40 research outputs found
Urgent Considerations for the Neuro-oncologic Treatment of Patients with Gliomas During the COVID-19 Pandemic.
The COVID-19 outbreak is posing unprecedented risks and challenges for all communities and healthcare systems, worldwide. There are unique considerations for many adult patients with gliomas who are vulnerable to the novel coronavirus due to older age and immunosuppression. As patients with terminal illnesses, they present ethical challenges for centers that may need to ration access to ventilator care due to insufficient critical care capacity. It is urgent for the neuro-oncology community to develop a pro-active and coordinated approach to the care of adults with gliomas in order to provide them with the best possible oncologic care while also reducing their risk of viral infection during times of potential healthcare system failure. In this article, we present an approach developed by an international multi-disciplinary group to optimize the care of adults with gliomas during this pandemic. We recommend measures to promote strict social distancing and minimize exposures for patients, address risk and benefit of all therapeutic interventions, pro-actively develop end of life plans, educate patients and caregivers and ensure the health of the multi-disciplinary neuro-oncology workforce. This pandemic is already changing neuro-oncologic care delivery around the globe. It is important to highlight opportunities to maximize the benefit and minimize the risk of glioma management during this pandemic and potentially, in the future
Exact solutions of the radial Schrodinger equation for some physical potentials
By using an ansatz for the eigenfunction, we have obtained the exact
analytical solutions of the radial Schrodinger equation for the pseudoharmonic
and Kratzer potentials in two dimensions. The energy levels of all the bound
states are easily calculated from this eigenfunction ansatz. The normalized
wavefunctions are also obtained.Comment: 13 page
Approximate k-state solutions to the Dirac-Yukawa problem based on the spin and pseudospin symmetry
Using an approximation scheme to deal with the centrifugal
(pseudo-centrifugal) term, we solve the Dirac equation with the screened
Coulomb (Yukawa) potential for any arbitrary spin-orbit quantum number
{\kappa}. Based on the spin and pseudospin symmetry, analytic bound state
energy spectrum formulas and their corresponding upper- and lower-spinor
components of two Dirac particles are obtained using a shortcut of the
Nikiforov-Uvarov method. We find a wide range of permissible values for the
spin symmetry constant C_{s} from the valence energy spectrum of particle and
also for pseudospin symmetry constant C_{ps} from the hole energy spectrum of
antiparticle. Further, we show that the present potential interaction becomes
less (more) attractive for a long (short) range screening parameter {\alpha}.
To remove the degeneracies in energy levels we consider the spin and pseudospin
solution of Dirac equation for Yukawa potential plus a centrifugal-like term. A
few special cases such as the exact spin (pseudospin) symmetry Dirac-Yukawa,
the Yukawa plus centrifugal-like potentials, the limit when {\alpha} becomes
zero (Coulomb potential field) and the non-relativistic limit of our solution
are studied. The nonrelativistic solutions are compared with those obtained by
other methods.Comment: 21 pages, 6 figure
Symmetries of a class of nonlinear fourth order partial differential equations
In this paper we study symmetry reductions of a class of nonlinear fourth
order partial differential equations \be u_{tt} = \left(\kappa u + \gamma
u^2\right)_{xx} + u u_{xxxx} +\mu u_{xxtt}+\alpha u_x u_{xxx} + \beta u_{xx}^2,
\ee where , , , and are constants. This
equation may be thought of as a fourth order analogue of a generalization of
the Camassa-Holm equation, about which there has been considerable recent
interest. Further equation (1) is a ``Boussinesq-type'' equation which arises
as a model of vibrations of an anharmonic mass-spring chain and admits both
``compacton'' and conventional solitons. A catalogue of symmetry reductions for
equation (1) is obtained using the classical Lie method and the nonclassical
method due to Bluman and Cole. In particular we obtain several reductions using
the nonclassical method which are no} obtainable through the classical method
The iron lines as a tool for magnetic field estimations in non-flat accretion flows
Observations of AGNs and microquasars by ASCA, RXTE, Chandra and XMM-Newton
indicate the existence of broad X-ray emission lines of ionized heavy elements
in their spectra. Such spectral lines were discovered also in X-ray spectra of
neutron stars and X-ray afterglows of GRBs. Recently, Zakharov et al. (MNRAS,
2003, 342, 1325) described a procedure to estimate an upper limit of the
magnetic fields in regions from which X-ray photons are emitted. The authors
simulated typical profiles of the iron line in the presence of
magnetic field and compared them with observational data in the framework of
the widely accepted accretion disk model. Here we further consider typical
Zeeman splitting in the framework of a model of non-flat accretion flows, which
is a generalization of previous consideration into non-equatorial plane motion
of particles emitting X-ray photons.
Using perspective facilities of space borne instruments (e.g. Constellation-X
mission) a better resolution of the blue peak structure of iron line
will allow to evaluate the magnetic fields with higher accuracy.Comment: 22 pages, 6 figure
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Static and dynamic dipole polarizability of the helium atom using wave functions involving logarithmic terms
Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline.
To provide guidance to clinicians regarding therapy for diffuse astrocytic and oligodendroglial tumors in adults.
ASCO and the Society for Neuro-Oncology convened an Expert Panel and conducted a systematic review of the literature.
Fifty-nine randomized trials focusing on therapeutic management were identified.
Adults with newly diagnosed oligodendroglioma, isocitrate dehydrogenase (IDH)-mutant, 1p19q codeleted CNS WHO grade 2 and 3 should be offered radiation therapy (RT) and procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ) is a reasonable alternative for patients who may not tolerate PCV, but no high-level evidence supports upfront TMZ in this setting. People with newly diagnosed astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 2 should be offered RT with adjuvant chemotherapy (TMZ or PCV). People with astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 should be offered RT and adjuvant TMZ. People with astrocytoma, IDH-mutant, CNS WHO grade 4 may follow recommendations for either astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 or glioblastoma, IDH-wildtype, CNS WHO grade 4. Concurrent TMZ and RT should be offered to patients with newly diagnosed glioblastoma, IDH-wildtype, CNS WHO grade 4 followed by 6 months of adjuvant TMZ. Alternating electric field therapy, approved by the US Food and Drug Administration, should be considered for these patients. Bevacizumab is not recommended. In situations in which the benefits of 6-week RT plus TMZ may not outweigh the harms, hypofractionated RT plus TMZ is reasonable. In patients age ≥ 60 to ≥ 70 years, with poor performance status or for whom toxicity or prognosis are concerns, best supportive care alone, RT alone (for MGMT promoter unmethylated tumors), or TMZ alone (for MGMT promoter methylated tumors) are reasonable treatment options. Additional information is available at www.asco.org/neurooncology-guidelines