26,895 research outputs found
The meteorology of Mars and Venus Final report
Meteorology of Mars and Venu
The Physics Inside Topological Quantum Field Theories
We show that the equations of motion defined over a specific field space are
realizable as operator conditions in the physical sector of a generalized Floer
theory defined over that field space. The ghosts associated with such a
construction are found not to be dynamical. This construction is applied to
gravity on a four dimensional manifold, ; whereupon, we obtain Einstein's
equations via surgery, along , in a five-dimensional topological quantum
field theory.Comment: LaTeX, 7 page
Topology, Quantum Gravity and Particle Physics
It is argued that quantum gravity has an interpretation as a topological
field theory provided a certain constraint from the path intergral measure is
respected. The constraint forces us to couple gauge and matter fields to
gravity for space - time dimensions different from 3. We then discuss possible
models which may be relevant to our universe.Comment: 18 pages, LaTeX. Replaced version corrects typos and has additional
reference
Quantum interference and sub-Poissonian statistics for time-modulated driven dissipative nonlinear oscillator
We show that quantum-interference phenomena can be realized for the
dissipative nonlinear systems exhibiting hysteresis-cycle behavior and quantum
chaos. Such results are obtained for a driven dissipative nonlinear oscillator
with time-dependent parameters and take place for the regimes of long time
intervals exceeding dissipation time and for macroscopic levels of oscillatory
excitation numbers. Two schemas of time modulation: (i) periodic variation of
the strength of the {\chi}(3) nonlinearity; (ii) periodic modulation of the
amplitude of the driving force, are considered. These effects are obtained
within the framework of phase-space quantum distributions. It is demonstrated
that the Wigner functions of oscillatory mode in both bistable and chaotic
regimes acquire negative values and interference patterns in parts of
phase-space due to appropriately time-modulation of the oscillatory nonlinear
dynamics. It is also shown that the time-modulation of the oscillatory
parameters essentially improves the degree of sub-Poissonian statistics of
excitation numbers
The effect of humidity on engine power at altitude
From tests made in the altitude chamber of the Bureau of Standards, it was found that the effect of humidity on engine power is the same at altitudes up to 25,000 feet as at sea level. Earlier tests on automotive engines, made under sea-level conditions, showed that water vapor acts as an inert diluent, reducing engine power in proportion to the amount of vapor present. By combining the effects of atmospheric pressure, temperature, and humidity, it is shown that the indicated power obtainable from an engine is proportional to its mass rate of consumption of oxygen. This has led the National Advisory Committee for Aeronautics to adopt a standard basis for the correction of engine performance, in which the effect of humidity is included
Measuring and tracking vitamin B12: a review of current methods with a focus on optical spectroscopy
Published online: 13 Sep 2016Vitamin B12 deficiency has been associated with an increased risk of cognitive decline. This literature review explores the current methods available for measuring vitamin B12 in human blood, serum, and urine, and the need for a globally accepted reference range for vitamin B12. We present optical spectroscopy, including chemiluminescence measurements, absorption and fluorescence spectroscopy, surface plasmon resonance, and Raman spectroscopy, as a promising technique for detection and tracking of vitamin B12. Considerations for future research are highlighted, including enhancing the sensitivity of optical spectroscopy and prospective pathways to improve the reproducibility, selectivity, and speed of vitamin B12 detection.Georgios Tsiminis, Erik P. Schartner, Joanna L. Brooks, and Mark R. Hutchinso
Dynamical Dark Matter: II. An Explicit Model
In a recent paper (arXiv:1106.4546), we introduced "dynamical dark matter," a
new framework for dark-matter physics, and outlined its underlying theoretical
principles and phenomenological possibilities. Unlike most traditional
approaches to the dark-matter problem which hypothesize the existence of one or
more stable dark-matter particles, our dynamical dark-matter framework is
characterized by the fact that the requirement of stability is replaced by a
delicate balancing between cosmological abundances and lifetimes across a vast
ensemble of individual dark-matter components. This setup therefore
collectively produces a time-varying cosmological dark-matter abundance, and
the different dark-matter components can interact and decay throughout the
current epoch. While the goal of our previous paper was to introduce the broad
theoretical aspects of this framework, the purpose of the current paper is to
provide an explicit model of dynamical dark matter and demonstrate that this
model satisfies all collider, astrophysical, and cosmological constraints. The
results of this paper therefore constitute an "existence proof" of the
phenomenological viability of our overall dynamical dark-matter framework, and
demonstrate that dynamical dark matter is indeed a viable alternative to the
traditional paradigm of dark-matter physics. Dynamical dark matter must
therefore be considered alongside other approaches to the dark-matter problem,
particularly in scenarios involving large extra dimensions or string theory in
which there exist large numbers of particles which are neutral under
Standard-Model symmetries.Comment: 45 pages, LaTeX, 10 figures. Replaced to match published versio
On-disc observations of flux rope formation prior to its eruption
Coronal mass ejections (CMEs) are one of the primary manifestations of solar activity and can drive severe space weather effects. Therefore, it is vital to work towards being able to predict their occurrence. However, many aspects of CME formation and eruption remain unclear, including whether magnetic flux ropes are present before the onset of eruption and the key mechanisms that cause CMEs to occur. In this work, the pre-eruptive coronal configuration of an active region that produced an interplanetary CME with a clear magnetic flux rope structure at 1 AU is studied. A forward-S sigmoid appears in extreme-ultraviolet (EUV) data two hours before the onset of the eruption (SOL2012-06-14), which is interpreted as a signature of a right-handed flux rope that formed prior to the eruption. Flare ribbons and EUV dimmings are used to infer the locations of the flux rope footpoints. These locations, together with observations of the global magnetic flux distribution, indicate that an interaction between newly emerged magnetic flux and pre-existing sunspot field in the days prior to the eruption may have enabled the coronal flux rope to form via tether-cutting-like reconnection. Composition analysis suggests that the flux rope had a coronal plasma composition, supporting our interpretation that the flux rope formed via magnetic reconnection in the corona. Once formed, the flux rope remained stable for two hours before erupting as a CME
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