23,822 research outputs found
The 13-C(p,d) Reaction at 120 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
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Directed routes or chosen pathways? : teachers' views of continuing professional development within a group of rural primary schools
This research project examines teachers' Continuing Professional Development (C. P. D. ) within two clusters of rural primary schools in the north of England. The research considers teachers' attitudes to, and their understanding of, the meaning and purpose of C. P. D., and how it affects themselves and the pupils they teach. The research, which is set within its historical context with particular reference to the impact of the Education Reform Act (1988) and the raft of initiatives that have influenced the direction of teachers' C. P. D., reflects on teachers as professionals. Through a combination of survey and case study, quantitative and qualitative approaches to data collection were used and the initial questionnaires were followed up by semi-structured interviews in the two case study schools. Using Bolam's (1993) tripartite definition as an analytical framework C. P. D. is subdivided into the areas of training, education and support. The data analysis showed that across both clusters teachers' C. P. D. was driven by national government initiatives and, in some cases, the national initiatives became the schools' priorities, leaving little opportunity for an individual school based approach to C. P. D. Across the clusters there was an established relationship between the School Development Plan (S. D. P. ), performance management and C. P. D. The one year performance management cycle appeared to dictate the length of the C. P. D. cycle and promoted short term development, reducing opportunities for longer courses, such as advanced diplomas and higher degrees. The constraints of the cycle, along with the emphasis on the deficit model of C. P. D., is viewed as contributing to the general deprofessionalisation of teachers
Spectroscopy of -nucleus bound states at GSI and FAIR --- very preliminary results and future prospects ---
The possible existence of \eta'-nucleus bound states has been put forward
through theoretical and experimental studies. It is strongly related to the
\eta' mass at finite density, which is expected to be reduced because of the
interplay between the anomaly and partial restoration of chiral
symmetry. The investigation of the C(p,d) reaction at GSI and FAIR, as well as
an overview of the experimental program at GSI and future plans at FAIR are
discussed.Comment: 7 pages, 3 figures; talk at the International Conference on Exotic
Atoms and Related Topics (EXA2014), Vienna, Austria, 15-19 September 2014. in
Hyperfine Interactions (2015
Parity-Affected Superconductivity in Ultrasmall Metallic Grains
We investigate the breakdown of BCS superconductivity in {\em ultra}\/small
metallic grains as a function of particle size (characterized by the mean
spacing between discrete electronic eigenstates), and the parity ( =
even/odd) of the number of electrons on the island. Assuming equally spaced
levels, we solve the parity-dependent BCS gap equation for the order parameter
. Both the critical level spacing and the
critical temperature at which are parity
dependent, and both are so much smaller in the odd than the even case that
these differences should be measurable in current experiments.Comment: 4 pages RevTeX, 1 encapsulated postscript figure, submitted to
Physical Review Letter
Berezin-type quantization on even-dimensional compact manifolds
In this article we show that a Berezin-type quantization can be achieved on a
compact even dimensional manifold by removing a skeleton of
lower dimension such that what remains is diffeomorphic to
which we identify with and embed in . A local
Poisson structure and Berezin-type quantization are induced from . We have a Hilbert space with a reproducing kernel. The symbols of
bounded linear operators on the Hilbert space have a star product which
satisfies the correspondence principle outside a set of measure zero. This
construction depends on the diffeomorphism. However, suppose has a complex structure and we have from , ( a set
of measure zero or empty) a biholomorphism from it to , (where is of measure zero or empty). As before we embed in and then into and we
have a Berezin-type quantization induced from . If we use
another biholomorphism, we have a map of the two Hilbert spaces under
consideration such that the reproducing kernel of one maps to the reproducing
kernel of the other and we have an equivalent quantization. We have a similar
construction where we consider an arbitrary complex manifold and use local
coordinates to induce the quantization from . We study the
possibility of defining a global Berezin quantization on compact complex
manifolds. We give a defintion of pullback Toeplitz operators and exhibit
Toeplitz quantization of compact even dimensional manifolds after removing a
set of measure zero. Next we give a simple construction of pullback coherent
states on compact smooth manifolds which are simplified versions of those
defined in an earlier work by the authors
List decoding Reed-Muller codes over small fields
The list decoding problem for a code asks for the maximal radius up to which
any ball of that radius contains only a constant number of codewords. The list
decoding radius is not well understood even for well studied codes, like
Reed-Solomon or Reed-Muller codes.
Fix a finite field . The Reed-Muller code
is defined by -variate degree-
polynomials over . In this work, we study the list decoding radius
of Reed-Muller codes over a constant prime field ,
constant degree and large . We show that the list decoding radius is
equal to the minimal distance of the code.
That is, if we denote by the normalized minimal distance of
, then the number of codewords in any ball of
radius is bounded by independent
of . This resolves a conjecture of Gopalan-Klivans-Zuckerman [STOC 2008],
who among other results proved it in the special case of
; and extends the work of Gopalan [FOCS 2010] who
proved the conjecture in the case of .
We also analyse the number of codewords in balls of radius exceeding the
minimal distance of the code. For , we show that the number of
codewords of in a ball of radius is bounded by , where
is independent of . The dependence on is tight.
This extends the work of Kaufman-Lovett-Porat [IEEE Inf. Theory 2012] who
proved similar bounds over .
The proof relies on several new ingredients: an extension of the
Frieze-Kannan weak regularity to general function spaces, higher-order Fourier
analysis, and an extension of the Schwartz-Zippel lemma to compositions of
polynomials.Comment: fixed a bug in the proof of claim 5.6 (now lemma 5.5
Theoretical studies in the molecular Platonic solids: Pure and mixed carbon, nitrogen, phosphorus, and silicon tetrahedranes
Calculations were conducted at the G4MP2 and G4 composite method levels of theory on the 35 potential carbon, nitrogen, silicon, and phosphorus tetrahedrane derivatives with the general form C~a~N~b~Si~c~P~d~H~(4-b-d)~ (where a+b+c+d=4). At both levels of theory, optimized electronic ground state neutral singlet gas phase (298.15 K, 1 atm) geometries were obtained for 24 of the 35 possible C/N/Si/P tetrahedrane derivatives. Corresponding enthalpies of formation were calculated using the atomization method. Triplet state neutral tetrahedron starting geometries for all compounds either resulted in cage opening or failed to converge. Only 9 cationic and 3 anionic forms converged to stable geometries that retained the tetrahedron cage and were absent imaginary frequencies, thereby allowing the calculation of adiabatic ionization energies and electron affinities
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