Experimental localized radar cross sections of aircraft

Localized RCS measurements are presented for the Boeing 727 and the Lockheed L-1011 aircraft. The measurements were made at X-band from a few degrees aft of broadside. The elevation angle was approximately 30°. Four data sets, each of 128 pulses, were obtained from each airplane examined. The data presented are composites of measurements of five Boeing 727s and three L-1011s     

Overcoming language barriers when teaching the Advanced Trauma Life Support course

OBJECTIVES: To determine whether blurred vision caused by exposure to triethylamine (TEA) can be detected by the measurement of contrast sensitivity. METHODS: 41 cold box core makers of three foundries and 82 control workers were examined. A detailed ocular and medical history was obtained from the subjects. The contrast sensitivity of the core makers was measured on Monday and Friday of the same week both before and immediately after work and also on a third day, when air samples of TEA were collected. Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast. The changes in contrast sensitivity were used for the analysis. The results of binocular vision and the results of the dominant eye were analysed. Urine specimens for the analysis of TEA were collected on every occasion when contrast sensitivity was measured. RESULTS: 78% of the core makers had had symptoms of blurred vision, and 31% had had trouble driving or working. The breathing zone eight hour time weighted average TEA concentrations were 0.3-60 mg/m3. The mean urinary TEA concentration after the shift was 35 mmol/mol creatinine. Continuous monitoring showed high peaks of TEA leakage at a core making machine. Changes in binocular visual acuity did not differ between the exposed and unexposed workers. The contrast sensitivity decreased in 49% of the core makers and 21% of the controls (P = 0.002). CONCLUSIONS: The blurred vision caused by exposure to TEA can be documented by measuring contrast sensitivity. The mechanism by which TEA produces symptoms remains an issue of further study.     

Medical ethics in an interreligious comparison: Judaism

Ethik in der Medizin -     

Organically modified silicate thin films doped with colourimetric pH indicators methyl red and bromocresol green as pH responsive sol-gel hybrid materials

The colourimetric pH indicators methyl red and bromocresol green have been immobilised in organic-inorganic silica hybrid matrices prepared by a sol-gel method. The optically transparent sol-gel thin films containing encapsualated dye molecules were deposited onto glass substrates using spin-coating and dip-coating techniques. The organic-inorganic hybrid materials were obtained by co-polymerisation of tetraethoxysilane together with glycidoxypropyltrimethoxysilane as an organically modified sol-gel precursor. Matrix polarity and morphology were varied by using solutions containing different ratios of sol-gel precursors and surfactants. Spectral characterisation of the films was performed using ultra-violet and visible absorption spectroscopy, and the spectral changes in different matrices were identified. The effects of the sol-gel mixtures composition on the mechanical stability and homogeneity of the films, and the colourimetric response to solutions of differing pH were studied. The apparent pK_app values of the immobilised pH indicators were also determined in the different matrices.     

Stochastic simulations of ErbB homo and heterodimerisation: potential impacts of receptor conformational state and spatial segregation

ErbB overexpression is linked to carcinogenesis. It is hypothesised that this is due to increased receptor density and receptor clustering, leading to increased receptor dimerisation and activation. Herein, spatial stochastic simulations have been performed to shed light receptor dimerisation processes. First, ligand- independent homodimerisation, is considered, based upon constitutive oligomerisation estimates (14%) in A431 cells that overexpress epidermal growth factor receptor (EGFR). When autocrine stimulation is blocked, ligand-independent EGFR activation is demonstrated by persistent, low levels of phosphorylation. The possibility that ligand-independent signalling is due to the fluctuation of EGFR conformation is considered. The agent-based model predicts the frequency (expressed as a probability) that uniformly distributed receptors would need to flux to the open conformation to reach 14% EGFR dimers at high receptor density. Simulations suggest that ligand-independent EGFR homodimerisation is highly density dependent, since collisions between 'open', dimerisation-competent receptors are a rare event at low receptor levels. Simulations that incorporate receptor clustering lower the threshold for homodimerisation of unoccupied receptors as well as the estimate of the probability for fluxing to the dimer-competent conformation. The impact of ErbB receptor clustering patterns on hetero and homodimerisation rates is also considered, using immunoelectron microscopy data derived from SKBR3 breast cancer cells that express ErbB2 Gt EGFR > ErbB3. Partial spatial segregation of ErbB receptors has a profound effect on simulated heterodimerisation rates. Despite the general assumption that ErbB2 is a preferred heterodimerising partner for other ErbBs, it is predicted that most ErbB2 will form homodimers. Overall, it is proposed that both receptor density and membrane spatial organisation contribute to the carcinogenesis process.     

A multiresolution homogenization of modal analysis with application to layered media

We apply multiresolution techniques to study the effective properties of boundary value problems. Conditions under which boundary values are preserved in the effective (‘homogenized') formulation are developed and discussed. Relations between the eigenfunctions and eigenvalues of the generic formulation and those of the effective formulation are explored. Applications to the construction of effective Green function in a complex lamination are discussed. The analytic results are demonstrated via numerical computations.     

The consequences of pairing questions: Context effects in personality measurement.

The effect of context on responses to questions has been a prominent focus in social and political survey research. However, little investigation of context effects has been done for the measurement of psychological constructs. A measure of anger experience and expression in development uses vignettes describing interpersonal situations that provoke varying degrees of anger and require respondents to indicate their affective and/or expressive response to the situation. In this study, the consequences of pairing the two questions for each vignette are investigated. Pairing the anger-experience and likelihood-of-expression questions changes the item's context. Item response theory analysis similar to that used to detect differential item functioning was performed. For some of the items, responding to a single or paired question affected the extremity of responses. The findings are discussed in terms of their implications for personality measurement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MHC class I genes in a New World primate, the cotton-top tamarin (Saguinus oedipus), have evolved by an active process of loci turnover

Lymphocytes of a New World primate, the cotton-top tamarin (Saguinus oedipus), express classical G-related major histocompatibility complex (MHC) class I molecules with unusually limited polymorphism and variability. Three G-related loci, an F locus, an E locus, and two pseudogenes (So-N1 and So-N3) have been identified by cDNA library screening and extensive PCR analysis of both cDNA and genomic DNA from the cotton-top tamarin. Furthermore, each genus of the subfamily Callitrichinae (tamarins and marmosets) appears to express its own unique set of MHC class I genes, likely due to a rapid turnover of loci. The rapid emergence of unique MHC class I genes in the Callitrichinae genera, resulting from an active process of duplication and inactivation of loci, may account for the limited diversity of the MHC class I genes in the cotton-top tamarin. To determine the nature of the entire complement of MHC class I genes in the cotton-top tamarin, we synthesized a genomic DNA library and screened it with MHC class I-specific probes. We isolated nine new MHC class I pseudogenes from this library. These newly isolated tamarin G-related MHC class I pseudogenes are not closely related to any of their functional counterparts in the tamarin, suggesting that they do not share a recent common ancestral gene with the tamarin's currently expressed MHC class I loci. In addition, these tamarin sequences display a high rate of nonsynonymous substitutions in their putative peptide binding region. This indicates that the genes from which they have derived were likely subject to positive selection and, therefore, were once functional. Our data support the notion that an extremely high rate of loci turnover is largely responsible for the limited diversity of the MHC class I genes in the cotton-top tamarin.