204 research outputs found
Water metabolism regulating mechanisms in hypokinesia
The range of daily fluctuations of the proportion of the amount of consumed water and its content in the body was evaluated by means of a water metabolism regulation factor. This index constitutes a relative measure of fluctuations of the constant of tritium water elimination from the body per 24 hours. It is established that under conditions of long term hypokinesia regulation of water metabolism is disturbed both in humans and in animals. Still more marked changes are observed 2 to 3 weeks after restoration of motor activity. The shifts noted are evidence of general biological regularity of disturbance of regulation systems in long term restriction of motor activity and in the early restoration period
Changes of some blood indices and myocardial electrolyte content during hypokinesia
Using special hypokinetic cages, the volume changes of circulating blood, its hematocrit and protein content, volume ratios between extra- and intracellular liquids in the body, as well as electrolyte content in the blood and myocardium during hypokinesia were investigated experimentally in rabbits
Fundamental Gates for a Strongly Correlated Two-Electron Quantum Ring
We demonstrate that conditional as well as unconditional basic operations
which are prerequisite for universal quantum gates can be performed with almost
100% fidelity within a strongly interacting two-electron quantum ring. Both
sets of operations are based on a quantum control algorithm that optimizes a
driving electromagnetic pulse for a given quantum gate. The demonstrated
transitions occur on a time scale much shorter than typical decoherence times
of the system.Comment: 4 pages, 4 figures, copyright 2010 The American Physical Societ
Mechanisms of water-salt metabolism disturbances in dogs subjected to six month hypokinesia
Water-salt metabolism in dogs during prolonged restricted motor activity (hypokinesia) was investigated. It was found that hydration occurred and fluid was redistributed between the extra- and intra-cellular sectors. Also, electrolyte excretion rose, and magnetism and calcium metabolism changed significantly. It is concluded that the forces caused by muscle strain proper (which was decreased under conditions of hypokinesia) influence the state of bone metabolism
Experimental investigation of the role of thyrocalcitonin in the prophylaxis of disturbances in the water-salt and mineral metabolism during a 30-day hypokinesia
The effect of thyrocalcitonin (TCT) injections on the metabolism of water and electrolytes in free-moving and immobilized chinchilla hares is described. Calcium excretion from immobilized animals was elevated, but normalized in those also receiving TCT injections. TCT also normalized water content and excretion rates
Photon storage in Lambda-type optically dense atomic media. II. Free-space model
In a recent paper [Gorshkov et al., Phys. Rev. Lett. 98, 123601 (2007)], we
presented a universal physical picture for describing a wide range of
techniques for storage and retrieval of photon wave packets in Lambda-type
atomic media in free space, including the adiabatic reduction of the photon
group velocity, pulse-propagation control via off-resonant Raman techniques,
and photon-echo based techniques. This universal picture produced an optimal
control strategy for photon storage and retrieval applicable to all approaches
and yielded identical maximum efficiencies for all of them. In the present
paper, we present the full details of this analysis as well some of its
extensions, including the discussion of the effects of non-degeneracy of the
two lower levels of the Lambda system. The analysis in the present paper is
based on the intuition obtained from the study of photon storage in the cavity
model in the preceding paper [Gorshkov et al., Phys. Rev. A 76, 033804 (2007)].Comment: 26 pages, 8 figures. V2: significant changes in presentation, new
references, higher resolution of figure
Functional Characterization of Lamina X Neurons in ex-Vivo Spinal Cord Preparation
Functional properties of lamina X neurons in the spinal cord remain unknown despite
the established role of this area for somatosensory integration, visceral nociception,
autonomic regulation and motoneuron output modulation. Investigations of neuronal
functioning in the lamina X have been hampered by technical challenges. Here we
introduce an ex-vivo spinal cord preparation with both dorsal and ventral roots still
attached for functional studies of the lamina X neurons and their connectivity using an
oblique LED illumination for resolved visualization of lamina X neurons in a thick tissue.
With the elaborated approach, we demonstrate electrophysiological characteristics
of lamina X neurons by their membrane properties, firing pattern discharge and
fiber innervation (either afferent or efferent). The tissue preparation has been also
probed using Ca2+ imaging with fluorescent Ca2+ dyes (membrane-impermeable or
-permeable) to demonstrate the depolarization-induced changes in intracellular calcium
concentration in lamina X neurons. Finally, we performed visualization of subpopulations
of lamina X neurons stained by retrograde labeling with aminostilbamidine dye to
identify sympathetic preganglionic and projection neurons in the lamina X. Thus, the
elaborated approach provides a reliable tool for investigation of functional properties
and connectivity in specific neuronal subpopulations, boosting research of lamina X of
the spinal cord
On Pure Spinor Superfield Formalism
We show that a certain superfield formalism can be used to find an off-shell
supersymmetric description for some supersymmetric field theories where
conventional superfield formalism does not work. This "new" formalism contains
even auxiliary variables in addition to conventional odd super-coordinates. The
idea of this construction is similar to the pure spinor formalism developed by
N.Berkovits. It is demonstrated that using this formalism it is possible to
prove that the certain Chern-Simons-like (Witten's OSFT-like) theory can be
considered as an off-shell version for some on-shell supersymmetric field
theories. We use the simplest non-trivial model found in [2] to illustrate the
power of this pure spinor superfield formalism. Then we redo all the
calculations for the case of 10-dimensional Super-Yang-Mills theory. The
construction of off-shell description for this theory is more subtle in
comparison with the model of [2] and requires additional Z_2 projection. We
discover experimentally (through a direct explicit calculation) a non-trivial
Z_2 duality at the level of Feynman diagrams. The nature of this duality
requires a better investigation
Errors in quantum optimal control and strategy for the search of easily implementable control pulses
We introduce a new approach to assess the error of control problems we aim to
optimize. The method offers a strategy to define new control pulses that are
not necessarily optimal but still able to yield an error not larger than some
fixed a priori threshold, and therefore provide control pulses that might be
more amenable for an experimental implementation. The formalism is applied to
an exactly solvable model and to the Landau-Zener model, whose optimal control
problem is solvable only numerically. The presented method is of importance for
applications where a high degree of controllability of the dynamics of quantum
systems is required.Comment: 13 pages, 3 figure
Optimal control of atom transport for quantum gates in optical lattices
By means of optimal control techniques we model and optimize the manipulation
of the external quantum state (center-of-mass motion) of atoms trapped in
adjustable optical potentials. We consider in detail the cases of both non
interacting and interacting atoms moving between neighboring sites in a lattice
of a double-well optical potentials. Such a lattice can perform
interaction-mediated entanglement of atom pairs and can realize two-qubit
quantum gates. The optimized control sequences for the optical potential allow
transport faster and with significantly larger fidelity than is possible with
processes based on adiabatic transport.Comment: revised version: minor changes, 2 references added, published versio
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