Finite element model of ocular adduction with unconstrained globe translation.

Details of the anatomy and behavior of the structures responsible for human eye movements have been extensively elaborated since the first modern biomechanical models were introduced. Based on these findings, a finite element model of human ocular adduction is developed based on connective anatomy and measured optic nerve (ON) properties, as well as active contractility of bilaminar extraocular muscles (EOMs), but incorporating the novel feature that globe translation is not otherwise constrained so that realistic kinematics can be simulated. Anatomy of the hemisymmetric model is defined by magnetic resonance imaging. The globe is modeled as suspended by anatomically realistic connective tissues, orbital fat, and contiguous ON. The model incorporates a material subroutine that implements active EOM contraction based on fiber twitch characteristics. Starting from the initial condition of 26° adduction, the medial rectus (MR) muscle was commanded to contract as the lateral rectus (LR) relaxed. We alternatively modeled absence or presence of orbital fat. During pursuit-like adduction from 26 to 32°, the globe translated 0.52 mm posteriorly and 0.1 mm medially with orbital fat present, but 1.2 mm posteriorly and 0.1 mm medially without fat. Maximum principal strains in the optic disk and peripapillary reached 0.05-0.06, and von-Mises stress 96 kPa. Tension in the MR orbital layer was ~ 24 g-force after 6° adduction, but only ~ 3 gm-f in the whole LR. This physiologically plausible simulation of EOM activation in an anatomically realistic globe suspensory system demonstrates that orbital connective tissues and fat are integral to the biomechanics of adduction, including loading by the ON

Size- and speed-dependent mechanical behavior in living mammalian cytoplasm

Active transport in the cytoplasm plays critical roles in living cell physiology. However, the mechanical resistance that intracellular compartments experience, which is governed by the cytoplasmic material property, remains elusive, especially its dependence on size and speed. Here we use optical tweezers to drag a bead in the cytoplasm and directly probe the mechanical resistance with varying size a and speed V. We introduce a method, combining the direct measurement and a simple scaling analysis, to reveal different origins of the size- and speed-dependent resistance in living mammalian cytoplasm. We show that the cytoplasm exhibits size-independent viscoelasticity as long as the effective strain rate V/a is maintained in a relatively low range (0.1 s −1 < V/a < 2 s −1 ) and exhibits size-dependent poroelasticity at a high effective strain rate regime (5 s −1 < V/a < 80 s −1 ). Moreover, the cytoplasmic modulus is found to be positively correlated with only V/a in the viscoelastic regime but also increases with the bead size at a constant V/a in the poroelastic regime. Based on our measurements, we obtain a full-scale state diagram of the living mammalian cytoplasm, which shows that the cytoplasm changes from a viscous fluid to an elastic solid, as well as from compressible material to incompressible material, with increases in the values of two dimensionless parameters, respectively. This state diagram is useful to understand the underlying mechanical nature of the cytoplasm in a variety of cellular processes over a broad range of speed and size scales. Keywords: cell mechanics; poroelasticity; viscoelasticity; cytoplasmic state diagra

The efficacy of Schwann cell transplantation on motor function recovery after spinal cord injuries in animal models: A systematic review and meta-analysis

Aim: This article aimed to assess the efficacy of Schwann cell transplantation on motor function recovery in animal model of spinal cord injuries via meta-analysis. Methods: An extended search was carried out in the electronic databases of Medline (via PubMed), EMBASE (via OvidSP), CENTRAL, SCOPUS, Web of Science (BIOSIS), and ProQuest. Finally, 41 eligible studies conducted on 1046 animals including 517 control animals and 529 transplanted animals were included in the meta-analysis. Pooled standardized mean difference (SMD) and odds ratio (OR) with 95% confidence interval (95% CI) were reported. Results: The findings showed that treatment with Schwann cells leads to a modest motor function recovery after spinal cord injury (SMD = 0.85; 95% CI: 0.63–1.07; p < 0.001). Transplantation of these cells in acute phase of the injury (immediately after the injury) (OR = 4.30; 95% CI: 1.53–12.05; p = 0.007), application of mesenchymal/skin-derived precursors (OR = 2.34; 95% CI: 1.28–4.29; p = 0.008), and cells with human sources are associated with an increase in efficacy of Schwann cells (OR = 10.96; 95% CI: 1.49–80.77; p = 0.02). Finally, it seems thatthe efficacy of Schwann cells in mice is significantly lower than rats (OR = 0.03; 95% CI: 0.003–0.41; p = 0.009). Conclusion: Transplantation of Schwann cells can moderately improve motor function recovery. It seems that inter-species differences might exist regarding the efficacy of this cells. Therefore, this should be taken into account when using Schwann cells in clinical trials regarding spinal cord injuries

Diode Laser in Minor Oral Surgery: A Case Series of Laser Removal of Different Benign Exophytic Lesions

Introduction: The role of laser in conservative management of oral disease is well established. Laser procedures are common in the fields of oral surgery, implant dentistry, endodontic, and periodontic therapy.Case: This case series describes the use of diode laser for the excision of oral exophytic lesions. All the patients attended the oral medicine department of Shahid Beheshti University of Medical Sciences, Tehran, Iran. Criteria in patient selection were accessibility to lesions, patient fear from blade surgery, aesthetics, and probability of bleeding. An informed consent was filled by every patient. All of the lesions were completely excised under local anaesthesia by diode laser with 300 μm-fibre tip, 808 nm continuous wavelength and 3-3.5 W power for 3×60 seconds (Dr Smile, Italia). During surgery, the fibre tip was in contact with lesions. No analgesics were prescribed to the patients. The patients were followed for the first, second, and forth week after treatment.Conclusion: The lesions could be excised using the diode laser. This procedure was a quick clinical technique without bleeding

The Relation between Energy Consumption in Small Urban Workshops and their Environmental Pollution Emissions: a case study from Qom city

Background: One of the major environmental impacts of energy use is air pollutant emissions such as greenhouse gases. The aim of this study was to investigate the relation between energy consumption in small urban businesses and their air pollution in small urban businesses in the city of Qom in 2015. Methods: In the first step, by referring to Qom chamber of trade, a list of all urban jobs from 67 trade :::union:::s was prepared and then, a total of 223 workshops were selected randomly and visited. Means consumption of electricity and gas were calculated by referring to the related gas and electricity offices in Qom. The amount of pollutants produced from energy consumption was calculated by using the software available at the Abraxas Energy website. Results: The results showed that the average monthly consumption of 9098.86 kwh and 41669.35 cubic meters of gas in the small businesses of Qom, on average produced 50.995 of carbon dioxide, 78.963 kg of lead compounds, 52.39 kg nitrogen compounds, 8.403 kg carbon monoxide, 5.02 kg volatile organic compounds, 1.996 kg nitrogen oxides, 1.781 kg mercury compounds and less than 1 kg per month particulate matter and SO2. Conclusion: Any attempt for reducing energy consumption, in addition to its economic benefits, can be a basic measure to reduce environmental pollutants. Implementation of proper management plans for reducing electricity and gas consumption is a major step in this direction. Keywords: Air pollution, Energy, Small workshops, Qom, Ira

Biomechanics of Articular Cartilage: Osteoarthritis and Tissue Engineering

In the normal adult synovial articular joint, articular cartilage (AC) as an avascular tissue, is attached to the calcified cartilage (CC). Calcified cartilage is a thin tissue layer, separated from AC by tidemark (TM), and subchondral bone (ScB) by cement line (CL). Calcified cartilage and subchondral bone plate together form subchondral plate (ScP). ScP merges into a porous network called trabecular bone (TB). Cartilage degeneration and loss may be caused by different diseases such as osteoarthritis (OA) or trauma. There are many vascular canals embedded within subchondral plate which carry various types of cells and blood vessels. In OA, the structure of the cartilage and subchondral plate underneath, the geometry of the canals as well as the spacing between them may change. The effect of ScP changes on the biomechanics of articular cartilage is unclear. Furthermore, after cartilage is lost due to OA or trauma, current efforts are underway to resurface the joint. While methods for bending cartilage have been introduced, the mechanics of such bending are unclear. Thus, this dissertation aims to (1) analyze images of normal (NL) and OA samples in order to clarify the structure of the ScP vascular canals, (2) investigate the effect of such vascular canals on the biomechanics of the deep zone of cartilage and (3) evaluate the mechanics of articular cartilage sheet as a poroelastic material under pure bending.In (1) Digital Volumetric Images were used to obtain 2-D cross sections of cartilage and subchondral plate of 5 OA and 6 NL samples. Vascular canal were found as 12 different types associated with the presence/absence of a cap and the degree of canal penetration of the ScP and AC. In NL samples, there were no invaded open canal through tidemark, while from 37 open canals were found in OA samples, 11 of which penetrated the tidemark. The diameter of canals was smaller (27 μm) in NL samples than (67 μm) in OA samples. The spacing between the open canals was smaller (135 μm) in OA samples than (809 μm) in NL.In (2), using three small, mean and large diameters and spacing, a confined compression test was analyzed with ABAQUS software to analyze the effect of change of size and spacing of those canals on the spatial and temporal distribution of fluid pressure as well as strain-stress through articular cartilage. With the increase of the diameters of the canals and decrease of the spacing between them, fluid pressure (pore pressure) within cartilage, especially at the deep zone, decays. Furthermore, with the increase of the spacing between canals, the mechanical response of the sample becomes close to that of NL sample In (3), poroelastic theory was applied to evaluate the biomechanics of cartilage under pure bending. Under pure bending, axial strain varies linearly between compression and tension (concave to convex). In the bent state, the bending moment relaxes as strain redistributes axially, and fluid is exuded from the compressed region and imbibed in the stretched region. At equilibrium, the bending moment and strain stabilize as fluid ceases to flow. After the bending is suddenly released, creep recovery occurs as fluid flow into and out of the sheet reverses and also redistributes within the sheet.These studies developed models to describe the biomechanics of articular cartilage as a poroelastic material when subjected to various loading and boundary conditions. The prediction of loading effects on the deep zone of OA cartilage may be involved in progressive cartilage degeneration. The understanding of time-dependent mechanical behavior of poroelastic sheet under bending may help develop loading strategies to achieve an appropriately contoured shape before implantatio

Biomechanics of Articular Cartilage: Osteoarthritis and Tissue Engineering

In the normal adult synovial articular joint, articular cartilage (AC) as an avascular tissue, is attached to the calcified cartilage (CC). Calcified cartilage is a thin tissue layer, separated from AC by tidemark (TM), and subchondral bone (ScB) by cement line (CL). Calcified cartilage and subchondral bone plate together form subchondral plate (ScP). ScP merges into a porous network called trabecular bone (TB). Cartilage degeneration and loss may be caused by different diseases such as osteoarthritis (OA) or trauma. There are many vascular canals embedded within subchondral plate which carry various types of cells and blood vessels. In OA, the structure of the cartilage and subchondral plate underneath, the geometry of the canals as well as the spacing between them may change. The effect of ScP changes on the biomechanics of articular cartilage is unclear. Furthermore, after cartilage is lost due to OA or trauma, current efforts are underway to resurface the joint. While methods for bending cartilage have been introduced, the mechanics of such bending are unclear. Thus, this dissertation aims to (1) analyze images of normal (NL) and OA samples in order to clarify the structure of the ScP vascular canals, (2) investigate the effect of such vascular canals on the biomechanics of the deep zone of cartilage and (3) evaluate the mechanics of articular cartilage sheet as a poroelastic material under pure bending.In (1) Digital Volumetric Images were used to obtain 2-D cross sections of cartilage and subchondral plate of 5 OA and 6 NL samples. Vascular canal were found as 12 different types associated with the presence/absence of a cap and the degree of canal penetration of the ScP and AC. In NL samples, there were no invaded open canal through tidemark, while from 37 open canals were found in OA samples, 11 of which penetrated the tidemark. The diameter of canals was smaller (27 μm) in NL samples than (67 μm) in OA samples. The spacing between the open canals was smaller (135 μm) in OA samples than (809 μm) in NL.In (2), using three small, mean and large diameters and spacing, a confined compression test was analyzed with ABAQUS software to analyze the effect of change of size and spacing of those canals on the spatial and temporal distribution of fluid pressure as well as strain-stress through articular cartilage. With the increase of the diameters of the canals and decrease of the spacing between them, fluid pressure (pore pressure) within cartilage, especially at the deep zone, decays. Furthermore, with the increase of the spacing between canals, the mechanical response of the sample becomes close to that of NL sample In (3), poroelastic theory was applied to evaluate the biomechanics of cartilage under pure bending. Under pure bending, axial strain varies linearly between compression and tension (concave to convex). In the bent state, the bending moment relaxes as strain redistributes axially, and fluid is exuded from the compressed region and imbibed in the stretched region. At equilibrium, the bending moment and strain stabilize as fluid ceases to flow. After the bending is suddenly released, creep recovery occurs as fluid flow into and out of the sheet reverses and also redistributes within the sheet.These studies developed models to describe the biomechanics of articular cartilage as a poroelastic material when subjected to various loading and boundary conditions. The prediction of loading effects on the deep zone of OA cartilage may be involved in progressive cartilage degeneration. The understanding of time-dependent mechanical behavior of poroelastic sheet under bending may help develop loading strategies to achieve an appropriately contoured shape before implantatio

Health Care Financing for the Victims of Traffic Accidents in Iran; Challenges and Solutions

Background: Traffic accidents are the first cause of death in Iran and due to its necessity in the fourth and fifth Socio-Economic Development plan, two laws (articles No. 92 and 37) were passed to provide immediate and free service to traffic victims. The current study was designed to explore the challenges and complexities related to health care financing for this victims and to provide solutions. Method: In this applied research, the qualitative phenomenological approach was used. All interviews were conducted in 2013 by semi-structured questions with 36 people including the managers at the Ministry of Health, Medical Sciences Universities, trauma specialized hospitals and basic insurances. Sampling was done using snowball, targeted and quota techniques. Data analysis was done using framework method and through Atlas Ti 5.2 software. Results: As a result of qualitative analysis, 3 main themes, 14 codes and 4 sub- codes were identified. The main challenges of health care financing for victims of traffic accidents included challenges of financial integration, accumulation, distribution of financial resources and service purchasing. Conclusions: Creating a process to collect more appropriate resources for article No. 92 at the Ministry of Health, compiling a services package and applying strong monitoring to improve the quality of services were found as mechanisms that can be used to obtain sustainable financing and quality in providing services to victims of traffic accidents. Keywords: Financing, Victims of traffic accidents, Health Car

On η-Upper Sign Property and Upper Sign Continuity and Their Applications in Equilibrium-Like Problems

We first introduce the notion of η-upper sign property which is an extension of the upper sign property introduced in Castellani and Giuli, 2013, by relaxing convexity on the set. Afterwards, we establish a link between the solution sets of local dual equilibrium problem (Minty local equilibrium problem) and equilibrium problem for mappings whose domains are not necessarily convex by relaxing the upper sign continuity on the map, as it is assumed in the literature (Bianchi and Pini, 2005; Castellani and Giuli, 2013; Farajzadeh and Zafarani, 2010). Accordingly, it allows us to extend and obtain some existence results for equilibrium-like problems