Complete homochirality induced by the nonlinear autocatalysis and recycling

A nonlinear autocatalysis of a chiral substance is shown to achieve homochirality in a closed system, if the back-reaction is included. Asymmetry in the concentration of two enantiomers or the enantiometric excess increases due to the nonlinear autocatalysis. Furthermore, when the back-reaction is taken into account, the reactant supplied by the decomposition of the enantiomers is recycled to produce more and more the dominant one, and eventually the homochirality is established.Comment: 4 pages, 2 figure

The Evolution of Damped Lyman-alpha Absorbers: Metallicities and Star Formation Rates

The damped Lyman-alpha (DLA) and sub-DLA quasar absorption lines provide powerful probes of the evolution of metals, gas, and stars in galaxies. One major obstacle in trying to understand the evolution of DLAs and sub-DLAs has been the small number of metallicity measurements at z < 1.5, an epoch spanning \~70 % of the cosmic history. In recent surveys with the Hubble Space Telescope and Multiple Mirror Telescope, we have doubled the DLA Zn sample at z < 1.5. Combining our results with those at higher redshifts from the literature, we find that the global mean metallicity of DLAs does not rise to the solar value at low redshifts. These surprising results appear to contradict the near-solar mean metallicity observed for nearby (z ~ 0) galaxies and the predictions of cosmic chemical evolution models based on the global star formation history. Finally, we discuss direct constraints on the star formation rates (SFRs) in the absorber galaxies from our deep Fabry-Perot Ly-alpha imaging study and other emission-line studies in the literature. A large fraction of the observed heavy-element quasar absorbers at 0 < z < 3.4 appear to have SFRs substantially below the global mean SFR, consistent with the low metallicities observed in the spectroscopic studies.Comment: 6 pages,3 figures, To appear in "Probing Galaxies through Quasar Absorption Lines", Proceedings IAU Colloquium 199, 2005, Eds. P. R. Williams, C. Shu, and B. Menar

Book Reviews

Die hartJou Harl en Lewe. Deur A. J. Brink. Bl. 248. Gemustreer. RI6,95. Pretoria: Femina. 1982.The physiology of digestionExperiments and Observations on the Gastric Juice and the Physiology of Digestion. By William Beaumonr. 1st ed. 1&amp;33. Reprinted in facsimile for the Classics ofMedicine Library, Division of Gryphon Editions Ltd, Birmingham, Alabama, 1980.Bone in Clinical Orthopaedics: A Study in ComparativeOsteology. Ed. by G. Sumner-Smith. Pp. xvi + 435. Illustrated. R94,25. Philadelphia: W. B. Saunders. 1982.Tamoxifen in breast cancerThe Role of Tamoxifen in Breast Cancer. Ed. by S. Iacobelli, M. E. Lippman and G. R. Della Cuna. Pp. xii + 124. Illustrated. 523,12. New York: Raven Press. 1982.Under the Influence. A History ofNitrous Oxide and OxygenAnaesthesia. By W. D. A. Smith. Pp. xxviii + 188. Illustrated. R33,50. London: Macmillan. 1982.Clinical internal medicine in the agedClinical Internal Medicine in the Aged. By R. W. Schrier. Pp. vii + 324. Illustrated. R61,-. Philadelphia: W. B. Saunders. 1982.Genital Infection by Chlamydia Trachomatis (Current Topicsin Infection, No. 2). By J. D. Oriel and G. L. Ridgway. Pp. viii + 144. Illustrated. R32,20. London: Edward Arnold. 1982.Placental Function Tests. By T. Chard and A. Klopper. Pp. viii + 94. Illustrated. DM42,-. Berlin: Springer-Verlag. 1982.Therapeutic Heat and Cold. 3rd ed. Ed. by J. F. Lehmann. Pp. xiv + 641. Illustrated. Baltimore: Williams &amp; Wilkins. 1982

Formaldehyde treatment of proteins enhances proteolytic degradation by the endo-lysosomal protease cathepsin S

Enzymatic degradation of protein antigens by endo-lysosomal proteases in antigen-presenting cells is crucial for achieving cellular immunity. Structural changes caused by vaccine production process steps, such as formaldehyde inactivation, could affect the sensitivity of the antigen to lysosomal proteases. The aim of this study was to assess the effect of the formaldehyde detoxification process on the enzymatic proteolysis of antigens by studying model proteins. Bovine serum albumin, β-lactoglobulin A and cytochrome c were treated with various concentrations of isotopically labelled formaldehyde and glycine, and subjected to proteolytic digestion by cathepsin S, an important endo-lysosomal endoprotease. Degradation products were analysed by mass spectrometry and size exclusion chromatography. The most abundant modification sites were identified by their characteristic MS doublets. Unexpectedly, all studied proteins showed faster proteolytic degradation upon treatment with higher formaldehyde concentrations. This effect was observed both in the absence and presence of glycine, an often-used excipient during inactivation to prevent intermolecular crosslinking. Overall, subjecting proteins to formaldehyde or formaldehyde/glycine treatment results in changes in proteolysis rates, leading to an enhanced degradation speed. This accelerated degradation could have consequences for the immunogenicity and the efficacy of vaccine products containing formaldehyde-inactivated antigens.Drug Delivery Technolog

Bayesian Dynamic Linear Models for Estimation of Phenological Events from Remote Sensing Data

Estimating the timing of the occurrence of events that characterize growth cycles in vegetation from time series of remote sensing data is desirable for a wide area of applications. For example, the timings of plant life cycle events are very sensitive to weather conditions and are often used to assess the impacts of changes in weather and climate. Likewise, understanding crop phenology can have a large impact on agricultural strategies. To study phenology using remote sensing data, the timings of annual phenological events must be estimated from noisy time series that may have many missing values. Many current state-of-the-art methods consist of smoothing time series and estimating events as features of smoothed curves. A shortcoming of many of these methods is that they do not easily handle missing values and require imputation as a preprocessing step. In addition, while some currently used methods may be extendable to allow for temporal uncertainty quantification, uncertainty intervals are not usually provided with phenological event estimates. We propose methodology utilizing Bayesian dynamic linear models to estimate the timing of key phenological events from remote sensing data with uncertainty intervals. We illustrate the methodology on weekly vegetation index data from 2003 to 2007 over a region of southern India, focusing on estimating the timing of start of season and peak of greenness. Additionally, we present methods utilizing the Bayesian formulation and MCMC simulation of the model to estimate the probability that more than one growing season occurred in a given year. Supplementary materials accompanying this paper appear online. © 2018, International Biometric Society

Tropomyosin concentration but not formin nucleators mDia1 and mDia3 determines the level of tropomyosin incorporation into actin filaments

The majority of actin filaments in human cells exist as a co-polymer with tropomyosin, which determines the functionality of actin filaments in an isoform dependent manner. Tropomyosin isoforms are sorted to different actin filament populations and in yeast this process is determined by formins, however it remains unclear what process determines tropomyosin isoform sorting in mammalian cells. We have tested the roles of two major formin nucleators, mDia1 and mDia3, in the recruitment of specific tropomyosin isoforms in mammals. Despite observing poorer cell-cell attachments in mDia1 and mDia3 KD cells and an actin bundle organisation defect with mDia1 knock down;depletion of mDia1 and mDia3 individually and concurrently did not result in any significant impact on tropomyosin recruitment to actin filaments, as observed via immunofluorescence and measured via biochemical assays. Conversely, in the presence of excess Tpm3.1, the absolute amount of Tpm3.1-containing actin filaments is not fixed by actin filament nucleators but rather depends on the cell concentration of Tpm3.1. We conclude that mDia1 and mDia3 are not essential for tropomyosin recruitment and that tropomyosin incorporation into actin filaments is concentration dependent

A simulated rugby match protocol induces physiological fatigue without decreased individual scrummaging performance

Background: A rugby union game consists of 80 minutes of strenuous exertion. Forwards are required to participate in the arduous activity of scrummaging throughout a game.Objectives: The purpose of this study was to identify whether rugby-match simulated fatigue modified individual scrummaging technique and reduced performance.Methods: Twelve forwards (body mass 106.2±13.3 kg; stature 179.5±8.4 cm) had individual scrum kinetics and kinematics assessed prior to and following a protocol that simulated a rugby match. The simulated rugby match protocol required participants to run at various velocities and perform rugby specific tasks. Rating of Perceived Exertion (RPE) was assessed using a 6-20 Borg scale and Visual Analogue Scale (VAS). Blood lactate, heart rate and RPE were measured prior to, at mid-point and after the simulated game, while markers of muscle damage (blood creatine kinase activity (CK) and urea) were measured prior to and following the protocol.Results: RPE (p&lt;0.0001) and VAS (p&lt;0.0001) showed significant increases between the pre- and post-simulation values. Of the physiological markers, heart rate (p&lt;0.0001) and blood urea concentration (p=0.004) increased following the match simulation. No significant differences were observed for blood CK (p=0.281), individual scrummaging forces (p=0.433) or in the kinematic variables following the protocol. While physiological fatigue and subjective ratings of physiological fatigue may develop during a rugby simulation, no differences were observed in peak forces or in body kinematics at peak force.Conclusion: Physiological fatigue does not influence individual scrummaging performance and technique

A multi-detector array for high energy nuclear e+e- pair spectrosocopy

A multi-detector array has been constructed for the simultaneous measurement of energy- and angular correlation of electron-positron pairs produced in internal pair conversion (IPC) of nuclear transitions up to 18 MeV. The response functions of the individual detectors have been measured with mono-energetic beams of electrons. Experimental results obtained with 1.6 MeV protons on targets containing $^{11}$B and $^{19}$F show clear IPC over a wide angular range. A comparison with GEANT simulations demonstrates that angular correlations of $e^+e^-$ pairs of transitions in the energy range between 6 and 18 MeV can be determined with sufficient resolution and efficiency to search for deviations from IPC due to the creation and subsequent decay into $e^+e^-$ of a hypothetical short-lived neutral boson.Comment: 20 pages, 8 figure

An item and construct bias analysis of two language versions of a verbal analogies scale

The Woodcock Muñoz Language Survey is a test of cognitive academic language proficiency that has been adapted from English into Xhosa by a South African team of researchers. This study was primarily concerned with the Verbal Analogies Scale of the Woodcock Muñoz Language Survey and aimed to extend previous research on the equivalence of the two language versions of the scale. The study employed a monolingual two-group design consisting of 150 mainly English-speaking and 149 mainly Xhosa learners in Grades 6 and 7. The first research objective was to investigate item bias (or differential item functioning items) in the Visual Analogies Scale across the Xhosa and English versions using logistic regression and Mantel–Haenszel statistical techniques. Five items were identified as differential item functioning. The second objective was to evaluate the construct equivalence of the two versions by conducting a factor analysis after removing the differential item functioning items from the scale. Two factors were identified. The first factor displayed significant loadings across both language versions. The second factor was stable for the English version but not for the Xhosa version. Results were supported by calculating a Tucker’s phi coefficient for both factors. It was therefore concluded that Factor 1 is structurally equivalent across the two language versions but that Factor 2 was not structurally equivalent. Thus, the detection and removal of differential item functioning items did not result in structural equivalence.Department of HE and Training approved lis