156 research outputs found
Application of Non-Perturbative Renormalization Group to Nambu-Jona-Lasinio/Gross-Neveu model at Finite Temperature and Chemical Potential
The chiral phase structure of the Nambu-Jona-Lasinio/Gross-Neveu model at
finite temperature T and finite chemical potential \mu is investigated using
(Wilsonian) Non-Perturbative Renormalization Group (NPRG). In the large N_c
limit, the solutions of NPRG with various cutoff schemes are shown. For a
sufficiently large ultra-violet cutoff, NPRG results coincide with those of
Schwinger-Dyson equation and have little cutoff scheme dependence. Next, to
improve the approximation, we incorporate the mesonic fluctuations. We
introduce the auxiliary fields for mesons, and then derive NPRG equation for
finite N_c. The chiral phase structure on (T,\mu) plane beyond the leading of
1/N_c expansion is investigated in the sharp cutoff limit. N_c dependence of
chiral phase diagram is obtained.Comment: 21 pages, 10 epsf figures, to be published in Progress of Theoretical
Physic
Prevention of Catastrophic Volcanic Eruptions
Giant volcanic eruptions emit sulphate aerosols as well as volcanic ash. Needless to say that volcanic ash causes significant damage to the environment and human at large. However, the aerosols are even worse. They reach the Stratosphere and stay there for months to years reflecting insolation. As a result, air temperature at the Earth's surfaces drops. Even a slight temperature drop may cause severe food shortage. Yellowstone supervolcano, for example, can even make human in the Northern Hemisphere extinct in several hundred thousand years. Therefore, gradual energy release by supercritical geothermal power generation was proposed to prevent such catastrophic eruptions. The necessary technical innovation is drilling into the depth. However, after the innovation, the power generation itself would be profitable. The risk is unpredicted induction of unwanted catastrophic eruptions.ISERME 2017:International Symposium on Earth Resources Management & Environment. 29-30 August 2017, Colombo, Sri Lank
Impact on permeability due to axial stress disturbances for cretaceous sandy shale
Seismic waves generated from earthquakes and artificial surface vibration might alter the water level in the wells and oil or gas production. These transient stress disturbances prospectively caused the permeability change due to new pathway occurring or existing pathway being cleared. The permeability change might encourage enhancing gas recovery, inducing small earthquakes preventing future large earthquakes, and de-routing underground water flow for various purposes. The prospective permeability increase by axial stress disturbances of Cretaceous sandy shale may effectively expand the capacity of methane gas recovery of Kushiro Coal Mine. The paper observes the permeability change of intact or triaxially fractured Kushiro Cretaceous sandy shale by axial stress disturbances. It will be shown that increasing and decreasing factors might work together on permeability.MMIJ Fall Meeting 2017, Sept. 26-28 2017, Sapporo, Japan (資源・素材2017(札幌): 平成29年度資源・素材関係学協会合同秋季大会, 2017年9月26日~28日, 北海道大学, 札幌市
Effect of Injection Flow Rate on Product Gas Quality in Underground Coal Gasification (UCG) Based on Laboratory Scale Experiment: Development of Co-Axial UCG System
Underground coal gasification (UCG) is a technique to recover coal energy without mining by converting coal into a valuable gas. Model UCG experiments on a laboratory scale were carried out under a low flow rate (6~12 L/min) and a high flow rate (15~30 L/min) with a constant oxygen concentration. During the experiments, the coal temperature was higher and the fracturing events were more active under the high flow rate. Additionally, the gasification efficiency, which means the conversion efficiency of the gasified coal to the product gas, was 71.22% in the low flow rate and 82.42% in the high flow rate. These results suggest that the energy recovery rate with the UCG process can be improved by the increase of the reaction temperature and the promotion of the gasification area
Geological and Geotechnical Evaluation of Gully Erosion at Nguzu Edda, Afikpo Sub-Basin, Southeastern Nigeria
A detailed geological field mapping of Nguzu Edda has revealed that gully erosion and landslides have remained active over the years, posing serious threats to human life, agricultural land, infrastructure and socio-economic activities within the area. Consequently, twelve true representative soil samples from different locations within gully sites have been analyzed based on ASTM and British Standards, to evaluate geologic conditions and geotechnical parameters that influence the gullies problems. The results of the laboratory tests revealed that the soil at the gully sites are predominantly sands (57~99.5 % with mean of 69.7%) with low amount of fines (silt; 0.3~ 22% with average value of 14.6% and clay: 0.2 ~ 21% with average value of 13.9%). The liquid limit (LL) ranged from 15 ~ 31.50 % with mean of 23.32% and the plasticity index (PI) ranged from 2.92~14.42% with mean of 8.95%. The moisture content, permeability, bulk density, porosity, organic matter and pH have average values of 25.31%, 6.04×10-4 cm/sec, 1.55 kg/m3, 40.40, 1.26% and 5.12, respectively. The cation exchange capacity (CEC) is low, which could be attributed to low organic matter, pH and non active clay minerals. With regard to the aforementioned characteristics, the soils at gully sites are loose sands with low amount of fines fraction, hence cohesionless, and are easily exposed to agents/factors of gully erosion. Thus, provides insights about the vulnerable causes of gully erosion and landslides problems that are prevalent in the area. This research addresses, to a great extent the effects of local geology, geotechnical properties of the underlying soil and associated human activities on the formation of gully erosion, in-turn results to landslides within in the study area. Engineering-geologic aspects of soil erosion control were also recommended. Keywords: Afikpo Sub-basin, Geologic conditions, Geotechnical analysis, Gully erosion and Erosion control measures
Monitoring and evaluation of simulated underground coal gasification in an ex-situ experimental artificial coal seam system
In this study, to better simulate underground coal gasification (UCG), an artificial coal seam was constructed to use as a simulated underground gasifier, which comprised coal blocks excavated from the coal seam. This study reports the process and results of three independently designed experiments using coaxial-hole and linking-hole UCG models: (a) a coaxial model using a coaxial pipeline as a gasification channel, (b) a coaxial model using the coaxial pipeline combined with a bottom cross-hole, and (c) a linking-hole model using a horizontal V-shaped cross-hole. In the present work, the fracturing activities and cavity growth inside the reactor were monitored with acoustic emission (AE) technologies. During the process, the temperature profiles, gas production rate, and gas content were measured successively. The results show that AE activities monitored during UCG process are significantly affected by operational variables such as feed gas rate, feed gas content, and linking-hole types. Moreover, the amount of coal consumed during UCG process were estimated using both of the stoichiometric approach and balance computation of carbon (C) based on the product gas contents. A maximum error of less than 10% was observed in these methods, in which the gas leakage was also considered. This demonstrates that the estimated results using the proposed stoichiometric approach could be useful for evaluating energy recovery during UCG
"Per cell" normalization method for mRNA measurement by quantitative PCR and microarrays
BACKGROUND: Transcriptome data from quantitative PCR (Q-PCR) and DNA microarrays are typically obtained from a fixed amount of RNA collected per sample. Therefore, variations in tissue cellularity and RNA yield across samples in an experimental series compromise accurate determination of the absolute level of each mRNA species per cell in any sample. Since mRNAs are copied from genomic DNA, the simplest way to express mRNA level would be as copy number per template DNA, or more practically, as copy number per cell. RESULTS: Here we report a method (designated the "Percellome" method) for normalizing the expression of mRNA values in biological samples. It provides a "per cell" readout in mRNA copy number and is applicable to both quantitative PCR (Q-PCR) and DNA microarray studies. The genomic DNA content of each sample homogenate was measured from a small aliquot to derive the number of cells in the sample. A cocktail of five external spike RNAs admixed in a dose-graded manner (dose-graded spike cocktail; GSC) was prepared and added to each homogenate in proportion to its DNA content. In this way, the spike mRNAs represented absolute copy numbers per cell in the sample. The signals from the five spike mRNAs were used as a dose-response standard curve for each sample, enabling us to convert all the signals measured to copy numbers per cell in an expression profile-independent manner. A series of samples was measured by Q-PCR and Affymetrix GeneChip microarrays using this Percellome method, and the results showed up to 90 % concordance. CONCLUSION: Percellome data can be compared directly among samples and among different studies, and between different platforms, without further normalization. Therefore, "percellome" normalization can serve as a standard method for exchanging and comparing data across different platforms and among different laboratories
Mechanomyographic activity in the human lateral pterygoid muscle during mandibular movement
The activity of the lateral pterygoid muscle has been regarded to be related to the pathological condition of the temporomandibular joint (TMJ) in the craniomandibular disorders. Because the lateral pterygoid muscle is a deep muscle, a needle electrode is necessary for EMG recordings. The purpose of this study was to establish a non-invasive method for the evaluation of muscle activity of the lateral pterygoid muscle using mechanomyogram (MMG). In three male subjects, surface electromyogram (EMG) in the left masseter muscle, left anterior and posterior belly of the temporal muscle, left anterior belly of the digastric muscle and needle EMG of the inferior head of the lateral pterygoid were recorded during mandibular movement tasks simultaneously with the MMG derived from a condenser microphone in the external ear canal. There were significant positive correlations between the needle EMG signal of the lateral pterygoid muscle and the MMG signal for the tasks of static jaw opened position of 30 mm of interincisal distance (p = 0.000, R(2)=0.725), static jaw opened position of 40 mm of interincisal distance (p = 0.000, R(2) = 0.753), 5 mm protruded mandibular position (p = 0.000, R(2) = 0.653), the most protruded mandibular position (p = 0.000, R(2) = 0803). On the contrary, for the task of maximal clenching, there was no significant correlation between the EMG signal of the lateral pterygoid muscle and the MMG signal. These results suggest that the activity of the lateral pterygoid muscle could be evaluated by the MMG signals recorded in the external ear canal, unless jaw closing major muscles show active contraction
Cross-enhancement of ANGPTL4 transcription by HIF1 alpha and PPAR beta/delta is the result of the conformational proximity of two response elements
BACKGROUND: Synergistic transcriptional activation by different stimuli has been reported along with a diverse array of mechanisms, but the full scope of these mechanisms has yet to be elucidated. RESULTS: We present a detailed investigation of hypoxia-inducible factor (HIF) 1 dependent gene expression in endothelial cells which suggests the importance of crosstalk between the peroxisome proliferator-activated receptor (PPAR) β/δ and HIF signaling axes. A migration assay shows a synergistic interaction between these two stimuli, and we identify angiopoietin-like 4 (ANGPTL4) as a common target gene by using a combination of microarray and ChIP-seq analysis. We profile changes of histone marks at enhancers under hypoxia, PPARβ/δ agonist and dual stimulations and these suggest that the spatial proximity of two response elements is the principal cause of the synergistic transcription induction. A newly developed quantitative chromosome conformation capture assay shows the quantitative change of the frequency of proximity of the two response elements. CONCLUSIONS: To the best of our knowledge, this is the first report that two different transcription factors cooperate in transcriptional regulation in a synergistic fashion through conformational change of their common target genes
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