SLAM using an Imaging Sonar for Partially Structured Underwater Environments

In this paper we describe a system for underwater navigation with AUVs in partially structured environments, such as dams, ports or marine platforms. An imaging sonar is used to obtain information about the location of planar structures present in such environments. This information is incorporated into a feature-based SLAM algorithm in a two step process: (I) the full 360deg sonar scan is undistorted (to compensate for vehicle motion), thresholded and segmented to determine which measurements correspond to planar environment features and which should be ignored; and (2) SLAM proceeds once the data association is obtained: both the vehicle motion and the measurements whose correct association has been previously determined are incorporated in the SLAM algorithm. This two step delayed SLAM process allows to robustly determine the feature and vehicle locations in the presence of large amounts of spurious or unrelated measurements that might correspond to boats, rocks, etc. Preliminary experiments show the viability of the proposed approach

Organized vs. competitive corruption

We study bureaucratic corruption in a model in which a constituencysets required levels for a given set of activities. Each activity iscarried out by an external provider, and its realization is supervisedby a bureaucrat. While bureaucrats are supposed to act on behalf of theconstituency, they can decide to be corrupt and allow providers todeliver lower activity levels than contracted in exchange for a bribe.Given this, the constituency sets the optimal activity levels weighingoff the value of activity levels, their costs, as well as the possibilityfor the bureaucrats to be corrupt. We use this setup to study the impacton equilibrium corruption of the degree of decentralization of corruption.To do this we compute equilibrium corruption in two different settings:1) Each bureaucrat acts in such a way as to maximize his own individualutility (competitive corruption); 2) An illegal syndicate oversee thecorruption decisions of the population of bureaucrats in such a way asto maximize total proceeds from corruption (organized corruption). Weshow that, since average corruption payoff is increasing in the activitylevels set by the constituency, and since the latter responds to highlevels of corruption by reducing required activity levels, in equilibriumthe illegal syndicate acts in such a way as to restrain the total numberof corrupt transactions, so that corruption is lower when it is organizedthan when it is competitive.

Manipulation of earnings reports in Spain - some evidence

Accounting regulation is a highly topical issue for listed companies in Europe. From 1 January 2005 all companies listed in the EU member states are required to produce financial reports compliant with international accounting standards. Financial reports will be comparable with each other only if full compliance with the international standards can be ensured. Historically, however, an enduring weakness of the international standard-setting regime has been its inability to enforce compliance with its standards. There is a danger that implementation and compliance will be variable across the adopting countries, and that deeply ingrained national reporting practices will persist. The purpose of this paper is to examine some distinctive elements of Spanish financial reporting practices. Spanish financial reporting by major companies demonstrates a tendency towards quite overt manipulation of the earnings figures. The research reported in the paper firstly identifies four common earnings manipulation practices, and then proceeds to examine their incidence in the financial statements of the IBEX-35 companies over a three year period.

Unemployment dynamics and NAIRU estimates for CEECs : a univariate approach

In this paper we test for the hysteresis versus the natural rate hypothesis on the unemployment rates of the EU new members using unit root tests that account for the presence of level shifts. As a by product, the analysis proceeds to the estimation of a NAIRU measure from a univariate point of view. The paper also focuses on the precision of these NAIRU estimates studying the two sources of inaccuracy that derive from the break points estimation and the autoregressive parameters estimation. The results point to the existence of up to four structural breaks in the transition countries NAIRU that can be associated with institutional changes implementing market-oriented reforms. Moreover, the degree of persistence in unemployment varies dramatically among the individual countries depending on the stage reached in the transition process

Fine speckle contrast in InGaAs/InP systems: Influence of layer thickness, missmatch, and growing temperature

This work is focused on the study of the fine speckle contrast present in planar view observations of matched and mismatched InGaAs layers grown by molecular beam epitaxy on InP substrates. Our results provide experimental evidence of the evolution of this fine structure with the mismatch, layer thickness, and growth temperature. The correlation of the influence of all these parameters on the appearance of the contrast modulation points to the development of the fine structure during the growth. Moreover, as growth proceeds, this structure shows a dynamic behavior which depends on the intrinsic layer substrate stress.

Unemployment dynamics and NAIRU estimates for CEECs : a univariate approach

In this paper we test for the hysteresis versus the natural rate hypothesis on the unemployment rates of the EU new members using unit root tests that account for the presence of level shifts. As a by product, the analysis proceeds to the estimation of a NAIRU measure from a univariate point of view. The paper also focuses on the precision of these NAIRU estimates studying the two sources of inaccuracy that derive from the break points estimation and the autoregressive parameters estimation. The results point to the existence of up to four structural breaks in the transition countries NAIRU that can be associated with institutional changes implementing market-oriented reforms. Moreover, the degree of persistence in unemployment varies dramatically among the individual countries depending on the stage reached in the transition process

Monte Carlo simulation of interface alloying

An Ising-like model, with interactions ranging up to next-nearest-neighbor pairs, is used to simulate the process of interface alloying. Interactions are chosen to stabilize an intermediate "antiferromagnetic" ordered structure. The dynamics proceeds exclusively by atom-vacancy exchanges. In order to characterize the process, the time evolution of the width of the intermediate ordered region and the diffusion length is studied. Both lengths are found to follow a power-law evolution with exponents depending on the characteristic features of the model.

Crystallization behaviour of some melt spun Nd-Fe-B alloys

The kinetics of crystallization of four amorphous (or partially amorphous) melt spun Nd-Fe-B alloys induced by thermal treatment is studied by means of differential scanning calorimetry and scanning electron microscopy, In the range of temperatures explored experimentally, the crystallization process is thermally activated and generally proceeds in various stages. The Curie temperature and the crystallization behavior have been measured. The apparent activation energy of crystallization of most of the crystallization stages has been determined for each melt spun alloy. The explicit form of the kinetic equation that best describes the first stage of crystallization has been found. It follows in general the Johnson-Mehl-Avrami-Erofe'ev model, but clear deviations to that model occur for one alloy. Scanning electron microscopy demonstrates that preferentially hetereogeneous nucleation occurs at the ribbon surface which was in contact with the wheel. From crystallization kinetics results the lower part of the experimental time-temperature-transformation curves for all studied alloys are deduced and extrapolated to the high temperature limit of their range of validity, also deduced.

Dispersion of passive particles by a quasi-two-dimensional turbulent flow

Using the experimental data of Paret and Tabeling [Phys. Rev. Lett. 79, 4162 (1997)] we consider in detail the dispersion of particle pairs by a two-dimensional turbulent flow and its relation to the kinematic properties of the velocity field. We show that the mean square separation of a pair of particles is governed by rather rare, extreme events and that the majority of initially close pairs are not dispersed by the flow. Another manifestation of the same effect is the fact that the dispersion of an initially dense cluster is not the result of homogeneously spreading the particles within the whole system. Instead it proceeds through a splitting into smaller but also dense clusters. The statistical nature of this effect is discussed.

Assessing the pH and DP of canvasses with NIR spectroscopy

The canvas support in easel paintings is composed mainly of cellulose. One of the maindegradation paths of cellulose is acid-catalysed hydrolysis, which means that in an acidic environment (low pH), its degradation proceeds at a faster rate (Strlič et al., 2005).The main effect of acid-catalysed hydrolysis is the breaking up of the polymer chains,measured by the “Degree of Polymerisation” (DP). The lowering of the DP value impliesa lower mechanical strength of the textile (Scicolone, 1993), and thus this parameter canbe used to monitor degradation. Knowing these two parameters can, therefore, be veryinformative regarding the condition of the canvas support.

Assessing the pH and DP of canvasses with NIR spectroscopy

The canvas support in easel paintings is composed mainly of cellulose. One of the maindegradation paths of cellulose is acid-catalysed hydrolysis, which means that in an acidic environment (low pH), its degradation proceeds at a faster rate (Strlič et al., 2005).The main effect of acid-catalysed hydrolysis is the breaking up of the polymer chains,measured by the “Degree of Polymerisation” (DP). The lowering of the DP value impliesa lower mechanical strength of the textile (Scicolone, 1993), and thus this parameter canbe used to monitor degradation. Knowing these two parameters can, therefore, be veryinformative regarding the condition of the canvas support.

Diagnóstico de las dificultades de lectura y escritura y de la dislexia basado en la Teoría PASS de lainteligencia utilizando la batería DN-CAS. Origen cognitivo de la dislexia

Las dificultades de lectura y escritura se pueden detectar desde el momento en que los niños y niñas inician el aprendizaje de la lectoescritura en la etapa de Educación Infantil. En algunos casos estos alumnos reciben un apoyo escolar que en muchas ocasiones no conlleva las mejoras esperadas, siendo las técnicas y metodologías de refuerzo aplicadas ineficaces. El problema, desde nuestro punto de vista, empieza con el diagnóstico que se realiza a estos jóvenes, que determina las directrices de la intervención idónea en cada caso. La Teoría PASS de la inteligencia nos permite conocer qué procesos están implicados cuando el niño lee o escribe, y parte de la premisa de que si conocemos el perfil cognitivo de un alumno que presenta dificultades podremos entender como estas se originan. Para conocer este perfil cognitivo (los cuatro procesos cognitivos que describe esta teoría: Planificación, Atención, Simultaneo y Secuencial) utilizamos la batería DN-CAS (Das & Naglieri: Cognitive Assessment System). El perfil obtenido al aplicar el DN-CAS nos permitirá conocer el origen de las dificultades de lectura y escritura, saber cuando está justificada una dislexia, descartar problemas emocionales o la presencia de los mismos y diseñar la intervención más adecuada en cada situación

Entropic transport in confined media: a challenge for computational studies in biological and soft-matter systems

Transport in small-scale biological and soft-matter systems typically occurs under confinement conditions in which particles proceed through obstacles and irregularities of the boundaries that may significantly alter their trajectories. A transport model that assimilates the confinement to the presence of entropic barriers provides an efficient approach to quantify its effect on the particle current and the diffusion coefficient. We review the main peculiarities of entropic transport and treat two cases in which confinement effects play a crucial role, with the appearance of emergent properties. The presence of entropic barriers modifies the mean first-passage time distribution and therefore plays a very important role in ion transport through micro- and nano-channels. The functionality of molecular motors, modeled as Brownian ratchets, is strongly affected when the motor proceeds in a confined medium that may constitute another source of rectification. The interplay between ratchet and entropic rectification gives rise to a wide variety of dynamical behaviors, not observed when the Brownian motor proceeds in an unbounded medium. Entropic transport offers new venues of transport control and particle manipulation and new ways to engineer more efficient devices for transport at the nanoscale.

Structural Insight into the Mode of Action of a Direct Inhibitor of Coregulator Binding to the Thyroid Hormone Receptor.

The development of nuclear hormone receptor antagonists that directly inhibit the association of the receptor with its essential coactivators would allow useful manipulation of nuclear hormone receptor signaling. We previously identified 3-(dibutylamino)-1-(4-hexylphenyl)-propan-1-one (DHPPA), an aromatic β-amino ketone that inhibits coactivator recruitment to thyroid hormone receptor β (TRβ), in a high-throughput screen. Initial evidence suggested that the aromatic β-enone 1-(4-hexylphenyl)-prop-2-en-1-one (HPPE), which alkylates a specific cysteine residue on the TRβ surface, is liberated from DHPPA. Nevertheless, aspects of the mechanism and specificity of action of DHPPA remained unclear. Here, we report an x-ray structure of TRβ with the inhibitor HPPE at 2.3-Å resolution. Unreacted HPPE is located at the interface that normally mediates binding between TRβ and its coactivator. Several lines of evidence, including experiments with TRβ mutants and mass spectroscopic analysis, showed that HPPE specifically alkylates cysteine residue 298 of TRβ, which is located near the activation function-2 pocket. We propose that this covalent adduct formation proceeds through a two-step mechanism: 1) β-elimination to form HPPE; and 2) a covalent bond slowly forms between HPPE and TRβ. DHPPA represents a novel class of potent TRβ antagonist, and its crystal structure suggests new ways to design antagonists that target the assembly of nuclear hormone receptor gene-regulatory complexes and block transcription.

The Francoist repression in the Catalan Countries

This article offers an overview of Francoist repression in the Catalan Countries from the outbreak of the Civil War to the first decade after the establishment of the dictatorship. It covers both physical violence and measures such as economic repression, imprisonment, professional purges and the social and moral control to which the population as a whole was subjected. First the type of violence and domination exercised by the insurgents in the territories occupied is briefly examined. Then the author offers an account of the events: she commences in the summer of 1936 in Majorca, the only Catalan-speaking territory to remain in rebel hands, then proceeds to the Lleida region, which was occupied in the spring of 1938, and concludes with the final offensive against Catalonia and Valencia, launched in the winter of that same year. Special stress is laid on the repercussions of the 1939 Law of Political Responsibilities and the meaning attached by the occupiers to the pacification and reconstruction of the conquered territories.