234 research outputs found
Estimating the avoidable burden of certain modifiable risk factors in osteoporotic hip fracture using Generalized Impact Fraction (GIF) model in Iran
Backgrounds: The number of hip fractures, the most common complication of osteoporosis, has increased rapidly over the past decades. The goal of this study is to estimate the avoidable burden of certain modifiable risk factor of the condition using the Generalized Impact Fraction (GIF) model, which has been suggested and used by epidemiologists to overcome the drawbacks associated with the use of Attributable Fraction index. In addition to preventing a risk factor or the avoidable fraction of burden, this index can also calculate the change in the burden, when a risk factor is altered.Methods: International databases were searched through PubMed, CINAHLD, Embase using OVID and Google scholar. National resources were searched through IranDoc, IranMedex, SID and Journal sites. Other resources include abstract books and articles sent to the IOF congress. The following search strategy was used: (" Osteoporotic fracture" OR " Fragility Hip fracture" OR " Calcium" OR " vitamin D" OR " BMI" OR " lean body weight" OR " Physical activity" OR " exercise" OR " Smoke" ) AND (" prevalence" OR " incidence" OR " relative risk" ) and limited to " humans." Results: With regards to different scenarios already explained in modifying the studied risk factors, the greatest impact in reducing the prevalence of risk factors on osteoporotic hip fractures, was seen in low serum vitamin D levels, low physical activity and low intake of calcium and vitamin D, respectively. According to the fact that interventions for low serum vitamin D and low intake of calcium and vitamin D, are related to each other, it can be concluded that implementing interventions to change these two risk factors, in the easy, moderate and difficult scenarios, would result in approximately a 5%, 11% and 17% decrease in the burden of osteoporotic hip fractures, respectively. The addition of interventions addressing low physical activity in the easy, moderate and difficult scenarios, an 8%, 21% and 35% reduction in the burden of osteoporotic hip fractures would be reported, respectively.Conclusion: Improving serum vitamin D levels, recommending the consumption of calcium and vitamin D supplementations and advocating physical activity are the most effective interventions to reduce the risk of osteoporotic hip fractures. © 2013 Shahnazari et al; licensee BioMed Central Ltd
The thickness effect of rubbery nanofibrous mat on modes I–II fracture mechanism of composite laminates
This study investigates the effect of the interleaving nanofibers, made of NBR/PCL blend, on the interlaminar fracture toughness of carbon/epoxy laminates. Different nanomat thicknesses, ranging from 20 μm to 120 μm, were tested at Mode-I and mode-II and results were compared to the non-modified laminates. Acoustic Emission (AE) technique was used to assess the influence of interleaving nanofibers on dominant damage modes of the specimens, i.e., matrix cracking, fiber/matrix debonding, and fiber breakage. Moreover, the damage mechanism and the nanofiber toughening contribution were investigated by means of crack path and surface analysis. Results indicated that the optimum nanomat thickness for mode-I is 40 μm (GI,R = + 333 %), while for mode-II is 20 μm (GII,R = + 43 %). The study also confirmed by AE the significant impact of nanofibers on various damage modes, especially during mode-I loading
The road to developing economically feasible plans for green, comfortable and energy efficient buildings
Owing to the current challenges in energy and environmental crises, improving buildings, as one of the biggest concerns and contributors to these issues, is increasingly receiving attention from the world. Due to a variety of choices and situations for improving buildings, it is important to review the building performance optimization studies to find the proper solution. In this paper, these studies are reviewed by analyzing all the different key parameters involved in the optimization process, including the considered decision variables, objective functions, constraints, and case studies, along with the software programs and optimization algorithms employed. As the core literature, 44 investigations recently published are considered and compared. The current investigation provides sufficient information for all the experts in the building sector, such as architects and mechanical engineers. It is noticed that EnergyPlus and MATLAB have been employed more than other software for building simulation and optimization, respectively. In addition, among the nine different aspects that have been optimized in the literature, energy consumption, thermal comfort, and economic benefits are the first, second, and third most optimized, having shares of 38.6%, 22.7%, and 17%, respectively
The surgery-first approach for orthognathic correction of maxillary deficiency—is it stable? Three-dimensional assessment of CBCT scans and digital dental models
The aim of this study was to determine the skeletal stability of Le Fort I maxillary advancement following the surgery-first approach, by three-dimensional (3D) assessment of cone beam computed tomography (CBCT) scans and digital dental models. CBCT scans of 25 class III patients obtained 1 week preoperatively (T0) and 1 week (T1) and 6 months (T2) postoperatively were superimposed to measure surgical movements (T0–T1) and skeletal relapse (T1–T2). The distorted dentition of the CBCT scans at T1 was replaced with 3D images of the dental models to assess the postoperative occlusion. Surgical movements of the maxilla (mean ± standard deviation values) were 6.79 ± 2.30 mm advancement, 1.28 ± 1.09 mm vertically, and 0.71 ± 0.79 mm mediolaterally. Horizontal rotation (yaw) was 1.56° ± 1.21°, vertical rotation (pitch) 1.86° ± 1.88°, and tilting (roll) 1.63° ± 1.54°. At T2, the posterior relapse was 0.72 ± 0.43 mm (P = 0.001) and relapse in pitch was 1.56° ± 1.42° (P = 0.007). There was no correlation between the size of the surgical movements and the amount of relapse. A weak correlation was noted between the number of teeth in occlusal contact immediately following surgery and relapse of maxillary roll (r = − 0.434, P = 0.030). The stability of maxillary advancement with the surgery-first approach was satisfactory and was not correlated with the quality of the immediate postoperative occlusion
A suggested prototype for assessing bone health
Background- Osteoporosis is becoming a health concern worldwide. Considering the fact that prevention plays an important role in reducing the burden of this silent disease and in view of the limited resources available, many countries have adopted certain programs to fight osteoporosis through shifting their attention towards at-risk individuals. The Iranian Multicenter Osteoporosis Study (IMOS) is one of these programs. The program aims to assess bone health and the prevalence of vitamin D deficiency in different parts of Iran with various altitudes, latitudes and lifestyle habits in a way that the results could be generalized to the country. Method- The present article presents the protocol used in the third phase of the study. It was designed based on the experiences gathered in the previous phases to overcome the shortcomings particularly subject loss. The questionnaire applied in this study was developed based on a thorough literature review of the risk factors and secondary causes of osteoporosis and was approved by an expert panel. It should be added that while the majority of the existing studies aim to study a certain aspect of osteoporosis, the present protocol provides the information needed for policy makers and researchers to study different osteoporosis-related issues. Conclusion- The authors believe the protocol, to be implemented with small modifications, can help policymakers in different parts of the world, particularly developing countries, gather accurate information on different aspects of bone health at the national level. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved
Review of Person Re-identification Techniques
Person re-identification across different surveillance cameras with disjoint
fields of view has become one of the most interesting and challenging subjects
in the area of intelligent video surveillance. Although several methods have
been developed and proposed, certain limitations and unresolved issues remain.
In all of the existing re-identification approaches, feature vectors are
extracted from segmented still images or video frames. Different similarity or
dissimilarity measures have been applied to these vectors. Some methods have
used simple constant metrics, whereas others have utilised models to obtain
optimised metrics. Some have created models based on local colour or texture
information, and others have built models based on the gait of people. In
general, the main objective of all these approaches is to achieve a
higher-accuracy rate and lowercomputational costs. This study summarises
several developments in recent literature and discusses the various available
methods used in person re-identification. Specifically, their advantages and
disadvantages are mentioned and compared.Comment: Published 201
R&D Planning of Thorium Fuel Pellets Fabrication Using Technology Roadmapping Technique
Increasing of the global energy demand, effects of greenhouse gases emissions and restrictions on the use of renewable energies, will inevitably lead to rise again nuclear energy in the future. Due to the importance of energy security and the sustainability of resources, better waste management, as well as the inability to use nuclear proliferation, many countries have focused on the use of Thorium fuel in the nuclear energy field. It is very difficult to select appropriate technologies and make the right decisions about investing for R & D managers and policymakers because of resource constraints. The aim of this study is to use the technology roadmapping to support the development of the Thorium fuel pellets fabrication technology planning. First, the types of technology roadmapping processes were identified and T-plan approach were selected. Next, by holding workshops and expert panels, the type of fuel pellet, mixed Thorium with 4.8% enriched Uranium oxide pellet, was selected among carbide, oxide and metal fuels and its functional characteristics determined. Based on the technology importance, which was considered as capability and attractivity indicators, sedimentation and sol-gel methods were selected for powder production technologies, and SGMP and powder metalorgy methods were chosen because of their priorities. Finally, with the suggestion of research projects for the acquisition of technical knowledge of Thorium Fuel pellet fabrication, the technology roadmap was developed
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Persistence of earnings and prediction of future cash flows: the role of timely recognition of bad news
Timely recognition of losses and expenses compared to revenues and increased values precipitates future expenses to match with current revenues. Thus, timely recognition of losses acts to reduce the persistence of earnings. However, it is expected that a more timely recognition of negative cash flows, as bad news, increase the power of earnings for predicting future cash flows. This study investigates the effects of the timely recognition of bad news (loss) versus the good news on the decrease of the persistence of earnings, and the effect of negative cash flows on forecasting future cash flows. In this study, two pooling type models and a panel type model have been used to estimate the persistence of earnings and cash flows. Seventy eight firms that were listed in the Tehran Stock Exchange during the period 2003–2010 were duly reviewed. The results of this research proved that the timely recognition of loss does not affect the persistence and the power of earnings for the purpose of forecasting future cash flows. The findings imply that conservatism does not distort persistence of earnings
Investigating the Impact of Polymer and Portland Cement on the Crack Resistance of Half-Warm Bituminous Emulsion Mixtures
Cold mix asphalt (CMA) is emerging as an environmentally friendly alternative to traditional hot mix asphalt (HMA). It offers advantages such as lower costs, reduced energy demands, decreased environmental impacts, and improved safety aspects. Among the various types of CMA, the cold bitumen emulsion mixture (CBEM) stands out. The CBEM involves diluting bitumen through emulsification, resulting in lower bitumen viscosity. However, this process has certain drawbacks, including extended setting (curing) times, lower early strength, increased porosity, and susceptibility to moisture. This study focuses on enhancing CBEM properties through the utilization of low-energy heat techniques, such as microwave technology, and the incorporation of a polymeric additive, specifically acrylic. These innovations led to the development of a novel paving technology known as a half-warm bitumen emulsion mixture (HWBEM). The research was conducted in two phases. First, the study assessed the impact of low-energy heating on the CBEM. Subsequently, it explored the combined effects of low-energy heating and the addition of an acrylic polymer. CBEM samples containing ordinary Portland cement (OPC) as an active filler were utilized in the sample manufacturing process. The effectiveness of these techniques in enhancing crack resistance was evaluated by analysing the results of the indirect tensile strength test. Notably, CBEM samples containing an amount of 2.5% of acrylic polymer and OPC exhibited the highest resistance to cracking. Furthermore, significant improvements were observed in their volumetric and mechanical properties, comparable to those of HMA
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