Neck,shoulder and low back pain in secondary schoolchildren in relation to schoolbag carriage: Should the recommended weight limits be gender-specific?

The occurrence of neck, shoulder and low back complaints in relation to schoolbag carriage and other potential risk factors were investigated in a cross-sectional study of 586 Iranian schoolchildren aged 12–14 years. The average load carried by schoolchildren was 2.8 kg. Neck, shoulder and low back complaints during the preceding month were reported by 35.3%, 26.1% and 33% of the students, respectively. Gender was an independent factor predicting musculoskeletal symptoms in schoolchildren. Girls were more likely than boys to suffer from neck, shoulder and low back complaints, although there was no significant difference between genders in terms of schoolbag carriage variables. The findings suggest that the recommended weight limit for schoolbag carriage may need to differ between boys and girls. The associations between schoolbag variables and reported symptoms are also discussed. The results provide evidence that the current weight limit should consider a broader combination of factors that influence the use of schoolbags.     

Ammonia borane confined by poly(methyl methacrylate)/multiwall carbon nanotube nanofiber composite,as a polymeric hydrogen storage material

In this work, poly(methyl methacrylate)/ammonia borane/multiwall carbon nanotube (PMMA/AB/MWCNT) nanofiber composites have been fabricated and the synergetic nanoconfinement effect of nanofiber and CNT components on dehydrogenation temperature and liberating unwanted byproducts of AB (NH₃BH₃) have been studied. The results of dehydrogenation of PMMA/AB and PMMA/AB/MWCNT samples show 112 and 85 °C exothermic reaction temperatures, which are dramatically lower than pure AB (120 °C). Furthermore, by capture and interaction of AB molecules in the MWCNT and PMMA nanofiber structures, the enthalpy of exothermic decomposition decreases from ?21.00 to ?1.83 kJ mol^?1 H₂, suggesting that this type of AB nanofiber composite can provide a convenient reversible hydrogen storage material. The utilization of MWCNT as carbon catalyst and confining of AB result in a decrease of ammonia borane weight loss from 60.00 to 2.88 wt% which in turn can vigorously decline the emission of byproduct impurities. The synthesis process of PMMA/AB/MWCNT nanofiber composites causes the crystal structure of AB particles changed to the amorphous structure which has been clearly confirmed by X-ray diffraction analyses. The strategy of combining nanofiber structure and MWCNT as carbon catalyst with AB particles can be presented as a practicable solution to reach lower operational temperature and to decline undesirable volatile products.     

Semi-automatic measurement of rigid gas-permeable contact lens movement in keratoconus patients using blinking images

Purpose

To introduce a method for estimation of the rigid gas-permeable contact lens (RGP) movement.

Effect of Low Concentration Sn Doping on Optical Properties of CdS Films Grown by CBD Technique

Thin and transparent films of doped cadmium sulfide (CdS) were obtained on commercial glass substrates by Chemical Bath Deposition (CBD) technique. The films were doped with low concentration of Sn, and annealed in air at 300 °C for 45 min. The morphological characterization of the films with different amounts of dopant was made using SEM and EDAX analysis. Optical properties of the films were evaluated by measuring transmittance using the UV-vis spectrophotometer. A comparison of the results revealed that lower concentration of Sn doping improves transmittance of CdS films and makes them suitable for application as window layer of CdTe/CIGS solar cells.     

Beam shaping design for coupling high power diode laser stack to fiber

A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible.     

Performance Evaluation of Deteriorating Highway Bridges Located in High Seismic Areas

This paper studies the life-cycle performance and cost of reinforced concrete highway bridges subjected to earthquake ground motions while they are continuously exposed to the attack of chloride ions. The penetration of chloride ions into the concrete is simulated through a finite difference approach that takes into account all the parameters that can affect the corrosion process. From simulation results, the corrosion initiation time is predicted, and the extent of structural degradation is calculated over the entire life of the bridge. A group of detailed bridge models with various structural attributes are developed to evaluate the changes in the structural capacity and seismic response of corroded bridges. For the purpose of the probabilistic seismic risk assessment of bridges, the seismic fragility curves are generated and updated at regular time intervals. The time-dependent fragility parameters are employed to investigate the life-cycle cost of bridges by introducing a performance index that combines the effects of probable seismic events and chloride-induced corrosion. The proposed approach provides a multihazard framework that leads to more realistic performance and cost estimates.     

Dietary assessment of hemodialysis patients in Tehran, Iran

Inadequate dietary intakes are a major determinant of malnutrition in hemodialysis (HD) patients. Considering the lack of information available on dietary intakes of HD patients in Iran, the present study was designed to assess the dietary intakes of HD patients in Tehran, Iran. For this cross‐sectional study, from among adult HD patients of 50 Tehran hemodialysis centers, 291 patients were randomly selected. Dietary intakes of these patients were assessed using a 4‐day dietary recall. In addition, 4 mL of blood was obtained from each patient before dialysis to measure serum urea, creatinine, albumin, phosphorus, calcium, potassium, and high sensitive C‐reactive protein levels. Dietary intakes of energy, protein and fiber were lower than recommended intakes in 88%, 84.5%, and 99% of HD patients, respectively. There were significant associations between dietary energy intake with the patient's age (p < 0.05), and HD vintage (P < 0.001). In addition, a significant association was found between dietary protein intake and sex (P < 0.05). Intakes of vitamins B1, B2, B3, B6, B12, C, E, folic acid, and of the minerals calcium and zinc (from both the diet and supplements) were lower than recommended intakes in 13.5%, 41.5%, 19%, 66%, 61%, 78%, 77%, 24%, 34%, and 98.5% of HD patients, respectively. Inadequate intakes of energy and various nutrients are prevalent in HD patients in Tehran, Iran, which may contribute to increased morbidity and mortality in these patients. Therefore, nutrition counseling and the administration of vitamin and mineral supplements are necessary in Iranian HD patients.     

Electrochemical detection and discrimination of single copy gene target DNA in non-amplified genomic DNA

A sensitive, fast and inexpensive method for direct electrochemical detection of target DNA sequences in non-amplified genomic DNA samples is described. Hybridization detection relies on the alteration in guanine oxidation signal following hybridization of the probe with complementary genomic DNA. Initially, the method was tested to detect target DNA on low cycle number PCR amplicons. Having obtained promising detection results from only 5 cycles product, the feasibility of target sequence detection in extracted genomic DNA without PCR amplification, but with the vortex mediated fragmentation of the large genomic DNA into small pieces was examined. Experimental variables affecting the efficiency of sensor were investigated. Detection experiments with various non-complementary genomic DNAs as well as a proper probe, non-specific with respect to all genomic samples confirmed the excellent selectivity of the approach. The sensitivity of the method for analyzing the vortex mediated fragmentized genomic DNA samples is estimated to be approximately of 0.58 ng/μl.     

A new combined method based on curvelet transform and morphological operators for automatic detection of foveal avascular zone

In order to achieve early detection of diabetic retinopathy (DR) for the sake of preventing from blindness, regular screening using retinal photography is necessary. Abnormalities of DR do not have uniform distribution over the retina. Certain types of abnormalities usually occur in specific areas on the retina. The distance between lesions, such as micro-aneurysms, and the foveal avascular zone (FAZ) is a useful feature for later analysis and grading of DR. In this paper, a new fully automatic system is presented to find the location of FAZ in fundus fluorescein angiogram photographs. The method is based on two procedures: digital curvelet transform (DCUT) and morphological operations. Firstly, end points of vessels are detected based on vessel segmentation using DCUT. By connecting these points in the selected region of interest, FAZ region is extracted. Secondly, vessels are subtracted from the retinal image, and morphological dilatation and erosion are applied on the resulted image. By choosing an appropriate threshold, FAZ region is detected. The final FAZ region is extracted by performing logical AND between two segmented FAZ. Our experiments show that the system achieves, respectively, the specificity and sensitivity of (>98 and >96 %) for normal stage, for mild/moderate non-proliferative DR (NPDR) (>98, and >95 %) and for Sever NPDR + PDR (>97 and >93 %).     

Design adaptations in a large and deep urban excavation: Case study

In this paper, design, re-design, and performance of a long-standing very deep excavation, which was originally planned to depth of 38 m, are presented. Over-digging was not planned in the original design, thus the reassessment was performed. Two main topics were followed: deepening to increase the maximum depth of an existent excavation from 38 m to 42.5 m, and feasibility for upgrading a predesigned support system from temporary to permanent support system. The geological investigations in the project site illustrated a type of stiff and cemented coarse-grained alluvium. An observational approach with additional geotechnical investigations and in situ tests was applied. Back analyses of stability of an unsupported access ramp, as well as deformation monitoring of walls, were used in order to review geotechnical design parameters that represent the full-scale behavior of the ground. Additional nails and soldier piles together with building mat foundation were implemented as a complementary lateral support in the retaining system. From an engineering point of view, by assuming a corrosion rate of 0.065 mm/a for existent rebars, according to chemical and electrical resistivity tests, the long-term performance of the revised retaining system was verified by static and pseudo-dynamic ultimate limit state analyses. Performance monitoring during the construction shows that the measured deformation is in the lower limit of the prediction.