Derivation of revised formulae for eddy viscous forces used in the ocean general circulation model

Presented is a re-derivation of the eddy viscous dissipation tensor commonly used in present oceanographic general circulation models. When isotropy is imposed, the currently-used form of the tensor fails to return to the laplacian operator. In this paper, the source of this error is identified in a consistent derivation of the tensor in both rectangular and earth spherical coordinates, and the correct form of the eddy viscous tensor is presented

Quantification of Myocardial Perfusion in Human Subjects Using 82Rb and Wavelet-Based Noise Reduction

Quantification of myocardial perfusion with 82Rb has been difficult to achieve because of the low signal-to-noise ratio of the dynamic data curves. This study evaluated the accuracy of flow estimates after the application of a novel multidimensional wavelet-based noise-reduction protocol. Methods: Myocardial perfusion was estimated using 82Rb and a two-compartment model from dynamic PET scans on 11 healthy volunteers at rest and after hyperemic stress with dipyridamole. Midventricular planes were divided into eight regions of interest, and a wavelet transform protocol was applied to images and time–activity curves. Flow estimates without and with the wavelet approach were compared with those obtained using H215O. Results: Over a wide flow range (0.45–2.75 mL/g/min), flow achieved with the wavelet approach correlated extremely closely with values obtained with H215O (y = 1.03 x -0.12; n = 23 studies, r = 0.94, P < 0.001). If the wavelet noise-reduction technique was not used, the correlation was less strong (y = 1.11 x + 0.24; n = 23 studies, r = 0.79, P < 0.001). In addition, the wavelet approach reduced the regional variation from 75% to 12% and from 62% to 11% (P < 0.001 for each comparison) for resting and stress studies, respectively. Conclusion: The use of a wavelet protocol allows near-optimal noise reduction, markedly enhances the physiologic flow signal within the PET images, and enables accurate measurement of myocardial perfusion with 82Rb in human subjects over a wide range of flows

Absolute quantitation of coronary steal induced by intravenous dipyridamole

AbstractOBJECTIVESThe study was done to determine whether coronary steal (defined as an absolute decrease in perfusion from resting blood flow) is induced by intravenous (IV) dipyridamole in patients with severe coronary artery disease (CAD).BACKGROUNDMyocardial ischemia during coronary vasodilation is usually attributed to coronary steal. However, there is limited data on the absolute magnitude of coronary steal in humans.METHODSEighteen patients with multivessel CAD underwent dynamic positron emission tomography (PET) imaging with 13NH3at rest and after infusion of IV dipyridamole. Eight myocardial sectors were analyzed per short axis slice and myocardial blood flow calculated with a two-compartment model in absolute terms.RESULTSCoronary steal occurred in 8 of the 18 patients. In the 8 patients with coronary steal, myocardial blood flow decreased from 90 ± 18 ml/100 g/min at rest to 68 ± 27 ml/100 g/min following dipyridamole in the segments with steal, and increased from 87 ± 19 to 138 ± 16 ml/100 g/min following dipyridamole in the segments without steal. Significant clinical correlates of coronary steal were either ST elevation or the combination of ST depression and angina.CONCLUSIONSCoronary vasodilation with IV dipyridamole is associated with significant reductions in blood flow to collateral-dependent myocardium consistent with coronary steal in about 45% of patients with severe CAD

Comparative Geochemistry of 234Th, 210Pb, and 210Po: A Case Study in the Hung-Tsai Trough off Southwestern Taiwan

Detailed profiles of dissolved and particulate 234Th, 210Pb, and 210Po activities at three stations in the Hung-Tsai Trough off south western Taiwan were determined. The total 234Th activ ity is 20 ~ 25% deficientfrom its secular equilibrium in the entire water column. Except for an evident excess of 210Po at some depths in the mixed layer and in the pycnocline layer, total 210Po activity is also lower than total 210Pb activity. As a result of atmospheric deposition, 210Pb is about 25% in excess of its parent, 226Ra, through out the water column of the Hung-Tsai Trough. The ratios of the distribution coefficients of 234Th, 210Pb, and 210Po show that the order of particle affinity is Po > Th ~ Pb in the mixed layer and bottom layer, whereas the order changes, due to particlere generation, into Th > Pb > Po in the pycnocline layer of the Hung-Tsai Trough

Discovery and characterization of medaka miRNA genes by next generation sequencing platform

Background MicroRNAs (miRNAs) are endogenous non-protein-coding RNA genes which exist in a wide variety of organisms, including animals, plants, virus and even unicellular organisms. Medaka (Oryzias latipes) is a useful model organism among vertebrate animals. However, no medaka miRNAs have been investigated systematically. It is beneficial to conduct a genome-wide miRNA discovery study using the next generation sequencing (NGS) technology, which has emerged as a powerful sequencing tool for high-throughput analysis. Results In this study, we adopted ABI SOLiD platform to generate small RNA sequence reads from medaka tissues, followed by mapping these sequence reads back to medaka genome. The mapped genomic loci were considered as candidate miRNAs and further processed by a support vector machine (SVM) classifier. As result, we identified 599 novel medaka pre-miRNAs, many of which were found to encode more than one isomiRs. Besides, additional minor miRNAs (also called miRNA star) can be also detected with the improvement of sequencing depth. These quantifiable isomiRs and minor miRNAs enable us to further characterize medaka miRNA genes in many aspects. First of all, many medaka candidate pre-miRNAs position close to each other, forming many miRNA clusters, some of which are also conserved across other vertebrate animals. Secondly, during miRNA maturation, there is an arm selection preference of mature miRNAs within precursors. We observed the differences on arm selection preference between our candidate pre-miRNAs and their orthologous ones. We classified these differences into three categories based on the distribution of NGS reads. Finally, we also investigated the relationship between conservation status and expression level of miRNA genes. We concluded that the evolutionally conserved miRNAs were usually the most abundant ones. Conclusions Medaka is a widely used model animal and usually involved in many biomedical studies, including the ones on development biology. Identifying and characterizing medaka miRNA genes would benefit the studies using medaka as a model organism

Acetylome of acinetobacter baumannii SK17 reveals a highly-conserved modification of histone-like protein HU

Lysine acetylation is a prevalent post-translational modification in both eukaryotes and prokaryotes. Whereas this modification is known to play pivotal roles in eukaryotes, the function and extent of this modification in prokaryotic cells remain largely unexplored. Here we report the acetylome of a pair of antibiotic-sensitive and -resistant nosocomial pathogen Acinetobacter baumannii SK17-S and SK17-R. A total of 145 lysine acetylation sites on 125 proteins was identified, and there are 23 acetylated proteins found in both strains, including histone-like protein HU which was found to be acetylated at Lys13. HU is a dimeric DNA-binding protein critical for maintaining chromosomal architecture and other DNA-dependent functions. To analyze the effects of site-specific acetylation, homogenously Lys13-acetylated HU protein, HU(K13ac) was prepared by genetic code expansion. Whilst not exerting an obvious effect on the oligomeric state, Lys13 acetylation alters both the thermal stability and DNA binding kinetics of HU. Accordingly, this modification likely destabilizes the chromosome structure and regulates bacterial gene transcription. This work indicates that acetyllysine plays an important role in bacterial epigenetics

Transcriptional regulation of miR-196b by ETS2 in gastric cancer cells

E26 transformation-specific sequence (ETS)-2 is a transcriptional modulator located on chromosome 21, alterations in its expression have been implicated with a reduced incidence of solid tumors in Down syndrome patients. MicroRNAs (miRNAs) are thought to participate in diverse biological functions; however, the regulation of miRNAs is not well characterized. Recently, we reported that miR-196b is highly expressed in gastric cancers. Herein, we demonstrate that miR-196b expression was significantly repressed by ETS2 during gastric cancer oncogenesis. We demonstrate that knockdown of endogenous ETS2 expression increases miR-196b expression. A genomic region between −751 and −824 bp upstream of the miR-196b transcriptional start site was found to be critical for the repression activity. This putative regulatory promoter region contains three potential ETS2-binding motifs. Mutations within the ETS2 binding sites blocked the repression activity of ETS2. Furthermore, knockdown of ETS2 or overexpression of miR-196b significantly induced migration and invasion in gastric cancer cells. In addition, alterations in ETS2 and miR-196b expression in gastric cancer cell lines affected the expression of epithelial–mesenchymal transition-related genes. The levels of vimentin, matrix metalloproteinase (MMP)-2 and MMP9 were drastically induced, but levels of E-cadherin were decreased in shETS2- or miR-196b-transfected cells. Our data indicate that ETS2 plays a key role in controlling the expression of miR-196b, and miR-196b may mediate the tumor suppressor effects of ETS2. We demonstrated that miR-196b was transcriptionally regulated by ETS2 and there was an inverse expression profile between miR-196b and ETS2 in clinical samples. This finding could be beneficial for the development of effective cancer diagnostic and alternative therapeutic strategies

Facile synthesis of a interleaved expanded graphite-embedded sulphur nanocomposite as cathode of Li-S batteries with excellent lithium storage performance

通讯作者地址: Huang, L (通讯作者),Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, Sch Energy Res, Xiamen 361005, Peoples R China 3. Univ Wollongong, Inst Superconducting & Elect Mat, Wollongong, NSW 2522, Australia 电子邮件地址: [email protected]; [email protected] paper reports the facile synthesis of a unique interleaved expanded graphite-embedded sulphur nanocomposite (S-EG) by melt-diffusion strategy. The SEM images of the S-EG materials indicate the nanocomposites consist of nanosheets with a layer-by-layer structure. Electrochemical tests reveal that the nanocomposite with a sulphur content of 60% (0.6S-EG) can deliver the highest discharge capacity of 1210.4 mAh g(-1) at a charge-discharge rate of 280 mA g(-1) in the first cycle, the discharge capacity of the 0.6S-EG remains as high as 957.9 mAh g(-1) after 50 cycles of charge-discharge. Furthermore, at a much higher charge-discharge rate of 28 A g(-1), the 0.6S-EG cathode can still deliver a high reversible capacity of 337.5 mAh g(-1). The high sulphur utilization, excellent rate capability and reduced over-discharge phenomenon of the 0.6S-EG material are exclusively attributed to the particular microstructure and composition of the cathode.NSFC 2093110426 21003102 21021002 20833005 973 program 209CB22010