320 research outputs found
Generalized Euler-Poincar\'e equations on Lie groups and homogeneous spaces, orbit invariants and applications
We develop the necessary tools, including a notion of logarithmic derivative
for curves in homogeneous spaces, for deriving a general class of equations
including Euler-Poincar\'e equations on Lie groups and homogeneous spaces.
Orbit invariants play an important role in this context and we use these
invariants to prove global existence and uniqueness results for a class of PDE.
This class includes Euler-Poincar\'e equations that have not yet been
considered in the literature as well as integrable equations like Camassa-Holm,
Degasperis-Procesi, CH and DP equations, and the geodesic equations
with respect to right invariant Sobolev metrics on the group of diffeomorphisms
of the circle
The phase diagram of quantum systems: Heisenberg antiferromagnets
A novel approach for studying phase transitions in systems with quantum
degrees of freedom is discussed. Starting from the microscopic hamiltonian of a
quantum model, we first derive a set of exact differential equations for the
free energy and the correlation functions describing the effects of
fluctuations on the thermodynamics of the system. These equations reproduce the
full renormalization group structure in the neighborhood of a critical point
keeping, at the same time, full information on the non universal properties of
the model. As a concrete application we investigate the phase diagram of a
Heisenberg antiferromagnet in a staggered external magnetic field. At long
wavelengths the known relationship to the Quantum Non Linear Sigma Model
naturally emerges from our approach. By representing the two point function in
an approximate analytical form, we obtain a closed partial differential
equation which is then solved numerically. The results in three dimensions are
in good agreement with available Quantum Monte Carlo simulations and series
expansions. More refined approximations to the general framework presented here
and few applications to other models are briefly discussed.Comment: 17 pages, 7 figure
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
Mechanical performance and healing patterns of the novel sirolimus-eluting bioresorbable Fantom scaffold: 6-month and 9-month follow-up by optical coherence tomography in the FANTOM II study
Objectives We aimed to evaluate the mechanical properties
and healing patterns 6 and 9 months after implantation of the
sirolimus-eluting Fantom bioresorbable scaffold (BRS).
Background The Fantom BRS (Reva Medical, San Diego,
USA) has differentiating properties including radiopacity,
strut thickness of 125 µm, high expansion capacity and
has demonstrated favourable mid-term clinical and
angiographic outcomes.
Methods and results FANTOM II was a prospective,
single arm study with implantation of the Fantom BRS
in 240 patients with stable angina pectoris. Guidance by
optical coherence tomography (OCT) was encouraged and
was repeated at 6-month (cohort A) or 9-month follow-up
(cohort B). Matched baseline and follow-up OCT recordings
were available in 152 patients. In-scaffold mean lumen
area in cohort A was 6.8±1.7mm2
and 5.7±1.4mm2
at baseline and follow-up (p<0.0001) and was
7.2±1.6mm2
and 5.6±1.4mm2
in cohort B (p<0.0001).
Mean scaffold area remained stable from 7.1±1.5mm2
at baseline to 7.2±1.4mm2
at 6 months (p=0.12), and
from 7.4±1.5mm2
to 7.3±1.4mm2
at 9 months. Strut
malapposition was median 0.8 (IQR 0.0;3.5)% and 1.8 (IQR
0.3;6.0)% at baseline and was 0.0 (IQR 0.0;0.0)% in both
groups at 6-month and 9-month follow-up. Strut tissue
coverage was 98.1 (IQR 95.9;99.4)% at 6 months and
98.9 (IQR 98.3;100.0)% at 9 months.
Conclusions The novel Fantom BRS had favourable
healing patterns at 6-month and 9-month follow-up as
malapposition was effectively resolved and strut coverage
was almost complete. The scaffold remained stable
through follow-up with no signs of systematic late recoil
Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA
In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2
The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019
BACKGROUND: Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. METHODS: The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. FINDINGS: Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]). INTERPRETATION: The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden
Search for pair production of boosted Higgs bosons via vector-boson fusion in the bb¯bb¯ final state using pp collisions at √s = 13 TeV with the ATLAS detector
A search for Higgs boson pair production via vector-boson fusion is performed in the Lorentz-boosted regime,
where a Higgs boson candidate is reconstructed as a single large-radius jet, using 140 fb−1 of proton–proton
collision data at √s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Only Higgs boson
decays into bottom quark pairs are considered. The search is particularly sensitive to the quartic coupling between
two vector bosons and two Higgs bosons relative to its Standard Model prediction, K2V . This study constrains K2V
to 0.55 < K2V < 1.49 at the 95% confidence level. The value K2V = 0 is excluded with a significance of 3.8 standard
deviations with other Higgs boson couplings fixed to their Standard Model values. A search for new heavy spin-0
resonances that would mediate Higgs boson pair production via vector-boson fusion is carried out in the mass
range of 1–5 TeV for the first time under several model and decay-width assumptions. No significant deviation
from the Standard Model hypothesis is observed and exclusion limits at the 95% confidence level are derived
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