Caracterização da rigidez de misturas betuminosas em ensaios de tracção indirecta por compressão diametral de provetes cilíndricos

As misturas betuminosas utilizadas nas camadas dos pavimentos rodoviários têm comportamento mecânico do tipo visco-elástico. Na prática do dimensionamento, este comportamento é definido pelo módulo de rigidez e pelo coeficiente de Poisson que caracterizam o comportamento elástico linear, mas admitindo que estes parâmetros são dependentes da temperatura e da frequência de aplicação das cargas. A norma europeia EN 12697-26 diz respeito à caracterização da rigidez de misturas betuminosas fabricadas a quente em ensaios com carregamentos repetidos à flexão, tracção indirecta ou tracção directa uniaxial. Esta norma contempla o ensaio de tracção indirecta por compressão diametral de provetes cilíndricos. O Instituto Superior Técnico possui o equipamento NAT que tem permitido o desenvolvimento de estudos baseados nesta técnica de ensaio. O artigo apresenta as principais conclusões de alguns desses estudos relacionadas, essencialmente, com a exactidão do método de ensaio e a sua adequação para caracterizar misturas betuminosas de aplicação corrente na construção e reabilitação das estradas da rede rodoviária nacional. É descrito ainda um modelo de previsão do módulo de rigidez, validado e calibrado para os resultados experimentais obtidos

Consideration of non-linearity of soils behaviour in the numerical modelling of road pavements

O objectivo principal desta comunicação é evidenciar a importância de considerar a nãolinearidade do comportamento dos solos de fundação na modelação numérica dos pavimentos rodoviários, para fins de dimensionamento estrutural. A instrumentação e observação de dois trechos experimentais numa estrada em Lisboa permitiram analisar o comportamento dos solos com esta finalidade. Durante a construção dos aterros foram realizados ensaios de carga com placa e ensaios de carga com pneu. A análise estrutural dos solos da fundação dos pavimentos, pelo método dos elementos finitos, permitiu concluir que a utilização do modelo elástico nãolinear foi a metodologia mais adequada à modelação do comportamento observado durante os ensaios. A consideração de comportamento elástico linear, tão corrente no dimensionamento dos pavimentos, mostrou-se inadequada e com tendência para subestimar a rigidez da fundação.The main objective of this paper is to point out the importance of non linearity of soils foundation behaviour in the road pavement modelling, for structural design purposes. The monitoring of two full-scale instrumented pavements in a road in Lisbon had allowed to this objective. During the test sections constructions, plate load tests and wheel load tests were carried out. The structural analysis of soils behaviour, by the finite elements method, allowed to conclude that the best adjustment to the experimental results was performed with the non-linear elastic model. The elastic linear behaviour, so worldwide used in pavements design, has shown inadequate and with trend to under predict foundation stiffness

Fetopathy associated with exposure to angiotensin converting enzyme inhibitors

Angiotensin Converting Enzyme Inhibitors (ACEI) are commonly used antihypertensive drugs, although contraindicated during pregnancy by fetopathy association such as renal dysgenesis, oligohydramnios, hipocalvaria, pulmonary hypoplasia, intrauterine growth restriction, and neonatal anuric renal failure. The authors present a clinical report of a child that developed neonatal anuric renal failure with peritoneal dialysis support by an in uterus exposure to ACEI with very good recovery. This case and literature review states the need to avoid ACEI prescription to Young women and it's suspension as soon as possible during pregnancy

Stability maps for the 5/3 mean motion resonance between Ariel and Umbriel with inclination

The evolution of the five largest satellites of Uranus during the crossing of the 5/3 mean motion resonance between Ariel and Umbriel is strongly affected by chaotic motion. Studies with numerical integrations of the equations of motion and analysis of Poincar\'e surface sections provided helpful insights to the role of chaos on the system. However, they lack of a quantification of this chaos in the phase-space. Here, we construct stability maps using the frequency analysis method. We determine that for low energies (small eccentricity and/or inclinations), the phase-space is mainly stable. As the energy increases, the chaotic regions replace the stable motion, until only small, localized libration regions remain stable.Comment: arXiv admin note: text overlap with arXiv:2305.0879

Bovine mortality: the utility of two data sources for the provision of population-level surveillance intelligence

Introduction: The use of existing data to provide surveillance intelligence is widely advocated but often presents considerable challenges. Two data sources could be used as proxies for the mortality experienced by the Scottish cattle population: deaths recorded in the mandatory register [Cattle Tracing System (CTS)] and fallen stock collections by the National Fallen Stock Company (NSFCo) with a nationwide voluntary membership.Methods: Data for the period 2011–2016 were described and compared to establish their strengths and limitations. Similarities and differences in their temporal, seasonal and spatial patterns were examined overall, at postcode area level and for different age groups. Temporal aberration detection algorithms (TADA) were fitted.Results: Broadly, similar patterns were observed in the two datasets; however, there were some notable differences. The observed seasonal, annual and spatial patterns match expectations, given knowledge of Scottish cattle production systems. The registry data provide more comprehensive coverage of all areas of Scotland, while collections data provide a more comprehensive measure of the mortality experienced in 0–1-month-old calves.Discussion: Consequently, estimates of early calf mortality and their impact on the livestock sector made using CTS, or successor registers, will be under-estimates. This may apply to other registry-based systems. Fitted TADA detected points of deviations from expected norms some of which coincided in the two datasets; one with a known external event that caused increased mortality. We have demonstrated that both data sources do have the potential to be utilized to provide measures of mortality in the Scottish cattle population that could inform surveillance activities. While neither is perfect, they are complementary. Each has strengths and weaknesses, so ideally, a system where they are analyzed and interpreted in parallel would optimize the information obtained for surveillance purposes for epidemiologists, risk managers, animal health policy-makers and the wider livestock industry sector. This study provides a foundation on which to build an operational system. Further development will require improvements in the timeliness of data availability and further investment of resources

Management and biosecurity practices by small to medium egg producers in Scotland

1. Information about procedures and biosecurity practices used by small and medium egg producers (SMEPs) is scarce. Anecdotal evidence suggests that biosecurity in such enterprises may be poor, as personnel and equipment move freely between sites and this may be compounded by personnel working on commercial units who keep their own poultry. 2. To fill this knowledge gap, a questionnaire was designed and implemented targeting SMEPs in Scotland. Small enterprises were defined as egg producers that have ≥50 laying hens but &lt;350 laying hens; while medium enterprises were defined as egg producers that have ≥350 laying hens but ≤32 000 laying hens. The questionnaire consisted of a total of 56 questions divided into multiple sections, covering the characteristics of the primary keeper, location of the enterprise and size of the flocks, husbandry, marketing of products and health/biosecurity. 3. The questionnaire was posted to 375 holdings at the beginning of March 2017 and the survey remained open until the end of May 2017. In total 90 questionnaires were received by the cut-off date of which 76 questionnaires were from SMEPs. Forty were small enterprises and 36 were medium enterprises. For three questionnaires, it was not possible to identify the enterprise type. 4. Differences were observed between SMEPs in terms of reported biosecurity and management practices, with medium enterprises reporting the adoption of more biosecurity measures than small enterprises. Furthermore, SMEPs behave differently from backyard poultry keepers and large commercial companies in terms of disease risk. 5. In conclusion, it is important to ensure that SMEPs are considered in contingency plans and disease control programmes and that engagement with them is promoted so that the uptake of relevant information, such as awareness of disease control programmes, is optimised.</p

Incomplete Shone’s complex: adult age diagnosis

A 25-year-old male with previous history of heart surgery was referred for a control echocardiogram. He had been operated when he was 5 years old for reparation of aortic coarctation and the excision of a subaortic membrane, and was then lost to follow-up. No other changes were detected previously or during surgery. The patient was clinically stable without medication and the physical exam was unremarkable. The echocardiogram showed normal left ventricular function, but bicuspid aortic valve (figure 1 A), conditioning mild aortic stenosis, and a parachute mitral valve (figure 1 B, C) with single papillary muscle (figure 1 D, E – arrow) were present, with slight increase in transmitral velocity and mild regurgitation. No residual coarctation was present. Shone’s complex is a rare congenital heart disease consisting of several levels of left-sided obstructive lesions including supravalvar mitral ring, parachute mitral valve subaortic stenosis and coarctation of aorta, being classified as complete (if all levels are present) or incomplete (if only 2 or 3 lesions are present). Our patient had a previous surgical intervention and no correction was made for two undiagnosed lesions. Furthermore, the main critical problem associated with this condition appears to be mitral valve obstruction which was not significant in our patient. A conservative approach was decided and at 3-year follow-up no events occurred. This case highlights the importance of exhaustive preoperative echocardiographic evaluation and reminds us that, in the presence of two-levels of left-side cavities obstruction, other possible related anatomical lesions must be excluded.info:eu-repo/semantics/publishedVersio

Interrupted aortic arch in a 58-year-old patient

A 58-year-old male patient was evaluated in the cardiology outpatient setting after an episode of hypertension and atrial fibrillation. He was also an ex-moker.Echocardiogram revealed slight left ventricular dilation with diastolic dysfunction and a systolic function in the lower normality level, as well as a rheumatic valvar disease with moderate mitral stenosis and slight aortic valve involvement, atrial enlargement and pulmonary hypertension. After an episode of acute pulmonar oedema the patient was referred for coronary catheterization. A right femoral approach was attempted and progression of the guidewire was not possible due to na interrupted aortic arch (IAA) (figure 1A), that was confirmed by right radial approach (figure 1B). The coronary arteries had no ignificant stenosis but the circumflex artery had an anomalous origin. A CT-scan confirmed an interrupted aortic arch (IAA) in the descending aorta, 27 mm below the left subclavian artery, and a short, 15-mm occluded segment Interrupted aortic arch in a 58-year-old patientcharacterized, originating from the right coronary Valsalva sinus and separated from the right coronary artery (figure 1D, arrow; figure 1F). The patient was submitted to cardiac correction surgery with the implantation of an intrapericardial Dacron conduit connecting both aortic ends. The periprocedural period was uneventful and at 1-year follow-up the patient was clinically stable with no cardiac complications. This IAA was an incidental finding, and it may have arisen from progression of an undiagnosed coarctation of the aorta while the absence of the ductus arteriosus was probably due to a progressive occlusion.info:eu-repo/semantics/publishedVersio

An Approach to Predict Shear Modulus of Soils in the Range of 10\u3csup\u3e-6\u3c/sup\u3e to 10\u3csup\u3e-2\u3c/sup\u3e Strain Levels

This paper presents the results of several resonant column tests carried out in a large variety of soils, including lateritic and saprolitic tropical soils. The data analysed are restricted to the strain dependence of shear modulus in the range of 10-6 to 10-2. Despite the different isotropic consolidated stresses, degrees of saturation and overconsolidation ratios applied for the different types of soil, all the test results fit very well in a previous proposed normalised curve of G/G0 as a function of γ/γ0.7, where γ0.7 is the shear strain corresponding to a value of G≈0.7 x G0. The hyperbolic stress-strain equation can conveniently describe this fitting. Simple practical relationships are also proposed for tropical soils to the prediction of G0 and γ0.7 allowing with the normalised curve to estimate shear modulus in the strain range relevant to the service state of many civil engineering structures