272 research outputs found
Public and Private Property Rights: Regulatory and Physical Takings and the Public Trust Doctrine
In Lucas v. South Carolina Coastal Council, the Supreme Court held that, when a regulation has deprived a landowner of all economically beneficial use, a threshold issue in determining whether compensation is due is whether the landownerâs rights of ownership are confined by the limitations on the use of land which âinhere in the title itself.â For land that may fall within the public trust doctrine, Lucasâs threshold determination has significant consequences. Because the public trust doctrine is a âbackground principle,â buyers and sellers of real property may not be able to claim full title, and should be cognizant of the potential application of the doctrine to their land. Further, state and local regulatory bodies should strategically employ the public trust doctrine in environmental protection regulation. Finally, the public trust doctrineâs role in a takings analysis suggests that property rights are perhaps more communal than generally acknowledged, and reveals that it may make sense to evaluate property rights from a community-based perspective
Genotoxicity of nitroso compounds and sodium dichromate in a model combining organ cultures of human nasal epithelia and the comet assay
Genotoxic effects of xenobiotics are a possible step in tumor initiation in the mucosa of the upper aerodigestive tract. Using the comet assay, detecting genotoxicity in human tissue has been restricted to single incubations in vitro, but in vivo most xenobiotics harm their target in a repetitive or chronic manner. Therefore, we propose a model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures. Samples of human inferior nasal turbinate mucosa (n = 25) were cultured according to a modified version of a technique originally described by Steinsvag. On day 1 fresh samples and on days 7, 9 and 11 organ cultures were incubated with N-nitrosodiethylamine (NDEA), sodium dichromate (Na2Cr2O7) and N'-methyl-N-nitro-N-nitrosoguanidine(MNNG). Mucosa samples and organ cultures, respectively, underwent a modified comet assay on days 1, 7 and 11. Genotoxicity could be shown for NDEA, Na2Cr2O7 and MNNG on days 1, 7 and 11. Duration of tissue culture and repetitive incubations did not significantly influence the results for NDEA. Nevertheless, Na2Cr2O7 and MNNG caused higher genotoxic effects on cultures subjected to the comet assay on day 11. This model may help to assess genotoxic hazards posed by environ mental pollutants that have a cumulative character in repetitive or chronic exposure in vivo. Copyright (C) 2001 S. Karger AG, Basel
High density NV sensing surface created via He^(+) ion implantation of (12)^C diamond
We present a promising method for creating high-density ensembles of
nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity
magnetic imaging. Practically, narrow spin-resonance linewidths substantially
reduce the optical and RF power requirements for ensemble-based sensing. The
method combines isotope purified diamond growth, in situ nitrogen doping, and
helium ion implantation to realize a 100 nm-thick sensing surface. The obtained
10^(17) cm^(-3) nitrogen-vacancy density is only a factor of 10 less than the
highest densities reported to date, with an observed spin resonance linewidth
over 10 times more narrow. The 200 kHz linewidth is most likely limited by
dipolar broadening indicating even further reduction of the linewidth is
desirable and possible.Comment: 5 pages including references. 3 figure
Australia and New Zealand applied linguistics (ANZAL): Taking stock
This paper reviews some emerging trends in applied linguistics in both Australia and New Zealand. It sketches the current scene of (selected) postgraduate applied linguistics programs in higher education and considers how various university programs define applied linguistics through the classes (titles) they have postgraduate students complete to be awarded a degree. Evidence of program requirements and topics reveal not only what applied linguistics generally entails, but offers insights into how applied linguistics is defined and practiced. Additionally, some of the salient research topics (titles) being published in the journals from the two countries' applied linguistics associations are sketched
Probing Noise in Flux Qubits via Macroscopic Resonant Tunneling
Macroscopic resonant tunneling between the two lowest lying states of a
bistable RF-SQUID is used to characterize noise in a flux qubit. Measurements
of the incoherent decay rate as a function of flux bias revealed a Gaussian
shaped profile that is not peaked at the resonance point, but is shifted to a
bias at which the initial well is higher than the target well. The r.m.s.
amplitude of the noise, which is proportional to the decoherence rate 1/T_2^*,
was observed to be weakly dependent on temperature below 70 mK. Analysis of
these results indicates that the dominant source of low frequency (1/f) flux
noise in this device is a quantum mechanical environment in thermal
equilibrium.Comment: 4 pages 4 figure
Conduction channels of superconducting quantum point contacts
Atomic quantum point contacts accommodate a small number of conduction
channels. Their number N and transmission coefficients {T_n} can be determined
by analyzing the subgap structure due to multiple Andreev reflections in the
current-voltage (IV) characteristics in the superconducting state. With the
help of mechanically controllable break-junctions we have produced Al contacts
consisting of a small number of atoms. In the smallest stable contacts, usually
three channels contribute to the transport. We show here that the channel
ensemble {T_n} of few atom contacts remains unchanged up to temperatures and
magnetic fields approaching the critical temperature and the critical field,
respectively, giving experimental evidence for the prediction that the
conduction channels are the same in the normal and in the superconducting
state.Comment: 8 pages, 5 .eps figures. To be published in Physica B 22
Observation of Andreev Reflection Enhanced Shot Noise
We have experimentally investigated the quasiparticle shot noise in
NbN/MgO/NbN superconductor - insulator - superconductor tunnel junctions. The
observed shot noise is significantly larger than theoretically expected. We
attribute this to the occurrence of multiple Andreev reflection processes in
pinholes present in the MgO barrier. This mechanism causes the current to flow
in large charge quanta (Andreev clusters), with a voltage dependent average
value of m = 1+ 2 Delta/eV times the electron charge. Because of this charge
enhancement effect, the shot noise is increased by the factor m.Comment: 4 pages, 5 figures include
Universal distribution of transparencies in highly conductive Nb/AlO/Nb junctions
We report the observation of the universal distribution of transparencies,
predicted by Schep and Bauer [Phys. Rev. Lett. {\bf 78}, 3015 (1997)] for dirty
sharp interfaces, in uniform Nb/AlO/Nb junctions with high specific
conductance ( Ohmcm). Experiments used the BCS density of
states in superconducting niobium for transparency distribution probing.
Experimental results for both the dc curves at magnetic-field-suppressed
supercurrent and the Josephson critical current in zero magnetic field coincide
remarkably well with calculations based on the multimode theory of multiple
Andreev reflections and the Schep-Bauer distribution.Comment: 4 pages, 4 figures, references adde
Mesoscopic proximity effect in double barrier Superconductor/Normal Metal junctions
We report transport measurements down to T=60mK of SININ and SNIN structures
in the diffusive limit. We fabricated Al-AlOx/Cu/AlOx/Cu (SININ) and
Al/Cu/AlOx/Cu (SNIN) vertical junctions. For the first time, a zero bias
anomaly was observed in a metallic SININ structure. We attribute this peak of
conductance to coherent multi-reflections of electrons between the two tunnel
barriers. This conductance maximum is quantitatively fitted by the relevant
theory of mesoscopic SININ structures. When the barrier at the SN interface is
removed (SNIN structure), we observe a peak of conductance at finite voltage
accompagnied by an excess of sub-gap conductance.Comment: 4 pages, 4 figures, editorially approved for publication in Phys.
Rev. B Rapid Com
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