945 research outputs found
Fatou flowers and parabolic curves
In this survey we collect the main results known up to now (July 2015) regarding possible generalizations to several complex variables of the classical Leau-Fatou flower theorem about holomorphic parabolic dynamics
Line shape of the muH(3p - 1s) hyperfine transitions
The (3p - 1s) X-ray transition to the muonic hydrogen ground state was
measured with a high resolution crystal spectrometer. A Doppler effect
broadening of the X-ray line was established which could be attributed to
different Coulomb de-excitation steps preceding the measured transition. The
assumption of a statistical population of the hyperfine levels of the muonic
hydrogen ground state was directly confirmed by the experiment and measured
values for the hyperfine splitting can be reported. The results allow a
decisive test of advanced cascade model calculations and establish a method to
extract fundamental strong-interaction parameters from pionic hydrogen
experiments.Comment: Submitted to Physical Review Letter
Holomorphic linearization of commuting germs of holomorphic maps
Let be germs of biholomorphisms of \C^n fixing the
origin. We investigate the shape a (formal) simultaneous linearization of the
given germs can have, and we prove that if commute and their
linear parts are almost simultaneously Jordanizable then they are
simultaneously formally linearizable. We next introduce a simultaneous
Brjuno-type condition and prove that, in case the linear terms of the germs are
diagonalizable, if the germs commutes and our Brjuno-type condition holds, then
they are holomorphically simultaneously linerizable. This answers to a
multi-dimensional version of a problem raised by Moser.Comment: 24 pages; final version with erratum (My original paper failed to
cite the work of L. Stolovitch [ArXiv:math/0506052v2]); J. Geom. Anal. 201
Role of virtual break-up of projectile in astrophysical fusion reactions
We study the effect of virtual Coulomb break-up, commonly known as the dipole
polarizability, of the deuteron projectile on the astrophysical fusion reaction
3He(d,p)4He. We use the adiabatic approximation to estimate the potential shift
due to the E1 transition to the continuum states in the deuteron, and compute
the barrier penetrability in the WKB approximation. We find that the
enhancement of the penetrability due to the deuteron break-up is too small to
resolve the longstanding puzzle observed in laboratory measurements that the
electron screening effect is surprisingly larger than theoretical prediction
based on an atomic physics model. The effect of the 3He break-up in the
3He(d,p)4He reaction, as well as the 7Li break-up in the 7Li(p,alpha)4He
reaction is also discussed.Comment: 9 pages, 2 eps figure
Muonic hydrogen cascade time and lifetime of the short-lived state
Metastable muonic-hydrogen atoms undergo collisional -quenching,
with rates which depend strongly on whether the kinetic energy is above
or below the energy threshold. Above threshold, collisional
excitation followed by fast radiative
deexcitation is allowed. The corresponding short-lived component
was measured at 0.6 hPa room temperature gas pressure, with
lifetime ns (i.e.,
at liquid-hydrogen density) and population
% (per atom). In
addition, a value of the cascade time, ns, was found.Comment: 4 pages, 3 figure
Mechanism of miR-222 and miR-126 regulation and its role in asbestos-induced malignancy
MiR-222 and miR-126 are associated with asbestos exposure and the ensuing malignancy, but the mechanism(s) of their regulation remain unclear. We evaluated the mechanism by which asbestos regulates miR-222 and miR-126 expression in the context of cancer etiology. An âin vitroâ model of carcinogen-induced cell transformation was used based on exposing bronchial epithelium BEAS-2B cells to three different carcinogens including asbestos. Involvement of the EGFR pathway and the role of epigenetics have been investigated in carcinogen-transformed cells and in malignant mesothelioma, a neoplastic disease associated with asbestos exposure. Increased expression of miR-222 and miR-126 were found in asbestos-transformed cells, but not in cells exposed to arsenic and chrome. Asbestos-mediated activation of the EGFR pathway and macrophages-induced inflammation resulted in miR-222 upregulation, which was reversed by EGFR inhibition. Conversely, asbestos-induced miR-126 expression was affected neither by EGFR modulation nor inflammation. Rather than methylation of the miR-126 host gene EGFL7, epigenetic mechanism involving DNMT1- and PARP1-mediated chromatin remodeling was found to upregulate of miR-126 in asbestos-exposed cells, while miR-126 was downregulated in malignant cells. Analysis of MM tissue supported the role of PARP1 in miR-126 regulation. Therefore, activation of the EGFR pathway and the PARP1-mediated epigenetic regulation both play a role in asbestos-induced miRNA expression, associated with in asbestos-induced carcinogenesis and tumor progression
Long-term adherence to a mediterranean diet 1-Year after completion of the MedLey study
Mediterranean populations enjoy the health benefits of a Mediterranean diet (MedDiet), but is it feasible to implement such a pattern beyond the Mediterranean region? The MedLey trial, a 6-month MedDiet intervention vs habitual diet in older Australians, demonstrated that the participants could maintain high adherence to a MedDiet for 6 months. The MedDiet resulted in improved systolic blood pressure (BP), endothelial dilatation, oxidative stress, and plasma triglycerides in comparison with the habitual diet. We sought to determine if 12 months after finishing the MedLey study, the participants maintained their adherence to the MedDiet principles and whether the reduction in the cardiovascular disease (CVD) risk factors that were seen in the trial were sustained. Participants completed a food frequency questionnaire, and a 15-point MedDiet adherence score (MDAS; greater score = greater adherence) was calculated. Home BP was measured over 6 days, BMI was assessed, and fasting plasma triglycerides were measured. The data were analysed using intention-to-treat linear mixed effects models with a group à time interaction term, comparing data at baseline, 2, 4, and 18 months (12 months post-trial). At 18 months (12 months after finishing the MedLey study), the MedDiet group had a MDAS of 7.9 ± 0.3, compared to 9.6 ± 0.2 at 4 months (p \u3c 0.0001), and 6.7 ± 0.2 (p \u3c 0.0001), at baseline. The MDAS in the HabDiet group remained unchanged over the 18-month period (18 months 6.9 ± 0.3, 4 months 6.9 ± 0.2, baseline 6.7 ± 0.2). In the MedDiet group, the consumption of olive oil, legumes, fish, and vegetables remained higher (p \u3c 0.01, compared with baseline) and discretionary food consumption remained lower (p = 0.02) at 18 months. These data show that some MedDiet principles could be adhered to for 12 months after finishing the MedLey trial. However, improvements in cardiometabolic health markers, including BP and plasma triglycerides, were not sustained. The results indicate that further dietary support for behaviour change may be beneficial to maintaining high adherence and metabolic benefits of the MedDiet
Pseudo-Hermitian Hamiltonians, indefinite inner product spaces and their symmetries
We extend the definition of generalized parity , charge-conjugation
and time-reversal operators to nondiagonalizable pseudo-Hermitian
Hamiltonians, and we use these generalized operators to describe the full set
of symmetries of a pseudo-Hermitian Hamiltonian according to a fourfold
classification. In particular we show that and are the generators of
the antiunitary symmetries; moreover, a necessary and sufficient condition is
provided for a pseudo-Hermitian Hamiltonian to admit a -reflecting
symmetry which generates the -pseudounitary and the -pseudoantiunitary
symmetries. Finally, a physical example is considered and some hints on the
-unitary evolution of a physical system are also given.Comment: 20 page
Atomic effects in astrophysical nuclear reactions
Two models are presented for the description of the electron screening
effects that appear in laboratory nuclear reactions at astrophysical energies.
The two-electron screening energy of the first model agrees very well with the
recent LUNA experimental result for the break-up reaction , which so far defies all available theoretical models.
Moreover, multi-electron effects that enhance laboratory reactions of the CNO
cycle and other advanced nuclear burning stages, are also studied by means of
the Thomas-Fermi model, deriving analytical formulae that establish a lower and
upper limit for the associated screening energy. The results of the second
model, which show a very satisfactory compatibility with the adiabatic
approximation ones, are expected to be particularly useful in future
experiments for a more accurate determination of the CNO astrophysical factors.Comment: 14 RevTex pages + 2 ps (revised) figures. Phys.Rev.C (in production
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