5,216 research outputs found
Assessment of radiofrequency ablation technique in development of aortic valve stenosis in rabbits
Purpose: To develop a minimally invasive and reproducible model of aortic stenosis in rabbits using radiofrequency ablation technique (RFA).
Material and methods: Eleven rabbits were studied. A radiofrequency ablation catheter was introduced via the femoral artery and advanced to the aortic valve area under fluoroscopic control. In three rabbits radiofrequency energies, at 5 W, 10 W and 15 W respectively, were applied thrice for 90 sec. In eight rabbits, energy of 15 W was applied for the same time periods. The velocity of the blood through the aortic valve was determined by color Doppler ultrasound immediately before and after ablation and after six weeks. After six weeks the rabbits were sacrificed and the aortic valve was examined macroscopically.
Results: Peak systolic velocity (PSV) was similar at the time of ablation and after six weeks in eight of the nine surviving rabbits, and had increased from 1.1 to 1.75 m/s in one rabbit. Two rabbits developed aortic insufficiencies visualized by color Doppler. No macroscopic changes were seen at the aortic valve area 6 weeks after ablation.
Conclusion: In the current study we did not succeed in inducing aortic valve damage/fibrosis using different RFA energies. Inadequate RFA power or inappropriate positioning of the RFA catheter could be limitations of our study
Investigating Ca II emission in the RS CVn binary ER Vulpeculae using the Broadening Function Formalism
The synchronously rotating G stars in the detached, short-period (0.7 d),
partially eclipsing binary, ER Vul, are the most chromospherically active
solar-type stars known. We have monitored activity in the Ca II H & K reversals
for almost an entire orbit. Rucinski's Broadening Function Formalism allows the
photospheric contribution to be objectively subtracted from the highly blended
spectra. The power of the BF technique is also demonstrated by the good
agreement of radial velocities with those measured by others from less crowded
spectral regions. In addition to strong Ca II emission from the primary and
secondary, there appears to be a high-velocity stream flowing onto the
secondary where it stimulates a large active region on the surface 30 - 40
degrees in advance of the sub-binary longitude. A model light curve with a spot
centered on the same longitude also gives the best fit to the observed light
curve. A flare with approximately 13% more power than at other phases was
detected in one spectrum. We suggest ER Vul may offer a magnified view of the
more subtle chromospheric effects synchronized to planetary revolution seen in
certain `51 Peg'-type systems.Comment: Accepted to AJ; 17 pages and 16 figure
Optimal crop management can reduce energy use and greenhouse gases emissions in rainfed canola production
Abstract Energy use and greenhouse gases (GHG) emissions in rainfed canola production in north eastern Iran were analyzed to find measures to reduce energy use and GHG emissions. Four production scenarios, i.e. a high-input, a low-input, a better crop management and a usual scenario, evaluated. All activities and production processes were monitored and recorded over three consecutive years. The usual scenario consumed 13 GJ ha -1 energy input, resulted in 52 GJ ha -1 energy output and GHG emissions of 1028 kg CO 2 -eq ha -1 and 556 kg CO 2 -eq t -1 . The key factors relating to energy use and GHG emissions were nitrogen fertilizer and fuel for field operations. Compared to the usual production scenario, the better crop management production scenario was significantly more efficient; it consumed 25% less input energy, needed 17% lower amount of nitrogen fertilizer, but resulted in 35% more grain yield and output energy. This scenario also resulted in 26% less GHG emissions per unit field area and 45% less GHG emissions per ton of grain. Measures of improvement in energy use and GHG emission were identified
Experimental Investigation of nanofluid heat transfer in a square cross-sectional duct
English version Forced convective heat transfer of two different nanofluids
including ALO-water and CuO-water in laminar flow through square cross
section duct under constant heat flux has been investigated. The Nusselt number
and average convective heat transfer coefficient for different nanoparticles
concentrations as a function of Peclet number have been analyzed.
ALO-water nanofluid with 0.2, 0.5, 1.0, 1.5, 2.0 and 2.5 percent volume
fractions has been tested. The maximum enhancement of convective heat transfer
coefficient for each of the above mentioned concentrations was 7, 10, 13, 18,
22, 27 percent, respectively. Also, CuO-water nanofluid was tested at 0.1, 0.2,
0.5, 0.8, 1.0 and 1.5 percent volume fractions and the results show that the
maximum enhancement of convective heat transfer coefficient for each
concentration was 8, 10, 14, 16, 19, 21 percent, respectively.Comment: 6 pages, in Persia
Genome-wide single nucleotide polymorphism-based autozygosity mapping facilitates identification of mutations in consanguineous families with epidermolysis bullosa
Autozygosity mapping (AM) is a technique utilised for mapping homozygous autosomal recessive (AR) traits and facilitation of genetic diagnosis. We investigated the utility of AM for the molecular diagnosis of heterogeneous AR disorders, using epidermolysis bullosa (EB) as a paradigm. We applied this technique to a cohort of 46 distinct EB families using both short tandem repeat (STR) and genome-wide single nucleotide polymorphism (SNP) array-based AM to guide targeted Sanger sequencing of EB candidate genes. Initially, 39 of the 46 cases were diagnosed with homozygous mutations using this method. Independently, 26 cases, including the seven initially unresolved cases, were analysed with an EB-targeted next-generation sequencing (NGS) panel. NGS identified mutations in five additional cases, initially undiagnosed due to the presence of compound heterozygosity, deep intronic mutations or runs of homozygosity below the set threshold of 2 Mb, for a total yield of 44 of 46 cases (95.7) diagnosed genetically. © 2018 John Wiley & Sons Ltd
Using boundary line analysis to assess the on-farm crop yield gap of wheat
Food security is one of the most important challenges facing human kind. A very promising approach to solve the problem is closing the yield gap, i.e. the difference between farmer’s and potential yield. A ‘complete yield gap assessment method’ must provide information regarding potential yield, actual yield and yield gap, the causes of the gap and their importance. The objective of this study was to indicate how boundary line analysis (BLA) could be applied to such an assessment. BLA was only applied to crop management practices/inputs, e.g. sowing date and rate and fertilizer applications. The data were gathered from about 700 wheat farms in Golestan province, one of the major wheat producing regions in Iran, during two growing seasons of 2013–2014 and 2014–2015. Wheat production in Golestan province can be divided into three production situations according to agro- and geo-climatology criteria: these are ‘irrigated or high-rainfall’, ‘high-yield rainfed’, and ‘low-yield rainfed’. Boundary lines were fitted to the edge of the data cloud of crop yield versus management variables using data from each of the three wheat production situations in the province. Actual farmers’ yields were 3900 kg ha–1 for irrigated, 4000 kg ha–1 for high-yield rainfed and 2000 kg ha–1 for low-yield-rainfed situations; BLA indicated that potential yields (the highest yields obtained by farmers in the sample) were 6900, 5800 and 3900 kg ha−1 for each situation, respectively. The corresponding yield gaps were high at 42%, 31% and 50%. Using BLA it was possible to determine the optimal sowing date, seeding rate, frequency and amount of nitrogen fertilizer applied, amount of nitrogen top-dressing, amount of phosphorus and potassium fertilizers and irrigation frequency. The percentage of farmers who cultivated outside of the optimal levels was also identified and was used to determine the importance of each management factor in yield gap. It was concluded that BLA as applied in the study, was a cheap and simple method which, without the need for expensive experimentation, was able to detect yield gaps and their causes in a region. The method can be used effectively in countries/regions where important yield gaps exist
Possibility of trout farms efluent return to groundwater In non-agricultural seasons
This project is trying to investigate water contamination after use in ponds. For this aquaculture status, physical and chemical water properties, microbial pollutants and heavy metals levels in the some of trout ponds effluent in East Azerbaijan province were evaluated in 2007 to 2009. The information of groundwater and climate conditions in ten years, Drilling and wells piezometric Information, in local wells are reviewed. According to data obtained from analysis of water samples in the output pools range studied concentrations(term mg/l) some parameters are as follows:(BOD: 1.9-3.2), (COD: 3.4-34.1), (TSS: 26.6-42.7), (N-NO_2:0.003-.136),(P-Po4:0.0170.067), (pH:7.75-8.28). Electrical conductivity (500 ±2 to 1129±144 term µm/cm) in the effluent ponds. Based on the results of we can say that between input and effluent ponds in the review of all factors as chlorine, sulfate, sodium, potassium, total nitrogen, soluble phosphorus, total phosphorus, calcium, total hardness, magnesium, alkalinity and silica significant changes not be observed. Review of water analysis data to some factors (such as: water temperature, EC, pH, NO_2, CO_2, HCO_3, CO_3, DO, COD, BOD) and compare this data with the authorities standard confirmed that the All factors mentioned in effluent is allowed now. In terms of microbial contamination and heavy metals (Zn, Cu, Ca, Pb, Fe, Cr) is no pollution. Appropriate strategies for removing suspended materials must to use. We can use Watershed Management solutions to inject output water to the underground table. Should be noted status change (eg change in flow rate, an unusual increase in temperature, fish density increasing, reducing food quality, lack of appropriate management actions and ...) may reduce the effluent quality and the ability of injection water underground to lose. In this case, measures must be for wastewater treatment and improve the quality ponder
Characterization of active and infiltrative tumorous subregions from normal tissue in brain gliomas using multiparametric MRI
Background: Targeted localized biopsies and treatments for diffuse gliomas rely on accurate identification of tissue subregions, for which current MRI techniques lack specificity.
Purpose: To explore the complementary and competitive roles of a variety of conventional and quantitative MRI methods for distinguishing subregions of brain gliomas.
Study Type: Prospective.
Population: Fifty‐one tissue specimens were collected using image‐guided localized biopsy surgery from 10 patients with newly diagnosed gliomas.
Field Strength/Sequence: Conventional and quantitative MR images consisting of pre‐ and postcontrast T1w, T2w, T2‐FLAIR, T2‐relaxometry, DWI, DTI, IVIM, and DSC‐MRI were acquired preoperatively at 3T.
Assessment: Biopsy specimens were histopathologically attributed to glioma tissue subregion categories of active tumor (AT), infiltrative edema (IE), and normal tissue (NT) subregions. For each tissue sample, a feature vector comprising 15 MRI‐based parameters was derived from preoperative images and assessed by a machine learning algorithm to determine the best multiparametric feature combination for characterizing the tissue subregions.
Statistical Tests: For discrimination of AT, IE, and NT subregions, a one‐way analysis of variance (ANOVA) test and for pairwise tissue subregion differentiation, Tukey honest significant difference, and Games‐Howell tests were applied (P < 0.05). Cross‐validated feature selection and classification methods were implemented for identification of accurate multiparametric MRI parameter combination.
Results: After exclusion of 17 tissue specimens, 34 samples (AT = 6, IE = 20, and NT = 8) were considered for analysis. Highest accuracies and statistically significant differences for discrimination of IE from NT and AT from NT were observed for diffusion‐based parameters (AUCs >90%), and the perfusion‐derived parameter as the most accurate feature in distinguishing IE from AT. A combination of “CBV, MD, T2_ISO, FLAIR” parameters showed high diagnostic performance for identification of the three subregions (AUC ∼90%).
Data Conclusion: Integration of a few quantitative along with conventional MRI parameters may provide a potential multiparametric imaging biomarker for predicting the histopathologically proven glioma tissue subregions
Molecular genetic diagnosis of Glanzmann syndrome in Iranian population; Reporting novel and recurrent mutations
Background: Glanzmann thrombasthenia (GT) is a rare autosomal recessive abnormality of platelet aggregation with quantitative and/or qualitative abnormality of αIIbβ3 integrin. The αIIbβ3 is a platelet fibrinogen receptor, which is required for platelet aggregation, firm adhesion, and also spreading. The disease is more prevalent in the populations with a higher rate of consanguineous marriages as in some Middle Eastern populations including Iraq, Jordan, and Iran. Different types of mutations in ITGA2B and ITGB3 genes have been previously reported to cause the disease. Result: In this study, 16 patients with the clinical diagnosis of GT were studied. Direct sequencing of the exons and exon-intron boundaries of the above genes revealed mutations in 14 patients (detection rate: 87.5). Briefly, out of fifteen types of identified mutations, 14 were novel. Seven mutations in the ITGB3 gene included 4 missense c.2T > C, c.155 G > T, c. 538 G > A, c.1990 G > T, one nonsense mutation c.1303 G > T, a small deletion c.1656-1658delCTC and a deletion of one nucleotide c.401delA. Mutations in the ITGA2B were 8 different mutations consisting 2 missense c.286 T > A, c.842 C > T, 2 deletions c.1899 del T, c.189-319-236del, an insertion c.1071-1072insG and one splice site mutations c.409-3 C > G, one synonymous mutation that might alter the normal splicing process c.1392 A > G and a nonsense mutation c.1555 C > T. The causative mutation in 2 patients remained unknown. Using long-range PCR and sequencing, we found a rather large deletion. The break point of this deletion covers 319 nt from the last part of the first intron and 48 nt from the beginning of the second exon of ITGA2B gene. The deletion was also detected in two unrelated patients with the same ethnicity. In addition, in silico analyses of novel mutations were performed. Conclusion: There was no recurrent mutation in the studied population. This may be due to either small sample size or the heterogeneity of the studied population. © 2019 The Author(s)
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