Influence of the contact–impact force model on the dynamic response of multi-body systems

This work deals with contact–impact force models for both spherical and cylindrical contact surfaces. The incorporation of the friction phenomenon, based on the Coulomb friction law, is also discussed together with an effective computational strategy, which includes the automatic step size selection procedure. Impacts within a revolute clearance joint in a basic slider–crank mechanism are used as an example to compare the different contact force models. The collision is a prominent phenomenon in manymulti-body systems such as mechanisms with intermittent motion, kinematic discontinuities, and clearance joints. As a result of an impact, the values of the system state variables change very fast, eventually looking like discontinuities in the system velocities and accelerations. The impact is characterized by large forces that are applied and removed in a short time period. The knowledge of the peak forces developed in the impact process is very important for the dynamic analysis of multibody systems and it has consequences in the design process. The model for the contact–impact force must consider the material and geometric properties of the colliding surfaces, consider information on the impact velocity, contribute to an efficient integration, and account for some level of energy dissipation. These characteristics are ensured with a continuous contact force model, in which the deformation and contact forces are considered as continuous functions.FEDER - Project POCTI/2001/EME/38281.Fundação para a Ciência e a Tecnologia (FCT)

Conservative Management of Asymptomatic Adnexal Masses Classified as Benign by the IOTA ADNEX Model: a Prospective Multicenter Portuguese Study

This prospective multicentric study aiming to determine the incidence of complications (malignant transformation, torsion or rupture) during conservative management of adnexal masses was performed in two Portuguese tertiary referral hospitals. It included ≥18-year-old, non-pregnant patients with asymptomatic adnexal masses (associated IOTA ADNEX risk of malignancy < 10%) sonographically diagnosed between January 2016 and December 2020. Conservative patient management consisted of serial clinical and ultrasound assessment up to 60 months of follow-up, spontaneous resolution of the formation or surgical excision (median follow-up: 17.8; range 9-48 months). From the 573 masses monitored (328 premenopausal and 245 postmenopausal adnexal masses), no complications were observed in 99.5%. The annual lesion growth rates and increases in morphological complexity were similar in the premenopausal and postmenopausal patients. Spontaneous resolution, evidenced in 16.4% of the patients, was more common in the premenopausal group (p < 0.05). Surgical intervention was performed in 18.4% of the cases; one borderline and one invasive FIGO IA stage cancer were diagnosed. There was an isolated case of ovary torsion (0.17%). These data support conservative management as a safe option for sonographically benign, stable and asymptomatic adnexal masses before and after menopause and highlight the need for expedite treatment of symptomatic or increased-morphological-complexity lesions.info:eu-repo/semantics/publishedVersio

Aroma Compounds Prevision using Artificial Neural Networks Influence of Newly Indigenous Saccharomyces SPP in White Wine Produced with Vitis Vinifera Cv Siria

Commercial yeasts strains of Saccharomyces cerevisae are frequently used in white wine production as starters in fermentation process, however, these strains can affect the wine characteristics. The aim of this study was to evaluate the effect of three strains of Saccharomyces spp. (var. 1, 2 and 3) on wine aroma compounds produced in microvinification assays. Microvinification assays were carried out with Vitis vinifera cv Síria grapes using the strains in study as starters. Aroma compounds were identified and quantified by GC-FID and GC-MS. At the end of fermentation process and during the first three months of maturation some aroma compounds were detected, namely propanol, isobutanol, isoamyl acetate, isoamylic alcohol, ethyl hexanoate, ethyl lactate, hexanol, ethyl octanoate, 3-ethylhydroxibutirate, benzaldehyde, 3-methyl-2-butanol, 2,3-butanediol, g-butyrolactone, ethyl decanoate, diethyl succinate, methionol, 4-hydroxi-2-butyrolactone, heptanoic acid, phenylethyl acetate, ethyl dodecanoate, phenylethanol, octanoic acid, 2-methoxy-4- vinylphenol and decanoic acid. Artificial Neural Networks (ANNs) were used to predict the concentration of twelve wine aroma compounds from the phenyl ethanol, propanol, isobutanol, hexanol, heptanoic acid, octanoic acid and decanoic acid concentrations. Results showed that, either, maturation time and Saccharomyces strain used as starter influence the aroma compounds produced. Wines produced with S. cerevisae var. 1 and S. cerevisae var. 2 showed a similar composition in aroma compounds, relatively to the wines produced with the strain S. cerevisae var. 3. However, for S. cerevisae var. 1 and S. cerevisae var. 2 the time of maturation influence the aroma composition of wines. From a technological approach, the choice of yeast strain and maturation time has decisive influence on the aroma compounds produced

Ghost dynamics in the soft gluon limit

We present a detailed study of the dynamics associated with the ghost sector of quenched QCD in the Landau gauge, where the relevant dynamical equations are supplemented with key inputs originating from large-volume lattice simulations. In particular, we solve the coupled system of Schwinger-Dyson equations that governs the evolution of the ghost dressing function and the ghost-gluon vertex, using as input for the gluon propagator lattice data that have been cured from volume and discretization artifacts. In addition, we explore the soft gluon limit of the same system, employing recent lattice data for the three-gluon vertex that enters in one of the diagrams defining the Schwinger-Dyson equation of the ghost-gluon vertex. The results obtained from the numerical treatment of these equations are in excellent agreement with lattice data for the ghost dressing function, once the latter have undergone the appropriate scale-setting and artifact elimination refinements. Moreover, the coincidence observed between the ghost-gluon vertex in general kinematics and in the soft gluon limit reveals an outstanding consistency of physical concepts and computational schemes.Comment: 34 pages, 12 figure

Operacionalização do conceito de resiliência de forrageiras sob pastoreio rotativo aos distúrbios de mudanças climáticas

A resiliência de forrageiras sob pastoreio rotativo aos distúrbios de mudanças climáticas, em particular aos efeitos do déficit hídrico em veranicos, é um atributo básico para alcançar a sustentabilidade do sistema de produção de leite. Este trabalho apresenta um método baseado na dinâmica de sistemas para estimar os índices de resiliência: dureza, robustez, rapidez de recuperação e elasticidade. Um metamodelo para o manejo do ecossistema planta-animal foi adaptado para simular os efeitos dos distúrbios causados por veranicos no estoque de matéria seca dos piquetes. Os resultados dos experimentos in silico mostram diferenças entre as resiliências de dois cultivares de forrageiras para uma mesma magnitude de distúrbio e diferenças devido a época de ocorrência do déficit hídrico ser na fase de crescimento da forrageira ou na fase de uso dos piquetes pelos animais. O índice de rapidez de recuperação mostrou aderência conceitual para as condições de pastoreio rotativo, devido à premência de tempo na definição da entrada e saída dos animais nos piquetes. Concluiu-se que a operacionalização e avaliação da resiliência geram informações sobre a dinâmica do estoque de matéria seca ofertada para os animais e que estas informações são úteis para o planejamento do pastoreio rotativo

A permeabilidade entre o ensino vocacional e o ensino superior: análise dos percursos dos alunos dos CET da Universidade de Aveiro

A permeabilidade entre os sistemas formais de Ensino Vocacional (EV) e de Ensino Superior (ES) tem adquirido momentum em toda a comunidade Europeia, muito devido ao crescente número de estagiários que concluíram formação de nível cinco1 e pretendem continuar estudos para obter qualificações superiores. O surgimento de cursos de EV em instituições de ES, nomeadamente os extintos Cursos de Especialização Tecnológica (CET) e os atuais Cursos de Técnicos Superiores Profissionais (CTeSP), apresentam-se como uma realidade incontornável que em muito contribuiu e contribui para esse momentum. O presente capítulo incide, no âmbito da permeabilidade entre EV e ES, na análise da trajetória de diplomados dos CET que prosseguiram estudos no ES, designadamente na Universidade de Aveiro (UA). Pretende-se, por um lado, investigar se a permeabilidade promovida pela UA teve influência nessa mesma trajetória; por outro lado, ambiciona-se identificar que aspetos podem potenciar a permeabilidade desses estudantes. Espera-se, assim, contribuir para uma base de trabalho fundamental para o sucesso dos CTeSP no que diz respeito à permeabilidade entre EV e ES.publishe

Chorioallantoic and yolk sac placentation in the plains viscacha (Lagostomus maximus) - A caviomorph rodent with natural polyovulation

Objectives: Reproduction in the plains viscacha is characterized by the polyovulation of hundreds of oocytes, the loss of implantation and the development of 1-3 offspring. Our goal was to determine whether placental development was affected by these specializations. Study design: Thirteen placentas from early pregnancy to near-term pregnancy were analyzed using histological, immunohistochemical and transmission electron microscopy. Results: An inverted, villous yolk sac was present. Placentas were formed by the trophospongium, labyrinth and subplacenta. A lobulated structure with a hemomonochorial barrier was established early in pregnancy. Proliferating trophoblast that was clustered at the outer border and inside the labyrinth was responsible for placental growth. Trophoblast invasion resulted from the cellular trophoblast and syncytial streamers derived from the subplacenta. Different from other caviomorphs, numerous giant cells were observed. Conclusions: The principle processes of placentation in caviomorphs follow an extraordinarily stable pattern that is independent of specializations, such as polyovulation.Facultad de Ciencias Veterinaria

Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications.

BACKGROUND: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. METHOD: The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea. CONCLUSIONS: The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy.(undefined)info:eu-repo/semantics/publishedVersio

Placentation in Sigmodontinae: a rodent taxon native to South America

Background: Sigmodontinae, known as ""New World rats and mice,"" is a large subfamily of Cricetidae for which we herein provide the first comprehensive investigation of the placenta. Methods: Placentas of various gestational ages ranging from early pregnancy to near term were obtained for five genera, i.e. Necromys, Euryoryzomys, Cerradomys, Hylaeamys, and Oligoryzomys. They were investigated by means of histology, immunohistochemistry, a proliferation marker, DBA-lectin staining and transmission electron microscopy. Results: The chorioallantoic placenta was organized in a labyrinthine zone, spongy zone and decidua and an inverted yolk sac persisted until term. The chorioallantoic placenta was hemotrichorial. The interhemal barrier comprised fetal capillary endothelium and three layers of trophoblast, an outermost, cellular layer and two syncytial ones, with interspersed trophoblast giant cells (TGC). In addition, accumulations of TGC occurred below Reichert's membrane. The junctional zone contained syncytial trophoblast, proliferative cellular trophoblast, glycogen cells and TGC that were situated near to the maternal blood channels. In three of the genera, TGC were also accumulated in distinct areas at the placental periphery. PAS-positive glycogen cells derived from the junctional zone invaded the decidua. Abundant maternal uNK cells with positive response to PAS, vimentin and DBA-lectin were found in the decidua. The visceral yolk sac was completely inverted and villous. Conclusion: The general aspect of the fetal membranes in Sigmodontinae resembled that found in other cricetid rodents. Compared to murid rodents there were larger numbers of giant cells and in some genera these were seen to congregate at the periphery of the placental disk. Glycogen cells were found to invade the decidua but we did not identify trophoblast in the walls of the deeper decidual arteries. In contrast these vessels were surrounded by large numbers of uNK cells. This survey of wild-trapped specimens from five genera is a useful starting point for the study of placentation in an important subfamily of South American rodents. We note, however, that some of these rodents can be captive bred and recommend that future studies focus on the study of time dated pregnancies.This research was supported by grants from FAPESP (Proc. 07/51491-3 and\ud 09/53392-8)