Discharge studies in micromegas detectors in a 150 GeV/c pion beam

A detailed study of several Micromegas detectors prototyped for the COMPASS and CLAS12 experiments is presented. Using a 150 GeV/c pion beam, the discharge probability was measured for several detector variants including bulk and non-bulk Micromegas. A detector equipped with an additional GEM foil as pre-amplification stage was also tested. A resistive coating of the readout strips was found to reduce the amplitude of the discharge by at least two orders of magnitude which was below the detection limit of the experimental setup. The effects of the micro-mesh type and material were investigated as well as the influence of the drift gap. Response in the presence of a 1.5 T transverse magnetic field was also studied. The measurements presented were performed during a RD51 beam test period.     

A novel electron beam-based method for the immobilization of trypsin on poly(ethersulfone) and poly(vinylidene fluoride) membranes

A novel technique for the covalent immobilization of trypsin in a one-step reaction using low-energy electron beam is described. The enzyme immobilization was applied on poly(ethersulfone) and poly(vinylidene fluoride) microfiltration membranes. For this purpose, the membranes were dipped in an aqueous solution of trypsin followed by electron beam treatment.The effect of irradiation conditions on the immobilization was investigated, as well as the resulting membrane properties with respect to enzymatic activity, immobilized enzyme concentration, pure water flux, scanning electron microscopy, and porosimetry. This technique shall provide a simple, inexpensive method for enzyme immobilization on various polymer membranes and offer a tool for the application in enzymatic membrane reactors.     

Optimal sensor locations for nonparametric identification of viscoelastic materials

The problem of optimal sensor locations in nonparametric identification of viscoelastic materials is considered. Sensor locations have previously been assigned in an ad hoc manner, resulting in a sub-optimal experiment design with a comparatively high variance of the estimates. Different scalar criteria of the covariance matrix, connected to A- and D-optimal experiment design, are considered and evaluated. The results indicate that the accuracy of the estimates can be greatly improved by the use of optimally placed sensors. The theoretical study has been verified by experiments. The presented results can be used to design experiments with improved accuracy of the estimates.     

Advances in Modeling Completely Mixed Flow Reactors for Ion Exchange

This work advances the mathematical modeling of ion exchange treatment in completely mixed flow reactors in which there is recycle and regeneration of the ion exchange resin. The most common application of this process is magnetic ion exchange resin to remove dissolved organic carbon from raw drinking water. The motivation for this work was the complex distribution of resin particle ages and sizes that result from the recycle and regeneration processes. The newly developed model uses a single “age-averaged” diffusion equation to represent resin particle age as compared with the previous Monte Carlo model that uses a large number of diffusion equations to represent various resin particle ages. Advantages of the age-averaged model over the Monte Carlo model include a closed-form analytical solution for the steady-state case of the model, advanced numerical techniques used for the nonsteady-state case of the model, and model simulations require much less computational time and yield more accurate results. The age-averaged model is a robust numerical tool that can be used to evaluate a range of treatment scenarios as a result of these advancements.     

Phosphate recovery using hybrid anion exchange: Applications to source-separated urine and combined wastewater streams

There is increasing interest in recovering phosphorus (P) from various wastewater streams for beneficial use as fertilizer and to minimize environmental impacts of excess P on receiving waters. One such example is P recovery from human urine, which has a high concentration of phosphate (200–800 mg P/L) and accounts for a small volume (∼1%) of total wastewater flow. Accordingly, the goal of this study was to evaluate the potential to recover P from source-separated and combined wastewater streams that included undiluted human urine, urine diluted with tap water, greywater, mixture of urine and greywater, anaerobic digester supernatant, and secondary wastewater effluent. A hybrid anion exchange (HAIX) resin containing hydrous ferric oxide was used to recover P because of its selectivity for phosphate and the option to precipitate P minerals in the waste regeneration solution. The P recovery potential was fresh urine > hydrolyzed urine > greywater > biological wastewater effluent > anaerobic digester supernatant. The maximum loading of P on HAIX resin was fresh urine > hydrolyzed urine > anaerobic digester supernatant ≈ greywater > biological wastewater effluent. Results indicated that the sorption capacity of HAIX resin for phosphate and the total P recovery potential were greater for source-separated urine than the combined wastewater streams of secondary wastewater effluent and anaerobic digester supernatant. Dilution of urine with tap water decreased the phosphate loading on HAIX resin. The results of this work advance the current understanding of nutrient recovery from complex wastewater streams by sorption processes.     

Genome-Wide Investigation of Multifocal and Unifocal Prostate Cancer—Are They Genetically Different?

Prostate cancer is widely observed to be biologically heterogeneous. Its heterogeneity is manifested histologically as multifocal prostate cancer, which is observed more frequently than unifocal prostate cancer. The clinical and prognostic significance of either focal cancer type is not fully established. To investigate prostate cancer heterogeneity, the genetic profiles of multifocal and unifocal prostate cancers were compared. Here, we report observations deduced from tumor-tumor comparison of copy number alteration data of both focal categories. Forty-one fresh frozen prostate cancer foci from 14 multifocal prostate cancers and eight unifocal prostate cancers were subjected to copy number variation analysis with the Affymetrix SNP 6.0 microarray tool. With the investigated cases, tumors obtained from a single prostate exhibited different genetic profiles of variable degrees. Further comparison identified no distinct genetic pattern or signatures specific to multifocal or unifocal prostate cancer. Our findings suggest that samples obtained from multiple sites of a single unifocal prostate cancer show as much genetic heterogeneity and variability as separate tumors obtained from a single multifocal prostate cancer.     

Electrical-Impulse-Induced Fracture of Zinc Oxide Varistor Ceramics

When varistors are subject to very short (˜1 μ s), high-current pulses, they occasionally fracture. We attribute the occurrence of fracture to stress waves, created by inertial forces in response to the rapid Joule heating, causing the propagation of preexisting microstructural flaws. The amplitude of the stress oscillation is shown to be proportional to the second derivative of temperature with respect to time which, in turn, is directly related to the rate of increase of power. An upper limit for the magnitude of the peak stress is derived in terms of material parameters, varistor geometry, and the maximum electrical power. From the magnitude of the peak stress, a critical defect size is estimated which will cause fracture under given pulse conditions. Conclusions for the design and testing of varistors are drawn.     

Disseminated tuberculosis of unusual locations

We report a case of disseminated tuberculosis involving the middle ear, the central nervous system, the spine and the lung. The tuberculous epidural abscess and otomastoiditis don't have any specific imaging features. But their coexistence with an other tuberculous involvement might suggest their tuberculous nature. The epidural abscess may result from direct extension from otomastoiditis.     

Music training improves verbal but not visual memory: Cross-sectional and longitudinal explorations in children.

The hypothesis that music training can improve verbal memory was tested in children. The results showed that children with music training demonstrated better verbal but not visual memory than did their counterparts without such training. When these children were followed up after a year, those who had begun or continued music training demonstrated significant verbal memory improvement. Students who discontinued the training did not show any improvement. Contrary to the differences in verbal memory between the groups, their changes in visual memory were not significantly different. Consistent with previous findings for adults (A. S. Chan, Y. Ho, & M. Cheung, 1998), the results suggest that music training systematically affects memory processing in accordance with possible neuroanatomical modifications in the left temporal lobe. (PsycINFO Database Record (c) 2010 APA, all rights reserved)