11,968 research outputs found
Star Formation Rate from Dust Infrared Emission
We examine what types of galaxies the conversion formula from dust infrared
(IR) luminosity into the star formation rate (SFR) derived by
Kennicutt (1998) is applicable to. The ratio of the observed IR luminosity,
, to the intrinsic bolometric luminosity of the newly (\la 10
Myr) formed stars,
, of a galaxy can be determined by a mean dust opacity in the
interstellar medium and the activity of the current star formation. We find
that these parameters area being is very large, and many nearby normal and active star-forming
galaxies really fall in this area. It results from offsetting two effects of a
small dust opacity and a large cirrus contribution of normal galaxies relative
to starburst galaxies on the conversion of the stellar emission into the dust
IR emission. In conclusion, the SFR determined from the IR luminosity under the
assumption of like Kennicutt (1998) is reliable within
a factor of 2 for all galaxies except for dust rich but quiescent galaxies and
extremely dust poor galaxies.Comment: Accepted by ApJL: 6 pages (emulateapj5), 2 figures (one is an extra
figure not appeared in ApJL
Perturbation theory for localized solutions of sine-Gordon equation: decay of a breather and pinning by microresistor
We develop a perturbation theory that describes bound states of solitons
localized in a confined area. External forces and influence of inhomogeneities
are taken into account as perturbations to exact solutions of the sine-Gordon
equation. We have investigated two special cases of fluxon trapped by a
microresistor and decay of a breather under dissipation. Also, we have carried
out numerical simulations with dissipative sine-Gordon equation and made
comparison with the McLaughlin-Scott theory. Significant distinction between
the McLaughlin-Scott calculation for a breather decay and our numerical result
indicates that the history dependence of the breather evolution can not be
neglected even for small damping parameter
Magnetic moments of S-shell pentaquarks in the constituent quark model
We discuss the magnetic moments of the recently discovered exotic baryons
Theta(+) and Xi(--) and their multiplet partners in the framework of a naive
additive quark model. These baryons are set up as pentaquark states where four
quarks and a single antiquark are located in their ground state orbit. The
pentaquark states are classified as members of the flavor SU(3) octet and
antidecuplet with spin-parity J^P = (1/2)^- and (3/2)^-, where we determine the
magnetic moments of these pentaquark states.Comment: 13 pages, 2 figures, elsart; publication version, 8 pages, 1 figure,
ptptex; upload miss correcte
Constraints to achieving the MDGs through domestic resource mobilization
The present paper focuses on the role of domestic resource mobilization for financing poverty reduction strategies. Policy makers should be aware of important macroeconomic trade-offs associated with MDG strategies financed from tax increases or domestic borrowing. The trade-offs are largely intertemporal: can poor and middle-income countries absorb the initial financing costs in order to achieve expected gains in productivity and human development over time? This calls for a dynamic economy-wide framework to identify the importance of such trade-offs. The paper presents such a framework and illustrates its usefulness in applications for Costa Rica and Ecuador.computable general equilibrium models; distribution; welfare and poverty; foreign aid; macroeconomic analyses of economic development.
One-way electromagnetic Tamm states in magnetophotonic structures
We study surface Tamm states in magnetophotonic structures magnetized in the Cotton–Mouton (Voigt) geometry. We demonstrate that the periodicity violation due to the structure truncation together with the violation of the time reversal symmetry due to the presence of magneto-optical materials gives rise to nonreciprocality of the surface modes. Dispersion of forward and backward modes splits and becomes magnetization dependent. This results in the magnetization-induced transitions between bulk and surface modes and unidirectional propagation of surface waves.We thank the Australian Research Council for a financial
support and S. Fan for useful discussions. This work was
supported in part by the Super Optical Information Memory
Project from the Ministry of Education, Culture, Sports, Science
and Technology of Japan MEXT, and Grant-in-Aid
for Scientific Research S Grant No. 17106004 from Japan
Society for the Promotion of Science JSPS
Non-equilibrium spin accumulation in ferromagnetic single-electron transistors
We study transport in ferromagnetic single-electron transistors. The non-
equilibrium spin accumulation on the island caused by a finite current through
the system is described by a generalized theory of the Coulomb blockade. It
enhances the tunnel magnetoresistance and has a drastic effect on the time-
dependent transport properties. A transient decay of the spin accumulation may
reverse the electric current on time scales of the order of the spin-flip
relaxation time. This can be used as an experimental signature of the non-
equilibrium spin accumulation.Comment: 9 postscript figures, to appear in The European Physical Journal
Comparison of theory with experiment for positron production from high-energy electrons moving along crystal axes
Various positron distributions are obtained using an approach developed
earlier for the description of electron-photon showers in axially aligned
single crystals. Based on these distributions, characteristics of the positron
yield measured in recent experiments are calculated. Theoretical estimations
display a rather good agreement with experimental results obtained using 3 to
10 GeV electrons aligned to the - axis of the tungsten crystals.Comment: 10 pages, 6 Postscript figure
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