5,766 research outputs found
Exceptional covers and bijections on rational points
We show that if f: X --> Y is a finite, separable morphism of smooth curves
defined over a finite field F_q, where q is larger than an explicit constant
depending only on the degree of f and the genus of X, then f maps X(F_q)
surjectively onto Y(F_q) if and only if f maps X(F_q) injectively into Y(F_q).
Surprisingly, the bounds on q for these two implications have different orders
of magnitude. The main tools used in our proof are the Chebotarev density
theorem for covers of curves over finite fields, the Castelnuovo genus
inequality, and ideas from Galois theory.Comment: 19 pages; various minor changes to previous version. To appear in
International Mathematics Research Notice
Evaluating the application of research-based guidance to the design of an emergency preparedness leaflet
UNLABELLED: Guidelines for the design of emergency communications were derived from primary research and interrogation of the literature. The guidelines were used to re-design a nuclear emergency preparedness leaflet routinely distributed to households in the local area. Pre-test measures of memory for, and self-reported understanding of, nuclear safety information were collected. The findings revealed high levels of non-receipt of the leaflet, and among those who did receive it, memory for safety advice was poor. Subjective evaluations of the trial leaflet suggested that it was preferred and judged easier to understand than the original. Objective measures of memory for the two leaflets were also recorded, once after the study period, and again one week or four weeks later. Memory for the advice was better, at all time periods, when participants studied the trial leaflet. The findings showcase evaluation of emergency preparedness literature and suggest that extant research findings can be applied to the design of communications to improve memory and understandability. STATEMENT OF RELEVANCE: Studies are described that showcase the use of research-based guidelines to design emergency communications and provide both subjective and objective data to support designing emergency communications in this way. In addition, the research evaluates the effectiveness of emergency preparedness leaflets that are routinely distributed to households. This work is of relevance to academics interested in risk communication and to practitioners involved in civil protection and emergency preparedness
Distinguishability of infinite groups and graphs
The distinguishing number of a group G acting faithfully on a set V is the least number of colors needed to color the elements of V so that no non-identity element of the group preserves the coloring. The distinguishing number of a graph is the distinguishing number of its automorphism group acting on its vertex set. A connected graph Gamma is said to have connectivity 1 if there exists a vertex alpha \in V\Gamma such that Gamma \setminus \{\alpha\} is not connected. For alpha \in V, an orbit of the point stabilizer G_\alpha is called a suborbit of G.
We prove that every nonnull, primitive graph with infinite diameter and countably many vertices has distinguishing number 2. Consequently, any nonnull, infinite, primitive, locally finite graph is 2-distinguishable; so, too, is any infinite primitive permutation group with finite suborbits. We also show that all denumerable vertex-transitive graphs of connectivity 1 and all Cartesian products of connected denumerable graphs of infinite diameter have distinguishing number 2.
All of our results follow directly from a versatile lemma which we call The Distinct Spheres Lemma
Origin of anomalous breakdown of Bloch's rule in the Mott-Hubbard insulator MnTe
We reinvestigate the pressure dependence of the crystal structure and
antiferromagnetic phase transition in MnTe by the rigorous and reliable
tool of high pressure neutron powder diffraction. First-principles density
functional theory calculations are carried out in order to gain microscopic
insight. The measured N\'eel temperature of MnTe is found to show unusually
large pressure dependence of K GPa. This gives rise to large
violation of Bloch's rule given by , to a value of -6.0 0.1 for
MnTe. The ab-initio calculation of the electronic structure and the
magnetic exchange interactions in MnTe, for the measured crystal structures
at different pressures, gives the pressure dependence of the Ne\'el
temperature, to be -5.61, in close agreement with experimental
finding. The microscopic origin of this behavior turns to be dictated by the
distance dependence of the cation-anion hopping interaction strength
The kinetics of surfactant desorption at the air–solution interface
The kinetics of desorption of the anionic surfactant sodium dodecylbenzene sulfonate at the air–solution interface have been studied using neutron reflectivity (NR). The experimental arrangement incorporates a novel flow cell in which the subphase can be exchanged (diluted) using a laminar flow whilst the surface region remains unaltered. The kinetics of the desorption is relatively slow and occurs over many tens of minutes compared with the dilution timescale of approximately 10–30 minutes. A detailed mathematical model, in which the rate of the desorption is determined by transport through a near-surface diffusion layer into a diluted bulk solution below, is developed and provides a good description of the timedependent adsorption data.\ud
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A key parameter of the model is the ratio of the depth of the diffusion layer, Hc , to the depth of the fluid, Hf, and we find that this is related to the reduced Péclet number, Pe*, for the system, via Hc/Hf, = C/Pe* 1/ 2 . Although from a highly idealised experimental arrangement, the results provide an important insight into the ‘rinse mechanism’, which is applicable to a wide variety of domestic and industrial circumstances
An analysis of likes and dislikes for history and geography of 3360 sixth grade children
Thesis (Ed.M.)--Boston Universit
Mixed Sneutrinos, Dark Matter and the LHC
We study the phenomenology of supersymmetric models in which gauge-singlet
scalars mix with the MSSM sneutrinos through weak-scale terms. After
reviewing the constraints on mixed-sneutrino dark matter from measurements of
and from direct-detection experiments, we explore
mixed-sneutrino signatures relevant to the LHC. For a mixed-sneutrino LSP and a
right-handed slepton NLSP, decays of the lightest neturalino can produce
opposite-sign, same-flavor (OSSF) dileptons with an invariant-mass distribution
shifted away from the kinematic endpoint. In different parameter regions, the
charginos and neutralinos produced in cascades all decay dominantly to the
lighter sneutrinos, leading to a kinematic edge in the jet-lepton
invariant-mass distribution from the decay chain \tilde{q} \to \chi^- q \to
\snu^* l q, without an OSSF dilepton signature. We explore the possibility of
using mass estimation methods to distinguish this mixed-sneutrino jet-lepton
signature from an MSSM one. Finally, we consider signatures associated with
Higgs-lepton or -lepton production in cascades involving the heavier
sneutrinos
Carrying Little Sticks: Is There a ‘Deterrence Gap’ in Employment Standards Enforcement in Ontario, Canada?
This article assesses whether a deterrence gap exists in the enforcement of the Ontario Employment Standards Act (ESA), which sets minimum conditions of employment in areas such as minimum wage, overtime pay and leaves. Drawing on a unique administrative data set, the article measures the use of deterrence in Ontario’s ESA enforcement regime against the role of deterrence within two influential models of enforcement: responsive regulation and strategic enforcement. The article finds that the use of deterrence is below its prescribed role in either model of enforcement. We conclude that there is a deterrence gap in Ontario
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