Opin visindi

    Impact of Wind on Stormwater Pond Particulate Removal

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    Stormwater ponds provide cost and space-efficient treatment of urban runoff via gravitational settling. The goal of this paper was to quantify different mechanisms by which wind can affect the particle removal efficiency of a shallow retention pond. An analytical bulk model was developed and validated numerically against total suspended solids (TSS) measurements in a small (0.3 ha), optimally designed oval pond during four runoff events with 7–11  m/s winds. Simulations highlighted wind as an effective mixing mechanism, lowering the removal of medium silt particles by 10–20% from ideal plug flow, and severely constraining the removal of small clay and silt particles (<6  μm). Initial background concentrations of <12  mg/L TSS were positively correlated with wind speed 5 h prior to the event, indicative of localized wind resuspension. A widespread remobilization of bed sediments was found unlikely in a 1.7-m deep, 112-m fetch pond. A stirred reactor with 60% effective volume is proposed as a first order tool to assess the treatment performance of ideally structured ponds in areas with strong, unobstructed winds.This work was funded by the University of Iceland Research Fund. The Icelandic Meteorological Office is thanked for data and equipment for PSD assessment. Gudbjörg Esther Vollertsen is thanked for field data collection. Professor Lars Bengtsson at Lund Technical University is thanked for his comments on the manuscript.Peer Reviewe

    Feature Selection Based on Hybridization of Genetic Algorithm and Particle Swarm Optimization

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    A new feature selection approach that is based on the integration of a genetic algorithm and particle swarm optimization is proposed. The overall accuracy of a support vector machine classifier on validation samples is used as a fitness value. The new approach is carried out on the well-known Indian Pines hyperspectral data set. Results confirm that the new approach is able to automatically select the most informative features in terms of classification accuracy within an acceptable CPU processing time without requiring the number of desired features to be set a priori by users. Furthermore, the usefulness of the proposed method is also tested for road detection. Results confirm that the proposed method is capable of discriminating between road and background pixels and performs better than the other approaches used for comparison in terms of performance metrics.Rannís; Rannsóknarnámssjóður / The Icelandic Research Fund for Graduate Students.PostPrin

    „Whose interest matter prevail?“: The lived experience of managers and specialists of the effect of published application lists on applicants in governmental hiring

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    Birting umsækjendalista í opinberum ráðningum er umræðuefni sem heitar umræður skapast oft um. Grein þessi byggist á niðurstöðum úr rannsókn þar sem skoðuð var reynsla og upplifun stjórnenda og sérfræðinga á áhrifum birtingar lista yfir umsækjendur í opinberum ráðningum. Samkvæmt niðurstöðum rannsóknarinnar er ákveðinn fælingarmáttur fólginn í birtingunni. Tekin voru viðtöl við stjórnendur og sérfræðinga sem hafa reynslu af ráðningum og þekkingu á áhrifum birtingar umsækjendalista á umsækjendur í opinberum ráðningum. Leitast var við að öðlast frekari skilning á ferli opinberra ráðninga og hvort þessir sérfræðingar teldu að birtingin hefði fælingarmátt. Rannsóknargögnin voru túlkuð og greind samkvæmt fyrirbærafræðilegri aðferðafræði. Niðurstöður sýna fram á að þeir stjórnendur og sérfræðingar sem leitað var til í þessari rannsókn telja að fælingarmáttur í birtingu á umsækjendalistum í opinberum ráðningum sé afar mikill. Talið er að um 10-35% umsækjenda dragi umsókn sína til baka. Þetta getur haft mjög neikvæð áhrif á ráðningarferlið í heild. Nafnbirting getur því leitt til þess að hæfasti umsækjandinn sækir ekki um starfið. Í lokin gefa niðurstöður rannsóknarinnar einnig til kynna að kerfisbundin birting á listum yfir umsækjendur þarfnist endurskoðunar. Þannig má auka líkur á því að sá hæfasti verði ráðinn og að fagmennska ráði för í umsóknar- og ráðningarferli í opinberum ráðningum.In this study the researchers set out to gain insight into the experience and attitude of managers and specialists concerning display of applicant lists in governmental hiring. The study focused on whether publication of application lists would have repellent effect on applicants and consequently if public employees had the appropriate qualifications. Information was gathered with semi-structured interviews with managers in organizations, ministries, municipals and experts in recruitment and their experience on publication of applicant lists probed. The data were analyzed and interpreted according to phenomenological methodology. Highlights of the study are that publication of applicants have repellent effects and it is estimated that about 10-35% of applicants withdraw their application when it is clear that a disclosure will occur. The results indicate that the managers and specialists in this study believe that published application list in governmental hiring is very repellent for prospective applicants and that the publications cause them to withdraw their application. As the names of the applicants will be published, the applicants withdraw and as a result of that, the most qualified candidate for the job will not be hired. Therefore the employer will not get the most qualified applicant for the job. Finally, the results of this study indicate that systematic publication of the application lists need to be re-examined in order to increase the possibility that the best and most qualified candidate will be hired and professionalism will prevail in the application and hiring process in governmental hiring.Peer Reviewe

    Interaction of Flavonoids from Woodwardia unigemmata with Bovine Serum Albumin (BSA): Application of Spectroscopic Techniques and Molecular Modeling Methods

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    Phytochemical investigation on the methanol extract of Woodwardia unigemmata resulted in the isolation of seven flavonoids, including one new flavonol acylglycoside (1). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis and comparison of literature data. The multidrug resistance (MDR) reversing activity was evaluated for the isolated compounds using doxorubicin-resistant K562/A02 cells model. Compound 6 showed comparable MDR reversing effect to verapamil. Furthermore, the interaction between compounds and bovine serum albumin (BSA) was investigated by spectroscopic methods, including steady-state fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular docking approach. The experimental results indicated that the seven flavonoids bind to BSA by static quenching mechanisms. The negative ∆H and ∆S values indicated that van der Waals interactions and hydrogen bonds contributed in the binding of compounds 2–6 to BSA. In the case of compounds 1 and 7 systems, the hydrophobic interactions play a major role. The binding of compounds to BSA causes slight changes in the secondary structure of BSA. There are two binding sites of compound 6 on BSA and site I is the main site according to the molecular docking studies and the site marker competitive binding assayThis work was supported by the Natural Science Foundation of China (81502921) and the Young Scholars Program of Shandong University (2015WLJH50).Peer Reviewe

    The 1912 Iceland earthquake rupture: Growth and development of a nascent transform system

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    We have mapped in detail surface ruptures of the 1912 magnitude 7.0 strike-slip earthquake in south Iceland. This earthquake ruptured fresh basalt flows that had covered the pre-existing fault. The observed style of surface fracturing closely matches both theoretical predictions of the first stages of shear fracture development and microscopic-scale observations from laboratory experiments. The shear offset distributed across the zone of surface fractures produced by this earthquake is right-lateral and is in the range of 1 to 3 m. Total mapped rupture length is 9 km, but total rupture length is probably at least ∼ 20 km. This interplate earthquake had an exceptionally high ratio of slip to fault length and, by inference, stress drop. The north-south trending rupture of the 1912 earthquake is part of the “bookshelf” faulting in the east-west trending South Iceland Seismic Zone. We ascribe the “bookshelf” faulting in the South Iceland Seismic Zone to a combination of the early development stage of the transform and regional strength anisotropy of the crust.This research was supported by the National Science Foundation, the Icelandic National Power Authority (Landsvirkjun), and the Department of Geological Sciences of Columbia University. Lamont-Dohert Contribution 5036.Peer Reviewe

    Non-analyticity of holographic Rényi entropy in Lovelock gravity

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    We compute holographic Rényi entropies for spherical entangling surfaces on the boundary while considering third order Lovelock gravity with negative cosmological constant in the bulk. Our study shows that third order Lovelock black holes with hyperbolic event horizon are unstable, and at low temperatures those with smaller mass are favoured, giving rise to first order phase transitions in the bulk. We determine regions in the Lovelock parameter space in arbitrary dimensions, where bulk phase transitions happen and where boundary causality constraints are met. We show that each of these points corresponds to a dual boundary conformal field theory whose Rényi entropy exhibits a kink at a certain critical index n.This research was supported in part by the Icelandic Research Fund under contracts 163419-051 and 163422-051, and by grants from the University of Iceland Research Fund.Peer Reviewe

    Host-Parasite Interactions and Population Dynamics of Rock Ptarmigan

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    Populations of rock ptarmigan (Lagopus muta) in Iceland fluctuate in multiannual cycles with peak numbers c. every 10 years. We studied the ptarmigan-parasite community and how parasites relate to ptarmigan age, body condition, and population density. We collected 632 ptarmigan in northeast Iceland in early October from 2006 to 2012; 630 (99.7%) were infected with at least one parasite species, 616 (98%) with ectoparasites, and 536 (85%) with endoparasites. We analysed indices for the combined parasite community (16 species) and known pathogenic parasites, two coccidian protozoans Eimeria muta and Eimeria rjupa, two nematodes Capillaria caudinflata and Trichostrongylus tenuis, one chewing louse Amyrsidea lagopi, and one skin mite Metamicrolichus islandicus. Juveniles overall had more ectoparasites than adults, but endoparasite levels were similar in both groups. Ptarmigan population density was associated with endoparasites, and in particular prevalence of the coccidian parasite Eimeria muta. Annual aggregation level of this eimerid fluctuated inversely with prevalence, with lows at prevalence peak and vice versa. Both prevalence and aggregation of E. muta tracked ptarmigan population density with a 1.5 year time lag. The time lag could be explained by the host specificity of this eimerid, host density dependent shedding of oocysts, and their persistence in the environment from one year to the next. Ptarmigan body condition was negatively associated with E. muta prevalence, an indication of their pathogenicity, and this eimerid was also positively associated with ptarmigan mortality and marginally inversely with fecundity. There were also significant associations between fecundity and chewing louse Amyrsidea lagopi prevalence (negative), excess juvenile mortality and nematode Capillaria caudinflata prevalence (positive), and adult mortality and skin mite Metamicrolichus islandicus prevalence (negative). Though this study is correlational, it provides strong evidence that E. muta through time-lag in prevalence with respect to host population size and by showing significant relations with host body condition, mortality, and fecundity could destabilize ptarmigan population dynamics in Iceland.This work was supported by the Icelandic Research Fund, grant number 090207021: salary including funding of this work; Hunting Card Fund: salary including funding of this work; Landsvirkjun Energy Fund: salary and funding of this work; Institute for Experimental Pathology, Keldur, University of Iceland:Peer Reviewe

    Correlation functions in theories with Lifshitz scaling

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    The 2+1 dimensional quantum Lifshitz model can be generalised to a class of higher dimensional free field theories that exhibit Lifshitz scaling. When the dynamical critical exponent equals the number of spatial dimensions, equal time correlation functions of scaling operators in the generalised quantum Lifshitz model are given by a d-dimensional higher-derivative conformal field theory. Autocorrelation functions in the generalised quantum Lifshitz model in any number of dimensions can on the other hand be expressed in terms of autocorrelation functions of a two-dimensional conformal field theory. This also holds for autocorrelation functions in a strongly coupled Lifshitz field theory with a holographic dual of Einstein-Maxwell-dilaton type. The map to a two-dimensional conformal field theory extends to autocorrelation functions in thermal states and out-of-equilbrium states preserving symmetry under spatial translations and rotations in both types of Lifshitz models. Furthermore, the spectrum of quasinormal modes of scalar field perturbations in Lifshitz black hole backgrounds can be obtained analytically at low spatial momenta and exhibits a linear dispersion relation at z = d. At high momentum, the mode spectrum can be obtained in a WKB approximation and displays very different behaviour compared to holographic duals of conformal field theories. This has implications for thermalisation in strongly coupled Lifshitz field theories with z > 1.Icelandic Research Fund grant 163422-051 University of Iceland Research Fund Swedish Research Council 621-2014-5838 Netherlands Organisation for Scientific Research (NWO) under the VICI grant 680-47-603 Dutch Ministry of Education, Culture and Science (OCW)Peer Reviewe

    Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images

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    Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Statistics in snow- and ice-free areas reveal similar vertical relative accuracy (<  0.5 m) with and without ground control points (GCPs), demonstrating the capability for measuring seasonal snow accumulation. The calculated winter (14 October 2014 to 22 May 2015) mass balance of Drangajökull was 3.33 ± 0.23 m w.e. (meter water equivalent), with ∼ 60 % of the accumulation occurring by February, which is in good agreement with nearby ground observations. On average, the repeated DEMs yield 22 % less elevation change than the length of eight winter snow cores due to (1) the time difference between in situ and satellite observations, (2) firn densification and (3) elevation changes due to ice dynamics. The contributions of these three factors were of similar magnitude. This study demonstrates that seasonal geodetic mass balance can, in many areas, be estimated from sub-meter resolution satellite stereo images.This study was funded by the University of Iceland (UI) Research Fund. Pleiades images were acquired at research price thanks to the CNES ISIS program (http://www.isis-cnes.fr). The WV2 DEM was obtained through the ArcticDEM project. This work is a contribution to the Rannis grant of excellence project, ANATILS. Collaboration and travels between IES and LEGOS were funded by the Jules Verne research fund and the TOSCA program from the French Space Agency, CNES. This study used the recent lidar mapping of the glaciers in Iceland that was funded by the Icelandic Research Fund, the Landsvirkjun research fund, the Icelandic Road Administration, the Reykjavik Energy Environmental and Energy Research Fund, the Klima-og Luftgruppen (KoL) research fund of the Nordic Council of Ministers, the Vatnajokull National Park, the organization Friends of Vatnajokull, the National Land Survey of Iceland, the Icelandic Meteorological Office and the UI research fund. The ground-based mass balance measurements on Drangajokull have been jointly funded by Orkubu Vestfjarda (Westfjord Power Company), the National Energy Authority (2004-2009) and the Icelandic Meteorological Office (2009-2015).Peer Reviewe

    Meta-analysis identifies five novel loci associated with endometriosis highlighting key genes involved in hormone metabolism

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    Endometriosis is a heritable hormone-dependent gynecological disorder, associated with severe pelvic pain and reduced fertility; however, its molecular mechanisms remain largely unknown. Here we perform a meta-analysis of 11 genome-wide association case-control data sets, totalling 17,045 endometriosis cases and 191,596 controls. In addition to replicating previously reported loci, we identify five novel loci significantly associated with endometriosis risk (P<5 × 10−8), implicating genes involved in sex steroid hormone pathways (FN1, CCDC170, ESR1, SYNE1 and FSHB). Conditional analysis identified five secondary association signals, including two at the ESR1 locus, resulting in 19 independent single nucleotide polymorphisms (SNPs) robustly associated with endometriosis, which together explain up to 5.19% of variance in endometriosis. These results highlight novel variants in or near specific genes with important roles in sex steroid hormone signalling and function, and offer unique opportunities for more targeted functional research efforts.We acknowledge all the study participants in 11 individual endometriosis studies that provided an opportunity for the current study. We also thank many hospital directors and staff, gynaecologists, general practitioners and pathology services in Australia who provided assistance with confirmation of diagnoses. We would like to thank the research participants and employees of 23andMe for making this work possible. We thank the subjects of the Icelandic deCODE study for their participation. We thank research staff and clinicians for providing diagnostic confirmation for the OX data set. We would like to express our gratitude to the staff and members of the Biobank Japan and Laboratory for Statistical Analysis, RIKEN Center for Integrative Medical Sciences for their outstanding assistance. The QIMR study was supported by grants from the National Health and Medical Research Council (NHMRC) of Australia (241,944, 339,462, 389,927, 389,875, 389,891, 389,892, 389,938, 443,036, 442,915, 442,981, 496,610, 496,739, 552,485, 552,498, 1,026,033 and 1,050,208), the Cooperative Research Centre for Discovery of Genes for Common Human Diseases (CRC), Cerylid Biosciences (Melbourne) and donations from N. Hawkins and S. Hawkins. Analyses of the QIMRHCS and OX GWAS were supported by the Wellcome Trust (WT084766/Z/08/Z) and makes use of WTCCC2 control data generated by the Wellcome Trust Case-Control Consortium (awards 076113 and 085475). The iPSYCH study was funded by The Lundbeck Foundation, Denmark (R102-A9118, R155-2014-1724 ), and the research has been conducted using the Danish National Biobank resource supported by the Novo Nordisk Foundation. A full list of the investigators who contributed to the generation of these data is available from http://www.wtccc.org.uk. D.R.N. was supported in part by the NHMRC Fellowship (613674) and ARC Future Fellowship (FT0991022) schemes. E.G.H. (631096) and G.W.M. (339446, 619667) were supported by the NHMRC Fellowships Scheme. S.M. is supported by an Australian Research Council Future Fellowship. A.P.M. was supported by a Wellcome Trust Senior Research Fellowship (award WT098017). N.R. was supported by funding from the Medical Research Council UK (MR/K011480/1). This study was funded by the BioBank Japan project, which is supported by the Ministry of Education, Culture, Sports, Sciences and Technology of Japanese government.Peer Reviewe
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