Assessing the Working-Cycle Fluctuation in Internal-Combustion Engines from the Nonuniformity of the Idling Speed

Russian Engineering Research - In practice, it is important to assess the nonuniformity of the crankshaft speed in internal combustion engines. In such assessments, the sensitivity of the chosen...     

Plasmon resonances in a silver elliptical cylinder surrounded by a confocal elliptical glass shell

Plasmon resonances occurring in a 2D problem of diffraction of a plane wave by a silver cylinder enclosed in a glass shell are studied under the assumption that the media interfaces are shaped as confocal ellipses. Scattering and absorption spectra in the optical range are calculated using strict numerical techniques. The obtained analytical expressions allow resonance parameters of the structure to be obtained in the quasi-static approximation.     

Features of the operation of high-stability lasers after connection to an unmatched optical load

The results of investigation of the laser-interferometer electromagnetic system are presented by the example of the analysis of a three-mirror optical resonator as the simplest model of a laser connected to an unmatched load. Integral equations describing the electromagnetic field in a three-mirror resonator with cylindrical mirrors are analyzed. The results obtained are verified by the numerical simulation of the behavior of eigenfrequencies for several simplest designs of a three-mirror laser resonator.     

Singular points and singular lines in problems of diffraction by bodies with an anisotropic impedance

The effect (earlier discovered) of penetration of an electromagnetic-field power flux into a wall exhibiting perfect mixed anisotropic conductivity is considered in more detail. It is shown that the power transmitted into the screen through the nodes of conductivity lines and through resonance-length closed contours can be regarded as the limit value of the power absorbed in a wall characterized by an anisotropic impedance when the absorbing impedance approaches the values corresponding to the case of perfect mixed conductivity.     

The changing presentation of pyloric stenosis

A triplet pregnancy in a 23-year-old woman was terminated at 15 weeks of gestation because of her severe hypertension, lung edema, and secondary hyperthyroidism. The pregnancy consisted of a hydatidiform mole with a 46,XY karyotype and two fetuses each with 46,XX and a 46,XY karyotype. To determine the zygosity and genetic origin of the mole and fetuses, PCR- and computer-assisted genotyping were performed at 27 CA-repeat marker loci that were distributed evenly over the genome. As a result, genotypes of the three pregnancy products were distinct from each other, indicating that the triplets were trizygotic. The mole lacked any maternal alleles but inherited both of the paternal alleles and/or one paternal allele in duplicate. This, along with the XY sex chromosome constitution, indicated that the mole resulted from dispermic androgenesis. The mother developed a persistent trophoblastic tumor thereafter.     

Hallucinations, sleep fragmentation, and altered dream phenomena in Parkinson''s disease

Middle ear effusion has been considered the most common cause of vestibular disturbance in children. However, there have been only a few studies on vestibular disturbance in children with otitis media with effusion. We studied the vestibular systems of 30 children with otitis media with effusion aged 8 to 13 years and compared the results with 15 age- and sex-matched controls. A questionnaire relating to vestibular disturbance was given to patients and their parents. Spontaneous nystagmus and positional nystagmus were recorded by electronystagmography as diagnostic tests of the vestibular system. Romberg's and past-pointing tests were performed on children with otitis media with effusion and controls. After vestibular tests were completed, myringotomy was performed, and a ventilation tube was inserted. The questionnaire and the vestibular tests were repeated after the operation and during the first month after surgery. Our study showed that there was a history of vestibular disturbance in 33% of children with otitis media with effusion. Electronystagmography and Romberg's test findings demonstrated that 33% of the children had vestibular dysfunction (p < 0.05). After myringotomy with ventilation tube insertion, vestibular test results returned to normal, and symptoms related to vestibular disturbance improved. These findings confirm the assumption that middle ear effusion may affect the vestibular system, which can be resolved after myringotomy with ventilation tube insertion.     

Triply degenerate surface waves in the metamaterial plate

A triply degenerate surface wave has been shown to exist in the metamaterial plate with the electrodynamic parameters ɛ₀= −1.036… and μ₀ > −0.964… The behavioral features of the field excited by a point source located near the plate have been revealed under the assumption that the plate parameters tend to resonant quantities and ɛ₀ and μ₀.     

Thin screens that exhibit the properties of a magnetic wall and are based on small-period gratings of Helmholtz resonators

An electrodynamic theory is developed for thin screens that exhibit the properties of a magnetic wall and are small-period gratings of low-frequency Helmholtz resonators.     

<Superscript>212</Superscript>Pb/<Superscript>212</Superscript>Bi Generator for nuclear medicine

A scheme for producing the α-emitters ²¹²Pb and ²¹²Bi, to be used in a promising method of diagnostics and therapy in oncology – radioimmunotherapy, is proposed. The technology is based on two generators operating in tandem: ²²⁸Th/²¹²Pb and ²¹²Pb/²¹²Bi. The first one is based on separation from an initial solution containing thorium isotopes and gaseous ²²⁰Rn, which secures the purity of the desired products ²¹²Pb and ²¹²Bi. For a ²²⁸Th/²¹²Pb model generator, the efficiency of ²²⁰Rn extraction from solution was ~60%. After conditioning, the ²¹²Pb solution from the ²²⁸Th/²¹²Pb generator was used to charge a column, which functioned as a ²¹²Pb/²¹²Bi generator, with a cation exchanger.