8,633 research outputs found
Becoming Monica : Names, Naming, and Name Changing in Monica Sone’s Nisei Daughter
departmental bulletin pape
A simple derivation of the electromagnetic field of an arbitrarily moving charge
The expression for the electromagnetic field of a charge moving along an
arbitrary trajectory is obtained in a direct, elegant, and Lorentz invariant
manner without resorting to more complicated procedures such as differentiation
of the Lienard-Wiechert potentials. The derivation uses arguments based on
Lorentz invariance and a physically transparent expression originally due to
J.J.Thomson for the field of a charge that experiences an impulsive
acceleration.Comment: The following article has been accepted by the American Journal of
Physics. After it is published, it will be found at
http://scitation.aip.org/ajp; 12 pages, 1 figur
Electromagnetic Transition in Waveguide with Application to Lasers
The electromagnetic transition of two-level atomic systems in a waveguide is
calculated. Compared with the result in free space, the spontaneous emission
rate decrease because the phase space is smaller, and meanwhile, some resonance
appears in some cases. Moreover, the influence of non-uniform electromagnetic
field in a waveguide on absorption and stimulated emission is considered.
Applying the results to lasers, a method to enhance the laser power is
proposed.Comment: 4 pages, 2 figure
Importance of an Astrophysical Perspective for Textbook Relativity
The importance of a teaching a clear definition of the ``observer'' in
special relativity is highlighted using a simple astrophysical example from the
exciting current research area of ``Gamma-Ray Burst'' astrophysics. The example
shows that a source moving relativistically toward a single observer at rest
exhibits a time ``contraction'' rather than a ``dilation'' because the light
travel time between the source and observer decreases with time. Astrophysical
applications of special relativity complement idealized examples with real
applications and very effectively exemplify the role of a finite light travel
time.Comment: 5 pages TeX, European Journal of Physics, in pres
Researching Bradford: A review of social research on Bradford District
A synthesis of findings from social research on the District of Bradford. This report synthesises the findings from a wide range of social research undertaken on the District of Bradford, primarily between 1995 and 2005. The researchers reviewed almost 200 pieces of work. The key results are summarised under thematic headings: - The social, economic and institutional context - Community cohesion - Housing, neighbourhoods and regeneration - Business and enterprise - Health, disability and social care - Children and young people - Education, skills and the labour market - Crime and community safety It also identifies a future research agenda. The main purpose of the review was to provide the Joseph Rowntree Foundation and local organisations in Bradford with a firm basis upon which to build future work in the District
Schiff moment of the Mercury nucleus and the proton dipole moment
We calculated the contribution of internal nucleon electric dipole moments to
the Schiff moment of Hg. The contribution of the proton electric dipole
moment was obtained via core polarization effects that were treated in the
framework of random phase approximation with effective residual forces. We
derived a new upper bound cm of the proton
electric dipole moment.Comment: 4 pages, 2 figures, RevTex
Evolution of massive protostars: the IRAS 18151-1208 region
The study of physical and chemical properties of massive protostars is
critical to better understand the evolutionary sequence which leads to the
formation of high-mass stars. IRAS 18151-1208 is a nearby massive region (d =
3kpc, L ~ 20000 Lsun) which splits into three cores: MM1, MM2 and MM3
(separated by 1'-2'). We aim at (1) studying the physical and chemical
properties of the individual MM1, MM2 and MM3 cores; (2) deriving their
evolutionary stages; (3) using these results to improve our view of the
evolutionary sequence of massive cores. The region was observed in the CS,
C34S, H2CO, HCO+, H13CO+, and N2H+ lines at mm wavelengths with the IRAM 30m
and Mopra telescopes. We use 1D and 2D modeling of the dust continuum to derive
the density and temperature distributions, which are then used in the RATRAN
code to model the lines and constrain the abundances of the observed species.
All the lines were detected in MM1 and MM2. MM3 shows weaker emission, or even
is undetected in HCO+ and all isotopic species. MM2 is driving a newly
discovered CO outflow and hosts a mid-IR-quiet massive protostar. The abundance
of CS is significantly larger in MM1 than in MM2, but smaller than in a
reference massive protostar such as AFGL2591. In contrast the N2H+ abundance
decreases from MM2 to MM1, and is larger than in AFGL2591. Both MM1 and MM2
host an early phase massive protostar, but MM2 (and mid-IR-quiet sources in
general) is younger and more dominated by the host protostar than MM1
(mid-IR-bright). The MM3 core is probably in a pre-stellar phase. We find that
the N2H+/C34S ratio varies systematically with age in the massive protostars
for which the data are available. It can be used to identify young massive
protostars.Comment: 19 pages, 17 figures, accepted by A&A the 3 June 200
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