130,504 research outputs found
Stewardship of very large digital data archives
An archive is a permanent store. There are relatively few very large digital data archives in existence. Most business records are expired within five or ten years. Many kinds of business records that do have long lives are embedded in data bases that are continually updated and re-issued cyclically. Also, a great deal of permanent business records are actually archived as microfilm, fiche, or optical disk images - their digital version being an operational convenience rather than an archive. The problems forseen in stewarding the very large digital data archives that will accumulate during the mission of the Earth Observing System (EOS) are addressed. It focuses on the function of shepherding archived digital data into an endless future. Stewardship entails storing and protecting the archive and providing meaningful service to the community of users. The steward will (1) provide against loss due to physical phenomena; (2) assure that data is not lost due to storage technology obsolescence; and (3) maintain data in a current formatting methodology
The TeV blazar Markarian 421 at the highest spatial resolution
We report the results obtained for the AGN Markarian 421 by model-fitting the
data in the visibility plane, studing the proper motion of jet components, the
light curve, and the spectral index of the jet features. We compare the radio
data with optical light curves obtained at the Steward Observatory, considering
also the optical polarization information. Mrk 421 has a bright nucleus and a
one-sided jet extending towards the north-west for a few parsecs. The
model-fits show that brightness distribution is well described using 6-7
circular Gaussian components, four of which are reliably identified at all
epochs; all components are effectively stationary except for component D, at
~0.4 mas from the core, whose motion is however subluminal. Analysis of the
light curve shows two different states, with the source being brighter and more
variable in the first half of 2011 than in the second half. The highest flux
density is reached in February. A comparison with the optical data reveals an
increase of the V magnitude and of the fractional polarization simultaneous
with the enhancement of the radio activity.Comment: 11 pages, 6 figure
Spectroscopic Classification of Post-AGB Candidates: (Searching for Proto-Planetary Nebulae)
We have determined the spectral classification of approximately 50 candidates for post-AGB, proto-planetary nebula (PPN) objects. The candidates were chosen based on their infrared excesses as seen in the IRAS data. The spectra are of low-resolution (R~550) and were obtained with the Kitt Peak National Observatory 2.1-m and the Steward Observatory 2.3-m telescopes. Spectroscopy has permitted us to discriminate between PPNe and other objects with dust, such as pre-main sequence stars and planetary nebulae. Most of the objects appear to be PPNe, ranging in spectral type from K to B, with some of the hotter ones showing hydrogen emission lines. A number of the objects have published classifications, which we list for comparison. Some were previously classified as PPNe but a few are new identifications. We are also carrying on a photometric monitoring program of many of these objects to study light variability. This research is supported by the NSF (most recently AST-1413660)
Protein synthesis at synaptic sites on dendrites
Studies over the past 20 years have revealed that gene expression in neurons is carried out by a distributed network of translational machinery. One component of this network is localized in dendrites, where polyribosomes and associated membranous elements are positioned beneath synapses and translate a particular population of dendritic mRNAs. The localization of translation machinery and mRNAs at synapses endows individual synapses with the capability to independently control synaptic strength through the local synthesis of proteins. The present review discusses recent studies linking synaptic plasticity to dendritic protein synthesis and mRNA trafficking and considers how these processes are regulated. We summarize recent information about how synaptic signaling is coupled to local translation and to the delivery of newly transcribed mRNAs to activated synaptic sites and how local translation may play a role in activity-dependent synaptic modification
To What Extent Does the Ideological Construct of Collectivism Continue to Govern the British Trade Union and Labour Movement?
This project addresses the issue of declining collectivism within the British labour movement. This paper will argue that recent changes in the structures of capitalism – such as flexible labour markets, belligerent state relations and private sector expansion – have successfully individualised the functionality of the labour movement. As a result of these developments the ability for trade unions to develop a collectivist social identity has been hindered, leading them to apply increasingly individualised strategies. Similarly, due to these changes, the British Labour Party has altered its traditional collectivist position leading to an erosion of the party-union relationship. Data has been drawn from secondary research accompanied by qualitative interviews to assess participants’ understanding of an ideological shift. It is concluded that trade unions will need to apply the dimensions of collectivism to a supply side environment by devolving democratic procedures and increasing democratic participation to modernise their activity
The optical spectrum of PKS 1222+216 and its black hole mass
We investigate the optical spectral properties of the blazar PKS 1222+216
during a period of 3 years. While the continuum is highly variable the broad
line emission is practically constant. This supports a scenario in which the
broad line region is not affected by jet continuum variations. We thus infer
the thermal component of the continuum from the line luminosity and we show
that it is comparable with the continuum level observed during the phases of
minimum optical activity. The mass of the black hole is estimated through the
virial method from the FWHM of MgII, Hbeta, and Halpha broad lines and from the
thermal continuum luminosity. This yields a consistent black hole mass value of
6x10^8 solar masses.Comment: 7 pages, 4 figures, accepted for publication in MNRA
Florida, State of (Human Services, Professional, Operational Services and Administrative and Clerical Units Agreement) and Florida Public Employees, American Federation of State, County and Municipal Employees (AFSCME) AFL-CIO, Council 79 (1998)
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The impact of financial histories on individuals and societies: A replication of and extension of Berg el al. (1995)
We replicate and extend the social history treatment of the Berg, Dickhaut, and McCabe (1995) investment game, to further document how the reporting of financial history influences how laboratory societies organize themselves over time. We replicate Berg et al. (1995) by conducting a No History and a Financial History session to determine whether a report summarizing the financial transactions of a previous experimental session will significantly reduce entropy in the amounts sent by Investors and returned by Stewards in the investment game, as Berg et al. (1995) found. We extend Berg et al. (1995) in two ways. First, we conduct a total of five sessions (one No History and four Financial History sessions). Second, we introduce Shannon's (1948) measure of entropy from information theory to assess whether the introduction of financial transaction history reduces the amount of dispersion in the amounts invested and returned across generations of players. Results across sessions indicate that entropy declined in both the amounts sent by Investors and the percentage returned by Stewards, but these patterns are weaker and mixed compared to those in the Berg et al. (1995) study. Additional research is needed to test how initial conditions, path dependencies, actors' strategic reasoning about others' behavior, multiple sessions, and communication may mediate the impact of financial history. The study's multiple successive Financial History sessions and entropy measure are new to the investment game literature
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