A polynomial hyperelastic model for the mixture of fat and glandular tissue in female breast

In the breast of adult women, glandular and fat tissues are intermingled and cannot be clearly distinguished. This work studies if this mixture can be treated as a homogenized tissue. A mechanical model is proposed for the mixture of tissues as a function of the fat content. Different distributions of individual tissues and geometries have been tried to verify the validity of the mixture model. A multiscale modelling approach was applied in a finite element model of a representative volume element (RVE) of tissue, formed by randomly assigning fat or glandular elements to the mesh. Both types of tissues have been assumed as isotropic, quasi-incompressible hyperelastic materials, modelled with a polynomial strain energy function, like the homogenized model. The RVE was subjected to several load cases from which the constants of the polynomial function of the homogenized tissue were fitted in the least squares sense. The results confirm that the fat volume ratio is a key factor in determining the properties of the homogenized tissue, but the spatial distribution of fat is not so important. Finally, a simplified model of a breast was developed to check the validity of the homogenized model in a geometry similar to the actual one

SPATIO-TEMPORAL PATTERNS OF JUVENILES IN EU PURSE SEINE FLEET CATCHES TARGETING TROPICAL TUNAS OVER THE PERIOD 1990-2019

The knowledge of the juvenile distribution in fisheries is essential to better manage the fishing effort on a stock. The exploration of a large dataset which covers 30 years of the purse seine fishery sampling enabled to study the spatio-temporal dynamic of the juvenile catches of the yellowfin and bigeye tunas. Results showed the existence of several areas of prime importance in terms of catch and concentration in juveniles with seasonal variations. Thus, the south of the fishing ground (Cape Lopez) was fished during winter month and the north during summer months (Cape Verde, Senegal y Mauritania). Offshore coastal zone and Gulf of Guinea were fished almost all along the year. This seasonal pattern is quite stable since the 90s but the proportion of juveniles in schools associated with floating objects tended to increase in both species. This preliminary study opened the way for further research on this important component of the fish stocks. La connaissance de la répartition des juvéniles dans les pêcheries est essentielle pour mieux gérer l'effort de pêche sur un stock. L'exploration d'un vaste jeu de données couvrant 30 ans d'échantillonnage de la pêcherie à la senne a permis d'étudier la dynamique spatio-temporelle des captures de juvéniles d'albacore et de thon obèse. Les résultats ont montré l'existence de plusieurs zones de première importance en termes de capture et de concentration des juvéniles avec des variations saisonnières. Ainsi, le sud de la zone de pêche (Cap Lopez) était pêché pendant les mois d'hiver et le nord pendant les mois d'été (Cabo Verde, Sénégal et Mauritanie). La zone côtière offshore et le golfe de Guinée ont été pêchés presque toute l'année. Bien que ce schéma saisonnier soit stable depuis les années 1990, la proportion de juvéniles dans les bancs associés à des objets flottants avait tendance à augmenter pour ces deux espèces. Cette étude préliminaire a ouvert la voie à d'autres recherches sur cette composante importante des stocks de poissons. El conocimiento de la distribución de los juveniles en las pesquerías es esencial para gestionar mejor el esfuerzo pesquero en un stock. La exploración de un gran conjunto de datos que abarca 30 años de muestreo de la pesquería de cerco permitió estudiar la dinámica espacio-temporal de las capturas de juveniles de rabil y patudo. Los resultados mostraron la existencia de varias zonas de importancia primordial en cuanto a la captura y concentración de juveniles con variaciones estacionales. Así, el sur del caladero (Cabo López) se pescaba durante el mes de invierno y el norte durante los meses de verano (Cabo Verde, Senegal y Mauritania). En la zona costera y en el golfo de Guinea se pescaba casi todo el año. Esta pauta estacional es bastante estable desde los años 90, pero la proporción de juveniles en los cardúmenes asociados a objetos flotantes tendió a aumentar en ambas especies. Este estudio preliminar abrió el camino a nuevas investigaciones sobre este importante componente de los stocks de peces.Versión del edito

Spatio-temporal patterns of juveniles in EU Purse sein fleet catch targetting tropical tunas over the period 1990-2019

The knowledge of the juvenile distribution in fisheries is essential to better manage the fishing effort on a stock. The exploration of a large dataset which covers 30 years of the purse seine fishery sampling enabled to study the spatio-temporal dynamic of the juvenile catches of the yellowfin and bigeye tunas. Results showed the existence of several areas of prime importance in terms of catch and concentration in juveniles with seasonal variations. Thus, the south of the fishing ground (Cape Lopez) was fished during winter month and the north during summer months (Cape Verde, Senegal y Mauritania). Offshore coastal zone and Gulf of Guinea were fished almost all along the year. This seasonal pattern is quite stable since the 90s but the proportion of juveniles in schools associated with floating objects tended to increase in both species. This preliminary study opened the way for further research on this important component of the fish stocks.Versión del edito

Management of borderline ovarian tumours: A comprehensive review of the literature

Borderline ovarian tumours differ from epithelial ovarian cancer by their low incidence, frequent association with infertility, low association with mutations in BCRA genes, different percentages of the most common histological types, early stage diagnosis, and high survival rate, even when associated with peritoneal involvement. They occur in younger women, which is why one of the objectives in these patients will be the preservation of fertility. The management of these tumours has been widely discussed and still continues to be controversial. The latest findings underscore the importance of full staging in both radical and conservative surgery, to choose the most comprehensive treatment and obtain an accurate prognosis. One of the objectives of this article shall be the in-depth review of the indications, benefits, and disadvantages of each type of surgery, as well as the usefulness of the medical treatment. In addition, the article aims to review follow-up guidelines and to clarify the main prognostic factors that affect recurrence and survival of these patients

Spatio-temporal distribution of spinetail devil ray (Mobula mobular) in the eastern tropical Atlantic Ocean.

The distribution of the spinetail devil ray Mobula mobular in the eastern tropical Atlantic remains poorly known compared to the Pacific and Indian Oceans. We used fisherydependent data and generalized additive models to examine the environmental characteristics associated with the presence of M. mobular in the eastern Atlantic Ocean. Results revealed that the distribution of M. mobular is significantly associated with seasonal upwelling systems in coastal and pelagic areas. Our model predicted the presence of the species in areas where there is evidence of its occurrence, such as the Angolan upwelling system and the coast of Ghana. In addition, our model predicted new hotspot areas, including locations around the Mauritanian upwelling system, the Guinea coast, offshore Ghana and the south coast of Angola and Brazil, where sample sizes are limited. Those areas, as well as the environmental preferences depicted by the model, provide valuable information about the habitat and ecology of the spinetail devil ray. Future research lines derived from this study, as well as its limitations, are discussed. Furthermore, in light of our results we discuss the improvements that are needed to contribute to the conservation and management of this vulnerable species.Versión del edito

A preliminary analysis of spatiotemporal patterns in swordfish habitat distributions.

A species distribution model (SDM) for swordfish that was in the development stage has been finalized. The model used detailed biological and oceanographic data to define the spatial distribution of Swordfish. The SDM adequately predicted Swordfish habitat (and thus fish) distributions such that it was found suitable for investigations into the spatiotemporal distribution of habitat. Results of this preliminary investigation supports the current hypothesized stock boundaries between the north and south Atlantic stocks used for management. Both the north and south Atlantic may be experiencing an expansion of habitat. This could result in decreased density of swordfish into a larger area and/or change MSY production metrics. A more detailed examination of this possibility is recommended.Versión del edito

Procedimiento para la detección de grietas en ejes de pala de aerogeneradores

Se presenta un procedimiento para detectar la existencia de una grieta en los ejes de pala de un aerogenerador, sin que sea necesario desmontar la maquina para el proceso de inspección. El procedimiento es sencillo de aplicar y con costes de inspección bastante reducidos. El método se basa en la variación de las tensiones en la superficie del eje, en una zona cercana a la de inicio de la grieta, al ir creciendo esta. Se analiza numéricamente mediante elementos finitos un modelo del eje y posteriormente se realizan dos ensayos con ejes de pala instrumentados mediante bandas extensométricas, analizando la evolución de las tensiones con la longitud de grieta y la influencia de las condiciones de contorno.A procedure is presented to detect the existence of a crack in the blade shaft of wind power turbine, without it is necessary to dismount the it schemes for the inspection process. The procedure is simple of applying and with quite reduced inspection costs. The method is based on the variation of the stress in the surface of the shaft, in a near area to that of beginning of the crack, when going growing this. lt is analysed numerically by means of finite elements. They are carried out tests with two shafts with strain gauges, analysing the evolution of the stress with the crack dimension and the influence of the boundary conditions

Effect of freezing storage time on the elastic and viscous properties of the porcine TMJ disc

The correct characterisation of the articular disc of the temporomandibular joint (TMJ) is key to study the masticatory biomechanics. For the interval from extraction until testing, freezing is the most used preservation technique for biological tissues, but its influence on their behaviour is still unclear. An important error can be committed in the characterisation of such tissues if freezing has any effect on their mechanical properties. Thus, the aim of this study was to determine whether the freezing storage time causes any change in the mechanical properties of the TMJ discs. To check that, the specimens were stored in a °C freezer during different time intervals: 1 day, 1 week, 1 month and 3 months. Fresh specimens, tested right after extraction, were used as the control group. Compressive stress relaxation tests were carried out on the specimens and a quasi-linear viscoelastic (QLV) model was used to fit the experimental curves. A statistical analysis detected significant differences among the groups. Post-hoc tests determined that freezing the specimens more than 30 days may lead to changes in the viscoelastic properties of the tissue.Junta de Andalucía P07-TEP-0311

Comparison of different constitutive models to characterize the viscoelastic properties of human abdominal adipose tissue. A pilot study

Knowing the mechanical properties of human adipose tissue is key to simulate surgeries such as liposuction, mammoplasty and many plastic surgeries in which the subcutaneous fat is present. One of the most important surgeries, for its incidence, is the breast reconstruction surgery that follows a mastectomy. In this case, achieving a deformed shape similar to the healthy breast is crucial. The reconstruction is most commonly made using autologous tissue, taken from the patient's abdomen. The amount of autologous tissue and its mechanical properties have a strong influence on the shape of the reconstructed breast. In this work, the viscoelastic mechanical properties of the human adipose tissue have been studied. Uniaxial compression stress relaxation tests were performed in adipose tissue specimens extracted from the human abdomen. Two different viscoelastic models were used to fit to the experimental tests: a quasi-linear viscoelastic (QLV) model and an internal variables viscoelastic (IVV) model; each one with four different hyperelastic strain energy density functions to characterise the elastic response: a 5-terms polynomial function, a first order Ogden function, an isotropic Gasser-Ogden-Holzapfel function and a combination of a neoHookean and an exponential function. The IVV model with the Ogden function was the best combination to fit the experimental tests. The viscoelastic properties are not important in the simulation of the static deformed shape of the breast, but they are needed in a relaxation test performed under finite strain rate, particularly, to derive the long-term behaviour (as time tends to infinity), needed to estimate the static deformed shape of the breast. The so obtained stiffness was compared with previous results given in the literature for adipose tissue of different regions, which exhibited a wide dispersion.Ministerio de Economía y Competitividad DPI2011-2808

Gamete biology: Perspectives for Bluefin Tuna Aquaculture

Taking care of fish reproductive physiology and gamete biology allowed significant progresses in fry production control for many commercially interesting fish. Can it be a similar situation for bluefin tuna? Fish gamete production results from long processes controlled mainly by climatic conditions, mediated by neuroendocrine and endocrine factors. The possibility to monitor the development of germinal cells by successive sampling in individual fish which easily breed in captivity, has allowed learning about the sequences of gametogenesis and their control, as well as important characteristics of fish gamete biology. The female ovarian cycle involves a progressive accumulation of yolk in the oocytes (i.e., vitellogenesis), followed by cytoplasmic and nuclear events related to maturation and ovulation. The phases of vitellogenesis and maturation are of different duration in different species. In captive fish the endocrine regulation of reproduction may be disrupted by stress, thus preventing spontaneous spawning, while the application of exogenous hormones at the conclusion of gametogenesis allowed production of good quality gametes. In males, gamete production is not continuous as in mammals. Spermatozoa are produced after a cycle that includes a resting period, followed by continuous or discontinuous sequences of spermatogenesis (spermatogenesis sensu stricto, spermiogenesis and spermiation). The discontinuity of fish sperm production may induce a phenomenon of ageing along the period of spermiation, which decreases the quality of semen with time. Wild bluefin tuna breed in specific areas during a short summer spawning season. When kept in cages in the area of Cartagena (Spain), they present developed gamete stages at the same time as wild fish, but, until now, neither mating behavior nor eggs have been observed as was the case in Japan. It has not been possible to monitor individual gonad recrudescence by successive sampling, due to inability to handle the fish without causing mortality, so that the reproduction failure remains unexplained. Hormonal stimulation may be an interesting alternative but its use requires an assessment of gonadal stage to be performed properly. The high post-handling mortality of bluefin tuna in captivity is a real bottleneck for reproduction control. The improvement of handling and the use of less stress-susceptible individuals may be a major progress for bluefin tuna reproduction control. The occurrence of a second generation of juveniles in Japan, subjected to first domestication selection may provide very interesting experimental fish.EU 5FP REPRODOTT (Q5RS-2002-01355