A new approach to bad news effects on volatility: the Multiple-Sign-Volume sensitive regime EGARCH model (MSV-EGARCH)

In this paper, using daily data for six major international stock market indexes and a modified EGARCH specification, the links between stock market returns, volatility and trading volume are investigated in a new nonlinear conditional variance framework with multiple regimes and volume effects. Volatility forecast comparisons, using the Harvey-Newbold test for multiple forecasts encompassing, seem to demonstrate that the MSV-EGARCH complex threshold structure is able to correctly fit GARCH-type dynamics of the series under study and dominates competing standard asymmetric models in several of the considered stock indexes.info:eu-repo/semantics/acceptedVersio

Mathematical methods for the randomized non-autonomous Bertalanffy model

[EN] In this article we analyze the randomized non-autonomous Bertalanffy model x' (t, omega) = a(t, omega)x(t, omega) b(t, omega)x(t, omega)(2/3), x(t(0), omega) = x(0)(omega), where a(t, omega) and b(t, omega) are stochastic processes and x(0)(omega) is a random variable, all of them defined in an underlying complete probability space. Under certain assumptions on a, b and x(0), we obtain a solution stochastic process, x(t, omega), both in the sample path and in the mean square senses. By using the random variable transformation technique and Karhunen-Loeve expansions, we construct a sequence of probability density functions that under certain conditions converge pointwise or uniformly to the density function of x(t, omega), f (t) (x). This permits approximating the expectation and the variance of x(t, omega). At the end, numerical experiments are carried out to put in practice our theoretical findings.This work was supported by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO), by the Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER UE) grant MTM2017-89664-P. Marc Jornet acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigacion y Desarrollo (PAID), Universitat Politecnica de Valencia.Calatayud, J.; Caraballo, T.; Cortés, J.; Jornet, M. (2020). Mathematical methods for the randomized non-autonomous Bertalanffy model. Electronic Journal of Differential Equations. 2020:1-19. http://hdl.handle.net/10251/161056S119202

First report of an olive ridley (Lepidochelys olivacea) inside the Mediterranean Sea

We report the first confirmed occurrence of a Lepidochelys olivacea in the Mediterranean Sea based on the study of an individual stranded on a beach, located in the town of Oropesa del Mar (40º05ʹ32ʺN, 0º08ʹ02ʺE), Castellón province, East Spain, in May 2014. Morphological and genetic analyses were used to confirm the identification of the species. The individual had a sequence that matched the 470 bp Lepidochelys olivacea haplotype F (Genbank accession number: AF051773), found in several Atlantic populations. This becomes one of the northernmost known occurrences of olive ridleys in the world and is the first reports of this species in the Mediterranean Sea

Avaliação do comportamento agronómico de porta-enxertos tolerantes à tristeza dos citrinos

A detecção no nosso país de alguns núcleos de plantas infectadas com o citrus tristeza virus (CTV), impôs a necessidade de desenvolver um plano de prevenção, nomeadamente através do incentivo da substituição progressiva dos porta-enxertos susceptíveis por porta-enxertos tolerantes. Com a identificação do seu principal vector (Toxoptera citricidus Kirk.) em finais 2003, nas regiões de Entre-Douro e Minho e de Trás-os-Montes é de prever que a dispersão da doença ocorra mais rapidamente. As novas plantações utilizam na sua maioria as citranjeiras Troyer e Carrizo, que nem sempre se mostram adequadas às condições edafo-climáticas existentes. Considerando esta problemática, a Direcção Regional de Agricultura do Algarve, em colaboração com outras entidades (Universidade do Algarve e Centro de Citricultura), tem vindo a desenvolver estudos conducentes à adaptação de novos porta-enxertos, com o objectivo de diversificar as opções existentes relativamente aos condicionalismos da região. Com este objectivo foi instalado em Tavira, em Maio de 1998, num solo calcário, um ensaio de campo para avaliação do comportamento de 11 clones de porta-enxertos (T. Sunki x P. trifoliata FAO 30590; Citranjeira Troyer B2 FAO 31655; T. Cleopatra x P. trifoliata FAO 30584; T. Cleopatra x C. Carrizo FAO 30575; Laranjeira Gou Tou B7; Citrandarineira 31443; Laranjeira azeda B6C-T1; Tangerineira Changsa; Tangerineira Sunki; Tangerineira Cleópatra; Citranjeira Troyer 4 AS). Durante três anos, as plantas foram submetidas a três níveis de salinidade da água de rega, expressos pela condutividade eléctrica da água de rega ECw – 1; 3 e 6 dS.m-1, obtidos através de um esquema experimental fonte dupla gota-a-gota. Foram medidos vários parâmetros agro-ambientais, como o desenvolvimento vegetativo das plantas e o aumento da condutividade eléctrica do extracto de saturação do solo (medido no extracto aquoso). Os resultados obtidos mostram que os porta-enxertos com maior tolerância à salinidade foram o clone de laranjeira azeda B6C-T1 e a laranjeira Gou Tou.info:eu-repo/semantics/publishedVersio

The discrimination capabilities of Micromegas detectors at low energy

The latest generation of Micromegas detectors show a good energy resolution, spatial resolution and low threshold, which make them idoneous in low energy applications. Two micromegas detectors have been built for dark matter experiments: CAST, which uses a dipole magnet to convert axion into detectable x-ray photons, and MIMAC, which aims to reconstruct the tracks of low energy nuclear recoils in a mixture of CF4 and CHF3. These readouts have been respectively built with the microbulk and bulk techniques, which show different gain, electron transmission and energy resolutions. The detectors and the operation conditions will be described in detail as well as their discrimination capabilities for low energy photons will be discussed.Comment: To be published in the proceedings of the TIPP2011 conference (Physics Procedia

Integrating a framework for conducting public health systems research into statewide operations-based exercises to improve emergency preparedness

<p>Abstract</p> <p>Background</p> <p>Due to the uncommon nature of large-scale disasters and emergencies, public health practitioners often turn to simulated emergencies, known as “exercises”, for preparedness assessment and improvement. Under the right conditions, exercises can also be used to conduct original public health systems research. This paper describes the integration of a research framework into a statewide operations-based exercise program in California as a systems-based approach for studying public health emergency preparedness and response.</p> <p>Methods</p> <p>We developed a research framework based on the premise that operations-based exercises conducted by medical and public health agencies can be described using epidemiologic concepts. Using this framework, we conducted a survey of key local and regional medical and health agencies throughout California following the 2010 Statewide Medical and Health Exercise. The survey evaluated: (1) the emergency preparedness capabilities activated and functions performed in response to the emergency scenario, and (2) the major challenges to inter-organizational communications and information management.</p> <p>Results</p> <p>Thirty-five local health departments (LHDs), 24 local emergency medical services (EMS) agencies, 121 hospitals, and 5 Regional Disaster Medical and Health Coordinators/Specialists (RDMHC) responded to our survey, representing 57%, 77%, 26% and 83%, respectively, of target agencies in California. We found two sets of response capabilities were activated during the 2010 Statewide Exercise: a set of core capabilities that were common across all agencies, and a set of agency-specific capabilities that were more common among certain agency types. With respect to one response capability in particular, inter-organizational information sharing, we found that the majority of respondents’ comments were related to the complete or partial failure of communications equipment or systems.</p> <p>Conclusions</p> <p>Using the 2010 Statewide Exercise in California as an opportunity to develop our research framework, we characterized several aspects of the public health and medical system’s response to a standardized emergency scenario. From a research perspective, this study provides a potential new framework for conducting exercise-based research. From a practitioner’s perspective, our results provide a starting point for preparedness professionals’ dialogue about expected and actual organizational roles, responsibilities, and resource capacities within the public health system. Additionally, the identification of specific challenges to inter-organizational communications and information management offer specific areas for intervention.</p

First-principles calculation of intrinsic defect formation volumes in silicon

We present an extensive first-principles study of the pressure dependence of the formation enthalpies of all the know vacancy and self-interstitial configurations in silicon, in each charge state from -2 through +2. The neutral vacancy is found to have a formation volume that varies markedly with pressure, leading to a remarkably large negative value (-0.68 atomic volumes) for the zero-pressure formation volume of a Frenkel pair (V + I). The interaction of volume and charge was examined, leading to pressure--Fermi level stability diagrams of the defects. Finally, we quantify the anisotropic nature of the lattice relaxation around the neutral defects.Comment: 9 pages, 9 figure

Slowly rotating voids in cosmology

We consider a spacetime consisting of an empty void separated from an almost Friedmann-Lema\^\i tre-Robertson-Walker (FLRW) dust universe by a spherically symmetric, slowly rotating shell which is comoving with the cosmic dust. We treat in a unified manner all types of the FLRW universes. The metric is expressed in terms of a constant characterizing the angular momentum of the shell, and parametrized by the comoving radius of the shell. Treating the rotation as a first order perturbation, we compute the dragging of inertial frames as well as the apparent motion of distant stars within the void. Finally, we discuss, in terms of in principle measurable quantities, 'Machian' features of the model.Comment: 21 pages, 5 figures, REVTex, accepted for publication in Class.Quant.Gravit