363 research outputs found
Maturity and volatility effects on UK smiles or dying smiling?
The “smile effect” is a result of an empirical observation of the options’ implied volatility with the same expiration date, across different exercise prices. However, its shape has been under discussion seeming to be dependent on the option underlying security. In this paper, and filling up a scarce empirical research on the topic, we used liquid equity options on 9 stocks traded on the London International Financial Futures and Options Exchange (LIFFE) between August 1990 and December 1991. We tested two different hypothesis for testing two different phenomena: (1) the increase of the “smile” as maturity approaches; (2) and the association between the smile and the volatility of the underlying stock. In order to estimate implied volatilities for unavailable exercise prices, we modelled the smile using cubic B-spline curves. We found empirical support for the smile intensification (the U-shape is more pronounced) as maturity approaches as well as when volatility rises. However, we found two major sources of disagreement with the literature on stochastic volatility models. First, as maturity approaches, out-of-themoney options’ implied volatility tends to be higher than the implied volatility of in-the-money options. Second, as the volatility of the underlying asset increases, the implied volatility of in-the-money options tends to be higher than implied volatility of out-of-the-money options.Financial support granted by the Fundação para a Ciência e a Tecnologia (FCT) and the Programa Praxis XXIinfo:eu-repo/semantics/publishedVersio
Programa De Rastreamento Populacional De Câncer De Colo Uterino Organizado: é Um Bom Momento Para O Brasil De Hoje
38416116
Primary Melanoma Of The Uterine Cervix Figo Stage Iii B.
The primary malignant melanoma of the uterine cervix is rare, usually diagnosed at an advanced stage and with poor prognosis. The diagnosis is made through histological evaluation and confirmed by special staining procedures. Radical surgery has been used and advocated. However in its advanced stages chemotherapy, immunotherapy or radiotherapy can be employed. A case of a patient with malignant melanoma of the uterine cervix, Stage IIIb, is presented in addition to a clinical and pathological discussion.11641778178
Biomechanical study of cervical spine with pathology
O conhecimento da cinemática da coluna cervical é uma ferramenta muito importante, dado que esta região é uma das estruturas mais complexas do esqueleto humano e porque a incidência de incapacidade que pode resultar de traumas ou doenças degenerativas é relativamente elevada. O principal objetivo deste estudo consiste na análise e comparação da fusão cervical anterior e/ou fusão cervical posterior como possíveis tratamentos para uma fratura do tipo C2.2, segundo a classificação da AO spine injury classification system, sendo que este estudo poderá auxiliar os profissionais de saúde na escolha do melhor método de fusão. Para o efeito, foi construído um modelo 3 D de elementos finitos do segmento cervical C4‐C5‐C6. Foram modelados os respetivos discos intervertebrais (IV ) e os seus componentes, nomeadamente o núcleo pulposo, o anel fibroso, as fibras lamelares e as placas cartilaginosas. Os 6 conjuntos de ligamentos (longitudinais anteriores, longitudinais posteriores, interespinhosos, supraespinhosos, amarelos e capsulares) foram também modelados, assim como as articulações intervertebrais.
A simulação de uma fratura foi realizada em 3 passos distintos: introdução de uma fratura na zona anterior da vértebra C5, o comprometimento (rompimento) dos ligamentos da região posterior e o deslizamento da vértebra C5. A instrumentação utilizada nos tratamentos em estudo e ainda a substituição dos discos lesados por um enxerto ósseo proveniente do ilíaco foram também modeladas.
Com este estudo, concluiu‐se que a fusão cervical anterior e posterior apresenta melhores resultados em comparação com os outros tipos de fusão cervical estudados em termos de deslocamento da unidade funcional.The knowledge of the kinematics of the cervical spine is a very important tool, since this region is one of the more complex structures of the human skeleton and because the incidence of failure that may result from trauma or degenerative diseases is relatively high. The main objective of this study is the analysis and comparison of anterior cervical fusion and/or posterior cervical fusion as possible treatments for a fracture of type C2.2 according to AO spine injury classification system, and this study may assist health professionals in choosing the best fusion technique. To this end we built a 3 D finite element model of the cervical segment C4‐C5‐C6. Their intervertebral discs (IV ) and its components, namely the nucleus pulposus, the annulus fibrosus, the fibers and the lamellar cartilaginous plates were modeled. Six sets of ligaments (anterior longitudinal, posterior longitudinal, interspinous, suprespinous, yellow and capsular) and the facet joints were also modeled.
The simulation of the fracture was performed in 3 different steps: introduction of a fracture zone in the previous C5 vertebra, rupture of the ligaments of the posterior region and the sliding of the C5 vertebra. The instrumentation used in the study treatments and even the replacement of the damaged disc by bone graft from the iliac bone, were also modeled.
Analyzing the displacements of the functional unit it was concluded that the anterior and posterior cervical fusion provides the best results compared to other types of cervical fusion studied in terms of displacement of the functional unit.Peer Reviewe
Effect of hydroxyurea on G gamma chain fetal hemoglobin synthesis by sickle-cell disease patients
Hydroxyurea is used for sickle-cell disease patients in order to increase fetal hemoglobin synthesis and consequently decrease the severity of pain episodes. Fetal hemoglobin, which is formed by gamma-globin chains A and G, is present in a constant composition throughout fetal development: about 75% of Ggamma and 25% of Agamma. In contrast, adult red cells contain about 40% of Ggamma and 60% of Agamma. In the present study, we analyzed the effect of hydroxyurea induction on the gamma chain composition of fetal hemoglobin in 31 sickle-cell disease patients treated with hydroxyurea. The control group was composed of 30 sickle-cell disease patients not treated with hydroxyurea in clinical steady state. The patients were older than 13 years and were not matched for age. All patients were seen at Hemocentro/UNICAMP and Boldrini Infantile Center, Campinas, SP, Brazil. The levels of total hemoglobin were significantly higher in patients treated with hydroxyurea (mean ± SD, 9.6 ± 2.16 g/dl) than in untreated patients (8.07 ± 0.91 g/dl). Fetal hemoglobin levels were also higher in treated patients (14.16 ± 8.31%) than in untreated patients (8.8 ± 4.09%), as was the Ggamma/Agamma ratio (1.45 ± 0.78 vs 0.98 ± 0.4, P < 0.005). The increase in the Ggamma/Agamma ratio in patients treated with hydroxyurea suggests the prevalence of a pattern of fetal hemoglobin synthesis, whereas patients not treated with hydroxyurea maintain the adult pattern of fetal hemoglobin synthesis. Because no correlation was observed between the Ggamma/Agamma ratio and total hemoglobin or fetal hemoglobin levels, the increase in Ggamma chain synthesis may not imply a higher production of hemoglobin.1289129
Structural, morphological and dielectric properties of ErNbO4 prepared by the sol-gel method
In this work, ErNbO4 samples were prepared using the sol-gel method, through the citrate route, and heat-treated at temperatures between 700 and 1600 °C. The structure was studied by X-ray diffraction and Raman spectroscopy. The crystallite size was estimated using the Rietveld refinement and the Sherrer's formula, presenting values from 31.27 to 86.65 nm and from 40.96 to 78.23 nm, respectively. The morphology was studied by scanning electron microscopy. The measurement of the complex permittivity was made using the small perturbation technique, with a cavity operating in TE105 mode, at resonant frequency of 2.7 GHz. The increase of the treatment temperature promoted the increase of the dielectric constant and the dielectric losses were still maintained with low values, allowing their potential application in electric storage devices. The dielectric constant of ErNbO4 in a zero porosity sample case was estimated and compared with the experimental values.publishe
Experimental assessment of the performance of two marine coatings to curb biofilm formation of microfoulers
Biofilms formed on submerged marine surfaces play a critical role in the fouling process, causing increased fuel consumption, corrosion, and high maintenance costs. Thus, marine biofouling is a major issue and motivates the development of antifouling coatings. In this study, the performance of two commercial marine coatings, a foul-release silicone-based paint (SilRef) and an epoxy resin (EpoRef), was evaluated regarding their abilities to prevent biofilm formation by Cyanobium sp. and Pseudoalteromonas tunicata (common microfoulers). Biofilms were developed under defined hydrodynamic conditions to simulate marine settings, and the number of biofilm cells, wet weight, and thickness were monitored for 7 weeks. The biofilm structure was analyzed by confocal laser scanning microscopy (CLSM) at the end-point. Results demonstrated that EpoRef surfaces were effective in inhibiting biofilm formation at initial stages (until day 28), while SilRef surfaces showed high efficacy in decreasing biofilm formation during maturation (from day 35 onwards). Wet weight and thickness analysis, as well as CLSM data, indicate that SilRef surfaces were less prone to biofilm formation than EpoRef surfaces. Furthermore, the efficacy of SilRef surfaces may be dependent on the fouling microorganism, while the performance of EpoRef was strongly influenced by a combined effect of surface and microorganism.This research was funded by Base Funding - UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology, and Energy - LEPABE - funded by national funds through the FCT/MCTES (PIDDAC), “CVMAR+i - Industrial Innovation and Marine Biotechnology Valorization” project, funded by INTERREG V Espanha Portugal (POCTEP) (0302_CVMAR_I_1_P), and UIDB/04423/2020 and UIDP/04423/2020 (CIIMAR). The research work was also supported by UIDB/04046/2020 and UIDP/04046/2020 research units grants, Portugal (to BioISI). R.T.-S. thanks the receipt of a junior researcher fellowship from the Project PTDC/BII-BIO/29589/2017 POCI-01-0145-FEDER-029589 funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES. L.C.G. thanks the Portuguese Foundation for Science and Technology (FCT) for the financial support of her work contract through the Scientific Employment Stimulus-Individual Call-[CEECIND/01700/2017]. Atomic force microscopy technique was performed at the Biointerface and Nanotechnology i3S Scientific Platform with the assistance of Manuela Brás
Electrical, morphology and structural properties of biodegradable nanocomposite polyvinyl-acetate/ cellulose nanocrystals
In this work, the dielectric properties and the electrical conductivity of polyvinyl acetate (PVAc) polymer doped with cellulose nanocrystals (CNC), extracted from the date palm rachis, are reported. We investigate the filler effect on the molecular mobility of the PVAc polymer chains and the charge transport properties of this material. PVAc/CNC films structure was characterized by powder X-Ray diffraction (XRD), showing the crystalline behavior of the cellulose filler. The dielectric properties were investigated using impedance spectroscopy, in the frequency range of 102–106 Hz and temperatures from 200 to 350 K. A β relaxation, assigned to the motions of the -OCOCH3 side groups, and α relaxation, associated with the glass transition of the PVAc matrix, can be detected.publishe
HASTE INTRAMEDULAR DE POLIPROPILENO, COMBINADA OU NÃO A BIOMATERIAIS, NO TRATAMENTO DE FRATURAS INDUZIDAS NO ÚMERO DE POMBOS
O trabalho teve por objetivo avaliar a utilização da haste intramedular de polipropileno,
combinada ou não a biomateriais de origem bovina, no tratamento de fraturas transversas
induzidas no terço médio do úmero direito de pombos-domésticos. No grupo I (n=7), a fratura foi
estabilizada por meio de haste intramedular de polipropileno aplicada em ambos os fragmentos
da fratura, sem ultrapassar as articulações. No grupo II (n=7) utilizou-se a mesma fixação,
porém foi aplicado junto ao foco de fratura uma mistura de biomateriais, constituída de proteínas
morfogenéticas do osso e aglutinante de colágeno liofilizado. Em ambos os grupos, a asa foi
imobilizada junto ao corpo com bandagem em forma de 8 por um período de 30 dias. Com seis
semanas de pós-operatório, cinco fraturas do grupo I e quatro do grupo II estavam totalmente
consolidadas. Foram observadas uma não consolidação hipertrófica (grupo I) e duas não
consolidações com deslocamento do eixo ósseo (grupo II). Exceto as três aves que apresentaram
complicações nas fraturas, as demais recuperaram a capacidade de vôo. Foi possível concluir
que a haste intramedular de polipropileno foi um método de imobilização de eficácia limitada e
os biomateriais utilizados não estimularam a consolidação das fraturas.
Use of polypropylene intramedullary rod alone or combined with biomaterials for
treatment of induced humeral transverse fractures in pigeons
Abstract
The aim of this study was to evaluate a polypropylene intramedullary rod alone or
combined with biomaterials from bovine origin for the treatment of transverse fractures induced
in the midshaft of right humerus in pigeons. In group I (n=7) the fracture was immobilized using a
polypropylene intramedullary rod inserted into both fractured extremities without entering the joints.
The same device was used in group II (n=7). Additionally, the fractured site in group II animals
received a mixture of biomaterials composed by bone morphogenetic proteins and lyophilized
collagen. In both groups a cast was applied to the affected wing, which was immobilized with a
figure-of-8 bandage applied to the body and wing during 30 days. Complete healing was observed
after six weeks of surgery in five and four animals from groups I and II, respectively. Observed
complications included one hypertrophic nonunion (group I) and two nonunion with bone shaft
dislocation (group II). Except for the three pigeons that showed postoperative complications, the
remaining animals recovered the ability of flight. It was possible to conclude that the polypropylene
intramedullary rod is a limited method of immobilization and the biomaterials used in this study did
not stimulate fracture healing
I Ciclo de Conferências : Conselho Técnico Científico : temas atuais em investigação
A obra é constituída pelos resumos das comunicações apresentadas pelos docentes da Escola Superior Agrária do Instituto Politécnico de Castelo Branco e são referentes aos projetos de investigação nos quais estão envolvidos.O Conselho Técnico-Científico (CTC) da Escola Superior Agrária tomou posse no dia 9 de Fevereiro de 2010. As suas primeiras acções orientaram-se no sentido de dar cumprimento ao estabelecido nos Estatutos da Escola Superior Agrária do Instituto Politécnico de Castelo Branco, que entraram em vigor a partir de 14 de Janeiro de 2010. Estas acções centraram-se na re-organização interna da estrutura técnica e científica, na definição das estratégias de formação e de investigação, desenvolvimento e inovação (ID&I) da Escola Superior Agrária. Enquadrada nesta estratégia, o CTC considerou oportuno promover um ciclo de conferências, com o principal objectivo de criar um meio de apresentação e debate público do trabalho de ID&I desenvolvido por docentes e técnicos que possibilitasse, nas áreas de intervenção da ESA, o desenvolvimento de novas ideias e a criação de sinergias para estabelecimento de trabalhos pluridisciplinares e parcerias, não só a nível interno como também com stakeholders. A publicação das conferências realizadas neste primeiro mandato (2010-2012), disponibiliza a informação para um público mais alargado, visando contribuir de uma forma concreta para o desenvolvimento da região, aspecto de interesse prioritário na missão do IPCB/ESA
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