686 research outputs found
The U.S. Deep Seabed Mining Regulations: The Legal Basis for an Alternative Regime
This Article examines the jurisdictional limitations established by United States deep seabed mining legislation. The author argues that by incorporating the ambiguous jurisdictional language of earlier international agreements into domestic legislation, the drafters have missed the opportunity to expand the United States\u27 unrestricted access to deep seabed hard minerals. The author proposes that the promotion of continued development of deep seabed mining technology can be achieved through the legislative enactment of an Exclusive Economic Zone, which would place portions of the deep seabed, that would have otherwise have been excluded, under national jurisdiction
Transport in a three-terminal graphene quantum dot in the multi-level regime
We investigate transport in a three-terminal graphene quantum dot. All nine
elements of the conductance matrix have been independently measured. In the
Coulomb blockade regime accurate measurements of individual conductance
resonances reveal slightly different resonance energies depending on which pair
of leads is used for probing. Rapid changes in the tunneling coupling between
the leads and the dot due to localized states in the constrictions has been
excluded by tuning the difference in resonance energies using in-plane gates
which couple preferentially to individual constrictions. The interpretation of
the different resonance energies is then based on the presence of a number of
levels in the dot with an energy spacing of the order of the measurement
temperature. In this multi-level transport regime the three-terminal device
offers the opportunity to sense if the individual levels couple with different
strengths to the different leads. This in turn gives qualitative insight into
the spatial profile of the corresponding quantum dot wave functions.Comment: 12 pages, 6 figure
Do Stress Trajectories Predict Mortality in Older Men? Longitudinal Findings from the VA Normative Aging Study
We examined long-term patterns of stressful life events (SLE) and their impact on mortality contrasting two theoretical models: allostatic load (linear relationship) and hormesis (inverted U relationship) in 1443 NAS men (aged 41–87 in 1985; M = 60.30, SD = 7.3) with at least two reports of SLEs over 18 years (total observations = 7,634). Using a zero-inflated Poisson growth mixture model, we identified four patterns of SLE trajectories, three showing linear decreases over time with low, medium, and high intercepts, respectively, and one an inverted U, peaking at age 70. Repeating the analysis omitting two health-related SLEs yielded only the first three linear patterns. Compared to the low-stress group, both the moderate and the high-stress groups showed excess mortality, controlling for demographics and health behavior habits, HRs = 1.42 and 1.37, ps <.01 and <.05. The relationship between stress trajectories and mortality was complex and not easily explained by either theoretical model
MapOptics: A light-weight, cross-platform visualisation tool for optical mapping alignment
Availability and implementation:
MapOptics is implemented in Java 1.8 and released under an MIT licence. MapOptics can be downloaded from https://github.com/FadyMohareb/mapoptics and run on any standard desktop computer equipped with a Java Virtual Machine (JVM).
Supplementary data are available at Bioinformatics online.Bionano optical mapping is a technology that can assist in the final stages of genome assembly by lengthening and ordering scaffolds in a draft assembly by aligning the assembly to a genomic map. However, currently, tools for visualisation are limited to use on a Windows operating system or are developed initially for visualising large-scale structural variation. MapOptics is a lightweight cross-platform tool that enables the user to visualise and interact with the alignment of Bionano optical mapping data and can be used for in depth exploration of hybrid scaffolding alignments. It provides a fast, simple alternative to the large optical mapping analysis programs currently available for this area of research
PIRS: Python-based framework for coupled MC-TH reactor calculations
We develop a set of Python packages to provide a modern programming interface to codes used for analysis of nuclear reactors. Currently implemented interfaces to the Monte Carlo (MC) neutronics code MCNP and thermo-hydraulic (TH) code SCF allow efficient description of calculation models and provide a framework for coupled calculations. In this paper we illustrate how these interfaces can be used to describe a pin model, and report results of coupled MCNP-SCF calculations performed for a PWR fuel assembly, organized by means of the interfaces
Incidence of Ovine Progressive Pneumonia in the North Dakota State University Sheep Flocks, Determined by Agar-gel Immunodiffusion
In 1968, the causative agent of OPP, ovine progressive pneumonia virus (PPV) or Lunger's Disease was first isolated in the United States. A serological test, agar-gel imuno-diffusion (AGID) was applied for the detection of precipitating antibodies aginst PPV in sheep sera (colostrum-whey) against PPV is indicative of infection. But, antibodies are evidently play no part in fighting infection. By the time taht antibodies are produced, the virus is residing intracellularly and is unattainable to antibodies. The article gives a description of the symptoms and effects of the disease. The objective of this study was to characterize the extent of OPP in a naturally infected sheep flock by AGID, to determine whether differences in age or breed of the sheep influences the susceptibility to OPP and to attempt to establish an OPP-free from an infected source flock. The incidence of ovine progressive pneumonia by breed and age in a naturally infected flock was determined. An ovine progressive pneumonia free flock was established five years prior
Coherent Electron-Phonon Coupling in Tailored Quantum Systems
The coupling between a two-level system and its environment leads to
decoherence. Within the context of coherent manipulation of electronic or
quasiparticle states in nanostructures, it is crucial to understand the sources
of decoherence. Here, we study the effect of electron-phonon coupling in a
graphene and an InAs nanowire double quantum dot. Our measurements reveal
oscillations of the double quantum dot current periodic in energy detuning
between the two levels. These periodic peaks are more pronounced in the
nanowire than in graphene, and disappear when the temperature is increased. We
attribute the oscillations to an interference effect between two alternative
inelastic decay paths involving acoustic phonons present in these materials.
This interpretation predicts the oscillations to wash out when temperature is
increased, as observed experimentally.Comment: 11 pages, 4 figure
Aharonov-Bohm-Coulomb Problem in Graphene Ring
We study the Aharonov-Bohm-Coulomb problem in a graphene ring. We
investigate, in particular, the effects of a Coulomb type potential of the form
on the energy spectrum of Dirac electrons in the graphene ring in two
different ways: one for the scalar coupling and the other for the vector
coupling. It is found that, since the potential in the scalar coupling breaks
the time-reversal symmetry between the two valleys as well as the effective
time-reversal symmetry in a single valley, the energy spectrum of one valley is
separated from that of the other valley, demonstrating a valley polarization.
In the vector coupling, however, the potential does not break either of the two
symmetries and its effect appears only as an additive constant to the spectrum
of Aharonov-Bohm potential. The corresponding persistent currents, the
observable quantities of the symmetry-breaking energy spectra, are shown to be
asymmetric about zero magnetic flux in the scalar coupling, while symmetric in
the vector coupling.Comment: 20 pages, 12 figures (V2) 18 pages, accepted in JPHYS
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