1,911 research outputs found
Morphological variation of Varroa destructor (Parasitiformes, Varroidae) in different seasons
Varroosis is one of the most dangerous and common diseases of honey bees (Apis mellifera Linnaeus, 1758) worldwide, caused by gamasid mites of the species Varroa destructor Anderson and Trueman, 2000. This external parasite is widespread and adapted to the climate conditions of most countries of the world, and it can infect bees at any life stage. It parasites on worker bees, male and queen bees, larvae and pupae, feeding on their hemolymph and fat bodies, causing lower survival rates and lower density of bee colonies, decreasing the beesβ life span. Here, we studied the specifics of the seasonal variation of female V. destructor mites, obtained from honey bees, by the morphological characters of mites belonging to the summer and winter generations, and their differences were established. Using the methods of multivariate statistics, we found significant differences between the summer (JuneβJuly) and winter (OctoberβNovember) morphotypes of V. destructor mites. There are differences between the seasonal samples by 12 morphological characters of the parasite, namely the width of dorsal shield, width of dorsoventral shield, number of pores on sternal shield, length of tarsus and macrochaeta IV, and distances between setae of gnathosoma. Processing the seasonal samples of mites with discriminant analysis resulted in differences by 11 morphological characters including the length of dorsal shield, number of lancet setae, length and width of genitoventral shield, width of anal shield, number of setae and pores on sternal shield and distance between setae of gnathosoma. In general, the summer females are smaller and elongated compared to winter females, with larger genitoventral shield and shorter legs. The mites of summer and winter generations are adapted to different seasons: the summer mites to the reproductive period, the winter generation to overwintering on bees. The ratio of morphotypes in female V. destructor mites is observed to change during the year, from 20.2% winter morphotype in summer generation to 20.7% summer morphotype in winter mites. Studying the influence of acaricides on the distinguished morphotypes is a promising approach to improve pest control measures against varroosis of honey bees
Specific features of state regulation of operations with cryptocurrencies in the conditions of digitalization
Purpose: The article investigates specific features of state regulation of operations with cryptocurrencies in the conditions of the world economy digitalization. Design/Methodology/Approach: In order to form the state regulation of operations with cryptocurrencies, which create additional risks for the national currencies functioning in international financial and credit relations, it is necessary to consider this phenomenon first, from the position of a complete ban on the use of cryptocurrencies as a means of payment, second, in combination of a ban on the use of cryptocurrencies as means of payment, third, from the possibility of expanding the range of cryptocurrency users by including legal entities into it and fourth, the full legalization of the cryptocurrency. Findings: The authors developed and proposed a set of measures aimed at the formation of common standards and norms of state regulation of operations with cryptocurrencies in international financial relations. Practical Implications: The results of the study can be applied in the development of legal regulation of virtual currencies not only at the national level, but also at the international level. Originality/Value: The main contribution of the study is to identify possible risks in the sphere of state regulation of cryptocurrencies based on the experience of some countries: from formal permission (including recommendations on possible risks) or the application of general principles of regulation in the field of payments to the complete ban of such activities.peer-reviewe
Energy cascades and spectra in turbulent Bose-Einstein condensates
We present a numerical study of turbulence in Bose-Einstein condensates
within the 3D Gross-Pitaevskii equation. We concentrate on the direct energy
cascade in forced-dissipated systems. We show that behavior of the system is
very sensitive to the properties of the model at the scales greater than the
forcing scale, and we identify three different universal regimes: (1) a
non-stationary regime with condensation and transition from a four-wave to a
three-wave interaction process when the largest scales are not dissipated, (2)
a steady weak wave turbulence regime when largest scales are dissipated with a
friction-type dissipation, (3) a state with a scale-by-scale balance of the
linear and the nonlinear timescales when the large-scale dissipation is a
hypo-viscosity.Comment: 10 pages, 5 figure
Pade approximations of solitary wave solutions of the Gross-Pitaevskii equation
Pade approximants are used to find approximate vortex solutions of any
winding number in the context of Gross-Pitaevskii equation for a uniform
condensate and condensates with axisymmetric trapping potentials. Rational
function and generalised rational function approximations of axisymmetric
solitary waves of the Gross-Pitaevskii equation are obtained in two and three
dimensions. These approximations are used to establish a new mechanism of
vortex nucleation as a result of solitary wave interactions.Comment: In press by Journal of Physics: Mathematics and Genera
Investigation of Non-Stable Processes in Close Binary Ry Scuti
We present results of reanalysis of old electrophotometric data of early type
close binary system RY Scuti obtained at the Abastumani Astrophysical
Observatory, Georgia, during 1972-1990 years and at the Maidanak Observatory,
Uzbekistan, during 1979-1991 years. It is revealed non-stable processes in RY
Sct from period to period, from month to month and from year to year. This
variation consists from the hundredths up to the tenths of a magnitude.
Furthermore, periodical changes in the system's light are displayed near the
first maximum on timescales of a few years. That is of great interest with
regard to some similar variations seen in luminous blue variable (LBV) stars.
This also could be closely related to the question of why RY Sct ejected its
nebula.Comment: 11 pages, 6 figures, 2 table
Π¦Π΅ΡΠ΅Π±ΡΠ°Π»ΡΠ½ΡΠΉ ΠΈΡΠ΅ΠΌΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΈΠ½ΡΡΠ»ΡΡ ΠΊΠ°ΠΊ ΠΌΠ°Π½ΠΈΡΠ΅ΡΡΠ°ΡΠΈΡ ΡΠ°Π½Π½Π΅Π³ΠΎ Π½Π΅ΠΉΡΠΎΡΠΈΡΠΈΠ»ΠΈΡΠ°
Specific defeat of vessels of a brain at a syphilis can be one of the stroke reasons. The results of retrospective analysis of 53 case records of patients early manifest by forms neurosyphilis are resulted in article. The first group included the patients who were not receiving specific therapy concerning a syphilis, the patients treated earlier concerning a syphilitic infection have been included in another. From the given groups patients with cerebrovascular forms of neurosyphilis (only 24) have been allocated. The diagnosis has been verified on the basis of the clinical data, results clinic β laboratory and serologikal researches of whey of blood and liquor, the data of a magnito-resonant tomography, dopplerography researches of a brain blood-groove, compression, hypercapnia tests. Features of a clinical current cerebrovascular forms early neurosyphilis with stroke a current are revealed.ΠΠ΄Π½ΠΎΠΉ ΠΈΠ· ΠΏΡΠΈΡΠΈΠ½ ΠΈΠ½ΡΡΠ»ΡΡΠ° ΠΌΠΎΠΆΠ΅Ρ Π²ΡΡΡΡΠΏΠ°ΡΡ ΡΠΏΠ΅ΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΏΠΎΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ ΡΠΎΡΡΠ΄ΠΎΠ² Π³ΠΎΠ»ΠΎΠ²Π½ΠΎΠ³ΠΎ ΠΌΠΎΠ·Π³Π° ΠΏΡΠΈ ΡΠΈΡΠΈΠ»ΠΈΡΠ΅. ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΡΠ΅ΡΡΠΎΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π° 53 ΠΈΡΡΠΎΡΠΈΠΉ Π±ΠΎΠ»Π΅Π·Π½ΠΈ ΠΏΠ°ΡΠΈΠ΅Π½ΡΠΎΠ² Ρ ΡΠ°Π½Π½ΠΈΠΌΠΈ ΠΌΠ°Π½ΠΈΡΠ΅ΡΡΠ½ΡΠΌΠΈ ΡΠΎΡΠΌΠ°ΠΌΠΈ Π½Π΅ΠΉΡΠΎΡΠΈΡΠΈΠ»ΠΈΡΠ°. Π ΠΏΠ΅ΡΠ²ΡΡ Π³ΡΡΠΏΠΏΡ Π²ΠΎΡΠ»ΠΈ ΠΏΠ°ΡΠΈΠ΅Π½ΡΡ, Π½Π΅ ΠΏΠΎΠ»ΡΡΠ°Π²ΡΠΈΠ΅ ΡΠΏΠ΅ΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ ΠΏΠΎ ΠΏΠΎΠ²ΠΎΠ΄Ρ ΡΠΈΡΠΈΠ»ΠΈΡΠ°, Π²ΠΎ Π²ΡΠΎΡΡΡ Π±ΡΠ»ΠΈ Π²ΠΊΠ»ΡΡΠ΅Π½Ρ Π±ΠΎΠ»ΡΠ½ΡΠ΅, Π»Π΅ΡΠΈΠ²ΡΠΈΠ΅ΡΡ ΡΠ°Π½Π΅Π΅ ΠΏΠΎ ΠΏΠΎΠ²ΠΎΠ΄Ρ ΡΠΈΡΠΈΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΈΠ½ΡΠ΅ΠΊΡΠΈΠΈ. ΠΠ· Π΄Π°Π½Π½ΡΡ
Π³ΡΡΠΏΠΏ Π²ΡΠ΄Π΅Π»Π΅Π½Ρ 24 ΠΏΠ°ΡΠΈΠ΅Π½ΡΠ° Ρ ΡΠ΅ΡΠ΅Π±ΡΠΎΠ²Π°ΡΠΊΡΠ»ΡΡΠ½ΡΠΌΠΈ ΡΠΎΡΠΌΠ°ΠΌΠΈ Π½Π΅ΠΉΡΠΎΡΠΈΡΠΈΠ»ΠΈΡΠ°. ΠΠΈΠ°Π³Π½ΠΎΠ· Π±ΡΠ» Π²Π΅ΡΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½ Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΈΡ
Π΄Π°Π½Π½ΡΡ
, ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠ² ΠΊΠ»ΠΈΠ½ΠΈΠΊΠΎ-Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
ΠΈ ΡΠ΅ΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ ΡΡΠ²ΠΎΡΠΎΡΠΊΠΈ ΠΊΡΠΎΠ²ΠΈ ΠΈ Π»ΠΈΠΊΠ²ΠΎΡΠ°, Π΄Π°Π½Π½ΡΡ
ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎ-ΡΠ΅Π·ΠΎΠ½Π°Π½ΡΠ½ΠΎΠΉ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΠΈ, Π΄ΠΎΠΏΠ»Π΅ΡΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΌΠΎΠ·Π³ΠΎΠ²ΠΎΠ³ΠΎ ΠΊΡΠΎΠ²ΠΎΡΠΎΠΊΠ°, ΠΊΠΎΠΌΠΏΡΠ΅ΡΡΠΈΠΎΠ½Π½ΠΎΠΉ, Π³ΠΈΠΏΠ΅ΡΠΊΠ°ΠΏΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠ±. ΠΡΡΠ²Π»Π΅Π½Ρ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΡΠ΅ΡΠ΅Π±ΡΠΎΠ²Π°ΡΠΊΡΠ»ΡΡΠ½ΡΡ
ΡΠΎΡΠΌ ΡΠ°Π½Π½Π΅Π³ΠΎ Π½Π΅ΠΉΡΠΎΡΠΈΡΠΈΠ»ΠΈΡΠ° Ρ ΠΈΠ½ΡΡΠ»ΡΡΠΎΠΎΠ±ΡΠ°Π·Π½ΡΠΌ ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ΠΌ
Polaron Effects on Superexchange Interaction: Isotope Shifts of , , and in Layered Copper Oxides
A compact expression has been obtained for the superexchange coupling of
magnetic ions via intermediate anions with regard to polaron effects at both
magnetic ions and intermediate anions. This expression is used to analyze the
main features of the behavior of isotope shifts for temperatures of three types
in layered cuprates: the Neel temperatures (), critical temperatures of
transitions to a superconducting state (), and characteristic temperatures
of the pseudogap in the normal state ().Comment: 4 pages, 1 figur
Surface alignment and anchoring transitions in nematic lyotropic chromonic liquid crystal
The surface alignment of lyotropic chromonic liquid crystals (LCLCs) can be
not only planar (tangential) but also homeotropic, with self-assembled
aggregates perpendicular to the substrate, as demonstrated by mapping optical
retardation and by three-dimensional imaging of the director field. With time,
the homeotropic nematic undergoes a transition into a tangential state. The
anchoring transition is discontinuous and can be described by a double-well
anchoring potential with two minima corresponding to tangential and homeotropic
orientation.Comment: Accepted for publication in Phys. Rev. Lett. (Accepted Wednesday Jun
02, 2010
Experimental study of the inverse cascade in gravity wave turbulence
We perform experiments to study the inverse cascade regime of gravity wave
turbulence on the surface of a fluid. Surface waves are forced at an
intermediate scale corresponding to the gravity-capillary wavelength. In
response to this forcing, waves at larger scales are observed. The spectrum of
their amplitudes exhibits a frequency-power law at high enough forcing. Both
observations are ascribed to the upscale wave action transfers of gravity wave
turbulence. The spectrum exponent is close to the value predicted by the weak
turbulence theory. The spectrum amplitude is found to scale linearly with the
mean injected power. We measure also the distributions of the injected power
fluctuations in the presence of upscale (inverse) transfers or in the presence
of a downscale (direct) cascade in gravity wave turbulence.Comment: in press in EPL (2011
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