Linking the 1940 U.S. Census with Modern Data

The U.S. Census Bureau has created a set of linkable census, survey, and administrative records that provides longitudinal data on the American population across the past eight decades. While these files include modern decennial censuses, Census Bureau surveys, and administrative records files from other federal agencies, the long time span is only possible with the addition of the complete count 1940 Census microdata. In this paper, we discuss the development of this linked data infrastructure and provide an overview of the record linkage techniques used. We primarily focus on the techniques used to produce a beta version of a linkable 1940 Census microdata file and discuss the potential to further document and extend the infrastructure.

Frozen Film and FOSDIC Forms: Restoring the 1960 U.S. Census of Population and Housing

In this article, the authors describe a collaboration of the Minnesota Population Center (MPC), the U.S. Census Bureau, and the National Archives and Records Administration to restore the lost data from the 1960 Census. The data survived on refrigerated microfilm in a cave in Lenexa, Kansas. The MPC is now converting the data to usable form. Once the restored data are processed, the authors intend to develop three new data sources based on the 1960 census. These data will replace the most inadequate sample in the series of public-use census microdata spanning the years from 1850 to 2000, extend the chronological scope of the public census summary files, and provide a powerful new resource for the Census Bureau and its Research Data Centers.

The calcium-induced curvature reversal of rat sperm is potentiated by cAMP and inhibited by anti-calmodulin

Rat sperm, demembranated with 0.1% Triton X-100, were used to explore the reversal in flagellar curvature induced by calcium ion. As reported earlier (Lindemann and Goltz, Cell Motil. Cytoskeleton, 10:420-431, 1988), the radius of curvature of the flagellar midpiece of rat sperm is controlled by the free Ca2+ concentration. A reversal of the direction of curvature (judged by the asymmetric sperm head) takes place at approximately 2.5 x 10(-6) M free Ca2+. In our current study, the time course of the curvature change, after elevating free Ca2+ to 3.5 x 10(-4) M, was utilized to assess the effects of the cAMP-kinase A pathway on the calcium response. In addition, calmodulin's involvement in this response was explored using anti-calmodulin and Cd2+. The activity state of the sperm models (which could be directly influenced through cAMP) was found to control the rate of curvature change in response to increased free Ca2+. In the most extreme case, fully quiescent sperm did not respond to Ca2+ at all, and cAMP-primed sperm models completed the response to Ca2+ in two minutes or less. Anti-calmodulin demonstrated strong inhibitory effects on the curvature reversal. Cadmium ion was also extremely potent at blocking the response to Ca2+, completely eliminating the curvature reversal at 2 x 10(-10) M free Cd2+. Based on these findings, it appears that the Ca(2+)-activated curvature reversal of rat sperm is potentiated by cAMP-dependent kinase and may be mediated through calmodulin.

Evidence for an increased sensitivity to Ca2+ in the flagella of sperm from tw32/+mice

The majority of sperm from mice carrying the tw32 haplotype undergo hyperactivation sooner than sperm from +/+ mice of the same strains (Olds-Clarke, Dev Biol 131:475-482, 1989). To investigate the mechanism underlying this abnormal motility, the Ca2+ sensitivity of their flagellar apparatus was compared to that of age- and strain-matched controls using Triton X-100-extracted sperm. Under these conditions, the curvature of the sperm flagellum is controlled by the free calcium concentration. Sperm from mice carrying the tw32 haplotype consistently exhibited a change in flagellar curvature at lower free calcium concentrations than controls. In addition, intact sperm from tw32/+ mice were much more likely than congenic control sperm to have a hook-like bend in the midpiece, which persisted throughout most of the beat cycle. Sperm exhibiting the hooked middle piece could be converted to a more normal appearance by 2 mM procaine, which immobilizes cytoplasmic calcium. Thus an increased sensitivity of the sperm motor apparatus to calcium could be the cause of the precocious hyperactivation of sperm from mice carrying the tw32 haplotype.

The interaction of pH and cyclic adenosine 3',5'-monophosphate on activation of motility in Triton X-100 extracted bull sperm

The motility of demembranated bull sperm was found to be governed by the concentrations of cyclic adenosine 3', 5'-monophosphate (cAMP) and Ca2+ at low pH (6.6-7.1), and was less sensitive to these variables at higher pH (7.4-7.8). Although motility was generally found to increase with increasing pH in the range from 6.6 to 7.8, the addition of exogenous cAMP markedly and selectively improved the motility at the lower end of the range (pH 6.6-7.1). In the presence of 10 microM cAMP, low Ca2+ (8.0 X 10(-8) M), and a high concentration of Mg-adenosine 5'-triphosphate (ATP, 8 mM), demembranated sperm at pH 6.8 and 7.1 exhibited swimming similar to that of live ejaculated sperm. At a free Ca2+ concentration of 4.4 X 10(-5) M, the motility was rapidly inhibited at pH 6.8-7.1, whereas at pH 7.4-7.8, the activity was not greatly affected. Since calcium is known to antagonize the cAMP pathway by activating Ca2+-dependent phosphodiesterase and Ca2+-dependent phosphatase, this further supports the idea that cAMP-dependent activation is crucial for motility at low pH. Our results demonstrate that the flagellar axoneme can function normally at relatively acidic pH, and produce vigorous swimming at high levels of ATP. The ATP content of live sperm was measured and found to be high enough (approximately 8 mM) to support the vigorous motility seen at pH 6.6-7.1 in the models.(ABSTRACT TRUNCATED AT 250 WORDS)