228,412 research outputs found
On non hadronic origin of high energy neutrinos
Some of the non hadronic interactions, such as the \eta resonance formation
in the \gamma \gamma interactions and the muon pair production in the e\gamma
interactions, are identified as possible source interactions for generating
high energy neutrinos in the cosmos.Comment: 9 pages, 1 figure, talk given at First NCTS Workshop on Astroparticle
Physics, 6-9 December, 2001, Kenting, Taiwan (to appear in its proceedings
edited by H. Athar, Guey-Lin Lin, and K.-W. Ng
Radio Planetary Nebulae in the Small Magellanic Cloud
We present ten new radio continuum (RC) detections at catalogued planetary
nebula (PN) positions in the Small Magellanic Cloud (SMC): SMPS6, LIN 41, LIN
142, SMP S13, SMP S14, SMP S16, J18, SMP S18, SMP S19 and SMP S22.
Additionally, six SMC radio PNe previously detected, LIN 45, SMP S11, SMPS17,
LIN321, LIN339 and SMPS24 are also investigated (re-observed) here making up a
population of 16 radio detections of catalogued PNe in the SMC. These 16 radio
detections represent ~15 % of the total catalogued PN population in the SMC. We
show that six of these objects have characteristics that suggest that they are
PN mimics: LIN 41, LIN 45, SMP S11, LIN 142, LIN 321 and LIN 339. We also
present our results for the surface brightness - PN radius relation
({\Sigma}-D) of the SMC radio PN population. These are consistent with previous
SMC and LMC PN measurements of the ({\Sigma}-D) relation.Comment: Accepted for publication in Astrophysics and Space Scienc
SCDM-k: Localized orbitals for solids via selected columns of the density matrix
The recently developed selected columns of the density matrix (SCDM) method
[J. Chem. Theory Comput. 11, 1463, 2015] is a simple, robust, efficient and
highly parallelizable method for constructing localized orbitals from a set of
delocalized Kohn-Sham orbitals for insulators and semiconductors with
point sampling of the Brillouin zone. In this work we generalize the SCDM
method to Kohn-Sham density functional theory calculations with k-point
sampling of the Brillouin zone, which is needed for more general electronic
structure calculations for solids. We demonstrate that our new method, called
SCDM-k, is by construction gauge independent and is a natural way to describe
localized orbitals. SCDM-k computes localized orbitals without the use of an
optimization procedure, and thus does not suffer from the possibility of being
trapped in a local minimum. Furthermore, the computational complexity of using
SCDM-k to construct orthogonal and localized orbitals scales as O(N log N )
where N is the total number of k-points in the Brillouin zone. SCDM-k is
therefore efficient even when a large number of k-points are used for Brillouin
zone sampling. We demonstrate the numerical performance of SCDM-k using systems
with model potentials in two and three dimensions.Comment: 25 pages, 7 figures; added more background sections, clarified
presentation of the algorithm, revised the presentation of previous work,
added a more high level overview of the new algorithm, and mildly clarified
the presentation of the results (there were no changes to the numerical
results themselves
Resonance scattering at lyman-alpha by an atomic hydrogen cell
Hydrogen cell and ion chamber for obtaining photoelectric data on resonance scattering at lyman alpha lin
Scenario of inflationary cosmology from the phenomenological models
Choosing the three phenomenological models of the dynamical cosmological term
, viz., , and
where is the cosmic scale factor, it has been shown by
the method of numerical analysis that the three models are equivalent for the
flat Universe . The evolution plots for dynamical cosmological term
vs. time and also the cosmic scale factor vs. are drawn
here for . A qualitative analysis has been made from the plots which
supports the idea of inflation and hence expanding Universe.Comment: 12 latex pages with 12 figures; Replaced with the revised version;
Accepeted for `J. Non-lin. Frac. Phen. Sci. Engg.
- …