506 research outputs found
Resonance-continuum interference in the di-photon Higgs signal at the LHC
A low mass Standard Model Higgs boson should be visible at the Large Hadron
Collider through its production via gluon-gluon fusion and its decay to two
photons. We compute the interference of this resonant process, gg -> H -> gamma
gamma, with the continuum QCD background, gg -> gamma gamma induced by quark
loops. Helicity selection rules suppress the effect, which is dominantly due to
the imaginary part of the two-loop gg -> gamma gamma scattering amplitude. The
interference is destructive, but only of order 5% in the Standard Model, which
is still below the 10-20% present accuracy of the total cross section
prediction. We comment on the potential size of such effects in other Higgs
models.Comment: 10 pages, 2 figure
The parentage of 'Sangiovese', the most important Italian wine grape
A previous microsatellite study pointed out a possible parent-offspring relationship between 'Sangiovese', the most widespread red grape cultivar in Italy, and 'Ciliegiolo', an ancient Tuscan variety. Testing 'Sangiovese' as a parent of 'Ciliegiolo', we searched for the putative other parent in our extensive, private and standardized database, but we did not find any candidate. Testing 'Ciliegiolo' as a parent of 'Sangiovese', we found four candidate cultivars. After the analysis of 50 microsatellites, only one stood the paternity test and we established with a strong statistical support that 'Sangiovese' is a progeny of 'Ciliegiolo' and 'Calabrese di Montenuovo', an obscure grapevine from Campania, Italy. This cultivar does not have a registered name and is supposed to have been introduced from Calabria. Among 180 additional local grape cultivars from Calabria, Campania or Tuscany, we did not find any matching variety. As a consequence, we propose to adopt the name 'Calabrese di Montenuovo' for this grape cultivar. In addition, we found relatives of 'Sangiovese' and 'Calabrese di Montenuovo' in Calabria, thus strongly suggesting a Calabrian origin for 'Calabrese di Montenuovo' and indicating that 'Sangiovese' has ancestors and/or progenies in Tuscany and in Southern Italy.
Broken symmetries and directed collective energy transport
We study the appearance of directed energy current in homogeneous spatially
extended systems coupled to a heat bath in the presence of an external ac field
E(t). The systems are described by nonlinear field equations. By making use of
a symmetry analysis we predict the right choice of E(t) and obtain directed
energy transport for systems with a nonzero topological charge Q. We
demonstrate that the symmetry properties of motion of topological solitons
(kinks and antikinks) are equivalent to the ones for the energy current.
Numerical simulations confirm the predictions of the symmetry analysis and,
moreover, show that the directed energy current drastically increases as the
dissipation parameter reduces. Our results generalize recent rigorous
theories of currents generated by broken time-space symmetries to the case of
interacting many-particle systems.Comment: 4 pages, 2 figure
Diffusion and Current of Brownian Particles in Tilted Piecewise Linear Potentials: Amplification and Coherence
Overdamped motion of Brownian particles in tilted piecewise linear periodic
potentials is considered. Explicit algebraic expressions for the diffusion
coefficient, current, and coherence level of Brownian transport are derived.
Their dependencies on temperature, tilting force, and the shape of the
potential are analyzed. The necessary and sufficient conditions for the
non-monotonic behavior of the diffusion coefficient as a function of
temperature are determined. The diffusion coefficient and coherence level are
found to be extremely sensitive to the asymmetry of the potential. It is
established that at the values of the external force, for which the enhancement
of diffusion is most rapid, the level of coherence has a wide plateau at low
temperatures with the value of the Peclet factor 2. An interpretation of the
amplification of diffusion in comparison with free thermal diffusion in terms
of probability distribution is proposed.Comment: To appear in PR
Primary spinal cord tumors of childhood: effects of clinical presentation, radiographic features, and pathology on survival
To determine the relationship between clinical presentation, radiographic features, pathology, and treatment on overall survival of newly diagnosed pediatric primary spinal cord tumors (PSCT). Retrospective analysis of all previously healthy children with newly diagnosed PSCT at a single institution from 1995 to present was performed. Twenty-five pediatric patients (15 boys, average 7.9 years) were diagnosed with PSCT. Presenting symptoms ranged from 0.25 to 60 months (average 7.8 months). Symptom duration was significantly shorter for high grade tumors (average 1.65 months) than low grade tumors (average 11.2 months) (P = 0.05). MRI revealed tumor (8 cervical, 17 thoracic, 7 lumbar, 7 sacral) volumes of 98–94,080 mm3 (average 19,474 mm3). Homogeneous gadolinium enhancement on MRI correlated with lower grade pathology (P = 0.003). There was no correlation between tumor grade and volume (P = 0.63) or edema (P = 0.36) by MRI analysis. Median survival was 53 months and was dependent on tumor grade (P = 0.05) and gross total resection (P = 0.01) but not on gender (P = 0.49), age of presentation (P = 0.82), duration of presenting symptoms (P = 0.33), or adjuvant therapies (P = 0.17). Stratified Kaplan–Meier analysis confirmed the association between degree of resection and survival after controlling for tumor grade (P = 0.01). MRI homogeneous gadolinium enhancement patterns may be helpful in distinguishing low grade from high grade spinal cord malignancies. While tumor grade and gross total resection rather than duration of symptoms correlated with survival in our series, greater than one-third of patients had reported symptoms greater than 6 months duration prior to diagnosis
Multiple brain developmental venous anomalies as a marker for constitutional mismatch repair deficiency syndrome
The occurrence of multiple developmental venous anomalies in this study of 10 patients with constitutional mismatch repair deficiency syndrome (CMMRD) suggests that developmental venous anomalies may be a characteristic of this syndrome that has not been previously described. A retrospective descriptive analysis of brain MR imaging studies from 3 families with CMMRD was performed. Analysis included the number of developmental venous anomalies, location, draining vessels, and associated vascular anomalies (for instance, cavernomas) with clinical correlation of symptoms and tumors. CMMRD is a cancer-predisposition syndrome with very high penetrance and most reported individuals are affected during childhoodInternational Biallelic Mismatch Repair Deficiency ConsortiumMeagan’s Walk, the CIHR Joint Canada- Israel Health Research Program, and an American Association for Cancer Research Stand Up 2 Cancer Catalyst TM Research Gran
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