14,896 research outputs found
Persistence in foreign exchange rates: derivation of the multivariate persistence estimates and associated standard errors.
The paper provides a technical discussion on how the multivariate persistence measures described in VandeGucht, Kwok and Dekimpe (1993) can be estimated both when cointegration is present and absent. Procedures to derive the associated asymptotic standard errors are discussed.Foreign exchange; Foreign exchange rates;
Infrared Spectroscopic Study of a Selection of AGB and Post-AGB Stars
We present here near-infrared spectroscopy in the H and K bands of a
selection of nearly 80 stars that belong to various AGB types, namely S type, M
type and SR type. This sample also includes 16 Post-AGB (PAGB) stars. From
these spectra, we seek correlations between the equivalent widths of some
important spectral signatures and the infrared colors that are indicative of
mass loss. Repeated spectroscopic observations were made on some PAGB stars to
look for spectral variations. We also analyse archival SPITZER mid-infrared
spectra on a few PAGB stars to identify spectral features due to PAH molecules
providing confirmation of the advanced stage of their evolution. Further, we
model the SEDs of the stars (compiled from archival data) and compare
circumstellar dust parameters and mass loss rates in different types.
Our near-infrared spectra show that in the case of M and S type stars, the
equivalent widths of the CO(3-0) band are moderately correlated with infrared
colors, suggesting a possible relationship with mass loss processes. A few PAGB
stars revealed short term variability in their spectra, indicating episodic
mass loss: the cooler stars showed in CO first overtone bands and the hotter
ones showed in HI Brackett lines. Our spectra on IRAS 19399+2312 suggest that
it is a transition object. From the SPITZER spectra, there seems to be a
dependence between the spectral type of the PAGB stars and the strength of the
PAH features. Modelling of SEDs showed among the M and PAGB stars that the
higher the mass loss rates, the higher the [K-12] colour in our sample.Comment: 14 pages; accepted in MNRAS, 200
Kwok-Yung Lo
Radio astronomer and physicist Kwok-Yung “Fred” Lo was born on 19 October 1947 in Nanjing, China. The third of six sons, he grew up in Hong Kong, where his father had moved his antique business in 1949 in search of better opportunities. Fred came to the US in 1965 to attend MIT, where he earned his BS in 1969 and a PhD in 1974, both in physics. His thesis, titled “Interstellar microwave radiation and early stellar evolution,” was supervised by radio astronomer Bernard Burke
Pipeline Implementations of Neumann-Neumann and Dirichlet-Neumann Waveform Relaxation Methods
This paper is concerned with the reformulation of Neumann-Neumann Waveform
Relaxation (NNWR) methods and Dirichlet-Neumann Waveform Relaxation (DNWR)
methods, a family of parallel space-time approaches to solving time-dependent
PDEs. By changing the order of the operations, pipeline-parallel computation of
the waveform iterates are possible without changing the final solution. The
parallel efficiency and the increased communication cost of the pipeline
implementation is presented, along with weak scaling studies to show the
effectiveness of the pipeline NNWR and DNWR algorithms.Comment: 20 pages, 8 figure
An appraisal of the marketing of vegetables in Hong Kong.
by Man Kwok Kei.Thesis (M.Comm.)--Chinese University of Hong Kong
Mapping the structural diversity of C60 carbon clusters and their infrared spectra
The current debate about the nature of the carbonaceous material carrying the
infrared (IR) emission spectra of planetary and proto-planetary nebulae,
including the broad plateaus, calls for further studies on the interplay
between structure and spectroscopy of carbon-based compounds of astrophysical
interest. The recent observation of C60 buckminsterfullerene in space suggests
that carbon clusters of similar size may also be relevant. In the present work,
broad statistical samples of C60 isomers were computationally determined
without any bias using a reactive force field, their IR spectra being
subsequently obtained following local optimization with the
density-functional-based tight-binding theory. Structural analysis reveals four
main structural families identified as cages, planar polycyclic aromatics,
pretzels, and branched. Comparison with available astronomical spectra
indicates that only the cage family could contribute to the plateau observed in
the 6-9 micron region. The present framework shows great promise to explore and
relate structural and spectroscopic features in more diverse and possibly
hydrogenated carbonaceous compounds, in relation with astronomical
observations
Analysis: China factory unrest flares as global economy slows - Reuters
This document is part of a digital collection provided by the Martin P. Catherwood Library, ILR School, Cornell University, pertaining to the effects of globalization on the workplace worldwide. Special emphasis is placed on labor rights, working conditions, labor market changes, and union organizing.CLW_2011_Report_China_analysis_china.pdf: 19 downloads, before Oct. 1, 2020
Automated Classification of 2000 Bright IRAS Sources
An Artificial Neural Network (ANN) has been employed using a supervised
back-propagation scheme to classify 2000 bright sources from the Calgary
database of IRAS (Infrared Astronomy Satellite) spectra in the wavelength
region of 8-23 microns. The data base has been classified into 17
pre-determined classes based on spectral morphology. We have been able to
classify more than 80 percent of the 2000 sources correctly at the first
instance. The speed and robustness of the scheme will allow us to classify the
whole of LRS database, containing more than 50,000 sources in the future.Comment: 26 pages, To appear in ApJS after July 200
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