Sergey V. Mironov

Octonic representation of electromagnetic field equations

In this paper we represent eight-component values “octons,” generating associative noncommutative algebra. It is shown that the electromagnetic field in a vacuum can be described by a generalized octonic equation, which leads both to the wave equations for potentials and fields and to the system of Maxwell’s equations. The octonic algebra allows one to perform compact combined calculations simultaneously with scalars, vectors, pseudoscalars, and pseudovectors. Examples of such calculations are demonstrated by deriving the relations for energy, momentum, and Lorentz invariants of the electromagnetic field.

Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis

We study spatially flat bouncing cosmologies and models with the early-time Genesis epoch in a popular class of generalized Galileon theories. We ask whether there exist solutions of these types which are free of gradient and ghost instabilities. We find that irrespectively of the forms of the Lagrangian functions, the bouncing models either are plagued with these instabilities or have singularities. The same result holds for the original Genesis model and its variants in which the scale factor tends to a constant as

Octonic second-order equations of relativistic quantum mechanics

t\to -\infty

DNA barcoding and minibarcoding as a powerful tool for feather mite studies

. The result remains valid in theories with additional matter that obeys the Null Energy Condition and interacts with the Galileon only gravitationally. We propose a modified Genesis model which evades our no-go argument and give an explicit example of healthy cosmology that connects the modified Genesis epoch with kination (the epoch still driven by the Galileon field, which is a conventional massless scalar field at that stage).

Properties of Scalar Perturbations Generated by Conformal Scalar Field

We demonstrate a generalization of relativistic quantum mechanics using eight-component value “octons” that generate an associative noncommutative spatial algebra. It is shown that the octonic second-order equation for the eight-component octonic wave function, obtained from the Einstein relation for energy and momentum, describes particles with spin 1/2. It is established that the octonic wave function of a particle in the state with defined spin projection has a specific spatial structure that takes the form of an octonic oscillator with two spatial polarizations: longitudinal linear and transverse circular.

OCTONIC FIRST-ORDER EQUATIONS OF RELATIVISTIC QUANTUM MECHANICS

Feather mites (Astigmata: Analgoidea and Pterolichoidea) are among the most abundant and commonly occurring bird ectosymbionts. Basic questions on the ecology and evolution of feather mites remain unanswered because feather mite species identification is often only possible for adult males, and it is laborious even for specialized taxonomists, thus precluding large‐scale identifications. Here, we tested DNA barcoding as a useful molecular tool to identify feather mites from passerine birds. Three hundred and sixty‐one specimens of 72 species of feather mites from 68 species of European passerine birds from Russia and Spain were barcoded. The accuracy of barcoding and minibarcoding was tested. Moreover, threshold choice (a controversial issue in barcoding studies) was also explored in a new way, by calculating through simulations the effect of sampling effort (in species number and species composition) on threshold calculations. We found one 200‐bp minibarcode region that showed the same accuracy as the full‐length barcode (602 bp) and was surrounded by conserved regions potentially useful for group‐specific degenerate primers. Species identification accuracy was perfect (100%) but decreased when singletons or species of the Proctophyllodes pinnatus group were included. In fact, barcoding confirmed previous taxonomic issues within the P. pinnatus group. Following an integrative taxonomy approach, we compared our barcode study with previous taxonomic knowledge on feather mites, discovering three new putative cryptic species and validating three previous morphologically different (but still undescribed) new species.

High-efficiency second-harmonic generation of superintense ultrashort laser pulses

Primordial scalar perturbations may be generated when complex conformal scalar field rolls down its negative quartic potential. We begin with the discussion of peculiar infrared properties of this scenario. We then consider the statistical anisotropy inherent in the model. Finally, we discuss the non-Gaussianity of scalar perturbations. Because of symmetries, the bispectrum vanishes identically. We present a general expression for the trispectrum and give its explicit form in the folded limit.

Climate-driven variation in the intensity of a host-symbiont animal interaction along a broad elevation gradient.

We demonstrate a generalization of relativistic quantum mechanics using eight-component octonic wave function and octonic spatial operators. It is shown that the second-order equation for octonic wave function describing particles with spin 1/2 can be reformulated in the form of a system of first-order equations for quantum fields, which is analogous to the system of Maxwell equations for the electromagnetic field. It is established that for the special types of wave functions the second-order equation can be reduced to the single first-order equation analogous to the Dirac equation. At the same time it is shown that this first-order equation describes particles, which do not have quantum fields.

New feather mites of the subfamily Pterodectinae (Acari: Proctophyllodidae) from passerines and woodpeckers (Aves: Passeriformes and Piciformes) in Vietnam

The effect of instantaneous cubic nonlinearity on second-harmonic generation of femtosecond laser pulses is investigated. The possibility of improving generation efficiency and shortening pulse duration is analyzed. Energy conversion efficiency of 60% was obtained in an experiment in a 1 mm thickness KDP crystal at the peak intensity of 0.6 TW/cm(2) and the duration of 60 fs.

Parasite biodiversity faces extinction and redistribution in a changing climate

Gradients of environmental stress may affect biotic interactions in unpredictable ways responding to climate variation, depending on the abiotic stress tolerance of interacting partners. Here, we study the effect of local climate on the intensity of feather mites in six mountain passerines along a 1400 m elevational gradient characterized by shifting temperature and rainfall. Although obligatory symbionts of warm-blooded organisms are assumed to live in mild and homeothermic environments, those inhabiting external, non-blood-irrigated body portions of the host organism, such as feather mites, are expected to endure exposure to the direct influence of a fluctuating climate. As expected, feather mite intensity declined with elevation in all bird species, a pattern that was also found in cold-adapted passerines that have typical alpine habits. The elevation cline was mainly explained by a positive effect of the average temperature upon mite intensity in five of the six species studied. Precipitation explained less variance in mite intensity than average temperature, and showed a negative correlation in half of the studied species. We found no climate-driven migration of mites along the wings of birds, no replacement of mite species along elevation gradients and no association with available food resources for mites (estimated by the size of the uropygial gland). This study suggests that ectosymbionts of warm-blooded animals may be highly sensitive to climatic variation and become less abundant under stressful environmental conditions, providing empirical evidence of the decline of specialized biotic interactions among animal species at high elevations.