10,290 research outputs found
Bares 2.0 wave buoy and sustainable buoy network
The aim of this article is to show the operation of the Bares 2.0 wave buoy
and the Bares network developed by HCTech. In the marine sector it is highly important
to know the state of the sea for applications such as the construction of ports,
the study of the impact of waves in coastal areas, the development and calibration
of forecasting wave models, the knowledge of the state of the maritime navigation
channels, etc. Some of the great difficulties that exist in order to obtain the information
of ocean waves is the high cost of the buoys, installation and maintenance. The
Bares network aims to cover areas of high oceanographic interest, the target is a
sustainable network of buoys that facilitate the access to wave data. The features
of this network are the optimized cost, high reliability and reduced maintenance.Peer Reviewe
Pathological element-based active device models and their application to symbolic analysis
This paper proposes new pathological element-based active device models which can be used in analysis tasks of linear(ized) analog circuits. Nullators and norators along with the voltage mirror-current mirror (VM-CM) pair (collectively known as pathological elements) are used to model the behavior of active devices in voltage-, current-, and mixed-mode, also considering parasitic elements. Since analog circuits are transformed to nullor-based equivalent circuits or VM-CM pairs or as a combination of both, standard nodal analysis can be used to formulate the admittance matrix. We present a formulation method in order to build the nodal admittance (NA) matrix of nullor-equivalent circuits, where the order of the matrix is given by the number of nodes minus the number of nullors. Since pathological elements are used to model the behavior of active devices, we introduce a more efficient formulation method in order to compute small-signal characteristics of pathological element-based equivalent circuits, where the order of the NA matrix is given by the number of nodes minus the number of pathological elements. Examples are discussed in order to illustrate the potential of the proposed pathological element-based active device models and the new formulation method in performing symbolic analysis of analog circuits. The improved formulation method is compared with traditional formulation methods, showing that the NA matrix is more compact and the generation of nonzero coefficients is reduced. As a consequence, the proposed formulation method is the most efficient one reported so far, since the CPU time and memory consumption is reduced when recursive determinant-expansion techniques are used to solve the NA matrix.Promep-Mexico UATLX-PTC-088Junta de Andalucía TIC-2532Ministerio de Educación y Ciencia TEC2007-67247, TEC2010-14825UC-MEXUS-CONACyT CN-09-31
Dynamics of link states in complex networks: The case of a majority rule
Motivated by the idea that some characteristics are specific to the relations
between individuals and not of the individuals themselves, we study a prototype
model for the dynamics of the states of the links in a fixed network of
interacting units. Each link in the network can be in one of two equivalent
states. A majority link-dynamics rule is implemented, so that in each dynamical
step the state of a randomly chosen link is updated to the state of the
majority of neighboring links. Nodes can be characterized by a link
heterogeneity index, giving a measure of the likelihood of a node to have a
link in one of the two states. We consider this link-dynamics model on fully
connected networks, square lattices and Erd \"os-Renyi random networks. In each
case we find and characterize a number of nontrivial asymptotic configurations,
as well as some of the mechanisms leading to them and the time evolution of the
link heterogeneity index distribution. For a fully connected network and random
networks there is a broad distribution of possible asymptotic configurations.
Most asymptotic configurations that result from link-dynamics have no
counterpart under traditional node dynamics in the same topologies.Comment: 9 pages, 13 figure
Local regularity for fractional heat equations
We prove the maximal local regularity of weak solutions to the parabolic
problem associated with the fractional Laplacian with homogeneous Dirichlet
boundary conditions on an arbitrary bounded open set
. Proofs combine classical abstract regularity
results for parabolic equations with some new local regularity results for the
associated elliptic problems.Comment: arXiv admin note: substantial text overlap with arXiv:1704.0756
Discovery and characterizatopn of small molecular weight metallocarboxypeptidase inhibitors
Descripció del recurs: el 02 de novembre de 2010Las hidrolasas son enzimas que catalizan la ruptura del enlace amida o peptódico, y por lo tanto son denominadas también proteasas o peptidasas. Las proteasas constituyen cerca del 2 % del genoma humano, lo que representa unos 600 productos génicos. De acuerdo con el residuo catalóticamente activo, existen seis grandes grupos de peptidasas. En este trabajo nos centraremos en la familia M14 de peptidasas, también denominadas metalocarboxipeptidasas (CPs) debido a que su actividad catalótica reside en el ion zinc presente en el sitio activo de la enzima. En el genoma humano, se han identificado al menos 26 genes que codifican carboxipeptidasas. Las peptidasas de la familia M14 que actúan en el tracto gastrointestinal son las principales metaloproteasas responsables de la obtención de aminoácidos libres de la proteína de la dieta. En otros compartimientos corporales, las CPs pueden llevar a cabo tareas especializadas y altamente reguladas como ser la maduración de neuropéptidos, citokinas y hormonas peptódicas. En algunos casos, una actividad catalótica fuera de control puede conducir a enfermedades. Cada vez existe una mayor evidencia experimental que demuestra la actividad carboxipeptidasa en procesos como la pancreatitis aguda, la diabetes, la inflamación, la fibrinólisis y el cáncer. A pesar de ciertos avances en algunos aspectos, la actividad específica de las CPs es pobremente conocida. Además, las carboxipeptidasas son blancos terapéuticos interesantes para el desarrollo de fármacos, y por lo tanto se ha decidido emplear una aproximación multi-disciplinaria para la identificación y caracterización de nuevas moléculas de bajo peso molecular capaces de interferir la actividad carboxipeptidasa. Así, en este trabajo se han combinado modernas herramientas computacionales, screening in vitro, modelado molecular y cristalografía de rayos X con el fin de obtener nuevas entidades quφmicas como base para el desarrollo de fármacos. Con base en herramientas computacionales, aplicando el método de Optimal Docking Areaö, se han caracterizado sitios de unión proteína-proteína y proteína-ligando en la superficie de las peptidasas de la familia M14. A partir de aquí, se identificó una nueva clase de compuestos químicos capaces de explotar las diferencias existentes entre enzimas de la familia por unión a regiones hidrofóbicas. Otros inhibidores fueron identificados mediante un screening in silico de grandes colecciones de compuestos. Ensayos in vitro demostraron que los compuestos líderes inhibieron de manera potente a las carboxipeptidasas blanco con otras características interesantes como la posibilidad de coordinación del ion zinc catalítico por intermedio de un anillo oxadiazol. A través de una colaboración con el Departamento de Química Orgánica se obtuvieron y caracterizaron nuevos compuestos químicos con conectividades atómicas novedosas que, inesperadamente, demostraron ser potentes inhibidores de carboxipeptidasas. Una clase adicional de molécula de bajo peso molecular caracterizada corresponde a inhibidores que se unen covalentemente al enzima blanco. En este caso, se logró obtener la estructura tridimensional del complejo a resolución atómica mediante cristalografφa de rayos X, lo que ha permitido el dise±o basado en la estructura de una nueva generación de compuestos. Basados en otros datos de cristalografía de rayos X y análisis computacional, se ha revisado y ampliado el mecanismo de acción catalítica de las peptidasas de la familia M14 a partir de una nueva forma cristalina de CPB a alta resolución. En conjunto, nuestro trabajo ha permitido la obtención de nuevas moléculas líderes de bajo peso molecular que podrían servir como base para futuros desarrollos en el diseño de fármacos y agentes de diagnóstico o imaginería dirigidos a metalocarboxipeptidasas fisiológicamente activas.Hydrolases are enzymes catalyzing the breakdown of the amide or peptide bond, and are therefore called proteases or peptidases as well. In the human genome, proteases made up about 2% of the genome, or about 600 gene products. There are six major groups of peptidases according to the catalytic residue. In our work we focused on the M14 family of peptidases, also called metallocarboxypeptidases (CPs) because of their catalytic activity hinges on the zinc ion present in the active site of the enzyme. In the human genome there are identified at least 26 genes encoding for CPs. M14 peptidases in the gastrointestinal tract are the main metalloproteases responsible of the liberation of free aminoacids from the protein content of the diet. In other compartments of the body, CPs may perform specialized and tightly controlled tasks such as neuropeptide, cytokine and hormone maturation. In some instances an imbalance in their activity leads to disease states in man. Increasing evidence shows carboxypeptidase involvement in acute pancreatitis, diabetes, inflammation, fibrinolysis and cancer. Although some aspects have become clearer, much of their activity remain poorly understood. Besides, carboxypeptidases are interesting targets for drug development, and therefore we pursued a multidisciplinary approach to identify and characterize novel small molecular weight compounds able to interfere carboxypeptidase activity. In this work we combined modern computational tools, in vitro screening, molecular modelling and X-ray crystallography to obtain new chemical entities useful as scaffolds for drug design. Based on a bioinformatics tools, the Optimal Docking Area method, we identified protein-protein and protein-ligand binding sites over the surface of M14 peptidases. This knowledge was employed to find out a new class of small molecular weight inhibitors which exploit the differential binding provided by hydrophobic patches. A further class of inhibitors was identified from in silico screening of collections of compounds. In vitro analysis revealed that the leads were potent inhibitors against the target proteases with interesting features like an oxadiazole zinc-chelating moiety. Compounds obtained from the Organic Chemistry Department were also screened, and unexpectedly, afforded some good inhibitors with unprecedented atomic bonding. One further class involved inhibitors that attach covalently to the target enzyme. In this case the structure of the complex obtained at high resolution by X-ray crystallography allowed the structure-guided design of new generation of compounds. The catalytic mechanism of M14 peptidases was also revisited based on our crystallographic and computational analysis of a new CPB crystal form at high resolution. Overall, our study provided new lead small molecular weight inhibitors which can be the foundation for further developments in the design of drugs and bioimaging or diagnostic agents targeted to physiologically-relevant metallocarboxypeptidases
Self-supported polypyrrole/polyvinylsulfate films: electrochemical synthesis, characterization, and sensing properties of their redox reactions
Thick films of polypyrrole/polyvinylsulfate (PPy/PVS) blends were electrogenerated on stainless‐steel electrodes under potentiostatic conditions from aqueous solution. The best electropolymerization potential window was determined by cyclic voltammetry. After removing the film from the back metal, self‐supported electrodes were obtained. Voltammetric, coulovoltammetric, and chronoamperometric responses from a LiClO4 aqueous solution indicated the formation of an energetically stable structure beyond a reduction threshold of the material. Its subsequent oxidation required higher anodic voltammetric overpotentials or longer chronoamperometric oxidation times. This structure was attributed to the formation of lamellar or vacuolar structures. X‐ray photoelectron spectroscopy analysis of the films under different oxidations states revealed that the electrochemical reactions drive the reversible exchange of cations between the film and the electrolyte. The electrical energy and the charge consumed by the reversible reaction of the film under voltammetric conditions between the constant potential limits are a function of the potential scan rate, that is, they sense the working electrochemical conditions.This project was supported by the Marie‐Sklodowska‐Curie Innovative Training Network MICACT‐H2020‐MSCA‐ITN‐2014 and by the Séneca Foundation project 19253/PI/14
The BLA Benchmark: Investigating Basic Language Abilities of Pre-Trained Multimodal Models
Despite the impressive performance achieved by pre-trained language-and-vision models in downstream tasks, it remains an open question whether this reflects a proper understanding of image-text interaction. In this work, we explore to what extent they handle basic linguistic constructions—active-passive voice, coordination, and relative clauses—that even preschool children can typically master. We present BLA, a novel, automatically constructed benchmark to evaluate multimodal models on these Basic Language Abilities. We show that different types of Transformer-based systems, such as CLIP, ViLBERT, and BLIP2, generally struggle with BLA in a zero-shot setting, in line with previous findings. Our experiments, in particular, show that most of the tested models only marginally benefit when fine-tuned or prompted with construction-specific samples. Yet, the generative BLIP2 shows promising trends, especially in an in-context learning setting. This opens the door to using BLA not only as an evaluation benchmark but also to improve models’ basic language abilities
Spin degree of freedom in two dimensional exciton condensates
We present a theoretical analysis of a spin-dependent multicomponent
condensate in two dimensions. The case of a condensate of resonantly
photoexcited excitons having two different spin orientations is studied in
detail. The energy and the chemical potentials of this system depend strongly
on the spin polarization . When electrons and holes are located in two
different planes, the condensate can be either totally spin polarized or spin
unpolarized, a property that is measurable. The phase diagram in terms of the
total density and electron-hole separation is discussed.Comment: 4 pages, 3 figures, Accepted for publication in Physical Review
Letter
Numerical modeling and measurement by pulsed television holography of ultrasonic displacement maps in plates with through-thickness defects
We present a novel numerical modeling of ultrasonic Lamb and Rayleigh wave propagation and scattering by through-thickness defects like holes and slots in homogeneous plates, and its experimental verification in both near and far field by a self-developed pulsed TV holography system. In contrast to rigorous vectorial formulation of elasticity theory, our model is based on the 2-D scalar wave equation over the plate surface, with specific boundary conditions in the defects and plate edges. The experimental data include complex amplitude maps of the out-of-plane displacements of the plate surface, obtained by a two-step spatiotemporal Fourier transform method. We find a fair match between the numerical and experimental results, which allows for quantitative characterization of the defects
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