819 research outputs found
High order fluid model for streamer discharges. II. Numerical solution and investigation of planar fronts
The high order fluid model developed in the preceding paper is employed here
to study the propagation of negative planar streamer fronts in pure nitrogen.
The model consists of the balance equations for electron density, average
electron velocity, average electron energy and average electron energy flux.
These balance equations have been obtained as velocity moments of Boltzmann's
equation and are here coupled to the Poisson equation for the space charge
electric field. Here the results of simulations with the high order model, with
a PIC/MC (Particle in cell/Monte Carlo) model and with the first order fluid
model based on the hydrodynamic drift-diffusion approximation are presented and
compared. The comparison with the MC model clearly validates our high order
fluid model, thus supporting its correct theoretical derivation and numerical
implementation. The results of the first order fluid model with local field
approximation, as usually used for streamer discharges, show considerable
deviations. Furthermore, we study the inaccuracies of simulation results caused
by an inconsistent implementation of transport data into our high order fluid
model. We also demonstrate the importance of the energy flux term in the high
order model by comparing with results where this term is neglected. Finally,
results with an approximation for the high order tensor in the energy flux
equation is found to agree well with the PIC/MC results for reduced electric
fields up to 1000 Townsend, as considered in this work.Comment: 26 pages, 11 figure
Derivation and test of high order fluid model for streamer discharges
A high order fluid model for streamer dynamics
is developed by closing the system after the 4th moment
of the Boltzmann equation in local mean energy approximation.
This is done by approximating the high order
pressure tensor in the heat flux equation through the previous
moments. Mathematical characteristics of the system is
studied. Then planar ionization fronts for negative streamers
in Nsub2 are simulated with the classical streamer model,
MC-PIC particle model, and with the present higher order
model
Testicular dermoid cyst in a 14-year-old child
ΠΠΠ ΠΠΠΠΠΠΠ― ΠΠΠ‘Π’Π /ΠΠΠΠΠΠΠΠ ΠΠΠΠ /ΠΠΠΠΠΠ―ΠΠ§ΠΠ /Π£ΠΠ¬Π’Π ΠΠ‘ΠΠΠΠΠ’ΠΠΠΠΠΠΠ§ΠΠ‘ΠΠΠ Π‘ΠΠ£Π§ΠΠΠ ΡΠ°Π±ΠΎΡΠ΅ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠ»ΡΡΠ°ΠΉ ΡΠ΅Π±Π΅Π½ΠΊΠ°, 14 Π»Π΅Ρ, Ρ Π΄Π΅ΡΠΌΠΎΠΈΠ΄Π½ΠΎΠΉ ΠΊΠΈΡΡΠΎΠΉ ΠΏΡΠ°Π²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΠ°. ΠΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ Π²ΠΏΠ΅ΡΠ²ΡΠ΅ Π±ΡΠ»ΠΎ Π²ΡΡΠ²Π»Π΅Π½ΠΎ ΠΏΡΠΈ ΠΏΡΠΎΡΠΈΠ»Π°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΎΡΠΌΠΎΡΡΠ΅ Π² ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠ΅. Π ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠ΅ΠΌ ΠΏΠ°ΡΠΈΠ΅Π½ΡΡ Π½Π΅ΠΎΠ΄Π½ΠΎΠΊΡΠ°ΡΠ½ΠΎ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΎΡΡ ΡΠ»ΡΡΡΠ°Π·Π²ΡΠΊΠΎΠ²ΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π½Π°ΡΡΠΆΠ½ΡΡ
ΠΏΠΎΠ»ΠΎΠ²ΡΡ
ΠΎΡΠ³Π°Π½ΠΎΠ², ΠΏΡΠΈ ΠΊΠΎΡΠΎΡΠΎΠΌ Π² Π²Π΅ΡΡ
Π½Π΅ΠΌ ΠΏΠΎΠ»ΡΡΠ΅ ΠΏΡΠ°Π²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΠ° Π²ΡΡΠ²Π»ΡΠ»Π°ΡΡ Π½Π΅ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½Π°Ρ ΡΡ
ΠΎΡΡΡΡΠΊΡΡΡΠ° ΡΠ°Π·ΠΌΠ΅ΡΠ°ΠΌΠΈ 14 ΠΌΠΌ, 13,7 ΠΌΠΌ ΠΈ 12 ΠΌΠΌ Ρ ΡΠ΅ΡΠΊΠΈΠΌ, ΡΠΎΠ²Π½ΡΠΌ ΠΊΠΎΠ½ΡΡΡΠΎΠΌ. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΠΌΠΌΡΠ½ΠΎΡΠ΅ΡΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π° ΠΊΡΠΎΠ²ΠΈ Π½Π΅ ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΈ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠ΅ ΠΎΡΠ½ΠΎΠ²Π½ΡΡ
ΠΌΠ°ΡΠΊΠ΅ΡΠΎΠ² ΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΠΎΠ³ΠΎ ΠΏΡΠΎΡΠ΅ΡΡΠ°. ΠΡΠΈ Π±ΠΈΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΎΠΌ ΡΠ΅ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΠΊΡΠΎΠ²ΠΈ ΠΎΡΠΌΠ΅ΡΠ°Π»ΠΎΡΡ Π½Π΅Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠ΅ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΠ΅ ΡΡΠΎΠ²Π½Ρ ΠΏΡΡΠΌΠΎΠ³ΠΎ Π±ΠΈΠ»ΠΈΡΡΠ±ΠΈΠ½Π° ΠΈ ΡΡΠ²ΠΎΡΠΎΡΠΎΡΠ½ΠΎΠ³ΠΎ ΠΆΠ΅Π»Π΅Π·Π°. ΠΠ»Ρ ΡΡΠΎΡΠ½Π΅Π½ΠΈΡ Π΄ΠΈΠ°Π³Π½ΠΎΠ·Π° ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½Π° ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎ-ΡΠ΅Π·ΠΎΠ½Π°Π½ΡΠ½Π°Ρ ΡΠΎΠΌΠΎΠ³ΡΠ°ΡΠΈΡ ΠΎΡΠ³Π°Π½ΠΎΠ² ΠΌΠ°Π»ΠΎΠ³ΠΎ ΡΠ°Π·Π° Ρ Π²Π½ΡΡΡΠΈΠ²Π΅Π½Π½ΡΠΌ ΠΊΠΎΠ½ΡΡΠ°ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ. ΠΠΎΡΠ»Π΅ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΡΠΊΠ°Π·Π°Π½Π½ΠΎΠ³ΠΎ ΠΎΠ±ΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π±ΡΠ» Π²ΡΡΡΠ°Π²Π»Π΅Π½ Π΄ΠΈΠ°Π³Π½ΠΎΠ· "ΠΊΠΈΡΡΠΎΠ·Π½ΠΎΠ΅ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠ°Π²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΠ°". ΠΠΎΡΠ»Π΅ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΡΡ
Π΄ΠΎΠΏΠΎΠ»Π½ΠΈΡΠ΅Π»ΡΠ½ΡΡ
Π΄ΠΈΠ°Π³Π½ΠΎΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΌΠ΅ΡΠΎΠΏΡΠΈΡΡΠΈΠΉ (Π£ΠΠ ΠΏΠ΅ΡΠΈΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π»ΠΈΠΌΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ·Π»ΠΎΠ², ΠΎΠ±ΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π±ΡΡΡΠ½ΠΎΠΉ ΠΏΠΎΠ»ΠΎΡΡΠΈ Ρ Π²Π½ΡΡΡΠΈΠ²Π΅Π½Π½ΡΠΌ ΠΊΠΎΠ½ΡΡΠ°ΡΡΠ½ΡΠΌ ΡΡΠΈΠ»Π΅Π½ΠΈΠ΅ΠΌ) Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΎΠΏΠ΅ΡΠ°ΡΠΈΡ, Π·Π°ΠΊΠ»ΡΡΠ°Π²ΡΠ°ΡΡΡ Π² ΡΠ΅Π²ΠΈΠ·ΠΈΠΈ ΠΏΡΠ°Π²ΠΎΠΉ ΠΏΠΎΠ»ΠΎΠ²ΠΈΠ½Ρ ΠΌΠΎΡΠΎΠ½ΠΊΠΈ ΠΈ ΡΠ΄Π°Π»Π΅Π½ΠΈΠΈ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠ°Π²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΠ°. ΠΠ½ΡΡΠ°ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½ΠΎ ΠΏΠΎ Π΄Π°Π½Π½ΡΠΌ ΡΠΊΡΠΏΡΠ΅ΡΡ-Π±ΠΈΠΎΠΏΡΠΈΠΈ Π΄ΠΈΠ°Π³Π½ΠΎΡΡΠΈΡΠΎΠ²Π°Π»Π°ΡΡ Π΄Π΅ΡΠΌΠΎΠΈΠ΄Π½Π°Ρ ΠΊΠΈΡΡΠ° ΠΏΡΠ°Π²ΠΎΠ³ΠΎ ΡΠΈΡΠΊΠ°, ΡΡΠΎ ΠΏΠΎΠ΄ΡΠ²Π΅ΡΠ΄ΠΈΠ»ΠΎΡΡ ΠΏΡΠΈ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠ΅ΠΌ Π³ΠΈΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΈ. ΠΠΎΡΠ»Π΅ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠΎΠ½Π½ΡΠΉ ΠΏΠ΅ΡΠΈΠΎΠ΄ ΠΏΡΠΎΡΠ΅ΠΊΠ°Π» Π³Π»Π°Π΄ΠΊΠΎ. ΠΠ°ΡΠΈΠ΅Π½Ρ Π²ΡΠΏΠΈΡΠ°Π»ΡΡ Π² ΡΠ΄ΠΎΠ²Π»Π΅ΡΠ²ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠΌ ΡΠΎΡΡΠΎΡΠ½ΠΈΠΈ. Π’Π°ΠΊΠΈΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ, ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π½ΠΎΠ΅ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΎΠ΅ Π½Π°Π±Π»ΡΠ΄Π΅Π½ΠΈΠ΅ ΠΏΠΎΠ΄ΡΠ΅ΡΠΊΠΈΠ²Π°Π΅Ρ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΠΎΡΠΈΠ»Π°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ°Π±ΠΎΡΡ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΎΠ³ΠΎ ΠΏΠ΅ΡΡΠΎΠ½Π°Π»Π° ΠΏΠ΅ΡΠ²ΠΈΡΠ½ΠΎΠ³ΠΎ Π·Π²Π΅Π½Π° ΠΏΠΎ ΡΠ²ΠΎΠ΅Π²ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠΉ Π΄ΠΈΠ°Π³Π½ΠΎΡΡΠΈΠΊΠ΅ ΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΡΡ
ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² Π½Π°ΡΡΠΆΠ½ΡΡ
ΠΏΠΎΠ»ΠΎΠ²ΡΡ
ΠΎΡΠ³Π°Π½ΠΎΠ², ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎ Ρ Π΄Π΅ΡΠ΅ΠΉ ΠΏΡΠ±Π΅ΡΡΠ°ΡΠ½ΠΎΠ³ΠΎ Π²ΠΎΠ·ΡΠ°ΡΡΠ°.The paper presents a clinical case of a 14-year-old child with a dermoid cyst of the right testicle. The formation was first detected during a routine check-up in the polyclinic. Then the external genitalia ultrasound examination was repeatedly performed to the patient, which revealed an inhomogeneous echostructure with dimensions of 14 mm, 13.7 mm and 12 mm with a clear, even contour in the upper pole of the right testicle. The enzyme-linked immunosorbent assay (ELISA) did not show an increase in the main tumour markers. The biochemical blood test revealed an insignificant rise in conjugated bilirubin and serum iron. To clarify the diagnosis, magnetic resonance tomography of the pelvic organs with intravenous contrast was recommended. After examination, the cystic lesion of the right testicle was diagnosed. After carrying out the necessary additional diagnostic measures (ultrasound examination of the peripheral lymphatic nodes, the abdominal cavity exploration with intravenous contrast enhancement), the child underwent an operation consisting in revising the right half of the scrotum and removing the formation of the right testicle. Intraoperatively, according to the express biopsy test, the dermoid cyst of the right testicle was diagnosed, which was confirmed by the subsequent histological examination. The postoperative period was uneventful. The patient was discharged in satisfactory state. Thus, the presented clinical observation emphasizes the need to optimize the preventive work of primary care medical personnel for timely diagnosis of tumor processes in the external genital organs, especially in children of puberty
High order fluid model for streamer discharges
A high order fluid model for streamer discharges is developed and used to investigate propagation of negative streamer fronts in N2 . Mo- mentum transfer theory is employed to evaluate the collision terms and close the system of moment/balance equations. The results of simulations are compared with those obtained by a PIC/MC method and by the classical first order fluid model based on the drif
Peculiarities of a Colloidal Polysaccharide of Newly Isolated Iron Oxidizing Bacteria in Armenia
Microorganisms belonging to different systematic and physiological groups produce various intra- and extracellular polysaccharides, which both play an important role in the life of microorganisms and have great practical application. Iron and sulfur oxidizing bacteria produce capsular (EPS) and colloidal polysaccharides. At present the properties and functional role of EPS are well studied. However, the properties of the colloidal polysaccharides produced by iron oxidizing bacteria have not been sufficiently explored. A new iron oxidizing bacteria Leptospirillum ferriphilium CC was isolated from sulfide ores of Armenia. Its morphological and physiological features have been studied. A colloidal polysaccharide has been isolated with the use of an original method developed by the authors, and its physical and chemical properties have been studied. It has been shown that the colloidal polysaccharide consists of three different monomers- glucose, fructose, mannose.. Investigations with a complex method of optical polarization microscopy and analytical programs allowed determining the size, shape change, perimeter, degree of hydratation and crystallization at 0.07% and 0.04% of polysaccharide concentration. It was shown that the size of a polysaccharide colloidal particle does not much depend on polysaccharide concentration, however, the number of identical colloidal formations is dependent on the concentration of polysaccharide
- β¦