Quantum Computing vs. Coherent Computing

In this review article, we compare the performance of two computing systems: quantum computing and coherent computing. A layered architecture for circuit-model quantum computing, employing surface code quantum error correction, has been recently discussed. Using this concrete hardware platform, it is possible to provide resource analysis for executing the fault-tolerent quantum computing for prime number factoring and molecular eigen-energy calculation that cannot be solved by the present day computing systems. A particular quantum computing system could solve such problems on the time scale of 1-10 days by using 10⁸ – 10⁹ physical qubits. We discuss an alternative computing system based on an injection-locked laser network wnicn is called a coherent computing system here. A three-dimensional Ising model is mapped onto the mutually injection-locked slave laser network, while the independent injection signal from a master laser implements a Zeeman Hamiltonian. In this computing system, an Ising spin taking either up or down state is represented by the polarization degrees of freedom, right or left circular polarizations, of the lasing photons in each slave laser. A spin-spin coupling coefficient is implemented by simple linear polarization optics connecting the two slave lasers. We numerically study the scaling law of the proposed machine against the anti-ferromagnetic Ising model with varying problem size M. A transient time to reach a steady state polarization configuration is inversely proportional to the locking bandwidth and does not depend on the problem size strongly up to M=1000.     

Bayes Error Estimation Using Parzen and k-NN Procedures

The use of k nearest neighbor (k-NN) and Parzen density estimates to obtain estimates of the Bayes error is investigated under limited design set conditions. By drawing analogies between the k-NN and Parzen procedures, new procedures are suggested, and experimental results are given which indicate that these procedures yield a significant improvement over the conventional k-NN and Parzen procedures. We show that, by varying the decision threshold, many of the biases associated with the k-NN or Parzen density estimates may be compensated, and successful error estimation may be performed in spite of these biases. Experimental results are given which demonstrate the effect of kernel size and shape (Parzen), the size of k (k-NN), and the number of samples in the design set.     

Automatic detection of dust devils and clouds on Mars

The acquisition of science data in space applications is shifting from teleoperated data collection to an automated onboard analysis, resulting in improved data quality, as well as improved usage of limited resources such as onboard memory, CPU, and communications bandwidth. Science instruments onboard a modern deep-space spacecraft can acquire much more data that can be downloaded to Earth, given the limited communication bandwidth. Onboard data analysis offers a means of compressing the huge amounts of data collected and downloading only the most valuable subset of the collected data. In this paper, we describe algorithms for detecting dust devils and clouds onboard Mars rovers, and summarize the results. These algorithms achieve the accuracy required by planetary scientists, as well as the runtime, CPU, memory, and bandwidth constraints set by the engineering mission parameters. The detectors have been uploaded to the Mars Exploration Rovers, and currently are operational. These detectors are the first onboard science analysis processes on Mars.     

High repetition rate PEA system for in-situ space charge measurement during breakdown tests

In order to investigate transient space charge phenomena, it is essential that the space charge profile be observed at a high repetition rate. We have developed a new space charge measurement system using the pulsed electroacoustic (PEA) method, which can measure the space charge profiles every 10 /spl mu/s. It employs the most recent digitising oscilloscope model and a semiconductor switch. The effect of prestressing on impulse breakdown voltage of a low-density polyethylene sheet was investigated by using the new system. Experimental results suggest that positive charge injection was dominant immediately before the breakdown, and charge injection during the prestressing causes distortion of the electric field near the electrode, and enhances the subsequent charge injection due to the impulse voltage.     

Space charge formation at the interface between a charge transportlayer and a polyester film

The organic photoconductor structure used in a copying machine consists of electron-conductive and ion-conductive layers, a charge generation layer, and a charge transport layer. We applied the pulsed electroacoustic method, which has been used to evaluate HV insulation, to measure the space charge behavior of the charge transport layer coated on a polyester film. On the surface of the charge transport layer, various electrodes were evaporated. An internal space charge accumulated at the interface between the charge transport layer and the polyester film under a dc electric field. We show that the charge distribution is formed by the injection of holes from the anode and by the surface charge, and that the hole injection is influenced by the anode material     

Mineralogical mapping of southern Namibia by application of continuum-removal MSAM method to the HyMap data

We applied the Modified Spectral Angle Mapper (MSAM) and continuum-removal methods to reflectance data obtained in the shortwave infrared regions by the airborne hyperspectral sensor, HyMap, to delineate distribution of the minerals related to hydrothermal alteration and pegmatite. The combination of these two methods was applied to remotely sensed hyperspectral data for the first time in this study. The effectiveness of this method, ‘continuum-removal MSAM’, was confirmed by comparing our mineral index maps with existing mineral maps of the Cuprite region, Nevada, USA. We then produced mineral index maps of southern Namibia using newly observed hyperspectral data. The existence of many pegmatite- and porphyry-type deposits is reported in this study area, where detailed mineralogical mapping based on remote-sensing data has not previously been conducted. Our mineral index maps are consistent with our field survey results, and also with X-ray diffraction analyses and spectral measurements of rock samples. In this study, the continuum-removal MSAM method successfully discriminated hydrothermal alteration minerals such as kaolinite and pyrophyllite, and pegmatite-related minerals such as high-aluminium muscovite and lepidolite in southern Namibia for the first time. The main advantages of our classification method are simplicity and high-precision identification of alteration minerals.     

Effects of Trans and Conjugated LC N‐3 Polyunsaturated Fatty Acids on Lipid Composition and Abdominal Fat Weight in Rats

ABSTRACT: Trans and conjugated fatty acids may exhibit either beneficial or detrimental bioactive effects depending on their metabolic properties. This study was conducted to elucidate if isomerization and conjugation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) demonstrate more favorable bioactivity on lipid metabolism compared to unmodified EPA and DHA. The effects of dietary intake of trans and conjugated forms of EPA and DHA on lipid metabolism were evaluated in animal trials and compared to a control group fed soybean oil. None of the experimental diets showed significant differences from the control in terms of body weight; however, the white adipose tissue weight of rodents fed trans DHA, conjugated EPA (CEPA), and conjugated DHA (CDHA) was significantly lower than the control. Triacylglycerol levels in plasma were significantly decreased in groups fed trans DHA (17.2 mg/dL) and CDHA (31.9 mg/dL) relative to the control (51.3 mg/dL). The total cholesterol concentrations were significantly lower than the control (68.0 mg/dL) in all experimental groups (47.3 to 53.7 mg/dL) except CEPA (58.3 mg/dL). Fatty acid compositions of lipids extracted from rodent livers were influenced by the dietary fatty acid profiles, with all groups showing higher concentrations of stearic acid and lower levels of linoleic acid compared to the control. Rodents fed trans DHA did not have detectable levels of these fatty acid isomers in their livers, suggesting either quick metabolism or a difficulty with bio‐absorption.     

Characterization of CuMn-spinel catalyst for methanol steam reforming

CuMn-spinel oxide (CuMn(S)) and non-spinel CuMn (CuMn(NS)) oxide have been obtained by calcining the same precursor at 900 °C and 300 °C, respectively. CuMn(S) was composed of Cu_1.5Mn_1.5O₄ spinel and Mn₃O₄, while CuMn(NS) consisted of CuO and Mn₃O₄. XRD, EXAFS, and TEM measurements of the samples reduced in hydrogen revealed that both CuMn(S) and CuMn(NS) were reduced to Cu metal dispersed on MnO and that the particle size of Cu metal from the CuMn(S) was smaller than that from CuMn(NS). In methanol steam reforming, the spinel derived catalyst showed higher activity than the non-spinel due to the higher dispersion of the Cu metal.     

Nucleation kinetics of a Li2O·2SiO2 glass based on a liquid model

A liquid model was proposed wherein crystal embryos should exist in equilibrated melts at temperatures even above the melting point or liquidus temperature and the number density of embryos should decrease as the melting temperature increases. Crystallization behavior of a Li₂O·2SiO₂ glass was studied. Secondary heat-treatment (600 °C for 20–60 min) of the Li₂O·2SiO₂ glass induced different number of crystals depending upon the melting temperature in the range 1040°–1300 °C and duration of heat-treatment t. The number density of crystals N decreased with increasing temperature of melting. The number density of pre-existing embryos was estimated from (N – t) diagram and was found consistent with what the proposed model claims.     

Pulsed laser processing of nano-polycrystalline diamond: A comparative study with single crystal diamond

We have conducted laser processing of ultrahard nano-polycrystalline and single crystalline diamonds (NPD, SCD, respectively) using nano-pulsed near-ultraviolet laser, and the machining properties were compared through microstructural examinations by SEM, TEM and Raman spectroscopy. The cut depth of the laser-cut grooves was observed to be deeper for the NPD than for the SCD. This is probably due to the lower thermal conductivity feature of NPD, which provides higher absorption efficiency of the laser energy and decreases the laser ablation threshold. TEM cross-section observation showed that the processed grooves in the both types of diamonds are covered with identical laser-modified layers (~ 1 µm thick) composed of roughly oriented nanocrystalline graphite. A marked difference was observed between the laser-processed surfaces of NPD and SCD: in the former the diamond–graphite interface is almost linear and undamaged, whereas in the latter the boundary is slightly folded and significantly distorted. These textural features suggest that different laser-machining processes are involved between NPD and SCD in the microscopic scale. Our results demonstrate that pulsed laser can be used even more effectively for the fabrication of nano-polycrystalline diamond than the case for single crystal diamond.