Vpliv likvidnostnega tveganja na izračun tvegane vrednosti

V članku uvajamo likvidnost v standardno analizo tvegane vrednosti. Osnovne VaR modele nadgradimo z informacijami o cenovnem razponu med ponujeno in povpraševano ceno naložbe. Nadgrajene modele testiramo na podlagi domačega in tujih naborov delnic. Ugotavljamo, da likvidnostni VaR modeli ob upoštevanju predpostavk raziskave primerno ocenjujejo tržna tveganja. Le-ti metodološko na eni strani predstavljajo napredek v okviru obravnave tržnih tveganj, vendar na drugi strani rezultati testiranj modelov kažejo pomanjkanje robustnosti. Glede primerjave rezultatov po naborih delnic pa ugotavljamo, da so rezultati za slovenski nabor kljub manjši globini trga primerljivi s tistimi iz tujine.In this article we implement liquidity in the standard value-at-risk framework. We incorporate bid-ask spread into basic VaR models. We then test these models on three foreign markets and on a domestic one. We conclude that liquidity VaR models adequately measure market risk. On one hand, the liquidity VaR methodology represents advancement in market risk analysis, but on the other hand, those models are not yet robust enough to pass all back tests. Comparing the results between markets we conclude that the results for the domestic market are comparable to those of foreign ones despite their size difference

Unexplained mortalities of hatchery-reared, juvenile oysters, Crassostrea virginica (Gmelin)

Survival. growth and pathology of juvenile oysters. Crassostrea virginica. in off-bottom culture at Oyster Bay and Fishers Island, New York, were monitored during the summer of 1991 to document and help explain the episodic mass mortalities of cultured seed oysters that have occurred in the northeastern USA over the past several years. Al Oyster Bay. where the more detailed study was conducted. 54 to 7So/o losses affected several 1991 cohorts at mean shell heights ranging from IS to 24 mm, within 3 to 6V, weeks of transfer from the hatchery to growout trays. Mortalities occurred in July and August, at temperatures between 22 and 25°C, and were reduced significantly at low stocking densiucs. Deaths were associated with reduced tissue and shell growth. reduced condition index, mantle retraction, the deposition of an abnom1al conchiolin layer on the inner shell, and lesions of the mantle surface. No obvious pathogen was identified in soft tissues or shells by light or electron microscopy. The pathology suggested that a LOitin-producing agent of bacterial or microalgal origin. or chemical contaminant. caused mantle retraction and secretion of anomalous conchiolin as a defense mechanism. Two potential agents were recognized. Bacteria were found in mantle lesions and within the abnormal conchiolin sheet, but not consistently and with \u3c30% prevalence; il is not clear whether these were primary or secondary invaders. Blooms of a large dinoflagellate, Gymnmodium sanguineum. occurred at peak densities of 5 x I 05 cells 1- 1 at the time of initial oyster mortalities. although the species is not known to be toxic to bivalves. Follow up studies are planned to identify the etiological agent and culture methods that minimize losse

Marine molluscs in nearshore habitats of the United Arab Emirates : decadal changes and species of public health significance

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Journal of Coastal Research 34 (2018): 1157-1175, doi:10.2112/JCOASTRES-D-17-00119.1.This paper describes the results of three qualitative surveys of marine molluscs conducted in December 2010 and May 2011 and 2012 in nearshore benthic habitats along the Arabian Gulf and Gulf of Oman coasts of the United Arab Emirates. Findings are compared to historical studies, focusing on extensive surveys from the 1960s and 1970s. Molluscan species of public health significance are identified based on their potential as vectors of algal toxins in light of the recent occurrence of harmful algal blooms (HABs) in the region. Habitats sampled included intertidal sand or gravel beaches, rocks and jetties, sheltered soft-sediment flats and mangroves, and shallow subtidal coral reefs. The present study showed differences in taxonomic composition and decreased species richness of gastropods compared to a previous mollusc survey conducted in the early 1970s, reflecting the probable impacts of extensive, ongoing coastal development activities, although other environmental stressors may play a contributing role. The major habitat change found in the current survey was replacement of natural “rocky” substrates with manmade jetties and breakwaters. Of the 27 live gastropod species collected, 7 predatory or scavenging species were identified as potential biotoxin vectors: Thais savignyi, T. tissoti, T. lacera, Murex scolopax, Nassarius persicus, Hexaplex kuesterianus and Rapana sp. Of the 22 live bivalve species collected, the following 11 suspension-feeders were deemed to be potential vectors of HAB toxins based on their body size and feeding mode: three venerid clams (Circenita callipyga, and Tivela ponderosa that are consumed locally, and Amiantis umbonella), the widespread encrusting rock oyster, Saccostrea cuccullata, also consumed locally, two pearl oyster species, Pinctada spp., the prickly pen shell Pinna muricata, the scallop Chlamys livida, the cockle Acrosterigma lacunosa, and the facultative suspension-feeding tellinids Asaphis violascens and Hiatula rosea.This study was funded by the Ministry of Climate Change and Environment (formerly the Ministry of Environment and Water), UAE, as part of a consultancy led by Don Anderson, Anderson Consulting Associates, Marion, Massachusetts, USA

Nastajanje niobij karbonitridnog eutektika u konstrukcijskom čeliku

The reduction of area in the through thickness direction is an essential mechanical property of thick steel heavy plates. By a routine control, a very small through thickness reduction of area was found for tensile specimen of a 90 mm plate. Careful investigations of the fracture and section of specimens cut from the as solidified continuously cast 250mmthick slab showed that the cause was the presence of coarse particles of niobium carbonitride as constituent of the quasi eutectic Fe-Nb(C, N) that form because of the centerline segregation of niobium.Kontrakcija u smjeru debljine je vrlo važno mehaničko svojstvo debelih limova od konstrukcijskih čelika. Pri rutinskoj kontroli svojstava čelika utvrđena je ispitivanjem na razvlačenje na uzorku lima debljine 90 mm, vrlo mala kontrakcija u smjeru debljine lima. Ispitivanja prijelomne površine i presjeka uzoraka izrezanih iz kontinuirano odlivenog 250 mm debelog slaba pokazala su da je uzrok tome prisutnost grubih čestica niobijevih karbonitrida u kvazieutektiku Fe-Nb(C, N) koji je nastao zbog središnjih segregacija niobija

Nastajanje niobij karbonitridnog eutektika u konstrukcijskom čeliku

The reduction of area in the through thickness direction is an essential mechanical property of thick steel heavy plates. By a routine control, a very small through thickness reduction of area was found for tensile specimen of a 90 mm plate. Careful investigations of the fracture and section of specimens cut from the as solidified continuously cast 250mmthick slab showed that the cause was the presence of coarse particles of niobium carbonitride as constituent of the quasi eutectic Fe-Nb(C, N) that form because of the centerline segregation of niobium.Kontrakcija u smjeru debljine je vrlo važno mehaničko svojstvo debelih limova od konstrukcijskih čelika. Pri rutinskoj kontroli svojstava čelika utvrđena je ispitivanjem na razvlačenje na uzorku lima debljine 90 mm, vrlo mala kontrakcija u smjeru debljine lima. Ispitivanja prijelomne površine i presjeka uzoraka izrezanih iz kontinuirano odlivenog 250 mm debelog slaba pokazala su da je uzrok tome prisutnost grubih čestica niobijevih karbonitrida u kvazieutektiku Fe-Nb(C, N) koji je nastao zbog središnjih segregacija niobija

Expressed sequence tag analysis of genes expressed during development of the tropical abalone Haliotis asinina

The tropical abalone. Haliotis asinina. is,in ideal species to investigate the molecular mechanisms that control development. growth, reproduction and shell formation in all cultured haliotids. Here we describe the analysis of 232 expressed sequence tags (EST) obtained front a developmental H. asinina cDNA library intended for future microarray studies. From this data set we identified 183 unique gene Clusters. Of these, 90 clusters showed significant homology with sequences lodged in GenBank, ranging in function from general housekeeping to signal transduction, gene regulation and cell-cell communication. Seventy-one clusters possessed completely novel ORFs greater than 50 codons in length, highlighting the paucity of sequence data from molluscs and other lophotrochozoans. This study of developmental gene expression in H. asinina provides the foundation for further detailed analyses of abalone growth, development and reproduction

Studies on the Growth of Chlorella vulgaris in Culture Media with Different Carbon Sources

Diminishing oil reserves, rising oil prices and a significant increase in atmospheric carbon dioxide levels have led to an increasing demand for alternative fuels. Microalgae have been suggested as a suitable means for fuel production because of their advantages related to higher growth rates, higher photosynthetic efficiency and higher biomass production, compared to other terrestrial energy crops. During photosynthesis, microalgae can fix carbon dioxide from different sources, including the atmosphere, industrial exhaust gases and soluble carbonate salts. To determine the most optimal conditions for the growth of Chlorella vulgaris in order to produce lipids that can be transformed into biodiesel fuel, different nutritional conditions were investigated. For this purpose, three media, namely Jaworski’s medium, an enriched solution from modified Dual Solvay process and natural mineral water, were prepared and analyzed for biomass production, chlorophyll content and lipid content. The best growth resulted in an enriched solution from the modified Solvay process. This medium was diluted in different dilution ratios (1:100, 1:50, 1:10) and the best results were obtained in a medium diluted in a 1:10 ratio on the fifth day of culturing (3.72 · 106 cells mL–1; 4.98 μg mL–1 chlorophyll a)

Preface

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 103 (2014): 1-5, doi:10.1016/j.dsr2.2014.02.007.The Gulf of Maine (GOM) is a continental shelf sea in the northwest Atlantic, USA that supports highly-productive shellfisheries that are frequently contaminated by toxigenic Alexandrium fundyense blooms and outbreaks of paralytic shellfish poisoning (PSP), resulting in significant economic and social impacts. Additionally, an emerging threat to these resources is from blooms of toxic Pseudo-nitzschia species that produce domoic acid, the toxin responsible for amnesic shellfish poisoning (ASP). Nearshore shellfish toxins are monitored by state agencies, whereas most offshore stocks have had little or no routine monitoring. As a result, large areas of federal waters have been indefinitely closed or their shellfish beds underexploited because of the potential risk these toxins pose and the lack of scientific understanding and management tools. Patterns and dynamics of Alexandrium blooms and the resulting shellfish toxicity in nearshore waters were examined in a number of research projects, the largest being the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB)-Gulf of Maine (GOM), a five-year regional program emphasizing field surveys, laboratory studies and numerical modeling. At the completion of the ECOHAB-GOM program (documented in Anderson et al., 2005), great progress was made in understanding A. fundyense blooms and resulting shellfish toxicity in nearshore waters, but there were major unknowns that still required investigation. For example, little was known about A. fundyense bloom dynamics in the waters south and east of Cape Cod, Massachusetts, and in particular, about the link between blooms in surface waters and toxicity in deep offshore shellfish. Large areas of offshore shellfish beds were off limits to harvest, including a 40,000 km2 region closed during the 2005 bloom and a much larger zone (~80,000 km2) including portions of Georges Bank was closed in 1990 after high levels of PSP toxicity were detected. In recent years, pressures were mounting from industry to open those offshore areas and to develop management strategies so that surfclam (Spisula solidissima), ocean quahog (Arctica islandica), and roe-on sea scallop (Placopecten magellanicus) fisheries could be opened. In response to these unknowns and societal needs, a new multi-investigator program, GOMTOX (Gulf of Maine Toxicity), was formulated and ultimately funded through the NOAA ECOHAB program. GOMTOX was a regional observation and modeling program that investigated the patterns and mechanisms underlying A. fundyense and Pseudo-nitzschia blooms and the resulting toxicity in shellfish in the southern GOM and its adjacent New England shelf waters, with special emphasis on the delivery pathways, mechanisms, and dynamics of offshore shellfish toxicity. The GOMTOX team of investigators included 16 principal investigators from eight institutions and, continuing in the ECOHAB-GOM tradition, strong participation from federal and state resource managers as well as representatives of the shellfish industry. This team worked together for over five years, running numerous large-scale survey cruises of Alexandrium cells and cysts, and also supporting industry cruises to collect shellfish from offshore sites including Georges Bank. Other efforts included participation in National Marine Fisheries Service surveys for shellfish (sea scallops, surfclams, and ocean quahogs), numerical modeling studies, deployment of sediment traps, and laboratory and ship-based experiments to investigate grazing and other processes that might regulate blooms and deliver toxins to shellfish in deeper waters. A smaller-scale but concurrent effort collected samples to characterize Pseudo-nitzschia species and their potential toxicity in the region.We gratefully acknowledge the support of NOAA through the ECOHAB program. Partial support for some of the studies contained herein was provided by NSF and NIEHS through the Woods Hole Center for Oceans and Human Health. Funding for J.L. Martin’s contributions from the Bay of Fundy was provided by Fisheries and Oceans Canada and NERACOOS, which is a part of the U.S. Integrated Ocean Observing System, funded in part by National Oceanic and Atmospheric Administration (NOAA)