9,346 research outputs found
Evaluating the impact of conditional cash transfer programs : lessons from Latin America
Unlike most development initiatives, conditional cash transfer programs recently introduced in the Latin America and the Caribbean region have been subject to rigorous evaluations of their effectiveness. These programs provide money to poor families, conditional on certain behavior, usually investments in human capital-such as sending children to school or bringing them to health centers on a regular basis. Rawlings and Rubio review the experience in evaluating the impact of these programs, exploring the application of experimental and quasi-experimental evaluation methods and summarizing results from programs launched in Brazil, Honduras, Jamaica, Mexico, and Nicaragua. Evaluation results from the first generation of programs in Brazil, Mexico, and Nicaragua show that conditional cash transfer programs are effective in promoting human capital accumulation among poor households. There is clear evidence of success in increasing enrollment rates, improving preventive health care, and raising household consumption. Despite this promising evidence, many questions remain unanswered about the impact of conditional cash transfer programs, including those concerning their effectiveness under different country conditions and the sustainability of the welfare impacts.Public Health Promotion,Poverty Monitoring&Analysis,Poverty Impact Evaluation,Health Monitoring&Evaluation,Health Systems Development&Reform,Poverty Monitoring&Analysis,Poverty Impact Evaluation,Health Monitoring&Evaluation,Poverty Assessment,Health Systems Development&Reform
High Excitation Molecular Gas in the Magellanic Clouds
We present the first survey of submillimeter CO 4-3 emission in the
Magellanic Clouds. The survey is comprised of 15 6'x6' maps obtained using the
AST/RO telescope toward the molecular peaks of the Large and Small Magellanic
Clouds. We have used these data to constrain the physical conditions in these
objects, in particular their molecular gas density and temperature. We find
that there are significant amounts of molecular gas associated with most of
these molecular peaks, and that high molecular gas temperatures are pervasive
throughout our sample. We discuss whether this may be due to the low
metallicities and the associated dearth of gas coolants in the Clouds, and
conclude that the present sample is insufficient to assert this effect.Comment: 18 pages, 3 figures, 5 tables. To appear in Ap
Granular Scale Magnetic Flux Cancellations in the Photosphere
We investigate the evolution of 5 granular-scale magnetic flux cancellations
just outside the moat region of a sunspot by using accurate spectropolarimetric
measurements and G-band images with the Solar Optical Telescope aboard Hinode.
The opposite polarity magnetic elements approach a junction of the
intergranular lanes and then they collide with each other there. The
intergranular junction has strong red shifts, darker intensities than the
regular intergranular lanes, and surface converging flows. This clearly
confirms that the converging and downward convective motions are essential for
the approaching process of the opposite-polarity magnetic elements. However,
motion of the approaching magnetic elements does not always match with their
surrounding surface flow patterns in our observations. This suggests that, in
addition to the surface flows, subsurface downward convective motions and
subsurface magnetic connectivities are important for understanding the approach
and collision of the opposite polarity elements observed in the photosphere. We
find that the horizontal magnetic field appears between the canceling opposite
polarity elements in only one event. The horizontal fields are observed along
the intergranular lanes with Doppler red shifts. This cancellation is most
probably a result of the submergence (retraction) of low-lying photospheric
magnetic flux. In the other 4 events, the horizontal field is not observed
between the opposite polarity elements at any time when they approach and
cancel each other. These approaching magnetic elements are more concentrated
rather than gradually diffused, and they have nearly vertical fields even while
they are in contact each other. We thus infer that the actual flux cancellation
is highly time dependent events at scales less than a pixel of Hinode SOT
(about 200 km) near the solar surface.Comment: Accepted for publication in the Astrophysical Journa
Subalgebras with Converging Star Products in Deformation Quantization: An Algebraic Construction for \complex \mbox{\LARGE P}^n
Based on a closed formula for a star product of Wick type on \CP^n, which
has been discovered in an earlier article of the authors, we explicitly
construct a subalgebra of the formal star-algebra (with coefficients contained
in the uniformly dense subspace of representative functions with respect to the
canonical action of the unitary group) that consists of {\em converging} power
series in the formal parameter, thereby giving an elementary algebraic proof of
a convergence result already obtained by Cahen, Gutt, and Rawnsley. In this
subalgebra the formal parameter can be substituted by a real number :
the resulting associative algebras are infinite-dimensional except for the case
, a positive integer, where they turn out to be isomorphic to
the finite-dimensional algebra of linear operators in the th energy
eigenspace of an isotropic harmonic oscillator with degrees of freedom.
Other examples like the -torus and the Poincar\'e disk are discussed.Comment: 16 pages, LaTeX with AMS Font
Importance de l'état énergétique de l'eau sur l'aptitude au tassement de matériaux argileux non saturés
Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai
Scanning tunneling microscopy simulations of poly(3-dodecylthiophene) chains adsorbed on highly oriented pyrolytic graphite
We report on a novel scheme to perform efficient simulations of Scanning
Tunneling Microscopy (STM) of molecules weakly bonded to surfaces. Calculations
are based on a tight binding (TB) technique including self-consistency for the
molecule to predict STM imaging and spectroscopy. To palliate the lack of
self-consistency in the tunneling current calculation, we performed first
principles density-functional calculations to extract the geometrical and
electronic properties of the system. In this way, we can include, in the TB
scheme, the effects of structural relaxation upon adsorption on the electronic
structure of the molecule. This approach is applied to the study of
regioregular poly(3-dodecylthiophene) (P3DDT) polymer chains adsorbed on highly
oriented pyrolytic graphite (HOPG). Results of spectroscopic calculations are
discussed and compared with recently obtained experimental datComment: 15 pages plus 5 figures in a tar fil
Switching the Conductance of a Molecular Junction using a Proton Transfer Reaction
A novel mechanism for switching a molecular junction based on a proton
transfer reaction triggered by an external electrostatic field is proposed. As
a specific example to demonstrate the feasibility of the mechanism, the
tautomers [2,5-(4-hydroxypyridine)] and {2,5-[4(1H)-pyridone]} are considered.
Employing a combination of first-principles electronic structure calculations
and Landauer transport theory, we show that both tautomers exhibit very
different conductance properties and realize the "on" and "off" states of a
molecular switch. Moreover, we provide a proof of principle that both forms can
be reversibly converted into each other using an external electrostatic field.Comment: 14 pages, 5 figure
Total positivity and high relative accuracy for several classes of Hankel matrices
Gramian matrices with respect to inner products defined for Hilbert spaces supported on bounded and unbounded intervals are represented through a bidiagonal factorization. It is proved that the considered matrices are strictly totally positive Hankel matrices and their catalecticant determinants are also calculated. Using the proposed representation, the numerical resolution of linear algebra problems with these matrices can be achieved to high relative accuracy. Numerical experiments are provided, and they illustrate the excellent results obtained when applying the theoretical results
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