2,535 research outputs found
The Matching Method for Treatment Evaluation with Selective Participation and Ineligibles
The matching method for treatment evaluation does not balance selective unobserved differences between treated and non-treated. We derive a simple correction term if there is an instrument that shifts the treatment probability to zero in specific cases. Policies with eligibility restrictions, where treatment is impossible if some variable exceeds a certain value, provide a natural application. In an empirical analysis, we first examine the performance of matching versus regression-discontinuity estimation in the sharp age-discontinuity design of the NDYP job search assistance program for young unemployed in the UK. Next, we exploit the age eligibility restriction in the Swedish Youth Practice subsidized work program for young unemployed, where compliance is imperfect among the young. Adjusting the matching estimator for selectivity changes the results towards ineffectiveness of subsidized work in moving individuals into employment.job search assistance, selection, regression discontinuity, treatment effect, policy evaluation, propensity score, subsidized work, youth unemployment
The matching method for treatment evaluation with selective participation and ineligibles
The matching method for treatment evaluation does not balance selective unobserved differences between treated and non-treated. We derive a simple correction term if there is an instrument that shifts the treatment probability to zero in specific cases. Policies with eligibility restrictions, where treatment is impossible if some variable exceeds a certain value, provide a natural application. In an empirical analysis, we first examine the performance of matching versus regression-discontinuity estimation in the sharp age-discontinuity design of the NDYP job search assistance program for young unemployed in the UK. Next, we exploit the age eligibility restriction in the Swedish Youth Practice subsidized work program for young unemployed, where compliance is imperfect among the young. Adjusting the matching estimator for selectivity changes the results towards inefectiveness of subsidized work in moving individuals into employment.Propensity score; policy evaluation; treatment effect; regression discontinuity; selection; job search assistance; subsidized work; youth unemployment
Analysis using Adaptive Tree Structured Clustering Method for Medical Data of Patients with Coronary Heart Disease
It is known that the classification of medical data is
difficult problem because the medical data has ambiguous
information or missing data. As a result, the classification method that can handle ambiguous information or missing data is necessity. In this paper we proposed an adaptive tree structure clustering method in order to clarify clustering result of selforganizing feature maps. For the evaluating effectiveness of proposed clustering method for the data set with ambiguous information, we applied an adaptive tree structured clustering
method for classification of coronary heart disease database.
Through the computer simulation we showed that the proposed
clustering method was effective for the ambiguous data set
Method of extending hyperfine coherence times in Pr^3+:Y_2SiO_5
In this letter we present a method for increasing the coherence time of
praseodymium hyperfine ground state transitions in Pr^3+:Y_2SiO_5 by the
application of a specific external magnetic field. The magnitude and angle of
the external field is applied such that the Zeeman splitting of a hyperfine
transition is at a critical point in three dimensions, making the first order
Zeeman shift vanishingly small for the transition. This reduces the influence
of the magnetic interactions between the praseodymium ions and the spins in the
host lattice on the transition frequency. Using this method a phase memory time
of 82ms was observed, a value two orders of magnitude greater than previously
reported. It is shown that the residual dephasing is amenable quantum error
correction
Applying Cluster Ensemble to Adaptive Tree Structured Clustering
Adaptive tree structured clustering (ATSC) is our proposed divisive hierarchical clustering method that recursively
divides a data set into 2 subsets using self-organizing feature map (SOM). In each partition, the data set is quantized by SOM and the quantized data is divided using agglomerative hierarchical clustering. ATSC can divide data sets regardless of data size in feasible time. On the other hand clustering result stability of ATSC is equally unstable as other divisive hierarchical clustering and partitioned clustering methods. In this paper, we apply cluster ensemble for each data partition of ATSC in order to improve stability. Cluster ensemble is a framework for improving partitioned clustering stability. As a result of applying cluster ensemble, ATSC yields unique clustering results that could not be yielded by previous hierarchical clustering methods. This is because a different class distances function is used in each division in ATSC
Chiral symmetry breaking and stability of strangelets
We discuss the stability of strangelets by considering dynamical chiral
symmetry breaking and confinement. We use a
symmetric Nambu--Jona-Lasinio model for chiral symmetry breaking supplemented
by a boundary condition for confinement. It is shown that strangelets with
baryon number can stably exist. For the observables, we
obtain the masses and the charge-to-baryon number ratios of the strangelets.
These quantities are compared with the observed data of the exotic particles.Comment: 10 pages, 9 figures, submitted to Physical Review
Chiral charge-density-waves
We discovered the chirality of charge density waves (CDW) in 1T-TiSe by
using scanning tunnelling microscopy (STM) and optical ellipsometry. We found
that the CDW intensity becomes , where (i =1, 2, 3) is the amplitude of the tunnelling current
contributed by the CDWs. There were two states, in which the three intensity
peaks of the CDW decrease \textit{clockwise} and \textit{anticlockwise} when we
index each nesting vector in order of intensity in the Fourier transformation
of the STM images. The chirality in CDW results in the three-fold symmetry
breaking. Macroscopically, two-fold symmetry was indeed observed in optical
measurement. We propose the new generalized CDW chirality H_{CDW} \equiv
{\boldmath q_1} \cdot ({\boldmath q_2}\times {\boldmath q_3}), where
{\boldmath q_i} are the nesting vectors, which is independent of the
symmetry of components. The nonzero - the triple-{\boldmath q}
vectors do not exist in an identical plane in the reciprocal space - should
induce a real-space chirality in CDW system.Comment: 12 pages, 4 figure
Strangelets: Who is Looking, and How?
It has been over 30 years since the first suggestion that the true ground
state of cold hadronic matter might be not nuclear matter but rather strange
quark matter (SQM). Ever since, searches for stable SQM have been proceeding in
various forms and have observed a handful of interesting events but have
neither been able to find compelling evidence for stable strangelets nor to
rule out their existence. I will survey the current status and near future of
such searches with particular emphasis on the idea of SQM from strange star
collisions as part of the cosmic ray flux.Comment: Talk given at International Conference on Strangeness in Quark
Matter, 2006. 8 pages. 1 figur
Higher order effects in the and transfer reactions
Full Coupled Channels Calculations were performed for the
and transfer reactions at several deuteron incident
energies from MeV up to 3.27 MeV. A strong polarization effect
between the entrance channel and the transfer channels
and was
observed. This polarization effect had to be taken into account in order to
obtain realistic spectroscopic factors from these reactions.Comment: 15 papes, 13 figures, accepted for publication in Phys. Rev.
Model for the Quasifree Polarization-Transfer Measurements in the (p,n) reaction at 495 MeV
The recent (p,n) polarization transfer experiments at LAMPF are explained in
terms of a dropping rho-meson mass in the medium.Comment: 12 pages of text (LATEX), 4 figures (not included, available from the
authors). February 199
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