Epidemiological Baseline of Influenza Virus in Wild Aquatic Birds in Hong Kong during the Pre-H5N1 Endemic Era

Influenza virus surveillance was conducted on wild ducks and shorebirds in Hong Kong at the Mai Po Nature Reserve to determine whether East Asian wild aquatic birds passing through or overwintering in Hong Kong are reservoirs of H5N1 influenza viruses and to establish an epidemiological baseline of influenza virus in wild aquatic birds during the pre-H5N1 endemic era. Three influenza viruses were isolated from 3178 faecal samples collected over three sampling periods from 1988 to 2001 during the southern and northern migration periods. The isolation rates and viruses were, respectively 0.08% (H10N5) in 1988 – 1990, 0.12% (H11N1) in 1998 and 0.09% (H3N8) in 1999 – 2001. Whereas tracheal and intestinal colon explants from representative shorebirds were susceptible to in vitro infection by the H10N5 virus, orally infected shorebirds were apparently not. Genetic analyses indicated that the nucleoprotein, matrix and nonstructural genes of the three viruses were related to those of aquatic bird viruses in Asia, but not to those of the human H5N1 virus. The present study provided epidemiological baseline information for future influenza virus surveillance in wild aquatic birds in southeast China

Nonmetallic impurities improve mechanical properties of vapor-deposited tungsten

Mechanical properties of vapor deposited tungsten are improved by selective incorporation of various nonmetallic impurities. Addition of trace quantities of carbon, nitrogen, or oxygen can significantly increase both low and high temperature yield strength without greatly affecting ductile-to-brittle transition temperature

Coherence and Decoherence in Biological Systems: Principles of Noise Assisted Transport and the Origin of Long-lived Coherences

The quantum dynamics of transport networks in the presence of noisy environments have recently received renewed attention with the discovery of long-lived coherences in different photosynthetic complexes. This experimental evidence has raised two fundamental questions: Firstly, what are the mechanisms supporting long-lived coherences and secondly, how can we assess the possible functional role that the interplay of noise and quantum coherence might play in the seemingly optimal operation of biological systems under natural conditions? Here we review recent results, illuminate them at the hand of two paradigmatic systems, the Fenna-Matthew-Olson (FMO) complex and the light harvesting complex LHII, and present new progress on both questions. In particular we introduce the concept of the phonon antennae and discuss the possible microscopic origin or long-lived electronic coherences.Comment: Paper delivered at the Royal Society Discussion Meeting "Quantum-coherent energy transfer: implications for biology and new energy technologies", 27 - 28 April 2011 at The Kavli Royal Society International Centre, Buckinghamshire, UK. Accepted for publication in Philosophical Transactions of the Royal Society

Finding the constrained Delaunay triangulation and constrained Voronoi diagram of a simple polygon in linear time

In this paper, we present a Θ(n) time worst-case deterministic algorithm for finding the constrained Delaunay triangulation and constrained Voronoi diagram of a simple n-sided polygon in the plane. Up to now, only an O(n log n) worst-case deterministic and an O(n) expected time bound have been shown, leaving an O(n) deterministic solution open to conjecture.published_or_final_versio

Effects of additions of nonmetallics on the properties of vapor-deposited tungsten

Nonmetallic additive effects on properties of vapor deposited tungste

Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array

In this paper, we proposed a newly modified cuckoo search (MCS) algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The basic cuckoo search (CS) algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA) techniques include particle swarm optimization (PSO) and genetic algorithms (GA)

Efficient simulation of strong system-environment interactions

Multi-component quantum systems in strong interaction with their environment are receiving increasing attention due to their importance in a variety of contexts, ranging from solid state quantum information processing to the quantum dynamics of bio-molecular aggregates. Unfortunately, these systems are difficult to simulate as the system-bath interactions cannot be treated perturbatively and standard approaches are invalid or inefficient. Here we combine the time dependent density matrix renormalization group methods with techniques from the theory of orthogonal polynomials to provide an efficient method for simulating open quantum systems, including spin-boson models and their generalisations to multi-component systems

Experimental and analytical investigation of the variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer

The variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer was measured by laser light-scattering technology. An analytical model was developed to predict the variation of spray characteristics along the radial distance. A comparison of the predicted and experimental data showed excellent agreement. Therefore, the spray model proposed, although relatively simple, is correct and can be used, with some expansion and modification of the prepared model, to predict more complicated spray systems

The detection of extragalactic 15^{15}N: Consequences for nitrogen nucleosynthesis and chemical evolution

Detections of extragalactic $^{15}$N are reported from observations of the rare hydrogen cyanide isotope HC$^{15}$N toward the Large Magellanic Cloud (LMC) and the core of the (post-) starburst galaxy NGC 4945. Accounting for optical depth effects, the LMC data from the massive star-forming region N113 infer a $^{14}N/^{15}$N ratio of 111 $\pm$ 17, about twice the $^{12}C/^{13}$C value. For the LMC star-forming region N159HW and for the central region of NGC 4945, $^{14}N/^{15}$N ratios are also $\approx$ 100. The $^{14}N/^{15}$N ratios are smaller than all interstellar nitrogen isotope ratios measured in the disk and center of the Milky Way, strongly supporting the idea that $^{15}$N is predominantly of `primary' nature, with massive stars being its dominant source. Although this appears to be in contradiction with standard stellar evolution and nucleosynthesis calculations, it supports recent findings of abundant $^{15}$N production due to rotationally induced mixing of protons into the helium-burning shells of massive stars.Comment: 15 pages including one postscript figure, accepted for publication by ApJ Letter, further comments: please contact Yi-nan Chi