11,631 research outputs found
Meridional heat transport across the Antarctic Circumpolar Current by the Antarctic Bottom Water overturning cell
The heat transported by the lower limb of the Southern Ocean meridional overturning circulation is commonly held to be negligible in comparison with that transported by eddies higher in the water column. We use output from one of the first global high resolution models to have a reasonably realistic export of Antarctic Bottom Water, the OCCAM one twelfth degree model. The heat fluxed southward by the deep overturning cell using the annual mean field for 1994 at 56S is 0.033 PW, but the 5-day mean fields give a larger heat flux (0.048 and 0.061 PW depending on calculation method). This is more than 30% of previous estimates of the total heat flux. Eddies and other transients add considerably to the heat flux. These results imply that this component of meridional heat flux may not be negligible as has been supposed
FRT-duals as Quantum Enveloping Algebras
The Hopf algebra generated by the l-functionals on the quantum double C_q[G]
\bowtie C_q[G] is considered, where C_q[G] is the coordinate algebra of a
standard quantum group and q is not a root of unity. It is shown to be
isomorphic to C_q[G]^op \bowtie U_q(g). This was conjectured by T. Hodges in
[Ho]. As an algebra it can be embedded into U_q(g) \otimes U_q(g). Here it is
proven that there is no bialgebra structure on U_q(g) \otimes U_q(g), for which
this embedding becomes a homomorphism of bialgebras. In particular, it is not
an isomorphism. As a preliminary a lemma of [Ho] concerning the structure of
l-functionals on C_q[G] is generalized. For the classical groups a certain
choice of root vectors is expressed in terms of l-functionals. A formula for
their coproduct is derived.Comment: Revised version of math.QA/0109157, 12 page
The Cartan form for constrained Lagrangian systems and the nonholonomic Noether theorem
This paper deals with conservation laws for mechanical systems with
nonholonomic constraints. It uses a Lagrangian formulation of nonholonomic
systems and a Cartan form approach. We present what we believe to be the most
general relations between symmetries and first integrals. We discuss the
so-called nonholonomic Noether theorem in terms of our formalism, and we give
applications to Riemannian submanifolds, to Lagrangians of mechanical type, and
to the determination of quadratic first integrals.Comment: 25 page
Can commercially-oriented microfinance help meet the Millennium Development Goals? Evidence from Pakistan.
YesThe current emphasis in the microfinance industry is a shift from donor-funded to commercially sustainable operations. This article evaluates the impact of access to microloans from the Khushhali Bank - Pakistan's first and largest microfinance bank which operates on commercial principles. Using primary data from a detailed household survey of nearly 3000 borrower and non-borrower households, a difference in difference approach is used to test for the impact of access to loans. Once the results are disaggregated between rural and urban areas there is a positive impact in rural areas on food expenditure and on some social indicators
Experimental and modeling studies on the synthesis and properties of higher fatty esters of corn starch
This paper describes a systematic study on the synthesis of higher fatty esters of corn starch (starch laurate and starch stéarate) by using the corresponding vinyl esters. The reactions were carried out in DMSO using basic catalysts (Na2HPO4, K2CO3, and Naacetate). The effect of the process variables (vinyl ester to starch ratio, catalyst intake, reaction temperature and type of the catalyst) on the degree of substitution (DS) of the starch laurate and starch stearate esters was determined by performing a total of 54 experiments. The results were adequately modeled using a non-linear multivariable regression model (R2≥0. 96). The basicity of the catalyst and the reaction temperature have the highest impact on the product DS. The thermal and mechanical properties of some representative product samples were determined. High-DS products (DS = 2.26-2.39) are totally amorphous whereas the low-DS ones (DS = 1.45-1.75) are still partially crystalline. The thermal stability of the esterlfied products is higher than that of native starch. Mechanical tests show that the products have a tensile strength (stress at break) between 2.7-3.5 MPa, elongation at break of 3-26%, and modulus of elasticity of 46-113 MPa.
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