Sensitivity analysis of natural convection in a porous cavity filled with nanofluid and equipped with horizontal fins using various optimization methods and MRT-LB.

In the present study, natural convection heat transfer is investigated in a porous cavity filled with Cu/water nanofluid and equipped with horizontal fins. Optimization and sensitivity analysis of the fin's geometry, porous medium and nanofluid properties to maximize heat transfer rate is the aim of this work. To achieve this purpose, a design space is created by input parameters which include length, number of fins, distance between fins, porosity, Darcy number and volumetric fraction of the nanoparticles. Several tools have been used to implement optimization methods including the Taguchi method (TM) for design points generation, sensitivity analysis of design variables by using signal-to-noise ratio (SNR) and analysis of variance (ANOVA), response surface method (RSM) for interpolation and regression by using nonparametric regression, and genetic algorithm (GA) for finding optimum design point. The double multi-relaxation time lattice Boltzmann method (MRT-LBM) is used to analyze and simulate the flow field and heat transfer in each design point. The results show that the optimal configuration leads to an average Nusselt number of 5.56. This optimal configuration is at the length of fins L/2, the number of fins 2, the distance between fins L/12, porosity 0.8, Darcy number 0.1, and the volumetric fraction of the nanoparticles 0.02. By using the SNR results, the Darcy number and the number of fins have the most and the least effect in maximizing the average Nusselt number, respectively. The ANOVA results and global sensitivity analysis (GSA) findings further validated this conclusion.

Experimental study on inlet turbulent flow under ultrasonic vibration: Pressure drop and heat transfer enhancement.

This experimental study examines the impact of ultrasonic vibration on pressure drop and heat transfer enhancement of inlet turbulent flows. A stainless steel tube connected to an ultrasonic transducer and immersed in a constant temperature two-phase fluid was considered as the test section. Regarding the designed configuration, the ultrasonic transducer utilized had an acoustic frequency of 28 kHz and two different power levels of 75 W and 100 W. The experiments were conducted for different ultrasonic power levels, inlet temperatures, and flow rates. The accuracy of measurements was successfully validated via the existing empirical correlations. The results indicate that the effect of ultrasonic vibration on pressure drop and heat transfer enhancement diminishes with the growth of both Reynolds number and inlet temperature. Based on previously reported results on inlet flows with a laminar flow regime, the effect of ultrasonic vibration is very trivial in current turbulent inlet flows (up to 7.28% for heat convection enhancement). The results of the present study will be beneficial for future investigations on designing vibrating heat exchangers.

Safe sex norm questionnaire for female sex workers: development and validation study in Iran.

OBJECTIVES: The aim of the present study was to develop and validate a safe sex norm questionnaire as an appropriate instrument which would be adaptable to the female sex worker (FSW) population. STUDY DESIGN: A mixed method study. METHODS: Appropriate content was prepared through a literature review. Content validation indices were assessed using interviews with content experts and lay experts. A conservative approach was used to assess the inter-rater agreement among the participants about the instrument relevance and clarity. The scale content validity index was computed using the average method. Non-parametric Mokken scale analysis was used for assessing scalability and unidimensionality of the questionnaire in a sample of 170 FSWs in Tehran. To evaluate the reliability and internal consistency of the questionnaire intra-class correlation and Cronbach's alpha were employed. RESULTS: A list of 34 items was finalized, with subscales for actual behavioral norms and for perceived norms. The relevance of the actual and perceived norms subscales in the final questionnaire was higher than 96%; clarity of the subtests was 99% and higher. The comprehensiveness of the actual and perceived norms subscales was 85% for both. Mokken scale analysis showed that the two subscales were distinct constructs, and all items are good indicators for the constructs. CONCLUSION: Our findings support that the safe sex norm questionnaire is a valid and reliable measure that would be useful to harm reduction programs and help effective HIV prevention among female sex workers.

Effect of socio-economic status, family smoking and mental health through social network on the substance use potential in adolescents: a mediation analysis.

OBJECTIVES: Understanding pathways that influence substance use potential (SUP) can help with effective substance use prevention interventions among adolescents. The aim of the present study is to contribute to a better understanding of the SUP of adolescents by examining the mediating role of social network quality in the SUP of Iranian adolescents. STUDY DESIGN: A cross-sectional study. METHODS: Structural equation modeling was conducted to assess the hypothesized model that social network quality would mediate the association of family socio-economic status, a mental health disorder, and family smoking with addiction potential. RESULTS: The model shows a good fit to the data. Social network quality mediated the effect of family smoking on the SUP for boys. A mental health disorder had a positive significant direct effect on addiction potential for both girls and boys. CONCLUSIONS: Social network quality mediates the effect of family smoking on boys' addiction potential in the context of Iran. Educational programs based on local societal ways and cultural norms are recommended to change tobacco smoking behavior among family members. In addition, to prevent subsequent substance use among adolescents, more effort is needed to improve their mental health.

Computational fluid dynamics (CFD) simulation of a newly designed passive particle sampler.

In this work a series of computational fluid dynamics (CFD) simulations were performed to predict the deposition of particles on a newly designed passive dry deposition (Pas-DD) sampler. The sampler uses a parallel plate design and a conventional polyurethane foam (PUF) disk as the deposition surface. The deposition of particles with sizes between 0.5 and 10 µm was investigated for two different geometries of the Pas-DD sampler for different wind speeds and various angles of attack. To evaluate the mean flow field, the k-ɛ turbulence model was used and turbulent fluctuating velocities were generated using the discrete random walk (DRW) model. The CFD software ANSYS-FLUENT was used for performing the numerical simulations. It was found that the deposition velocity increased with particle size or wind speed. The modeled deposition velocities were in general agreement with the experimental measurements and they increased when flow entered the sampler with a non-zero angle of attack. The particle-size dependent deposition velocity was also dependent on the geometry of the leading edge of the sampler; deposition velocities were more dependent on particle size and wind speeds for the sampler without the bend in the leading edge of the deposition plate, compared to a flat plate design. Foam roughness was also found to have a small impact on particle deposition.

Association of Maternal Working Condition with Low Birth Weight: The Social Determinants of Health Approach.

BACKGROUND: The socioeconomic conditions have made more job opportunities available to women. This has created interest to conduct studies on the effect of working lifestyle on pregnancy outcomes. AIM: This study was conducted with the aim to assess the relationship between mothers' working status as a social determinant and the incidence of low birth weight (LBW) of the newborn. SUBJECTS AND METHODS: This case-control study was conducted on 500 women with normal weight infants (control group) and 250 women with LBW infants (case group) in selected hospitals in Tehran. Data were collected using a researcher-made questionnaire, designed to assess the effect of mothers' prenatal lifestyle, as a social determinant, on LBW of the newborn. A section of the questionnaire involved assessment of mother's working condition in terms of the work environment, activities, and job satisfaction. Data were analyzed using Chi-square and logistic regression tests. RESULTS: LBW among employed mothers was 5 times more likely than unemployed ones (odds ratio = 5.35, P < 0.001). Unfavorable work conditions such as humid environment, contact with detergents, and being in one standing or sitting position for long hours were significantly associated with LBW (P < 0.001). CONCLUSION: The present study showed that unfavorable work conditions were associated with LBW; therefore, they need special attention.

Financial performance of the teaching pharmacies in Isfahan: an economic evaluation.

Teaching pharmacies are amongst the important cornerstones of a healthcare system for drug supplying, pharmacy education and pharmacy practice research. Assessment of the Iranian healthcare system costs shows that after personnel charges, drug outlay is the second expensive factor. This great financial mass requires integral audit and management in order to provide costumers satisfaction in addition to financial viability. Teaching pharmacies are required to realize financial viability as well as providing several educational and drug servicing goals, which makes microeconomic analysis important. The aim of this study was to evaluate the financial performance of the teaching pharmacies affiliated with the Isfahan University of Medical Sciences (with the abrreviated names as: SHM, ISJ, AZH for the confidentialiy of the financial data). This is a descriptive and cross-sectional study done in 2008. The target pharmacies of this study were all the 3 teaching pharmacies affiliated with the Isfahan University of Medical Sciences. The data collecting template was prepared using the standard scientific methods according to the goals of this research The goals also nominated necessary items needed in economic profit evaluation. The data collection template was completed by reference to the teaching pharmacies financial documents and reports, used as a base for calculating the total income and the total costs in 2007-2008 financial year. The difference between these two balances showed the value of profits or loss. The profit/cost ratio was also calculated, using the proportion of the total income to the total costs. The collected data was statistically analyzed using the Excel software (Microsoft 2007). For the financial year 2007-2008, the difference between the total income and the total costs was -831.6 million Rials (excess costs to income) for the SHM pharmacy, + 25.4 billion Rials for the ISJ pharmacy and -429.5 million Rials for the AZH pharmacy. According to our findings there is a strong requirement to improve the financial performance of all the three teaching pharmacies while maintaining a high standardard of teaching and educational affairs.

Outcomes of surgical (pars plicata and limbal lensectomy, vitrectomy) and non-surgical management of persistent fetal vasculature (PFV): an analysis of 54 eyes.

PURPOSE: To identify clinical characteristics associated with outcomes of treatment for persistent fetal vasculature (PFV based on a modified classification. METHODS: In this noncomparative case series, 54 eyes of 47 consecutive patients with PFV managed from 1981 until 1998 at a tertiary eye hospital were reviewed. Pars plicata lensectomy and vitrectomy was performed in 34 eyes and translimbal lensectomy and vitrectomy in five. Fifteen eyes were managed non-surgically. The following outcomes were measured: 1) "Visual improvement", defined as at least one Zipf's category improvement of best corrected final vision as compared with initial visual acuity, provided that final vision of CSUM (central, steady, unmaintained) equal to 20/100-20/30 was obtained. 2) "Cosmetic acceptability", defined as the absence of the following: small orbit, externally small appearing eye with microcornea and hypotony, eye deviation more than 35 prism diopters without strabismus surgery and corneal opacity. RESULTS: Six eyes were inoperable. In 10 out of 33 operated eyes (30.3%) improvement of vision was obtained including four eyes with an anterior form and six eyes with a combined form of PFV. In univariate analysis, factors such as anterior form of PFV surgery in the combined form and having a normal retina, had a weak association with a higher chance of visual improvement. In multivariate regression analysis the likelihood of unacceptable cosmetic appearance was higher in females than males (OR = 10.5), and in bilateral cases (OR = 7.9). Offspring of consanguineous marriages had more severe forms of PFV. CONCLUSIONS: Although visual potential is limited in PFV some eyes with an anterior or combined form and normal retina achieved improvement of visual acuity after surgery. However, statistically no single factor except sex and bilateral PFV (for cosmetic unacceptability) reliably predicted the results of treatment. Therapy should be individualized based on clinical findings. Genetic studies in offspring of consanguineous marriages with PFV may prove informative.

Factors influencing anatomic and visual results in primary scleral buckling.

PURPOSE: To identify the factors influencing anatomical and visual results in cases of rhegmatogenous retinal detachment undergoing primary scleral buckling. METHODS: A retrospective study of 233 eyes of 226 patients was done. The data were evaluated by univariate analysis and stepwise logistic regression analysis. RESULTS: Retinal reattachment was achieved with primary scleral buckling in 197 eyes (84.5%). The extent of retinal detachment, preoperative proliferative vitreoretinopathy (PVR), preoperative visual acuity and relative afferent pupillary defects were identified as influencing anatomical results, by univariate analysis. The predictive roles of extent of retinal detachment (P<0.0001) and preoperative PVR (P=0.0085) were shown to be significant by step-wise logistic regression. As well as the above factors, the patient's age, the duration of symptoms and the status of the macula were predictors of visual results, by univariate analysis. Stepwise logistic regression analysis confirmed the predictive roles of preoperative visual acuity (P<0.0001) and the extent of retinal detachment (P=0.0089). CONCLUSIONS: Cases with a larger extent of retinal detachment, more advanced preoperative PVR and poorer preoperative visual acuity have less favorable anatomical and functional results.

A one-stage, versatile procedure: intact-bridge mastoidectomy.

Patients who have never had otologic surgery or whose previous surgery has preserved the bridge or canal wall can undergo an intact-bridge mastoidectomy. The intact-bridge mastoidectomy can achieve the advantages of improved hearing (as in intact-wall techniques) and eradicated cholesteatoma (as in open-cavity techniques). This article reviews the surgical techniques of intact-bridge mastoidectomy.

Thiersch skin grafting and postoperative care of otologic patients.

Postoperative care is as important as the actual surgical procedure, if not more important. Thiersch skin grafting remains an excellent technique to ensure proper healing in the mastoid cavity and ear canal. Successful surgical outcomes depend on a well-coordinated effort by the surgical team and the patient. Preoperative planning, intraoperative surgical technique, and postoperative care and follow-up are discussed in this article.

Primary capsulectomy, anterior vitrectomy, lensectomy, and posterior chamber lens implantation in children: limbal versus pars plana.

PURPOSE: To compare the results of a limbal versus a pars plana approach for primary posterior capsulectomy and anterior vitrectomy in the management of childhood cataract. SETTING: Department of Ophthalmology, Labbafinejad Medical Center, Tehran, Iran. METHODS: A randomized, controlled, double-masked clinical trial of 45 eyes was conducted. After being matched, 38 eyes were included in the study and were divided into 2 equal groups for data analysis. All eyes had lensectomy and posterior chamber intraocular lens (PC IOL) implantation. Primary posterior capsulectomy and anterior vitrectomy were performed through the limbus in half of the eyes and the pars plana in the other half. Main outcome measures included visual acuity, estimated red reflex, postsurgical inflammatory reaction, corneal clarity, posterior synechias, iris capture, IOL position, capsulectomy size, glaucoma, cystoid macular edema, retinal tear, and postoperative refraction. RESULTS: No statistically significant differences were found between the 2 approaches in the outcome measures. CONCLUSION: The anatomic and visual results were encouraging when posterior capsulectomy and anterior vitrectomy, using a limbal or pars plana approach, were combined with lensectomy and PC IOL implantation in children. The application of these techniques depends on surgeon experience and skill.

Endolymphatic sac enhancement surgery in elderly patients with Ménière's disease.

Ménière's disease is a pathologic condition of the inner ear that is characterized by vertigo, tinnitus and a progressive loss of hearing. When Ménière's disease is unresponsive to medical treatment and when destructive surgery is not advisable, patients, particularly the elderly, often benefit from endolymphatic sac enhancement, a conservative, nondestructive surgical procedure. We evaluated the outcomes of 62 such patients, aged 65 years and older, who underwent a total of 78 endolymphatic sac enhancements. We assessed their response to surgery by means of a questionnaire, which classified pre- and post-surgical data according to criteria established by the American Academy of Otolaryngology-Head and Neck Surgery. Of the 27 patients who returned questionnaires, 23 reported significant alleviation of vertigo symptoms and 19 said their hearing ability had either improved or was maintained at presurgical levels. Endolymphatic sac enhancement resulted in no mortality, and morbidity was documented in only one patient. We conclude that endolymphatic sac enhancement is a safe and viable treatment for elderly patients with Ménière's disease that is refractory to medical therapy.

Surgical management of cataract and posterior chamber intraocular lens implantation in Fuchs' heterochromic iridocyclitis.

BACKGROUND: To determine the inflammatory course and level of visual rehabilitation after cataract extraction and posterior chamber lens implantation in patients with Fuchs' heterochromic iridocyclitis complicated by cataract. METHODS: In a clinical trial, 32 eyes (visual acuity of 20/160 or worse) of 30 patients underwent extracapsular cataract extraction (19 eyes) or lensectomy (13 eyes) accompanied by posterior chamber intraocular lens implantation. Indirect ophthalmoscopy was performed intraoperatively prior to intraocular lens implantation and the extent of vitreous haze was assessed. If vitreous haziness was 3+ or more, core vitrectomy (two eyes) or three-port pars plana deep vitrectomy (four eyes) was performed. RESULTS: After an average follow up of 14.4 months (6 to 24 months), there was no statistically significant increase in cell and flare in the anterior chamber and vitreous or in keratic precipitates compared with the preoperative status of the eyes. However, 12% of the eyes developed synechiae (anterior and/or posterior) in comparison to preoperative condition (p < 0.05). Eight-seven percent of the eyes gained visual acuity of 20/40 or better (P < 0.005). Using the logistic regression model, a higher level of preoperative inflammation was associated with reduced likelihood of gaining visual acuity of 20/25 or more (OR = 0.25, 95% CI 0.049, 1.255). The complications of surgery were synechiae, 12%; opaque posterior capsule, 12%; vitreous loss, 3%; chronic glaucoma, 3%; and retinal detachment, 3%. CONCLUSIONS: Implantation of a posterior chamber intraocular lens can be well tolerated in patients with Fuchs' heterochromic iridocyclitis. Vitrectomy, whenever indicated in addition to cataract extraction, improves visual rehabilitation.

Astigmatic shift following sutureless, triplanar, curvilinear, single hinge, clear corneal incision for phacoemulsification and intraocular lens implantation.

BACKGROUND AND OBJECTIVE: Questions remain regarding wound stability, in particular astigmatism and leakage, in large, sutureless, clear corneal incisions. A polymethylmethacrylate (PMMA) implant, which may be more desirable than a silicone foldable in a very young patient, can be implanted through this incision. PATIENTS AND METHODS: Twenty eyes of 19 patients underwent a 5.2-mm, temporal approach, clear corneal, sutureless phacoemulsification with intraocular lens implantation. The Langerman single hinge technique with a curvilinear groove and a triplanar, sutureless incision was used in all cases. RESULTS: The average axis-corrected induced cylinder was 1.05 D of with-the-rule change. Stromal hydration was not done and only one eye required a single suture. CONCLUSION: A 5.2-mm, clear corneal incision was self-sealing, with an acceptable induced with-the-rule astigmatism.

Results of penetrating keratoplasty in CHED. Congenital hereditary endothelial dystrophy.

Congenital hereditary endothelial dystrophy is characterized by a diffuse bilateral corneal opacity (edema). Its inheritance has been reported to be both autosomal recessive and dominant. All our cases seemed to be autosomal recessive. There seems to be a prevalence of the recessive gene in the Iranian population. The dystrophy might be misdiagnosed as congenital glaucoma, as in several of our cases. We have operated on 37 eyes of 21 patients during the past 10 years. Our visual and anatomical success rate has been very good, with 92% clear grafts and only an 8% rejection rate, in contrast to poor prognosis that has been previously reported. In children, suture removal should be started 3 months postoperatively. Partial amblyopia was preexistent in all cases, but deep amblyopia was not common.

Bilateral penetrating keratoplasty for sclerocornea in an infant with monosomy 21. Case report and review of the literature.

An 8-month-old caucasian girl with monosomy 21 and sclerocornea underwent bilateral penetrating keratoplasties. Both light and electron microscopic studies were performed on the corneal buttons. Light microscopy revealed variable and abnormal corneal thickness with the peripheral cornea being thinner than the center, lack of Bowman's layer, irregular stromal lamellae, stromal vascularization, markedly underdeveloped or absent Descemet's membrane, and marked attenuation of the endothelium. Electron microscopy demonstrated basal epithelial cells with a thin epithelial basement membrane residing directly on stromal lamellae without intervening Bowman's layer. Stromal collagen fibrils were irregular in size measuring 38-69 nm in diameter. We believe this to be the first report of corneal transplantation and the second reported case of sclerocornea in a patient with monosomy 21.

Temporary keratoprosthesis for surgical management of complicated combined anterior and posterior segment injuries to the eye: combat- versus noncombat-injury cases.

We used a Landers-Foulks temporary keratoprosthesis lens to combine penetrating keratoplasty with vitreoretinal surgery in 21 eyes of 21 patients. Ten of these patients were victims of combat injuries; 11 had traumatic injuries unrelated to war. After a mean follow up of 11 months, satisfactory overall results, ie, an attached retina and a clear cornea, were obtained in nine eyes (42.8%). In two, the retina was attached but the corneal graft was rejected. Eight eyes achieved a visual acuity of 5/200 or better. The visual prognosis as well as the rate of retinal reattachment for the combat-injured eyes were poorer than those for the traumatic noncombat-injured eyes. At the last follow-up examination, 60% of the combat-injured eyes were considered visually lost, as compared with 36.3% of the noncombat-injured eyes.

Endolymphatic sac enhancement.

Endolymphatic sac enhancement surgery has proved, over the last several decades, to be a conservative and relatively safe procedure for patients in whom extensive empirical medical therapy has failed. The operation can usually be done as an outpatient procedure or with a one-night postoperative stay, and it has relatively low morbidity. Up to 90% of patients exhibit significant improvement of their episodic vertigo after the operation. Destructive procedures such as labyrinthectomy and vestibular neurectomy are reserved for rare cases of failure of the endolymphatic sac enhancement and are not offered to patients as a primary surgical alternative. Wide decompression of the mastoid and sigmoid sinus is of paramount importance in achieving an adequate endolymphatic sac enhancement. At the end of the operation, meticulous attention should be given to cleaning bone dust and debris from the wound and to stopping all bleeding and bony oozing. Wide opening of the posterior aditus and facial recess is usually necessary to prevent postoperative aditus block. In the postoperative period, scrupulous attention should be given to wound healing; if infection develops in the wound, aggressive antibiotic therapy should be administered to prevent labyrinthitis that could result in deafness.

Low dose cyclosporin-A therapy in Behçet's disease.

The effect of systemic low dose cyclosporin-A (5 mg/kg/day as initial dose) combined with 0.2 to 0.6 mg/kg/day prednisolone (when necessary) in clinical course of 22 patients suffering from severe forms of Behçet's disease are reviewed. All the patients had received other drugs previously and had either no response to them or developed intolerable side effects, therefore, pre treatment visual acuity (VA) was compared to post treatment VA as "self control". The average age of our patients was 30.6 years (range 19-51 years). The average duration of our therapy was 19.5 months (range 4-32 months). Improvement or stabilization of vision was achieved in 21 patients (95%). The intraocular inflammation was controlled in all of the eyes and most of the non-ocular signs and symptoms were also improved. Serious side effects included rise in creatinine in 10 (45%) of the patients, rise in bilirubin in 6 (27%) and hypertension in 1 (4.5%). These side effects disappeared as the dose of cyclosporin-A was tapered. We believe this form of therapy is of great value in the management of severe forms of Behçet's disease.