17,722 research outputs found
Trends in AFDC Participation Rates: The Implications for Welfare Reform
Congress justified the recent reform of federal welfare policy in part by citing the increase in the AFDC caseload since the late 1960s. The caseload, i.e., the number of families using AFDC, is determined by the number of families eligible to participate and by the proportion of these families who use the program. Yet the debate over reforming welfare rarely paid attention to the latter—the participation rates among female heads of families. While the number of cases changed little during the early to mid-1980s, the percentage of families with single female heads who used AFDC declined. During the late 1980s and early 1990s, both caseloads and participation rates increased. This paper documents the changes in participation rates since the mid-1980s, racial and ethnic differences in participation rates, and factors that might be associated with these changes. The only major trend that consistently parallels the changes in participation rates is the trend in unemployment. Existing data do not permit us to conclude that unemployment is the major determinant of participation rates. If unemployment drives participation rates, however, the recent changes in welfare legislation may create serious problems for many female heads of families in periods of high unemployment.
Supervised Classification Using Sparse Fisher's LDA
It is well known that in a supervised classification setting when the number
of features is smaller than the number of observations, Fisher's linear
discriminant rule is asymptotically Bayes. However, there are numerous modern
applications where classification is needed in the high-dimensional setting.
Naive implementation of Fisher's rule in this case fails to provide good
results because the sample covariance matrix is singular. Moreover, by
constructing a classifier that relies on all features the interpretation of the
results is challenging. Our goal is to provide robust classification that
relies only on a small subset of important features and accounts for the
underlying correlation structure. We apply a lasso-type penalty to the
discriminant vector to ensure sparsity of the solution and use a shrinkage type
estimator for the covariance matrix. The resulting optimization problem is
solved using an iterative coordinate ascent algorithm. Furthermore, we analyze
the effect of nonconvexity on the sparsity level of the solution and highlight
the difference between the penalized and the constrained versions of the
problem. The simulation results show that the proposed method performs
favorably in comparison to alternatives. The method is used to classify
leukemia patients based on DNA methylation features
Method of fan sound mode structure determination
A method for the determination of fan sound mode structure in the Inlet of turbofan engines using in-duct acoustic pressure measurements is presented. The method is based on the simultaneous solution of a set of equations whose unknowns are modal amplitude and phase. A computer program for the solution of the equation set was developed. An additional computer program was developed which calculates microphone locations the use of which results in an equation set that does not give rise to numerical instabilities. In addition to the development of a method for determination of coherent modal structure, experimental and analytical approaches are developed for the determination of the amplitude frequency spectrum of randomly generated sound models for use in narrow annulus ducts. Two approaches are defined: one based on the use of cross-spectral techniques and the other based on the use of an array of microphones
Resource management implications of ERTS-1 data to Ohio
Initial experimental analysis of ERTS-1 imagery has demonstrated that remote sensing from space is a means of delineating and inventorying Ohio's strip-mined areas, detecting power plant smoke plumes, and proving the data necessary for periodically compiling land use maps for the entire state. The nature and extent of these problems throughout Ohio, how ERTS data can contribute to their solution, and estimates of the long term significance of these initial findings to overall resource management interests in Ohio are summarized
Orbital surveys and state resource management
The resource management implications of satellite earth resource surveys for the state of Ohio are discussed. Discussions cover environmental problems, planning future developments, and short- and long-range benefits of such resource management
The Adiabatic Invariance of the Action Variable in Classical Dynamics
We consider one-dimensional classical time-dependent Hamiltonian systems with
quasi-periodic orbits. It is well-known that such systems possess an adiabatic
invariant which coincides with the action variable of the Hamiltonian
formalism. We present a new proof of the adiabatic invariance of this quantity
and illustrate our arguments by means of explicit calculations for the harmonic
oscillator.
The new proof makes essential use of the Hamiltonian formalism. The key step
is the introduction of a slowly-varying quantity closely related to the action
variable. This new quantity arises naturally within the Hamiltonian framework
as follows: a canonical transformation is first performed to convert the system
to action-angle coordinates; then the new quantity is constructed as an action
integral (effectively a new action variable) using the new coordinates. The
integration required for this construction provides, in a natural way, the
averaging procedure introduced in other proofs, though here it is an average in
phase space rather than over time.Comment: 8 page
An evolutionary perspective on the kinome of malaria parasites
Malaria parasites belong to an ancient lineage that diverged very early from the main branch of eukaryotes. The approximately 90-member plasmodial kinome includes a majority of eukaryotic protein kinases that clearly cluster within the AGC, CMGC, TKL, CaMK and CK1 groups found in yeast, plants and mammals, testifying to the ancient ancestry of these families. However, several hundred millions years of independent evolution, and the specific pressures brought about by first a photosynthetic and then a parasitic lifestyle, led to the emergence of unique features in the plasmodial kinome. These include taxon-restricted kinase families, and unique peculiarities of individual enzymes even when they have homologues in other eukaryotes. Here, we merge essential aspects of all three malaria-related communications that were presented at the Evolution of Protein Phosphorylation meeting, and propose an integrated discussion of the specific features of the parasite's kinome and phosphoproteome
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