79 research outputs found
Daily variation of particulate air pollution and poor cardiac autonomic control in the elderly
Particulate matter air pollution (PM) has been related to cardiovascular disease mortality in a number of recent studies. lThe pathophysiologic mechanisms for this association are under study. Low heart rate variability, a marker of poor cardiac autonomic control, is associated with higher risk of myocardial infarction and sudden cardiac death. To address the possible mechanisms for
PM-cardiovascular disease mortality, we examined the cardiac autonomic response to daily variations
in PM in 26 elderly (mean age 81) individuals for 3 consecutive weeks. Several standardized
methods were used to measure 24-hr average PM concentrations prior to the clinical test
inside (indoor PM2.5) and immediately outside (outdoor PM2.5 and PM2.5-10) of participants'
residences. Resting, supine, 6-min R wave to R wave (R-R) interval data were collected to estimate
high frequency (0.15-0.40 Hz) and low frequency (0.04-0.15 Hz) powers and standard
deviation of normal R-R intervals (SDNN) as cardiac autonomic control indices. Participant-specific
lower heart rate variability days were defined as days for which the high-frequency
indices fell below the first tertile of the individual's high-frequency distribution over the study
period. Indoor PM 25 > 15 μg/m3 was used to define high pollution days. Results show that the
odds ratio (95% confidence interval) of low heart rate variability high frequency for high (vs. not
high) pollution days was 3.08 (1.43, 6.59). The β-coefficients (standard error) from mixed models
to assess the quantitative relationship between variations in indoor PM25 and the log-transformed
high frequency, low frequency, and SDNN were: -0.029 (0.010), -0.027 (0.009), and
-0.004 (0.003), respectively. This first study of cardiac autonomic control response to daily variations
of PM2.5 indicates that increased levels of PM2.5 are associated with lower cardiac autonomic
control, suggesting a possible mechanistic link between PM and cardiovascular disease
mortality
Dipole Strength Distributions from HIGS Experiments
A series of photon scattering experiments has been performed on the double-beta decay partners 76Ge and 76Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesi
Energy separation of the 1⁺/1⁻ parity doublet in ²⁰Ne
The parity doublet of 1⁺/1⁻ states of Ne⁻²⁰ at 11.26 MeV excitation energy is one of the best known test cases to study the weak part of the nuclear Hamiltonian. The feasibility of parity violation experiments depend on the effective nuclear enhancement factor (RN/|E(1⁺) − E(l⁻)|) which amplifies the impact of the matrix element of the weak interaction on observables indicating parity mixing. An extreme large value of Rn/|E(1⁺) − E(l⁻)| = (670 ± 7000) MeV⁻¹ was reported for the doublet in ²⁰Ne. The large uncertainty depends amongst others on the large uncertainty of |E(1⁺) − E(l⁻)| = 7.7±5.5 keV of the parity doublet. Nuclear resonance fluorescence (NRF) experiments with linearly and circularly polarized photon beams were performed at the High Intensity Gamma-Ray Source at Duke University, Durham, NC, USA, to determine the energy difference of the parity doublet with higher precision. The different angular distributions for 0⁺ → 1⁻ → 0⁺ and 0⁺ → 1⁺ → 0⁺ NRF cascades in polarized γ-ray beams were used to determine the energy difference of the parity doublet to 2.9(13) keV
Structure of high-lying levels populated in the Y-96 -> Zr-96 beta decay
The nature of levels of Zr below the -decay value of Y has been investigated in high-resolution -ray spectroscopy following the decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from decay allow the absolute excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of levels below the value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the Y decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum
Preliminary investigations into tris(2,2\u27-bipyridyl) ruthenium (III) as a chemiluminescent reagent for the detection of 3,6-diacetylmorphine (heroin) on surfaces
The use of tris(2,2\u27-bipyridyl) ruthenium (III) as a chemiluminescent spray reagent spot-test for heroin is discussed. Two forms of the reagent are investigated an aqueous and an anhydrous where both were found to give vastly different results. The aqueous reagent giving slow, low intensity chemiluminescence whilst the anhydrous reagent gave a fast, bright response in the presence of 3,6-diacetylmorphine. The anhydrous reagent is less sensitive the slow, intensity response is characteristic of only two opiates tested 3,6-diacetylmorphine and 3-monoacetylmorphine.<br /
Structure of high-lying levels populated in the 96Y →96Zr β decay
WOS:000713124400027The nature of the high-lying final levels of the 96Ygs β decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum, has been investigated in high-resolution γ-ray spectroscopy following the β decay as well as in a campaign of inelastic photon scattering experiments. The comprehensive approach establishes 1− levels associated with the Pygmy Dipole Resonance as high-lying final levels in the β decay. Branching ratios extracted from β decay complement photon scattering and allow the absolute E1 excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of the 1− levels below the Qβ value, which are investigated in the Quasiparticle Phonon Model. The calculations reveal that the components populated in β decay contribute only with small amplitudes to the complex wavefunction of these 1− levels. A comparison of the β decay results to data from total absorption γ-ray spectroscopy demonstrates a good agreement between both measurements
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