A Search for Optical Variability of Type 2 Quasars in SDSS Stripe 82

Hundreds of Type 2 quasars have been identified in Sloan Digital Sky Survey (SDSS) data, and there is substantial evidence that they are generally galaxies with highly obscured central engines, in accord with unified models for active galactic nuclei (AGNs). A straightforward expectation of unified models is that highly obscured Type 2 AGNs should show little or no optical variability on timescales of days to years. As a test of this prediction, we have carried out a search for variability in Type 2 quasars in SDSS Stripe 82 using difference-imaging photometry. Starting with the Type 2 AGN catalogs of Zakamska et al. (2003) and Reyes et al. (2008), we find evidence of significant g-band variability in 17 out of 173 objects for which light curves could be measured from the Stripe 82 data. To determine the nature of this variability, we obtained new Keck spectropolarimetry observations for seven of these variable AGNs. The Keck data show that these objects have low continuum polarizations (p<~1% in most cases) and all seven have broad H-alpha and/or MgII emission lines in their total (unpolarized) spectra, indicating that they should actually be classified as Type 1 AGNs. We conclude that the primary reason variability is found in the SDSS-selected Type 2 AGN samples is that these samples contain a small fraction of Type 1 AGNs as contaminants, and it is not necessary to invoke more exotic possible explanations such as a population of "naked" or unobscured Type 2 quasars. Aside from misclassified Type 1 objects, the Type 2 quasars do not generally show detectable optical variability over the duration of the Stripe 82 survey.Comment: 14 pages, 8 figures. Accepted for publication in A

Array phasing device Patent

Apparatus for generating microwave signals at progressively related phase angles for driving antenna arra

Overall Declines in Child Poverty Mask Relatively Stable Rates Across States

In this brief, authors Andrew Schaefer, Jessica Carson, and Marybeth Mattingly use Census data released on September 15, 2016, from the American Community Survey--the only regular source for estimating yearly child poverty rates at, and below, the state level--to examine child poverty rates across the United States by place type, region, and state. They report that between 2014 and 2015, child poverty declined nationwide across rural areas, suburbs, and cities. As before, cities had the highest child poverty, followed closely by rural areas. Suburbs had the lowest rates. In thirteen states, child poverty declined since 2014; only Mississippi saw an increase since 2014, and the remaining thirty-six states and the District of Columbia had stable rates. Mississippi, New Mexico, and Louisiana had exceptionally high child poverty rates, each over 28 percent. New Hampshire child poverty was among the lowest nationwide, at 10.7 percent. It is important to keep in mind that most states experienced no change between 2014 and 2015. Lower child poverty rates appear to be driven by higher median incomes over the past year

Cause for Optimism? Child Poverty Declines for the First Time Since Before the Great Recession

New data released on September 18, 2014, by the U.S. Census Bureau indicate that child poverty fell by 0.4 percentage point between 2012 and 2013, to 22.2 percent. Though still significantly higher than in 2007 when the Great Recession hit (18.0 percent), and higher than at its conclusion (20.0 percent) in 2009, the decline from 2012 may be cause for optimism. Estimates suggest the number of poor children declined by roughly 300,000 between 2012 and 2013

Child Care Costs Exceed 10 Percent of Family Income for One in Four Families

In this brief, authors Marybeth Mattingly, Andrew Schaefer, and Jessica Carson analyze families’ child care expenses and identify, among families with young children who pay for child care, the share that are “cost burdened,” defined in this context as spending more than 10 percent of their gross income on child care. Using data from the 2012–2016 Current Population Survey, they present their findings by number of children; age of youngest child; parental characteristics; family income measures; and U.S. region, metropolitan status, and state. They report that about one in four families with young children who have child care costs are “burdened” by the cost, spending more than 10 percent of family income on child care. Across families with young children, an average of 8.8 percent of family income is spent on child care. More than half of poor families with young children are cost burdened by child care, compared to 39.3 percent of low income families (those with incomes between one and two times the poverty threshold) and just 13.4 percent of families at or above five times the poverty threshold. One in five married couples, and two in five single parents with young children and child care expenses, pay more than 10 percent of their income on these costs. Access to quality, affordable child care is critical for American working families

2016 Child Poverty Rate Sees Largest Decline Since Before Great Recession

Child poverty declined by 1.2 percentage points between 2015 and 2016, according to analyses of the official poverty measure (OPM) in the latest American Community Survey

Gains in Reducing Child Poverty, but Racial-Ethnic Disparities Persist

In this brief, authors Jessica Carson, Marybeth Mattingly, and Andrew Schaefer use data from the American Community Survey to investigate patterns of child poverty across race-ethnicities and across regions and place types. They also explore changes in child poverty rates since 2014 and since the end of the Great Recession in 2009. The authors report that between 2014 and 2015, child poverty fell for all race-ethnicities except Asians. The largest declines in child poverty occurred among blacks and Hispanics, and the poverty gap between them and white and Asian children narrowed, although these groups’ poverty rates are far from converging. Given the well-established connection between child poverty and brain development, educational attainment, later labor market participation, and long-term health outcomes, the high disparities in child poverty in the United States are of particular concern. Closer attention to these disparities may nudge policy makers to think carefully about the context of place in efforts to alleviate poverty and increase youth opportunity

Entanglement of two qubits in a relativistic orbit

The creation and destruction of entanglement between a pair of interacting two-level detectors accelerating about diametrically opposite points of a circular path is investigated. It is found that any non-zero acceleration has the effect of suppressing the vacuum entanglement and enhancing the acceleration radiation thereby reducing the entangling capacity of the detectors. Given that for large accelerations the acceleration radiation is the dominant effect, we investigate the evolution of a two detector system initially prepared in a Bell state using a perturbative mater equation and treating the vacuum fluctuations as an unobserved environment. A general function for the concurrence is obtained for stationary and symmetric worldlines in flatspace. The entanglement sudden death time is computed.Comment: v2: Some typo's fixed, figures compressed to smaller filesize and added some references

Booster propulsion/vehicle impact study, 2

This is the final report in a study examining the impact of launch vehicles for various boost propulsion design options. These options included: differing boost phase engines using different combinations of fuels and coolants to include RP-1, methane, propane (subcooled and normal boiling point), and hydrogen; variable and high mixture ratio hydrogen engines; translating nozzles on boost phase engines; and cross feeding propellants from the booster to second stage. Vehicles examined included a fully reusable two stage cargo vehicle and a single stage to orbit vehicle. The use of subcooled propane as a fuel generated vehicles with the lowest total vehicle dry mass. Engines with hydrogen cooling generated only slight mass reductions from the reference, all-hydrogen vehicle. Cross feeding propellants generated the most significant mass reductions from the reference two stage vehicle. The use of high mixture ratio or variable mixture ratio hydrogen engines in the boost phase of flight resulted in vehicles with total dry mass 20 percent greater than the reference hydrogen vehicle. Translating nozzles for boost phase engines generated a heavier vehicle. Also examined were the design impacts on the vehicle and ground support subsystems when subcooled propane is used as a fuel. The most significant cost difference between facilities to handle normal boiling point versus subcooled propane is 5 million dollars. Vehicle cost differences were negligible. A significant technical challenge exists for properly conditioning the vehicle propellant on the ground and in flight when subcooled propane is used as fuel

The Rachel Carson Letters and the Making of Silent Spring

Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance