9,717 research outputs found
Death of a 78-Year Old Woman
This official opinion of the District Attorney of Milwaukee County, E. Michael McCann, represents a synthesis of sound jurisprudence and sound medical-ethical reasoning in a difficult medical situation
Screening in gated bilayer graphene via variational calculus
We analyze the response of bilayer graphene to an external transverse
electric field using a variational method. A previous attempt to do so in a
recent paper by Falkovsky [Phys. Rev. B 80, 113413 (2009)] is shown to be
flawed. Our calculation reaffirms the original results obtained by one of us
[E. McCann, Phys. Rev. B 74, 161403(R) (2006)] by a different method. Finally,
we generalize these original results to describe a dual-gated bilayer graphene
device.Comment: 4 pages, 1 figur
Radiation environment and shielding for early manned Mars missions
The problem of shielding a crew during early manned Mars missions is discussed. Requirements for shielding are presented in the context of current astronaut exposure limits, natural ionizing radiation sources, and shielding inherent in a particular Mars vehicle configuration. An estimated range for shielding weight is presented based on the worst solar flare dose, mission duration, and inherent vehicle shielding
Uniform Density Theorem for the Hubbard Model
A general class of hopping models on a finite bipartite lattice is
considered, including the Hubbard model and the Falicov-Kimball model. For the
half-filled band, the single-particle density matrix \uprho (x,y) in the
ground state and in the canonical and grand canonical ensembles is shown to be
constant on the diagonal , and to vanish if and if and
are on the same sublattice. For free electron hopping models, it is shown in
addition that there are no correlations between sites of the same sublattice in
any higher order density matrix. Physical implications are discussed.Comment: 15 pages, plaintex, EHLMLRJM-22/Feb/9
Forward velocity effects on fan noise and the influence of inlet aeroacoustic design as measured in the NASA Ames 40 x 80 foot wind tunnel
The inlet radiated noise of a turbofan engine was studied. The principal research objectives were to characterize or suppress such noise with particular regard to its tonal characteristics. The major portion of this research was conducted by using ground-based static testing without simulation of aircraft forward speed or aircraft installation-related aeroacoustic effects
Gate-tunable bandgap in bilayer graphene
The tight-binding model of bilayer graphene is used to find the gap between
the conduction and valence bands, as a function of both the gate voltage and as
the doping by donors or acceptors. The total Hartree energy is minimized and
the equation for the gap is obtained. This equation for the ratio of the gap to
the chemical potential is determined only by the screening constant. Thus the
gap is strictly proportional to the gate voltage or the carrier concentration
in the absence of donors or acceptors. In the opposite case, where the donors
or acceptors are present, the gap demonstrates the asymmetrical behavior on the
electron and hole sides of the gate bias. A comparison with experimental data
obtained by Kuzmenko et al demonstrates the good agreement.Comment: 6 pages, 5 figure
Standing: Who Speaks for the Environment?
Standing: Who Speaks for the Environment
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