15 research outputs found
On the modelling and testing of a laboratory scale Foucault pendulum as a precursor for the design of a high performance measurement instrument
An integrated study is presented on the dynamic modelling and experimental testing of a mid-length Foucault pendulum with the aim of confirming insights from the literature on the reliable operation of this device and setting markers for future research in which the pendulum may be used for the measurement of relativistic effects due to terrestrial gravity. A tractable nonlinear mathematical model is derived for the dynamics of a practical laboratory Foucault pendulum and its performance with and without parametric excitation, and with coupling to long-axis torsion is investigated numerically for different geographical locations. An experimental pendulum is also tested, with and without parametric excitation, and it is shown that the model closely predicts the general precessional performance of the pendulum, for the case of applied parametric excitation of the length, when responding to the Newtonian rotation of the Earth. Many of the principal inherent performance limitations of Foucault pendulums from the literature have been confirmed and a general prescription for design is evolved, placing the beneficial effect of principal parametric resonance of this inherently nonlinear system in a central mitigating position, along with other assistive means of response moderation such as excitational phase control through electromagnetic pushing, enclosure, and the minimization of seismic and EMC noise. It is also shown, through a supporting analysis and calculation, that although the terrestrial measurement of the Lense-Thirring (LT) precession by means of a Foucault pendulum is certainly still within the realms of possibility, there remains a very challenging increase in resolution capability required, in the order of 2 × 10 9 to be sure of reliable detection, notwithstanding the removal of extraneous motions and interferences. This study sets the scene for a further investigation in the very near future in which these challenges are to be met, so that a new assault can be made on the terrestrial measurement of LT precession
EVALUATION OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION OUTCOMES
The anterior cruciate ligament (ACL) is the main stabilizer of the knee. Its injury has been increasing, especially in adolescents and young adults, active and sportsmen. Reconstruction surgery is recommended for the return to pre-injury activity, although with some aspects still debatable to obtain the best results.O ligamento cruzado anterior (LCA) é o principal estabilizador do joelho. Sua lesão vem aumentando, principalmente em adolescentes e adultos jovens, ativos e desportistas. A cirurgia de reconstrução é recomendada para o retomo a atividade pré-lesão, embora com alguns aspectos ainda discutíveis para se obter os melhores resultados
Filter Papers to Collect Blood Samples from Dogs: An Easier Way to Monitor the Mass Vaccination Campaigns against Rabies?
Rabies is a deadly viral disease present mainly in low-income countries of Africa and Asia. Dogs are the main reservoir and the source of human deaths. Mass vaccination campaigns of dogs are pivotal to achieve rabies elimination. The monitoring of the immune response of the dog population is necessary to evaluate the effectiveness of these campaigns, taking into account field conditions. This study explores the feasibility and the performance of a new tool using filter papers (FPs) to collect blood samples associated with an Enzyme-Linked ImmunoSorbent Assay (ELISA) titration of rabies antibodies in dogs. A total of 216 eluates from FP samples were collected from 111 dogs kept in experimental facilities in France and 29 dogs from the field in Tunisia. Sera were also analyzed using both the Fluorescence Antibody Virus Neutralization test (FAVNt) and ELISA. A high specificity (98.0%) was obtained by testing FP blood eluates from 51 unvaccinated dogs, with the results compared with those of FAVNt and ELISA on serum samples. The coefficients of concordance between FP eluates and tested sera were 88.9% for FAVNt and 88.0% for ELISA. Blood filter papers coupled with the titration of rabies antibodies by ELISA provide a reliable, simple, and effective solution to overcome the issues of the logistics and transport of samples, especially in low-income countries
Evaluation of the immune response of dogs after a mass vaccination campaign against rabies in Tunisia
Abstract Background Rabies (RABV) is an enzootic disease in Tunisia, with dogs being the primary reservoir. Vaccinating dogs is the key to eradicate rabies. Regional Veterinary Services conduct nationwide immunisation campaigns on an annual basis. Evaluation of the immune response is still important to make sure that the vaccination is effective in the conditions of the Tunisian field. In this paper, the FAVN technique was used to test rabies antibody dynamics in dogs from three distinct Tunisian areas observed for one year following a mass vaccination campaign. Results On day 30 after vaccination, 75% of all dogs vaccinated during the campaign were sero-positive (titres greater than or equal to 0.5 transformed IU/ml). On day 180, 48% of all dogs were sero-positive. Only 25.6% of primary-vaccinated dogs remained sero-positive on day 180 and 7% on day 365, whereas 91% of previously sero-positive dogs remained sero-positive on day 365. Conclusions Although a single rabies vaccine is successful at stimulating an immunological response, it is recommended that primary-vaccinated dogs have a second booster between one and three months after the initial vaccination to maintain seropositivity. To achieve the rabies eradication objective, all dogs should receive an annual booster to maintain effective immunological protection
The Clinical Features and Outcomes of Renal Amyloidosis in Tunisia
Systemic amyloidosis is a rare disease characterized by clinical polymorphism. Indeed, the kidney is the most common organ involved and represents a real turning point in the disease. We aimed to determine the clinicopathological prognostic factors of renal amyloidosis (RA). We conducted a retrospective study including 40 cases with biopsy-proven RA collected in our department over a period of 10 years. Biochemical, demographic, and clinicopathological findings at diagnosis, as well as the follow-up data, were evaluated for each patient. The prevalence of amyloidosis was 2.7 per 100 nontransplant renal biopsies. The mean age at presentation was 55.5 ± 15.6 years with a male-to-female ratio of 1.85. The diagnosis of RA was confirmed by a renal biopsy in 85% of cases. Amyloid A (AA) amyloidosis was the most common type of amyloidosis (65%), and chronic infections ranked first in the panel of etiologies (41%). Amyloid light chain amyloidosis was mainly associated with multiple myeloma (57%). The median patient survival was 59 months versus 12 months for kidney survival. Age and extrarenal localization were independent predictors of mortality, whereas renal failure at presentation significantly influenced renal survival. The results of our study emphasize the rarity but also the severity of RA. AA amyloidosis was the most common type identified, which was mainly caused by chronic infections. Prevention remains the best solution until we can achieve therapeutic advances in inflammatory diseases
Molecular Epidemiology of Rabies in Wild Canidae in Tunisia
Rabies is a viral zoonosis that is transmissible to humans via domestic and wild animals. There are two epidemiological cycles for rabies, the urban and the sylvatic cycles. In an attempt to study the epidemiological role of wild canidae in rabies transmission, the present study aimed to analyze the genetic characteristics of virus isolates and confirm prior suggestions that rabies is maintained through a dog reservoir in Tunisia. Virus strains isolated from wild canidae were subject to viral sequencing, and Bayesian phylogenetic analysis was performed using Beast2 software. Essentially, the virus strains isolated from wild canidae belonged to the Africa-1 clade, which clearly diverges from fox-related strains. Our study also demonstrated that genetic characteristics of the virus isolates were not as distinct as could be expected if a wild reservoir had already existed. On the contrary, the geographic landscape is responsible for the genetic diversity of the virus. The landscape itself could have also acted as a natural barrier to the spread of the virus