How does financial theory apply to catastrophe-linked derivatives? En empirical test of several princing models

The paper focuses on the PCS Catastrophe Insurance Option Contracts and empirically tests the degree of agreement between their real quotes and the standard fmancial theory. The highest possible precision is incorporated since the real quotes are perfectly synchronized and the bid-ask spread is always considered. A static setting is assumed and the main topics of arbitrage, hedging and portfolio choice are involved in the analysis. Three significant conclusions are reached. First, the catastrophe derivatives may be very often priced by arbitrage methods, and the paper provides some examples of practical strategies that were available in the market. Second, hedging arguments also yield adequate criteria to price the derivatives and some real examples are provided as well. Third, in a variance aversion context many agents could be interested in selling derivatives to invest the money in stocks and bonds. These strategies show a suitable level in the variance for any desired expected return. Furthermore, the methodology here applied seems to be quite general and may be useful to price other derivative securities. Simple assumptions on the underlying asset behavior are the only required conditions

Los precios en los mercados reestructurados de electricidad: algunas lecciones básicas para la negociación derivada

Este artículo investiga los precios al contado de mercados reestructurados de la electricidad de diversas partes del mundo. Primero se proporciona un análisis detallado de las propiedades distributivas y de la dinámica de los precios de contado eléctricos. Después se realiza una introducción a los múltiples factores por el lado de la demanda y de la oferta que contribuyen a su complejo y variado comportamiento. Finalmente se extraen algunas lecciones fundamentales del análisis anterior para la negociación de derivados sobre la electricidad.This paper investigates the spot prices from restructured electricity markets around the world. First, we provide a comprehensive survey of the distributional properties and the dynamics of spot electricity prices. Then, we introduce the multiple demand and supply factors that contribute to their complex and diverse behaviour. Finally, we extract some fundamental lessons implied by such characteristics, for the power [email protected]

How Financial Theory Applies to Catastrophe-Linked Derivatives--An Empirical Test of Several Pricing Models

This paper discusses the PCS Catastrophe Insurance Option Contracts, pro- viding empirical support on the level of correspondence between real quotes and standard financial theory. The highest possible precision is incorpo- rated since the real quotes are perfectly synchronized and the bid-ask spread is always considered. A static setting is assumed and the main topics of arbitrage, hedging, and portfolio choice are involved in the analysis. Three significant conclusions are reached. First, the catastrophe derivatives may often be priced by arbitrage methods, and the paper provides some examples of practical strategies that were available in the market. Second, hedging arguments also yield adequate criteria to price the derivatives, and some real examples are provided as well. Third, in a variance aversion context many agents could be interested in selling derivatives to invest the money in stocks and bonds. These strategies show a suitable level in the variance for any desired expected return. Furthermore, the methodology here ap- plied seems to be quite general and may be useful to price other derivative securities. Simple assumptions on the underlying asset behavior are the only required conditions.Publicad

Evaluation of the Performance of the IDvet IFN-Gamma Test for Diagnosis of Bovine Tuberculosis in Spain

In Spain, the national bovine tuberculosis (bTB) eradication program is based on yearly skin testing of every ≥6 weeks old animal using the single or comparative tuberculin test and parallel use of the interferon-gamma (IFN-γ) assay as an ancillary diagnostic test in infected herds. There are several versions of the latter. Recently, a new commercial IDvet IFN-γ assay has been authorized for use in the program, but there is limited scientific evidence about its performance in different epidemiological settings. Therefore, two studies to evaluate the performance of the IDvet assay were conducted. In study 1, a concordance analysis between the new IDvet and the Bovigam IFN-γ assay in use in Spain for over 10 years was conducted. In study 2, results from the IDvet assay when applied in tandem with a single intradermal tuberculin (SIT) test were used to evaluate the concordance between both tests and to estimate their sensitivity (Se) and specificity (Sp) using a Bayesian latent-class model. Field data from cattle herds located in Madrid and Castilla y Leon (Spain) were collected. For study 1, herd selection was based on a high expected prevalence of reactors to the IFN-γ assay, while herds were selected at random to estimate Se and Sp of the new IDvet assay in study 2. Agreement between the results obtained with both kits for IFN-γ assay was poor (Kappa = 0.20), and a receiver operating characteristic (ROC) analysis indicated a low Se of the new IDvet relative to the Bovigam in a heavily bTB infected population. The Bayesian latent-class analysis estimated the Se of the IDvet assay to be 36.7% [95% probability posterior interval (PPI) 14.7–78.8%] with estimated Sp close to 100% when the cut-off recommended by the manufacturer (35) was applied. At the alternative cut-off values of 16 and 4, the estimated Se of the IDvet assay increased to 49.0% (PPI: 24.8–94.1%) and 56.0% (PPI: 30.8–96.3%), respectively, while maintaining a high specificity. The results suggest that the new IDvet assay may have lower sensitivity than the Bovigam for diagnosis of bTB in cattle herds in Spain, and that adjusting its cut-off might be considered

Factores de riesgo de mortalidad por Covid-19 en pacientes hospitalizados: un modelo de regresión logística

Introducción: La población es susceptible al COVID-19 y conocer las características y comorbilidades más predominantes de los afectados resulta imprescindible para disminuir sus efectos. Objetivo: El presente estudio analizó los factores biológicos, sociales y clínicos de riesgo de mortalidad en pacientes hospitalizados con COVID-19 en el distrito de Trujillo, Perú. Métodos: El tipo de estudio fue descriptivo, de enfoque cuantitativo y diseño correlacional, retrospectivo, de corte transversal. Se obtuvieron los datos del sistema del Ministerio de Salud, con una muestra de 64 pacientes de marzo a mayo del 2020. Resultados: El 85,71% del total de fallecidos son del sexo masculino, la ocupación más predominante es jubilados con un 28,57% y tienen una edad promedio de 64,67 años. En el caso de los síntomas en pacientes fallecidos la dificultad respiratoria representa el mayor porcentaje 90,48%; la fiebre con un 80,95%, seguido de un malestar en general con un 57,14% y tos con un 52,38%. Los signos con mayor porcentaje en fallecidos fueron la disnea y auscultación pulmonar anormal con un 47,62%, en Comorbilidades se encontraron pacientes con enfermedad cardiovascular en un 42,86% y un 14,29% con diabetes. El modelo de regresión logística para predecir la mortalidad en pacientes hospitalizados permitió la selección de factores de riesgo como edad, sexo, tos, dificultad respiratoria y diabetes. Conclusión: El modelo es el adecuado para establecer estos factores, ya que muestran que un porcentaje de variación explicada bastante considerable, clasificaría correctamente el 90,6% de los casos

Multiple unbiased approaches identify oxidosqualene cyclase as the molecular target of a promising anti-leishmanial

Phenotypic screening identified a benzothiophene compound with activity against Leishmania donovani, the causative agent of visceral leishmaniasis. Using multiple orthogonal approaches, oxidosqualene cyclase (OSC), a key enzyme of sterol biosynthesis, was identified as the target of this racemic compound and its enantiomers. Whole genome sequencing and screening of a genome-wide overexpression library confirmed that OSC gene amplification is associated with resistance to compound 1. Introduction of an ectopic copy of the OSC gene into wild-type cells reduced susceptibility to these compounds confirming the role of this enzyme in resistance. Biochemical analyses demonstrated the accumulation of the substrate of OSC and depletion of its product in compound (S)-1-treated-promastigotes and cell-free membrane preparations, respectively. Thermal proteome profiling confirmed that compound (S)-1 binds directly to OSC. Finally, modeling and docking studies identified key interactions between compound (S)-1 and the LdOSC active site. Strategies to improve the potency for this promising anti-leishmanial are proposed

Occurrence of Mycobacterium avium subspecies paratuberculosis across host species and European countries with evidence for transmission between wildlife and domestic ruminants

<p>Abstract</p> <p>Background</p> <p><it>Mycobacterium avium </it>subspecies <it>paratuberculosis </it>(<it>Map</it>) causes an infectious chronic enteritis (paratuberculosis or Johne's disease) principally of ruminants. The epidemiology of <it>Map </it>is poorly understood, particularly with respect to the role of wildlife reservoirs and the controversial issue of zoonotic potential (Crohn's disease). Genotypic discrimination of <it>Map </it>isolates is pivotal to descriptive epidemiology and resolving these issues. This study was undertaken to determine the genetic diversity of <it>Map</it>, enhance our understanding of the host range and distribution and assess the potential for interspecies transmission.</p> <p>Results</p> <p>164 <it>Map </it>isolates from seven European countries representing 19 different host species were genotyped by standardized IS<it>900 </it>- restriction fragment length polymorphism (IS<it>900</it>-RFLP), pulsed-field gel electrophoresis (PFGE), amplified fragment length polymorphisms (AFLP) and mycobacterial interspersed repeat unit-variable number tandem repeat (MIRU-VNTR) analyses. Six PstI and 17 BstEII IS<it>900</it>-RFLP, 31 multiplex [SnaBI-SpeI] PFGE profiles and 23 MIRU-VNTR profiles were detected. AFLP gave insufficient discrimination of isolates for meaningful genetic analysis. Point estimates for Simpson's index of diversity calculated for the individual typing techniques were in the range of 0.636 to 0.664 but a combination of all three methods increased the discriminating power to 0.879, sufficient for investigating transmission dynamics. Two predominant strain types were detected across Europe with all three typing techniques. Evidence for interspecies transmission between wildlife and domestic ruminants on the same property was demonstrated in four cases, between wildlife species on the same property in two cases and between different species of domestic livestock on one property.</p> <p>Conclusion</p> <p>The results of this study showed that it is necessary to use multiple genotyping techniques targeting different sources of genetic variation to obtain the level of discrimination necessary to investigate transmission dynamics and trace the source of <it>Map </it>infections. Furthermore, the combination of genotyping techniques may depend on the geographical location of the population to be tested. Identical genotypes were obtained from <it>Map </it>isolated from different host species co-habiting on the same property strongly suggesting that interspecies transmission occurs. Interspecies transmission of <it>Map </it>between wildlife species and domestic livestock on the same property provides further evidence to support a role for wildlife reservoirs of infection.</p

Impact of safety-related dose reductions or discontinuations on sustained virologic response in HCV-infected patients: Results from the GUARD-C Cohort

BACKGROUND: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. METHODS: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the impact of sr-RD on SVR24 (HCV RNA <50 IU/mL) were conducted in 951 Caucasian, noncirrhotic genotype (G)1 patients assigned to peginterferon alfa-2a/ribavirin for 48 weeks. The probability of SVR24 was identified by a baseline scoring system (range: 0-9 points) on which scores of 5 to 9 and <5 represent high and low probability of SVR24, respectively. RESULTS: SVR24 rates were 46.1% (754/1634), 77.1% (279/362), 68.0% (514/756), and 51.3% (203/396), respectively, in G1, 2, 3, and 4 patients. Overall, 16.9% and 21.8% patients experienced 651 sr-RD for peginterferon alfa and ribavirin, respectively. Among Caucasian noncirrhotic G1 patients: female sex, lower body mass index, pre-existing cardiovascular/pulmonary disease, and low hematological indices were prognostic factors of sr-RD; SVR24 was lower in patients with 651 vs. no sr-RD by Week 4 (37.9% vs. 54.4%; P = 0.0046) and Week 12 (41.7% vs. 55.3%; P = 0.0016); sr-RD by Week 4/12 significantly reduced SVR24 in patients with scores <5 but not 655. CONCLUSIONS: In conclusion, sr-RD to peginterferon alfa-2a/ribavirin significantly impacts on SVR24 rates in treatment-naive G1 noncirrhotic Caucasian patients. Baseline characteristics can help select patients with a high probability of SVR24 and a low probability of sr-RD with peginterferon alfa-2a/ribavirin

Forest and woodland replacement patterns following drought-related mortality

Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern post drought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.Peer reviewe