Elucidating the Correlation of the Quasar \ion{Fe}{2}/\ion{Mg}{2} Ratio with Redshift

Interpretation of the \ion{Fe}{2}(UV)/\ion{Mg}{2} emission ratios from quasars has a major cosmological motivation. Both Fe and Mg are produced by short-lived massive stars. In addition, Fe is produced by accreting white dwarf supernovae somewhat after star formation begins. Therefore, we expect that the Fe/Mg ratio will gradually decrease with redshift. We have used data from the Sloan Digital Sky Survey to explore the dependence of the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio on redshift and on luminosity in the redshift range of $0.75< z< 2.20$, and we have used predictions from our 830-level model for the \ion{Fe}{2} atom in photoionization calculations to interpret our findings. We have split the quasars into several groups based upon the value of their \ion{Fe}{2}(UV)/\ion{Mg}{2} emission ratios, and then checked to see how the fraction of quasars in each group varies with the increase of redshift. We next examined the luminosity dependence of the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio, and we found that beyond a threshold of \ion{Fe}{2}(UV)/\ion{Mg}{2} =~ 5, and $M_{2500} < -25\rm mag$, the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio increases with luminosity, as predicted by our model. We interpret our observed variation of the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio with redshift as a result of the correlation of redshift with luminosity in a magnitude limited quasar sample.Comment: ApJL accepte

Submillimeter Atmospheric Transparency at Maunakea, at the South Pole, and at Chajnantor

For a systematic assessment of submillimeter observing conditions at different sites, we constructed tipping radiometers to measure the broad band atmospheric transparency in the window around 350 $\mu$m wavelength. The tippers were deployed on Maunakea, Hawaii, at the South Pole, and in the vicinity of Cerro Chajnantor in northern Chile. Identical instruments permit direct comparison of these sites. Observing conditions at the South Pole and in the Chajnantor area are better than on Maunakea. Simultaneous measurements with two tippers demonstrate conditions at the summit of Cerro Chajnantor are significantly better than on the Chajnantor plateau.Comment: Accepted by PAS

The Intergenerational Effects of Early Childbearing

Since World War II, the average age at which women experience their first birth has drifted up, but since 1986 there has been a resurgence of births to teenagers. Just as early fertility appears to adversely affect the life chances of the teen mother, it may also have negative effects on her children. We hypothesize that when the children of teen mothers are young adults, they will tend to have lower education, and will be more likely to be economically inactive, to have children when they are teens, and to have children out of wedlock when they are teens. In this paper, we present several models designed to reveal the impact that being born to a teenage mother has on children's chances for success as young adults. Our findings indicate that the children of mothers who first gave birth as teens are adversely affected as young adults.

Do Teens Make Rational Choices? The Case of Teen Nonmarital Childbearing

With emphasis on the role of economic incentives, we explore the determinants of a woman’s choice of whether or not to give birth as an unmarried teenager. Our data are taken from the Panel Study of Income Dynamics. Guided by a simple utility-maximization model, we represent the income possibilities available to teenaged women if they do and do not give birth out of wedlock. We estimate these choice-conditioned income possibilities through a two-stage probit procedure, relying on the observed incomes of a secondary sample of somewhat older women. The response of the young women in our primary sample to these income expectations is measured after controlling for the effects of a variety of other factors, including the characteristics of the girl’s family, the social and economic environment in which she lives (including such policy-related factors as expenditures by states on family planning programs and education), and her own prior choices. We use the estimated structural parameters from our model to simulate the effects of a variety of policy interventions on the probability of becoming an unmarried teen mother. Our estimations provide evidence that income expectations have a persistent influence on the childbearing decision. They also provide evidence that the provision of public family planning expenditures and increases in parental education could reduce the prevalence of teen nonmarital births.

Delineation of the boundaries of a buried pre-glacial valley with LANDSAT-1 data

The continuity of a narrow meandering strip of Udoll (prairie) soils running east and west for approximately 40 miles across north central Indiana in an area predominantly of Udalfs (timber soils) was detected from LANDSAT-1 data taken on June 9, 1973. This data was processed through a clustering procedure and classified with resulting increased definition of the boundaries among soils grouped according to nine categories and vegetation to two categories of reflectance. This dark stretch of prairie soil is believed to have formed in the heavy textured, poorly drained glacial debris which filled a major pre-glacial tributary of the Teays River System. Ready identification and location of the valley has significance to soil survey and land classification people as a guide to soil classification and land use and to geologists as a guide to location of a potentially economically significant aquifer

Evaluation of materials and design modifications for aircraft brakes

A test program is described which was carried out to evaluate several proposed design modifications and several high-temperature friction materials for use in aircraft disk brakes. The evaluation program was carried out on a specially built test apparatus utilizing a disk brake and wheel half from a small het aircraft. The apparatus enabled control of brake pressure, velocity, and braking time. Tests were run under both constant and variable velocity conditions and covered a kinetic energy range similar to that encountered in aircraft brake service. The results of the design evaluation program showed that some improvement in brake performance can be realized by making design changes in the components of the brake containing friction material. The materials evaluation showed that two friction materials show potential for use in aircraft disk brakes. One of the materials is a nickel-based sintered composite, while the other is a molybdenum-based material. Both materials show much lower wear rates than conventional copper-based materials and are better able to withstand the high temperatures encountered during braking. Additional materials improvement is necessary since both materials show a significant negative slope of the friction-velocity curve at low velocities

Diagnostics of the structure of AGN's broad line regions with reverberation mapping data: confirmation of the two-component broad line region model

We re-examine the ten Reverberation Mapping (RM) sources with public data based on the two-component model of the Broad Line Region (BLR). In fitting their broad H-beta lines, six of them only need one Gaussian component, one of them has a double-peak profile, one has an irregular profile, and only two of them need two components, i.e., a Very Broad Gaussian Component (VBGC) and an Inter-Mediate Gaussian Component (IMGC). The Gaussian components are assumed to come from two distinct regions in the two-component model; they are Very Broad Line Region (VBLR) and Inter-Mediate Line region (IMLR). The two sources with a two-component profile are Mrk 509 and NGC 4051. The time lags of the two components of both sources satisfy $t_{IMLR}/t_{VBLR}=V^2_{VBLR}/V^2_{IMLR}$, where $t_{IMLR}$ and $t_{VBLR}$ are the lags of the two components while $V_{IMLR}$ and $V_{VBLR}$ represent the mean gas velocities of the two regions, supporting the two-component model of the BLR of Active Galactic Nuclei (AGN). The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR; consequently, the radius obtained from the R-L relationship mainly represent the radius of VBLR. Moreover, NGC 4051, with a lag of about 5 days in the one component model, is an outlier on the R-L relationship as shown in Kaspi et al. (2005); however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC, respectively.Comment: 7 pages, 5 figures. Accepted for publication in the Special Issue of Science in China (G) "Astrophysics of Black holes and Related Compact Objects

Stress, coping, and emotional distress of medically underserved lung and head-and-neck cancer patients

2019 Summer.Includes bibliographical references.The intent of this study was to investigate how lung cancer (LC) and head and neck cancer (HNC) patients who are medically underserved (i.e. uninsured, underinsured, low income) experience emotional distress (symptoms of depression and anxiety) after being diagnosed with LC or HNC. Participants were recruited from four Colorado hospitals. They completed a baseline survey which included measures of perceived stress, coping self-efficacy, depression symptoms, and anxiety symptoms. The Transactional Model of Stress and Coping (TMSC) was used as a theoretical guide for analyses about the relations of stress coping and emotional distress. When age, sex, and stage of cancer were controlled for, levels of perceived stress were observed to be positively associated with experience of emotional distress. Further, coping was shown to be an effective moderator of the relation of perceived stress to emotional distress. The TMSC is a functional theoretical model for organizing the understanding of stress, coping and emotional distress for medically underserved LC and HNC patients. Further research should be conducted to assess for changes in these variables overtime, particularly if psychological interventions can be used to influence each variable

Aerodynamic design of the contoured wind-tunnel liner for the NASA supercritical, laminar-flow-control, swept-wing experiment

An overview is presented of the entire procedure developed for the aerodynamic design of the contoured wind tunnel liner for the NASA supercritical, laminar flow control (LFC), swept wing experiment. This numerical design procedure is based upon the simple idea of streamlining and incorporates several transonic and boundary layer analysis codes. The liner, presently installed in the Langley 8 Foot Transonic Pressure Tunnel, is about 54 ft long and extends from within the existing contraction cone, through the test section, and into the diffuser. LFC model testing has begun and preliminary results indicate that the liner is performing as intended. The liner design results presented in this paper, however, are examples of the calculated requirements and the hardware implementation of them