Publishing Performance of Spanish Academics: 1970-2004: Institutions, Researchers et al.

This work complements some of the results appearing in the article ?Publishing Performance in Economics: Spanish Rankings? by Dolado et al. . Specifically we focus on the robustness of the results regardless of the time span considered, the effect of the choice of a particular database on the final results, and the effects on changes in the unit of institutional measure (departments versus institutions as a whole). Differences are significant when we expand the time period considered. There are also significant but small differences if we combine datasets to derive the rankings. Finally, department rankings offer a more precise picture of the situation of the Spanish academics, although results do not differ substantially from those obtained when overall institutions are considered.rankings, economics, Spanish academics, bibliometric indicators

Manipulation of optically fabricated particle arrays using broadband radiation

Consideration is given to methods of manipulating optically fabricated particle arrays using broadband radiation and a superposition of optical fields. Specifically, the changes that the optical binding energy experiences, when part of the spectrum of this light is filtered, are analyzed. It is then shown that these optically induced arrays can be reordered by the introduction of additional fields with transverse Poynting vectors. Subsequently, it is shown how pairs of particles can be reordered on a surface by modifying the form of the optical binding interaction. Finally, the effect of particle size on these methods is briefly discussed

How Much Uncompensated Care do Doctors Provide?

The magnitude of provider uncompensated care has become an important public policy issue. Yet existing measures of uncompensated care are flawed because they compare uninsured payments to list prices, not to the prices actually paid by the insured. We address this issue using a novel source of data from a vendor that processes financial data for almost 4000 physicians. We measure uncompensated care as the net amount that physicians lose by lower payments from the uninsured than from the insured. Our best estimate is that physicians provide negative uncompensated care to the uninsured, earning more on uninsured patients than on insured patients with comparable treatments. Even our most conservative estimates suggest that uncompensated care amounts to only 0.8% of revenues, or at most $3.2 billion nationally. These results highlight the important distinction between charges and payments, and point to the need for a re-definition of uncompensated care in the health sector going forward.

The value of coskewness in evaluating mutual funds

Recent asset pricing studies demonstrate the relevance of incorporating the coskewness in Asset Pricing Models, and illustrate how this component helps to explain the time variation of ex-ante market risk premiums. This paper analyzes the role of coskewness in mutual funds performance evaluation. We find evidence that adding a coskewness factor is economically and statistically significant. We document that some managers are managing the coskewness and show, in general, a persistent behaviour on time in their coskewness policy. One of the most striking results is that many negative (positive) alpha funds measured relative to the CAPM risk adjustments would be reclassified as positive (negative) alpha funds using a model with coskewness. Therefore, a ranking of funds based on risk adjusted returns without considering coskewness would generate an erroneous classification. Moreover, some fund characteristics, such as the turnover ratio or the category, are related to the likelihood of managing coskewness.Mutual funds, Performance measures, Coskewness

Formal security analysis of registration protocols for interactive systems: a methodology and a case of study

In this work we present and formally analyze CHAT-SRP (CHAos based Tickets-Secure Registration Protocol), a protocol to provide interactive and collaborative platforms with a cryptographically robust solution to classical security issues. Namely, we focus on the secrecy and authenticity properties while keeping a high usability. In this sense, users are forced to blindly trust the system administrators and developers. Moreover, as far as we know, the use of formal methodologies for the verification of security properties of communication protocols isn't yet a common practice. We propose here a methodology to fill this gap, i.e., to analyse both the security of the proposed protocol and the pertinence of the underlying premises. In this concern, we propose the definition and formal evaluation of a protocol for the distribution of digital identities. Once distributed, these identities can be used to verify integrity and source of information. We base our security analysis on tools for automatic verification of security protocols widely accepted by the scientific community, and on the principles they are based upon. In addition, it is assumed perfect cryptographic primitives in order to focus the analysis on the exchange of protocol messages. The main property of our protocol is the incorporation of tickets, created using digests of chaos based nonces (numbers used only once) and users' personal data. Combined with a multichannel authentication scheme with some previous knowledge, these tickets provide security during the whole protocol by univocally linking each registering user with a single request. [..]Comment: 32 pages, 7 figures, 8 listings, 1 tabl