376 research outputs found
Hexagonal Tilings: Tutte Uniqueness
We develop the necessary machinery in order to prove that hexagonal tilings
are uniquely determined by their Tutte polynomial, showing as an example how to
apply this technique to the toroidal hexagonal tiling.Comment: 12 figure
Hexagonal Tilings and Locally C6 Graphs
We give a complete classification of hexagonal tilings and locally C6 graphs,
by showing that each of them has a natural embedding in the torus or in the
Klein bottle. We also show that locally grid graphs are minors of hexagonal
tilings (and by duality of locally C6 graphs) by contraction of a perfect
matching and deletion of the resulting parallel edges, in a form suitable for
the study of their Tutte uniqueness.Comment: 14 figure
Extended reagions of radio emission not associated with the AGN phenomenon as sources of acceleration of cosmic rays: The case of cD galaxies
Diffuse, non-thermal extended emission not associated with the AGN
phenomenon, found in many clusters of galaxies hosted by an AGN, are related to
the acceleration of cosmic rays. In the current work we present preliminary
evidence of absence of such formations in clusters of galaxies hosted by
optically identified cD galaxies. Our subsample consists of three powerful low
redshift radiogalaxies, centered in poor clusters of galaxies. We have searched
for radio relics and (mini)halos which could be forming as a result of the
confinement of cosmic rays by bubbles creayed by the AGN. We report on the work
in progress.Comment: 4 pages, Conference HEPRO II
Singular perturbations of zⁿ with a pole on the unit circle
We consider the family of complex maps given by fλ,a (z) = z n + λ/(z − a)d where n, d ≥ 1 are integers, and a and λ are complex parameters such that a = 1 and is sufficiently small. We focus on the topological characteristics of the Julia and Fatou sets of fλ,a
Generalized rings around the McMullen domain
We consider the family of rational maps given by F (z) = z + λ/ z where n, d∈ N with 1 / n+ 1 / d 1 is given by τkn,d=dnk-2(n-1)-nk-1+1
La economía colaborativa en el ámbito de la vivienda: cuestiones fiscales pendientes
La economía colaborativa constituye un modelo de consumo que permite, gracias a las tecnologías, acceder a bienes y servicios de forma eficiente y participativa. Es un fenómeno creciente en los últimos años, en especial en el sector del transporte y del alojamiento. Los retos son, sin embargo, muchos. Su complejidad y su trascendencia exigen que los Estados aborden la regulación y la ordenación de todas las prácticas que se desarrollan para que puedan conciliarse los derechos y obligaciones de todos los operadores.En esta comunicación analizaremos los retos fiscales de la economía colaborativa en la vivienda. Para que sea una salida eficaz de la crisis y proporcione ingresos a los Estados (también ingresos fiscales), es necesario el cumplimiento de las obligaciones fiscales por parte de los operadores, de forma socialmente responsable. Igualmente, habrá que plantearse la necesidad de realizar reformas fiscales para facilitar el cumplimiento de dichas obligaciones.------------------------------------------------------------------Sharing economy is a consumption model that allows, thanks to the technologies, to access goods and services in an efficient and participatory way. It is a growing phenomenon in recent years, especially in the transport and accommodation sector. The challenges are, however, many. Their complexity and their importance require that States address the regulation and management of all practices that are developed in order to reconcile the rights and obligations of all operators.In this communication we will analyze the fiscal challenges of the sharing economy in housing. In order to be an effective way out of the crisis and to provide revenue to States (also tax revenues), it is necessary to fulfill the tax obligations on the part of the operators in a socially responsible way. Likewise, it will be necessary to consider the need to carry out fiscal reforms to facilitate the fulfillment of these obligations
Random-walk simulation of cell migration and proliferation
Cell migration and proliferation has been modelled in several works of the literature as a process similar to diffusion. However, diffusion models to simulate the proliferation and migration of cells tend to create a homogeneous distribution in the cell density, but this result is not real. Diffusion is not the mechanism of cell dispersal: cells disperse by crawling or proliferation, or are transported in a moving fluid. The use of stochastic models or other (cellular automata, models particles, etc...) can modify this limitation. Therefore, this paper presents a stochastic model (random-walk) to simulate the proliferation and migration of cells. Both processes are considered as completely stochastic as discrete. The model developed aims to predict the behavior of in vitro cell cultures performed with adult muscle satellite cells. Non homogeneous distribution of cells has been observed inside the culture well. Using previous stochastic model we have been able to predict the non homogeneous cell distribution and accurate quantitative results have been computed. In a future, the model will allow us to incorporate other aspects such as cell differentiation, incorporate several cell populations simultaneously, etc
TEMPORAL AND SPATIAL DISTRIBUTION OF POACEAE POLLEN IN AREAS OF SOUTHERN UNITED KINGDOM, SPAIN AND PORTUGAL
Overall, longer Poaceae pollen seasons coincided with earlier pollen season start dates. Winter rainfall noticeably affects
the intensity of Poaceae pollen seasons in Mediterranean areas, but this was not as important in Worcester. Weekly data
from Worcester followed a similar pattern to that of Badajoz and Évora but at a distance of more than 1500 km and 4-5
weeks later
Globular Clusters in Dense Clusters of Galaxies
Deep imaging data from the Keck II telescope are employed to study the
globular cluster (GC) populations in the cores of six rich Abell clusters. The
sample includes A754, A1644, A2124, A2147, A2151, and A2152, and spans the
redshift range z = 0.035-0.066. The clusters also range in morphology from
spiral-rich, irregular systems to centrally concentrated cD clusters rich in
early-type galaxies. Globular cluster specific frequencies S_N and luminosity
function dispersions are measured for a total of 9 galaxies in six central
fields. The measured values of S_N for the six brightest cluster galaxies
(BCGs) are all higher than typical values for giant ellipticals, in accord with
the known S_N-density correlations. The three non-BCGs analyzed also have
elevated values of S_N, confirming that central location is a primary factor.
The number of GCs per unit mass for these fields are consistent with those
found in an earlier sample, giving further evidence that GC number scales with
mass and that the S_N variations are due to a deficit of halo light, i.e., S_N
reflects mass-to-light ratio.
The discussion builds on an earlier suggestion that the GCs (both metal rich
and metal poor) around the central cluster galaxies were assembled at early
times, and that star formation halted prematurely in the central galaxies at
the epoch of cluster collapse. This is consistent with recent simulations of
BCG/cluster formation. The subsequent addition of luminous material through
cluster dynamical evolution can cause S_N to decrease, and we may be seeing the
first evidence of this. Finally, the GC luminosity function measurements are
used to constrain the relative distances of the three clusters that make up the
Hercules supercluster.Comment: Uses emulateapj.sty (included); 17 pages with 9 included PostScript
figures. Figures 1-6 are separate GIF images (so 15 figures total) available
from http://astro.caltech.edu/~jpb/clusters -- the full PostScript version of
the paper (20 pages; 2.2 Mb compressed) incorporating Figures 1-6 can also be
grabbed from this URL. Accepted for publication in A
Differential protein expression analysis to study the pathogenicity of the protozoa parasite Trichomonas Gallinae
Comunicaciones a congreso
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