75 research outputs found
Isotropy of the velocity of light and the Sagnac effect
In this paper, it is shown, using a geometrical approach, the isotropy of the
velocity of light measured in a rotating frame in Minkowski space-time, and it
is verified that this result is compatible with the Sagnac effect. Furthermore,
we find that this problem can be reduced to the solution of geodesic triangles
in a Minkowskian cylinder. A relationship between the problems established on
the cylinder and on the Minkowskian plane is obtained through a local isometry.Comment: LaTeX, 13 pages, 3 eps figures; typos corrected, added references,
minor changes; to appear in "Relativity in Rotating Frames", ed. G. Rizzi G.
and M.L. Ruggiero, Kluwer Academic Publishers, Dordrecht (2003
Institutional investors and corporate governance
We provide a comprehensive overview of the role of institutional investors in corporate governance with three main components. First, we establish new stylized facts documenting the evolution and importance of institutional ownership. Second, we provide a detailed characterization of key aspects of the legal and regulatory setting within which institutional investors govern portfolio firms. Third, we synthesize the evolving response of the recent theoretical and empirical academic literature in finance to the emergence of institutional investors in corporate governance. We highlight how the defining aspect of institutional investors – the fact that they are financial intermediaries – differentiates them in their governance role from standard principal blockholders. Further, not all institutional investors are identical, and we pay close attention to heterogeneity amongst institutional investors as blockholders
Validar a guerra: a construção do regime de Expertise estratégica
This article is intended to contribute to the interpretative analysis of war. For that purpose, it investigates how some apparatuses located in strategic thinking help to make modern war a social practice considered both technically feasible and, at the same time, legitimate for soldiers. In so doing, it makes use of two different but closely related theoretical fields, pragmatic sociology (finding inspiration in the work of scholars such as Luc Boltanski, Nicolas Dodier and Francis Chateauraynaud), and the sociology of scientific knowledge (based mostly on the work of Bruno Latour). On the one hand, the sociology of scientific knowledge has developed a productive questioning of the construction of scientific facts that is particularly relevant to the present research. On the other hand, pragmatic sociology generates a compatible framework able to describe collective actions. The combination of both approaches allows the description of the formation of a strategic expertise regime that supports the technical legitimacy of the use of military force. Together, the sociology of scientific knowledge and pragmatic sociology bring a particularly relevant perspective to research pertaining to war.info:eu-repo/semantics/publishe
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
THEORETICAL AND EXPERIMENTAL STRESS ANALYSIS OF ORNL THIN-SHELL CYLINDER-TO- CYLINDER MODEL NO. 1.
High-Spatial- and High-Temporal-Resolution Dynamic Contrast-enhanced MR Breast Imaging with Sweep Imaging with Fourier Transformation: A Pilot Study
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Durability of composites in automotive structural applications
The overall goal of the project is to develop experimentally-based, durability-driven design guidelines for automotive composite structures and to demonstrate their applicability to lightweight, manufacturable structures under representative field loading histories and environments. Key technical issues are the potentially degrading effects that (1) both cyclic and long-term sustained loadings, (2) various automotive environments, and (3) low-energy impacts can have on the dimensional stability, strength, and stiffness of automotive composite structures. The purpose of this paper is to present the findings and observations developed to date and to outline future directions
Contaminant Adsorption on Nanoscale Particles: Structural and Theoretical Characterization of Cu<sup>2+</sup> Bonding on the Surface of Keggin-Type Polyaluminum (Al<sub>30</sub>) Molecular Species
The adsorption of contaminants onto
metal oxide surfaces with nanoscale
Keggin-type structural topologies has been well established, but identification
of the reactive sites and the exact binding mechanism are lacking.
Polyaluminum species can be utilized as geochemical model compounds
to provide molecular level details of the adsorption process. An Al<sub>30</sub> Keggin-type species with two surface-bound Cu<sup>2+</sup> cations (Cu<sub>2</sub>Al<sub>30</sub>-S) has been crystallized
in the presence of disulfonate anions and structurally characterized
by single-crystal X-ray diffraction. Density functional theory (DFT)
calculations of aqueous molecular analogues for Cu<sub>2</sub>Al<sub>30</sub>-S suggest that the reactivity of Al<sub>30</sub> toward
Cu<sup>2+</sup> and SO<sub>4</sub><sup>2–</sup> shows opposite
trends in preferred adsorption site as a function of particle topology,
with anions preferring the beltway and cations preferring the caps.
The bonding competition was modeled using two stepwise reaction schemes
that consider Cu<sub>2</sub>Al<sub>30</sub>-S formation through initial
Cu<sup>2+</sup> or SO<sub>4</sub><sup>2–</sup> adsorption.
The associated DFT energetics and charge density analyses suggest
that strong electrostatic interactions between SO<sub>4</sub><sup>2–</sup> and the beltway of Al<sub>30</sub> play a vital role
in governing where Cu<sup>2+</sup> binds. The calculated electrostatic
potential of Al<sub>30</sub> provides a theoretical interpretation
of the topology-dependent reactivity that is consistent with the present
study as well as other results in the literature
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