Sea Level at Port Leopold, N.W.T. in 1848

Forty-seven days of hourly sea level and atmospheric pressure data collected in 1848 at Port Leopold, N.W.T., are analyzed using modern time series computation techniques. Tidal analysis reveals a mixed tide but mainly semi-diurnal. A detailed analysis of the tidal data reveals that the time-keeping of the record was as good as today's standard. A high correlation between hourly sea level and atmospheric pressure data demonstrates the inverse barometric effect.Key words: Arctic, sea level, tide, ice cover, free oscillation, lowpass, scatter diagram, time series, Resolute, Port LeopoldMots clés: Arctique, Niveau de la mer, marée, couvert de glace, oscillation libre, goulet, diagramme de dispersion, series chronologiques, Resolute, Port Léopol

El culto lícito a los Santos y Beatos (canon 1187)

The aim of the article is to given an explanatory overview of canon 1187, starting from the process by which it was drafted. This commentary involves the clarification of a number of key concepts, including the difference between canonization and beatification, private and public devotion, licit acts of devotion to Servants of God and licit public worship devotion to Blesseds and Saints.El artículo pretende explicitar exegéticamente los contenidos del can. 1187 comenzando por su proceso de su redacción. En el comentario del canon se llevará a cabo una necesaria clarificación de conceptos, se diferenciarán los actos de la canonización y la beatificación, los de culto público y privado, los actos lícitos de culto a los Siervos de Dios y el culto público lícito que se puede otorgar a los Beatos y a los Santos

On the Phase Diagram of the SU(2) Adjoint Higgs Model in 2+1 Dimensions

The phase diagram is investigated for SU(2) lattice gauge theory in d=3, coupled to adjoint scalars. For small values of the quartic scalar coupling, lambda, the transition separating Higgs and confinement phases is found to be first-order, in agreement with earlier work by Nadkarni. The surface of second-order transitions conjectured by Nadkarni, however, is shown instead to correspond to crossover behaviour. This conclusion is based on a finite size analysis of the scalar mass and susceptibility. The nature of the phase transition at the termination of first-order behaviour is investigated and we find evidence for a critical point at which the scalar mass vanishes. The photon mass and confining string tension are measured and are found to be negligibly small in the Higgs phase. This is correlated with the very small density of magnetic monopoles in the Higgs phase. The string tension and photon mass rise rapidly as the crossover is traversed towards the symmetric phase.Comment: LaTeX. Replaced with version to be published in Physics Letters B. Minor changes onl

Search for Kosterlitz-Thouless transition in a triangular Ising antiferromagnet with further-neighbour ferromagnetic interactions

We investigate an antiferromagnetic triangular Ising model with anisotropic ferromagnetic interactions between next-nearest neighbours, originally proposed by Kitatani and Oguchi (J. Phys. Soc. Japan {\bf 57}, 1344 (1988)). The phase diagram as a function of temperature and the ratio between first- and second- neighbour interaction strengths is thoroughly examined. We search for a Kosterlitz-Thouless transition to a state with algebraic decay of correlations, calculating the correlation lengths on strips of width up to 15 sites by transfer-matrix methods. Phenomenological renormalization, conformal invariance arguments, the Roomany-Wyld approximation and a direct analysis of the scaled mass gaps are used. Our results provide limited evidence that a Kosterlitz-Thouless phase is present. Alternative scenarios are discussed.Comment: 10 pages, RevTeX 3; 11 Postscript figures (uuencoded); to appear in Phys. Rev. E (1995

Globally Optimal Spatio-temporal Reconstruction from Cluttered Videos

International audienceWe propose a method for multi-view reconstruction from videos adapted to dynamic cluttered scenes under uncontrolled imaging conditions. Taking visibility into account, and being based on a global optimization of a true spatio-temporal energy, it oilers several desirable properties: no need for silhouettes, robustness to noise, independent from any initialization, no heuristic force, reduced flickering results, etc. Results on real-world data proves the potential of what is, to our knowledge, the only globally optimal spatio-temporal multi-view reconstruction method

Order-Disorder Transition in a Two-Layer Quantum Antiferromagnet

We have studied the antiferromagnetic order -- disorder transition occurring at $T=0$ in a 2-layer quantum Heisenberg antiferromagnet as the inter-plane coupling is increased. Quantum Monte Carlo results for the staggered structure factor in combination with finite-size scaling theory give the critical ratio $J_c = 2.51 \pm 0.02$ between the inter-plane and in-plane coupling constants. The critical behavior is consistent with the 3D classical Heisenberg universality class. Results for the uniform magnetic susceptibility and the correlation length at finite temperature are compared with recent predictions for the 2+1-dimensional nonlinear $\sigma$-model. The susceptibility is found to exhibit quantum critical behavior at temperatures significantly higher than the correlation length.Comment: 11 pages (5 postscript figures available upon request), Revtex 3.

Thermodynamics of the Anisotropic Spin-1/2 Heisenberg Chain and Related Quantum Chains

The free energy and correlation lengths of the spin-1/2 $XYZ$ chain are studied at finite temperature. We use the quantum transfer matrix approach and derive non-linear integral equations for all eigenvalues. Analytic results are presented for the low-temperature asymptotics, in particular for the critical $XXZ$ chain in an external magnetic field. These results are compared to predictions by conformal field theory. The integral equations are solved numerically for the non-critical $XXZ$ chain and the related spin-1 biquadratic chain at arbitrary temperature.Comment: 31 pages, LATEX, 5 PostScript figures appended, preprint cologne-93-471

Disorder Induced Phase Transition in a Random Quantum Antiferromagnet

A two-dimensional Heisenberg model with random antiferromagnetic nearest-neighbor exchange is studied using quantum Monte Carlo techniques. As the strength of the randomness is increased, the system undergoes a transition from an antiferromagnetically ordered ground state to a gapless disordered state. The finite-size scaling of the staggered structure factor and susceptibility is consistent with a dynamic exponent $z = 2$.Comment: Revtex 3.0, 10 pages + 5 postscript figures available upon request, UCSBTH-94-1