1,347 research outputs found
Father Come Home
https://digitalcommons.library.umaine.edu/mmb-me/1747/thumbnail.jp
A History of Flips in Combinatorial Triangulations
Given two combinatorial triangulations, how many edge flips are necessary and
sufficient to convert one into the other? This question has occupied
researchers for over 75 years. We provide a comprehensive survey, including
full proofs, of the various attempts to answer it.Comment: Added a paragraph referencing earlier work in the vertex-labelled
setting that has implications for the unlabeled settin
Controlling the Sign of Magnetoconductance in Andreev Quantum Dots
We construct a theory of coherent transport through a ballistic quantum dot
coupled to a superconductor. We show that the leading-order quantum correction
to the two-terminal conductance of these Andreev quantum dots may change sign
depending on (i) the number of channels carried by the normal leads or (ii) the
magnetic flux threading the dot. In contrast, spin-orbit interaction may affect
the magnitude of the correction, but not always its sign. Experimental
signatures of the effect include a non-monotonic magnetoconductance curve and a
transition from an insulator-like to a metal-like temperature dependence of the
conductance. Our results are applicable to ballistic or disordered dots.Comment: Final version (4pages 3figs)- improved presentation and fig 3, and
updated reference
Being Good for Goodness Sake: The Influence of Family Involvement on Motivations to Engage in Small Business Social Responsibility
Small family and nonfamily firms are acknowledged to serve as important facilitators of social responsibility within their communities; however, both have received relatively little attention in the literature for these efforts or their motivation for undertaking them. Grounded in Enlightened Self-Interest (ESI) and intentions, we explore motivations for participation in socially responsible behaviors and the moderating effect of family involvement. We develop measures for small business social responsibility (SBSR), ESI, and SBSR intentions. Our analyses indicate positive direct effects exist for both SBSR intentions and ESI on engagement in SBSR. We find that family involvement strengthens the relationship between ESI and participation in civic SBSR, thus suggesting that family firms may be partially motivated to "do good" in visible forms of SBSR to protect their own interests
Being Good for Goodness Sake: The Influence of Family Involvement on Motivations to Engage in Small Business Social Responsibility
Small family and nonfamily firms are acknowledged to serve as important facilitators of social responsibility within their communities; however, both have received relatively little attention in the literature for these efforts or their motivation for undertaking them. Grounded in Enlightened Self-Interest (ESI) and intentions, we explore motivations for participation in socially responsible behaviors and the moderating effect of family involvement. We develop measures for small business social responsibility (SBSR), ESI, and SBSR intentions. Our analyses indicate positive direct effects exist for both SBSR intentions and ESI on engagement in SBSR. We find that family involvement strengthens the relationship between ESI and participation in civic SBSR, thus suggesting that family firms may be partially motivated to "do good" in visible forms of SBSR to protect their own interests
3-D Models of Embedded High-Mass Stars: Effects of a Clumpy Circumstellar Medium
We use 3-D radiative transfer models to show the effects of clumpy
circumstellar material on the observed infrared colors of high mass stars
embedded in molecular clouds. We highlight differences between 3-D clumpy and
1-D smooth models which can affect the interpretation of data. We discuss
several important properties of the emergent spectral energy distribution
(SED): More near-infrared light (scattered and direct from the central source)
can escape than in smooth 1-D models. The near- and mid-infrared SED of the
same object can vary significantly with viewing angle, depending on the clump
geometry along the sightline. Even the wavelength-integrated flux can vary with
angle by more than a factor of two. Objects with the same average circumstellar
dust distribution can have very different near-and mid-IR SEDs depending on the
clump geometry and the proximity of the most massive clump to the central
source.
Although clumpiness can cause similar objects to have very different SEDs,
there are some observable trends. Near- and mid-infrared colors are sensitive
to the weighted average distance of clumps from the central source and to the
magnitude of clumpy density variations (smooth-to-clumpy ratio). Far-infrared
emission remains a robust measure of the total dust mass. We present simulated
SEDs, colors, and images for 2MASS and Spitzer filters. We compare to
observations of some UCHII regions and find that 3-D clumpy models fit better
than smooth models. In particular, clumpy models with fractal dimensions in the
range 2.3-2.8, smooth to clumpy ratios of <50%, and density distributions with
shallow average radial density profiles fit the SEDs best.Comment: accepted to ApJ; version with full-res figures:
http://www.astro.virginia.edu/~ri3e/clumpy3d.pd
Scientific investigations in the Gulf of Mexico and Caribbean Sea during the 1974-1975 Calypso cruise, parts 1 and 2
The distribution and concentrations of the standing crop of phytoplankton and nutrient salts in the Gulf of Mexico and the Caribbean Sea were investigated to provide ground truth for correlating temperature and chlorophyll-a measurements with observations from NASA U-2 aircraft equipped with specially designed sensors for measuring ocean color phenomena. The physical, chemical, and biological data obtained is summarized. Sampling procedures and methods used for determining plant pigments, species composition of phytoplankton, nutrient salt analysis, and the euphotic zones are described
2-D Radiative Transfer in Protostellar Envelopes: I. Effects of Geometry on Class I Sources
We present 2-D radiation transfer models of Class I Protostars and show the
effect of including more realistic geometries on the resulting spectral energy
distributions and images. We begin with a rotationally flattened infalling
envelope as our comparison model, and add a flared disk and bipolar cavity. The
disk affects the spectral energy distribution most strongly at edge-on
inclinations, causing a broad dip at about 10 um (independent of the silicate
feature) due to high extinction and low scattering albedo in this wavelength
region. The bipolar cavities allow more direct stellar+disk radiation to emerge
into polar directions, and more scattering radiation to emerge into all
directions. The wavelength-integrated flux, often interpreted as luminosity,
varies with viewing angle, with pole-on viewing angles seeing 2-4 times as much
flux as edge-on, depending on geometry. Thus, observational estimates of
luminosity should take into account the inclination of a source. The envelopes
with cavities are significantly bluer in near-IR and mid-IR color-color plots
than those without cavities. Using 1-D models to interpret Class I sources with
bipolar cavities would lead to an underestimate of envelope mass and an
overestimate of the implied evolutionary state. We compute images at near-,
mid-, and far-IR wavelengths. We find that the mid-IR colors and images are
sensitive to scattering albedo, and that the flared disk shadows the midplane
on large size scales at all wavelengths plotted. Finally, our models produce
polarization spectra which can be used to diagnose dust properties, such as
albedo variations due to grain growth. Our results of polarization across the
3.1 um ice feature agree well with observations for ice mantles covering 5% of
the radius of the grains.Comment: Accepted for publication in ApJ, 37 pages, 13 figures (several
figures reduced in quality; find original version at
http://gemelli.colorado.edu/~bwhitney/preprints.html
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