Probabilistic Bisimulations for PCTL Model Checking of Interval MDPs

Verification of PCTL properties of MDPs with convex uncertainties has been investigated recently by Puggelli et al. However, model checking algorithms typically suffer from state space explosion. In this paper, we address probabilistic bisimulation to reduce the size of such an MDPs while preserving PCTL properties it satisfies. We discuss different interpretations of uncertainty in the models which are studied in the literature and that result in two different definitions of bisimulations. We give algorithms to compute the quotients of these bisimulations in time polynomial in the size of the model and exponential in the uncertain branching. Finally, we show by a case study that large models in practice can have small branching and that a substantial state space reduction can be achieved by our approach.Comment: In Proceedings SynCoP 2014, arXiv:1403.784

A study on relationship among free cash flow, firm value and investors’ cautiousness: Evidence from Tehran Stock Exchange

Financial statements as well as financial standards are always considered as primary sources for getting rich information of firms. The standards are normally divided in two categories of economic and accounting and each of these standards shows one of the specifications of the company and has its own advantageous and disadvantageous. There are different standards, which are used for firm assessment. Therefore, a company with more gained prominences has more change to succeed in attracting credits and financing from the capital market. Under such circumstances, such a company can attract more finance and it can be sold sooner on the stock exchange. This paper tries to investigate on the free cash flow as an effective factor in specifying the real value of the business enterprises on 56 selected firms from Tehran Stock Exchange. The results of this study have disclosed that, there was a direct and meaningful relationship between free cash flow of the business enterprises and their real values. Second, the real values of the business enterprises are more than their predicted values. Finally, the predicted value of the business enterprises on the basis of the free cash flow is more than their market value

Subgroups of finite index in an additive group of a ring

If K is an infinite field and G⫅K is a subgroup of finite index in an additive group, then K∗=G∗G∗−1 where G∗ denotes the set of all invertible elements in G and G∗−1 denotes all inverses of elements of G∗. Similar results hold for various fields, division rings and rings

Outline of changes in cortisol and melatonin circadian rhythms in the security guards of Shiraz University of Medical Sciences

Background: According to the literature, a large number of people working in industries and service providing personnel, such as firefighters, physicians, and nurses are shift workers. The spread of shift working in industrial societies and the incidence of the problems resulting from shift working have caused the researchers to conduct studies on this issue. The present study also aimed to investigate melatonin and cortisol circadian rhythms in the security guards of Shiraz University of Medical Sciences, Shiraz, Iran. Methods: The present study was conducted on 20 security guards of Shiraz University of Medical Sciences. In order to collect the study data, blood samples were taken from the study subjects in different times of the day (1, 4, 7, 10, 13, 16, 19, and 22) and cortisol and melatonin levels were determined using the radioimmunoassay and enzyme immunoassay techniques, respectively. Results: The results showed that as the intensity of light increased at night, the plasma cortisol level increased, as well. Besides, no statistically significant difference was found between the plasma cortisol levels in natural light and 4500-lux light. On the other hand, a significant difference was observed between the plasma cortisol levels in natural light and 9000-lux light as well as 4500- and 9000-lux lights. The study findings also showed that as the intensity of light increased at night, the plasma melatonin level decreased. In addition, a statistically significant difference was found between the plasma melatonin levels in natural light and 4500-lux light. Nevertheless, no significant difference was observed between the plasma melatonin levels in the natural light and 9000-lux light as well as 4500- and 9000-lux lights. Conclusions: The present study aimed to investigate the subsequences of shift working in the security guards of Shiraz University of Medical Sciences and showed that occupational exposure to bright light could affect some biological markers, such as melatonin and cortisol secretion

Outline of changes in cortisol and melatonin circadian rhythms in the security guards of Shiraz University of Medical Sciences

Background: According to the literature, a large number of people working in industries and service providing personnel, such as firefighters, physicians, and nurses are shift workers. The spread of shift working in industrial societies and the incidence of the problems resulting from shift working have caused the researchers to conduct studies on this issue. The present study also aimed to investigate melatonin and cortisol circadian rhythms in the security guards of Shiraz University of Medical Sciences, Shiraz, Iran. Methods: The present study was conducted on 20 security guards of Shiraz University of Medical Sciences. In order to collect the study data, blood samples were taken from the study subjects in different times of the day (1, 4, 7, 10, 13, 16, 19, and 22) and cortisol and melatonin levels were determined using the radioimmunoassay and enzyme immunoassay techniques, respectively. Results: The results showed that as the intensity of light increased at night, the plasma cortisol level increased, as well. Besides, no statistically significant difference was found between the plasma cortisol levels in natural light and 4500-lux light. On the other hand, a significant difference was observed between the plasma cortisol levels in natural light and 9000-lux light as well as 4500- and 9000-lux lights. The study findings also showed that as the intensity of light increased at night, the plasma melatonin level decreased. In addition, a statistically significant difference was found between the plasma melatonin levels in natural light and 4500-lux light. Nevertheless, no significant difference was observed between the plasma melatonin levels in the natural light and 9000-lux light as well as 4500- and 9000-lux lights. Conclusions: The present study aimed to investigate the subsequences of shift working in the security guards of Shiraz University of Medical Sciences and showed that occupational exposure to bright light could affect some biological markers, such as melatonin and cortisol secretion

Photorefractive Keratectomy for Mild-to-Moderate Myopics with Thin Corneas: A 3-Year Follow-up Results

Background: The purpose of this study was to evaluate the 3-year visual outcomes in mild-to-moderate myopic patients with thin corneas who underwent photorefractive keratectomy (PRK) with or without mitomycin C (MMC).Methods: Thirty myopic eyes with a mean spherical equivalent (SE) of −3.76 ± 1.72 (−6.50 to −1.25) diopter (D) and a mean corneal thickness of 486.03 ± 11.93 (452-499) µm at the thinnest point underwent PRK. MMC was used if they had > 4.0 D myopia. All surgeries were performed with the VISX STAR S4 Excimer Laser (Abbott Medical Optics, Abbott Park, Illinois, USA).Results: Uncorrected visual acuity showed a significant improvement 3 years after surgery when compared to baseline and reached 0.01 ± 0.04 LogMAR (P < 0.001). Best-corrected visual acuity was 0.00 ± 0.01 LogMAR preoperatively and did not change significantly postoperatively. Spherical (P < 0.001) and cylindrical (P < 0.001) error significantly decreased. Manifest refraction SE showed a significant decrease when compared to before the operation and reached −0.08 ± 0.16 D (P < 0.001). At 3 years, mesopic contrast sensitivity was not significantly different from baseline at any spatial frequency. Vertical coma showed a significant decrease and reached −0.10 ± 0.27 µm (P = 0.004). Total coma (P < 0.001), spherical aberration (P < 0.001), and total high order aberrations (P < 0.001) also increased significantly.Conclusions: Based on the 3-year results, PRK (+MMC in patients with SE > 4.0 D) is a safe, effective, and predictable treatment option for mild-to-moderate myopic patients whose minimum corneal thickness is < 500 µm

Intraoperative OCT for Monitoring Corneal Pachymetry during Corneal Collagen Cross-Linking for Keratoconus

Biomechanical reinforcement of the cornea by collagen cross-linking (CXL) using riboflavin and ultraviolet A (UV-A) irradiation is a well-established treatment for halting the progression of keratoconus. Corneal pachymetry is one of the most important factors with respect to the safety of CXL. In addition to the initial pachymetric changes, significant changes in corneal pachymetry may occur during the different steps of the procedure, highlighting the role of intraoperative pachymetric measurements. Intraoperative optical coherence tomography (OCT) can be used safely and effectively to monitor the corneal pachymetry during CXL. Among the advantages of this technology is its ability to provide a more detailed profile of the corneal thickness in a noncontact manner compared to the ultrasound method. These features are especially advantageous for monitoring corneal pachymetry in the setting of CXL in KCN patients, considering the marked irregularity of the epithelium and stroma in these patients. OCT has also been used for evaluation of other aspects of the CXL procedure like evaluation of in vivo riboflavin penetration in to the corneal stroma

Evaluating the performance of clarification and ultraviolet units in disinfection of Isfahan North waste water treatment plant (WWTP) effluent in pilot plant

زمینه و هدف: استفاده از پساب تصفیه خانه فاضلاب شهری به خصوص در مصارف کشاورزی مستلزم گندزدایی پساب تا حد استاندارد می باشد. کاربرد اشعه UV به دلیل معایب کمتر در مقایسه با سایر گندزداها، در نقاط مختلف دنیا در حال گسترش است. هدف از انجام این مطالعه بررسی امکان تصفیه و گندزدایی پساب تصفیه خانه فاضلاب شمال اصفهان با واحد زلال سازی و اشعه UV می باشد. روش بررسی: در این مطالعه تجربی از یک واحد زلال ساز و دو نوع سیستم گندزدایی فرابنفش کم فشار (LP) و فشار متوسط (MP) جهت گندزدایی پساب ثانویه استفاده شد. پارامترهای میکروبی کلیفرم کل و مدفوعی، استرپتوکوک مدفوعی و همچنین پارامترهای شیمیایی کل مواد معلق TSS (Total Suspended Solids)، آهن، سختی، جذب و عبور اشعه UV در نمونه های برداشت شده قبل و بعد از واحدها مورد آزمایش قرار گرفت. داده ها با استفاده از آزمون آماری t زوجی تجزیه و تحلیل گردید. یافته ها: متوسط عبور اشعهUV در طول موج nm254 (نانومتر) از پساب زلال شده 34 درصد و میزان جذب اشعهau/cm 47/0 بدست آمد. در گندزدایی پساب زلال شده توسط لامپ LP، MP و تلفیق هر دو نوع لامپ، به ترتیب در دوز اشعه 400، 576 و mws/cm2 407 (میلی وات ثانیه بر سانتی متر مربع) غلظت کلیفرم‌ها به حد استاندارد سازمان حفاظت محیط زیست ایرانml) 100 FC/ 400 و TC1000 (رسید و تعداد استرپتوکوک مدفوعی در دوزهای mws/cm2400، 422 و mws/cm2407 تا log 5 کاهش یافت (05/0

Comprehensive planning for classification and disposal of solid waste at the industrial parks regarding health and environmental impacts

The aim of this study is the comprehensive planning for integrated management of solid waste at the industrial parks. The share of each industrial group including food, metal, chemical, non-metallic minerals, textile, electrical and electronical, and cellulose industries were 48.2, 14.9, 6.7, 22, 0.9, 0.6, and 6.5 percent, respectively. The results showed that nearly half of total industrial waste produced from the range of biological materials are biodegradable and discharging them without observing environmental regulations leads to short-term pollution and nuisance in the acceptor environment. Also some parts of case study waste were recyclable which is considerable from viewpoint of economical and environmental pollution. Long-term impacts will appear due to improper site selection of disposal from the spatial standpoint. In this way, an approach for site selection using several socioeconomic, physical, and environmental criteria based on multicriteria decision making model (MCDM) is introduced. Health risks and environment pollution such as soil and surface water may be done. It is essential to revise the studied industries layout, particularly those units which produce special waste which should be more cautious. Also stricter enforcement is required as an effective step in reducing the harmful impacts of it. © 2014 Hassan Hashemi et al