24,503 research outputs found
Reconstruction of Initial Beam Conditions at the Exit of the DARHT II Accelerator
We consider a technique to determine the initial beam conditions of the DARHT
II Accelerator by measuring the beam size under three different magnetic
transport settings. This may be time gated to resolve the parameters as a
function of time within the 2000 nsec pulse. This technique leads to three
equations in three unknowns with solution giving the accelerator exit beam
radius, tilt and emittance. We find that systematic errors cancel and so are
not a problem in unfolding the initial beam conditions. Random uncorrelated
shot to shot errors can be managed by one of three strategies: 1) make the
transport system optically de-magnifying; 2) average over many individual
shots; or 3) make the random uncorrelated shot to shot errors sufficiently
small. The high power of the DARHT II beam requires that the beam transport
system leading to a radius measuring apparatus be optically magnifying. This
means that the shot to shot random errors must either be made small (less than
about 1%) or that we average each of the three beam radius determinations over
many individual shots.Comment: 3 pages, 3 figures, LINAC2000 paper TUB1
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Charitable giving to humanitarian organizations in Spain
This paper studies influences on private donations in Spain. After surveying economic theory and past empirical findings on charitable behavior, I introduce Spanish microdata from 1992 on giving to humanitarian organizations. Using binary and multinomial logit models, I probe the likelihood of giving to these organizations, as well as that of stating different reasons for not giving. I find that the variable that most strongly predicts giving is income, and that, while most respondents that do not give cite financial reasons, lack of knowledge of the charities better explains low giving among most specific demographic groups. I discuss the implications of these results for public policy and nonprofit management. Classification-JEL : L3.. Nonprofit organizations, philanthropy, Spanish economy.
The Arts Economy in 20 Cities: Where Does Atlanta Stand?
The tremendous growth that Atlanta has experienced over the past decade has catapulted the city into a major metropolitan hub. Along with this growth, many issues have gained significance with regards to plans for the city's future direction of growth. One sector in particular that demands greater attention is the area of non-profit arts and art policy. The arts and culture have many perceived benefits for a community. The arts are commonly thought to improve a community's cultural life, revitalize urban areas, and while they also provide a base of support for artists and art organizations, may also ultimately stimulate economic growth. These benefits are thought to yield other desirable outcomes such as a safe and agreeable downtown, and an attractive site for business relocation.Unfortunately, non-profit regional arts in Atlanta have faced challenges in the areas of funding and audience development and there is anecdotal evidence that arts support is being provided by a relatively small segment of society. The Atlanta Arts Think Tank perceived that one appropriate way to validate the importance of these problems was to analyze data on Atlanta's regional performance, relative to other metropolitan peers.The purpose of this study is to gain a better understanding of the factors that might explain the condition of arts organizations in the region. The study compares Atlanta to nineteen of its peers in an attempt to determine where and if Atlanta is falling short, and what can be learned from other communities
Waterfowl Harvest and Hunter Use at Carlyle Lake During the 1972 Season
Division of Wildlife Resources Migratory Bird Section, Periodic Report No. 1Report issued on: March 26, 197
Variation in a host-epiphyte relationship along a wave exposure gradient
The red alga Polysiphonia lanosa (L ) Tandy is an obligate epiphyte that primarily occurs on the fucoid brown algal basiphyte Ascophyllum nodosum (L) Le Jolis In the present study we examine how epiphytic interactions between P lanosa and A nodosum vary along a wave exposure gradient within the southern Gulf of Maine, USA P lanosa was most dense on protected shores, however because the stature of P lanosa was greater on exposed than on sheltered shores, greater biomass occurred In exposed habitats Epiphytlc P lanosa pnmanly attached to inlured vegetative bssue at exposed sites, while ~ t osc currence was primarily receptacular at sheltered sites A significantly stronger correlation was found between host receptacle abundance and epiphyte abundance at a protected low than an exposed site As a result, the distribution of epiphytes along the host S stlpe vanes at different sites We suggest that changes in the distribution and abundance of P lanosa across this wave exposure gradient are highly influenced by vanations in the distribution and persistence of suitable attachment sites on the host plant Because both the quantity and quality of attachment sites vanes w t h exposure, we hypothesize that d~fferenpt rocesses limit or de t e rm~neP lanosa populations in different locations In protected sites P lanosa may be limited by the presence of adequate substrata (inlured bssue and lateral pits) where successful recruitment may occur By contrast at exposed sites the supply of P lanosa sporelings, rather than quantity of appropnate substrata, may limlt population size
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