Volatility behavior of oil,industrial commodity and stock markets in a regime-switching environment

This study supplements previous regime-switching studies on WTI crude oil and finds two possible volatility regimes for the strategic commodity prices of Brent oil, WTI oil, copper, gold and silver, and the S&P 500 index, but with varying high-to-low volatility ratios. The dynamic conditional correlations (DCCs) indicate increasing correlations among all the commodities since the 2003 Iraq war but decreasing correlations with the S&P 500 index. The commodities also show different volatility persistence responses to financial and geopolitical crises, while the S&P 500 index responds to both financial and geopolitical crises. Implications are discussed.     

Frequency domain characterization of LoS nonfading indoor wireless LAN channel employing frequency and polarization diversity in the 63.4-65.4 GHz band

This paper presents results of frequency domain measurements conducted to characterize the distortionless transmission bandwidth (DTB) of indoor nonfading channels employing vertically and horizontally polarized antennas in the frequency band 63.4-65.4 GHz. The mean delay spread (/spl tau//sub mean/), root mean square (rms) delay spread (/spl tau//sub rms/), and the DTB of the channel are also presented as functions of distance between terminals and are compared for both polarizations. The dependence of DTB on the separation between terminals d is modeled as DTB=kd/sup -n/ where k is a constant. /spl tau//sub mean/ increases linearly with d, and its relationship with DTB is characterized as DTB=(1//spl alpha//spl tau//sub mean//sup n/)+c, where /spl alpha/ and c are constants. The effectiveness of frequency and polarization diversity in mitigating the effects of multipath fading in indoor channels has also been evaluated. The performance of both diversity techniques when modulated signals with high data rates for multimedia applications are utilized is presented for maximum selection combining. The performance of frequency diversity is also shown as a function of frequency separation between diversity branch signals to determine whether an optimal frequency separation exists.     

Coherence bandwidth measurements in a suburban microcell at 62.4GHz

Results of experiments made at 62.4 GHz to measure the coherence bandwidth in a suburban mobile radio environment are presented. The correlation coefficients between envelopes separated in frequency are measured and expressed as functions of distance from the base station. They are found to be highly variable with the location of the receiver in the microcell. From these data, the frequency correlation function is computed and used to calculate the coherence bandwidth. Values of the coherence bandwidth for correlation levels of 0.5, 0.7 and 0.9 are given for 90% of the time     

Interpolation techniques for building a continuous map from discrete wireless sensor network data

Wireless sensor networks (WSNs) typically gather data at a discrete number of locations. However, it is desirable to be able to design applications and reason about the data in more abstract forms than in points of data. By bestowing the ability to predict inter‐node values upon the network, it is proposed that it will become possible to build applications that are unaware of the concrete reality of sparse data. This interpolation capability is realised as a service of the network. In this paper, the ‘map’ style of presentation has been identified as a suitable sense data visualisation format. Although map generation is essentially a problem of interpolation between points, a new WSN service, called the map generation service, which is based on a Shepard interpolation method, is presented. A modified Shepard method that aims to deal with the special characteristics of WSNs is proposed. It requires small storage, can be localised and integrates the information about the application domain to further reduce the map generation cost and improve the mapping accuracy. Empirical analysis has shown that the map generation service is an accurate, a flexible and an efficient method. Copyright © 2011 John Wiley & Sons, Ltd.     

Conventional and solar cooling systems for Kuwait : An economic analysis

The economics of five cooling systems — two conventional vapour compression systems and three solar (absorption and photovoltaic) cooling systems — are discussed and compared for different occupancies and capacities on the basis of respective life-cycle costs per unit of refrigeration output. The absorption system and the water- and air-cooled photovoltaic systems are assumed to receive equal amounts of conventional electricity. The study concludes that occupancy is a major factor in determining costs per ton-hour and cost per ton of installed capacity for all the cooling systems. At present, no solar cooling system can be considered a viable substitute for the conventional systems. Among all the solar systems considered, the absorption system is the most promising and the cost difference between that system and the conventional systems declines steadily as occupancy increases.     

Structure-based design of novel pyrimido[4,5-c]pyridazine derivatives as dihydropteroate synthase inhibitors with increased affinity

Dihydropteroate synthase (DHPS) is the validated drug target for sulfonamide antimicrobial therapy. However, due to widespread drug resistance and poor tolerance, the use of sulfonamide antibiotics is now limited. The pterin binding pocket in DHPS is highly conserved and is distinct from the sulfonamide binding site. It therefore represents an attractive alternative target for the design of novel antibacterial agents. We previously carried out the structural characterization of a known pyridazine inhibitor in the Bacillus anthracis DHPS pterin site and identified a number of unfavorable interactions that appear to compromise binding. With this structural information, a series of 4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-c]pyridazines were designed to improve binding affinity. Most importantly, the N-methyl ring substitution was removed to improve binding within the pterin pocket, and the length of the side chain carboxylic acid was optimized to fully engage the pyrophosphate binding site. These inhibitors were synthesized and evaluated by an enzyme activity assay, X-ray crystallography, isothermal calorimetry, and surface plasmon resonance to obtain a comprehensive understanding of the binding interactions from structural, kinetic, and thermodynamic perspectives. This study clearly demonstrates that compounds lacking the N-methyl substitution exhibit increased inhibition of DHPS, but the beneficial effects of optimizing the side chain length are less apparent.     

Transient Thermal Response of a Homogeneous Composite Thin Layer Exposed to a Fluctuating Heating Source under the Effect of the Dual-Phase-Lag Heat-Conduction Model

The transient thermal behavior of a homogeneous composite domain described by three macroscopic heat-conduction models, under the effect of a fluctuating heating source, was investigated analytically. The composite domain consists of a matrix (domain 1) and inserts (domain 2), each made of different material. The matrix has a high concentration or volume fraction (>0.5) while the insert has a low concentration or volume fraction (< 0.5). The range of parameters within which the use of the hyperbolic or the dual-phase-lag heat-conduction models is a necessity was traced. The role that the frequency and amplitude of the fluctuating thermal disturbance plays in using the appropriate macroscopic heat-conduction model was studied.     

Structural properties and hyperfine interactions in Co–Zn Y-type hexaferrites prepared by sol–gel method

Y-type barium hexaferrites Ba₂Co_2−xZn_xFe₁₂O₂₂ (0.0≤x≤2.0) were prepared using sol–gel method and then sintering at temperatures between 900 and 1100 °C. The properties of the prepared samples were investigated using X-ray diffraction, scanning electron microscopy, and Mössbauer spectroscopy. XRD patterns revealed the presence of a single Y-type hexaferrite phase in the samples sintered at temperatures above 1000 °C. Mössbauer data indicated that Co²⁺ ions occupied octahedral sites in the T blocks, while Zn²⁺ ions were distributed between the two tetrahedral sites. This trend for cationic distribution resulted in weakening the superexchange interactions between spin-up and spin-down sublattices with increasing Zn content, and a consequent reduction in the hyperfine fields in Zn rich compounds.     

Symmetric and asymmetric US sector return volatilities in presence of oil,financial and economic risks

This paper examines the impacts of world, country, and sector-specific variables on the stock return volatility of twenty-seven US sectors in the short- and long-run, accounting for the asymmetric shocks based on GARCH models. In the standard GARCH model the two world variables, oil and Morgan Stanley Capital Index (MSCI), have differing impacts on the US equity sector returns’ volatility, with oil price dampening it while MSCI heightening it for most sectors. This result underlines the need for hedging more against world capital market risk relative to oil risk which is probably hedged by many sectors. The world and country factors’ impacts are not as pervasive across the board, compared with the sector-specific impacts of the P/B ratio and trading volume which affect almost all sectors. Increases in the P/B ratio would reduce the aggregate volatility, while increases in the trading volume would heighten it for all sectors. Asymmetry of factor impacts on volatility is also found for most sectors. Most of the GARCH factor results are confirmed in the CGARCH model with the exception of the impact of interest rate on the short-lived transitory volatility. Finally, interesting econometric results on the inclusion or exclusion of trading volumes are discussed.     

Scattering cross-section characterisation of vegetation media atmicrowave frequencies

The backscatter signal level emerging from vegetation media and its dependence on the azimuthal direction of the receiving antenna are investigated. Experimental results obtained at 11.2 GHz using two different test sites are presented and further characterised in terms of the scattering cross-section per unit area