Direct Numerical Simulation of 3D Salt Fingers: From Secondary Instability to Chaotic Convection

The amplification and equilibration of three-dimensional salt fingers in unbounded uniform vertical gradients of temperature and salinity is modeled with a Direct Numerical Simulation in a triply periodic computational domain. A fluid dynamics video of the simulation shows that the secondary instability of the fastest growing square-planform finger mode is a combination of the well-known vertical shear instability of two-dimensional fingers [Holyer, 1984] and a new horizontal shear mode.Comment: APS DFD Gallery of Fluid Motion 200

Primary and secondary intrusions in double-diffusively stable vertical gradients

The purpose of this paper is to show that molecularly-driven double-diffusive intrusions can produce significant lateral and vertical double-diffusive mixing even when the initial temperature and salinity are both stably stratified in the vertical. Assuming uniform density-compensated horizontal gradients and periodic disturbances, three-dimensional direct numerical simulations (DNS) for the fastest growing intrusion show that the latter equilibrates due to the generation of salt fingers which reduce the driving buoyancy pressure gradient. The DNS also provided statistical data for a new parameterization of the salt finger fluxes which includes the effects of shear and variable vertical gradients. This parameterization makes it feasible to numerically investigate the subharmonic instabilities of the equilibrium DNS solution. Linearized calculations with parameterized salt fingers show that the vertical and horizontal wavelength of the fastest growing secondary instability are approximately three and fourteen times that of the primary intrusion. Nonlinear simulations show that the equilibrium lateral and vertical double-diffusive fluxes of the secondary mode are an order of magnitude larger than those of the primary intrusion. Numerically determined dependences of the intrusion lateral velocity on the vertical wavelength are compared to previous numerical and experimental work

Tactical decisions in the operative treatment of advanced and urgent cases of colorectal cancer

The authors reviewed retrospectively the patients treated in the Clinic of Surgery for colorectal cancer (CRC) during a five-year period (2008-2012). The main purpose was to consider the different tactical decisions for operative treatment in complicated, advanced and urgent cases. There were a total of 706 operated patients who were analyzed according to their age, gender, stage of disease, planned and urgent operative interventions, presence of concomitant diseases, performed operative procedures and mortality rate. The principles of assessment of every different case and those for making decisions for operative tactics and kind of intervention were described. The performed different operations in complicated, advanced and urgent patients were analyzed, too. Conclusions concerning the obtained results and their comparison with literature data available as well as concerning the benefits of differentiated tactical approach to every individual case with CRC were drawn

Tactics of treatment of acute left colon cancer obstruction

Back ground: Advanced colorectal cancer is commonly associated with colon obstruction/between 15-20% of patients with colonic cancer/ or/and tumor infiltration to adjacent organs. We set out to study in-hospital morbidity and mortality after operations of acute left colon cancer obstruction.Methods: From 2000 to 2010 the medical records of 204 cases /15.1%/ of acute left colon cancer obstruction were reviewed from total of 1351 patients who were operated from colorectal cancer. Results: The types of operations were a Hartmann procedure in 78 patients /38.2%/, colostomy in 58 patients /29.4%%, a type of colectomy with ileo-coloanastomosis in 54 patients /26.5%/ and a standard resection in 14 patients /6.8%/. The following early complications were occurred: anastomotic leakage in 4 patients, wound infections in 5 patients, dehiscence of operative wound in 2 patients. The in-hospital mortality rate was 11.3%.Conclusions: The emergency management of acute left-sided colonic obstruction remains controversial. The one-stage resection anastomosis which could be subtotal colectomy or segmental resection is useful and the preferred choice for low risk patients. Simple colostomy or Hartmann procedure should be re served for high risk patients. Colonic stenting is the best option either for palliation or as a bridge to surgery

Prototype performance evaluation of multimedia service components

This paper deals with a formal approach for decomposition and description of multimedia service components and their performance analysis. Our approach is based on the Temporal Logic of Actions (TLA) specifications. A TLA based specification of multimedia components is transformed into process prototypes described with the SPIMS (SICS Protocol Implementation Measurement System) application language. The multimedia component prototype derived in this way is then evaluated with the SPIMS tool for different QoS parameters. The proposed approach using TLA based specifications, transformations in SPIMS application prototypes, and performance analysis provides the background for an computer based system for test specification and performance analysis which is currently under development. We present and discuss practical test scenarios derived from the proposed method for performance analysis of the Audio-Visual Communication (AVC)component of the Joint-Viewing and Tele-Operation Service (JVTOS). The multimedia test scenarios shown use the TCP/IP and XTP protocols on top of FORE ATM networks

Fragment-based discovery of a regulatory site in thioredoxin glutathione reductase acting as "doorstop" for NADPH entry

Members of the FAD/NAD-linked reductase family are recognized as crucial targets in drug development for cancers, inflammatory disorders, and infectious diseases. However, individual FAD/NAD reductases are difficult to inhibit in a selective manner with off target inhibition reducing usefulness of identified compounds. Thioredoxin glutathione reductase (TGR), a high molecular weight thioredoxin reductase-like enzyme, has emerged as a promising drug target for the treatment of schistosomiasis, a parasitosis afflicting more than 200 million people. Taking advantage of small molecules selected from a high-throughput screen and using X-ray crystallography, functional assays, and docking studies, we identify a critical secondary site of the enzyme. Compounds binding at this site interfere with well-known and conserved conformational changes associated with NADPH reduction, acting as a doorstop for cofactor entry. They selectivity inhibit TGR from Schistosoma mansoni and are active against parasites in culture. Since many members of the FAD/NAD-linked reductase family have similar catalytic mechanisms the unique mechanism of inhibition identified in this study for TGR broadly opens new routes to selectively inhibit homologous enzymes of central importance in numerous diseases

Firefly luciferase in chemical biology: A compendium of inhibitors, mechanistic evaluation of chemotypes, and suggested use as a reporter

Firefly luciferase (FLuc) is frequently used as a reporter in high-throughput screening assays owing to the exceptional sensitivity, dynamic range, and rapid measurement that bioluminescence affords. However, interaction of small molecules with FLuc has, to some extent, confounded its use in chemical biology and drug discovery. To identify and characterize chemotypes interacting with FLuc, we determined potency values for 360,864 compounds, found in the NIH Molecular Libraries Small Molecule Repository, available in PubChem. FLuc inhibitory activity was observed for 12% of this library with discernible SAR. Characterization of 151 inhibitors demonstrated a variety of inhibition modes including FLuc-catalyzed formation of multisubstrate-adduct enzyme inhibitor complexes. As in some cell-based FLuc reporter assays compounds acting as FLuc inhibitors yield paradoxical luminescence increases, data on compounds acquired from FLuc-dependent assays requires careful analysis as described in this report