719 research outputs found
Molecular double core-hole electron spectroscopy for chemical analysis
We explore the potential of double core hole electron spectroscopy for
chemical analysis in terms of x-ray two-photon photoelectron spectroscopy
(XTPPS). The creation of deep single and double core vacancies induces
significant reorganization of valence electrons. The corresponding relaxation
energies and the interatomic relaxation energies are evaluated by CASSCF
calculations. We propose a method how to experimentally extract these
quantities by the measurement of single and double core-hole ionization
potentials (IPs and DIPs). The influence of the chemical environment on these
DIPs is also discussed for states with two holes at the same atomic site and
states with two holes at two different atomic sites. Electron density
difference between the ground and double core-hole states clearly shows the
relaxations accompanying the double core-hole ionization. The effect is also
compared with the sensitivity of single core hole ionization potentials (IPs)
arising in single core hole electron spectroscopy. We have demonstrated the
method for a representative set of small molecules LiF, BeO, BF, CO, N2, C2H2,
C2H4, C2H6, CO2 and N2O. The scalar relativistic effect on IPs and on DIPs are
briefly addressed.Comment: 35 pages, 6 figures. To appear in J. Chem. Phys
Enabling energy system transition toward decarbonization in Japan through energy service demand reduction
Japan's mid-century strategy for reducing greenhouse gas emissions by 80% in 2050 would require large-scale energy system transformation and associated increases in mitigation costs. Nevertheless, the role of energy demand reduction, especially reductions related to energy services such as behavioral changes and material use efficiency improvements, have not been sufficiently evaluated. This study aims to identify key challenges and opportunities of the decarbonization goal when considering the role of energy service demand reduction. To this end, we used a detailed bottom-up energy system model in conjunction with an energy service demand model to explore energy system changes and their cost implications. The results indicate that final energy demand in 2050 can be cut by 37% relative to the no-policy case through energy service demand reduction measures. Although the lack of carbon capture and storage would cause mitigation costs to double or more, these economic impacts can be offset by energy service demand reduction. Among energy demand sectors, the impact of industrial service demand reduction is largest, as it contributes to reducing residual emissions from the industry sector. These findings highlight the importance of energy service demand reduction measures for meeting national climate goals in addition to technological options
Association between exposure to environmental tobacco smoke and biomarkers of oxidative stress among patients hospitalised with acute myocardial infarction
Objective
To determine whether exposure to environmental tobacco smoke was associated with oxidative stress among patients hospitalised for acute myocardial infarction.<p></p>
Design
An existing cohort study of 1,261 patients hospitalised for acute myocardial infarction.<p></p>
Setting
Nine acute hospitals in Scotland.<p></p>
Participants
Sixty never smokers who had been exposed to environmental tobacco smoke (admission serum cotinine ≥3.0 ng/mL) were compared with 60 never smokers who had not (admission serum cotinine ≤0.1 ng/mL).<p></p>
Intervention
None.<p></p>
Main outcome measures
Three biomarkers of oxidative stress (protein carbonyl, malondialdehyde (MDA) and oxidised low-density lipoprotein (ox-LDL)) were measured on admission blood samples and adjusted for potential confounders.<p></p>
Results
After adjusting for baseline differences in age, sex and socioeconomic status, exposure to environmental tobacco smoke was associated with serum concentrations of both protein carbonyl (beta coefficient 7.96, 95% CI 0.76, 15.17, p = 0.031) and MDA (beta coefficient 10.57, 95% CI 4.32, 16.81, p = 0.001) but not ox-LDL (beta coefficient 2.14, 95% CI −8.94, 13.21, p = 0.703).<p></p>
Conclusions
Exposure to environmental tobacco smoke was associated with increased oxidative stress. Further studies are requires to explore the role of oxidative stress in the association between environmental tobacco smoke and myocardial infarction.<p></p>
Fractionation and characterization of oil palm (Elaeis guineensis) as treated by supercritical water
The Mechanisms of Codon Reassignments in Mitochondrial Genetic Codes
Many cases of non-standard genetic codes are known in mitochondrial genomes.
We carry out analysis of phylogeny and codon usage of organisms for which the
complete mitochondrial genome is available, and we determine the most likely
mechanism for codon reassignment in each case. Reassignment events can be
classified according to the gain-loss framework. The gain represents the
appearance of a new tRNA for the reassigned codon or the change of an existing
tRNA such that it gains the ability to pair with the codon. The loss represents
the deletion of a tRNA or the change in a tRNA so that it no longer translates
the codon. One possible mechanism is Codon Disappearance, where the codon
disappears from the genome prior to the gain and loss events. In the
alternative mechanisms the codon does not disappear. In the Unassigned Codon
mechanism, the loss occurs first, whereas in the Ambiguous Intermediate
mechanism, the gain occurs first. Codon usage analysis gives clear evidence of
cases where the codon disappeared at the point of the reassignment and also
cases where it did not disappear. Codon disappearance is the probable
explanation for stop to sense reassignments and a small number of reassignments
of sense codons. However, the majority of sense to sense reassignments cannot
be explained by codon disappearance. In the latter cases, by analysis of the
presence or absence of tRNAs in the genome and of the changes in tRNA
sequences, it is sometimes possible to distinguish between the Unassigned Codon
and Ambiguous Intermediate mechanisms. We emphasize that not all reassignments
follow the same scenario and that it is necessary to consider the details of
each case carefully.Comment: 53 pages (45 pages, including 4 figures + 8 pages of supplementary
information). To appear in J.Mol.Evo
Right coronary wall cmr in the older asymptomatic advance cohort: positive remodeling and associations with type 2 diabetes and coronary calcium
<p>Abstract</p> <p>Background</p> <p>Coronary wall cardiovascular magnetic resonance (CMR) is a promising noninvasive approach to assess subclinical atherosclerosis, but data are limited in subjects over 60 years old, who are at increased risk. The purpose of the study was to evaluate coronary wall CMR in an asymptomatic older cohort.</p> <p>Results</p> <p>Cross-sectional images of the proximal right coronary artery (RCA) were acquired using spiral black-blood coronary CMR (0.7 mm resolution) in 223 older, community-based patients without a history of cardiovascular disease (age 60-72 years old, 38% female). Coronary measurements (total vessel area, lumen area, wall area, and wall thickness) had small intra- and inter-observer variabilities (r = 0.93~0.99, all p < 0.0001), though one-third of these older subjects had suboptimal image quality. Increased coronary wall thickness correlated with increased coronary vessel area (p < 0.0001), consistent with positive remodeling. On multivariate analysis, type 2 diabetes was the only risk factor associated with increased coronary wall area and thickness (p = 0.03 and p = 0.007, respectively). Coronary wall CMR measures were also associated with coronary calcification (p = 0.01-0.03).</p> <p>Conclusions</p> <p>Right coronary wall CMR in asymptomatic older subjects showed increased coronary atherosclerosis in subjects with type 2 diabetes as well as coronary calcification. Coronary wall CMR may contribute to the noninvasive assessment of subclinical coronary atherosclerosis in older, at-risk patient groups.</p
Frequentist Coverage Properties of Uncertainty Intervals for Weak Poisson Signals in the Presence of Background
We construct uncertainty intervals for weak Poisson signals in the presence
of background. We consider the case where a primary experiment yields a
realization of the signal plus background, and a second experiment yields a
realization of the background. The data acquisitions times for the
background-only experiment,T_bg, and the primary experiment,T, are selected so
that their ratio varies from 1 to 25. The expected number of background counts
in the primary experiment varies from 0.2 to 2. We construct 90 and 95 percent
confidence intervals based on a propagation-of-errors method as well as two
implementations of a Neyman procedure where acceptance regions are constructed
based on a likelihood-ratio criterion that automatically determines whether the
resulting confidence interval is one-sided or two-sided. The first Neyman
procedure (due to Feldman and Cousins) neglects uncertainty in the background.
In the other Neyman procedure, we account for uncertainty in the background
with a parametric bootstrap method. We also construct minimum length Bayesian
credibility intervals. For each method, we test for the presence of a signal
based on the value of the lower endpoint of the uncertainty interval. When
T_bg/T is 5 or more and the expected background is 2 or less, the Feldman
Cousins method outperforms the other methods considered.Comment: 12 pages,12 tables, 10 figures. This is the final version of a
manuscript that has been accepted for publication by Measurement Science and
Technolog
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