Excess Returns in the Hong Kong Commercial Real Estate Market

This study examines the existence of excess returns of the office, retail and industrial real estate sectors in Hong Kong using time series of both valuations and transaction prices. The analysis covers the period from 1980 to 1995. If valuations are an accurate reflection of transaction prices then excess returns, if they exits, should be detected in both series. Our findings confirm that excess returns can be detected in both valuation and transaction-based series. They are not, however, persistent although there appear to be greater opportunities for earning excess returns in the office sector.

CONCENTRATION OF CO, IN THE AIR ABOVE A SUGAR BEET FIELD

The concentration of CO, in air sampled above a sugar beet crop was measured during July, August, and early September 1966 at Scottsbluff, Nebr. During July the mean daytime concentration decreased from 310 ppm to 283 ppm as the leaf area index increased from 0.8 to 4.0. Only small deviations from the mean daytime Concentration of 283 ppm occurred during the remainder of the season. The mean nocturnal concentration during this period was 320 ppm and was more variable than the daytime concentration. The daily amplitude of concentration averaged 70 ppm and was as great at times as 100 ppm. Regression analysis revealed strong negative correlation between COZ concentration and mean wind speed during the night. Mean concentration was independent of mean temperature, mean incident radiation, and predominant wind direction. During each day the concentration remained constant between 1% hr after sunrise and 1 hr before sunset except for a few cases. These were associated with incident radiation below 0.2 cal cm-2 min-1 and/or wind speeds at 25 cm above the crop of less than 0.3 m sec-l or more than 3 m sec-I. Evidence is presented that the concentrations reported here are at least partially dependent on the flux to and from the sugar beet crop

Comparison of Momentum and Energy Balance Methods of Computing Vertical Transfer Within a Crop

Measurements of windspeed, air temperature, wet-bulb depression, and net radiation were made at several levels within and above the crop. Soil heat flux and incident radiation were also measured. Transfer coefficient distributions were computed separately from the windspeed data by a momentum balance approach, and from the other data by the energy balance method. The agreement between the two methods was better near the top of the crop than near the soil. Drag coefficients computed from the energy balance results were not independent of height within the crop as was assumed in the momentum balance analysis. The low Reynolds numbers for the lower portion of the crop could account for the deviation. The energy balance approach required more measurements but was easier to apply in calculating the distribution of the transfer coefficient for the computation of the vertical flux of such entities as heat, water vapor, and carbon dioxide within the crop

The response to high magnetic fields of the vacuum phototriodes for the compact muon solenoid endcap electromagnetic calorimeter

The endcap electromagnetic calorimeter of the Compact Muon Solenoid (CMS) detects particles with the dense fast scintillator lead tungstate (PbWO4). Due to the low light yield of this scintillator photodetectors with internal gain are required. Silicon avalanche photodiodes cannot be used in the endcap region due to the intense neutron flux. Following an extensive R&D programme 26 mm diameter single-stage photomultipliers (vacuum phototriodes) have been chosen as the photodetector in the endcap region. The first 1400 production devices are currently being evaluated following recent tests of a pre-production batch of 500 tubes. Tubes passing our acceptance tests have responses, averaged over the angular acceptance of the endcap calorimeter, corresponding to the range 20 to 55 electrons per MeV deposited in PbWO4. These phototriodes operate, with a typical gain of 10, in magnetic fields up to 4T.PPARC, EC(INTAS-CERN scheme 99-424

Vacuum polarization in two-dimensional static spacetimes and dimensional reduction

We obtain an analytic approximation for the effective action of a quantum scalar field in a general static two-dimensional spacetime. We apply this to the dilaton gravity model resulting from the spherical reduction of a massive, non-minimally coupled scalar field in the four-dimensional Schwarzschild geometry. Careful analysis near the event horizon shows the resulting two-dimensional system to be regular in the Hartle-Hawking state for general values of the field mass, coupling, and angular momentum, while at spatial infinity it reduces to a thermal gas at the black-hole temperature.Comment: REVTeX 4, 23 pages. Accepted by PRD. Minor modifications from original versio

Analytical approximation of the stress-energy tensor of a quantized scalar field in static spherically symmetric spacetimes

Analytical approximations for ${}$ and ${}$ of a quantized scalar field in static spherically symmetric spacetimes are obtained. The field is assumed to be both massive and massless, with an arbitrary coupling $\xi$ to the scalar curvature, and in a zero temperature vacuum state. The expressions for ${}$ and ${}$ are divided into low- and high-frequency parts. The contributions of the high-frequency modes to these quantities are calculated for an arbitrary quantum state. As an example, the low-frequency contributions to ${}$ and ${}$ are calculated in asymptotically flat spacetimes in a quantum state corresponding to the Minkowski vacuum (Boulware quantum state). The limits of the applicability of these approximations are discussed.Comment: revtex4, 17 pages; v2: three references adde

Acute and Genetic Toxicity of Municipal Landfill Leachate

Municipal solid waste (MSW) landfills have been found to contain many of the same hazardous constituents as found in hazardous waste landfills. Because of the large number of MSW landfills, these sites pose a serious environmental threat to groundwater quality. This study was conducted to assess the environmental hazards that materials leaching from four MSW landfills pose to groundwater supplies. Four leachate and one upgradient groundwater samples were collected from landfills selected to be representative of landfills of differing ages and types of wastes. Each sample was tested through three genetic toxicity bioassays (The Aspergillus diploid assay, the Bacillus DNA repair assay and the Salmonella/microsome assay) to measure the ability of each sample to induce mutations in bacteria, bind to microbial DNA, or cause chromosome damage in diploid fungi. Genetically toxic chemicals may cause cancer, genetic disease, sterility, abortions, heart disease or a variety of other chronic effects. These chronic effects can be subtle and may not appear for decades after exposure. In addition to the three genetic toxicity assays, each sample was tested in the Microtox test to measure acute toxicity. This assay is a measure of the ability of the sample to cause cell death. Organisms exposed to elevated levels of acute toxins may express the toxic effects through organ disfunction or the complete death of the organism. Each sample was chemically analyzed using GC/MS techniques and the chemical concentrations were used to calculate a chemical based risk assessment which is an estimate of the potential carcinogenic health effects associated with the mixture of chemicals in the sample. All four leachate samples exhibited acute toxicity in the Microtox test. Leachate from landfills representative of both an old unlined landfill which received residential waste and a new operating landfill receiving residential waste contained concentrations of some priority pollutants in excess of promulgated standards for drinking water. Chemical based risk assessments for these same two leachates showed them to have mean and 98th percentile cancer risks of 1 in a thousand (10-3) which is greater than both leachate from a Superfund landfill and leachate from the Love Canal landfill. The results of the acute and genetic toxicity bioassays, combined with the chemical analyses and associated cancer risk assessment clearly showed that leachate from municipal solid waste landfills is just as toxic as that which leaches from landfills where residential and hazardous wastes were codisposed

Breakdown of Particle-Hole Symmetry in the Lowest Landau Level Revealed by Tunneling Spectroscopy

Tunneling measurements on 2D electron gases at high magnetic field reveal a qualitative difference between the two spin sublevels of the lowest Landau level. While the tunneling current-voltage characteristic at filling factor $\nu = 1/2$ is a single peak shifted from zero bias by a Coulomb pseudogap, the spectrum at $\nu=3/2$ shows a well-resolved double peak structure. This difference is present regardless of whether $\nu =1/2$ and $\nu = 3/2$ occur at the same or different magnetic fields. No analogous effect is seen at $\nu = 5/2$ and 7/2 in the first excited Landau level.Comment: 5 pages, 4 figure

Structural characterisation of MBE grown zinc-blende Ga1-xMnxN/GaAs(001) as a function of Ga flux

Ga1-xMnxN films grown on semi-insulating GaAs(001) substrates at 680°C with fixed Mn flux and varied Ga flux demonstrated a transition from zinc-blende/wurtzite mixed phase growth for low Ga flux (N-rich conditions) to zinc-blende single phase growth with surface Ga droplets for high Ga flux (Ga-rich conditions). N-rich conditions were found favourable for Mn incorporation in GaN lattice. α-MnAs inclusions were identified extending into the GaAs buffer layer

Method to compute the stress-energy tensor for the massless spin 1/2 field in a general static spherically symmetric spacetime

A method for computing the stress-energy tensor for the quantized, massless, spin 1/2 field in a general static spherically symmetric spacetime is presented. The field can be in a zero temperature state or a non-zero temperature thermal state. An expression for the full renormalized stress-energy tensor is derived. It consists of a sum of two tensors both of which are conserved. One tensor is written in terms of the modes of the quantized field and has zero trace. In most cases it must be computed numerically. The other tensor does not explicitly depend on the modes and has a trace equal to the trace anomaly. It can be used as an analytic approximation for the stress-energy tensor and is equivalent to other approximations that have been made for the stress-energy tensor of the massless spin 1/2 field in static spherically symmetric spacetimes.Comment: 34 pages, no figure