34,370 research outputs found
Using Pinch Gloves(TM) for both Natural and Abstract Interaction Techniques in Virtual Environments
Usable three-dimensional (3D) interaction techniques are difficult to design, implement, and evaluate. One reason for this is a poor understanding of the advantages and disadvantages of the wide range of 3D input devices, and of the mapping between input devices and interaction techniques. We present an analysis of Pinch Glovesā¢ and their use as input devices for virtual environments (VEs). We have developed a number of novel and usable interaction techniques for VEs using the gloves, including a menu system, a technique for text input, and a two-handed navigation technique. User studies have indicated the usability and utility of these techniques
Design integration and noise studies for jet STOL aircraft. Task 7C: Augmentor wing cruise blowing valveless system. Volume 1: Static testing of augmentor noise and performance
Static performance and acoustic tests were conducted on a two-dimensional one-third-scale augmentor flap model that simulated a cruise blowing augmentor system designed for a scale augmentor flap model that simulated a cruise blowing augmentor, which offers a degree of 150-passenger STOL airplane. The cruise blowing augmentor, which offers a degree of simplicity by requiring no fan air diverter valves, was simulated by fitting existing lobe suppressor nozzles with new nozzle fairings. Flow turning performance of the cruise blowing augmentor was measured through a large range of flap deflection angles. The noise suppression characteristics of a multilayer acoustic lining installed in the augmentor were also measured
Kinetics of viral self-assembly: the role of ss RNA antenna
A big class of viruses self-assemble from a large number of identical capsid
proteins with long flexible N-terminal tails and ss RNA. We study the role of
the strong Coulomb interaction of positive N-terminal tails with ss RNA in the
kinetics of the in vitro virus self-assembly. Capsid proteins stick to
unassembled chain of ss RNA (which we call "antenna") and slide on it towards
the assembly site. We show that at excess of capsid proteins such
one-dimensional diffusion accelerates self-assembly more than ten times. On the
other hand at excess of ss RNA, antenna slows self-assembly down. Several
experiments are proposed to verify the role of ss RNA antenna.Comment: 4 pages, 3 figures, several experiments are proposed, a new idea of
experiment is adde
Flux Penetration in Superconducting Strip with Edge-Indentation
The flux penetration near a semicircular indentation at the edge of a thin
superconducting strip placed in a transverse magnetic field is investigated.
The flux front distortion due to the indentation is calculated numerically by
solving the Maxwell equations with a highly nonlinear law. We find that
the excess penetration, , can be significantly ( 50%) larger than
the indentation radius , in contrast to a bulk supercondutor in the
critical state where . It is also shown that the flux creep tends
to smoothen the flux front, i.e. reduce . The results are in very good
agreement with magneto-optical studies of flux penetration into an
YBaCuO film having an edge defect.Comment: 5 pages, 7 figure
Existence of multi-site intrinsic localized modes in one-dimensional Debye crystals
The existence of highly localized multi-site oscillatory structures (discrete
multibreathers) in a nonlinear Klein-Gordon chain which is characterized by an
inverse dispersion law is proven and their linear stability is investigated.
The results are applied in the description of vertical (transverse, off-plane)
dust grain motion in dusty plasma crystals, by taking into account the lattice
discreteness and the sheath electric and/or magnetic field nonlinearity.
Explicit values from experimental plasma discharge experiments are considered.
The possibility for the occurrence of multibreathers associated with vertical
charged dust grain motion in strongly-coupled dusty plasmas (dust crystals) is
thus established. From a fundamental point of view, this study aims at
providing a first rigorous investigation of the existence of intrinsic
localized modes in Debye crystals and/or dusty plasma crystals and, in fact,
suggesting those lattices as model systems for the study of fundamental crystal
properties.Comment: 12 pages, 8 figures, revtex forma
On Properties of Boundaries and Electron Conductivity in Mesoscopic Polycrystalline Silicon Films for Memory Devices
We present the results of molecular dynamics modeling on the structural
properties of grain boundaries (GB) in thin polycrystalline films. The
transition from crystalline boundaries with low mismatch angle to amorphous
boundaries is investigated. It is shown that the structures of the GBs satisfy
a thermodynamical criterion. The potential energy of silicon atoms is closely
related with a geometrical quantity -- tetragonality of their coordination with
their nearest neighbors. A crossover of the length of localization is observed.
To analyze the crossover of the length of localization of the single-electron
states and properties of conductance of the thin polycrystalline film at low
temperature, we use a two-dimensional Anderson localization model, with the
random one-site electron charging energy for a single grain (dot), random
non-diagonal matrix elements, and random number of connections between the
neighboring grains. The results on the crossover behavior of localization
length of the single-electron states and characteristic properties of
conductance are presented in the region of parameters where the transition from
an insulator to a conductor regimes takes place.Comment: 8 pages, 3 figure
On the Validity of the Tomonaga Luttinger Liquid Relations for the One-dimensional Holstein Model
For the one-dimensional Holstein model, we show that the relations among the
scaling exponents of various correlation functions of the Tomonaga Luttinger
liquid (LL), while valid in the thermodynamic limit, are significantly modified
by finite size corrections. We obtain analytical expressions for these
corrections and find that they decrease very slowly with increasing system
size. The interpretation of numerical data on finite size lattices in terms of
LL theory must therefore take these corrections into account. As an important
example, we re-examine the proposed metallic phase of the zero-temperature,
half-filled one-dimensional Holstein model without employing the LL relations.
In particular, using quantum Monte Carlo calculations, we study the competition
between the singlet pairing and charge ordering. Our results do not support the
existence of a dominant singlet pairing state.Comment: 7 page
An extreme paucity of second population AGB stars in the normal globular cluster M4
Galactic Globular clusters (GCs) are now known to harbour multiple stellar
populations, which are chemically distinct in many light element abundances. It
is becoming increasingly clear that asymptotic giant branch (AGB) stars in GCs
show different abundance distributions in light elements compared to those in
the red giant branch (RGB) and other phases, skewing toward more primordial,
field-star-like abundances, which we refer to as subpopulation one (SP1). As
part of a larger program targeting giants in GCs, we obtained high-resolution
spectra for a sample of 106 RGB and 15 AGB stars in Messier 4 (NGC 6121) using
the 2dF+HERMES facility on the Anglo-Australian Telescope. In this Letter we
report an extreme paucity of AGB stars with [Na/O] > -0.17 in M4, which
contrasts with the RGB that has abundances up to [Na/O] =0.55. The AGB
abundance distribution is consistent with all AGB stars being from SP1. This
result appears to imply that all subpopulation two stars (SP2; Na-rich, O-poor)
avoid the AGB phase. This is an unexpected result given M4's horizontal branch
morphology -- it does not have an extended blue horizontal branch. This is the
first abundance study to be performed utilising the HERMES spectrograph.Comment: 5 pages, 2 figures, 4 tables (full Table 1 online). Accepted for
publication in MNRAS Letter
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