On the Eigenvalue Density of Real and Complex Wishart Correlation Matrices

Wishart correlation matrices are the standard model for the statistical analysis of time series. The ensemble averaged eigenvalue density is of considerable practical and theoretical interest. For complex time series and correlation matrices, the eigenvalue density is known exactly. In the real case, however, a fundamental mathematical obstacle made it forbidingly complicated to obtain exact results. We use the supersymmetry method to fully circumvent this problem. We present an exact formula for the eigenvalue density in the real case in terms of twofold integrals and finite sums.Comment: 4 pages, 2 figure

An optimized strategy to measure protein stability highlights differences between cold and hot unfolded states

Macromolecular crowding ought to stabilize folded forms of proteins, through an excluded volume effect. This explanation has been questioned and observed effects attributed to weak interactions with other cell components. Here we show conclusively that protein stability is affected by volume exclusion and that the effect is more pronounced when the crowder's size is closer to that of the protein under study. Accurate evaluation of the volume exclusion effect is made possible by the choice of yeast frataxin, a protein that undergoes cold denaturation above zero degrees, because the unfolded form at low temperature is more expanded than the corresponding one at high temperature. To achieve optimum sensitivity to changes in stability we introduce an empirical parameter derived from the stability curve. The large effect of PEG 20 on cold denaturation can be explained by a change in water activity, according to Privalov's interpretation of cold denaturation

EDTA and Taurolidine Affect Pseudomonas aeruginosa Virulence In Vitro-Impairment of Secretory Profile and Biofilm Production onto Peritoneal Dialysis Catheters

Peritoneal catheter-associated biofilm infection is reported to be the main cause of refractory peritonitis in peritoneal dialysis patients. The application of antimicrobial lock therapy, based on results on central venous catheters, may be a promising option for treatment of biofilm-harboring peritoneal catheters. This study investigated the effects of two lock solutions, EDTA and taurolidine, on an in vitro model of Pseudomonas aeruginosa biofilm-related peritoneal catheter infection. Silicone peritoneal catheters were incubated for 24 h with a bioluminescent strain of P. aeruginosa. Then, serial dilutions of taurolidine and/or EDTA were applied (for 24 h) once or twice onto the contaminated catheters, and P. aeruginosa viability/persistence were evaluated in real time up to 120 h using a Fluoroskan reader. On selected supernatants, high-performance liquid chromatography mass spectrometry (HPLC-MS) analysis was performed to measure the production of autoinducers (AI), phenazines, and pyocyianines. Taurolidine alone or in combination with EDTA caused a significant decrease of bacterial load and biofilm persistence on the contaminated catheters. The treatment did not lead to the sterilization of the devices, yet it resulted in a substantial destructuration of the catheter-associated P. aeruginosa biofilm. HPLC-MS analysis showed that the treatment of biofilm-harboring catheters with taurolidine and EDTA also affected the secretory activity of the pathogen. EDTA and taurolidine affect P. aeruginosa biofilm produced on peritoneal catheters and profoundly compromise the microbial secretory profile. Future studies are needed to establish whether such lock solutions can be used to render peritoneal catheterrelated infections more susceptible to antibiotic treatment

Microbioreactor (micro-Matrix) potential in aerobic and anaerobic conditions with different industrially relevant microbial strains

Microscale fermentation systems are important high throughput tools in clone selection, and bioprocess set up and optimization, since they provide several parallel experiments in controlled conditions of pH, temperature, agitation, and gas flow rate. In this work we evaluated the performance of biotechnologically relevant strains with different respiratory requirements in the micro-Matrix microbioreactor. In particular Escherichia coli K4 requires well aerated fermentation conditions to improve its native production of chondroitin-like capsular polysaccharide, a biomedically attractive polymer. Results from batch and fed-batch experiments demonstrated high reproducibility with those obtained on 2 L reactors, although highlighting a pronounced volume loss for longer-term experiments. Basfia succiniciproducens and Actinobacillus succinogenes need CO2 addition for the production of succinic acid, a building block with several industrial applications. Different CO2 supply modes were tested for the two strains in 24 h batch experiments and results well compared with those obtained on lab-scale bioreactors. Overall, it was demonstrated that the micro-Matrix is a useful scale-down tool that is suitable for growing metabolically different strains in simple batch process, however, a series of issues should still be addressed in order to fully exploit its potential

the use of poly lactic acid to improve projection of reconstructed nipple

Abstract Purpose Nipple-areola reconstruction represents an important step for final mammary reconstruction. Many techniques have been described. The drawback is the progressive nipple projection loss with time from 50% to over 70% of the initial projection. In this report, we evaluated the effect of injectable poly-lactic acid (PLLA) to improve projection of reconstructed nipples. Results We selected 12 patients with a residual nipple projection between 0.1 and 2 mm. The patients were injected locally inside the nipple with 0.5 ml of PLLA (dilution 1:4) every 4 weeks for 4 times. At the study end, patients were satisfied with results. No adverse effects were observed. After one year, an increase of nipple projection ranging from 0.5 to 3.5 mm was obtained with an average increase of 2.3 mm (282%) and this variation was statistically significant ( p Conclusion The use of injectable PLLA is a simple and effective procedure to improve projection of reconstructed nipple

Parametrical analysis of the degradation of gas phase trichloroetylene in a photocatalytic reactor with titanium dioxide coated glass fiber meshes

El estudio de la degradación de Tricloroetileno (TCE) en aire en un reactor fotocatalítico con dióxido de titanio depositado sobre un lecho fijo ha permitido obtener en un trabajo previo, una expresión cinética que contempla la influencia de la concentración del contaminante, la Radiación Incidente y el efecto competitivo del agua y el TCE por los sitios activos del catalizador(1). En este trabajo se resuelve numéricamente la ecuación diferencial en derivadas parciales de transferencia de materia en un reactor fotocatalítico constituido por mallas de vidrio con dióxido de titanio depositado e irradiadas mediante radiación UV. Esta solución numérica evita la introducción de un coeficiente de transferencia de materia sobre la superficie catalítica, obtenido a partir de correlaciones típicas para interfaces gas-sólido bajo el régimen de flujo correspondiente(2,3). Modificando los parámetros relevantes del sistema resulta posible simular el comportamiento del reactor bajo distintas condiciones de operación.The analysis of Trichloroethylene (TCE) degradation in air in a photocatalytic reactor with titanium dioxide coated on a fixed bed has provided in a previous work, a Kinetic expression which takes into account the pollutant concentration, the Incident Radiation and the competition between water and TCE for the photocatalytic active sites(1). In this work, the numerical solution of the mass transfer partial differential equation in a photocatalytic reactor with glass fiber meshes coated with titanium dioxide and UV irradiated is accomplished. This numerical solution avoids the use of a mass transfer coefficient over the catalytic surface, obtained by means of typical correlations for gas-solid interfaces under the correspondent flow regime(2,3). Changing the relevant system parameters, it is possible to simulate the reactor behaviour under different operation conditions.Fil: Esterkin, C. R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Negro, Antonio Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Cassano, Alberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin