822 research outputs found

    Search in weighted complex networks

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    We study trade-offs presented by local search algorithms in complex networks which are heterogeneous in edge weights and node degree. We show that search based on a network measure, local betweenness centrality (LBC), utilizes the heterogeneity of both node degrees and edge weights to perform the best in scale-free weighted networks. The search based on LBC is universal and performs well in a large class of complex networks.Comment: 14 pages, 5 figures, 4 tables, minor changes, added a referenc

    ES11MA110N OF GLOBAL WARMING DAMAGE COST DUE TO THE FOREST RRES IN THE IMBULPE DIVISIONAL SECRETARIAT DIVISION, 2003 IN SRI LANKA

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    The objective of the study was to estimate the global warming damage costs caused byman made catastrophic forest fires in the Imbulpe divisional secretariat division (23140ha), Balangoda electorate in the Ratnapura district in Sri Lanka in 2003. The climaticforest fires occur every year during the period June to mid October in this area, creatingnumerous environmental and socio-economic problems such as declining of water table,extinction of endemic flora and fauna species, loss of bio diversity and pollution of air,water, and land and occasionally rendering people homeless. Even though the gravity ofthose forest fires in this region every year was devastating, the majority of the researchersdid not take this aspect into their consideration.Hence to combat this menace the Sabaragamuwa University Centre for Environment andSustainable Development (SUCEDS) had launched a number of projects since 2000 andthe current study is one such project. To accomplish this task primary data (forest fireaffected land areas and types of forests) were collected by means of household surveysand land surveying techniques. In addition to that maps and previous reports pertainingto the area were used to obtain secondary data (land use types, population of that area,endemic plant species). Determination of the extent of burnt land of diverse types and theconsideration of catastrophic forest fires caused in the Imbulpe area were identified using1:50000 map. The estimation of the global warming damage cost of the burnt area wascarried out by carbon Sequestration value of the burnt forest in the Imbulpe area by theTurner's (1994) value of $20. This value has been suggested as the financial damagecaused by every ton of carbon released from burning tropical rain forests, whichcontributes the global warming. The estimated global warming damage costs based onlost carbon sequestration function was Rs. 126.5 millionFurther this research disclosed that the main reasons for such fires were fires set out forunknown reasons, fires to prepare fresh grazing land for cattle feeding, hunters also setfire to forests for poaching of wild animals, fires caused by butt-ends of cigarettes andfires set to clear virgin forests for agricultural purposes.

    Hidden magnetic states emergent under electric field, in a room temperature composite magnetoelectric multiferroic

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    The ability to control a magnetic phase with an electric field is of great current interest for a variety of low power electronics in which the magnetic state is used either for information storage or logic operations. Over the past several years, there has been a considerable amount of research on pathways to control the direction of magnetization with an electric field. More recently, an alternative pathway involving the change of the magnetic state (ferromagnet to antiferromagnet) has been proposed. In this paper, we demonstrate electric field control of the Anomalous Hall Transport in a metamagnetic FeRh thin film, accompanying an antiferromagnet (AFM) to ferromagnet (FM) phase transition. This approach provides us with a pathway to "hide" or "reveal" a given ferromagnetic region at zero magnetic field. By converting the AFM phase into the FM phase, the stray field, and hence sensitivity to external fields, is decreased or eliminated. Using detailed structural analyses of FeRh films of varying crystalline quality and chemical order, we relate the direct nanoscale origins of this memory effect to site disorder as well as variations of the net magnetic anisotropy of FM nuclei. Our work opens pathways toward a new generation of antiferromagnetic - ferromagnetic interactions for spintronics

    Boreal forest soil carbon fluxes one year after a wildfire: Effects of burn severity and management

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    The extreme 2018 hot drought that affected central and northern Europe led to the worst wildfire season in Sweden in over a century. The Ljusdal fire complex, the largest area burnt that year (8995 ha), offered a rare opportunity to quantify the combined impacts of wildfire and post-fire management on Scandinavian boreal forests. We present chamber measurements of soil CO2 and CH4 fluxes, soil microclimate and nutrient content from five Pinus sylvestris sites for the first growing season after the fire. We analysed the effects of three factors on forest soils: burn severity, salvage-logging and stand age. None of these caused significant differences in soil CH4 uptake. Soil respiration, however, declined significantly after a high-severity fire (complete tree mortality) but not after a low-severity fire (no tree mortality), despite substantial losses of the organic layer. Tree root respiration is thus key in determining post-fire soil CO2 emissions and may benefit, along with heterotrophic respiration, from the nutrient pulse after a low-severity fire. Salvage-logging after a high-severity fire had no significant effects on soil carbon fluxes, microclimate or nutrient content compared with leaving the dead trees standing, although differences are expected to emerge in the long term. In contrast, the impact of stand age was substantial: a young burnt stand experienced more extreme microclimate, lower soil nutrient supply and significantly lower soil respiration than a mature burnt stand, due to a thinner organic layer and the decade-long effects of a previous clear-cut and soil scarification. Disturbance history and burn severity are, therefore, important factors for predicting changes in the boreal forest carbon sink after wildfires. The presented short-term effects and ongoing monitoring will provide essential information for sustainable management strategies in response to the increasing risk of wildfire

    Belle II Executive Summary

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    Belle II is a Super BB Factory experiment, expected to record 50 ab1^{-1} of e+ee^+e^- collisions at the SuperKEKB accelerator over the next decade. The large samples of BB mesons, charm hadrons, and tau leptons produced in the clean experimental environment of e+ee^+e^- collisions will provide the basis of a broad and unique flavor-physics program. Belle II will pursue physics beyond the Standard Model in many ways, for example: improving the precision of weak interaction parameters, particularly Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and phases, and thus more rigorously test the CKM paradigm, measuring lepton-flavor-violating parameters, and performing unique searches for missing-mass dark matter events. Many key measurements will be made with world-leading precision.Comment: 7 pages, to be submitted to the "Rare and Precision Measurements Frontier" of the APS DPF Community Planning Exercise Snowmass 202

    Varietal Adoption, Outcomes and Impact

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    Parallel to the preceding chapter, we synthesize the results of Chapters 6–17 here. The focus is on outcomes and impacts. Outcomes centre on varietal adoption and turnover; impacts refer to changes in on-farm productivity, poverty and food security. Hypotheses from Chapter 3 are revisited at the end of each thematic section..

    Underground Wireless Channel Bandwidth and Capacity

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    The UG channel bandwidth and capacity are vital parameters in wireless underground communication system design. In this chapter, a comprehensive analysis of the wireless underground channel capacity is presented. The impact of soil on return loss, bandwidth, and path loss is discussed. The results of underground multi-carrier modulation capacity are also outlined. Moreover, the single user capacity and multi-carrier capacity are also introduced with an in-depth treatment of soil texture, soil moisture, and distance effects on channel capacity. Finally, the chapter is concluded with a discussion of challenges and open research issues

    Aberration-corrected electron microscopy of nanoparticles

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    The early history of scanning transmission electron microscopy (STEM) is reviewed as a way to frame the technical issues that make aberration correction an essential upgrade for the study of nanoparticles using STEM. The principles of aberration correction are explained, and the use of aberration-corrected microscopy in the study of nanostructures is exemplified in order to remark the features and challenges in the use of this measuring techniqu
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