Genetic homogeneity among Listeria monocytogenes strains from infected patients and meat products from two geographic locations determined by phenotyping,ribotyping and PCR analysis of virulence genes

Thirty Listeria monocytogenes isolates from human patients and foods originated from two different geographic locations without any epidemiological relations were analyzed for their genotypic and phenotypic virulence gene expressions and genetic relatedness. All strains contained virulence genes, inlA, inlB, actA, hlyA, plcA and plcB, with expected product size in PCR assay except for the actA gene. Some strains produced actA gene product of 268 and others 385 bp. Phenotypically, all were hemolytic but showed variable expressions of phospholipase activity. Ribotyping classified isolates into 12 different groups based on the similarity to DuPont Identification numbers (DID), which consisted primarily of clinical or food isolates or both. Cluster analysis also indicated possible existence of clones of L. monocytogenes that are found in food or human hosts or are evenly distributed between these two. Two isolates (F1 from food and CHL1250 from patient) had unique ribotype patterns that were not previously reported in the RiboPrinter database. This study indicates distribution of diverse L. monocytogenes strains in clinical and food environments. The isolates showed 92-99% genetic homogeneity, in spite of their origins from two different geographic locations and environments.     

An integrated micro cooling system for electronic circuits

A fully FR4-compatible integrated cooling system has been developed. Cooling channels have been etched into a thick copper layer to form microchannels. The structure is reinforced by two prepreg layers toward the component and solder side. Several cooling channels can be independently run. The heat dissipation capability of the system is 20 W per channel (and heat source). Typical coolants are water or methoxynonafluorobutane. For an outlet to inlet temperature difference of 25°C and a power dissipation of 30 W, a (water) flow rate of 20 ml/min is required. Pressure losses are below 300 mbar (for water)     

The Role of Scale Stresses in the Sulfidation of Steels

Several high-temperature processes in chemical,petrochemical, and energy-processing industry arecharacterized by H₂S-containing atmospheres,confronting engineers with severe corrosion attack ofthe metallic components. Sulfidation is observed onmaterials used for heat exchangers within theheat-recovery zones. The damage is originated not onlyby the relatively fast growth rates of the sulfidescales, but is also due to the loss of their limitedprotective effect by cracking. Scale failure, as aconsequence of stresses generated during scale growthand by temperature changes, was investigated on a carbon steel, a low-chromium steel (1Cr-0.4Mo, T12),a ferritic-chromium steel (12Cr-1Mo), and on austeniticsteel (18Cr-9Ni, AISI 321). The experiments in thetemperature range 400-600°C (700°C), withsubsequent cooling to ambient temperature, wereaccompanied by acoustic-emission measurements in orderto detect scale cracking. Critical parameters for scalefailure are presented.     

A number-needed-to-treat analysis of the use of respiratory syncytial virus immune globulin to prevent hospitalization

OBJECTIVES: To estimate how many infants in selected high-risk subgroups would require treatment with respiratory syncytial virus immune globulin (RSV-IG) to avoid 1 hospital admission and to determine whether this is economically justified. DESIGN: Cost-benefit analysis. Data from 3 randomized controlled trials of RSV-IG are used to estimate the number needed to treat to prevent 1 hospital admission for respiratory syncytial virus infection. The threshold number needed to treat is computed according to a formula incorporating costs and benefits of RSV-IG prophylaxis. Estimates of the willingness to pay were obtained from a sample of 39 health care providers (35 physicians and 4 nurses). MAIN OUTCOME MEASURES: The number needed to treat to prevent 1 hospital admission for respiratory syncytial virus infection. The threshold number needed to treat that would balance costs with benefits. RESULTS: More than 16 (95% confidence interval, 12.5-23.8) infants would need to be treated with RSV-IG to avoid 1 hospital admission for respiratory syncytial virus infection, ranging from 63 for premature infants without chronic lung disease to 12 (confidence interval, 6.3-100.0) for infants with bronchopulmonary dysplasia. A sensitivity analysis of the costs and values of hospital admission for respiratory syncytial virus infection and RSV-IG treatment resulted in a weak recommendation against the treatment of infants with bronchopulmonary dysplasia and strong recommendations that the costs and risks of RSV-IG treatment outweigh the benefits for the combined sample of infants and premature infants without lung disease. CONCLUSIONS: The number-needed-to-treat procedures offer a method to assess evidence of treatment effects and decision rules for whether to accept treatment recommendations. Under plausible assumptions, treatment with RSV-IG is not recommended for infants without lung disease. Institutions can examine cost and benefit assumptions that best fit their own practice setting.     

HCS: A New Local Search Strategy for Memetic Multiobjective Evolutionary Algorithms

In this paper, we propose and investigate a new local search strategy for multiobjective memetic algorithms. More precisely, we suggest a novel iterative search procedure, known as the Hill Climber with Sidestep (HCS), which is designed for the treatment of multiobjective optimization problems, and show further two possible ways to integrate the HCS into a given evolutionary strategy leading to new memetic (or hybrid) algorithms. The pecularity of the HCS is that it is intended to be capable both moving toward and along the (local) Pareto set depending on the distance of the current iterate toward this set. The local search procedure utilizes the geometry of the directional cones of such optimization problems and works with or without gradient information. Finally, we present some numerical results on some well-known benchmark problems, indicating the strength of the local search strategy as a standalone algorithm as well as its benefit when used within a MOEA. For the latter we use the state of the art algorithms Nondominated Sorting Genetic Algorithm-II and Strength Pareto Evolutionary Algorithm 2 as base MOEAs.      

Easy and effective stabilisation measure for fast recursive least squares algorithms for adaptive transversal filters

Fast recursive least squares (FRLS) algorithms are known for their favourable convergence characteristics. They are of special interest for the fast adaptation of transversal filters of high order N. Unfortunately FRLS algorithms have a tendency towards numeric instability. A new and effective stabilisation measure is presented for a 0(7N) FRLS algorithm which needs only one additional multiplication per iteration step.<>     

Modified fast exact NLMS adaptive algorithm

A novel method for efficiently implementing the fast exact NLMS (FENLMS) algorithm is proposed. The method is based on partitioning the algorithm into an `updating' part and a `fixed' filtering part, leading to a uniform distribution and a significant reduction in the number of arithmetic operations within the block. Its application is illustrated on the basis of some simulation results dealing with the identification of an acoustic room impulse response     

Epidemiology and molecular identification of Salmonella infections in children

OBJECTIVE: To explore the role of foods and the environment in the development of infections with Salmonella in infants and children. DESIGN: Case-controlled survey and the use of pulsed-field gel electrophoresis to establish DNA fingerprint patterns. SETTING: Ambulatory and hospitalized patients at a children's hospital. PATIENTS OR OTHER PARTICIPANTS: A consecutive sample of children younger than 4 years old who were infected with Salmonella and 3 age-matched controls per patient were to be surveyed. Of the 103 eligible cases of salmonellosis, 90 cases and 264 controls were included in the study. DATA ANALYSIS: Univariate analysis was done using the Mantel-Haenszel chi2 test or the Fisher exact test. The Bonferroni correction was used for multiple comparisons. DNA fingerprints were inspected for identical banding. RESULTS: Results demonstrated similar diets between cases and controls with the exception of more potato or macaroni salad or coleslaw consumption in the control group (P<.001). DNA fingerprints of Salmonella newport and Salmonella typhimurium demonstrated that all cases were due to unique isolates except in 5 instances involving 12 patients. Seven of these patients could be connected geographically. CONCLUSIONS: Most of the cases of salmonellosis in children younger than 4 years are of a sporadic nature and the major source of infection remains unidentified. For patients infected with identical isolates of Salmonella, a common food source could not be incriminated with the methods used. Environmental contamination or other sources of Salmonella are suggested by these epidemiological data.     

Cracking and Healing of Oxide Scales on Ti-Al Alloys at 900°C

The behavior of oxide scales on Ti-50Al andTi-50Al-2Nb (at.%) was investigated in constantstrain-rate tensile tests at 900°C in air. Thestrain rates ranged between 1 × 10^-9sec^-1 and 3 × 10^-4sec^-1. The tests were accompanied byacoustic-emission measurements in order to detectscale-cracking processes during deformation. Thecritical strains to scale cracking amounted to 0.12-0.5%for the scales on TiAl and 0.17-0.58% for Ti-50Al-2Nb. Thesevalues were found to depend strongly on the size of thepores in the scales and, by using a fracturemechanics-based model, the results for the criticalstrains could be condensed into a narrow scatterband,which is independent of the applied strain rate. Healingof scale cracks was found for strain rates below 1.5× 10^-6 sec^-1 (Ti-Al) and 1.9× 10^-4 sec^-1 (Ti-Al-Nb), respectively. It turned out that the healingprocess is dominated by TiO₂ growth. In alater healing stage, the originalAl₂O₃ barrier is, however,restored in the scale on Ti-50Al. For Ti-50Al-2Nb, an Al₂O₃ layer is found onthe former scale-crack contours. The healing process isalso described by a quantitative model. As a generalconclusion from the investigations, it turned out thatcritical strains to oxide-scale cracking can be estimated fromjust simple oxidation experiments without sophisticatedmechanical testing if the microstructural parameters ofthe scale are determined quantitatively as a function of oxidation time by metallographicmeans.     

Identification of organic solvents by a virtual multisensor system with hierarchical classification

To improve the selectivity of semiconductor gas sensors, temperature modulation is often used. We present a study showing the potential of this technique with information gained comparable to multisensor systems. A dynamic operating mode coupled with a low-complexity evaluation strategy allows the identification of six organic solvent vapors over a wide concentration range (2-200 ppm) with a single sensor, for example, for leak detection systems. The system features low false alarm rates; in addition, interference by other gases, such as CO or NO/sub 2/, can be suppressed. For even higher identification power, switching on-line between different temperature cycles was studied, which provides better information for critical decisions.