The comparison of ultrasonic and orbscan corneal pachymetry in corneal thickness measurement in the patients referred to Aban eye clinic, Isfahan

زمینه و هدف: با افزایش جراحی های لیزری در اصلاح عیوب انکساری و اهمیت اندازه گیری ضخامت قرنیه قبل از انجام اعمال جراحی اصلاح عیوب انکساری چشم، تعیین دقیق ضخامت قرنیه در انجام این روشها دارای اهمیت می باشد. اندازه گیری ضخامت قرنیه (Pachymetry) به دو روشOptical با استفاده از دستگاه ارب اسکن (Orbscan) و اولتراسوند (Ultrasound) انجام می شود. لذا این مطالعه برای مقایسه نتایج تعیین ضخامت قرنیه با استفاده از دو روش فوق انجام شد. روش بررسی: در یک مطالعه توصیفی - تحلیلی 324 چشم از 324 بیمار مراجعه کننده به کلینیک چشم پزشکی آبان اصفهان مورد بررسی قرار گرفت. ضخامت قرنیه با استفاده از دستگاه ارب اسکن و دستگاه Ultrasound pachymetry در هر چشم اندازه گیری شد و با استفاده از تست های آماری t-test ، t زوجی، آنالیز واریانس و آزمون همبستگی مورد تجزیه و تحلیل آماری قرار گرفت. یافته ها: میانگین و انحرف معیار ضخامت قرنیه بیماران با استفاده از دستگاه اولتراسوند 23/26±28/504 میکرون و دستگاه ارب اسکن 94/35±4/484 میکرون بدست آمد که اختلاف دو گروه از نظر آماری معنی دار می باشد (001/0

The Role of Influentials in the Diffusion of New Products

This dissertation comprises three separate essays that deal with the role of influentials in the diffusion of new products. Influentials are a small group of consumers who are likely to play an important role in the diffusion of a new product through their propensity to adopt the product early and/or their persuasive influence on others’ new product adoption decisions. The literature labels these consumers as opinion leaders, social hubs, innovators, early adopters, lead users, experts, market mavens, and boundary spanners. This dissertation integrates two perspectives that researchers have mostly studied independently: market-level, which investigates the spread of a new product (e.g., total number of products sold) across markets over time as a function of aggregate-level marketing and social parameters; and individual-level, which considers how to identify influentials and their impact on the adoption behaviors of others. The first essay reviews and integrates the literature on the role of influentials in the diffusion of new products from a marketing management perspective. The study develops a framework using the individual- and market-level research perspectives to highlight five major interrelated areas: the two theoretical bases of why influentials have a high propensity to adopt new products early and why they considerably influence others’ adoption decisions, the issues concerned with how marketers can identify influentials and effectively target them, and how significant individual-level processes lead to significant market-level behavior. The study synthesizes the relevant research findings and suggests future research directions for improving our knowledge of the role of influentials in the diffusion of new products.The second essay explores firms’ decisions regarding the selection of target consumers for seeding—providing free products to enhance the diffusion process. The study examines the profit impact of targeting five groups of potential consumers for seeding under alternative social network structures. The findings suggest that seeding programs generally increase the net present value of profits. Moreover, social hubs—the most connected consumers—offer the best seeding target under most conditions that were examined. However, under certain conditions firms can achieve comparable results through random seeding and save the resources and effort required to identify the social hubs. Finally, the interactions among several variables—the choice of seeding target, consumer social network structure, and variable seeding cost—impact the returns that seeding programs generate and the ‘optimal’ number of giveaways.The third essay explores the adverse impacts of three types of consumer resistance to new products—postponement, rejection, and opposition—on firm profits. The study investigates these effects across five groups of consumers and alternative social network structures. The findings suggest that complex interactions between three groups of parameters—resistance, consumer social network, and diffusion parameters—affect the relationship between resistance and profits. Moreover, opposition reduces firm profits to a degree that is significantly greater than rejection and postponement. Finally, influential resister groups generally have stronger adverse impacts on profits than do randomly designated resisters

Socio-hydrology from Local to Large Scales: An Agent-based Modeling Approach

For decades, the interaction between water and people has attracted hydrologists’ attention. However, the coevolution of social and natural processes, which occurs across a range of time scales, has not yet been adequately characterized. This research gap has motivated more research in recent years under the umbrella of “socio-hydrology”. The purpose of socio-hydrology is to posit the endogeneity of humans in a hydrological system and then to investigate feedback mechanisms between hydrological and human systems that might lead to emergent phenomena. The current state-of-the-art in socio-hydrology faces several challenges that include (1) a tenuous connection of socio-hydrology to broader research on social, economic, and policy aspects of water resources, (2) the (in)capability of socio-hydrological models to capture human behavior by generic feedback mechanisms that can be extrapolated to other places, and (3) unsatisfying calibration or validation processes in modeling. To address the first gap, a socio-hydrology study needs to connect proper social theories on water-related human decision making with a water resource model based on a given context and scale. Addressing the second gap calls for socio-hydrology research with case studies in different and contrasting regions and at different scales. In fact, such study can shed light on the similarities and differences in socio-hydrological systems in different contexts and scales as initial steps for future research. The third research gap calls for a socio-hydrology study that improves calibration and validation processes. Thus, to address all these gaps in one thesis, two case studies with completely different environments are chosen to investigate various phenomena at different scales. The research presented here contributes to socio-hydrological understanding at two spatial scales. To account for the heterogeneity of human decision making and its interactions with the hydrologic system, an agent-based modeling (ABM) approach is used in this research. The first objective is to explore human adaptation to drought as well as the subsequent expected or unexpected effects on the agricultural sector and to develop a socio-hydrological model to predict agricultural water demand. To do so, an agent-based agricultural water demand model (ABAD) is developed. This model is applied to the Bow River Basin in Alberta, Canada, as a study region, which has recently experienced drought periods. The second objective is to explore conflict-and-cooperation processes in transboundary rivers as socio-hydrological phenomena at a large scale. The Eastern Nile Basin Socio-hydrological (ENSH) model is developed and applied to the Eastern Nile Basin (ENB) in Africa in which conflict-and-cooperation dynamics can be seen among Egypt, Sudan, and Ethiopia. The ENSH model aims to quantify and simulate these countries’ willingness to cooperate in the ENB. ABAD demonstrates (1) how farmers’ attitudes toward profits, risk aversion, environmental protection, social interaction, and irrigation expansion explain the dynamics of the water demand and (2) how the conservation program may paradoxically lead to the rebound phenomenon whereby the water demand may increase after decreasing through modernized irrigation systems. Through the ABAD model analysis, economic factors are found to dominantly control possible rebounds. Based on the insights gained via the model analysis, it is discussed that several strategies, including community participation and water restrictions, can be adopted to avoid the rebound phenomenon in irrigation systems. Fostering farmers’ awareness about the average water use in their community could be a means to avoid the rebound phenomenon through community participation. Also, another strategy to avoid the rebound phenomenon could be to reassign water allocations to reduce farmers’ water rights. The ENSH model showed that (1) socio-political factors (i.e., relative political stability and foreign direct investment) can explain two historical trends (i.e., (a) fluctuations in Ethiopia’s willingness to cooperate between 1983 and 2009 and (b) a decreasing Ethiopia’s willingness to cooperate between 2009 and 2016); (2) the 2008 food crisis (i.e., Sudan’s food gap) may account for Sudan recovering its willingness to cooperate; and (3) Egypt’s political (in)stability plays a role in its willingness to cooperate. The outcomes of this research can provide valuable insights to support policymakers for the long-term sustainability of water planning. This research investigates two main socio-hydrological phenomena at different spatial scales: the agricultural rebound phenomenon at a small geographical scale and the conflict and cooperation phenomena at a large geographical scale. The emergence of these phenomena can be a complex resultant of interaction and feedback mechanisms between the social system at the individual, institutional, and society levels and the hydrological system. Through developing quantitative socio-hydrological models, this research investigates the feedback mechanisms that may lead to the rebound phenomenon at a small scale and the conflict and cooperation phenomenon at a large scale. Finally, the research shows how these socio-hydrological models can be used for sustainable water management to avoid negative long-term consequences

Refractive and Aberration Outcomes After Customized Photorefractive Keratectomy in Comparison With Customized Femtosecond Laser

To compare the refractive and visual outcomes and higher order aberrations in patients with low to moderate myopia who underwent customized photorefractive keratectomy (PRK) or  femtosecond laser in situ keratomileusis (Femto-LASIK) this study performed This research includes data of 120 consecutive eyes of 60 patients with myopia between -3.00 D and -7.00 D with or without astigmatism in two surgery groups: PRK and Femto-LASIK. Refractive, visual, and aberration outcomes of the two methods of surgery were compared after 6 months of follow-up. After 6 months of follow-up, sphere and cylinder were found significantly decreased and there was no statistically significant difference between the two groups. The mean of uncorrected distance visual acuity in LogMar format for the PRK and Femto-LASIK groups was -0.03±0.07 and -0.01±0.08, respectively, which was not significantly different between the two groups. Higher orders and spherical aberrations increased in both groups significantly, while total aberrations decreased in both groups. After surgery, no differences were observed between the two groups in the amount of aberrations. Both PRK and Femto-LASIK are effective and safe in correcting myopia. In this study PRK induced more spherical and higher order aberrations than Femto-LASIK

The Numerical and Approximate Analytical Solution of Parabolic Partial Differential Equations with Nonlocal Boundary Conditions

Many scientific and engineering problems can be modeled by parabolic partial differential equations with nonlocal boundary conditions. Examples of such problems can be found in chemical diffusion, thermoelasticity, heat conduction processes, nuclear reactor dynamics, inverse problems, control theory and so forth. In the last two decades, the development of numerical and approximate analytical techniques to solve these equations has been an important area of research due to the need to better understand the underlying physical phenomena

Visual outcomes of Femto-LASIK for correction of residual refractive error after corneal graft

To evaluate the outcomes of the Femto-LASIK method in the treatment of refractive errors following penetrating keratoplasty (PK) at the Persian Eye Clinic, Isfahan, Iran In a prospective, non-comparative case series, 34 consecutive symptomatic eyes of 34 patients after corneal graft, were operated on. Tissue-saving (TS) Femto-LASIK (n = 16), and Zyoptix Personalized Treatment Advanced (PTA) Femto-LASIK (n = 18) were performed using the Bausch & Lomb Technolas 217z excimer laser and Zyoptic algorithm. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, contrast sensitivity, and HOAs were evaluated preoperatively and 12 months after enhancement treatment. At 12 months, the mean preoperative myopic spherical equivalent refraction (SE) decreased from -6.50 +/- 2.8 D to -1.6 +/- 1.8 D, and mean hyperopic SE from +3.2 +/- 2.20 D to 0.37 +/- 1.2 D. The safety index was 1.42 (1.2 in the TS group and 1.5 in the PTA group). In the TS group, 100 % of eyes achieved 20/80 or better UCVA and 50 %, 20/40 or better and in the PTA group, 100 % of eyes achieved 20/80 or better UCVA and 77.7 %, 20/40 or better. The efficacy index was 1.08 (0.9 in TS group and 1.21 in the PTA group). Patients obtained statistically significant lower values of root mean square (RMS) of HOAs with spherical aberrations (p < 0.05). Femto-LASIK method with Zyoptic programs after PK was safe, effective, and predictable for correction of spherical and cylindrical components of the refractive error

Visual outcomes of topography-guided excimer laser surgery for treatment of patients with irregular astigmatism

The aim of this study was to evaluate the efficacy, safety, and predictability of topography-guided treatments to enhance refractive status following other corneal surgical procedures. In a prospective case series study, 28 consecutive eyes of 26 patients with irregular astigmatism after radial keratotomy, corneal transplant, small hyperopic and myopic excimer laser optical zones, and corneal scars were operated. Laser-assisted in situ keratomileusis (LASIK) (n = 8) and photorefractive keratectomy (PRK) (n = 20) were performed using the ALLEGRETTO WAVE excimer laser and topography-guided customized ablation treatment software. Preoperative and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest and cycloplegic refraction, and corneal topography with asphericity were analyzed in 12 months follow-up. Uncorrected visual acuity (UCVA) changed from 0.2 +/- 0.2 or (20/100 +/- 20/100) to 0.51 +/- 0.31 or (20/40 +/- 20/60) in the LASIK group (P = 0.01) and from 0.34 +/- 0.16 or (20/60 +/- 20/120) to 0.5 +/- 0.23 or (20/40 +/- 20/80) in the PRK group (P = 0.01). Refractive cylinder decreased from -3.2 +/- 0.84 diopters (D) to -2.06 +/- 0.42 D in the LASIK group (P = 0.07) and from -2.25 +/- 0.39 D to -1.5 +/- 0.23 D in the PRK group (P = 0.008). Best corrected visual acuity did not change significantly in either group. Topography-guided treatment is effective in correcting the irregular astigmatism after refractive surgery. Topography-guided PRK can significantly reduce irregular astigmatism and increase the UCVA and BCVA

On the Convergence of the Homotopy Analysis Method for Inner-Resonance of Tangent Nonlinear Cushioning Packaging System with Critical Components

Homotopy analysis method (HAM) is applied to obtain the approximate solution of inner-resonance of tangent cushioning packaging system based on critical components. The solution is obtained in the form of infinite series with components which can be easily calculated. Using a convergence-control parameter, the HAM utilizes a simple method to adjust and control the convergence region of the infinite series solution. The obtained results show that the HAM is a very accurate technique to obtain the approximate solution

Detecting enteropathogenic Campylobacters in chicken feces by PCR and comparing with culture method

امروزه کامپیلوباکترها از شایع ترین علل اسهال های باکتریایی در سرتاسر جهان محسوب می شوند. در جنس کامپیلوباکتر 18 گونه و تحت گونه وجود دارد که گونه های Campylobacter jejuni و Campylobacter coli مسبب اکثر عفونت های انسانی ناشی از کامپیلوباکترها می باشند و مهم ترین بیماری آنها نیز اسهال می باشد. بیماری در انسان متعاقب مصرف آب و مواد غذایی بویژه گوشت ماکیان رخ می دهد. تشخیص باکتریولوژیک این باکتری با دشواری زیادی از قبیل طولانی بودن مدت انکوباسیون و محدودیت تست های افتراقی همراه است. بنابراین استفاده از روش های دیگر تشخیصی امروزه مورد توجه قرار گرفته است. تعداد 116 نمونه رکتال سواپ از مرغ های موجود در مرغداری های شهر اصفهان گرفته شده و پس از 18-12 ساعت غنی سازی در محیط Campy-Thio، در محیط اختصاصی Campylobacter selective agar کشت شدند. برای شناسایی و تعیین گونه ها از رنگ آمیزی گرم و تست های اکسیداز، کاتالاز، هیدرولیز هیپورات و سنجش حساسیت به نالیدیسیک اسید و سفالوتین استفاده شد. جهت استخراج DNA از کیت های اختصاصی استفاده شد و با استفاده از پرایمرهای ویژه گونه های ژژونی و کلی اقدام به انجام PCR (Palymeras Chain Reaction) گردید. نتیجه کشت در 11 مورد مثبت بود (5/9) که از این تعداد 8 مورد مربوط به گونه ژژونی و 3 مورد مربوط به گونه کلی بود. نتیجه PCR نمـونه هـا در 27 مـورد مثـبت بود (2/23) که از این تعداد 18 مورد مربوط به گونه ژژونی و 9 مورد مربوط به گونه کلی بود. حساسیت و ویژگی روش PCR در مقایسه با روش کشت بترتیب 100 و 7/84 درصد بود. روش PCR مورد استفاده در این تحقیق قادر به شناسایی تمام نمونه های کشت مثبت بود و نتایج تعیین گونه با این روش تطابق کاملی با روش بیوشیمیایی داشت. بنابراین با توجه به دقت بالا و سرعت زیاد به نظر می رسد روش PCR جایگزین مناسبی جهت کشت در تشخیص کامپیلوباکترها در نمونه های مرغ ها باشد

Effect of iris registration on outcomes of FEMTOLASIK for myopia and myopic astigmatism.

PURPOSE To compare the visual and refractive outcomes after FEMTOLASIK with and without iris registration. METHODS In this randomized, prospective, comparative, contralateral eye study, 118 eyes of 59 patients with myopia and myopic astigmatism underwent LASIK using the Femto LDV femtosecond laser (160 µm) and the MEL80 with or without iris registration. For each patient, iris registration FEMTOLASIK was performed on one eye and non-iris registration FEMTOLASIK was performed on the other eye, assigned at random. Patients were evaluated before and 12 months. Uncorrected visual acuity, best-corrected visual acuity, manifest refraction, contrast sensitivity, and higher-order aberrations (HOAs) were evaluated. RESULTS At 12 months, the mean UDVA was 0.002 ± 0.07 logMAR (20/19) in iris registration eyes and 0.00 ± 0.06 logMAR (20/24) in non-iris registration eyes (P = 0.9). 61% of iris registration eyes and 71.2% of non-iris registration eyes achieved a UDVA of 20/20 or better (P = 0.31); 98.3% of eyes with the iris registration FEMTOLASIK and 94.9% with the non-iris registration FEMTOLASIK were within ±0.50 D from emmetropia (P = 0.71). No statistically significant difference was found in postoperative contrast sensitivity between groups at 3, 6, 12, or 18 cycles/degree (P > 0.05). There was significant increase in total HOA root mean square in two groups. The mean error magnitude of surgically induced astigmatism 12 months postoperatively was -0.33 in iris registration eyes and -0.24 in the non-iris registration eyes (P = 0.36). CONCLUSIONS FEMTOLASIK with and without iris registration provides similar results in myopic and myopic astigmatism patients