Recent advances in identifying the structure of liquid and glassy oxide and chalcogenide materials under extreme conditions: a joint approach using diffraction and atomistic simulation

The advent of advanced instrumentation and measurementprotocols makes it increasingly feasible to use X-ray andneutron diffraction methods to investigate the structureof liquid and glassy materials under extreme conditions ofhigh-temperatures and/or high-pressures. In particular, acombination of diffraction and modern simulation techniquesis allowing for an understanding of the structure of thesedisordered materials at both the atomistic and electronic levels.In this article, we highlight some of the recent work in solvingthe structure of liquid and glassy oxide and chalcogenidematerials under extreme conditions. We consider, in turn, theuse of aerodynamic levitation with laser heating to investigatethe structure of high-temperature oxide melts and tofabricate novel glassy materials by container-less processing;the use of high-pressure methods in the gigapascal regimeto investigate the mechanisms of network collapse for glassynetwork structures; and the simultaneous application of high pressuresand high-temperatures to explore the structure ofdisordered materials. Finally, we consider the use of otherquantum-beam diffraction-based techniques for probing theorder hidden in the correlation functions that describe thestructure of disordered matter

The association of metacognitive beliefs with emotional distress after diagnosis of cancer.

Objective: Emotional distress after a diagnosis of cancer is normal and, for most people, will diminish over time. However, a significant minority of patients with cancer experience persistent or recurrent symptoms of emotional distress for which they need help. A model developed in mental health, the self-regulatory executive function model (S-REF), specifies that maladaptive metacognitive beliefs and processes, including persistent worry, are key to understanding why such emotional problems persist. This cross-sectional study explored, for the first, time whether metacognitive beliefs were associated with emotional distress in a cancer population, and whether this relationship was mediated by worry, as predicted by the S-REF model. Method: Two hundred twenty-nine participants within 3 months of diagnosis of, and before treatment for, primary breast or prostate cancer completed self-report questionnaires measuring anxiety, depression, posttraumatic stress disorder (PTSD) symptoms, metacognitive beliefs, worry, and illness perceptions. Results: Regression analysis showed that metacognitive beliefs were associated with symptoms of anxiety, depression, and PTSD, and explained additional variance in these outcomes after controlling for age, gender, and illness perceptions. Structural equation modeling was consistent with cross-sectional hypotheses derived from the theory that metacognitive beliefs cause and maintain distress both directly and indirectly by driving worry. Conclusions: The findings provide promising first evidence that the S-REF model may be usefully applied in cancer. Further study is required to establish the predictive and clinical utility of these findings

Acquisition of acid vapor and aerosol concentration data for use in dry deposition studies in the South Coast Air Basin

An atmospheric monitoring network was operated throughout the South Coast Air Basin in the greater Los Angeles area during the year 1986. The primary objective of this study was to measure the spatial and temporal concentration distributions of atmospheric gas phase and particulate phase acids and bases in support of the California Air Resources Board's dry deposition research program. Gaseous pollutants measured include HNO_3, HCl, HF, HBr, formic acid, acetic acid and ammonia. The chemical composition of the airborne particulate matter complex was examined in three size ranges: fine particles (less than 2.2 μm aerodynamic diameter, AD), PM_(10) (less than 10 μm AD) and total particles (no size discrimination). Upwind of the air basin at San Nicolas Island, gas phase acids concentrations are very low: averaging 0.3 μg m^(-3) (0.1 ppb) for HNO_3, 0.8 μg m^(-3) for HCl, 0.13 μg m^(-3) for HF, and 2.6 μg m^(-3) for formic acid. Annual average HN03 concentrations ranged from 3.1 μg m^(-3) (1.2 ppb) near the Southern California coast to 6.9 μg m^(-3) (2.7 ppb) at an inland site in the San Gabriel Mountains. HCl concentrations within the South Coast Air Basin averaged from 0.8 μg m^(-3) to 1.8 μg m^(-3) during the year 1986. Long-term average HF concentrations within the air basin are very low, in the range from 0.14 to 0.22 μg m^(-3) between monitoring sites. Long-term average formic acid concentrations are lowest near the coastline (5.0 μg m^(-3) at Hawthorne), with the highest average concentrations (10.7 μg m^(-3)) observed inland at Upland. Ammonia concentrations at low elevation within the South Coast Air Basin average from 2.1 μg m^(-3) to 4.4 μg m^(-3) at all sites except Rubidoux. Rubidoux is located directly downwind of a large ammonia source created by dairy farming and other agricultural activities in the Chino area. Ammonia concentrations at Rubidoux average 30 μg m^(-3) during 1986, a factor of approximately 10 higher than elsewhere in the air basin. Annual average PM_(10) mass concentrations within the South Coast Air Basin ranged from 47.0 μg m^(-3) along the coast to 87.4 μg m^(-3) at Rubidoux, the farthest inland monitoring site. Five major aerosol components (carbonaceous material, NO_3^-, SO_4^-, NH_4^+ and soil-related material) accounted for greater than 80% of the annual average PM_(10) mass concentration at all on-land monitoring stations. A peak 24-h average PM_(10) mass concentration of 299 μg m^(-3) was observed at Rubidoux during 1986. That value is a factor of 2 higher than the federal 24-h average PM_(10) concentration standard, and a factor of 6 higher than the State of California PM_(10) standard. More than 40% of the PM_(10) aerosol mass measured at Rubidoux during that peak day event consisted of aerosol nitrates plus ammonium ion. Reaction of gaseous nitric acid to form aerosol nitrates was a major contributor to the high PM_(10) concentrations observed in the Rubidoux area near Riverside, California

Persistent homology in two-dimensional atomic networks

The topology of two-dimensional network materials is investigated by persistent homology analysis. The constraint of two dimensions allows for a direct comparison of key persistent homology metrics (persistence diagrams, cycles, Betti numbers) with more traditional metrics such as the ring-size distributions. Two different types of networks are employed in which the topology is manipulated systematically. In the first, comparatively rigid networks are generated for a triangle-raft model, which are representative of materials such as silica bilayers. In the second, more flexible networks are generated using a bond-switching algorithm, which are representative of materials such as graphene. Bands are identified in the persistence diagrams by reference to the length-scales associated with distorted polygons. The triangle-raft models with the largest ordering allow specific bands Bn (n = 1, 2, 3,. . .) to be allocated to configurations of atoms separated by n bonds. The persistence diagrams for the more disordered network models also display bands albeit less pronounced. The persistent homology method thereby provides information on n-body correlations that is not accessible from structure factors or radial distribution functions. An analysis of the persistent cycles gives the primitive ring statistics, provided the level of disorder is not too large. The method also gives information on the regularity of rings that is unavailable from a ring-statistics analysis. The utility of the persistent homology method is demonstrated by its application to experimentally-obtained configurations of silica bilayers and graphene

The North Atlantic circulation: Combining simplified dynamics with hydrographic data

We estimate the time-averaged velocity field in the North Atlantic from observations of density, wind stress and bottom topography. The flow is assumed geostrophic, with prescribed Ekman pumping at the surface, and no normal component at the bottom. These data and dynamics determine velocity to within an arbitrary function of (Coriolis parameter)/(ocean depth), which we call the “dynamical free mode.” The free mode is selected to minimize mixing of potential density at mid-depth. This tracer-conservation criterion serves as a relatively weak constraint on the calculation. Estimates of vertical velocity are particularly sensitive to variations in the free mode and to errors in density. In contrast, horizontal velocities are relatively robust. Below the thermocline, we predict a strong O (1 cm/sec) westward flow across the entire North Atlantic, in a narrow range of latitude between 25N and 32N. This feature supports the qualitative (and controversial) conjecture by Wüst (1935) of flow along the “Mediterranean Salt Tongue.” Along continental margins and at the Mid-Atlantic Ridge, predicted bottom velocity points along isobaths, with shallow water to the right. These flows agree with many long-term current measurements and with notions of the circulation based on tracer distributions. The results conflict with previous oceanographic-inverse models, which predict mid-depth flows an order of magnitude smaller and often in opposite directions. These discrepancies may be attributable to our relatively strong enforcement of the bottom boundary condition. This involves the plausible, although tenuous, assertion that the flow “feels” only the large-scale features of the bottom topography. Our objective is to investigate the consequences of using this hypothesis to estimate the North Atlantic circulation

Impact of pressure on the structure of glass and its material properties

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Voz y corporalidad: una propuesta pedagógica holística para el estudio del canto

En este trabajo de Comunicación, proponemos el desarrollo de una metodología para la enseñanza del Canto, a partir de principios de integración de procesos cognitivos, basada en la interacción creativa entre maestro y estudiante, en lo que denominamos una propuesta pedagógica holística. En ella, consideramos el ser en su totalidad, y promovemos un trabajo integrador de los múltiples aspectos que conforman la individualidad. Sostenemos que el reconocimiento y desarrollo de la propia voz, asumiendo la propia identidad vocal, es el punto de partida que conduce a la verdadera vocalidad. A partir de estas ideas, proponemos una serie de objetivos y recursos basados en la interacción entre los distintos aspectos corporales, vocales y psicológicos, tendientes a trascender la percepción fragmentada de los mismos, con miras a contribuir al desarrollo de recursos técnicos e interpretativos integrados entre sí, propiciando una actitud proactiva en el estudiante y el maestro. Incluimos en este trabajo los resultados de nuestra investigación Hacia el concepto de voz incorporada, en base a los cuales aportamos algunas conclusiones en relación a la implementación de esta metodología. Nuestra propuesta nos permite fomentar el desarrollo de la creatividad inherente a la actividad de todo intérprete.Sesión temática: Experiencia musical: Cognición CorporeizadaLaboratorio para el Estudio de la Experiencia Musica

Recent advances in identifying the structure of liquid and glassy oxide and chalcogenide materials under extreme conditions: a joint approach using diffraction and atomistic simulation

The advent of advanced instrumentation and measurementprotocols makes it increasingly feasible to use X-ray andneutron diffraction methods to investigate the structureof liquid and glassy materials under extreme conditions ofhigh-temperatures and/or high-pressures. In particular, acombination of diffraction and modern simulation techniquesis allowing for an understanding of the structure of thesedisordered materials at both the atomistic and electronic levels.In this article, we highlight some of the recent work in solvingthe structure of liquid and glassy oxide and chalcogenidematerials under extreme conditions. We consider, in turn, theuse of aerodynamic levitation with laser heating to investigatethe structure of high-temperature oxide melts and tofabricate novel glassy materials by container-less processing;the use of high-pressure methods in the gigapascal regimeto investigate the mechanisms of network collapse for glassynetwork structures; and the simultaneous application of high pressuresand high-temperatures to explore the structure ofdisordered materials. Finally, we consider the use of otherquantum-beam diffraction-based techniques for probing theorder hidden in the correlation functions that describe thestructure of disordered matter

High-pressure neutron diffraction apparatus for investigating the structure of liquids under hydrothermal conditions

A high-pressure setup is described for making neutron diffraction experiments on liquids under hydrothermal conditions. Designs are given for a modied Bridgman unsupported area seal, a fluid separator that keeps apart the liquid sample and pressurising fluid, and a pressure-cell made from the null-scattering alloy Ti0:676Zr0:324.Special attention is paid to the choice of construction materials used to avoid corrosion by the liquid sample under load at elevated temperatures. The apparatus is used to investigate the structure of heavy water at pressures up to 2 kbar and temperatures up to 250 degC