Exames andrológicos em bovinos de carne na região do Alentejo, Portugal#

É referida a importância do exame andrológico em bovinos explorados em regime extensivo e como este serviço médico-veterinário tem vindo a ser oferecido em Portugal. Descrevem-se os resultados encontrados por uma equipa médico-veterinária em contexto prático na região do Alentejo e discute-se como podem ser avaliados estes resultados com critérios o mais objectivo possiveis para selecção dos melhores touros

Defect formation in superconducting rings: external fields and finite-size effects

Consistent with the predictions of Kibble and Zurek, scaling behaviour has been seen in the production of fluxoids during temperature quenches of superconducting rings. However, deviations from the canonical behaviour arise because of finite-size effects and stray external fields. Technical developments, including laser heating and the use of long Josephson tunnel junctions, have improved the quality of data that can be obtained. With new experiments in mind we perform large-scale 3D simulations of quenches of small, thin rings of various geometries with fully dynamical electromagnetic fields, at nonzero externally applied magnetic flux. We find that the outcomes are, in practice, indistinguishable from those of much simpler Gaussian analytical approximations in which the rings are treated as one-dimensional systems and the magnetic field fluctuation-free.Comment: 10 pages, 3 figures, presentation at QFS2012, to appear in JLT

A vortex description of the first-order phase transition in type-I superconductors

Using both analytical arguments and detailed numerical evidence we show that the first order transition in the type-I 2D Abelian Higgs model can be understood in terms of the statistical mechanics of vortices, which behave in this regime as an ensemble of attractive particles. The well-known instabilities of such ensembles are shown to be connected to the process of phase nucleation. By characterizing the equation of state for the vortex ensemble we show that the temperature for the onset of a clustering instability is in qualitative agreement with the critical temperature. Below this point the vortex ensemble collapses to a single cluster, which is a non-extensive phase, and disappears in the absence of net topological charge. The vortex description provides a detailed mechanism for the first order transition, which applies at arbitrarily weak type-I and is gauge invariant unlike the usual field-theoretic considerations, which rely on asymptotically large gauge coupling.Comment: 4 pages, 6 figures, uses RevTex. Additional references added, some small corrections to the tex

Semi-automatic quantification of the epicardial fat in CT images

In this work we present a technique to automatically or semi-automatically quantify the epicardial fat in noncontrasted Computed Tomography (CT) images. In CT images, the epicardial fat is very close to the pericardial fat, distincted only by the pericardium. The pericardium appears in the image as a very thin line, very hard to discriminate. To enhance the pericardium line and to remove noise as well as higher intensities due to calcifications, some pre-processing was applied, namely region growing, thresholding and average filtering techniques. To detect the pericardium line an algorithm was developed that considerer the heart anatomy to find control points belonging to that line. From the points detected an interpolation was done based on the cubic spline method. This method was also improved to avoid incorrect interpolation that occurs when one of the coordinates of the points is repeated. After having the line delineation, the pixels bellow the line were counted, considering only the pixels in the fat window (-190 to -30 Hounsfiel Units). In 10 images tested, in 4 the system fully automatically returned the correct value for epicardial fat. In the other 6 the system needed a small correction by moving 1 or 2 points to return the correct value of epicardial fat. The values of the automatic quantification were compared to the values obtained by the manual process, having 10% as maximum error allowed. We concluded that this method is able to, automatically or with a small interaction, return the value of the epicardial fat, for the non contrast CT images tested

DESCRIÇÃO DE TRÊS CASOS DE CRIPTORQUIDISMO EM EQUINOS DE RAÇA QUARTO DE MILHA EM PORTUGAL

O criptorquidismo consiste na não-descida dos testículos para o escroto, podendo ser uni ou bilateral. Cerca de 10% dos casos são de criptorquidismo bilateral e as situações unilaterais ocorrem frequentemente do lado esquerdo. Os testículos podem localizar-se na cavidade abdominal, no canal inguinal ou no tecido subcutâneo junto ao anel inguinal externo. As características das lesões macro e microscópicas do(s) testículo(s) dependem da idade do cavalo e da localização do testículo. Normalmente a observação macroscópica revela atrofia pronunciada e aumento da consistência. No exame histopatológico observa-se hipoplasia das células da linha germinativa e, em cavalos idosos, fibrose ao nível das túnicas. Os cavalos com criptorquidismo bilateral são estéreis mas, mantendo-se a produção de testosterona pelas células de Leydig, o comportamento sexual masculino não é alterado, apresentando-se, por vezes, estes animais mais agressivos que os não-criptorquídeos. Em equinos é considerado uma situação hereditária com carácter dominante, que ocorre com prevalência elevada em determinadas raças nomeadamente no American Quarter Horse (Quarto de Milha). Assim, mesmo os cavalos com criptorquidismo unilateral, que ainda apresentam de sémen, não devem ser utilizados para a reprodução devendo ser recomendada a sua castração. A castração pode ser efectuada por acesso inguinal, parainguinal, suprapúbico paramediano ou no flanco. Recentemente tem-se desenvolvido a castração por laparoscopia com o cavalo em estação ou em decúbito. O presente trabalho refere três casos de critptorquidismo esquerdo, em cavalos Quarto de Milha, castrados no Hospital Veterinário da Universidade de Évora (HVUE), com 2 1/2, 3 ½ e 6 anos de idade. Os testículos ectópicos localizavam-se, respectivamente, no anel inguinal, no tecido sub-cutâneo e na cavidade abdominal. A castração do cavalo cujo testículo se encontrava sub-cutâneo, junto ao anel inguinal externo, realizou-se por acesso inguinal, com o cavalo sedado e em estação. As outras duas cirurgias realizaram-se sob anestesia geral (por via inalatória) com os cavalos em decúbito dorsal sendo ambas iniciadas por acesso inguinal. O testículo de localização abdominal, teve que ser extraído por acesso parainguinal, dada a impossibilidade de exteriorização pelo anel inguinal. Ao exame macroscópico os testículos ectópicos encontravam-se atrofiados. O testículo com localização subcutânea apresentava forma irregular e os de localização no anel inguinal e na cavidade abdominal apresentavam, respectivamente, aumento da consistência e diminuição da mesma. Ao exame histopatológico observou-se, em todas as amostras, hipoplasia e degenerescência testicular severa sobretudo das células da linha germinativa, sendo que o testículo com localização abdominal apresentava ausência quase total destas células e também alterações degenerativas das células de Sertoli.#The cryptorchidism refers to the retention of one (unilateral) or both (bilateral) testicles and its absence in the scrotum. 10% of the cases of cryptorchidism are bilateral and the unilateral cases are frequently observed on the left side. The ectopic testicles can be located in the abdominal cavity, the inguinal ring or the sub-cutaneous tissue near the external inguinal ring. The macroscopic and microscopic lesions observed in the testicles depend both from the animal’s age as well as from the testicles’s location. More often the macroscopic examination reveals a marked atrophic testicle and a harder consistency of it. On the hystopathological exam we observe hypoplasia of the cells of the germinative pathway and in older horses a pronounced fibrosis in the area of the tunics. Horses with bilateral cryptorchidism suffer from sterility, however since the Leydig cells still produce testosterone, the mating behaviour and secondary sexual characteristics suffer no changes, horses are sometimes even more aggressive than non-cryptorchids horses. Cryptorchidism in horses is considered a hereditary situation with dominant character and has a high prevalence in some horse breeds like the American Quarter Horse. Concerning this fact, horses with this pathology, even if is unilateral and even with production of semen, should not be used as stallions and its castration should be recommended. The castration can be performed by several “traditional” approaches but presently some surgeons prefer the laparoscopic approach with the horse standing or in dorsal recumbency. The present work refers to three cases of left side cryptorchidism (unilateral) in American Quarter Horse that were castrated in the Hospital Veterinário da Universidade de Évora (HVUE). The three horses were 2 1/2, 3½ and 6 years old. The ectopic testicles were located in the inguinal ring (the 2 ½ years old horse), sub-cutaneous tissue (the 3½ years old horse) and in the abdominal cavity (the 6 years old horse). The surgery performed for the testicle located in the subcutaneous tissue was performed by inguinal approach with the animal standing and sedated. The other two surgeries were both performed with general inhalant anaesthesia with the animal in dorsal recumbency. Both surgeries were initially done by inguinal approach being the inguinal testicle well exteriorized by this approach. The intra abdominal testicle was impossible to remove through the inguinal ring so the para inguinal approach was used to exteriorize it. In the macroscopic examination all ectopic testicles were severely atrophic. The testicle removed from the subcutaneous tissue presented an irregular shape and the other testicles presented changes in consistency with higher consistency for the inguinal ring testicle and decreased consistency for the intra abdominal one. In the hystopathological examination, hypoplasia and severe testicular degenerative changes were observed in all samples especially in the germinative cells. In intra abdominal testicle these cells are almost absent and the Sertoli cells had marked degenerative changes

Hydrodynamic scaling from the dynamics of relativistic quantum field theory

Hydrodynamic behavior is a general feature of interacting systems with many degrees of freedom constrained by conservation laws. To date hydrodynamic scaling in relativistic quantum systems has been observed in many high energy settings, from cosmic ray detections to accelerators, with large particle multiplicity final states. Here we show first evidence for the emergence of hydrodynamic scaling in the dynamics of a relativistic quantum field theory. We consider a simple scalar $\lambda \phi^4$ model in 1+1 dimensions in the Hartree approximation and study the dynamics of two colliding kinks at relativistic speeds as well as the decay of a localized high energy density region. The evolution of the energy-momentum tensor determines the dynamical local equation of state and allows the measurement of the speed of sound. Hydrodynamic scaling emerges at high local energy densities.Comment: 4 pages, 4 color eps figures, uses RevTex, v2 some typos corrected and references adde

Interaction between vortices in models with two order parameters

The interaction energy and force between widely separated strings is analyzed in a field theory having applications to superconducting cosmic strings, the SO(5) model of high-temperature superconductivity, and solitons in nonlinear optics. The field theory has two order parameters, one of which is broken in the vacuum (giving rise to strings), the other of which is unbroken in the vacuum but which could nonetheless be broken in the core of the string. If this does occur, there is an effect on the energetics of widely separated strings. This effect is important if the length scale of this second order parameter is longer than that of the other fields in the problem.Comment: 11 pages, 3 figures. Minor changes in the text. Accepted for publication in Phys. Rev.