A multiple scales approach to evaporation induced Marangoni convection

This paper considers the stability of thin liquid layers of binary mixtures of a volatile (solvent) species and a non-volatile (polymer) species. Evaporation leads to a depletion of the solvent near the liquid surface. If surface tension increases for lower solvent concentrations, sufficiently strong compositional gradients can lead to Bénard-Marangoni-type convection that is similar to the kind which is observed in films that are heated from below. The onset of the instability is investigated by a linear stability analysis. Due to evaporation, the base state is time dependent, thus leading to a non-autonomous linearised system, which impedes the use of normal modes. However, the time scale for the solvent loss due to evaporation is typically long compared to the diffusive time scale, so a systematic multiple scales expansion can be sought for a finite dimensional approximation of the linearised problem. This is determined to leading and to next order. The corrections indicate that sufficient separation of the top eigenvalue from the remaining spectrum is required for the validity of the expansions, but not the magnitude of the eigenvalues themselves. The approximations are applied to analyse experiments by Bassou and Rharbi with polystyrene/toluene mixtures [Langmuir 2009 (25) 624–632]

The theory of the fluctuations in brightness of the Milky way. II.

In this paper the integral equation governing the fluctuations in brightness of the Milky Way is considered for the case in which the system extends to infinity in the direction of the line of sight. The equation is explicitly solved for the two cases in which all the clouds are equally transparent and when the frequency of occurrence of clouds with a transparency factor q is (n + 1)qn. The derived distributions of brightness are illustrated

The theory of the fluctuations in brightness of the Milky Way. III

In this paper the integral equation (derived in Paper I) governing the fluctuations in brightness of the Milky Way is explicitly solved for the case in which the system extends to a finite distance in the direction of the line of sight and when all the clouds are equally transparent, The derived theoretical distributions are illustrated

The theory of the fluctuations in brightness of the Milky way. I.

In this paper the following statistical problem is considered. Let stars and interstellar clouds occur with a uniform distribution. Let the system extend to a linear distance L in the direction of a line of sight. Let a cloud reduce the intensity of the light of the stars immediately behind it by a factor q. Let the occurrence of clouds with a transparency factor q be governed by a frequency function ψ(q). Given all this, - it is required to find the probability distribution, g(I, L), of the observed brightness, I. From a consideration of this problem it is shown that the following integral equation governs the distribution of brightness: g(u+ξ)+∂g/∂u+∂g/∂ξ=∫10g(u/q,ξ)ψ(q)dq/q, where u is the observed brightness measured in suitable units and ξ is the average number of clouds in the direction of the line of sight. It is further shown that the foregoing integral equation enables us to obtain explicit formulae for all the moments of g as functions of ξ and the moments of ψ(q). As an illustration of the use of these general formulae for the moments, an example investigated by Markarian has been reconsidered in an attempt to derive the mean and mean-square deviation of the optical thicknesses of the interstellar clouds

Infrared Spectra of Low-Temperature Stars

Spectra of stars of types M, N(R), and S, as well as of NML objects in Cygnus and Taurus, are presented in the regions ⋋⋋l 5-1.8 μ and ⋋⋋l 9-2 5 μ. In M stars the absorption due to stellar H_2O is apparent from the wings of the bands at ⋋l.4, ⋋l.9, and ⋋2.7 μ Stars of N and S types show weaker H_2O absorption. The Δv = 2 and Δv = 3 vibration-rotation band sequences of CO appear well marked in all stars, being somewhat weaker in the M types than in other stars. The late N stars Y CVn and U Hyd show a sharp discontinuity or band head at ⋋l.76 μ not present in other stars. The entire spectra of Y CVn and U Hyd shortward of this discontinuity appears veiled, the Δv = 3 CO band sequence being conspicuously weak. The spectra of the NML objects in Cygnus and Taurus have spectral characteristics resembling the carbon more than the M stars

Infrared Coronal Lines. II. Observation of [SI x] λ 1.43 μ and [Mg VIII] λ 3.03 μ

The wavelengths and intensities of the coronal lines of the ions Si^(9+) and Mg^(8+), resulting from the airborne observation of the November 12, 1966, total solar eclipse, are given

Controlled topological transitions in thin film phase separation

In this paper the evolution of a binary mixture in a thin-film geometry with a wall at the top and bottom is considered. By bringing the mixture into its miscibility gap so that no spinodal decomposition occurs in the bulk, a slight energetic bias of the walls towards each one of the constituents ensures the nucleation of thin boundary layers that grow until the constituents have moved into one of the two layers. These layers are separated by an interfacial region where the composition changes rapidly. Conditions that ensure the separation into two layers with a thin interfacial region are investigated based on a phase-field model. Using matched asymptotic expansions a corresponding sharp-interface problem for the location of the interface is established. It is then argued that this newly created two-layer system is not at its energetic minimum but destabilizes into a controlled self-replicating pattern of trapezoidal vertical stripes by minimizing the interfacial energy between the phases while conserving their area. A quantitative analysis of this mechanism is carried out via a thin-film model for the free interfaces, which is derived asymptotically from the sharp-interface model.Comment: Submitted 23/12/201

Children's emotion understanding: A meta-analysis of training studies.

BACKGROUND: In the course of development, children show increased insight and understanding of emotions-both of their own emotions and those of others. However, little is known about the efficacy of training programs aimed at improving children's understanding of emotion. OBJECTIVES: To conduct an effect size analysis of trainings aimed at three aspects of emotion understanding: external aspects (i.e., the recognition of emotional expressions, understanding external causes of emotion, understanding the influence of reminders on present emotions); mental aspects (i.e., understanding desire-based emotions, understanding belief-based emotions, understanding hidden emotions); and reflective aspects (i.e., understanding the regulation of an emotion, understanding mixed emotions, understanding moral emotions). DATA SOURCES: A literature search was conducted using PubMed, PsycInfo, the Cochrane Library, and manual searches. REVIEW METHODS: The search identified 19 studies or experiments including a total of 749 children with an average age of 86 months (S.D.=30.71) from seven different countries. RESULTS: Emotion understanding training procedures are effective for improving external (Hedge's g = 0.62), mental (Hedge's g = 0.31), and reflective (Hedge's g = 0.64) aspects of emotion understanding. These effect sizes were robust and generally unrelated to the number and lengths of training sessions, length of the training period, year of publication, and sample type. However, training setting and social setting moderated the effect of emotion understanding training on the understanding of external aspects of emotion. For the length of training session and social setting, we observed significant moderator effects of training on reflective aspects of emotion. CONCLUSION: Emotion understanding training may be a promising tool for both preventive intervention and the psychotherapeutic process. However, more well-controlled studies are needed.R34 MH086668 - NIMH NIH HHS; R01 AT007257 - NCCIH NIH HHS; R21 MH101567 - NIMH NIH HHS; R34 MH099311 - NIMH NIH HHS; R21 MH102646 - NIMH NIH HHS; K23 MH100259 - NIMH NIH HHS; R01 MH099021 - NIMH NIH HH

Surface induced phase separation of a swelling hydrogel

We present a formulation of the free boundary problem for a hydrogel that accounts for the interfacial free energy and finite strain due to the large deformation of the polymer network during solvent transport across the free boundary. For the geometry of an initially dry layer fixed at a rigid substrate, our model predicts a phase transition when a critical value of the solvent concentration has been reached near the free boundary. A one-dimensional case study shows that depending on the flux rate at the free boundary an initial saturation front is followed by spinodal decomposition of the hydrogel and the formation of an interfacial front that moves through the layer. Moreover, increasing the shear modulus of the elastic network delays or even suppresses phase separation

Infrared radiometry experiment for Mariner Mars 1971

The infrared radiometer is designed to provide brightness temperatures of the surface of Mars by measuring the energy radiated in the 8 to 12 and 18 to 25 μ wavelength bands. The instrument is essentially the same as that flown on the Mariner Mars 1969 missions, modified only to define more sharply the field of view. Because Mariner Mars 1971 will orbit Mars, a given area of the planet will be observed at a variety of local times, and the characterization of the various areas by their thermophysical properties will be more complete than that obtained by Mariner Mars 1969