13,864 research outputs found
Ion chambers simplify absolute intensity measurements in the vacuum ultraviolet
Single or double ion chamber technique measures absolute radiation intensities in the extreme vacuum ultraviolet region of the spectrum. The ion chambers use rare gases as the ion carrier. Photon absorbed by the gas creates one ion pair so a measure of these is a measure of the number of incident photons
Precautionary savings and wealth accumulation with parameter uncertainty and learning
This paper considers the intertemporal consumption/savings decision when income follows a random walk with drift and the drift coefficient is unknown. Instead agents are Bayesian learners, combining prior and sample information to form a posterior for the drift coefficient and future income. This parameter uncertainty increases by an order of magnitude the uncertainty of future income over that generated by unknown future shocks to income and can lead agents to have much more precautionary savings and hence to accumulate more wealth than otherwise. In a calibration exercise it is shown that for a plausible specification of the level of prior information and real interest rate, that the level of aggregate wealth due to this parameter uncertainty could be larger than that generated by unknown future shocks to income, the latter of which has been estimated elsewhere to potentially account for 60 percent of US aggregate wealth. --Permanent Income Hypothesis, Precautionary Savings, Parameter Uncertainty, Bayesian learning, Wealth Accumulation.
General practitioners' reasons for removing patients from their lists: postal survey in England and Wales
The removal of patients from doctors' lists causes conÂ
siderable public and political concern, with speculation
that patients are removed for inappropriate, including
financial, reasons. In 1999 the House of Commons
Select Committee on Public Administration noted that
little evidence was available on either the frequency of,
or the reasons for, removal of patients. National statistics do not distinguish between patients removed after
moving out of a practice area and those removed for
other reasons. Two postal surveys have reported why
general practitioners might, in general, remove
patients, and one small study has described the
reasons doctors give for particular removals. We
therefore determined the current scale of, and doctors'
reasons for, removal of patients from their lists in EngÂ
land and Wales
Constraining the Solution to the Last Parsec Problem with Pulsar Timing
The detection of a stochastic gravitational-wave signal from the
superposition of many inspiraling supermassive black holes with pulsar timing
arrays (PTAs) is likely to occur within the next decade. With this detection
will come the opportunity to learn about the processes that drive
black-hole-binary systems toward merger through their effects on the
gravitational-wave spectrum. We use Bayesian methods to investigate the extent
to which effects other than gravitational-wave emission can be distinguished
using PTA observations. We show that, even in the absence of a detection, it is
possible to place interesting constraints on these dynamical effects for
conservative predictions of the population of tightly bound supermassive
black-hole binaries. For instance, if we assume a relatively weak signal
consistent with a low number of bound binaries and a low black-hole-mass to
galaxy-mass correlation, we still find that a non-detection by a simulated
array, with a sensitivity that should be reached in practice within a few
years, disfavors gravitational-wave-dominated evolution with an odds ratio of
30:1. Such a finding would suggest either that all existing astrophysical
models for the population of tightly bound binaries are overly optimistic, or
else that some dynamical effect other than gravitational-wave emission is
actually dominating binary evolution even at the relatively high
frequencies/small orbital separations probed by PTAs.Comment: 14 pages, 8 figure
The oxidation of carbon monoxide using a tin oxide catalyst
This paper outlines some of the steps involved in the development by the United Kingdom Atomic Energy Authority (UKAEA) of a catalytic device for the recombination of carbon monoxide and oxygen in a CO2 laser system. It contrasts the differences between CO oxidation for air purification and for laser environmental control, but indicates that there are similarities between the physical specifications. The principal features of catalytic devices are outlined and some experimental work described. This includes measurements concerning the structure and mechanical properties of the artifact, the preparation of the catalyst coating and its interaction with the gaseous environment. The paper concludes with some speculation about the method by which the reaction actually occurs
Application of airborne infrared technology to monitor building heat loss
The application of airborne infrared technology to the requirements for energy conservation in buildings was studied. Quantitative airborne data of the City of Ypsilanti, Michigan, were collected and processed to identify roof temperatures. A thermal scanner was flown at an altitude of 1,200 feet with two thermal bands 8.2-9.3 micrometers and 10.4-12.5 micrometers recorded by an analog system. Calibration was achieved by standard hot and cold plates. Using a thermal model to interpret ceiling insulation status, environmental factors were found to influence the relation between roof temperature and insulation. These include interior and sky temperatures, roofing materials, and the pitch and orientation of the roof. A follow-up mail survey established the ability to identify insulated and uninsulated houses from the airborne infrared data
Preparing Aspiring Superintendents to Lead School Improvement: Perceptions of Graduates for Program Development
Changes in the design and delivery of educational leadership preparation programs are advocated in order to meet the needs of leadership for 21st century schools (Byrd, 2001; Cox, 2002; McKerrow, 1998; Smylie & Bennett, 2005). The changing needs of the 21st century, coupled with accountability standards and more diverse populations of students within school districts, create challenges for leaders who are attempting to increase student achievement (Firestone & Shipps, 2005; Schlechty, 2008). Further, student performance demands have increased at the state and national level because of the No Child Left Behind Act (Wong & Nicotera, 2007). These standards have thus increased the emphasis of the administrator\u27s responsibility to positively impact student achievement (Taylor, 2001). With the graying of the profession and the need for exemplary school superintendents, the preparation of school superintendents who can successfully lead school improvement is vitally important (Lashway, 2006). According to the National Council for the Accreditation of Teacher Education (NCATE, 2002), university preparation programs should seek current leaders\u27 perspectives of critical content components and the processes to be used in the preparation of educational leaders who can lead school improvement practices and processes
The Operational Loops of a Pandemic
This article analyses the visual operations of contagions and their material aftereffects. Data visualizations and diagrams have played a key role in the visual culture of the contagion, and this article explores especially two recurring themes: curves and simulations. The article will address the data diagrams that describe and predict, advise and control actions during the pandemic. We argue that these curves and simulations are also crucial epistemic and aesthetic occurrences that produce the long tail of the epidemic as it pertains to a variety of actions from policy-making to affective responses. Furthermore, the text investigates the theme of the operational loop in order to help us to grasp statistical curves and simulations as part of a multi-scalar logics of the epidemic image and in order to discuss the temporal modalities of these various images and diagrams. The article also includes David Benqué’s speculative diagrams of contagions loops that present an artistic response to the theoretical theme
- …