How non-linear scaling relations unify dwarf and giant elliptical galaxies

Dwarf elliptical galaxies are frequently excluded from bright galaxy samples because they do not follow the same linear relations in diagrams involving effective half light radii R_e or mean effective surface brightnesses _e. However, using two linear relations which unite dwarf and bright elliptical galaxies we explain how these lead to curved relations when one introduces either the half light radius or the associated surface brightness. In particular, the curved _e - R_e relation is derived here. This and other previously misunderstood curved relations, once heralded as evidence for a discontinuity between faint and bright elliptical galaxies at M_B ~ -18 mag, actually support the unification of such galaxies as a single population whose structure (i.e. stellar concentration) varies continuously with stellar luminosity and mass.Comment: 4 pages including 2 figures, to appear in "A Universe of dwarf galaxies", Conf. Proc. (Lyon, June 14-18, 2010

Microstructural controls on the geomechanics of coarse grained soft rocks; Waitemata Group, Auckland

The geomechanical behaviour of a variety of soft rocks from the Waitemata Group, Auckland, is characterised, and the influence of microstructure in determining the geomechanics examined. Field geotechnical measurements of joint spacing and Schmidt Hammer rebound are related to geomechanical properties to determine controls on joint development and applicability of field index tests for soft materials. Samples studied are dominantly sandstones, with one conglomerate; all of which have a significant component of swelling clay minerals. Low bulk densities, high porosities and large void ratios are characteristic of the samples. They vary from extremely weak, very low durability rocks to moderately: strong and durable materials. Extremely weak sandstones are highly deformable and undergo plastic deformation when loaded in compression. The stronger samples undergo strain softening and respond elastically to applied stresses prior to brittle failure. High softening factors indicate that compressive and tensile strengths are greatly reduced upon saturation. All the study rocks have high proportions of sand and silt size material (≤ 95 %), and up to 10 % of < 2 μ m proportions; significant gravel size material only occurs in the conglomerate. Volcanic and detrital rock fragments are the dominant constituents in all samples, with abundant quartz, minor calcic plagioclase, and a variety of accessory minerals. The dominant clay is smectite with lesser amounts of illite, kaolinite, and mixed-layer clays. Individual sand and silt grains are dominantly subrounded to subangular quartz, regular bricks of feldspar, and rods of rutile, and are often clay coated. Microaggregates and grains are combined into aggregates and assemblages, and in some cases macroassemblages, to form granular arrangements, which produce a network of interconnecting pores. The fabric of the rocks is characterised by discontinuous matrices. Fabric types range from skeletal to turbostratic, and arrangements range from tightly interlocking grains to loose granular structures. Clay micro aggregates are either flocculated or form welded FF honeycomb arrangements. Strength and durability are not influenced by quantity, size, or type of clasts or minerals present; rather, it is the arrangement of individual components (and associated pore spaces) in the rock fabric which directly determines the geomechanical behaviour. Strong, durable samples have an abundance of clean grain to grain contacts, and few large clay aggregates. Clay microaggregates are arranged in welded FF arrangements, and pore space is restricted to micropores which resist water infiltration. Progressively weaker rocks are characterised by an increase in clay coated grains, clay aggregates, and clay connectors (which form weak links for stress transmission), and interconnecting pores at all levels in the fabric. In the weakest rock macroassemblages of clay coated grains, and open flocculated smectitic aggregates connected by point contacts, produce a network of macropores, allowing easy access of water which flocculates clays into weaker states by reducing bonding and cohesion. Schmidt rebound values in the field do not provide a useful indication of either compressive or tensile strength of these rocks. The rebound values do, however, correlate well with laboratory determined dynamic elasticity values, suggesting that the instrument should be used in the field to predict rock elasticity and not strength. Joint spacing within the rock units is related to elasticity with units capable of storing stress through plastic deformation having reasonably wide, uniformly spaced joints. Units which release stress through brittle fracture have closely spaced, and more complex joint systems

Grassroots Narratives in Oaxaca and Ciudad Juarez: Images in Blocks, Stencils and Photographs, Herzstein Latin American Reading Room Gallery, September 15 - October 20, 2010

Exhibit Poster - Grassroots Narratives in Oaxaca and Ciudad Juarez: Images in Blocks, Stencils and Photographs, curated by Mikey G. De la Rosa, Herzstein Latin American Reading Room Gallery, September 15 - October 20, 2010https://digitalrepository.unm.edu/ias_exhibits/1007/thumbnail.jp

Removal of AMPA receptors (AMPARs) from synapses is preceded by transient endocytosis of extrasynaptic AMPARs

AMPA receptors (AMPARs) are dynamically regulated at synapses, but the time course and location of their exocytosis and endocytosis are not known. Therefore, we have used ecliptic pHluorin-tagged glutamate receptor 2 to visualize changes in AMPAR surface expression in real time. We show that synaptic and extrasynaptic AMPARs respond very differently to NMDA receptor activation; there is a rapid internalization of extrasynaptic AMPARs that precedes the delayed removal of synaptic AMPARs

Negative index fishnet with nanopillars formed by direct nano-imprint lithography

In this paper we demonstrate the ability to fabricate fishnets by nanoimprinting directly into a pre-deposited three layer metal–dielectric–metal stack, enabling us to pattern large areas in two minutes. We have designed and fabricated two different fishnet structures of varying dimensions using this method and measured their resonant wavelengths in the near-infrared at 1.45 μm and 1.88 μm. An important by-product of directly imprinting into the metal–dielectric stack, without separation from the substrate, is the formation of rectangular nanopillars that sit within the rectangular apertures between the fishnet slabs. Simulations complement our measurements and suggest a negative refractive index real part with a magnitude of 1.6. Further simulations suggest that if the fishnet were to be detached from the supporting substrate a refractive index real part of 5 and FOM of 2.74 could be obtained

Beyond the paint and ink: ASAR Oaxaca resistance and getting up Arte Pal Pueblo

This thesis aims to address the ways in Oaxacan street artists frame alternative realities within art and interviews about their art. Asamblea de Artistas Revolucionarios de Oaxaca or ASARO, is a revolutionary artist collective that currently works in Oaxaca Mexico. They place their art in publically accessible areas and comment on local, national and international social issues. Through ethnographic interviews and participant observation with members of ASARO along with critical discourse analysis of their images, I explore the ways getting up is accomplished. The combination of ethnographic field work paired with a critical approach deepens an understanding of what influences modern communication production through art in a marginalized area of Mexicos periphery. In this thesis ideas of art as transformative, legible, accessible are explored. Also Mexican local and global issues such as immigration, iconography, collective action, women\u27s and human rights, exploitation of workers and natural resources are also analyzed within images created by ASARO

Modeling of the hydrogen Lyman lines in solar flares

The hydrogen Lyman lines (91.2 nm &lt; λ &lt; 121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and they are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme Ultraviolet Variability instrument onboard the Solar Dynamics Observatory exhibit Doppler motions equivalent to speeds on the order of 30 km s−1. However, contrary to expectations, both redshifts and blueshifts were present and no dominant flow direction was observed. To understand the formation of the Lyman lines, particularly their Doppler motions, we have used the radiative hydrodynamic code, RADYN, along with the radiative transfer code, RH, to simulate the evolution of the flaring chromosphere and the response of the Lyman lines during solar flares. We find that upflows in the simulated atmospheres lead to blueshifts in the line cores, which exhibit central reversals. We then model the effects of the instrument on the profiles, using the Extreme Ultraviolet Variability Experiment (EVE) instrument's properties. What may be interpreted as downflows (redshifted emission) in the lines, after they have been convolved with the instrumental line profile, may not necessarily correspond to actual downflows. Dynamic features in the atmosphere can introduce complex features in the line profiles that will not be detected by instruments with the spectral resolution of EVE, but which leave more of a signature at the resolution of the Spectral Investigation of the Coronal Environment instrument onboard the Solar Orbiter