3,974 research outputs found
An epidemiological study of cancer in adult twins born in Norway 1905–1945
We have identified 23 334 individuals (40%) of twins born in Norway 1905–45 where both twins were alive in 1960 without malignant disease. These were linked to the Cancer Registry of Norway. A reduced risk of malignant disease was demonstrated among twins for all tumour sites combined; standardized incidence rate (SIR): 0.90 (95% CI 0.85–0.94) in females and 0.95 (95% Cl 0.90–0.99) in males. In both sexes, we observed a significant reduced incidence of malignant melanomas of the skin. The incidence of colorectal cancer tended to be reduced for both sexes. In females, the incidence of tumours of the central nervous system and lungs were reduced. We consider our findings are real, but cannot explain them. © 2001 Cancer Research Campaign http://www.bjcancer.co
Escaping many-body localization in an exact eigenstate
Isolated quantum systems typically follow the eigenstate thermalization
hypothesis, but there are exceptions, such as many-body localized (MBL) systems
and quantum many-body scars. Here, we present the study of a weak violation of
MBL due to a special state embedded in a spectrum of MBL states. The special
state is not MBL since it displays logarithmic scaling of the entanglement
entropy and of the bipartite fluctuations of particle number with subsystem
size. In contrast, the bulk of the spectrum becomes MBL as disorder is
introduced. We establish this by studying the entropy as a function of disorder
strength and by observing that the level spacing statistics undergoes a
transition from Wigner-Dyson to Poisson statistics as the disorder strength is
increased.Comment: 8 pages, 7 figure
A Helium-Surface Interaction Potential of BiTe(111) from Ultrahigh-Resolution Spin-Echo Measurements
We have determined an atom-surface interaction potential for the
HeBiTe(111) system by analysing ultrahigh resolution measurements of
selective adsorption resonances. The experimental measurements were obtained
using He spin-echo spectrometry. Following an initial free-particle model
analysis, we use elastic close-coupling calculations to obtain a
three-dimensional potential. The three-dimensional potential is then further
refined based on the experimental data set, giving rise to an optimised
potential which fully reproduces the experimental data. Based on this analysis,
the HeBiTe(111) interaction potential can be described by a
corrugated Morse potential with a well depth , a
stiffness and a surface electronic
corrugation of % of the lattice constant. The improved
uncertainties of the atom-surface interaction potential should also enable the
use in inelastic close-coupled calculations in order to eventually study the
temperature dependence and the line width of selective adsorption resonances
Probing the isovector transition strength of the low-lying nuclear excitations induced by inverse kinematics proton scattering
A compact approach based on the folding model is suggested for the
determination of the isoscalar and isovector transition strengths of the
low-lying () excitations induced by inelastic proton
scattering measured with exotic beams. Our analysis of the recently measured
inelastic O+p scattering data at and 43 MeV/nucleon
has given for the first time an accurate estimate of the isoscalar
and isovector deformation parameters (which cannot be determined from
the (p,p') data alone by standard methods) for 2 and excited
states in O. Quite strong isovector mixing was found in the 2
inelastic O+p scattering channel, where the strength of the isovector
form factor (prototype of the Lane potential) corresponds to a
value almost 3 times larger than and a ratio of nuclear transition
matrix elements .Comment: 5 pages, 3 figure
Embeddings of SL(2,Z) into the Cremona group
Geometric and dynamic properties of embeddings of SL(2,Z) into the Cremona
group are studied. Infinitely many non-conjugate embeddings which preserve the
type (i.e. which send elliptic, parabolic and hyperbolic elements onto elements
of the same type) are provided. The existence of infinitely many non-conjugate
elliptic, parabolic and hyperbolic embeddings is also shown.
In particular, a group G of automorphisms of a smooth surface S obtained by
blowing-up 10 points of the complex projective plane is given. The group G is
isomorphic to SL(2,Z), preserves an elliptic curve and all its elements of
infinite order are hyperbolic.Comment: to appear in Transformation Group
Evidence for a direct band gap in the topological insulator Bi2Se3 from theory and experiment
Using angle-resolved photoelectron spectroscopy and ab-initio GW
calculations, we unambiguously show that the widely investigated
three-dimensional topological insulator Bi2Se3 has a direct band gap at the
Gamma point. Experimentally, this is shown by a three-dimensional band mapping
in large fractions of the Brillouin zone. Theoretically, we demonstrate that
the valence band maximum is located at the Brillouin center only if many-body
effects are included in the calculation. Otherwise, it is found in a
high-symmetry mirror plane away from the zone center.Comment: 8 pages, 4 figure
Capsular profiling of the Cronobacter genus and the association of specific Cronobacter sakazakii and C. malonaticus capsule types with neonatal meningitis and necrotizing enterocolitis
Background: Cronobacter sakazakii and C. malonaticus can cause serious diseases especially in infants where they are associated with rare but fatal neonatal infections such as meningitis and necrotising enterocolitis.
Methods: This study used 104 whole genome sequenced strains, covering all seven species in the genus, to analyse capsule associated clusters of genes involved in the biosynthesis of the O-antigen, colanic acid, bacterial cellulose, enterobacterial common antigen (ECA), and a previously uncharacterised K-antigen.
Results: Phylogeny of the gnd and galF genes flanking the O-antigen region enabled the defining of 38 subgroups which are potential serotypes. Two variants of the colanic acid synthesis gene cluster (CA1 and CA2) were found which differed with the absence of galE in CA2. Cellulose (bcs genes) were present in all species, but were absent in C. sakazakii sequence type (ST) 13 and clonal complex (CC) 100 strains. The ECA locus was found in all strains. The K-antigen capsular polysaccharide Region 1 (kpsEDCS) and Region 3 (kpsMT) genes were found in all Cronobacter strains. The highly variable Region 2 genes were assigned to 2 homology groups (K1 and K2). C. sakazakii and C. malonaticus isolates with capsular type [K2:CA2:Cell+] were associated with neonatal meningitis and necrotizing enterocolitis. Other capsular types were less associated with clinical infections. Conclusion: This study proposes a new capsular typing scheme which identifies a possible important virulence trait associated with severe neonatal infections. The various capsular polysaccharide structures warrant further investigation as they could be relevant to macrophage survival, desiccation resistance, environmental survival, and biofilm formation in the hospital environment, including neonatal enteral feeding tubes
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Quantifying sources of inter-model diversity in the cloud albedo effect
There is large diversity in simulated aerosol forcing among models that participated in the fifth Coupled Model Intercomparison Project (CMIP5), particularly related to aerosol interactions with clouds. Here we use the reported model data and fitted aerosol-cloud relations to separate the main sources of inter-model diversity in the magnitude of the cloud albedo effect. There is large diversity in the global load and spatial distribution of sulfate aerosol, as well as in global-mean cloud-top effective radius. The use of different parameterizations of aerosol-cloud interactions makes the largest contribution to diversity
in modeled radiative forcing (up to -39%, +48% about the mean estimate). Uncertainty in pre-industrial sulfate load also makes a substantial contribution (-15%, +61% about the mean estimate), with smaller contributions from inter-model differences in the historical change in sulfate load and in mean cloud fraction
The effect of harmonized emissions on aerosol properties in global models – an AeroCom experiment
The effects of unified aerosol sources on global aerosol fields simulated by different models are examined in this paper. We compare results from two AeroCom experiments, one with different (ExpA) and one with unified emissions, injection heights, and particle sizes at the source (ExpB). Surprisingly, harmonization of aerosol sources has only a small impact on the simulated diversity for aerosol burden, and consequently optical properties, as the results are largely controlled by model-specific transport, removal, chemistry (leading to the formation of secondary aerosols) and parameterizations of aerosol microphysics (e.g. the split between deposition pathways) and to a lesser extent on the spatial and temporal distributions of the (precursor) emissions.
The burdens of black carbon and especially sea salt become more coherent in ExpB only, because the large ExpA diversity for these two species was caused by few outliers. The experiment also indicated that despite prescribing emission fluxes and size distributions, ambiguities in the implementation in individual models can lead to substantial differences.
These results indicate the need for a better understanding of aerosol life cycles at process level (including spatial dispersal and interaction with meteorological parameters) in order to obtain more reliable results from global aerosol simulations. This is particularly important as such model results are used to assess the consequences of specific air pollution abatement strategies
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