368 research outputs found
The Teaching of Legislation in Canadian Law Faculties
Wade MacLauchlan: On behalf of Pierre Issalys, who serves as co- President of the Administrative Law Section of the Canadian Association of Law Teachers, and myself, I would like to welcome you to our annual section meeting. The subject which has been adopted for today\u27s meeting is: The Teaching of Legislation in Canadian Law Faculties . We have the good fortune to have as panelists three of the most experienced and vital teachers of Administrative Law in the country. Professors Terry Ison of Osgoode Hall Law School, Hudson Janisch of the University of Toronto and Pierre-Andr6 Cot6 of l\u27Universit6 de Montr6al combine sixty years of teaching in various law faculties across Canada. Moreover, each has made his mark in specific areas related to legislation, Professor Ison in compensation schemes, particularly in workers\u27 compensation, Professor Janisch in the area of regulated industries and Professor Cot6 in statutory interpretation
Orientation of the Stripe Formed by the Two-Dimensional Electrons in Higher Landau Levels
Effect of periodic potential on the stripe phase realized in the higher
Landau levels is investigated by the Hartree-Fock approximation. The period of
the potential is chosen to be two to six times of the fundamental period of the
stripe phase. It is found that the stripe aligns perpendicularly to the
external potential in contrast to a naive expectation and hydrodynamic theory.
Charge modulation towards the Wigner crystallization along the stripe is
essential for the present unexpected new result.Comment: 5 pages, RevTex, two figures included in the tex
Static Properties of Trapped Bose-Fermi Mixed Condensate of Alkali Atoms
Static properties of a bose-fermi mixture of trapped potassium atoms are
studied in terms of coupled Gross-Pitaevskii and Thomas-Fermi equations for
both repulsive and attractive bose-fermi interatomic potentials. Qualitative
estimates are given for solutions of the coupled equations, and the parameter
regions are obtained analytically for the boson-density profile change and for
the boson/fermion phase separation. Especially, the parameter ratio
is found that discriminates the region of the large boson-profile change. These
estimates are applied for numerical results for the potassium atoms and checked
their consistency. It is suggested that a small fraction of fermions could be
trapped without an external potential for the system with an attractive
boson-fermion interaction.Comment: 8 pages,5 figure
An atlas of 2.4 to 4.1 microns ISO/SWS spectra of early-type stars
We present an atlas of spectra of O- and B-type stars, obtained with the
Short Wavelength Spectrometer (SWS) during the Post-Helium program of the
Infrared Space Observatory (ISO). This program is aimed at extending the Morgan
& Keenan classification scheme into the near-infrared. Later type stars will be
discussed in a seperate publication. The observations consist of 57 SWS
Post-Helium spectra from 2.4 to 4.1 microns, supplemented with 10 spectra
acquired during the nominal mission with a similar observational setting. For
B-type stars, this sample provides ample spectral converage in terms of subtype
and luminosity class. For O-type stars,the ISO sample is coarse and therefore
is complemented with 8 UKIRT L'-band observations. In terms of the presence of
diagnostic lines, the L'-band is likely the most promising of the near-infrared
atmospheric windows for the study of the physical properties of B stars.
Specifically, this wavelength interval contains the Brackett alpha, Pfund
gamma, and other Pfund lines which are probes of spectral type, luminosity
class and mass loss. Here, we present simple empirical methods based on the
lines present in the 2.4 to 4.1 microns interval that allow the determination
of: the spectral type of B dwarfs and giants to within two subtypes; the
luminosity class of B stars to within two classes; the mass-loss rate of O
stars and B supergiants to within 0.25 dex.Comment: 19 pages, 11 Postscript figures, accepted by A&
Zero-temperature phase diagram of binary boson-fermion mixtures
We calculate the phase diagram for dilute mixtures of bosons and fermions at
zero temperature. The linear stability conditions are derived and related to
the effective boson-induced interaction between the fermions. We show that in
equilibrium there are three possibilities: a) a single uniform phase, b) a
purely fermionic phase coexisting with a purely bosonic one and c) a purely
fermionic phase coexisting with a mixed phase.Comment: 8 pages, revtex, 3 postscript figures; NORDITA-1999/71 C
Disk Evolution in W5: Intermediate Mass Stars at 2-5 Myr
We present the results of a survey of young intermediate mass stars (age
~5 Myr, 1.5 15 ) in the W5 massive star
forming region. We use combined optical, near-infrared and {\it Spitzer} Space
Telescope photometry and optical spectroscopy to define a sample of stars of
spectral type A and B and examine their infrared excess properties. We find
objects with infrared excesses characteristic of optically thick disks, i.e.
Herbig AeBe stars. These stars are rare: 1.5% of the entire spectroscopic
sample of A and B stars, and absent among stars more massive than 2.4
. 7.5% of the A and B stars possess infrared excesses in a variety of
morphologies that suggest their disks are in some transitional phase between an
initial, optically thick accretion state and later evolutionary states. We
identify four morphological classes based on the wavelength dependence of the
observed excess emission above theoretical photospheric levels: (a) the
optically thick disks; (b) disks with an optically thin excess over the
wavelength range 2 to 24 \micron, similar to that shown by Classical Be
stars; (c) disks that are optically thin in their inner regions based on their
infrared excess at 2-8 \micron and optically thick in their outer regions
based on the magnitude of the observed excess emission at 24 \micron; (d)
disks that exhibit empty inner regions (no excess emission at
8 \micron) and some measurable excess emission at 24 \micron. A sub-class
of disks exhibit no significant excess emission at 5.8
\micron, have excess emission only in the {\it Spitzer} 8 \micron band and
no detection at 24 \micron. We discuss these spectral energy distribution
(SED) types, suggest physical models for disks exhibiting these emission
patterns and additional observations to test these theories.Comment: 35 pages, 10 figures, accepted to Astrophysical Journa
Sliding motion of a two-dimensional Wigner crystal in a strong magnetic field
We study the sliding state of a two-dimensional Wigner crystal in a strong
magnetic field and a random impurity potential. Using a high-velocity
perturbation theory, we compute the nonlinear conductivity, various correlation
functions, and the interference effects arising in combined AC + DC electric
effects, including the Shapiro anomaly and the linear response to an AC field.
Disorder is found to induce mainly transverse distortions in the sliding state
of the lattice. The Hall resistivity retains its classical value. We find that,
within the large velocity perturbation theory, free carriers which affect the
longitudinal phonon modes of the Wigner crystal do not change the form of the
nonlinear conductivity. We compare the present sliding Wigner crystal in a
strong magnetic field to the conventional sliding charge-density wave systems.
Our result for the nonlinear conductivity agrees well with the
characteristics measured in some experiments at low temperatures or large
depinning fields, for the insulating phases near filling factor = 1/5. We
summarize the available experimental data, and point out the differences among
them.Comment: appeared in RPB vol. 50, 4600 (1994); LaTex file; 3 figures available
from [email protected]
GHASP : an H alpha kinematic survey of spiral and irregular galaxies. V. Dark matter distribution in 36 nearby spiral galaxies
The results obtained from a study of the mass distribution of 36 spiral
galaxies are presented. The galaxies were observed using Fabry-Perot
interferometry as part of the GHASP survey. The main aim of obtaining high
resolution H alpha 2D velocity fields is to define more accurately the rising
part of the rotation curves which should allow to better constrain the
parameters of the mass distribution. The H alpha velocities were combined with
low resolution HI data from the literature, when available. Combining the
kinematical data with photometric data, mass models were derived from these
rotation curves using two different functional forms for the halo: an
isothermal sphere and an NFW profile. For the galaxies already modeled by other
authors, the results tend to agree. Our results point at the existence of a
constant density core in the center of the dark matter halos rather than a
cuspy core, whatever the type of the galaxy from Sab to Im. This extends to all
types the result already obtained by other authors studying dwarf and LSB
galaxies but would necessitate a larger sample of galaxies to conclude more
strongly. Whatever model is used (ISO or NFW), small core radius halos have
higher central densities, again for all morphological types. We confirm
different halo scaling laws, such as the correlations between the core radius
and the central density of the halo with the absolute magnitude of a galaxy:
low luminosity galaxies have small core radius and high central density. We
find that the product of the central density with the core radius of the dark
matter halo is nearly constant, whatever the model and whatever the absolute
magnitude of the galaxy. This suggests that the halo surface density is
independent from the galaxy type.Comment: 21 pages, 14 figures. MNRAS (accepted october 3rd 2007
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