Tracking social provenance in chains of retweets

Knowledge and Information Systems - In the era of massive sharing of information, the term social provenance is used to denote the ownership, source or origin of a piece of information which has...     

Ensemble data assimilation in the presence of cloud

In numerical weather prediction (NWP) data assimilation (DA) methods are used to combine available observations with numerical model estimates. This is done by minimising measures of error on both observations and model estimates with more weight given to data that can be more trusted. For any DA method an estimate of the initial forecast error covariance matrix is required. For convective scale data assimilation, however, the properties of the error covariances are not well understood.An effective way to investigate covariance properties in the presence of convection is to use an ensemble-based method for which an estimate of the error covariance is readily available at each time step. In this work, we investigate the performance of the ensemble square root filter (EnSRF) in the presence of cloud growth applied to an idealised 1D convective column model of the atmosphere. We show that the EnSRF performs well in capturing cloud growth, but the ensemble does not cope well with discontinuities introduced into the system by parameterised rain. The state estimates lose accuracy, and more importantly the ensemble is unable to capture the spread (variance) of the estimates correctly. We also find, counter-intuitively, that by reducing the spatial frequency of observations and/or the accuracy of the observations, the ensemble is able to capture the states and their variability successfully across all regimes.     

Leachability of degradation products from hard chairside reline resins in artificial saliva: Effect of water‐bath post‐polymerization treatment

The effect of a post‐polymerization treatment on the leaching of methacrylic acid (MA) and benzoic acid (BA) from the reline resins [Kooliner (K), New Truliner (N), Ufi Gel hard (U), and Tokuso Rebase Fast (T)] was evaluated. Specimens of each material were divided into two groups: Group C (control) – left untreated; Group WB (water‐bath) – immersion in water at 55 ± 1°C for 10 min. Specimens were placed in artificial saliva at 37 ± 1°C and, after 1‐, 3‐, 5‐, 24‐h and 3‐, 7‐, 14‐, and 30‐day intervals, aliquots were removed and analyzed using high performance liquid chromatography. Data were analyzed by using Wilcoxon, Mann–Whitney or Kruskal–Wallis tests (α = 0.05). At 1 h, the concentration of MA released from U control specimens was higher than those of the other ones, and decreased after 3 h. WB specimens released lower amounts of MA than control specimens only for material U, at the 1‐ and 3‐h periods. For all control specimens, concentrations of leached BA progressively decreased within 5 h and from 24 h to the end. WB specimens released significantly lower amounts of BA than did the control groups. The highest concentration of MA was leached from control specimens of Ufi Gel hard. Water‐bath post‐polymerization treatment caused a significant reduction in elution of BA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PIn. II. Comparative evaluation of SSM/I and TMI precipitable waterestimate for the Mediterranean Sea

For pt.I see ibid., vol.39, no.12, p.2566-74 (2001). To estimate integrated precipitable water vapor along with liquid water path and water vapor effective profile (i.e. standard atmospheric profile approximation), utilizing the Special Sensor Microwave/Imager (SSM/I) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometers, an operative procedure was developed and assessed. This procedure is based on a fast nonlinear physical inversion algorithm (PIn) developed by the authors. A large data set of near-coincident TMI and SSM/I data acquisitions were collected and used to supply the procedure. Retrieved parameters were compared against retrievals achieved with well-accepted statistical algorithms, and consistency between TMI and SSM/I retrievals was confirmed. As far as TMI and SSM/I precipitable water retrieving consistency is concerned, this research revealed a linear relationship up to 20 kg/m² and a general overestimate of TMI retrieving, for higher values. A new algorithm for obtaining integrated precipitable water from TMI brightness temperatures was introduced and the goodness of its accuracy was reported. The procedure proved to be reliable and portable and its integrated precipitable water vapor retrieving was assessed to be as accurate as the best radiometric retrieving algorithms, reported in literature. For SSM/I data, developed-procedure liquid water path estimates seemed to be in good agreement with statistical retrievals. Eventually the procedure provided effective water vapor vertical profiles which belong to a deterministic distribution area characterized by an upper and lower limit; it was confirmed that SSM/I and TMI vertical profile distribution areas mainly overlap even if they are characterized by different sensitivities to profile parameters     

A technique for improving depolarization measurements beyond 10 GHz: Tilting the polarization planes

Depolarization measurements in linear polarization aiming at determining the effective canting angle of the principal planes and the related anisotropy can be improved, in many important cases, by adopting the simple expedient of tilting the polarization planes with respect to the vertical/horizontal orientations. Optimum tilt angles depend on the system configuration but the choice is not critical in a range spanning from about20degto about30degprovided that the disturbance is small enough (say 50 dB under the copolar level) and/or the anisotropy of the medium is large enough (say 2 dB in the differential attenuation).     

Anodic oxidation of wastewater containing the Reactive Orange 16 Dye using heavily boron-doped diamond electrodes

Boron-doped diamond (BDD) films grown on the titanium substrate were used to study the electrochemical degradation of Reactive Orange (RO) 16 Dye. The films were produced by hot filament chemical vapor deposition (HFCVD) technique using two different boron concentrations. The growth parameters were controlled to obtain heavily doped diamond films. They were named as E1 and E2 electrodes, with acceptor concentrations of 4.0 and 8.0 × 10²¹ atoms cm⁻³, respectively. The boron levels were evaluated from Mott-Schottky plots also corroborated by Raman's spectra, which characterized the film quality as well as its physical property. Scanning Electron Microscopy showed well-defined microcrystalline grain morphologies with crystal orientation mixtures of (1 1 1) and (1 0 0). The electrode efficiencies were studied from the advanced oxidation process (AOP) to degrade electrochemically the Reactive Orange 16 azo-dye (RO16). The results were analyzed by UV/VIS spectroscopy, total organic carbon (TOC) and high-performance liquid chromatography (HPLC) techniques. From UV/VIS spectra the highest doped electrode (E2) showed the best efficiency for both, the aromaticity reduction and the azo group fracture. These tendencies were confirmed by the TOC and chromatographic measurements. Besides, the results showed a direct relationship among the BDD morphology, physical property, and its performance during the degradation process.     

Influence of O2 on the quality of virgin olive oil during malaxation

The aim of this work was to investigate the effect of malaxation operating conditions on virgin olive oil quality. Legal, sensory and nutritional parameters of olive oil were evaluated by identifying the role played by enzymes. A comparison was made between oil obtained from a traditional malaxation plant and oil obtained from malaxation equipment (LOM) able to work at low oxygen level and temperature. Research results showed that, during malaxation, oxygen had an effect on both phenolic compounds and fatty acids, mainly favouring enzyme phenomena. Malaxation at a low oxygen level was found to be selective for the formation of both phenolic and C₆ compounds. Oil obtained from malaxation LOM equipment was shown to be richer in both aldehydes such as trans‐2‐hexenal and phenolic compounds than oil obtained from traditional processing. Copyright © 2006 Society of Chemical Industry     

Anatomy,micromorphology, and histochemistry of leaves and stems of Cantinoa althaeifolia (Lamiaceae)

This article enumerates the detailed anatomy of Cantinoa althaeifolia (Lamiaceae) illustrated with light and scanning electron microscopy images. The anatomical markers include the presence of branched nonglandular trichomes and capitate, peltate, and clavate types of glandular trichomes; prismatic crystals on the leaf and stem surfaces; and oil droplets in the leaf mesophyll. Histochemical tests and EDS analyses were performed in order to detect the composition of certain cells and their contents. The key findings of the present study can contribute to the taxonomy, species identification, and quality control of Cantinoa althaeifolia.     

How “flat” is the rich premixed flame produced by your McKenna burner?

McKenna burners are widely used in the combustion community for producing “flat” premixed flames. These flames are considered as standards for the development and calibration of optical techniques. Rich premixed flames produced by McKenna burners are frequently investigated in order to understand soot formation processes both by optical and by sampling techniques. Measurements are normally performed along the axis of the flames, with a uniform distribution of temperature and species concentration assumed in the radial direction. In this work it is shown that the soot radial profiles of rich premixed ethylene–air flames produced by a McKenna burner with a stainless steel porous plug may be far from being “flat.” Soot is mainly distributed in an annular region and nonsoot fluorescing species are present in the core of the flames. This surprising result was verified under several working conditions. Furthermore, flames cannot be considered axial-symmetric but present a skewed soot distribution. Another McKenna burner with a bronze porous disk was used to produce flames of the same equivalence ratio and flows. These flames show a completely different soot radial profile, closer to the claimed flat distribution. These results cast doubts about the conclusions drawn in several studies on soot formation performed with a stainless steel McKenna burner.     

Application of the Hough transform for the automatic determination of soot aggregate morphology

We report a new method for automated identification and measurement of primary particles within soot aggregates as well as the sizes of the aggregates and discuss its application to high-resolution transmission electron microscope (TEM) images of the aggregates. The image processing algorithm is based on an optimized Hough transform, applied to the external border of the aggregate. This achieves a significant data reduction by decomposing the particle border into fragments, which are assumed to be spheres in the present application, consistent with the known morphology of soot aggregates. Unlike traditional techniques, which are ultimately reliant on manual (human) measurement of a small sample of primary particles from a subset of aggregates, this method gives a direct measurement of the sizes of the aggregates and the size distributions of the primary particles of which they are composed. The current version of the algorithm allows processing of high-resolution TEM images by a conventional laptop computer at a rate of 1-2 ms per aggregate. The results were validated by comparison with manual image processing, and excellent agreement was found.