Accretion variability of Herbig Ae/Be stars observed by X-Shooter. HD 31648 and HD 163296

This work presents X-Shooter/VLT spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of twelve ultraviolet, optical and near infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 x 10^-7 and 4.50 x 10^-7 Msun yr^-1 for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ~ 15 years. Averaged accretion luminosities derived from the Balmer excess are consistent with the ones inferred from the empirical calibrations with the emission line luminosities, indicating that those can be extrapolated to HAe stars. In spite of that, the accretion rate variations do not generally coincide with those estimated from the line luminosities, suggesting that the empirical calibrations are not useful to accurately quantify accretion rate variability.Comment: 14 pages, 7 Figures, Accepted in Ap

Intrinsic limitations of inverse inference in the pairwise Ising spin glass

We analyze the limits inherent to the inverse reconstruction of a pairwise Ising spin glass based on susceptibility propagation. We establish the conditions under which the susceptibility propagation algorithm is able to reconstruct the characteristics of the network given first- and second-order local observables, evaluate eventual errors due to various types of noise in the originally observed data, and discuss the scaling of the problem with the number of degrees of freedom

Software infrastructure for solving non-linear partial differential equations and its application to modelling crustal fault systems

In this paper we will give a brief introduction into the Python-based modelling language escript. We will present a model for the dynamics of fault systems in the Earth's crust and then show how escript is used to implement solution algorithms for a dynamic as well as a quasi-static scenario

Introduction to construction dispute resolution

Leading construction experts have identified Productivity, Innovation, Cost Control, Safety, and Litigation Expenses as critical areas in need of improvement in the construction industry of this next century. In the United States alone, $60 billion are spent every year on lawsuits, of which the construction industry accounts for nearly$5 billion. The fact that these construction litigation expenditures have increased at an average rate of 10% per year for the past ten years is one of the primary motivations for this book. This reality has generated the need to develop new Dispute Avoidance and Resolution Techniques (DART) with the aim of curving this cost spiral and improving productivity. Fueled by this need, and as projects throughout the world continually achieve higher levels of complexity, the field of construction dispute resolution has exploded with innovative ways to prevent conflict and resolve disagreements. Companies have found that in highly competitive markets, the resolution of disputes has become a key to forging stronger and longer-lasting relationships with their clients. As a result, the construction industry has been in the forefront of the development of DART. This book presents and reviews a significant number of new and innovative ways to promote collaborative environments and resolve disputes in construction. This includes some practical applications of DART in the construction industry throughout a number of nations. The aim is to provide the reader with data to support the successes or failures of these techniques in multiple cultures. In effort to ground the material in this book, some examples are presented of how the material relates to current construction projects. These examples will be referred to as cases. Not all the information specific to the project has been presented, as they are only included to correlate theory with practice. They are also not included to illustrate either effective or ineffective handling of dispute avoidance and resolution procedures. In addition, some names or facts may have been changed for confidentiality reasons. Each of the relevant chapters will open up with an introduction of facts to the case and leave the reader with some questions to ponder while reading the chapter. At the end of each chapter the case is revisited relating the chapter information to the project situation. This introductory book is divided into 12 chapters. The first chapter describes the construction industry, focusing on its size, structure, relationships and sources of conflicts. Chapter 2 presents a background for the evolution of construction DART. It also presents a brief review of the reasons behind the apparent large number of disputes in the construction industry, and identifies characteristics that make the construction process adversarial in nature. The final section of Chapter 2 looks at two different proposals for the organization of DART in the construction industry. It selects the concept of the “Dispute Resolution Ladder” (DRL) to organize and present different techniques found being used around the world. Chapters 3 through 9 present the state of the art review of DART in the construction industry following each of the stages of the DRL defined in Chapter 2. Chapter 3 reviews techniques in the Prevention Stage with examples of mechanisms that can mitigate and discourage disputes during the construction process. This chapter highlights the role the owner plays in the introduction of dispute avoidance and resolution clauses in construction contracts and as a promoter of honest communications between the parties to the project. Chapter 4 reviews the concept of Partnering. Although not a Stage in the Dispute Resolution Ladder (DRL), Partnering was developed to change the adversarial approach to the construction process, with the aim to improve job performance and reduce conflict and confrontation. This concept integrates dispute resolution with other communication and collaboration techniques that have resulted in a significant reduction in the number of conflicts in those projects in which it is fully implemented. This chapter introduces the essential phases of the system, and its key components. Chapter 5 examines the Negotiation Stage in the process of dispute resolution in construction. This chapter offers three different approaches to improving the outcomes of negotiations: Step Negotiations, Structured Negotiations, and Facilitated Negotiations. The introduction of neutral third parties begins in Chapter 6, with the Standing Neutral Stage; a concept based on the incorporation of an unbiased, knowledgeable party as an instrument to resolve disputes efficiently and effectively as soon as they develop. Chapter 7 examines the Non-Binding Phase of the DRL, covering Mediation, Advisory Opinion, Fact-based Mediation, Minitrial, Summary Jury Trial, and Voluntary Settlement Conference as the available DART techniques. A significant acceptance of non-binding dispute resolution mechanisms is reflected in the number of variations that have developed, as these procedures represent the last stage of the DRL in which the parties have control over the outcome of the dispute. Chapter 8 examines approaches where a third party issues a final award to settle the dispute. These approaches correspond to the Binding Dispute Resolution Stage in the DRL. Arbitration, the most common form of binding resolution procedure, is reviewed, together with three other developments that can prove advantageous to a project that might be inclined to minimize arbitration. Finally, as part of this review of DART in construction, Chapter 9 looks at Alternative Litigation and Litigation as the last Stage in the DRL. This Stage corresponds to a dispute resolution procedure of “last-resort,” and is examined together with three techniques that can help reduce the amount of resources spent on court proceedings (i.e., time and money). Chapter 10 presents the concept of a Conflict Management Plan for projects. In all arenas of construction, conflict is evident, but being able to quantify the degree of conflict is challenging. Taking into consideration, the causes and results of the most common conflict situations, a conflict management plan can be designed from the DART presented in the previous chapters. The probability of conflict occurring is assessed along with the impact that each conflict may have on the project. A preventative strategy is developed to reduce the probability of conflict occurring and a resolution strategy is planned to minimize the impact of conflict if it does occur. The resulting Conflict Management Plan will help owners and contractors to evaluate the interactions among participants and actively involve everyone in the dispute resolution process. Following the presentation of all the material in the book, Chapter 11 analyzes a light rail transit project in San Juan, Puerto Rico. This case study is included to promote discussion on the methods to avoid claims and resolve disputes used in the project. This project made use of preventative measures such as Partnering as well as a predefined dispute resolution system. Analyzing this project allows the reader to envision how new and innovative techniques can be implemented into the industry. Finally, Chapter 12 gathers the conclusions of the book. First, it summarizes the DART techniques. Second, it highlights the importance of alternative dispute resolution in construction worldwide and how cultural conditions have affected the selection of the DART, based on the examples presented throughout the book. Finally, this chapter suggests areas for further study in the field of construction conflict, dispute avoidance, and alternative resolution methodologies

Sarcophagidae (Diptera) atraídos a cadáveres de cochinillo, con nuevas citas para la fauna portuguesa

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Thermodynamics of natural images

The scale invariance of natural images suggests an analogy to the statistical mechanics of physical systems at a critical point. Here we examine the distribution of pixels in small image patches and show how to construct the corresponding thermodynamics. We find evidence for criticality in a diverging specific heat, which corresponds to large fluctuations in how "surprising" we find individual images, and in the quantitative form of the entropy vs. energy. The energy landscape derived from our thermodynamic framework identifies special image configurations that have intrinsic error correcting properties, and neurons which could detect these features have a strong resemblance to the cells found in primary visual cortex

Regularization of odd-dimensional AdS gravity: Kounterterms

As an alternative to the Dirichlet counterterms prescription, I introduce the concept of Kounterterms as the boundary terms with explicit dependence on the extrinsic curvature K_{ij} that regularize the AdS gravity action. Instead of a Dirichlet boundary condition on the metric, a suitable choice of the boundary conditions --compatible with any asymptotically AdS (AAdS) spacetime-- ensures a finite action principle for all odd dimensions. Background-independent conserved quantities are obtained as Noether charges associated to asymptotic symmetries and their general expression appears naturally split in two parts. The first one gives the correct mass and angular momentum for AAdS black holes and vanishes identically for globally AdS spacetimes. Thus, the second part is a covariant formula for the vacuum energy in AAdS spacetimes and reproduces the results obtained by the Dirichlet counterterms method in a number of cases. It is also shown that this Kounterterms series regularizes the Euclidean action and recovers the correct black hole thermodynamics in odd dimensions.Comment: 35+6 pages, 8 references and an appendix added, improved discussion on boundary conditions and geometrical origin of Kounterterms. Version accepted in JHE

Thermodynamics of Black Holes in Schroedinger Space

A black hole and a black hyperboloid solutions in the space with the Schroedinger isometries are presented and their thermodynamics is examined. The on-shell action is obtained by the difference between the extremal and non-extremal ones with the unusual matching of the boundary metrics. This regularization method is first applied to the black brane solution in the space of the Schroedinger symmetry and shown to correctly reproduce the known thermodynamics. The actions of the black solutions all turn out to be the same as the AdS counterparts. The phase diagram of the black hole system is obtained in the parameter space of the temperature and chemical potential and the diagram contains the Hawking-Page phase transition and instability lines.Comment: 20 page