Understanding of the Retarded Oxidation Effects in Silicon Nanostructures

In-depth understanding of the retarded oxidation phenomenon observed during the oxidation of silicon nanostructures is proposed. The wet thermal oxidation of various silicon nanostructures such as nanobeams, concave/convex nanorings and nanowires exhibits an extremely different and complex behavior. Such effects have been investigated by the modeling of the mechanical stress generated during the oxidation process explaining the retarded regime. The model describes the oxidation kinetics of silicon nanowires down to a few nanometers while predicting reasonable and physical stress levels at the Si/SiO$_{2}$ interface by correctly taking into account the relaxation effects in silicon oxide through plastic flow

Planetary companions orbiting M giants HD 208527 and HD 220074

Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) is used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 +/- 5.8 and 672.1 +/- 3.7 days. The RV variations are not apparently related to the surface inhomogeneities and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 +/- 0.4 and 1.2 +/- 0.3 M_Sun, we obtain the minimum masses for the exoplanets of 9.9 +/- 1.7 and 11.1 +/- 1.8 M_Jup around HD 208527 and HD 220074 with an orbital semi-major axis of 2.1 +/- 0.2 and 1.6 +/- 0.1 AU and an eccentricity of 0.08 and 0.14, respectively. We also find that the previously known spectral classification of HD 208527 and HD 220074 was in error: Our new estimation of stellar parameters suggest that both HD 208527 and HD 220074 are M giants. Therefore, HD 208527 and HD 220074 are so far the first candidate M giants to harbor a planetary companion.Comment: 7 pages, 9 figures, 4 tables, accepted for publisation in Astronomy & Astrophysic

Seasonal variation of the three-dimensional mean circulation over the Scotian Shelf

The seasonal-mean circulation over the Scotian Shelf is studied numerically by computing mean and tidal current fields for winter, spring, and summer using a three-dimensional nonlinear diagnostic model. The mean current fields are forced by seasonal-mean baroclinic pressure gradients, tidal rectification, uniform wind stresses, and associated barotropic pressure gradients. A historical hydrographic database is used to determine the climatological mean baroclinic forcing. Upstream open boundary conditions are estimated from the density fields to give no normal geostrophic bottom flow and are specified as either along-boundary elevation gradients or depth-integrated normal velocities. The numerical solutions for nominal bimonthly periods (January–February, April–May, and July–August) reveal the dominant southwestward nearshore and shelf-break flows of relatively cool and fresh shelf water from the Gulf of St. Lawrence and Newfoundland Shelf, with speeds up to about 20 cm/s. The seasonal intensification of the southwestward flows is reproduced by the model, with the transport increasing from 0.3 Sv in summer to 0.9 Sv in winter on the inner Halifax section. There are also pronounced topographic-scale influences of submarine banks, basins, and cross-shelf channels on the circulation, such as anticyclonic gyres over banks and cyclonic gyres over basins. Baroclinicity is the dominant forcing throughout the domain, but tidal rectification is comparable on the southwestern Scotian Shelf (e.g., about 0.2 Sv recirculating transport around Browns Bank for all the periods). The mean wind stress generates offshore surface drift in winter. The solutions are in approximate agreement with observed currents and transports over the Scotian Shelf, although there are local discrepancies

Atomistic pseudopotential calculations of the optical properties of InAs/InP self-assembled quantum dots

We present a comprehensive study of the optical properties of InAs/InP self-assembled quantum dots (QDs) using an empirical pseudopotential method and configuration interaction treatment of the many-particle effects. The results are compared to those of InAs/GaAs QDs. The main results are: (i) The alignment of emission lines of neutral exciton, charged exciton and biexciton in InAs/InP QDs is quite different from that in InAs/GaAs QDs. (ii) The hidden correlation in InAs/InP QDs is 0.7 - 0.9 meV, smaller than that in InAs/GaAs QDs. (iii) The radiative lifetimes of neutral exciton, charged exciton and biexciton in InAs/InP QDs are about twice longer than those in InAs/GaAs QDs. (v) The phase diagrams of few electrons and holes in InAs/InP QDs differ greatly from those in InAs/GaAs QDs. The filling orders of electrons and holes are shown to obey the Hund's rule and Aufbau principle, and therefore the photoluminescence spectra of highly charged excitons are very different from those of InAs/GaAs QDs.Comment: 10 pages, 11 figure

Market Structure and International Trade: Business Groups in East Asia

In this paper we study the effect of market structure on the trade performance of South Korea, Taiwan, and Japan. We center our analysis on Korea and Taiwan, countries which have very different market structures: Korea has many large, vertically-integrated business groups known as chaebol, whereas business groups in Taiwan are smaller and horizontally-integrated in the production of intermediate inputs. The exports of these countries to the United States are compared using indexes of product variety and 'product mix', which are constructed at the 5-digit industry level. It is found that Taiwan tends to export a greater variety of products to the U.S. than Korea, and this holds across nearly all industries. In addition, Taiwan exports relatively more high-priced intermediate inputs, whereas Korea exports relatively more high-priced final goods. We argue that these results confirm the importance of market structure as a determinant of trade patterns.

Parallel processing architecture for computing inverse differential kinematic equations of the PUMA arm

In advanced robot control problems, on-line computation of inverse Jacobian solution is frequently required. Parallel processing architecture is an effective way to reduce computation time. A parallel processing architecture is developed for the inverse Jacobian (inverse differential kinematic equation) of the PUMA arm. The proposed pipeline/parallel algorithm can be inplemented on an IC chip using systolic linear arrays. This implementation requires 27 processing cells and 25 time units. Computation time is thus significantly reduced

The C-flash and the ignition conditions of type Ia supernovae

Thanks to a stellar evolution code able to compute through the C-flash we link the binary population synthesis of single degenerate progenitors of type Ia supernovae (SNe Ia) to their physical condition at the time of ignition. We show that there is a large range of possible ignition densities and we detail how their probability distribution depends on the accretion properties. The low density peak of this distribution qualitatively reminds of the clustering of the luminosities of Branch-normal SNe Ia. We tighten the possible range of initial physical conditions for explosion models: they form a one-parameter family, independent of the metallicity. We discuss how these results may be modified if we were to relax our hypothesis of a permanent Hachisu wind or if we were to include electron captures.Comment: 10 pages, 14 figures, MNRAS accepte

An easy-to-use diagnostic system development shell

The Diagnostic System Development Shell (DSDS), an expert system development shell for diagnostic systems, is described. The major objective of building the DSDS is to create a very easy to use and friendly environment for knowledge engineers and end-users. The DSDS is written in OPS5 and CommonLisp. It runs on a VAX/VMS system. A set of domain independent, generalized rules is built in the DSDS, so the users need not be concerned about building the rules. The facts are explicitly represented in a unified format. A powerful check facility which helps the user to check the errors in the created knowledge bases is provided. A judgement facility and other useful facilities are also available. A diagnostic system based on the DSDS system is question driven and can call or be called by other knowledge based systems written in OPS5 and CommonLisp. A prototype diagnostic system for diagnosing a Philips constant potential X-ray system has been built using the DSDS