6,564 research outputs found
PT-symmetric deformations of integrable models
We review recent results on new physical models constructed as PT-symmetrical
deformations or extensions of different types of integrable models. We present
non-Hermitian versions of quantum spin chains, multi-particle systems of
Calogero-Moser-Sutherland type and non-linear integrable field equations of
Korteweg-de-Vries type. The quantum spin chain discussed is related to the
first example in the series of the non-unitary models of minimal conformal
field theories. For the Calogero-Moser-Sutherland models we provide three
alternative deformations: A complex extension for models related to all types
of Coxeter/Weyl groups; models describing the evolution of poles in constrained
real valued field equations of non linear integrable systems and genuine
deformations based on antilinearly invariant deformed root systems.
Deformations of complex nonlinear integrable field equations of KdV-type are
studied with regard to different kinds of PT-symmetrical scenarios. A reduction
to simple complex quantum mechanical models currently under discussion is
presented.Comment: 21 pages, 3 figure
Moments of Dirichlet splines and their applications to hypergeometric functions
Dirichlet averages of multivariate functions are employed for a derivation of
basic recurrence formulas for the moments of multivariate Dirichlet splines. An
algorithm for computing the moments of multivariate simplex splines is
presented. Applications to hypergeometric functions of several variables are
discussed
Building California's Future
Current conditions in infrastructure planning, budgeting and financing in the state of Californi
e-Health and the Elderly: How Seniors Use the Internet for Health
Presents findings from a survey that examines how seniors use the Internet to look for information on doctors, research prescription drugs, find providers, manage their weight, follow health policy news, or look up the latest cancer treatments
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Purification and electron cryomicroscopy of coronavirus particles.
Intact, enveloped coronavirus particles vary widely in size and contour, and are thus refractory to study by traditional structural means such as X-ray crystallography. Electron microscopy (EM) overcomes some problems associated with particle variability and has been an important tool for investigating coronavirus ultrastructure. However, EM sample preparation requires that the specimen be dried onto a carbon support film before imaging, collapsing internal particle structure in the case of coronaviruses. Moreover, conventional EM achieves image contrast by immersing the specimen briefly in heavy-metal-containing stain, which reveals some features while obscuring others. Electron cryomicroscopy (cryo-EM) instead employs a porous support film, to which the specimen is adsorbed and flash-frozen. Specimens preserved in vitreous ice over holes in the support film can then be imaged without additional staining. Cryo-EM, coupled with single-particle image analysis techniques, makes it possible to examine the size, structure and arrangement of coronavirus structural components in fully hydrated, native virions. Two virus purification procedures are described
A flight investigation of a 4D area navigation system concept for STOL aircraft in the terminal area
A digital avionics system referred to as STOLAND was test flown in the NASA CV-340 aircraft to obtain performance data for time controlled guidance in the manual flight director mode. The advanced system components installed in the cockpit included an electronic attitude director indicator and an electronic multifunction display. Navigation guidance and control computations were performed on a digital computer. A detailed 4D area navigation systems description is given. The pilot/system interface and systems operation and performance are also described. Approach flightpaths were flown which included a 180 deg turn and a 1-min, 5 deg straight-in approach to 30 m altitude, at which point go-around was initiated. Results are presented for 19 approaches
Weak values of electron spin in a double quantum dot
We propose a protocol for a controlled experiment to measure a weak value of
the electron's spin in a solid state device. The weak value is obtained by a
two step procedure -- weak measurement followed by a strong one
(post-selection), where the outcome of the first measurement is kept provided a
second post-selected outcome occurs. The set-up consists of a double quantum
dot and a weakly coupled quantum point contact to be used as a detector.
Anomalously large values of the spin of a two electron system are predicted, as
well as negative values of the total spin. We also show how to incorporate the
adverse effect of decoherence into this procedure.Comment: 4+ pages, 3 figures, final published versio
Coordinating Growth Management Through Consensus-Building: Incentives and the Generation of Social, Intellectual and Political Capital
Radiant heating concept efficient for light-transmitting windows
Single-pane, uncoated windows absorb infrared rays and transmit visible and near-visible wavelengths. Two opposed rod heaters direct infrared rays at the pane, reflectors aid in this heating which prevents condensation. These windows are useful for telescopes and cameras for oceanographic and related studies
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