Little is known about the effects of the most recent welfare reform initiatives--which include work mandates, time limits, and enhanced earnings disregards--on children's outcomes. This is partly because the ways in which maternal employment and income affect children more generally are not well understood. This article describes the effects on child development of the Minnesota Family Investment Program (MFIP), a welfare program that began prior to 1996 federal welfare reform legislation. The present study utilized MFIP's unique, three-group research design to untangle the effects of different components of the program, and, in turn, discover how each component's effects on parents' income or employment affected children's development. This study's findings showed that MFIP increased employment rates and decreased poverty and, according to reports from mothers, children were less likely to exhibit problem behaviors and more likely to perform better and be more highly engaged in school. These findings, based on a total of 879 participants, bolster the long-standing literature that has associated poverty with worse outcomes for children by confirming, in a rigorous experiment, that incremental increases in income for working poor parents bring benefits to children.

DNA-mediated gene transfer (transfection) is used to introduce specific genes into vertebrate cells. Events soon after transfection were quantitatively analyzed by determining the infectivity of the DNA from an avian retrovirus and of mixtures of subgenomic fragments of this DNA. The limiting step of transfection with two DNA molecules is the uptake by a single cell of both DNA's in a biologically active state. Transfected cells mediate ligation and recombination of physically unlinked DNA's at nearly 100 percent efficiency.

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We document a negative association between nonmarital childbearing and the subsequent likelihood of first marriage in the United States, controlling for a variety of potentially confounding influences. Nonmarital childbearing does not appear to be driven by low expectations of future marriage. Rather, it tends to be an unexpected and unwanted event, whose effects on a woman's subsequent likelihood of first marriage are negative on balance. We find that women who bear a child outside marriage and who receive welfare have a particularly low probability of marrying subsequently, although there is no evidence that AFDC recipients have lower expectations of marriage. In addition, we find no evidence that stigma associated with nonmarital childbearing plays an important role in this process or that the demands of children significantly reduce unmarried mothers' time for marriage market activities.

We describe how pathway engineering can be used to convert a single intermediate derived from lipid biosynthesis, fatty aldehydes, into a variety of biofuel precursors including alkanes, free fatty acids and wax esters. In cyanobacteria, long-chain acyl-ACPs can be reduced to fatty aldehydes, and then decarbonylated to alkanes. We discovered a cyanobacteria class-3 aldehyde-dehydrogenase, AldE, that was necessary and sufficient to instead oxidize fatty aldehyde precursors into fatty acids. Overexpression of enzymes in this pathway resulted in production of 50 to 100 fold more fatty acids than alkanes, and the fatty acids were secreted from the cell. Co-expression of acyl-ACP reductase, an alcohol-dehydrogenase and a wax-ester-synthase resulted in a third fate for fatty aldehydes: conversion to wax esters, which accumulated as intracellular lipid bodies. Conversion of acyl-ACP to fatty acids using endogenous cyanobacterial enzymes may allow biofuel production without transgenesis.

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Monoclonal antibody interchain disulfide bond reduction was observed in a ChineseHamster Ovary manufacturing process that used single-use technologies. A similar reduction has been reported for processes that involved high mechanical shear recovery unit operations, such as continuous flow centrifugation and when the clarified harvest was stored under low dissolved oxygen (DO) conditions (Trexler-Schmidt et al., 2010. Biotechnology and Bioengineering, 106(3), 452-461). The work described here identifies disposable depth filtration used during cell culture harvest operations as a shear-inducing unit operation causing cell lysis. As a result, reduction of antibody interchain disulfide bonds was observed through the same mechanisms described for continuous flow centrifugation. Small-scale depth-filtration models were developed, and the differential pressure (ΔP) of the primary depth filter was identified as the key factor contributing to cell lysis. Strong correlations of ΔP and cell lysis were generated by measuring the levels of lactate dehydrogenase and thiol in the filtered harvest material. A simple risk mitigation strategy was implemented during manufacturing by providing an air overlay to the headspace of a single-use storage bag to maintain sufficient DO in the clarified harvest. In addition, enzymatic characterization studies determined that thioredoxin reductase and glucose-6phosphate dehydrogenase are critical enzymes involved in antibody reduction in a nicotinamide adenine dinucleotide phosphate (NADP + )/NADPH-dependent manner. K E Y W O R D Sair overlay, antibody, cell lysis, depth filtration, differential pressure, dissolved oxygen, disulfide reduction 1 | INTRODUCTION Monoclonal antibodies (mAbs) are commonly manufactured with fed-batch or perfusion mammalian cell culture processes. In such manufacturing processes, the mAb, which is expressed and secreted from the cell, accumulates in the cell culture fluid and is recovered using centrifugation and/or filtration. With the advent of high productivity (>5 g/L) cell culture processes and the availability of improved disposable technologies, the implementation of single-use systems, such as bioreactors, depth filters, columns, membranes, and bioprocess storage bags in the production of biologics has become standard industry practice (Liu, 2005).

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