A comparison of the finite difference and finite element methods for heat transfer calculations

The finite difference method and finite element method for heat transfer calculations are compared by describing their bases and their application to some common heat transfer problems. In general it is noted that neither method is clearly superior, and in many instances, the choice is quite arbitrary and depends more upon the codes available and upon the personal preference of the analyst than upon any well defined advantages of one method. Classes of problems for which one method or the other is better suited are defined

Validation of the World Health Organization-5 well-being index; assessment of maternal well-being and its associated factors

Objective: The aim of this study was to validate the World Health Organization-5 Well-Being Index (WHO-5) in a sample of pregnant Iranian women, to explore the changes in maternal well-being from pregnancy to postpartum, and to determine the factors associated with maternal well-being. Materials and Methods: This study included 341 pregnant women that presented to healthcare centers affiliated with Shahroud University of Medical Sciences, Iran, in 2011. The participants completed the General Health Questionnaire (GHQ-28) and Farsi version of WHO-5 during the third trimester of pregnancy and at 2 months postpartum. Results: Cronbach's alpha coefficient for WHO-5 items was 0.85. The correlation coefficient between WHO-5 and GHQ-28 was -0.64 (P < 0.001). Exploratory factor analysis yielded 1 factor with an eigen value equal to 3.15, which explained 63.1% of the total variance. Confirmatory factor analysis confirmed the 1-factor structure. The area under ROC curve was 0.82. A WHO-5 cut-off score of <50 exhibited optimal sensitivity (0.84) and specificity (0.59) for identifying psychological symptoms (GHQ-28 score ≥24). There was a significant difference between third trimester (58.4 ± 22) and postpartum (64.1 ± 22.3) mean WHO-5 scores (P < 0.001). Maternal level of education (OR = 1.130; 95% CI: 1.307, 1.232) was the only predictor of maternal well-being during third trimester. Breastfeeding difficulty (OR = 0.923; 95% CI: 0.882, 0.965) and maternal well-being scores during third trimester (OR = 1.038; 95% CI: 1.019, 1.058) were predictors of maternal well-being during the postpartum period. Conclusions: The Farsi version of WHO-5 was observed to be a reliable and valid instrument for screening psychological symptoms in pregnant Iranian women. The present findings show that maternal well-being improved following childbirth

Quality of life after cesarean and vaginal delivery

Objective: Cesarean rates in recent decades have been increasing and a number of studies have shown that cesarean increases maternal morbidities. The aim of this study is to compare the quality of life after cesarean and vaginal delivery. Methods: This prospective study was carried out on 356 pregnant women visiting urban health centers in Shahroud City, Northeast Iran, in 2011. The subjects completed the quality of life questionnaire in the third trimester of pregnancy and at 8 weeks postpartum. Results: In primiparas, the mean global QOL scores for the cesarean and vaginal delivery groups were 67.65±12.7 and 72.12±11.8, respectively. Also, the scores for the physical, psychological and social domains of QOL as well as the global score of QOL were higher in the vaginal delivery group than the cesarean group (p<0.05). In the case of primiparas, multiple regression analysis revealed that after adjusting for education, desirability of pregnancy and the General Health Questionnaire score, the delivery type remained as a predictor of the scores for the physical (R2=1.7%; B=-3.826; p=0.031; CI [-7.301, -.350]) and social (R2=2.5%; B=-5.708; p=0.017; CI [-10.392, -1.023]) domains of QOL and the global QOL score (R2=2.6%; B=-4.065; p=0.006; CI [-6.964, -1.164]). While multiparas, there was no relationship between QOL and type of delivery. Conclusion: In this sample of low-risk women, cesarean negatively affected the QOL of primiparas. More studies with larger sample sizes should be conducted to examine the effects of cesarean on QOL in both primiparas and multiparas within a shorter period after delivery. © OMSB, 2013

Interactive computation of radiation view factors

The development of a pair of computer programs to calculate the radiation exchange view factors is described. The surface generation program is based upon current graphics capabilities and includes special provisions which are unique to the radiation problem. The calculational program uses a combination of contour and double area integration to permit consideration of radiation with obstruction surfaces. Examples of the surface generation and the calculation are given

Effects of N-Acetylcysteine on auditory brainstem response threshold shift in rabbits exposed to noise and carbon monoxide

Problem statement: Noise Induced Hearing Loss (NIHL) is one of the most important occupational disease in worldwide. NIHL has been found to be potentiated by simultaneous Carbon monoxide (CO) exposure. Exposure to noise plus CO is common in occupational and environmental settings. Free radicals have been implicated in cochlear damage resulting from exposure to noise and due to CO hypoxia This study examined whether N-Acetylcysteine (NAC) administration cause attenuation of Auditory Brainstem Response (ABR) threshold shifts resulting from noise exposure and noise plus CO exposure. Approach: Forty-two rabbits were divided into seven groups including control, noise+ saline, noise+ CO +saline, noise+ NAC, noise+ CO+ NAC, CO+ NAC and NAC alone. ABR was assessed before exposure, 1 hour and 14 days post exposure. Results: The administration of 325 mg kg-1 of NAC prior, following and post exposure to noise or noise plus CO recovered permanent ABR threshold shift at 1 and 2 kHz almost to the baseline and provided significant attenuation in permanent ABR threshold shift at 4 and 8 kHz in subjects which were exposed to noise but it did not block the potentiating of threshold elevation by CO exposure (extra threshold loss by combined exposure) at 4 and 8 kHz. Conclusion: NAC provides protective effect against hearing loss resulting from noise exposure and simultaneous exposure to noise plus CO. © 2010 Science Publications

Assessment of outer hair cell function and blood antioxidant status of rabbits exposed to noise and metal welding fumes

Objectives: To investigate the interaction between welding fumes and noise in causation of hearing impairment. Methods: Groups of rabbits (n = 6) were exposed to noise, welding fumes or combination of both prior to Distortion Product Otoacoustic-Emissions (DPOAEs) analysis. The function of outer hair cells (OHCs) was examined by DPOAE assessment over a broad range of frequencies. Variations in DPOAE amplitude were compared between control (n = 6) and exposed (n = 18) groups. Results: The DPOAEs levels measured at different frequencies (1379-6299 Hz) were found to decrease significantly (P &lt; 0.05) in rabbits exposed to 110 dB sound pressure level (SPL) broadband noise (8 h/day, 12 days). In rabbits, exposed to carbon-steel welding fumes alone (157 mg/m3), the threshold shift was limited to the high frequencies (2759-6299 Hz), whereas, mixed exposure to noise and fumes resulted in reduction of DPOAEs at all the frequencies. Changes in DPOAEs were associated with increased susceptibility of erythrocytes to oxidation (P &lt; 0.05). Exposure to noise or fumes alone or simultaneously, suppressed total antioxidant ability of plasma as measured by ferric reducing ability of plasma (FRAP). Noise alone or in combination with fumes resulted in depletion of blood glutathione (GSH). Despite suppression of FRAP in the exposed groups, GSH was found to remain unchanged due to welding fumes suggesting that antioxidants other than GSH are affected by toxicants present in metal welding fumes. Conclusion: Exposure to very high levels of welding fumes can increase noise-related effects on OHC function by extending hearing threshold shift to wide band frequencies. © 2006 Elsevier Ireland Ltd. All rights reserved

Beyond Spheroids and Discs: Classifications of CANDELS Galaxy Structure at 1.4 < z < 2 via Principal Component Analysis

Important but rare and subtle processes driving galaxy morphology and star-formation may be missed by traditional spiral, elliptical, irregular or S\'ersic bulge/disk classifications. To overcome this limitation, we use a principal component analysis of non-parametric morphological indicators (concentration, asymmetry, Gini coefficient, $M_{20}$, multi-mode, intensity and deviation) measured at rest-frame $B$-band (corresponding to HST/WFC3 F125W at 1.4 $10^{10} M_{\odot}$) galaxy morphologies. Principal component analysis (PCA) quantifies the correlations between these morphological indicators and determines the relative importance of each. The first three principal components (PCs) capture $\sim$75 per cent of the variance inherent to our sample. We interpret the first principal component (PC) as bulge strength, the second PC as dominated by concentration and the third PC as dominated by asymmetry. Both PC1 and PC2 correlate with the visual appearance of a central bulge and predict galaxy quiescence. PC1 is a better predictor of quenching than stellar mass, as as good as other structural indicators (S\'ersic-n or compactness). We divide the PCA results into groups using an agglomerative hierarchical clustering method. Unlike S\'ersic, this classification scheme separates compact galaxies from larger, smooth proto-elliptical systems, and star-forming disk-dominated clumpy galaxies from star-forming bulge-dominated asymmetric galaxies. Distinguishing between these galaxy structural types in a quantitative manner is an important step towards understanding the connections between morphology, galaxy assembly and star-formation.Comment: 31 pages, 24 figures, accepted for publication in MNRA

INCREASED RADIORESISTANCE TO LETHAL DOSES OF GAMMA RAYS IN MICE AND RATS AFTER EXPOSURE TO MICROWAVE RADIATION EMITTED BY A GSM MOBILE PHONE SIMULATOR

The aim of this study was to investigate the effect of pre-irradiation with microwaves on the induction of radioadaptive response. In the 1st phase of the study, 110 male mice were divided into 8 groups. The animals in these groups were exposed/sham-exposed to microwave, low dose rate gamma or both for 5 days. On day six, the animals were exposed to a lethal dose (LD). In the 2nd phase, 30 male rats were divided into 2 groups of 15 animals. The 1st group received microwave exposure. The 2nd group (controls) received the same LD but there was no treatment before the LD. On day 5, all animals were whole-body irradiated with the LD. Statistically significant differences between the survival rate of the mice only exposed to lethal dose of gamma radiation before irradiation with a lethal dose of gamma radiation with those of the animals pre-exposed to either microwave (p=0.02), low dose rate gamma (p=0.001) or both of these physical adapting doses (p=0.003) were observed. Likewise, a statistically significant difference between survival rates of the rats in control and test groups was observed. Altogether, these experiments showed that exposure to microwave radiation may induce a significant survival adaptive response

Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products

We developed a low-cost, high-throughput microbiome profiling method that uses combinatorial sequence tags attached to PCR primers that amplify the rRNA V6 region. Amplified PCR products are sequenced using an Illumina paired-end protocol to generate millions of overlapping reads. Combinatorial sequence tagging can be used to examine hundreds of samples with far fewer primers than is required when sequence tags are incorporated at only a single end. The number of reads generated permitted saturating or near-saturating analysis of samples of the vaginal microbiome. The large number of reads al- lowed an in-depth analysis of errors, and we found that PCR-induced errors composed the vast majority of non-organism derived species variants, an ob- servation that has significant implications for sequence clustering of similar high-throughput data. We show that the short reads are sufficient to assign organisms to the genus or species level in most cases. We suggest that this method will be useful for the deep sequencing of any short nucleotide region that is taxonomically informative; these include the V3, V5 regions of the bac- terial 16S rRNA genes and the eukaryotic V9 region that is gaining popularity for sampling protist diversity.Comment: 28 pages, 13 figure