A Heavy QCD Axion model in Light of Pulsar Timing Arrays

Recently, pulsar timing array (PTA) experiments reported the observation of a stochastic gravitational wave (GW) background in the nanohertz range frequency band. We show that such signal can be originated from a cosmological first-order phase transition (PT) within a well-motivated heavy (visible) QCD axion model. Considering the Peccei-Quinn symmetry breaking at the TeV scale in the scenario, we find a supercooled PT, in the parameter space of the model, prolonging the PT with the reheating temperature at the GeV scale.Comment: 7 pages, 4 figure

Investigating the Causes of Corrosion in Heat Exchanger of Waste Incinerator System of Fajr Petrochemical and Providing Suggestions for Changing the Structure of Heat Exchanger

Optimization of operational performance of heat exchanger of waste incinerator systems from the temperature point of view in order to reduce corrosion is considerably important. At Fajr Petrochemicals, equipped with a biological waste incinerator system, some difficulties have arisen including corrosion in the equipment such as the heat exchanger and filter, which is the main factor of this corrosion rests in the heat exchanger. Therefore, the modeling of heat exchanger was investigated to find the causes of condensation formation and acid production. The modeling was done based on Computational Fluid Dynamics (CFD), and it was determined that, due to entry of hot gases to the heat exchanger and instantaneous cooling of them, humidity and condensation are formed in some parts of the heat exchanger and will cause the formation of acids and corrosion in it. In this study, a developed heat exchanger model is suggested so that the cooling of hot entry gases would be done in a mild manner, and also it would be possible to have a temperature control over outlet gases from the Heat Exchanger, and after the operational construction of the suggested model, and installation of it in the system, the previous difficulties were no longer

Investigating the Causes of Corrosion in Heat Exchanger of Waste Incinerator System of Fajr Petrochemical and Providing Suggestions for Changing the Structure of Heat Exchanger

Optimization of operational performance of heat exchanger of waste incinerator systems from the temperature point of view in order to reduce corrosion is considerably important. At Fajr Petrochemicals, equipped with a biological waste incinerator system, some difficulties have arisen including corrosion in the equipment such as the heat exchanger and filter, which is the main factor of this corrosion rests in the heat exchanger. Therefore, the modeling of heat exchanger was investigated to find the causes of condensation formation and acid production. The modeling was done based on Computational Fluid Dynamics (CFD), and it was determined that, due to entry of hot gases to the heat exchanger and instantaneous cooling of them, humidity and condensation are formed in some parts of the heat exchanger and will cause the formation of acids and corrosion in it. In this study, a developed heat exchanger model is suggested so that the cooling of hot entry gases would be done in a mild manner, and also it would be possible to have a temperature control over outlet gases from the Heat Exchanger, and after the operational construction of the suggested model, and installation of it in the system, the previous difficulties were no longer

Evaluation of bacterial and fungal contamination in equipments used in ladies and gentleman barbers in Shahrekord, 2009

زمینه و هدف: عفونت های قارچی و باکتریایی از جمله بیماری های واگیردار و شایعی هستند که در همه جا یافت می شوند و آرایشگاه ها به لحاظ عمومی بودن در این میان اهمیت خاصی دارند. این مطالعه با هدف بررسی آرایشگاه های شهرکرد از نظر آلودگی های میکروبی استافیلوکوک آرئوس و قارچ های درماتوفیت انجام شد. روش بررسی: در این تحقیق توصیفی– تحلیلی داده ها از طریق تکمیل چک لیست، نمونه گیری میکروبی و قارچی و انجام تجربیات آزمایشگاهی جمع آوری و به کمک آزمون آماری کای دو تجزیه و تحلیل شد. یافته ها: استافیلوکوک آرئوس عامل 4/12 آلودگی میکروبی بود. در بین آلودگی های قارچی کمتر از 1 قارچ درماتوفیت (میکروسپوروم نانوم)، 2/8 کاندیدا آلبیکانس، 11 پنی سیلیوم، 3/3 رایزوپوس و کمتر از 1 اسکوپولاریوپسیس مشاهده گردید. بین نتایج میکروبی و نوع آرایشگاه و همچنین بین نتایج میکروبی و موقعیت محلی آرایشگاه ارتباط معنی داری وجود نداشت. نتیجه گیری: سطح آلودگی به استافیلوکوک آرئوس و قارچ های درماتوفیت در آرایشگاه های شهرکرد در مقایسه با تحقیق های انجام شده در سایر اماکن عمومی نظیر بیمارستان ها، استخرهای شنا، مجموعه های ورزشی و اتاق عمل کمتر است

The role of gray-scale ultrasound and elastography in differentiating benign from malignant axillary lymph nodes in patients with breast cancer

Introduction: Breast cancer is one of the most common cancers in women. Involvement of regional lymph nodes by breast cancer has shown to be a significant marker in the overall diagnosis of patients. In this study, we aimed to investigate the role of gray-scale ultrasound and elastography in discriminating benign from malignant axillary lymph nodes in patients with breast cancer. Methods: In this analytical study, patients with breast cancer who were referred to sonography ward of a tertiary medical educational center and found to have suspicious lymph nodes were investigated. Formal properties were evaluated by grayscale ultrasound and tissue properties were assessed by elastography. Biopsies were performed on all cases and suspicious tissues were removed. Results: This study was conducted on 50 patients with the mean age of 48.54±10.58 years. 52% of patients had a mass in their right breast and the most prevalent type of breast cancer was intra-ductal carcinoma. 60% of the lymph nodes were reported to be malignant. In 56% of the lymph nodes, grayscale ultrasound tests demonstrated unusual findings and the most common finding was the removal of fat from lymph node hilum. Moreover, elastography results indicated that 36% of the cases have grade 4 (blue) lesions. Conclusion: This study indicated that grayscale ultrasound and elastography have high sensitivity and specificity in detecting metastatic lymph nodes. This finding was in line with the findings reported in many of the previous studies