172 research outputs found
Cause-specific long-term mortality in survivors of childhood cancer in Switzerland: A population-based study.
Survivors of childhood cancer have a higher mortality than the general population. We describe cause-specific long-term mortality in a population-based cohort of childhood cancer survivors. We included all children diagnosed with cancer in Switzerland (1976-2007) at age 0-14 years, who survived ≥5 years after diagnosis and followed survivors until December 31, 2012. We obtained causes of death (COD) from the Swiss mortality statistics and used data from the Swiss general population to calculate age-, calendar year-, and sex-standardized mortality ratios (SMR), and absolute excess risks (AER) for different COD, by Poisson regression. We included 3,965 survivors and 49,704 person years at risk. Of these, 246 (6.2%) died, which was 11 times higher than expected (SMR 11.0). Mortality was particularly high for diseases of the respiratory (SMR 14.8) and circulatory system (SMR 12.7), and for second cancers (SMR 11.6). The pattern of cause-specific mortality differed by primary cancer diagnosis, and changed with time since diagnosis. In the first 10 years after 5-year survival, 78.9% of excess deaths were caused by recurrence of the original cancer (AER 46.1). Twenty-five years after diagnosis, only 36.5% (AER 9.1) were caused by recurrence, 21.3% by second cancers (AER 5.3) and 33.3% by circulatory diseases (AER 8.3). Our study confirms an elevated mortality in survivors of childhood cancer for at least 30 years after diagnosis with an increased proportion of deaths caused by late toxicities of the treatment. The results underline the importance of clinical follow-up continuing years after the end of treatment for childhood cancer
Stuffed Rare Earth Pyrochlore Solid Solutions
Synthesis and crystal structures are described for the compounds
Ln2(Ti2-xLnx)O7-x/2, where Ln = Tb, Dy, Ho, Er, Tm, Yb, Lu, and x ranges from 0
to 0.67. Rietveld refinements on X-ray powder diffraction data indicate that in
Tb and Dy titanate pyrochlores, extra Ln3+ cations mix mainly on the Ti4+ site
with little disorder on the original Ln3+ site. For the smaller rare earths
(Ho-Lu), stuffing additional lanthanide ions results in a pyrochlore to defect
fluorite transition, where the Ln3+ and Ti4+ ions become completely randomized
at the maximum (x=0.67). In all of these Ln-Ti-O pyrochlores, the addition of
magnetic Ln3+ in place of nonmagnetic Ti4+ adds edge sharing tetrahedral spin
interactions to a normally corner sharing tetrahedral network of spins. The
increase in spin connectivity in this family of solid solutions represents a
new avenue for investigating geometrical magnetic frustration in the rare earth
titanate pyrochlores.Comment: 25 pages, 7 figures, submitted to J. Solid State Che
Magnetic Reconnection in Extreme Astrophysical Environments
Magnetic reconnection is a basic plasma process of dramatic rearrangement of
magnetic topology, often leading to a violent release of magnetic energy. It is
important in magnetic fusion and in space and solar physics --- areas that have
so far provided the context for most of reconnection research. Importantly,
these environments consist just of electrons and ions and the dissipated energy
always stays with the plasma. In contrast, in this paper I introduce a new
direction of research, motivated by several important problems in high-energy
astrophysics --- reconnection in high energy density (HED) radiative plasmas,
where radiation pressure and radiative cooling become dominant factors in the
pressure and energy balance. I identify the key processes distinguishing HED
reconnection: special-relativistic effects; radiative effects (radiative
cooling, radiation pressure, and Compton resistivity); and, at the most extreme
end, QED effects, including pair creation. I then discuss the main
astrophysical applications --- situations with magnetar-strength fields
(exceeding the quantum critical field of about 4 x 10^13 G): giant SGR flares
and magnetically-powered central engines and jets of GRBs. Here, magnetic
energy density is so high that its dissipation heats the plasma to MeV
temperatures. Electron-positron pairs are then copiously produced, making the
reconnection layer highly collisional and dressing it in a thick pair coat that
traps radiation. The pressure is dominated by radiation and pairs. Yet,
radiation diffusion across the layer may be faster than the global Alfv\'en
transit time; then, radiative cooling governs the thermodynamics and
reconnection becomes a radiative transfer problem, greatly affected by the
ultra-strong magnetic field. This overall picture is very different from our
traditional picture of reconnection and thus represents a new frontier in
reconnection research.Comment: Accepted to Space Science Reviews (special issue on magnetic
reconnection). Article is based on an invited review talk at the
Yosemite-2010 Workshop on Magnetic Reconnection (Yosemite NP, CA, USA;
February 8-12, 2010). 30 pages, no figure
Meta-analysis identifies seven susceptibility loci involved in the atopic March
Eczema often precedes the development of asthma in a disease course called the a 'atopic march'. To unravel the genes underlying this characteristic pattern of allergic disease, we conduct a multi-stage genome-wide association study on infantile eczema followed by childhood asthma in 12 populations including 2,428 cases and 17,034 controls. Here we report two novel loci specific for the combined eczema plus asthma phenotype, which are associated with allergic disease for the first time; rs9357733 located in EFHC1 on chromosome 6p12.3 (OR 1.27; P=2.1 × 10 a'8) and rs993226 between TMTC2 and SLC6A15 on chromosome 12q21.3 (OR 1.58; P=5.3 × 10 a'9). Additional susceptibility loci identified
Constraining the electric charges of some astronomical bodies in Reissner-Nordstrom spacetimes and generic r^-2-type power-law potentials from orbital motions
We put model-independent, dynamical constraints on the net electric charge Q
of some astronomical and astrophysical objects by assuming that their exterior
spacetimes are described by the Reissner-Nordstroem metric, which induces an
additional potential U_RN \propto Q^2 r^-2. Our results extend to other
hypothetical power-law interactions inducing extra-potentials U_pert = r^-2 as
well (abridged).Comment: LaTex2e, 16 pages, 3 figures, no tables, 128 references. Version
matching the one at press in General Relativity and Gravitation (GRG). arXiv
admin note: substantial text overlap with arXiv:1112.351
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model
We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)
[no abstract available
Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background
The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society
- …