515 research outputs found
(Un)frozen spaces: Exploring the role of sea ice in the marine socio-legal spaces of the Bering and Beaufort Seas
Sea ice is a dynamic physical element of the greater Arctic marine system, one that has myriad connections to human systems on a variety of spatial and temporal scales. Changes to the spatial extent of sea ice simultaneously permits and endangers maritime operations, as well as impacts current debates over maritime boundaries, presenting an interesting challenge for international law. Sea ice is not a stationary object; it moves through time and space in response to the physical forces of wind, ocean currents, and heating. It has a tangible, material and substantive role in contestations over territory, resources and marine boundaries in both the Beaufort and Bering Seas. We suggest here that sea ice’s material nature in these marine regions continuously challenges stationary conceptions of law in complex and sometimes contradictory ways. Building on recent work on the human geographies of sea ice, the dynamic field of legal geography and recent contributions in ocean-space geography, we outline how the dynamism of sea ice could influence notions of boundary, resources and climate change in ocean-spaces of the greater Arctic region
Efficient Doubling on Genus Two Curves over Binary Fields
In most algorithms involving elliptic and hyperelliptic curves, the costliest part consists in computing multiples of ideal classes. This paper investigates how to compute faster doubling over fields of characteristic two.
We derive explicit doubling formulae making strong use of the defining equation of the curve. We analyze how many field operations are needed depending on the curve making clear how much generality one loses by the respective choices. Note, that none of the proposed types is known to
be weak – one only could be suspicious because of the more special types. Our results allow to choose curves from a large enough variety which have extremely fast doubling needing only half the time of an addition. Combined with a sliding window method this leads to fast computation
of scalar multiples. We also speed up the general case
Theory of Double-Sided Flux Decorations
A novel two-sided Bitter decoration technique was recently employed by Yao et
al. to study the structure of the magnetic vortex array in high-temperature
superconductors. Here we discuss the analysis of such experiments. We show that
two-sided decorations can be used to infer {\it quantitative} information about
the bulk properties of flux arrays, and discuss how a least squares analysis of
the local density differences can be used to bring the two sides into registry.
Information about the tilt, compressional and shear moduli of bulk vortex
configurations can be extracted from these measurements.Comment: 17 pages, 3 figures not included (to request send email to
[email protected]
Counting points on hyperelliptic curves over finite fields
International audienceWe describe some algorithms for computing the cardinality of hyperelliptic curves and their Jacobians over finite fields. They include several methods for obtaining the result modulo small primes and prime powers, in particular an algorithm à la Schoof for genus 2 using Cantor's division polynomials. These are combined with a birthday paradox algorithm to calculate the cardinality. Our methods are practical and we give actual results computed using our current implementation. The Jacobian groups we handle are larger than those previously reported in the literature
Salinity tolerance of diapausing eggs of freshwater zooplankton
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73091/1/j.1365-2427.2004.01185.x.pd
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Measurement of the partial widths of the Z into up- and down-type quarks
Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma
decays were selected by tagging hadronic final states with isolated photon
candidates in the electromagnetic calorimeter. Combining the measured rates of
Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the
simultaneous determination of the widths of the Z into up- and down-type
quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18}
MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with
the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.
Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation
Data from e+e- annihilation into hadrons at centre-of-mass energies between
91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study
the four-jet rate as a function of the Durham algorithm resolution parameter
ycut. The four-jet rate is compared to next-to-leading order calculations that
include the resummation of large logarithms. The strong coupling measured from
the four-jet rate is alphas(Mz0)=
0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass)
in agreement with the world average. Next-to-leading order fits to the
D-parameter and thrust minor event-shape observables are also performed for the
first time. We find consistent results, but with significantly larger
theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.
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