15,958 research outputs found
Actions of higher-rank lattices on free groups
If is a semisimple Lie group of real rank at least 2 and is an
irreducible lattice in , then every homomorphism from to the outer
automorphism group of a finitely generated free group has finite image.Comment: 11 pages, no figures. Final version. To appear in Compositio Mat
An Investigation of Firm Heterogeneity in the Constraints to Development and Growth in Pakistan
This study considers the importance of firm characteristics in explaining the degree of business constraints facing Pakistani firms in the Investment Climate Survey. We quantify how firms with differing characteristics experience particular problems. After controlling for other factors, the largest differences in responses to business constraints occur among firms that vary by manufacturing industry, and among firms operating under different ownership structures or selling in different markets. In some cases, firm size and firm location also play an important role. The age of the firm generally does not lead to significant differences. These results account for the heterogeneity of firms better than others, and may be important for policy-makers to develop more specific approaches to fostering the investment climate.Pakistan, Investment Climate, Business Constraints
A search for strong, ordered magnetic fields in Herbig Ae/Be stars
The origin of magnetic fields in intermediate-mass and high-mass stars is
fundamentally a mystery. Clues toward solving this basic astrophysical problem
can likely be found at the pre-main sequence (PMS) evolutionary stage. With
this work, we perform the largest and most sensitive search for magnetic fields
in pre-main sequence Herbig Ae/Be (HAeBe) stars. Sixty-eight observations of 50
HAeBe stars have been obtained in circularly polarised light using the FORS1
spectropolarimeter at the ESO VLT. An analysis of both Balmer and metallic
lines reveals the possible presence of weak longitudinal magnetic fields in
photospheric lines of two HAeBe stars, HD 101412 and BF Ori. The intensity of
the longitudinal fields detected in HD 101412 and BF Ori suggest that they
correspond to globally-ordered magnetic fields with surface intensities of
order 1 kG. Monte Carlo simulations of the longitudinal field measurements of
the undetected stars allow us to place an upper limits of about 300 G on the
general presence of aligned magnetic dipole magnetic fields, and of about 500 G
on perpendicular dipole fields. We find that the observed bulk incidence of
magnetic HAeBe stars in our sample is 8-12%, in good agreement with that of
magnetic main sequence stars of similar masses. We also find that the rms
longitudinal field intensity of magnetically-detected HAeBe stars is similar to
that of Ap stars and consistent with magnetic flux conservation during stellar
evolution. These results are all in agreement with the hypothesis that the
magnetic fields of main sequence Ap/Bp stars are fossils, which already exist
within the stars at the pre-main sequence stage. Finally, we explore the
ability of our new magnetic data to constrain magnetospheric accretion in
Herbig Ae/Be stars.Comment: Accepted by Monthly Notices of the Royal Astronomical Society, 2007
January 11. Received 2007 January 11; in original form 2006 August 18. The
paper contains 18 pages, 11 figures and 2 table
On the design of an adjustable high precision latching hinge
The design and test details of a high precision hinge and locking mechanism created principally in support of the Lockheed space deployable Flexrib Parabolic Antenna concept are presented. These developed improvements in the detail design of ultra-precise rib hinge and contour adjustment mechanisms will allow radio frequency antenna reflectors to expand into the 15-50 meter diameter size class and to support the .013 mm. deployment repeatability tolerance required to support the 12+ GHz frequency range
Post heat treatment effects on double layer metal structures for VLSI applications
The realization of high yield double layer metal systems using wet chemistry processes and the ability to extend yields beyond that attainable with wet chemistry by means of post sintering processes at temperatures below 500 C for potential applications in very large scale integration structures were studied. Yields in excess of 98% and average total contact resistance of less than 150 ohms and 200 ohms were realized for a series of 560 vias of 0.5 X 0.5 mils and 0.2 X 0.2 mils in size, respectively
The Douglas-Peucker line simplification algorithm : an introduction with programs
CISRG discussion paper ;
Effects of a simulated space environment on thermal radiation characteristics of selected black coatings
Simulated space environment effects on thermal radiation characteristics of black coating
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