Pulsar Timing with the Fermi LAT

We present an overview of precise pulsar timing using data from the Large Area Telescope (LAT) on Fermi. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. In addition to determining the spindown behavior of the pulsars and detecting glitches and timing noise, such timing analyses allow the precise determination of the pulsar position, thus enabling detailed multiwavelength follow up.Comment: 6 page, 3 figures, to appear in AIP Conference Proceedings of Pulsar Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe", Sardinia, October 201

Calorimeter R&D for the SuperNEMO Double Beta Decay Experiment

SuperNEMO is a next-generation double beta decay experiment based on the successful tracking plus calorimetry design approach of the NEMO3 experiment currently running in the Laboratoire Souterrain de Modane (LSM). SuperNEMO can study a range of isotopes, the baseline isotopes are 82Se and possibly 150Nd. The total isotope mass will be 100-200 kg. A sensitivity to neutrinoless double beta decay half-life greater than 10e26 years can be reached which gives access to Majorana neutrino masses of 50-100 meV. One of the main challenges of the SuperNEMO R&D is the development of the calorimeter with an unprecedented energy resolution of 4% FWHM at 3 MeV (Qbb value of 82Se).Comment: Presented at 13th International Conference on Calorimetry in High Energy Physics (CALOR08), Pavia, Italy, 26-30 May 200

Searching for gravitational waves from the Crab pulsar - the problem of timing noise

Of the current known pulsars, the Crab pulsar (B0531+21) is one of the most promising sources of gravitational waves. The relatively large timing noise of the Crab causes its phase evolution to depart from a simple spin-down model. This effect needs to be taken in to account when performing time domain searches for the Crab pulsar in order to avoid severely degrading the search efficiency. The Jodrell Bank Crab pulsar ephemeris is examined to see if it can be used for tracking the phase evolution of any gravitational wave signal from the pulsar, and we present a method of heterodyning the data that takes account of the phase wander. The possibility of obtaining physical information about the pulsar from comparisons of the electromagnetically and a gravitationally observed timing noise is discussed. Finally, additional problems caused by pulsar glitches are discussed.Comment: 5 pages, 1 figure, Proceedings of the 5th Amaldi Conference on Gravitational Waves, Pisa, Italy, 6-11 July 200

Network Externalities, Mutuality, and Compatibility

Positive network externalities can arise when consumers benefit from the consumption of compatible products by other consumers (user-positive consumption externalities) or, alternatively, when they incur costs from the consumption of incompatible products by other consumers (nonuser-negative consumption externalities). But whereas user-positive externalities are typically mutually imposed and imply mutual benefit because they relate to interoperability, with nonuser-negative externalities the costs of incompatibility may be imposed unilaterally and borne asymmetrically. For example, increased risks of death and injury on the roads due to the co-existence of large and small vehicles are imposed exclusively by the owners of the large vehicles and borne exclusively by the occupants of the small vehicles. This paper compares the social optimality of incentives for compatibility under regimes involving user-positive and nonuser-negative externalities. Earlier work with respect to user-positive externalities (e.g., Katz and Shapiro, 1985) suggests that firms with relatively small networks or weak reputations tend to be biased in favor of compatibility, while individual firms’ incentives for compatibility are suboptimal when their networks are closely matched in size. Meanwhile, intuition suggests that with nonuser-negative externalities incentives for incompatibility should always be excessive, reflecting the notion that activities involving unilaterally imposed negative externalities will always be overprovided by the market (in the absence of regulation or Coaseian mitigation). Using a "location" model of differentiated products, we find that, under both regimes, incentives for compatibility tend to be suboptimal when firms' networks are close in size, and excessive for the small firm when the networks differ greatly in size. Surprising public policy implications with respect to externalities are discussed

A quasi-real-time ground-based trajectory optimization tool for greener operations

This paper describes the methodology adopted in designing a quasi-real-time ground-based trajectory optimization tool for use by air traffic control officers. The tool is primarily intended for the optimization of aircraft trajectories during the climb and descent phases in which the user can define the trajectory in four dimensions. The optimized trajectories would then contribute to a reduction in fuel burn and emissions. The designed tool takes into account different aircraft types and sub-types through BADA performance and engine coefficients. A simple case study for an approach in Malta International Airport has also been presented to illustrate the use of the tool.peer-reviewe

Impurity transport in Alcator C-Mod in the presence of poloidal density variation induced by ion cyclotron resonance heating

Impurity particle transport in an ion cyclotron resonance heated Alcator C-Mod discharge is studied with local gyrokinetic simulations and a theoretical model including the effect of poloidal asymmetries and elongation. In spite of the strong minority temperature anisotropy in the deep core region, the poloidal asymmetries are found to have a negligible effect on the turbulent impurity transport due to low magnetic shear in this region, in agreement with the experimental observations. According to the theoretical model, in outer core regions poloidal asymmetries may contribute to the reduction of the impurity peaking, but uncertainties in atomic physics processes prevent quantitative comparison with experiments.Comment: 32 pages, 12 figure

IVOA Recommendation: VOResource: an XML Encoding Schema for Resource Metadata Version 1.03

This document describes an XML encoding standard for IVOA Resource Metadata, referred to as VOResource. This schema is primarily intended to support interoperable registries used for discovering resources; however, any application that needs to describe resources may use this schema. In this document, we define the types and elements that make up the schema as representations of metadata terms defined in the IVOA standard, Resource Metadata for the Virtual Observatory [Hanicsh et al. 2004]. We also describe the general model for the schema and explain how it may be extended to add new metadata terms and describe more specific types of resources

The edges of galaxies in the Fornax Cluster: Fifty percent smaller and denser compared to the field

Physically motivated measurements are crucial for understanding galaxy growth and the role of the environment on their evolution. In particular, the growth of galaxies as measured by their size or radial extent provides an empirical approach for addressing this issue. However, the established definitions of galaxy size used for nearly a century are ill-suited for these studies because of a previously ignored bias. The conventionally-measured radii consistently miss the diffuse, outer extensions of stellar emission which harbour key signatures of galaxy growth, including star formation and gas accretion or removal. This issue is addressed by examining low surface brightness truncations or galaxy "edges" as a physically motivated tracer of size based on star formation thresholds. Our total sample consists of $\sim900$ galaxies with stellar masses ranging from $10^5 M_{\odot} < M_{\star} < 10^{11} M_{\odot}$. This sample of nearby cluster, group satellite and nearly isolated field galaxies was compiled using multi-band imaging from the Fornax Deep Survey, deep IAC Stripe 82 and Dark Energy Camera Legacy Surveys. Across the full mass range studied, we find that compared to the field, the edges of galaxies in the Fornax Cluster are located at 50% smaller radii and the average stellar surface density at the edges are two times higher. These results are consistent with the rapid removal of loosely bound neutral hydrogen (HI) in hot, crowded environments which truncates galaxies outside-in earlier, preventing the formation of more extended sizes and lower density edges. In fact, we find that galaxies with lower HI fractions have edges with higher stellar surface density. Our results highlight the importance of deep imaging surveys to study the low surface brightness imprints of the large scale structure and environment on galaxy evolution.Comment: 22 pages, 12 figures, 2 tables, submitted to A&A after LSST DESC internal and collaboration wide review (see acknowledgements). Example galaxies in Figs. 2, 5 and 6. Key results in Figs. 7, 8, 11 and 1