684 research outputs found
Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and Southeast Asia during 2009-2013
Short-lived organic brominated compounds make up a significant part of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five very short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLB-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr and CHBr2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ∼100 ppb O3 corresponding to the extra-tropical tropopause layer
Dynamic Changes in High-Sensitivity Cardiac Troponin I in Response to Anthracycline-Based Chemotherapy
Aims:
Treatment advances have improved cancer-related outcomes and shifted interest towards minimising long-term iatrogenic complications, particularly chemotherapy-related cardiotoxicity. High-sensitivity cardiac troponin I (hs-cTnI) assays accurately quantify very low concentrations of plasma troponin and enable early detection of cardiomyocyte injury prior to the development of myocardial dysfunction. The profile of hs-cTnI in response to anthracycline-based treatment has not previously been described.
Materials and methods:
This was a multicentre prospective observational cohort study. Female patients with newly diagnosed invasive breast cancer scheduled to receive anthracycline-based (epirubicin) chemotherapy were recruited. Blood sampling was carried out before and 24 h after each cycle. Hs-cTnI concentrations were measured using the Abbott ARCHITECTSTAT assay.
Results:
We recruited 78 women with a median (interquartile range) age of 52 (49–61) years. The median baseline troponin concentration was 1 (1–4) ng/l and the median cumulative epirubicin dose was 394 (300–405) mg/m2. Following an initial 33% fall 24 h after anthracycline dosing (P < 0.001), hs-cTnI concentrations increased by a median of 50% (P < 0.001) with each successive treatment cycle. In total, 45 patients had troponin measured immediately before the sixth treatment cycle, 21 (46.6%) of whom had hs-cTnI concentrations ≥16 ng/l, indicating myocardial injury. Plasma hs-cTnI concentrations before the second treatment cycle were a strong predictor of subsequent myocardial injury.
Conclusions:
Cardiotoxicity arising from anthracycline therapy is detectable in the earliest stages of breast cancer treatment and is cumulative with each treatment cycle. This injury is most reliably determined from blood sampling carried out before rather than after each treatment cycle
Coupled-mode equations and gap solitons in a two-dimensional nonlinear elliptic problem with a separable periodic potential
We address a two-dimensional nonlinear elliptic problem with a
finite-amplitude periodic potential. For a class of separable symmetric
potentials, we study the bifurcation of the first band gap in the spectrum of
the linear Schr\"{o}dinger operator and the relevant coupled-mode equations to
describe this bifurcation. The coupled-mode equations are derived by the
rigorous analysis based on the Fourier--Bloch decomposition and the Implicit
Function Theorem in the space of bounded continuous functions vanishing at
infinity. Persistence of reversible localized solutions, called gap solitons,
beyond the coupled-mode equations is proved under a non-degeneracy assumption
on the kernel of the linearization operator. Various branches of reversible
localized solutions are classified numerically in the framework of the
coupled-mode equations and convergence of the approximation error is verified.
Error estimates on the time-dependent solutions of the Gross--Pitaevskii
equation and the coupled-mode equations are obtained for a finite-time
interval.Comment: 32 pages, 16 figure
Statistical Analysis of Different Muon-antineutrino->Electron-antineutrino Searches
A combined statistical analysis of the experimental results of the LSND and
KARMEN \numubnueb oscillation search is presented. LSND has evidence for
neutrino oscillations that is not confirmed by the KARMEN experiment. This
joint analysis is based on the final likelihood results for both data sets. A
frequentist approach is applied to deduce confidence regions. At a combined
confidence level of 36%, there is no area of oscillation parameters compatible
with both experiments. For the complementary confidence of 1-0.36=64%, there
are two well defined regions of oscillation parameters (sin^2(2th),Dm^2)
compatible with both experiments.Comment: 25 pages, including 10 figures, submitted to Phys. Rev.
Tests of CPT Invariance at Neutrino Factories
We investigate possible tests of CPT invariance on the level of event rates
at neutrino factories. We do not assume any specific model but phenomenological
differences in the neutrino-antineutrino masses and mixing angles in a Lorentz
invariance preserving context, such as it could be induced by physics beyond
the Standard Model. We especially focus on the muon neutrino and antineutrino
disappearance channels in order to obtain constraints on the
neutrino-antineutrino mass and mixing angle differences; we found, for example,
that the sensitivity
could be achieved.Comment: 6 pages, 1 figure, RevTeX4. Final version to be published in Phys.
Rev.
Genetics of human neural tube defects
Neural tube defects (NTDs) are common, severe congenital malformations whose causation involves multiple genes and environmental factors. Although more than 200 genes are known to cause NTDs in mice, there has been rather limited progress in delineating the molecular basis underlying most human NTDs. Numerous genetic studies have been carried out to investigate candidate genes in cohorts of patients, with particular reference to those that participate in folate one-carbon metabolism. Although the homocysteine remethylation gene MTHFR has emerged as a risk factor in some human populations, few other consistent findings have resulted from this approach. Similarly, attention focused on the human homologues of mouse NTD genes has contributed only limited positive findings to date, although an emerging association between genes of the non-canonical Wnt (planar cell polarity) pathway and NTDs provides candidates for future studies. Priorities for the next phase of this research include: (i) larger studies that are sufficiently powered to detect significant associations with relatively minor risk factors; (ii) analysis of multiple candidate genes in groups of well-genotyped individuals to detect possible gene–gene interactions; (iii) use of high throughput genomic technology to evaluate the role of copy number variants and to detect ‘private’ and regulatory mutations, neither of which have been studied to date; (iv) detailed analysis of patient samples stratified by phenotype to enable, for example, hypothesis-driven testing of candidates genes in groups of NTDs with specific defects of folate metabolism, or in groups of fetuses with well-defined phenotypes such as craniorachischisis
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Climate Forcing and Trends of Organic Aerosols in the Community Earth System Model (CESM2)
Abstract The Community Earth System Model version 2 (CESM2) includes three main atmospheric configurations: the Community Atmosphere Model version 6 (CAM6) with simplified chemistry and a simplified organic aerosol (OA) scheme, CAM6 with comprehensive tropospheric and stratospheric chemistry representation (CAM6‐chem), and the Whole Atmosphere Community Climate Model version 6 (WACCM6). Both, CAM6‐chem and WACCM6 include a more comprehensive secondary organic aerosols (SOA) approach using the Volatility Basis Set (VBS) scheme and prognostic stratospheric aerosols. This paper describes the different OA schemes available in the different atmospheric configurations of CESM2 and discusses differences in aerosol burden and resulting climate forcings. Derived OA burden and trends differ due to differences in OA formation using the different approaches. Regional differences in Aerosol Optical Depth with larger values using the comprehensive approach occur over SOA source regions. Stronger increasing SOA trends between 1960 and 2015 in WACCM6 compared to CAM6 are due to increasing biogenic emissions aligned with increasing surface temperatures. Using the comprehensive SOA approach further leads to improved comparisons to aircraft observations and SOA formation of ≈143 Tg/yr. We further use WACCM6 to identify source contributions of OA from biogenic, fossil fuel, and biomass burning emissions, to quantify SOA amounts and trends from these sources. Increasing SOA trends between 1960 and 2015 are the result of increasing biogenic emissions aligned with increasing surface temperatures. Biogenic emissions are at least two thirds of the total SOA burden. In addition, SOA source contributions from fossil fuel emissions become more important, with largest values over Southeast Asia. The estimated total anthropogenic forcing of OA in WACCM6 for 1995–2010 conditions is −0.43 W/m2, mostly from the aerosol direct effect.</p
Is symmetry identity?
Wigner found unreasonable the "effectiveness of mathematics in the natural
sciences". But if the mathematics we use to describe nature is simply a coded
expression of our experience then its effectiveness is quite reasonable. Its
effectiveness is built into its design. We consider group theory, the logic of
symmetry. We examine the premise that symmetry is identity; that group theory
encodes our experience of identification. To decide whether group theory
describes the world in such an elemental way we catalogue the detailed
correspondence between elements of the physical world and elements of the
formalism. Providing an unequivocal match between concept and mathematical
statement completes the case. It makes effectiveness appear reasonable. The
case that symmetry is identity is a strong one but it is not complete. The
further validation required suggests that unexpected entities might be
describable by the irreducible representations of group theory
Global Search for New Physics with 2.0/fb at CDF
Data collected in Run II of the Fermilab Tevatron are searched for
indications of new electroweak-scale physics. Rather than focusing on
particular new physics scenarios, CDF data are analyzed for discrepancies with
the standard model prediction. A model-independent approach (Vista) considers
gross features of the data, and is sensitive to new large cross-section
physics. Further sensitivity to new physics is provided by two additional
algorithms: a Bump Hunter searches invariant mass distributions for "bumps"
that could indicate resonant production of new particles; and the Sleuth
procedure scans for data excesses at large summed transverse momentum. This
combined global search for new physics in 2.0/fb of ppbar collisions at
sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D
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