Environmental air pollution and DNA adducts in Copenhagen bus drivers--effect of GSTM1 and NAT2 genotypes on adduct levels

Fecal samples from 335 dairy farm residents and 1458 cattle on 80 farms were tested for Vero cytotoxin (VT)-producing Escherichia coli (VTEC). Residents were also tested for antibodies to VT1 and O157 lipopolysaccharide (LPS). Residents and cattle on farms with VTEC-positive persons or E. coli O157:H7-positive cattle were retested. Twenty-one persons (6.3%) on 16 farms (20.8%) and 46% of cattle on 100% of the farms had VTEC in fecal samples. Human VTEC isolates included E. coli O157:H7 and 8 other serotypes, 4 of which were present in cattle on the same farms. More persons had antibodies to VT1 (41%) than to O157 LPS (12.5%). Seropositivity to O157 LPS was associated with isolation of E. coli O157:H7 on the farm (P = .022). Human VTEC infection was negatively associated with age (P < .05) and was not associated with clinical illness. Many dairy farm residents experience subclinical immunizing VTEC infections at a young age, which frequently involve non-O157 VTEC found in cattle.     

The skin, free radicals, and oxidative stress

Oxidative stress involves the adverse effects of oxygen and other free radicals on living tissue. An overview of the various types of free radicals generated in the body, the basic chemistry of free radicals, and how they arise is presented. The importance of understanding the action of free radicals on specific target tissues in the skin and how this affects the physiology of the skin in relation to treatment is covered.     

From the times of the first scribes: innovation and technology within graphic design

The authors use their different work and training background as perspectives for discussing the changing world of graphical design. In this digital world, expert knowledge of the technology is essential, but the authors argue that a consequence of prioritising technical expertise in the new interdisciplinary IT- design studies may be a loss of quality in design. To improve the depth in design the authors introduce a psychological framework for design work and on this basis they suggest a systematic method. The method is a 4-step conceptual model: reason, function, emotion and senses, and technology. The model interacts with all phases of the design, and functions as a generating-creating and execution-evaluation system. The authors emphasise that evaluation is embedded throughout the design process. They suggest that a systematic method becomes the guiding tool in interdisciplinary design education, an essential part of the students design qualifications as well as an essential tool in design work.     

Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model

This paper investigates the well-known model for unsteady friction developed by Zielke in 1968. The model is based on weights of past local bulk accelerations and is analytically correct for laminar flow, but computationally demanding. Different models have been proposed using dynamic properties, typically based on instantaneous accelerations (IAB) that are more rapid in computational schemes. Unfortunately, they are not as accurate as Zielke’s model and fail to model certain types of transients. This paper points out that the water hammer transient is dominated by a periodicity varying along the pipe. Because of this, the unsteady friction calculated by the Zielke model is distributed nonuniformly along the pipe, and changes in the pipe length change the local unsteady friction. This phenomenon may explain why IAB models using calibrated coefficients to match experimental results have a large span in value for the reported coefficients. This paper will hopefully contribute to further work to find highly accurate and rapid models. The subject deserves to be brought up for discussion as a part of a total understanding of the problem.     

Transient Friction in Pressurized Pipes. II: Two-Coefficient Instantaneous Acceleration–Based Model

The goal in the field of modeling of hydraulic transients is a comprehensive model for pipe networks that is computationally fast and accurate. The fastest models are the one-dimensional (1D) models that use instantaneous acceleration–based (IAB) properties, but unfortunately these models are not as accurate as the more demanding 1D convolution-based (CB) models or quasi two-dimensional models. Focusing on a single pipe, this paper investigates the fundamental behavior of the much more accurate 1D CB model to find two coefficients for use with the two-coefficient formulation of the much-used modified IAB (MIAB) model for complete closing of a downstream valve. Two coefficients are found based on the weighting function used in the CB model, and these coefficients vary along the pipe length. Simulations are compared with two experimental results from tests performed at University of Adelaide in Australia in 1995. The experimental results are for different initial Reynolds numbers of approximately 2,000 and 5,800. The results show very good agreement between simulations and experiments. The improvement of the MIAB model is not general, and for the time being, only complete closure of a downstream valve in a single pipeline at low Reynolds numbers has been investigated.     

Investigation of the Equivalence of National Dew-Point Temperature Realizations in the ?50?°C to +?20?°C Range

In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4?years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from ?50?°C to +20?°C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008?°C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025?°C at ?50?°C and 0.010?°C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field.     

Molecular Heterojunctions of Oligo(phenylene ethynylene)s with Linear to Cruciform Framework

Electrical transport properties of molecular junctions are fundamentally affected by the energy alignment between molecular frontier orbitals (highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO)) and Fermi level (or work function) of electrode metals. Dithiafulvene (DTF) is used as substituent group to the oligo(phenylene ethynylene) (OPE) molecular wires and different molecular structures based on OPE3 backbone (with linear to cruciform framework) are achieved, with viable molecular orbitals and HOMO–LUMO energy gaps. OPE3, OPE3–DTF, and OPE3–tetrathiafulvalene (TTF) can form good self‐assembled monolayers (SAMs) on Au substrates. Molecular heterojunctions based on these SAMs are investigated using conducting probe–atomic force microscopy with different tips (Ag, Au, and Pt) and Fermi levels. The calibrated conductance values follow the sequence OPE3–TTF > OPE3–DTF > OPE3 irrespective of the tip metal. Rectification properties (or diode behavior) are observed in case of the Ag tip for which the work function is furthest from the HOMO levels of the OPE3s. Quantum chemical calculations of the transmission qualitatively agree with the experimental data and reproduce the substituent effect of DTF. Zero‐bias conductance, and symmetric or asymmetric couplings to the electrodes are investigated. The results indicate that improved fidelity of molecular transport measurements may be achieved by systematic studies of homologues series of molecular wires applying several different metal electrodes.