3,100 research outputs found
BTZ black hole from (3+1) gravity
We propose an approach for constructing spatial slices of (3+1) spacetimes
with cosmological constant but without a matter content, which yields (2+1)
vacuum with solutions. The reduction mechanism from (3+1) to (2+1)
gravity is supported on a criterion in which the Weyl tensor components are
required to vanish together with a dimensional reduction via an appropriate
foliation. By using an adequate reduction mechanism from the
Pleba\'nski-Carter[A] solution in (3+1) gravity, the (2+1) BTZ solution can be
obtained.Comment: 4 pages, Late
A Comprehensive Approach for the Conceptual Modeling of Genomic Data
The human genome is traditionally represented as a DNA sequence of three billion base pairs. However, its intricacies are captured by many more complex signals, representing DNA variations, the expression of gene activity, or DNA’s structural rearrangements; a rich set of data formats is used to represent such signals. Different conceptual models explain such elaborate structure and behavior. Among them, the Conceptual Schema of the Human Genome (CSG) provides a concept-oriented, top-down representation of the genome behavior – independent of data formats. The Genomic Conceptual Model (GCM) instead provides a data-oriented, bottom-up representation, targeting a well-organized, unified description of these formats. We hereby propose to join these two approaches to achieve a more complete vision, linking (1) a concepts layer, describing genome elements and their conceptual connections, with (2) a data layer, describing datasets derived from genome sequencing with specific technologies. The link is established when specific genomic data types are chosen in the data layer, thereby triggering the selection of a view in the concepts layer. The benefit is mutual, as data records can be semantically described by high-level concepts and exploit their links. In turn, the continuously evolving abstract model can be extended thanks to the input provided by real datasets. As a result, it will be possible to express queries that employ a holistic conceptual perspective on the genome, directly translated onto data-oriented terms and organization. The approach is here exemplified using the DNA variation data type but is applicable to all genomic information
Anticancer applications of nanostructured silica-based materials functionalized with titanocene derivatives: Induction of cell death mechanism through TNFR1 modulation
This article belongs to the Special Issue Nanomaterials for Biomedical ApplicationsA series of cytotoxic titanocene derivatives have been immobilized onto nanostructured silica-based materials using two different synthetic routes, namely, (i) a simple grafting protocol via protonolysis of the Ti-Cl bond; and (ii) a tethering method by elimination of ethanol using triethoxysilyl moieties of thiolato ligands attached to titanium. The resulting nanostructured systems have been characterized by different techniques such as XRD, XRF, DR-UV, BET, SEM, and TEM, observing the incorporation of the titanocene derivatives onto the nanostructured silica and slight changes in the textural features of the materials after functionalization with the metallodrugs. A complete biological study has been carried out using the synthesized materials exhibiting moderate cytotoxicity in vitro against three human hepatic carcinoma (HepG2, SK-Hep-1, Hep3B) and three human colon carcinomas (DLD-1, HT-29, COLO320) and very low cytotoxicity against normal cell lines. In addition, the cells' metabolic activity was modified by a 24-h exposure in a dose-dependent manner. Despite not having a significant effect on TNFalfa or the proinflammatory interleukin 1alfa secretion, the materials strongly modulated tumor necrosis factor (TNF) signaling, even at sub-cytotoxic concentrations. This is achieved mainly by upregulation of the TNFR1 receptor production, something which has not previously been observed for these systems.We gratefully acknowledge financial support from FEDER and the Ministerio de Economía y Competitividad, Spain (grant no. CTQ2015-66164-R) and the Romanian UEFISCDI Exploratory Research Project PN-III-P4-ID-PCE-2016-0870, IMPRESS. We would also like to thank Universidad Rey Juan Carlos and
Banco de Santander for supporting our Research Group of Excellence QUINANOAP. Finally, we thank D. Pérez
for valuable discussion and S. Carralero and C. Forcé for their assistance with solid-state NMR experiments
A Software Engineering Experiments to value MDE in testing. Learning Lessons
Controlled experiments are commonly used to evaluate Software Engineering
methods, processes and tools. Validating results of Software Engineering re search in industrial settings is a direct way to obtain feedback about its value.
However, few software engineering experiments are running in industry. The
lack of communication between companies and research teams does not make
the necessary cooperation among them possible. This paper presents our experi ences when running an experiment dealing with Early Testing at the University
of Seville. It also introduces the strategy we followed to obtain the participation
of 97 practitioners from 32 different software companies. Such strategy is
pointed out as a set of guidelines to successfully involve this large number of
companies and practitioners.Ministerio de Economía y Competitividad TIN2013-46928-C3-3-RMinisterio de Economía y Competitividad TIN2015-71938-RED
Monolithic integration of Giant Magnetoresistance (GMR) devices onto standard processed CMOS dies
Giant Magnetoresistance (GMR) based technology is nowadays the preferred option for low magnetic fields sensing in disciplines such as biotechnology or microelectronics. Their compatibility with standard CMOS processes is currently investigated as a key point for the development of novel applications, requiring compact electronic readout. In this paper, such compatibility has been experimentally studied with two particular non-dedicated CMOS standards: 0.35 μm from AMS (Austria MicroSystems) and 2.5 μm from CNM (Centre Nacional de Microelectrònica, Barcelona) as representative examples. GMR test devices have been designed and fabricated onto processed chips from both technologies. In order to evaluate so obtained devices, an extended characterization has been carried out including DC magnetic measurements and noise analysis. Moreover, a 2D-FEM (Finite Element Method) model, including the dependence of the GMR device resistance with the magnetic field, has been also developed and simulated. Its potential use as electric current sensors at the integrated circuit level has also been demonstrated
Classification Rule Mining with Iterated Greedy
In the context of data mining, classi cation rule discovering
is the task of designing accurate rule based systems that model the useful
knowledge that di erentiate some data classes from others, and is present
in large data sets.
Iterated greedy search is a powerful metaheuristic, successfully applied to
di erent optimisation problems, which to our knowledge, has not previously
been used for classi cation rule mining.
In this work, we analyse the convenience of using iterated greedy algorithms
for the design of rule classi cation systems. We present and
study di erent alternatives and compare the results with state-of-the-art
methodologies from the literature. The results show that iterated greedy
search may generate accurate rule classi cation systems with acceptable
interpretability level
A Reference Meta-model to Understand DNA Variant Interpretation Guidelines
Determining the role of a DNA variant in patients’ health status – a process known as variant interpretation – is highly critical for precision medicine applications. Variant interpretation involves a complex process where, regrettably, there is still debate on how to combine and weigh diverse available evidence to achieve proper and consistent answers. Indeed, at the time of writing, 22 different variant interpretation guidelines are available to the scientific community, each of them attempting to establish a framework for standardizing the interpretation process. However, these guidelines are qualitative and vague by nature, which hinders their streamlined application and potential automation. Consequently, more precise definitions are needed. Conceptual modeling provides the means to bring clarification within this domain. This paper presents our efforts to define and use a UML meta-model that describes the main concepts involved in the definition of variant interpretation guidelines and the constructs they evaluate. The precise conceptual definition of the guidelines allowed us to identify four common misinterpretation patterns that hamper the correct interpretation process and that can consequently affect classification results. In several proposed examples, the use of the meta-model provides support in identifying the inconsistencies in the observed process; this result paves the way for further proposing reconciliation strategies for the existing guidelines
An Alternative Interpretation for the Moduli Fields of the Cosmology Associated to Type IIB Supergravity with Fluxes
We start with a particular cosmological model derived from type IIB
supergravity theory with fluxes, where usually the dilaton is interpreted as a
Quintessence field. Instead of that, in this letter we interpret the dilaton as
the dark matter of the universe. With this alternative interpretation we find
that in this supergravity model gives a similar evolution and structure
formation of the universe compared with the CDM model in the linear
regime of fluctuations of the structure formation. Some free parameters of the
theory are fixed using the present cosmological observations. In the non-linear
regimen there are some differences between the type IIB supergravity theory
with the traditional CDM paradigm. The supergravity theory predicts the
formation of galaxies earlier than the CDM and there is no density cusp in the
center of galaxies. These differences can distinguish both models and can give
a distinctive feature to the phenomenology of the cosmology coming from
superstring theory with fluxes.Comment: 7 pages, 5 figures, references added, minor modifications, typos
corrected. Version accepted for publication in IJMP
Colliding Plane Waves in Einstein-Maxwell-Dilaton Fields
Within the metric structure endowed with two orthogonal space-like Killing
vectors a class of solutions of the Einstein-Maxwell-Dilaton field equations is
presented. Two explicitly given sub-classes of solutions bear an interpretation
as colliding plane waves in the low-energy limit of the heterotic string
theory.Comment: 14 pages, LaTex; To appear in Phys. Rev.
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