The Employment and Earnings Impacts of the Targeted Jobs Tax Credit

The Targeted Jobs Tax Credit (TJTC) is intended to stimulate the employment of individuals who are members of certain groups of the labor force by providing a wage subsidy (in the form of a tax credit) to employers of recently-hired eligible workers. This intervention into the labor market has direct and indirect earnings and employment consequences for both eligible and ineligible individuals. The paper evaluates the impacts of TJTC by using a treatment and comparison group methodology. Corrections for nonrandom selection are undertaken. The primary sources of data are state quarterly wage record data from the Unemployment Insurance system and the Employment Service Automated Reporting System (ESARS). The results indicate that the availability and usage of TJTC enhances outcomes for nonwhite male youth (both eligible and ineligible), but is stigmatizing for eligible individuals from other race/sex groups, who appear to be slightly worse off because of the program than their ineligible counterparts. Obtaining a voucher increases employment and wages, but it appears as if selection effects are responsible. Importantly, the improved outcomes are not accompanied by displacement effects. Finally, being certified results in increased wages, but higher turnover and lower total employment.targeted, tax, job, credit, employment, earnings, Hollenbeck, Willke

Stabilized lasers for advanced gravitational wave detectors

Second-generation interferometric gravitational wave detectors require high-power lasers with approximately 200 W of output power in a linear polarized, single-frequency, fundamental-mode laser beam. Furthermore very high temporal and spatial stability is required. This paper discusses the design of a 200 W pre-stabilized laser (PSL) system and the underlying concepts. The PSL requirements for advanced gravitational wave detectors as well as for the laser system are described. The laser stabilization scheme proposed for the Advanced LIGO gravitational wave detector and the so-called diagnostic breadboard will serve as examples to explain the general laser stabilization concepts and the achieved performance and its limitations

Optical characterization of ultra-high diffraction efficiency gratings

We report on the optical characterization of an ultra-high diffraction efficiency grating in 1st order Littrow configuration. The apparatus used was an optical cavity built from the grating under investigation and an additional high reflection mirror. Measurement of the cavity finesse provided precise information about the grating's diffraction efficiency and its optical loss. We measured a finesse of 1580 from which we deduced a diffraction efficiency of (99.635$\pm$0.016)% and an overall optical loss due to scattering and absorption of just 0.185 %. Such high quality gratings, including the tool used for their characterization, might apply for future gravitational wave detectors. For example the demonstrated cavity itself presents an all-reflective, low-loss Fabry-Perot resonator that might replace conventional arm cavities in advanced high power Michelson interferometers

Laser power stabilization for second-generation gravitational wave detectors

We present results on the power stabilization of a Nd:YAG laser in the frequency band from 1 Hz to 100 kHz. High-power, low-noise photodetectors are used in a dc-coupled control loop to achieve relative power fluctuations down to 5×10−9 Hz−1/2 at 10 Hz and 3.5×10−9 Hz−1/2 up to several kHz, which is very close to the shot-noise limit for 80 mA of detected photocurrent on each detector. We investigated and eliminated several noise sources such as ground loops and beam pointing. The achieved stability level is close to the requirements for the Advanced LIGO gravitational wave detector

Frequency stabilization of a monolithic Nd:YAG ring laser by controlling the power of the laser-diode pump source

The frequency of a 700mW monolithic non-planar Nd:YAG ring laser (NPRO) depends with a large coupling coefficient (some MHz/mW) on the power of its laser-diode pump source. Using this effect we demonstrate the frequency stabilization of an NPRO to a frequency reference by feeding back to the current of its pump diodes. We achieved an error point frequency noise smaller than 1mHz/sqrt(Hz), and simultaneously a reduction of the power noise of the NPRO by 10dB without an additional power stabilization feed-back system.Comment: accepted for publication by Optics Letter

Frequency domain interferometer simulation with higher-order spatial modes

FINESSE is a software simulation that allows to compute the optical properties of laser interferometers as they are used by the interferometric gravitational-wave detectors today. It provides a fast and versatile tool which has proven to be very useful during the design and the commissioning of gravitational-wave detectors. The basic algorithm of FINESSE numerically computes the light amplitudes inside an interferometer using Hermite-Gauss modes in the frequency domain. In addition, FINESSE provides a number of commands to easily generate and plot the most common signals like, for example, power enhancement, error or control signals, transfer functions and shot-noise-limited sensitivities. Among the various simulation tools available to the gravitational wave community today, FINESSE is the most advanced general optical simulation that uses the frequency domain. It has been designed to allow general analysis of user defined optical setups while being easy to install and easy to use.Comment: Added an example for the application of the simulation during the commisioning of the GEO 600 gravitational-wave detecto

Dislocated Worker Human Capital Depreciation and Recovery

Previous studies have estimated the "human capital depreciation" of women re-entering the work force after voluntary, lengthy interruptions. Those studies have found reduced real wages and furthermore the decrease is positively related to the length of the interruption. Upon re-entry, however, real wages grow rapidly as human capital is restored. This paper develops a model of the wage histories of dislocated workers. Similar to labor force re-entrants, those dislocated workers who become re-employed would experience wages below their final wage prior to dislocation and the decrease should be associated with the length of dislocation. However, the model suggests that since the career disruptions are involuntary and since occupational shifts generally occur, recovery will not be rapid nor complete. The model is estimated with data from a sample of workers in Ohio who had been dislocated and received services under Title III of the Job Training Partnership Act (JTPA). This data set has the limitation that the observations are for workers who chose to receive services, but it also has the advantage that the effects of a variety of training interventions on outcomes can be determined.dislocated, workers, JTPA, Hollenbeck

Physical Acoustics

Contains report on one research project.U. S. Navy (Office of Naval Research) under Contract Nonr-1841(42