10,121 research outputs found
Gerasim\u27s Compassion in Tolstoy\u27s The Death of Ivan Ilyich
In this article on Gerasim, from Tolstoy\u27s The Death of Ivan Ilyich, David Urban examines this character\u27s example of compassion in the face of his master\u27s terminal illness. Urban suggests that all humans would do well to follow Gerasim\u27s example, especially in light of everyone\u27s mortality
Prague's Emission Fourier Transform Microwave Spectrometer - Design and Preliminary Results
The design, performance and operation of the high resolution microwave spectrometer are described. The spectrometer is based on the Fabry-Perot resonator supplemented by a pulsed supersonic nozzle for adiabatic cooling of the sample. The spectrometer’s high sensitivity and resolution are demonstrated by several examples
Automated Reasoning and Presentation Support for Formalizing Mathematics in Mizar
This paper presents a combination of several automated reasoning and proof
presentation tools with the Mizar system for formalization of mathematics. The
combination forms an online service called MizAR, similar to the SystemOnTPTP
service for first-order automated reasoning. The main differences to
SystemOnTPTP are the use of the Mizar language that is oriented towards human
mathematicians (rather than the pure first-order logic used in SystemOnTPTP),
and setting the service in the context of the large Mizar Mathematical Library
of previous theorems,definitions, and proofs (rather than the isolated problems
that are solved in SystemOnTPTP). These differences poses new challenges and
new opportunities for automated reasoning and for proof presentation tools.
This paper describes the overall structure of MizAR, and presents the automated
reasoning systems and proof presentation tools that are combined to make MizAR
a useful mathematical service.Comment: To appear in 10th International Conference on. Artificial
Intelligence and Symbolic Computation AISC 201
Lobster Eye X-ray optics for astrophysics: Recent status
X-ray optics in Lobster Eye arrangement represent promising complementary device to narrow field X-ray optics in common use. We present briefly recent status of design, developments, and tests of X-ray optics including Lobster Eye modules developed and tested within recent space project
Engineering study to determine feasible methods of simulating planetary albedo and radiation effects upon the thermal balance of spacecraft Final report
Planetary radiation and albedo effects on thermal balance of spacecraft orbiting Mars and Venu
Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry
We report the use of an atomic magnetometer based on nonlinear
magneto-optical rotation with frequency modulated light (FM NMOR) to detect
nuclear magnetization of xenon gas. The magnetization of a
spin-exchange-polarized xenon sample (cm at a pressure of bar,
natural isotopic abundance, polarization 1%), prepared remotely to the
detection apparatus, is measured with an atomic sensor (which is insensitive to
the leading field of 0.45 G applied to the sample; an independent bias field at
the sensor is G). An average magnetic field of nG induced by
the xenon sample on the 10-cm diameter atomic sensor is detected with
signal-to-noise ratio , limited by residual noise in the magnetic
environment. The possibility of using modern atomic magnetometers as detectors
of nuclear magnetic resonance and in magnetic resonance imaging is discussed.
Atomic magnetometers appear to be ideally suited for emerging low-field and
remote-detection magnetic resonance applications.Comment: 4 pages, 4 figure
An ultraweak space-Time variational formulation for the wave equation: Analysis and efficient numerical solution
We introduce an ultraweak space-time variational formulation for the wave equation, prove its well-posedness (even in the case of minimal regularity) and optimal inf-sup stability. Then, we introduce a tensor product-style space-time Petrov–Galerkin discretization with optimal discrete inf-sup stability, obtained by a non-standard definition of the trial space. As a consequence, the numerical approximation error is equal to the residual, which is particularly useful for a posteriori error estimation.
For the arising discrete linear systems in space and time, we introduce efficient numerical solvers that appropriately exploit the equation structure, either at the preconditioning level or in the approximation
phase by using a tailored Galerkin projection. This Galerkin method shows competitive behavior concerning wall-clock time, accuracy and memory as compared with a standard time-stepping method in
particular in low regularity cases. Numerical experiments with a 3D (in space) wave equation illustrate our findings
Geometric phases of scattering states in a ring geometry: adiabatic pumping in mesoscopic devices
Geometric phases of scattering states in a ring geometry are studied based on
a variant of the adiabatic theorem. Three time scales, i.e., the adiabatic
period, the system time and the dwell time, associated with adiabatic
scattering in a ring geometry plays a crucial role in determining geometric
phases, in contrast to only two time scales, i.e., the adiabatic period and the
dwell time, in an open system. We derive a formula connecting the gauge
invariant geometric phases acquired by time-reversed scattering states and the
circulating (pumping) current. A numerical calculation shows that the effect of
the geometric phases is observable in a nanoscale electronic device.Comment: 9 pages, 3 figure
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