5,238 research outputs found
Functional Communication in Chronic Aphasia and Executive Function: The Effect of Treating Cognitive Flexibility
To examine the effect of flexibility skills training on success in conversation, a single-subjects design with repeated measures across subjects was implemented. The findings support the predictions that, for individuals with chronic aphasia, the use of exercises to enhance cognitive flexibility would (1) improve objective measures of problem solving ability and (2) lead to more functional communication. Following intervention for cognitive flexibility, subjects' spontaneous attempts to repair communication breakdowns increased by 40 to 100% in two distinct communication tasks for 75% of participants. Although severity of aphasia did not change, objective change in cognitive flexibility skill following intervention was evidenced
Caracteristicas biologicas y diagnostico inmunologico de un virus de poliedrosis nuclear de Spodoptera eridania (Stoll)(Lepidoptera : Noctuidae)
Group actions on central simple algebras: a geometric approach
We study actions of linear algebraic groups on central simple algebras using
algebro-geometric techniques. Suppose an algebraic group G acts on a central
simple algebra A of degree n. We are interested in questions of the following
type: (a) Do the G-fixed elements form a central simple subalgebra of A of
degree n? (b) Does A have a G-invariant maximal subfield? (c) Does A have a
splitting field with a G-action, extending the G-action on the center of A?
Somewhat surprisingly, we find that under mild assumptions on A and the
actions, one can answer these questions by using techniques from birational
invariant theory (i.e., the study of group actions on algebraic varieties, up
to equivariant birational isomorphisms). In fact, group actions on central
simple algebras turn out to be related to some of the central problems in
birational invariant theory, such as the existence of sections, stabilizers in
general position, affine models, etc. In this paper we explain these
connections and explore them to give partial answers to questions (a)-(c).Comment: 33 pages. Final version, to appear in Journal of Algebra. Includes a
short new section on Brauer-Severi varietie
Variable stars in the field of the Galactic bulge globular cluster NGC 6522
We present a comprehensive analysis of the variable stars projected on the
field of the Galactic bulge globular cluster NGC 6522, offering valuable
insights into their characteristics. Using proper motions from Gaia DR3, we aim
to distinguish between field stars and true cluster members. For an accurate
color-magnitude diagram of the member stars, we produced a differential
reddening map. We detect and discuss the peculiarities of variable stars of the
types RR Lyrae, type II Cepheids, Long Period Variables (LPV) and eclipsing
binaries, whose light curves are available through the OGLE III and IV
databases. Notably, we explore the variable V24, which shows a prominent phase
modulation resulting from period changes in a time scale of ~1100 days. The
variable stars among the cluster members serve as indicators of the cluster
metallicity and distance; these determinations are based on their light curves.
With the Fourier light curve decomposition of three RRc stars, we have derived
the following cluster parameters: the metallicity in the spectroscopic scale
[Fe/H]=--1.16 0.09; and the mean distance
kpc.Comment: 15 pages, 10 Figures, 3 table
The morphological discrimination of microfilariae of Onchocerca volvulus from Mansonella ozzardi.
There is no published account which allows the morphological discrimination of microfilariae of Onchocerca volvulus and M. ozzardi from each other. However, they occur together in parts of Brazil and Venezuela, and presumably there is always the possibility that migration could establish new sympatric populations in the future. The objective of this study was to evaluate simple morphological characters that might be used for species-diagnosis of microfilariae. The conclusions were that the location of microfilariae in the blood or skin, the body size and the nucleation of the nerve ring are expected to be useful first indications of species identity, but cannot be used for confident diagnosis. The structure of the cephalic armature (stained with alcian blue) seems to be species specific, but is of limited application because it is often difficult to see. However, the pattern of nucleation of the tail (as expressed by the ratio of the length of the terminal nucleus compared with the length of the tail space) is distinctive and is expected to be diagnostic
Riddled-like Basin in Two-Dimensional Map for Bouncing Motion of an Inelastic Particle on a Vibrating Board
Motivated by bouncing motion of an inelastic particle on a vibrating board, a
simple two-dimensional map is constructed and its behavior is studied
numerically. In addition to the typical route to chaos through a periodic
doubling bifurcation, we found peculiar behavior in the parameter region where
two stable periodic attractors coexist. A typical orbit in the region goes
through chaotic motion for an extended transient period before it converges
into one of the two periodic attractors. The basin structure in this parameter
region is almost riddling and the fractal dimension of the basin boundary is
close to two, {\it i.e.}, the dimension of the phase space.Comment: 4 pages, 5 figures. to be published in J. Phys. Soc. Jpn. (2002
Classification of Reductive Monoid Spaces Over an Arbitrary Field
In this semi-expository paper we review the notion of a spherical space. In
particular we present some recent results of Wedhorn on the classification of
spherical spaces over arbitrary fields. As an application, we introduce and
classify reductive monoid spaces over an arbitrary field.Comment: This is the final versio
Discovery of the progenitor of the type Ia supernova 2007on
Type Ia supernovae are exploding stars that are used to measure the
accelerated expansion of the Universe and are responsible for most of the iron
ever produced. Although there is general agreement that the exploding star is a
white dwarf in a binary system, the exact configuration and trigger of the
explosion is unclear, which could hamper their use for precision cosmology. Two
families of progenitor models have been proposed. In the first, a white dwarf
accretes material from a companion until it exceeds the Chandrasekhar mass,
collapses and explodes. Alternatively, two white dwarfs merge, again causing
catastrophic collapse and an explosion. It has hitherto been impossible to
determine if either model is correct. Here we report the discovery of an object
in pre-supernova archival X-ray images at the position of the recent type Ia
supernova (2007on) in the elliptical galaxy NGC 1404. Deep optical images (also
archival) show no sign of this object. From this we conclude that the X-ray
source is the progenitor of the supernova, which favours the accretion model
for this supernova, although the host galaxy is older (6-9 Gyr) than the age at
which the explosions are predicted in the accreting models.Comment: Published in Nature See also the two follow-up papers: Roelofs,
Bassa, Voss, Nelemans Nelemans, Voss, Roelofs, Bassa both on astro-ph
02/15/0
MoDOT Pavement Preservation Research Program
The following report documents a research project on pavement preservation performed by the Missouri University of Science and Technology (Missouri S&T) and the University of Missouri-Columbia (UMC) on behalf of the Missouri Department of Transportation (MoDOT). the report consists of a Summary Report followed by six detailed technical reports. to achieve the goal of reducing maintenance costs and improving minor road ratings, MoDOT has embarked upon a plan of formalizing its maintenance/preservation planning. to assist in developing the plan, MoDOT contracted with the Missouri S&T and UMC to conduct a research project, entitled MoDOT Pavement Preservation Research Program . the product of this research would become a part of MoDOT’s overall Pavement Management System. the overall objective of the research was to provide a process that would allow MoDOT to do more selective planning, better engineering and more effective maintenance to minimize costs while maintaining adequate safety and performance of Missouri’s pavements. Six Guidance Documents were to ultimately be created which would act as guidelines for MoDOT’s Pavement Specialists and Engineers. the work was divided into six Tasks, each with its own research team
The Kerr-Schild double copy in curved spacetime
We thank Tim Adamo, Ricardo Monteiro and Donal O’Connell for discussions and / or
comments on the manuscript. CDW and NBA are supported by the U.K. Science and
Technology Facilities Council (STFC). AL is funded by a Conacyt studentship, and thanks
Queen Mary University of London for hospitalit
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