1,012 research outputs found
High-j single-particle neutron states outside the N=82 core
The behaviour of the i13/2 and h9/2 single-neutron strength was studied with
the (4He,3He) reaction on 138Ba, 140Ce, 142Nd and 144Sm targets at a beam
energy of 51 MeV. The separation between the single-neutron states i13/2 and
h9/2 was measured in N =83 nuclei with changing proton number. To this end
spectroscopic factors for states populated in high-l transfer were extracted
from the data. Some mixing of l=5 and 6 strength was observed with states that
are formed by coupling the f7/2 state to the 2+ and 3- vibrational states and
the mixing matrix elements were found to be remarkably constant. The centroids
of the strength indicate a systematic change in the energies of the i13/2 and
h9/2 single-neutron states with increasing proton number that is in
quantitative agreement with the effects expected from the tensor interaction.Comment: 12 pages of text, 3 diagram
Reducing False Alarms of Intensive Care Online-Monitoring Systems: An Evaluation of Two Signal Extraction Algorithms
Online-monitoring systems in intensive care are affected by a high rate of false threshold alarms. These are caused by irrelevant noise and outliers in the measured time series data. The high false alarm rates can be lowered by separating relevant signals from noise and outliers online, in such a way that signal estimations, instead of raw measurements, are compared to the alarm
limits. This paper presents a clinical validation study for two recently developed online signal filters. The filters are based on robust repeated median regression in moving windows of varying width. Validation is done offline using a large annotated reference database. The performance criteria are sensitivity and the proportion of false alarms suppressed by the signal filters
Experimental evidence of a natural parity state in Mg and its impact to the production of neutrons for the s process
We have studied natural parity states in Mg via the
Ne(Li,d)Mg reaction. Our method significantly improves the
energy resolution of previous experiments and, as a result, we report the
observation of a natural parity state in Mg. Possible spin-parity
assignments are suggested on the basis of published -ray decay
experiments. The stellar rate of the Ne(,)Mg
reaction is reduced and may give rise to an increase in the production of
s-process neutrons via the Ne(,n)Mg reaction.Comment: Published in PR
Absolute Determination of the 22Na(p,g) Reaction Rate in Novae
Gamma-ray telescopes in orbit around the Earth are searching for evidence of
the elusive radionuclide 22Na produced in novae. Previously published
uncertainties in the dominant destructive reaction, 22Na(p,g)23Mg, indicated
new measurements in the proton energy range of 150 to 300 keV were needed to
constrain predictions. We have measured the resonance strengths, energies, and
branches directly and absolutely by using protons from the University of
Washington accelerator with a specially designed beamline, which included beam
rastering and cold vacuum protection of the 22Na implanted targets. The
targets, fabricated at TRIUMF-ISAC, displayed minimal degradation over a ~ 20 C
bombardment as a result of protective layers. We avoided the need to know the
stopping power, and hence the target composition, by extracting resonance
strengths from excitation functions integrated over proton energy. Our
measurements revealed that resonance strengths for E_p = 213, 288, 454, and 610
keV are stronger by factors of 2.4 to 3.2 than previously reported. Upper
limits have been placed on proposed resonances at 198-, 209-, and 232-keV. We
have re-evaluated the 22Na(p,g) reaction rate, and our measurements indicate
the resonance at 213 keV makes the most significant contribution to 22Na
destruction in novae. Hydrodynamic simulations including our rate indicate that
the expected abundance of 22Na ejecta from a classical nova is reduced by
factors between 1.5 and 2, depending on the mass of the white-dwarf star
hosting the nova explosion.Comment: 20 pages, 18 figures; shortened paper, accepted in Phys. Rev.
Interrelation of inflammation and APP in sIBM: IL-1 beta induces accumulation of beta-amyloid in skeletal muscle.
Distinct interrelationships between inflammation and beta-amyloid-associated degeneration, the two major hallmarks of the skeletal muscle pathology in sporadic inclusion body myositis (sIBM), have remained elusive. Expression of markers relevant for these pathomechanisms were analysed in biopsies of sIBM, polymyositis (PM), dermatomyositis (DM), dystrophic and non-myopathic muscle as controls, and cultured human myotubes. By quantitative PCR, a higher upregulation was noted for the mRNA-expression of CXCL-9, CCL-3, CCL-4, IFN-gamma, TNF-alpha and IL-1 beta in sIBM muscle compared to PM, DM and controls. All inflammatory myopathies displayed overexpression of degeneration-associated markers, yet only in sIBM, expression of the mRNA of amyloid precursor protein (APP) significantly and consistently correlated with inflammation in the muscle and mRNA-levels of chemokines and IFN-gamma. Only in sIBM, immunohistochemical analysis revealed that inflammatory mediators including IL-1 beta co-localized to beta-amyloid depositions within myofibres. In human myotubes, exposure to IL-1 beta caused upregulation of APP with subsequent intracellular aggregation of beta-amyloid. Our data suggest that, in sIBM muscle, production of high amounts of pro-inflammatory mediators specifically induces beta-amyloid-associated degeneration. The observations may help to design targeted treatment strategies for chronic inflammatory disorders of the skeletal muscle
Pair correlations in nuclei involved in neutrinoless double beta decay: 76Ge and 76Se
Precision measurements were carried out to test the similarities between the
ground states of 76Ge and 76Se. The extent to which these two nuclei can be
characterized as consisting of correlated pairs of neutrons in a BCS-like
ground state was studied. The pair removal (p,t) reaction was measured at the
far forward angle of 3 degrees. The relative cross sections are consistent (at
the 5% level) with the description of these nuclei in terms of a correlated
pairing state outside the N=28 closed shells with no pairing vibrations. Data
were also obtained for 74Ge and 78Se
Production of 26Al in stellar hydrogen-burning environments: spectroscopic properties of states in 27Si
Model predictions of the amount of the radioisotope 26Al produced in
hydrogen-burning environments require reliable estimates of the thermonuclear
rates for the 26gAl(p,{\gamma})27Si and 26mAl(p,{\gamma})27Si reactions. These
rates depend upon the spectroscopic properties of states in 27Si within about 1
MeV of the 26gAl+p threshold (Sp = 7463 keV). We have studied the
28Si(3He,{\alpha})27Si reaction at 25 MeV using a high-resolution
quadrupole-dipole-dipole-dipole magnetic spectrograph. For the first time with
a transfer reaction, we have constrained J{\pi} values for states in 27Si over
Ex = 7.0 - 8.1 MeV through angular distribution measurements. Aside from a few
important cases, we generally confirm the energies and spin-parity assignments
reported in a recent {\gamma}-ray spectroscopy study. The magnitudes of neutron
spectroscopic factors determined from shell-model calculations are in
reasonable agreement with our experimental values extracted using this
reaction.Comment: accepted for publication in Phys. Rev.
First application of Markov chain Monte Carlo-based Bayesian data analysis to the Doppler-shift attenuation method
Motivated primarily by the large uncertainties in the thermonuclear rate of the 30P(p,Îł)31S reaction that limit our understanding of classical novae, we carried out lifetime measurements of 31S excited states using the Doppler Shift Lifetimes (DSL2) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility. The 31S excited states were populated by the 3He(32S,α)31S reaction. The deexcitation Îł rays were detected by a clover-type high-purity germanium detector in coincidence with the α particles detected by a silicon detector telescope. We have applied modern Markov chain Monte Carlo-based Bayesian statistical techniques to perform lineshape analyses of Doppler-shift attenuation method Îł-ray data for the first time. We have determined the lifetimes of the two lowest-lying 31S excited states. First experimental upper limits on the lifetimes of four higher-lying states have been obtained. The experimental results were compared to shell-model calculations using five universal sd-shell Hamiltonians. Evidence for Îł rays originating from the astrophysically important JÏ=3/2+, 260-keV 30P(p,Îł)31S resonance with an excitation energy of Ex=6390.2(7) keV in 31S has also been observed, although strong constraints on the lifetime will require better statistics
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