Scattering of Pruppacher-Pitter raindrops at 30 GHz

Optimum design of modern ground-satellite communication systems requires the knowledge of rain-induced differential attenuation, differential phase shift, and cross polarization factors. Different available analytical techniques for raindrop scattering problems were assessed. These include: (1) geometrical theory of diffraction; (2) method of moment; (3) perturbation method; (4) point matching methods; (5) extended boundary condition method; and (6) global-local finite element method. The advantages and disadvantages of each are listed. The extended boundary condition method, which was determined to yield the most scattering results, is summarized. The scattered fields for Pruppacher-Pitter raindrops with sizes ranging from 0.5 mm to 3.5 mm at 20 C and at 30 GHz for several incidence angles are tabulated

Fiber-diffraction Interferometer using Coherent Fiber Optic Taper

We present a fiber-diffraction interferometer using a coherent fiber optic taper for optical testing in an uncontrolled environment. We use a coherent fiber optic taper and a single-mode fiber having thermally-expanded core. Part of the measurement wave coming from a test target is condensed through a fiber optic taper and spatially filtered from a single-mode fiber to be reference wave. Vibration of the cavity between the target and the interferometer probe is common to both reference and measurement waves, thus the interference fringe is stabilized in an optical way. Generation of the reference wave is stable even with the target movement. Focus shift of the input measurement wave is desensitized by a coherent fiber optic taper

A geographical study of health services utilization among elderly in Hong Kong: from spatial variations to health care implications

Introduction: Levels of utilization of health services vary socially and geographically. Differences in the rates of usage are also associated with geographical aspects of health care systems. The purpose of this study was to capture spatial variations in hospital health services utilization in the elderly population in Hong Kong, a Special Administrative Region of China. Materials and Methods: We carried out a secondary analysis of a database from the Hospital Authority (HA) which covers 98% (N = 243,245) of the total registered deaths in Hong Kong during 1999 to 2005. Deaths at age 65y and above (N = 184,671) were included in the analysis. Age-sex weighted mean utilization ratio of hospital services was calculated by dividing the age-sex weighted mean usage of a particular service for each district by that for the whole territory. The variation in utilization by the seniors was analyzed in terms of four types of services: length of stay (LOS) in HA hospitals, number of inpatient admissions, number of visits to specialist outpatient department (SOPD), and attendances at accident and emergency department (AED). Results: Deaths at age 65y and above contributed to 76% of the total registered deaths. Each district contributed 1.0% to 9.1% of the total number of deaths in Hong Kong. Spatial analysis of the age-sex weighted mean utilization ratio showed significant geographic variation in the use of hospital services: the range of difference in the LOS between the lowest and highest district was 44%, while some differences as high as 33%, 35% and 39% in utilization ratios were observed in relation to number of inpatient admissions, visits to SOPD, and attendances at AED respectively. However, the patterns of these variations were not consistent for the four types of service being analyzed. Conclusions: Geographic variation in the utilization of hospital health services across the 18 districts in Hong Kong among the elderly population during the last three years before death was demonstrated. However, the patterns of variation were different for the types of services being examined. Further studies using primary data at an individual level are needed to explain the variations. Detailed analysis examining the relationship between service provision, accessibility and health outcomes are also indicated in order to inform the planning of health service delivery.published_or_final_versio

Bell inequality for pairs of particle-number-superselection-rule restricted states

Proposals for Bell inequality tests on systems restricted by superselection rules often require operations that are difficult to implement in practice. In this paper, we derive a new Bell inequality, where pairs of states are used to by-pass the superselection rule. In particular, we focus on mode entanglement of an arbitrary number of massive particles and show that our Bell inequality detects the entanglement in the pair when other inequalities fail. However, as the number of particles in the system increases, the violation of our Bell inequality decreases due to the restriction in the measurement space caused by the superselection rule. This Bell test can be implemented using techniques that are routinely used in current experiments.Comment: 9 pages, 6 figures; v2 is the published versio

Detection of volatile organic compounds (VOCs) using an optical fibre long period grating with a calixarene anchored mesoporous thin film

A long period grating (LPG) modified with a mesoporous film infused with a functional compound, calix[4]arene, was employed for the detection of volatile organic compounds (VOCs). The mesoporous film consisted of an inorganic part, of SiO2 nanoparticles (NPs) along with an organic moiety of poly(allylamine hydrochloride) polycation PAH, which was finally infused with functional compound, p-sulphanatocalix[4]arene (CA[4]). The LPG sensor was designed to operate at the phase matching turning point to provide the highest sensitivity. The sensing mechanism is based on the measurement of the refractive index (RI) change induced by the complexion of the VOCs with calix[4]arene (CA). The LPG modified with 5 cycles of (SiO2 NPs/PAH)5PAA responded to exposure to chloroform and benzene vapours. The sensitivity to humidity as an interfering parameter was also investigated

Chemical Abundance Study of One Red Giant Star in NGC 5694 : A Globular Cluster with Dwarf Spheroidals' Chemical Signature?

We report the abundance analysis of one red giant branch star in the metal-poor outer halo globular cluster NGC 5694. We obtain [Fe/H] = -1.93, based on the ionized lines, and our metallicity measurement is in good agreement with previous estimates. We find that [Ca+Ti/2Fe] and [Cu/Fe] of NGC 5694 are about 0.3 -- 0.4 dex lower than other globular clusters with similar metallicities, but similar to some LMC clusters and stars in some dwarf spheroidal galaxies. Differences persist, however, in the abundances of neutron capture elements. The unique chemical abundance pattern and the large Galactocentric distance (30 kpc) and radial velocity (-138.6 +/- 1.0 km/sec) indicate that NGC 5694 had an extragalactic origin.Comment: ApJL accepte

Effects of Impurities in Random Sequential Adsorption on a One-Dimensional Substrate

We have solved the kinetics of random sequential adsorption of linear $k$-mers on a one-dimensional disordered substrate for the random sequential adsorption initial condition and for the random initial condition. The jamming limits $\theta(\infty, k', k)$ at fixed length of linear $k$-mers have a minimum point at a particular density of the linear $k'$-mers impurity for both cases. The coverage of the surface and the jamming limits are compared to the results for Monte Carlo simulation. The Monte Carlo results for the jamming limits are in good agreement with the analytical results. The continuum limits are derived from the analytical results on lattice substrates.Comment: 9 pages, latex, 1 figure not included, accepted in Phys. Rev.