596 research outputs found
[Review of] William A. Doublass and Richard W. Etulain, eds., Basque Americans: A Guide to Information Sources
This is a selected and annotated bibliography on the European and American Basques, the immigrants and their descendents known as the Amerikanauk. It is useful for both lay people and serious researchers and, short as it may seem, treats a wide variety of subjects concerning one of the least known minority ethnic groups that are an integral part of this multicultural country
Can Conformal Weyl Gravity be Considered a Viable Cosmological Theory?
We present exact analytical solutions to the Conformal Weyl Gravity
cosmological equations that are valid for both the matter and radiation
dominated eras. The Primordial Nucleosynthesis process is also exhaustively
studied. The main conclusion of our work is that cosmological models derived
from this theory are not likely to reproduce the observational properties of
our Universe. They fail to fulfill simultaneously the observational constraints
on present cosmological parameters and on primordial light element abundances.Comment: 7 pages, (1 Figure included), uuencode compressed Postscript. (To be
published in ApJ, June 1994.). FTUAM-93-2
Hydrodynamical simulations of galaxy properties: Environmental effects
Using N-body+hydro simulations we study relations between the local
environments of galaxies on 0.5 Mpc scale and properties of the luminous
components of galaxies. Our numerical simulations include effects of star
formation and supernova feedback in different cosmological scenarios: the
standard Cold Dark Matter model, the Broken Scale Invariance model (BSI), and a
model with cosmological constant (LCDM).
In this paper, we concentrate on the effects of environment on colors and
morphologies of galaxies, on the star formation rate and on the relation
between the total luminosity of a galaxy and its circular velocity. We
demonstrate a statistically significant theoretical relationship between
morphology and environment. In particular, there is a strong tendency for
high-mass galaxies and for elliptical galaxies to form in denser environments,
in agreement with observations. We find that in models with denser environments
(CDM scenario) ~ 13 % of the galactic halos can be identified as field
ellipticals, according to their colors. In simulations with less clustering
(BSI and LCDM), the fraction of ellipticals is considerably lower (~ 2-3 %).
The strong sensitivity of morphological type to environment is rather
remarkable because our results are applicable to ``field'' galaxies and small
groups. If all galaxies in our simulations are included, we find a
statistically significant dependence of the galaxy luminosity - circular
velocity relation on dark matter overdensity within spheres of radius 0.5 Mpc,
for the CDM simulations. But if we remove ``elliptical'' galaxies from our
analysis to mimic the Tully-Fisher relation for spirals, then no dependence is
found in any model.Comment: 44 pages, 21 figures (17 included). Submitted to New Astronomy. GIFF
color plots and the complete paper in Postscript (including color figures)
can be found at http://astrosg.ft.uam.es/~gustavo/newas
[Review of] Judy Nolte Lensink, ed. Old Southwest! New Southwest: Essays on a Region and Its Literature
Here are sixteen essays by various genres of thinkers, among which we find poets, fiction writers, scientists, historians, academic and lay scholars, librarians and artists who presented papers in 1985 at a conference bearing the book\u27s title. N. Scott Momaday, Frank Waters, R. Hinojosa Smith, Janice Monk and Vera Norwood, Rudolfo A. Anaya, and John Nichols are among the contributors. Their papers are the text of this work on the cultures of the American Southwest. Old Southwest indeed becomes an American culture reader, like a treatise on its epistemology and the forms of literature past and present of the region most of us know as the Southwest. They may give significant scientific, poetic, critical, even lyrical expressions such as Momaday\u27s or the refreshing-refreshingly revealing statement of John Nichols ... a cultural worker with a voice
[Review of] Marcienne Rocard, Les Fils du Soleil: La Minorite; Mexicaine a Travers la Litterature des Etats Unis
The first major work of its kind published in France by an Americanist, Les Fils du Soleil (The Children of the Sun: The Mexican Minority as Seen Through the Literature of the United States) deserves recognition as a historical landmark and French contribution to the study of the Chicano. Its thorough treatment of the subject surpasses in thematic outreach all previously published works
Integrating wildlife conservation into ecosystem service payments and carbon offsets: A case study from Costa Rica
Wildlife conservation is challenged by the expensive and cost prohibitive strategy of directly purchasing land to protect habitat at the landscape scale. An alternative mechanism used to protect habitat includes payments for ecosystemâservices (PES), where farmers and landowners are paid to manage their lands for a particular ecological service. Some of these easements are used to conserve a diversity of resources (i.e., water, soil, nutrient cycling, and biodiversity); however, the largest PES easement programs focus on carbon sequestration and are sold on international carbon markets as offsets. Here, we demonstrate that successfully protecting vulnerable habitat for wildlife can be achieved through partnerships with programs that trade in carbon offsets by focusing landowner recruitment activities in areas with ecologically valuable habitat. This collaborative strategy represents a cost effective and efficient model to protect wildlife at landscape scales. As proof of concept, in 2015 we successfully protected and restored habitats used by goldenâwinged warblers, a species being considered by the United States Fish and Wildlife Service for protection under the Endangered Species Act, by partnering with organizations responsible for managing carbon offsets in Costa Rica. Through these partnerships, we successfully protected 790âha of valuable habitat, within a single year, by recruiting farmers and landowners into an easement program in the heart of the warbler\u27s winter range. We present our efforts as a model for similar collaborative partnerships in the tropics and beyond
Local and global gravity
Our long experience with Newtonian potentials has inured us to the view that
gravity only produces local effects. In this paper we challenge this quite
deeply ingrained notion and explicitly identify some intrinsically global
gravitational effects. In particular we show that the global cosmological
Hubble flow can actually modify the motions of stars and gas within individual
galaxies, and even do so in a way which can apparently eliminate the need for
galactic dark matter. Also we show that a classical light wave acquires an
observable, global, path dependent phase in traversing a gravitational field.
Both of these effects serve to underscore the intrinsic difference between
non-relativistic and relativistic gravity.Comment: LaTeX, 20 pages plus three figures in two postscript files. To appear
in a special issue of Foundations of Physics honoring Professor Lawrence
Horwitz on the occasion of his 65th birthday; A. van der Merwe and S. Raby,
Editors, Plenum Publishing Company, N.Y., 199
TipTrap: A Co-located Direct Manipulation Technique for Acoustically Levitated Content
Acoustic levitation has emerged as a promising approach for mid-air displays, by using multiple levitated particles as 3D voxels, cloth and thread props, or high-speed tracer particles, under the promise of creating 3D displays that users can see, hear and feel with their bare eyes, ears and hands. However, interaction with this mid-air content always occurred at a distance, since external objects in the display volume (e.g. user's hands) can disturb the acoustic fields and make the particles fall. This paper proposes TipTrap, a co-located direct manipulation technique for acoustically levitated particles. TipTrap leverages the reflection of ultrasound on the users' skin and employs a closed-loop system to create functional acoustic traps 2.1 mm below the fingertips, and addresses its 3 basic stages: selection, manipulation and deselection. We use Finite-Differences Time Domain (FDTD) simulations to explain the principles enabling TipTrap, and explore how finger reflections and user strategies influence the quality of the traps (e.g. approaching direction, orientation and tracking errors), and use these results to design our technique. We then implement the technique, characterizing its performance with a robotic hand setup and finish with an exploration of the ability of TipTrap to manipulate different types of levitated content
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