Casimir effect in a weak gravitational field and the spacetime index of refraction

In a recent paper [arXiv:0904.2904] using a conjecture it is shown how one can calculate the effect of a weak stationary gravitational field on vacuum energy in the context of Casimir effect in an external gravitational field treated in 1+3 formulation of spacetime decomposition.. In this article, employing quntum field theory in curved spacetime, we explicitly calculate the effect of a weak static gravitational field on virtual massless scalar particles in a Casimir apparatus. It is shown that, as expected from the proposed conjecture, both the frequency and renormalized energy of the virtual scalar field are affected by the gravitational field through its index of refraction. This could be taken as a strong evidence in favour of the proposed conjecture. Generalizations to weak {\it stationary} spacetimes and virtual photons are also discussed.Comment: 11 pages, RevTex, typos corrected (combined with arXiv:0904.2904 published in PRD

Predicting compressive strength of different geopolymers by artificial neural networks

In the present study,six different models based on artificial neural networks have been developed to predict the compressive strength of different types of geopolymers.The differences between the models were in the number of neurons in hidden layers and in the method of finalizing the models.Seven independent input parameters that cover the curing time,Ca(OH)2 content, the amount of superplasticizer, NaOH concentration,mold type,geopolymer type and H2O/Na2O molar ratio were considered.For each set of these input variables,the compressive strength of geopolymers was obtained.A total number of 399 input-target pairs were collected from the literature, randomly divided into 279,60 and 60data and were trained,validated and tested, respectively. The best performance model was obtained through a network with two hidden layers and absolute fraction of variance of 0.9916, the absolute percentage error of 2.2102 and the root mean square error of 1.4867 in training phase. Additionally,the entire trained,validated and tested network showed a strong potential for predicting the compressives trength of geopolymers with a reasonable performance in the considered range

The dual of z-submodules of modules and some of extensions

Let R be a commutative ring with identity and M be an R-module. The purpose of this paper is to introduced the dual notion of z-submodules of M and some of extensions. Moreover, we investigate some properties of these classes of modules when M is a coreduced comultiplication R-module

Simultaneous Determination of Nitrite and Nitrate in Milk Samples by Ion Chromatography Method and Estimation of Dietary Intake

The presence of nitrate and nitrite in foods may be considered hazardous after ingestion in the gastrointestinal tract due to their reaction with naturally occurred secondary amines to form potentially carcinogenic nitrosamines. Due to this fact, a new method was developed in this study for the simultaneous determination of nitrite and nitrate in milk samples using by ion chromatography. Proposed mobile phase composed of sodium hydrogen carbonate and sodium carbonate (1.0 and 3.2 mmol/L) with a flow rate of 0.7 ml/min. The average recoveries for nitrate and nitrite were higher than 86 and 88, respectively. The limit of detection for nitrate and nitrite were 0.24 and 0.09 mg/L, respectively. The results of 102 real milk samples showed nitrate was found in all of the samples (100) with a mean of 34 ± 11 mg/L, while nitrite was found in none of the samples. The mean intake of nitrate in all age groups was lower than World Health Organization guideline. The present assessment concludes that the maximum contaminant level was equal to 82.8 mg/L nitrate. This method was fast, sensitive and accurate and is capable of being an alternative method in food control laboratories for investigation of nitrite and nitrate content. This is the first study of the determination and survey of nitrite and nitrate and exposure assessment of the Iranian population to nitrite and nitrate level in milk, which was widely used in infants and adolescents as one of the basic food components. Copyright © Taylor & Francis Group, LLC

Modeling the compressive strength of geopolymeric binders by gene expression programming-GEP

GEP has been employed in this work to model the compressive strength of different types of geopolymers through six different schemes. The differences between the models were in their linking functions, number of genes, chromosomes and head sizes. The curing time, Ca(OH)2 content, the amount of superplasticizer, NaOH concentration, mold type, aluminosilicate source and H2O/Na2O molar ratio were the seven input parameters considered in the construction of the models to evaluate the compressive strength of geopolymers. A total number of 399 input-target pairs were collected from the literature, randomly divided into 299 and 100 sets and were trained and tested, respectively. The best performance model had 6 genes, 14 head size, 40 chromosomes and multiplication as linking function. This was shown by the absolute fraction of variance, the absolute percentage error and the root mean square error. These were of 0.9556, 2.4601 and 3.4716 for training phase, respectively and 0.9483, 2.8456 and 3.7959 for testing phase, respectively. However, another model with 7 genes, 12 head size, 30 chromosomes and addition as linking function showed suitable results with the absolute fraction of variance, the absolute percentage error and the root mean square of 0.9547, 2.5665 and 3.4360 for training phase, respectively and 0.9466, 2.8020 and 3.8047 for testing phase, respectively. These models showed that gene expression programming has a strong potential for predicting the compressive strength of different types of geopolymers in the considered range

Evaluation of preoperative anxiety and stress, and ways to modify it, the patients in Kashani hospital operating room in 2013

زمینه و هدف: با وجودی که در عصر حاضر بی هوشی و جراحی نسبت به گذشته کم عارضه تر و موفقیت آمیز تر شده است، ولی اضطراب قبل از عمل جراحی همچنان به قوت خود باقی است. اضطراب نوعی تشویش و نگرانی است که به دنبال وجود نوعی احساس تهدید یا خطر در فرد ایجاد می شود و می تواند در کاهش یا افزایش توانایی درک فرد، موثر باشد. این مطالعه با هدف ارزیابی عوامل اضطراب و استرس قبل از عمل جراحی و راه های تعدیل آن در بیماران جراحی شده انجام شده است. روش بررسی: این مطالعه ی توصیفی در سال 1392 بر روی 120 بیمار جراحی شده در اتاق عمل بیمارستان کاشانی شهرکرد انجام گرفت. افراد به روش تصادفی سیستماتیک انتخاب شدند. جهت سنجش اضطراب، از پرسشنامه محقق ساخته استفاده شد. یافته ها: بیشترین میزان اضطراب مربوط به نگرانی های قبل از عمل جراحی (13/15)، عوامل تنش زا و مراقبت انجام شده در بخش (12/19)، عوامل تنش زا در رابطه با کارکنان اتاق عمل (10/35) و عوامل تنیدگی آور محیط فیزیکی اتاق عمل (7/26) بوده است. نتیجه گیری: یافته های نهایی این پژوهش حاکی از آن است که با شناسایی عوامل مؤثر بر اضطراب قبل از عمل و رفع آن ها می توان میزان اضطراب قبل از عمل را به حداقل رساند؛ لذا پیشنهاد می گردد با به کارگیری روش های متنوع جهت آموزش بیماران و مشخص کردن برنامه مدون آموزشی در جهت رفع عوامل موثر بر اضطراب اقدام گردد

Effect of the timing of initial feeding on growth and survival of Persian sturgeon (Acipenser persicus) larvae

Effect of the timing of first feeding (9, 10, 11, 12 and 13 days post hatch) with a live food (Artemia naupli) on Persian sturgeon was examined at 17.7±0.8 and 18.1±0.4°C. The results showed that the timing of first feeding affected on weight, length, length-weight ratio and specific growth rate, but one day delay in the timing of initial feeding doesn't affect on the survival and two days delay in the timing of initial feeding doesn't affect on the condition factor. Results of this research showed that some factors such as weight, length, length-weight ratio and specific growth rate, are more suitable than survival and condition factor for exhibiting of effects of delay in the starting time of initial feeding in Persian sturgeon fish larvae. Thus it is better that the initial feeding of Persian sturgeon at 17.7±0.8 and 18.1 ±0.4°C started on 12 and 9 days after hatching, respectively, as well as more delay in initiating exogenous feeding has negative effects on growth of larvae