219 research outputs found
Energy balance of cosmic rays
Energy dissipation channels of cosmic rays in galaxy and metagalax
Constraints on the variability of quark masses from nuclear binding
Based on recent work on nuclear binding, we update and extend the anthropic
constraints on the light quark masses, with results that are more tightly
constrained than previously obtained. We find that heavy nuclei would fall
apart (because the attractive nuclear central potential becomes too weak) if
the sum of the light quark masses m_u+m_d would exceed their physical values by
64% (at 95% confidence level). We summarize the anthropic constraints that
follow from requiring the existence both of heavy atoms and of hydrogen. With
the additional assumption that the quark Yukawa couplings do not vary, these
constraints provide a remarkably tight anthropic window for the Higgs vacuum
expectation value: 0.39 < v/v_physical < 1.64.Comment: 21 pages, 7 figure
Inhibitory systems of the spinal cord in the control of interactions of functionally coupled muscles
Studies on muscle functional coupling mechanisms have detected excitatory and inhibitory reflex systems differing in their organization at the spinal level. The classic notions on inhibitory interactions between antagonists at the motoneuronal and premotoneuronal levels are supplemented with data on excitatory interactions. Mutual excitation of synergist muscles is also not the only possible type of interaction: inhibitory relationships are found in the system of synergists under certain physiological conditions. This organization of the motor centers of antagonists and synergists enhances the possibilities for fine coordination of their activity, inhibition and disinhibition mechanisms playing an important role in this system. Data on the inhibitory systems of the spinal cord, in particular, the inhibitory interactions between functionally coupled muscles, are reviewed. © Pleiades Publishing, Inc. 2007
Self-similarity of rogue wave generation in gyrotrons: Beyond the Peregrine breather
Within the framework of numerical simulations, we study the gyrotron dynamics
under conditions of a significant excess of the operating current over the
starting value, when the generation of electromagnetic pulses with anomalously
large amplitudes ("rogue waves") are realized. We demonstrate that the relation
between peak power and duration of rogue waves is self-similar, but does not
reproduce the one characteristic for Peregrine breathers. Remarkably, the
discovered self-similar relation corresponds to the exponential nonlinearity of
an equivalent Schr\"odinger-like evolution equation. This interpretation can be
used as a theoretical basis for explaining the giant amplitudes of gyrotron
rogue waves
THE ROLE OF PROTOCOL BIOPSIES IN EARLY PERIOD AFTER KIDNEY TRANSPLANTATION
46 protocol graft biopsies with the subsequent histological examination were performed in 39 patients after kidney transplantation. In 20 patients with stable graft function acute subclinical rejection were revealed in 12 (60%) with the following steroid therapy. In 19 patients with delayed kidney graft function acute rejection was revealed in 13 (68,4%). Treatment by steroids was successful and function renewed. Our results showed that protocol biopsy is a safe and reliable method that allows to recognize such kidney graft pathology as subclinical rejection and to perform its treatment in time
Many-worlds interpretation of quantum theory and mesoscopic anthropic principle
We suggest to combine the Anthropic Principle with Many-Worlds Interpretation
of Quantum Theory. Realizing the multiplicity of worlds it provides an
opportunity of explanation of some important events which are assumed to be
extremely improbable. The Mesoscopic Anthropic Principle suggested here is
aimed to explain appearance of such events which are necessary for emergence of
Life and Mind. It is complementary to Cosmological Anthropic Principle
explaining the fine tuning of fundamental constants. We briefly discuss various
possible applications of Mesoscopic Anthropic Principle including the Solar
Eclipses and assembling of complex molecules. Besides, we address the problem
of Time's Arrow in the framework of Many-World Interpretation. We suggest the
recipe for disentangling of quantities defined by fundamental physical laws and
by an anthropic selection.Comment: 11 page
Computational and Biological Analogies for Understanding Fine-Tuned Parameters in Physics
In this philosophical paper, we explore computational and biological
analogies to address the fine-tuning problem in cosmology. We first clarify
what it means for physical constants or initial conditions to be fine-tuned. We
review important distinctions such as the dimensionless and dimensional
physical constants, and the classification of constants proposed by
Levy-Leblond. Then we explore how two great analogies, computational and
biological, can give new insights into our problem. This paper includes a
preliminary study to examine the two analogies. Importantly, analogies are both
useful and fundamental cognitive tools, but can also be misused or
misinterpreted. The idea that our universe might be modelled as a computational
entity is analysed, and we discuss the distinction between physical laws and
initial conditions using algorithmic information theory. Smolin introduced the
theory of "Cosmological Natural Selection" with a biological analogy in mind.
We examine an extension of this analogy involving intelligent life. We discuss
if and how this extension could be legitimated.
Keywords: origin of the universe, fine-tuning, physical constants, initial
conditions, computational universe, biological universe, role of intelligent
life, cosmological natural selection, cosmological artificial selection,
artificial cosmogenesis.Comment: 25 pages, Foundations of Science, in pres
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