. As postulated...

  5. Eastern Europe's market role

    International Nuclear Information System (INIS)

    Schreiber, K.F.

    1991-01-01

    Until the late 1980s, trade in nuclear fuel between market economy countries and those with planned economies was limited. The exception to this was in the enrichment market across Western Europe during the 1970s. Most of the nuclear generating plants in the Soviet Union and Eastern Europe are light water reactors needing enriched uranium. Under the fuel supply agreements with Eastern Europe, the Soviet Union has provided all of the regions' enrichment services, and therefore it has developed the only enrichment facilities. Techsnabexport (TENEX), the USSR foreign trade organization for the nuclear fuel cycle, first appeared in the early 1970s. It was as an alternative supplier to the US government, which had a monopoly in the West regarding enrichment. In 1986 the USSR entered and soon dominated the spot market for enrichment. Political changes in Eastern Europe at the end of 1989 and throughout 1990 opened the nuclear fuel market even wider. In 1990 the USSR began allowing exports of concentrates, as well as enriched product, and a free flow of trade to the Western market is now developing for both enrichment and uranium. (author)

  6. Free energy analysis of cell spreading.

    Science.gov (United States)

    McEvoy, Eóin; Deshpande, Vikram S; McGarry, Patrick

    2017-10-01

    In this study we present a steady-state adaptation of the thermodynamically motivated stress fiber (SF) model of Vigliotti et al. (2015). We implement this steady-state formulation in a non-local finite element setting where we also consider global conservation of the total number of cytoskeletal proteins within the cell, global conservation of the number of binding integrins on the cell membrane, and adhesion limiting ligand density on the substrate surface. We present a number of simulations of cell spreading in which we consider a limited subset of the possible deformed spread-states assumed by the cell in order to examine the hypothesis that free energy minimization drives the process of cell spreading. Simulations suggest that cell spreading can be viewed as a competition between (i) decreasing cytoskeletal free energy due to strain induced assembly of cytoskeletal proteins into contractile SFs, and (ii) increasing elastic free energy due to stretching of the mechanically passive components of the cell. The computed minimum free energy spread area is shown to be lower for a cell on a compliant substrate than on a rigid substrate. Furthermore, a low substrate ligand density is found to limit cell spreading. The predicted dependence of cell spread area on substrate stiffness and ligand density is in agreement with the experiments of Engler et al. (2003). We also simulate the experiments of Théry et al. (2006), whereby initially circular cells deform and adhere to "V-shaped" and "Y-shaped" ligand patches. Analysis of a number of different spread states reveals that deformed configurations with the lowest free energy exhibit a SF distribution that corresponds to experimental observations, i.e. a high concentration of highly aligned SFs occurs along free edges, with lower SF concentrations in the interior of the cell. In summary, the results of this study suggest that cell spreading is driven by free energy minimization based on a competition between decreasing

  7. Spreading paths in partially observed social networks

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A.

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  8. Spreading paths in partially observed social networks.

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  9. Assessment of thema code against spreading experiments

    International Nuclear Information System (INIS)

    Spindler, B.; Veteau, J.M.; Cecco, L. de; Montanelli, P.; Pineau, D.

    2000-01-01

    In the frame work of severe accident research, the spreading code THEMA, developed at CEA/DRN, aims at predicting the spreading extent of molten core after a vessel melt-through. The code solves fluid balance equations integrated over the fluid depth for oxidic and/or metallic phases under the shallow water assumption, using a finite difference scheme. Solidification is taken into account through crust formation on the substrate and at contact with the surroundings, as well as increase of fluid viscosity with solid fraction in the melt. A separate energy equation is solved for the solid substrate, including possible ablation. The assessment of THEMA code against the spreading experiments performed in the framework of the corium spreading and coolability project of the European Union is presented. These experiments use either simulating materials at medium (RIT), or at high temperature (KATS), or corium (VULCANO, FARO), conducted at different mass flow rates and with large or low solidification interval. THEMA appears to be able to simulate the whole set of the experiments investigated. Comparison between experimental and computed spreading lengths and substrate temperatures are quite satisfactory. The results show a rather large sensitivity at mass flow rate and inlet temperature, indicating that, generally, efforts should be made to improve the accuracy of the measurements of such parameters in the experiments. (orig.)

  10. Post-Tanner spreading of nematic droplets

    International Nuclear Information System (INIS)

    Mechkov, S; Oshanin, G; Cazabat, A M

    2009-01-01

    The quasistationary spreading of a circular liquid drop on a solid substrate typically obeys the so-called Tanner law, with the instantaneous base radius R(t) growing with time as R∼t 1/10 -an effect of the dominant role of capillary forces for a small-sized droplet. However, for droplets of nematic liquid crystals, a faster spreading law sets in at long times, so that R∼t α with α significantly larger than the Tanner exponent 1/10. In the framework of the thin film model (or lubrication approximation), we describe this 'acceleration' as a transition to a qualitatively different spreading regime driven by a strong substrate-liquid interaction specific to nematics (antagonistic anchoring at the interfaces). The numerical solution of the thin film equation agrees well with the available experimental data for nematics, even though the non-Newtonian rheology has yet to be taken into account. Thus we complement the theory of spreading with a post-Tanner stage, noting that the spreading process can be expected to cross over from the usual capillarity-dominated stage to a regime where the whole reservoir becomes a diffusive film in the sense of Derjaguin.

  11. Altitudinal Barrier to the Spread of an Invasive Species: Could the Pyrenean Chain Slow the Natural Spread of the Pinewood Nematode?

    Directory of Open Access Journals (Sweden)

    Julien Haran

    Full Text Available Mountain ranges may delimit the distribution of native species as well as constitute potential barriers to the spread of invasive species. The invasive pinewood nematode, Bursaphelenchus xylophilus, is a severe forest pest inducing pine wilt disease. It is vectored in Europe by a native long-horned beetle, Monochamus galloprovincialis. This study explored the potential of the Pyrenean chain to slow or prevent the natural spread of nematode-infested beetles from the Iberian Peninsula, where the nematode is established and is expanding its range, towards France and the rest of Europe. An analysis of the genetic structure and migration patterns of the beetle populations throughout the Pyrenean mountain range was combined with a spread model simulating the potential movements of nematode-infested beetles across it. The central part of the Pyrenees, which corresponds to the highest elevation zone, was shown to prevent gene flow between the French and Spanish populations of M. galloprovincialis on each side of the mountains. Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range. Simulations of the spread of nematode-infested beetles under various thresholds of beetle survival and pine wilt disease expression gave results consistent with the variation in genetic make-up, suggesting that western and eastern hillsides may represent corridors favoring natural spread of the nematode from the Iberian Peninsula to France. Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations. Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles. These results, which have to be considered together with potential human-assisted long-distance spread of the nematode, highlight

  12. Seasonal variations of equatorial spread-F

    Directory of Open Access Journals (Sweden)

    B. V. Krishna Murthy

    Full Text Available The occurrence of spread-F at Trivandrum (8.5°N, 77°E, dip 0.5°N has been investigated on a seasonal basis in sunspot maximum and minimum years in terms of the growth rate of irregularities by the generalized collisional Rayleigh-Taylor (GRT instability mechanism which includes the gravitational and cross-field instability terms. The occurrence statistics of spread-F at Trivandrum have been obtained using quarter hourly ionograms. The nocturnal variations of the growth rate of irregularities by the GRT mechanism have been estimated for different seasons in sunspot maximum and minimum years at Trivandrum using h'F values and vertical drift velocities obtained from ionograms. It is found that the seasonal variation of spread-F occurrence at Trivandrum can, in general, be accounted for on the basis of the GRT mechanism.

  13. Seasonal variations of equatorial spread-F

    Directory of Open Access Journals (Sweden)

    K. S. V. Subbarao

    1994-01-01

    Full Text Available The occurrence of spread-F at Trivandrum (8.5°N, 77°E, dip 0.5°N has been investigated on a seasonal basis in sunspot maximum and minimum years in terms of the growth rate of irregularities by the generalized collisional Rayleigh-Taylor (GRT instability mechanism which includes the gravitational and cross-field instability terms. The occurrence statistics of spread-F at Trivandrum have been obtained using quarter hourly ionograms. The nocturnal variations of the growth rate of irregularities by the GRT mechanism have been estimated for different seasons in sunspot maximum and minimum years at Trivandrum using h'F values and vertical drift velocities obtained from ionograms. It is found that the seasonal variation of spread-F occurrence at Trivandrum can, in general, be accounted for on the basis of the GRT mechanism.

  14. Diffusive spreading in nature, technology and society

    CERN Document Server

    Caro, Jürgen; Kärger, Jörg; Vogl, Gero

    2018-01-01

    This book deals with randomly moving objects and their spreading. The objects considered are particles like atoms and molecules, just as living beings like humans, animals, plants, bacteria and even abstract entities like ideas, rumors, information, innovations and linguistic features. The book explores and communicates the laws behind these movements and reports about astonishing similarities and very specific features typical of the given object under considerations. Leading scientists in disciplines as different as archeology, epidemics, linguistics and sociology, in contact with their colleagues from engineering, natural sciences and mathematics, introduce into the phenomena of spreading as relevant for their fields. An introductory chapter on “Spreading Fundamentals” provides a common basis for all these considerations, with a minimum of mathematics, selected and presented for enjoying rather than frustrating the reader.

  15. Linear theory of equatorial spread F

    International Nuclear Information System (INIS)

    Hudson, M.K.; Kennel, C.F.

    1975-01-01

    A fluid dispersion relation for the drift and interchange (Rayleigh-Taylor) modes in a collisional plasma forms the basis for a linear theory of equatorial spread F. The collisional drift mode growth rate will exceed the growth rate of the Rayleigh-Taylor mode at short perpendicular wavelengths and density gradient scale lengths, and the drift mode can grow on top side as well as on bottom side density gradients. However, below the F peak, where spread F predominates, it is concluded that both the drift and the Rayleigh-Taylor modes contribute to the total spread F spectrum, the Rayleigh-Taylor mode dominating at long and the drift mode at short perpendicular wavelengths above the ion Larmor radius

  16. Turbulent forces within river plumes affect spread

    Science.gov (United States)

    Bhattacharya, Atreyee

    2012-08-01

    When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States, the Columbia River—the largest river by volume draining into the Pacific Ocean from North America—generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation's fishing industry as well as the global economy.

  17. The spread of gossip in American schools

    Science.gov (United States)

    Lind, P. G.; da Silva, L. R.; Andrade, J. S., Jr.; Herrmann, H. J.

    2007-06-01

    Gossip is defined as a rumor which specifically targets one individual and essentially only propagates within its friendship connections. How fast and how far a gossip can spread is for the first time assessed quantitatively in this study. For that purpose we introduce the "spread factor" and study it on empirical networks of school friendships as well as on various models for social connections. We discover that there exists an ideal number of friendship connections an individual should have to minimize the danger of gossip propagation.

  18. Can rewiring strategy control the epidemic spreading?

    Science.gov (United States)

    Dong, Chao; Yin, Qiuju; Liu, Wenyang; Yan, Zhijun; Shi, Tianyu

    2015-11-01

    Relation existed in the social contact network can affect individuals' behaviors greatly. Considering the diversity of relation intimacy among network nodes, an epidemic propagation model is proposed by incorporating the link-breaking threshold, which is normally neglected in the rewiring strategy. The impact of rewiring strategy on the epidemic spreading in the weighted adaptive network is explored. The results show that the rewiring strategy cannot always control the epidemic prevalence, especially when the link-breaking threshold is low. Meanwhile, as well as strong links, weak links also play a significant role on epidemic spreading.

  19. Lateral spread as a special form of soil movement in Dolina area in municipality Puconci

    Directory of Open Access Journals (Sweden)

    Magda Čarman

    2014-07-01

    Full Text Available The paper presents a particular form of soil instability, which is rarely observed in Slovenia. This is a lateral spread of the soil, which appeared some years ago in the central part of Dolina area in the municipality of Puconci. The area is mainly build up from clay and sandy sediments of the Pannonian Sea, predominantly Pliocene age. A significant damage of building has begun several years ago. According to data from research carried out, we suggest that the flat area is disintegrated into individual blocks, moving in different directions. These led to such extensive damage to buildings. Possible cause could be erosion of Dolinski stream at the eastern edge of the area or seismic survey (blasting, vibrations, which were carried out here about 20 years ago. Determination the exact cause of the formation of the soil lateral spread, its extent and dynamics, remain a challenge for the future.

  20. Exploring Geographic Variability in Cancer Prevalence in Eastern Morocco: A Retrospective Study over Eight Years.

    Science.gov (United States)

    Elidrissi Errahhali, Manal; Elidrissi Errahhali, Mounia; Abda, Naima; Bellaoui, Mohammed

    2016-01-01

    Malignant diseases have been believed to be more common in some areas of Eastern Morocco, but until now, cancer patterns have not been reported for this region. In this paper we present for the first time the cancer prevalence analysis in Eastern Morocco. Cross-sectional study carried out among all patients diagnosed and/or treated with cancer at the Hassan II Regional Oncology Center (ROC) since it was established in October 2005 until December 2012. The ROC is the only hospital specialized in cancer care in Eastern Morocco. A total of 8,508 cases of cancer were registered among residents in Eastern Morocco, with a female to male ratio of 2.1. The mean age at diagnosis was 53.9 ± 15.2 years (median age = 53 years). Thus, unlike in Western countries, cancer in Eastern Morocco afflicts younger population. The areas of Eastern Morocco did not differ significantly by mean age at diagnosis (p = 0.061). However, these regions differed significantly by sex ratio (p Morocco was observed, both in males and females (p Morocco differed significantly by cancer prevalence (p Morocco. Our study illustrates substantial differences in cancer patterns between areas of Eastern Morocco. These findings are important for cancer control and highlight the need to develop program aiming at controlling and preventing the spread of major cancer sites in Eastern Morocco, particularly in areas with increased cancer prevalence rates.

  1. Paleotsunamis in Eastern Taiwan

    Science.gov (United States)

    Yen, Jiun-Yee; Yu, Neng-Ti; Hirakawa, Kazuomi; Chyi, Shyh-Jeng; Huang, Shao-Yi

    2017-04-01

    Although Taiwan is located in the active collision zone between Eurasian and the Philippine Sea plate with very high seismicity in and surrounding the island, and supposedly highly susceptible to tsunami hazard. However, there is no record of tsunami hazard in the past one hundred years, and only very few historical records show some possible extreme event occurred. Therefore study of tsunami was scarce in Taiwan. Although historical records do show possible tsunami events, the records were too sparse and incomplete to confidently reconstruct the paleotsunami events. In the past few years, numerical simulations based on possible tsunami-genic zones near Taiwan show that the island could be affected by the correctly directed tsunami. Nevertheless, there is no detail, scientific research of paleotsunami records yet in Taiwan. Our field survey in eastern Taiwan (facing the western Pacific Ocean) along the coast uncovered several outcrops contain gravels embedded in well-developed soil layers. The rounded meta-sandstone gravels are clearly beach-origin and were brought to their current location upon extreme wave events, which is composed of either volcanic-clastic deposits from nearby hills or organic soil layers formed locally. Our investigation indicates that there are at least 3 events in the northern half of eastern Taiwan and at least 2 events in southern part of eastern Taiwan. Although these outcrops are next to the shoreline and Taiwan is susceptible from typhoons, these gravels could be farther away from the beach at the time of their deposition due to current high retreat rate of the sea cliff. Further investigations are needed to delineate possible sources of tsunamis that caused the deposits.

  2. Experiments on non-isothermal spreading

    International Nuclear Information System (INIS)

    Ehrhard, P.

    1992-09-01

    Experiments are performed on axisymmetric spreading of viscous drops on glass plates. Two liquids are investigated: silicone oil (M-100) spreads to 'infinity' and paraffin oil spreads to a finite-radius steady state. The experiments with silicone oil partly recover the behaviour of previous workers data; those experiments with paraffin oil provide new data. It is found that gravitational forces dominate at long enough times while at shorter times capillary forces dominate. When the plate is heated or cooled with respect to the ambient gas, thermocapillary forces generate flows that alter the spreading dynamics. Heating (cooling) the plate is found to retard (augment) the streading. Moreover, in case of partial wetting, the finally-approached drop radius is smaller (larger) for a heated (cooled) plate. These data are all new. All these observations are in excellent quantitative agreement with the related model predictions of Ehrhard and Davis (1991). A breakdown of the axisymmetric character of the flow is observed only for very long times and/or very thin liquid layers. (orig.) [de

  3. Social Distancing Strategies against Disease Spreading

    Science.gov (United States)

    Valdez, L. D.; Buono, C.; Macri, P. A.; Braunstein, L. A.

    2013-12-01

    The recurrent infectious diseases and their increasing impact on the society has promoted the study of strategies to slow down the epidemic spreading. In this review we outline the applications of percolation theory to describe strategies against epidemic spreading on complex networks. We give a general outlook of the relation between link percolation and the susceptible-infected-recovered model, and introduce the node void percolation process to describe the dilution of the network composed by healthy individual, i.e., the network that sustain the functionality of a society. Then, we survey two strategies: the quenched disorder strategy where an heterogeneous distribution of contact intensities is induced in society, and the intermittent social distancing strategy where health individuals are persuaded to avoid contact with their neighbors for intermittent periods of time. Using percolation tools, we show that both strategies may halt the epidemic spreading. Finally, we discuss the role of the transmissibility, i.e., the effective probability to transmit a disease, on the performance of the strategies to slow down the epidemic spreading.

  4. Disease spreading in real-life networks

    Science.gov (United States)

    Gallos, Lazaros; Argyrakis, Panos

    2002-08-01

    In recent years the scientific community has shown a vivid interest in the network structure and dynamics of real-life organized systems. Many such systems, covering an extremely wide range of applications, have been recently shown to exhibit scale-free character in their connectivity distribution, meaning that they obey a power law. Modeling of epidemics on lattices and small-world networks suffers from the presence of a critical infection threshold, above which the entire population is infected. For scale-free networks, the original assumption was that the formation of a giant cluster would lead to an epidemic spreading in the same way as in simpler networks. Here we show that modeling epidemics on a scale-free network can greatly improve the predictions on the rate and efficiency of spreading, as compared to lattice models and small-world networks. We also show that the dynamics of a disease are greatly influenced by the underlying population structure. The exact same model can describe a plethora of networks, such as social networks, virus spreading in the Web, rumor spreading, signal transmission etc.

  5. Spread of Rare Fungus from Vancouver Island

    Centers for Disease Control (CDC) Podcasts

    2006-12-20

    Cryptococcus gattii, a rare fungus normally found in the tropics, has infected people and animals on Vancouver Island, Canada. Dr. David Warnock, Director, Division of Foodborne, Bacterial, and Mycotic Diseases, CDC, discusses public health concerns about further spread of this organism.  Created: 12/20/2006 by Emerging Infectious Diseases.   Date Released: 12/29/2006.

  6. DataSpread: Unifying Databases and Spreadsheets.

    Science.gov (United States)

    Bendre, Mangesh; Sun, Bofan; Zhang, Ding; Zhou, Xinyan; Chang, Kevin ChenChuan; Parameswaran, Aditya

    2015-08-01

    Spreadsheet software is often the tool of choice for ad-hoc tabular data management, processing, and visualization, especially on tiny data sets. On the other hand, relational database systems offer significant power, expressivity, and efficiency over spreadsheet software for data management, while lacking in the ease of use and ad-hoc analysis capabilities. We demonstrate DataSpread, a data exploration tool that holistically unifies databases and spreadsheets. It continues to offer a Microsoft Excel-based spreadsheet front-end, while in parallel managing all the data in a back-end database, specifically, PostgreSQL. DataSpread retains all the advantages of spreadsheets, including ease of use, ad-hoc analysis and visualization capabilities, and a schema-free nature, while also adding the advantages of traditional relational databases, such as scalability and the ability to use arbitrary SQL to import, filter, or join external or internal tables and have the results appear in the spreadsheet. DataSpread needs to reason about and reconcile differences in the notions of schema, addressing of cells and tuples, and the current "pane" (which exists in spreadsheets but not in traditional databases), and support data modifications at both the front-end and the back-end. Our demonstration will center on our first and early prototype of the DataSpread, and will give the attendees a sense for the enormous data exploration capabilities offered by unifying spreadsheets and databases.

  7. Unidirectional spreading of oil under solid ice

    International Nuclear Information System (INIS)

    Weerasuriya, S.A.; Yapa, P.D.

    1993-01-01

    Equations are presented to describe the unidirectional spreading of oil under solid ice covers floating in calm water. These spreading equations are derived using a simplified form of the Navier-Stokes equations, and cover both the constant discharge and the constant volume modes. An equation for computing final slick length is also given. Laboratory experiments using physical models were conducted to verify the equations. The experiments used oils of different viscosities, ice cover roughnesses varying from smooth to rough, and a variety of discharge conditions. The emphasis of the study was on the dominant spreading mechanism for oil under ice, which is the buoyancy-viscous phase. The laboratory results agree closely with the theoretical predictions. Discrepancies can be attributed to the experimental difficulties and errors introduced from the assumptions made in deriving the theory. The equations presented will be useful in computing spreading rate during an accidental oil spill or in contingency planning. The equations are simple to use, suitable for hand calculations or for incorporation into numerical models for oil spill simulation. 24 refs., 10 figs., 1 tab

  8. Modelling of fire spread in car parks

    NARCIS (Netherlands)

    Noordijk, L.M.; Lemaire, A.D.

    2005-01-01

    Currently, design codes assume that in a car park fire at most 3-4 vehicles are on fire at the same time. Recent incidents in car parks have drawn international attention to such assumptions and have raised questions as to the fire spreading mechanism and the resulting fire load on the structure.

  9. Spread of Rare Fungus from Vancouver Island

    Centers for Disease Control (CDC) Podcasts

    Cryptococcus gattii, a rare fungus normally found in the tropics, has infected people and animals on Vancouver Island, Canada. Dr. David Warnock, Director, Division of Foodborne, Bacterial, and Mycotic Diseases, CDC, discusses public health concerns about further spread of this organism

  10. Energy spread in ion beam analysis

    International Nuclear Information System (INIS)

    Szilagyi, E.

    2000-01-01

    In ion beam analysis (IBA) the depth profiles are extracted from the experimentally determined energy profiles. The spectra, however, are subject to finite energy resolution of both extrinsic and intrinsic origin. Calculation of those effects such as instrumental beam, geometry and detection-related energy and angular spreads as well as energy straggling, multiple scattering and Doppler effects in the sample itself is not trivial, especially since it involves treatment of non-independent random processes. A proper account for energy spread is vital in IBA not only for correct extraction of elemental and isotopic depth profiles from the measured spectra, but already prior to data acquisition, in optimising experimental conditions to reach the required depth resolution at a certain depth. After a short review of the literature on the different energy spread contributions experimental examples are given from resonance, RBS, elastic BS and ERDA practice in which an account for energy spread contributions is essential. Some further examples illustrate extraction of structural information (roughness, pore size, etc.) from elaborated depth resolution calculation for such layer structures

  11. Energy spread in ion beam analysis

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, E. E-mail: szilagyi@rmki.kkfki.hu

    2000-03-01

    In ion beam analysis (IBA) the depth profiles are extracted from the experimentally determined energy profiles. The spectra, however, are subject to finite energy resolution of both extrinsic and intrinsic origin. Calculation of those effects such as instrumental beam, geometry and detection-related energy and angular spreads as well as energy straggling, multiple scattering and Doppler effects in the sample itself is not trivial, especially since it involves treatment of non-independent random processes. A proper account for energy spread is vital in IBA not only for correct extraction of elemental and isotopic depth profiles from the measured spectra, but already prior to data acquisition, in optimising experimental conditions to reach the required depth resolution at a certain depth. After a short review of the literature on the different energy spread contributions experimental examples are given from resonance, RBS, elastic BS and ERDA practice in which an account for energy spread contributions is essential. Some further examples illustrate extraction of structural information (roughness, pore size, etc.) from elaborated depth resolution calculation for such layer structures.

  12. International business of banking: the pricing example of retail currency spreads

    Directory of Open Access Journals (Sweden)

    Enn Listra

    2013-05-01

    Full Text Available In this paper the pricing of a specific service of currency exchange based on the retail exchange rate spreads is studied on the example of four international banking groups. The aim of this study is to explore pricing of currency exchange services based on bid-ask differences in some commercial banks and possible price discrimination in this segment of market comparing the behaviour of Western mothers and Eastern daughters in European international banking groups. The retail currency rate spreads in different bank groups and countries are compared with each other. The main results of the study are that statistically significant differences exist in the spreads set by banking groups in different countries. All banking groups in the pilot sample offer more favourable rates in Western countries indicating that the pricing policy of bank groups may be discriminatory. The volatility of spreads over different currencies suggests that different decision making mechanisms may be present in the groups depending on the location of banking unit. The results of this pilot study suggest that further research is needed to understand the extent and the mechanism of findings.

  13. Revised South China Sea spreading history based on macrostructure analysis of IODP Expedition 349 core samples and geophysical data

    Science.gov (United States)

    Sun, Z.; Ding, W.; Zhao, X.; Qiu, N.; Lin, J.; Li, C.

    2017-12-01

    In Internaltional Ocean Discovery Program (IODP) Expedition 349, four sites were drilled and cored successfully in the South China Sea (SCS). Three of them are close to the central spreading ridge (Sites U1431, U1433 and U1434), and one (Site U1435) is located on an outer rise,,providingsignificant information on the spreading history of the SCS.In order to constrain the spreading historymore accurately with the core results, we analyzed the identifiable macrostructures (over 300 fractures, veins and slickensides)from all the consolidated samples of these four drill sites. Then we made a retrograde reconstruction of the SCS spreading history with the constraints of the estimated fractures and veins, post-spreading volcanism,seismic interpretation, as well as free-air gravity and magnetic anomaly and topography analysis. Our study indicates that the spreading of the SCS experienced at least one ridge jump event and two events of ridge orientation and spreading direction adjustment, which mademagnetic anomaly orientation, ridge positionand facture zone directionskeep changing in the South China Sea. During the last spreading stage, the spreading direction was north-southward but lasted for a very short time period. The oceanic crust is wider in the eastern SCS and tapers out toward west.Due to the subductionof SCS beneath the Philippine Sea plate, the seafloor began to develop new fractures:the NWW-to EW-trending R' shear faults and the NE-trending P faultsbecame dominant faults and controlled the eruption of post-drift volcanism.

  14. Energy in Eastern Europe

    International Nuclear Information System (INIS)

    Bouma, J.W.J.

    1993-01-01

    The present energy market in Central and Eastern Europe differs strongly from the energy situation in open market economies. Compared to the European Communities, the energy market in Central and eastern Europe is characterized by its high energy intensity, high quantity of imported oil and gas from a one country (the ex-Soviet Union), the dominant role of solid fossil fuels in some countries, and environmental pollution. Expected future developments are the reduction of the energy intensity and the total energy consumption, the reduction of the industrial energy consumption, the reduction of the solid fossil fuels as well as the geographic distribution of energy import. The restructuring of the energy industry has been started by introducing a market orientated policy including privatisation and the promotion of the free play of price-making forces, accompanied by relatively small-scale investments. Recent data indicate a decrease of energy consumption due to the economic decline and the shut-down of companies in the heavy industries. (A.S.) 4 figs. 5 tabs

  15. Pipelines to eastern Canada

    International Nuclear Information System (INIS)

    Otsason, J.

    1998-01-01

    This presentation focused on four main topics: (1) the existing path of pipelines to eastern Canada, (2) the Chicago hub, (3) transport alternatives, and (4) the Vector Pipeline' expansion plans. In the eastern Canadian market, TransCanada Pipelines dominates 96 per cent of the market share and is effectively immune to expansion costs. Issues regarding the attractiveness of the Chicago hub were addressed. One attractive feature is that the Chicago hub has access to multiple supply basins including western Canada, the Gulf Coast, the mid-continent, and the Rockies. Regarding Vector Pipelines' future plans, the company proposes to construct 343 miles of pipeline from Joliet, Illinois to Dawn, Ontario. Project description included discussion of some of the perceived advantages of this route, namely, extensive storage in Michigan and south-western Ontario, the fact that the proposed pipeline traverses major markets which would mitigate excess capacity concerns, arbitrage opportunities, cost effective expansion capability reducing tolls, and likely lower landed costs in Ontario. Project schedule, costs, rates and tariffs are also discussed. tabs., figs

  16. Population genetic structure of a common host predicts the spread of white-nose syndrome, an emerging infectious disease in bats.

    Science.gov (United States)

    Wilder, Aryn P; Kunz, Thomas H; Sorenson, Michael D

    2015-11-01

    Landscape complexity influences patterns of animal dispersal, which in turn may affect both gene flow and the spread of pathogens. White-nose syndrome (WNS) is an introduced fungal disease that has spread rapidly throughout eastern North America, causing massive mortality in bat populations. We tested for a relationship between the population genetic structure of the most common host, the little brown myotis (Myotis lucifugus), and the geographic spread of WNS to date by evaluating logistic regression models of WNS risk among hibernating colonies in eastern North America. We hypothesized that risk of WNS to susceptible host colonies should increase with both geographic proximity and genetic similarity, reflecting historical connectivity, to infected colonies. Consistent with this hypothesis, inclusion of genetic distance between infected and susceptible colonies significantly improved models of disease spread, capturing heterogeneity in the spatial expansion of WNS despite low levels of genetic differentiation among eastern populations. Expanding our genetic analysis to the continental range of little brown myotis reveals strongly contrasting patterns of population structure between eastern and western North America. Genetic structure increases markedly moving westward into the northern Great Plains, beyond the current distribution of WNS. In western North America, genetic differentiation of geographically proximate populations often exceeds levels observed across the entire eastern region, suggesting infrequent and/or locally restricted dispersal, and thus relatively limited opportunities for pathogen introduction in western North America. Taken together, our analyses suggest a possibly slower future rate of spread of the WNS pathogen, at least as mediated by little brown myotis. © 2015 John Wiley & Sons Ltd.

  17. Eastern Sources of Invitational Education.

    Science.gov (United States)

    Ryback, David

    1993-01-01

    Presents historical perspective suggesting that invitational theory shares many beliefs with ancient Eastern philosophies. Submits that teachers and other educators who embrace the invitational perspective may benefit from an understanding of Eastern principles. Briefly describes Buddhism, Confucianism, Taoism, Zen Buddhism, and their relevance to…

  18. Rhinoplasty in Middle Eastern Patients.

    Science.gov (United States)

    Sajjadian, Ali

    2016-01-01

    Rhinoplasty in patients of Middle Eastern origin requires complete understanding of nasal morphology and an individualized approach to create a racially congruent and aesthetically pleasing outcome. In this article, common anatomic features and characteristics and detailed steps, surgical techniques, and operative maneuvers that can lead to predictable outcome in rhinoplasty of Middle Eastern patients are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Social networks and spreading of epidemics

    Science.gov (United States)

    Trimper, Steffen; Zheng, Dafang; Brandau, Marian

    2004-05-01

    Epidemiological processes are studied within a recently proposed social network model using the susceptible-infected-refractory dynamics (SIR) of an epidemic. Within the network model, a population of individuals may be characterized by H independent hierarchies or dimensions, each of which consists of groupings of individuals into layers of subgroups. Detailed numerical simulations reveals that for H > 1, the global spreading results regardless of the degree of homophily α of the individuals forming a social circle. For H = 1, a transition from a global to a local spread occurs as the population becomes decomposed into increasingly homophilous groups. Multiple dimensions in classifying individuals (nodes) thus make a society (computer network) highly susceptible to large scale outbreaks of infectious diseases (viruses). The SIR-model can be extended by the inclusion of waiting times resulting in modified distribution function of the recovered.

  20. GENERAL: Epidemic spreading on networks with vaccination

    Science.gov (United States)

    Shi, Hong-Jing; Duan, Zhi-Sheng; Chen, Guan-Rong; Li, Rong

    2009-08-01

    In this paper, a new susceptible-infected-susceptible (SIS) model on complex networks with imperfect vaccination is proposed. Two types of epidemic spreading patterns (the recovered individuals have or have not immunity) on scale-free networks are discussed. Both theoretical and numerical analyses are presented. The epidemic thresholds related to the vaccination rate, the vaccination-invalid rate and the vaccination success rate on scale-free networks are demonstrated, showing different results from the reported observations. This reveals that whether or not the epidemic can spread over a network under vaccination control is determined not only by the network structure but also by the medicine's effective duration. Moreover, for a given infective rate, the proportion of individuals to vaccinate can be calculated theoretically for the case that the recovered nodes have immunity. Finally, simulated results are presented to show how to control the disease prevalence.

  1. Epidemic spreading on weighted complex networks

    International Nuclear Information System (INIS)

    Sun, Ye; Liu, Chuang; Zhang, Chu-Xu; Zhang, Zi-Ke

    2014-01-01

    Nowadays, the emergence of online services provides various multi-relation information to support the comprehensive understanding of the epidemic spreading process. In this Letter, we consider the edge weights to represent such multi-role relations. In addition, we perform detailed analysis of two representative metrics, outbreak threshold and epidemic prevalence, on SIS and SIR models. Both theoretical and simulation results find good agreements with each other. Furthermore, experiments show that, on fully mixed networks, the weight distribution on edges would not affect the epidemic results once the average weight of whole network is fixed. This work may shed some light on the in-depth understanding of epidemic spreading on multi-relation and weighted networks.

  2. Epidemic spreading on weighted complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ye [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Liu, Chuang, E-mail: liuchuang@hznu.edu.cn [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Chu-Xu [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China); Zhang, Zi-Ke, E-mail: zhangzike@gmail.com [Institute of Information Economy, Hangzhou Normal University, Hangzhou 311121 (China); Alibaba Research Center of Complexity Science, Hangzhou Normal University, Hangzhou 311121 (China)

    2014-01-31

    Nowadays, the emergence of online services provides various multi-relation information to support the comprehensive understanding of the epidemic spreading process. In this Letter, we consider the edge weights to represent such multi-role relations. In addition, we perform detailed analysis of two representative metrics, outbreak threshold and epidemic prevalence, on SIS and SIR models. Both theoretical and simulation results find good agreements with each other. Furthermore, experiments show that, on fully mixed networks, the weight distribution on edges would not affect the epidemic results once the average weight of whole network is fixed. This work may shed some light on the in-depth understanding of epidemic spreading on multi-relation and weighted networks.

  3. Spread of edema with brain tumors

    International Nuclear Information System (INIS)

    Hosoya, Takaaki

    1987-01-01

    Cerebral edema associated with brain tumors is visualized on CT as a hypodensity lesion involving mainly the white matter. The detailed features of its evolution were investigated in a review of CT examinations performed on 56 patients with brain tumors, with the following results. 1. The susceptibility to edema varied according to the types of fibers. Association fibers were more sensitive to edema than projection and commissural fibers. 2. The edema had a characteristic of spreading along not only the association fibers but also the projection and commissural fibers. 3. The spread of edema along the association fibers was interupted in sites of convergence of the fibers such as the external capsule and just beneath the central sulcus in the certrum semiovale. 4. In some cases with intra-axial tumors, the edema extended mainly in the projection and commissural fibers considered to be more resistant to it. For example, in cases with parietal and temporal intra-axial tumors, the posterior limb of the internal capsule was often more edematous than the external capsule. 5. The edema associated with meningioma had a characteristic of spreading mainly along the association fibers. When situated close to the corpus callosum, however, the commissural fibers were also involved. Edema extending mainly in the internal capsule, thus, was rarely observed in meningioma. 6. There was unique pattern of spread of edema in frontal tumors, which differentiated their CT pattern. Therefore, the location of the tumor could be correctly diagnosed by the pattern of the edema extension, even near the central sulcus or in the operculum region. (author)

  4. Spreading of a relativistic wave packet

    International Nuclear Information System (INIS)

    Almeida, C.; Jabs, A.

    1983-01-01

    A simple general proof that the spreading velocity of a relativistic free wave packet of the Broglie waves is limited is presented. For a wide class of packets it is confirmed that the limit is the velocity of light, and it is shown how this limit is approached when the width Δp of the wave packet in momentum space tends to infinity and the minimum width σ(t=o) in ordinary space tends to zero. (Author) [pt

  5. The Equilibrium Spreading Tension of Pulmonary Surfactant

    OpenAIRE

    Dagan, Maayan P.; Hall, Stephen B.

    2015-01-01

    Monomolecular films at an air/water interface coexist at the equilibrium spreading tension (γe) with the bulk phase from which they form. For individual phospholipids, γe is single-valued, and separates conditions at which hydrated vesicles adsorb from tensions at which overcompressed monolayers collapse. With pulmonary surfactant, isotherms show that monolayers compressed on the surface of bubbles coexist with the three-dimensional collapsed phase over a range of surface tensions. γe therefo...

  6. Eastern Equine Encephalitis Virus

    Energy Technology Data Exchange (ETDEWEB)

    Borucki, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-08-05

    Eastern equine encephalitis virus (EEEV) is a mosquito-borne virus capable of causing large outbreaks of encephalitis in humans and horses. In North America, EEEV infection has a very high mortality rate in humans, and survivors often suffer severe neurological sequelae. Interestingly, EEEV infections from South American isolates are generally subclinical. Although EEEV is divided into two antigenic varieties and four lineages, only eleven isolates have been sequenced and eight of these are from the North American variety (Lineage I). Most sequenced strains were collected from mosquitoes and only one human isolate has been sequenced. EEEV isolates exist from a variety of hosts, vectors, years, and geographical locations and efforts should focus on sequencing strains that represent this diversity.

  7. Middle Eastern power systems

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Middle Eastern Power systems have evolved independently of each other over many decades. The region covers a wide geographical area of over 4 million square kilometers with an estimated population in 1990 of over 120 million people. This paper discusses the present status and future power system developments in the Middle East with emphasis on the Mashrequ Arab Countries (MAC). MAC consists of Egypt, Iraq, Jordan, Lebanon, Syria, Yemen, and the six Gulf Cooperation Council (GCC) countries, namely, Bahrain, Kuwait, Qatar, Saudi Arabia, Oman, and the United Arab Emirates (UAE). Interconnections within MAC and possible extensions to Turkey, Europe, and Central Africa are discussed. A common characteristic of the MAC power systems is that they are all operated by government or semi-government bodies. The energy resources in the region are varied. Countries such as Iraq, Egypt, and Syria have significant hydro power resources. On the other hand, the GCC countries and Iraq have abundant fossil fuel reserves

  8. Physical model for membrane protrusions during spreading

    International Nuclear Information System (INIS)

    Chamaraux, F; Ali, O; Fourcade, B; Keller, S; Bruckert, F

    2008-01-01

    During cell spreading onto a substrate, the kinetics of the contact area is an observable quantity. This paper is concerned with a physical approach to modeling this process in the case of ameboid motility where the membrane detaches itself from the underlying cytoskeleton at the leading edge. The physical model we propose is based on previous reports which highlight that membrane tension regulates cell spreading. Using a phenomenological feedback loop to mimic stress-dependent biochemistry, we show that the actin polymerization rate can be coupled to the stress which builds up at the margin of the contact area between the cell and the substrate. In the limit of small variation of membrane tension, we show that the actin polymerization rate can be written in a closed form. Our analysis defines characteristic lengths which depend on elastic properties of the membrane–cytoskeleton complex, such as the membrane–cytoskeleton interaction, and on molecular parameters, the rate of actin polymerization. We discuss our model in the case of axi-symmetric and non-axi-symmetric spreading and we compute the characteristic time scales as a function of fundamental elastic constants such as the strength of membrane–cytoskeleton adherence

  9. Diffusion, spread, and migration of botulinum toxin.

    Science.gov (United States)

    Ramirez-Castaneda, Juan; Jankovic, Joseph; Comella, Cynthia; Dashtipour, Khashayar; Fernandez, Hubert H; Mari, Zoltan

    2013-11-01

    Botulinum toxin (BoNT) is an acetylcholine release inhibitor and a neuromuscular blocking agent used for the treatment of a variety of neurologic and medical conditions. The efficacy and safety of BoNT depends on accurate selection and identification of intended targets but also may be determined by other factors, including physical spread of the molecule from the injection site, passive diffusion, and migration to distal sites via axonal or hematogenous transport. The passive kinetic dispersion of the toxin away from the injection site in a gradient-dependent manner may also play a role in toxin spread. In addition to unique properties of the various BoNT products, volume and dilution may also influence local and systemic distribution of BoNT. Most of the local and remote complications of BoNT injections are thought to be due to unwanted spread or diffusion of the toxin's biologic activity into adjacent and distal muscles. Despite widespread therapeutic and cosmetic use of BoNT over more than three decades, there is a remarkable paucity of published data on the mechanisms of distribution and its effects on clinical outcomes. The primary aim of this article is to critically review the available experimental and clinical literature and place it in the practical context. © 2013 International Parkinson and Movement Disorder Society.

  10. Mechanistic movement models to understand epidemic spread.

    Science.gov (United States)

    Fofana, Abdou Moutalab; Hurford, Amy

    2017-05-05

    An overlooked aspect of disease ecology is considering how and why animals come into contact with one and other resulting in disease transmission. Mathematical models of disease spread frequently assume mass-action transmission, justified by stating that susceptible and infectious hosts mix readily, and foregoing any detailed description of host movement. Numerous recent studies have recorded, analysed and modelled animal movement. These movement models describe how animals move with respect to resources, conspecifics and previous movement directions and have been used to understand the conditions for the occurrence and the spread of infectious diseases when hosts perform a type of movement. Here, we summarize the effect of the different types of movement on the threshold conditions for disease spread. We identify gaps in the literature and suggest several promising directions for future research. The mechanistic inclusion of movement in epidemic models may be beneficial for the following two reasons. Firstly, the estimation of the transmission coefficient in an epidemic model is possible because animal movement data can be used to estimate the rate of contacts between conspecifics. Secondly, unsuccessful transmission events, where a susceptible host contacts an infectious host but does not become infected can be quantified. Following an outbreak, this enables disease ecologists to identify 'near misses' and to explore possible alternative epidemic outcomes given shifts in ecological or immunological parameters.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Author(s).

  11. Observed and Modeled Pathways of the Iceland Scotland Overflow Water in the eastern North Atlantic

    Science.gov (United States)

    Zou, Sijia; Lozier, Susan; Zenk, Walter; Bower, Amy; Johns, William

    2017-04-01

    The Iceland Scotland Overflow Water (ISOW), one of the major components of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC), is formed in the Nordic Seas and enters the eastern North Atlantic subpolar gyre via the Iceland-Scotland sill. After entraining the ambient waters, the relatively homogeneous ISOW spreads southward into the North Atlantic. An understanding of the distribution and variability of the spreading pathways of the ISOW is fundamental to our understanding of AMOC structure and variability. Three major ISOW pathways have been identified in the eastern North Atlantic by previous studies: 1) across the Reykjanes Ridge via deep gaps, 2) through the Charlie Gibbs Fracture Zone, and 3) southward along the eastern flank of the Mid Atlantic Ridge (MAR). However, most of these studies were conducted using an Eulerian frame with limited observations, especially for the third pathway along the eastern flank of the MAR. In this work, we give a comprehensive description of ISOW pathways in the Eulerian and Lagrangian frames, quantify the relative importance of each pathway and examine the temporal variability of these pathways. Our study distinguishes itself from past studies by using both Eulerian (current meter data) and Lagrangian (eddy-resolving RAFOS float data) observations in combination with modeling output (1/12° FLAME) to describe ISOW spreading pathways and their variability.

  12. Observed and modeled pathways of the Iceland Scotland Overflow Water in the eastern North Atlantic

    Science.gov (United States)

    Zou, Sijia; Lozier, Susan; Zenk, Walter; Bower, Amy; Johns, William

    2017-12-01

    The spreading of Iceland Scotland Overflow Water (ISOW) in the eastern North Atlantic has largely been studied in an Eulerian frame using numerical models or with observations limited to a few locations. No study to date has provided a comprehensive description of the ISOW spreading pathways from both Eulerian and Lagrangian perspectives. In this paper, we use a combination of previously unreported current meter data, hydrographic data, RAFOS float data, and a high resolution (1/12°) numerical ocean model to study the spreading pathways of ISOW from both of these perspectives. We identify three ISOW transport cores in the central Iceland Basin (∼59°N), with the major core along the eastern boundary of the Reykjanes Ridge (RR) and the other two in the basin interior. Based on trajectories of observed and/or numerical floats seeded along 59°N, we also describe the ISOW spreading pathways and quantify their relative importance. Within 10 years, 7-11% of ISOW from 59°N escapes into the Irminger Sea via gaps in the RR north of the Charlie Gibbs Fracture Zone (CGFZ); the water that moves through these gaps principally originates from the shallower ISOW layer along the RR eastern boundary. 10-13% travels further southward until the CGFZ, where it crosses westward into the western subpolar gyre. 18-21% of ISOW spreads southward along the eastern flank of the Mid-Atlantic Ridge into the Western European Basin (WEB). Most of the remaining water stays in the Iceland Basin over the 10-year period. A model-based investigation provides a first look at the temporal variability of these ISOW pathways. We find that the fraction of southward water exported into the WEB is anti-correlated with the export through the CGFZ, a result assumed to reflect these pathways' interactions with the North Atlantic Current in magnitude and/or position shift.

  13. A low-cost and reliable technique to monitor the spread of an invasive seagrass in the Caribbean Sea

    Science.gov (United States)

    Jobsis, D.; Wyllie-Echeverria, S.

    2016-02-01

    In 2002 the seagrass Halophila stipulacea was observed in Grenada in the Eastern Caribbean Sea. Since then this invasive species has spread northward through the Lesser Antilles and Leeward Islands into the US Virgin Islands. There are native Halophila species as well as other seagrass species in Eastern Caribbean therefore it is essential to accurately identify H. stipulacea before an invasion event is reported. Moreover, because the consequences of H. stipulaceapresence and spread are not known in many locations, after accurate identification is made it is also important to map patch expansion as a first step in process studies designed to determine impact. We now report a low-cost (GoPro video camera placed inside underwater housing, a weighted towfish and a GPS tracking device. The camera, set in the time-lapse mode, is fixed to the towfish; Afterward using a series of straight line transects, our array is towed at low speeds while synched to GPS. The accuracy of an underwater video system is based on knowing the accurate position of seagrass on the seafloor during filming (Norris et al. 1997). After sampling images and their associated GPS coordinates are imported to a spreadsheet and coded such that H. stipulaceais related to a known position on the bottom. With this system we produce accurate maps that specifically identify H. stipulacea patches, regardless of water depth, on the seafloor. During our poster presentation we will show a series of images from 2015 sampling and display mapping results. Since the 2002 sighting in Grenada, H. stipulaceae has spread northward to nineteen Eastern Caribbean Islands (Williette et al 2014). Our technique will allow those charged with protecting natural resources to track the spread of this invasion and potentially provide an early warning system for islands nations not yet invaded.

  14. Default Spread dan Term Spread sebagai Variabel Proxy Siklus Bisnis pada Model Fama-French

    Directory of Open Access Journals (Sweden)

    Edwin Hendra

    2015-08-01

    Full Text Available This research aims to apply the Fama-French models and test the effect of alternative variable of bond yield spread, default spread (RBBB – RAAA and RAAA – RF, and the term spread (RSUN10-RSUN1, as proxy variables of the business cycle, in IDX stock data during 2005-2010. Four types of asset pricing models tested are Sharpe-Lintner CAPM, Fama-French models, Hwang et al.model, and hybrid model. The results showed that the size effect and value effect has an impact on excess stock returns. Slopes of market beta, SMB, and HML are more sensitive to stock big size and high B / M. Default spreads and term spreads in Hwang et al. model can explain the value effect, and weakly explain the size effect, meanwhile the power of explanation disappeared on Hybrid models. Based on the assessment adjusted R2 and the frequency of rejection of non-zero alpha, is found that the hybrid model is the most suitable model.  

  15. Spreading in online social networks: the role of social reinforcement.

    Science.gov (United States)

    Zheng, Muhua; Lü, Linyuan; Zhao, Ming

    2013-07-01

    Some epidemic spreading models are usually applied to analyze the propagation of opinions or news. However, the dynamics of epidemic spreading and information or behavior spreading are essentially different in many aspects. Centola's experiments [Science 329, 1194 (2010)] on behavior spreading in online social networks showed that the spreading is faster and broader in regular networks than in random networks. This result contradicts with the former understanding that random networks are preferable for spreading than regular networks. To describe the spreading in online social networks, a unknown-known-approved-exhausted four-status model was proposed, which emphasizes the effect of social reinforcement and assumes that the redundant signals can improve the probability of approval (i.e., the spreading rate). Performing the model on regular and random networks, it is found that our model can well explain the results of Centola's experiments on behavior spreading and some former studies on information spreading in different parameter space. The effects of average degree and network size on behavior spreading process are further analyzed. The results again show the importance of social reinforcement and are accordant with Centola's anticipation that increasing the network size or decreasing the average degree will enlarge the difference of the density of final approved nodes between regular and random networks. Our work complements the former studies on spreading dynamics, especially the spreading in online social networks where the information usually requires individuals' confirmations before being transmitted to others.

  16. Predictive validation of an influenza spread model.

    Directory of Open Access Journals (Sweden)

    Ayaz Hyder

    Full Text Available BACKGROUND: Modeling plays a critical role in mitigating impacts of seasonal influenza epidemics. Complex simulation models are currently at the forefront of evaluating optimal mitigation strategies at multiple scales and levels of organization. Given their evaluative role, these models remain limited in their ability to predict and forecast future epidemics leading some researchers and public-health practitioners to question their usefulness. The objective of this study is to evaluate the predictive ability of an existing complex simulation model of influenza spread. METHODS AND FINDINGS: We used extensive data on past epidemics to demonstrate the process of predictive validation. This involved generalizing an individual-based model for influenza spread and fitting it to laboratory-confirmed influenza infection data from a single observed epidemic (1998-1999. Next, we used the fitted model and modified two of its parameters based on data on real-world perturbations (vaccination coverage by age group and strain type. Simulating epidemics under these changes allowed us to estimate the deviation/error between the expected epidemic curve under perturbation and observed epidemics taking place from 1999 to 2006. Our model was able to forecast absolute intensity and epidemic peak week several weeks earlier with reasonable reliability and depended on the method of forecasting-static or dynamic. CONCLUSIONS: Good predictive ability of influenza epidemics is critical for implementing mitigation strategies in an effective and timely manner. Through the process of predictive validation applied to a current complex simulation model of influenza spread, we provided users of the model (e.g. public-health officials and policy-makers with quantitative metrics and practical recommendations on mitigating impacts of seasonal influenza epidemics. This methodology may be applied to other models of communicable infectious diseases to test and potentially improve

  17. Vectorised Spreading Activation algorithm for centrality measurement

    Directory of Open Access Journals (Sweden)

    Alexander Troussov

    2011-01-01

    Full Text Available Spreading Activation is a family of graph-based algorithms widely used in areas such as information retrieval, epidemic models, and recommender systems. In this paper we introduce a novel Spreading Activation (SA method that we call Vectorised Spreading Activation (VSA. VSA algorithms, like “traditional” SA algorithms, iteratively propagate the activation from the initially activated set of nodes to the other nodes in a network through outward links. The level of the node’s activation could be used as a centrality measurement in accordance with dynamic model-based view of centrality that focuses on the outcomes for nodes in a network where something is flowing from node to node across the edges. Representing the activation by vectors allows the use of the information about various dimensionalities of the flow and the dynamic of the flow. In this capacity, VSA algorithms can model multitude of complex multidimensional network flows. We present the results of numerical simulations on small synthetic social networks and multi­dimensional network models of folksonomies which show that the results of VSA propagation are more sensitive to the positions of the initial seed and to the community structure of the network than the results produced by traditional SA algorithms. We tentatively conclude that the VSA methods could be instrumental to develop scalable and computationally efficient algorithms which could achieve synergy between computation of centrality indexes with detection of community structures in networks. Based on our preliminary results and on improvements made over previous studies, we foresee advances and applications in the current state of the art of this family of algorithms and their applications to centrality measurement.

  18. Predictive Validation of an Influenza Spread Model

    Science.gov (United States)

    Hyder, Ayaz; Buckeridge, David L.; Leung, Brian

    2013-01-01

    Background Modeling plays a critical role in mitigating impacts of seasonal influenza epidemics. Complex simulation models are currently at the forefront of evaluating optimal mitigation strategies at multiple scales and levels of organization. Given their evaluative role, these models remain limited in their ability to predict and forecast future epidemics leading some researchers and public-health practitioners to question their usefulness. The objective of this study is to evaluate the predictive ability of an existing complex simulation model of influenza spread. Methods and Findings We used extensive data on past epidemics to demonstrate the process of predictive validation. This involved generalizing an individual-based model for influenza spread and fitting it to laboratory-confirmed influenza infection data from a single observed epidemic (1998–1999). Next, we used the fitted model and modified two of its parameters based on data on real-world perturbations (vaccination coverage by age group and strain type). Simulating epidemics under these changes allowed us to estimate the deviation/error between the expected epidemic curve under perturbation and observed epidemics taking place from 1999 to 2006. Our model was able to forecast absolute intensity and epidemic peak week several weeks earlier with reasonable reliability and depended on the method of forecasting-static or dynamic. Conclusions Good predictive ability of influenza epidemics is critical for implementing mitigation strategies in an effective and timely manner. Through the process of predictive validation applied to a current complex simulation model of influenza spread, we provided users of the model (e.g. public-health officials and policy-makers) with quantitative metrics and practical recommendations on mitigating impacts of seasonal influenza epidemics. This methodology may be applied to other models of communicable infectious diseases to test and potentially improve their predictive

  19. Directional spread parameter at intermediate water depth

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Deo, M.C.; Anand, N.M.; AshokKumar, K.

    ’ involves only the significant wave height, zero crossing wave period and water depth, the spreading function based on ‘s 3 ’ can be used for practical appli- cation. In the model based on ‘s 3 ’ the mean wave direction is an input and this has...-linearity parameter can be recommended for practical use as it provides an averaged distribution. Acknowledgements The authors would like to thank the Department of Science and Technology, New Delhi, for funding the project titled “Directional wave modelling...

  20. Trigeminal perineural spread of renal cell carcinoma

    International Nuclear Information System (INIS)

    Hornik, Alejandro; Rosenblum, Jordan; Biller, Jose

    2012-01-01

    A 55-year-old man had a five-day history of “pins and needles” sensation on the left chin. Examination showed decreased pinprick sensation on the territory of the left mandibular branch of the trigeminal nerve. Brain magnetic resonance imaging (MRI) with gadolinium showed enhancement involving the left mandibular branch. Computed tomography (CT) of the chest, abdomen, and pelvis showed a left kidney mass diagnosed as renal carcinoma following nephrectomy. The “numb-chin” syndrome heralds or accompanies systemic malignancies. Trigeminal perineural spread has been well-documented in head and neck neoplasms, however, to our knowledge, it has not been reported in renal neoplasms. (author)

  1. Simultaneous spreading and evaporation: recent developments.

    Science.gov (United States)

    Semenov, Sergey; Trybala, Anna; Rubio, Ramon G; Kovalchuk, Nina; Starov, Victor; Velarde, Manuel G

    2014-04-01

    The recent progress in theoretical and experimental studies of simultaneous spreading and evaporation of liquid droplets on solid substrates is discussed for pure liquids including nanodroplets, nanosuspensions of inorganic particles (nanofluids) and surfactant solutions. Evaporation of both complete wetting and partial wetting liquids into a nonsaturated vapour atmosphere are considered. However, the main attention is paid to the case of partial wetting when the hysteresis of static contact angle takes place. In the case of complete wetting the spreading/evaporation process proceeds in two stages. A theory was suggested for this case and a good agreement with available experimental data was achieved. In the case of partial wetting the spreading/evaporation of a sessile droplet of pure liquid goes through four subsequent stages: (i) the initial stage, spreading, is relatively short (1-2 min) and therefore evaporation can be neglected during this stage; during the initial stage the contact angle reaches the value of advancing contact angle and the radius of the droplet base reaches its maximum value, (ii) the first stage of evaporation is characterised by the constant value of the radius of the droplet base; the value of the contact angle during the first stage decreases from static advancing to static receding contact angle; (iii) during the second stage of evaporation the contact angle remains constant and equal to its receding value, while the radius of the droplet base decreases; and (iv) at the third stage of evaporation both the contact angle and the radius of the droplet base decrease until the drop completely disappears. It has been shown theoretically and confirmed experimentally that during the first and second stages of evaporation the volume of droplet to power 2/3 decreases linearly with time. The universal dependence of the contact angle during the first stage and of the radius of the droplet base during the second stage on the reduced time has been

  2. Dynamic Modeling of CDS Index Tranche Spreads

    DEFF Research Database (Denmark)

    Dorn, Jochen

    This paper provides a Market Model which implies a dynamics for standardized CDS index tranche spreads, i.e. tranches which securitise CDS index series and dispose of predefined subordination. This model is useful for pricing options on tranches with future Issue Dates as well as for modeling...... options on structured credit derivatives. With the upcoming regulation of the CDS market in perspective, the model presented here is also an attempt to face the effects on pricing approaches provoked by an eventual Clearing Chamber . It becomes also possible to calibrate Index Tranche Options with bespoke...... tenors/tranche subordination to market data obtained by more liquid Index Tranche Options with standard characteristics....

  3. Survey report: Eastern Caribbean.

    Science.gov (United States)

    Yinger, N

    1991-01-01

    Over 1 million people live on 8 small islands in the Eastern Caribbean: St. Kitts-Nevis, Montserrat, Grenada, St. Vincent, Antigua, Barbados, St. Lucia, and Dominica. Starting in 1985 the International Planned Parenthood Federation, Western Hemisphere Region has carried out a series of contraceptive prevalence surveys in these countries. Current information is provided by these surveys in the areas of fertility levels and preferences, contraceptive knowledge and use. Also, socioeconomic, historical and demographic background and analysis such as fertility patterns, desire for additional children, and breastfeeding data; contraceptive awareness including family planning methods and sources; contraceptive use by method, source, and timing, satisfaction, and male attitudes are provided in the surveys, but not in the report abstracted here. The total fertility rate (TFR) and the contraceptive prevalence rate (CPR) for the 8 islands are as follows: St. Kitts-Nevis (1984) 2.9 TFR, 40.6 CPR; St. Vincent (1988) 2.9 TFR, 58.3 CPR; Antigua (1988) 1.8 TFR, 52.6 CPR; Barbados (1988) not given, 55.0 CPR; St. Lucia (1988) 3.2 TFR, 47.3 CPR; Dominica (1987) 3.2 TFR, 49.8 CPR. The islands have unusual demographic patterns related to extensive out-migration.

  4. Middle Eastern Christians in Europe

    DEFF Research Database (Denmark)

    Sparre, Sara Cathrine Lei; Hunter, Alistair; Jørgensen, Anne Rosenlund

    This booklet, published in English, Danish, Swedish and Arabic, has the aim to present overall findings of the research project Defining and Identifying Middle Eastern Christians in Europe (DIMECCE) to a broader audience.......This booklet, published in English, Danish, Swedish and Arabic, has the aim to present overall findings of the research project Defining and Identifying Middle Eastern Christians in Europe (DIMECCE) to a broader audience....

  5. Infections Unlikely to be Spread Through Swimming Pools

    Science.gov (United States)

    ... Water Home Infections Unlikely to be Spread Through Swimming Pools Language: English (US) Español (Spanish) Recommend on ... included below. Infections Unlikely to be Spread by Swimming Pools Head Lice Head lice are unlikely to ...

  6. Spreading depolarisations and outcome after traumatic brain injury

    DEFF Research Database (Denmark)

    Hartings, Jed A; Bullock, M Ross; Okonkwo, David O

    2011-01-01

    Pathological waves of spreading mass neuronal depolarisation arise repeatedly in injured, but potentially salvageable, grey matter in 50-60% of patients after traumatic brain injury (TBI). We aimed to ascertain whether spreading depolarisations are independently associated with unfavourable...

  7. Stopping the Spread of Germs at Home, Work and School

    Science.gov (United States)

    ... Pandemic Other Stopping the Spread of Germs at Home, Work & School Language: English (US) Español Recommend on Facebook ... everyone from getting germs or spreading germs at home, work, or school. Clean and disinfect surfaces or objects. ...

  8. Recording, analysis, and interpretation of spreading depolarizations in neurointensive care

    DEFF Research Database (Denmark)

    Dreier, Jens P; Fabricius, Martin; Ayata, Cenk

    2017-01-01

    Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly r...

  9. Preoperative evaluation of locally spreaded pelvic tumors

    International Nuclear Information System (INIS)

    Baramia, M.; Todua, F.; Gotsadze, D.; Khutulashvili, N.; Lashkhi, K.; Nadareishvili, A.

    1998-01-01

    Am of the study: preoperative evaluation of patients with locally advanced pelvic tumors subjected to pelvic exenteration. Determine operability to avoid explorative laparatomies, which cause serious complications in these patients. Evaluate condition of urinary system in case of this pathology. Materials and methods: 34 patients with locally advanced pelvic tumors where pelvic exenteration was attempted were studied. Along with other methods of diagnostic CT and MRI were performed. Results: In all patients secondary involvement of the urinary bladder was noted. In 30 patients CT and MR findings were confirmed (88,2%) intraoperatively and different types of pelvic organs exenteration were performed. In 1 case spread of tomoruos infiltrate to the pelvic wall and common iliac vessels was detected intraoperatively (patient had history of radiation therapy). In 2 cases carcinomatosis of the peritoneum was found. In 1 case involvement of urinary bladder was simulated by close attachment of enlarged uterus. Conclusion: Obtained results show, that CT and MR are highly informative methods of disease spread evaluation and thus determining operability. Radiotherapy performed prior to operation sets difficulties in differentiation for tumourous infiltrate and post-radiotherapy changes in pelvis. (Full text)

  10. A lattice model for influenza spreading.

    Directory of Open Access Journals (Sweden)

    Antonella Liccardo

    Full Text Available We construct a stochastic SIR model for influenza spreading on a D-dimensional lattice, which represents the dynamic contact network of individuals. An age distributed population is placed on the lattice and moves on it. The displacement from a site to a nearest neighbor empty site, allows individuals to change the number and identities of their contacts. The dynamics on the lattice is governed by an attractive interaction between individuals belonging to the same age-class. The parameters, which regulate the pattern dynamics, are fixed fitting the data on the age-dependent daily contact numbers, furnished by the Polymod survey. A simple SIR transmission model with a nearest neighbors interaction and some very basic adaptive mobility restrictions complete the model. The model is validated against the age-distributed Italian epidemiological data for the influenza A(H1N1 during the [Formula: see text] season, with sensible predictions for the epidemiological parameters. For an appropriate topology of the lattice, we find that, whenever the accordance between the contact patterns of the model and the Polymod data is satisfactory, there is a good agreement between the numerical and the experimental epidemiological data. This result shows how rich is the information encoded in the average contact patterns of individuals, with respect to the analysis of the epidemic spreading of an infectious disease.

  11. Principles of spread-spectrum communication systems

    CERN Document Server

    Torrieri, Don

    2015-01-01

    This book provides a concise but lucid explanation of the fundamentals of spread-spectrum systems with an emphasis on theoretical principles. The choice of specific topics is tempered by the author’s judgment of their practical significance and interest to both researchers and system designers. The book contains many improved derivations of the classical theory and presents the latest research results that bring the reader to the frontier of the field. This third edition includes new coverage of topics such as CDMA networks, acquisition and synchronization in DS-CDMA cellular networks, hopsets for FH-CDMA ad hoc networks, implications of information theory, the central limit theorem, the power spectral density of FH/CPM complex envelopes, adaptive filters, and adaptive arrays.   ·         Focuses on the fundamentals of spread-spectrum communication systems and provides current examples of their applications ·         Includes problem sets at the end of each chapter to assist readers in co...

  12. Wave-like spread of Ebola Zaire.

    Directory of Open Access Journals (Sweden)

    2005-11-01

    Full Text Available In the past decade the Zaire strain of Ebola virus (ZEBOV has emerged repeatedly into human populations in central Africa and caused massive die-offs of gorillas and chimpanzees. We tested the view that emergence events are independent and caused by ZEBOV variants that have been long resident at each locality. Phylogenetic analyses place the earliest known outbreak at Yambuku, Democratic Republic of Congo, very near to the root of the ZEBOV tree, suggesting that viruses causing all other known outbreaks evolved from a Yambuku-like virus after 1976. The tendency for earlier outbreaks to be directly ancestral to later outbreaks suggests that outbreaks are epidemiologically linked and may have occurred at the front of an advancing wave. While the ladder-like phylogenetic structure could also bear the signature of positive selection, our statistical power is too weak to reach a conclusion in this regard. Distances among outbreaks indicate a spread rate of about 50 km per year that remains consistent across spatial scales. Viral evolution is clocklike, and sequences show a high level of small-scale spatial structure. Genetic similarity decays with distance at roughly the same rate at all spatial scales. Our analyses suggest that ZEBOV has recently spread across the region rather than being long persistent at each outbreak locality. Controlling the impact of Ebola on wild apes and human populations may be more feasible than previously recognized.

  13. Epidemics spreading in interconnected complex networks

    International Nuclear Information System (INIS)

    Wang, Y.; Xiao, G.

    2012-01-01

    We study epidemic spreading in two interconnected complex networks. It is found that in our model the epidemic threshold of the interconnected network is always lower than that in any of the two component networks. Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. Theoretical analysis and simulation results show that, generally speaking, the epidemic size is not significantly affected by the inter-network correlation. In interdependent networks which can be viewed as a special case of interconnected networks, however, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant. -- Highlights: ► We study epidemic spreading in two interconnected complex networks. ► The epidemic threshold is lower than that in any of the two networks. And Interconnection correlation has impacts on threshold and average outbreak size. ► Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. ► We demonstrated and proved that Interconnection correlation does not affect epidemic size significantly. ► In interdependent networks, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant.

  14. Epidemic spreading on preferred degree adaptive networks.

    Science.gov (United States)

    Jolad, Shivakumar; Liu, Wenjia; Schmittmann, B; Zia, R K P

    2012-01-01

    We study the standard SIS model of epidemic spreading on networks where individuals have a fluctuating number of connections around a preferred degree κ. Using very simple rules for forming such preferred degree networks, we find some unusual statistical properties not found in familiar Erdös-Rényi or scale free networks. By letting κ depend on the fraction of infected individuals, we model the behavioral changes in response to how the extent of the epidemic is perceived. In our models, the behavioral adaptations can be either 'blind' or 'selective'--depending on whether a node adapts by cutting or adding links to randomly chosen partners or selectively, based on the state of the partner. For a frozen preferred network, we find that the infection threshold follows the heterogeneous mean field result λ(c)/μ = / and the phase diagram matches the predictions of the annealed adjacency matrix (AAM) approach. With 'blind' adaptations, although the epidemic threshold remains unchanged, the infection level is substantially affected, depending on the details of the adaptation. The 'selective' adaptive SIS models are most interesting. Both the threshold and the level of infection changes, controlled not only by how the adaptations are implemented but also how often the nodes cut/add links (compared to the time scales of the epidemic spreading). A simple mean field theory is presented for the selective adaptations which capture the qualitative and some of the quantitative features of the infection phase diagram.

  15. Epidemics spreading in interconnected complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Institute of High Performance Computing, Agency for Science, Technology and Research (A-STAR), Singapore 138632 (Singapore); Xiao, G., E-mail: egxxiao@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2012-09-03

    We study epidemic spreading in two interconnected complex networks. It is found that in our model the epidemic threshold of the interconnected network is always lower than that in any of the two component networks. Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. Theoretical analysis and simulation results show that, generally speaking, the epidemic size is not significantly affected by the inter-network correlation. In interdependent networks which can be viewed as a special case of interconnected networks, however, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant. -- Highlights: ► We study epidemic spreading in two interconnected complex networks. ► The epidemic threshold is lower than that in any of the two networks. And Interconnection correlation has impacts on threshold and average outbreak size. ► Detailed theoretical analysis is proposed which allows quick and accurate calculations of epidemic threshold and average outbreak/epidemic size. ► We demonstrated and proved that Interconnection correlation does not affect epidemic size significantly. ► In interdependent networks, impacts of inter-network correlation on the epidemic threshold and outbreak size are more significant.

  16. Modelling dengue epidemic spreading with human mobility

    Science.gov (United States)

    Barmak, D. H.; Dorso, C. O.; Otero, M.

    2016-04-01

    We explored the effect of human mobility on the spatio-temporal dynamics of Dengue with a stochastic model that takes into account the epidemiological dynamics of the infected mosquitoes and humans, with different mobility patterns of the human population. We observed that human mobility strongly affects the spread of infection by increasing the final size and by changing the morphology of the epidemic outbreaks. When the spreading of the disease is driven only by mosquito dispersal (flight), a main central focus expands diffusively. On the contrary, when human mobility is taken into account, multiple foci appear throughout the evolution of the outbreaks. These secondary foci generated throughout the outbreaks could be of little importance according to their mass or size compared with the largest main focus. However, the coalescence of these foci with the main one generates an effect, through which the latter develops a size greater than the one obtained in the case driven only by mosquito dispersal. This increase in growth rate due to human mobility and the coalescence of the foci are particularly relevant in temperate cities such as the city of Buenos Aires, since they give more possibilities to the outbreak to grow before the arrival of the low-temperature season. The findings of this work indicate that human mobility could be the main driving force in the dynamics of vector epidemics.

  17. A fundamental look at fire spread in California chaparral

    Science.gov (United States)

    David R. Weise; Thomas Fletcher; Larry Baxter; Shankar Mahalingam; Xiangyang Zhou; Patrick Pagni; Rod Linn; Bret Butler

    2004-01-01

    The USDA Forest Service National Fire Plan funded a research program to study fire spread in live fuels of the southwestern United States. In the U.S. current operational fire spread models do not distinguish between live and dead fuels in a sophisticated manner because the study of live fuels has been limited. The program is experimentally examining fire spread at 3...

  18. The joint estimation of term structures and credit spreads

    NARCIS (Netherlands)

    Houweling, P.; Hoek, J.; Kleibergen, F.R.

    1999-01-01

    We present a new framework for the joint estimation of the default-free government term structure and corporate credit spread curves. By using a data set of liquid, German mark denominated bonds, we show that this yields more realistic spreads than traditionally obtained spread curves that result

  19. Forecasting oil price movements with crack spread futures

    International Nuclear Information System (INIS)

    Murat, Atilim; Tokat, Ekin

    2009-01-01

    In oil markets, the crack spread refers to the crude-product price relationship. Refiners are major participants in oil markets and they are primarily exposed to the crack spread. In other words, refiner activity is substantially driven by the objective of protecting the crack spread. Moreover, oil consumers are active participants in the oil hedging market and they are frequently exposed to the crack spread. From another perspective, hedge funds are heavily using crack spread to speculate in oil markets. Based on the high volume of crack spread futures trading in oil markets, the question we want to raise is whether the crack spread futures can be a good predictor of oil price movements. We investigated first whether there is a causal relationship between the crack spread futures and the spot oil markets in a vector error correction framework. We found the causal impact of crack spread futures on spot oil market both in the long- and the short-run after April 2003 where we detected a structural break in the model. To examine the forecasting performance, we use the random walk model (RWM) as a benchmark, and we also evaluate the forecasting power of crack spread futures against the crude oil futures. The results showed that (a) both the crack spread futures and the crude oil futures outperformed the RWM; and (b) the crack spread futures are almost as good as the crude oil futures in predicting the movements in spot oil markets. (author)

  20. Hydroclimatological And Anthropogenic Drivers For Cholera Spreading

    Science.gov (United States)

    Righetto, Lorenzo; Bertuzzo, Enrico; Mari, Lorenzo; Casagrandi, Renato; Gatto, Marino; Rinaldo, Andrea

    2010-05-01

    The nature of waterborne diseases, among which cholera has a prominent importance, calls for a better understanding of the link between epidemic spreading, water and climate. To this end, we have developed a framework which involves a network-based description of a river system, connected with local communities which act as nodes of the network. This has allowed us to produce consistent simulations of real case studies. More recent investigations comprise the evaluation of the spreading velocity of an epidemic wave by means of a reaction-diffusion modeling approach. In particular, we have found that both transport processes and epidemiological quantities, such as the basic reproduction number, have a crucial effect in controlling the spreading of the epidemics. We first developed a description of bacterial movement along the network driven by advection and diffusion; afterward, we have included the movement of human populations. This latter model allowed us to establish the conditions that can trigger epidemic waves that start from the coastal region, where bacteria are autochthonous, and travel inland. In particular, our findings suggest that even relatively low values of human diffusion can have the epidemic propagate upstream. The interaction between climate, hydrology and epidemic events is still much debated, since no clear correlation between climatologic and epidemiological phenomena has emerged so far. However, a spatial assessment of hydrological and epidemiological mechanisms could be crucial to understand the evolution of cholera outbreaks. In particular, a hotly debated topic is the understanding of the mechanisms that can generate patterns of cholera incidence that exhibit an intra-annual double peak, as frequently observed in endemic region such as Bangladesh. One of the possible explanations proposed in the literature is that spring droughts cause bacteria concentration in water to rise dramatically, triggering the first peak. On the other hand

  1. Operator Spreading in Random Unitary Circuits

    Science.gov (United States)

    Nahum, Adam; Vijay, Sagar; Haah, Jeongwan

    2018-04-01

    Random quantum circuits yield minimally structured models for chaotic quantum dynamics, which are able to capture, for example, universal properties of entanglement growth. We provide exact results and coarse-grained models for the spreading of operators by quantum circuits made of Haar-random unitaries. We study both 1 +1 D and higher dimensions and argue that the coarse-grained pictures carry over to operator spreading in generic many-body systems. In 1 +1 D , we demonstrate that the out-of-time-order correlator (OTOC) satisfies a biased diffusion equation, which gives exact results for the spatial profile of the OTOC and determines the butterfly speed vB. We find that in 1 +1 D , the "front" of the OTOC broadens diffusively, with a width scaling in time as t1 /2. We address fluctuations in the OTOC between different realizations of the random circuit, arguing that they are negligible in comparison to the broadening of the front within a realization. Turning to higher dimensions, we show that the averaged OTOC can be understood exactly via a remarkable correspondence with a purely classical droplet growth problem. This implies that the width of the front of the averaged OTOC scales as t1 /3 in 2 +1 D and as t0.240 in 3 +1 D (exponents of the Kardar-Parisi-Zhang universality class). We support our analytic argument with simulations in 2 +1 D . We point out that, in two or higher spatial dimensions, the shape of the spreading operator at late times is affected by underlying lattice symmetries and, in general, is not spherical. However, when full spatial rotational symmetry is present in 2 +1 D , our mapping implies an exact asymptotic form for the OTOC, in terms of the Tracy-Widom distribution. For an alternative perspective on the OTOC in 1 +1 D , we map it to the partition function of an Ising-like statistical mechanics model. As a result of special structure arising from unitarity, this partition function reduces to a random walk calculation which can be

  2. Resource Allocation with Adaptive Spread Spectrum OFDM Using 2D Spreading for Power Line Communications

    Directory of Open Access Journals (Sweden)

    Baudais Jean-Yves

    2007-01-01

    Full Text Available Bit-loading techniques based on orthogonal frequency division mutiplexing (OFDM are frequently used over wireline channels. In the power line context, channel state information can reasonably be obtained at both transmitter and receiver sides, and adaptive loading can advantageously be carried out. In this paper, we propose to apply loading principles to an spread spectrum OFDM (SS-OFDM waveform which is a multicarrier system using 2D spreading in the time and frequency domains. The presented algorithm handles the subcarriers, spreading codes, bits and energies assignment in order to maximize the data rate and the range of the communication system. The optimization is realized at a target symbol error rate and under spectral mask constraint as usually imposed. The analytical study shows that the merging principle realized by the spreading code improves the rate and the range of the discrete multitone (DMT system in single and multiuser contexts. Simulations have been run over measured power line communication (PLC channel responses and highlight that the proposed system is all the more interesting than the received signal-to-noise ratio (SNR is low.

  3. Resource Allocation with Adaptive Spread Spectrum OFDM Using 2D Spreading for Power Line Communications

    Science.gov (United States)

    Baudais, Jean-Yves; Crussière, Matthieu

    2007-12-01

    Bit-loading techniques based on orthogonal frequency division mutiplexing (OFDM) are frequently used over wireline channels. In the power line context, channel state information can reasonably be obtained at both transmitter and receiver sides, and adaptive loading can advantageously be carried out. In this paper, we propose to apply loading principles to an spread spectrum OFDM (SS-OFDM) waveform which is a multicarrier system using 2D spreading in the time and frequency domains. The presented algorithm handles the subcarriers, spreading codes, bits and energies assignment in order to maximize the data rate and the range of the communication system. The optimization is realized at a target symbol error rate and under spectral mask constraint as usually imposed. The analytical study shows that the merging principle realized by the spreading code improves the rate and the range of the discrete multitone (DMT) system in single and multiuser contexts. Simulations have been run over measured power line communication (PLC) channel responses and highlight that the proposed system is all the more interesting than the received signal-to-noise ratio (SNR) is low.

  4. Dielectric fluid directional spreading under the action of corona discharge

    Science.gov (United States)

    Zhou, Shangru; Liu, Jie; Hu, Qun; Jiang, Teng; Yang, Jinchu; Liu, Sheng; Zheng, Huai

    2018-01-01

    Liquid spreading is a very common nature phenomenon and of significant importance for a broad range of applications. In this study, a dielectric fluid directional spreading phenomenon is presented. Under the action of corona discharge, a dielectric fluid, here a typical silicone directionally spreads along conductive patterns on conductive/nonconductive substrates. Directional spreading behaviors of silicone were experimentally observed on different conductive patterns in detail. Spreading speeds were analyzed at different driving voltages, which induced the corona discharge. The presented phenomenon may be useful to inspire several techniques of manipulating liquid transportation and fabricating micropatterns.

  5. Modeling Epidemics Spreading on Social Contact Networks.

    Science.gov (United States)

    Zhang, Zhaoyang; Wang, Honggang; Wang, Chonggang; Fang, Hua

    2015-09-01

    Social contact networks and the way people interact with each other are the key factors that impact on epidemics spreading. However, it is challenging to model the behavior of epidemics based on social contact networks due to their high dynamics. Traditional models such as susceptible-infected-recovered (SIR) model ignore the crowding or protection effect and thus has some unrealistic assumption. In this paper, we consider the crowding or protection effect and develop a novel model called improved SIR model. Then, we use both deterministic and stochastic models to characterize the dynamics of epidemics on social contact networks. The results from both simulations and real data set conclude that the epidemics are more likely to outbreak on social contact networks with higher average degree. We also present some potential immunization strategies, such as random set immunization, dominating set immunization, and high degree set immunization to further prove the conclusion.

  6. Spread of epidemic disease on networks

    Science.gov (United States)

    Newman, M. E.

    2002-07-01

    The study of social networks, and in particular the spread of disease on networks, has attracted considerable recent attention in the physics community. In this paper, we show that a large class of standard epidemiological models, the so-called susceptible/infective/removed (SIR) models can be solved exactly on a wide variety of networks. In addition to the standard but unrealistic case of fixed infectiveness time and fixed and uncorrelated probability of transmission between all pairs of individuals, we solve cases in which times and probabilities are nonuniform and correlated. We also consider one simple case of an epidemic in a structured population, that of a sexually transmitted disease in a population divided into men and women. We confirm the correctness of our exact solutions with numerical simulations of SIR epidemics on networks.

  7. Quarantine generated phase transition in epidemic spreading

    Science.gov (United States)

    Dicksion, Mark; Lagorio, Cecilia; Vazquez, F.; Braunstein, L.; Macri, P. A.; Migueles, M. V.; Havlin, S.; Stanley, H. E.

    2011-03-01

    We study the critical effect of quarantine on the propagation of epidemics on an adaptive network of social contacts. For this purpose, we analyze the susceptible-infected-recovered (SIR) model in the presence of quarantine, where susceptible individuals protect themselves by disconnecting their links to infected neighbors with probability w, and reconnecting them to other susceptible individuals chosen at random. Starting from a single infected individual, we show by an analytical approach and simulations that there is a phase transition at a critical rewiring (quarantine) threshold wc separating a phase (w =wc) where the disease does not spread out. We find that in our model the topology of the network strongly affects the size of the propagation, and that wc increases with the mean degree and heterogeneity of the network. We also find that wc is reduced if we perform a preferential rewiring, in which the rewiring probability is proportional to the degree of infected nodes.

  8. Abnormal cascading failure spreading on complex networks

    International Nuclear Information System (INIS)

    Wang, Jianwei; Sun, Enhui; Xu, Bo; Li, Peng; Ni, Chengzhang

    2016-01-01

    Applying the mechanism of the preferential selection of the flow destination, we develop a new method to quantify the initial load on an edge, of which the flow is transported along the path with the shortest edge weight between two nodes. Considering the node weight, we propose a cascading model on the edge and investigate cascading dynamics induced by the removal of the edge with the largest load. We perform simulated attacks on four types of constructed networks and two actual networks and observe an interesting and counterintuitive phenomenon of the cascading spreading, i.e., gradually improving the capacity of nodes does not lead to the monotonous increase in the robustness of these networks against cascading failures. The non monotonous behavior of cascading dynamics is well explained by the analysis on a simple graph. We additionally study the effect of the parameter of the node weight on cascading dynamics and evaluate the network robustness by a new metric.

  9. Intensity-dependent point spread image processing

    International Nuclear Information System (INIS)

    Cornsweet, T.N.; Yellott, J.I.

    1984-01-01

    There is ample anatomical, physiological and psychophysical evidence that the mammilian retina contains networks that mediate interactions among neighboring receptors, resulting in intersecting transformations between input images and their corresponding neural output patterns. The almost universally accepted view is that the principal form of interaction involves lateral inhibition, resulting in an output pattern that is the convolution of the input with a ''Mexican hat'' or difference-of-Gaussians spread function, having a positive center and a negative surround. A closely related process is widely applied in digital image processing, and in photography as ''unsharp masking''. The authors show that a simple and fundamentally different process, involving no inhibitory or subtractive terms can also account for the physiological and psychophysical findings that have been attributed to lateral inhibition. This process also results in a number of fundamental effects that occur in mammalian vision and that would be of considerable significance in robotic vision, but which cannot be explained by lateral inhibitory interaction

  10. Spread of acid rain over India

    Science.gov (United States)

    Khemani, L. T.; Momin, G. A.; Rao, P. S. Prakasa; Safai, P. D.; Singh, G.; Kapoor, R. K.

    Rain water and aerosol samples were collected at a few locations representative of urban and non-urban regions in India. Also, rain water samples were collected in and around a coal-fired power plant. All the rain water and aerosol samples were analyzed for major chemical components along with pH. The rain water at all the places of measurement, except near the industrial sources, has been found to be alkaline and was characterized by the presence of excess cations, particularly by Ca 2+. The acid rain near the industrial sources was associated with excess anions, especially SO 42-. The atmospheric aerosols at all the places of measurement were found rich with basic components, suggesting that the alkaline soil dust and fly ash are responsible at present for preventing the spread of acid rain in India.

  11. Emergence and spreading potential of Zika virus

    Directory of Open Access Journals (Sweden)

    Alvaro Fajardo

    2016-10-01

    Full Text Available Zika virus (ZIKV is an arthropod-borne Flavivirus (family Flaviviridae closely related to dengue, yellow fever and West Nile viruses. ZIKV remained neglected, confined to enzootic transmission cycles in Africa and Asia, until the first significant outbreak was reported in Micronesia in 2007. Subsequent epidemics of growing incidence occurred in French Polynesia and other South Pacific Islands, and recently, in the Americas. The latter and currently ongoing outbreak of unprecedented incidence revealed the association of ZIKV infection with the occurrence of severe congenital malformations and neurological diseases, leading to a widespread concern about its potential to pose a global public health threat. Serological and molecular data suggest that the genetic and geographic diversification of ZIKV may be greatly underestimated. Here we discuss several ecological and epidemiological aspects, together with the evolutionary processes that may have driven the emergence and abrupt spread of ZIKV in the Americas.

  12. Avian Influenza spread and transmission dynamics

    Science.gov (United States)

    Bourouiba, Lydia; Gourley, Stephen A.; Liu, Rongsong; Takekawa, John Y.; Wu, Jianhong; Chen, Dongmei; Moulin, Bernard; Wu, Jianhong

    2015-01-01

    The spread of highly pathogenic avian influenza (HPAI) viruses of type A of subtype H5N1 has been a serious threat to global public health. Understanding the roles of various (migratory, wild, poultry) bird species in the transmission of these viruses is critical for designing and implementing effective control and intervention measures. Developing appropriate models and mathematical techniques to understand these roles and to evaluate the effectiveness of mitigation strategies have been a challenge. Recent development of the global health surveillance (especially satellite tracking and GIS techniques) and the mathematical theory of dynamical systems combined have gradually shown the promise of some cutting-edge methodologies and techniques in mathematical biology to meet this challenge.

  13. Understanding the Spatio-Temporal Pattern of Fire Disturbance in the Eastern Mongolia Using Modis Product

    Science.gov (United States)

    Wurihan; Zhang, H.; Zhang, Z.; Guo, X.; Zhao, J.; Duwala; Shan, Y.; Hongying

    2018-04-01

    Fire disturbance plays an important role in maintaining ecological balance, biodiversity and self-renewal. In this paper, the spatio-temporal pattern of fire disturbances in eastern Mongolia are studied by using the ArcGIS spatial analysis method, using the MCD45A1 data of MODIS fire products with long time series. It provides scientific basis and reference for the regional ecological environment security construction and international ecological security. Research indicates: (1) The fire disturbance in eastern Mongolia has obvious high and low peak interleaving phenomenon in the year, and the seasonal change is obvious. (2) The distribution pattern of fire disturbance in eastern Mongolia is aggregated, which indicates that the fire disturbance is not random and it is caused by certain influence. (3) Fire disturbance is mainly distributed in the eastern province of Mongolia, the border between China and Mongolia and the northern forest area of Sukhbaatar province. (4) The fire disturbance in the eastern part of the study area is strong and the southwest is weaker. The spreading regularity of fire disturbances in eastern Mongolia is closer to the natural level of ecosystem.

  14. UNDERSTANDING THE SPATIO-TEMPORAL PATTERN OF FIRE DISTURBANCE IN THE EASTERN MONGOLIA USING MODIS PRODUCT

    Directory of Open Access Journals (Sweden)

    Wurihan

    2018-04-01

    Full Text Available Fire disturbance plays an important role in maintaining ecological balance, biodiversity and self-renewal. In this paper, the spatio-temporal pattern of fire disturbances in eastern Mongolia are studied by using the ArcGIS spatial analysis method, using the MCD45A1 data of MODIS fire products with long time series. It provides scientific basis and reference for the regional ecological environment security construction and international ecological security. Research indicates: (1 The fire disturbance in eastern Mongolia has obvious high and low peak interleaving phenomenon in the year, and the seasonal change is obvious. (2 The distribution pattern of fire disturbance in eastern Mongolia is aggregated, which indicates that the fire disturbance is not random and it is caused by certain influence. (3 Fire disturbance is mainly distributed in the eastern province of Mongolia, the border between China and Mongolia and the northern forest area of Sukhbaatar province. (4 The fire disturbance in the eastern part of the study area is strong and the southwest is weaker. The spreading regularity of fire disturbances in eastern Mongolia is closer to the natural level of ecosystem.

  15. Quantifier spreading: children misled by ostensive cues

    Directory of Open Access Journals (Sweden)

    Katalin É. Kiss

    2017-04-01

    Full Text Available This paper calls attention to a methodological problem of acquisition experiments. It shows that the economy of the stimulus employed in child language experiments may lend an increased ostensive effect to the message communicated to the child. Thus, when the visual stimulus in a sentence-picture matching task is a minimal model abstracting away from the details of the situation, children often regard all the elements of the stimulus as ostensive clues to be represented in the corresponding sentence. The use of such minimal stimuli is mistaken when the experiment aims to test whether or not a certain element of the stimulus is relevant for the linguistic representation or interpretation. The paper illustrates this point by an experiment involving quantifier spreading. It is claimed that children find a universally quantified sentence like 'Every girl is riding a bicycle 'to be a false description of a picture showing three girls riding bicycles and a solo bicycle because they are misled to believe that all the elements in the visual stimulus are relevant, hence all of them are to be represented by the corresponding linguistic description. When the iconic drawings were replaced by photos taken in a natural environment rich in accidental details, the occurrence of quantifier spreading was radically reduced. It is shown that an extra object in the visual stimulus can lead to the rejection of the sentence also in the case of sentences involving no quantification, which gives further support to the claim that the source of the problem is not (or not only the grammatical or cognitive difficulty of quantification but the unintended ostensive effect of the extra object.  This article is part of the special collection: Acquisition of Quantification

  16. Area Studies and Eastern Europe: How Eastern Europe Collapsed

    Directory of Open Access Journals (Sweden)

    Mirjana Kasapović

    2007-01-01

    Full Text Available In the first part, the author outlines the development of area studies in contemporary comparative politics, and points to their importance for the development of political science. In the second part, she examines the methodology – research design and methods – of regional comparatistics, paying particular attention to the problem of defining the region as a central category in this field of comparative politics. The third and central part is focused on the emergence of Eastern Europe as a historical-political and socio-cultural region in the course of history, especially after World War II, and on its dissolution in the processes of democratic transformation of communist regimes in the last two decades. The dissolution of Eastern Europe has resulted in restoration of a tripartite political geography in the area which it used to take up, made up of Central Europe, Southeast Europe and the proper Eastern Europe.

  17. Topology dependent epidemic spreading velocity in weighted networks

    International Nuclear Information System (INIS)

    Duan, Wei; Qiu, Xiaogang; Quax, Rick; Lees, Michael; Sloot, Peter M A

    2014-01-01

    Many diffusive processes occur on structured networks with weighted links, such as disease spread by airplane transport or information diffusion in social networks or blogs. Understanding the impact of weight-connectivity correlations on epidemic spreading in weighted networks is crucial to support decision-making on disease control and other diffusive processes. However, a real understanding of epidemic spreading velocity in weighted networks is still lacking. Here we conduct a numerical study of the velocity of a Reed–Frost epidemic spreading process in various weighted network topologies as a function of the correlations between edge weights and node degrees. We find that a positive weight-connectivity correlation leads to a faster epidemic spreading compared to an unweighted network. In contrast, we find that both uncorrelated and negatively correlated weight distributions lead to slower spreading processes. In the case of positive weight-connectivity correlations, the acceleration of spreading velocity is weak when the heterogeneity of weight distribution increases. (paper)

  18. Non-isothermal spreading of liquid drops on horizontal plates

    International Nuclear Information System (INIS)

    Ehrhard, P.; Davis, S.H.

    1990-05-01

    A viscous-liquid drop spreads on a smooth horizontal surface, which is uniformly heated or cooled. Lubrication theory is used to study thin drops subject to capillary, thermocapillary and gravity forces, and a variety of contact-angle-versus-speed conditions. It is found for isothermal drops that gravity is very important at large times and determines the power law for unlimited spreading. Predictions compare well with the experimental data on isothermal spreading for both two-dimensional and axisymmetric configurations. It is found that heating (cooling) retards (augments) the spreading process. When the advancing contact angle is zero, heating will cause the drop to spread only finitely far. For positive advancing contact angles, sufficient cooling will cause unlimited spreading. Thus, the heat transfer serves as a sentitive control on the spreading. (orig.) [de

  19. FACTORS INFLUENCING YIELD SPREADS OF THE MALAYSIAN BONDS

    Directory of Open Access Journals (Sweden)

    Norliza Ahmad

    2009-01-01

    Full Text Available Malaysian bond market is developing rapidly but not much is understood in terms of macroeconomic factors that could influence the yield spread of the Ringgit Malaysian denominated bonds. Based on a multifactor model, this paper examines the impact of four macroeconomic factors namely: Kuala Lumpur Composite Index (KLCI, Industry Production Index (IPI, Consumer Price Index (CPI and interest rates (IR on bond yield spread of the Malaysian Government Securities (MGS and Corporate Bonds (CBs for a period from January 2001 to December 2008. The findings support the expected hypotheses that CPI and IR are the major drivers that influence the changes in MGS yield spreads. However IPI and KLCI have weak and no influence on MGS yield spreads respectively Whilst IR, CPI and IPI have significant influence on the yield spreads of CB1, CB2 and CB3, KLCI has significant influence only on the CB1 yield spread but not on CB2 and CB3 yield spreads.

  20. Environmental protection in Eastern Europe

    International Nuclear Information System (INIS)

    Kabala, S.

    1990-01-01

    There is a need for the development of institutional structures to make the transfer of technology work to improve the ability of Eastern Europe to find solutions to its environmental problems. Envisioned is technical assistance: U.S. experts who will work on-site with Eastern European experts. The idea is to technically train individuals in pollution-prevention methods. Trained experts could then upgrade processes to save input, energy, and materials. In the exchange of environmental information, discussions have led to four issues: it is expensive to transfer equipment and make qualified personnel available for a long period; information is comparatively inexpensive to convey; in Eastern Europe there are trained and competent personnel; the theoretical knowledge, academic knowledge, and education are at a very high level but little of this knowledge has been put into practice. The technology transfer goal is to develop a response to needs identified by partner institutions and counterpart professionals that will enable Eastern Europe to tap resources that do exist- scientific, managerial, and economic resources and tap information resources in the US in order to address the environmental problems that exist in Eastern Europe

  1. Nuclear power in Eastern Europe

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, S. (Sussex Univ., Brighton (UK). Science Policy Research Unit)

    1991-01-01

    The main aim of this article is that of illustrating the experience of the use of nuclear power in Eastern Europe in order to estimate the degree of adequacy or inadequacy of COMECON's nuclear technology. The author examines four areas of interest concerning: the feasibility of new orders for nuclear plants in Eastern Europe; the pros and cons of completing half-built nuclear power plants; current policy towards existing nuclear power plants; and a review of the available evidence on the operating performance of plants in Eastern Europe. The common belief that the nuclear power experience had by old COMECON countries is uniformly bad does not seem to be fully supported by the limited evidence available. In the author's opinion, the prospects for a successful nuclear power industry in these countries depends on a series on interdependent factors among which, human skills hold a prominent position.

  2. Strategy Formation in Eastern Jutland

    DEFF Research Database (Denmark)

    Olesen, Kristian

    2008-01-01

      In Eastern Jutland a strategy formation process has been initiated with the aim of developing a strategic spatial plan for the city region.  An organisation has been set up to deal with the first phase of the process, which is to carry out three functional analyses and prepare a common vision...... in the area.   The municipalities acknowledge the articulation of the city region and the initiated planning process.  However, the municipalities might see the arena as means to lobby for infrastructure investments in Eastern Jutland, as it is doubtful whether the municipalities will feel encouraged to enter...... a process, which is aiming at increasing the national regulation within their territory.    The result might very well be that the discussion about future infrastructure investments is not linked to discussions about future urban development in Eastern Jutland.  These aspects raises serious questions about...

  3. Eastern Orthodox perspectives on violence

    DEFF Research Database (Denmark)

    Hilton Saggau, Emil

    2017-01-01

    Abstract: In the post-communist era, the contemporary national Eastern Orthodox churches have often been accused of taking either direct or ideological part in violence across Eastern Europe. In several scholarly analyses, the churches have been linked with ethnic and national violence. They have...... thus been identified as an ideological root for a distinctive ethno-religious nationalism either blocking the way for a pluralistic society or simply defying it. These cases of violence and conflicts, as well as their subsequent analysis, only point to a practical and visible manifestation of conflicts......, and they therefore don’t answer a broader theological question, namely the question of the general position of the Eastern Orthodox churches regarding violence. This article will address this broader question of what the Orthodox churches’ position is on violence and discuss the co-relation and intersection between...

  4. Regional Development of Eastern Slovakia

    Directory of Open Access Journals (Sweden)

    Monika Hergezelová

    2017-08-01

    Full Text Available Purpose and Originality: The aim of the work is to provide an overview of regional development in Eastern Slovakia, where are Košice and Prešov Region. The originality of the work lies in the work of enriching the SWOT analysis from the author Eve Rajčáková, which is given in the book deals with the issue of Regional development and regional policy of the European Union and Slovakia. Research question: The conditions of life of people in eastern Slovakia. Method: For writing this contribution will be used method of analysis and statistics. Knowledge on this subject have been looking on the internet and in books and sources of information publicly available. Using the data collected, we dealt with the issue of regional development in the Košice and Prešov regions. Results: The topic was the beginning focused on the overall characteristics of eastern Slovakia. Furthermore, we are at work we dealt with social and economic phenomena in both regions of eastern Slovakia. We focused on GDP, unemployment and tourism, which is in the region is widespread. Society: It is well known that there are obviously different living conditions in eastern Slovakia as in other parts of Slovakia. People are forced to, mainly because of employment, leave their region to move or commute to work to the west. The paper point out the right of this negative phenomenon that is quite visible - high unemployment. Limitations: The limits of work are limited by problems of regional development in eastern Slovakia, mainly focusing on economic and social phenomena in the society.

  5. Risk spreading, connectivity, and optimal reserve spacing.

    Science.gov (United States)

    Blowes, Shane A; Connolly, Sean R

    2012-01-01

    Two important processes determining the dynamics of spatially structured populations are dispersal and the spatial covariance of demographic fluctuations. Spatially explicit approaches to conservation, such as reserve networks, must consider the tension between these two processes and reach a balance between distances near enough to maintain connectivity, but far enough to benefit from risk spreading. Here, we model this trade-off. We show how two measures of metapopulation persistence depend on the shape of the dispersal kernel and the shape of the distance decay in demographic covariance, and we consider the implications of this trade-off for reserve spacing. The relative rates of distance decay in dispersal and demographic covariance determine whether the long-run metapopulation growth rate, and quasi-extinction risk, peak for adjacent patches or intermediately spaced patches; two local maxima in metapopulation persistence are also possible. When dispersal itself fluctuates over time, the trade-off changes. Temporal variation in mean distance that propagules are dispersed (i.e., propagule advection) decreases metapopulation persistence and decreases the likelihood that persistence will peak for adjacent patches. Conversely, variation in diffusion (the extent of random spread around mean dispersal) increases metapopulation persistence overall and causes it to peak at shorter inter-patch distances. Thus, failure to consider temporal variation in dispersal processes increases the risk that reserve spacings will fail to meet the objective of ensuring metapopulation persistence. This study identifies two phenomena that receive relatively little attention in empirical work on reserve spacing, but that can qualitatively change the effectiveness of reserve spacing strategies: (1) the functional form of the distance decay in covariance among patch-specific demographic rates and (2) temporal variation in the shape of the dispersal kernel. The sensitivity of metapopulation

  6. PLUMEX II: A second set of coincident radar and rocket observations of equatorial spread-F

    International Nuclear Information System (INIS)

    Szuszczewicz, E.P.; Tsunoda, R.T.; Narcisi, R.; Holmes, J.C.

    1981-01-01

    PLUMEX II, the second rocket in a two-rocket operation that successfully executed coincident rocket and radar measurements of backscatter plumes and plasma depletions, was launched into the mid-phase of well-developed equatorial spread-F. In contrast with the first operation, the PLUMEX II results show large scale F-region irregularities only on the bottomside gradient with smaller scale irregularities (i.e., small scale structure imbedded in larger scale features) less intense than corresponding observations in PLUMEX I. The latter result could support current interpretations of east-west plume asymmetry which suggests that during initial upwelling the western wall of a plume (the PLUMEX I case) is more unstable than its eastern counterpart (the PLUMEX II case). In addition, ion mass spectrometer results are found to provide further support for an ion transport model which ''captures'' bottomside ions in an upwelling bubble and transports them to high altitudes

  7. International risk of yellow fever spread from the ongoing outbreak in Brazil, December 2016 to May 2017.

    Science.gov (United States)

    Dorigatti, Ilaria; Hamlet, Arran; Aguas, Ricardo; Cattarino, Lorenzo; Cori, Anne; Donnelly, Christl A; Garske, Tini; Imai, Natsuko; Ferguson, Neil M

    2017-07-13

    States in south-eastern Brazil were recently affected by the largest Yellow Fever (YF) outbreak seen in a decade in Latin America. Here we provide a quantitative assessment of the risk of travel-related international spread of YF indicating that the United States, Argentina, Uruguay, Spain, Italy and Germany may have received at least one travel-related YF case capable of seeding local transmission. Mitigating the risk of imported YF cases seeding local transmission requires heightened surveillance globally. This article is copyright of The Authors, 2017.

  8. Spreading Optics in the primary school

    International Nuclear Information System (INIS)

    Gargallo, Ana; Gómez-Varela, Ana I; Gónzalez-Nuñez, Héctor; Delgado, Tamara; Almaguer, Citlalli; Cambronero, Ferran; García-Sánchez, Ángel; Pallarés, David; Aymerich, María; Aragón, Ángel L; Flores-Arias, Maria T

    2015-01-01

    The USC-OSA is a student chapter located at the University of Santiago de Compostela (Spain) whose objective is to bring optics and photonics knowledge closer to general public. In order to arouse kids' interest in Optics we developed an activity called Funny Light. This activity consisted on a visit of some USC-OSA members to a several local primary schools where we organized several optics experiments. In this work we present the optics demonstrations and the reaction of the 6 years-old students. The activities with greater acceptance include an explanation of light properties as polarization, refraction or reflection, and the workshop where they learnt how to build their own kaleidoscope and made a chromatic disk. Besides, they also participated in a demonstration and explanation of color properties and some optical illusions. We think that this activity has several benefits including spreading Optics through children meanwhile they have fun and experiment science in real life, as well as helping teachers to explain some complex properties and Physics phenomena of light. Given the broad acceptance of this activity, we are intending to make it a routine event of our student chapter repeating it every year. (paper)

  9. Onset conditions for equatorial spread F

    International Nuclear Information System (INIS)

    Mendillo, M.; Baumgardner, J.; Xiaoqing Pi; Sultan, P.J.; Tsunoda, R.

    1992-01-01

    The problem of day-to-day variability in the occurrence of equatorial spread F (ESF) is addressed using multidiagnostic observations and semiempirical modeling. The observational results are derived from a two-night case study of ESF onset conditions observed at Kwajalein Atoll (Marshall Islands) using the ALTAIR incoherent scatter radar and all-sky optical imaging techniques. The major difference between nights when ESF instabilities did not occur (August 14, 1988) and did occur (August 15, 1988) in the Kwajalein sector was that the northern meridional gradient of 6300-angstrom airglow was reduced on the night of limited ESF activity. Modeling results suggest that this unusual airglow pattern is due to equatorward neutral winds. Previous researchers have shown that transequatorial thermospheric winds can exert a control over ESF seasonal and longitudinal occurrence patterns by inhibiting Rayleigh-Taylor instability growth rates. They present evidence to suggest that this picture can be extended to far shorter time scales, namely, that 'surges' in transequatoral winds acting over characteristic times of a few hours to a day can result in a stabilizing influence upon irregularity growth rates. The seemingly capricious nature of ESF onset may thus be controlled, in part, by the inherent variability of low-latitude thermospheric winds

  10. Spreading continents kick-started plate tectonics.

    Science.gov (United States)

    Rey, Patrice F; Coltice, Nicolas; Flament, Nicolas

    2014-09-18

    Stresses acting on cold, thick and negatively buoyant oceanic lithosphere are thought to be crucial to the initiation of subduction and the operation of plate tectonics, which characterizes the present-day geodynamics of the Earth. Because the Earth's interior was hotter in the Archaean eon, the oceanic crust may have been thicker, thereby making the oceanic lithosphere more buoyant than at present, and whether subduction and plate tectonics occurred during this time is ambiguous, both in the geological record and in geodynamic models. Here we show that because the oceanic crust was thick and buoyant, early continents may have produced intra-lithospheric gravitational stresses large enough to drive their gravitational spreading, to initiate subduction at their margins and to trigger episodes of subduction. Our model predicts the co-occurrence of deep to progressively shallower mafic volcanics and arc magmatism within continents in a self-consistent geodynamic framework, explaining the enigmatic multimodal volcanism and tectonic record of Archaean cratons. Moreover, our model predicts a petrological stratification and tectonic structure of the sub-continental lithospheric mantle, two predictions that are consistent with xenolith and seismic studies, respectively, and consistent with the existence of a mid-lithospheric seismic discontinuity. The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth's interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining.

  11. Spread of Zika virus in the Americas.

    Science.gov (United States)

    Zhang, Qian; Sun, Kaiyuan; Chinazzi, Matteo; Pastore Y Piontti, Ana; Dean, Natalie E; Rojas, Diana Patricia; Merler, Stefano; Mistry, Dina; Poletti, Piero; Rossi, Luca; Bray, Margaret; Halloran, M Elizabeth; Longini, Ira M; Vespignani, Alessandro

    2017-05-30

    We use a data-driven global stochastic epidemic model to analyze the spread of the Zika virus (ZIKV) in the Americas. The model has high spatial and temporal resolution and integrates real-world demographic, human mobility, socioeconomic, temperature, and vector density data. We estimate that the first introduction of ZIKV to Brazil likely occurred between August 2013 and April 2014 (90% credible interval). We provide simulated epidemic profiles of incident ZIKV infections for several countries in the Americas through February 2017. The ZIKV epidemic is characterized by slow growth and high spatial and seasonal heterogeneity, attributable to the dynamics of the mosquito vector and to the characteristics and mobility of the human populations. We project the expected timing and number of pregnancies infected with ZIKV during the first trimester and provide estimates of microcephaly cases assuming different levels of risk as reported in empirical retrospective studies. Our approach represents a modeling effort aimed at understanding the potential magnitude and timing of the ZIKV epidemic and it can be potentially used as a template for the analysis of future mosquito-borne epidemics.

  12. Metallicity Spreads in M31 Globular Clusters

    Science.gov (United States)

    Bridges, Terry

    2003-07-01

    Our recent deep HST photometry of the M31 halo globular cluster {GC} Mayall II, also called G1, has revealed a red-giant branch with a clear spread that we attribute to an intrinsic metallicity dispersion of at least 0.4 dex in [Fe/H]. The only other GC exhibiting such a metallicity dispersion is Omega Centauri, the brightest and most massive Galactic GC, whose range in [Fe/H] is about 0.5 dex. These observations are obviously linked to the fact that both G1 and Omega Cen are bright and massive GC, with potential wells deep enough to keep part of their gas, which might have been recycled, producing a metallicity scatter among cluster stars. These observations dramatically challenge the notion of chemical homogeneity as a defining characteristic of GCs. It is critically important to find out how common this phenomenon is and how it can constrain scenarios/models of GC formation. The obvious targets are other bright and massive GCs, which exist in M31 but not in our Galaxy where Omega Cen is an isolated giant. We propose to acquire, with ACS/HRC, deep imaging of 3 of the brightest M31 GCs for which we have observed velocity dispersion values similar to those observed in G1 and Omega Cen. A sample of GCs with chemical abundance dispersions will provide essential information about their formation mechanism. This would represent a major step for the studies of the origin and evolution of stellar populations.

  13. Spreading Culture on Quantum Entanglement and Consciousness

    Science.gov (United States)

    Nobili, G.; Teodorani, M.

    The subject of "quantum entanglement" in general doesn't seem to be particularly considered in Europe in the form of popularizing books or of educational physics projects. These authors have started to spread out this kind of scientific culture in both forms, including popularizing seminars too. Concerning the entanglement phenomenon, recently, new thought experiments have been outlined, new laboratory results have come out in the form of real discoveries in quantum optics, new studies on "bio-entanglement" and 'global consciousness effects' have been carried out, and very sophisticated new ideas have been developed in the fields of quantum physics, biophysics, cosmology and epistemology. These authors intend to show their effort of diffusing widely this growing scientific knowledge. Beyond all this there is a long-term strategy aimed at inculcating new concepts in physics in order to trigger the interest of scholars at all levels, in that which is probably the most innovative and interdisciplinary subject of the human knowledge of this new millennium.

  14. Spread of Traditional Medicines in India

    Science.gov (United States)

    Srinivasan, R.; Sugumar, V. Raji

    2015-01-01

    For the first time, we have a comprehensive database on usage of AYUSH (acronym for Ayurveda, naturopathy and Yoga, Unani, Siddha, and Homeopathy) in India at the household level. This article aims at exploring the spread of the traditional medical systems in India and the perceptions of people on the access and effectiveness of these medical systems using this database. The article uses the unit level data purchased from the National Sample Survey Organization, New Delhi. Household is the basic unit of survey and the data are the collective opinion of the household. This survey shows that less than 30% of Indian households use the traditional medical systems. There is also a regional pattern in the usage of particular type of traditional medicine, reflecting the regional aspects of the development of such medical systems. The strong faith in AYUSH is the main reason for its usage; lack of need for AYUSH and lack of awareness about AYUSH are the main reasons for not using it. With regard to source of medicines in the traditional medical systems, home is the main source in the Indian medical system and private sector is the main source in Homeopathy. This shows that there is need for creating awareness and improving access to traditional medical systems in India. By and large, the users of AYUSH are also convinced about the effectiveness of these traditional medicines. PMID:26438717

  15. Spreading Optics in the primary school

    Science.gov (United States)

    Gargallo, Ana; Gómez-Varela, Ana I.; Gónzalez-Nuñez, Héctor; Delgado, Tamara; Almaguer, Citlalli; Cambronero, Ferran; García-Sánchez, Ángel; Pallarés, David; Aymerich, María; Aragón, Ángel L.; Flores-Arias, Maria T.

    2015-04-01

    The USC-OSA is a student chapter located at the University of Santiago de Compostela (Spain) whose objective is to bring optics and photonics knowledge closer to general public. In order to arouse kids' interest in Optics we developed an activity called Funny Light. This activity consisted on a visit of some USC-OSA members to a several local primary schools where we organized several optics experiments. In this work we present the optics demonstrations and the reaction of the 6 years-old students. The activities with greater acceptance include an explanation of light properties as polarization, refraction or reflection, and the workshop where they learnt how to build their own kaleidoscope and made a chromatic disk. Besides, they also participated in a demonstration and explanation of color properties and some optical illusions. We think that this activity has several benefits including spreading Optics through children meanwhile they have fun and experiment science in real life, as well as helping teachers to explain some complex properties and Physics phenomena of light. Given the broad acceptance of this activity, we are intending to make it a routine event of our student chapter repeating it every year.

  16. Facing Two Rapidly Spreading Internet Worms

    CERN Multimedia

    IT Department

    2009-01-01

    The Internet is currently facing a growing number of computer infections due to two rapidly spreading worms. The "Conficker" and "Downadup" worms have infected an estimated 1.1 million PCs in a 24-hour period, bringing the total number of infected computers to 3.5 million [1]. Via a single USB stick, these worms were also responsible for the infection of about 40 laptops at the last EGEE conference in Istanbul. In order to reduce the impact of these worms on CERN Windows computers, the Computer Security Team has suggested several preventive measures described here. Disabling the Windows AutoRun and AutoPlay Features The Computer Security Team and the IT/IS group have decided to disable the "AutoRun" and "AutoPlay" functionality on all centrally-managed Windows computers at CERN. When inserting CDs, DVDs or USB sticks into a PC, "AutoRun" and "AutoPlay" are responsible for automatically playing music or films stored on these media, or ...

  17. Numerical unit spread assessment pedigree (NUSAP)

    International Nuclear Information System (INIS)

    Schaffhauser, A. Jr.

    1994-01-01

    Data estimates and information require a system for signaling the uncertainty and quality of the entries for users. Few of the entries will be known with certainty, or even generally agreed upon as the prevalent quantity or relation. For example, the ecological or health responses of resources exposed to energy-related pollutants cannot be known with certainty given current knowledge of the relationships. The monetary valuations associated with the imperfectly known impacts are also uncertain and sometimes controversial. To leave entries standing alone without signaling their uncertainty and quality would overstate the precision with which the entries are known. In addition, signaling the uncertainty and quality for entries will indicate areas where further study is needed most. Uncertainty and quality are signaled through a notational system named NUSAP as an acronym for its categories. NUSAP was developed by Funtowicz and Ravetz to provide a 'quality control' of quantitative information.' We have adapted the NUSAP system for signaling the uncertainty and quality of quantitative information to be used in estimating the emissions, impacts, NUSAP and external costs of fuel cycles. Uncertainty refers to the spread of plausible values for a cell entry and the level of confidence placed in a quantitative statement. Quality refers to both an entry's worth as a piece of information and the credibility of the theory, data, and methods used to generate the entry

  18. Eastern European retailers and wholesalers' buying behaviour

    DEFF Research Database (Denmark)

    Esbjerg, Lars; Stacey, Julia

    1999-01-01

    During the last ten years, retailing in Eastern Europe has undergone considerable changes. The entry of Western European retail chains into Eastern Europe has helped accelerate the distributive trade of Eastern Europe. But what does it take to sell fish and cheese to retailers and wholesalers...... in Eastern Europe compared to Western Europe? Eastern European buyers attach great importance to other aspects when they list new suppliers and products than does Western European retailing. These are the results of a MAPP study of Eastern European retail and wholesale buying behaviour for fish and cheese....... Low prices and favourable terms of payment are most important when retailers in Eastern Europe buy fish and cheese. Then follows the supplier's range of products, trustworthiness of the supplier and product quality. Eastern European wholesalers also rank price and financial conditions as most...

  19. Eastern Africa Social Science Research Review: Contact

    African Journals Online (AJOL)

    Eastern Africa Social Science Research Review: Contact. Journal Home > About the Journal > Eastern Africa Social Science Research Review: Contact. Log in or Register to get access to full text downloads.

  20. The reasons for successful spreading of the fishes from the genus Carassius

    Directory of Open Access Journals (Sweden)

    Lukáš Kalous

    2015-11-01

    Full Text Available Freshwater fishes of the genus Carassius are widespread throughout home Eurasia but also other continents (Kottelat and Feryhof, 2007. They represent important aquaculture fishes and include the world's most important pet fish, the goldfish (Rylková et al., 2010. On the other hand they are also the most successful invasive pests with a considerable ecological impact at many places (Ribeiro et al., 2015; Copp et al., 2005. High similarities in morphological taxa definitions and occurrence of species complexes have brought lot of confusion in their taxonomy, biogeography and introduction history (Kalous et al., 2012. We present a historical overview and outline past and present reasons that have led to their successful spreading. Our findings are based on phylogenetic, historical and social-economic data. Europe is inhabited by at least five mtDNA lineages of the genus Carassius, which correspond to four taxa and one undescribed species. In Europe there occur: Carassius carassius, feral populations of Carassius auratus, Carassius gibelio, Carassius langsdorfii and Carassius sp.. C. auratus and C. langsdorfii are not native to Europe C. carassius is native to Eastern, Central and Northern Europe (Kalous et al., 2012. The populations of C. gibelio in Eastern and Central Europe should be considered a result of natural postglacial range expansion but the whole Europe was also colonized by introduced Carassius biotypes of various genome combinations from East Asia in the 20th century (Rylková et al., 2013. The spreading of non-native fishes of the genus Carassius has been caused mainly by human activities comprising pet trade, aquaculture and recreational fisheries (Kalous et al., 2013; Kalous et al., 2015.

  1. Dynamic properties of epidemic spreading on finite size complex networks

    Science.gov (United States)

    Li, Ying; Liu, Yang; Shan, Xiu-Ming; Ren, Yong; Jiao, Jian; Qiu, Ben

    2005-11-01

    The Internet presents a complex topological structure, on which computer viruses can easily spread. By using theoretical analysis and computer simulation methods, the dynamic process of disease spreading on finite size networks with complex topological structure is investigated. On the finite size networks, the spreading process of SIS (susceptible-infected-susceptible) model is a finite Markov chain with an absorbing state. Two parameters, the survival probability and the conditional infecting probability, are introduced to describe the dynamic properties of disease spreading on finite size networks. Our results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks. Also, knowledge about the dynamic character of virus spreading is helpful for adopting immunity policy.

  2. Minimizing Energy Spread In The REX/HIE-ISOLDE Linac

    CERN Document Server

    Yucemoz, Mert

    2017-01-01

    This report tries to minimize the energy spread of the beam at the end of the REX-HIE-ISOLDE Linac using the last RF cavity as a buncher. Beams with very low energy spread are often required by the users of the facility In addition, one of the main reason to have minimum energy spread in longitudinal phase space is that higher beam energy spread translates in to a position spread after interacting with target. This causes an overlap in the position of different particles that makes it difficult to distinguish them. Hence, in order to find the operation settings for minimum energy spread at the end of the REX-HIE-ISOLDE linac and to inspect the ongoing physics, several functions on Matlab were created that runs beam dynamics program called “TRACKV39” that provides some graphs and values as a result for analysis.

  3. Asymmetrically interacting spreading dynamics on complex layered networks.

    Science.gov (United States)

    Wang, Wei; Tang, Ming; Yang, Hui; Younghae Do; Lai, Ying-Cheng; Lee, GyuWon

    2014-05-29

    The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics.

  4. Passive bookshelf faulting driven by gravitational spreading as the cause of the tiger-stripe-fracture formation and development in the South Polar Terrain of Enceladus

    Science.gov (United States)

    Yin, A.; Pappalardo, R. T.

    2013-12-01

    Detailed photogeologic mapping of the tiger-stripe fractures in the South Polar Terrain (SPT) of Enceladus indicates that these structures are left-slip faults and terminate at hook-shaped fold-thrust zones and/or Y-shaped horsetail splay-fault zones. The semi-square-shaped tectonic domain that hosts the tiger-stripe faults is bounded by right-slip and left-slip faults on the north and south edges and fold-thrust and extensional zones on the western and eastern edges. We explain the above observations by a passive bookshelf-faulting model in which individual tiger-stripe faults are bounded by deformable wall rocks accommodating distributed deformation. Based on topographic data, we suggest that gravitational spreading had caused the SPT to spread unevenly from west to east. This process was accommodated by right-slip and left-slip faulting on the north and south sides and thrusting and extension along the eastern and southern margins of the tiger-stripe tectonic domain. The uneven spreading, expressed by a gradual northward increase in the number of extensional faults and thrusts/folds along the western and eastern margins, was accommodated by distributed right-slip simple shear across the whole tiger-stripe tectonic domain. This mode of deformation in turn resulted in the development of a passive bookshelf-fault system characterized by left-slip faulting on individual tiger-stripe fractures.

  5. Community Size Effects on Epidemic Spreading in Multiplex Social Networks

    OpenAIRE

    Liu, Ting; Li, Ping; Chen, Yan; Zhang, Jie

    2016-01-01

    The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explo...

  6. Farm-retail price spread for pork in Malaysia

    OpenAIRE

    Tey, (John) Yeong-Sheng; Randy, Stringer; Wendy, Umberger

    2009-01-01

    The price difference between farm and retail levels is called price spread, which is constituted mostly by marketing costs and profits. From the price spread, this paper intends to estimate elasticities of price transmission for pork in Malaysia via different empirical model specifications of markup pricing model. Using data from January 1997 to December 2007, a quantitative analysis of farm-to-retail price spreads was undertaken for pork in Malaysia. It was found that retail price is the onl...

  7. Spreading dynamics of power-law fluid droplets

    International Nuclear Information System (INIS)

    Liang Zhanpeng; Peng Xiaofeng; Wang Xiaodong; Lee, D-J; Su Ay

    2009-01-01

    This paper aims at providing a summary of the theoretical models available for non-Newtonian fluid spreading dynamics. Experimental findings and model predictions for a Newtonian fluid spreading test are briefly reviewed. Then how the complete wetting and partial wetting power-law fluids spread over a solid substrate is examined. The possible extension of Newtonian fluid models to power-law fluids is also discussed.

  8. Hybrid epidemic spreading - from Internet worms to HIV infection

    OpenAIRE

    Zhang, C.

    2015-01-01

    Epidemic phenomena are ubiquitous, ranging from infectious diseases, computer viruses, to information dissemination. Epidemics have traditionally been studied as a single spreading process, either in a fully mixed population or on a network. Many epidemics, however, are hybrid, employing more than one spreading mechanism. For example, the Internet worm Conficker spreads locally targeting neighbouring computers in local networks as well as globally by randomly probing any computer on the Inter...

  9. Relationship between attenuation coefficients and dose-spread kernels

    International Nuclear Information System (INIS)

    Boyer, A.L.

    1988-01-01

    Dose-spread kernels can be used to calculate the dose distribution in a photon beam by convolving the kernel with the primary fluence distribution. The theoretical relationships between various types and components of dose-spread kernels relative to photon attenuation coefficients are explored. These relations can be valuable as checks on the conservation of energy by dose-spread kernels calculated by analytic or Monte Carlo methods

  10. Currency substitution in Eastern Europe

    NARCIS (Netherlands)

    van Aarle, B.; Budina, N.

    1995-01-01

    Monetary instability during the transition process from a command economy to a market economy has induced a considerable increase in currency substitution in Eastern Europe. Currency substitution itself affects monetary stability since it reduces the stability of velocity. This paper investigates

  11. Anthracnose Diseases of Eastern Hardwoods

    Science.gov (United States)

    Frederick H. Berry

    1985-01-01

    Anthracnose diseases of hardwood trees are widespread throughout the Eastern United States. The most common symptom of these diseases is dead areas or blotches on the leaves. Because of the brown and black, scorched appearance of the leaves, the diseases are sometimes called leaf blight.

  12. Citizenship norms in Eastern Europe

    NARCIS (Netherlands)

    Coffé, H.R.; Lippe, T. van der

    2010-01-01

    Research on Eastern Europe stresses the weakness of its civil society and the lack of political and social involvement, neglecting the question: What do people themselves think it means to be a good citizen? This study looks at citizens’ definitions of good citizenship in Poland, Slovenia, the Czech

  13. Uranium mining in Eastern Germany

    International Nuclear Information System (INIS)

    Sauer, H.D.

    1990-01-01

    A problem which simply does not exist in Western Germany is the uranium mining in the South of Eastern Germany (SDAG Wismuth). The cleaning up and control measure which are urgently needed will be a task for more than one generation. (orig./HP) [de

  14. The small world yields the most effective information spreading

    International Nuclear Information System (INIS)

    Lü Linyuan; Chen Duanbing; Zhou Tao

    2011-01-01

    The spreading dynamics of information and diseases are usually analyzed by using a unified framework and analogous models. In this paper, we propose a model to emphasize the essential difference between information spreading and epidemic spreading, where the memory effects, the social reinforcement and the non-redundancy of contacts are taken into account. Under certain conditions, the information spreads faster and broader in regular networks than in random networks, which to some extent supports the recent experimental observation of spreading in online society (Centola D 2010 Science 329 1194). At the same time, the simulation result indicates that the random networks tend to be favorable for effective spreading when the network size increases. This challenges the validity of the above-mentioned experiment for large-scale systems. More importantly, we show that the spreading effectiveness can be sharply enhanced by introducing a little randomness into the regular structure, namely the small-world networks yield the most effective information spreading. This work provides insights into the role of local clustering in information spreading. (paper)

  15. Dynamics of Ionic Shifts in Cortical Spreading Depression.

    Science.gov (United States)

    Enger, Rune; Tang, Wannan; Vindedal, Gry Fluge; Jensen, Vidar; Johannes Helm, P; Sprengel, Rolf; Looger, Loren L; Nagelhus, Erlend A

    2015-11-01

    Cortical spreading depression is a slowly propagating wave of near-complete depolarization of brain cells followed by temporary suppression of neuronal activity. Accumulating evidence indicates that cortical spreading depression underlies the migraine aura and that similar waves promote tissue damage in stroke, trauma, and hemorrhage. Cortical spreading depression is characterized by neuronal swelling, profound elevation of extracellular potassium and glutamate, multiphasic blood flow changes, and drop in tissue oxygen tension. The slow speed of the cortical spreading depression wave implies that it is mediated by diffusion of a chemical substance, yet the identity of this substance and the pathway it follows are unknown. Intercellular spread between gap junction-coupled neurons or glial cells and interstitial diffusion of K(+) or glutamate have been proposed. Here we use extracellular direct current potential recordings, K(+)-sensitive microelectrodes, and 2-photon imaging with ultrasensitive Ca(2+) and glutamate fluorescent probes to elucidate the spatiotemporal dynamics of ionic shifts associated with the propagation of cortical spreading depression in the visual cortex of adult living mice. Our data argue against intercellular spread of Ca(2+) carrying the cortical spreading depression wavefront and are in favor of interstitial K(+) diffusion, rather than glutamate diffusion, as the leading event in cortical spreading depression. © The Author 2015. Published by Oxford University Press.

  16. Beam-width spreading of vortex beams in free space

    Science.gov (United States)

    Wang, Weiwei; Li, Jinhong; Duan, Meiling

    2018-01-01

    Based on the extended Huygens-Fresnel principle and the definition of second-order moments of the Wigner distribution function, the analytical expression for the beam-width spreading of Gaussian Schell-model (GSM) vortex beams in free space are derived, and used to study the influence of beam parameters on the beam-width spreading of GSM vortex beams. With the increment of the propagation distance, the beam-width spreading of GSM vortex beams will increase; the bigger the topological charge, spatial correlation length, wavelength and waist width are, the smaller the beam-width spreading is.

  17. Perineural spread of nasopharyngeal carcinoma: Radiological and CT demonstration

    International Nuclear Information System (INIS)

    Pandolfo, I.; Gaeta, M.; Longo, M.; Faranda, C.; Blandino, A.

    1988-01-01

    Perineural spread is well known to be the most insidious form of tumour spread of a number of head and neck malignancies. However, perineural extension of nasopharyngeal carcinoma (NC) is a poorly recognized event. Four cases of perineural metastases from NC have been detected with pluridirectional tomography and CT. In 3 cases involvement of the Vidian nerve (nervus canalis pterygoidei) and pterygoid canal was observed. In a fourth patient, invasion of one pterygopalatine fossa and perineural spread along ipsilateral maxillary nerve with enlargement and erosion of the foramen rotundum was demonstrated. Radiological diagnosis of clinically unsuspected perineural tumour spread is important because it markedly influences treatment planning and prognosis of NC. (orig.)

  18. Perineural spread of nasopharyngeal carcinoma: Radiological and CT demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Pandolfo, I.; Gaeta, M.; Longo, M.; Faranda, C.; Blandino, A.

    1988-11-01

    Perineural spread is well known to be the most insidious form of tumour spread of a number of head and neck malignancies. However, perineural extension of nasopharyngeal carcinoma (NC) is a poorly recognized event. Four cases of perineural metastases from NC have been detected with pluridirectional tomography and CT. In 3 cases involvement of the Vidian nerve (nervus canalis pterygoidei) and pterygoid canal was observed. In a fourth patient, invasion of one pterygopalatine fossa and perineural spread along ipsilateral maxillary nerve with enlargement and erosion of the foramen rotundum was demonstrated. Radiological diagnosis of clinically unsuspected perineural tumour spread is important because it markedly influences treatment planning and prognosis of NC.

  19. Epidemic spreading on random surfer networks with infected avoidance strategy

    International Nuclear Information System (INIS)

    Feng Yun; Ding Li; Huang Yun-Han; Guan Zhi-Hong

    2016-01-01

    In this paper, we study epidemic spreading on random surfer networks with infected avoidance (IA) strategy. In particular, we consider that susceptible individuals’ moving direction angles are affected by the current location information received from infected individuals through a directed information network. The model is mainly analyzed by discrete-time numerical simulations. The results indicate that the IA strategy can restrain epidemic spreading effectively. However, when long-distance jumps of individuals exist, the IA strategy’s effectiveness on restraining epidemic spreading is heavily reduced. Finally, it is found that the influence of the noises from information transferring process on epidemic spreading is indistinctive. (paper)

  20. Epidemic spreading in time-varying community networks.

    Science.gov (United States)

    Ren, Guangming; Wang, Xingyuan

    2014-06-01

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold qc. The epidemic will survive when q > qc and die when q epidemic spreading in complex networks with community structure.

  1. Risk assessment for canine leishmaniasis spreading in the north of Italy

    Directory of Open Access Journals (Sweden)

    Giulia Morosetti

    2009-11-01

    Full Text Available The incidence of zoonotic visceral leishmaniasis has not only been recognized but is, in fact, increasing in territories of northern continental Italy previously regarded as non-endemic. Recent findings of sporadic autochthonous canine infections and the presence of phlebotomine vectors in some provinces of north-eastern Italy have stimulated risk assessment for the spreading of leishmaniasis in the autonomous province of Bolzano-South Tyrol, the northernmost territory of the Italian eastern Alps. In July 2008, 61 phlebotomine sand flies (Diptera, Psychodidae were caught and identified as Phlebotomus perniciosus and Sergentomyia minuta. This is the first record in South Tyrol of P. perniciosus, the most competent vector of Leishmania infantum in Mediterranean countries. Leishmania serology on local dogs kept in kennels gave negative results, while only imported canine leishmaniasis cases were reported by local veterinarians through a questionnaire survey. Bio-geographic aspects and epidemiological consequences are analyzed in relation with the risk of leishmaniasis introduction into the area.

  2. Genetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa

    Science.gov (United States)

    Ranciaro, Alessia; Campbell, Michael C.; Hirbo, Jibril B.; Ko, Wen-Ya; Froment, Alain; Anagnostou, Paolo; Kotze, Maritha J.; Ibrahim, Muntaser; Nyambo, Thomas; Omar, Sabah A.; Tishkoff, Sarah A.

    2014-01-01

    In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ∼2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ∼198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa. PMID:24630847

  3. Genetic origins of lactase persistence and the spread of pastoralism in Africa.

    Science.gov (United States)

    Ranciaro, Alessia; Campbell, Michael C; Hirbo, Jibril B; Ko, Wen-Ya; Froment, Alain; Anagnostou, Paolo; Kotze, Maritha J; Ibrahim, Muntaser; Nyambo, Thomas; Omar, Sabah A; Tishkoff, Sarah A

    2014-04-03

    In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ~2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ~198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa. Copyright © 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  4. Range-Wide Genetic Analysis of Little Brown Bat (Myotis lucifugus Populations: Estimating the Risk of Spread of White-Nose Syndrome.

    Directory of Open Access Journals (Sweden)

    Maarten J Vonhof

    Full Text Available The little brown bat (Myotis lucifugus is one of the most widespread bat species in North America and is experiencing severe population declines because of an emerging fungal disease, white-nose syndrome (WNS. To manage and conserve this species effectively it is important to understand patterns of gene flow and population connectivity to identify possible barriers to disease transmission. However, little is known about the population genetic structure of little brown bats, and to date, no studies have investigated population structure across their entire range. We examined mitochondrial DNA and nuclear microsatellites in 637 little brown bats (including all currently recognized subspecific lineages from 29 locations across North America, to assess levels of genetic variation and population differentiation across the range of the species, including areas affected by WNS and those currently unaffected. We identified considerable spatial variation in patterns of female dispersal and significant genetic variation between populations in eastern versus western portions of the range. Overall levels of nuclear genetic differentiation were low, and there is no evidence for any major barriers to gene flow across their range. However, patterns of mtDNA differentiation are highly variable, with high ΦST values between most sample pairs (including between all western samples, between western and eastern samples, and between some eastern samples, while low mitochondrial differentiation was observed within two groups of samples found in central and eastern regions of North America. Furthermore, the Alaskan population was highly differentiated from all others, and western populations were characterized by isolation by distance while eastern populations were not. These data raise the possibility that the current patterns of spread of WNS observed in eastern North America may not apply to the entire range and that there may be broad-scale spatial variation in

  5. Monitoring presence and advance of the alien invasive western corn rootworm beetle in eastern Slovenia with highly sensitive Metcalf traps.

    Science.gov (United States)

    Hummel, H E; Urek, G; Modic, S; Hein, D F

    2005-01-01

    The American Chrysomelid beetle Diabrotica virgifera virgifera LeConte (D.v.v.), also called the western corn rootworm, spread from the location of its original introduction into Europe, Belgrade airport (BACA 1993), in all directions. Within a decade it occupied almost all countries of South-eastern and Central Europe. However, it reached Slovenia as late as 2003: Only 19 specimen were found in maize fields of the eastern and also western provinces. Already in the summer of 2004, their number had risen to 386 which were mainly found in the eastern provinces near the borders to Croatia, Austria and Hungary. For their monitoring, a simple trap is being described which can be acquired in high numbers at a very low price and can guaranty a most sensitive detection of beetles. The Metcalf cup trap which in Slovenia so far has been unknown performed the task of monitoring quite well at five locations. It will also facilitate the future search for new and increasing infestations. Comparing 2004 with the year 2003, D.v.v. expanded its range in eastern Slovenia by about 15 km. These new infestations will include territories in which fields of the regionally Important oil seed pumpkin Cucurbita pepo are located. With important traffic connections between South-eastern and Central Europe, Slovenia will occupy a bridgehead function in the preventive protection of maize from D.v.v. spreading into more northerly European regions including western Austria and southern Germany.

  6. Genetic reconstruction of a bullfrog invasion to elucidate vectors of introduction and secondary spread

    Science.gov (United States)

    Kamath, Pauline L.; Sepulveda, Adam; Layhee, Megan J.

    2016-01-01

    Reconstructing historical colonization pathways of an invasive species is critical for uncovering factors that determine invasion success and for designing management strategies. The American bullfrog (Lithobates catesbeianus) is endemic to eastern North America, but now has a global distribution and is considered to be one of the worst invaders in the world. In Montana, several introduced populations have been reported, but little is known of their sources and vectors of introduction and secondary spread. We evaluated the genetic composition of introduced populations at local (Yellowstone River floodplain) and regional (Montana and Wyoming) scales in contrast to native range populations. Our objectives were to (1) estimate the number of introductions, (2) identify probable native sources, (3) evaluate genetic variation relative to sources, and (4) characterize properties of local- and regional-scale spread. We sequenced 937 bp of the mitochondrial cytochrome b locus in 395 tadpoles collected along 100 km of the Yellowstone River, from three additional sites in MT and a proximate site in WY. Pairwise ΦST revealed high divergence among nonnative populations, suggesting at least four independent introductions into MT from diverse sources. Three cyt b haplotypes were identical to native haplotypes distributed across the Midwest and Great Lakes regions, and AMOVA confirmed the western native region as a likely source. While haplotype (Hd = 0.69) and nucleotide diversity (π = 0.005) were low in introduced bullfrogs, the levels of diversity did not differ significantly from source populations. In the Yellowstone, two identified haplotypes implied few introduction vectors and a significant relationship between genetic and river distance was found. Evidence for multiple invasions and lack of subsequent regional spread emphasizes the importance of enforcing legislation prohibiting bullfrog importation and the need for continuing public education to prevent

  7. Spreading of Somma-Vesuvio Volcanic Complex: is the Hazard for Plinian Eruptions being reduced?

    Science.gov (United States)

    Borgia, A.; Tizzani, P.; Solaro, G.; Luongo, G.; Fusi, N.

    2003-12-01

    Contrary to what is the common knowledge, a detailed structural study of active faulting and rifting of the summit area of Somma-Vesuvio volcanic complex, combined with INSAR, levelling data and seismic profiling at sea suggests that the present-day long-term dynamic behaviour of the complex and of its summit caldera is characterized by volcanic spreading. The structural evolution is controlled by a number of asymmetric, intersecting leaf-grabens. The boundary faults of these grabens intersect at different angles the Somma caldera walls generating a set of wedge-horsts. While normal faulting characterizes the Somma caldera walls, the lavas of the past 150 years, infilling the caldera, have been rifted all around the southern, eastern and northern base of Vesuvio's cone, which, in turn, is being displaced seaward. Associated to the subsidence and extension of the summit area, relative uplift occurs along the coast; in addition, deformation of recent sediments 6-18 km offshore also indicate compression and uplift, which appears to be unrelated to regional tectonics. A preliminary evaluation indicates that rifting of the lavas is in the order of 1-2 mm/a with a southwestward average direction of displacement. Based on these data, we suggest that a wide sector of Somma-Vesuvio is spreading on its plastic sedimentary substratum, which have been identified by drilling. Volcanic spreading appears to have controlled the magmatic evolution and the energy decrease of major historic explosive eruptions since 79 AD. If our interpretation is correct, major plinian eruptions should not occur in the near future. On the other hand, rifting around the caldera suggests that volcanic activity could soon be renewed.

  8. Community Size Effects on Epidemic Spreading in Multiplex Social Networks.

    Directory of Open Access Journals (Sweden)

    Ting Liu

    Full Text Available The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explore the interactions between disease spreading and population response in terms of information diffusion and individuals' alertness. We model the system by mapping multiplex networks into two-layer networks and incorporating individuals' risk awareness, on the assumption that their response to the disease spreading depends on the size of the community they belong to. By comparing the final incidence of diseases in multiplex networks, we find that there is considerable mitigation of diseases spreading for full phase of spreading speed when individuals' protection responses are introduced. Interestingly, the degree of community overlap between the two layers is found to be critical factor that affects the final incidence. We also analyze the consequences of the epidemic incidence in communities with different sizes and the impacts of community overlap between two layers. Specifically, as the diseases information makes individuals alert and take measures to prevent the diseases, the effective protection is more striking in small community. These phenomena can be explained by the multiplexity of the networked system and the competition between two spreading processes.

  9. Community Size Effects on Epidemic Spreading in Multiplex Social Networks.

    Science.gov (United States)

    Liu, Ting; Li, Ping; Chen, Yan; Zhang, Jie

    2016-01-01

    The dynamical process of epidemic spreading has drawn much attention of the complex network community. In the network paradigm, diseases spread from one person to another through the social ties amongst the population. There are a variety of factors that govern the processes of disease spreading on the networks. A common but not negligible factor is people's reaction to the outbreak of epidemics. Such reaction can be related information dissemination or self-protection. In this work, we explore the interactions between disease spreading and population response in terms of information diffusion and individuals' alertness. We model the system by mapping multiplex networks into two-layer networks and incorporating individuals' risk awareness, on the assumption that their response to the disease spreading depends on the size of the community they belong to. By comparing the final incidence of diseases in multiplex networks, we find that there is considerable mitigation of diseases spreading for full phase of spreading speed when individuals' protection responses are introduced. Interestingly, the degree of community overlap between the two layers is found to be critical factor that affects the final incidence. We also analyze the consequences of the epidemic incidence in communities with different sizes and the impacts of community overlap between two layers. Specifically, as the diseases information makes individuals alert and take measures to prevent the diseases, the effective protection is more striking in small community. These phenomena can be explained by the multiplexity of the networked system and the competition between two spreading processes.

  10. Topology dependent epidemic spreading velocity in weighted networks

    NARCIS (Netherlands)

    Duan, W.; Quax, R.; Lees, M.; Qiu, X.; Sloot, P.M.A.

    2014-01-01

    Many diffusive processes occur on structured networks with weighted links, such as disease spread by airplane transport or information diffusion in social networks or blogs. Understanding the impact of weight-connectivity correlations on epidemic spreading in weighted networks is crucial to support

  11. Dynamics of a spreading thin film with gravitational counterflow ...

    Indian Academy of Sciences (India)

    film climbing up on a vertical substrate against gravity shows interesting dynamics ... For the spreading of a thin film several theoretical studies have shown quantitative agree- ..... The two critical values of this param- ... Davis J M, Fischer B J and Troian S M 2003 A general approach to the linear stability of thin spreading.

  12. Age-Related Changes in Spreading Activation during Infancy

    Science.gov (United States)

    Barr, Rachel; Walker, Joanne; Gross, Julien; Hayne, Harlene

    2014-01-01

    The concept of spreading activation describes how retrieval of one memory cues retrieval of other memories that are associated with it. This study explored spreading activation in 6-, 12-, and 18-month-old infants. Infants (n = 144) learned two tasks within the same experimental session; one task, deferred imitation (DI), is typically remembered…

  13. Credit ratings and bond spreads of the GIIPS

    NARCIS (Netherlands)

    de Vries, Tim; de Haan, Jakob

    2016-01-01

    We examine the relationship between credit ratings and bond yield spreads of peripheral countries in the euro area (Greece, Ireland, Italy, Portugal and Spain) for the period 1995-2014. Since 2012, bond spreads of those countries have come down very fast, whereas credit ratings have hardly changed.

  14. Spread of H1N1 within Households

    Centers for Disease Control (CDC) Podcasts

    This podcast describes an investigation into how H1N1 was spreading within households during the initial days of the pandemic in Texas. CDC's Dr. Oliver Morgan discusses what investigators learned about the role that children played in introducing the virus into households and spreading flu.

  15. Dogwood Anthracnose and its Spread in the South

    Science.gov (United States)

    Robert L. Anderson; John L. Knighten; Keith Langdon; Floyd Hedrix; Ron Roncadori

    In the 15 years since it was first reported in the United States, dogwood anthracnose (caused by Discula destructive sp. nov.) has spread rapidly and caused serious losses among flowering dogwoods (Cornus florida L.), particularly in the South. Infection begins in leaves and spreads to twigs and branches, which dieback. Main-stem infections cause cankers, which kill...

  16. Regime-dependent determinants of Euro area sovereign CDS spreads

    NARCIS (Netherlands)

    Blommestein, H.J.; Eijffinger, Sylvester; Qian, Zongxin

    We study the determinants of sovereign CDS spreads of five Euro area countries (Greece, Ireland, Italy, Portugal, and Spain) after the collapse of Lehman Brothers. We find that global and/or European Monetary Union (EMU)-wide factors are the main drivers of changes in the sovereign CDS spreads in

  17. Comparative study on spreading function for directional wave spectra

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.S.; Anand, N.M.; Nayak, B.U.

    -dimensional wave energy S(f) and the directional spreading function D(f, theta). This paper reviews various spreading functions proposed in the past for estimating the directional wave energy and presents their application to the Indian wave condition. It is found...

  18. The potential and realized spread of wildfires across Canada

    Science.gov (United States)

    Xianli Wang; Marc-Andre Parisien; Mike D. Flannigan; Sean A. Parks; Kerry R. Anderson; John M. Little; Steve W. Taylor

    2014-01-01

    Given that they can burn for weeks or months, wildfires in temperate and boreal forests may become immense (eg., 100 - 04 km2). However, during the period within which a large fire is 'active', not all days experience weather that is conducive to fire spread; indeed most of the spread occurs on a small proportion (e.g., 1 - 15 days) of not necessarily...

  19. An examination of fire spread thresholds in discontinuous fuel beds

    Science.gov (United States)

    Mark A. Finney; Jack D. Cohen; Isaac C. Grenfell; Kara M. Yedinak

    2010-01-01

    Many fuel beds, especially live vegetation canopies (conifer forests, shrub fields, bunch-grasses) contain gaps between vegetation clumps. Fires burning in these fuel types often display thresholds for spread that are observed to depend on environmental factors like wind, slope, and fuel moisture content. To investigate threshold spread behaviours, we conducted a set...

  20. Individual stock-option prices and credit spreads

    NARCIS (Netherlands)

    Cremers, M.; Driessen, J.; Maenhout, P.; Weinbaum, D.

    2008-01-01

    This paper introduces measures of volatility and jump risk that are based on individual stock options to explain credit spreads on corporate bonds. Implied volatilities of individual options are shown to contain useful information for credit spreads and improve on historical volatilities when

  1. Human activity and the spread of Phytophthora ramorum

    Science.gov (United States)

    Hall J. Cushman; Michelle Cooper; Ross K. Meentemeyer; Shelly Benson

    2008-01-01

    Increasing numbers of studies are finding that humans can facilitate the spread of exotic plant species in protected wildlands. Hiking trails commonly serve as conduits for invaders and the number of exotic plant species occurring in protected areas is often correlated positively with visitation rates. Despite such evidence linking human activity to the spread of...

  2. Raman hyperspectral imaging and analysis of fat spreads

    NARCIS (Netherlands)

    Dalen, van G.; Velzen, van E.J.J.; Heussen, P.C.M.; Sovago, M.; Malssen, van K.F.; Duynhoven, van J.P.M.

    2017-01-01

    The microstructure of fat spreads is of fundamental importance to their sensorial properties such as texture, mouthfeel and spreadability. Fat spreads are water in oil emulsions,with a continuous phase supported by a fat crystal network. Confocal Raman microscopy offers the possibility for the

  3. Epidemic spread in bipartite network by considering risk awareness

    Science.gov (United States)

    Han, She; Sun, Mei; Ampimah, Benjamin Chris; Han, Dun

    2018-02-01

    Human awareness plays an important role in the spread of infectious diseases and the control of propagation patterns. Exploring the interplay between human awareness and epidemic spreading is a topic that has been receiving increasing attention. Considering the fact, some well-known diseases only spread between different species we propose a theoretical analysis of the Susceptible-Infected-Susceptible (SIS) epidemic spread from the perspective of bipartite network and risk aversion. Using mean field theory, the epidemic threshold is calculated theoretically. Simulation results are consistent with the proposed analytic model. The results show that, the final infection density is negative linear with the value of individuals' risk awareness. Therefore, the epidemic spread could be effectively suppressed by improving individuals' risk awareness.

  4. The spreading time in SIS epidemics on networks

    Science.gov (United States)

    He, Zhidong; Van Mieghem, Piet

    2018-03-01

    In a Susceptible-Infected-Susceptible (SIS) process, we investigate the spreading time Tm, which is the time when the number of infected nodes in the metastable state is first reached, starting from the outbreak of the epidemics. We observe that the spreading time Tm resembles a lognormal-like distribution, though with different deep tails, both for the Markovian and the non-Markovian infection process, which implies that the spreading time can be very long with a relatively high probability. In addition, we show that a stronger virus, with a higher effective infection rate τ or an earlier timing of the infection attempts, does not always lead to a shorter average spreading time E [Tm ] . We numerically demonstrate that the average spreading time E [Tm ] in the complete graph and the star graph scales logarithmically as a function of the network size N for a fixed fraction of infected nodes in the metastable state.

  5. Central and eastern European activities

    International Nuclear Information System (INIS)

    Rea, J.L.

    1993-01-01

    The Florida State University/Technical University of Budapest environmental research center, Center for Hungarian/American Environmental Research, Studies and Exchanges (CHAERSE), provides a resource base for information and technologies that is used to address near- and long-term environmental problems within the Department of Energy (DOE) complex and in Central and Eastern Europe. The CHAERSE is used as a technology transfer conduit for environmental restoration and waste management (ER/WM) problems and solutions. The International Technology Exchange Division (ITED) used the CHAERSE as one source of information for the identification of international ER/WM technologies being developed in Central and Eastern Europe. This was accomplished by matching high-priority problems in that region to high-priority problems in the DOE Complex; conducting symposia, meetings and workshops with international environmental experts; and identifying innovative technologies

  6. Nuclear power in Eastern Europe

    International Nuclear Information System (INIS)

    Sturm, R.

    1993-01-01

    This paper analyses the operating experience of nuclear power plants in Eastern and Western Europe, the former Soviet Union and the United States to investigate differences in the effects of learning, technical change and the effect of recent political developments. The performance of Soviet-designed reactors compares favourably with Western reactors on the standard performance measures. However, learning curve estimates reveal a disturbing trend: the former Soviet Union and all countries in Eastern Europe experience increasing unplanned losses as plants age, whereas all Western countries reduce their unplanned losses. A similar ''forgetting'' phenomenon is observable for plant availability and there is some evidence that the recent political and economic reorganization have exacerbated this trend. (Author)

  7. Flame spread over inclined electrical wires with AC electric fields

    KAUST Repository

    Lim, Seung J.

    2017-07-21

    Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field applied, the flame spread rate and the flame width of downwardly spreading flames (DSFs) decreased from the horizontal case for −20° ≤ θ < 0° and maintained near constant values for −90° ≤ θ < −20°, while the flame spread rate increased appreciably as the inclination angle of upwardly spreading flames (USFs) increased. When an AC electric field was applied, the behavior of flame spread rate in DSFs (USFs) could be classified into two (three) sub-regimes characterized by various functional dependences on VAC, fAC, and θ. In nearly all cases of DSFs, a globular molten polyethylene formed ahead of the spreading flame edge, occasionally dripping onto the ground. In these cases, an effective flame spread rate was defined to represent the burning rate by measuring the mass loss due to dripping. This effective spread rate was independent of AC frequency, while it decreased linearly with voltage and was independent of the inclination angle. In DSFs, when excessively high voltage and frequency were applied, the dripping led to flame extinction during propagation and the extinction frequency correlated well with applied voltage. In USFs, when high voltage and frequency were applied, multiple globular molten PEs formed at several locations, leading to ejections of multiple small flame segments from the main flame, thereby reducing the flame spread rate, which could be attributed to the electrospray phenomenon.

  8. Genetic structure of little brown bats (Myotis lucifugus) corresponds with spread of white-nose syndrome among hibernacula.

    Science.gov (United States)

    Miller-Butterworth, Cassandra M; Vonhof, Maarten J; Rosenstern, Joel; Turner, Greg G; Russell, Amy L

    2014-01-01

    Until recently, the little brown bat (Myotis lucifugus) was one of the most common bat species in North America. However, this species currently faces a significant threat from the emerging fungal disease white-nose syndrome (WNS). The aims of this study were to examine the population genetic structure of M. lucifugus hibernating colonies in Pennsylvania (PA) and West Virginia (WV), and to determine whether that population structure may have influenced the pattern of spread of WNS. Samples were obtained from 198 individuals from both uninfected and recently infected colonies located at the crest of the disease front. Both mitochondrial (636bp of cytochrome oxidase I) and nuclear (8 microsatellites) loci were examined. Although no substructure was evident from nuclear DNA, female-mediated gene flow was restricted between hibernacula in western PA and the remaining colonies in eastern and central PA and WV. This mitochondrial genetic structure mirrors topographic variation across the region: 3 hibernating colonies located on the western Appalachian plateau were significantly differentiated from colonies located in the central mountainous and eastern lowland regions, suggesting reduced gene flow between these clusters of colonies. Consistent with the hypothesis that WNS is transmitted primarily through bat-to-bat contact, these same 3 hibernating colonies in westernmost PA remained WNS-free for 1-2 years after the disease had swept through the rest of the state, suggesting that female migration patterns may influence the spread of WNS across the landscape.

  9. Spreading and germination of yellow nutsedge (Cyperus esculentus L.) in Hungary.

    Science.gov (United States)

    Hoffmann, Z P; Buzsáki, K; Béres, I

    2006-01-01

    Yellow nutsedge (Cyperus esculentus) is a cosmopolitan, tropical, subtropical plant. On the basis of Ujvarosi life-form it is a G2 perennial plant, overwintering with tubers in the soil. It occurs in all continents: along Eastern and Western coastlines of Africa and even in South-Africa, North and South America, Japan, India, Near-Eastern countries, Western, Southern and Eastern Europe. It has been spread since the 70's in Europe, but its remarkable occurrence was between 1980 and 1995 years. Nowadays it occurs in Germany, the Netherlands, Belgium, France, Portugal, Austria, Croatia, Switzerland, Italy and Hungary among the European countries. The first occurrence of C. esculentus was observed in Hungary in 1993, at the surroundings of Keszthely and H&viz towns in a maize-ecosystem (Dancza 1994). It can be presumed, that its import happened with Gladiolus tubers and seed-grain of maize. At present C. esculentus occurs in four regions and surroundings of 20 habitations of Hungary. Somogy county is the most infected area, where it occurs on 10,000 hectares. C. esculentus took the 16th place in the important order of weeds of the world in the 70's. On the basis of EPPO IAS Panel at present this weed specics is considered as one of the most harmful invasive species of the world, due to its severe economic injury. Most harmful effect of C. esculentus is expressed in spring-sown hoed cultures, mainly in maize. Beside this it also occurs in sunflower, potato and sugarbeet cultures. C. esculentus has a good competitive ability by reducing crop quality and quantity. Vegetative reproduction is dominant in spreading but its propagation by seeds is also presumed in Hungary. Cool, rainy weather favours for the vegetative reproduction, while warm, dry one for the flowering. It has a 1-1.5 mm long fruit with one seed. One clustering can contain 600 seeds. According to Lapham (1985) there are areas in Zimbabwe where one can find 100 million C. esculentus seeds in a hectare. At a 1

  10. Museology History of Eastern Siberia

    Directory of Open Access Journals (Sweden)

    Natalia D. Firer

    2012-08-01

    Full Text Available The article is focused on the aspects of the establishment of the first museums and libraries in Eastern Siberia. The author considers the role of the museum in development of culture and public education in Minusinsk, Yeniseysk, notes the valuable contribution of the activities of merchants and intelligentsia to the museum business, as well as the reflection of the present and past of museums in Siberia.

  11. Eastern Africa Coastal Forest Programme

    OpenAIRE

    Younge, A.

    2002-01-01

    The eastern African coastal forest ecoregion is recognised as one of Africa’s centres of species endemism, and is distributed over six countries (Somalia, Kenya, Tanzania, Mozambique, Zimbabwe and Malawi). Most is found in Kenya, Tanzania and Mozambique, which form our focal region. The coastal forests are fragmented, small and surrounded by poor communities that have a high demand for land and forest resources. Although coastal forests have significant cultural and traditional...

  12. Growth form and distribution of introduced plants in their native and non-native ranges in Eastern Asia and North America

    Science.gov (United States)

    Robert E. Ricklefs; Qinfeng Guo; Hong Qian

    2008-01-01

    There is a growing interest in understanding the influence of plant traits on their ability to spread in non-native regions. Many studies addressing this issue have been based on relatively small areas or restricted taxonomic groups. Here, we analyse a large data base involving 1567 plant species introduced between Eastern Asia and North America or from elsewhere to...

  13. Ex-vessel corium spreading: results from the VULCANO spreading tests

    Energy Technology Data Exchange (ETDEWEB)

    Journeau, Christophe E-mail: christophe.journeau@cea.fr; Boccaccio, Eric E-mail: eric.boccaccio@cea.fr; Brayer, Claude; Cognet, Gerard E-mail: gerard.cognet@cea.fr; Haquet, Jean-Francois E-mail: haquet@eloise.cad.cea.fr; Jegou, Claude E-mail: claude.jegou@cea.fr; Piluso, Pascal E-mail: pascal.piluso@cea.fr; Monerris, Jose E-mail: jose.monerris@cea.fr

    2003-07-01

    In the hypothetical case of a nuclear reactor severe accident, the reactor core could melt and form a mixture, called corium, of highly refractory oxides (UO{sub 2}, ZrO{sub 2}) and metallic or oxidized steel, that could eventually flow out of the vessel and mix with the basemat decomposition products (generally oxides such as SiO{sub 2}, Al{sub 2}O{sub 3}, CaO, Fe{sub 2}O{sub 3}, ...). For some years, the French Atomic Energy Commission (CEA) has launched an R and D program which aimed at providing the tools for improving the mastering of severe accidents. Within this program, the VULCANO experimental facility is operated to perform experiments with prototypic corium (corium of realistic chemical composition including depleted UO{sub 2}). This is coupled with the use of specific high-temperature instrumentation requiring in situ cross calibration. This paper is devoted to the 'spreading experiments' performed in the VULCANO facility, in which the effects of flow and solidification are studied. Due to the complex behavior of corium in the solidification range, an interdisciplinary approach has been used combining thermodynamics of multicomponent mixtures, rheological models of silicic semisolid materials, heat transfer at high temperatures, free-surface flow of a fluid with temperature-dependant properties. Twelve high-temperature spreading tests have been performed and analyzed. The main experimental results are the good spreadability of corium-concrete mixtures having large solidification ranges even with viscous silicic melts, the change of microstructure due to cooling rates, the occurrence of a large thermal contact resistance at the corium-substrate interface, the presence of a steep viscosity gradient at the surface, the transient concrete ablation. Furthermore, the experiments showed the presence of the gaseous inclusions in the melt even without concrete substrate. This gas release is linked to the local oxygen content in the melt which is

  14. A model of spreading of sudden events on social networks

    Science.gov (United States)

    Wu, Jiao; Zheng, Muhua; Zhang, Zi-Ke; Wang, Wei; Gu, Changgui; Liu, Zonghua

    2018-03-01

    Information spreading has been studied for decades, but its underlying mechanism is still under debate, especially for those ones spreading extremely fast through the Internet. By focusing on the information spreading data of six typical events on Sina Weibo, we surprisingly find that the spreading of modern information shows some new features, i.e., either extremely fast or slow, depending on the individual events. To understand its mechanism, we present a susceptible-accepted-recovered model with both information sensitivity and social reinforcement. Numerical simulations show that the model can reproduce the main spreading patterns of the six typical events. By this model, we further reveal that the spreading can be speeded up by increasing either the strength of information sensitivity or social reinforcement. Depending on the transmission probability and information sensitivity, the final accepted size can change from continuous to discontinuous transition when the strength of the social reinforcement is large. Moreover, an edge-based compartmental theory is presented to explain the numerical results. These findings may be of significance on the control of information spreading in modern society.

  15. A review of recent results on spread F theory

    International Nuclear Information System (INIS)

    Ossakow, S.L.

    1979-01-01

    Ionospheric Spread F was discovered some four decades ago. Yet only in the past few years has significant progress been made in the theoretical explanation of such phenomena. In particular, considerable effort has been expended to explain equatorial Spread F and the attendant satellite signal propagation scintillation phenomena. The present review dwells mainly in this low latitude area. The various linear plasma instabilities thought to initiate equatorial Spread F are discussed. Recent theoretical and numerical simulation studies of the nonlinear evolution of the collisional Rayleigh-Taylor instability in equatorial Spread F are reviewed. Also, analytical studies of rising equatorial Spread F bubbles in the collisional and collisionless Rayleigh-Taylor regime are discussed, as well as the nohlinear saturation of instabilities in these two regimes. Current theories on very small scale (< approx 10 meters) size irregularities observed by radar backscatter during equatorial Spread F and their relation to the larger wavelength scintillation causing irregularities are discussed. Application of turbulence theory to equatorial Spread F phenomena is reviewed. Remaining problems to be dealt with at equatorial latitudes are summarized. (Auth.)

  16. Influence of trust in the spreading of information

    Science.gov (United States)

    Wu, Hongrun; Arenas, Alex; Gómez, Sergio

    2017-01-01

    The understanding and prediction of information diffusion processes on networks is a major challenge in network theory with many implications in social sciences. Many theoretical advances occurred due to stochastic spreading models. Nevertheless, these stochastic models overlooked the influence of rational decisions on the outcome of the process. For instance, different levels of trust in acquaintances do play a role in information spreading, and actors may change their spreading decisions during the information diffusion process accordingly. Here, we study an information-spreading model in which the decision to transmit or not is based on trust. We explore the interplay between the propagation of information and the trust dynamics happening on a two-layer multiplex network. Actors' trustable or untrustable states are defined as accumulated cooperation or defection behaviors, respectively, in a Prisoner's Dilemma setup, and they are controlled by a memory span. The propagation of information is abstracted as a threshold model on the information-spreading layer, where the threshold depends on the trustability of agents. The analysis of the model is performed using a tree approximation and validated on homogeneous and heterogeneous networks. The results show that the memory of previous actions has a significant effect on the spreading of information. For example, the less memory that is considered, the higher is the diffusion. Information is highly promoted by the emergence of trustable acquaintances. These results provide insight into the effect of plausible biases on spreading dynamics in a multilevel networked system.

  17. Effects of individual popularity on information spreading in complex networks

    Science.gov (United States)

    Gao, Lei; Li, Ruiqi; Shu, Panpan; Wang, Wei; Gao, Hui; Cai, Shimin

    2018-01-01

    In real world, human activities often exhibit preferential selection mechanism based on the popularity of individuals. However, this mechanism is seldom taken into account by previous studies about spreading dynamics on networks. Thus in this work, an information spreading model is proposed by considering the preferential selection based on individuals' current popularity, which is defined as the number of individuals' cumulative contacts with informed neighbors. A mean-field theory is developed to analyze the spreading model. Through systematically studying the information spreading dynamics on uncorrelated configuration networks as well as real-world networks, we find that the popularity preference has great impacts on the information spreading. On the one hand, the information spreading is facilitated, i.e., a larger final prevalence of information and a smaller outbreak threshold, if nodes with low popularity are preferentially selected. In this situation, the effective contacts between informed nodes and susceptible nodes are increased, and nodes almost have uniform probabilities of obtaining the information. On the other hand, if nodes with high popularity are preferentially selected, the final prevalence of information is reduced, the outbreak threshold is increased, and even the information cannot outbreak. In addition, the heterogeneity of the degree distribution and the structure of real-world networks do not qualitatively affect the results. Our research can provide some theoretical supports for the promotion of spreading such as information, health related behaviors, and new products, etc.

  18. Deterministic ripple-spreading model for complex networks.

    Science.gov (United States)

    Hu, Xiao-Bing; Wang, Ming; Leeson, Mark S; Hines, Evor L; Di Paolo, Ezequiel

    2011-04-01

    This paper proposes a deterministic complex network model, which is inspired by the natural ripple-spreading phenomenon. The motivations and main advantages of the model are the following: (i) The establishment of many real-world networks is a dynamic process, where it is often observed that the influence of a few local events spreads out through nodes, and then largely determines the final network topology. Obviously, this dynamic process involves many spatial and temporal factors. By simulating the natural ripple-spreading process, this paper reports a very natural way to set up a spatial and temporal model for such complex networks. (ii) Existing relevant network models are all stochastic models, i.e., with a given input, they cannot output a unique topology. Differently, the proposed ripple-spreading model can uniquely determine the final network topology, and at the same time, the stochastic feature of complex networks is captured by randomly initializing ripple-spreading related parameters. (iii) The proposed model can use an easily manageable number of ripple-spreading related parameters to precisely describe a network topology, which is more memory efficient when compared with traditional adjacency matrix or similar memory-expensive data structures. (iv) The ripple-spreading model has a very good potential for both extensions and applications.

  19. Two New Epiphyllous Leptolejeunea (Hepaticae: Lejeuneaceae from Eastern Himalaya, India

    Directory of Open Access Journals (Sweden)

    Monalisa Dey

    2010-11-01

    Full Text Available Two new epiphyllous species of the genus Leptolejeunea (Spruce Schiffn., viz. L. mirikana M. Dey et D. K. Singh sp. nov. and L. udarii M. Dey et D. K. Singh sp. nov., are described from Darjeeling district of West Bengal and East district of Sikkim respectively in Eastern Himalaya, India. While, the former is characterized by obovate leaf lobes with acute – subacute leaf apices and entire margin; rectangular – trapezoid underleaves with rectangular – lanceolate lobes which are 3-4 cells long, 2-3 cells wide, or rarely 1 cell wide at apex, and crenulate – denticulate margin; presence of ocelli in female bracts and bracteoles and obconical perianth with truncate apices and 5 obliquely – horizontally spreading horn-like keels extending from apex to 1/2-3/5 of perianth length, the latter is distinct in having small length-breadth ratio of the leaves ranging between 1.2:1-1.3:1; obovate leaf lobes with subacute apices; terminal as well as intercalary androecia with male bracteoles present throughout; numerous ocelli scattered on female bracts, bracteoles and perianth and obconical – campanulate perianth with 5 smooth, erect – obliquely spreading horn-like keels. A key to the Indian species of the genus has been provided.

  20. Did vaccination slow the spread of bluetongue in France?

    Directory of Open Access Journals (Sweden)

    Maryline Pioz

    Full Text Available Vaccination is one of the most efficient ways to control the spread of infectious diseases. Simulations are now widely used to assess how vaccination can limit disease spread as well as mitigate morbidity or mortality in susceptible populations. However, field studies investigating how much vaccines decrease the velocity of epizootic wave-fronts during outbreaks are rare. This study aimed at investigating the effect of vaccination on the propagation of bluetongue, a vector-borne disease of ruminants. We used data from the 2008 bluetongue virus serotype 1 (BTV-1 epizootic of southwest France. As the virus was newly introduced in this area, natural immunity of livestock was absent. This allowed determination of the role of vaccination in changing the velocity of bluetongue spread while accounting for environmental factors that possibly influenced it. The average estimated velocity across the country despite restriction on animal movements was 5.4 km/day, which is very similar to the velocity of spread of the bluetongue virus serotype 8 epizootic in France also estimated in a context of restrictions on animal movements. Vaccination significantly reduced the propagation velocity of BTV-1. In comparison to municipalities with no vaccine coverage, the velocity of BTV-1 spread decreased by 1.7 km/day in municipalities with immunized animals. For the first time, the effect of vaccination has been quantified using data from a real epizootic whilst accounting for environmental factors known to modify the velocity of bluetongue spread. Our findings emphasize the importance of vaccination in limiting disease spread across natural landscape. Finally, environmental factors, specifically those related to vector abundance and activity, were found to be good predictors of the velocity of BTV-1 spread, indicating that these variables need to be adequately accounted for when evaluating the role of vaccination on bluetongue spread.

  1. Lattice model for influenza spreading with spontaneous behavioral changes.

    Science.gov (United States)

    Fierro, Annalisa; Liccardo, Antonella

    2013-01-01

    Individual behavioral response to the spreading of an epidemic plays a crucial role in the progression of the epidemic itself. The risk perception induces individuals to adopt a protective behavior, as for instance reducing their social contacts, adopting more restrictive hygienic measures or undergoing prophylaxis procedures. In this paper, starting with a previously developed lattice-gas SIR model, we construct a coupled behavior-disease model for influenza spreading with spontaneous behavioral changes. The focus is on self-initiated behavioral changes that alter the susceptibility to the disease, without altering the contact patterns among individuals. Three different mechanisms of awareness spreading are analyzed: the local spreading due to the presence in the neighborhood of infective individuals; the global spreading due to the news published by the mass media and to educational campaigns implemented at institutional level; the local spreading occurring through the "thought contagion" among aware and unaware individuals. The peculiarity of the present approach is that the awareness spreading model is calibrated on available data on awareness and concern of the population about the risk of contagion. In particular, the model is validated against the A(H1N1) epidemic outbreak in Italy during the 2009/2010 season, by making use of the awareness data gathered by the behavioral risk factor surveillance system (PASSI). We find that, increasing the accordance between the simulated awareness spreading and the PASSI data on risk perception, the agreement between simulated and experimental epidemiological data improves as well. Furthermore, we show that, within our model, the primary mechanism to reproduce a realistic evolution of the awareness during an epidemic, is the one due to globally available information. This result highlights how crucial is the role of mass media and educational campaigns in influencing the epidemic spreading of infectious diseases.

  2. Lattice model for influenza spreading with spontaneous behavioral changes.

    Directory of Open Access Journals (Sweden)

    Annalisa Fierro

    Full Text Available Individual behavioral response to the spreading of an epidemic plays a crucial role in the progression of the epidemic itself. The risk perception induces individuals to adopt a protective behavior, as for instance reducing their social contacts, adopting more restrictive hygienic measures or undergoing prophylaxis procedures. In this paper, starting with a previously developed lattice-gas SIR model, we construct a coupled behavior-disease model for influenza spreading with spontaneous behavioral changes. The focus is on self-initiated behavioral changes that alter the susceptibility to the disease, without altering the contact patterns among individuals. Three different mechanisms of awareness spreading are analyzed: the local spreading due to the presence in the neighborhood of infective individuals; the global spreading due to the news published by the mass media and to educational campaigns implemented at institutional level; the local spreading occurring through the "thought contagion" among aware and unaware individuals. The peculiarity of the present approach is that the awareness spreading model is calibrated on available data on awareness and concern of the population about the risk of contagion. In particular, the model is validated against the A(H1N1 epidemic outbreak in Italy during the 2009/2010 season, by making use of the awareness data gathered by the behavioral risk factor surveillance system (PASSI. We find that, increasing the accordance between the simulated awareness spreading and the PASSI data on risk perception, the agreement between simulated and experimental epidemiological data improves as well. Furthermore, we show that, within our model, the primary mechanism to reproduce a realistic evolution of the awareness during an epidemic, is the one due to globally available information. This result highlights how crucial is the role of mass media and educational campaigns in influencing the epidemic spreading of infectious

  3. The Coupling of Back-arc Extension, Extrusion and Subduction Dynamics in the Eastern Mediterranean

    Science.gov (United States)

    Capitanio, Fabio A.

    2017-04-01

    Extension in the Aegean Sea and lateral Anatolian extrusion are contrasting and seemingly unrelated examples of continental tectonics In the Eastern Mediterranean. It is acknowledged that these must reconcile with the dynamics of Tethys closure and following continental collision along the convergent margin, however the underlying mechanisms have been difficult to pinpoint, thus far. Three-dimensional numerical modelling of the dynamics of subduction and coupling with the mantle and upper plates allows probing the evolution of similar areas, supporting inferences on the ultimate causes for the continental tectonics. I will present models that reproduce the force balance of subducting slabs' buoyancy, mantle flow and upper plate interiors, and emphasise the role of perturbations in the force balance that may have followed slab breakoff, collision and trench land-locking reconstructed during the oceanic closure in the Eastern Mediterranean. These perturbations lead to a range of different margin motions and strain regimes in the upper plate, from rollback and back-arc spreading, to indentation and extrusion along the collisional margin. Different spatial and temporal fingerprints are illustrated for these processes, and while the trench rollback and back-arc spreading are rather stable features, extrusion is transient. When these regimes overlap, rapid and complex rearrangements of the tectonics in the upper plate are the result. The remarkable similarity between the models' and the Eastern Mediterranean tectonic regimes and geophysical observable allows proposing viable driving mechanisms and support inferences on the Miocene-to-Pliocene evolution of this puzzling area.

  4. CIS/Eastern countries. A curtain raising on eastern Europe

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Slowly and laboriously a new russian petroleum industry is setting in. To illustrate this new scenery, statistical data and maps, giving the production and consumption rates are presented. Two big companies (Shell and B.P.) stand for the privatization of Rosneft, the russian petroleum group. The legal and financial petroleum aspects of Russian are changing but very slowly, attracting the western companies around the petroleum industry. But this interest remains careful. The european bank of investment (BEI) decided to take a financial share in the eastern energy. (A.L.B.)

  5. Dynamics of cell area and force during spreading.

    Science.gov (United States)

    Brill-Karniely, Yifat; Nisenholz, Noam; Rajendran, Kavitha; Dang, Quynh; Krishnan, Ramaswamy; Zemel, Assaf

    2014-12-16

    Experiments on human pulmonary artery endothelial cells are presented to show that cell area and the force exerted on a substrate increase simultaneously, but with different rates during spreading; rapid-force increase systematically occurred several minutes past initial spreading. We examine this theoretically and present three complementary mechanisms that may accompany the development of lamellar stress during spreading and underlie the observed behavior. These include: 1), the dynamics of cytoskeleton assembly at the cell basis; 2), the strengthening of acto-myosin forces in response to the generated lamellar stresses; and 3), the passive strain-stiffening of the cytoskeleton. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Spreading depression analysis of contact behaviour of rats.

    Science.gov (United States)

    Tikal, K

    1977-08-01

    Social contact behaviour induced by spreading cortical depression was studied in rats. The controls looked for and remained in contact, whereas between the rats with spreading cortical depression and their other partners there was no contact. This phenomenon is due mainly to the absence of an active urge for contact. The contact behaviour of rats is evidently controlled by the cerebral cortex or by subcortical areas of the brain which are inhibited after the elicitation of spreading depression. The experiments show that the contact behaviour of rats has at least two components - an active urge for contact and passive tolerance of contact.

  7. Mobile agents affect worm spreading in wireless ad hoc networks

    International Nuclear Information System (INIS)

    Huang, Zi-Gang; Sun, Jin-Tu; Wang, Ying-Hai; Wang, Sheng-Jun; Xu, Xin-Jian

    2009-01-01

    Considering the dynamic nature of portable computing devices with wireless communication capability, an extended model is introduced for worm spreading in the wireless ad hoc network, with a population of mobile agents in a planar distribution, starting from an initial infected seed. The effect of agents' mobility on worm spreading is investigated via extensive Monte Carlo simulations. The threshold behavior and the dynamics of worm epidemics in the wireless networks are greatly affected by both agents' mobility and spatial and temporal correlations. The medium access control mechanism for the wireless communication promotes the sensitivity of the spreading dynamics to agents' mobility

  8. Analysis of pig movements across eastern Indonesia, 2009-2010.

    Science.gov (United States)

    Leslie, Edwina E C; Christley, Robert M; Geong, Maria; Ward, Michael P; Toribio, Jenny-Ann L M L

    2015-03-01

    Knowledge of live animal movement through markets and from farm-to-farm is needed to inform strategies for control of trans-boundary animal diseases (TADs) in south-east Asia, particularly due to consumer preference for fresh meat. In eastern Indonesia a TAD of principal interest for control is classical swine fever (CSF) due to its impacts on smallholder farmers. Pig movement is considered a contributor to failure of current CSF control efforts but pig movement patterns are not well understood. This study investigated movement of live pigs in West Timor, Flores and Sumba islands during 2009-2010, with the aim of informing CSF control policies for Nusa Tenggara Timor province. A market survey of 292 pig sellers and 281 pig buyers across nine live pig markets and a farmer survey across 18 villages with 289 smallholder farmers were conducted and information collected on pig movements. The data obtained was used for social network analysis (SNA) on formal (via a market) and informal (village-to-village) movements using information on trading practices, source and destination locations, and the number of pigs being moved. Both inter- and intra-island movements were identified, however inter-island movement was only observed between Flores and Sumba islands. West Timor and Sumba had highly connected networks where large numbers of villages were directly and indirectly linked through pig movement. Further for West Timor, both formal and informal pig movements linked the capital Kupang, on the eastern end of the island to the western districts bordering East Timor connecting all five districts and demonstrating that informal movement transports pigs over distances similar to formal movement on this island. Sumba had a higher potential for pigs to move to a greater number of sequential locations across the entire island. Flores was found to have a more fragmented network, with pig movements concentrated in its eastern or western regions, influenced by terrain. Markets were

  9. Revisiting Seafloor-Spreading in the Red Sea: Basement Nature, Transforms and Ocean-Continent Boundary

    Science.gov (United States)

    Tapponnier, P.; Dyment, J.; Zinger, M. A.; Franken, D.; Afifi, A. M.; Wyllie, A.; Ali, H. G.; Hanbal, I.

    2013-12-01

    A new marine geophysical survey on the Saudi Arabian side of the Red Sea confirms early inferences that ~ 2/3 of the eastern Red Sea is floored by oceanic crust. Most seismic profiles south of 24°N show a strongly reflective, landward-deepening volcanic basement up to ~ 100 km east of the axial ridge, beneath thick evaporitic deposits. This position of the Ocean-Continent Boundary (OCB) is consistent with gravity measurements. The low amplitudes and long wavelengths of magnetic anomalies older than Chrons 1-3 can be accounted for by low-pass filtering due to thick sediments. Seafloor-spreading throughout the Red Sea started around 15 Ma, as in the western Gulf of Aden. Its onset was coeval with the activation of the Aqaba/Levant transform and short-cutting of the Gulf of Suez. The main difference between the southern and northern Red Sea lies not in the nature of the crust but in the direction and modulus of the plate motion rate. The ~ 30° counterclockwise strike change and halving of the spreading rate (~ 16 to ~ 8 mm/yr) between the Hermil (17°N) and Suez triple junctions results in a shift from slow (≈ North Atlantic) to highly oblique, ultra-slow (≈ Southwest Indian) ridge type. The obliquity of spreading in the central and northern basins is taken up by transform discontinuities that stop ~ 40 km short of the coastline, at the OCB. Three large transform fault systems (Jeddah, Zabargad, El Akhawein) nucleated as continental transfer faults reactivating NNE-trending Proterozoic shear zones. The former two systems divide the Red Sea into three main basins. Between ~15 and ~5 Ma, for about 10 million years, thick evaporites were deposited directly on top of oceanic crust in deep water, as the depositional environment, modulated by climate, became restricted by the Suez and Afar/Bab-el-Mandeb volcano-tectonic 'flood-gates.' The presence of these thick deposits (up to ~ 8 km) suffices to account for the difference between the Red Sea and the Gulf of Aden

  10. A migration-driven model for the historical spread of leprosy in medieval Eastern and Central Europe

    Czech Academy of Sciences Publication Activity Database

    Donoghue, H. D.; Taylor, G. M.; Marcsik, A.; Molnár, E.; Pálfi, G.; Pap, I.; Teschler-Nicola, M.; Pinhasi, R.; Erdal, Y. S.; Velemínský, P.; Likovský, Jakub; Belcastro, M. G.; Mariotti, V.; Riga, A.; Rubini, M.; Zaio, P.; Besra, G. S.; Lee, O. Y.-C.; Wu, H. H.T.; Minnikin, D. E.; Bull, I. D.; O'Grady, J.; Spigelman, M.

    2015-01-01

    Roč. 31, April (2015), s. 250-256 ISSN 1567-1348 Institutional support: RVO:67985912 Keywords : ancient DNA * genotyping * human migrations * lipid biomarkers * Mycobacterium leprae * Mycobacterium tuberculosis Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 2.591, year: 2015

  11. Epidemic spreading in time-varying community networks

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guangming, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [School of Electronic and Information, Guangdong Polytechnic Normal University, Guangzhou 510665 (China); Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2014-06-15

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q{sub c}. The epidemic will survive when q > q{sub c} and die when q < q{sub c}. These results can help understanding the impacts of human travel on the epidemic spreading in complex networks with community structure.

  12. Visual attention spreads broadly but selects information locally.

    Science.gov (United States)

    Shioiri, Satoshi; Honjyo, Hajime; Kashiwase, Yoshiyuki; Matsumiya, Kazumichi; Kuriki, Ichiro

    2016-10-19

    Visual attention spreads over a range around the focus as the spotlight metaphor describes. Spatial spread of attentional enhancement and local selection/inhibition are crucial factors determining the profile of the spatial attention. Enhancement and ignorance/suppression are opposite effects of attention, and appeared to be mutually exclusive. Yet, no unified view of the factors has been provided despite their necessity for understanding the functions of spatial attention. This report provides electroencephalographic and behavioral evidence for the attentional spread at an early stage and selection/inhibition at a later stage of visual processing. Steady state visual evoked potential showed broad spatial tuning whereas the P3 component of the event related potential showed local selection or inhibition of the adjacent areas. Based on these results, we propose a two-stage model of spatial attention with broad spread at an early stage and local selection at a later stage.

  13. Mental representation of tonal spreading in Bemba: Evidence from ...

    African Journals Online (AJOL)

    words. We complement this with an AX discrimination task comparing binary vs ternary spread, which are phonologically contrastive, on the one hand, with a tonally similarly salient but non-phonologically relevant contrast, on the other. We show ...

  14. Epidemic Spreading with Heterogeneous Awareness on Human Networks

    Directory of Open Access Journals (Sweden)

    Yanling Lu

    2017-01-01

    Full Text Available The spontaneous awareness behavioral responses of individuals have a significant impact on epidemic spreading. In this paper, a modified Susceptible-Alert-Infected-Susceptible (SAIS epidemic model with heterogeneous awareness is presented to study epidemic spreading in human networks and the impact of heterogeneous awareness on epidemic dynamics. In this model, when susceptible individuals receive awareness information about the presence of epidemic from their infected neighbor nodes, they will become alert individuals with heterogeneous awareness rate. Theoretical analysis and numerical simulations show that heterogeneous awareness can enhance the epidemic threshold with certain conditions and reduce the scale of virus outbreaks compared with no awareness. What is more, for the same awareness parameter, it also shows that heterogeneous awareness can slow effectively the spreading size and does not delay the arrival time of epidemic spreading peak compared with homogeneous awareness.

  15. Live Cell Imaging of Alphaherpes Virus Anterograde Transport and Spread

    Science.gov (United States)

    Taylor, Matthew P.; Kratchmarov, Radomir; Enquist, Lynn W.

    2013-01-01

    Advances in live cell fluorescence microscopy techniques, as well as the construction of recombinant viral strains that express fluorescent fusion proteins have enabled real-time visualization of transport and spread of alphaherpes virus infection of neurons. The utility of novel fluorescent fusion proteins to viral membrane, tegument, and capsids, in conjunction with live cell imaging, identified viral particle assemblies undergoing transport within axons. Similar tools have been successfully employed for analyses of cell-cell spread of viral particles to quantify the number and diversity of virions transmitted between cells. Importantly, the techniques of live cell imaging of anterograde transport and spread produce a wealth of information including particle transport velocities, distributions of particles, and temporal analyses of protein localization. Alongside classical viral genetic techniques, these methodologies have provided critical insights into important mechanistic questions. In this article we describe in detail the imaging methods that were developed to answer basic questions of alphaherpes virus transport and spread. PMID:23978901

  16. Rumor Spreading Model with Trust Mechanism in Complex Social Networks

    International Nuclear Information System (INIS)

    Wang Ya-Qi; Yang Xiao-Yuan; Han Yi-Liang; Wang Xu-An

    2013-01-01

    In this paper, to study rumor spreading, we propose a novel susceptible-infected-removed (SIR) model by introducing the trust mechanism. We derive mean-field equations that describe the dynamics of the SIR model on homogeneous networks and inhomogeneous networks. Then a steady-state analysis is conducted to investigate the critical threshold and the final size of the rumor spreading. We show that the introduction of trust mechanism reduces the final rumor size and the velocity of rumor spreading, but increases the critical thresholds on both networks. Moreover, the trust mechanism not only greatly reduces the maximum rumor influence, but also postpones the rumor terminal time, which provides us with more time to take measures to control the rumor spreading. The theoretical results are confirmed by sufficient numerical simulations. (interdisciplinary physics and related areas of science and technology)

  17. Rumor Spreading Model with Trust Mechanism in Complex Social Networks

    Science.gov (United States)

    Wang, Ya-Qi; Yang, Xiao-Yuan; Han, Yi-Liang; Wang, Xu-An

    2013-04-01

    In this paper, to study rumor spreading, we propose a novel susceptible-infected-removed (SIR) model by introducing the trust mechanism. We derive mean-field equations that describe the dynamics of the SIR model on homogeneous networks and inhomogeneous networks. Then a steady-state analysis is conducted to investigate the critical threshold and the final size of the rumor spreading. We show that the introduction of trust mechanism reduces the final rumor size and the velocity of rumor spreading, but increases the critical thresholds on both networks. Moreover, the trust mechanism not only greatly reduces the maximum rumor influence, but also postpones the rumor terminal time, which provides us with more time to take measures to control the rumor spreading. The theoretical results are confirmed by sufficient numerical simulations.

  18. Mathematical model for spreading dynamics of social network worms

    International Nuclear Information System (INIS)

    Sun, Xin; Liu, Yan-Heng; Han, Jia-Wei; Liu, Xue-Jie; Li, Bin; Li, Jin

    2012-01-01

    In this paper, a mathematical model for social network worm spreading is presented from the viewpoint of social engineering. This model consists of two submodels. Firstly, a human behavior model based on game theory is suggested for modeling and predicting the expected behaviors of a network user encountering malicious messages. The game situation models the actions of a user under the condition that the system may be infected at the time of opening a malicious message. Secondly, a social network accessing model is proposed to characterize the dynamics of network users, by which the number of online susceptible users can be determined at each time step. Several simulation experiments are carried out on artificial social networks. The results show that (1) the proposed mathematical model can well describe the spreading dynamics of social network worms; (2) weighted network topology greatly affects the spread of worms; (3) worms spread even faster on hybrid social networks

  19. Spreading depolarizations and late secondary insults after traumatic brain injury

    DEFF Research Database (Denmark)

    Hartings, Jed A; Strong, Anthony J; Fabricius, Martin

    2009-01-01

    Here we investigated the incidence of cortical spreading depolarizations (spreading depression and peri-infarct depolarization) after traumatic brain injury (TBI) and their relationship to systemic physiologic values during neurointensive care. Subdural electrode strips were placed on peri......-contusional cortex in 32 patients who underwent surgical treatment for TBI. Prospective electrocorticography was performed during neurointensive care with retrospective analysis of hourly nursing chart data. Recordings were 84 hr (median) per patient and 2,503 hr in total. In 17 patients (53%), 280 spreading...... depolarizations (spreading depressions and peri-infarct depolarizations) were observed. Depolarizations occurred in a bimodal pattern with peak incidence on days 1 and 7. The probability of a depolarization occurring increased significantly as a function of declining mean arterial pressure (MAP; R(2) = 0.78; p...

  20. Epidemic spreading on random surfer networks with infected avoidance strategy

    Science.gov (United States)

    Feng, Yun; Ding, Li; Huang, Yun-Han; Guan, Zhi-Hong

    2016-12-01

    In this paper, we study epidemic spreading on random surfer networks with infected avoidance (IA) strategy. In particular, we consider that susceptible individuals’ moving direction angles are affected by the current location information received from infected individuals through a directed information network. The model is mainly analyzed by discrete-time numerical simulations. The results indicate that the IA strategy can restrain epidemic spreading effectively. However, when long-distance jumps of individuals exist, the IA strategy’s effectiveness on restraining epidemic spreading is heavily reduced. Finally, it is found that the influence of the noises from information transferring process on epidemic spreading is indistinctive. Project supported in part by the National Natural Science Foundation of China (Grant Nos. 61403284, 61272114, 61673303, and 61672112) and the Marine Renewable Energy Special Fund Project of the State Oceanic Administration of China (Grant No. GHME2013JS01).

  1. Flame spread over inclined electrical wires with AC electric fields

    KAUST Repository

    Lim, Seung J.; Park, Sun H.; Park, Jeong; Fujita, Osamu; Keel, Sang I.; Chung, Suk-Ho

    2017-01-01

    Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field

  2. 21 CFR 133.179 - Pasteurized process cheese spread.

    Science.gov (United States)

    2010-04-01

    ..., malt sirup, and hydrolyzed lactose, in a quantity necessary for seasoning. (4) Water. (5) Salt. (6... propionate. (9) Pasteurized process cheese spread in consumer-sized packages may contain lecithin as an...

  3. Simulation spread sheet of Angra-1 secondary circuit

    International Nuclear Information System (INIS)

    Futuro, F.L.; Rucos, J.; Ogando, A.; Maprelian, E.; Bassel, W.S.; Baptista Filho, B.D.

    2000-01-01

    The efficient operation of a Nuclear Power Plant (NPP) requires the continuous identification of derivations in the main operating parameters. The identification and analysis of those derivations allow someone to detect the degradation of instruments or even of any equipment. In order to study this problem the group of thermal generation of Angra 1 NPP, devised the use of a Microsoft Excel spread sheet for the automation of Angra 1 thermal balance. In the set of simulation spread sheets, measured values of the secondary system main parameters were compared with project values for a given reactor power level and condenser pressure. The spread sheets provide the turbines power and efficiency and do the plant thermal balance. This work presents a general description of the spread sheets set and a real case analysis of Angra 1 NPP, showing its precision and use easiness. (author)

  4. Crystal mosaic spread determination by slow neutron scattering

    International Nuclear Information System (INIS)

    Adib, M.; Naguib, K.; Abdel Kawy, A.; Ashry, A.; Abbas, Y.; Wahba, M.; Maayouf, M.A.

    1988-01-01

    A method has been established for determination of the crystal mosaic spread. The method is based on recording all neutron-reflected, under bragg condition, from a certain crystal plane. A computer code was developed especially in order to fit the measured wavelength's distribution of the reflected neutrons with the calculated one, assuming that the crystal mosaic spread has a Gaussian shape. The code accounts for the parameters of the time of flight spectrometer used during the present measurements, as well as divergence of the incident neutron beam. The developed method has been applied for determination of the mosaic spread of both zinc and pyrolytic graphite (P.G.) crystals. The mosaic spread values deduced from the present measurements, are 10'+-6' and 3.60 0 +-0.16 0 respectively for Zn and P.G. crystals

  5. Analyzing Spread of Influence in Social Networks for Transportation Applications

    Science.gov (United States)

    2016-09-02

    This project analyzed the spread of influence in social media, in particular, the Twitter social media site, and identified the individuals who exert the most influence to those they interact with. There are published studies that use social media to...

  6. Analyzing Spread of Influence in Social Networks for Transportation Application.

    Science.gov (United States)

    2016-09-02

    This project analyzed the spread of influence in social media, in particular, the Twitter social media site, and identified the individuals who exert the most influence to those they interact with. There are published studies that use social media to...

  7. Airborne spread of disease--the implications for dentistry.

    Science.gov (United States)

    Harrel, Stephen K

    2004-11-01

    The potential for the airborne spread of disease has been recognized for many years. Recent studies have shown that this mode for disease transmission is capable of spreading a fatal disease such as Severe Acute Respiratory Syndrome over a wide area. Many dental procedures produce extensive aerosols and splatter that are routinely contaminated with bacteria, viruses, and blood. In the past, the potential for these aerosols and splatter to be a vector for disease spread has not been emphasized in dental infection control. Recently published data shows a need to reassess the potential for dental aerosols and splatter to spread disease and the need for their control. Simple and inexpensive methods for the control of dental aerosols and splatter are given. Dental personnel are urged to make the control of aerosols a standard part of their infection control procedures.

  8. Epidemic spreading in time-varying community networks

    International Nuclear Information System (INIS)

    Ren, Guangming; Wang, Xingyuan

    2014-01-01

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q c . The epidemic will survive when q > q c and die when q  c . These results can help understanding the impacts of human travel on the epidemic spreading in complex networks with community structure

  9. Cultural Clues to the Middle Eastern Student

    Science.gov (United States)

    Parker, Orin D.; And Others

    1976-01-01

    Cultural patterns and characteristics of Middle Eastern students indicate their adaptability ease or difficulty in American society. Manners, paternalistic patterns, religion, and social relationships are discussed. (LBH)

  10. Re-membering Eastern Europe

    DEFF Research Database (Denmark)

    Wilken, Lisanne

    2016-01-01

    -Soviet states into the “Eurovision” has been represented and discussed in Britain and Denmark, two countries with their own complex and complicated relationship to "Europe". Taking the cue from a growing scholarly production that argues for the importance of pop culture in the construction of social...... for analysing (political) memory. It then discusses the ways that the “Eastern enlargement” of the Contest in the 1990s triggered discussions of borders and belonging in both a historical and contemporary perspective. Finally the paper zooms in on British and Danish debates of three post-Soviet states; Estonia...

  11. HOMED-Homicides Eastern Denmark

    DEFF Research Database (Denmark)

    Colville-Ebeling, Bonnie; Frisch, Morten; Lynnerup, Niels

    2014-01-01

    Background:An introduction to a forensic medical homicide database established at the Department of Forensic Medicine in Copenhagen. Content: The database contains substantial clinical and demographic data obtained in conjunction with medico-legal autopsies of victims and forensic clinical...... examinations of perpetrators in homicide cases in eastern Denmark. Validity and coverage: The database contains information on all homicide cases investigated at the Department of Forensic Medicine in Copenhagen since 1971. Coverage for the catchment area of the department is assumed to be very good because...

  12. Email networks and the spread of computer viruses

    Science.gov (United States)

    Newman, M. E.; Forrest, Stephanie; Balthrop, Justin

    2002-09-01

    Many computer viruses spread via electronic mail, making use of computer users' email address books as a source for email addresses of new victims. These address books form a directed social network of connections between individuals over which the virus spreads. Here we investigate empirically the structure of this network using data drawn from a large computer installation, and discuss the implications of this structure for the understanding and prevention of computer virus epidemics.

  13. Dynamical interplay between awareness and epidemic spreading in multiplex networks

    OpenAIRE

    Granell, Clara; Gomez, Sergio; Arenas, Alex

    2013-01-01

    We present the analysis of the interrelation between two processes accounting for the spreading of an epidemics, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusiv...

  14. Physical Proximity and Spreading in Dynamic Social Networks

    OpenAIRE

    Stopczynski, Arkadiusz; Pentland, Alex Sandy; Lehmann, Sune

    2015-01-01

    Most infectious diseases spread on a dynamic network of human interactions. Recent studies of social dynamics have provided evidence that spreading patterns may depend strongly on detailed micro-dynamics of the social system. We have recorded every single interaction within a large population, mapping out---for the first time at scale---the complete proximity network for a densely-connected system. Here we show the striking impact of interaction-distance on the network structure and dynamics ...

  15. Predicting Agency Rating Migrations with Spread Implied Ratings

    OpenAIRE

    Jianming Kou; Dr Simone Varotto

    2005-01-01

    Investors traditionally rely on credit ratings to price debt instruments. However, rating agencies are known to be prudent in their approach to rating revisions, which results in delayed ratings adjustments to mutating credit conditions. For a large set of eurobonds we derive credit spread implied ratings and compare them with the ratings issued by rating agencies. Our results indicate that spread implied ratings often anticipate future movement of agency ratings and hence could help track cr...

  16. FACTORS INFLUENCING YIELD SPREADS OF THE MALAYSIAN BONDS

    OpenAIRE

    Norliza Ahmad; Joriah Muhammad; Tajul Ariffin Masron

    2009-01-01

    Malaysian bond market is developing rapidly but not much is understood in terms of macroeconomic factors that could influence the yield spread of the Ringgit Malaysian denominated bonds. Based on a multifactor model, this paper examines the impact of four macroeconomic factors namely: Kuala Lumpur Composite Index (KLCI), Industry Production Index (IPI), Consumer Price Index (CPI) and interest rates (IR) on bond yield spread of the Malaysian Government Securities (MGS) and Corporate Bonds (CBs...

  17. An Overview of Head and Neck Malignancy with Perineural Spread.

    Science.gov (United States)

    Panizza, Benedict J

    2016-04-01

    This article provides an overview of perineural spread of head and neck malignancy. It defines the problem and explores some of the unique features, which occur with this pathology. The expectation is for a better understanding of this extraordinary disease, hopefully leading to earlier diagnosis and for a more consistent reporting of results. It summarizes the topics to be covered in this special edition, which should leave the reader with a fairly complete understanding of the contemporary issues of perineural spread.

  18. Continental collision, gravity spreading, and kinematics of Aegea and Anatolia

    OpenAIRE

    Martinod , Joseph; Hatzfeld , Denis; Brun, , Jean-Pierre; Davy , Philippe; Gautier , Pierre

    2000-01-01

    International audience; We have carried out experiments using a layered medium of sand and silicone to investigate the lateral extrusion of a material which spreads over its own weight while being compressed by the advance of a rigid indenter. Boundary conditions in the box mimic those prevailing in the Anatolian-Aegean system. Both shortening in front of the rigid piston, which models the northward motion of Arabia, and extension resulting from the gravity spreading of the sand-silicone laye...

  19. Spread of H1N1 within Households

    Centers for Disease Control (CDC) Podcasts

    2010-03-29

    This podcast describes an investigation into how H1N1 was spreading within households during the initial days of the pandemic in Texas. CDC's Dr. Oliver Morgan discusses what investigators learned about the role that children played in introducing the virus into households and spreading flu.  Created: 3/29/2010 by Emerging Infectious Diseases.   Date Released: 3/29/2010.

  20. The Real Interest Rate Spread as a Monetary Policy Indicator

    OpenAIRE

    Browne, Frank; Everett, Mary

    2006-01-01

    This paper employs a consumption-based capital asset pricing model to derive the generalised Fisher equation, in order to estimate the natural rate of interest and corresponding real interest rate spread for the US. Analysis reveals not only is the estimated real interest rate spread a useful measure of the degree of looseness/tightness in the Federal Reserve’s monetary policy stance, but also the variable contributes substantially to an understanding of the evolution of US inflation over the...

  1. New PN Even Balanced Sequences for Spread-Spectrum Systems

    Directory of Open Access Journals (Sweden)

    Inácio JAL

    2005-01-01

    Full Text Available A new class of pseudonoise even balanced (PN-EB binary spreading sequences is derived from existing classical odd-length families of maximum-length sequences, such as those proposed by Gold, by appending or inserting one extra-zero element (chip to the original sequences. The incentive to generate large families of PN-EB spreading sequences is motivated by analyzing the spreading effect of these sequences from a natural sampling point of view. From this analysis a new definition for PG is established, from which it becomes clear that very high processing gains (PGs can be achieved in band-limited direct-sequence spread-spectrum (DSSS applications by using spreading sequences with zero mean, given that certain conditions regarding spectral aliasing are met. To obtain large families of even balanced (i.e., equal number of ones and zeros sequences, two design criteria are proposed, namely the ranging criterion (RC and the generating ranging criterion (GRC. PN-EB sequences in the polynomial range are derived using these criteria, and it is shown that they exhibit secondary autocorrelation and cross-correlation peaks comparable to the sequences they are derived from. The methods proposed not only facilitate the generation of large numbers of new PN-EB spreading sequences required for CDMA applications, but simultaneously offer high processing gains and good despreading characteristics in multiuser SS scenarios with band-limited noise and interference spectra. Simulation results are presented to confirm the respective claims made.

  2. Nonlinear model of epidemic spreading in a complex social network.

    Science.gov (United States)

    Kosiński, Robert A; Grabowski, A

    2007-10-01

    The epidemic spreading in a human society is a complex process, which can be described on the basis of a nonlinear mathematical model. In such an approach the complex and hierarchical structure of social network (which has implications for the spreading of pathogens and can be treated as a complex network), can be taken into account. In our model each individual has one of the four permitted states: susceptible, infected, infective, unsusceptible or dead. This refers to the SEIR model used in epidemiology. The state of an individual changes in time, depending on the previous state and the interactions with other individuals. The description of the interpersonal contacts is based on the experimental observations of the social relations in the community. It includes spatial localization of the individuals and hierarchical structure of interpersonal interactions. Numerical simulations were performed for different types of epidemics, giving the progress of a spreading process and typical relationships (e.g. range of epidemic in time, the epidemic curve). The spreading process has a complex and spatially chaotic character. The time dependence of the number of infective individuals shows the nonlinear character of the spreading process. We investigate the influence of the preventive vaccinations on the spreading process. In particular, for a critical value of preventively vaccinated individuals the percolation threshold is observed and the epidemic is suppressed.

  3. Mapping Pn amplitude spreading and attenuation in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory

    2010-12-06

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  4. Modeling universal dynamics of cell spreading on elastic substrates.

    Science.gov (United States)

    Fan, Houfu; Li, Shaofan

    2015-11-01

    A three-dimensional (3D) multiscale moving contact line model is combined with a soft matter cell model to study the universal dynamics of cell spreading over elastic substrates. We have studied both the early stage and the late stage cell spreading by taking into account the actin tension effect. In this work, the cell is modeled as an active nematic droplet, and the substrate is modeled as a St. Venant Kirchhoff elastic medium. A complete 3D simulation of cell spreading has been carried out. The simulation results show that the spreading area versus spreading time at different stages obeys specific power laws, which is in good agreement with experimental data and theoretical prediction reported in the literature. Moreover, the simulation results show that the substrate elasticity may affect force dipole distribution inside the cell. The advantage of this approach is that it combines the hydrodynamics of actin retrograde flow with moving contact line model so that it can naturally include actin tension effect resulting from actin polymerization and actomyosin contraction, and thus it might be capable of simulating complex cellular scale phenomenon, such as cell spreading or even crawling.

  5. Understanding the spreading patterns of mobile phone viruses

    Science.gov (United States)

    Wang, Pu; Gonzalez, Marta; Hidalgo, Cesar; Barabasi, Albert-Laszlo

    2009-03-01

    Mobile viruses are little more than a nuisance today, but given our increased reliance on wireless communication, in the near future they could pose more risk than their PC based counterparts. Despite of the more than three hundred mobile viruses known so far, little is known about their spreading pattern, partly due to a lack of data on the communication and travel patterns of mobile phone users. Starting from the traffic and the communication pattern of six million mobile phone users, we model the vulnerability of mobile communications against potential virus outbreaks. We show that viruses exploiting Bluetooth and multimedia messaging services (MMS) follow markedly different spreading patterns. The Bluetooth virus can reach all susceptible handsets, but spreads relatively slowly, as its spread is driven by human mobility. In contrast, an MMS virus can spread rapidly, but because the underlying social network is fragmented, it can reach only a small fraction of all susceptible users. This difference affects both their spreading rate, the number of infected users, as well as the defense measures one needs to take to protect the system against potential viral outbreak.

  6. Fire spread estimation on forest wildfire using ensemble kalman filter

    Science.gov (United States)

    Syarifah, Wardatus; Apriliani, Erna

    2018-04-01

    Wildfire is one of the most frequent disasters in the world, for example forest wildfire, causing population of forest decrease. Forest wildfire, whether naturally occurring or prescribed, are potential risks for ecosystems and human settlements. These risks can be managed by monitoring the weather, prescribing fires to limit available fuel, and creating firebreaks. With computer simulations we can predict and explore how fires may spread. The model of fire spread on forest wildfire was established to determine the fire properties. The fire spread model is prepared based on the equation of the diffusion reaction model. There are many methods to estimate the spread of fire. The Kalman Filter Ensemble Method is a modified estimation method of the Kalman Filter algorithm that can be used to estimate linear and non-linear system models. In this research will apply Ensemble Kalman Filter (EnKF) method to estimate the spread of fire on forest wildfire. Before applying the EnKF method, the fire spread model will be discreted using finite difference method. At the end, the analysis obtained illustrated by numerical simulation using software. The simulation results show that the Ensemble Kalman Filter method is closer to the system model when the ensemble value is greater, while the covariance value of the system model and the smaller the measurement.

  7. Project finance in Eastern Europe

    International Nuclear Information System (INIS)

    Hart, R.C.

    1993-01-01

    A dysfunctional system of commercial, legal, and financial institutions is the primary problem facing the energy sectors in Eastern Europe. Generally, a major systemic transformation is well underway in the area and is already showing signs of success. The empty promise of export credit financing exerts a significant negative influence on this reform process. The discipline of project finance provides the best, if not the only, basis for financing the modernization of the Eastern European energy sector. An example is given of the Cracow Environmental Project, a modernization project. The power plant is a combined heat and power facility with 460 MW of electric capacity and 1450 MW of thermal energy capacity. Located near the center of Cracow, the plant burns hard coal and provides more than seventy percent of the central district heat consumed in the city. The scope of proposed improvements has changed from the addition of capacity to a combination of modernization and environmental retrofit of the existing plant. The total estimated cost of the improvements program is 150 million dollars. The project consists of three major elements. First, it has proposed and is in the process of restructuring the ownership of the power plant. Second, it is engaged in a major restructuring of the commercial arrangements that govern the operation of the plant. Finally, it is in the late stages of selecting an engineering, procurement, and construction consortium with which it will contract to design and make major improvements to the existing plant

  8. Natural gas in Eastern Europe

    Energy Technology Data Exchange (ETDEWEB)

    Grabarczyk, Ewa; McCallum, Robert; Wergeland, Tor H

    1994-12-31

    The paper is based on Ewa Grabarczyk`s thesis ``The European Gas Market and the Former East Block Countries`` in the Master of International Business Programme at the Norwegian School of Economics and Business Administration. The material of Grabarczyk`s work has been split into two parts; SNF Working Papers Nos. 97/93 and 98/93. Working Paper 97/93 ``The European Gas Markets`` contains an equilibrium model of the European Gas Market employed to investigate some scenarios to the consequences of an integration of the former Soviet Union. Working Paper 98/93 ``Natural Gas in Eastern Europe`` contains descriptions of the energy sectors of former Eastern European countries and an evaluation of the potential future demand for natural gas in these nations. The paper has chapters on each country and sections on reserves, production, exports and markets, transport possibilities and technology, demand and development as well as evaluation of the present situation. 11 figs., 37 tabs., 33 refs

  9. Effect of network topology on the spreading of technologies

    International Nuclear Information System (INIS)

    Kocsis, G.; Kun, F.

    2007-01-01

    Complete text of publication follows. Technological evolution of socio-economic systems has two major components: (i) Innovation New products, ideas, paradigms emerge as a result of innovations which are then tested by the market. (ii) Spreading Successful technologies spread over the system resulting in an overall technological progress. In the present project we study the spreading of new technological achievements, searching for the conditions of technological development. One of the key components of the spreading of successful technologies is the copying, i.e. members of the system adopt technologies used by other individuals according to certain decision mechanisms. Decision making is usually based on a cost-benefit balance so that a technology gets adopted by a large number of individuals if the upgrading provides enough benefits. The gradual adaptation of high level technologies leads to spreading of technologies and an overall technological progress of the socio-economic system. We proposed an agent based model for the spreading process of such technologies in which the interaction of individuals plays a crucial role. Agents of the model use products of different technologies to collaborate with each other which induce costs proportional to the difference of technological levels. Additional costs arise when technologies of different providers are used. Agents can adopt technologies and providers of their interacting partners in order to reduce their costs leading to microscopic rearrangements of the system. Starting from a random configuration of different technological levels a complex time evolution emerges where the spreading of advanced technologies and the overall technological progress of the system are determined by the amount of advantages more advanced technologies provide, and by the structure of the social environment of agents. When technological progress arises, the spreading of technologies in the system can be described by extreme order

  10. Morphology and segmentation of the western Galápagos Spreading Center, 90.5°-98°W: Plume-ridge interaction at an intermediate spreading ridge

    Science.gov (United States)

    Sinton, John; Detrick, Robert; Canales, J. Pablo; Ito, Garrett; Behn, Mark

    2003-12-01

    Complete multibeam bathymetric coverage of the western Galápagos Spreading Center (GSC) between 90.5°W and 98°W reveals the fine-scale morphology, segmentation and influence of the Galápagos hot spot on this intermediate spreading ridge. The western GSC comprises three morphologically defined provinces: A Western Province, located farthest from the Galápagos hot spot west of 95°30'W, is characterized by an axial deep, rift valley morphology with individual, overlapping, E-W striking segments separated by non-transform offsets; A Middle Province, between the propagating rift tips at 93°15'W and 95°30'W, with transitional axial morphology strikes ˜276°; An Eastern Province, closest to the Galápagos hot spot between the ˜90°50'W Galápagos Transform and 93°15'W, with an axial high morphology generally less than 1800 m deep, strikes ˜280°. At a finer scale, the axial region consists of 32 individual segments defined on the basis of smaller, mainly lower overall magma supply and larger offset distance at the latter. The structure of the Eastern Province is complicated by the intersection of a series of volcanic lineaments that appear to radiate away from a point located on the northern edge of the Galápagos platform, close to the southern limit of the Galápagos Fracture Zone. Where these lineaments intersect the GSC, the ridge axis is displaced to the south through a series of overlapping spreading centers (OSCs); abandoned OSC limbs lie even farther south. We propose that southward displacement of the axis is promoted during intermittent times of increased plume activity, when lithospheric zones of weakness become volcanically active. Following cessation of the increased plume activity, the axis straightens by decapitating southernmost OSC limbs during short-lived propagation events. This process contributes to the number of right stepping offsets in the Eastern Province.

  11. AHP 28: Review - Origins and Migrations in the Extended Eastern Himalayas

    Directory of Open Access Journals (Sweden)

    Jack Hayes

    2013-12-01

    Full Text Available This multidisciplinary anthology draws from papers presented at the international conference "Origins and Migrations Among TibetoBurman-Speakers of the Extended Eastern Himalaya" held at Humboldt University, Berlin in 2008. This collection of articles contributes to discussions surrounding the nature of and questions surrounding data, hypotheses, and theories of origins and migration in the 'extended Eastern Himalaya'. This region includes the hill peoples and territory ranging from eastern Nepal to runachal Pradesh, Nagaland, upland Southeast Asia and southwest China. Although there is some thematic overlap among the fourteen essays, they are quite a diverse lot, critically examining local and regional history, theoretical and methodological issues writ large, myths and rituals, society and social narrative, language and linguistic relationships, identity formation, and local-state dynamics related to local ideas about origins and migration. This book is particularly useful for gaining a better understanding of the issues linked to topics and theories of identity in the Eastern Himalaya (and wider Himalaya region more broadly considering the core importance of 'origins' in any construction or reconstruction of identity among diverse and idely spread communities. Graduate students and specialists interested in the Himalayan region will find this book useful. Individual chapters, especially the more theory-oriented ones, are also well suited for undergraduate courses.

  12. Uncovered Interest Parity in Central and Eastern Europe: Convergence and the Global Financial Crisis

    Directory of Open Access Journals (Sweden)

    Fabio Filipozzi

    2012-12-01

    Full Text Available This paper presents tests of uncovered interest parity in Croatia, the Czech Republic, Hungary, Poland and Romania; all countries in Central and Eastern Europe with floating exchange rates. Data are monthly and the trading horizon is three months. The estimations show that the UIP hypothesis is rejected for the full sample from 1999 to 2011 for all five countries. A number of reasons for the rejection were investigated. Rolling regressions show that standard versions of the UIP essentially lose all explanatory power in 2008-10, which was a period in which the global financial crisis led to instability in currency and interest markets in Central and Eastern Europe. Two indicators of global risk aversion were also found to enter significantly in the many UIP estimations. Finally, the size of the interest rates spread also seems to be of importance, at least for Poland and Romania

  13. An analytical study of the improved nonlinear tolerance of DFT-spread OFDM and its unitary-spread OFDM generalization.

    Science.gov (United States)

    Shulkind, Gal; Nazarathy, Moshe

    2012-11-05

    DFT-spread (DFT-S) coherent optical OFDM was numerically and experimentally shown to provide improved nonlinear tolerance over an optically amplified dispersion uncompensated fiber link, relative to both conventional coherent OFDM and single-carrier transmission. Here we provide an analytic model rigorously accounting for this numerical result and precisely predicting the optimal bandwidth per DFT-S sub-band (or equivalently the optimal number of sub-bands per optical channel) required in order to maximize the link non-linear tolerance (NLT). The NLT advantage of DFT-S OFDM is traced to the particular statistical dependency introduced among the OFDM sub-carriers by means of the DFT spreading operation. We further extend DFT-S to a unitary-spread generalized modulation format which includes as special cases the DFT-S scheme as well as a new format which we refer to as wavelet-spread (WAV-S) OFDM, replacing the spreading DFTs by Hadamard matrices which have elements +/-1 hence are multiplier-free. The extra complexity incurred in the spreading operation is almost negligible, however the performance improvement with WAV-S relative to plain OFDM is more modest than that achieved by DFT-S, which remains the preferred format for nonlinear tolerance improvement, outperforming both plain OFDM and single-carrier schemes.

  14. 76 FR 28210 - Eastern Arizona Counties Resource Advisory Committee

    Science.gov (United States)

    2011-05-16

    ... DEPARTMENT OF AGRICULTURE Forest Service Eastern Arizona Counties Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Eastern Arizona Counties will meet...: Julia Faith Rivera, RAC Program Manager, Eastern Arizona Counties Resource Advisory Committee, Apache...

  15. 76 FR 41755 - Eastern Arizona Counties Resource Advisory; Meeting

    Science.gov (United States)

    2011-07-15

    ... DEPARTMENT OF AGRICULTURE Forest Service Eastern Arizona Counties Resource Advisory; Meeting AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Eastern Arizona Counties Resource... FURTHER INFORMATION CONTACT: Julia Faith Rivera, RAC Program Manager, Eastern Arizona Counties Resource...

  16. Old age mortality in Eastern and South-Eastern Asia

    Directory of Open Access Journals (Sweden)

    Danan Gu

    2013-11-01

    Full Text Available Background: Eastern and South-Eastern Asian countries have witnessed a marked decline in old age mortality in recent decades. Yet no studies have investigated the trends and patterns in old age morality and cause-of-death in the region. Objective: We reviewed the trends and patterns of old age mortality and cause-of-death for countries in the region. Methods: We examined data on old age mortality in terms of life expectancy at age 65 and age-specific death rates from the 2012 Revision of the World Population Prospects for 14 countries in the region (China, Hong Kong, Democratic People's Republic of Korea, Indonesia, Japan, Lao People's Democratic Republic, Myanmar, Malaysia, Mongolia, Philippines, Republic of Korea, Singapore, Thailand, and Viet Nam and data on cause-of-death from the WHO for five countries (China, Hong Kong, Japan, Republic of Korea, and Singapore from 1980 to 2010. Results: While mortality transitions in these populations took place in different times, and at different levels of socioeconomic development and living environment, changes in their age patterns and sex differentials in mortality showed certain similarities: women witnessed a similar decline to men in spite of their lower mortality, and young elders had a larger decline than the oldest-old. In all five countries examined for cause-of-death, most of the increases in life expectancy at age 65 in both men and women were attributable to declines in mortality from stroke and heart disease. GDP per capita, educational level, and urbanization explained much of the variations in life expectancy and cause-specific mortality, indicating critical contributions of these basic socioeconomic development indicators to the mortality decline over time in the region. Conclusions: These findings shed light on the relationship between epidemiological transition, changing age patterns of mortality, and improving life expectancy in these populations.

  17. Simulation of melt spreading in consideration of phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Spengler, C. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Koeln (Germany)

    2002-07-01

    The analysis of melt spreading and relocation phenomena in the containment of LWR power plants in case of hypothetical severe accidents leading to core melting is an important issue for reactor safety investigations. For the simulation of melt spreading the code LAVA has been developed on the basis of a method from the related subject of volcanology by adding more detailed models for heat transfer phenomena and flow rheology. The development is supported by basic analysis of the spreading of gravity currents as well as experimental investigations of the rheology of solidifying melts. These exhibit strong non-Newtonian effects in case of a high content of solids in the freezing melt. The basic model assumption in LAVA is the ideal Bingham plastic approach to the non-Newtonian, shear-thinning characteristic of solidifying melts. For the recalculation of melt spreading experiments, the temperature-dependent material properties for solidifying melt mixtures have been calculated using correlations from the literature. With the parameters and correlations for the rheological material properties approached by results from literature, it was possible to recalculate successfully recent spreading experiments with simulant materials and prototypic reactor core materials. An application to the behaviour of core melt in the reactor cavity assumed a borderline case for the issue of spreading. This limit is represented by melt conditions (large solid fraction, low volume flux), under which the melt is hardly spreadable. Due to the persistent volume flux the reactor cavity is completely, but inhomogeneously filled with melt. The degree of inhomogeneity is rather small, so it is concluded, that for the long-term coolability of a melt pool in narrow cavities the spreading of melt will probably have only negligible influence. (orig.)

  18. Epidemiological models for the spread of anti-malarial resistance

    Directory of Open Access Journals (Sweden)

    Antia R

    2003-02-01

    Full Text Available Abstract Background The spread of drug resistance is making malaria control increasingly difficult. Mathematical models for the transmission dynamics of drug sensitive and resistant strains can be a useful tool to help to understand the factors that influence the spread of drug resistance, and they can therefore help in the design of rational strategies for the control of drug resistance. Methods We present an epidemiological framework to investigate the spread of anti-malarial resistance. Several mathematical models, based on the familiar Macdonald-Ross model of malaria transmission, enable us to examine the processes and parameters that are critical in determining the spread of resistance. Results In our simplest model, resistance does not spread if the fraction of infected individuals treated is less than a threshold value; if drug treatment exceeds this threshold, resistance will eventually become fixed in the population. The threshold value is determined only by the rates of infection and the infectious periods of resistant and sensitive parasites in untreated and treated hosts, whereas the intensity of transmission has no influence on the threshold value. In more complex models, where hosts can be infected by multiple parasite strains or where treatment varies spatially, resistance is generally not fixed, but rather some level of sensitivity is often maintained in the population. Conclusions The models developed in this paper are a first step in understanding the epidemiology of anti-malarial resistance and evaluating strategies to reduce the spread of resistance. However, specific recommendations for the management of resistance need to wait until we have more data on the critical parameters underlying the spread of resistance: drug use, spatial variability of treatment and parasite migration among areas, and perhaps most importantly, cost of resistance.

  19. Process contributions to the intermodel spread in amplified Arctic warming

    Science.gov (United States)

    Boeke, R.; Taylor, P. C.

    2016-12-01

    The Arctic is warming at a rate more than twice the global average. This robust climate system response to an external forcing is referred to as Arctic Amplification (AA). While Coupled Model Intercomparison Project 5 (CMIP5) climate models simulate AA, the largest intermodel spread in projected warming is also found in the Arctic. Quantifying the amount of polar warming relative to global warming influences how society adapts to climate change; a 2°C increase in global mean temperature would result in a polar warming between 4-8°C according to the intermodel spread in CMIP5 simulations. A trove of previous work has considered AA diagnostically using variations in the surface energy budget to attribute the intermodel spread in AA to an assortment of feedbacks—surface albedo, cloud, surface turbulent flux, and atmospheric and oceanic energy transport. We consider a systems-thinking approach treating AA as a process that evolves over time. We hypothesize that two specific components of the AA process are most important and influence the intermodel spread. (1) The inability of the Arctic system to effectively remove excess heat sourced from natural variability. The change in the efficiency of the `Arctic air conditioner' is thought to be due to thinner and less extensive sea ice and the resulting ice albedo feedback. (2) The process through which energy is stored in the ocean and exchanged with the atmosphere within the context of the sea ice annual cycle is also important. This study uses CMIP5 simulations from the historical and RCP8.5 (Representative Concentration Pathway; an emission scenario with forcing increasing to 8.5 W m-2 by 2100) to analyze how the AA process operates in present and future climate. The intermodel spread in these processes and the influence on the spread in AA are discussed. This approach identifies models that more realistically simulate the AA process and will aid in narrowing intermodel spread in Arctic surface temperature

  20. Babesia microti infection, eastern Pennsylvania, USA.

    Science.gov (United States)

    Acosta, Marcela E Perez; Ender, Peter T; Smith, Erin M; Jahre, Jeffrey A

    2013-07-01

    Infection with Babesia microti has not been well-described in eastern Pennsylvania, USA, despite the vector of this organism being prevalent. We report 3 cases of babesiosis in eastern Pennsylvania in persons without recent travel outside the region or history of blood transfusions, suggesting emergence of this infection.

  1. Eastern Africa Social Science Research Review

    African Journals Online (AJOL)

    The Eastern Africa Social Science Research Review (EASSRR) is a bi-annual journal published by the Organization for Social Science Research in Eastern Africa (OSSREA). Since the publication of its maiden ... Emerging regions in Ethiopia: are they catching up with the rest of Ethiopia? EMAIL FULL TEXT EMAIL FULL ...

  2. tive conflict resolution mechanism in eastern Ethiopia

    African Journals Online (AJOL)

    eastern Ethiopia: The case of the Ittu ... The study was conducted in eastern Ethiopia where the Somali and ... Zigale Tamir Tenaw is assistant professor in the Department of Gender and Development ..... regional state in collaboration with the local people – aggravate the already ..... Resource Based Conflict Network,.

  3. Using a network model to assess risk of forest pest spread via recreational travel.

    Directory of Open Access Journals (Sweden)

    Frank H Koch

    Full Text Available Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spread of alien species. One pathway of concern in North America is the possible spread of forest pests in firewood carried by visitors to campgrounds or recreational facilities. We present a network model depicting the movement of campers and, by extension, potentially infested firewood. We constructed the model from US National Recreation Reservation Service data documenting more than seven million visitor reservations (including visitors from Canada at campgrounds nationwide. This bi-directional model can be used to identify likely origin and destination locations for a camper-transported pest. To support broad-scale decision making, we used the model to generate summary maps for 48 US states and seven Canadian provinces that depict the most likely origins of campers traveling from outside the target state or province. The maps generally showed one of two basic spatial patterns of out-of-state (or out-of-province origin risk. In the eastern United States, the riskiest out-of-state origin locations were usually found in a localized region restricted to portions of adjacent states. In the western United States, the riskiest out-of-state origin locations were typically associated with major urban areas located far from the state of interest. A few states and the Canadian provinces showed characteristics of both patterns. These model outputs can guide deployment of resources for surveillance, firewood inspections, or other activities. Significantly, the contrasting map patterns indicate that no single response strategy is appropriate for all states and provinces. If most out-of-state campers are traveling from distant areas, it may be effective to deploy resources at key points along major roads (e.g., interstate highways, since these locations could effectively represent bottlenecks of camper movement. If most campers are from nearby areas, they may

  4. Properly pricing country risk: a model for pricing long-term fundamental risk applied to central and eastern European countries

    Directory of Open Access Journals (Sweden)

    Debora Revoltella

    2010-09-01

    Full Text Available The private sector has used proxies such as sovereign credit ratings, spreads on sovereign bonds and spreads on sovereign credit default swaps (CDS to gauge country risk, even though these measures are pricing the risk of default of government bonds, which is different from the risks facing private participants in cross-border financing. Under normal market conditions, the CDS spreads are a very useful source of information on country risk. However, the recent crisis has shown that the CDS spreads might lead to some underpricing or overpricing of fundamentals in the case of excessively low or excessively high risk aversion. In this paper we develop an alternative measure of country risk that extracts the volatile, short-term market sentiment component from the sover eign CDS spread in order to improve its reliability in periods of market distress. We show that adverse market sentiment was a key driver of the sharp increase in sovereign CDS spreads of central and eastern European (CEE countries during the most severe phase of the crisis. We also show that our measure of country risk sheds some light on the observed stability of cross-border bank flows to CEE banks during the crisis.

  5. Lichens of neglected habitats in Eastern and East-Central European lowlands

    Directory of Open Access Journals (Sweden)

    Jurga Motiejūnaitē

    2013-12-01

    Full Text Available Situation of lichens of aquatic and transient habitats in Eastern and East-Central European lowlands is discussed basing on example of several selected species: Leptogium biatorinum, Sarcosagium campestre, Steinia geophana, Verrucaria aquatilis, V. hydrela, V. praetermissa, V. xyloxena. Both habitat types are generally very much neglected in the region and all species show large spatial gaps in recording, which makes it difficult to judge both about their true distribution limits and spreading dynamics. On the other hand, targeted search through the suitable habitats and abundance of such indicate that many of these lichens are probably not uncommon in the region.

  6. Paleogene plate tectonic evolution of the Arabian and Eastern Somali basins

    Digital Repository Service at National Institute of Oceanography (India)

    Royer, J.-Y.; Chaubey, A.K.; Dyment, J.; Bhattacharya, G.C.; Srinivas, K.; Yatheesh, V.; Ramprasad, T.

    with systemahyphenminus tic ridge propagation in both basins (Miles & Roest 1993: Chaubey er at. 1998. Dyment 1998). Ridge propagation explains the large spreading asymmetry between the Arabian and Eastern Somali basins. Between Chrons 26 and 25. c. 65% of the crust..., the differences be- tween the India-Somalia and Capricorn-Somalia motions in Paleogene time can be used to estimate and refine the Capricorn-India integral motion as suggested by Royer & Chang (1991). Such en- deavour would require an accurate assessment...

  7. Mesquite Risk Mapping and Assessment in Tokar Delta-Eastern Sudan

    OpenAIRE

    Suliman, Mahgoub; NAWATA, Hiroshi; Hoshino, Buho; Karamalla, Abdelaziz

    2015-01-01

    Tokar Delta is a name given to a small delta of approximately 161,000 hectares situated in the southern area of the Red Sea in Eastern Sudan. Beginning of 1980, mesquite species (Prosopis chilensis & Prosopis juliflora) were introduced to Tokar area to be planted as a shelterbelt for the city Tokar, but after while; it spread out to the delta area and became an invasive plant to the agricultural lands and along Khor Barak banks. Nowadays mesquite covers more than half of the delta area, decre...

  8. Migration in relation to possible tectonic and regional controls in eastern Australian volcanism

    International Nuclear Information System (INIS)

    Sutherland, F.L.

    1981-01-01

    The Wellman-McDougall model for southward migration of central volcano activity in eastern Australia is extended to the basaltic lava provinces. Latitude-age plots of volcanic episodes are related to trails initiated from regions of active volcanism at the commencement of northward drift of Australia (53 m.y. B.P.), from Southern Ocean spreading. These trails intersect at least 75%, and possibly up to 95%, of basaltic episodes and suggest a migratory control. The migration of central volcano felsic activity, however, consistently exceeds sea-floor spreading rates with a relative southward motion of 4-10 mm/yr. The trails give a mean migration direction of 24 PM 9 0 W of S before 29-30 m.y., but 8-12 0 W of S after 29 m.y. (orig./ME)

  9. Active spreading processes at ultraslow mid-ocean ridges: The 1999-2001 seismo-volcanic episode at 85°E Gakkel ridge, Arctic Ocean

    Science.gov (United States)

    Schlindwein, Vera; Riedel, Carsten; Korger, Edith; Läderach, Christine

    2010-05-01

    The rate of magma and crustal production at mid-ocean ridges is thought to decrease with decreasing spreading rate. At ultraslow spreading rates below 10-20 mm/y full rate, heat loss by conduction greatly reduces melt production with less melt produced at increasingly greater depths. Gakkel Ridge, the actively spreading mid-ocean ridge in the Arctic Ocean, opens at rates of 14 mm/y in the west decreasing to less than 6 mm/y at its eastern termination and demonstrates that magma production is not only a function of spreading rate. Whereas amagmatic spreading takes place at rates of about 12-10 mm/y, focussed melt production occurs at even lower spreading rates in long-lived discrete volcanic centres. One such centre is the 85°E volcanic complex at eastern Gakkel ridge where in 1999 a teleseismically recorded earthquake swarm consisting of more than 250 earthquakes over 9 months signalled the onset of an active spreading episode. The earthquake swarm is believed to be associated with volcanic activity although no concurrent lava effusion was found. We analysed the teleseismic earthquake swarm together with visual observation and microseismic data recorded at this site in 2001 and 2007 and noted the following characteristics which may be indicative for volcanic spreading events at the still poorly explored ultraslow spreading ridges: - unusual duration: The 1999 earthquake swarm lasted over 9 months rather than a few weeks as observed on faster spreading ridges. In addition, in 2001 seismoacoustic sounds which we interpret as gas discharge in Strombolian eruptions and a giant event plume maintained over more than one year indicate waxing and waning volcanic activity since 1999. - unusual strength: The earthquake swarm was detected at teleseismic distances of more than 1000 km and included 11 events with a magnitude >5. No other confirmed mid-ocean ridge eruption released a comparable seismic moment. Rather than focussing in a narrow area or showing pronounced

  10. Epidemic spreading on dual-structure networks with mobile agents

    Science.gov (United States)

    Yao, Yiyang; Zhou, Yinzuo

    2017-02-01

    The rapid development of modern society continually transforms the social structure which leads to an increasingly distinct dual structure of higher population density in urban areas and lower density in rural areas. Such structure may induce distinctive spreading behavior of epidemics which does not happen in a single type structure. In this paper, we study the epidemic spreading of mobile agents on dual structure networks based on SIRS model. First, beyond the well known epidemic threshold for generic epidemic model that when the infection rate is below the threshold a pertinent infectious disease will die out, we find the other epidemic threshold which appears when the infection rate of a disease is relatively high. This feature of two thresholds for the SIRS model may lead to the elimination of infectious disease when social network has either high population density or low population density. Interestingly, however, we find that when a high density area is connected to a low density may cause persistent spreading of the infectious disease, even though the same disease will die out when it spreads in each single area. This phenomenon indicates the critical role of the connection between the two areas which could radically change the behavior of spreading dynamics. Our findings, therefore, provide new understanding of epidemiology pertinent to the characteristic modern social structure and have potential to develop controlling strategies accordingly.

  11. Suppressing epidemic spreading in multiplex networks with social-support

    Science.gov (United States)

    Chen, Xiaolong; Wang, Ruijie; Tang, Ming; Cai, Shimin; Stanley, H. Eugene; Braunstein, Lidia A.

    2018-01-01

    Although suppressing the spread of a disease is usually achieved by investing in public resources, in the real world only a small percentage of the population have access to government assistance when there is an outbreak, and most must rely on resources from family or friends. We study the dynamics of disease spreading in social-contact multiplex networks when the recovery of infected nodes depends on resources from healthy neighbors in the social layer. We investigate how degree heterogeneity affects the spreading dynamics. Using theoretical analysis and simulations we find that degree heterogeneity promotes disease spreading. The phase transition of the infected density is hybrid and increases smoothly from zero to a finite small value at the first invasion threshold and then suddenly jumps at the second invasion threshold. We also find a hysteresis loop in the transition of the infected density. We further investigate how an overlap in the edges between two layers affects the spreading dynamics. We find that when the amount of overlap is smaller than a critical value the phase transition is hybrid and there is a hysteresis loop, otherwise the phase transition is continuous and the hysteresis loop vanishes. In addition, the edge overlap allows an epidemic outbreak when the transmission rate is below the first invasion threshold, but suppresses any explosive transition when the transmission rate is above the first invasion threshold.

  12. An empirical model of global spread-f occurrence

    International Nuclear Information System (INIS)

    Singleton, D.G.

    1974-09-01

    A method of combining models of ionospheric F-layer peak electron density and irregularity incremental electron density into a model of the occurrence probability of the frequency spreading component of spread-F is presented. The predictions of the model are compared with spread-F occurrence data obtained under sunspot maximum conditions. Good agreement is obtained for latitudes less than 70 0 geomagnetic. At higher latitudes, the inclusion of a 'blackout factor' in the model allows it to accurately represent the data and, in so doing, resolves an apparent discrepancy in the occurrence statistics at high latitudes. The blackout factor is ascribed to the effect of polar blackout on the spread-F statistics and/or the lack of a definitve incremental electron density model for irregularities at polar latitudes. Ways of isolating these effects and assessing their relative importance in the blackout factor are discussed. The model, besides providing estimates of spread-F occurrence on a worldwide basis, which will be of value in the engineering of HF and VHF communications, also furnishes a means of further checking the irregularity incremental electron density model on which it is based. (author)

  13. Generation and reception of spread-spectrum signals

    Science.gov (United States)

    Moser, R.

    1983-05-01

    The term 'spread-spectrum' implies a technique whereby digitized information is added to a pseudo-random number sequence and the resultant bit stream changes some parameter of the carrier frequency in discrete increments. The discrete modulation of the carrier frequency is usually realized either as a multiple level phase shift keyed or frequency shift keyed signal. The resultant PSK-modulated frequency spectrum is referred to as direct sequence spread-spectrum, whereas the FSK-modulated carrier frequency is referred to as a frequency hopped spread spectrum. These can be considered the major subsets of the more general term 'spread-spectrum'. In discussing signal reception, it is pointed out that active correlation methods are used for channel synchronization when the psuedo random sequences are long or when the processing gain is large, whereas the passive methods may be used for either short pseudo-random noise generation codes or to assist in attaining initial synchronization in long sequence spread-spectrum systems.

  14. Explosive spreading on complex networks: The role of synergy.

    Science.gov (United States)

    Liu, Quan-Hui; Wang, Wei; Tang, Ming; Zhou, Tao; Lai, Ying-Cheng

    2017-04-01

    In spite of the vast literature on spreading dynamics on complex networks, the role of local synergy, i.e., the interaction of elements that when combined produce a total effect greater than the sum of the individual elements, has been studied but only for irreversible spreading dynamics. Reversible spreading dynamics are ubiquitous but their interplay with synergy has remained unknown. To fill this knowledge gap, we articulate a model to incorporate local synergistic effect into the classical susceptible-infected-susceptible process, in which the probability for a susceptible node to become infected through an infected neighbor is enhanced when the neighborhood of the latter contains a number of infected nodes. We derive master equations incorporating the synergistic effect, with predictions that agree well with the numerical results. A striking finding is that when a parameter characterizing the strength of the synergy reinforcement effect is above a critical value, the steady-state density of the infected nodes versus the basic transmission rate exhibits an explosively increasing behavior and a hysteresis loop emerges. In fact, increasing the synergy strength can promote the spreading and reduce the invasion and persistence thresholds of the hysteresis loop. A physical understanding of the synergy promoting explosive spreading and the associated hysteresis behavior can be obtained through a mean-field analysis.

  15. Spread-sheet application to classify radioactive material for shipment

    International Nuclear Information System (INIS)

    Brown, A.N.

    1998-01-01

    A spread-sheet application has been developed at the Idaho National Engineering and Environmental Laboratory to aid the shipper when classifying nuclide mixtures of normal form, radioactive materials. The results generated by this spread-sheet are used to confirm the proper US DOT classification when offering radioactive material packages for transport. The user must input to the spread-sheet the mass of the material being classified, the physical form (liquid or not) and the activity of each regulated nuclide. The spread-sheet uses these inputs to calculate two general values: 1)the specific activity of the material and a summation calculation of the nuclide content. The specific activity is used to determine if the material exceeds the DOT minimal threshold for a radioactive material. If the material is calculated to be radioactive, the specific activity is also used to determine if the material meets the activity requirement for one of the three low specific activity designations (LSA-I, LSA-II, LSA-III, or not LSA). Again, if the material is calculated to be radioactive, the summation calculation is then used to determine which activity category the material will meet (Limited Quantity, Type A, Type B, or Highway Route Controlled Quantity). This spread-sheet has proven to be an invaluable aid for shippers of radioactive materials at the Idaho National Engineering and Environmental Laboratory. (authors)

  16. Dynamical Behaviors of Rumor Spreading Model with Control Measures

    Directory of Open Access Journals (Sweden)

    Xia-Xia Zhao

    2014-01-01

    Full Text Available Rumor has no basis in fact and flies around. And in general, it is propagated for a certain motivation, either for business, economy, or pleasure. It is found that the web does expose us to more rumor and increase the speed of the rumors spread. Corresponding to these new ways of spreading, the government should carry out some measures, such as issuing message by media, punishing the principal spreader, and enhancing management of the internet. In order to assess these measures, dynamical models without and with control measures are established. Firstly, for two models, equilibria and the basic reproduction number of models are discussed. More importantly, numerical simulation is implemented to assess control measures of rumor spread between individuals-to-individuals and medium-to-individuals. Finally, it is found that the amount of message released by government has the greatest influence on the rumor spread. The reliability of government and the cognizance ability of the public are more important. Besides that, monitoring the internet to prevent the spread of rumor is more important than deleting messages in media which already existed. Moreover, when the minority of people are punished, the control effect is obvious.

  17. Ionosonde observations of daytime spread F at low latitudes

    Science.gov (United States)

    Jiang, Chunhua; Yang, Guobin; Liu, Jing; Yokoyama, Tatsuhiro; Komolmis, Tharadol; Song, Huan; Lan, Ting; Zhou, Chen; Zhang, Yuannong; Zhao, Zhengyu

    2016-12-01

    Spread F on ionograms has been considered to be a phenomenon mainly occurred at nighttime. This study presented a case study of daytime spread F observed by the ionosonde installed at Puer (PUR; 22.7°N, 101.05°E; dip latitude 12.9°N), where daytime spread F that lasted for more than 2 h (about 08:30 LT 10:45 LT) was observed on 14 November 2015. To investigate the possible mechanism, ionograms recorded at PUR and Chiang Mai (18.76°N, 98.93°E; dip latitude 9.04°N) were used in this study. We found that traveling ionospheric disturbances were observed before the occurrence of daytime spread F. Meanwhile, the movement of the peak height of the ionosphere was downward. We suggested that downward vertical neutral winds excited by traveling atmospheric disturbances/atmospheric gravity waves might play a significant role in forming daytime spread F over PUR during geomagnetic storms.

  18. Drop spreading and penetration into pre-wetted powders

    KAUST Repository

    Marston, Jeremy

    2013-05-01

    We present results from an experimental study of the impact of liquid drops onto powder beds which are pre-wetted with the impacting liquid. Using high-speed video imaging, we study both the dynamics of the initial spreading regime and drainage times once the drop has reached its maximum spread on the surface. During the initial spreading stage, we compare our experimental data to a previously developed model which incorporates imbibition into the spreading dynamics and observe reasonable agreement. We find that the maximum spread is a strong function of the moisture content in the powder bed and that the total time from impact to complete drainage is always shorter than that for dry powder. Our results indicate that there is an optimum moisture content (or saturation) which leads to the fastest penetration. We use simple scaling arguments which also identify an optimum moisture content for fastest penetration, which agrees very well with the experimental result. © 2013 Elsevier B.V.

  19. [SPREADING OF NCTC CLONE 929 CELLS AFTER RESEEDING].

    Science.gov (United States)

    Petrov, Yu P; Negulyaev, Yu A; Tsupkina, N V

    2015-01-01

    The period (1 h after reseeding) of behaviour of mouse NCTC clone 929 cells to the conditions of artificial cultivation was studied. The time-lapse imaging followed the processing of the cells with ImageJ program was applied. To characterize the parametres cell status we used the cell area (projection of the cell on substrate) and Rp/Ra ratio introduced earlier as a spreading coefficient (Kuz'minykh, Petrov, 2004). After attaching a substratum, cells have a form of sphere (the phase "sphere") as the daughter cells after a mitosis. We revealed however that after this phase the reseeded cells do not start usual spreading and migration along substratum. They pass a phase of equally spreading in all directions and shaping their area as a circle (phase "circle"). This phase is absent of the daughter cells spreading after mitosis. We assume that the phase "circle" is a result of adaptation of the cells to reseedings at artificial cultivation. It is necessary for formation of a substrate composed of own extracellular matrix components (ECM) of the cells. Own ECM facilitates transition of the cells to their usual spreading and migration along substratum.

  20. The VULCANO VE-U7 Corium spreading benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Journeau, Christophe; Haquet, Jean-Francois [CEA Cadarache, Severe Accident Mastering experimental Laboratory (DEN/DTN/STRI/LMA), 13108 St Paul lez Durance (France); Spindler, Bertrand [CEA Grenoble, Physicochemistry and Multiphasic Thermalhydraulics Laboratory (DEN/DTN/SE2T/LPTM), 17 rue des Martyrs, F-38054 Grenoble CEDEX 9 (France); Spengler, Claus [Gesellschaft fuer Reaktorsicherheit mbH, Department for Thermohydraulics/Process Engineering, Schwertnergasse 1, D-50667 Koeln (Germany); Foit, Jerzy [Forschungszentrum Karlsruhe GmbH, Institut fuer Kern nd Energietechnik (IKET), P.O. Box 3640, D-76021 Karlsruhe (Germany)

    2006-07-01

    In a hypothetical nuclear reactor severe accident, corium spreading is one possible mitigation measure that has been selected for the EPR design. A post-test benchmark exercise has been organized on the VULCANO VE-U7 corium spreading experiment. In this test, a prototypic corium mixture representative of what could be expected at the opening of EPR reactor-pit gate has been spread on siliceous concrete and on a reference channel in inert refractory ceramic. The spreading progression was not much affected by the presence of concrete and sparging gases. The procedure used to estimate the corium physical properties from its composition and temperature provided a satisfactory data set. The CORFLOW, LAVA and THEMA codes provide satisfactory calculations of the spreading front evolution and of its final length. LAVA and THEMA estimations of the substrate temperatures, which are the initial conditions for longer term Molten Core Concrete Interaction or Corium Ceramic Interaction computations, are also close to the measured data, within the experimental uncertainties. (authors)

  1. The VULCANO VE-U7 Corium spreading benchmark

    International Nuclear Information System (INIS)

    Journeau, Christophe; Haquet, Jean-Francois; Spindler, Bertrand; Spengler, Claus; Foit, Jerzy

    2006-01-01

    In a hypothetical nuclear reactor severe accident, corium spreading is one possible mitigation measure that has been selected for the EPR design. A post-test benchmark exercise has been organized on the VULCANO VE-U7 corium spreading experiment. In this test, a prototypic corium mixture representative of what could be expected at the opening of EPR reactor-pit gate has been spread on siliceous concrete and on a reference channel in inert refractory ceramic. The spreading progression was not much affected by the presence of concrete and sparging gases. The procedure used to estimate the corium physical properties from its composition and temperature provided a satisfactory data set. The CORFLOW, LAVA and THEMA codes provide satisfactory calculations of the spreading front evolution and of its final length. LAVA and THEMA estimations of the substrate temperatures, which are the initial conditions for longer term Molten Core Concrete Interaction or Corium Ceramic Interaction computations, are also close to the measured data, within the experimental uncertainties. (authors)

  2. 77 FR 51966 - Eastern Arizona Resource Advisory Committee

    Science.gov (United States)

    2012-08-28

    ... DEPARTMENT OF AGRICULTURE Forest Service Eastern Arizona Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Eastern Arizona Resource Advisory Committee...

  3. Ozone modelling in Eastern Austria

    Energy Technology Data Exchange (ETDEWEB)

    Stohl, A.; Wotawa, G.; Kromp-Kolb, H. [Univ. of Agriculture, Vienna (Austria). Inst. of Meteorology and Physics; Winiwater, W. [Austrian Research Centre, Seibersdorf (Austria); Baumann, R.; Spangl, W. [Federal Environmental Agency, Vienna (Austria)

    1995-12-31

    High ozone concentrations are frequently observed in Eastern Austria, often exceeding local as well as international health standards, both for short-term as well as for long-term exposures. The maximum concentrations are produced in urban plumes, e.g. of the city of Vienna, whereas regional-scale transport and production of ozone is more important for the long-term concentrations. The Pannonian Ozone Project (POP) is an Austrian research initiative to model photochemical processes on a regional as well as on a local scale with a Lagrangian model to better understand the mechanisms leading to the high ozone concentrations and to develop abatement strategies. Up to now, focus has been on the regional scale. Aircraft, tethered balloon, tetroon and intensified ground measurements are carried out to validate the model. Although the major measurement campaign will be held in summer 1995, first results from a measurement campaign in summer 1994 are already available

  4. Relevant Measures to Prevent the Spread of African Swine Fever in the European Union Domestic Pig Sector.

    Science.gov (United States)

    Jurado, Cristina; Martínez-Avilés, Marta; De La Torre, Ana; Štukelj, Marina; de Carvalho Ferreira, Helena Cardoso; Cerioli, Monica; Sánchez-Vizcaíno, José Manuel; Bellini, Silvia

    2018-01-01

    During the past decade, African swine fever (ASF) has spread from the Caucasus region to eastern European Union countries affecting domestic pig and wild boar populations. In order to avert ASF spread, mitigation measures targeting both populations have been established. However, despite these efforts, ASF has been reported in thirteen different countries (Georgia, Azerbaijan, Armenia, the Russian Federation, Ukraine, Belarus, Estonia, Latvia, Lithuania, Poland, Moldova, Czech Republic, and Romania). In the absence of an effective vaccine or treatment to ASF, introduction and spread of ASF onto domestic pig farms can only be prevented by strict compliance to control measures. This study systematically reviewed available measures to prevent the spread of ASF in the EU domestic pig sector distinguishing between commercial, non-commercial, and outdoor farms. The search was performed in PubMed and using a common browser. A total of 52 documents were selected for the final review process, which included scientific articles, reports, EU documents and official recommendations, among others. From this literature review, 37 measures were identified as preventive measures for the introduction and spread of ASF. Subsequently, these measures were assessed by ASF experts for their relevance in the mitigation of ASF spread on the three mentioned types of farms. All experts agreed that some of the important preventive measures for all three types of farms were: the identification of animals and farm records; strict enforcement of the ban on swill feeding; and containment of pigs, so as to not allow direct or indirect pig-pig and/or pig-wild boar contacts. Other important preventive measures for all farms were education of farmers, workers, and operators; no contact between farmers and farm staff and external pigs; appropriate removal of carcasses, slaughter residues, and food waste; proper disposal of manure and dead animals, and abstaining from hunting activities during the

  5. Relevant Measures to Prevent the Spread of African Swine Fever in the European Union Domestic Pig Sector

    Directory of Open Access Journals (Sweden)

    Cristina Jurado

    2018-04-01

    Full Text Available During the past decade, African swine fever (ASF has spread from the Caucasus region to eastern European Union countries affecting domestic pig and wild boar populations. In order to avert ASF spread, mitigation measures targeting both populations have been established. However, despite these efforts, ASF has been reported in thirteen different countries (Georgia, Azerbaijan, Armenia, the Russian Federation, Ukraine, Belarus, Estonia, Latvia, Lithuania, Poland, Moldova, Czech Republic, and Romania. In the absence of an effective vaccine or treatment to ASF, introduction and spread of ASF onto domestic pig farms can only be prevented by strict compliance to control measures. This study systematically reviewed available measures to prevent the spread of ASF in the EU domestic pig sector distinguishing between commercial, non-commercial, and outdoor farms. The search was performed in PubMed and using a common browser. A total of 52 documents were selected for the final review process, which included scientific articles, reports, EU documents and official recommendations, among others. From this literature review, 37 measures were identified as preventive measures for the introduction and spread of ASF. Subsequently, these measures were assessed by ASF experts for their relevance in the mitigation of ASF spread on the three mentioned types of farms. All experts agreed that some of the important preventive measures for all three types of farms were: the identification of animals and farm records; strict enforcement of the ban on swill feeding; and containment of pigs, so as to not allow direct or indirect pig–pig and/or pig–wild boar contacts. Other important preventive measures for all farms were education of farmers, workers, and operators; no contact between farmers and farm staff and external pigs; appropriate removal of carcasses, slaughter residues, and food waste; proper disposal of manure and dead animals, and abstaining from hunting

  6. Relevant Measures to Prevent the Spread of African Swine Fever in the European Union Domestic Pig Sector

    Science.gov (United States)

    Jurado, Cristina; Martínez-Avilés, Marta; De La Torre, Ana; Štukelj, Marina; de Carvalho Ferreira, Helena Cardoso; Cerioli, Monica; Sánchez-Vizcaíno, José Manuel; Bellini, Silvia

    2018-01-01

    During the past decade, African swine fever (ASF) has spread from the Caucasus region to eastern European Union countries affecting domestic pig and wild boar populations. In order to avert ASF spread, mitigation measures targeting both populations have been established. However, despite these efforts, ASF has been reported in thirteen different countries (Georgia, Azerbaijan, Armenia, the Russian Federation, Ukraine, Belarus, Estonia, Latvia, Lithuania, Poland, Moldova, Czech Republic, and Romania). In the absence of an effective vaccine or treatment to ASF, introduction and spread of ASF onto domestic pig farms can only be prevented by strict compliance to control measures. This study systematically reviewed available measures to prevent the spread of ASF in the EU domestic pig sector distinguishing between commercial, non-commercial, and outdoor farms. The search was performed in PubMed and using a common browser. A total of 52 documents were selected for the final review process, which included scientific articles, reports, EU documents and official recommendations, among others. From this literature review, 37 measures were identified as preventive measures for the introduction and spread of ASF. Subsequently, these measures were assessed by ASF experts for their relevance in the mitigation of ASF spread on the three mentioned types of farms. All experts agreed that some of the important preventive measures for all three types of farms were: the identification of animals and farm records; strict enforcement of the ban on swill feeding; and containment of pigs, so as to not allow direct or indirect pig–pig and/or pig–wild boar contacts. Other important preventive measures for all farms were education of farmers, workers, and operators; no contact between farmers and farm staff and external pigs; appropriate removal of carcasses, slaughter residues, and food waste; proper disposal of manure and dead animals, and abstaining from hunting activities during the

  7. Information spread of emergency events: path searching on social networks.

    Science.gov (United States)

    Dai, Weihui; Hu, Hongzhi; Wu, Tunan; Dai, Yonghui

    2014-01-01

    Emergency has attracted global attentions of government and the public, and it will easily trigger a series of serious social problems if it is not supervised effectively in the dissemination process. In the Internet world, people communicate with each other and form various virtual communities based on social networks, which lead to a complex and fast information spread pattern of emergency events. This paper collects Internet data based on data acquisition and topic detection technology, analyzes the process of information spread on social networks, describes the diffusions and impacts of that information from the perspective of random graph, and finally seeks the key paths through an improved IBF algorithm. Application cases have shown that this algorithm can search the shortest spread paths efficiently, which may help us to guide and control the information dissemination of emergency events on early warning.

  8. Spreading depolarizations occur in human ischemic stroke with high incidence

    DEFF Research Database (Denmark)

    Dohmen, C.; Sakowitz, O.W.; Fabricius, M.

    2008-01-01

    Objective: Cortical spreading depression (CSD) and periinfarct depolarization (PID) have been shown in various experimental models of stroke to cause secondary neuronal damage and infarct expansion. For decades it has been questioned whether CSD or PID occur in human ischemic stroke. Here, we...... potential change spreading between adjacent channels was accompanied by transient depression of ECoG activity. In PID, a slow potential change spread between neighboring channels despite already established suppression of ECoG activity. Most CSDs and PIDs appeared repetitively in clusters. CSD or PID...... was observed in all but two patients. In these two patients, the electrode strip had been placed over infarcted tissue, and accordingly, no local ECoG or recurrent transient depolarization activity occurred throughout the observation period. Interpretation: CSD and PID occurred spontaneously with high...

  9. Dynamic wetting and spreading and the role of topography

    International Nuclear Information System (INIS)

    McHale, Glen; Newton, Michael I; Shirtcliffe, Neil J

    2009-01-01

    The spreading of a droplet of a liquid on a smooth solid surface is often described by the Hoffman-de Gennes law, which relates the edge speed, v e , to the dynamic and equilibrium contact angles θ and θ e through v e ∝θ(θ 2 -θ e 2 ). When the liquid wets the surface completely and the equilibrium contact angle vanishes, the edge speed is proportional to the cube of the dynamic contact angle. When the droplets are non-volatile this law gives rise to simple power laws with time for the contact angle and other parameters in both the capillary and gravity dominated regimes. On a textured surface, the equilibrium state of a droplet is strongly modified due to the amplification of the surface chemistry induced tendencies by the topography. The most common example is the conversion of hydrophobicity into superhydrophobicity. However, when the surface chemistry favors partial wetting, topography can result in a droplet spreading completely. A further, frequently overlooked consequence of topography is that the rate at which an out-of-equilibrium droplet spreads should also be modified. In this report, we review ideas related to the idea of topography induced wetting and consider how this may relate to dynamic wetting and the rate of droplet spreading. We consider the effect of the Wenzel and Cassie-Baxter equations on the driving forces and discuss how these may modify power laws for spreading. We relate the ideas to both the hydrodynamic viscous dissipation model and the molecular-kinetic theory of spreading. This suggests roughness and solid surface fraction modified Hoffman-de Gennes laws relating the edge speed to the dynamic and equilibrium contact angle. We also consider the spreading of small droplets and stripes of non-volatile liquids in the capillary regime and large droplets in the gravity regime. In the case of small non-volatile droplets spreading completely, a roughness modified Tanner's law giving the dependence of dynamic contact angle on time is

  10. Energy spread in SLC linac with Landau damping

    International Nuclear Information System (INIS)

    Seeman, J.

    1984-01-01

    The possibility of using Landau damping to reduce the growth of the beam size due to transverse wake fields has been known for some time. Recently K. Bane has calculated the effects of Landau damping for the SLC. The energy spread is then slowly removed so that at the end of the linac it has returned to the SLC specification of less than +0.5%. The purpose of the energy spread is to reduce the resonant driving of the tail of the bunch by the head. In this note the expected energy spreads within the beam are tabulated at various positions along the linac for use by those people designing momentum dependent equipment and for those interested in Landau damping

  11. Spreading of Trisiloxanes on Thin Water Film: Dry Spot Profile

    Directory of Open Access Journals (Sweden)

    Derrick Ovunda NJOBUENWU

    2007-08-01

    Full Text Available This paper reports the results of an experimental investigation of the spreading of trisiloxanes EO6, EO7, EO8, EO9 and sodium dodecyl sulphate SDS on thin films which are 320 microns in thickness; the concentrations covered are above the CMC. The spreading of SDS is accompanied by the formation of a “dry spot” which advances in time roughly as t1/4. The trisiloxanes spreading gave rise to dry spot formation that was accompanied by “irregularities”, which corresponded to an abrupt jump in the plot of dry spot radius versus time. The behaviour is attributed to a variety of factors: disjoining pressure effects or the fact that the Petri dish was too small so that backward propagating waves were set up due to reflections from the walls which interacted with the outspreading dry spot.

  12. Information Spread of Emergency Events: Path Searching on Social Networks

    Directory of Open Access Journals (Sweden)

    Weihui Dai

    2014-01-01

    Full Text Available Emergency has attracted global attentions of government and the public, and it will easily trigger a series of serious social problems if it is not supervised effectively in the dissemination process. In the Internet world, people communicate with each other and form various virtual communities based on social networks, which lead to a complex and fast information spread pattern of emergency events. This paper collects Internet data based on data acquisition and topic detection technology, analyzes the process of information spread on social networks, describes the diffusions and impacts of that information from the perspective of random graph, and finally seeks the key paths through an improved IBF algorithm. Application cases have shown that this algorithm can search the shortest spread paths efficiently, which may help us to guide and control the information dissemination of emergency events on early warning.

  13. Epidemic cholera in Latin America: spread and routes of transmission.

    Science.gov (United States)

    Guthmann, J P

    1995-12-01

    In the most recent epidemic of cholera in Latin America, nearly a million cases were reported and almost 9000 people died between January 1991 and December 1993. The epidemic spread rapidly from country to country, affecting in three years all the countries of Latin America except Uruguay and the Caribbean. Case-control studies carried out in Peru showed a significant association between drinking water and risk of disease. Cholera was associated with the consumption of unwashed fruit and vegetables, with eating food from street vendors and with contaminated crabmeat transported in travellers' luggage. This article documents the spread of the epidemic and its routes of transmission and discusses whether the introduction of the epidemic to Peru and its subsequent spread throughout the continent could have been prevented.

  14. Users' participation and social influence during information spreading on Twitter.

    Science.gov (United States)

    Zhang, Xin; Han, Ding-Ding; Yang, Ruiqi; Zhang, Ziqiao

    2017-01-01

    Online Social Networks generate a prodigious wealth of real-time information at an incessant rate. In this paper we study the empirical data that crawled from Twitter to describe the topology and information spreading dynamics of Online Social Networks. We propose a measurement with three measures to state the efforts of users on Twitter to get their information spreading, based on the unique mechanisms for information retransmission on Twitter. It is noticed that small fraction of users with special performance on participation can gain great influence, while most other users play a role as middleware during the information propagation. Thus a community analysis is performed and four categories of users are found with different kinds of participation that cause the information dissemination dynamics. These suggest that exiting topological measures alone may reflect little about the influence of individuals and provide new insights for information spreading.

  15. Epidemic spread in coupled populations with seasonally varying migration rates

    Science.gov (United States)

    Muzyczyn, Adam; Shaw, Leah B.

    2009-03-01

    The H5N1 strain of avian influenza has spread worldwide, and this spread may be due to seasonal migration of birds and mixing of birds from different regions in the wintering grounds. We studied a multipatch model for avian influenza with seasonally varying migration rates. The bird population was divided into two spatially distinct patches, or subpopulations. Within each patch, the disease followed the SIR (susceptible-infected-recovered) model for epidemic spread. Migration rates were varied periodically, with a net flux toward the breeding grounds during the spring and towards the wintering grounds during the fall. The case of two symmetric patches reduced to single-patch SIR dynamics. However, asymmetry in the birth and contact rates in the breeding grounds and wintering grounds led to bifurcations to longer period orbits and chaotic dynamics. We studied the bifurcation structure of the model and the phase relationships between outbreaks in the two patches.

  16. Airborne spread of foot-and-mouth disease - Model intercomparison

    DEFF Research Database (Denmark)

    Gloster, John; Jones, Andrew; Redington, Alison

    2010-01-01

    Foot-and-mouth disease virus (FMDV) spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route, with the relative importance of each mechanism depending on the particular outbreak characteristics....... Atmospheric dispersion models have been developed to assess airborne spread of FMDV in a number of countries, including the UK, Denmark, Australia, New Zealand, USA and Canada. These models were compared at a Workshop hosted by the Institute for Animal Health/Met Office in 2008. Each modeller was provided...... with data relating to the 1967 outbreak of FMD in Hampshire, UK, and asked to predict the spread of FMDV by the airborne route. A number of key issues emerged from the Workshop and subsequent modelling work: (1) in general all models predicted similar directions for livestock at risk, with much...

  17. Suppressing traffic-driven epidemic spreading by adaptive routing strategy

    International Nuclear Information System (INIS)

    Yang, Han-Xin; Wang, Zhen

    2016-01-01

    The design of routing strategies for traffic-driven epidemic spreading has received increasing attention in recent years. In this paper, we propose an adaptive routing strategy that incorporates topological distance with local epidemic information through a tunable parameter h. In the case where the traffic is free of congestion, there exists an optimal value of routing parameter h, leading to the maximal epidemic threshold. This means that epidemic spreading can be more effectively controlled by adaptive routing, compared to that of the static shortest path routing scheme. Besides, we find that the optimal value of h can greatly relieve the traffic congestion in the case of finite node-delivering capacity. We expect our work to provide new insights into the effects of dynamic routings on traffic-driven epidemic spreading.

  18. Disease spreading with epidemic alert on small-world networks

    International Nuclear Information System (INIS)

    Han, Xiao-Pu

    2007-01-01

    Base on two-dimension small-world networks, a susceptible-infected model with epidemic alert is proposed in this Letter. In this model, if some parts of the network are alarmed as dangerous, a fraction of edges between the alarmed parts and others will be removed, and two cases of alerting rules that the degree and frequency of contacts kept unchanged are considered respectively. The numerical simulations show that the spreading velocity is reduced by the accurate and timely epidemic alert, and the more accurate and timely, the stronger the deceleration effect. This model indicates that to broadcast epidemic alert timely is helpful and necessary in the control of epidemic spreading, and in agreement with the general view of epidemic alert. This work is helpful to understand the effects of epidemic alert on disease spreading

  19. Numerical study of drop spreading on a flat surface

    Science.gov (United States)

    Wang, Sheng; Desjardins, Olivier

    2017-11-01

    In this talk, we perform a numerical study of a droplet on a flat surface with special emphasis on capturing the spreading dynamics. The computational methodology employed is tailored for simulating large-scale two-phase flows within complex geometries. It combines a conservative level-set method to capture the liquid-gas interface, a conservative immersed boundary method to represent the solid-fluid interface, and a sub-grid curvature model at the triple-point to implicitly impose the contact angle of the liquid-gas interface. The performance of the approach is assessed in the inertial droplet spreading regime, the viscous spreading regime of high viscosity drops, and with the capillary oscillation of low viscosity droplets.

  20. Spread and burning behavior of continuous spill fires

    DEFF Research Database (Denmark)

    Zhao, Jinlong; Huang, Hong; Jomaas, Grunde

    2017-01-01

    Spill fire experiments with continuous discharge on a fireproof glass sheet were conducted to improve the understanding of spill fire spread and burning. Ethanol was used as the fuel and the discharge rate was varied from 2.8. mL/s to 7.6. mL/s. Three ignition conditions were used...... in the experiments; no ignition, instantaneous ignition and delayed ignition. The spread rate, regression rate, penetrated thermal radiation and the temperature of the bottom glass were analyzed. The experiments clearly show the entire spread process for spill fires. Further, the regression rate of spill fires...... at the quasi-steady burning was lower than that of pool fires and the ratio of the spill fires' regression rate to the pool fires' regression rate was found to be approximately 0.89. With respect to the radiative penetration and the heat conduction between the fuel layer and the glass, a regression rate...

  1. Analyses of corium spreading in Mark I containment geometry

    International Nuclear Information System (INIS)

    Sienicki, J.J.; Chu, C.C.; Farmer, M.T.

    1991-01-01

    An assessment of melt spreading in the Mark I system has been carried out using the MELTSPREAD-1 computer code together with supporting analyses. Application of MELTSPREAD-1 confirms the calculation of shell survival in a wet containment for the most probable melt release conditions from NUREG/CR-5423. According to MELTSPREAD-1, a dry containment also may not be threatened by melt spreading. This reflects the heat losses undergone by the melt in the process of spreading to the shell conservatively neglected in NUREG/CR-5423. However, there exist parameter ranges outside the most probable set where shell failure may be calculated. Accounting for the breakup and quenching of melt relocating through a deep layer of subcooled water also conservatively neglected in NUREG/CR-5423 can reduce the set of parameter variations for which containment failure is calculated in the wet case

  2. An information spreading model based on online social networks

    Science.gov (United States)

    Wang, Tao; He, Juanjuan; Wang, Xiaoxia

    2018-01-01

    Online social platforms are very popular in recent years. In addition to spreading information, users could review or collect information on online social platforms. According to the information spreading rules of online social network, a new information spreading model, namely IRCSS model, is proposed in this paper. It includes sharing mechanism, reviewing mechanism, collecting mechanism and stifling mechanism. Mean-field equations are derived to describe the dynamics of the IRCSS model. Moreover, the steady states of reviewers, collectors and stiflers and the effects of parameters on the peak values of reviewers, collectors and sharers are analyzed. Finally, numerical simulations are performed on different networks. Results show that collecting mechanism and reviewing mechanism, as well as the connectivity of the network, make information travel wider and faster, and compared to WS network and ER network, the speed of reviewing, sharing and collecting information is fastest on BA network.

  3. Outwitting the series resistance in scanning spreading resistance microscopy

    International Nuclear Information System (INIS)

    Schulze, A.; Cao, R.; Eyben, P.; Hantschel, T.; Vandervorst, W.

    2016-01-01

    The performance of nanoelectronics devices critically depends on the distribution of active dopants inside these structures. For this reason, dopant profiling has been defined as one of the major metrology challenges by the international technology roadmap of semiconductors. Scanning spreading resistance microscopy (SSRM) has evolved as one of the most viable approaches over the last decade due to its excellent spatial resolution, sensitivity and quantification accuracy. However, in case of advanced device architectures like fins and nanowires a proper measurement of the spreading resistance is often hampered by the increasing impact of parasitic series resistances (e.g. bulk series resistance) arising from the confined nature of the aforementioned structures. In order to overcome this limitation we report in this paper the development and implementation of a novel SSRM mode (fast Fourier transform-SSRM: FFT-SSRM) which essentially decouples the spreading resistance from parasitic series resistance components. We show that this can be achieved by a force modulation (leading to a modulated spreading resistance signal) in combination with a lock-in deconvolution concept. In this paper we first introduce the principle of operation of the technique. We discuss in detail the underlying physical mechanisms as well as the technical implementation on a state-of-the-art atomic force microscope (AFM). We demonstrate the performance of FFT-SSRM and its ability to remove substantial series resistance components in practice. Eventually, the possibility of decoupling the spreading resistance from the intrinsic probe resistance will be demonstrated and discussed. - Highlights: • A novel electrical AFM mode for carrier profiling in confined volumes is presented. • Thereby the force and hence the contact area between AFM probe and sample is modulated. • Information on the spreading resistance is derived using a lock-in approach. • Bulk series resistance components are

  4. Zeno dynamics in wave-packet diffraction spreading

    Energy Technology Data Exchange (ETDEWEB)

    Porras, Miguel A. [Departamento de Fisica Aplicada, Universidad Politecnica de Madrid, Rios Rosas 21, ES-28003 Madrid (Spain); Luis, Alfredo; Gonzalo, Isabel [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, ES-28040 Madrid (Spain); Sanz, Angel S. [Instituto de Fisica Fundamental-CSIC, Serrano 123, ES-28006 Madrid (Spain)

    2011-11-15

    We analyze a simple and feasible practical scheme displaying Zeno, anti-Zeno, and inverse-Zeno effects in the observation of wave-packet spreading caused by free evolution. The scheme is valid both in spatial diffraction of classical optical waves and in time diffraction of a quantum wave packet. In the optical realization, diffraction spreading is observed by placing slits between a light source and a light-power detector. We show that the occurrence of Zeno or anti-Zeno effects depends just on the frequency of observations between the source and detector. These effects are seen to be related to the diffraction mode theory in Fabry-Perot resonators.

  5. Surgical Management of Perineural Spread of Head and Neck Cancers.

    Science.gov (United States)

    Solares, C Arturo; Mason, Eric; Panizza, Benedict J

    2016-04-01

    The surgical management of perineural spread of head and neck cancers has become an integral part in the contemporary treatment of this pathology. We now understand that tumour spreads within the epineurium and in a continuous fashion. We also can rely on the accuracy of magnetic resonance neurography in detecting and defining the extent of disease. With modern skull base techniques and a greater understanding of the anatomy in this region, specific operations can be designed to help eradicate disease. We review the current approaches and techniques used that enable us to better obtain tumour free margins and hence improve survival.

  6. Spreading dynamics of 2D dipolar Langmuir monolayer phases.

    Science.gov (United States)

    Heinig, P; Wurlitzer, S; Fischer, Th M

    2004-07-01

    We study the spreading of a liquid 2D dipolar droplet in a Langmuir monolayer. Interfacial tensions (line tensions) and microscopic contact angles depend on the scale on which they are probed and obey a scaling law. Assuming rapid equilibration of the microscopic contact angle and ideal slippage of the 2D solid/liquid and solid/gas boundary, the driving force of spreading is merely expressed by the shape-dependent long-range interaction integrals. We obtain good agreement between experiment and numerical simulations using this theory.

  7. Accuracy of single photoelectron time spread measurement of fast photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.

    1975-01-01

    The accuracy of time spread measurements of fast photomultipliers was investigated, using single photoelectrons. The effect of the finite light pulse width on the measurement accuracy was determined and discussed. Experimental data were obtained on a special measuring system for light pulse widths ranging from 200 psec to 10 nsec, using fast photomultipliers 8850 and C31024 with optimized operating conditions for minimum transit time spread. A modified exponential function expression and curve-fitting parameters are given, which fit closely the experimentally obtained data over a wide dynamic range of light pulse widths. (U.S.)

  8. The impact of awareness on epidemic spreading in networks.

    Science.gov (United States)

    Wu, Qingchu; Fu, Xinchu; Small, Michael; Xu, Xin-Jian

    2012-03-01

    We explore the impact of awareness on epidemic spreading through a population represented by a scale-free network. Using a network mean-field approach, a mathematical model for epidemic spreading with awareness reactions is proposed and analyzed. We focus on the role of three forms of awareness including local, global, and contact awareness. By theoretical analysis and simulation, we show that the global awareness cannot decrease the likelihood of an epidemic outbreak while both the local awareness and the contact awareness can. Also, the influence degree of the local awareness on disease dynamics is closely related with the contact awareness.

  9. Inhomogeneity of epidemic spreading with entropy-based infected clusters.

    Science.gov (United States)

    Wen-Jie, Zhou; Xing-Yuan, Wang

    2013-12-01

    Considering the difference in the sizes of the infected clusters in the dynamic complex networks, the normalized entropy based on infected clusters (δ*) is proposed to characterize the inhomogeneity of epidemic spreading. δ* gives information on the variability of the infected clusters in the system. We investigate the variation in the inhomogeneity of the distribution of the epidemic with the absolute velocity v of moving agent, the infection density ρ, and the interaction radius r. By comparing δ* in the dynamic networks with δH* in homogeneous mode, the simulation experiments show that the inhomogeneity of epidemic spreading becomes smaller with the increase of v, ρ, r.

  10. The continuum of spreading depolarizations in acute cortical lesion development

    DEFF Research Database (Denmark)

    Hartings, Jed A; Shuttleworth, C William; Kirov, Sergei A

    2017-01-01

    A modern understanding of how cerebral cortical lesions develop after acute brain injury is based on Aristides Leão's historic discoveries of spreading depression and asphyxial/anoxic depolarization. Treated as separate entities for decades, we now appreciate that these events define a continuum....... The causal role of these waves in lesion development has been proven by real-time monitoring of electrophysiology, blood flow, and cytotoxic edema. The spreading depolarization continuum further applies to other models of acute cortical lesions, suggesting that it is a universal principle of cortical lesion...

  11. Visualization of the Eastern Renewable Generation Integration Study: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gruchalla, Kenny; Novacheck, Joshua; Bloom, Aaron

    2016-12-01

    The Eastern Renewable Generation Integration Study (ERGIS), explores the operational impacts of the wide spread adoption of wind and solar photovoltaics (PV) resources in the U.S. Eastern Interconnection and Quebec Interconnection (collectively, EI). In order to understand some of the economic and reliability challenges of managing hundreds of gigawatts of wind and PV generation, we developed state of the art tools, data, and models for simulating power system operations using hourly unit commitment and 5-minute economic dispatch over an entire year. Using NREL's high-performance computing capabilities and new methodologies to model operations, we found that the EI, as simulated with evolutionary change in 2026, could balance the variability and uncertainty of wind and PV at a 5-minute level under a variety of conditions. A large-scale display and a combination of multiple coordinated views and small multiples were used to visually analyze the four large highly multivariate scenarios with high spatial and temporal resolutions. state of the art tools, data, and models for simulating power system operations using hourly unit commitment and 5-minute economic dispatch over an entire year. Using NRELs high-performance computing capabilities and new methodologies to model operations, we found that the EI, as simulated with evolutionary change in 2026, could balance the variability and uncertainty of wind and PV at a 5-minute level under a variety of conditions. A large-scale display and a combination of multiple coordinated views and small multiples were used to visually analyze the four large highly multivariate scenarios with high spatial and temporal resolutions.

  12. Ethnographies of Grey Zones in Eastern Europe

    DEFF Research Database (Denmark)

    Over the last two decades, Eastern Europe has experienced extensive changes in geo-political relocations and relations leading to everyday uncertainty. Attempts to establish liberal democracies, re-orientations from planned to market economics, and a desire to create ‘new states’ and internationa......Over the last two decades, Eastern Europe has experienced extensive changes in geo-political relocations and relations leading to everyday uncertainty. Attempts to establish liberal democracies, re-orientations from planned to market economics, and a desire to create ‘new states...... contemporary Eastern Europe....

  13. Ethnographies of Grey Zones in Eastern Europe:

    DEFF Research Database (Denmark)

    Over the last two decades, Eastern Europe has experienced extensive changes in geo-political relocations and relations leading to everyday uncertainty. Attempts to establish liberal democracies, re-orientations from planned to market economics, and a desire to create ‘new states’ and internationa......Over the last two decades, Eastern Europe has experienced extensive changes in geo-political relocations and relations leading to everyday uncertainty. Attempts to establish liberal democracies, re-orientations from planned to market economics, and a desire to create ‘new states...... contemporary Eastern Europe....

  14. 60,000 years of interactions between Central and Eastern Africa documented by major African mitochondrial haplogroup L2.

    Science.gov (United States)

    Silva, Marina; Alshamali, Farida; Silva, Paula; Carrilho, Carla; Mandlate, Flávio; Jesus Trovoada, Maria; Černý, Viktor; Pereira, Luísa; Soares, Pedro

    2015-07-27

    Mitochondrial DNA (mtDNA) haplogroup L2 originated in Western Africa but is nowadays spread across the entire continent. L2 movements were previously postulated to be related to the Bantu expansion, but L2 expansions eastwards probably occurred much earlier. By reconstructing the phylogeny of L2 (44 new complete sequences) we provide insights on the complex net of within-African migrations in the last 60 thousand years (ka). Results show that lineages in Southern Africa cluster with Western/Central African lineages at a recent time scale, whereas, eastern lineages seem to be substantially more ancient. Three moments of expansion from a Central African source are associated to L2: (1) one migration at 70-50 ka into Eastern or Southern Africa, (2) postglacial movements (15-10 ka) into Eastern Africa; and (3) the southward Bantu Expansion in the last 5 ka. The complementary population and L0a phylogeography analyses indicate no strong evidence of mtDNA gene flow between eastern and southern populations during the later movement, suggesting low admixture between Eastern African populations and the Bantu migrants. This implies that, at least in the early stages, the Bantu expansion was mainly a demic diffusion with little incorporation of local populations.

  15. Male out-migration: a factor for the spread of HIV infection among married men and women in rural India.

    Directory of Open Access Journals (Sweden)

    Niranjan Saggurti

    Full Text Available INTRODUCTION: Thus far, the reasons for increasing HIV prevalence in northern and eastern Indian states are unknown. We investigated the role of male out-migration in the spread of human immunodeficiency virus (HIV infection through a case-control study in rural India. METHODS: Currently married men and women were recruited from HIV testing and treatment centers across seven selected districts with high rates of male out-migration in eastern and northern India in 2010 using a case-control study design. Case subjects (men: 595, women: 609 were people who tested HIV seropositive and control subjects (men: 611, women: 600 were those tested HIV seronegative. For each gender, we obtained adjusted odds ratios (AORs and population attributable risks (PARs for migration, and behavioral factors. RESULTS: For men, the prevalence of HIV was significantly higher among those with a migration history (AOR, 4.4; for women, the prevalence of HIV was higher among those with migrant husbands (AOR, 2·3. For both genders, the returned male migration (men: AOR, 3·7; women: AOR, 28 was significantly associated with higher prevalence of HIV infection. The PAR associated with male migration was higher for men (54.5%-68.6% than for women (32·7%-56·9% across the study areas. DISCUSSION: Male out-migration is the most important risk factor influencing the spread of HIV infection in rural areas with high out-migration rates, thereby emphasizing the need for interventions, particularly, for returned migrants and spouses of those migrants.

  16. Eastern Renewable Generation Integration Study

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, Aaron [National Renewable Energy Lab. (NREL), Golden, CO (United States); Townsend, Aaron [National Renewable Energy Lab. (NREL), Golden, CO (United States); Palchak, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Novacheck, Joshua [National Renewable Energy Lab. (NREL), Golden, CO (United States); King, Jack [RePPAE LLC, Wexford, PA (United States); Barrows, Clayton [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ibanez, Eduardo [GE Energy, Denver, CO (United States); O' Connell, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jordan, Gary [GE Energy, Denver, CO (United States); Roberts, Billy [National Renewable Energy Lab. (NREL), Golden, CO (United States); Draxl, Caroline [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gruchalla, Kenny [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-08-01

    The Eastern Interconnection (EI) is one of the largest power systems in the world, and its size and complexity have historically made it difficult to study in high levels of detail in a modeling environment. In order to understand how this system might be impacted by high penetrations (30% of total annual generation) of wind and solar photovoltaic (PV) during steady state operations, the National Renewable Energy Laboratory (NREL) and the U.S. Department of Energy (DOE) conducted the Eastern Renewable Generation Integration Study (ERGIS). This study investigates certain aspects of the reliability and economic efficiency problem faced by power system operators and planners. Specifically, the study models the ability to meet electricity demand at a 5-minute time interval by scheduling resources for known ramping events, while maintaining adequate reserves to meet random variation in supply and demand, and contingency events. To measure the ability to meet these requirements, a unit commitment and economic dispatch (UC&ED) model is employed to simulate power system operations. The economic costs of managing this system are presented using production costs, a traditional UC&ED metric that does not include any consideration of long-term fixed costs. ERGIS simulated one year of power system operations to understand regional and sub-hourly impacts of wind and PV by developing a comprehensive UC&ED model of the EI. In the analysis, it is shown that, under the study assumptions, generation from approximately 400 GW of combined wind and PV capacity can be balanced on the transmission system at a 5-minute level. In order to address the significant computational burdens associated with a model of this detail we apply novel computing techniques to dramatically reduce simulation solve time while simultaneously increasing the resolution and fidelity of the analysis. Our results also indicate that high penetrations of wind and PV (collectively variable generation (VG

  17. Contour adaptation reduces the spreading of edge induced colors.

    Science.gov (United States)

    Coia, Andrew J; Crognale, Michael A

    2017-04-25

    Brief exposure to flickering achromatic outlines of an area causes a reduction in the brightness contrast of the surface inside the area. This contour adaptation to achromatic contours does not reduce surface contrast when the surface is chromatic (the saturation or colorimetric purity of the surface is maintained). In addition to reducing the brightness of physical luminance contrast, contour adaptation also reduces (or even reverses) the illusory brightness contrast seen in the Craik-O'Brien-Cornsweet illusion, in which two physically identical grey areas appear different brightness because of a sharp luminance edge separating them. Chromatic color spreading illusions also occur with chromatic inducing edges, and an unanswered question is whether contour adaptation can reduce the perceived contrast of illusory color spreading from edges, even though it cannot reduce the perceived contrast of physical surface color. The current studies use a color spreading illusion known as the watercolor effect in order to test whether illusory color spreading is affected by contour adaptation. The general findings of physical achromatic contrast being reduced and chromatic contrast being robust to contour adaptation were replicated. However, both illusory brightness and color were reduced by contour adaptation, even when the illusion edges only differed in chromatic contrast with each other and the background. Additional studies adapting to chromatic contours showed opposite effects on illusory color contrast than achromatic adaptation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The Spread of Substance Use and Delinquency between Adolescent Twins

    Science.gov (United States)

    Laursen, Brett; Hartl, Amy C.; Vitaro, Frank; Brendgen, Mara; Dionne, Ginette; Boivin, Michel

    2017-01-01

    This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A 3-wave longitudinal actor-partner…

  19. Measuring and Controlling the Energy Spread in CEBAF

    CERN Document Server

    Krafft, G A; Dickson, R W; Kazimi, R; Lebedev, V A; Tiefenback, M G

    2000-01-01

    As compared to electron storage rings, one advantage of recirculating linear accelerators is that the beam properties at target are no longer dominated by the equilibrium between quantum radiative diffusion and radiation damping because new beam is continually injected into the accelerator. This allows the energy spread from a CEBAF-type machine to be relatively small; the measured energy spread from CEBAF at 4 GeV is less than 100 parts per million accumulated over times of order several days. In this paper, the various subsystems contributing to the energy spread of a CEBAF-type accelerator are reviewed, as well as the machine diagnostics and controls that are used in CEBAF to ensure that a small energy spread is provided during routine running. Examples of relevant developments are (1) stable short bunches emerging from the injector, (2) precision timing and phasing of the linacs with respect to the centroid of the beam bunches on all passes, (3) implementing 2 kHz sampling rate feedback systems for final ...

  20. Sovereign bonds in developing countries: Drivers of issuance and spreads

    Directory of Open Access Journals (Sweden)

    Andrea F. Presbitero

    2016-06-01

    Full Text Available In the last decade there has been a new wave of sovereign bond issuances in Africa. What determines the ability of developing countries to issue bonds in international capital and what explains the spreads on these bonds? This paper examines these questions using a dataset that includes 105 developing countries during the period 1995–2014. We find that a country is more likely to issue a bond when, in comparison with non-issuing peers, it is larger in economic size, has higher per capita GDP, a lower public debt, and a more effective government. Spreads on sovereign bonds are lower for countries with strong external and fiscal positions, as well as robust economic growth and government effectiveness. We also find that primary spreads for the average Sub-Saharan African issuer are higher than in other regions. With regard to global factors, our results confirm the existing evidence that issuances are more likely during periods of global liquidity and high commodity prices, especially for Sub-Saharan African countries, and spreads are higher in periods of higher market volatility.

  1. Visual Attention and Quantifier-Spreading in Heritage Russian Bilinguals

    Science.gov (United States)

    Sekerina, Irina A.; Sauermann, Antje

    2015-01-01

    It is well established in language acquisition research that monolingual children and adult second language learners misinterpret sentences with the universal quantifier "every" and make quantifier-spreading errors that are attributed to a preference for a match in number between two sets of objects. The present Visual World eye-tracking…

  2. Term structure of sovereign spreads: a contingent claim model

    Directory of Open Access Journals (Sweden)

    Katia Rocha

    2007-12-01

    Full Text Available This paper proposes a simple structural model to estimate the termstructure and the implied default probability of a selected group of emerging countries, which account for 54% of the JPMorgan EMBIG index on average for the period 2000-2005. The real exchange rate dynamic, modeled as a pure diffusion process, is assumed to trigger default. The calibrated model generates sovereign spread curves consistent to market data. The results suggest that the market is systematically overpricing spreads for Brazil in 100 basis points, whereas for Mexico, Russia and Turkey the model is able to reproduce the market behavior.Este trabalho propõe um modelo estrutural para estimar a estrutura a termo e a probabilidade implícita de default de países emergentes que representam, em média, 54% do índice EMBIG do JPMorgan no período de 2000-2005. A taxa de câmbio real, modelada como um processo de difusão simples, é considerada como indicativa de default. O modelo calibrado gera a estrutura a termo dos spreads consistente com dados de mercado, indicando que o mercado sistematicamente sobre-estima os spreads para o Brasil em 100 pontos base na média, enquanto para México, Rússia e Turquia reproduz o comportamento do mercado.

  3. Do Free Quantum-Mechanical Wave Packets Always Spread?

    Science.gov (United States)

    Klein, James R.

    1980-01-01

    The spreading or shrinking of free three-dimensional quantum-mechanical wave packets is addressed. A seeming paradox concerning the time evolution operator and nonspreading wave packets is discussed, and the necessity of taking into account the appropriate mathematical structure of quantum mechanics is emphasized. Teaching implications are given.…

  4. Spread Spectrum Techniques and their Applications to Wireless Communications

    DEFF Research Database (Denmark)

    Prasad, Ramjee; Cianca, E.

    2005-01-01

    Spread Spectrum (SS) radio communications is on the verge of potentially explosive commercial development An SS-based multiple access, such as CDMA, has been chosen for 3G wireless communications. Other current applications of SS techniues are in Wireless LANs and Satellite Navigation Systems...

  5. Fire spread in chaparral -"go or no-go?"

    Science.gov (United States)

    D.R. Weise; Xiangyang Zhou; Lulu Sun; Shankar Mahalingam

    2005-01-01

    Current fire models are designed to model the spread of a linear fire front in dead, small-diameter fuels. Fires in predominantly living vegetation account for a large proportion of annual burned area nationally. Prescribed burning is used to manage living fuels; however, prescribed burning is currently conducted under conditions that result in marginal burning. We do...

  6. Web malware spread modelling and optimal control strategies

    Science.gov (United States)

    Liu, Wanping; Zhong, Shouming

    2017-02-01

    The popularity of the Web improves the growth of web threats. Formulating mathematical models for accurate prediction of malicious propagation over networks is of great importance. The aim of this paper is to understand the propagation mechanisms of web malware and the impact of human intervention on the spread of malicious hyperlinks. Considering the characteristics of web malware, a new differential epidemic model which extends the traditional SIR model by adding another delitescent compartment is proposed to address the spreading behavior of malicious links over networks. The spreading threshold of the model system is calculated, and the dynamics of the model is theoretically analyzed. Moreover, the optimal control theory is employed to study malware immunization strategies, aiming to keep the total economic loss of security investment and infection loss as low as possible. The existence and uniqueness of the results concerning the optimality system are confirmed. Finally, numerical simulations show that the spread of malware links can be controlled effectively with proper control strategy of specific parameter choice.

  7. Effective Strategies to Spread Redesigning Care Processes Among Healthcare Teams.

    Science.gov (United States)

    Lavoie-Tremblay, Mélanie; O'Connor, Patricia; Lavigne, Geneviève L; Briand, Anaïck; Biron, Alain; Baillargeon, Sophie; MacGibbon, Brenda; Ringer, Justin; Cyr, Guylaine

    2015-07-01

    The purpose of this study was to describe how spread strategies facilitate the successful implementation of the Transforming Care at the Bedside (TCAB) program and their impact on healthcare workers and patients in a major Canadian healthcare organization. This study used a qualitative and descriptive design with focus groups and individual interviews held in May 2014. Participants included managers and healthcare providers from eight TCAB units in a university health center in Quebec, Canada. The sample was composed of 43 individuals. The data were analyzed using NVivo according to the method proposed by Miles and Huberman. The first two themes that emerged from the analysis are related to context (organizational transition requiring many changes) and spread strategies for the TCAB program (senior management support, release time and facilitation, rotation of team members, learning from previous TCAB teams, and engaging patients). The last theme that emerged from the analysis is the impact on healthcare professionals (providing front-line staff and managers with the training they need to make changes, team leadership, and increasing receptivity to hearing patients' and families' needs and requests). This study describes the perspectives of managers and team members to provide a better understanding of how spread strategies can facilitate the successful implementation of the TCAB program in a Canadian healthcare organization. Spread strategies facilitate the implementation of changes to improve the quality and safety of care provided to patients. © 2015 Sigma Theta Tau International.

  8. Correlation between spinal column length and the spread of ...

    African Journals Online (AJOL)

    Correlation between spinal column length and the spread of subarachnoid hyperbaric bupivacaine in the term parturient. W.M Wan Rahiza, A.R Raha, A Muhd, M.N Nadia, M Muhammad, Z Azmil, I Azarinah, M.Z Jaafar ...

  9. Six Tips to Help Prevent the Spread of Norovirus

    Centers for Disease Control (CDC) Podcasts

    2013-08-27

    Dr. Aron Hall, a CDC epidemiologist specializing in noroviruses, discusses six tips to help prevent the spread of norovirus.  Created: 8/27/2013 by National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases (DVD).   Date Released: 8/27/2013.

  10. The Term Structure of Credit Spreads on Euro Corporate Bonds

    NARCIS (Netherlands)

    van Landschoot, A.

    2003-01-01

    Although there is a broad literature on structural credit risk models, there has been little empirical testing of these models.In this paper we examine the term structure of credit spreads on euro corporate bonds and the empirical validation of structural credit risk models.The latter provide a

  11. Spreading history of the Arabian Sea: Some new constraints

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.; Bhattacharya, G.C.; Murty, G.P.S.; Desa, M.

    Based on a new identification of magnetic anomalies, additional constraints are provided on the two episodes of spreading history of the Arabian Sea. Commencing at A27, the older phase ended at A21 and sprading of the younger phase started shortly...

  12. Analysis of wave directional spreading using neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Deo, M.C.; Gondane, D.S.; SanilKumar, V.

    describes how a representative spreading parameter could be arrived at from easily available wave parameters such as significant wave height and average zero-cross wave period, using the technique of neural networks. It is shown that training of the network...

  13. Don't Get, Don't Spread: Seasonal Flu

    Centers for Disease Control (CDC) Podcasts

    2010-09-29

    In this podcast, Dr. Joe Bresee describes how to keep from getting the seasonal flu and spreading it to others.  Created: 9/29/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/29/2010.

  14. Credit Spread Modeling: Macro-financial versus HOC Approach

    Directory of Open Access Journals (Sweden)

    Sanja Dudaković

    2014-12-01

    Full Text Available The aim of this paper is to throw light on the relationship between credit spread changes and past changes of U.S. macro-financial variables when invariants do not have Gaussian distribution. The first part presents the empirical analysis which is based on 10-year AAA corporate bond yields and 10-year Treasury bond yields. Explanatory variables include lagged U.S. leading index, Russell 2000 returns, BBB bond price changes interest rate swaps, exchange rates EUR/ USD, Repo rates, S& P 500 returns and S&P 500 volatility, Treasury bill changes, liquidity index-TRSW, LIBOR rates, Moody’s default rates; credit spread volatility and Treasury bills volatility. The proposed dynamical model explains 73% of the U.S. credit spread variance for the period 1999:07-2013:07. The second part of the article introduces the parameter estimation method based on higher order cumulants. It is demonstrated empirically that much of the information about variability of Credit Spread can be extracted from higher order cumulant function (85%.

  15. A Spread Willingness Computing-Based Information Dissemination Model

    Science.gov (United States)

    Cui, Zhiming; Zhang, Shukui

    2014-01-01

    This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user's spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network. PMID:25110738

  16. Regional spread of Ebola virus, West Africa, 2014.

    Science.gov (United States)

    Rainisch, Gabriel; Shankar, Manjunath; Wellman, Michael; Merlin, Toby; Meltzer, Martin I

    2015-03-01

    To explain the spread of the 2014 Ebola epidemic in West Africa, and thus help with response planning, we analyzed publicly available data. We found that the risk for infection in an area can be predicted by case counts, population data, and distances between affected and nonaffected areas.

  17. Regional Spread of Ebola Virus, West Africa, 2014

    OpenAIRE

    Rainisch, Gabriel; Shankar, Manjunath; Wellman, Michael; Merlin, Toby; Meltzer, Martin I.

    2015-01-01

    To explain the spread of the 2014 Ebola epidemic in West Africa, and thus help with response planning, we analyzed publicly available data. We found that the risk for infection in an area can be predicted by case counts, population data, and distances between affected and nonaffected areas.

  18. Knowledge of and misconceptions about the spread and prevention ...

    African Journals Online (AJOL)

    Three or more misconceptions were present in 48% of the participants, such as HIV spread by casual contact, the sharing of personal items, air-borne infection, mosquito bites, HIV testing and AIDS prevention or cure by traditional medicines or alternatives. Sixty-two per cent of the older women were found to have adequate ...

  19. A spread willingness computing-based information dissemination model.

    Science.gov (United States)

    Huang, Haojing; Cui, Zhiming; Zhang, Shukui

    2014-01-01

    This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user's spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network.

  20. Drop spreading and penetration into pre-wetted powders

    KAUST Repository

    Marston, Jeremy; Sprittles, James E.; Zhu, Y.; Li, Erqiang; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur T

    2013-01-01

    We present results from an experimental study of the impact of liquid drops onto powder beds which are pre-wetted with the impacting liquid. Using high-speed video imaging, we study both the dynamics of the initial spreading regime and drainage

  1. Determinants of Commercial banks' interest rate spreads in Botswana

    African Journals Online (AJOL)

    The paper investigated the determinants of commercial banks' interest rate spreads in Botswana using time series cross-sectional analysis for the period of 2004Q1 to 2014Q4. Factors empirically tested are bank-specific, industry-specific and macroeconomic data. Results indicate that bank intermediation, GDP, inflation ...

  2. Seafloor spreading magnetic anomalies south off Sri Lanka

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, M.; Ramana, M.V.; Ramprasad, T.

    Cretaceous is estimated to have evolved with variable half-spreading rates ranging from 5.5 to 1.53 cm/yr. The trends of the fracture zones inferred from the offsets in the magnetic anomalies have been constrained using the satellite gravity mosaic...

  3. Determinants of sovereign debt yield spreads under EMU: Pairwise approach

    NARCIS (Netherlands)

    Fazlioglu, S.

    2013-01-01

    This study aims at providing an empirical analysis of long-term determinants of sovereign debt yield spreads under European EMU (Economic and Monetary Union) through pairwise approach within panel framework. Panel gravity models are increasingly used in the cross-market correlation literature while

  4. Information Spreading in Epidemics and in Communication Networks

    DEFF Research Database (Denmark)

    Uekermann, Florian Philipp

    The PhD thesis revolves mainly around models of disease spreading and human behavior. We present models for different epidemic patterns of infectious diseases. This includes investigations of the trajectory of the 2014 Ebola outbreak in West-Africa, influenza evolution and the seasonal dynamics...

  5. Competing spreading processes and immunization in multiplex networks

    International Nuclear Information System (INIS)

    Gao, Bo; Deng, Zhenghong; Zhao, Dawei

    2016-01-01

    Epidemic spreading on physical contact network will naturally introduce the human awareness information diffusion on virtual contact network, and the awareness diffusion will in turn depress the epidemic spreading, thus forming the competing spreading processes of epidemic and awareness in a multiplex networks. In this paper, we study the competing dynamics of epidemic and awareness, both of which follow the SIR process, in a two-layer networks based on microscopic Markov chain approach and numerical simulations. We find that strong capacities of awareness diffusion and self-protection of individuals could lead to a much higher epidemic threshold and a smaller outbreak size. However, the self-awareness of individuals has no obvious effect on the epidemic threshold and outbreak size. In addition, the immunization of the physical contact network under the interplay between of epidemic and awareness spreading is also investigated. The targeted immunization is found performs much better than random immunization, and the awareness diffusion could reduce the immunization threshold for both type of random and targeted immunization significantly.

  6. Competing spreading processes on multiplex networks: awareness and epidemics.

    Science.gov (United States)

    Granell, Clara; Gómez, Sergio; Arenas, Alex

    2014-07-01

    Epidemiclike spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [C. Granell et al., Phys. Rev. Lett. 111, 128701 (2013).] presented an analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the spreading of information awareness to prevent infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease revealed the existence of a metacritical point at which the critical onset of the epidemics starts, depending on completion of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between the two competing processes for a wide spectrum of parameters representing the interaction between them. We also analyze the consequences of a massive broadcast of awareness (mass media) on the final outcome of the epidemic incidence. Importantly enough, the mass media make the metacritical point disappear. The results reveal that the main finding, i.e., existence of a metacritical point, is rooted in the competition principle and holds for a large set of scenarios.

  7. A Spread Willingness Computing-Based Information Dissemination Model

    Directory of Open Access Journals (Sweden)

    Haojing Huang

    2014-01-01

    Full Text Available This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user’s spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network.

  8. Determinants of bond yield spread changes in South Africa | Radier ...

    African Journals Online (AJOL)

    This paper offers an emerging market perspective on the determinants of bond yield spread changes. The study covers the period 2005-2013 and it is based on a sample of 106 corporate vanilla bonds listed on the South African market. To capture the impact of the financial crisis of 2007-2008, the sample period is split into ...

  9. Short range spread-spectrum radiolocation system and method

    Science.gov (United States)

    Smith, Stephen F.

    2003-04-29

    A short range radiolocation system and associated methods that allow the location of an item, such as equipment, containers, pallets, vehicles, or personnel, within a defined area. A small, battery powered, self-contained tag is provided to an item to be located. The tag includes a spread-spectrum transmitter that transmits a spread-spectrum code and identification information. A plurality of receivers positioned about the area receive signals from a transmitting tag. The position of the tag, and hence the item, is located by triangulation. The system employs three different ranging techniques for providing coarse, intermediate, and fine spatial position resolution. Coarse positioning information is provided by use of direct-sequence code phase transmitted as a spread-spectrum signal. Intermediate positioning information is provided by the use of a difference signal transmitted with the direct-sequence spread-spectrum code. Fine positioning information is provided by use of carrier phase measurements. An algorithm is employed to combine the three data sets to provide accurate location measurements.

  10. Point-spread function in depleted and partially depleted CCDs

    International Nuclear Information System (INIS)

    Groom, D.E.; Eberhard, P.H.; Holland, S.E.; Levi, M.E.; Palaio, N.P.; Perlmutter, S.; Stover, R.J.; Wei, M.

    1999-01-01

    The point spread function obtainable in an astronomical instrument using CCD readout is limited by a number of factors, among them the lateral diffusion of charge before it is collected in the potential wells. They study this problem both theoretically and experimentally, with emphasis on the thick CCDs on high-resistivity n-type substrates being developed at Lawrence Berkeley National Laboratory

  11. Ripple-Spreading Network Model Optimization by Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Xiao-Bing Hu

    2013-01-01

    Full Text Available Small-world and scale-free properties are widely acknowledged in many real-world complex network systems, and many network models have been developed to capture these network properties. The ripple-spreading network model (RSNM is a newly reported complex network model, which is inspired by the natural ripple-spreading phenomenon on clam water surface. The RSNM exhibits good potential for describing both spatial and temporal features in the development of many real-world networks where the influence of a few local events spreads out through nodes and then largely determines the final network topology. However, the relationships between ripple-spreading related parameters (RSRPs of RSNM and small-world and scale-free topologies are not as obvious or straightforward as in many other network models. This paper attempts to apply genetic algorithm (GA to tune the values of RSRPs, so that the RSNM may generate these two most important network topologies. The study demonstrates that, once RSRPs are properly tuned by GA, the RSNM is capable of generating both network topologies and therefore has a great flexibility to study many real-world complex network systems.

  12. Potential corridors and barriers for plague spread in central Asia

    Science.gov (United States)

    2013-01-01

    Background Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap. Methods Three 20 by 20 km areas with known great gerbil burrow distributions were used to analyse the spatial distribution of the burrows. Object-based image analysis was used to map the landscape at several scales, and was linked to the burrow maps. A novel object-based method was developed – the mean neighbour absolute burrow density difference (MNABDD) – to identify the optimal scale and evaluate the efficacy of using landscape objects as opposed to square cells. Multiple regression using raster maps was used to identify the landscape-ecological variables that explain burrow density best. Functional corridors and barriers were mapped using burrow density thresholds. Cumulative resistance of the burrow distribution to potential disease spread was evaluated using cost distance analysis. A 46-year plague surveillance dataset was used to evaluate whether plague spread was radially symmetric. Results The burrow distribution was found to be non-random and negatively correlated with Greenness, especially in the floodplain areas. Corridors and

  13. 78 FR 43874 - Texas Eastern Transmission, LP; Notice of Application

    Science.gov (United States)

    2013-07-22

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. CP13-514-000] Texas Eastern Transmission, LP; Notice of Application On July 2, 2013, Texas Eastern Transmission, LP (Texas Eastern) filed... natural gas facilities no longer in service. As described more fully in the Application, Texas Eastern...

  14. 76 FR 7833 - Texas Eastern Transmission, LP; Notice of Application

    Science.gov (United States)

    2011-02-11

    ...] Texas Eastern Transmission, LP; Notice of Application Take notice that on January 25, 2011, Texas Eastern Transmission, LP (Texas Eastern), 5400 Westheimer Court, Houston, Texas 77056, filed in the above... TEAM 2012 Project. Specifically, Texas Eastern requests: (i) Authorization under NGA sections 7(b) and...

  15. Transcultural Memory in Eastern European Migrant Literature

    DEFF Research Database (Denmark)

    Ortner, Jessica

    of the major processes that circulate memories across cultural and national borderlines. This paper will investigate the circulation of memories in Eastern Europe migrant-literature that since 2000 has become an increasingly influential literary tendency in Germany. Articulating an eastern perspective...... consciously follow the mission to “enlighten and inform Western readers about their eastern neighbours” (Haines 2008). Causing an “eastern enlargement” of German literature (Bürger-Koftis 2008), the wave of migrant authors broadens Germany’s cultural memory by supplementing it with “new” memories. Furthermore......The “transcultural turn” of memory studies focuses on the fluid and dynamic aspects of cultural memory. This paper is concerned with the traveling of memories along the paths of migration. As migrants carry along “collective images and narratives of the past” (Erll 2011), migration is one...

  16. Eastern and Southern Africa Seismological Working Group

    International Nuclear Information System (INIS)

    Ogubazghi, G.

    2002-01-01

    Member countries of the Eastern and Southern Africa Seismologica Working Group are listed. The presentation also gives the objectives, activities, date of birth and sponsors of the said ESARSWG. Areas of possible cooperation with CTBTO are indicated

  17. Lateral spread affects nitrogen leaching from urine patches.

    Science.gov (United States)

    Cichota, Rogerio; Vogeler, Iris; Snow, Val; Shepherd, Mark; McAuliffe, Russell; Welten, Brendon

    2018-09-01

    Nitrate leaching from urine deposited by grazing animals is a critical constraint for sustainable dairy farming in New Zealand. While considerable progress has been made to understand the fate of nitrogen (N) under urine patches, little consideration has been given to the spread of urinary N beyond the wetted area. In this study, we modelled the lateral spread of nitrogen from the wetted area of a urine patch to the soil outside the patch using a combination of two process-based models (HYDRUS and APSIM). The simulations provided insights on the extent and temporal pattern for the redistribution of N in the soil following a urine deposition and enabled investigating the effect of lateral spread of urinary N on plant growth and N leaching. The APSIM simulation, using an implementation of a dispersion-diffusion function, was tested against experimental data from a field experiment conducted in spring on a well-drained soil. Depending on the geometry considered for the dispersion-diffusion function (plate or cylindrical) the area-averaged N leaching decreased by 8 and 37% compared with simulations without lateral N spread; this was due to additional N uptake from pasture on the edge area. A sensitivity analysis showed that area-averaged pasture growth was not greatly affected by the value of the dispersion factor used in the model, whereas N leaching was very sensitive. Thus, the need to account for the edge effect may depend on the objective of the simulations. The modelling results also showed that considering lateral spread of urinary N was sufficient to describe the experimental data, but plant root uptake across urine patch zones may still be relevant in other conditions. Although further work is needed for improving accuracy, the simulated and experimental results demonstrate that accounting for the edge effect is important for determining N leaching from urine-affected areas. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Spatial distribution of emissions to air - the SPREAD model

    Energy Technology Data Exchange (ETDEWEB)

    Plejdrup, M S; Gyldenkaerne, S

    2011-04-15

    The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmark's obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously, a distribution on the 17x17 km EMEP grid has been set up and used in research projects combined with detailed distributions for a few sectors or sub-sectors e.g. a distribution for emissions from road traffic on 1x1 km resolution. SPREAD is developed to generate improved spatial emission data for e.g. air quality modelling in exposure studies. SPREAD includes emission distributions for each sector in the Danish inventory system; stationary combustion, mobile sources, fugitive emissions from fuels, industrial processes, solvents and other product use, agriculture and waste. This model enables generation of distributions for single sectors and for a number of sub-sectors and single sources as well. This report documents the methodologies in this first version of SPREAD and presents selected results. Further, a number of potential improvements for later versions of SPREAD are addressed and discussed. (Author)

  19. Spatial distribution of emissions to air - the SPREAD model

    Energy Technology Data Exchange (ETDEWEB)

    Plejdrup, M.S.; Gyldenkaerne, S.

    2011-04-15

    The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmark's obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously, a distribution on the 17x17 km EMEP grid has been set up and used in research projects combined with detailed distributions for a few sectors or sub-sectors e.g. a distribution for emissions from road traffic on 1x1 km resolution. SPREAD is developed to generate improved spatial emission data for e.g. air quality modelling in exposure studies. SPREAD includes emission distributions for each sector in the Danish inventory system; stationary combustion, mobile sources, fugitive emissions from fuels, industrial processes, solvents and other product use, agriculture and waste. This model enables generation of distributions for single sectors and for a number of sub-sectors and single sources as well. This report documents the methodologies in this first version of SPREAD and presents selected results. Further, a number of potential improvements for later versions of SPREAD are addressed and discussed. (Author)

  20. Eastern Canada natural gas developments

    International Nuclear Information System (INIS)

    Wall, A.

    2001-01-01

    This power point presentation addressed the following topics regarding development of natural gas in eastern Canada: (1) the 18 Tcf of proven natural gas reserves at Sable Island, (2) Canadian markets benefiting from the Maritimes and Northeast Pipeline (M and NP), (3) a 20 year franchise agreement between Enbridge Gas and the government of New Brunswick, (4) the 25 year provincial franchise agreement by Sempra Atlantic Gas, and (5) Sable Island's influence on central Canada. The Sable Offshore Energy Project (SOEP) is now producing about 540,000 MMBtu/day from 6 fields. Plans for Tier 2 expansion are underway. Firm contracts for the M and NP are scheduled to transport gas from the SOEP to markets in Nova Scotia, New Brunswick, Maine and New Hampshire. Sable gas is also a potential supply for the Quebec market. Gaz Metropolitain and Enbridge have proposed to build the Cartier Pipeline from the Quebec/New Brunswick border to Quebec City. It is unlikely that Sable Island supply will directly serve the Ontario market. Canadian customers for Sable gas and M and NP service include pulp and paper companies, oil refineries, power generators and local distribution companies (LDC), with the majority of demand coming form the electric power industry. tabs., figs

  1. Eastern countries - WIN activity review

    International Nuclear Information System (INIS)

    Stiopol, Mihaela

    1998-01-01

    Women can play this important role in informing people about nuclear energy. WIN is a world-wide association of women working professionally in the fields of nuclear energy and radiation application who want to devote their time to public information. The main goal of the WIN is to establish an objective and effective communication with the public through educational programmes, information exchange and arranging study visits. The membership includes women working in medicine and health care, in regulatory authorities, in industry and as independent researches at Universities. They want to contribute to objectively informing the public by making presentation, discussing and giving information materials on subjects such as; radiation, radioactivity and health effects medical applications nuclear energy nuclear power plants and their safety nuclear and environment uranium mining radiation protection energy sustainable development WIN is also open to men, supporting the goals of WIN. The intention of this paper was to underline the main aspects which reflect WIN activity in some Eastern and Central countries. There are common features and also specific elements for each country. But the goal is the same: to assure an effective and a real information of the public related to the nuclear field

  2. The energy question in Eastern Europe

    International Nuclear Information System (INIS)

    Locatelli, C.

    1992-01-01

    In a first part, this book describes the energetic schemes, energy consumption and centralized economy in Eastern Europe countries. In the second part, the relationships between energy supply and macro-economic disequilibria in USSR is studied: Petroleum and power generation are chosen as example. In the third part, the book shows the energetic stakes in Central and Eastern Europe: the end of the exchange model (imports, exports) and the energetic schemes facing economical reforms

  3. Midwifery education in Central-Eastern Europe.

    Science.gov (United States)

    Mivšek, Polona; Baškova, Martina; Wilhelmova, Radka

    2016-02-01

    Problems in midwifery in many Central-Eastern European countries are very similar; it is possible to speak about the evolving Central-Eastern model of midwifery care. The educational models of this region have a relatively strong theoretical part; however, there is an insufficient practical dimension. Theoretical part of midwifery education in the universities is relatively autonomous and is slowly changing the professional identity of graduates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Environmental change and Rift Valley fever in eastern Africa: projecting beyond HEALTHY FUTURES

    Directory of Open Access Journals (Sweden)

    David Taylor

    2016-03-01

    Full Text Available Outbreaks of Rift Valley fever (RVF, a relatively recently emerged zoonosis endemic to large parts of sub-Saharan Africa that has the potential to spread beyond the continent, have profound health and socio-economic impacts, particularly in communities where resilience is already low. Here output from a new, dynamic disease model [the Liverpool RVF (LRVF model], driven by downscaled, bias-corrected climate change data from an ensemble of global circulation models from the Inter-Sectoral Impact Model Intercomparison Project run according to two radiative forcing scenarios [representative concentration pathway (RCP4.5 and RCP8.5], is combined with results of a spatial assessment of social vulnerability to the disease in eastern Africa. The combined approach allowed for analyses of spatial and temporal variations in the risk of RVF to the end of the current century. Results for both scenarios highlight the high-risk of future RVF outbreaks, including in parts of eastern Africa to date unaffected by the disease. The results also highlight the risk of spread from/to countries adjacent to the study area, and possibly farther afield, and the value of considering the geography of future projections of disease risk. Based on the results, there is a clear need to remain vigilant and to invest not only in surveillance and early warning systems, but also in addressing the socio-economic factors that underpin social vulnerability in order to mitigate, effectively, future impacts.

  5. Abiotic variables accounting for presence of the exotic rainbow trout (Oncorhynchus mykiss in Eastern Quebec Rivers

    Directory of Open Access Journals (Sweden)

    Thibault I.

    2010-10-01

    Full Text Available Rainbow trout is an exotic fish species that has been introduced in Quebec (Canada since 1893–1894. Despite spatially-restricted stocking for recreational fishing, the species has spread throughout the Saint Lawrence River. In this study, the relationship between rainbow trout occurrence (presence or absence and abiotic variables (river geomorphology and climate was examined for 91 coastal rivers throughout Eastern Quebec in order to determine which variables promote or impede the ongoing invasion process. Results revealed that rainbow trout presence in Eastern Quebec was primarily determined by geomorphological parameters. The invader’s presence was strongly related to the presence of tributaries (especially larger ones. To a lesser extent, the presence of rainbow trout was positively related to warm spring and summer temperatures and negatively related to the peak flood date occurring during the egg deposition period (May. This study proposes a parsimonious modelling approach to identify which environmental parameters favour the spreading of an invader, even when a limited dataset is available due to the incomplete invasion process.

  6. Spread ability of diamondblack moth (Plutella xylotella L) steriled by irradiation

    International Nuclear Information System (INIS)

    Yang Rongxin; Fang Julian; Xia Darong; Chu Jiming; Feng Chunsheng

    1990-01-01

    The spread ability of the radiation steriled diamondblack moth (DBM) is reported. It shows that the 94.2% of DBM is spread in 40 m duration of 10 days and a few of moths are 120 m. It indicates that the spread of steriled DBM is definitely time limit, the spread area is withinca. 700 m 2 in the first three days

  7. RECOGNIZE: A Social Norms Campaign to Reduce Rumor Spreading in a Junior High School

    Science.gov (United States)

    Cross, Jennifer E.; Peisner, William

    2009-01-01

    This article studied changes in rumor spreading and perceptions of peers' rumor spreading among students at one public junior high school following a social norms marketing campaign. Results of the study show that perceptions of peer rumor spreading fell following the campaign, but self-reports of rumor spreading did not decrease. Results suggest…

  8. 75 FR 68397 - DeQueen and Eastern Railroad, LLC-Acquisition and Operation Exemption-DeQueen and Eastern...

    Science.gov (United States)

    2010-11-05

    ... Eastern Railroad, LLC--Acquisition and Operation Exemption--DeQueen and Eastern Railroad Company DeQueen and Eastern Railroad, LLC (DQE), a noncarrier, has filed a verified notice of exemption under 49 CFR 1150.31 to acquire from DeQueen and Eastern Railroad Company and to operate approximately 47 miles of...

  9. Spread of porcine circovirus associated disease (PCVAD in Ontario (Canada swine herds: Part I. Exploratory spatial analysis

    Directory of Open Access Journals (Sweden)

    Young Beth

    2010-12-01

    Full Text Available Abstract Background The systemic form of porcine circovirus associated disease (PCVAD, also known as postweaning multisystemic wasting syndrome (PMWS was initially detected in the early 1990s. Starting in 2004, the Canadian swine industry experienced considerable losses due to PCVAD, concurrent with a shift in genotype of porcine circovirus type 2 (PCV2. Objectives of the current study were to explore spatial characteristics of self-reported PCVAD distribution in Ontario between 2004 and 2008, and to investigate the existence and nature of local spread. Results The study included 278 swine herds from a large disease-monitoring project that included porcine reproductive and respiratory syndrome (PRRS virus-positive herds identified by the diagnostic laboratory, and PRRS virus-negative herds directly from the target population. Herds were included if they had growing pigs present on-site and available geographical coordinates for the sampling site. Furthermore, herds were defined as PCVAD-positive if a producer reported an outbreak of circovirus associated disease, or as PCVAD-negative if no outbreak was noted. Spatial trend was investigated using generalized additive models and time to PCVAD outbreak in a herd using Cox's proportional hazard model; spatial and spatio-temporal clustering was explored using K-functions; and location of most likely spatial and spatio-temporal clusters was investigated using scan statistics. Over the study period, the risk of reporting a PCVAD-positive herd tended to be higher in the eastern part of the province after adjustment for herd PRRS status (P = 0.05. This was partly confirmed for spread (Partial P P = 0.06 existence of spatio-temporal clustering of PCVAD and detection of a spatio-temporal cluster (P = 0.04. Conclusions In Ontario, PCVAD has shown a general trend, spreading from east-to-west. We interpret the existence of spatio-temporal clustering as evidence of spatio-temporal aggregation of PCVAD

  10. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  11. Weather Effects on Crop Diseases in Eastern Germany

    Science.gov (United States)

    Conradt, Tobias

    2017-04-01

    Since the 1970s there are several long-term monitoring programmes for plant diseases and pests in Germany. Within the framework of a national research project, some otherwise confidential databases comprising 77 111 samples from numerous sites accross Eastern Germany could be accessed and analysed. The pest data covered leaf rust (Puccinia triticina) and powdery mildew (Blumeria graminis) in winter wheat, aphids (Aphididae, four genera) on wheat and other cereal crops, late blight (Phytophthora infestans) in potatoes, and pollen beetles (Brassicogethes aeneus) on rape. These data were complemented by daily weather observations from the German Weather Service (DWD). In a first step, Pearson correlations between weather variables and pest frequencies were calculated for seasonal time periods of different start months and durations and ordered into so-called correlograms. This revealed principal weather effects on disease spread - e. g. that wind is favourable for mildew throughout the year or that rape pollen beetles like it warm, but not during wintertime. Secondly, the pest frequency samples were found to resemble gamma distributions, and a generalised linear model was fitted to describe their parameter shift depending on end-of-winter temperatures for aphids on cereals. The method clearly shows potential for systematic pest risk assessments regarding climate change.

  12. Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France.

    Directory of Open Access Journals (Sweden)

    Thomas eGuillard

    2015-10-01

    Full Text Available Fluoroquinolone (FQ agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE and multilocus sequence typing (MLST.Among them, 14.7% (12/75 carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75 harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75. The MLST study revealed that E. cloacae isolates’ clonality was wide (24 different STs. The more widespread STs were ST74, ST101, ST110, ST114 and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. PMQR determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i pOXA-48a is spreading in North-Eastern France, (ii qnr is preponderant in E. cloacae, (iii E. cloacae comprised a large amount of lineages spreading in North-Eastern France and (iv FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised.

  13. 137 Caesium distribution in the eastern Mediterranean Sea. Recent changes and future trends

    International Nuclear Information System (INIS)

    Papucci, C.; Delfanti, R.

    1999-01-01

    A series of sampling campaigns were carried out in the eastern Mediterranean in the period 1995-1997, to examine the relationship between the distribution of 137Cs in the water column and water mass circulation. 137Cs concentration in the surface water ranges between 3.3 and 4.0 mBq/l all over the area, indicating that the input due to the Chernobyl accident has been transferred to deep water layers by convection processes. In fact, in the vertical profiles, relative maxima are observed in the intermediate (4 mBq/l) and deep waters (∼2.5 mBq/l) formed after the Chernobyl accident. A clear Chernobyl signal also traces the new deep waters formed in the Aegean Sea that, exiting from the Cretan Arc Straits, since 1991 are spreading in the bottom layer of the eastern Mediterranean. The changes in 137Cs vertical profiles related to the new thermohaline circulation of the intermediate and deep waters of the eastern Mediterranean are being monitored at a deep station in the western Ionian Sea. The 1997 profile shows a decrease in 137Cs concentration both in the Levantine intermediate water and in the eastern Mediterranean deep water with respect to 1996. The decrease in Levantine intermediate water is likely due to seasonal/interannual variability, while the changes in the deep layer are related to the spreading westward into the Ionian of the new Aegean dense water. Along the path towards the western Mediterranean, 137Cs content in the Levantine intermediate water decreases from ∼4 mBq/l in the W-Ionian Sea to ∼2 mBq/l at the western sill of the Sicily Straits, due to mixing with underlying water, with lower caesium content, near the Malta Sill. Time-series measurements at the western sill of the Sicily Straits show that, while 137Cs concentration in the surface water entering the eastern Mediterranean remained constant (∼3.5 mBq/l) in the period 1993-1997, its level in the Levantine intermediate water leaving the basin decreased from 3.5 to 2.0 mBq/l

  14. Partial genetic characterization of peste des petits ruminants virus from goats in northern and eastern Tanzania.

    Science.gov (United States)

    Kgotlele, T; Macha, E S; Kasanga, C J; Kusiluka, L J M; Karimuribo, E D; Van Doorsselaere, J; Wensman, J J; Munir, M; Misinzo, G

    2014-08-01

    Peste des petits ruminants (PPR) is an acute viral disease of small ruminants. The disease was first reported in Tanzania in 2008 when it was confined to the Northern Zone districts bordering Kenya. The present study was carried out to confirm the presence of PPR virus (PPRV) in Tanzania and to establish their phylogenetic relationships. Samples (oculonasal swabs, tissues and whole blood) were obtained from live goats with clinical presentation suggestive of PPR and goats that died naturally in Ngorongoro (Northern Tanzania) and Mvomero (Eastern Tanzania) districts. The clinical signs observed in goats suspected with PPR included fever, dullness, diarrhea, lacrimation, matting of eye lids, purulent oculonasal discharges, cutaneous nodules, erosions on the soft palate and gums and labored breathing. Post mortem findings included pneumonia, congestion of the intestines, and hemorrhages in lymph nodes associated with the respiratory and gastrointestinal systems. PPRV was detected in 21 out of 71 tested animals using primers targeting the nucleoprotein (N) gene. Phylogenetic analysis, based on the N gene, indicated that PPRV obtained from Northern and Eastern Tanzania clustered with PPRV strains of Lineage III, together with PPRV from Sudan and Ethiopia. The findings of this study indicate that there are active PPRV infections in Northern and Eastern Tanzania, suggesting risks for potential spread of PPR in the rest of Tanzania. © 2014 The Authors. Transboundary and Emerging Diseases Published by Blackwell Verlag GmbH.

  15. Glazed pottery of the South-Eastern Crimea from the excavations of the Tsarev settlement

    Directory of Open Access Journals (Sweden)

    Iudin Nikita I.

    2015-09-01

    Full Text Available The article deals with the findings of glazed ceramics produced in the South-Eastern Crimea, and then excavated at the Tsarev settlement. Their typology, chronology and topography are being introduced by the author. On the basis of the 165 analyzed fragments and whole vessels the author suggests a 4-level classification scheme, which includes the production center, functional purpose of the items, morphological characteristics and ornamentation of the vessels. Basic types and variations of vessels’ shapes are being described according to three major chronological periods: 1. Early 1300s, 2. 1330s, 3. The second half of the 14th century. Notably, the earliest findings of ceramics dated by the first two periods were located on the South-Eastern part of the Tsarev settlement. Most of all, its are the bowls on a circular underpan lacking ornamentation and covered with green transparent glazing. Since the second half of the 14th century the vessels from the South-Eastern Crimea had been widely spread on the entire area of the settlement. The assortment of vessels’ shapes used at this time along with jars and bowls, was now widened by aftobes and apothecary amphoras.

  16. Local and Regional Spread of Primary Conjunctival Squamous Cell Carcinoma.

    Science.gov (United States)

    Desai, Shilpa J; Pruzan, Noelle L; Geske, Michael J; Jeng, Bennie H; Bloomer, Michele M; Vagefi, M Reza

    2016-04-06

    Two cases of biopsy-proven conjunctival squamous cell carcinoma (SCC) that developed local and regional spread are described. The cases involved a 65-year-old woman and a 79-year-old man who were initially treated at outside institutions for SCC of the conjunctiva. The patients did not have a history of immune compromise. The female patient presented with direct extension into the lacrimal gland but deferred recommended exenteration. Despite eventual exenteration, she developed metastasis to a neck node 6 months later, which was treated with radiotherapy. The male patient presented with local recurrence and a parotid node metastasis treated with exenteration, parotidectomy, selective neck dissection, and postoperative radiotherapy. Review of the outside pathology of both cases revealed positive tumor margins at the time of original resection. Local control of conjunctival SCC is of critical importance to reduce the risk of orbital extension and regional spread.

  17. Dynamical Interplay between Awareness and Epidemic Spreading in Multiplex Networks

    Science.gov (United States)

    Granell, Clara; Gómez, Sergio; Arenas, Alex

    2013-09-01

    We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases.

  18. Dynamical interplay between awareness and epidemic spreading in multiplex networks.

    Science.gov (United States)

    Granell, Clara; Gómez, Sergio; Arenas, Alex

    2013-09-20

    We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases.

  19. Performance Spread of Re-entrant System Structures

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2001-01-01

    and even spreads indicate a situation where the priority policy has a clear tendency often to induce severe virtual bottlenecks into the system at hand, resulting in poor performance. The findings, in summary, are as follows. Almost every priority scheme examined in this simulation study showed...... way to assess the relevance of bad performance structures could then be to simulate a number of scenarios based on a variety of priority policies, different number of machines and job-classes, and let the structure of the job-routes and process times be chosen randomly within the system's realistic...... capabilities. Individual machine utilisation is arbitrarily set to 80% in this study. Each scenario is replicated a 1000 times and the measure used to evaluate the system's performance is the total batch throughput time based on 5000 processed units. It is the spread of this measure that is of interest. Large...

  20. Wet climate and transportation routes accelerate spread of human plague

    Science.gov (United States)

    Xu, Lei; Stige, Leif Chr.; Kausrud, Kyrre Linné; Ben Ari, Tamara; Wang, Shuchun; Fang, Xiye; Schmid, Boris V.; Liu, Qiyong; Stenseth, Nils Chr.; Zhang, Zhibin

    2014-01-01

    Currently, large-scale transmissions of infectious diseases are becoming more closely associated with accelerated globalization and climate change, but quantitative analyses are still rare. By using an extensive dataset consisting of date and location of cases for the third plague pandemic from 1772 to 1964 in China and a novel method (nearest neighbour approach) which deals with both short- and long-distance transmissions, we found the presence of major roads, rivers and coastline accelerated the spread of plague and shaped the transmission patterns. We found that plague spread velocity was positively associated with wet conditions (measured by an index of drought and flood events) in China, probably due to flood-driven transmission by people or rodents. Our study provides new insights on transmission patterns and possible mechanisms behind variability in transmission speed, with implications for prevention and control measures. The methodology may also be applicable to studies of disease dynamics or species movement in other systems. PMID:24523275

  1. a Discrete Mathematical Model to Simulate Malware Spreading

    Science.gov (United States)

    Del Rey, A. Martin; Sánchez, G. Rodriguez

    2012-10-01

    With the advent and worldwide development of Internet, the study and control of malware spreading has become very important. In this sense, some mathematical models to simulate malware propagation have been proposed in the scientific literature, and usually they are based on differential equations exploiting the similarities with mathematical epidemiology. The great majority of these models study the behavior of a particular type of malware called computer worms; indeed, to the best of our knowledge, no model has been proposed to simulate the spreading of a computer virus (the traditional type of malware which differs from computer worms in several aspects). In this sense, the purpose of this work is to introduce a new mathematical model not based on continuous mathematics tools but on discrete ones, to analyze and study the epidemic behavior of computer virus. Specifically, cellular automata are used in order to design such model.

  2. Spreading of correlations in the Falicov-Kimball model

    Science.gov (United States)

    Herrmann, Andreas J.; Antipov, Andrey E.; Werner, Philipp

    2018-04-01

    We study dynamical properties of the one- and two-dimensional Falicov-Kimball model using lattice Monte Carlo simulations. In particular, we calculate the spreading of charge correlations in the equilibrium model and after an interaction quench. The results show a reduction of the light-cone velocity with interaction strength at low temperature, while the phase velocity increases. At higher temperature, the initial spreading is determined by the Fermi velocity of the noninteracting system and the maximum range of the correlations decreases with increasing interaction strength. Charge order correlations in the disorder potential enhance the range of the correlations. We also use the numerically exact lattice Monte Carlo results to benchmark the accuracy of equilibrium and nonequilibrium dynamical cluster approximation calculations. It is shown that the bias introduced by the mapping to a periodized cluster is substantial, and that from a numerical point of view, it is more efficient to simulate the lattice model directly.

  3. Epidemic spreading between two coupled subpopulations with inner structures

    Science.gov (United States)

    Ruan, Zhongyuan; Tang, Ming; Gu, Changgui; Xu, Jinshan

    2017-10-01

    The structure of underlying contact network and the mobility of agents are two decisive factors for epidemic spreading in reality. Here, we study a model consisting of two coupled subpopulations with intra-structures that emphasizes both the contact structure and the recurrent mobility pattern of individuals simultaneously. We show that the coupling of the two subpopulations (via interconnections between them and round trips of individuals) makes the epidemic threshold in each subnetwork to be the same. Moreover, we find that the interconnection probability between two subpopulations and the travel rate are important factors for spreading dynamics. In particular, as a function of interconnection probability, the epidemic threshold in each subpopulation decreases monotonously, which enhances the risks of an epidemic. While the epidemic threshold displays a non-monotonic variation as travel rate increases. Moreover, the asymptotic infected density as a function of travel rate in each subpopulation behaves differently depending on the interconnection probability.

  4. HF band filter bank multi-carrier spread spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Laraway, Stephen Andrew; Moradi, Hussein; Farhang-Boroujeny, Behrouz

    2015-10-01

    Abstract—This paper describes modifications to the filter bank multicarrier spread spectrum (FB-MC-SS) system, that was presented in [1] and [2], to enable transmission of this waveform in the HF skywave channel. FB-MC-SS is well suited for the HF channel because it performs well in channels with frequency selective fading and interference. This paper describes new algorithms for packet detection, timing recovery and equalization that are suitable for the HF channel. Also, an algorithm for optimizing the peak to average power ratio (PAPR) of the FBMC- SS waveform is presented. Application of this algorithm results in a waveform with low PAPR. Simulation results using a wide band HF channel model demonstrate the robustness of this system over a wide range of delay and Doppler spreads.

  5. Digital hf radar observations of equatorial spread-F

    International Nuclear Information System (INIS)

    Argo, P.E.

    1984-01-01

    Modern digital ionosondes, with both direction finding and doppler capabilities can provide large scale pictures of the Spread-F irregularity regions. A morphological framework has been developed that allows interpretation of the hf radar data. A large scale irregularity structure is found to be nightward of the dusk terminator, stationary in the solar reference frame. As the plasma moves through this foehn-wall-like structure it descends, and irregularities may be generated. Localized upwellings, or bubbles, may be produced, and they drift with the background plasma. The spread-F irregularity region is found to be best characterized as a partly cloudy sky, due to the patchiness of the substructures. 13 references, 16 figures

  6. Design of Spreading-Codes-Assisted Active Imaging System

    Directory of Open Access Journals (Sweden)

    Alexey Volkov

    2015-07-01

    Full Text Available This work discusses an innovative approach to imaging which can improve the robustness of existing active-range measurement methods and potentially enhance their use in a variety of outdoor applications. By merging a proven modulation technique from the domain of spread-spectrum communications with the bleeding-edge CMOS sensor technology, the prototype of the modulated range sensor is designed and evaluated. A suitable set of application-specific spreading codes is proposed, evaluated and tested on the prototype. Experimental results show that the introduced modulation technique significantly reduces the impacts of environmental factors such as sunlight and external light sources, as well as mutual interference of identical devices. The proposed approach can be considered as a promising basis for a new generation of robust and cost-efficient range-sensing solutions for automotive applications, autonomous vehicles or robots.

  7. Mathematical analysis of dynamic spread of Pine Wilt disease.

    Science.gov (United States)

    Dimitrijevic, D D; Bacic, J

    2013-01-01

    Since its detection in Portugal in 1999, the pinewood nematode Bursaphelenchus xylophilus (Steiner and Buhrer), a causal agent of Pine Wilt Disease, represents a threat to European forestry. Significant amount of money has been spent on its monitoring and eradication. This paper presents mathematical analysis of spread of pine wilt disease using a set of partial differential equations with space (longitude and latitude) and time as parameters of estimated spread of disease. This methodology can be used to evaluate risk of various assumed entry points of disease and make defense plans in advance. In case of an already existing outbreak, it can be used to draw optimal line of defense and plan removal of trees. Optimization constraints are economic loss of removal of susceptible trees as well as budgetary constraints of workforce cost.

  8. Collective behavior in the spatial spreading of obesity

    Science.gov (United States)

    Gallos, Lazaros K.; Barttfeld, Pablo; Havlin, Shlomo; Sigman, Mariano; Makse, Hernán A.

    2012-06-01

    Obesity prevalence is increasing in many countries at alarming levels. A difficulty in the conception of policies to reverse these trends is the identification of the drivers behind the obesity epidemics. Here, we implement a spatial spreading analysis to investigate whether obesity shows spatial correlations, revealing the effect of collective and global factors acting above individual choices. We find a regularity in the spatial fluctuations of their prevalence revealed by a pattern of scale-free long-range correlations. The fluctuations are anomalous, deviating in a fundamental way from the weaker correlations found in the underlying population distribution indicating the presence of collective behavior, i.e., individual habits may have negligible influence in shaping the patterns of spreading. Interestingly, we find the same scale-free correlations in economic activities associated with food production. These results motivate future interventions to investigate the causality of this relation providing guidance for the implementation of preventive health policies.

  9. Spread spectrum mobile communication experiment using ETS-V satellite

    Science.gov (United States)

    Ikegami, Tetsushi; Suzuki, Ryutaro; Kadowaki, Naoto; Taira, Shinichi; Sato, Nobuyasu

    1990-01-01

    The spread spectrum technique is attractive for application to mobile satellite communications, because of its random access capability, immunity to inter-system interference, and robustness to overloading. A novel direct sequence spread spectrum communication equipment is developed for land mobile satellite applications. The equipment is developed based on a matched filter technique to improve the initial acquisition performance. The data rate is 2.4 kilobits per sec. and the PN clock rate is 2.4552 mega-Hz. This equipment also has a function of measuring the multipath delay profile of land mobile satellite channel, making use of a correlation property of a PN code. This paper gives an outline of the equipment and the field test results with ETS-V satellite.

  10. Influence of livestock markets on the spread of FMD

    DEFF Research Database (Denmark)

    Boklund, Anette; Hisham Beshara Halasa, Tariq; Christiansen, Lasse Engbo

    2012-01-01

    The purpose of this study was to investigate, whether cattle markets would influence the duration, size and economic consequences of a potential FMD epidemic in Denmark. The spread of FMD was simulated using the InterSpread Plus. For movements of cattle to and from markets, we modeled the frequency...... of movements to markets for the individual herd and categorized herds that could receive contacts from markets. The epidemics were initiated in herds with market contacts. In a basic market scenario, we used the individual herds’ probability of moving animals to markets, while in a control scenario we reduced...... all probabilities of movements to markets to zero, to reflect a situation with no markets. Each scenario was initiated in 386 different herds (index), and for each index herd, the model was run 100 times. The number of extra contacts generated through a market was set to 3.5 and the probability...

  11. Temporal percolation of the susceptible network in an epidemic spreading.

    Science.gov (United States)

    Valdez, Lucas Daniel; Macri, Pablo Alejandro; Braunstein, Lidia Adriana

    2012-01-01

    In this work, we study the evolution of the susceptible individuals during the spread of an epidemic modeled by the susceptible-infected-recovered (SIR) process spreading on the top of complex networks. Using an edge-based compartmental approach and percolation tools, we find that a time-dependent quantity ΦS(t), namely, the probability that a given neighbor of a node is susceptible at time t, is the control parameter of a node void percolation process involving those nodes on the network not-reached by the disease. We show that there exists a critical time t(c) above which the giant susceptible component is destroyed. As a consequence, in order to preserve a macroscopic connected fraction of the network composed by healthy individuals which guarantee its functionality, any mitigation strategy should be implemented before this critical time t(c). Our theoretical results are confirmed by extensive simulations of the SIR process.

  12. REGIME SWITCHING DETERMINANTS OF SOVEREIGN CDS SPREADS: EVIDENCE FROM TURKEY

    Directory of Open Access Journals (Sweden)

    Umurcan Polat

    2017-12-01

    Full Text Available In this study, it is assessed the main determinants of sovereign CDS spreads in Turkey from January 2006 to December 2015. Before delving into the nonlinear Markov regime-switching model estimation, a conventional one-state linear model is estimated answering to what extent the sovereign credit risk is affected in between global and country-specific market variables and by credit ratings announcement changes. In broad strokes, the regime-switching analysis reveals that among domestic variables, it is the foreign exchange rate that affects the sovereign credit risk more in more volatile periods and among global variables, the indicators standing for global volatility risk premiums and international liquidity primarily influence the changes in the sovereign CDS spread in turbulent regimes whereas proxies for global risk free rate are significant more in tranquil regimes.

  13. Diffuse spreading of inhomogeneities in the ionospheric dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shalimov, S. L., E-mail: pmsk7@mail.ru [Russian Academy of Sciences, Schmidt Institute of Physics of the Earth (Russian Federation); Kozlovsky, A. [Sodankylä Geophysical Observatory (Finland)

    2015-08-15

    According to results of sounding of the lower ionosphere at altitudes of about 100 km, the duration of radio reflections from sufficiently dense ionized meteor trails, which characterizes their lifetime, can reach a few tens of seconds to several tens of minutes. This is much longer than the characteristic spreading time (on the order of fractions of a second to several seconds) typical in meteor radar measurements. The presence of dust in the lower ionosphere is shown to affect the ambipolar diffusion coefficient, which determines the spreading of plasma inhomogeneities. It is found that the diffusion coefficient depends substantially on the charge and size of dust grains, which allows one to explain the results of ionospheric sounding.

  14. A Finsler geodesic spray paradigm for wildfire spread modelling

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    2015-01-01

    represents the local fire templates. The ‘paradigm’ part of the present proposal is thus concerned with the corresponding shift of attention from the actual fire-lines to consider instead the geodesic spray - the ‘fire-particles’ - which together, side by side, mold the fire-lines at each instant of time...... and thence eventually constitute the local and global structure of the wildfire spread....

  15. Fire spread simulation of a full scale cable tunnel

    International Nuclear Information System (INIS)

    Huhtanen, R.

    1999-11-01

    A fire simulation of a full scale tunnel was performed by using the commercial code EFFLUENT as the simulation platform. Estimation was made for fire spread on the stacked cable trays, possibility of fire spread to the cable trays on the opposite wall of the tunnel, detection time of smoke detectors in the smouldering phase and response of sprinkler heads in the flaming phase. According to the simulation, the rise of temperature in the smouldering phase is minimal, only of the order 1 deg C. The estimates of optical density of smoke show that normal smoke detectors should give an alarm within 2-4 minutes from the beginning of the smouldering phase, depending on the distance to the detector (in this case it was assumed that the thermal source connected to the smoke source was 50 W). The flow conditions at smoke detectors may be challenging, because the velocity magnitude is rather low at this phase. At 4 minutes the maximum velocity at the detectors is 0.12 m/s. During the flaming phase (beginning from 11 minutes) fire spreads on the stacked cable trays in an expected way, although the ignition criterion seems to perform poorly when ignition of new objects is considered. The Upper cable trays are forced to ignite by boundary condition definitions according to the experience found from ti full scale experiment and an earlier simulation. After 30 minutes the hot layer in the room becomes so hot that it speeds up the fire spread and the rate of heat release of burning objects. Further, the hot layer ignites the cable trays on the opposite wall of the tunnel after 45 minutes. It is estimated that the sprinkler heads would be activated at 20-22 minutes near the fire source and at 24-28 minutes little further from the fire source when fast sprinkler heads are used. The slow heads are activated between 26-32 minutes. (orig.)

  16. Corium spreading issue; Le corium et son etalement

    Energy Technology Data Exchange (ETDEWEB)

    Cognet, G.; Brayer, C.; Cranga, M.; Journeau, C.; Laffont, G.; Splinder, B.; Veteau, J.M. [CEA Grenoble, Dept. de Thermohydraulique et de Physique (DPT), 38 (France)

    1999-07-01

    Safety is one of the major issues for nuclear power plants; its improvement is a constant R and D axis for the CEA. In the event of a highly unlikely core melt-down accident in Light Water Reactors, the Safety Authorities of several EU countries have requested the industries and utilities to consider severe accidents with reactor pressure vessel failure for the design of the next generation of nuclear power plants. The objective is to preserve the integrity of the containment as the main barrier of fission product release to the environment. This can only be achieved if the core melt mixture (called corium, essentially composed of UO{sub 2}, ZrO{sub 2}, Zr, Fe and fission products) is stabilized before it can penetrate the basement. Consequently, various core-catcher concepts are under investigation for future reactors in order to prevent basement erosion, and to stabilize and control the corium within the containment. In particular, in the EPR (European Pressurized Reactor) core-catcher concept, the corium is mixed with a special concrete, and the molten mixture spread over a large multi-layer surface cooled from the bottom; with subsequent cooling by flooding with water. Therefore, melt spreading requires intensive investigation in order to determine and quantify the key phenomena, which govern the spreading. For some years now, the Nuclear Reactor Division of the Atomic Energy Commission (CEA/DRN) has been conducting a large program to improve knowledge on corium behaviour and coolability. This program is based on experimental (with simulant and prototypic materials) and theoretical investigations, which are finally gathered into scenario and mechanistic computer codes. Within this framework, a large part is currently devoted to the study of corium spreading. After a reminder of the general objectives and a description of the DRn approach and facilities, this paper presents the most important results. (authors)

  17. Effect of pollutant oscillations on oil spreading on the sea

    International Nuclear Information System (INIS)

    Abbey, T.M.; Amakiri, J.O.; Bestman, A.R.

    1997-01-01

    Analytical solutions for oil spreading on the sea are deduced when the pollutant source fluctuates with time for a simple rectangular geometry. Both asymmetrical and symmetrical solutions in the direction perpendicular to the uniform tidal stream are derived. The asymmetrical solution, though ad hoc, sheds light on the necessary adjustment to the simpler symmetric problem. Only a micro computer is necessary to simulate these solutions. (Author)

  18. Modeling of Ceiling Fire Spread and Thermal Radiation.

    Science.gov (United States)

    1981-10-01

    under a PMMA ceiling and flame lengths under an inert ceiling are found to be in reasonable agreement with full-scale behavior. Although fire spread...5 3 Flame Lengths under Full-Scale Ceilings 12 4 Correlation of Flame Length under Inert Ceilings 16 5 Correlation of Flame Length under No 234 Model...Ceilings 17 6 Correlation of Flame Length under No B8811 Model Ceilings 18 7 Correlation of Flame Length under No. 223 Model Ceilings 19 8

  19. Multiscale analysis of spreading in a large communication network

    International Nuclear Information System (INIS)

    Kivelä, Mikko; Pan, Raj Kumar; Kaski, Kimmo; Kertész, János; Saramäki, Jari; Karsai, Márton

    2012-01-01

    In temporal networks, both the topology of the underlying network and the timings of interaction events can be crucial in determining how a dynamic process mediated by the network unfolds. We have explored the limiting case of the speed of spreading in the SI model, set up such that an event between an infectious and a susceptible individual always transmits the infection. The speed of this process sets an upper bound for the speed of any dynamic process that is mediated through the interaction events of the network. With the help of temporal networks derived from large-scale time-stamped data on mobile phone calls, we extend earlier results that indicate the slowing-down effects of burstiness and temporal inhomogeneities. In such networks, links are not permanently active, but dynamic processes are mediated by recurrent events taking place on the links at specific points in time. We perform a multiscale analysis and pinpoint the importance of the timings of event sequences on individual links, their correlations with neighboring sequences, and the temporal pathways taken by the network-scale spreading process. This is achieved by studying empirically and analytically different characteristic relay times of links, relevant to the respective scales, and a set of temporal reference models that allow for removing selected time-domain correlations one by one. Our analysis shows that for the spreading velocity, time-domain inhomogeneities are as important as the network topology, which indicates the need to take time-domain information into account when studying spreading dynamics. In particular, results for the different characteristic relay times underline the importance of the burstiness of individual links

  20. Temperature dependence of spreading width of giant dipole resonance

    International Nuclear Information System (INIS)

    Storozhenko, A.N.; Vdovin, A.I.; Ventura, A.; Blokhin, A.I.

    2002-01-01

    The Quasiparticle-Phonon Nuclear Model extended to finite temperature within the framework of Thermo Field Dynamics is applied to calculate a temperature dependence of the spreading width Γ ↓ of a giant dipole resonance. Numerical calculations are made for 120 Sn and 208 Pb nuclei. It is found that Γ ↓ increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones, existing in the literature