23,879 research outputs found
Phase 1 of the automated array assembly task of the low cost silicon solar array project
The results of a study of process variables and solar cell variables are presented. Interactions between variables and their effects upon control ranges of the variables are identified. The results of a cost analysis for manufacturing solar cells are discussed. The cost analysis includes a sensitivity analysis of a number of cost factors
Two-Dimensional Bosonization from Variable Shifts in the Path Integral
A method to perform bosonization of a fermionic theory in (1+1) dimensions in
a path integral framework is developed. The method relies exclusively on the
path integral property of allowing variable shifts, and does not depend on the
explicit form of Greens functions. Two examples, the Schwinger model and the
massless Thirring model, are worked out.Comment: 4 page
Observing IMBH-IMBH Binary Coalescences via Gravitational Radiation
Recent numerical simulations have suggested the possibility of forming double
intermediate mass black holes (IMBHs) via the collisional runaway scenario in
young dense star clusters. The two IMBHs formed would exchange into a common
binary shortly after their birth, and quickly inspiral and merge. Since
space-borne gravitational wave (GW) observatories such as LISA will be able to
see the late phases of their inspiral out to several Gpc, and LIGO will be able
to see the merger and ringdown out to similar distances, they represent
potentially significant GW sources. In this Letter we estimate the rate at
which LISA and LIGO will see their inspiral and merger in young star clusters,
and discuss the information that can be extracted from the observations. We
find that LISA will likely see tens of IMBH--IMBH inspirals per year, while
advanced LIGO could see ~10 merger and ringdown events per year, with both
rates strongly dependent on the distribution of cluster masses and densities.Comment: Accepted for publication in ApJL. Minor changes to reflect accepted
version. 4 pages in emulateapj, 3 figure
Classical solution of the wave equation
The classical limit of wave quantum mechanics is analyzed. It is shown that
the general requirements of continuity and finiteness to the solution
, where and
is the reduced classical action of the physical system, result in the
asymptote of the exact solution and general quantization condition for ,
which yields the exact eigenvalues of the system.Comment: 8 Pages, 10 Refs, LaTe
Quantum Fermion Hair
It is shown that the Dirac operator in the background of a magnetic
%Reissner-Nordstr\"om black hole and a Euclidean vortex possesses normalizable
zero modes in theories containing superconducting cosmic strings. One
consequence of these zero modes is the presence of a fermion condensate around
magnetically charged black holes which violates global quantum numbers.Comment: 16pp (harvmac (l)) and 2 figs.(not included
Gender and educational leadership in England: a comparison of secondary headteachers' views over time
In the context of gender being a barrier to accessing leadership, this paper presents a comparison of the views of men and women head teacher (principals) of secondary schools in England in the 1990s and in 2004. The same survey instrument was used on both occasions. The perceptions of the head teachers show change in some areas and no change in others. Overall, women are more likely to become head teachers and are now less likely to be categorised into pastoral roles, but in some cases women still meet prejudice from governors and others in the wider community. Women head teachers are more likely to have partners and children than in the 1990s, sharing equally or carrying most of the domestic responsibilities, whereas male colleagues are most likely to have partners who take the majority of responsibility in the home. Essentialist stereotypes about women and men as leaders still prevail, although both the women and men head teachers see themselves as adopting a traditionally âfeminineâ style of leadership. Women head teachers are likely to see some benefits in being a woman in a role stereotypically associated with men. However, there has been an increase in the proportion of women who feel that they have to prove their worth as a leader, and this may be linked with increased levels of accountability in schools
Minimal Potentials with Very Many Minima
We demonstrate, by construction, that simple renormalizable matrix potentials
with S_N, as opposed to O(N), symmetry can exhibit an exponentially large
number of inequivalent deep local minima.Comment: LaTeX, 9 pages, 2 figures. Additional applications and references
adde
Microlensing of Extended Stellar Sources
We investigate the feasibility of reconstructing the radial intensity profile
of extended stellar sources by inverting their microlensed light curves. Using
a simple, linear, limb darkening law as an illustration, we show that the
intensity profile can be accurately determined, at least over the outer part of
the stellar disc, with realistic light curve sampling and photometric errors.
The principal requirement is that the impact parameter of the lens be less than
or equal to the stellar radius. Thus, the analysis of microlensing events
provides a powerful method for testing stellar atmosphere models.Comment: 4 pages LaTeX, to appear in New Astronomy Reviews - proceedings of
the Oxford Workshop `Gravitational Lensing: Nature's Own Weighing Scales'.
Uses elsart.cls. Paper also available at
ftp://info.astro.gla.ac.uk/pub/martin/extended.p
- âŠ