Opacity Measurements Research Articles

The relevance of financial and economic informational environment: evidence from South Asian markets

PurposeThis study aims to explore the firm's specific, opacity and economy-specific variables to explain the variation in South Asian market returns and indicate that how the difference in adoption of accounting standards refers to the effect of the movement in stock returns.Design/methodology/approachFollowing the scope of the study, factor analysis, fixed effect, Driscoll and Kraay standard errors (DKSE) and Panel Corrected standard error (PCSE) models have been inducted to determine the influence of firm-specific, opacity and economy-specific variables on stock returns. The sample of study comprises 1,885 firms from five countries located in the South Asia region with the period 2005–2018. To ensure the reliability of data, firm-specific data have been collected from DataStream International, while an international country risk guide was used to compile the data for economy-specific variables.FindingsThis study concluded that firm-specific variables showed a consistent and significant association with stock return except for beta, accrual and momentum while earning aggressiveness was the only factor in opacity measure to capture the variation in stock return. The implementation of international accounting standards seemed to be significant and proves to be helpful to enhance the quality of accounting information.Research limitations/implicationsThe limitations of this study comprised the estimation error by avoiding the firm's observations with negative equity in case of earning opacity and majority (more than 50%) of the observation belongs to a single market as India out of final sample which leads to having biasedness in findings.Practical implicationsThis study helps the investors to consider the firms with smaller market capitalization and lower book to market ratio and avoid the momentum strategy under firm specific factors. Moreover, earning aggressiveness under opacity domain capture the variation in stock return and must be considered while investing funds.Originality/valueThe influence of adoption of international accounting standards along with firm and economy specific variable in South Asian Equity Markets return was the major contribution. Moreover, the inclusion of DKSE and PCSE models to examine the relevance of the financial and economic informational environment was also considered as a part of major contribution of this study.

Systematic errors in dust mass determinations: insights from laboratory opacity measurements

ABSTRACTThe thermal emission of dust is one of the most important tracers of the interstellar medium: multiwavelength photometry in the far-infrared (FIR) and submillimetre (submm) can be fitted with a model, providing estimates of the dust mass. The fit results depend on the assumed value for FIR/submm opacity, which in most models – due to the scarcity, until recently, of experimental measurements – is extrapolated from shorter wavelengths. Lab measurements of dust analogues, however, show that FIR opacities are usually higher than the values used in models and depend on temperature, which suggests that dust mass estimates may be biased. To test the extent of this bias, we create multiwavelength synthetic photometry for dusty galaxies at different temperatures and redshifts, using experimental results for FIR/submm dust opacity and then we fit the synthetic data using standard dust models. We find that the dust masses recovered by typical models are overestimated by a factor of 2–20, depending on how the experimental opacities are treated. If the experimental dust samples are accurate analogues of interstellar dust, therefore, current dust masses are overestimated by up to a factor of 20. The implications for our understanding of dust, both Galactic and at high redshift, are discussed.

Catalytic Paper Filters for Diesel Soot Abatement: Studies at Laboratory and Bench Scales

A scaling-up of the impregnation process for the preparation of catalytic ceramic papers was developed by which Co and Ce oxides were incorporated on to a ceramic paper structure. To this end, a spray generator and a vacuum system were coupled, allowing the preparation of catalytic ceramic papers in the form of circular sheets 16 cm in diameter and 0.3-cm thick. The catalytic papers were set inside a metallic case in order to conform a diesel particulate filter (DPF), which was tested at bench scale placing the filter at the exhaust pipe of a FIAT turbocharged diesel engine. The catalytic ceramic papers showed elevated capacity to trap soot particles, as opacity measurements indicated. Temperature-programmed oxidation (TPO) was employed to evaluate the performance of the catalytic systems both for the simultaneous combustion of soot and hydrocarbons collected after test bench runs. TPO results for soot combustion on catalytic papers prepared at laboratory scale (1.6 cm diameter) were compared with those obtained for the scaled-up system (16 cm diameter) incorporating soot from a suspension of the carbonaceous particles in n-hexane. Similar activities were obtained, indicating the success of the scaling-up procedure. Bench-scale tests showed that catalytic ceramic papers have mechanical and catalytic properties adequate to be used as DPF.

Measurements of the Ka Band opacity of sulfuric acid vapor with application towards radio occultations of Venus

Radio occultation experiments are capable of providing insight into the properties of the Venus atmosphere at the boundary between the upper and lower atmosphere. To retrieve vertical profiles of atmospheric gases from Venus radio occultation experiments, accurate models for the absorption of these gases are necessary. New laboratory measurements have been made of the microwave opacity of H2SO4 vapor at Ka Band (30–45 GHz, 6.5–10 mm) in mixtures containing up to 3 bars of CO2 at temperatures ranging from 550 to 585 K, simulating the conditions of the lower atmosphere of Venus. The results of these measurements and prior microwave and millimeter-wavelength laboratory studies have been used to derive a model for H2SO4 vapor opacity valid from 1 to 150 GHz. This model is incorporated into a microwave radiative transfer model of the Venus atmosphere, which has been used to predict the penetration depth of a radio occultation signal at 32 GHz and determine the contributions of atmospheric gases to 32 GHz opacity. These results can be used to interpret signal attenuation profiles for future Ka Band radio occultations of Venus.

Opacity Measures of Fuzzy Discrete Event Systems

Opacity, as an important security property, has been well investigated in crisp discrete event systems. However, in some practical systems, the general behaviors, secret and nonsecret behaviors obtained by the intruder need to be expressed as fuzzy sets rather than crisp sets. Under this situation, the intruder makes inferences by fuzzy logic rather than classic logic, thus the notions of the fuzzy opacity measures are desired to be established. First, by means of the basic laws of fuzzy logic, a general fuzzy opacity measure, as a template, is presented, in this article, for the given generalized characterizations of secret and nonsecret behaviors. Moreover, a specific measure, called as fuzzy initial-final opacity (FIFO) measure, is investigated under the assumption that the secrets and nonsecrets can be coded into the initial-final state-pairs. In addition, two variants of FIFO measure are also proposed under the assumptions that the secrets and nonsecrets are only related to the initial-states or final-states. With these fuzzy opacity measures, the system designers can evaluate the opacity degree of the systems to be designed. To show the applicability of the fuzzy opacity measures to practical systems, we finally present an illustrative example of evaluating the location privacy protection systems in location-based services by means of the fuzzy opacity measures.

Interpretation of Lyman opacity measurements in JET with the ITER-like wall using a particle balance approach

Recent measurements of the Lyβ/Dα ratio in the JET ITER-like wall (ILW) divertor show comparatively more pronounced Lyβ reabsorption relative to previous results in JET with the carbon wall (JET-C). At the outer horizontal target ion current rollover point a Lyβ reabsorption rate of 60% is measured, increasing to 80% in more pronounced detachment, implying a Lyα reabsorption rate of 90%–98%. The radially resolved Lyβ/Dα measurements are used to constrain Lyman opacity corrections to atomic rate coefficients using the population escape factor technique in order to capture the local changes to the excited state population structure in the high Lyman opacity regions at and outboard of the outer strike point. To check the self-consistency of the Lyman opacity measurements, a detailed spectroscopic interpretation of the outer divertor particle balance is presented, in which the impact of opacity corrections to the Lyα inverse photon efficiency coefficients is assessed. A five-fold deficit in the estimated D+ source rate obtained with optically thin plasma assumptions is reconciled once the opacity corrections are factored into the Lyα photon rate to ionization rate conversion. The experiment results are reproduced in EDGE2D-EIRENE density scan simulations in which an imposed ad hoc Lyman reabsorption rate is recovered spectroscopically using synthetic measurements, and a similar shortfall in the D+ source rate estimates is reconciled using Lyman opacity corrected atomic data. The model limitations prevent a more detailed self-consistent analysis of the Lyman opacity impact on divertor parameters and detachment evolution, and hence motivate renewed efforts to re-establish routine exploitation of the photon transport modelling capabilities in the EIRENE code package. Lyman opacity corrections to atomic data coefficients are necessary for spectroscopic interpretation of the JET-ILW divertor plasma, with significant influence on the divertor plasma also a likely consequence of the presence of strong Lyα reabsorption. Finally, a scan of auxiliary heating powers spanning L-mode and H-mode conditions reveals a strong correlation of the measured Lyβ opacity with the outer target temperature, suggesting new possibilities for using Lyman opacity measurements in establishing detachment scalings.

Do Japanese firms systematically inflate expected rate of returns from defined benefit pension plans?

Japanese firms systematically inflate expected rate of returns (ERRs) on pension assets relative to several benchmark rates including actual rate of returns (ARRs), historical ARRs, and future expected ARRs. The Accounting Standard Board of Japan began requiring firms to disclose asset allocation in 2013. With asset allocation data, we are able to infer the implied equity returns assumed by managers to be 6.61% per annum. The implied cost of equity from the Gebhardt, Lee, and Swaminathan (2001) model is 5.47% per annum. The difference is highly significant. Japanese managers are more optimistic about equity returns in their pension assets than what typical market investors anticipate from the stock market. We finally construct accrual-based earnings opacity measures and find that Japanese firms with more opaque earnings are more inclined to manage pension parameters to boost reported earnings.

Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b

Aims. The atmospheres of ultra-hot Jupiters (UHJs) are commonly considered to be at thermochemical equilibrium. We aim to provide disequilibrium chemistry maps for a global understanding of the chemistry in the atmosphere of HAT-P-7b and assess the importance of disequilibrium chemistry on UHJs. Methods. We applied a hierarchical modeling approach using 97 1D atmospheric profiles from a 3D general circulation model of HAT-P-7b. For each atmospheric 1D profile, we evaluated our kinetic cloud formation model consistently with the local gas-phase composition in chemical equilibrium. This served as input to study the quenching of dominating CHNO-binding molecules. We evaluated quenching results from a zeroth-order approximation in comparison to a kinetic gas-phase approach. Results. We find that the zeroth-order approach of estimating quenching points agrees well with the full gas-kinetic modeling results. However, it underestimates the quenching levels by about one order of magnitude at high temperatures. Chemical disequilibrium has the greatest effect on the nightside and morning abundance of species such as H, H2O, CH4, CO2, HCN, and all CnHm molecules; heavier CnHm molecules are more affected by disequilibrium processes. The CO abundance, however, is affected only marginally. While dayside abundances also notably change, those around the evening terminator of HAT-P-7b are the least affected by disequilibrium processes. The latter finding may partially explain the consistency of observed transmission spectra of UHJs with atmospheres in thermochemical equilibrium. Photochemistry only negligibly affects molecular abundances and quenching levels. Conclusions. In general, the quenching points of the atmosphere of HAT-P-7b are at much lower pressures than in the cooler hot-jupiters. We propose several avenues to determining the effect of disequilibrium processes on UHJs that are in general based on abundance and opacity measurements at different local times. It remains a challenge to completely disentangle this from the chemical effects of clouds and that of a primordial nonsolar abundance.

A cosmic UV/X-ray background model update

ABSTRACT We present an updated model of the cosmic ionizing background from the UV to the X-rays. Relative to our previous model, the new model provides a better match to a large number of up-to-date empirical constraints, including: (1) new galaxy and AGN luminosity functions; (2) stellar spectra including binary stars; (3) obscured and unobscured AGN; (4) a measurement of the non-ionizing UV background; (5) measurements of the intergalactic H i and He ii photoionization rates at z ∼ 0−6; (6) the local X-ray background; and (7) improved measurements of the intergalactic opacity. In this model, AGN dominate the H i ionizing background at z ≲ 3 and star-forming galaxies dominate it at higher redshifts. Combined with the steeply declining AGN luminosity function beyond z ∼ 2, the slow evolution of the H i ionization rate inferred from the high-redshift H i Ly α forest requires an escape fraction from star-forming galaxies that increases with redshift (a population-averaged escape fraction of $\approx 1{{\ \rm per\ cent}}$ suffices to ionize the intergalactic medium at z = 3 when including the contribution from AGN). We provide effective photoionization and photoheating rates calibrated to match the Planck 2018 reionization optical depth and recent constraints from the He ii Ly α forest in hydrodynamic simulations.

A quantitative study of some sources of uncertainty in opacity measurements

Laboratory (laser and Z-pinch) opacity measurements of well-characterized plasmas provide data to assist inertial confinement fusion, astrophysics and atomic-physics research. In order to test the atomic-physics codes devoted to the calculation of radiative properties of hot plasmas, such experiments must fulfill a number of requirements. In this work, we discuss some sources of uncertainty in absorption-spectroscopy experiments, concerning areal mass, background emission, intensity of the backlighter and self-emission of the plasma. We also study the impact of spatial non-uniformities of the sample.

Development of Bio-Active Patches Based on Pectin for the Treatment of Ulcers and Wounds Using 3D-Bioprinting Technology.

Biodegradable 3D-printable inks based on pectin have been developed as a system for direct and indirect wound-dressing applications, suitable for 3D printing technologies. The 3D-printable inks formed free-standing transparent films upon drying, with the latter exhibiting fast disintegration upon contact with aqueous media. The antimicrobial and wound-healing activities of the inks have been successfully enhanced by the addition of particles, comprised of chitosan and cyclodextrin inclusion complexes with propolis extract. Response Surface Methodology (RSM) was applied for the optimization of the inks (extrusion-printing pressure, shrinkage minimization over-drying, increased water uptake and minimization of the disintegration of the dry patches upon contact with aqueous media). Particles comprised of chitosan and cyclodextrin/propolis extract inclusion complexes (CCP), bearing antimicrobial properties, were optimized and integrated with the produced inks. The bioprinted patches were assessed for their cytocompatibility, antimicrobial activity and in vitro wound-healing properties. These studies were complemented with ex vivo skin adhesion measurements, a relative surface hydrophobicity and opacity measurement, mechanical properties, visualization, and spectroscopic techniques. The in vitro wound-healing studies revealed that the 3D-bioprinted patches enhanced the in vitro wound-healing process, while the incorporation of CCP further enhanced wound-healing, as well as the antimicrobial activity of the patches.

Bank Opacity and Systemic Risk

This paper examines the impact of bank opacity on European financial stability. Based on a panel dataset of capital market-oriented European banks covering the period 2002-2018, it can be shown that bank opacity has a significant influence on the institution-specific contribution to the ∆Conditional Value at Risk and Marginal Expected Shortfall. The policies introduced by accounting standard setters and regulators for the risk disclosure of banks have a positive impact on the mitigation of bank opacity and reducing systemic risk. Both the risk reporting in accordance with IFRS 7 and the measures introduced by the Basel Committee in the form of the Basel Pillar 3 Regulation lead to an increase in transparency (reduction of Bank Opacity) and thus to an improvement in financial market stability. The results are robust, both by using alternative opacity measures and by using dynamic panel data models (GMM) to control for endogeneity.

Ab initio simulations and measurements of the free-free opacity in aluminum.

The free-free opacity in dense systems is a property that both tests our fundamental understanding of correlated many-body systems, and is needed to understand the radiative properties of high energy-density plasmas. Despite its importance, predictive calculations of the free-free opacity remain challenging even in the condensed matter phase for simple metals. Here we show how the free-free opacity can be modelled at finite-temperatures via time-dependent density functional theory, and illustrate the importance of including local field corrections, core polarization, and self-energy corrections. Our calculations for ground-state Al are shown to agree well with experimental opacity measurements performed on the Artemis laser facility across a wide range of extreme ultraviolet wavelengths. We extend our calculations across the melt to the warm-dense matter regime, finding good agreement with advanced plasma models based on inverse bremsstrahlung at temperatures above 10eV.

Progress toward NIF opacity measurements

The opacities of iron and other mid-Z elements help to regulate the transport of energy in the sun. Recent experiments on the Sandia National Laboratories Z machine have shown large discrepancies between the measured and calculated opacities of iron at certain solar conditions. To replicate these opacity measurements a platform is being developed on the National Ignition Facility to measure the opacities of iron and other elements at the same conditions as in the Z experiments. The NIF platform consists of a hohlraum to heat the opacity sample to the desired conditions, a separate backlighter to radiograph the sample, and a spectrometer to give the spectrally resolved opacity. Not only must the opacity be measured but the temperature and density of the sample must also be accurately determined. This platform has now produced its first iron transmission measurements. These measurements will be presented along with plans for future measurements and details on how the measurements will be improved.

Free-free matrix-elements for two-photon opacity

Recent opacity measurements have inspired a close study of the two-photon contributions to the opacity of hot plasmas. The absorption and emission of radiation is controlled by dipole matrix-elements of electrons in an atom or ion. This paper describes two independent methods to calculate matrix-elements needed for the two-photon opacity and tests the results by the f-sum rule. The usual f-sum rule is extended to a matrix f-sum that offers a rigorous test for bound-bound, bound-free and free-free transitions. An additional higher-order sum-rule for the two-photon transition amplitudes is described. We obtain a simple parametric representation of a key plasma density effect on the matrix-elements.The perturbation theory calculation of two-photon cross-sections is compared to an independent method based on the solution of the time-dependent Schroedinger equation for an atom or ion in a high-frequency electromagnetic field. This is described as a high frequency Stark effect or AC Stark effect. Two-photon cross sections calculated with the AC Stark code agree with perturbation theory to within about 5%. In addition to this cross check, the AC Stark code is well suited to evaluating important questions such as the variation of two-photon opacity for different elements.

The Radial Distribution of Dust Particles in the HL Tau Disk from ALMA and VLA Observations

Abstract Understanding planet formation requires one to discern how dust grows in protoplanetary disks. An important parameter to measure in disks is the maximum dust grain size present. This is usually estimated through measurements of the dust opacity at different millimeter wavelengths assuming optically thin emission and dust opacity dominated by absorption. However, Atacama Large Millimeter/submillimeter Array (ALMA) observations have shown that these assumptions might not be correct in the case of protoplanetary disks, leading to overestimation of particle sizes and to underestimation of the disk’s mass. Here, we present an analysis of high-quality ALMA and Very Large Array images of the HL Tau protoplanetary disk, covering a wide range of wavelengths, from 0.8 mm to 1 cm, and with a physical resolution of ∼7.35 au. We describe a procedure to analyze a set of millimeter images without any assumption about the optical depth of the emission, and including the effects of absorption and scattering in the dust opacity. This procedure allows us to obtain the dust temperature, the dust surface density, and the maximum particle size at each radius. In the HL Tau disk, we found that particles have already grown to a few millimeters in size. We detect differences in the dust properties between dark and bright rings, with dark rings containing low dust density and small dust particles. Different features in the HL Tau disk seem to have different origins. Planet–disk interactions can explain substructure in the external half of the disk, but the internal rings seem to be associated with the presence of snow lines of several molecules.

Visibility and Line‐of‐Sight Extinction Estimates in Gale Crater During the 2018/MY34 Global Dust Storm

AbstractNorthern line‐of‐sight extinction within Gale Crater during the 2018 global dust storm was monitored daily using Mars Science Laboratory's Navcam. Additional observations with Mastcam (north) and Navcam (all directions) were obtained at a lower cadence. Using feature identification and georeferencing, extinction was estimated in all possible directions. Peak extinction of >1.1 km−1 was measured between sols 2086 and 2090, an order of magnitude higher than previous maxima. Northern and western directions show an initial decrease, followed by a secondary peak in extinction, not seen in column opacity measurements. Due to foreground topography, eastern direction results are provided only as limits, and southern results were indeterminable. Mastcam red and green filter results agree well, but blue filter results show higher extinctions, likely due to low signal‐to‐noise. Morning results are systematically higher than afternoon results, potentially indicative of atmospheric mixing.

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

We present solutions of the radiative transfer equation for cylinders, hollow hemi-ellipsoidal shells and tori for a uniform plasma of fixed geometry. The radiative transfer equation is explicitly solved for two directions of emission, parallel and perpendicular to the axis of symmetry. The ratio between the fluxes in these two directions is also calculated and its use in measuring the frequency resolved opacity of the plasma is discussed. We find that the optimal geometry to use this ratio as an opacity measurement is a planar geometry.

A plea for a measure of opacity: Psychoanalysis in an age of transparency Annual Birkbeck Counselling Association Lecture December 2018

‘Whatever can be catalogued is an occasion for despair’. Gabriel Marcel (1964).Ever since the Enlightenment, knowledge has been linked to the metaphor of light. The idea that ‘to see is to know’ so firmly grounds our current way of being in and understanding the world it is hard to imagine otherwise. But our insistence on open government, freedom of information and the public’s right to know privileges not only the visibility of information but also the visibility of the self. In this paper, I consider how we might think about and respond to the ever-increasing demand for transparency in the consulting room. I draw on the ideas of Derrida, Laplanche and Glissant to argue for what has been called ‘the right to opacity’, suggesting that psychoanalytic practitioners are particularly well placed to offer a critical perspective on today’s culture of surveillance.

Cornstarch-based wound dressing incorporated with hyaluronic acid and propolis: In vitro and in vivo studies

The unique physicochemical and functional characteristics of starch-based biomaterials and wound dressings have been proposed for several biomedical applications. Film dressings of cornstarch/hyaluronic acid/ ethanolic extract of propolis (CS/HA/EEP) were prepared by solvent-casting and characterized by attenuated total reflectance/Fourier transform infrared spectroscopy, scanning electron microscopy, gas chromatography/mass spectrometry, light transmission, opacity measurements, EEP release, equilibrium swelling, and in vitro and in vivo evaluations. The CS/HA/0.5%EEP film dressing exhibited higher antibacterial activity against Staphylococcus aureus (2.08 ± 0.14 mm), Escherichia coli (2.64 ± 0.18 mm), and Staphylococcus epidermidis (1.02 ± 0.15 mm) in comparison with the CS, CS/HA, and CS/HA/0.25%EEP films. Also, it showed no cytotoxicity for the L929 fibroblast cells. This wound dressing could effectively accelerate the wound healing process at Wistar rats' skin excisions. These results indicate that enrichment of cornstarch wound dressings with HA and EEP can significantly enhance their potential efficacy as wound dressing material.