503 research outputs found
"An Econometric Analysis of SARS and Avian Flu on International Tourist Arrivals to Asia"
This paper compares the impacts of SARS and human deaths arising from Avian Flu on international tourist arrivals to Asia. The effects of SARS and human deaths from Avian Flu will be compared directly according to human deaths. The nature of the short run and long run relationship is examined empirically by estimating a static line fixed effect model and a difference transformation dynamic model, respectively. Empirical results from the static fixed effect and difference transformation dynamic models are consistent, and indicate that both the short run and long run SARS effect have a more significant impact on international tourist arrivals than does Avian Flu. In addition, the effects of deaths arising from both SARS and Avian Flu suggest that SARS is more important to international tourist arrivals than is Avian Flu. Thus, while Avian Flu is here to stay, its effect is currently not as significant as that of SARS.
Absorption Cross Sections of NH_3, NH_2D, NHD_2, and ND_3 in the Spectral Range 140-220 nm and Implications for Planetary Isotopic Fractionation
Cross sections for photoabsorption of NH_3, NH_2D, NHD_2, and ND_3 in the spectral region 140-220 nm were determined at ~298 K using synchrotron radiation. Absorption spectra of NH_2D and NHD_2 were deduced from spectra of mixtures of NH_3 and ND_3, of which the equilibrium concentrations for all four isotopologues obey statistical distributions. Cross sections of NH_2D, NHD_2, and ND_3 are new. Oscillator strengths, an integration of absorption cross sections over the spectral lines, for both A ← X and B ← X systems of NH_3 agree satisfactorily with previous reports; values for NH_2D, NHD_2, and ND_3 agree with quantum chemical predictions. The photolysis of NH_3 provides a major source of reactive hydrogen in the lower stratosphere and upper troposphere of giant planets such as Jupiter. Incorporating the measured photoabsorption cross sections of NH_3 and NH_2D into the Caltech/JPL photochemical diffusive model for the atmosphere of Jupiter, we find that the photolysis efficiency of NH_2D is lower than that of NH_3 by as much as 30%. The D/H ratio in NH_2D/NH_3 for tracing the microphysics in the troposphere of Jupiter is also discussed
Traffic agents for improving QoS in mixed infrastructure and ad hoc modes wireless LAN
As an important complement to infrastructured wireless networks, mobile ad hoc networks (MANET) are more flexible in providing wireless access services, but more difficult in meeting different quality of service (QoS) requirements for mobile customers. Both infrastructure and ad hoc network structures are supported in wireless local area networks (WLAN), which can offer high data-rate wireless multimedia services to the mobile stations (MSs) in a limited geographical area. For those out-of-coverage MSs, how to effectively connect them to the access point (AP) and provide QoS support is a challenging issue. By mixing the infrastructure and the ad hoc modes in WLAN, we propose in this paper a new coverage improvement scheme that can identify suitable idle MSs in good service zones as traffic agents (TAs) to relay traffic from those out-of-coverage MSs to the AP. The service coverage area of WLAN is then expanded. The QoS requirements (e.g., bandwidth) of those MSs are considered in the selection process of corresponding TAs. Mathematical analysis, verified by computer simulations, shows that the proposed TA scheme can effectively reduce blocking probability when traffic load is light
Isotopic Fractionation of Nitrogen in Ammonia in the Troposphere of Jupiter
Laboratory measurements of the photoabsorption cross section of ^(15)NH_3 at wavelengths between 140 and 220 nm are presented for the first time. Incorporating the measured photoabsorption cross sections of ^(15)NH_3 and ^(14)NH_3 into a one-dimensional photochemical diffusive model, we find that at 400 mbar, the photolytic efficiency of ^(15)NH_3 is about 38% greater than that of ^(14)NH_3. In addition, it is known that ammonia can condense in the region between 200 and 700 mbar, and the condensation tends to deplete the abundance ratio of ^(15)NH_3 and ^(14)NH_3. By matching the observed ratio of ^(15)NH_3 and ^(14)NH_3 at 400 mbar, the combined effect of photolysis and microphysics produces the ratio of (2.42 ± 0.34) × 10^(-3) in the deep atmosphere, in excellent agreement with the Galileo spacecraft measurements. The usefulness of the isotopic composition of ammonia as a tracer of chemical and dynamical processes in the troposphere of Jupiter is discussed
An econometric analysis of SARS and Avian flu on international tourist arrivals to Asia
This paper compares the impacts of SARS and human deaths arising from Avian Flu on international tourist arrivals to Asia. The effects of SARS and human deaths from Avian Flu will be compared directly according to human deaths. The nature of the short run and long run relationship is examined empirically by estimating a static line fixed effect model and a difference transformation dynamic model, respectively. Empirical results from the static fixed effect and difference transformation dynamic models are consistent, and indicate that both the short run and long run SARS effect have a more significant impact on international tourist arrivals than does Avian Flu. In addition, the effects of deaths arising from both SARS and Avian Flu suggest that SARS is more important to international tourist arrivals than is Avian Flu. Thus, while Avian Flu is here to stay, its effect is currently not as significant as that of SARS
How do Agency Problems Affect the Implied Cost of Capital?
We test the relationship between the implied cost of capital and two agency problems, free cash flows and overinvestment. We show that free cash flows have a significant negative impact on the implied cost of capital, but overinvestment has a significantly positive impact. In addition, the pay-for-performance sensitivity has a negative effect but the sensitivity of volatility has a significantly positive effect on the implied cost of capital. After taking the incentives into account, we find that the significance of the impact from both agency problems still exists. Finally, we conclude that well-designed executive compensation should focus on reducing overinvestment and the sensitivity of volatility
Analysis of debris flow underground sound by wavelet transform - a case study of events in aiyuzih river
Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have successively carried out the establishment and maintenance of 17 debris flow monitoring stations over the Taiwan and 3 mobile debris flow monitoring stations. Geophone is one of the most important sensor to detect whether debris flow occur or not. The wavelet transform is employed in this study to analyze the underground sound of debris flows obtained from the geophones. Three debris flow events observed at Shenmu monitoring station (Nantou County) on July 2, 2004 and on August 8, 2009 are selected as examples. It is found that the wavelet transform not only can separate ambient noise effectively but also can be used to determine the beginning time of debris flow event. In order to estimate the magnitude of debris flow event, a so-called wavelet accumulated energy indicator is proposed. When debris flow occurs, the wavelet accumulated energy will increase. So the wavelet accumulated energy’s threshold value is double of normal value. It can be used to determine the occurrence of debris flow and to estimate its magnitude
The present development of debris flow monitoring technology in Taiwan – A Case study presentation
In order to document the on-site debris flow events, the Soil and Water Conservation Bureau (SWCB), Council of Agriculture, Taiwan, has devoted to develop the debris flow monitoring system since 2002. This paper introduces the technology of 17 on-site and 3 mobile debris flow monitoring stations established by SWCB in Taiwan. In each on-site monitoring station, several observation instruments including rain gauges, CCD cameras, wire sensors, geophones, and water level meters were installed to collect the dynamic debris flow information that can be used as the references for countermeasures of debris flow disaster mitigation. Besides, several meteorological sensors are also adopted recently in order to record the long-term climate change effects on the slopeland of Taiwan. The framework of the debris flow monitoring system consists of monitoring sensors, instrumental cabin (vehicle platform for mobile station), transmission system and web-based display system. During the typhoon Mindulle period in 2004, a debris flow event in Aiyuzih creek was observed by the Shenmu debris flow monitoring station on July 2, Nantou County, central Taiwan. On-site observation data including the rainfall patterns, video images, wire sensor ruptures and ground vibrations caused by debirs-flows are analyzed in detail
Vacuum-Ultraviolet Absorption Spectra of Icy C2H4 at 13–60 K
The thermal variation of absorption spectra of icy ethene in wavelength range 105–220 nm was measured from 13 to 100 K using a synchrotron as light source. Sublimation of icy ethene began above 62 K, resulting in decreasing absorption. The absorption of icy ethene increased at wavelengths less than about 150 nm with increasing temperature from 13 to 60 K, but decreased beyond above 150 nm. According to detailed examination, the absorption spectra of icy ethene intersected at isosbestic point 147.0 nm from 13 to 17 K, whereas those varied absorption profiles crossed at another point, 150.6 nm, from 23 to 60 K. These results indicate that ethene ices might exhibit three structures within temperature range 13–60 K. This work enhances our understanding of the spectra of icy ethene at low temperatures and our knowledge of its astrochemistry and astrophysics in cold astro-environments
Association Between Mid-arm Muscle Circumference and Cognitive Function: A Longitudinal Study of Chinese Adults
Background Dementia affects 55 million people worldwide and low muscle mass may be associated with cognitive decline. Mid-arm muscle circumference (MAMC) correlates with dual-energy Xray absorptiometry and bioelectrical impedance analyses, yet are not routinely available. Therefore, we examined the association between MAMC and cognitive performance in older adults. Methods We included community-dwelling adults ≥55 years from the China Health and Nutrition Survey. Cognitive function was estimated based on a subset of the modified Telephone Interview for Cognitive Status (0-27, low-high) during years (1991, 1993, 1997, 2000, 2004, 2006, 2009, 2011, 2015, 2018). A multivariable linear mixed-effects model was used to test whether MAMC was associated with rate of cognitive decline across age groups and cognitive function overall. Results Of 3702 adults (53% female, 63.2 ± 7.3 years), mean MAMC was 21.4 cm ± 3.0 and baseline cognitive score was 13.6 points ±6.6. We found no evidence that the age-related rate of cognitive decline differed by MAMC (P = .77). Declines between 5-year age groups ranged from −.80 [SE (standard error) .18] to −1.09 [.22] for those at a mean MAMC, as compared to −.86 [.25] to −1.24 [.31] for those at a 1 MAMC 1 standard deviation above the mean. Higher MAMC was associated with better cognitive function with .13 [.06] higher scores for each corresponding 1 standard deviation increase in MAMC across all ages. Conclusion Higher MAMC at any age was associated with better cognitive performance in older adults. Understanding the relationship between muscle mass and cognition may identify at-risk subgroups needing targeted interventions to preserve cognition
- …
