Experimental pig-to-pig transmission dynamics for African swine fever virus, Georgia 2007/1 strain

African swine fever virus (ASFV) continues to cause outbreaks in domestic pigs and wild boar in Eastern European countries. To gain insights into its transmission dynamics, we estimated the pig-to-pig basic reproduction number (R 0) for the Georgia 2007/1 ASFV strain using a stochastic susceptible-exposed-infectious-recovered (SEIR) model with parameters estimated from transmission experiments. Models showed that R 0 is 2·8 [95% confidence interval (CI) 1·3–4·8] within a pen and 1·4 (95% CI 0·6–2·4) between pens. The results furthermore suggest that ASFV genome detection in oronasal samples is an effective diagnostic tool for early detection of infection. This study provides quantitative information on transmission parameters for ASFV in domestic pigs, which are required to more effectively assess the potential impact of strategies for the control of between-farm epidemic spread in European countries.ISSN:0950-2688ISSN:1469-440

The TRENDS High-Contrast Imaging Survey. VI. Discovery of a Mass, Age, and Metallicity Benchmark Brown Dwarf

The mass and age of substellar objects are degenerate parameters leaving the evolutionary state of brown dwarfs ambiguous without additional information. Theoretical models are normally used to help distinguish between old, massive brown dwarfs and young, low mass brown dwarfs but these models have yet to be properly calibrated. We have carried out an infrared high-contrast imaging program with the goal of detecting substellar objects as companions to nearby stars to help break degeneracies in inferred physical properties such as mass, age, and composition. Rather than using imaging observations alone, our targets are pre-selected based on the existence of dynamical accelerations informed from years of stellar radial velocity (RV) measurements. In this paper, we present the discovery of a rare benchmark brown dwarf orbiting the nearby ($d=18.69\pm0.19$ pc), solar-type (G9V) star HD 4747 ([Fe/H]=$-0.22\pm0.04$) with a projected separation of only $\rho=11.3\pm0.2$ AU ($\theta \approx$ 0.6"). Precise Doppler measurements taken over 18 years reveal the companion's orbit and allow us to place strong constraints on its mass using dynamics ($m \sin(i) = 55.3\pm1.9M_J$). Relative photometry ($\Delta K_s=9.05\pm0.14$, $M_{K_s}=13.00\pm0.14$, $K_s - L' = 1.34\pm0.46$) indicates that HD 4747 B is most-likely a late-type L-dwarf and, if near the L/T transition, an intriguing source for studying cloud physics, variability, and polarization. We estimate a model-dependent mass of $m=72^{+3}_{-13}M_J$ for an age of $3.3^{+2.3}_{-1.9}$ Gyr based on gyrochronology. Combining astrometric measurements with RV data, we calculate the companion dynamical mass ($m=60.2\pm3.3M_J$) and orbit ($e=0.740\pm0.002$) directly. As a new mass, age, and metallicity benchmark, HD 4747 B will serve as a laboratory for precision astrophysics to test theoretical models that describe the emergent radiation of brown dwarfs.Comment: Accepted to Ap

Exact Histogram Specification Optimized for Structural Similarity

An exact histogram specification (EHS) method modifies its input image to have a specified histogram. Applications of EHS include image (contrast) enhancement (e.g., by histogram equalization) and histogram watermarking. Performing EHS on an image, however, reduces its visual quality. Starting from the output of a generic EHS method, we maximize the structural similarity index (SSIM) between the original image (before EHS) and the result of EHS iteratively. Essential in this process is the computationally simple and accurate formula we derive for SSIM gradient. As it is based on gradient ascent, the proposed EHS always converges. Experimental results confirm that while obtaining the histogram exactly as specified, the proposed method invariably outperforms the existing methods in terms of visual quality of the result. The computational complexity of the proposed method is shown to be of the same order as that of the existing methods. Index terms: histogram modification, histogram equalization, optimization for perceptual visual quality, structural similarity gradient ascent, histogram watermarking, contrast enhancement

Magnetic and superconducting instabilities of the Hubbard model at the van Hove filling

We use a novel temperature-flow renormalization group technique to analyze magnetic and superconducting instabilities in the two-dimensional t-t' Hubbard model for particle densities close to the van Hove filling as a function of the next-nearest neighbor hopping t'. In the one-loop flow at the van Hove filling, the characteristic temperature for the flow to strong coupling is suppressed drastically around t'_c approx. -0.33t, suggesting a quantum critical point between d-wave pairing at moderate t'>t'_c and ferromagnetism for t'<t'_c. Upon increasing the particle density in the latter regime the leading instability occurs in the triplet pairing channel.Comment: 4 pages, to appear in Physical Review Letter

Los insectos plaga del camu camu (Myrciaria dubia H.B.K.) y del araza (Eugenia stipitata Mc Vaugh) identificacion y control

Le camu camu (#Myrciaria dubio H.B.K.) et l'araza (#Eugenia stipitata Mc Vaugh) sont des cultures nouvelles en Amazonie péruvienne. Dans ce travail sont citées 21 espèces d'insectes nuisibles au camu camu, parmi lesquelles 6 espèces doivent être considérées comme des ravageurs économiquement importants, ce sont : #Austrotachardiella sp, #Ceroplastes sp., #Conotrachelus sp.1., #Dysmicoccus brevipes Cock, #Tuthillia cognata Hodk. y #Xylosandrus compactus Heichh. Sur araza 9 espèces ont été répertoriées, dont 4 sont des ravageurs importants : #Anastrepha obliqua Macq., #Atractomerus immigrans Clark, #Conotrachelus sp. 2 y #Plectrophoroides impressicollis Chevr. Quelques espèces nouvelles pour la science ont été décrites récemment ou sont en cours d'étude. On donne les premières informations sur les espèces dont la biologie et l'écologie n'étaient pas connues, ainsi que des méthodes de contrôle adaptées au système de gestion des plantations. (Résumé d'auteur

An intercomparison of flow around a 3D wall-mounted cylinder using TELEMAC-3D and OpenFOAM

Hydrodynamic

A comparative study of the passivation and localized corrosion of α-brass and β-brass in borate buffer solutions containing sodium chloride : III. The effect of temperature

The passivation and localized corrosion of α-brass and β-brass in an aqueous borate-boric acid buffer (pH 9) containing different concentrations of NaCl (cNaCl) in the temperature range 5 °C ≤ T ≤ 45 °C were studied comparatively by potential sweeping at 2 × 10−2Vs−1 and 2 × 10−4Vs−1 and de-alloying measurements. The passivation of α-brass and β-brass was related to the electroformation of a complex ZnO · xH2O/Cu2O layer, its thickness and compactness presumably increasing with temperature. For both α-brass and β-brass immersed in an aqueous NaCl-containing buffer, pitting corrosion was observed as the value of the breakdown potential (Eb) was exceeded. At constant temperature, the value of Eb shifted negatively as either cNaCl or the zinc content in the alloy was increased. For β-brass, the value of Eb decreased slightly with increasing temperature in the range 5 °C≤ T ≤45 °C. In the range 5 °C≤ T ≤ 25 °C, for α-brass the value of Eb was close to that reported for copper, whereas for T > 25 °C it approached those values measured for β-brass. De-alloying measurements in aqueous 0.5 M NaCl indicate that zinc surface enrichment of α-brass was responsible for the decrease in pitting corrosion resistance at T > 45 °C.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada