831 research outputs found
Influence of mollusk species on marine DELTA R determinations
Radiocarbon ages were measured on replicate samples of burnt grain and 5 mollusk species collected from a
single sealed layer at an archaeological site (Hornish Point) on the west coast of South Uist, Scotland. The aim was to examine
the impact of using different mollusk species on ΔR determinations that are calculated using the paired terrestrial/marine sample
approach. The mollusk species examined inhabit a range of environments and utilize a variety of food sources within the
intertidal zone. Several authors have suggested that these factors may be responsible for observed variations in the 14C activity
of mollusk shells that were contemporaneous in a single location. This study found no significant variation in the <sup>14</sup>C ages of
the mollusk species, and consequently, no significant variation in calculated values of ΔR. The implication is that in an area
where there are no carboniferous rocks or significant local inputs of freshwater to the surface ocean, any of a range of marine
mollusk species can be used in combination with short-lived terrestrial material from the same secure archaeological context
to accurately determine a ΔR value for a particular geographic location and period in time
<sup>14</sup>C AMS at SUERC: improving QA data from the 5 MV tandem AMS and 250 kV SSAMS
In 2003, a National Electrostatics Corporation (NEC) 5MV tandem accelerator mass spectrometer was installed at SUERC, providing the radiocarbon laboratory with 14C measurements to 4–5‰ repeatability. In 2007, a 250kV single-stage accelerator mass spectrometer (SSAMS) was added to provide additional 14C capability and is now the preferred system for 14C analysis. Changes to the technology and to our operations are evident in our copious quality assurance data: typically, we now use the 134-position MC-SNICS source, which is filled to capacity. Measurement of standards shows that spectrometer running without the complication of on-line δ13C evaluation is a good operational compromise. Currently, 3‰ 14C/13C measurements are routinely achieved for samples up to nearly 3 half-lives old by consistent sample preparation and an automated data acquisition algorithm with sample random access for measurement repeats. Background and known-age standard data are presented for the period 2003–2008 for the 5MV system and 2007–2008 for the SSAMS, to demonstrate the improvements in data quality
Targeting lentiviral vectors to antigen-specific immunoglobulins
Gene transfer into B cells by lentivectors can provide an alternative approach to managing B lymphocyte malignancies and autoreactive B cell-mediated autoimmune diseases. These pathogenic B cell Populations can be distinguished by their surface expression of monospecific immunoglobulin. Development of a novel vector system to deliver genes to these specific B cells could improve the safety and efficacy of gene therapy. We have developed an efficient rnethod to target lentivectors to monospecific immunoglobulin-expressing cells in vitro and hi vivo. We were able to incorporate a model antigen CD20 and a fusogenic protein derived from the Sindbis virus as two distinct molecules into the lentiviral Surface. This engineered vector could specifically bind to cells expressing Surface immunoglobulin recognizing CD20 (αCD20), resulting in efficient transduction of target cells in a cognate antigen-dependent manner in vitro, and in vivo in a xenografted tumor model. Tumor suppression was observed in vivo, using the engineered lentivector to deliver a suicide gene to a xenografted tumor expressing αCD20. These results show the feasibility of engineering lentivectors to target immunoglobulin-specific cells to deliver a therapeutic effect. Such targeting lentivectors also Could potentially be used to genetically mark antigen-specific B cells in vivo to study their B cell biology
A web of stakeholders and strategies: A case of broadband diffusion in South Korea
When a new technology is launched, its diffusion becomes an issue of importance. There are various stakeholders that influence diffusion. The question that remains to be determined is their identification and roles. This paper outlines how the strategies pursued by a government acting as the key stakeholder affected the diffusion of a new technology. The analysis is based on a theoretical framework derived from innovation diffusion and stakeholder theories. The empirical evidence comes from a study of broadband development in South Korea. A web of stakeholders and strategies is drawn in order to identify the major stakeholders involved and highlight their relations. The case of South Korea offers implications for other countries that are pursuing broadband diffusion strategies
Statewide geographic variation in outcomes for adults with acute myeloid leukemia in North Carolina
BACKGROUND: Population-based studies have demonstrated survival disparities related to socioeconomic factors for patients with acute myeloid leukemia (AML). The objective of the current study was to determine whether the local health care infrastructure, represented by Area Health Education Centers (AHEC) region, or treating center experience, represented by National Cancer Institute Comprehensive Cancer Center (NCICCC) designation, were associated with outcomes among patients with AML in North Carolina. METHODS: Patients who were diagnosed with AML from 2003 to 2009 were identified using the University of North Carolina Lineberger Integrated Cancer Information and Surveillance System, a database linking insurance claims to the North Carolina Cancer Registry. A Cox proportional-hazards model was used to explore survival based on AHEC region. A subset of patients who received inpatient chemotherapy was examined to evaluate the impact of treatment at an NCICCC. RESULTS: Nine hundred patients were identified in the study period, 553 of whom received inpatient chemotherapy therapy within 30 days of diagnosis. Almost one-half of these patients (n5294) received chemotherapy at a non-NCICCC. Among the patients who received intensive inpatient therapy, residence in 3 of 9 AHEC regions was associated with a higher risk of mortality (hazard ratio: range, 1.97-4.03; P<.01) at 1 year in multivariate analysis. Treatment at a non-NCICCC was not associated with an increased risk of mortality at 1 year (hazard ratio, 1.25; 95% confidence interval, 0.95-1.65). CONCLUSIONS: Survival among patients with AML in North Carolina varies according to geographic region. Further examination of local practice and referral patterns may inform strategies to improve AML outcomes across the state
Review of progress in Fast Ignition
Copyright 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 12(5), 057305, 2005 and may be found at http://dx.doi.org/10.1063/1.187124
On Quantum Control via Encoded Dynamical Decoupling
I revisit the ideas underlying dynamical decoupling methods within the
framework of quantum information processing, and examine their potential for
direct implementations in terms of encoded rather than physical degrees of
freedom. The usefulness of encoded decoupling schemes as a tool for engineering
both closed- and open-system encoded evolutions is investigated based on simple
examples.Comment: 12 pages, no figures; REVTeX style. This note collects various
theoretical considerations complementing/motivated by the experimental
demonstration of encoded control by Fortunato et a
Minimum Wages and Poverty with Income-Sharing
Textbook analysis tells us that in a competitive labor market, the introduction of a minimum wage in terms of poverty rather than in terms of unemployment. This paper makes three contributions to the basic theory of the minimum wage. First, we analyze the effects of a higher minimum wage in terms of poverty rather than in terms of unemployment. Second, we extend the standard textbook model to allow for income-sharing between employed and unemployed persons in society. Third, we extend the basic model to deal with income sharing within families. We find that there are situations in which a higher minimum wage raises poverty, others where it reduces poverty, and yet others in which poverty is unchanged. We characterize precisely how the poverty effect depends on four parameters: the degree of poverty aversion, the elasticity of labor demand, the ratio of the minimum wage to the poverty line, and the extent of income-sharing. Thus, shifting the perspective from unemployment to poverty leads to a considerable enrichment of the theory of the minimum wage
Uniform algebras and approximation on manifolds
Let be a bounded domain and let be a uniform algebra generated by a set
of holomorphic and pluriharmonic functions. Under natural assumptions on
and we show that the only obstruction to is that there is a holomorphic disk such that all functions in are holomorphic on , i.e., the
only obstruction is the obvious one. This generalizes work by A. Izzo. We also
have a generalization of Wermer's maximality theorem to the (distinguished
boundary of the) bidisk
Attentive Learning of Sequential Handwriting Movements: A Neural Network Model
Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)
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