Spin squeezing: transforming one-axis-twisting into two-axis-twisting

Squeezed spin states possess unique quantum correlation or entanglement that are of significant promises for advancing quantum information processing and quantum metrology. In recent back to back publications [C. Gross \textit{et al, Nature} \textbf{464}, 1165 (2010) and Max F. Riedel \textit{et al, Nature} \textbf{464}, 1170 (2010)], reduced spin fluctuations are observed leading to spin squeezing at -8.2dB and -2.5dB respectively in two-component atomic condensates exhibiting one-axis-twisting interactions (OAT). The noise reduction limit for the OAT interaction scales as $\propto 1/{N^{2/3}}$, which for a condensate with $N\sim 10^3$ atoms, is about 100 times below standard quantum limit. We present a scheme using repeated Rabi pulses capable of transforming the OAT spin squeezing into the two-axis-twisting type, leading to Heisenberg limited noise reduction $\propto 1/N$, or an extra 10-fold improvement for $N\sim 10^3$.Comment: 4 pages, 3 figure

The effects of surface finish and grain size on the strength of sintered silicon carbide

The effects of surface treatment and microstructure, especially abnormal grain growth, on the strength of sintered SiC were studied. The surfaces of sintered SiC were treated with 400, 800 and 1200 grit diamond wheels. Grain growth was induced by increasing the sintering times at 2050 C. The beta to alpha transformation occurred during the sintering of beta-phase starting materials and was often accompanied by abnormal grain growth. The overall strength distributions were established using Weibull statistics. The strength of the sintered SiC is limited by extrinsic surface flaws in normal-sintered specimens. The finer the surface finish and grain size, the higher the strength. But the strength of abnormal sintering specimens is limited by the abnormally grown large tabular grains. The Weibull modulus increases with decreasing grain size and decreasing grit size for grinding

Fault diagnostic instrumentation design for environmental control and life support systems

As a development phase moves toward flight hardware, the system availability becomes an important design aspect which requires high reliability and maintainability. As part of continous development efforts, a program to evaluate, design, and demonstrate advanced instrumentation fault diagnostics was successfully completed. Fault tolerance designs for reliability and other instrumenation capabilities to increase maintainability were evaluated and studied

Business Ecosystem and Stakeholders’ Role Transformation: Evidence from China’s Emerging Electric Vehicle Industry

Nurturing an emerging industry’s business ecosystem always requires stakeholders’ efforts and role transformation. By systematically reviewing and studying the evolution of the Chinese electric vehicle industry, this paper constructs a three-dimensional theoretical framework including stages of business ecosystem lifecycle, stakeholder classification and functional roles, to analyse the transformation both of different stakeholders and their functional roles. The findings show that business ecosystem stakeholders have experienced role transformation following a mechanism defined as the ‘Triple Oscillation’ Model during the evolution of the emerging industry. These findings also help develop a conceptual model of agent-based system for business ecosystem evolution, which could be a starting point for further emerging industry study

Cerenkov Line Emission as a Possible Mechanism of X-ray Lines in Gamma-ray Bursts

The recent discoveries of X-ray lines in the afterglows of gamma-ray bursts (GRBs) provide significant clues to the nature of GRB progenitors and central environments. However, the iron line interpretation by fluorescence or recombination mechanism requires a large amount of iron material. We argue that the very strong iron line could be attributed to an alternative mechanism: Cerenkov line emission since relativistic electrons and dense medium exist near GRB sites. Therefore, the broad iron lines are expected, and line intensity will be nearly independent of the iron abundance, the medium with the anomalously high Fe abundance is not required.Comment: 4 pages, revised version accepted for the publication in ApJ

Brushing Element Fields

Aggregate elements following certain directions have a variety of applications in graphics, design, and visualization. However, authoring oriented elements in various output domains, especially in 3D, remains challenging. We propose a novel brushing system to facilitate interactive authoring of aggregate elements with diverse properties over given output domains via an element synthesis approach. To increase output quality and reduce input workload, we further propose element fields that can automatically orient the entire elements in better alignments over the output domains according to partially user-specified strokes. The proposed system can effectively synthesize distinct types of elements within various output domains in higher quality and efficiency and offer more user friendliness than existing practices. Our method can be applied to practical applications such as graphic design, artistic collage, and aggregate modelin

A Critical Examination of Hypernova Remnant Candidates in M101. II. NGC 5471B

NGC 5471B has been suggested to contain a hypernova remnant because of its extraordinarily bright X-ray emission. To assess its true nature, we have obtained high-resolution images in continuum bands and nebular lines with the Hubble Space Telescope, and high-dispersion long-slit spectra with the Kitt Peak National Observatory 4-m echelle spectrograph. The images reveal three supernova remnant (SNR) candidates in the giant HII region NGC 5471, with the brightest one being the 77x60 pc shell in NGC 5471B. The Ha velocity profile of NGC 5471B can be decomposed into a narrow component (FWHM = 41 km/s) from the background HII region and a broad component (FWHM = 148 km/s) from the SNR shell. Using the brightness ratio of the broad to narrow components and the Ha flux measured from the WFPC2 Ha image, we derive an Ha luminosity of (1.4+-0.1)x10^39 ergs/s for the SNR shell. The [SII]6716,6731 doublet ratio of the broad velocity component is used to derive an electron density of ~700 cm^-3 in the SNR shell. The mass of the SNR shell is thus 4600+-500 Mo. With a \~330 km/s expansion velocity implied by the extreme velocity extent of the broad component, the kinetic energy of the SNR shell is determined to be 5x10^51 ergs. This requires an explosion energy greater than 10^52 ergs, which can be provided by one hypernova or multiple supernovae. Comparing to SNRs in nearby active star formation regions, the SNR shell in NGC 5471B appears truly unique and energetic. We conclude that the optical observations support the existence of a hypernova remnant in NGC 5471B.Comment: 27 pages, 9 figures, to appear in May 2002 issue of The Astronomical Journa