El componente de selección adversa de la horquilla de precios cotizada : una revisión de los modelos de estimación

[email protected] [email protected] de las principales preocupaciones en el área de la microestructura del mercado ha sido la estimación de los componentes no observables de la horquilla de precios a partir de las series de datos que proporcionan los mercados financieros, despertando quizá un mayor interés el de selección adversa por la implicaciones que supone la existencia del mismo. Esto ha provocado el desarrollo de numerosos modelos empíricos que, basándose en las propiedades estadísticas de las series de precios, proporcionan dichas estimaciones. La mayor disponibilidad de datos existentes en los mercados ha permitido el desarrollo en los últimos años de modelos basados en técnicas estadísticas más complejas como son el método generalizado de momentos o la metodología VAR y cuya base de partida es la dinámica de la formación del precio, y, en concreto, cómo la información privada de las transacciones se recoge en los nuevos precios cotizados. El objetivo de este trabajo es analizar este último grupo de trabajos, es decir, aquellos modelos de estimación de los componentes de la horquilla basados en la dinámica de la formación de precios que, además de permitir la estimación del componente de selección adversa en series temporales, suponen una herramienta fundamental para analizar el proceso de incorporación de la información a los precios cotizados en los distintos mercados.One of the main interests of market microstructure is the estimation of the bid–ask spread components from financial data, specially the adverse selection component given the implications of its own existence. As a result, several empirical models based on price time–series statistical properties have been developed in order to estimate them. Recent greater financial data availability has allowed the development of models that focus on price discovery and use more statistical complex methodologies like GMM or VAR. This paper analyses this set of models that allows the estimation of the bid–ask spread components from price dynamics, specifically, the estimation of the adverse selection component in time series. Actually, this sort of models are a powerful tool to investigate how information is incorporated into quotes

Assessing the sensitivity of a Mediterranean commercial rangeland to droughts under climate change scenarios by means of a multidisciplinary integrated model

Rangeland productivity is strongly conditioned by the amount and temporal distribution of precipitation. Thus, the worsening of droughts with climate change could be a serious threat to their existence. This paper presents a modelling study aimed at evaluating the sensitivity of a valuable type of commercial rangelands, namely Spanish dehesas, to increases in the frequency and intensity of droughts driven by climate change. The assessment consisted in a multi-way ANOVA carried out on the basis of 5400 simulations of a multidisciplinary integrated model. It included two blocking factors linked to climate change scenarios, namely Representative Concentration Pathway and downscaling method, and two treatment factors, namely return period and severity of droughts. The levels of all factors were included as part of the simulation scenarios. The response variables constituted a summary of model's behaviour throughout one simulation. They were average profits per farmer and average stocking rate, both calculated over the entire simulation period, and remaining soil depth at the end of the simulation. The effects of the treatment factors on the response variables were small for all blocks, thereby suggesting that the sensitivity, and thus the vulnerability, of Spanish dehesas to the worsening of droughts would be low under climate change. Farmers were defined as conservative in all model simulations, that is, they minimized changes in the size of their herds and bought supplementary feed to meet shortfalls in livestock feed unless it was excessively expensive. Thus, we conclude that this group strategy could explain the adaptive capacity of Spanish dehesas to droughts. This paper shows that multidisciplinary integrated models are valuable learning tools to acquire insights into the relationships between climate, ecologic and socio-economic factors. Although there is a recurrent call for holistic studies, they are still rare in the rangeland literature. Hopefully, this paper will motivate some researchers to consider this approach.This paper was written within the framework of Junta de Andalucía Research Project ‘Mesotopos: Habitat Conservation and Land Degradation in Andalucía’ P08 RNM-4023. The partial support of the Chilean FONDECYT Research Project 1161105 is also acknowledged. The authors are funded by the European Research Council grant agreement n◦ 647038 (BIODESERT)

Trichomonas vaginalis: la versatilidad de un parásito tenaz

Trichomonosis is one of the most prevalent nonviral sexually transmitted infection (S.T.I.) worldwide, with an estimated 276 million cases per year according to WHO overview. Little attention is paid to this disease, although more than 50% of S.T.I. curable are caused by this protozoon. Clinically, Trichomonas vaginalis infection can produce a wide range of pathological manifestations, from asymptomatic presentation to severe inflammatory and invasive lesions in the genitourinary tract of both men and women. The possible role displayed by T. vaginalis as a viral vector might also explain its role as a risk factor in the development of cervical and prostate neoplasia. In addition, trichomonosis is strongly associated with transmission and acquisition of other bacterial and viral pathogens like HIV. T. vaginalis is a very complex organism and has developed diverse mechanisms for the colonization of the genitourinary tract probably due to its extensive genome. This parasite must survive in a hostile environment exposed to continue fluctuations. Surprisingly, T. vaginalis possesses one of the largest and most repetitive genomes, with a core set of 60,000 protein-coding genes. According to all these features, T. vaginalis could be considered an excellent model of parasite to be studied in order to better understand the dynamics and immune evasion mechanisms of such versatile parasite.La tricomonosis urogenital humana, causada por el parásito Trichomonas vaginalis, es una de las infecciones de transmisión sexual (I.T.S.) de mayor prevalencia en el mundo, con un total de 276 millones de casos cada año, según la OMS.Algunos autores la han calificado como una enfermedad desatendida u olvidada ligada a la pobreza, a pesar de que más del 50% de las I.T.S. curables se deben a este agente etiológico. La tricomonosis cursa con un rango amplio de manifestaciones clínicas, que van desde casos asintomáticos hasta cuadros más graves e invasivos de los conductos genitourinarios. Se ha relacionado la infección con el riesgo de adquisición y transmisión del VIH y de lesiones preneoplásicas de cérvix y próstata. Este protozoo parásito presenta una gran variabilidad intraespecífica en su comportamiento patogénico, probablemente por el tamaño y complejidad de su genoma, con más de 60.000 genes codificantes. Es capaz de sobrevivir y colonizar un nicho complejo sometido a constantes fluctuaciones, el aparato genitourinario, pasando desapercibido en muchos casos. El tamaño y complejidad de su genoma convierten a T. vaginalis en un parásito de gran interés científico para el estudio de los mecanismos de patogenia y evasión de la respuesta inmune

Modelado físicamente riguroso de tejidos biológicos blandos a partir de datos

El Trabajo de Fin de Máster "Modelado físicamente riguroso de tejidos biológicos blandos a partir de datos" tiene como objetivo desarrollar una herramienta basada en inteligencia artificial, más concretamente en las llamadas redes SPNN (Structure-Preserving Neural Networks), que sea capaz de aprender leyes de comportamiento de tejidos biológicos blandos para reproducir la evolución temporal de diferentes variables seleccionadas que definen su comportamiento en base al formalismo GENERIC (General Equation for the Non-Equilibrium Reversible-Irreversible Coupling), que asegura el cumplimiento de las leyes básicas de la termodinámica.<br /

Main pathologies causing confiscation of equine livestock intended for human consumption

El caballo es un animal herbívoro que se utiliza para diversos fines, siendo uno de ellos la pro-ducción de carne destinada a consumo humano. A nivel mundial, la producción de carne de caballo está liderada por Asia, dejando a Europa en tercer lugar. España no es un país con gran tradición de consumo de esta carne, aun así, 18.275 explotaciones se dedican a ello, sacrificando 52.908 caballos al año. Concretamente, en la Comunidad Valenciana se sacrifican 6.368 caballos aproximadamente cada año. El objetivo del presente estudio es poder determinar, mediante la inspección ante mortem y post mortem, las causas de los principales decomisos producidos en el ganado equino destinado a consumo humano, reconociendo las lesiones y realizando el dictamen pertinente en cada uno de los órganos y partes del animal. Para ello, se ha llevado a cabo un es-tudio experimental en el que se han inspeccionado 794 caballos durante el año 2016 y los meses transcurridos de enero a abril de 2017. Se han recogido datos de las inspecciones realizadas du-rante la jornada laboral en el llamado “Parte diario de inspección de equino”, donde se registran cada uno de los decomisos generados y sus causas. Conociendo los sacrificios y la cantidad de decomisos realizados, se observa que el decomiso total queda relegado a un segundo plano y que el decomiso parcial es el predominante. El pulmón es el decomiso parcial más habitual, seguido del hígado. Las principales patologías causantes de decomisos son las neumonías y en un número elevado de casos se decomisan por decisión del veterinario oficial.The horse is a herbivorous animal that is used for various purposes, one of them is the produc-tion of meat intended for human consumption. Worldwide, horse meat production is led by Asia, leaving Europe in third place. Spain is not a country with a great tradition of consumption of this meat, even so, 18,275 farms are dedicated to it, sacrificing 52,908 horses per year. Specif ically, 6,368 horses are slaughtered approximately in a year in the Valencian Community. The objective of the present study is to determine, through antemortem and postmortem inspection, the causes of the main seizures produced in equine livestock destined for human consumption, recognizing the lesions and taking the pertinent decision in each of the organs and parts of the animal. To this end, an experimental study was carried out in 794 horses in 2016 and during the months from January to April 2017. Data have been collected from the inspections carried out during the working day in the so-called “Daily Equine Inspection Part’’, where each of the gen-erated seizures and their causes are recorded. Knowing the sacrifices and the amount of seizures made, it is observed that total confiscation is relegated to a second plane and partial seizure is the predominant one. The lung is the most common partial seizure, followed by the liver. The main pathologies causing seizures are pneumonias, and a large number of cases are seized by decision of the official veterinarian.Veterinari

Antiparasitic properties of cantharidin and the blister beetle berberomeloe majalis (Coleoptera: Meloidae)

Cantharidin (CTD) is a toxic monoterpene produced by blister beetles (Fam. Meloidae) as a chemical defense against predators. Although CTD is highly poisonous to many predator species, some have evolved the ability to feed on poisonous Meloidae, or otherwise beneficially use blister beetles. Great Bustards, Otis tarda, eat CTD-containing Berberomeloe majalis blister beetles, and it has been hypothesized that beetle consumption by these birds reduces parasite load (a case of self- medication). We examined this hypothesis by testing diverse organisms against CTD and extracts of B. majalis hemolymph and bodies. Our results show that all three preparations (CTD and extracts of B. majalis) were toxic to a protozoan (Trichomonas vaginalis), a nematode (Meloidogyne javanica), two insects (Myzus persicae and Rhopalosiphum padi) and a tick (Hyalomma lusitanicum). This not only supports the anti-parasitic hypothesis for beetle consumption, but suggests potential new roles for CTD, under certain conditions.This research was funded by MINECO/FEDER, Spain, Grant no. CTQ2015-64049-C3-1-R; Ministerio de Economía y Competitividad, Spain (MINECO/FEDER), Grant no. CGL2017-87206-

Metamorfoseando: trabajando el currículum de forma transversal en educación primaria a través de las mariposas

El uso de insectos vivos en las aulas es un recurso que, a pesar de presentar grandes beneficios educativos en el proceso de enseñanza-aprendizaje, resulta relativamente inexplorado en las aulas de centros educativos españoles. El presente trabajo presenta una secuencia didáctica, enmarcada en el currículo del cuarto curso de Educación Primaria, la cual gira alrededor de la temática delas mariposas. Además de las actividades principales, que se centran en el uso de mariposas vivas, también se ofrecen actividades complementarias, tales como un cuento interactivo, un timeline del ciclo de la mariposa y la instalación de un jardín de mariposas. Todas estas actividades muestran cómo, gracias al uso de un recurso educativo que está al alcance de todos, se puede dotar ala práctica docente de un enfoque más transversal

The TT Genotype of the STAT4 rs7574865 Polymorphism Is Associated with High Disease Activity and Disability in Patients with Early Arthritis

[Background] The number of copies of the HLA-DRB1 shared epitope, and the minor alleles of the STAT4 rs7574865 and the PTPN22 rs2476601 polymorphisms have all been linked with an increased risk of developing rheumatoid arthritis. In the present study, we investigated the effects of these genetic variants on disease activity and disability in patients with early arthritis. [Methodology and Results] We studied 640 patients with early arthritis (76% women; median age, 52 years), recording disease-related variables every 6 months during a 2-year follow-up. HLA-DRB1 alleles were determined by PCR-SSO, while rs7574865 and rs2476601 were genotyped with the Taqman 5′ allelic discrimination assay. Multivariate analysis was performed using generalized estimating equations for repeated measures. After adjusting for confounding variables such as gender, age and ACPA, the TT genotype of rs7574865 in STAT4 was associated with increased disease activity (DAS28) as compared with the GG genotype (β coefficient [95% confidence interval] = 0.42 [0.01–0.83], p = 0.044). Conversely, the presence of the T allele of rs2476601 in PTPN22 was associated with diminished disease activity during follow-up in a dose-dependent manner (CT genotype = −0.27 [−0.56– −0.01], p = 0.042; TT genotype = −0.68 [−1.64– −0.27], p = 0.162). After adjustment for gender, age and disease activity, homozygosity for the T allele of rs7574865 in STAT4 was associated with greater disability as compared with the GG genotype. [Conclusions] Our data suggest that patients with early arthritis who are homozygous for the T allele of rs7574865 in STAT4 may develop a more severe form of the disease with increased disease activity and disability.This work was partially supported by the RETICS (Redes Tematicas de Investigación Cooperativa, Cooperative Research Thematic Networks) Program, RD08/0075 (RIER) and FIS (Fondo de Investigación en Salud) Health Research Fund grant FIS 08/0754 to IG-A from Instituto de Salud Carlos III (ISCIII; www.isciii.es) and by grants from the European Innovative Medicines Initiative and BTCure Program (http://www.life-sciences-europe.com/orga​nisation/btcure-project-imi-efpia-201103​-innovative-medicines-initiative-2001-28​657.html). The work of IG-A was in part supported by a Research Intensification Grant from the National Health Care System (Instituto Carlos III; www.isciii.es), Madrid, Spain