14,432 research outputs found
TRUE STATE DEPENDENCE IN MONTHLY WELFARE PARTICIPATION:A NONEXPERIMENTAL ANALYSIS
This paper provides an empirical evaluation of true state dependence in welfare participation
using unique administrative data from California that is measured at the monthly frequency,
which coincides with the welfare eligibility period and so is free of time aggregation bias. The
analysis uses first- and second-order dynamic conditional logit models that non-parametrically
control for permanent unobserved heterogeneity to test for state dependence in welfare behavior.
The second-order model also absorbs individual-specific first-order Markov chains, and provides
a more robust test for state dependence in high frequency data. The results using the first-order
model show substantial first-order state dependence in monthly welfare participation. Absorbing
heterogeneous first-order effects, the hypothesis of no second-order state dependence is also
easily rejected. This suggests that past welfare participation predicts future participation, given
unrestricted effects of both the present state and unobserved heterogeneity, and provides
substantive evidence of duration dependence at the individual level.Binary response panel data, state dependence, unobserved heterogeneity, initialconditions, conditional logit models
Dynamical transition for a particle in a squared Gaussian potential
We study the problem of a Brownian particle diffusing in finite dimensions in
a potential given by where is Gaussian random field.
Exact results for the diffusion constant in the high temperature phase are
given in one and two dimensions and it is shown to vanish in a power-law
fashion at the dynamical transition temperature. Our results are confronted
with numerical simulations where the Gaussian field is constructed, in a
standard way, as a sum over random Fourier modes. We show that when the number
of Fourier modes is finite the low temperature diffusion constant becomes
non-zero and has an Arrhenius form. Thus we have a simple model with a fully
understood finite size scaling theory for the dynamical transition. In addition
we analyse the nature of the anomalous diffusion in the low temperature regime
and show that the anomalous exponent agrees with that predicted by a trap
model.Comment: 18 pages, 4 figures .eps, JPA styl
Shell Model Monte Carlo Studies of -Soft Nuclei
We present Shell Model Monte Carlo calculations for nuclei within the full
major shell 50-82 for both protons and neutrons. The interaction is determined
solely by self-consistency and odd-even mass differences. The methods are
illustrated for Sn, Te and Xe. We calculate shape
distributions, moments of inertia and pairing correlations as functions of
temperature and angular velocity. Our calculations are the first microscopic
evidence of -softness of nuclei in this region.Comment: uuencoded postscript of manuscript with three figure
Lecture videos to supplement electromagnetic classes at Cal Poly San Luis Obispo
Electromagnetics and Transmission Lines is a fundamental, yet difficult subject in the Electrical Engineering (EE) field. To help improve information retention, a series of lecture videos was created to supplement traditional lectures, to facilitate in-class discussions, and to improve studentsâ proficiency and interest in electromagnetics.
Engineering electromagnetics classes at California Polytechnic State University, San Luis Obispo cover fundamentals to understand and analyze cell phone communications, radar systems (air traffic control, law enforcement), and biomedical imaging (MRI). However, this subject also requires considerable mathematics preparation in vector calculus, differential equations, linear algebra, and background in both physics and EE.
Lecture videos were created on the Camtasia software to produce MP4 audio-visual files. All videos include a topic outline, stationary and animated visual displays of lecture topic applications, and a detailed discussion using outlines and handwritten notes. Example calculations and real-world applications, Smith Chart graphical analysis, and Matlab computations and visual animations (standing and traveling waves, dynamic vector field and scalar contour diagrams) augment theoretical discussions and help visualize course concepts. Real-world applications including the Large Hadron Collider (CERN), RF test equipment (network analyzers), cell phone tower antennas, and radar imaging systems are introduced in the videos and related to course topics. A total of 36 videos were recorded for EE 335 (junior-level electromagnetics); average video length is 20 to 25 minutes for each 50 minute lecture.
All lecture videos were stored online (dropbox.com) and made available one week prior to each class session. A student survey was conducted to assess perceived video effectiveness, to compare to traditional lectures, and to estimate video usage (how often watched, how many hours per week). Questions also include overall suggestions for video improvement, favorite (and not so favorite) parts of the class, and overall impressions.
Most students appeared to value the new videos: 55% agreed with the statement âthe lecture videos helped me learn course concepts.â Video length (20 â 25 minute average) was between too long (43%) and just right (29%). The most common negative comment mentioned the additional time required to view the videos over a traditional lecture class.
Future efforts toward a flipped (inverted) classroom format include the development of topic videos and post-video quizzes to encourage pre-lecture viewing, as suggested in [1]. Video production improvements including minimized length and enhanced information organization will be applied to future lecture videos. Practical lab projects [2] will also be explored and added as another method of enhancing student interest in electromagnetics. Finally, information retention between traditional and flipped classroom formats will be compared to determine the relative effectiveness of both approaches
A method for designing lightweight and flexible creep-age forming tools using mechanical splines and sparse controlling points
An Investigation, Using Standard Experimental Techniques, to Determine FLCs at Elevated Temperature for Aluminium Alloys
An experimental procedure has been developed for the determination of FLCs at elevated temperatures. The GOM ARGUS system was employed for measuring surface strain based on pre-applied grids (pattern), and limit strains were determined according to the ISO 12004-2:2008 standard. Forming limit curves (FLCs) have been determined for AA5754 under warm forming conditions in an isothermal environment. The tests were carried out at various temperatures up to 300oC and forming speeds ranging from 5 â 300 mm s-1 . Results reveal the significant effect of both temperature and forming speed on FLCs of AA5754. Formability increases with increasing temperature above 200oC. Formability also increases with decreasing speed. The presented FLC results show that the best formability exists at low forming speed and the high temperature end of the warm forming range
Large Deviations of Extreme Eigenvalues of Random Matrices
We calculate analytically the probability of large deviations from its mean
of the largest (smallest) eigenvalue of random matrices belonging to the
Gaussian orthogonal, unitary and symplectic ensembles. In particular, we show
that the probability that all the eigenvalues of an (N\times N) random matrix
are positive (negative) decreases for large N as \exp[-\beta \theta(0) N^2]
where the parameter \beta characterizes the ensemble and the exponent
\theta(0)=(\ln 3)/4=0.274653... is universal. We also calculate exactly the
average density of states in matrices whose eigenvalues are restricted to be
larger than a fixed number \zeta, thus generalizing the celebrated Wigner
semi-circle law. The density of states generically exhibits an inverse
square-root singularity at \zeta.Comment: 4 pages Revtex, 4 .eps figures included, typos corrected, published
versio
Extreme Value Statistics of Eigenvalues of Gaussian Random Matrices
We compute exact asymptotic results for the probability of the occurrence of
large deviations of the largest (smallest) eigenvalue of random matrices
belonging to the Gaussian orthogonal, unitary and symplectic ensembles. In
particular, we show that the probability that all the eigenvalues of an (NxN)
random matrix are positive (negative) decreases for large N as ~\exp[-\beta
\theta(0) N^2] where the Dyson index \beta characterizes the ensemble and the
exponent \theta(0)=(\ln 3)/4=0.274653... is universal. We compute the
probability that the eigenvalues lie in the interval [\zeta_1,\zeta_2] which
allows us to calculate the joint probability distribution of the minimum and
the maximum eigenvalue. As a byproduct, we also obtain exactly the average
density of states in Gaussian ensembles whose eigenvalues are restricted to lie
in the interval [\zeta_1,\zeta_2], thus generalizing the celebrated Wigner
semi-circle law to these restricted ensembles. It is found that the density of
states generically exhibits an inverse square-root singularity at the location
of the barriers. These results are confirmed by numerical simulations.Comment: 17 pages Revtex, 5 .eps figures include
A Survival Model for Unthinned Loblolly Pine Plantations That Incorporates Non-Planted Tree Competition, Site Quality, and Incidence of Fusiform Rust
Future biomass yields are functionally related to the number of trees surviving at a given age. A stand level survival model was developed that incorporates competition of non-planted trees, site quality, and the incidence of fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme). The model consists of a system of two equations, one of which represents the number of surviving trees infected by fusiform rust while the other represents the number of trees not infected by fusiform rust. Data from unthinned loblolly pine (Pinus taeda L.) plantations in East Texas were used to fit and evaluate the survival model and illustrate its use. The model successfully predicted that the number of surviving loblolly pine trees decreased as the number of non-planted trees increased. The model also successfully predicted the transition of loblolly pine trees from an uninfected to an infected status by fusiform rust
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