914 resultados para Movement of the trunk
Resumo:
Tourists to the archaeological site of Tiwanaku are presented with ancient calendars, of which the Gateway of the Sun is the most important, famous, and beautiful. Arthur Posnansky and other early 20th-century archaeologists claimed that its inscriptions constituted a written calendar. These claims were intimately connected to narratives of Tiwanaku as a central source of knowledge in both pre-Columbian times and the contemporary world. Posnansky presented his interpretation of Tiwanaku’s calendars as a response to the debates of the World Calendar Movement, which in the 1930s was attempting to rationalize the Gregorian calendar. In the Gateway, Posnansky found a uniquely Bolivian response to the international, North Atlantic-dominated scientific community’s search for a rational way to keep time in the world economy. Bolivian intellectuals merged their interest in the indigenous past with their concerns about the role of the modernist Bolivian state in the global system.
Resumo:
PURPOSE: To determine the radiation dose delivered to organs during standard computed tomographic (CT) examination of the trunk. MATERIALS AND METHODS: In vivo locations and sizes of specific body organs were determined from CT images of patients who underwent examinations. The corresponding CT investigations were then simulated on an anthropomorphic phantom. The resulting doses were measured at 70 different sites inside the phantom by using thermoluminescent dosimeters. On the basis of measurements of free-in-air air kerma at the rotation axis of the CT gantry, conversion factors were calculated so that measurements could be used with different models of CT equipment. RESULTS: Starting from the dose values recorded, the mean organ doses were determined for 21 organs. The skin received 22-36 mGy; the lungs, less than 1-18 mGy; the kidneys, 7-24 mGy; and the ovaries, less than 1-19 mGy, depending on the type of CT examination performed. CONCLUSION: These values are high compared with other x-ray examinations and should be minimized as much as possible. The number of tomographic sections obtained should be kept as low as possible according to diagnostic need.
Resumo:
The small all-β protein tendamistat folds and unfolds with two-state kinetics. We determined the volume changes associated with the folding process by performing kinetic and equilibrium measurements at variable pressure between 0.1 and 100 MPa (1 to 1,000 bar). GdmCl-induced equilibrium unfolding transitions reveal that the volume of the native state is increased by 41.4 ± 2.0 cm3/mol relative to the unfolded state. This value is virtually independent of denaturant concentration. The use of a high-pressure stopped-flow instrument enabled us to measure the activation volumes for the refolding (ΔVf0‡) and unfolding reaction (ΔVu0‡) over a broad range of GdmCl concentrations. The volume of the transition state is 60% native-like (ΔVf0‡ = 25.0 ± 1.2 cm3/mol) in the absence of denaturant, indicating partial solvent accessibility of the core residues. The volume of the transition state increases linearly with denaturant concentration and exceeds the volume of the native state above 6 M GdmCl. This result argues for a largely desolvated transition state with packing deficiencies at high denaturant concentrations and shows that the structure of the transition state depends strongly on the experimental conditions.
Resumo:
Xeroderma pigmentosum type G (XPG) is a human genetic disease exhibiting extreme sensitivity to sunlight. XPG patients are defective XPG endonuclease, which is an enzyme essential for DNA repair of the major kinds of solar ultraviolet (UV)-induced DNA damages. Here we describe a novel dynamics of this protein within the cell nucleus after UV irradiation of human cells. Using confocal microscopy, we have localized the immunofluorescent, antigenic signal of XPG protein to foci throughout the cell nucleus. Our biochemical studies also established that XPG protein forms a tight association with nuclear structure(s). In human skin fibroblast cells, the number of XPG foci decreased within 2 h after UV irradiation, whereas total nuclear XPG fluorescence intensity remained constant, suggesting redistribution of XPG from a limited number of nuclear foci to the nucleus overall. Within 8 h after UV, most XPG antigenic signal was found as foci. Using beta-galactosidase-XPG fusion constructs (beta-gal-XPG) transfected into HeLa cells, we have identified a single region of XPG that is evidently responsible both for foci formation and for the UV dynamic response. The fusion protein carrying the C terminus of XPG (amino acids 1146-1185) localized beta-gal specific antigenic signal to foci and to the nucleolus regions. After UV irradiation, antigenic beta-gal translocated reversibly from the subnuclear structures to the whole nucleus with kinetics very similar to the movements of XPG protein. These findings lead us to propose a model in which distribution of XPG protein may regulate the rate of DNA repair within transcriptionally active and inactive compartments of the cell nucleus.
Resumo:
Includes bibliographical references.
Resumo:
Mode of access: Internet.
Resumo:
Mode of access: Internet.
Resumo:
"United States Department of Agriculture in cooperation with the Texas Agricultural Experiment Station".
Resumo:
"To be presented before the American Electric Railway Transportation and Traffic Association convention held at San Francisco, Cal., June 23 to 26, 1930."
Resumo:
Mode of access: Internet.
Resumo:
During voluntary arm movements, the medial back muscles are differentially active. It is not known whether differential activity also occurs when the trunk is perturbed unpredictably, when the earliest responses are initiated by short-latency spinal mechanisms rather than voluntary commands. To assess this, in unpredictable and self-initiated conditions, a weight was dropped into a bucket that was held by the standing subject (n = 7). EMG activity was recorded from the deep (Deep MF), superficial (Sup MF) and lateral (Lat MF) lumbar multifidus, the thoracic erector spinae (ES) and the biceps brachii. With unpredictable perturbations, EMG activity was first noted in the biceps brachii, then the thoracic ES, followed synchronously in the components of the multifidus. During self-initiated perturbations, background EMG in the Deep MF increased two- to threefold, and the latency of the loading response decreased in six out of the seven subjects. In Sup MF and Lat MF, this increase in background EMG was not observed, and the latency of the loading response was increased. Short-latency reflex mechanisms do not cause differential action of the medial back muscles when the trunk is loaded. However, during voluntary tasks the central nervous system exerts a 'tuned response', which involves discrete activity in the deep and superficial components of the medial lumbar muscles in a way that varies according to the biomechanical action of the muscle component.
Resumo:
Despite the importance of the deep intrinsic spinal muscles for trunk control, few studies have investigated their activity during human locomotion or how this may change with speed and mode of locomotion. Furthermore, it has not been determined whether the postural and respiratory functions, of which these muscles take part, can be coordinated when locomotor demands are increased. EMG recordings of abdominal and paraspinal muscles were made in seven healthy subjects using fine-wire and surface electrodes. Measurements were also made of respiration and gait parameters. Recordings were made for 10s as subjects walked on a treadmill at 1 and 2 ms(-1) and ran at 2, 3, 4 and 5 ms(-1). Unlike the superficial muscles, transversus abdominis was active tonically throughout the gait cycle with all tasks, except running at speeds of 3 ms(-1) and greater. All other muscles were recruited in a phasic manner. The relative duration of these bursts of activity was influenced by speed and/or mode of locomotion. Activity of all abdominal muscles, except rectus abdominis (RA), was modulated both for respiration and locomotor-related functions but this activity was affected by the speed and mode of locomotion. This study provides evidence that the deep abdominal muscles are controlled independently of the other trunk muscles. Furthermore, the pattern of recruitment of the trunk muscles and their respiratory and postural coordination is dependent on the speed and mode of locomotion. (C) 2003 Published by Elsevier B.V.
Resumo:
Background: Although a lowered medial longitudinal arch has been cited as a causal factor in plantar fasciitis, there is little experimental evidence linking arch motion to the pathogenesis of the condition. This study investigated the sagittal movement of the arch in subjects with and without plantar fasciitis during gait. Methods: Digital fluoroscopy was used to acquire dynamic lateral radiographs from 10 subjects with unilateral plantar fasciitis and 10 matched control subjects. The arch angle and the first metatarsophalangeal joint angle were digitized and their respective maxima recorded. Sagittal movement of the arch was defined as the angular change between heel strike and the maximum arch angle observed during the stance phase of gait. The-thickness of the proximal plantar fascia was determined from sagittal sonograms of both feet. ANOVA models were used to identify differences between limbs with respect to each dependent variable. Relationships between arch movement and fascial thickness were investigated using correlations. Results: There was no significant difference in either the movement or maximum arch angle between limbs. However, subjects with plantar fasciitis were found to have a larger metatarsophalangeal joint angle than controls (P < 0.05). Whereas the symptomatic and asymptomatic plantar fascia were thicker than those of control feet (P < 0.05), significant correlations were noted between fascial thickness and peak arch and metatarsophalangeal joint angles (P < 0.05) in the symptomatic limb only. Conclusions: Neither abnormal shape nor movement of the arch are associated with chronic plantar fasciitis. However, arch mechanics may influence the severity of plantar fasciitis once the condition is present. Digital flexion, in contrast, has a protective role in what might be a bilateral disease process.