The fractional volatility model : no-arbitrage, leverage and completeness

When the volatility process is driven by fractional noise one obtains a model which is consistent with the empirical market data. Depending on whether the stochasticity generators of log-price and volatility are independent or are the same, two versions of the model are obtained with different leverage behaviors. Here, the no-arbitrage and completeness properties of the models are rigorously studied

Intersection local times of fractional Brownian motions with H∈(0,1)H\in(0,1) as generalized white noise functionals

In $\R^d$, for any dimension $d\geq 1$, expansions of self-intersection local times of fractional Brownian motions with arbitrary Hurst coefficients in $(0,1)$ are presented. The expansions are in terms of Wick powers of white noises (corresponding to multiple Wiener integrals), being well-defined in the sense of generalized white noise functionals.Comment: 17 page

Development of a metric of aquatic invertebrates for volunteers (MAIV): a simple and friendly biotic metric to assess ecological quality of streams

Citizen science activities, involving local people in volunteer-supported and sustainable monitoring programs, are common. In this context, the objective of the present work was to develop a simple Metric of Aquatic Invertebrates for Volunteers (MAIV), including a user-friendly tool that can be easily accessed by volunteers, and to evaluate the e ciency of a volunteer monitoring program following an audit procedure. To obtain MAIV values, macroinvertebrate communities were reduced to 18 surrogate taxa, which represented an acceptable compromise between simplicity, e ciency, and reproducibility of the data, compared to the regular Water Framework Directive monitoring. When compared to results obtained with the National Classification System of Portugal, MAIV accurately detected moderate, poor, and bad ecological status. Thus, MAIV can be used by volunteers as a complement to the o cial monitoring program, as well as a prospective early warning tool for local problems related to ecological quality. Volunteers were students supervised by their teachers. Results obtained by volunteers were compared to results obtained by experts on macroinvertebrate identification to measure the e ciency of the procedure, by counting gains and losses on sorting, and identification. Characteristics of groups of volunteers (age and school level) did not influence significantly the e ciency of the procedure, and generally results of volunteers and experts matched.info:eu-repo/semantics/publishedVersio

The effect of hydrogen cyanamide on bud break and yield of kiwifruit in Northwest-Portugal

Kiwifruit (Actinidia deliciosa cv. Hayward) was introduced into Northwest Portugal at the early 1970's increasing its importance up to date. The main objective of orchard management is to find out the cultural techniques suitable for the region, in order to obtain good yield and quality fruit. Winter chilling (less than or equal to7.2degreesC) plays a significant role in kiwifruit break dormancy. Insufficient chilling can be countered by chemical agents as hydrogen cyanamid (Dormex). The objective of this research was to quantify the efficiency of hydrogen cyanamide (0%, 4%, and 6%) on bud break dormancy and yield and fruit quality. Experiments were carried out over two years on a mature 'Hayward' kiwifruit orchard. The results showed that 4% Dormex was the most efficient in increasing marketable yield due to increase of flower bud formation and higher level of fruit set. There were no significant differences among treatments in soluble solids content, flesh firmness and dry weight. Titrable acidity showed higher values with increased Dormex concentration

Role of benzalkonium chloride surface preconditioning in the increased resistance of biofilms to removal and disinfection

The main goals of the present study was to ascertain the role of surface preconditioning in the biofilm sanitation (removal and disinfection) ability of the cationic surfactant benzalkonium chloride (BC) and to investigated whether BC preconditioning can be a factor of the increased resistance of the Pseudomonas fluorescens biofilms to the surfactant. Prior to biofilm formation, coupons of two distinct materials (stainless steel and silicone rubber) currently used on medical and industrial processing facilities were exposed to several sub-effective concentrations of BC for 30 min. Afterwards, these conditioned coupons were used as the surfaces to form biofilms in a chemostat for 6 days. The antimicrobial action of BC on the biofilms was assessed by means of respiratory activity, due to oxygen consumption, and biofilm mass. The results showed that BC preconditioning, by itself, did not prevent or impair biofilm formation. In general, the mass and respiratory activity of the biofilms developed on the conditioned coupons increased with the increase of the BC concentration used in the preconditioning. The data related with BC application to the bacterial biofilms formed on the conditioned metal and rubber coupons showed that biofilms became more difficult to inactivate, especially those that have been developed in the coupons preconditioned with the higher BC concentrations. Thus, it can be concluded that the antimicrobial ability of BC was considerably disturbed when the surfaces are preconditioned with the surfactant. Based merely on this data, it can be speculated that, in the initial adhesion stage, the contact of the P. fluorescens with the BC residues adsorbed on the coupons surface, due to preconditioning, induces bacteria resistance when they are entrapped in a developed biofilm and submitted to BC aggression.IBQF, and the Portuguese Foundation for Science and Technology (FCT

Chaetomellic acid A treatment improves oxidative stress in rats with renal mass reduction

Chaetomellic acid A (CA) is a potent and highly specific inhibitor of Ras farnesyl-protein transferase that has shown to decrease oxidative stress in rats with brain damage. Oxidative stress has been suggested to play an important role in the pathogenesis of chronic renal disease. Thus, the aim of this work was to evaluate the effect of chronic treatment with CA on oxidative stress in a model of renal mass reduction. Male Wistar rats were subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been placed in four experimental groups: RMR rats without treatment (n=12); RMR rats treated with CA (n=8); SO rats without treatment (n=13); SO rats treated with CA (n=13). CA was intraperitoneally administered in a dose of 0.23 μg/Kg three times a week for six months. To evaluate the effect of CA on renal redox potential, the status of oxidative stress in renal tissues was determined. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity, and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CA administration significantly increased catalase and GR activity (p<0.05), and increased GSH/GSSG ratio, but no significant difference between the treated and no treated groups was found in this ratio. These data suggest that CA can attenuate 5/6 RMR-induced oxidative stress and therefore, contribute to prevention of progressive renal failure in chronic renal disease

Thermal analysis of a polymorphic azo dye derived from 2-amino-5-nitrothiazole

An azo dye, derived from 2-amino-5-nitrothiazole and a substituted N,N-dimethyl aniline, was studied by various techniques. Two sets of proton signals were obtained by NMR in CDCl3 solution, suggesting that two polymorphs coexist, however only one set of signals is observed in DMSO solution. Differential scanning calorimetry and thermogravimetric analysis were used to confirm the existence of two forms. The events registered during thermal treatment of a sample were assigned to a glass transition, recrystallization and fusion of crystalline compounds. Hot-stage microscopy was used to obtain images of the dye samples at various stages of the heating program and these observations support the interpretation of the calorimetric results.Fundação para a Ciência e a Tecnologia (FCT

Cytogenetic Tools to Study the Biodiversity of Neotropical Fish: From the Classic to the Advent of Cell Culture

Neotropical Ichthyofauna is considered the richest and most diverse in the world. All this biodiversity has attracted attention from researchers from different areas of study, including the cytogenetics. Many cytogenetics studies have search to understand the evolution of macro and micro karyotype structure of these different groups of fish, and classical and molecular cytogenetics techniques have contributed significantly for all knowledge of this karyotypic diversity. Recently, the use of cell cultures as an alternative to obtaining mitotic chromosomes opening up new opportunities to study groups that have not been explored or have not yet been cytogenetically investigated. In this work, we take a chronological overview of the advances of different cytogenetic techniques (“in vivo” and “in vitro” methods to obtain the chromosome, C-banding, the detection of nucleolar organizer regions (Ag-RON), fluorescent in situ hybridization (FISH) with several repetitive probes and paint chromosome) over the decades and how these techniques helped elucidate questions of the organization and function of the fish genome