Localized knowledge spillovers and patent citations: A distance-based approach

We develop a new approach to localized knowledge spillovers by incorporating the concept of control patents (Jaffe, Trajtenberg and Henderson 1993) into the distance-based test of localization (Duranton and Overman, 2005). Using microgeographic data, we identify localization distance while allowing for cross-boundary spillovers, unlike the existing literature where the extent of localized knowledge spillovers is detected at the state or metropolitan statistical area level. We revisit the recent debate by Thompson and Fox-Kean (2005) and Henderson, Jaffe and Trajtenberg (2005) on the existence of localized knowledge spillovers, and find solid evidence supporting localization, even when finer controls are used.

Observation of a Rotating Radiation Belt in LHD

A poloidally rotating radiation belt with helical structure was observed during the high density discharges with detachment by photodiode fan arrays and a fast camera in LHD. The peak of radiation rotates inside the last closed flux surface, and the direction and mode number of the poloidal rotation are electron diamagnetic and one, respectively. During the recombination phase after termination of the plasma heating, the rotation continues, and its rotating radius shrinks with shrinking of the plasma column. The poloidal rotating frequency depends on the heating power, and increases from the orders of several tens of Hz to several hundreds of Hz with shrinking of the rotation radius. The mechanism of the rotation remains uncertain

ESI-MS Analysis of Effluents from Medical Silicon Rubber

The catheter tubes of medical silicon rubber were dipped in ethanol. The effluents were fractionated by thin-layer chromatography (TLC), and their fractions were analyzed by ion trap electrospray ionization mass spectrometry (ESI-MS). The ESI mass spectra resulting from the main TLC fraction, R1=0.5 showed that the effluents were determined to be poly(dimethyl siloxane) (8 to 20 mer) that is a main part of a silicon rubber. The spectra for the origin in TLC showed that poly(ethylene glycol) (4 to 10 mer and 14 to 18 mer) and poly- (propylene glycol) (19 to 36 mer) as an antistatic agent were identified

Astrometry of Water Maser Sources in Nearby Molecular Clouds with VERA - II. SVS 13 in NGC 1333

We report on the results of multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of the 22 GHz H2O masers associated with the young stellar object SVS 13 in the NGC 1333 region. We have carried out phase-referencing VLBI astrometry and measured an annual parallax of the maser features in SVS 13 of 4.25+/-0.32 mas, corresponding to the distance of 235+/-18 pc from the Sun. Our result is consistent with a photometric distance of 220 pc previously reported. Even though the maser features were detectable only for 6 months, the present results provide the distance to NGC 1333 with much higher accuracy than photometric methods. The absolute positions and proper motions have been derived, revealing that the H2O masers with the LSR (local standard of rest) velocities of 7-8 km s-1 are most likely associated with VLA4A, which is a radio counterpart of SVS 13. The origin of the observed proper motions of the maser features are currently difficult to attribute to either the jet or the rotating circumstellar disk associated with VLA4A, which should be investigated through future high-resolution astrometric observations of VLA4A and other radio sources in NGC 1333.Comment: 9 pages, 5 figures. PASJ, in press (2008, Vol. 60, No. 1

Astrometry of Galactic Star Forming Region Sharpless 269 with VERA : Parallax Measurements and Constraint on Outer Rotation Curve

We have performed high-precision astrometry of H2O maser sources in Galactic star forming region Sharpless 269 (S269) with VERA. We have successfully detected a trigonometric parallax of 189+/-8 micro-arcsec, corresponding to the source distance of 5.28 +0.24/-0.22 kpc. This is the smallest parallax ever measured, and the first one detected beyond 5 kpc. The source distance as well as proper motions are used to constrain the outer rotation curve of the Galaxy, demonstrating that the difference of rotation velocities at the Sun and at S269 (which is 13.1 kpc away from the Galaxy's center) is less than 3%. This gives the strongest constraint on the flatness of the outer rotation curve and provides a direct confirmation on the existence of large amount of dark matter in the Galaxy's outer disk.Comment: 7 pages and 4 figures, Accepted by PASJ (Vol. 59, No. 5, October 25, 2007 issue