The Transition from Welfare to Work

We consider the effects the child care market, child care vouchers, early childhood education programs, and welfare reforms have on welfare recipients in their transition from welfare to work. Specifically, we are interested in determining which factors encourage single mothers to move directly from welfare to work and which factors encourage the pursuit of additional schooling or job retraining before entering the labor market. Using Massachusetts data from July 1996 through August 1997, we find that the availability, quality, and cost of formal child care are all positively related to transiting directly from welfare to work. We also find that single mothers with older children are more likely to pursue a job and forego additional schooling, while single mothers with infants are more likely to advance their education before seeking employment.Welfare Reform, Child Care, Vouchers, Time Limits, Labor Supply

The Transition from Welfare to Work

We consider the effects the child care market, early care and education programs, and welfare reforms have on welfare recipients’ transition from welfare to work. Using 1996-1997 data for Massachusetts, we find that the availability and quality of formal child care, the presence of Head Start and Pre-K programs, and the probability of receiving a child care voucher are all positively related to transiting directly from welfare to work. Single mothers subject to work requirements are more likely to transit directly from assistance to work as well, while those not subject to work requirements are more likely to obtain additional education or job training.

Child Care and the Welfare to Work Transition

We assess the role of child care in the welfare to work transition using an unusually large and comprehensive data base. Our data are for Massachusetts, a state that began welfare reform in 1995 under a federal waiver, for the period July 1996 through August 1997. We find that both the nature of the child care market and the availability of subsidized care and early education affect the probability that current and former welfare recipients will work. Regarding the child care market, we find that the cost, stability and quality of care matter. We also find that child care subsidies and some types of early education serve to increase employment. To be more specific, we find that increased funding for child care subsidies and the availability of full day kindergarten significantly increase the probability the current and former welfare recipients work.

Computer techniques for sensor validation during EBR-II natural circulation

"November, 1984.""Includes MIT technical contributions from D.D. Lanning, J.E. Meyer, A.L. Schor, R.J. Witt and R.D. Wittmeier.""U.S. Dept. of Energy Breeder Technology Program, Division of Educational Programs, Argonne National Laboratory."Includes bibliographical references (leaf 17)Final project report; November, 198

Vasoprotective effects of human CD34+ cells: towards clinical applications

<p>Abstract</p> <p>Background</p> <p>The development of cell-based therapeutics for humans requires preclinical testing in animal models. The use of autologous animal products fails to address the efficacy of similar products derived from humans. We used a novel immunodeficient rat carotid injury model in order to determine whether human cells could improve vascular remodelling following acute injury.</p> <p>Methods</p> <p>Human CD34+ cells were separated from peripheral buffy coats using automatic magnetic cell separation. Carotid arterial injury was performed in male Sprague-Dawley nude rats using a 2F Fogarty balloon catheter. Freshly harvested CD34+ cells or saline alone was administered locally for 20 minutes by endoluminal instillation. Structural and functional analysis of the arteries was performed 28 days later.</p> <p>Results</p> <p>Morphometric analysis demonstrated that human CD34+ cell delivery was associated with a significant reduction in intimal formation 4 weeks following balloon injury as compared with saline (I/M ratio 0.79 ± 0.18, and 1.71 ± 0.18 for CD34, and saline-treated vessels, respectively P < 0.05). Vasoreactivity studies showed that maximal relaxation of vessel rings from human CD34+ treated animals was significantly enhanced compared with saline-treated counterparts (74.1 ± 10.2, and 36.8 ± 12.1% relaxation for CD34+ cells and saline, respectively, P < 0.05)</p> <p>Conclusion</p> <p>Delivery of human CD34+ cells limits neointima formation and improves arterial reactivity after vascular injury. These studies advance the concept of cell delivery to effect vascular remodeling toward a potential human cellular product.</p

Demonstration of methods for analytical measurement of natural circulation flow in EBR-II

Statement of responsibility on title page reads: R. J. Witt and J. E. Meyer, Includes MIT technical contributions from J. I. Choi, D. D. Lanning, J. E. Meyer, A. L. Schor, R. J. Witt and R. D. Wittmeier.""February, 1986."Includes bibliographical references (leaf 44)Final project reportSupported by U.S. Dept. of Energy, Breeder Technology Program, Division of Educational Programs, Argonne National Laborator

A Model-based Approach to Controlling the ST-5 Constellation Lights-Out Using the GMSEC Message Bus and Simulink

Space Technology 5 (ST-5) is a three-satellite constellation, technology validation mission under the New Millennium Program at NASA to be launched in March 2006. One of the key technologies to be validated is a lights-out, model-based operations approach to be used for one week to control the ST-5 constellation with no manual intervention. The ground architecture features the GSFC Mission Services Evolution Center (GMSEC) middleware, which allows easy plugging in of software components and a standardized messaging protocol over a software bus. A predictive modeling tool built on MatLab's Simulink software package makes use of the GMSEC standard messaging protocol to interface to the Advanced Mission Planning System (AMPS) Scenario Scheduler which controls all activities, resource allocation and real-time re-profiling of constellation resources when non-nominal events occur. The key features of this system, which we refer to as the ST-5 Simulink system, are as follows: Original daily plan is checked to make sure that predicted resources needed are available by comparing the plan against the model. As the plan is run in real-time, the system re-profiles future activities in real-time if planned activities do not occur in the predicted timeframe or fashion. Alert messages are sent out on the GMSEC bus by the system if future predicted problems are detected. This will allow the Scenario Scheduler to correct the situation before the problem happens. The predictive model is evolved automatically over time via telemetry updates thus reducing the cost of implementing and maintaining the models by an order of magnitude from previous efforts at GSFC such as the model-based system built for MAP in the mid-1990's. This paper will describe the key features, lessons learned and implications for future missions once this system is successfully validated on-orbit in 2006

Multi-Decadal Decline of Mercury in the North Atlantic Atmosphere Explained by Changing Subsurface Seawater Concentrations

[1] We analyze 1977–2010 trends in atmospheric mercury (Hg) from 21 ship cruises over the North Atlantic (NA) and 15 over the South Atlantic (SA). We find a steep 1990–2009 decline of −0.046 ± 0.010 ng m−3 a−1 (−2.5% a−1) over the NA (steeper than at Northern Hemispheric land sites) but no significant decline over the SA. Surface water Hg0 measurements in the NA show a decline of −5.7% a−1since 1999, and limited subsurface ocean data show an ∼80% decline from 1980 to present. We use a coupled global atmosphere-ocean model to show that the decline in NA atmospheric concentrations can be explained by decreasing oceanic evasion from the NA driven by declining subsurface water Hg concentrations. We speculate that this large historical decline of Hg in the NA Ocean could have been caused by decreasing Hg inputs from rivers and wastewater and by changes in the oxidant chemistry of the atmospheric marine boundary layer.Engineering and Applied Science