A note on the properties of power-transformed returns in long-memory stochastic volatility models with leverage effect

The autocorrelation function (acf) of powered absolute returns and their cross-correlations with original returns are derived, for any value of the power parameter, in the context of long-memory stochastic volatility models with leverage effect and Gaussian noises. These autocorrelations and cross-correlations generalize and correct recent results on the acf of squared and absolute returns.     

Activation of timber surfaces by flame and corona treatments to improve adhesion

Long-term durability of a structural adhesive joint is an important requirement, because it has to be able to support the required design loads, under service conditions, for the planed lifetime of the structure. One way of improving bond durability is through the use of surface treatments prior to bonding, which will activate the adherends’ surface, making it more receptive to the adhesive. In this study, the effects of two surface pre-treatments (corona discharge and flame ionization) on three timbers (maritime pine, iroko, and European oak) were evaluated quantitatively through contact angle measurements. These measurements allowed the determination of the changes in the timber surface thermodynamic characteristics, thus indicating which pre-treatment performed better. The results showed that both techniques increased each timber's surface free energy, which could translate into a durability enhancement of bonded joints. Overall, the corona-discharge treatment looks more promising, since this treatment leads to a bigger increase in the timber's surface energy, especially in its polar component, whilst also tended to be less species specific, less susceptible to variation, and the treatment effects lasted longer for this type of treatment.     

A tandem mass spectrometer for improved transmission and analysis of large macromolecular assemblies

We report the design and first applications of a tandem mass spectrometer (a quadrupole time-of-flight mass spectrometer) optimized for the transmission and analysis of large macromolecular assemblies. Careful control of the pressure gradient in the different pumping stages of the instrument has been found to be essential for the detection of macromolecular particles. Such assemblies are, however, difficult to analyze by tandem-MS approaches, because they give rise to signals above m/z 3,000-4,000, the limit for commercial quadrupoles. By reducing the frequency of the quadrupole to 300 kHz and using it as a narrow-band mass filter, we show that it is possible to isolate ions from a single peak at m/z 22,000 in a window as narrow as 22 m/z units. Using cesium iodide cluster signals, we show that the mass range in the time-of-flight (TOF) analyzer extends beyond m/z 90,000, in theory to more than m/z 150,000. We also demonstrate that the resolution of the instrument is greater than 3,000 at m/z 44,500. Tandem-MS capabilities are illustrated by separating components from heterooligomeric assemblies formed between tetrameric transthyretin, thyroxine, retinol-binding protein, and retinol. Isolation of a single charge state at m/z 5,340 in the quadrupole and subsequent collision-induced dissociation (CID) in the gas-filled collision cell leads to the formation of ions from individual subunits and subcomplexes, identified by their mass and charge in the TOF analyzer.     

Agile Practices Reduce Distance in Global Software Development

This article explores how agile practices can reduce three kinds of “distance” - temporal, geographical, and sociocultural - in global software development (GSD). On the basis of two in-depth case studies, specific Scrum and eXtreme Programming (XP) practices are found to be useful for reducing communication, coordination, and control problems that have been associated with GSD.     

The effects of assessment type on verbal ratings of conditional stimulus valence and contingency judgments: Implications for the extinction of evaluative learning.

Recent research on causal learning found (a) that causal judgments reflect either the current predictive value of a conditional stimulus (CS) or an integration across the experimental contingencies used in the entire experiment and (b) that postexperimental judgments, rather than the CS's current predictive value, are likely to reflect this integration. In the current study, the authors examined whether verbal valence ratings were subject to similar integration. Assessments of stimulus valence and contingencies responded similarly to variations of reporting requirements, contingency reversal, and extinction, reflecting either current or integrated values. However, affective learning required more trials to reflect a contingency change than did contingency judgments. The integration of valence assessments across training and the fact that affective learning is slow to reflect contingency changes can provide an alternative interpretation for researchers' previous failures to find an effect of extinction training on verbal reports of CS valence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

EDX analysis and microstructural properties of the Yba2Cu3O7−δ-Ba2HoSbO6 superconducting composites

We have fabricated and characterized Yba ₂ Cu ₃ O _7– -Ba ₂ HoSbO ₆ a realized high T _c superconductor - ceramic insulator composite system in which particles of the superconductor and ceramic insulator could coexist with well defined separated phases left intact by stringent processing conditions. All the composites exhibit superconductivity at 92K. EDX analysis show that element% and atomic% of the composites are in a good agreement with those of their respective components. SEM studies show homogenous surface morphology and particle size distribution. There is no detectable interface interaction between component grains and Ba ₂ HoSbO ₆ grains are distinguishably distributed in the Yba ₂ Cu ₃ O _7– matrix.     

Soret coefficients of some polyelectrolytes

We present here some measurements of thermal diffusion of some polyelectrolytes in aqueous solutions; in this work the Agar and Turner type of cell was used with its ancillary apparatus, built in this laboratory, developed to improve its precision. Isothermal diffusion coefficients were measured with Agar and Lobo's cell. Heat of transport are calculated and discussed. It is shown that some polyelectrolytes behave as a collection of connected spheres where each monomer unit contributes additively to the total heat of transport, whereas others behave differently.     

Isoelektrische Fokussierung und zweidimensionale Auftrennung einer wasserl?slichen Proteinfraktion von Hart- und Weichweizen aus Teigwarenprodukten

Zusammenfassung Die isoelektrische Fokussierung einer wasserlöslichen Proteinfraktion von Hart- und Weichweizen aus Teigwarenprodukten wird mit der bisher üblichen disk-elektrophoretischen Trennmethode verglichen. Die Elektrofokussierung liefert im Gegensatz zur Disk-Elektrophorese auch bei Anwesenheit von Ei-Proteinen sowie nach vorgängiger Hitzedenaturierung der Proteine zuverlässige und genaue Resultate. Im weiteren wird zur besseren Auftrennung und Charakterisierung der wasserlöslichen Proteinfraktion eine zweidimensionale Trennmethode (isoelektrische Fokussierung und anschließende Elektrophorese) beschrieben.

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Isoelectric focusing and two-dimensional separation of watersoluble protein fraction of hard and soft wheat from macaroni

Summary The isoelectric focusing of water-soluble protein fraction of hard and soft wheat from macaroni are compared with the disc electrophoresic separation methods. Electrofocusing produced more trustworthy and exacter results in the presence of egg proteins as well for heat-denaturated proteins. Further is described a better separation and characterisation of a water-soluble protein fraction using a two-dimensional system involving isoelectric focusing in the first dimension followed by electrophoresis in the second.

     

Prevalence of Escherichia coli O157 in cattle and swine in central Mexico

Escherichia coli O157:H7 is a foodborne pathogenic bacterium that can reside undetected in the gastrointestinal tract of cattle because colonization by this bacterium is asymptomatic. Recent research has indicated that swine can carry and transmit this pathogen as well. The development of more advanced and sensitive detection techniques has improved the limit of detection and increased sensitivity for this important pathogen. This study was undertaken to determine the prevalence of E. coli O157 in cattle and swine in Mexico with the more sensitive detection technique of immunomagnetic bead separation. Samples (n = 60 per farm) were taken from four cattle and four swine farms (n = 240 cattle samples, n = 240 swine samples) located throughout central Mexico in October 2001. The prevalence of E. coli O157 was found to be only 1.25% on cattle farms and 2.1% on swine farms. The prevalence in cattle in this study is lower than that reported in the United States and could be related to the lower reported prevalence of E. coli O157 in humans in Mexico. However, further research is needed to verify prevalence throughout other regions of Mexico, as well as prevalence during other seasons of the year.