1,645 research outputs found
How to say greedy in fork algebras
Because of their expressive power, binary relations are widely used in program specification and development within formal calculi. The existence of a finite equational axiomatization for algebras of binary relations with a fork operation guarantees that the heuristic power coming from binary relations is captured inside an abstract equational calculus.
In this paper we show how to express the greedy program design strategy into the first order theory of fork algebras.Eje: TeoríaRed de Universidades con Carreras en Informática (RedUNCI
How to say greedy in fork algebras
Because of their expressive power, binary relations are widely used in program specification and development within formal calculi. The existence of a finite equational axiomatization for algebras of binary relations with a fork operation guarantees that the heuristic power coming from binary relations is captured inside an abstract equational calculus.
In this paper we show how to express the greedy program design strategy into the first order theory of fork algebras.Eje: TeoríaRed de Universidades con Carreras en Informática (RedUNCI
The acyclic group dichotomy
Two extremal classes of acyclic groups are discussed. For an arbitrary group
G, there is always a homomorphism from an acyclic group of cohomological
dimension 2 onto the maximum perfect subgroup of G, and there is always an
embedding of G in a binate (hence acyclic) group. In the other direction, there
are no nontrivial homomorphisms from binate groups to groups of finite
cohomological dimension. Binate groups are shown to be of significance in
relation to a number of important K-theoretic isomorphism conjectures.Comment: To appea
The isocohomological property, higher Dehn functions, and relatively hyperbolic groups
The property that the polynomial cohomology with coefficients of a finitely
generated discrete group is canonically isomorphic to the group cohomology is
called the (weak) isocohomological property for the group. In the case when a
group is of type , i.e. that has a classifying space with the
homotopy type of a cellular complex with finitely many cells in each dimension,
we show that the isocohomological property is equivalent to the universal cover
of the classifying space satisfying polynomially bounded higher Dehn functions.
If a group is hyperbolic relative to a collection of subgroups, each of which
is polynomially combable (respectively and isocohomological), then
we show that the group itself has these respective properties too. Combining
with the results of Connes-Moscovici and Dru{\c{t}}u-Sapir we conclude that a
group satisfies the Novikov conjecture if it is relatively hyperbolic to
subgroups that are of property RD, of type and isocohomological.Comment: 35 pages, no figure
D-Branes on Noncompact Calabi-Yau Manifolds: K-Theory and Monodromy
We study D-branes on smooth noncompact toric Calabi-Yau manifolds that are
resolutions of abelian orbifold singularities. Such a space has a distinguished
basis {S_i} for the compactly supported K-theory. Using local mirror symmetry
we demonstrate that the S_i have simple transformation properties under
monodromy; in particular, they are the objects that generate monodromy around
the principal component of the discriminant locus. One of our examples, the
toric resolution of C^3/(Z_2 x Z_2), is a three parameter model for which we
are able to give an explicit solution of the GKZ system.Comment: 40 pp, substantial revision
Virtual image out-the-window display system study, volume I
Virtual image out-the-window display system and current approaches to visual simulatio
Salivary PYY: A Putative Bypass to Satiety
Peptide YY3-36 is a satiation hormone released postprandially into the bloodstream from L-endocrine cells in the gut epithelia. In the current report, we demonstrate PYY3-36 is also present in murine as well as in human saliva. In mice, salivary PYY3-36 derives from plasma and is also synthesized in the taste cells in taste buds of the tongue. Moreover, the cognate receptor Y2R is abundantly expressed in the basal layer of the progenitor cells of the tongue epithelia and von Ebner's gland. The acute augmentation of salivary PYY3-36 induced stronger satiation as demonstrated in feeding behavioral studies. The effect is mediated through the activation of the specific Y2 receptor expressed in the lingual epithelial cells. In a long-term study involving diet-induced obese (DIO) mice, a sustained increase in PYY3-36 was achieved using viral vector-mediated gene delivery targeting salivary glands. The chronic increase in salivary PYY3-36 resulted in a significant long-term reduction in food intake (FI) and body weight (BW). Thus this study provides evidence for new functions of the previously characterized gut peptide PYY3-36 suggesting a potential simple and efficient alternative therapeutic approach for the treatment of obesity
Mid-Infrared Properties of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. Emission-Line Diagnostics
We compare mid-infrared emission-line properties, from high-resolution
Spitzer spectra of a hard X-ray (14 -- 195 keV) selected sample of nearby (z <
0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The
luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89
micron, [Ne II] 12.81 micron, [Ne III] 15.56 micron and [Ne V] 14.32/24.32
micron, and hard X-ray continuum show no differences between Seyfert 1 and
Seyfert 2 populations, however six newly discovered BAT AGNs are under-luminous
in [O IV], most likely the result of dust extinction in the host galaxy. The
overall tightness of the mid-infrared correlations and BAT fluxes and
luminosities suggests that the emission lines primarily arise in gas ionized by
the AGN. We also compare the mid-infrared emission-lines in the BAT AGNs with
those from published studies of ULIRGs, PG QSOs, star-forming galaxies and
LINERs. We find that the BAT AGN sample fall into a distinctive region when
comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] ratios. These line
ratios are lower in sources that have been previously classified in the
mid-infrared/optical as AGN than those found for the BAT AGN, suggesting that,
in our X-ray selected sample, the AGN represents the main contribution to the
observed line emission. These ratios represent a new emission line diagnostic
for distinguishing between AGN and star forming galaxies.Comment: 54 pages, 9 Figures. Accepted for publication in The Astrophysical
Journal
A thermophysical study of the melting process in alkyl chain metal n-alkanoates: The thallium (I) series
The peculiar thermal behavior of the thallium(I) n-alkanoates series (consisting in several transitions between polymorphic and mesomorphic phases) in comparison with other metallic n-alkanoates series is stated. The allowance of highly accurate adiabatic heat capacity data permits a study of the CH2CH2 contributions to the lattice heat capacity curve at low temperature. Moreover, in this series an anomalous gradual enhancement of the lattice heat capacity has been interpreted from vibrational spectroscopy results as a noncooperative effect due to the internal hindered rotation of the alkyl chain (formation of gauche defects, even in the solid state). The thermodynamics of the “stepwise melting process” from the totally ordered solid at low temperature to the isotropic liquid is based on a revised lattice heat-capacity curve. This was used to evaluate the energy and entropy not only of the clear first order transitions present in the series but also of the described noncooperative effect. The CH2CH2 enthalpy and entropy contribution for this series is estimated and a comparison with the published values for other series is carried out. Moreover, the texture of the mesophases is revealed by polarized light microscopy. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69602/2/JCPSA6-111-8-3590-1.pd
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