12,346 research outputs found
The work of the Salford school board.
Salford was unique in 1870 in being a large town, of some 120,000 inhabitants, with an excess of public elementary school accommodation. In November 1870 Salford elected the sixth board in the country. The Board retained for the whole of its existence the voluntaryist majority with which it was first returned. Almost immediately the Board took over the payment of school-pence of poor but non-pauper children and with Manchester, up to 1st January 1877, paid more in fees than all the other boards together. Indeed, it was ever the policy of the Board to aid the Salford voluntary schools in any way possible, such as by fees assistance, and from this attitude and the initial excess of voluntary school places, it developed a reluctance to provide new board schools. From 1880 onwards this policy resulted in acute shortages of accommodation in various parts of Salford. The inspectorate constantly exhorted the Board to supply new school places. The Board did not even manage a school until 1877.The Board resolved to make attendance compulsory as soon as practicable, and this was enforced from 1872. However, the standards of exemption were low and the Board not particularly zealous in securing attendance. With the passing of the 1880 Elementary Education Act, it unavailingly sought to retain ease of exemption, but thereafter it remained slightly in front of the country generally in its regard for the children's welfare. It was never easy to induce children to stay on at school - even to-day Salford has the lowest proportion of sixth-formers in the country - and with the passing of the I889 Technical Instruction Act (largely engineered by the most famous member of the Salford Board, William Mather, who had been a member of the Samuelson Commission) a period of friction between the School Board and the Council's Technical Instruction Committee ensued. A large new technical college was built, and despite agreement, the college attempted to attract children from the upper standards of the Board's higher grade schools. Later, there were rival claims for the recognition as the local authority responsible for Science and Art Instruction, under Clause VII of the 1897 Directory. By 1901, however, a complete reconciliation had occurred
Relativistic many-body calculations of the Stark-induced amplitude of the 6P1/2 -7P1/2 transition in thallium
Stark-induced amplitudes for the 6P1/2 - 7P1/2 transition in Tl I are
calculated using the relativistic SD approximation in which single and double
excitations of Dirac-Hartree-Fock levels are summed to all orders in
perturbation theory. Our SD values alpha S = 368 a0 3 and beta S= 298 a 0 3 are
in good agreement with the measurements alpha S=377(8) a 0 3$ and beta S =
313(8) a 0 3 by D. DeMille, D. Budker, and E. D. Commins [Phys. Rev. A 50, 4657
(1994)]. Calculations of the Stark shifts in the 6P1/2 - 7P1/2 and 6P1/2 -
7S1/2 transitions are also carried out. The Stark shifts predicted by our
calculations agree with the most accurate measured values within the
experimental uncertainties for both transitions
Composite Fermions and quantum Hall systems: Role of the Coulomb pseudopotential
The mean field composite Fermion (CF) picture successfully predicts angular
momenta of multiplets forming the lowest energy band in fractional quantum Hall
(FQH) systems. This success cannot be attributed to a cancellation between
Coulomb and Chern-Simons interactions beyond the mean field, because these
interactions have totally different energy scales. Rather, it results from the
behavior of the Coulomb pseudopotential V(L) (pair energy as a function of pair
angular momentum) in the lowest Landau level (LL). The class of short range
repulsive pseudopotentials is defined that lead to short range Laughlin like
correlations in many body systems and to which the CF model can be applied.
These Laughlin correlations are described quantitatively using the formalism of
fractional parentage. The discussion is illustrated with an analysis of the
energy spectra obtained in numerical diagonalization of up to eleven electrons
in the lowest and excited LL's. The qualitative difference in the behavior of
V(L) is shown to sometimes invalidate the mean field CF picture when applied to
higher LL's. For example, the nu=7/3 state is not a Laughlin nu=1/3 state in
the first excited LL. The analysis of the involved pseudopotentials also
explains the success or failure of the CF picture when applied to other systems
of charged Fermions with Coulomb repulsion, such as the Laughlin quasiparticles
in the FQH hierarchy or charged excitons in an electron-hole plasma.Comment: 27 pages, 23 figures, revised version (significant changes in text
and figures), submitted to Phil. Mag.
Temperature-dependent Fermi surface evolution in heavy fermion CeIrIn5
In Cerium-based heavy electron materials, the 4f electron's magnetic moments
bind to the itinerant quasiparticles to form composite heavy quasiparticles at
low temperature. The volume of the Fermi surfacein the Brillouin zone
incorporates the moments to produce a "large FS" due to the Luttinger theorem.
When the 4f electrons are localized free moments, a "small FS" is induced since
it contains only broad bands of conduction spd electrons. We have addressed
theoretically the evolution of the heavy fermion FS as a function of
temperature, using a first principles dynamical mean-field theory (DMFT)
approach combined with density functional theory (DFT+DMFT). We focus on the
archetypical heavy electrons in CeIrIn5, which is believed to be near a quantum
critical point. Upon cooling, both the quantum oscillation frequencies and
cyclotron masses show logarithmic scaling behavior (~ ln(T_0/T)) with different
characteristic temperatures T_0 = 130 and 50 K, respectively. The resistivity
coherence peak observed at T ~ 50 K is the result of the competition between
the binding of incoherent 4f electrons to the spd conduction electrons at Fermi
level and the formation of coherent 4f electrons.Comment: 5 pages main article,3 figures for the main article, 2 page
Supplementary information, 2 figures for the Supplementary information.
Supplementary movie 1 and 2 are provided on the
webpage(http://www-ph.postech.ac.kr/~win/supple.html
A theoretical study of the C- 4So_3/2 and 2Do_{3/2,5/2} bound states and C ground configuration: fine and hyperfine structures, isotope shifts and transition probabilities
This work is an ab initio study of the 2p3 4So_3/2, and 2Do_{3/2,5/2} states
of C- and 2p2 3P_{0,1,2}, 1D_2, and 1S_0 states of neutral carbon. We use the
multi-configuration Hartree-Fock approach, focusing on the accuracy of the wave
function itself. We obtain all C- detachment thresholds, including correlation
effects to about 0.5%. Isotope shifts and hyperfine structures are calculated.
The achieved accuracy of the latter is of the order of 0.1 MHz.
Intra-configuration transition probabilities are also estimated.Comment: 15 pages, 2 figures, 12 table
Three-body correlations and finite-size effects in the Moore--Read states on a sphere
Two- and three-body correlations in partially filled degenerate fermion
shells are studied numerically for various interactions between the particles.
Three distinct correlation regimes are defined, depending on the short-range
behavior of the pair pseudopotential. For pseudopotentials similar to those of
electrons in the first excited Landau level, correlations at half-filling have
a simple three-body form consisting of the maximum avoidance of the triplet
state with the smallest relative angular momentum R_3=3. In analogy to the
superharmonic criterion for Laughlin two-body correlations, their occurrence is
related to the form of the three-body pseudopotential at short range. The
spectra of a model three-body repulsion are calculated, and the zero-energy
Moore--Read ground state, its +-e/4-charged quasiparticles, and the
magnetoroton and pair-breaking bands are all identified. The quasiparticles are
correctly described by a composite fermion model appropriate for Halperin's
p-type pairing with Laughlin correlations between the pairs. However, the
Moore--Read ground state, and specially its excitations, have small overlaps
with the corresponding Coulomb eigenstates when calculated on a sphere. The
reason lies in surface curvature which affects the form of pair pseudopotential
for which the "R_3>3" three-body correlations occur. In finite systems, such
pseudopotential must be slightly superharmonic at short range (different from
Coulomb pseudopotential). However, the connection with the three-body
pseudopotential is less size-dependent, suggesting that the Moore--Read state
and its excitations are a more accurate description for experimental nu=5/2
states than could be expected from previous calculations.Comment: 12 pages, 12 figures, submitted to PR
Mapping Exoplanets
The varied surfaces and atmospheres of planets make them interesting places
to live, explore, and study from afar. Unfortunately, the great distance to
exoplanets makes it impossible to resolve their disk with current or near-term
technology. It is still possible, however, to deduce spatial inhomogeneities in
exoplanets provided that different regions are visible at different
times---this can be due to rotation, orbital motion, and occultations by a
star, planet, or moon. Astronomers have so far constructed maps of thermal
emission and albedo for short period giant planets. These maps constrain
atmospheric dynamics and cloud patterns in exotic atmospheres. In the future,
exo-cartography could yield surface maps of terrestrial planets, hinting at the
geophysical and geochemical processes that shape them.Comment: Updated chapter for Handbook of Exoplanets, eds. Deeg & Belmonte. 17
pages, including 6 figures and 4 pages of reference
Relativistic calculations of the lifetimes and hyperfine structure constants in Zn
This work presents accurate {\it ab initio} determination of the magnetic
dipole (M1) and electric quadrupole (E2) hyperfine structure constants for the
ground and a few low-lying excited states in Zn, which is one of
the interesting systems in fundamental physics. The coupled-cluster (CC) theory
within the relativistic framework has been used here in this calculations. Long
standing demands for a relativistic and highly correlated calculations like CC
can be able to resolve the disagreements among the lifetime estimations
reported previously for a few low-lying states of Zn. The role of
different electron correlation effects in the determination of these quantities
are discussed and their contributions are presented.Comment: 9 pages, 1 figure. submitted to J. Phys. B Fast Trac
A multivariate approach to heavy flavour tagging with cascade training
This paper compares the performance of artificial neural networks and boosted
decision trees, with and without cascade training, for tagging b-jets in a
collider experiment. It is shown, using a Monte Carlo simulation of events, that for a b-tagging efficiency of 50%, the light jet
rejection power given by boosted decision trees without cascade training is
about 55% higher than that given by artificial neural networks. The cascade
training technique can improve the performance of boosted decision trees and
artificial neural networks at this b-tagging efficiency level by about 35% and
80% respectively. We conclude that the cascade trained boosted decision trees
method is the most promising technique for tagging heavy flavours at collider
experiments.Comment: 14 pages, 12 figures, revised versio
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