14,577 research outputs found
Radiolabeling human peripheral blood stem cells for positron emission tomography (PET) imaging in young rhesus monkeys.
These studies focused on a new radiolabeling technique with copper ((64)Cu) and zirconium ((89)Zr) for positron emission tomography (PET) imaging using a CD45 antibody. Synthesis of (64)Cu-CD45 and (89)Zr-CD45 immunoconjugates was performed and the evaluation of the potential toxicity of radiolabeling human peripheral blood stem cells (hPBSC) was assessed in vitro (viability, population doubling times, colony forming units). hPBSC viability was maintained as the dose of (64)Cu-TETA-CD45 increased from 0 (92%) to 160 µCi/mL (76%, p>0.05). Radiolabeling efficiency was not significantly increased with concentrations of (64)Cu-TETA-CD45 >20 µCi/mL (p>0.50). Toxicity affecting both growth and colony formation was observed with hPBSC radiolabeled with ≥40 µCi/mL (p<0.05). For (89)Zr, there were no significant differences in viability (p>0.05), and a trend towards increased radiolabeling efficiency was noted as the dose of (89)Zr-Df-CD45 increased, with a greater level of radiolabeling with 160 µCi/mL compared to 0-40 µCi/mL (p<0.05). A greater than 2,000 fold-increase in the level of (89)Zr-Df-CD45 labeling efficiency was observed when compared to (64)Cu-TETA-CD45. Similar to (64)Cu-TETA-CD45, toxicity was noted when hPBSC were radiolabeled with ≥40 µCi/mL (p<0.05) (growth, colony formation). Taken together, 20 µCi/mL resulted in the highest level of radiolabeling efficiency without altering cell function. Young rhesus monkeys that had been transplanted prenatally with 25×10(6) hPBSC expressing firefly luciferase were assessed with bioluminescence imaging (BLI), then 0.3 mCi of (89)Zr-Df-CD45, which showed the best radiolabeling efficiency, was injected intravenously for PET imaging. Results suggest that (89)Zr-Df-CD45 was able to identify engrafted hPBSC in the same locations identified by BLI, although the background was high
Longitudinal Spin Asymmetry and Cross Section of Inclusive pi0 Production in Polarized p+p Collisions at RHIC
We present the first measurement of the cross section and the double
longitudinal spin asymmetry of inclusive pi0 production in polarized p+p
collisions at Sqrt(s) = 200 GeV at mid-rapidity with the STAR detector, using
the barrel electromagnetic calorimeter. The measured cross section is compared
to NLO pQCD calculations and can provide constraints on the pion fragmentation
functions. Fragmentation is studied directly by measuring the momentum fraction
of pi0 in jets, a quantity that is affected by the fragmentation process and
jet reconstruction effects. The double longitudinal spin asymmetry is compared
to NLO pQCD calculations based on different assumptions for the gluon
polarization in the nucleon to provide constraints on delta g/g. At the present
level of statistics the measured asymmetry disfavors a large positive gluon
polarization, but can not yet distinguish between other scenarios.Comment: 4 pages, 2 figures, submitted to the proceedings of the 17th
International Spin Physics Symposium (SPIN2006), Kyoto, Japan, October 2 to
7, 200
An Integrated Tracker for STAR
The STAR experiment at the Relativistic Heavy Ion Collider RHIC studies the
new state of matter produced in relativistic heavy ion collisions and the spin
structure of the nucleon in collisions of polarized protons. In order to
improve the capabilities for heavy flavor measurements and the reconstruction
of charged vector bosons an upgrade of the tracking system both in the central
and the forward region is pursued. The integrated system providing high
resolution tracking and secondary vertex reconstruction capabilities will use
silicon pixel, strip and GEM technology.Comment: 4 pages, 2 figures, to be published in the Proceedings of the 9th
Conference on the Intersections of Particle and Nuclear Physics (CIPANP
2006), Rio Grande, Puerto Rico, May 30 - June 3, 200
Inclusive Hadron Production in p+p Collisions at STAR
The STAR experiment at RHIC has measured a variety of inclusive hadron cross
sections in collisions at Sqrt(s) = 200 GeV. Measurements of the
differential cross section for inclusive charged pion production at mid
rapidity and for inclusive neutral pion production at forward rapidity (3.0 <
eta < 4.2) as well as the first preliminary result from STAR for the
differential cross section for inclusive neutral pion production near mid
rapidity are presented. These cross sections are compared to next-to-leading
order perturbative QCD calculations and can provide constraints on the pion
fragmentation functions. Good agreement between data and pQCD has been found
for all three cross sections.Comment: 4 pages, 1 figure, to be published in the Proceedings of the 9th
Conference on the Intersections of Particle and Nuclear Physics (CIPANP
2006), Rio Grande, Puerto Rico, May 30 - June 3, 2006, v2 with updated
reference
Nuclear spin ferromagnetic phase transition in an interacting 2D electron gas
Electrons in a two-dimensional semiconducting heterostructure interact with
nuclear spins via the hyperfine interaction. Using a a Kondo lattice
formulation of the electron-nuclear spin interaction, we show that the nuclear
spin system within an interacting two-dimensional electron gas undergoes a
ferromagnetic phase transition at finite temperatures. We find that
electron-electron interactions and non-Fermi liquid behavior substantially
enhance the nuclear spin Curie temperature into the range with decreasing
electron density.Comment: 4.1 page
Universality properties of the stationary states in the one-dimensional coagulation-diffusion model with external particle input
We investigate with the help of analytical and numerical methods the reaction
A+A->A on a one-dimensional lattice opened at one end and with an input of
particles at the other end. We show that if the diffusion rates to the left and
to the right are equal, for large x, the particle concentration c(x) behaves
like As/x (x measures the distance to the input end). If the diffusion rate in
the direction pointing away from the source is larger than the one
corresponding to the opposite direction the particle concentration behaves like
Aa/sqrt(x). The constants As and Aa are independent of the input and the two
coagulation rates. The universality of Aa comes as a surprise since in the
asymmetric case the system has a massive spectrum.Comment: 27 pages, LaTeX, including three postscript figures, to appear in J.
Stat. Phy
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