970 resultados para mechanical system


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Data on record regarding weight variation in depot-medroxyprogesterone acetate (DMPA) and levonorgestrel-releasing intrauterine system (LNG-IUS) users are controversial. To date, no studies have yet evaluated weight variation in DMPA and LNG-IUS users in up to ten years of use compared to non-hormonal contraceptive users. A retrospective study analysed weight variations in 2138 women using uninterruptedly DMPA (150 mg intramuscularly, three-monthly; n = 714), the LNG-IUS (n = 701) or a copper-intrauterine device (Cu-IUD; n = 723). At the end of the first year of use, there was a mean weight increase of 1.3 kg, 0.7 kg and 0.2 kg among the DMPA-, LNG-IUS- and Cu-IUD users, respectively, compared to weight at baseline (p < 0.0001). After ten years of use, the mean weight had risen by 6.6 kg, 4.0 and 4.9 kg among the DMPA-, LNG-IUS- and Cu-IUD users, respectively. DMPA-users had gained more weight than LNG-IUS- (p = 0.0197) and than Cu-IUD users (p = 0.0294), with the latter two groups not differing significantly from each other in this respect (p = 0.5532). Users of hormonal and non-hormonal contraceptive methods gained a significant amount of weight over the years. DMPA users gained more weight over the treatment period of up to ten years than women fitted with either a LNG-IUS or a Cu-IUD.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

To develop Y-shaped plates with different thicknesses to be used in simulated fractures of the mandibular condyle. Ten plates were developed in Y shape, containing eight holes, and 30 synthetic polyurethane mandible replicas were developed for the study. The load test was performed on an Instron Model 4411 universal testing machine, applying load in the mediolateral and anterior-posterior positions on the head of the condyle. Two-way ANOVA with Tukey testing with a 5% significance level was used. It was observed that when the load was applied in the medial-lateral plate of greater thickness (1.5 mm), it gave the highest strength, while in the anteroposterior direction, the plate with the highest resistance was of the lesser thickness (0.6 mm). A plate with a thickness of 1.5 mm was the one with the highest average value for all displacements. In the anteroposterior direction, the highest values of resistance were seen in the displacement of 15 mm. After comparing the values of the biomechanical testing found in the scientific literature, it is suggested that the use of Y plates are suitable for use in subcondylar fractures within the limitations of the study.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study was designed to evaluate the correlation between computed tomography findings and data from the physical examination and the Friedman Staging System (FSS) in patients with obstructive sleep apnea (OSA). We performed a retrospective evaluation by reviewing the medical records of 33 patients (19 male and 14 female patients) with a mean body mass index of 30.38 kg/m(2) and mean age of 49.35 years. Among these patients, 14 presented with severe OSA, 7 had moderate OSA, 7 had mild OSA, and 5 were healthy. The patients were divided into 2 groups according to the FSS: Group A comprised patients with FSS stage I or II, and group B comprised patients with FSS stage III. By use of the Fisher exact test, a positive relationship between the FSS stage and apnea-hypopnea index (P = .011) and between the FSS stage and body mass index (P = .012) was found. There was no correlation between age (P = .55) and gender (P = .53) with the FSS stage. The analysis of variance test comparing the upper airway volume between the 2 groups showed P = .018. In this sample the FSS and upper airway volume showed an inverse correlation and were useful in analyzing the mechanisms of airway collapse in patients with OSA.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Oligodendrocytes and Schwann cells are engaged in myelin production, maintenance and repairing respectively in the central nervous system (CNS) and the peripheral nervous system (PNS). Whereas oligodendrocytes act only within the CNS, Schwann cells are able to invade the CNS in order to make new myelin sheaths around demyelinated axons. Both cells have some limitations in their activities, i.e. oligodendrocytes are post-mitotic cells and Schwann cells only get into the CNS in the absence of astrocytes. Ethidium bromide (EB) is a gliotoxic chemical that when injected locally within the CNS, induce demyelination. In the EB model of demyelination, glial cells are destroyed early after intoxication and Schwann cells are free to approach the naked central axons. In normal Wistar rats, regeneration of lost myelin sheaths can be achieved as early as thirteen days after intoxication; in Wistar rats immunosuppressed with cyclophosphamide the process is delayed and in rats administered cyclosporine it may be accelerated. Aiming the enlightening of those complex processes, all events concerning the myelinating cells in an experimental model are herein presented and discussed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The thermodynamic equilibrium is a state defined by conditions which depend upon some characteristics of the system. It requires thermal, mechanical, chemical and phase equilibrium. Continuum thermodynamics, its radical restriction usually called homogeneous processes thermodynamics, as well as the classical thermodynamic science of reversible processes, each of them defines equilibrium in a differing way. But these definitions lead to the same physical contents.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Sugarcane holds an important place in the Brazilian economy. Grate part of the sugarcane harvested still accomplished largely manually. Sugarcane harvesters available in Brazil use the technology to chop the cane into 200 to 300 mm billets to allow on the go cane transferring to transport, contradicting the traditional method of whole stalk sugarcane harvesting system. In order to make whole stalk mechanical harvesting system possible, one of the barriers to be expired is the mechanical removal of the straw. The design of a mechanism that accomplishes this operation depends directly on the knowledge of the mechanical properties of the sugarcane related to its resistance to compression and the forces necessary to remove the leaves from the stalk. Compression tests were conducted using the universal testing machine. For leaves removal test by friction, a special apparatus was designed to allow the registration of the normal and traction force. The sugarcane stalk can resist up to 4.9 MPa. With a normal pressure of 0.8 MPa, which correspond to a friction force of 315 N, it is possible to remove the leaves, independent of its location in the sugarcane stalk.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In the last few years the sugar-cane mechanical harvested area has increased, especially in regions with appropriated slop. The use of this technology brings some inconveniences, such as, the increase in the percentage of extraneous matter, which causes the reduction of technological quality of the raw material, and losses in the field. Extraneous matter (trash) is composed of tops and leaves in major percentage, plus soil and roots, and eventually some metal parts. In the green cane harvest system the percentage of extraneous matter has a tendency to increase due to the great amount of vegetal matter to be processed. The increase in the blower fan speed to reduce the amount of extraneous matter can lead to an unacceptable economic level of raw material losses. The main objective of this work was, using a cane loss monitor, to evaluate and quantify the amount of visible losses of sugar cane through the primary extractor at two different fan speeds. Afterwards these losses were related to the harvester cleaning efficiency. The piezoelectric transducer shows a reasonable sensibility. The results show that the cleaning efficiency in the primary extractor (85% mean), the cane losses (between 5.68% and 2.15%) and fan speed are interrelated. The total losses and specially splinters (between 3.19% and 0.91%), showed a significant difference among the treatments.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Quality evaluation of classification was done in two fresh market tomatoes packing house, using electronically and mechanical equipments in two harvest periods, summer and winter seasons. The main goal of this work was to evaluate size and color grading conformity with the standards proposed by the Brazilian Program for Horticulture Modernization and size grading obtainded with the one established by the packer. The cultivar studied was Carmen. The results showed that there was no grade conformity with the fresh tomato quality standards proposed by the Brazilian Program for Horticulture Modernization. The grade conformity obtained when compared with the one programmed by the packer, was only for large sizes, in both equipments. The electronically equipment has presented better performance, over the mechanical, considering grading quality and fruits post-harvest quality. However, the electronically equipment must be constantly monitored to achieve efficiency and investment return. On the other side, for mechanical equipment it will be necessary to review the actual system of size grading, in order to follow the fresh tomato quality standards.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

One of the problems found in mechanical harvest of sugar cane is the lack of synchronism between the harvest machine and the infield wagon, causing crop losses as well as operational capacity. The objective of the present research was to design a system capable of helping to synchronize the sugar cane harvest machine with the wagon. The communication between tractor and harvest machine is wireless. Two ultrasound sensors coupled to the elevator and a microprocessor manage such information, generating a correct synchronization among the machines. The system was tested in laboratory and on field performing its function adequately, maintaining the two machines in synchronization, indicating and alerting the operators their relative positions. The developed system reduced the sugar cane lost in 60 kg ha-1 comparing to the harvest with the system turned off.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Losses of horticulture product in Brazil are significant and among the main causes are the use of inappropriate boxes and the absence of a cold chain. A project for boxes is proposed, based on computer simulations, optimization and experimental validation, trying to minimize the amount of wood associated with structural and ergonomic aspects and the effective area of the openings. Three box prototypes were designed and built using straight laths with different configurations and areas of openings (54% and 36%). The cooling efficiency of Tommy Atkins mango (Mangifera Indica L.) was evaluated by determining the cooling time for fruit packed in the wood models and packed in the commercially used cardboard boxes, submitted to cooling in a forced-air system, at a temperature of 6ºC and average relative humidity of 85.4±2.1%. The Finite Element Method was applied, for the dimensioning and structural optimization of the model with the best behavior in relation to cooling. All wooden boxes with fruit underwent vibration testing for two hours (20 Hz). There was no significant difference in average cooling time in the wooden boxes (36.08±1.44 min); however, the difference was significant in comparison to the cardboard boxes (82.63±29.64 min). In the model chosen for structural optimization (36% effective area of openings and two side laths), the reduction in total volume of material was 60% and 83% in the cross section of the columns. There was no indication of mechanical damage in the fruit after undergoing the vibration test. Computer simulations and structural study may be used as a support tool for developing projects for boxes, with geometric, ergonomic and thermal criteria.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Universidade Estadual de Campinas . Faculdade de Educação Física

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Universidade Estadual de Campinas . Faculdade de Educação Física

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Universidade Estadual de Campinas. Faculdade de Educação Física

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Universidade Estadual de Campinas . Faculdade de Educação Física