Bone mineral density in Iranian patients: Effects of age, sex, and body mass index

Introduction: Osteoporosis is a multifactorial skeletal disease that is characterized by reduced bone mineral density (BMD). BMD values de-pend on several factors such as age, sex and age at menopause. The purpose of this study was to determine the prevalence and changes in bone mineral density in Iranian patients. Meth-ods: Three hundred patients were selected through random sampling technique in 2009. BMD was assessed by Norland (Excell) technique at the lumbar and femoral neck. Weight and height were measured through standard methods. A thorough history was taken from each patient. The data was analyzed using SPSS software version 13.0. P-values less than 0.05 were con-sidered statistically significant. Results: From among the 300 studied patients, 86.6% were fe-male. their mean age was 52.7 years. Their av-erage body mass index (BMI) was 28.14 kg/m2. Mean T-Score at lumbar spine and femoral neck was −1.07 ± 1.19 and −1.75 ± 1.33 respectively. Mean BMD value at lumbar spine and femoral neck was 0.92 ± 0.19 and 0.77 ± 0.16 respectively. The prevalence of osteoporosis at lumbar spine and femoral neck was 33.7% and 16.7, respec-tively. There was a significant correlation be-tween age, BMI and BMD values (P-Value < 0.01). Correlation between gender and BMD value at the lumbar spine and femoral neck was not sig-nificant. Conclusion: This study shows that age- ing and low BMI are risk factors associated with bone loss. it is recommended to measure BMD and implement prevention programs for high- risk people. Keywords: Bone Mineral Density; Body Mass Index;Age; Gende

The residual STL volume as a metric to evaluate accuracy and reproducibility of anatomic models for 3D printing: application in the validation of 3D-printable models of maxillofacial bone from reduced radiation dose CT images.

BackgroundThe effects of reduced radiation dose CT for the generation of maxillofacial bone STL models for 3D printing is currently unknown. Images of two full-face transplantation patients scanned with non-contrast 320-detector row CT were reconstructed at fractions of the acquisition radiation dose using noise simulation software and both filtered back-projection (FBP) and Adaptive Iterative Dose Reduction 3D (AIDR3D). The maxillofacial bone STL model segmented with thresholding from AIDR3D images at 100 % dose was considered the reference. For all other dose/reconstruction method combinations, a "residual STL volume" was calculated as the topologic subtraction of the STL model derived from that dataset from the reference and correlated to radiation dose.ResultsThe residual volume decreased with increasing radiation dose and was lower for AIDR3D compared to FBP reconstructions at all doses. As a fraction of the reference STL volume, the residual volume decreased from 2.9 % (20 % dose) to 1.4 % (50 % dose) in patient 1, and from 4.1 % to 1.9 %, respectively in patient 2 for AIDR3D reconstructions. For FBP reconstructions it decreased from 3.3 % (20 % dose) to 1.0 % (100 % dose) in patient 1, and from 5.5 % to 1.6 %, respectively in patient 2. Its morphology resembled a thin shell on the osseous surface with average thickness &lt;0.1 mm.ConclusionThe residual volume, a topological difference metric of STL models of tissue depicted in DICOM images supports that reduction of CT dose by up to 80 % of the clinical acquisition in conjunction with iterative reconstruction yields maxillofacial bone models accurate for 3D printing

Impact of Dialysis Access Fistula on Cardiac Function After Kidney Transplantation

Introduction. The cardiovascular impact of a patent arteriovenous fistula (AVF) following kidney transplantation has not been clearly described. This study aimed to evaluate the natural history of AVFs in kidney transplant recipients and the effect of spontaneous AVF closure after kidney transplantation on cardiac status. Materials and methods. Data on vascular access for dialysis were collected from medical charts of kidney transplant recipients between July 2009 and November 2010 at a single center. Echocardiographic re-assessment of the AVF flow and cardiac status was done in selected patients with functioning and nonfunctioning AVFs. Results. Of 180 kidney transplant recipients, 142 had AVFs before transplantation and 99 (69.7%) had a functioning fistula at the time of study after kidney transplantation. Twenty-three patients with a functioning AVF were compared with 17 with spontaneously closed AVFs. The left ventricular ejection fraction improved in both groups posttransplant. In the group with patent fistulas, there was a trend towards lower value of left ventricular endsystolic and end-diastolic diameters, but it did not reach statistical significance. The mean fistula flow was 560 +/- 405 mL/min in this group. A significant reduction was observed in the interventricular septum and left ventricular posterior wall diameters in the group with closed AVFs. Conclusions. Spontaneous AVF closure did not offer a significant cardiac beneficial effect. There are insufficient data to promote systematic closure of AVF after successful kidney transplantation

Two-Dimensional and High-Throughput Electrophoretic Separation of Proteins Using Polymeric Microchips

A major task in proteomics is to identify proteins from a biological sample using two-dimensional (2-D) separation prior to mass spectrometry of peptides generated via proteolytic digestion of the proteins. For 2-D separations, microfluidic devices are superior to bench top and capillary-based systems since they potentially provide higher separation efficiencies due to the minimal dead volumes produced during peak transfer between the two separation dimensions. In addition, fast separations can be envisioned because the column lengths are typically shorter in microfluidic platforms without scarifying peak capacity. High-throughput capabilities are extremely desirable for many types of bio-analytical analyses, such as understanding molecular interactions and the role they play in cellular functioning and drug discovery. Polymeric microchips possess a variety of physiochemical properties to match the intended application and their ease of fabrication increases the accessibility of technology to a large research base. In this dissertation, a comprehensive 2-D separation platform for proteins using a polymeric microchip with the ability to perform high performance separations within a few minutes was established. The system combined sodium dodecyl sulfate micro-capillary gel electrophoresis (SDS µ-CGE) with micellar electrokinetic chromatography (MEKC) in a poly(methyl methacrylate), PMMA, microchip and was reported with a programmed pulse injection/separation protocol with laser-induced fluorescence for detection. A novel sixteen-channel polycarbonate (PC) microfluidic device for high-throughput separations of proteins was also presented using a process to pattern gold features as microelectrode array for sixteen parallel channels on microchips. The system was able to simultaneously analyze sixteen different samples in parallel consisting of native proteins, amino acids, peptides, and oligonucleotides with conductivity. Finally, due to the diverse nature of polymer properties and the large number of potential applications for microfluidic chips, the physiochemical properties of various polymers were investigated to guide researchers in selecting the best material for a given application including protein analysis

Evaluation of the Effect of Commercialization of Technology in Creating Sustainable Competitive Advantage of Knowledge-based Companies Emphasizing the Moderating Role of Environmental Factors

The present study aimed at designing a structural equation model of the effect of technology commercialization performance on creating sustainable competitive advantage of knowledgeable companies with an emphasis on the moderating environmental factors.Research population includes 133 managers of knowledge based companies at the center for the growth and development of science and technology Park of East Azerbaijan University and based on the Cochran formula, the sample size was measured to be 99, and selection by stratified random sampling method, and the standard questionnaire is distributed among them. The research is applied in nature and the method is descriptive and survey. Then, the data were analyzed using smart pls software for partial least squares (PLS) path modeling. The results show that the technology commercialization performance has a positive effect on the competitive sustainable advantage of knowledge-based companies, as well as the role of variable moderating environmental factors (market turbulence, competitive intensity and technological turbulence) in the path between the technology commercialization performance and the sustainable competitive advantage of knowledge-based companies

Roundabout accident prediction model: random-parameter negative binomial approach

Roundabouts have been used widely on all road classes in the United Kingdom because they are considered safer than other types of intersections in general. The objective of this study was to examine geometric and traffic characteristics and their influences on the number of accidents. Data from each of 70 roundabouts (with 284 approaches) included all recorded vehicle accidents as well as geometric and traffic characteristics for the entire roundabout, within circulatory lanes, and at roundabout approaches. Resulting estimates were compared with those from random-parameter and fixed-parameter negative binomial count data models. The random-parameter results provided better goodness of fit than the fixed-parameter results, and more variables were found to be significant. Significant variables that influenced the number of accidents were total approach traffic, truck percentage, entry width, inscribed circle diameter, number of lanes, and presence of traffic signals

Upper Extremity Composite Tissue Allotransplantation Imaging

Objective: Upper extremity (UE) transplantation is the most commonly performed composite tissue allotransplantation worldwide. However, there is a lack of imaging standards for pre- and posttransplant evaluation. This study highlights the protocols and findings of UE allotransplantation toward standardization and implementation for clinical trials. Methods: Multimodality imaging protocols for a unilateral hand transplant candidate and a bilateral mid-forearm level UE transplant recipient include radiography, computed tomography (CT), magnetic resonance (MR) imaging, catheter angiography, and vascular ultrasonography. Pre- and posttransplant findings, including dynamic CT and MR performed for assessment of motor activity of transplanted hands, are assessed, and image quality of vessels and bones on CT and MR evaluated. Results: Preoperative imaging demonstrates extensive skeletal deformity and variation in vascular anatomy and vessel patency. Posttransplant images confirm bony union in anatomical alignment and patency of vascular anastomoses. Mild differences in rate of vascular enhancement and extent of vascular networks are noted between the 2 transplanted limbs. Dynamic CT and MR demonstrate a 15° to 30° range of motion at metacarpophalangeal joints and 90° to 110° at proximal interphalangeal joints of both transplanted hands at 8 months posttransplant. Image quality was slightly better for CT than for MR in the first subject, while MR was slightly better in the second subject. Conclusion: Advanced vascular and musculoskeletal imaging play an important role in surgical planning and can provide novel posttransplantation data to monitor the success of the procedure. Implementation of more standardized protocols should enable a more comprehensive assessment to evaluate the efficacy in clinical trials

Numerical Modeling of Financially Sustainable Urban Wastewater Systems

A system dynamics model first developed using the software Stella 7.0.2, which explores the complex behavior of the financially sustainable management of water distribution infrastructure, was converted here into a system of coupled non-linear algebraic differential equations (DAEs). Each differential equation involved a time derivative on a primary variable specifying the temporal evolution of the system. In addition, algebraic (secondary) equations and variables specified the non-linearity inherent in the system as well as any controls on the primary variables constraining the physical evolution of the system relevant to the problem at hand. While Stella employed a Runge-Kutta numerical strategy, the numerical DAE method used a fully-explicit, fully-implicit and Crank-Nicolson Euler scheme combined with a fixed-point iteration to resolve the non-linearity. The Runge-Kutta and numerical DAE solutions deviate markedly when the non-linearity of the system becomes pronounced. I demonstrate point-wise stability of the numerical DAE solution as the timestep is refined. Furthermore, the refined numerical DAE solution does not exhibit any of the spurious oscillations inherent in the Runge-Kutta solution and is physically correct for the problem at hand

Unsteady incompressible Navier-Stokes simulations on deforming domains

Mesh generation has been an important topic of research for the past four decades, primarily because it is one of the critical elements in the numerical simulation of fluid flows. One of the main current issues in this regard is mesh generation and flow solution on domains with moving boundaries. In this research, a novel scheme has been proposed for mesh generation on domains with moving boundaries, with the location of boundary nodes known at any particular time. A new set of linearized equations is derived based on a full nonlinear elliptic grid generation system. The basic assumption in deriving these new equations is that each node experiences only a small amount of disturbance when the mesh moves from one time to the next. Comparison with grids generated by the full elliptic system shows that this new method can generate high quality grids with significantly less computational cost. Inherently, the flow on such a domain will be unsteady. The Navier-Stokes equations for unsteady 2D laminar incompressible flow are expressed in the primitive variables formulation. A SIMPLE-like scheme is applied to link the pressure and velocity fields and ensure conservation of mass is satisfied. The equations are discretized in a pure finite difference formulation and solved by implicitly marching in time. The flow solver is validated against results in the literature for flow through a channel with a moving indentation along one wall