6,156 research outputs found
Modulation of charge-density waves by superlattice structures
We discuss the interplay between electronic correlations and an underlying
superlattice structure in determining the period of charge density waves
(CDW's), by considering a one-dimensional Hubbard model with a repeated
(non-random) pattern of repulsive (U>0) and free (U=0) sites. Density matrix
renormalization group diagonalization of finite systems (up to 120 sites) is
used to calculate the charge-density correlation function and structure factor
in the ground state. The modulation period can still be predicted through
effective Fermi wavevectors, k_F*, and densities, and we have found that it is
much more sensitive to electron (or hole) doping, both because of the narrow
range of densities needed to go from q*=0 to \pi, but also due to sharp
2k_F*-4k_F* transitions; these features render CDW's more versatile for actual
applications in heterostructures than in homogeneous systems.Comment: 4 pages, 5 figures, to appear in Phys Rev
Bethe Ansatz solutions for Temperley-Lieb Quantum Spin Chains
We solve the spectrum of quantum spin chains based on representations of the
Temperley-Lieb algebra associated with the quantum groups for and . The tool is a
modified version of the coordinate Bethe Ansatz through a suitable choice of
the Bethe states which give to all models the same status relative to their
diagonalization. All these models have equivalent spectra up to degeneracies
and the spectra of the lower dimensional representations are contained in the
higher-dimensional ones. Periodic boundary conditions, free boundary conditions
and closed non-local boundary conditions are considered. Periodic boundary
conditions, unlike free boundary conditions, break quantum group invariance.
For closed non-local cases the models are quantum group invariant as well as
periodic in a certain sense.Comment: 28 pages, plain LaTex, no figures, to appear in Int. J. Mod. Phys.
Charm lifetime
A review of the charmed meson and baryon lifetimes is presented. Our
knowledge of charmed particle lifetimes has greatly improved over the past two
years, a crucial r\^ole having been played by the E687 experiment at Fermilab,
which has almost quadrupled the samples of mesons. The lifetime ratios
and are now known with an
accuracy of 1.7\% and 3.7\% respectively. In the baryon sector the statistics
is still limited, but the experimental results on , and
exhibit a clear pattern of lifetime hierarchy, as expected from
simple theoretical arguments. The first measurement of from
E687 is also presented to complete the charmed baryon lifetime picture. The
more accurate experimental scenario can provide information on non-perturbative
QCD effects and the hadronic matrix elements.Comment: 10 pages, latex, 3 figures. Talk presented at the 6th. International
Symposium on Heavy Flavour Physics (Pisa, June 1995
European cancer mortality predictions for the year 2020 with a focus on prostate cancer
Background: Current cancer mortality figures are important for disease management and resource allocation. We estimated mortality counts and rates for 2020 in the European Union (EU) and for its six most populous countries.
Materials and methods: We obtained cancer death certification and population data from the World Health Organization and Eurostat databases for 1970-2015. We estimated projections to 2020 for 10 major cancer sites plus all neoplasms and calculated the number of avoided deaths over 1989-2020.
Results: Total cancer mortality rates in the EU are predicted to decline reaching 130.1/100 000 men (-5.4% since 2015) and 82.2 in women (-4.1%) in 2020. The predicted number of deaths will increase by 4.7% reaching 1 428 800 in 2020. In women, the upward lung cancer trend is predicted to continue with a rate in 2020 of 15.1/100 000 (higher than that for breast cancer, 13.5) while in men we predicted further falls. Pancreatic cancer rates are also increasing in women (+1.2%) but decreasing in men (-1.9%). In the EU, the prostate cancer predicted rate is 10.0/100 000, declining by 7.1% since 2015; decreases for this neoplasm are 3c8% at age 45-64, 14% at 65-74 and 75-84, and 6% at 85 and over. Poland is the only country with an increasing prostate cancer trend (+18%). Mortality rates for other cancers are predicted to decline further. Over 1989-2020, we estimated over 5 million avoided total cancer deaths and over 400 000 for prostate cancer.
Conclusion: Cancer mortality predictions for 2020 in the EU are favourable with a greater decline in men. The number of deaths continue to rise due to population ageing. Due to the persistent amount of predicted lung (and other tobacco-related) cancer deaths, tobacco control remains a public health priority, especially for women. Favourable trends for prostate cancer are largely attributable to continuing therapeutic improvements along with early diagnosis
European cancer mortality predictions for the year 2012
Background: Estimating current cancer mortality figures is important for defining priorities for prevention and treatment. Materials and methods: Using logarithmic Poisson count data joinpoint models on mortality and population data from the World Health Organization database, we estimated numbers of deaths and age-standardized rates in 2012 from all cancers and selected cancer sites for the whole European Union (EU) and its six more populated countries. Results: Cancer deaths in the EU in 2012 are estimated to be 1 283 101 (717 398 men and 565 703 women) corresponding to standardized overall cancer death rates of 139/100 000 men and 85/100 000 women. The fall from 2007 was 10% in men and 7% in women. In men, declines are predicted for stomach (−20%), leukemias (−11%), lung and prostate (−10%) and colorectal (−7%) cancers, and for stomach (−23%), leukemias (−12%), uterus and colorectum (−11%) and breast (−9%) in women. Almost stable rates are expected for pancreatic cancer (+2-3%) and increases for female lung cancer (+7%). Younger women show the greatest falls in breast cancer mortality rates in the EU (−17%), and declines are expected in all individual countries, except Poland. Conclusion: Apart for lung cancer in women and pancreatic cancer, continuing falls are expected in mortality from major cancers in the E
European cancer mortality predictions for the year 2019 with focus on breast cancer
Background We predicted cancer mortality figures in the European Union (EU) for the year 2017 using most recent available data, with a focus on lung cancer. Materials and methods We retrieved cancer death certification data and population figures from the World Health Organisation and Eurostat databases. Age-standardized (world standard population) rates were computed for France, Germany, Italy, Poland, Spain, the UK and the EU overall in 1970–2012. We obtained estimates for 2017 by implementing a joinpoint regression model. Results The predicted number of cancer deaths for 2017 in the EU is 1 373 500, compared with 1 333 400 in 2012 (+3%). Cancer mortality rates are predicted to decline in both sexes, reaching 131.8/100 000 men (−8.2% when compared with 2012) and 84.5/100 000 women (−3.6%). Mortality rates for all selected cancer sites are predicted to decline, except pancreatic cancer in both sexes and lung cancer in women. In men, pancreatic cancer rate is stable, in women it increases by 3.5%. Lung cancer mortality rate in women is predicted to rise to 14.6/100 000 in 2017 (+5.1% since 2012, corresponding to 92 300 predicted deaths), compared with 14.0/100 000 for breast cancer, corresponding to 92 600 predicted deaths. Only younger (25–44) women have favourable lung cancer trends, and rates at this age group are predicted to be similar in women (1.4/100 000) and men (1.2/100 000). In men lung cancer rates are predicted to decline by 10.7% since 2012, and falls are observed in all age groups. Conclusion European cancer mortality projections for 2017 confirm the overall downward trend in rates, with a stronger pattern in men. This is mainly due to different smoking prevalence trends in different generations of men and women. Lung cancer rates in young European women are comparable to those in men, confirming that smoking has the same impact on lung cancer in the two sexes
reply to the letter to the editor european cancer mortality predictions for the year 2019 with focus on breast cancer by malvezzi m et al by marsden and hamoda on behalf of the british menopause society medical advisory council
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Cancer mortality in the elderly in 11 countries worldwide, 1970-2015
BACKGROUND:
Population ageing results in an increasing cancer burden in the elderly. We aimed to evaluate time-trends in cancermortality for adults aged 65 and over for 17 major cancer-types and all cancer combined in 11 countries worldwide over the period 1970-2015.
MATERIALS AND METHODS:
We obtained cancer death certification and population figures from the WHO and PAHO databases. We computed age-standardized (world standard population) rates for individuals aged 65 and over, and applied joinpoint regression models.
RESULTS:
Age-standardized mortality rates for all cancers combined showed a heterogeneous, but widespread decline. Lung cancermortality rates have been decreasing among men, and increasing among women. Pancreatic cancer had unfavourable trends in all countriesfor both sexes. Despite variability across countries, other tobacco-related cancers (except kidney) showed overall favourable trends, except in Poland and Russia. Age-standardized mortality from stomach cancer has been declining in all countries for both sexes. Colorectal mortalityhas been declining, except in Poland and Russia. Liver cancer mortality increased in all countries, except in Japan, France and Italy, which had the highest rates in the past. Breast cancer mortality decreased for most countries, except for Japan, Poland and Russia. Trends for age-standardized uterine cancer rates in the USA, Canada and the UK were increasing over the last decade. Ovarian cancer rates showed declines in most countries. With the exception of Russia, prostate cancer rates showed overall declines. Lymphoid neoplasm rates have been declining in both sexes, except in Poland and Russia.
CONCLUSION:
Over the last decades, age-standardized cancer mortality in the elderly has been decreasing in major countries worldwideand for major cancer sites, with the major exception of lung and uterine cancer in women and liver, pancreas and kidney cancers in both sexes. Cancer mortality for the elderly in Central and Eastern Europe remains comparatively high
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