3,329 research outputs found
Labor Supply Effects of Social Insurance
This chapter examines the labor supply effects of social insurance programs. We argue that this topic deserves separate treatment from the rest of the labor supply literature because individuals may be imperfectly informed as to the rules of the programs and because key parameters are likely to differ for those who are eligible for social insurance programs, such as the disabled. Furthermore, differences in social insurance programs often provide natural experiments with exogenous changes in wages or incomes that can be used to estimate labor supply responses. Finally, social insurance often affects different margins of labor supply. For example, the labor supply literature deals mostly with adjustments in the number of hours worked, whereas the incentives of social insurance programs frequently affect the decision of whether to work at all. The empirical work on unemployment insurance (UI) and workers' compensation (WC) insurance finds that the programs tend to increase the length of time employees spend out of work. Most of the estimates of the elasticities of lost work time that incorporate both the incidence and duration of claims are close to 1.0 for unemployment insurance and between 0.5 and 1.0 for workers' compensation. These elasticities are substantially larger than the labor supply elasticities typically found for men in studies of the effects of wages or taxes on hours of work. The evidence on disability insurance and (especially) social security retirement suggests much smaller and less conclusively established labor supply effects. Part of the explanation for this difference probably lies in the fact that UI and WC lead to short-run variation in wages with mostly a substitution effect. Our review suggest that it would be misleading to apply a universal set of labor supply elasticities to these diverse problems and populations.
âA Rare BirdâŠ.â: Race, Masculinity, and the Community of Pilots in Postwar America
In the summer of 1969, one year after the assassination of the Rev. Martin Luther King, Jr. sparked race riots across the United States, Flying magazine published an article titled: âCan a Black Man Fly?â Despite the potentially provocative title, the author clearly had no doubts whether African Americans could master the complex technology of flight; that issue had been decisively settled during World War II by the famously successful Tuskegee Airmen. Instead, he wondered whether or not they were welcomed â or even allowed to enter â into the informal yet closely knit âcommunity of pilotsâ that dominated aviation in postwar America. His question reflected a stark demographic reality: most civilian aviators at the time were white. Although the federal government did not track the race of pilots, anecdotal evidence is overwhelming. During the decades following World War II, non-white pilots were almost entirely absent from the pages of mainstream aviation publications. And in an interview conducted years after Flying published this article, Jesse Lee Brown, an African American who earned his private pilotâs license shortly after returning home from the Vietnam War, joked that he was considered âa rare birdâ wherever he landed during flights around Alabama and neighboring states in the early 1970s. Even today, some estimates suggest that fewer than five percent of civilian pilots are non-white minorities.
The scarcity of non-white pilots is easy to explain in the immediate postwar era when racial segregation was legal in much of the country. Economics played a role, too. Private flying is expensive, and many minorities â who historically had lower incomes than their white counterparts â could not afford to become pilots even if they wanted to. However, formal barriers fell in the 1960s, informal attitudes regarding race began to change, and the economic prospects for minorities improved, yet private flying remained a mostly white activity. Why?
In addition to being mostly white, the community of pilots was also overwhelmingly male. In a book-length project nearing completion, I argue that postwar private fliers consciously created a culture that celebrated the mastery of technology as a hallmark of American masculinity. This, in turn, created an atmosphere in the cockpit and around the airport that, at the very least, made those who did not conform to these norms feel like unwelcome outsiders.
This conference paper represents the genesis of my next research project, in which I will examine the experiences of non-white pilots, especially African Americans. R.W. Connellâs path-breaking book Masculinities (1995) argues that different versions of masculinity, embraced by various subgroups of society, coexist side-by-side. This suggests that the masculine culture of postwar private aviation I describe in my first project was actually a form of white masculinity, created and defined by white males. Informed by Connellâs conclusions, as well as more recent work in the history of technology described in Amy Sue Bixâs bibliographic essay and other chapters in Bruce Sinclair, ed., Technology and the African-American Experience (2004), I argue that differing definitions of masculinity, as well as deep-rooted social and cultural expectations regarding who is (and is not) a pilot, help explain the longstanding dearth of non-white participants in private flying. This in turn helps shed light on the complex relationship amongst technical expertise, gender, and race.
Sources include the postwar experiences of former Tuskegee Airmen, records and oral history interviews related to the three largest organizations for African-American fliers in the U.S., articles from aviation magazines with a mostly white audience of licensed fliers, and popular publications aimed at minority, non-pilot audiences such as Ebony, Jet, and Black Enterprise
Electronic Intervention and Platforms and Their Impacts on Crowdfunding Behavior
Crowdfunding is a method of raising funds for projects, creative pursuits, peer-to-peer lending, and charitable causes. The idea of crowdfunding stems from the more encompassing concept of crowdsourcing, which refers not only to the gathering of funds, but to group participation in the convergence of ideas and content creation. Thus, crowdfunding can be considered to be one type of crowdsourcing. The following study examines the crowdfunding behavior of a sample of business professionals located in the service sector of metropolitan Pittsburgh, PA. In general, the empirical findings suggested that smaller goals tend to have better success ratios, while getting the targets achieved tends to attract more donors, especially when a goal is nearly met. Contrary to findings in some previous literature, there appears to be a weak link between respondentsâ social networking use and familiarity with crowdfunding. Furthermore, respondentsâ charitable giving habits did not closely link with crowdfunding solicitation behavior. Finally, there was a weak connection between crowdfunding behavior and income, but age did reveal a significant connection.
Interest in the project can be limiting. Some sites only focus on creative and fun projects. If the creatorâs project does not catch the attention and interest of donors, then it may receive little to no support. This can be made worse by similar projects competing for the same donors. The pool of donors may be limiting. Depending on the type and scope of the project, the amount and class of people a project will interest will be limited. Some sites only allow each donor to make a donation up to a certain amount so the number of donors would be very important. Other sites may require a minimum donation amount, so the class of donors targeted could be very important
Recent Developments in X-Ray Diagnostics for Cryogenic and Optically Dense Coaxial Rocket Sprays
The mixing and atomization of propellants is often characterized by optically dense flow fields and complex breakup dynamics. In the development of propulsion systems, the complexity of relevant physics and the range of spatio-temporal scales often makes computational simulation impractical for full scale injector elements; consequently, continued research into improved systems for experimental flow diagnostics is ongoing. One area of non-invasive flow diagnostics which has seen widespread growth is using synchrotron based x-ray diagostics. Over the past 3 years, a series of water and cryogenic based experiments were performed at the Advanced Photon Source, Argonne National Lab, on a NASA in-house designed swirl co-axial rocket injector, designed for operation using liquid oxygen and liquid methane in support of Project Morpheus. A range of techniques, such as x-ray fluorescence and time-averaged radiography were performed providing qualitative and quantitative mass and phase distributions, and were complemented by investigations using time-resolved radiography and white beam imaging, which provided information on breakup and mixing dynamics. Results of these investigations are presented, and conclusions regarding the viability of x-ray based diagnostics are discussed
Quantitative time-averaged gas and liquid distributions using x-ray fluorescence and radiography in atomizing sprays
A method for quantitative measurements of gas and liquid distributions is demonstrated using simultaneous x-ray fluorescence and radiography of both phases in an atomizing coaxial spray. Synchrotron radiation at 10.1 keV from the Advanced Photon Source at Argonne National Laboratory is used for x-ray fluorescence of argon gas and two tracer elements seeded into the liquid stream. Simultaneous time-resolved x-ray radiography combined with timeaveraged dual-tracer fluorescence measurements enabled corrections for reabsorption of x-ray fluorescence photons for accurate, line-of-sight averaged measurements of the distribution of the gas and liquid phases originating from the atomizing nozzle
Kidney and Pancreas Transplantation in the United States, 1998â2007: Access for Patients with Diabetes and End-Stage Renal Disease
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73092/1/j.1600-6143.2009.02566.x.pd
The SLAC highâdensity 3He target polarized by spinâexchange optical plumbing
A new highâdensity 3He target polarized by spin exchange with optically pumped rubidium vapor has recently been used at the Stanford Linear Accelerator in an experiment to measure the longitudinal spinâdependent structure function of the neutron. The 3He target operated at a density of 2.3Ă1020 atoms/cm3 in a 30 cm long scattering region with polarizations between 30% and 40% measured with NMR techniques. Target cells with several day spinârelaxation times were developed in order to achieve these polarizations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87509/2/244_1.pd
CMBPol Mission Concept Study: Prospects for polarized foreground removal
In this report we discuss the impact of polarized foregrounds on a future
CMBPol satellite mission. We review our current knowledge of Galactic polarized
emission at microwave frequencies, including synchrotron and thermal dust
emission. We use existing data and our understanding of the physical behavior
of the sources of foreground emission to generate sky templates, and start to
assess how well primordial gravitational wave signals can be separated from
foreground contaminants for a CMBPol mission. At the estimated foreground
minimum of ~100 GHz, the polarized foregrounds are expected to be lower than a
primordial polarization signal with tensor-to-scalar ratio r=0.01, in a small
patch (~1%) of the sky known to have low Galactic emission. Over 75% of the sky
we expect the foreground amplitude to exceed the primordial signal by about a
factor of eight at the foreground minimum and on scales of two degrees. Only on
the largest scales does the polarized foreground amplitude exceed the
primordial signal by a larger factor of about 20. The prospects for detecting
an r=0.01 signal including degree-scale measurements appear promising, with 5
sigma_r ~0.003 forecast from multiple methods. A mission that observes a range
of scales offers better prospects from the foregrounds perspective than one
targeting only the lowest few multipoles. We begin to explore how optimizing
the composition of frequency channels in the focal plane can maximize our
ability to perform component separation, with a range of typically 40 < nu <
300 GHz preferred for ten channels. Foreground cleaning methods are already in
place to tackle a CMBPol mission data set, and further investigation of the
optimization and detectability of the primordial signal will be useful for
mission design.Comment: 42 pages, 14 figures, Foreground Removal Working Group contribution
to the CMBPol Mission Concept Study, v2, matches AIP versio
- âŠ