614 research outputs found
Investigating the chromatic contribution to recognition of facial expression
A pedestrian may judge the intentions of another person by their facial expression amongst other cues and aiding such evaluation after dark is one aim of road lighting. Previous studies give mixed conclusions as to whether lamp spectrum affects the ability to make such judgements. An experiment was carried out using conditions better resembling those of pedestrian behaviour, using as targets photographs of actors portraying facial expressions corresponding to the six universally recognised emotions. Responses were sought using a forced-choice procedure, under two types of lamp and with colour and grey scale photographs. Neither lamp type nor image colour was suggested to have a significant effect on the frequency with which the emotion conveyed by facial expression was correctly identified
Laser Spectroscopy of Niobium Fission Fragments: First Use of Optical Pumping in an Ion Beam Cooler Buncher
A new method of optical pumping in an ion beam cooler buncher has been developed to selectively enhance ionic metastable state populations. The technique permits the study of elements previously inaccessible to laser spectroscopy and has been applied here to the study of Nb. Model independent mean-square charge radii and nuclear moments have been studied for Nb to cover the region of the N=50 shell closure and N≈60 sudden onset of deformation. The increase in mean-square charge radius is observed to be less than that for Y, with a substantial degree of β softness observed before and after N=60
Nuclear spins, magnetic moments and quadrupole moments of Cu isotopes from N = 28 to N = 46: probes for core polarization effects
Measurements of the ground-state nuclear spins, magnetic and quadrupole
moments of the copper isotopes from 61Cu up to 75Cu are reported. The
experiments were performed at the ISOLDE facility, using the technique of
collinear laser spectroscopy. The trend in the magnetic moments between the
N=28 and N=50 shell closures is reasonably reproduced by large-scale
shell-model calculations starting from a 56Ni core. The quadrupole moments
reveal a strong polarization of the underlying Ni core when the neutron shell
is opened, which is however strongly reduced at N=40 due to the parity change
between the and orbits. No enhanced core polarization is seen beyond
N=40. Deviations between measured and calculated moments are attributed to the
softness of the 56Ni core and weakening of the Z=28 and N=28 shell gaps.Comment: 13 pagers, 19 figures, accepted by Physical Review
Isomer shift and magnetic moment of the long-lived 1/2 isomer in Zn: signature of shape coexistence near Ni
Collinear laser spectroscopy has been performed on the Zn
isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred
milliseconds half-life was confirmed, and the nuclear spins and moments of the
ground and isomeric states in Zn as well as the isomer shift were
measured. From the observed hyperfine structures, spins and
are firmly assigned to the ground and isomeric states. The magnetic moment
(Zn) = 1.1866(10) , confirms the spin-parity
with a shell-model configuration, in excellent
agreement with the prediction from large scale shell-model theories. The
magnetic moment (Zn) = 1.0180(12) supports a
positive parity for the isomer, with a wave function dominated by a 2h-1p
neutron excitation across the shell gap. The large isomer shift
reveals an increase of the intruder isomer mean square charge radius with
respect to that of the ground state:
= +0.204(6) fm, providing first evidence of shape coexistence.Comment: 5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016
Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity 86Y- or 177Lu-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates
Purpose: GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pretargeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn–(radiolanthanide metal) complex.
Methods: PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent, and the C825 haptens [superscript 177]Lu-or [superscript 86]Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.c.) CRC xenograft model.
Results: Using optimized PRIT, therapeutic indices (TIs) for tumor radiation-absorbed dose of 73 (tumor/blood) and 12 (tumor/kidney) were achieved. Estimated absorbed doses (cGy/MBq) to tumor, blood, liver, spleen, and kidney for single-cycle PRIT were 65.8, 0.9 (TI 73), 6.3 (TI 10), 6.6
(TI 10), and 5.3 (TI 12), respectively. Two cycles of PRIT (66.6 or 111 MBq [superscript 177]Lu-DOTA-Bn) were safe and effective, with a complete response of established s.c. tumors (100 – 700 mm³) in nine of nine mice, with two mice alive without recurrence at >140 days. Tumor log kill in this model was estimated to be 2.1 – 3.0 based on time to 500-mm³ tumor recurrence. In addition, PRIT dosimetry/diagnosis was performed by PET imaging of the positron-emitting DOTA hapten [superscript 86]Y-DOTA-Bn.
Conclusion: We have developed anti-GPA33 PRIT as a triplestep theranostic strategy for preclinical detection, dosimetry, and safe targeted radiotherapy of established human colorectal mouse xenografts.National Institute of Mental Health (U.S.) (Grant R01-CA-101830
Halos and related structures
The halo structure originated in nuclear physics but is now encountered more
widely. It appears in loosely bound, clustered systems where the spatial
extension of the system is significantly larger than that of the binding
potentials. A review is given on our current understanding of these structures,
with an emphasis on how the structures evolve as more cluster components are
added, and on the experimental situation concerning halo states in light
nuclei.Comment: 27 pages, 3 figures, Contribution to Nobel Symposium 152 "Physics
With Radioactive Beams
Targeting of radiolabeled J591 antibody to PSMA-expressing tumors: optimization of imaging and therapy based on non-linear compartmental modeling
BACKGROUND: We applied a non-linear immunokinetic model to quantitatively compare absolute antibody uptake and turnover in subcutaneous LNCaP human prostate cancer (PCa) xenografts of two radiolabeled forms of the humanized anti-prostate-specific membrane antigen (PSMA) monoclonal antibody J591 ((124)I-J591 and (89)Zr-J591). Using the model, we examined the impact of dose on the tumor and plasma positron emission tomography (PET)-derived time-activity curves. We also sought to predict the optimal targeting index (ratio of integrated-tumor-to-integrated-plasma activity concentrations) for radioimmunotherapy. METHODS: The equilibrium rates of antibody internalization and turnover in the tumors were derived from PET images up to 96 h post-injection using compartmental modeling with a non-linear transfer rate. In addition, we serially imaged groups of LNCaP tumor-bearing mice injected with (89)Zr-J591 antibody doses ranging from antigen subsaturating to saturating to examine the suitability of using a non-linear approach and derived the time-integrated concentration (in μM∙hours) of administered tracer in tumor as a function of the administered dose of antibody. RESULTS: The comparison of (124)I-J591 and (89)Zr-J591 yielded similar model-derived values of the total antigen concentration and internalization rate. The association equilibrium constant (k(a)) was twofold higher for (124)I, but there was a ~tenfold greater tumoral efflux rate of (124)I from tumor compared to that of (89)Zr. Plots of surface-bound and internalized radiotracers indicate similar behavior up to 24 h p.i. for both (124)I-J591 and (89)Zr-J591, with the effect of differential clearance rates becoming apparent after about 35 h p.i. Estimates of J591/PSMA complex turnover were 3.9–90.5 × 10(12) (for doses from 60 to 240 μg) molecules per hour per gram of tumor (20 % of receptors internalized per hour). CONCLUSIONS: Using quantitative compartmental model methods, surface binding and internalization rates were shown to be similar for both (124)I-J591 and (89)Zr-J591 forms, as expected. The large difference in clearance rates of the radioactivity from the tumor is likely due to differential trapping of residualizing zirconium versus non-residualizing iodine. Our non-linear model was found to be superior to a conventional linear model. This finding and the calculated activity persistence time in tumor have important implications for radioimmunotherapy and other antibody-based therapies in patients
Developments for resonance ionization laser spectroscopy of the heaviest elements at SHIP
The experimental determination of atomic levels and the first ionization potential of the heaviest elements (Z >= 100) is key to challenge theoretical predictions and to reveal changes in the atomic shell structure. These elements are only artificially produced in complete-fusion evaporation reactions at on-line facilities such as the GSI in Darmstadt at a rate of, at most, a few atoms per second. Hence, highly sensitive spectroscopic methods are required. Laser spectroscopy is one of the most powerful and valuable tools to investigate atomic properties. In combination with a buffer-gas filled stopping cell, the Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique provides the highest sensitivity for laser spectroscopy on the heaviest elements. The RADRIS setup, as well as the measurement procedure, have been optimized and characterized using the a-emitter 155Yb in on-line conditions, resulting
in an overall efficiency well above 1%. This paves the way for a successful search of excited atomic levels in nobelium and heavier elements.publisher: Elsevier
articletitle: Developments for resonance ionization laser spectroscopy of the heaviest elements at SHIP
journaltitle: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
articlelink: http://dx.doi.org/10.1016/j.nimb.2016.06.001
content_type: article
copyright: © 2016 Elsevier B.V. All rights reserved.status: publishe
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