Lytic and nonlytic mechanism of inactivation of gram-positive bacteria by lysozyme under atmospheric and high hydrostatic pressure

A different behavior was observed in three gram-positive bacteria exposed to hen egg white lysozyme by plate counts and phase-contrast microscopy. The inactivation of Lactobacillus johnsonii was accompanied by spheroplast formation, which is an indication of peptidoglycan hydrolysis. Staphylococcus aureus was resistant to lysozyme and showed no signs of peptidoglycan hydrolysis, and Listeria innocua was inactivated and showed indications of cell leakage but not of peptidoglycan hydrolysis. Under high hydrostatic pressure, S. aureus also became sensitive to lysozyme but did not form spheroplasts and was not lysed. These results suggested the existence of a nonlytic mechanism of bactericidal action of lysozyme on the latter two bacteria, and this mechanism was further studied in L. innocua. Elimination of the enzymic activity of lysozyme by heat denaturation or reduction with beta-mercaptoethanol eliminated this bactericidal mechanism. By means of a LIVE/DEAD viability stain based on a membrane-impermeant fluorescent dye, the nonlytic mechanism was shown to involve membrane perturbation. In the absence of lysozyme, high-pressure treatment was shown to induce autolytic activity in S. aureus and L. innocua.     

Requirements elicitation for virtual actors in collaborative learning environments

This paper reports on the elicitation of requirements for Virtual Actors in Collaborative Virtual Learning Environments (CVLEs). The methodological approach followed involves the phased development of a series of learning environments which are observed in use by parents, children and teachers. The focus of study is on the interactivity and social communication issues that arise in the learning situation. The research uses as its case study the work of the Manchester Museum Education Service with children at Key Stage Level 2 (9–11 years old) of the National Curriculum. The particular learning situation is based on senet, an ancient Egyptian board game from the Museum’s collection of artefacts from the pyramid builders’ town of Kahun. Results are presented of the first phase prototype, a single display groupware system where interactions take place face-to-face in the ‘real-world’ external to the environment. Results are also presented of the second phase prototype, a multi-user groupware environment in which the users are remotely located and interaction is mainly internal to the environment. The paper discusses how the results from these two phases are being used to establish requirements for a CVLE to be developed in the third phase of research.     

Identification and Classification of Driving Behaviour at Signalized Intersections Using Support Vector Machine

When the drivers approaching signalized intersections (onset of yellow signal), the drivers would enter into a zone, where they will be in uncertain mode assessing their capabilities to stop or cross the intersection. Therefore, any improper decision might lead to a right-angle or back-end crash. To avoid a right-angle collision, drivers apply the harsh brakes to stop just before the signalized intersection. But this may lead to a back-end crash when the following driver encounters the former’s sudden stopping decision. This situation gets multifaceted when the traffic is heterogeneous, containing various types of vehicles. In order to reduce this issue, this study’s primary objective is to identify the driving behaviour at signalized intersections based on the driving features (parameters). The secondary objective is to classify the outcome of driving behaviour (safe stopping and unsafe stopping) at the signalized intersection using a support vector machine (SVM) technique. Turning moments are used to identify the zones and label them accordingly for further classification. The classification of 50 instances is identified for training and testing using a 70%–30% rule resulted in an accuracy of 85% and 86%, respectively. Classification performance is further verified by random sampling using five cross-validation and 30 iterations, which gave an accuracy of 97% and 100% for training and testing. These results demonstrate that the proposed approach can help develop a pre-warning system to alert the drivers approaching signalized intersections, thus reducing back-end crash and accidents.

     

Fumigation trials on the application of ethyl formate to wheat, split faba beans and sorghum in small metal bins

Field trials were carried out in Australia with ethyl formate for insect control in wheat (Harden, NSW), split faba beans (Vicia faba) (Two Wells, SA) and sorghum (milo) (Warwick, Qld) in unsealed metal bins normally used to store grain on farms. Liquid ethyl formate was applied as a split dose (a first dose of 85 g t⁻¹ and after 4 h another dose of 85 g t⁻¹) to the top of the grain through a PVC probe (4 cm i.d.×1.2 m). This method of application was chosen to maintain ethyl formate concentrations below the flammability level, reduce vaporisation, maintain an effective concentration of ethyl formate for >10 h and to avoid liquid ethyl formate accumulating at the bottom of the bin. With wheat, the concentration of ethyl formate was maintained at effective levels for about 2 days, all insects at all stages were killed rapidly, and in 5-7 days the residues were reduced to natural levels without aeration. Split faba beans sorbed ethyl formate strongly, the residues persisted longer and complete insect control was achieved. Control was high but not 100% in the sorghum trials. Residues in the sorghum at 10 °C persisted significantly longer than at 20 °C. During application and fumigation, the levels of ethyl formate in the working environment did not exceed a threshold limit value (TLV) of 100 ppm. The field trials have shown that ethyl formate has good potential as a fumigant in unsealed small metal bins as it kills insects rapidly. Residues decreased to natural levels even without aeration after 7 days for wheat and sorghum and 26 days for split faba beans.     

Regression-based synergy of optical, shortwave infrared and microwave remote sensing for monitoring the grain-size of intertidal sediments

A method is developed for monitoring the sediment grain-size of intertidal flats in the Westerschelde (southwest Netherlands), using information from both space-borne microwave (SAR) and optical/shortwave infrared remote sensing. Estimates of the backscattering coefficient were extracted from time-series of C-band ERS SAR imagery. Surface reflectance in the visible, near-infrared (VNIR) and shortwave infrared (SWIR) part of the electromagnetic spectrum, as well as spectral indices, were derived from matching multi-temporal Landsat TM imagery. In addition, surface reflectances were derived from a set of airborne multispectral (VNIR) CASI images, and hyperspectral (VNIR) measurements using a field spectroradiometer. The data were related to matching field measurements of surface characteristics, including sediment properties. Regression-based algorithms were developed to map the spatio-temporal distribution of mud content using (a) the C-band SAR backscattering coefficient, (b) surface reflectance in the green and SWIR, and (c) a combination of these, with corroborative field measurements. Mud content of the sediment has been successfully mapped by all three algorithms, but a combination of information from microwave and VNIR/SWIR provided best results. The algorithms were generally consistent in time, making them suitable for generating time-series and for monitoring. However, they should be validated and calibrated in order to be applicable to other intertidal areas.     

Validation of space-based polarization measurements by use of a single-scattering approximation,with application to the global ozone monitoring experiment

A method is presented for in-flight validation of space-based polarization measurements based on approximation of the direction of polarization of scattered sunlight by the Rayleigh single-scattering value. This approximation is verified by simulations of radiative transfer calculations for various atmospheric conditions. The simulations show locations along an orbit where the scattering geometries are such that the intensities of the parallel and orthogonal polarization components of the light are equal, regardless of the observed atmosphere and surface. The method can be applied to any space-based instrument that measures the polarization of reflected solar light. We successfully applied the method to validate the Global Ozone Monitoring Experiment (GOME) polarization measurements. The error in the GOME's three broadband polarization measurements appears to be approximately 1%.     

A physiological explanation of infants' early visual development.

Proposes a physiological explanation of infants' early visual development based on recent evidence that the cat's visual system contains at least 3 separate pathways that subserve different functions and develop at different rates. Several lines of evidence suggest the same is true in humans. Data from human newborns suggest that at birth, 2 of these pathways (the X-pathway to the cortex and the Y-pathway directly to the superior colliculus and pretecturm) are functional, but that the third, the Y-pathway to the cortex, is not. Striking changes at 2 mo appear to reflect the dawning influence of that Y-pathway to the cortex. (French abstract) (5 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shelf life and safety concerns of bakery products--a review

Bakery products are an important part of a balanced diet and, today, a wide variety of such products can be found on supermarket shelves. This includes unsweetened goods (bread, rolls, buns, crumpets, muffins and bagels), sweet goods (pancakes, doughnuts, waffles and cookies) and filled goods (fruit and meat pies, sausage rolls, pastries, sandwiches, cream cakes, pizza and quiche). However, bakery products, like many processed foods, are subject to physical, chemical and microbiological spoilage. While physical and chemical spoilage limits the shelf life of low and intermediate moisture bakery products, microbiological spoilage by bacteria, yeast and molds is the concern in high moisture products i.e., products with a water activity (a(w)) > 0.85. Furthermore, several bakery products also have been implicated infoodborne illnesses involving Salmonella spp., Listeria monoctyogenes and Bacillus cereus, while Clostridium botulinum is a concern in high moisture bakery products packaged under modified atmospheres. This extensive review is divided into two parts. Part I focuses on the spoilage concerns of low, intermediate and high moisture bakery products while Part II focuses on the safety concerns of high moisture bakery products only. In both parts, traditional and novel methods of food preservation that can be used by the bakery industry to extend the shelf life and enhance the safety of products are discussed in detail.     

"Social cognitions as organizers of autonomic and affective responses to social challenge": Correction.

Reports an error in the original article by D. B. Bugental et al (Journal of Personality and Social Psychology, 1993, Vol 64[1], 94–203). On page 97, the sentence "SCL was measured by bipolar silver-silver chloride electrodes placed on the thumb of the nonpreferred hand' should read as follows: "SCL was measured by bipolar silver-silver chloride electrodes placed on the thenar and hypothenar eminences of the nonpreferred hand.' (The following abstract of this article originally appeared in record 1993-21385-001.) Autonomic and affective responses to children were assessed as a function of adult perceptions of interpersonal control. Women (N?=?160) interacted with and provided feedback to computer-simulated children who behaved responsively or unresponsively on a computer game. Women were categorized as low in perceived control (PC) if they attributed high control to children but low control to self over negative events on the Parent Attribution Test. As predicted, low-PC women were maximally reactive to child characteristics, manifesting peak levels of defensive arousal (increased level of heart rate and electrodermal activity) and negative affect with unresponsive children and minimal levels of arousal and negative affect with responsive children … (PsycINFO Database Record (c) 2010 APA, all rights reserved)