We present unpublished work of D. Carter, G. Keller, and E. Paige on bounded generation in special linear groups. Let n be a positive integer, and let A = O be the ring of integers of an algebraic number field K (or, more generally, let A be a localization OS−1). If n = 2, assume that A has infinitely many units. We show there is a finite-index subgroup H of SL(n, A), such that every matrix in ...

In the present paper, we study the group SL 2 (H Z) of (2 2)-matrices with reduced norm 1 over the noncommutative ring of Hamilton quaternions with integral coeecients. In section 1, we obtain a presentation for SL 2 (H Z) in terms of generators and deening relations. In section 2, we exhibit a subgroup of nite index of SL 2 (H Z) with a nonabelian free quotient of rank 3. It is well known that...

The Kordkanlo Basin, one of the Atrak sub-basins, located in the northeastern of the Ghoochan city, the Khorasan Razavi Province; is situated in Kopet Dagh geologic zone. The overall objective of this study is to evaluate the morphotectonic effects on the drainage network of the basin, using morphometric indicators. In this research, morphometric quantitative indicators of hypsometric integral ...

Double-layer quantum Hall systems possess interlayer phase coherence at sufficiently small layer separations, even without interlayer tunneling. When interlayer tunneling is present, application of a sufficiently strong in-plane magnetic field B i.Bc drives a commensurate-incommensurate ~CI! transition to an incommensurate soliton-lattice ~SL! state. We calculate the Hartree-Fock ground-state e...

BACKGROUND This study aimed to investigate the association between exposure to occupational hazards for pregnancy and sick leave (SL) in pregnant workers. METHODS A cross-sectional study was performed in French occupational health services in 2014. Occupational hazards for pregnancy were assessed by occupational health physicians (OHPs). After delivery and at the time of returning to work, 1,...

“Danxia landform” is a landform type originally defined in China, characterized by red-colored sandstones and steep cliffs, and developed through long-term erosion. In recent years, Danxia landforms have been receiving international attention, and six examples in China became a UNESCO World Natural Heritage in 2010. However, morphometric studies of Danxia landforms in China have been very limit...

in central part of kopeh dagh there is an array of active right-lateral strike-slip faults that obliquely cut the range and produce offsets of several kilometers in the geomorphology and geological structure. geomorphic indices indicate the presence of differential uplifting in history of this area. tectonic activity of the study area is investigated by a large number of dem derived catchments ...

Iran is well known for having countless historical and instrumental records of tectonic events. Shahriary catchment, as a study area, is part of the Zagros collision seismic province. This research aimed to introduce a new method which is useful in identifying the relative active tectonic events of an area. The research method was designed in order to calculate the relative active tectonic inde...

Several methods for the estimation of functional diversity are employed in plant communities. However, it is hard to select the most suitable measures in practice. This work presents comparisons of nine distance-based measures applied to functional diversity analysis in forest communities (36 plots) along an elevational gradient in the Pangquangou Reserve, China. The employed indices and method...