Escherichia coli O157:H7 in retail ground beef in Seattle: results of a one-year prospective study

Escherichia coli O157:H7 was sought systematically in 1,400 samples of retail ground beef in Seattle in a 1-year prospective study. Sorbitol-nonfermenting, lactose-fermenting, indole-positive colonies isolated after enrichment culture were probed for the presence of Shiga toxin genes. Totals of 67,040 sorbitol-nonfermenting and 66,705 sorbitol-fermenting colonies were characterized, but E. coli O157:H7 was not identified. The sensitivity of this technique was usually sufficient to detect E. coli O157:H7 at a concentration below 1 CFU/g of meat. These data demonstrate that retail ground beef in Seattle is neither frequently nor heavily contaminated with E. coli O157:H7.     

Adaptive Cooperative Decode-and-Forward Transmission with Power Allocation Under Interference Constraint

In this paper, we examine an adaptive decode-and-forward cooperative protocol under interference constraint. In the proposed protocol, relying on the obtained instantaneous signal-to-noise ratios (SNRs), a direct link or relay link is used to transmit data from the secondary source to the secondary destination. In addition, once the relay link is used, the secondary source and relay must adapt their transmit power to maximize the instantaneous SNR of this link. To evaluate the performance of the proposed protocol, we derive closed-form lower-bound and upper-bound expressions for the outage probability over Rayleigh fading channel. Finally, various Monte-Carlo simulations are presented to verify our analysis and compare the performance of the proposed protocol with that of the direct transmission protocol in underlay cognitive network.     

Structural Characterization and Magnetic and Electrical Properties of La0.7Ca0.3MnO3–La1.5Sr0.5NiO4 Nanocomposites

Nanocomposite samples of (1 ? x)La_0.7Ca_0.3MnO₃ + xLa_1.5Sr_0.5NiO₄ (x = 0 to 0.3) were synthesized by a combination of the mechanical milling and solid-state reaction methods. X-ray diffraction analyses and magnetic measurements indicated that no reaction occurred between La_0.7Ca_0.3MnO₃ (LCMO) and La_1.5Sr_0.5NiO₄ (LSNO). The Curie temperature (T _C) was almost independent of x, while the metal–insulator transition temperature (T _MI) shifted from 251 K for x = 0.0 to 65 K for x = 0.2. The samples with x ≥ 0.25 exhibited insulating behavior in the temperature range from 30 K to 300 K. Addition of LSNO substantially increased the resistivity of the composites. This is attributed to enhanced magnetic disorder at LCMO grain boundaries due to the addition of LSNO. The temperature dependence of the resistivity, ρ(T), could be described by the phenomenological percolation model of phase segregation. Fitting the experimental ρ(T) data in the temperature range of 30 K to 300 K indicated that the activation energy of the composites increases as a function of the LSNO doping concentration (x).     

Schottky barrier characteristics of Pt contacts to all sputtering-made n-type GaN and MOS diodes

All sputtering-made Pt/n-GaN [metal–semiconductor (MS)] and Pt/SiO₂/n-GaN [metal–oxide–semiconductor (MOS)] diodes were investigated before and after annealing at 500 °C. n-GaN, Pt, and SiO₂ films were all fabricated by the cost-effective radio-frequency sputtering technique. A cermet target was used for depositing GaN. The Schottky barrier heights (SBHs) of both MS and MOS Schottky diodes have been investigated by the current–voltage (I–V) measurements. The results showed that SBHs increased after annealing at 500 °C for 20 min in N₂ ambient, compared to the as-deposited at 400 °C. By using Cheung’s and Norde methods, the highest SBHs of MOS Schottky diodes were respectively found to be 0.79 and 0.91 eV for the as-deposited and had reached to 0.81 and 0.94 eV after annealing. The annealed Schottky diode had showed the higher SBH, lower leakage current, smaller ideality factor, and denser microstructure.     

Zernike moment and local distribution fitting fuzzy energy-based active contours for image segmentation

This paper presents a new region-based active contour model for extracting the object boundaries in an image, based on techniques of curve evolution. The proposed model introduces an energy functional that involves intensity distributions in local image regions and fuzzy membership functions. The local image intensity distribution information used to guide the motion of the contour, in the paper, is derived by Hueckel operator in the neighborhood of each image point. The parameters of Hueckel operator are estimated by a set of orthogonal Zernike moments before curve evolution. Meanwhile, the fuzzy membership functions are used to measure the association degree of each image pixel to the region outside and inside the contour. To minimize the energy functional, instead of solving the Euler–Lagrange equation of the underlying problem, the paper employs a direct method to compute the energy alterations. As a result, the model can deal with images with intensity inhomogeneity. In addition, the model effectively alleviates the sensitivity to contour initialization. Moreover, the model reduces computational cost, avoids problems associated with choosing time steps as well as allows fast convergence to the segmentation solutions. Experimental results on synthetic, real images and comparisons with other models show the desired performances of the proposed model.     

Lapped transform via time-domain pre- and post-filtering

This paper presents a general framework of constructing a large family of lapped transforms with symmetric basis functions by adding simple time-domain pre- and post-processing modules onto existing block discrete cosine transform (DCT)-based infrastructures. A subset of the resulting solutions is closed-form, fast computable, modular, near optimal in the energy compaction sense and leads to an elegant boundary handling of finite-length data. Starting from these solutions, a general framework for block-based signal decomposition with a high degree of flexibility and adaptivity is developed. Several simplified models are also introduced to approximate the optimal solutions. These models are based on cascades of plane rotation operators and lifting steps, respectively. Despite tremendous savings in computational complexity, the optimized results of these simplified models are virtually identical to that of the complete solution. The multiplierless versions of these pre- and post-filters when combined with an appropriate multiplierless block transform, such as the binDCT, which is described in an earlier paper by Liang and Tran (see IEEE Trans. Signal Processing, vol.49, p.3032-44, Dec. 2001), generate a family of very large scale integration (VLSI)-friendly fast lapped transforms with reversible integer-to-integer mapping. Numerous design examples with arbitrary number of channels and arbitrary number of borrowed samples are presented.     

Extraction of Pentosans from Wheat Flour with Trichloroacetic Acid Solutions

Pentosans were extracted from wheat flour with 15% trichloroacetic acid (TCA) at 2°C. The TCA was extracted with ether and the aqueous solution dialyzed, centrifuged and lyophilized. Subfractions obtained by fractionation on Sepharose 6B and by ammonium sulfate precipitation were analyzed for carbohydrates, protein and hydroxyproline. The pentosans contained a high molecular weight component having only arabinose and galactose as monosaccharides, and 4.4% protein, of which 3% w/w was hydroxyproline.     

Stabilization of acidic soy protein-based dispersions and emulsions by soy soluble polysaccharides

Soy soluble polysaccharides (SSPS) are shown to prevent destabilization of soy protein isolate (SPI) dispersions and SPI-based oil-in-water (O/W) emulsions under acidic conditions. Addition of SSPS above a critical concentration (0.25 wt%) increased the stability of 0.50 wt% SPI dispersions against aggregation and phase separation under conditions where SPI would normally precipitate (near its isoelectric point). Though SSPS neutralized SPI surface charge via electrostatic interaction, there was increased stability against aggregation due to steric repulsion. At acidic pH, addition of 1 wt% NaCl electrostatically screened protein–polysaccharide complexation which led to SPI precipitation and sedimentation. However, the order of salt addition had a significant impact on charge screening, with salt added before pH adjustment reducing SPI–SSPS complexation whereas it had less effect when added afterwards. Salt penetration efficacy diminished with decreasing pH. O/W emulsions (5 wt% oil) prepared with 0.50 wt% SPI destabilized at pH 4–5 due to protein aggregation, but addition of ≥0.25 wt% SSPS improved emulsion stability by inhibiting protein–protein interactions thus limiting increases in oil droplet diameter over time. Overall, both dispersion and emulsion stability greatly depended on pH, ionic strength and SSPS concentration. These results demonstrated that SSPS could effectively stabilize acidic SPI dispersions and that SPI–SSPS interactions may be used as a tool to improve the kinetic stability of SPI-based O/W emulsions.     

Intestinal parasite infections in a periurban community from the Province of Buenos Aires, Argentina

A survey for intestinal parasites was performed on 38 individuals within the urban area of La Plata City (Province of Buenos Aires, Argentina). This community is composed of brick-factory workers who also live in the factory premises. An analysis for intestinal parasites was done on fecal samples collected serially and by means of anal swabs and thereafter preserved in formol solution. At the same time, the occurrence of the parasites under study as well as that of commensal organisms was investigated in water and soil samples within the factory environs. Information was also obtained from the members of this community as their age, sex, birthplace, and recent travels, either abroad or to the interior of Argentina. The prevalence of the pathogens and commensal parasites was 89.5%. The frequency of protozoans and helminths was: G. lamblia 26.3%, B. hominis 65.8%, A. lumbricoides 7.9%, H. nana 2.6%, Uncinaria sp. 7.9%, S. stercoralis 2.6% and E. vermicularis 42.1%. None of these parasite or commensal organisms were present in the water samples investigated. Four out of 20 soil samples analyzed contained parasitic elements: T. canis eggs (one), G. lamblia cysts (two) and A. lumbricoides eggs (one). These results indicated that most important factors causing such a high prevalence of coproparasites were the poor conditions of personal and community hygiene in combination with the frequent travels to the north and the northeast of the country, regions which are endemic parasitic areas. The implementation of programs on health education and communal sanitation would contribute in the control of this health problem.     

Moraxella catarrhalis: pathogenic significance in respiratory tract infections treated by community practitioners

We prospectively studied the pathogenic significance of Moraxella (Branhamella) catarrhalis isolated from 212 patients of community practitioners in Australia. This organism was most commonly isolated during winter and early spring, and 92% of isolates were beta-lactamase producers. On the basis of predetermined clinical and microbiological criteria, 42% of the isolates were definitely pathogenic, 7% were probably pathogenic, 21% were of indeterminate pathogenicity, and 30% were nonpathogenic. Factors associated with pathogenic significance included pneumonia or bronchitis (87% of patients), predisposing respiratory or systemic conditions (62%), isolation from sputum, and pure isolation. Thirty-six percent of patients were < 5 years old, but only 9% of isolates from these patients were pathogenic or probably pathogenic, a finding that reflects the fact that nasal-swab and nasopharyngeal-aspirate sampling is a common practice. Isolates from older patients were more likely to be pathogenically significant. An assessment of the pathogenic significance of M. catarrhalis isolated from a patient in a community practice should take into consideration factors such as the patient's age, clinical illness, and underlying conditions; the presence of other organisms; and the source of the isolate.