2,289 research outputs found
Experimental Analysis of Neighborhood Effects on Youth
neighborhood, real experiment, multiple testing
Analysis of harmonic current interaction in an industial plant
An analysis of current transients caused by the operation of a nearby device in an industrial plant is presented in the paper. The source of current transients in the factory lighting system was traced to the operation of the nearby six-pulse AC/DC converter. To determine the nature of the interaction, a measurement was done with a storage oscilloscope. Also, laboratory experiments on one lamp were conducted. It was possible to exclude the presence of a parallel resonance on this site. It was concluded that transients are caused by voltage notches in certain working regimes of the six-pulse converter. Possible solutions to the problem are separating the supplies of the converter and the lighting installation, filtering, or adding additional line reactance
Experimental Analysis of Neighborhood Effects
Families, primarily female-headed minority households with children, living in high-poverty public housing projects in five U.S. cities were offered housing vouchers by lottery in the Moving to Opportunity program. Four to seven years after random assignment, families offered vouchers lived in safer neighborhoods that had lower poverty rates than those of the control group not offered vouchers. We find no significant overall effects of this intervention on adult economic self-sufficiency or physical health. Mental health benefits of the voucher offers for adults and for female youth were substantial. Beneficial effects for female youth on education, risky behavior, and physical health were offset by adverse effects for male youth. For outcomes exhibiting significant treatment effects, we find, using variation in treatment intensity across voucher types and cities, that the relationship between neighborhood poverty rate and outcomes is approximately linear.
Moving to Opportunity in Boston: Early Results of a Randomized Mobility Experiment
This paper examines the short-run impacts of a change in residential neighborhood on the well-being of low-income families, using evidence from the Moving To Opportunity (MTO) program in which eligibility for a housing voucher was determined by random lottery. Applicants in high poverty public housing projects were assigned by lottery to one of three groups: Experimental offered mobility counseling and a voucher valid only in a low-poverty Census tract; Section 8 Comparison offered a geographically unrestricted voucher; or Control offered no new assistance, but continued eligibility for public housing. Our quantitative analyses of program impacts at the Boston site of MTO uses data on 540 families approximately two years after program enrollment. 48 percent of the Experimental group and 62 percent of the Section 8 Comparison group moved through the MTO program. Households in both treatment groups experienced improvements in multiple measures of well-being relative to the Control group including increased safety, improved health among household heads, and fewer behavior problems among boys. There were no significant short-run impacts of either MTO treatment on employment, earnings, or welfare receipt. Experimental group children were less likely to be personally victimized by crime, to be injured, or to experience an asthma attack.
Slingshot non-sequential double ionization as a gate to anti-correlated two electron escape
At intensities below-the-recollision threshold, we show that
re-collision-induced excitation with one electron escaping fast after
re-collision and the other electron escaping with a time delay via a Coulomb
slingshot motion is one of the most important mechanisms of non-sequential
double ionization, for strongly-driven He at 400 nm. Slingshot-NSDI is a
general mechanism present for a wide range of low intensities and pulse
durations. Anti-correlated two-electron escape is its striking hallmark. This
mechanism offers an alternative explanation of anti-correlated two-electron
escape obtained in previous studies.Comment: 6 pages, 3 figure
Moving to Opportunity and Tranquility: Neighborhood Effects on Adult Economic Self-Sufficiency and Health From a Randomized Housing Voucher Experiment
neighborhood effects, housing vouchers
MITG Station 1 Build 1 and Build 2 Disassembly
No Abstract. There is a duplicate copy
Continuous image distortion by astrophysical thick lenses
Image distortion due to weak gravitational lensing is examined using a
non-perturbative method of integrating the geodesic deviation and optical
scalar equations along the null geodesics connecting the observer to a distant
source. The method we develop continuously changes the shape of the pencil of
rays from the source to the observer with no reference to lens planes in
astrophysically relevant scenarios. We compare the projected area and the ratio
of semi-major to semi-minor axes of the observed elliptical image shape for
circular sources from the continuous, thick-lens method with the commonly
assumed thin-lens approximation. We find that for truncated singular isothermal
sphere and NFW models of realistic galaxy clusters, the commonly used thin-lens
approximation is accurate to better than 1 part in 10^4 in predicting the image
area and axes ratios. For asymmetric thick lenses consisting of two massive
clusters separated along the line of sight in redshift up to \Delta z = 0.2, we
find that modeling the image distortion as two clusters in a single lens plane
does not produce relative errors in image area or axes ratio more than 0.5%Comment: accepted to GR
Steering proton migration in hydrocarbons using intense few-cycle laser fields
Proton migration is a ubiquitous process in chemical reactions related to
biology, combustion, and catalysis. Thus, the ability to control the movement
of nuclei with tailored light, within a hydrocarbon molecule holds promise for
far-reaching applications. Here, we demonstrate the steering of hydrogen
migration in simple hydrocarbons, namely acetylene and allene, using
waveform-controlled, few-cycle laser pulses. The rearrangement dynamics are
monitored using coincident 3D momentum imaging spectroscopy, and described with
a quantum-dynamical model. Our observations reveal that the underlying control
mechanism is due to the manipulation of the phases in a vibrational wavepacket
by the intense off-resonant laser field.Comment: 5 pages, 4 figure
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