25,422 research outputs found
The effect of different solar simulators on the measurement of short-circuit current temperature coefficients
Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells
The Objective in War
In considering this subject, we must be clear about the distinction between the political objective and military objective. The two are different but not separate. For nations do not wage war for war\u27s sake, but in pursuance of policy. The military objective is only the means to a political end
The multiple junction edge illuminated solar cell
The multiple junction edge illuminated solar cell was devised for high voltage low current applications. Devices to be flight tested in early 1974 with 96 series connected PNN+ junctions in a 2 cm X 2.3 cm size deliver 36 volts at 1 milliampere. Test data of M-J cells fabricated with resistivities of 10, 50, 100, 200, 450, and 1000 ohm cm silicon are presented and problem areas are discussed. An additional potential application of the M-J cell lies in ultilization of its high intensity performance that has been demonstrated at levels in excess of 100 AMO suns
Magneto-x-ray effects in transition-metal alloys
We present a theory that combines the relativistic spin-polarized version of the Koringa-Kohn-Rostoker coherent-potential approximation theory and the macroscopic theory of magneto-optical effects enabling us to calculate magneto-x-ray effects from first principles. The theory is illustrated by calculation of Faraday and Kerr rotations and ellipticities for transition-metal alloys
Enhanced winnings in a mixed-ability population playing a minority game
We study a mixed population of adaptive agents with small and large memories,
competing in a minority game. If the agents are sufficiently adaptive, we find
that the average winnings per agent can exceed that obtainable in the
corresponding pure populations. In contrast to the pure population, the average
success rate of the large-memory agents can be greater than 50 percent. The
present results are not reproduced if the agents are fed a random history,
thereby demonstrating the importance of memory in this system.Comment: 9 pages Latex + 2 figure
The monopole mass in the three-dimensional Georgi-Glashow model
We study the three-dimensional Georgi-Glashow model to demonstrate how
magnetic monopoles can be studied fully non-perturbatively in lattice Monte
Carlo simulations, without any assumptions about the smoothness of the field
configurations. We examine the apparent contradiction between the conjectured
analytic connection of the `broken' and `symmetric' phases, and the
interpretation of the mass (i.e., the free energy) of the fully quantised 't
Hooft-Polyakov monopole as an order parameter to distinguish the phases. We use
Monte Carlo simulations to measure the monopole free energy and its first
derivative with respect to the scalar mass. On small volumes we compare this to
semi-classical predictions for the monopole. On large volumes we show that the
free energy is screened to zero, signalling the formation of a confining
monopole condensate. This screening does not allow the monopole mass to be
interpreted as an order parameter, resolving the paradox.Comment: 12 pages, 7 figures, uses revtex. Minor changes made to the text to
match with the published version at
http://link.aps.org/abstract/PRD/v65/e12500
The influence of paediatric HIV infection on circulating B cell subsets and CXCR5+ T helper cells
Antiretroviral therapy (ART) only partially restores HIV-induced alterations in lymphocyte populations. We assessed B and T cell phenotypes in a cohort of children from a single centre in the United Kingdom with perinatally acquired HIV compared to healthy controls. The majority of HIV infected children (44 of 56) were on fully suppressive combination ART. Children with perinatally acquired HIV had significantly lower memory B and CD4(+) CD45RO(+) CXCR5(+) [follicular T helper cell (Tfh)-like] T cell percentages. Detectable viraemia was associated with higher CD21(-) (activated and exhausted/tissue-like memory) B cells. A greater proportion of life spent on suppressive ART was associated with higher memory B cell percentages. These results suggest that early and sustained suppressive ART may preserve B and T cell phenotypes in perinatally acquired HIV and limit deficits in humoral immunity. A lower proportion of circulating Tfh-like cells in HIV infected children appears to be independent of HIV treatment history and ongoing HIV viraemia and warrants further investigation
Light scalars in strongly-coupled extra-dimensional theories
The low-energy dynamics of five-dimensional Yang-Mills theories compactified
on S^1 can be described by a four-dimensional gauge theory coupled to a scalar
field in the adjoint representation of the gauge group. Perturbative
calculations suggest that the mass of this elementary scalar field is protected
against power divergences, and is controlled by the size of the extra dimension
R. As a first step in the study of this phenomenon beyond perturbation theory,
we investigate the phase diagram of a SU(2) Yang-Mills theory in five
dimensions regularized on anisotropic lattices and we determine the ratios of
the relevant physical scales. The lattice system shows a dimensionally reduced
phase where the four-dimensional correlation length is much larger than the
size of the extra dimension, but still smaller than the four-dimensional
volume. In this region of the bare parameter space, at energies below 1/R, the
non-perturbative spectrum contains a \emph{light} scalar state. This state has
a mass that is independent of the cut-off, and a small overlap with glueball
operators. Our results suggest that light scalar fields can be introduced in a
lattice theory using compactified extra dimensions, rather than fine tuning the
bare mass parameter.Comment: 38 pages (7 pages of Appendix), 10 tables, 21 figures. Minor
corrections. Version accepted for publication in JHE
Theory of Networked Minority Games based on Strategy Pattern Dynamics
We formulate a theory of agent-based models in which agents compete to be in
a winning group. The agents may be part of a network or not, and the winning
group may be a minority group or not. The novel feature of the present
formalism is its focus on the dynamical pattern of strategy rankings, and its
careful treatment of the strategy ties which arise during the system's temporal
evolution. We apply it to the Minority Game (MG) with connected populations.
Expressions for the mean success rate among the agents and for the mean success
rate for agents with neighbors are derived. We also use the theory to
estimate the value of connectivity above which the Binary-Agent-Resource
system with high resource level goes into the high-connectivity state.Comment: 24 pages, 3 figures, submitted to PR
- …