63 research outputs found
Nonsingular solutions of Hitchin's equations for noncompact gauge groups
We consider a general ansatz for solving the 2-dimensional Hitchin's
equations, which arise as dimensional reduction of the 4-dimensional self-dual
Yang-Mills equations, with remarkable integrability properties. We focus on the
case when the gauge group G is given by a real form of SL(2,C). For G=SO(2,1),
the resulting field equations are shown to reduce to either the Liouville,
elliptic sinh-Gordon or elliptic sine-Gordon equations. As opposed to the
compact case, given by G=SU(2), the field equations associated with the
noncompact group SO(2,1) are shown to have smooth real solutions with
nonsingular action densities, which are furthermore localized in some sense. We
conclude by discussing some particular solutions, defined on R^2, S^2 and T^2,
that come out of this ansatz.Comment: 12 pages, 3 figures. To appear in Nonlinearit
Torsion and the Gravitational Interaction
By using a nonholonomous-frame formulation of the general covariance
principle, seen as an active version of the strong equivalence principle, an
analysis of the gravitational coupling prescription in the presence of
curvature and torsion is made. The coupling prescription implied by this
principle is found to be always equivalent with that of general relativity, a
result that reinforces the completeness of this theory, as well as the
teleparallel point of view according to which torsion does not represent
additional degrees of freedom for gravity, but simply an alternative way of
representing the gravitational field.Comment: Version 2: minor presentation changes, a reference added, 11 pages
(IOP style
The Mass Spectrum of Neutrinos
In a previous paper we showed that Weyl equation possess superluminal
solutions and moreover we showed that those solutions that are eigenstates of
the parity operator seem to describe a coupled pair of a monopole anti-monopole
system. This result suggests to look for a solution of Maxwell equation
\partialF^{\infty}=-gJ with a current J as source and such that the Lorentz
force on the current is null. We first identify a solution where
J={\gamma}^{5}J_{m}is a spacelike field (even if F is not a superluminal
solution of the homogeneous Maxwell equation). More surprisingly we find that
there exists a solution F of the free Maxwell \partialF=0 that is equivalent to
the non homogeneous equation for F^{\infty}. Once this result is proved it
suggests by itself to look for more general subluminal and superluminal
solutions F of the free Maxwell equation equivalent to a non homogeneous
Maxwell equation for a field F_{0} with a current term as source which may be
subluminal or superluminal. We exhibit one such subluminal solution, for which
the Dirac-Hestenes spinor field {\psi} associated the electromagnetic field
F_{0} satisfies a Dirac equation for a bradyonic neutrino under the ansatz that
the current is ce^{{\lambda}{\gamma}^{5}}g{\psi}{\gamma}^{0}{\psi}, with g the
quantum of magnetic charge and {\lambda} a constant to be determined in such a
way that the auto-force be null. Together with Dirac's quantization condition
this gives a quantized mass spectrum (Eq.49) for the neutrinos, with the masses
of the different flavor neutrinos being of the same order of magnitude (Eq.50)
which is in accord with recent experimental findings. As a last surprise we
show that the mass spectrum found in the previous case continues to hold if the
current is taken spacelike, i.e.,
ce^{{\lambda}{\gamma}^{5}}g{\psi}_{>}{\gamma}^{3}{\psi}_{>} with {\psi}_{>}, in
this case, satisfying a tachyonic Dirac-Hestenes equation.Comment: This version corrects some misprints, has a new remark and a new
referenc
A Comparison of the Conditioning Regimens BEAM and FEAM for Autologous Hematopoietic Stem Cell Transplantation in Lymphoma: An Observational Study on 1038 Patients From Fondazione Italiana Linfomi
Abstract Background Carmustine (BCNU)-Etoposide-Citarabine-Melphalan (BEAM) chemotherapy is the standard conditioning regimen for autologous stem cell transplantation (ASCT) in lymphomas. Owing to BCNU shortages, many centers switched to Fotemustine-substituted BEAM (FEAM), lacking proof of equivalence. Methods We conducted a retrospective cohort study in 18 Italian centers to compare safety and efficacy of BEAM and FEAM regimens for ASCT in lymphomas performed from 2008 to 2015. Results We enrolled 1038 patients (BEAM n=607, FEAM n=431), of which 27% had Hodgkin's lymphoma (HL), 14% indolent Non-Hodgkin's lymphoma (iNHL) and 59% aggressive NHL (aNHL). Baseline characteristics including age, sex, stage, B-symptoms, extranodal involvement, previous treatments, response before ASCT, overall conditioning intensity, were well balanced between BEAM and FEAM; notable exceptions were: ASCT year (median: BEAM=2011 vs FEAM=2013, p Conclusions BEAM and FEAM do not appear different in terms of survival and disease control. However, due to concerns of higher toxicity, Fotemustine substitution in BEAM does not seem justified, if not for easier supply
Effect of Nano-HA/Collagen Composite Hydrogels on Osteogenic Behavior of Mesenchymal Stromal Cells
Vemurafenib-induced radiation recall dermatitis: case report and review of the literature
The cutaneous effects of BRAF (serine/threonine protein kinase B-raf) inhibitors such as vemurafenib remain poorly defined. Rash, squamous cell carcinoma, keratoacanthoma and photosensitivity are the most common grade 2 or 3 adverse events observed in clinical trials. We here report the case of a patient with a BRAF V600E mutated metastatic melanoma who developed severe radiation recall dermatitis 6 weeks after completing radiotherapy. Vemurafenib treatment had been initiated 1 week before the development of dermatitis because of rapidly progressing disease. Upon topical treatment of the affected skin areas, clinical symptoms regressed over a period of 2 months, although vemurafenib was continuously administered. As our case goes in line with other reports, we believe that physicians should be aware of this additional cutaneous side effect of vemurafenib and that continuation of the treatment is safe when close clinical control and interdisciplinary management can be provided
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