Antibiotic resistance of coagulase-negative staphylococci associated with food and used in starter cultures

The resistance of 330 coagulase-negative staphylococci (CNS) associated with food or used in starter cultures and belonging to the species Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus piscifermentans, Staphylococcus equorum, Staphylococcus succinus and Staphylococcus xylosus, against 21 antibiotics was determined using the disk diffusion method. The incidence and number of resistances was found to be species and source of isolation dependent. Most strains of S. equorum (63%), S. succinus (90%) and S. xylosus (95%) exhibited resistances against up to seven antibiotics, whereas only few strains of S. carnosus (12%) and S. piscifermentans (27%) were antibiotic resistant. Resistances to lincomycin, penicillin, fusidic acid, oxacillin, ampicillin and tetracycline were predominant. Among strains of S. xylosus, the incidence of resistance ranged from 22% for tetracycline up to 69% for penicillin. Concerning the source of isolation, resistances were often determined in strains of S. equorum, S. succinus and S. xylosus isolated from cheese (87%) and sausage (83%), and strains of S. xylosus obtained from meat starter cultures (93%). Remarkably, all CNS were sensitive to the clinically important antibiotics chloramphenicol, clindamycin, cotrimoxazol, gentamicin, kanamycin, linezolid, neomycin, streptomycin, synercid and vancomycin. The phenotypic resistances to ss-lactam antibiotics, lincomycin and tetracycline were verified by PCR amplification and could be traced back to the genes blaZ, lnuA and tetK, respectively. This study permitted a comprehensive insight into the incidence of antibiotic resistances in food-associated CNS.     

Thermogravimetric analysis as a new method to determine the lignocellulosic composition of biomass

Biomass energy uses organic matter such as wood or plants - lignocellulosic biomass - for creating heat, generating electricity and producing green oil for cars. Modern biomass energy recycles organic leftovers from forestry and agriculture, like corn stovers, rice husks, wood waste and pressed sugar cane, or uses special, fast-growing “energy crops” like willow and switchgrass, as fuel. Biomass is composed of three major components: cellulose, hemicelluloses, and lignin. Their differences in chemical structures lead to different chemical reactivities, making the relative composition in cellulose, hemicelluloses and lignin in the biomass a crucial factor for process design. In this paper thermogravimetric analysis is investigated as a new method to obtain lignin, hemicellulose and ??-cellulose contents in biomass. It is shown that this alternative method lead to comparable results than common methods used for the determination of the ??-cellulose content, with an enhancement of the accuracy in the determination of the hemicellulose content. Unfortunately, this method cannot be adopted for the determination of the lignin amount.     

Scouring at Bed Sills as a Response to Flash Floods

The temporal development of clear-water local scour depth at bed sills in uniform gravel beds is considered. Experiments are presented on the development of scour holes under unsteady hydraulic conditions, with the triangular-shaped hydrographs tested being of different durations and different rates of flow variation. Based on the experimental results and a theoretical framework, a method is given for the definition and prediction of the scouring process under unsteady flows in terms of a dimensionless temporal parameter. A “flash flood” is here defined as an event for which the scour doesn’t attain its potential magnitude, i.e., the equilibrium value for the peak hydrograph flow rate. This flood nature is dependent on both the characteristics of the flood event itself and the characteristics of the stream. A quantitative measure of what constitutes a flash flood is given in terms of the identified temporal parameter. Results show that the ratio between the final scour depth and the potential scour depth at a bed sill for a given hydrograph can be estimated as a function of the identified temporal parameter.     

Effects of genotype and sowing date on phytostanol–phytosterol content and agronomic traits in wheat under organic agriculture

Cereals are an important source of sterols and stanols in the human diet. The present study underlines the effect of genotype and weather conditions in bread wheat, on total sterol and stanol content (TSS), agronomic traits, proteins and ash content under organic conditions. Variations in TSS as well as other characters between two sowing dates were observed. A broad genotypic variability was also reported since extreme genotypes differed by more than 30 mg 100 g⁻¹ DW for TSS, with total stanol content varying twofold. Moreover, two groups of genotypes that differed in agronomic production, ash and protein content were depicted, based on their response to an increase in temperature. This result suggests that the genotypic factor prevails over the sowing date factor for determining sterol and stanol traits in wheat cultivated under organic conditions. Nevertheless, a strong interaction exists between the two factors, which can be used to drive bioaccumulation of these molecules.     

A decision model for operating two alternate energy generating systems

A solar energy generating system is to be supplemented by two conventional generating systems. A method for investigating the effect of various operating policies of the combined system on the productivity and availability is developed. Using a Markov-Chain approach for computing the long-run expectations of the objectives it was demonstrated that the use of a stand-by mode for one of the conventional systems was optimal. Numerical examples are presented to demonstrate the methodology both for special and more general cases.     

The Scintillation Mechanism in Thallium Doped Alkali Halides

In the scintillation mechanism for alkali iodides doped with thallous iodide: 1. Most of the luminescence, and possibly all of it, is from recombination and therefore energy transfer is predominantly from charge transport to thallium. 2. There are two modes of recombination at thallium which differ in the sequence of charge trapping at Tl+. The electron may be trapped before a mobile hole recombines with it, or the hole may be trapped before recombination with a free electron. 3. Thermal hole diffusion is an important process at room temperature and determines which mode a recombination event follows. 4. Both modes of recombination are active. 5. There is non-thermal hole trapping which is a significant part of the scintillator mechanism.     

Optimal seat allocation for flights with one intermediate stop

During the time prior to departure of a flight with an intermediate stop decisions must be made concerning the allocation of reserved seats to passengers requesting space on the full or partial spans of the flight. The paper presents a model for finding the maximum allowable allocation of seats on the various spans at each time prior to departure such that a maximum expected contribution to profit for the flight is obtained.The model utilizes the time distribution of reservations and cancellations for both spans. Consideration is given to the effects of waitlists, standbys and overbookings. A Bayesian reassessment of probabilities is incorporated in a sequential decision procedure. A computer program was written to perform the calculations, and the results of a short sample problem which was run to test the validity of the model are presented.     

Röntgendiagnostik plasma‐gestützt abgeschiedener dünner Schichten

X‐ray diagnostics of plasma deposited thin layers Grazing incidence x‐ray diffractometry (GIXD) and x‐ray reflectometry (XR) have been introduced as well suited tools for investigations of plasma deposited thin layers. They are non‐destructive techniques, therefore a sample can be reused and measured with other techniques. A combination of GIXD and XR can give a range of interesting information about chemical, physical and crystallographic properties of thin films. Conclusions can be drawn how plasma deposition techniques and plasma parameters influence the film growth. In three examples we present the analysis of phase and chemical composition, defect structure and measurements of kinetic process parameters.