UNSWIRF: A Tunable Imaging Spectrometer for the Near-Infrared

We describe the specifications, characteristics, calibration, and analysis of data from the University of New South Wales Infrared Fabry-Perot (UNSWIRF) etalon. UNSWIRF is a near-infrared tunable imaging spectrometer, used primarily in conjunction with IRIS on the AAT, but suitable for use as a visitor instrument at other telescopes. The etalon delivers a resolving power in excess of 4000 (corresponding to a velocity resolution ~75 km/s), and allows imaging of fields up to 100" in diameter on the AAT at any wavelength between 1.5 and 2.4 microns for which suitable blocking filters are available.Comment: 16 pages, 10 figures, uses psfig.sty and html.sty (included). To appear in Publications of the Astronomical Society of Australi

Spin Squeezing under Non-Markovian Channels by Hierarchy Equation Method

We study spin squeezing under non-Markovian channels, and consider an ensemble of $N$ independent spin-1/2 particles with exchange symmetry. Each spin interacts with its own bath, and the baths are independent and identical. For this kind of open system, the spin squeezing under decoherence can be investigated from the dynamics of the local expectations, and the multi-qubit dynamics can be reduced into the two-qubit one. The reduced dynamics is obtained by the hierarchy equation method, which is a exact without rotating-wave and Born-Markov approximation. The numerical results show that the spin squeezing displays multiple sudden vanishing and revival with lower bath temperature, and it can also vanish asymptotically.Comment: 7 pages, 4 figure

Tunable Resonant Raman Scattering from Singly Resonant Single Wall Carbon Nanotubes

We perform tunable resonant Raman scattering on 17 semiconducting and 7 metallic singly resonant single wall carbon nanotubes. The measured scattering cross-section as a function laser energy provides information about a tube's electronic structure, the lifetime of intermediate states involved in the scattering process and also energies of zone center optical phonons. Recording the scattered Raman signal as a function of tube location in the microscope focal plane allows us to construct two-dimensional spatial maps of singly resonant tubes. We also describe a spectral nanoscale artifact we have coined the "nano-slit effect"

Enhanced Eco-Approach Control of Connected Electric Vehicles at Signalized Intersection with Queue Discharge Prediction

Long queues of vehicles are often found at signalized intersections, which increases the energy consumption of all the vehicles involved. This paper proposes an enhanced eco-approach control (EEAC) strategy with consideration of the queue ahead for connected electric vehicles (EVs) at a signalized intersection. The discharge movement of the vehicle queue is predicted by an improved queue discharge prediction method (IQDP), which takes both vehicle and driver dynamics into account. Based on the prediction of the queue, the EEAC strategy is designed with a hierarchical framework: the upper-stage uses dynamic programming to find the general trend of the energy-efficient speed profile, which is followed by the lower-stage model predictive controller to computes the explicit solution for a short horizon with guaranteed safe inter-vehicular distance. Finally, numerical simulations are conducted to demonstrate the energy efficiency improvement of the EEAC strategy. Besides, the effects of the queue prediction accuracy on the performance of the EEAC strategy are also investigated

Efficient Phase-Encoding Quantum Key Generation with Narrow-Band Single Photons

We propose an efficient phase-encoding quantum secret key generation scheme with heralded narrow-band single photons. The key information is carried by the phase modulation directly on the single-photon temporal waveform without using any passive beam splitters or optical switches. We show that, when the technique is applied to the conventional fiber-based phase-encoding BB84 and differential phase shift (DPS) quantum key distribution schemes, the key generation efficiencies can be improved by a factor of 2 and 3, respectively. For N(>3)-period DPS systems, the key generation efficiency can be improved by a factor of N. The technique is suitable for quantum memory-based long-distance fiber communication system.Comment: 5 pages, 5 figure

Spiking Neurons Learning Phase Delays

Time differences between the two ears are an important cue for animals to azimuthally locate a sound source. The first binaural brainstem nucleus, in mammals the medial superior olive, is generally believed to perform the necessary computations. Its cells are sensitive to variations of interaural time differences of about 10 μs. The classical explanation of such a neuronal time-difference tuning is based on the physical concept of delay lines. Recent data, however, are inconsistent with a temporal delay and rather favor a phase delay. By means of a biophysical model we show how spike-timing-dependent synaptic learning explains precise interplay of excitation and inhibition and, hence, accounts for a physical realization of a phase delay

Tests of Two-Body Dirac Equation Wave Functions in the Decays of Quarkonium and Positronium into Two Photons

Two-Body Dirac equations of constraint dynamics provide a covariant framework to investigate the problem of highly relativistic quarks in meson bound states. This formalism eliminates automatically the problems of relative time and energy, leading to a covariant three dimensional formalism with the same number of degrees of freedom as appears in the corresponding nonrelativistic problem. It provides bound state wave equations with the simplicity of the nonrelativistic Schroedinger equation. Here we begin important tests of the relativistic sixteen component wave function solutions obtained in a recent work on meson spectroscopy, extending a method developed previously for positronium decay into two photons. Preliminary to this we examine the positronium decay in the 3P_{0,2} states as well as the 1S_0. The two-gamma quarkonium decays that we investigate are for the \eta_{c}, \eta_{c}^{\prime}, \chi_{c0}, \chi_{c2}, \pi^{0}, \pi_{2}, a_{2}, and f_{2}^{\prime} mesons. Our results for the four charmonium states compare well with those from other quark models and show the particular importance of including all components of the wave function as well as strong and CM energy dependent potential effects on the norm and amplitude. The results for the \pi^{0}, although off the experimental rate by 15%, is much closer than the usual expectations from a potential model. We conclude that the Two-Body Dirac equations lead to wave functions which provide good descriptions of the two-gamma decay amplitude and can be used with some confidence for other purposes.Comment: 79 pages, included new sections on covariant scalar product and added pages on positronium decay for 3P0 and 3P_2 state

Effects of Stocking Rates on Water Use Efficiency of Established Species in \u3ci\u3eStipa breviflora\u3c/i\u3e Desert Steppe

Plant water use efficiency reflects the survival adaptation strategies adopted by plants to obtain maximum carbon harvest. Understanding the water and resource utilization strategies of Stipa breviflora in desert steppe will help people understand its growth mechanism, and it is of great significance to analyze the ecological countermeasures of Stipa breviflora to cope with disturbance. In this study, the water use efficiency (WUE) of the established populations of Stipa breviflora in desert steppe was measured by stable carbon isotope method and photosynthometer method, and the adaptation mechanism of Stipa breviflora under different stocking rates was discussed based on the basic quantitative characteristics, leaf nutrient content, and soil physical and chemical properties. The results showed as follows: WUEl of MG treatment was significantly lower than that of CK and HG treatment (P \u3c 0.05), and there was no significant difference between WUEl of LG treatment and other treatment (P \u3e 0.05). With the increase of stocking rate, WUEl of S. breviflora showed a trend of first decreasing and then increasing. S. breviflora WUEt in CK and LG treatments was significantly higher than that in HG treatment, but there was no significant difference between S. breviflora WUEt in MG treatment and other treatments. With the increase of stocking rate, S. breviflora WUEt showed a linear decreasing trend. The WUEi of S. breviflora in LG treatment area was significantly higher than that in HG treatment area, but there was no significant difference in WUEi among other treatment areas. In general, with the increase of stocking rate, the WUE of Stipa breviflora showed a downward trend. By exploring the effects of different stocking rates on WUE of the established species in Stipa breviflora desert steppe, we concluded that increasing stocking rates reduced WUE of Stipa breviflora, and banning grazing was an ideal way to improve WUE of the established species

Non-collinear magnetic structure and anisotropic magnetoelastic coupling in cobalt pyrovanadate Co2V2O7

The Co2V2O7 is recently reported to exhibit amazing magnetic field-induced magnetization plateaus and ferroelectricity, but its magnetic ground state remains ambiguous due to its structural complexity. Magnetometry measurements, and time-of-flight neutron powder diffraction (NPD) have been employed to study the structural and magnetic properties of Co2V2O7, which consists of two non-equivalent Co sites. Upon cooling below the Ne\'el temperature TN = 6.3 K, we observe magnetic Bragg peaks at 2K in NPD which indicated the formation of long range magnetic order of Co2+ moments. After symmetry analysis and magnetic structure refinement, we demonstrate that Co2V2O7 possesses a complicated non-collinear magnetic ground state with Co moments mainly located in b-c plane and forming a non-collinear spin-chain-like structure along the c-axis. The ab initio calculations demonstrate that the non-collinear magnetic structure is more stable than various ferromagnetic states at low temperature. The non-collinear magnetic structure with canted up-up-down-down spin configuration is considered as the origin of magnetoelectric coupling in Co2V2O7 because the inequivalent exchange striction induced by the spin-exchange interaction between the neighboring spins is the driving force of ferroelectricity. Besides, it is found that the deviation of lattice parameters a and b is opposite below TN, while the lattice parameter c and stay almost constant below TN, evidencing the anisotropic magnetoelastic coupling in Co2V2O7.Comment: 9 pages, 8 figure

Willingness to Pay for Better Air Quality: The case of China

Air pollution is a big threat to human beings and has attract worldwide attention from governments and scholars. Based on the survey of happiness in China, this paper attempts to analyze the impact of local air quality on the happiness of individuals, and to evaluate the monetary value of mitigating air pollution. Through merging individual happiness data in a nationally representative survey with daily air quality index (AQI) according to the date and location of each respondent, it calculates the marginal rate of substitution (MRS) between air quality and income, and then estimates respondents’ willingness to pay (WTP) for better air quality. Moreover, it has further explored the differences of WTPs among groups. This study reaches the conclusion that happiness is positively associated with income but negatively correlated with air pollution. Besides, individual happiness is heavily influenced by income, age, gender, health condition, marital status and other variables. Furthermore, WTPs differ greatly among groups and the estimated average WTP of whole sample is 549.36RMB(or 0.90% of annual household income) per year per family for one unit reduction in AQI