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Genetic and environmental factors are both responsible for the etiology of autism spectrum disorders (ASD). Although epidemiological studies have been conducted to clarify the association between restriction diets and ASD, the conclusion remains unclear. This study was undertaken to investigate the effect of gluten free diet (GFD) on gastrointestinal symptoms and behavioral indices in children with ASD. In this randomized clinical trial, 80 children diagnosed with ASD by the Autism Diagnostic Interview-Revised (ADI-R) were assigned into GFD (n=40) and regular diet (RD) (n=40) groups for 6 weeks. At the beginning and end of the intervention, the ROME Ш questionnaire for evaluating gastrointestinal symptoms and Gilliam Autism Rating Scale 2 questionnaire (GARS-2) for assessing psychometric properties were completed. Of the 80 children, 53.9% had gastrointestinal abnormalities. In the GFD group, the prevalence of gastrointestinal symptoms decreased significantly (P

To date, no studies have provided data on hepatitis B virus (HBV) prevalence among asymptomatic, healthy human T-lymphotropic virus (HTLV-I) positive carriers. This sero- and molecular epidemiology study was performed on patients in the Northeast of Iran, which is an endemic area for HTLV-I infection. A total of 109 sera were collected from HTLV-I positive healthy carriers who were admitted to Ghaem Hospital, Mashhad City. All were tested for HBV serology and subsequently, real time PCR was carried out on the samples, regardless of the results of the serology. Standard PCR and direct sequencing were applied on positive samples. All cases were negative for HBsAg, Anti-HBc, and anti-HBs were positive in 34 (31.1%), and 35 (32%) individuals, respectively. There were 19 (17.4%) cases that were positive only for anti-HBs, and they had already received HBV vaccine. 16 (15%) were positive for both anti-HBs and anti-HBc, indicating a past-resolved HBV infection. 18 (16.5%) were isolated as anti-HBc, and 56 (51.3%) were negative for all HBV serological markers. Only one subject (0.9%) had detectable HBV DNA (2153 copy/ml), and assigned as being an occult HBV infection. The low prevalence of HBsAg, despite the high percentage of anti-HBc positive cases, might be related to the suppression effect of HTLV-I on surface protein expression. The low prevalence of HBV infection among HTLV-I positive healthy carriers from an endemic region, indicates that the epidemiology of HTLV-I and HBV coinfection is related to the endemicity of HBV in that region, rather than HTLV-I endemicity.

The paper describes the design of computerized decision aid (DA) and a protocol for a cluster randomized controlled trial to study the effects of computerized DA on decisional conflict and knowledge of pregnant Iranian women pertaining to the mode of delivery: Caesarean section vs. vaginal delivery.

Background: The effect of psychosocial work environment on personal and organizational aspects of employees is well-known; and it is of fundamental importance to have valid tools to evaluate them. This study aims to evaluate the reliability and validity of the Persian version of Copenhagen Psychosocial Questionnaire (COPSOQ). Methods: The questionnaire was translated into Persian and then back translated into English by two translators separately. The wording of the final Persian version was established by comparing the translated versions with the original questionnaire. One hundred three health care workers completed the questionnaire. Chronbach’s alpha was calculated, and factor analysis was performed. Results: Factor analysis revealed acceptable validity for the five contexts of the questionnaire. Cronbach’s alpha ranged from 0.73 to 0.82 in different contexts. Conclusion: This study revealed that the Persian version of COPSOQ is a reliable and valid instrument for measuring psychosocial factors at work.

precise assessment of location of vegetation may be challenging in the presence of pacemaker and intracardiac defibrillator leads as well as tricuspid annuloplasty ring or bioprosthetic tricuspid valve by transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE), due to

Background: Histopathologic assessment of liver tissue is an essential step in management and follow-up of non-alcoholic fatty liver disease (NAFLD) while inter- and intra-observer variations limit the accuracy of these assessments. Objectives: The aim of this study was to assess the inter- and intra-observer reproducibility of histopathologic assessment of liver biopsies based on NAFLD activity score (NAS) scoring system. Materials and Methods: The anonymous liver biopsy samples of 100 consecutive NAFLD suspected adults were randomly assigned to four pathologists. Then, the samples were randomly reassigned to the pathologists for the second time in a way that each sample would be evaluated by two different pathologists. Biopsies were revisited by their first evaluator after two months. The results were reported based on NAS scoring system. Results: Inter-observer agreement of the pathology scores based on NAS scoring system was acceptable for steatosis, lobular inflammation, and fibrosis, but not for hepatocyte ballooning. The intra-observer agreement was acceptable in all scales, with lowest intra-class correlation observed for lobular inflammation. Conclusions: NAS scoring system has good overall inter- and intra-observer agreement, but more attention should be given to defining the hepatocyte ballooning and lobular inflammation, and training the pathologists to improve the accuracy of pathology reports.

LingoBee is a mobile application, which was designed as a tool for language learning. This application assists learners by providing them a community for language learning. This mobile app is running on Android operation system, and using Web 2.0 technology.There are pre-existing social network applications that is used for language learning such as Livemocha. But LingoBee focuses not only on social network sites but also creating communities for language learning.In this thesis I will analyze LingoBee user data collection, in order to evaluate this application. This evaluation is based on two aspects. First, LingoBee can provide an environment for learners to develop their learning process. Second, LingoBee gives the language learning communities the necessary environment to improve. There are too many articles exists on these topics but none of them have consider these to aspects together.

Background: The presence of an infected family member significantly increases the risk of HBV transmission, but many socio-demographic and viral characteristics of family members affect the transmission rate. Objectives: In this study, we have used data mining techniques to investigate the impact of different variables in intrafamilial transmission of HBV infection. Patients and Methods: demographic information, viral markers, and medical history of 330 patients with chronic hepatitis B and their offspring attending a referral center in Tehran were collected. Data-mining techniques were administered to detect patterns. Results: The overall transmission rate was 15.7% (5.4% and 27.3% for male and female index cases respectively). In female patients, HBe Ag positively affected the transmission rate (49% vs. 23.4%). There was a dominant change in transmission rate of female patients with negative results for Hbe Ag with HDV coinfection, where the transmission rate changed from 25% in patients with negative results for HDV Ab to 5% in those with positive results. In Hbe Ag negative male index cases, the transmission rate was 1.3% in cases with positive results for HDV Ab compared to 7% in those with negative findings. The overall transmission rate was statistically different between patients with positive and negative results for HDV Ab (P = 0.016). Conclusions: There is a minor but consistent pattern change in the presence of HDV infection which reduces familial transmission of HBV, especially in female patients with negative results for HBe Ag.

The present study is intended to investigate and compare the hemodynamics in two different sizes of hemodialysis arteriovenous grafts for upper arm hemodialysis vascular access: 8-mm tapered to 6-mm at the arterial side and straight 6 mm. A computational simulation approach is presented for this study, which is validated against the available experimental and numerical pressure measurements in the literature. The imposed boundary conditions at the arterial inlet and venous outlet boundaries of the models are physiological velocity and pressure waveforms, respectively. Blood flow fields and distribution patterns of the hemodynamic indices including wall shear stress (WSS) as one of the major hemodynamic parameters of the cardiovascular system and spatial wall shear stress gradient (SWSSG) as an indicator of disturbed flow patterns and hence susceptible sites of lesion developments are analyzed and compared between the two grafts. The tapered 6- to 8-mm graft seemingly is associated with less disturbed flow patterns within the venous anastomosis (VA) and the vein downstream while benefiting from higher blood flow rates within. Also, it shows a definitive advantage in terms of WSS and SWSSG distribution patterns around the VA and throughout the vein downstream with significantly lower values, which reduce the risk of thrombosis formation and stenotic lesion developments. The only disadvantage encountered in using 6- to 8-mm tapered graft is higher values of hemodynamic parameters at the arterial junction attributable to its significantly higher mean blood flow rate within. The results clearly indicate that the tapered 6- to 8-mm graft entirely outperforms straight 6-mm graft hemodynamically as an upper arm hemodialysis vascular access graft and confirms clinical data in the literature, which suggests advantageous use of tapered 6- to 8-mm grafts in the creation of upper arm brachioaxillary hemodialysis vascular access grafts in selected groups of patients with expectably higher patency rates and lower complications.

Sleep problems are common complaints in health care workers that can affect quality of life and productivity, both in patients and healthy individuals. This study evaluates the prevalence of low sleep quality in health care workers with no health issues or complaints of sleep problems.In this cross-sectional study was conducted on healthy employees of a health care organization in Tehran. The presence of physical and mental health issues and satisfaction from their sleep quality was assessed by means of a self-administered questionnaire. Sleep quality was evaluated by the Persian version of the Pittsburgh Sleep Quality Index (PSQI). PSQI scores of 5 or less were considered as good sleep quality.From 925 participants, 56.9% were good sleepers. There was a significant association between poor sleep quality and female sex, divorced, shift-working, and age; it was not associated with education level. Self-rated health (SRH) had a significant positive correlation with sleep quality.Poor sleep quality is common in our study population and associated with a lower SRH. The high prevalence of poor sleep quality in a group of healthy non-complaining employees can be an important early sign of underlying physical or mental health issues. Providing screening and monitoring programs to detect the underlying health conditions and their consequent treatment can promote health and productivity of employees and improve society's health, both directly and indirectly.

Immediate loading has gained a lot of attentions in dental rehabilitation. The goal of the present paper is to evaluate the stress distribution within the dental prosthesis and the bone-implant interface using finite element analysis. A precise 3D model of human mandible and prosthesis is employed and subjected to immediate loading. The results show that the stress levels in prosthetic components have not exceeded the failure threshold. The maximum stress occurs at the superficial regions of the cortical part and buccal sides of the interface receive higher stress magnitudes.

Fixed orthodontic treatment is based on effective bonding of bracket to enamel surface. During orthodontic therapy, load is applied on bracket slot by orthodontic wire, and then it is transferred to adhesive layer and enamel surface (state I). After the completion of treatment period, orthodontic brackets are debonded by load application on the incisal region of bracket-adhesive interface (state II). In order to compare the diversity in stress distribution pattern of these two states, micro CT images of maxillary premolar tooth and bracket were transformed to STL files and imported to Hypermesh software to create high quality 3D finite element models. Space between enamel and bracket was filled with orthodontic adhesive material which sets to 0.2 mm at thickest region. Mechanical property was assigned to each layer and appropriate boundary conditions were applied. By using a load distributing element RBE3, firstly 150 N shear load was applied on the bracket slot to simulate bracket-adhesive-tooth system of state I and secondly the same load was applied on the incisal area of bracket and bracket-adhesive bonding to simulate bracket-adhesive-tooth system of state II. Generated stresses on the bracket, the adhesive and the tooth in both systems were obtained and compared to each other. The Findings of this study, reveal that the effect of bonding loads was directly transform to the adhesive layer and the enamel surface; hence, treatment period would decrease. Alternatively, debonding loads would bring about higher stresses on the bracket and facilitate debonding action.

Background: Zinc plays an important role in a wide variety of metabolic processes in animal systems. The role of zinc in preservative treatment, fungicidal action and medicine, and addition of supplementary zinc have increased the probability of zinc toxicity, specially the chronic type. It is known that the composition and quantity of saliva influence the oral health. Regarding people's exposure to zinc in routine life and the importance of saliva, our purpose was to investigate the effects of oral zinc intoxication on secretory function in rat salivary glands and also on serum composition. Methods: In this study, there were five groups of female rats. Four groups received zinc acetate dehydrate through their drinking water. After 3 months of experiment, the chemical characteristics and flow rate of saliva and weight of salivary glands were determined. The effects of zinc on hematological and chemical factors of plasma were assessed too. Results: Flow rate of submandibular glands was significantly lower in experimental groups and there were significant changes in Na+, Ca2+ and K+ concentration both in saliva and in plasma. The serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, glucose levels in the plasma and urine creatinine levels were also altered in experimental groups in comparison with the control group. Conclusion: Our results show that zinc toxicity will affect the quantity and quality of saliva probably through changes in the various neurologic pathways to the salivary glands or effects on acinar cells of the salivary glands. Furthermore, our results showed that zinc toxicity will affect the liver and renal function.

Orthodontic braces are used to modify, malocclusions of teeth and jaws. Most of problems in dentistry can be investigated from a biomechanical point of view. Stress distribution in bracket, adhesive and tooth has been used as a criterion to determine bond strength of bracket- adhesive- tooth system. Tooth is consisted of three layers including enamel, dentin and pulp with three different mechanical properties, although most of previous studies have not paid attention to this and have considered the tooth as one layer material with unique mechanical property. In this study, Micro CT images of a tooth and a bracket were imported in Mimics 10 and different layers of the tooth were segmented. The bracket, the whole tooth and each layers of tooth were exported as STL files, separately. STL files of two bracket- adhesive- tooth systems including the system that have considered the whole tooth as a unique material and the system with segmented tooth layers were imported in Hypermesh software to create high quality 3D finite element meshes. The space between enamel and bracket has been filled with orthodontic adhesive substance that sets to 0.2 mm at thickest parts. For each system, property of each layer was assigned and appropriate boundary conditions were applied. Finally, pattern of stress distribution of two systems were compared with each other. The findings of this study show that both of the systems had similar pattern of stress distribution and stresses generated on the dentin and pulp of the system with segmented tooth layers were of lower magnitude in comparison with other layers. In the other words, anatomical details of dentin and pulp do not affect the results of study, significantly.

Something about 1 million skeletal defects are reported each year, which are in need of bone-grafting to be cured. Note that population of the world is getting older and so the probability of bone fractures is increasing, while dealing with this would have lots of social and economical effects. Bone grafts can be both autologous and autogenous or as an alternative, be made of nonorganic materials such as metals, polymers, ceramics or composite materials. Maxillofacial problems can cause a variety of malfunctions and abnormalities in the body and to handle these defects, two solutions exist, including surgical approach and non-surgical approach. In the first method, one should wait until the end of bone growth ages, and for the second, due to the need of wearing prosthesis, modifications of the prosthesis is essential as child grows. In this research a patient with cleft lip and palate was chosen and an appropriate implant was designed for him. An AFM analysis was performed to make see the stress distribution pattern. Final results show that using this method can help both patients and surgeons by improving implant-tissue contact.

The flow field downstream of a constriction can be laminar, turbulent, or transitional, depending strongly on the Reynolds number through the stenosis and the geometry of the stenosis. Not only laminar flow modeling but turbulent models such as the k-e, k-ω, LES or RANS ones are appropriate for this kind of blood flow either. Therefore, in this paper, simulation of the flow field downstream of a constriction with a new approach concentrated upon flow regime has been done. In order to achieve this goal, laminar model was used from inlet up to onset of turbulence. Turbulent model (k-ω SST) since onset of turbulence until relaminarization and finally with starting relaminarzation region, laminar model were applied. Steady axisymmetric flow simulations were accomplished on stenosis with 50 and 75% reductions in cross-sectional area at Reynolds numbers from 500 to 2000 employing a computational fluid dynamics solver, FLUENT (v6.3.17). The results were shown in the terms of axial velocity profiles, disturbance velocity, vortex length, wall shear stress and the results were compared with accepted experimental data and with CFD studies. The axial velocity profiles comparisons show that obtained results are in good agreement with the experimental measurements. Flow simulation results presented that disturbance velocity and wall shear stresses predicted by part by part simulation were moderately close to the experimental data.

Background: The effect of health status on productivity has widely been studied and discussed in literature. Valid and reliable tools are needed to evaluate the levels of health and productivity and provide detailed information, before any intervention is implemented. World Health Organization Health and Work Performance Questionnaire (HPQ) is a widely used instrument in estimating the workplace costs of health problems in terms of reduced job performance, sickness absence, and work-related accidents and injuries. Objective: To assess the reliability and validity of Persian version of HPQ in Iranian health care workers. Methods: The questionnaire was translated to Persian and back translated. 102 health care workers completed the questionnaire. Absence and sick-leave data was extracted from administrative records. Results: Factor analysis revealed acceptable validity for the questionnaire in part A (health). Cronbach's alpha was >0.73 for all scales of Parts B (work) and C (demographic). Questions targeting days of absence and sick-leave had acceptable correlation with administrative records (Pearson's r >0.75), while questions on total hours worked showed lower correlation. Conclusion: Persian version of HPQ can be considered a reliable and valid tool in Iranian health workers.

Background Antibodies against hepatitis B surface antigen (HBsAg) wane over time following hepatitis B immunisation; hence, it is unclear whether people vaccinated in three-dose or four-dose schedules of the hepatitis B vaccine are still immune when the hepatitis B surface antibody (anti-HBs) level in their body is undetectable, or lower than the level usually considered protective. This question may potentially be answered indirectly by measuring the anamnestic immune response to a booster dose of vaccine. The term 'booster' (or revaccination) refers to an additional dose of hepatitis B vaccine (HBV) given some time post-primary vaccination to induce immune memory and improve protection against hepatitis B virus (HBV) infection. Objectives To assess the benefits and harms of booster dose hepatitis B vaccination, more than five years after the primary vaccination, for preventing HBV infection in healthy individuals previously vaccinated with the hepatitis B vaccine, and with hepatitis B surface antibody (anti-HBs) levels below 10 mIU/mL. Search methods We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, conference databases, and reference lists of articles to January 2016. We also contacted authors of articles. In addition, we searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials (May 2016). Selection criteria Randomised clinical trials addressing anamnestic immune response to a booster dose of hepatitis B vaccine, more than five years after the primary vaccination, in apparently healthy participants, vaccinated in a three-dose or four-dose schedule of the hepatitis B vaccine during the primary vaccination, without receiving an additional dose or immunoglobulin. Data collection and analysis Both review authors decided if the identified studies met the inclusion criteria or not. Primary outcomes included the proportion of participants with anamnestic immune response in non-protected participants and signs of HBV infection. Secondary outcomes were the proportion of participants that developed local and systemic adverse events following a booster dose injection. We planned to report the weighted proportion with 95% confidence intervals (CIs). Main results There were no eligible randomised clinical trials fulfilling the inclusion criteria of this review. Authors' conclusions We were unable to include any randomised clinical trials on the topic; only randomised clinical trials will be able to provide an answer as to whether a booster dose vaccination is able to protect against hepatitis B infection.

Hemodialysis vascular access dysfunction is still considered as a major cause of morbidity and mortality in hemodialysis patients. The most common cause of this vascular access dysfunction is venous stenosis secondary to the progression of venous intimal hyperplasia at the graft-vein junction or in the draining vein. The geometry of the vessels and the local hemodynamics are believed to be contributory factors in the development of intimal hyperplasia. In the present study, the hemodynamic parameters in two types of vascular access grafts of different diameters: 6 mm and 8 mm tapered to 6 mm at the arterial site were compared. A three-dimensional CFD model was developed to simulate blood flow in the two graft types. The boundary conditions applied were a pulsatile velocity waveform at the arterial inlet and a pulsatile pressure waveform at the venous outlet. Computational fluid dynamics software was used to solve the time dependent Navier-Stokes equations under physiological conditions in both graft types. Since the cross section area and the diameter of the venous side of the tapered graft are larger than those of the straight one, the flow aligns well with the vein downstream of the graft and hence the smaller vortices are generated. Comparing the parameters at the two venous anastomosis regions also indicates that in spite of the higher flow rate in 6–8 mm tapered graft, the velocity and the wall shear stress values are lower than the values of the 6 mm straight graft.Copyright © 2010 by ASME

Hemodialysis vascular access failure considered as a primary cause of morbidity and hospital admissions for chronic hemodialysis patients. Clearly the hemodynamics within a vascular access graft and also the anastomotic geometry induced disturbed flow patterns have a substantial influence on the initiation and development of “intimal hyperplasia” the most common cause of vascular access failures. The present study is intended to investigate and compare the hemodynamics in two types of hemodialysis vascular access grafts of different diameters: 6 mm straight versus 8 mm tapered to 6 mm at the arterial site in an upper arm brachio-axillary prosthetic graft in straight configuration. Using a three-dimensional CFD model of an upper arm straight vascular access graft the two graft types have been compared in terms of overall flow pattern, wall shear stress distribution and other hemodynamic parameters. The boundary conditions applied are a physiological pulsatile velocity waveform at the arterial inlet and a pulsatile pressure waveform at the venous outlet. Results show higher values of wall shear stresses at the arterial amastomosis region of the 6-8 mm tapered graft over its 6 mm straight graft counterpart. Comparing the parameters at the two venous anastomosis regions indicates that in spite of the higher flow rate in 6-8 mm tapered graft, the velocity and the wall shear stress values are lower than the values of the 6 mm straight graft. The larger diameter and hence the larger venous anastomotic length of the tapered 6-8 mm graft let the flow align well with the vein downstream of the graft with less perturbation and thereby smaller the vortices generated and lower the wall shear stress values at the vein floor opposite to the graft outflow in comparison with the straight 6 mm graft.

Each year, something about 1 million skeletal defects are reported which are in need of bone-grafting to be cured. In both US and EU, the population is getting older and so the probability of bone fractures is increased, while dealing with this would have lots of social and economical effects. Bone grafts can be both autologous and autogenous or as an alternative, be made of metals, polymers, ceramics or composite materials. In the maxillofacial problems, which can cause more than 300 malfunctions and malformations in the body, such as dental abnormalities, nasal (and so breath) problems, digesting problems (chewing and swallowing), problems in speech and hear, problems dealing with beauty and emotions, and also economical problems. To handle these, two solutions exist, including surgical approach and non-surgical approach. In the first method, one should wait until the end of bone growth ages, and for the second, due to the need of wearing prosthesis, modifications of the prosthesis is essential as child grows.

Adjusting the rhythm of breath is one of the important parameters that a successful athlete must consider. In this paper, the relationship between man's activity and respiration rhythm is studied. A numerical simulation is carried out on a 2D axi-symmetric model using computational fluid dynamics (CFD) method. The model considers the oxygen uptake in the pulmonary capillaries in alveolar microcirculation system. The model consists of three main parts: a stationary capillary membrane, a moving plasma region and four semi-circular-shaped RBCs. Results show an inverse relationship between saturation time of RBCs and respiration rhythm. Using an inversion factor, a relationship is presented to assess the proper respiration rhythm for different exercise states.

This paper presents design and characterization of a MEMS comb accelerometer designated for integration into surgical probe to detect tissue hardness during cataract removal surgery. It helps the surgeon to avoid rupturing posterior lens capsule which if occurs leads to severe complications such as glaucoma, infection, or even blindness. The microsensor having overall dimensions of 480 ?m × 395 ?m consisted of 41 pairs of comb fingers on each side plus suspension springs, inertial mass and support anchors. Its ability to deliver significant capacitance variations during encountered vibration situations makes it capable to distinguish between different types of tissue. Integration of electronic components on chip ensures high level of reliability and noise immunity while minimizes space and power requirements. Physical characteristics and results on performance testing, proves integration of microsensor as an effective tool to aid the surgeon during the surgery.

To determine the incidence and risk factors of retinopathy of prematurity (ROP) in premature infants referred to a tertiary eye hospital during 2003-7 to provide preliminary evidence about ROP in Iran.In a cross-sectional study, data for premature infants screened for ROP in Farabi Eye Hospital including possible risk factors and eye exams' results were recorded and analysed using chi(2), univariate and multiple regressions. Severe ROP was defined as ROP needing treatment or stage 4 or 5 of ROP.Among 953 premature infants, there were 329 (34.5%) different stages of ROP. Severe ROP was seen in 22.6% (215/953) of infants (16.5%: treatable, 6.1%: advanced untreatable). The mean gestational age (GA) and birth weight (BW) of infants with severe ROP were 28.8 (SD 2.4) weeks and 1256 (389) g respectively. Univariate analysis showed a significant relation between GA, BW, oxygen therapy, blood transfusion and ROP (p0.001), while multiple-regression methods showed GA, BW and oxygen therapy as independent predictors of ROP (p0.001, 0.019 and 0.033, respectively).The authors observed a relatively high incidence of ROP in this series, especially its severe form affecting relatively more mature infants, which merits further investigation. GA, BW and oxygen therapy were independent ROP determinants.

This paper presents design and characterization of a microaccelerometer designated for integration into cataract surgical probe to detect hardness of different eye tissues during cataract surgery. Soft posterior lens capsule of eye can be easily damaged in comparison with hard opaque lens since the surgeon can not see directly behind cutting needle during the surgery. Presence of microsensor helps the surgeon to avoid rupturing posterior lens capsule which if occurs leads to severe complications such as glaucoma, infection, or even blindness. The microsensor having overall dimensions of 480 μm x 395 μm is able to deliver significant capacitance variations during encountered vibration situations which makes it capable to distinguish between different types of tissue. Integration of electronic components on chip ensures high level of reliability and noise immunity while minimizes space and power requirements. Physical characteristics and results on performance testing, proves integration of microsensor as an effective tool to aid the surgeon during this procedure., {"references":["Polla, D. L., Erdman, A. G., Robbins, W. P., Markus, D. T., Diaz-Diaz,\nJ., Rizq, R., Nam, Y.,Brickner, H.T., Krulevitch, P., and Wang, A.,\n2000, \"Microdevices in Medicine\", Ann Rev of Biomed Eng, 2:552-572.","Optikon \"Pulsar2 minimal stress\" series, Optikon Inc, Available:\nhttp://www.optikon.com","Alcon Inc, Available: http://www.alcon.com , Bausch & Lomb Inc,\nAvailable: http://www.bausch.com","C. F. Breads, Structural Vibration: Analysis and Damping, New York:\nJohn Willy & Sons Inc, 1996, pp. 47-52.","Lobontiu, N. O., Mechanical Design of Microresonators, New York:\nMcGraw HILL, 2004, pp. 3-22.","J. B. Starr, \"Squeeze-film damping in solid-state accelerometers\",\nTechnical Digest, IEEE Solid State Sensor and Actuator Workshop,\n1990, pp. 44-47.","T. W. Roszhart, \"The effect of thermoelastic internal friction on the Q\nof micromachined silicon resonators\", Technical Digest on Solid-State\nSensor and Actuator Workshop, 1990, pp. 13-16.","X. Zhang and W. C. Tang, \"Viscous Air Damping in Laterally Driven\nMicroresonators,\" Sensors and Materials, v. 7, no. 6, 1995, pp.415-430.","A. N. Cleland, and M. L. Rourkes, \"Noise processes in nanomechanical\nResonators\", Journal of Applied Physics, 92(5), 2002, pp. 2758-2769."]}

Undesired bone heating during ultrasound surgery is one of the operation constraints decreasing the treatment efficacy. Through choosing appropriate transducer geometry, one may be able to decrease the generated temperature at the bone and in the beam path. In this study, the considered model consisted of a transducer, an intervening tissue and a bone located past the tissue. By applying finite element method the Helmholtz and Bioheat equations were solved to calculate, respectively, the pressure field and the temperature generated throughout the tissue and the bone. The sample target in the model was located at a depth of 2cm and a distance of 4cm off the bone. Several transducer geometries were considered with the radius of curvature ranging from 4cm to 15cm and diameters of 6cm to 30cm. All the simulations were done for transducers at an operating frequency of 500 KHz. The pressure at the surface of each transducer was given so as to produce a constant maximum focal pressure of 2.5 MPa for each case. The simulations were terminated after each case reached 56 degrees Centigrade (at this temperature there is only one second needed to tissue to undergo necrosis). Results demonstrated that the final generated temperature at the post target bone is very sensitive to the value of the radius of curvature as well as the diameter. These two factors were considered simultaneously by using the focal number (R/d). It was seen that through adjusting the focal number to smaller possible values, we are capable of reducing the bone heating to great extents even in transducers with small diameters. This can also trim the necessary acoustic window size. For the best class of transducer geometries, the temperature generated at the post target bone was reduced by as much as 12 degrees Centigrade in our simulations.

In this paper, the finite-element method (FEM) simulation of ultrasound brain surgery is presented. The overheating problem of the post-target bone, which is one of the limiting factors for a successful ultrasound brain surgery, is considered. In order to decrease bone heating, precise choices of frequency, focal pressure, and scanning path are needed. The effect of variations in the mentioned scanning parameters is studied by means of the FEM. The resulting pressure and temperature distributions of a transdural ultrasound brain surgery are simulated by employing the FEM for solving the Helmholtz and bioheat equations in the context of a two-dimensional MRI-based brain model. Our results show that for a suitable value of the frequency, an increase in focal pressure leads to a decrease in the required duration of the treatment and is associated with less heating of the surrounding normal tissue. In addition, it is shown that at a threshold focal pressure, the target temperature reaches toxic levels whereas the temperature rise in the bone is minimal. Wave reflections from sinus cavities, which result in constructive interference with the incoming waves, are one of the reasons for overheating of the bone and can be avoided by choosing a suitable scanning path.