995 research outputs found
2006 Status of the Momentum eXchange Electrodynamic Re-Boost (MXER) Tether Development
The MXER Tether technology development is a high-payoff/high-risk investment area within the NASA In-Space Propulsion Technology (ISPT) Program. The ISPT program is managed by the NASA Headquarters Science Mission Directorate and implemented by the Marshall Space Flight Center in Huntsville, Alabama. The MXER concept was identified and competitively ranked within NASA's comprehensive Integrated In-Space Transportation Plan (IISTP); an agency-wide technology assessment activity. The objective of the MXER tether project within ISPT is to advance the technological maturation level for the MXER system, and its subsystems, as well as other space and terrestrial tether applications. Recent hardware efforts have focused on the manufacturability of space-survivable high-strength tether material and coatings, high-current electrodynamic tether, lightweight catch mechanism, high-accuracy propagator/predictor code, and efficient electron collection/current generation. Significant technical progress has been achieved with modest ISPT funding to the extent that MXER has evolved to a well-characterized system with greater capability as the design has been matured. Synergistic efforts in high-current electrodynamic tethers and efficient electron collection/current generation have been made possible through SBIR and STTR support. The entire development endeavor was orchestrated as a collaborative team effort across multiple individual contracts and has established a solid technology resource base, which permits a wide variety of future space cable/tether applications to be realized
Elliptic flow fluctuations in Au+Au collisions at GeV
Please note that after these results were reported at Quark Matter 2006 and
posted on the preprint server it was found that what is reported here as
\textit{elliptic flow fluctuations}, should rather be taken as an upper limit
on the fluctuations. Further analysis has shown that fitting the multiplicity
dependence of the q-distribution does not enable one to disentangle non-flow
and fluctuations. The data from the q-vector distrubution does not, therefore,
exclude the case of zero fluctuations. The remainder of these proceedings we
leave as they were originally reported.Comment: Statements regarding disentangling non-flow and fluctuations by
examining the multiplicity dependence of the q-vector distributions are
retracted: data presented here on elliptic flow fluctuations should be taken
as an upper limit on the fluctuation
Increases in ROPS Pricing from 2006-2012 and the Impact on ROPS Demand
In 2006, a social marketing campaign was developed to increase the installation of rollover protective structures (ROPS) on unprotected New York tractors. Using data gathered from the program\u27s hotline, the impact of price increases on farmers\u27 interest in ROPS is examined. Pricing data were obtained for all rigid ROPS kits commercially available in the U.S. since 2006. These data were stratified into two groups of ROPS suppliers: (1) tractor manufacturers that sell ROPS for their own tractors, referred to in this study as original equipment manufacturers (OEMs), and (2) aftermarket (AM) ROPS suppliers. The trend in price increases was contrasted with the change in the consumer price index (CPI), the probability of retrofitting within quintiles of cost was estimated, and the increase in ROPS prices over time was plotted The average price increase for a ROPS kit (excluding shipping and installation) over the six years of the study was 23.3% for OEM versus 60.5% for AM (p \u3c 0.0001). Out-of-pocket expenses held steady for OEM versus a six-year increase of $203 for AM (p = 0.098). The probability of a farmer retrofitting dropped monotonically from 66.9% in the lowest ROPS cost quintile to 23% in the highest. If these trends continue, the proportion of inquiries resulting in a ROPS retrofit will fall below 20% by 2020 for AM ROPS. Based on other trends identified in the literature, it is reasonable to assume that decreases in ROPS installation are likely to affect the tractor owners who are most likely to need these safety devices
Symmetric Grothendieck polynomials, skew Cauchy identities, and dual filtered Young graphs
Symmetric Grothendieck polynomials are analogues of Schur polynomials in the
K-theory of Grassmannians. We build dual families of symmetric Grothendieck
polynomials using Schur operators. With this approach we prove skew Cauchy
identity and then derive various applications: skew Pieri rules, dual
filtrations of Young's lattice, generating series and enumerative identities.
We also give a new explanation of the finite expansion property for products of
Grothendieck polynomials
A Gaussian Theory of Superfluid--Bose-Glass Phase Transition
We show that gaussian quantum fluctuations, even if infinitesimal, are
sufficient to destroy the superfluidity of a disordered boson system in 1D and
2D. The critical disorder is thus finite no matter how small the repulsion is
between particles. Within the gaussian approximation, we study the nature of
the elementary excitations, including their density of states and mobility edge
transition. We give the gaussian exponent at criticality in 1D and show
that its ratio to of the pure system is universal.Comment: Revtex 3.0, 11 pages (4 figures will be sent through airmail upon
request
Human small cell lung cancer NYH cells resistant to the bisdioxopiperazine ICRF-187 exhibit a functional dominant Tyr165Ser mutation in the Walker A ATP binding site of topoisomerase IIα
AbstractBisdioxopiperazine anti-cancer agents are catalytic inhibitors of topoisomerase II which by unknown means lock the enzyme in a closed clamp form and inhibit its ATPase activity. In order to demarcate a putative pharmacophore, we here describe a novel Tyr165Ser mutation in the enzyme’s Walker A ATP binding site leading to specific bisdioxopiperazine resistance when transformed into a temperature-conditional yeast system. The Tyr165Ser mutation differed from a previously described Arg162Gln by being heterozygous and by purified Tyr165Ser enzyme being drug-resistant in a kinetoplast DNA decatenation enzymatic assay. This suggested dominant nature of Tyr165Ser was supported by co-transformation studies in yeast of plasmids carrying wild type and mutant genes. These results enable a model of the bisdioxopiperazine pharmacophore using the proposed asymmetric ATP hydrolysis of the enzyme
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Creation of the Person-Centered Wellness Home in Older Adults
Background and Objectives: Extending the Patient-Centered Medical Home (PCMH) model into the community may address the poor linkage between medical clinics and underserved communities. Our first of three objectives was to determine if peer leaders and wellness coaches can be the relationship center of wellness care. We evaluated the Self-management Resource Center Small Group Programs (SMRCSGP), plus wellness coaching, as a booster intervention in older adults with chronic diseases. Second, we evaluated the role of personal health records (PHR) prototype as the linkage between the clinic and community. Using input from these two objectives, we lay the groundwork for the Person-centered Wellness Home (PCWH).
Research Design and Methods: Participants enrolled from five South Bronx New York City Housing Authority communities. We conducted a pragmatic, randomized controlled trial using two arms (n = 121): (1) SMRCSGP and (2) SMRCSGP plus wellness coaching initiated as a booster after SMRCSGP completion. Adjusted individual growth models compared the slope differences for outcomes. We conducted a social networking analysis on the ties between wellness coaches and participants. PCMH-certified physicians completed in-depth interviews on the PHR prototype. An adaptation from the consensus-workshop model summarized the priority PCWH items.
Results: There was an improvement in self-reported physical functioning (2.0 T-score units higher, p = .03) by the wellness coaching group, but the groups did not differ on physical activity. From the social networking analysis, connections were stable over time with wellness-coaches and participants. The Consensus Conference identified eight major components of the PCWH.
Discussion and Implications: Wellness coaching post-SMRCSGP was a booster to physical function, an upstream outcome for physical activity. During the Consensus-Conference, community-based prevention marketing and personal navigators for connecting to a PCMH emerged as novel components. This supports future work in training community health workers as peer leaders to provide evidence-based programs and other PCWH components
Site-dependent nuclear dynamics in core-excited butadiene
Symmetry breaking and competition between electronic decay and nuclear dynamics are major factors determining whether the memory of the initial core-hole localisation in a molecule is retained long enough to affect fragmentation. We investigate the fate of core holes localised at different sites in the free 1,3 trans butadiene molecule by using synchrotron radiation to selectively excite core electrons from different C 1s sites to π* orbitals. Fragmentation involving bonds localised at the site of the core hole provides clear evidence for preferential bond breaking for a core hole located at the terminal carbon site, while the signature of localisation is weak for a vacancy on the central carbon site. The origin of this difference is attributed to out-of-plane vibrations, and statistical evaporation of protons for vacancies located at the central carbon sites
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Delta chirality ruthenium ‘light-switch’ complexes can bind in the minor groove of DNA with five different binding modes
[Ru(phen)2(dppz)]2+ has been studied since the 1990s due to its “light-switch” properties. It can be used as a luminescent DNA probe, with emission switched on through DNA binding. The luminescence observed is dependent on the solvent accessibility of the pyrazine nitrogen atoms, and therefore is sensitive to changes in both binding site of the cation and chromophore orientation. The compound is also chiral, and there are distinct differences between the enantiomers in terms of the emission behaviour when bound to a variety of DNA sequences. Whilst a number of binary DNA-complex X-ray crystal structures is available, most include the Λ enantiomer, and there is very little structural information about binding of the Δ enantiomer. Here we present the first X-ray crystal structure of a Δ enantiomer bound to well-matched DNA, in the absence of the other, Λ, enantiomer. We show how the binding site observed here can be related to a more general pattern of motifs in the crystallographic literature and propose that the Δ enantiomer can bind with five different binding modes, offering a new hypothesis for the interpretation of solution data
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