Frequency Space Correlation Between REITs and Capital Market Indices

Several studies have examined real estate investment trust (REIT) co-movement with stocks or bonds using traditional time domain based methods, such as linear regression or correlation. Results of these studies have produced inconsistent statistical model parameters. The erratic behavior of the models may have resulted from the different time periods in the studies, the REITs included in a study or the market indices. Another factor contributing to the variation of the models comes from the compression of cyclical information over a study?s time period by time domain based techniques. Cross-spectral analysis provides a frequency space method of examining the coherency (i.e., frequency space correlation) between two time series across all frequencies. This article contains an examination of the coherency between REITs and stock market indices and REITs and U.S. Treasury debt indices for the period 1989-95. Results of the coherency spectra show significant co-movement between REITs and stock market indices, while debt instruments show very few frequencies with significant coherency. Furthermore, phase spectra provide evidence of contemporaneous movement between REITs and stock indices at all frequencies.

Volcanic thermal features observed by AVIRIS

In July 1991, Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was flown over Mount Etna and Stromboli, Italy. Lava-filled vents were then present within summit craters of both volcanoes. Since surfaces at magmatic temperatures radiate strongly over the wavelength ranges of the AVIRIS C- and D-spectrometers, it was hoped that the data collected would reveal clear thermal signatures, even of sub-pixel sized features, as have been observed in the 1.65 and 2.22 microns bands of Landsat Thematic Mapper images. This would provide an opportunity to explore the potential of imaging spectrometers for deriving temperature distributions of hot volcanic surfaces. Such research has implications for volcano monitoring in the EOS era, and also for any future AVIRIS deployments above active lava flows, lakes, and domes, where understanding of their behavior may be advanced by detailed thermal observations

Climate change and postglacial human dispersals in southeast Asia

Modern humans have been living in Island Southeast Asia (ISEA) for at least 50,000 years. Largely because of the influence of linguistic studies, however, which have a shallow time depth, the attention of archaeologists and geneticists has usually been focused on the last 6,000 years--in particular, on a proposed Neolithic dispersal from China and Taiwan. Here we use complete mitochondrial DNA (mtDNA) genome sequencing to spotlight some earlier processes that clearly had a major role in the demographic history of the region but have hitherto been unrecognized. We show that haplogroup E, an important component of mtDNA diversity in the region, evolved in situ over the last 35,000 years and expanded dramatically throughout ISEA around the beginning of the Holocene, at the time when the ancient continent of Sundaland was being broken up into the present-day archipelago by rising sea levels. It reached Taiwan and Near Oceania more recently, within the last approximately 8,000 years. This suggests that global warming and sea-level rises at the end of the Ice Age, 15,000-7,000 years ago, were the main forces shaping modern human diversity in the region

Thermal structure of a gas-permeable lava dome and timescale separation in its response to perturbation

The thermal boundary layer at the surface of a volcanic lava dome is investigated through a continuum model of the thermodynamic advection diffusion processes resulting from magmatic gas flow through the dome matrix. The magmatic gas mass flux, porosity and permeability of the rock are identified as key parameters. New, theoretical, nonlinear steady-state thermal profiles are reported which give a realistic surface temperature of 210 degC for a region of lava dome surface through which a gas flux of 3.5 x 10-3 kg s-1 m-2 passes. This contrasts favourably with earlier purely diffusive thermal models, which cool too quickly. Results are presented for time-dependent perturbations of the steady states as a response to: changes in surface pressure, a sudden rockfall from the lava dome surface, and a change in the magmatic gas mass flux at depth. Together with a generalized analysis using the method of multiple scales, this identifies two characteristic time scales associated with the thermal evolution of a dome carapace: a short time scale of several minutes, over which the magmatic gas mass flux, density, and pressure change to a new quasi-steady-state, and a longer time scale of several days, over which the thermal profile changes to a new equilibrium distribution. Over the longer time scale the dynamic properties of the dome continue to evolve, but only in slavish response to the ongoing temperature evolution. In the light of this time scale separation, the use of surface temperature measurements to infer changes in the magmatic gas flux for use in volcanic hazard prediction is discussed

Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type Ia Supernova

We have measured the rest-frame B,V, and I-band light curves of a high-redshift type Ia supernova (SN Ia), SN 1999Q (z=0.46), using HST and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, E_{B-I}, which is a sensitive indicator of interstellar or intergalactic dust which could affect recent cosmological measurements from high-redshift SNe Ia. Our observations disfavor a 30% opacity of SN Ia visual light by dust as an alternative to an accelerating Universe. This statement applies to both Galactic-type dust (rejected at the 3.4 sigma confidence level) and greyer dust (grain size > 0.1 microns; rejected at the 2.3 to 2.6 sigma confidence level) as proposed by Aguirre (1999). The rest-frame $I$-band light cur ve shows the secondary maximum a month after B maximum typical of nearby SNe Ia of normal luminosi ty, providing no indication of evolution as a function of redshift out to z~0.5. A n expanded set of similar observations could improve the constraints on any contribution of extragalactic dust to the dimming of high-redshift SNe Ia.Comment: Accepted to the Astrophysical Journal, 12 pages, 2 figure

Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment - exoplanets and disks - detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, we will review the current state of the art, by presenting world record contrasts obtained in the framework of technological demonstrations for space-based exoplanet imaging and characterization mission concepts. Finally, we will conclude by emphasizing the importance of the cross-breeding between techniques developed for both ground-based and space-based projects, which is relevant for future high contrast imaging instruments and facilities in space or on the ground.Comment: 21 pages, 7 figure

Aperture Mask Interferometry with an Integral Field Spectrograph

A non-redundant pupil mask placed in front of a low-resolution integral field spectrograph (IFS) adds a spectral dimension to high angular resolution imaging behind adaptive optics systems. We demonstrate the first application of this technique, using the spectroscopic binary star system β CrB as our target. The mask and IFS combination enabled us to measure the first low-resolution spectrum of the F3-F5 dwarf secondary component of β CrB, at an angular separation 141 mas from its A5-A7Vp primary star. To record multi-wavelength closure phases, we collected interferograms simultaneously in 23 spectral channels spanning the J and H bands (1.1 μm-1.8 μm), using the Project 1640 IFS behind the 249-channel PalAO adaptive optics system on the Hale telescope at Palomar Observatory. In addition to providing physical information about the source, spectrally resolved mask fringes have the potential to enhance detection limits over single filter observations. While the overall dynamic range of our observation suffers from large systematic calibration errors, the information gleaned from the full channel range improves the dynamic range by a factor of 3 to 4 over the best single channel