327 research outputs found
Inner products of resonance solutions in 1-D quantum barriers
The properties of a prescription for the inner products of the resonance
(Gamow states), scattering (Dirac kets), and bound states for 1-dimensional
quantum barriers are worked out. The divergent asypmtotic behaviour of the
Gamow states is regularized using a Gaussian convergence factor first
introduced by Zel'dovich. With this prescription, most of these states (with
discrete complex energies) are found to be orthogonal to each other, to the
bound states, and to the Dirac kets, except when they are neighbors, in which
case the inner product is divergent. Therefore, as it happens for the continuum
scattering states, the norm of the resonant ones remains non-calculable. Thus,
they exhibit properties half way between the (continuum real) Dirac-delta
orthogonality and the (discrete real) Kronecker-delta orthogonality of the
bound states.Comment: 13 pages, 2 figure
Advances in cyclin-dependent kinase inhibitors for the treatment of melanoma
Despite the recent advances in the treatment of malignant melanoma with immunotherapy and BRAF/MEK targeted agents, advanced disease still beholds a poor prognosis for a significant proportion of patients. Cyclin dependent kinase (CDK) inhibitors have been investigated as novel melanoma therapeutics throughout a range of phase 1 and 2 trials, as single agents and in combination with established treatments. Areas covered: This article summarises the rationale for, and development of CDK inhibitors in melanoma, with their evolution from pan-CDK inhibitors to highly specific agents, throughout clinical trials and finally their potential future use. Expert opinion: Whilst CDK inhibitors have been practice changing in breast cancer management, their efficacy is yet to be proven in melanoma. Combination with BRAF/MEK inhibitors has been hindered by dose limiting toxicities, but their role may yet to be found within the spectrum of biomarker derived personalised melanoma management. The effect that CDK inhibitors can have as an adjunct to immunotherapy also remains to be seen
Gauge Fixing in Higher Derivative Gravity
Linearized four-derivative gravity with a general gauge fixing term is
considered. By a Legendre transform and a suitable diagonalization procedure it
is cast into a second-order equivalent form where the nature of the physical
degrees of freedom, the gauge ghosts, the Weyl ghosts, and the intriguing
"third ghosts", characteristic to higher-derivative theories, is made explicit.
The symmetries of the theory and the structure of the compensating
Faddeev-Popov ghost sector exhibit non-trivial peculiarities.Comment: 21 pages, LaTe
Gauge fixing in higher derivative field theories
Higher Derivative (HD) Field Theories can be transformed into second order
equivalent theories with a direct particle interpretation. In a simple model
involving abelian gauge symmetries we examine the fate of the possible gauge
fixings throughout this process. This example is a useful test bed for HD
theories of gravity and provides a nice intuitive interpretation of the "third
ghost" occurring there and in HD gauge theories when a HD gauge fixing is
adopted.Comment: 16 pages, Latex,( Preprint imaff 93/10
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