7,315 research outputs found
The impact of grants, tax credit and education savings account on parental contributions to college expenses and the educational attainment of children
This paper presents a multi-period, dynamic programming model of household choices on savings, consumption, having children and helping to fund children\u27s education. Data from the National Longitudinal Survey young women cohort are used to estimate the parameters of the model. The full structural model is estimated using a simulated maximum likelihood procedure utilizing the dynamic programming model solution to create simulated data samples from which nonparametric kernel estimators are used to construct the densities in the likelihood. The estimated model is able to match the general trends in the NLS data, particularly as related to the interaction between children, savings and spending on education. The life-cycle paths of these choices suggest that parents do save to help make sizeable transfers to their children, and that making such choices endogenous is important. Furthermore, the parameter estimates indicate that the amount that parents choose to contribute to a child 19s education has a strong impact on the probability that a child attains a college degree, as does the level of education of the parents. Using the estimated model, policy experiments are performed to look at the impact of additional government grants for college education, tax credits for college spending and the creation of tax-free education savings accounts on parental savings, contributions toward education, and the education attainment of children. While all of the policies increase net contributions to children and increase the probability that a child attains a college degree, the grants and education savings accounts are found to be the most effective. In addition, both policies are actually found to have a greater impact on children with less educated parents
The impact of grants, tax credit and education savings account on parental contributions to college expenses and the educational attainment of children
This paper presents a multi-period, dynamic programming model of household choices on savings, consumption, having children and helping to fund children\u27s education. Data from the National Longitudinal Survey young women cohort are used to estimate the parameters of the model. The full structural model is estimated using a simulated maximum likelihood procedure utilizing the dynamic programming model solution to create simulated data samples from which nonparametric kernel estimators are used to construct the densities in the likelihood. The estimated model is able to match the general trends in the NLS data, particularly as related to the interaction between children, savings and spending on education. The life-cycle paths of these choices suggest that parents do save to help make sizeable transfers to their children, and that making such choices endogenous is important. Furthermore, the parameter estimates indicate that the amount that parents choose to contribute to a child 19s education has a strong impact on the probability that a child attains a college degree, as does the level of education of the parents. Using the estimated model, policy experiments are performed to look at the impact of additional government grants for college education, tax credits for college spending and the creation of tax-free education savings accounts on parental savings, contributions toward education, and the education attainment of children. While all of the policies increase net contributions to children and increase the probability that a child attains a college degree, the grants and education savings accounts are found to be the most effective. In addition, both policies are actually found to have a greater impact on children with less educated parents
Derivative expansion of the renormalization group in O(N) scalar field theory
We apply a derivative expansion to the Legendre effective action flow
equations of O(N) symmetric scalar field theory, making no other approximation.
We calculate the critical exponents eta, nu, and omega at the both the leading
and second order of the expansion, associated to the three dimensional
Wilson-Fisher fixed points, at various values of N. In addition, we show how
the derivative expansion reproduces exactly known results, at special values
N=infinity,-2,-4, ... .Comment: 29 pages including 4 eps figures, uses LaTeX, epsfig, and latexsy
Hadamard transform techniques in photothermal spectroscopy
Hadamard transform imaging is shown to be generally applicable to any linear spectroscopy and to be useful where locally high power densities are undesirable. Application to transverse photothermal deflection and Raman spectroscopies is reviewed. The modulation transfer functions (MTF) of both sourceâencoded and signalâencoded Hadamard imagers are described. Preliminary results from a signalâencoded imager are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87498/2/725_1.pd
Electrophoresis with Polarized Fluorescence Detection. Application to Capillary Fluorescence Rejection
In this paper, we integrate the apparatus of electrophoresis with polarized fluorescence detection to suppress the background fluorescence arising from illuminating the coating layer of channel containers with a laser excitation source. It has demonstrated moderate background suppression efficiency, close to the ideal 3âfold reduction on the surface doped with randomly distributed static fluorophores. In addition, when the fluorescence coverage is coated along the same orientation more uniformly, the background reduction is 10âfold in our experiments. This detection scheme is applicable to acquire the electrophoregrams of separating small organic molecules and biopolymers, such as nucleic acids, when the loading of staining dyes is not heavy. This apparatus is simple. Only adding a pair of polarizer optics is needed. This detection scheme should work equally well with an incoherent light source.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112242/1/200500106_ftp.pd
Surface enhanced Raman spectroscopy of neurotransmitters
The surfaceâenhanced Raman spectra (SERS) of neurotransmitters in biological matrices and synthetic solutions are described. The effects of protein adsorption on cathecholamine SERS intensity are discussed. Techniques for obtaining dopamine SERS spectra in cerebrospinal fluid and rat brain dialysate are demonstrated. Preliminary SERS of histamine and telâmethylhistamine are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87497/2/707_1.pd
Porous silica spheres as indoor air pollutant scavengers
Porous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene-divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for volatile organic compounds evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment
Bone quality assessment of osteogenic cell cultures by Raman microscopy
The use of autologous stem/progenitor cells represents a promising approach to the repair of craniofacial bone defects. The calvarium is recognized as a viable source of stem/progenitor cells that can be transplanted in vitro to form bone. However, it is unclear if bone formed in cell culture is similar in quality to that found in native bone. In this study, the quality of bone mineral formed in osteogenic cell cultures were compared against calvarial bone from postnatal mice. Given the spectroscopic resemblance that exists between cell and collagen spectra, the feasibility of extracting information on cell activity and bone matrix quality were also examined. Stem/progenitor cells isolated from fetal mouse calvaria were cultured onto fusedâquartz slides under osteogenic differentiation conditions for 28Â days. At specific time intervals, slides were removed and analyzed by Raman microscopy and mineral staining techniques. We show that bone formed in culture at Day 28 resembled calvarial bone from 1âdayâold postnatal mice with comparable mineralization, mineral crystallinity, and collagen crosslinks ratios. In contrast, bone formed at Day 28 contained a lower degree of ordered collagen fibrils compared with 1âdayâold postnatal bone. Taken together, bone formed in osteogenic cell culture exhibited progressive matrix maturation and mineralization but could not fully replicate the high degree of collagen fibril order found in native bone.In this Raman spectroscopic study, we examined the quality of bone formed in vitro by fetal mouse calvarial stem/progenitor cells under osteogenic differentiation conditions. We characterized bone mineral and matrix cell culture components and detected the presence of lipid and glycosaminoglycanâlike components. Bone formed in vitro at Day 28 was similar to 1âdayâold postnatal mouse calvarial bone in terms of mineralization, mineral crystallinity, and collagen crosslink ratios, but differed in the degree of collagen fibril order.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148347/1/jrs5521_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148347/2/jrs5521.pd
Sampling for Global Epidemic Models and the Topology of an International Airport Network
Mathematical models that describe the global spread of infectious diseases such as influenza, severe acute respiratory syndrome (SARS), and tuberculosis (TB) often consider a sample of international airports as a network supporting disease spread. However, there is no consensus on how many cities should be selected or on how to select those cities. Using airport flight data that commercial airlines reported to the Official Airline Guide (OAG) in 2000, we have examined the network characteristics of network samples obtained under different selection rules. In addition, we have examined different size samples based on largest flight volume and largest metropolitan populations. We have shown that although the bias in network characteristics increases with the reduction of the sample size, a relatively small number of areas that includes the largest airports, the largest cities, the most-connected cities, and the most central cities is enough to describe the dynamics of the global spread of influenza. The analysis suggests that a relatively small number of cities (around 200 or 300 out of almost 3000) can capture enough network information to adequately describe the global spread of a disease such as influenza. Weak traffic flows between small airports can contribute to noise and mask other means of spread such as the ground transportation
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