Low-frequency variability enhancement of the midlatitude climate in an eddy-resolving coupled ocean-atmosphere model-part II: ocean mechanisms

This paper investigates the spatial inhomogeneity of the time-averaged, quasigeostrophic, double-gyre circulation response to fixed, realistic, large-scale modes of wind-stress forcing. While the companion paper of this study focused on understanding the anatomy of low-frequency, midlatitude climate variability in an idealised, eddy-resolving coupled model, this paper looked at understanding the nature of the wind-induced ocean gyre response using an ocean-only configuration of the same model. Our analysis revealed two, time-averaged responses to an east–west dipole, wind-stress curl anomaly in the ocean basin. Firstly, wind-stress anomalies in the western ocean basin led to changes in relative strength of the inertial recirculation zones and jet-axis tilt. This is consistent with an advection-dominated, nonlinear adjustment of the ocean gyres to anomalous forcing. Secondly, wind-stress curl anomalies in the eastern ocean basin was found to induce a largely independent response involving meridional shifts of the western boundary current extension (WBCE). The effects of time-averaged advection in this region are weak and the discovery of westward-propagating Rossby waves along the WBCE revealed the response is more akin to a baroclinic Rossby wave adjustment

Low-frequency variability enhancement of the midlatitude climate in an eddy-resolving coupled ocean–atmosphere model. Part I: anatomy

This study investigated the coupling of the wind-driven ocean gyres with the atmospheric westerly jet using an idealised, eddy-resolving, coupled model. An empirical orthogonal function analysis of the low-pass filtered data showed that the ocean gyre variability is dominated by meridional shifts of the western boundary current extension (WBCE) and changes in the strength of the subtropical inertial recirculation zone. On the other hand, the atmospheric potential vorticity (PV) variability is dominated by the growth of standing Rossby wave patterns, while its pressure variability is dominated by a zonally-asymmetric meridional shift of the atmospheric jet. Damping sea surface temperature (SST) variability in the atmosphere was shown to weaken its PV variability and reduce the zonal asymmetry of the jet-shift mode. Singular value decompositions revealed a positive feedback between meridional shifts of the WBCE and the growth of standing Rossby wave disturbances in the atmospheric jet. The atmosphere’s response is controlled by shifts in the meridional eddy heat flux over the SST front which triggers the growth of baroclinic instabilities. This instability growth eventually leads to a large-scale, barotropic pressure response over the eastern ocean basin, or an aforementioned meridional shift of the atmospheric jet. Reduction in the atmospheric resolution inhibits the ability of atmospheric eddies to resolve length scales associated with meridional shifts of the SST front and WBCE. The lack of resolution consequently weakens the influence of ocean gyre variability on the atmospheric jet and reduces the strength of the positive feedback

Low temperature method for the production of calcium phosphate fillers

BACKGROUND: Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to develop a low cristalline material similar to bone in porosity and cristallinity. METHODS: Commercial hydroxyapatite (HAp) and monetite (M) powders are mixed with water and compacted to produce cylindrical samples. The material is processed at a temperature of 37–120 degrees C in saturated steam to obtain samples that are osteoconductive. The samples are studied by X-ray powder diffraction (XRD), Vickers hardness test (HV), scanning electron microscopy (SEM), and porosity evaluation. RESULTS: The X-ray diffractions of powders from the samples show patterns typical of HAp and M powders. After thermal treatment, no new crystal phase is formed and no increase of the relative intensity of the peaks is obtained. Vicker hardness data do not show any relationship with treatment temperature. The total porosity decreases by 50–60% according to the specific thermal treatment. Scanning electron microscopy of the surfaces of the samples with either HAp 80%-M 20% (c) or Hap 50%-M 50% (f), show cohesion of the powder grains. CONCLUSIONS: The dissolution-reprecipitation process is more intesive in manufactured samples (c) and (f), according to Vickers hardness data. The process occurs in a steam saturated environment between 37 degrees and 120 degrees C. (c) (f) manufactured samples show pore dimension distributions useful to cellular repopulation in living tissues

Long-term culture of cholangiocytes from liver fibro-granulomatous lesions

BACKGROUND: Extensive bile duct proliferation is a key feature of the tissue reaction to clinical and experimental forms of liver injury. Experimental infection of mice by Schistosoma mansoni is a well-studied model of liver fibrosis with bile duct hyperplasia. However, the regulatory mechanisms of bile duct changes are not well understood. In this study we report the reproducible isolation of long-term cultures of cholangiocytes from mice livers with schistosomal fibrosis. METHODS: We have isolated a cholangiocyte cell line from Schistosoma-induced liver granulomas using a combination of methods including selective adhesion and isopyknic centrifugation in Percoll. RESULTS: The cell line was characterized by morphological criteria in optical and transmission electron microscopy, ability to form well differentiated ductular structures in collagen gels and by a positive staining for cytokeratin 18 and cytokeratin 19. To our knowledge, this is the first murine cholangiocyte cell line isolated from schistosomal fibrosis reported in the literature. CONCLUSION: After 9 months and 16 passages this diploid cell line maintained differentiated characteristics and a high proliferative capacity. We believe the method described here may be a valuable tool to study bile duct changes during hepatic injury

Deletion of chromosome 4q predicts outcome in Stage II colon cancer patients

Background: Around 30% of all stage II colon cancer patients will relapse and die of their disease. At present no objective parameters to identify high-risk stage II colon cancer patients, who will benefit from adjuvant chemotherapy, have been established. With traditional histopathological features definition of high-risk stage II colon cancer patients is inaccurate. Therefore more objective and robust markers for prediction of relapse are needed. DNA copy number aberrations have proven to be robust prognostic markers, but have not yet been investigated for this specific group of patients. The aim of the present study was to identify chromosomal aberrations that can predict relapse of tumor in patients with stage II colon cancer

SAQC: SNP Array Quality Control

<p>Abstract</p> <p>Background</p> <p>Genome-wide single-nucleotide polymorphism (SNP) arrays containing hundreds of thousands of SNPs from the human genome have proven useful for studying important human genome questions. Data quality of SNP arrays plays a key role in the accuracy and precision of downstream data analyses. However, good indices for assessing data quality of SNP arrays have not yet been developed.</p> <p>Results</p> <p>We developed new quality indices to measure the quality of SNP arrays and/or DNA samples and investigated their statistical properties. The indices quantify a departure of estimated individual-level allele frequencies (AFs) from expected frequencies via standardized distances. The proposed quality indices followed lognormal distributions in several large genomic studies that we empirically evaluated. AF reference data and quality index reference data for different SNP array platforms were established based on samples from various reference populations. Furthermore, a confidence interval method based on the underlying empirical distributions of quality indices was developed to identify poor-quality SNP arrays and/or DNA samples. Analyses of authentic biological data and simulated data show that this new method is sensitive and specific for the detection of poor-quality SNP arrays and/or DNA samples.</p> <p>Conclusions</p> <p>This study introduces new quality indices, establishes references for AFs and quality indices, and develops a detection method for poor-quality SNP arrays and/or DNA samples. We have developed a new computer program that utilizes these methods called SNP Array Quality Control (SAQC). SAQC software is written in R and R-GUI and was developed as a user-friendly tool for the visualization and evaluation of data quality of genome-wide SNP arrays. The program is available online (<url>http://www.stat.sinica.edu.tw/hsinchou/genetics/quality/SAQC.htm</url>).</p