199 research outputs found
Construction of spherical cubature formulas using lattices
We construct cubature formulas on spheres supported by homothetic images of
shells in some Euclidian lattices. Our analysis of these cubature formulas uses
results from the theory of modular forms. Examples are worked out on the sphere
of dimension n-1 for n=4, 8, 12, 14, 16, 20, 23, and 24, and the sizes of the
cubature formulas we obtain are compared with the lower bounds given by Linear
Programming
A new approach to professional learning for academics teaching in next generation learning spaces
Abstract The promise of Next Generation Learning Spaces appears to remain unfulfilled. This chapter explores why and how the design of professional learning for academics teaching in such spaces can and should be transformed. It takes a fresh look at why old professional development is failing and proposes a new way to engage academics in their own professional learning. Rather than continuing with traditional professional development that is most often, ad hoc, formal and centrally driven, comprising mandated professional development workshops and a website that may only be visited once, the chapter explores the move from 'old' professional development to 'new' professional learning. It draws on the fields of organisational theory, cognitive theory and behavioural economics. New professional learning is characterised by a 'pull' rather than a 'push' philosophy. Academic staff themselves drive their own learning, choosing what, when and how they want to learn to become better teachers. Multiple and various learning opportunities embedded in day to day work are just-in-time, self-directed, performance-driven and evaluated within an organisational system. In this way the institutional setting influences behaviour by 'nudging' habits and setting defaults resulting in academics making the 'right' decisions and doing the 'right' thing. By addressing the compelling issue of how to enhance academic staff teaching capability, this chapter can help university leaders to think beyond the professional development approaches of yesterday. Aligning with this new direction will result in enhanced learning and teaching in the future
Which finitely generated Abelian groups admit isomorphic Cayley graphs?
We show that Cayley graphs of finitely generated Abelian groups are rather
rigid. As a consequence we obtain that two finitely generated Abelian groups
admit isomorphic Cayley graphs if and only if they have the same rank and their
torsion parts have the same cardinality. The proof uses only elementary
arguments and is formulated in a geometric language.Comment: 16 pages; v2: added reference, reformulated quasi-convexity, v3:
small corrections; to appear in Geometriae Dedicat
Assessing professional skills development at a third year level
Employers, professional bodies, instructors and students themselves recognise the need for graduates to leave university with a good understanding of both disciplinary content as well as a range of highly developed professional skills. Many universities have responded to this need by encouraging the development of such skills in their programs of study. Curtin Business School has implemented the Professional Skills Project that aims to integrate the teaching and assessing of professional skills into the units of the Bachelor of Commerce degree program.As part of this initiative, the first author successfully won a grant to implement a project that focussed on supporting students' development of their presentation and written communication skills in his third year management unit. These skills were specifically selected based on the lecturer's previous experiences of teaching the unit which showed that while students in CBS are given opportunities to develop their of professional skills throughout the course, there seemed to be a significant variation in students' skill levels. The variation in skill development was particularly apparent in the assessment of group presentations and written assignments in semester one 2001. Thus, opportunities for students to develop these skills were integrated into the unit and data on students' perceptions of their skill development were obtained by them completing a questionnaire at the beginning and end of the unit.In this paper, we outline how the skills were taught and assessed, present the data on the changes in students' perceptions of their skill levels, and discuss the implications for teaching and assessing presentation and written communication skills in the context of the discipline
An elementary approach to toy models for D. H. Lehmer's conjecture
In 1947, Lehmer conjectured that the Ramanujan's tau function
never vanishes for all positive integers , where is the -th
Fourier coefficient of the cusp form of weight 12. The theory of
spherical -design is closely related to Lehmer's conjecture because it is
shown, by Venkov, de la Harpe, and Pache, that is equivalent to
the fact that the shell of norm of the -lattice is a spherical
8-design. So, Lehmer's conjecture is reformulated in terms of spherical
-design.
Lehmer's conjecture is difficult to prove, and still remains open. However,
Bannai-Miezaki showed that none of the nonempty shells of the integer lattice
\ZZ^2 in \RR^2 is a spherical 4-design, and that none of the nonempty
shells of the hexagonal lattice is a spherical 6-design. Moreover, none
of the nonempty shells of the integer lattices associated to the algebraic
integers of imaginary quadratic fields whose class number is either 1 or 2,
except for \QQ(\sqrt{-1}) and \QQ(\sqrt{-3}) is a spherical 2-design. In
the proof, the theory of modular forms played an important role.
Recently, Yudin found an elementary proof for the case of \ZZ^{2}-lattice
which does not use the theory of modular forms but uses the recent results of
Calcut. In this paper, we give the elementary (i.e., modular form free) proof
and discuss the relation between Calcut's results and the theory of imaginary
quadratic fields.Comment: 18 page
Caffeine intake, plasma caffeine level, and kidney function: a Mendelian randomization study
Caffeine is a psychoactive substance widely consumed worldwide, mainly via sources such as coffee and tea. The effects of caffeine on kidney function remain unclear. We leveraged the genetic variants in the CYP1A2 and AHR genes via the two-sample Mendelian randomization (MR) framework to estimate the association of genetically predicted plasma caffeine and caffeine intake on kidney traits. Genetic association summary statistics on plasma caffeine levels and caffeine intake were taken from genome-wide association study (GWAS) meta-analyses of 9876 and of >47,000 European ancestry individuals, respectively. Genetically predicted plasma caffeine levels were associated with a decrease in estimated glomerular filtration rate (eGFR) measured using either creatinine or cystatin C. In contrast, genetically predicted caffeine intake was associated with an increase in eGFR and a low risk of chronic kidney disease. The discrepancy is likely attributable to faster metabolizers of caffeine consuming more caffeine-containing beverages to achieve the same pharmacological effect. Further research is needed to distinguish whether the observed effects on kidney function are driven by the harmful effects of higher plasma caffeine levels or the protective effects of greater intake of caffeine-containing beverages, particularly given the widespread use of drinks containing caffeine and the increasing burden of kidney disease
Measuring the quality of a quantum reference frame: the relative entropy of frameness
In the absence of a reference frame for transformations associated with a
group G, any quantum state that is non-invariant under the action of G may
serve as a token of the missing reference frame. We here introduce a novel
measure of the quality of such a token: the relative entropy of frameness. This
is defined as the relative entropy distance between the state of interest and
the nearest G-invariant state. Unlike the relative entropy of entanglement,
this quantity is straightforward to calculate and we find it to be precisely
equal to the G-asymmetry, a measure of frameness introduced by Vaccaro et al.
It is shown to provide an upper bound on the mutual information between the
group element encoded into the token and the group element that may be
extracted from it by measurement. In this sense, it quantifies the extent to
which the token successfully simulates a full reference frame. We also show,
that despite a suggestive analogy from entanglement theory, the regularized
relative entropy of frameness is zero and therefore does not quantify the rate
of interconversion between the token and some standard form of quantum
reference frame. Finally, we show how these investigations yield a novel
approach to bounding the relative entropy of entanglement.Comment: 12 pages; many improvements in v2 including a weakening of the
assumptions of the main theorem and better upper bounds for both the relative
entropy of frameness for arbitrary compact Lie groups and the relative
entropy of entanglement. Published versio
New Dimensions for Wound Strings: The Modular Transformation of Geometry to Topology
We show, using a theorem of Milnor and Margulis, that string theory on
compact negatively curved spaces grows new effective dimensions as the space
shrinks, generalizing and contextualizing the results in hep-th/0510044.
Milnor's theorem relates negative sectional curvature on a compact Riemannian
manifold to exponential growth of its fundamental group, which translates in
string theory to a higher effective central charge arising from winding
strings. This exponential density of winding modes is related by modular
invariance to the infrared small perturbation spectrum. Using self-consistent
approximations valid at large radius, we analyze this correspondence explicitly
in a broad set of time-dependent solutions, finding precise agreement between
the effective central charge and the corresponding infrared small perturbation
spectrum. This indicates a basic relation between geometry, topology, and
dimensionality in string theory.Comment: 28 pages, harvmac big. v2: references and KITP preprint number added,
minor change
On three-manifolds dominated by circle bundles
We determine which three-manifolds are dominated by products. The result is
that a closed, oriented, connected three-manifold is dominated by a product if
and only if it is finitely covered either by a product or by a connected sum of
copies of the product of the two-sphere and the circle. This characterization
can also be formulated in terms of Thurston geometries, or in terms of purely
algebraic properties of the fundamental group. We also determine which
three-manifolds are dominated by non-trivial circle bundles, and which
three-manifold groups are presentable by products.Comment: 12 pages; to appear in Math. Zeitschrift; ISSN 1103-467
Property (RD) for Hecke pairs
As the first step towards developing noncommutative geometry over Hecke
C*-algebras, we study property (RD) (Rapid Decay) for Hecke pairs. When the
subgroup H in a Hecke pair (G,H) is finite, we show that the Hecke pair (G,H)
has (RD) if and only if G has (RD). This provides us with a family of examples
of Hecke pairs with property (RD). We also adapt Paul Jolissant's works in 1989
to the setting of Hecke C*-algebras and show that when a Hecke pair (G,H) has
property (RD), the algebra of rapidly decreasing functions on the set of double
cosets is closed under holomorphic functional calculus of the associated
(reduced) Hecke C*-algebra. Hence they have the same K_0-groups.Comment: A short note added explaining other methods to prove that the
subalgebra of rapidly decreasing functions is smooth. This is the final
version as published. The published version is available at: springer.co
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