Catalogue of candidate emission-line objects in the Small Magellanic Cloud

H\alpha and [O III] narrow band, wide field (7 * 7 degree), CCD images of the Small Magellanic Cloud were compared and a catalogue of candidate planetary nebulae and H\alpha emission-line stars was compiled. The catalogue contains 131 planetary nebulae candidates, 23 of which are already known to be or are probable planetary nebulae or very low excitation objects. Also, 218 emission-line candidates have been identified with 113 already known. Our catalogue therefore provides a useful supplement to those of Meyssonnier & Azzopardi (1993) and Sanduleak, MacConnell & Davis Phillip (1978). Further observations are required to confirm the identity of the unknown objects.Comment: 8 pages, accepted by MNRA

Making Sense Of The New Cosmology

Over the past three years we have determined the basic features of the Universe -- spatially flat; accelerating; comprised of 1/3 a new form of matter, 2/3 a new form of energy, with some ordinary matter and a dash of massive neutrinos; and apparently born from a burst of rapid expansion during which quantum noise was stretched to astrophysical size seeding cosmic structure. The New Cosmology greatly extends the highly successful hot big-bang model. Now we have to make sense of all this: What is the dark matter particle? What is the nature of the dark energy? Why this mixture? How did the matter -- antimatter asymmetry arise? What is the underlying cause of inflation (if it indeed occurred)?Comment: 17 pages Latex (sprocl.sty). To appear in the Proceedings of 2001: A Spacetime Odyssey (U. Michigan, May 2001, World Scientific

X-Ray Eclipse Timing in the LMXB EXO0748-676

Orbital period changes are an important diagnostic for understanding low mass X-ray binary (LMXB) accretion-induced angular momentum exchange and overall system evolution. We present our most recent results for the eclipse timing of the LMXB EXO0748-676. Since its discovery in 1985 it has apparently undergone three distinct orbital period "epochs", each characterized by a different orbital period than the previous epoch. We outline the orbital period behavior for EXO0748-676 over the past 18 years and discuss the implications of this behavior in light of current theoretical ideas for LMXB evolution.Comment: 4 Pages, 3 Figures, Submitted to the X-Ray Timing 2003: Rossi and Beyond conference, November 200

Entropic Stabilization of Tunable Planar Modulated Superstructures

Self-assembling novel ordered structures with nanoparticles has recently received much attention. Here we use computer simulations to study a two-dimensional model system characterized by a simple isotropic interaction that could be realized with building blocks on the nanoscale. We find that the particles arrange themselves into hexagonal superstructures of twin boundaries whose superlattice vector can be tuned reversibly by changing the temperature. Thermodynamic stability is confirmed by calculating the free energy with a combination of thermodynamic integration and the Frenkel-Ladd method. Different contributions to the free energy difference are discussed.Comment: 4 pages, 5 figures plus 7 pages of supplementary figure

Do the new exchange rate indexes offer better answers to old questions?

Foreign exchange rates ; Dollar, American ; International trade

Survey of cometary CO2, CO, and particulate emissions using the Spitzer Space Telescope: Smog check for comets

We surveyed 23 comets using the Infrared Array Camera on the Spitzer Space Telescope in wide filters centered at 3.6 and 4.5 microns. Emission in the 3.6 micron filter arises from sunlight scattered by dust grains; these images generally have a coma near the nucleus and a tail in the antisolar direction due to dust grains swept back by solar radiation pressure. The 4.5 micron filter contains the same dust grains, as well as strong emission lines from CO2 and CO gas; these show distinct morphologies, in which cases we infer they are dominated by gas. Based on the ratio of 4.5 to 3.6 micron brightness, we classify the survey comets as CO2+CO "rich" and "poor." This classification is correlated with previous classifications by A'Hearn based on carbon-chain molecule abundance, in the sense that comets classified as "depleted" in carbon-chain molecules are also "poor" in CO2+CO. The gas emission in the IRAC 4.5 micron images is characterized by a smooth morphology, typically a fan in the sunward hemisphere with a radial profile that varies approximately as the inverse of projected distance from the nucleus, as would apply for constant production and free expansion. There are very significant radial and azimuthal enhancements in many of the comets, and these are often distinct between the gas and dust, indicating that ejection of solid material may be driven either by H2O or CO2. Notable features in the images include the following. There is a prominent loop of gas emission from 103P/Hartley 2, possible due to an outburst of CO2 before the Spitzer image. Prominent, double jets are present in the image of 88P/Howell. A prominent single jet is evident for 3 comets. Spirals are apparent in 29P and C/2006 W3; we measure a rotation rate of 21 hr for the latter comet. Arcs (possibly parts of a spiral) are apparent in the images of 10P/Tempel 2, and 2P/Encke.Comment: accepted for publication in Icaru

Acoustic model adaptation for ortolan bunting (Emberiza hortulana L.) song-type classification

Automatic systems for vocalization classification often require fairly large amounts of data on which to train models. However, animal vocalization data collection and transcription is a difficult and time-consuming task, so that it is expensive to create large data sets. One natural solution to this problem is the use of acoustic adaptation methods. Such methods, common in human speech recognition systems, create initial models trained on speaker independent data, then use small amounts of adaptation data to build individual-specific models. Since, as in human speech, individual vocal variability is a significant source of variation in bioacoustic data, acoustic model adaptation is naturally suited to classification in this domain as well. To demonstrate and evaluate the effectiveness of this approach, this paper presents the application of maximum likelihood linear regression adaptation to ortolan bunting (Emberiza hortulana L.) song-type classification. Classification accuracies for the adapted system are computed as a function of the amount of adaptation data and compared to caller-independent and caller-dependent systems. The experimental results indicate that given the same amount of data, supervised adaptation significantly outperforms both caller-independent and caller-dependent systems

VOLATILITY SPILLOVERS BETWEEN FOREIGN EXCHANGE, COMMODITY AND FREIGHT FUTURES PRICES: IMPLICATIONS FOR HEDGING STRATEGIES

In many studies the assumption is made that traders only encounter one type of price risk. In reality, however, traders are exposed to multiple price risks, and often have several relevant derivative instruments available with which to hedge price uncertainty. In this study, commodity, foreign exchange, and freight futures contracts are analyzed for their effectiveness in reducing price uncertainty for international grain traders. A theoretical model is developed for a representative European importer to depict a realistic trading problem encountered by an international grain trading corporation exposed to more than one type of price risk. The traditional method of estimating hedge ratios by Ordinary Least Squares (OLS) is compared to the Seemingly Unrelated Regression (SUR) and the multivariate GARCH (MGARCH) methodology, which takes into account time-varying variances and covariances between the cash and futures markets. Explicit modeling of the time-variation in futures hedge ratios via the MGARCH methodology, using all derivatives and taking into account dependencies between markets results in a significant reduction in price risk for grain traders. The results also confirm that the unique, but underutilized, freight futures market is a potentially useful mechanism for reducing price uncertainty for international grain traders. The research undertaken in this study provides valuable information about reducing price uncertainty for international grain traders and gives a better understanding of the linkages between closely related markets.hedging, multivariate GARCH, foreign exchange, freight and commodity futures, Financial Economics, International Relations/Trade,