BACKGROUND: Physical activity in old age probably protects against hip fracture. However, very little is known about the impact of occupation during working life, in terms of its physical activity level and the socio-economic status (SES) it indicates, on the risk of hip fracture in later life. METHOD: A population-based case-control study was conducted on 416 subjects to investigate relationships between risk of hip fracture and occupational physical activity and occupation-related SES. Occupational physical activity was coded according to the proportion of the working day at ages 20 and 50 years that the subjects were likely to have spent sitting. The Australian Classification of Standard Occupations (ASCO) was used as the basis for the coding of SES, indicated by job titles. RESULTS: Compared with those in the intermediate category, women with a sedentary job at age 50 years (odds ratio (OR) 7.2, 95 per cent confidence interval (CI) 1.2-41.9) or a mainly weight-bearing job (OR 5.1, 95 per cent CI 1.1-23.2) had an increased risk of hip fracture. A decreasing hip fracture risk with increasing SES of the longest held job was also observed. CONCLUSION: The finding of a J-shaped relationship in women between occupational physical activity and risk of hip fracture supports the need for research into the most effective types of exercise for maintenance of bone strength. Furthermore, the protective effect of SES demonstrated in this study still need to be corroborated in other studies before establishing evidence of a causal relationship. 相似文献
This paper will review and generalize the work of Gearing, Swart and Var dealing with the development of a mathematical model to aid the government of Turkey in determining the “best” allocation of the capital budget for tourism among a large group of competing proposals. One of the more unique aspects of this work was the development of a measure of benefit for particular allocation plans which allowed for subjective information to be an integral part of the investment planning model.The computational procedures developed heretofore to derive investment strategies from the model have been based on dynamic programming, integer programming or combined dynamic programming-integer programming approaches. This paper will show how various methods based on linear programming yield satisfactory answers to many questions regarding development policies. The primary advantage of these linear programming methods is that they can be implemented with standard linear programming computer packages which are generally available, and hence eliminate the high cost of developing special purpose computer codes. 相似文献
Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep. 相似文献
We present an algorithm that explicitly utilizes the wavelength dependence of tissue optical properties for diffuse optical tomography. We have previously shown that the method gives superior separation of absorption and scattering. Here the technique is described and tested in detail, and optimum wavelength sets for a broad range of chromophore combinations are discovered and analyzed. 相似文献
Technological advances in robotics increase progressively. Elder care is one of the work areas which have potential to involve robotic workforce. So, it is important to focus on interaction between humans and potential robot workers to prepare the organization for possible challenges. The current study examined the relationships between trust in robots and anthropomorphism of robots, intention to work with robots and preference of automation levels. For this purpose, 102 caregivers who work for elder care in a nursing home (aged between 19 and 40) participated in an experimental study. According to the results, anthropomorphism of robots did not make any difference in terms of trust in them. Trust in robots was significantly related to intention to work and preference of automation levels. Organizations may consider employees’ trust in robots as an important factor before adapting them to workplace area.
Summary
Polymerisation of methyl methacrylate was conducted by using alkyl lithium/dimethylsulfoxide (DMSO) system as initiator in
toluene. A special attention was focused on using some lithium polyetheralkoxides as polymerisation promoters at ambient temperatures.
Poly(methyl methacrylate) samples were characterized with Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance
Spectroscopy (1H NMR) and Differential Scanning Calorimetry (DSC). The positive effect of the μ/σ type ligands such as lithium 2-(2-methoxyethoxy)ethoxide
(LiOEEM), 2-(methoxy)ethoxide (LiOEM) on controlling the living character, molecular weight, stereo regularity and the yield
of the produced polymers was demonstrated. It has been found that this approach provided high polymerisation yields and low
polydispersity but low initiator efficiency.
Received: 9 April 2002 / Revised version: 10 May 2002 / Accepted: 15 June 2002 相似文献
The effective thermophysical and optical properties of high density polyethylene (HDPE) filled with 50???m and 5???m particle sizes of expanded graphite (EG50, EG5) are characterized. The methods used were front- and back-detection modulated photothermal radiometry (FD-, BD-PTR) and BD-flash IR thermography. Results were interpreted according to one-dimensional heat diffusion models. The absolute thermal diffusivity was determined at low frequency from FD- and BD-PTR spectra, while the volumetric heat capacity, the thermal effusivity, and the optical absorption coefficient were determined from broad-band FD-PTR spectra. The directly obtained diffusivity values compare well with those calculated from the heat capacity and thermal effusivity, and with BD-flash results. The errors caused by the finite absorption coefficient of diluted samples are also evaluated and corrected for. A particle-size effect with the opposite influence on thermal and optical properties has been observed. Heat transport parameters of HDPE/EG composites are significantly enhanced (factor of 3 to 4 in thermal diffusivity) at low particle charge before reaching saturation above a 0.10 particle volume fraction. These features are explained in the framework of effective medium models by strongly non-spherical EG particles. 相似文献
The characterizations of Co-Fe films electrodeposited on Ti substrates under potentiostatic conditions were investigated as a function of the Fe content in the films. The compositional analysis was carried out by energy dispersive X-ray spectroscopy. Scanning electron microscopy used to analyze the surface morphology of the films revealed that the film surface became rather smooth with the increase of the Fe contents. X-ray diffraction patterns showed that the crystal structure changed depending on the Co:Fe ratio in the films. It was observed that the crystal structure converted from the predominant face-centered-cubic to the body-centered-cubic with increasing Fe content. All films showed anisotropic magnetic resistance, but their magnitudes decrease as the Fe content increases. Magnetic data obtained from by vibrating sample magnetometer revealed that the changes observed in the saturation magnetization and coercivity values may arise from the Fe content of the films. The different magnetic and magnetotransport properties may come from the structural differences caused by the Fe content. 相似文献
Options are being actively sought in aviation to switch from petroleum-based fuels to alternative fuels, of which hydrogen is a promising candidate, despite challenges associated with its production and storage. The possibility is demonstrated in this study of using hydrogen in place of some mission fuel without making substantial aircraft modifications and while utilizing only available unused baggage space in the lower-deck cargo compartments of aircraft. The environmental impact reduction and weight increase are obtained accounting for a broad range of factors including aircraft model, seat capacity, passenger and baggage load factors, annual landing and take off cycles, container type, and costs of metal hydride and gaseous hydrogen storage units of various sizes. It is found that, while there may be a cost increase, CO2 emissions are substantially reduced, by 25,000–570,000 tonnes annually in several cases and by up to 1.1 million tonnes annually for the 10 types of aircraft considered. It is also determined that with present technology, despite the low density of hydrogen, the weight of storage systems constitutes more of a challenge than their volume in aviation. Large-body aircraft are found to have more difficulties than the narrow-body aircraft regarding storage system weight. For the most frequently used narrow- and large-body aircraft considered, the number of the available containers within the required limits of weight and volume respectively are found to be 3 and 4 for the B 737-800 aircraft and 2 and 10 for the A 340-300 aircraft. Overall, the combined usage of hydrogen and kerosene investigated here may be feasible in the future, but is a challenging option with present technology and aircraft due to various factors. 相似文献
Undoped ZnO and Mn-doped ZnO (MZO) films with 0.25, 0.50, and 0.75?mol pct were synthesized onto glass substrates by sol-gel spin-coating technique, and the effects of Mn on structural, morphologic, and optical properties were investigated. The XRD results indicate that the films have wurtzite structure with polycrystalline nature. However, the dominant peak was (002) diffraction peak for all samples; other diffraction peaks with less intensity such as (100), (101), (102), (110), (103), (112), and (004) were observed for the undoped ZnO. The lattice parameter values of MZO thin films were lower than that of the undoped ZnO. Plane stress values indicated that the films had the tensile stress. A decrease in the grain sizes was observed with the increasing Mn mole?percent. The optical transmission values were found to be 82?pct for the undoped ZnO and 80, 78, and 75?pct for the MZO with 0.25, 0.50, and 0.75?mol?pct, respectively, at the wavelength of 405?nm. The optical band gap values decreased from 3.287 to 3.270?eV, the surface roughness values increased from 58.13 to 60.67?nm, Urbach energy values increased??a 18.3-meV difference in Urbach energy was observed??and in addition, the steepness parameters decreased with increasing Mn content from 0 to 0.75?mol?pct. 相似文献