Dark Energy Accretion onto black holes in a cosmic scenario

In this paper we study the accretion of dark energy onto a black hole in the cases that dark energy is equipped with a positive cosmological constant and when the space-time is described by a Schwarzschild-de Sitter metric. It is shown that, if confronted with current observational data, the results derived when no cosmological constant is present are once again obtained in both cases.Comment: 7 pages, 3 figure

A dark energy multiverse

We present cosmic solutions corresponding to universes filled with dark and phantom energy, all having a negative cosmological constant. All such solutions contain infinite singularities, successively and equally distributed along time, which can be either big bang/crunchs or big rips singularities. Classicaly these solutions can be regarded as associated with multiverse scenarios, being those corresponding to phantom energy that may describe the current accelerating universe

Classical Euclidean wormhole solutions in Palatini f(R~)f(\tilde{R}) cosmology

We study the classical Euclidean wormholes in the context of extended theories of gravity. With no loss of generality, we use the dynamical equivalence between $f(\tilde{R})$ gravity and scalar-tensor theories to construct a point-like Lagrangian in the flat FRW space time. We first show the dynamical equivalence between Palatini $f(\tilde{R})$ gravity and the Brans-Dicke theory with self-interacting potential, and then show the dynamical equivalence between the Brans-Dicke theory with self-interacting potential and the minimally coupled O'Hanlon theory. We show the existence of new Euclidean wormhole solutions for this O'Hanlon theory and, for an special case, find out the corresponding form of $f(\tilde{R})$ having wormhole solution. For small values of the Ricci scalar, this $f(\tilde{R})$ is in agreement with the wormhole solution obtained for higher order gravity theory $\tilde{R}+\epsilon \tilde{R}^2,\epsilon<0$.Comment: 11 page

Estado del arte de los sistemas de navegación en cirugía hepática

Los avances en instrumentación, tecnologías de localización y en técnicas de procesado de imagen han permitido el desarrollo de la cirugía guiada por imagen (CGI). En concreto, los sistemas de navegación quirúrgicos permiten transferir los estudios preoperatorios, imágenes y decisiones al propio quirófano, sirviendo de apoyo a los cirujanos durante la intervención. Los principales retos de estos sistemas se hallan en su incorporación en cirugías de tejidos blandos, donde la deformación y el movimiento de los órganos complican el desarrollo de estos sistemas. Tal es el caso de las cirugías hepáticas. El presente trabajo recoge un estado del arte de sistemas de navegación centrados en cirugía hepátic

Slit Observations and Empirical Calculations for HII Regions

When analysing HII regions, a possible source of systematic error on empirically derived physical quantities is the limited size of the slit used for the observations. A grid of photoionization models was built through the Aangaba code varying the ionizing radiation spectrum emitted by a stellar cluster, as well as the gas abundance. The calculated line surface brightness was then used to simulate slit observations and to derive empirical parameters using the usual methods described in the literature. Depending on the fraction of the object covered by the slit, the parameters can be different from those obtained from observations of the whole object, an effect that is mainly dependent on the age of the ionizing stellar cluster. The low-ionization forbidden lines are more sensitive to the size of the area covered by the slit than the high-ionization forbidden lines or recombination lines. Regarding the temperature indicator T[OIII], the slit effects are small since this temperature is derived from [OIII] lines. On the other hand, for the abundance indicator R23, which depends also on the [OII] line, the slit effect is slightly higher. Therefore, the systematic error due to slit observations on the O abundance is low, being usually less than 10%, except for HII regions powered by stellar clusters with a relative low number of ionizing photons between 13.6 and 54.4 eV, which create a smaller O++ emitting volume. In this case, the systematic error on the empirical O abundance deduced from slit observations is more than 10% when the covered area is less than 50%.Comment: To be published in MNRAS, accepted in 09/09/2005, 17 pages and 6 figure

Quintessence and the first Doppler peak

By using a tracking quintessence model we obtain that the position of the first Doppler peak in the spectrum of CMB anisotropies only depends on the topology of the universe, $\Omega_k$, for any value of the ratio $\Omega_{\Lambda}/\Omega_M$, so that such a dependence is perfectly valid in the range suggested by supernova observations.Comment: 9 pages, LaTe

How can video analysis help laparoscopic surgeons?

Automatic analysis of minimally invasive surgical (MIS) video has the potential to drive new solutions that alleviate existing needs for safer surgeries: reproducible training programs, objective and transparent assessment systems and navigation tools to assist surgeons and improve patient safety. As an unobtrusive, always available source of information in the operating room (OR), this research proposes the use of surgical video for extracting useful information during surgical operations. Methodology proposed includes tools' tracking algorithm and 3D reconstruction of the surgical field. The motivation for these solutions is the augmentation of the laparoscopic view in order to provide orientation aids, optimal surgical path visualization, or preoperative virtual models overla

Electromagnetic waves in a wormhole geometry

We investigate the propagation of electromagnetic waves through a static wormhole. It is shown that the problem can be reduced to a one-dimensional Schr\"odinger-like equation with a barrier-type potential. Using numerical methods, we calculate the transmission coefficient as a function of the energy. We also discuss the polarization of the outgoing radiation due to this gravitational scattering.Comment: LaTex file, 5 pages, 2 figures, one reference added, accepted for publication in PR

The status of chestnut cultivation and utilization in the Canary Islands

Chestnut was introduced to the Canary Islands at the beginning of the 16th century during the time of the Spanish Conquest. It was utilised by the conquerors as a means of claiming property for communal lands. From that time until today, chestnut has been an important crop in the Canary Islands. It is important both as a source of food and timber and has contributed to the subsistence of the population, particularly at times when both resources were scarce. Nowadays it is mainly cultivated on the Islands of Tenerife (around 1300 ha) and La Palma. On other islands, such as Gran Canaria, La Gomera and El Hierro, semi-wild chestnut forests and small plots where farmers collect fruit still exist. Morphological and molecular marker (SSRs) studies have shown a great variability within the local population of chestnut trees in the Canaries. The main use for chestnut is fruit consumption, but it was also utilised in the past as an exchange commodity to obtain fish and other food. The fruit is consumed in many different ways, mainly toasted or roasted, but also cooked in soups, fish or meat dishes and even as an ingredient for the typical Canary Islands’ sweet ‘morcillas’ (a type of sausage). The wood of the tree has been used for furniture, with some shoots being utilised for basket making, and also as cattle food. The trunk of the chestnut has also been used to obtain cork or as a bee hive. Recent efforts to add value to chestnut cultivation in the Canary Islands have included the creation of a Chestnut Farmers Association in Tenerife that commercializes their products under a brand name

Recovering and harmonizing research cruises information

The IEO has maintained since late 60s, a local database with basic information on oceanographic campaigns, formerly known as ROSCOF reports, which were established in the framework of IODE initiatives, as a low-level inventory for future access to data. Technological advances in recent decades and different coordination activities between NODCs have favored the implementation of these reports in standardized digital formats (Cruise Summary Reports, CSR) that allow their integration in international repositories as SeaDataNet or POGO. However, this inventory and cataloging activity has suffered ups and downs over 40 years of activity, changes in storage criteria and periods of less activity. In the search for a unique criterion that can last over time and that unifies this information as much as possible with the data generated in these campaigns, an exhaustive review of the existing information has been carried out