11,062 research outputs found
Patchak v. Zinke, Separation of Powers, and the Pitfalls of Form over Substance
Mr. Patchak was a concerned citizen with standing to bring a suit against the federal government. A previous Supreme Court decision, Carcieri v. Salazar, made it clear that Mr. Patchak would win his case. Congress, however, did not want him to do so. Congress passed, and President Obama signed, the Gun Lake Act, which effectively ordered Mr. Patchak’s suit to be dismissed. Mr. Patchak’s suit was subsequently dismissed, and he appealed on the grounds that the Gun Lake Act violated separation of powers principles
The Partially-Split Hall Bar: Tunneling in the Bosonic Integer Quantum Hall Effect
We study point-contact tunneling in the integer quantum Hall state of bosons.
This symmetry-protected topological state has electrical Hall conductivity
equal to and vanishing thermal Hall conductivity. In contrast to the
integer quantum Hall state of fermions, a point contact can have a dramatic
effect on the low energy physics. In the absence of disorder, a point contact
generically leads to a partially-split Hall bar geometry. We describe the
resulting intermediate fixed point via the two-terminal electrical (Hall)
conductance of the edge modes. Disorder along the edge, however, both restores
the universality of the two-terminal conductance and helps preserve the
integrity of the Hall bar within the relevant parameter regime.Comment: 12 pages, 5 figures; v.2: typos fixed and clarified some argument
Criticality in multicomponent spherical models : results and cautions
To enable the study of criticality in multicomponent fluids, the standard
spherical model is generalized to describe an \ns-species hard core lattice
gas. On introducing \ns spherical constraints, the free energy may be
expressed generally in terms of an \ns\times\ns matrix describing the species
interactions. For binary systems, thermodynamic properties have simple
expressions, while all the pair correlation functions are combinations of just
two eigenmodes. When only hard-core and short-range overall attractive
interactions are present, a choice of variables relates the behavior to that of
one-component systems. Criticality occurs on a locus terminating a coexistence
surface; however, except at some special points, an unexpected
``demagnetization effect'' suppresses the normal divergence of susceptibilities
at criticality and distorts two-phase coexistence. This effect, unphysical for
fluids, arises from a general lack of symmetry and from the vectorial and
multicomponent character of the spherical model. Its origin can be understood
via a mean-field treatment of an XY spin system below criticality.Comment: 4 figure
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