171 resultados para Traction of Force


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This study aimed to evaluate the force degradation of synthetic elastics over time using dynamic biomechanical tests in order to find clinical parameters of what size of elastic and frequency of exchange should be used in orthodontic therapy. It was used 240 elastics of Dental Morelli, sizes 1/8", 3/16", 1/4 "and 5/16", medium force, divided in four groups. In each group was measured forces at different times, from immediate to 72 hours after immersion in water at 37°C and incubated stretched to 600% of its initial inner diameter. Tensile tests were performed on a universal testing machine EMIC DL2000 submerged in distilled water maintained at 37°C. Data were analyzed using SPSS version 16.0, by the Analysis of Variance (One-Way) with Tukey´s post test. There was a greater increase in pattern of force decay of immediate measurement until 24 hours in all sizes of synthetic elastics, from which it was observed a decrease in force progressively smaller, with the exception of 5/16´´ elastic with a maximum force decay occurred at 12h. It was concluded that: the elastic synthetic Dental Morelli suffered significant force degradation over time, with reduction of approximately 70% of the initial force during 24 hours of stretching, followed by a progressively smaller decrease; the amount of stretch for a ideal force in intermaxillary therapies depends on the distance between the points of attachment of elastic, being necessary to consult the tables to choose the size, force and frequency of replacement.

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Pós-graduação em Engenharia Elétrica - FEIS

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Pós-graduação em Psicologia - FCLAS

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Pós-graduação em Engenharia Elétrica - FEIS

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The tractors are the main potency source, for the traction of tillage equipments and their use are increasing more and more in Brazilian agriculture. In spite of the great technological progress the increase of the number of agricultural tractors brought positive aspects and some negative, among these last ones it stands out the appearance of a new source of work accidents, which importance is given by the physical damages caused to the operator. Therefore the objective of this work was to project and develop an inclinometer, which indicates the inclination of the land, as safety sensor for agricultural tractors to avoid lateral hollovers, through a resonant sign, for the operator and the machine preservation. The built and evaluated inclinometer showed to be efficient for inclination indication of different areas during field operations with agricultural tractors, small angle oscillation and enough answer time to help operators to take decisions in imminence situation of lateral machine hollovers.

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The central thesis that we aim to survey in this paper is that the present South-American political scene has required of the American imperialism a strategical redesign, in the sense of the neutralization, weakening and, if it is possible, destruction of regional political experiences/tendencies not aligned to its foreign politics. Under the mask of the defense of democracy and beneath the argument that Latin American "market oriented politics" are at stake, due to questions that goes back from the "delin-quency" —in Mexico—, the global terrorism, the organized international crime up to the worldwide drug traffic, the global strategy of American imperialism then sets up the definition of a new doctrine of preventive war that justifies the utilization of hard power against any country, in the name of its own defense. At the heart of the question what —actually— is in the agenda is the defense (and reproduction) of the benefits of its multinationals corporations and financial capital, by means of the international sub-traction of profitable assets, such as financial, energetic, communicational and natural resources, in addition to the domination of local markets, beyond facilitating capital flee amongst others.

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The aim of this work was to examine both the influence of anatomical and technical aspects on fertility rate of sheep based on the performance of transcervical artificial insemination (TCAI). Transcervical artificial insemination was performed with traction of the cervix in 122 ewes using frozen semen from 11 rams, both Santa Ines breed. The data collected were: type of external cervical opening (CO) (P - papilla; FL - flap; DB - duckbill, S - spiral; RO - rosette), duration of cervical manipulation (2-3, 4-5 and 6-7 minutes), degree of difficulty in cervical transposition (low, moderate, high) and presumed semen deposition site (SC - superficial cervical; DC - deep cervical; IU - intrauterine). The influence of these variables on pregnancy rate was evaluated. Cervical opening type and duration of cervical manipulation had no influence (p>0.05) on fertility. The degree of difficulty in cervical manipulation influenced (p<0.05) pregnancy rate, since insemination classified as low grade had 52% of pregnancy, while those classified as high recorded only 20%. The presumed site of semen deposition influenced significantly (p<0.05) fertility. Pregnancy rates of deposition at each site were: UI – 45.8%, DC – 25.7%; SC – 15.4%. As expected, deeper depositions resulted in higher fertility. In conclusion, the performance of TCAI did not depend on the anatomical classification of external cervical opening of ewe and the duration of cervical manipulation within the range tested (2-7 minutes). The TCAI may have higher fertility rates if difficulties in the application were reduced and the semen deposition was deeper.

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The present study describes a technique to obtain consecutive luteal samples by colpotomy. The animals received an epidural anesthesia and local anesthesia (vaginal vault) and after ten minutes the vaginal vault was incised with a scalpel blade and tissue was dissected to provide access to the pelvic cavity and to retract the ovary into the vagina. Then, a luteal biopsy was performed with a Yomann biopsy nipper. Signs indicative of pain and stress during the vaginal vault incision, traction of ovary or luteal biopsy were observed only in two collections. However, these signs were observed in ten collections during dissection of the vaginal wall and peritoneum. The occurrence of ataxia was observed in 26 collections and it was usually related to a longer duration of the procedure. Ataxia could be divided in light (15/26), moderate (6/26) and severe (5/26). The occurrence of ovarian adhesions ipsilateral to the incision was evaluated only in the initial four collections. Adhesions were present in 16 collections. The protocol described above provided a safe and efficient method to acquire luteal samples. The low incidence of adhesions allows the consecutive use of females without any interference in subsequent ovulations and collections.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Soil erosion data in El Salvador Republic are scarce and there is no rainfall erosivity map for this region. Considering that rainfall erosivity is an important guide for planning soil erosion control practices, a spatial assessment of indices for characterizing the erosive force of rainfall in El Salvador Republic was carried out. Using pluviometric records from 25 weather stations, we applied two methods: erosivity index equation and the Fournier index. In all study area, the rainiest period is from May to November. Annual values of erosivity index ranged from 7,196 to 17,856 MJ mm ha(-1) h(-1) year(-1) and the Fournier index ranged from 52.9 to 110.0 mm. The erosivity map showed that the study area can be broadly divided into three major erosion risk zones, and the Fournier index map was divided into four zones. Both methods revealed that the erosive force is severe in all study area and presented significant spatial correlation with each other. The erosive force in the country is concentrated mainly from May to November.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)