Chemical Measurement and Fluctuation Scaling

Main abstract: Fluctuation scaling reports on all processes producing a data set. Some fluctuation scaling relationships, such as the Horwitz curve, follow exponential dispersion models which have useful properties. The mean-variance method applied to Poisson distributed data is a special case of these properties allowing the gain of a system to be measured. Here, a general method is described for investigating gain (G), dispersion (β), and process (α) in any system whose fluctuation scaling follows a simple exponential dispersion model, a segmented exponential dispersion model, or complex scaling following such a model locally. When gain and dispersion cannot be obtained directly, relative parameters, GR and βR, may be used. The method was demonstrated on data sets conforming to simple, segmented, and complex scaling. These included mass, fluorescence intensity, and absorbance measurements and specifications for classes of calibration weights. Changes in gain, dispersion, and process were observed in the scaling of these data sets in response to instrument parameters, photon fluxes, mathematical processing, and calibration weight class. The process parameter which limits the type of statistical process that can be invoked to explain a data set typically exhibited 04 possible. With two exceptions, calibration weight class definitions only affected β. Adjusting photomultiplier voltage while measuring fluorescence intensity changed all three parameters (0<α<0.8; 0<βR<3; 0<GR<4.1). The method provides a framework for calibrating and interpreting uncertainty in chemical measurement allowing robust compar ison of specific instruments, conditions, and methods. Supporting information abstract: On first inspection, fluctuation scaling data may appear to approximate a straight line when log transformed. The data presented in figure 5 of the main text gives a reasonable approximation to a straight line and for many purposes this would be sufficient. The purpose of the study of fluorescence intensity was to determine whether adjusting the voltage of a photomultiplier tube while measuring a fluorescent sample changes the process (α), the dispersion (β) and/or the gain (G). In this regard, the linear model established that PMT setting affects more than the gain. However, a detailed analysis beginning with testing for model mis-specification provides additional information. Specifically, Poisson behavior is only seen over a limited wavelength range in the 600 V and 700 V data sets

A fault-tolerant multiprocessor architecture for aircraft, volume 1

A fault-tolerant multiprocessor architecture is reported. This architecture, together with a comprehensive information system architecture, has important potential for future aircraft applications. A preliminary definition and assessment of a suitable multiprocessor architecture for such applications is developed

Designing Markets for Biodiversity Offsets: Lessons from Tradable Pollution Permits

Globally, governments and regulators face an ongoing trade‐off between meeting economic development needs and conserving biodiversity. Markets for biodiversity offsets are one tool which could secure biodiversity protection at lower costs to society whilst allowing some economic development to still take place. We provide a new perspective on biodiversity offset markets by focussing on what can be learnt from one of the best‐researched environmental markets: the market for tradable pollution permits. We argue there are four key design parameters in terms of how and what to trade. These design parameters likely determine the ecological effectiveness and economic efficiency of any market in biodiversity offsets. Applying lessons from tradable pollution permit markets will be important if the benefits of biodiversity offset markets are to be realized more fully in future. A well‐functioning market for biodiversity offsets dually minimizes the economic costs of preventing future losses in biodiversity due to development and provides an economic incentive for landowners to invest in biodiversity conservation. The most crucial aspect of the market is what to trade (the currency in the offset market), and this has significant implications on the other key aspects of market design; the trading ratio which governs the rate of exchange between offsets at different points in space and time; the scale of the market; and how the market is regulated. We argue that markets function best where the conservation priority is a well‐defined unit of biodiversity which can be readily measured and monitored. In situations where there are already strong regulations safeguarding biodiversity, the benefit of biodiversity offset markets is in reducing the aggregate costs of conservation. We believe biodiversity offset markets will offer the highest potential in developing countries with weaker environmental protection and a greater need to reconcile economic development needs with conservation under limited funding

Photoresponse of PbS nanoparticles-quaterthiophene films prepared by gaseous deposition as probed by XPS

Cataloged from PDF version of article.Semiconducting lead sulfide (PbS) nanoparticles were cluster beam deposited into evaporated quaterthiophene (4T) organic films, which in some cases were additionally modified by simultaneous 50 eV acetylene ion bombardment. Surface chemistry of these nanocomposite films was first examined using standard x-ray photoelectron spectroscopy (XPS). XPS was also used to probe photoinduced shifts in peak binding energies upon illumination with a continuous wave green laser and the magnitudes of these peak shifts were interpreted as changes in relative photoconductivity. The four types of films examined all displayed photoconductivity: 4T only, 4T with acetylene ions, 4T with PbS nanoparticles, and 4T with both PbS nanoparticles and acetylene ions. Furthermore, the ion-modified films displayed higher photoconductivity, which was consistent with enhanced bonding within the 4T organic matrix and between 4T and PbS nanoparticles. PbS nanoparticles displayed higher photoconductivity than the 4T component, regardless of ion modification. (C) 2012 American Vacuum Society

Carotid atherosclerosis and a reduced likelihood for lowered cognitive Performance in a Canadian first nations population

Background: We investigated the associations among cardiovascular risk factors, carotid atherosclerosis and cognitive function in a Canadian First Nations population. Methods: Individuals aged ≥18 years, without stroke, nonpreg- nant and with First Nations status were assessed by the Trail Making Test Parts A and B. Results were combined into a Trail Making Test executive function score (TMT-exec). Doppler ultrasonography assessed carotid stenosis and plaque volume. Anthropometric, vascular and metabolic risk factors were assessed by interview, clinical examinations and blood tests. Results: For 190 individuals with TMT-exec scores, the median age of the population was 39 years. Compared to the reference group, individuals with elevated levels of left carotid stenosis (LCS) and total carotid stenosis (TCS) were less likely to demonstrate lowered cognitive performance [LCS, odds ratio (OR): 0.47, 95% confidence interval (CI): 0.24-0.96; TCS, OR: 0.40, 95% CI: 0.20-0.80]. No effect was shown for plaque volume. In structural equation modeling, we found that for every 1-unit change in the anthropometric factor in kg/m2, there was a 0.86-fold decrease in the percent of TCS (p \u3c 0.05). Conclusions: Individuals with elevated levels of LCS and TCS were less likely to demonstrate lowered performance. There was some suggestion that TCS mediates the effect of anthropometric risk factors on cognitive function. Copyright © 2009 S. Karger AG, Basel

Energy dissipation in soil samples during drained triaxial shearing

The discrete-element method was used to simulate drained triaxial compression of large-scale, polydisperse numerical samples at a range of void ratios while tracing all relevant energy components. The frictional dissipation and boundary work are almost equal regardless of sample density. The volumetric work reaches a steady value at large strain. However, the distortional work increases continually as sample deformation continues post-critical state. There is a preferential orientation for frictional dissipation at around 45° to the major principal stress direction. This matches the orientation at which there is the largest number of sliding contacts. The work equations, which are fundamental in most commonly used constitutive models, are linear when plotted against deviatoric strain. The modified Cam Clay work equation substantially over-predicts the frictional dissipation for dense samples. An alternative, thermodynamically consistent work equation gives a much better description of frictional dissipation and is therefore recommended to ensure accuracy in modelling

Cognitive demands of face monitoring: Evidence for visuospatial overload

Young children perform difficult communication tasks better face to face than when they cannot see one another (e.g., Doherty-Sneddon & Kent, 1996). However, in recent studies, it was found that children aged 6 and 10 years, describing abstract shapes, showed evidence of face-to-face interference rather than facilitation. For some communication tasks, access to visual signals (such as facial expression and eye gaze) may hinder rather than help children’s communication. In new research we have pursued this interference effect. Five studies are described with adults and 10- and 6-year-old participants. It was found that looking at a face interfered with children’s abilities to listen to descriptions of abstract shapes. Children also performed visuospatial memory tasks worse when they looked at someone’s face prior to responding than when they looked at a visuospatial pattern or at the floor. It was concluded that performance on certain tasks was hindered by monitoring another person’s face. It is suggested that processing of visual communication signals shares certain processing resources with the processing of other visuospatial information

Toxicogenomic analysis incorporating operon-transcriptional coupling and toxicant concentration-expression response: analysis of MX-treated Salmonella

<p>Abstract</p> <p>Background</p> <p>Deficiencies in microarray technology cause unwanted variation in the hybridization signal, obscuring the true measurements of intracellular transcript levels. Here we describe a general method that can improve microarray analysis of toxicant-exposed cells that uses the intrinsic power of transcriptional coupling and toxicant concentration-expression response data. To illustrate this approach, we characterized changes in global gene expression induced in <it>Salmonella typhimurium </it>TA100 by 3-chloro-4-(dichloromethyl)-5-hydroxy-2(<it>5H</it>)-furanone (MX), the primary mutagen in chlorinated drinking water. We used the co-expression of genes within an operon and the monotonic increases or decreases in gene expression relative to increasing toxicant concentration to augment our identification of differentially expressed genes beyond Bayesian-t analysis.</p> <p>Results</p> <p>Operon analysis increased the number of altered genes by 95% from the list identified by a Bayesian t-test of control to the highest concentration of MX. Monotonic analysis added 46% more genes. A functional analysis of the resulting 448 differentially expressed genes yielded functional changes beyond what would be expected from only the mutagenic properties of MX. In addition to gene-expression changes in DNA-damage response, MX induced changes in expression of genes involved in membrane transport and porphyrin metabolism, among other biological processes. The disruption of porphyrin metabolism might be attributable to the structural similarity of MX, which is a chlorinated furanone, to ligands indigenous to the porphyrin metabolism pathway. Interestingly, our results indicate that the <it>lexA </it>regulon in <it>Salmonella</it>, which partially mediates the response to DNA damage, may contain only 60% of the genes present in this regulon in <it>E. coli</it>. In addition, <it>nanH </it>was found to be highly induced by MX and contains a putative <it>lexA </it>regulatory motif in its regulatory region, suggesting that it may be regulated by <it>lexA</it>.</p> <p>Conclusion</p> <p>Operon and monotonic analyses improved the determination of differentially expressed genes beyond that of Bayesian-t analysis, showing that MX alters cellular metabolism involving pathways other than DNA damage. Because co-expression of similarly functioning genes also occurs in eukaryotes, this method has general applicability for improving analysis of toxicogenomic data.</p