Log-log growth of channel capacity for nondispersive nonlinear optical fiber channel in intermediate power range

We consider a model nondispersive nonlinear optical fiber channel with an additive Gaussian noise. Using Feynman path-integral technique, we find the optimal input signal distribution maximizing the channel's per-sample mutual information at large signal-to-noise ratio in the intermediate power range. The optimal input signal distribution allows us to improve previously known estimates for the channel capacity. We calculate the output signal entropy, conditional entropy, and per-sample mutual information for Gaussian, half-Gaussian, and modified Gaussian input signal distributions. We demonstrate that in the intermediate power range the capacity (the per-sample mutual information for the optimal input signal distribution) is greater than the per-sample mutual information for half-Gaussian input signal distribution considered previously as the optimal one. We also show that the capacity grows as loglogP in the intermediate power range, where P is the signal power

NEW DATA ON THE RESULTS OF THE MOLOGA-SHEKSNA LOWLAND LAKES RESEARCH (VOLOGDA REGION, RUSSIA)

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Low-temperature heat capacity of fullerite C₆₀ doped with nitrogen

The heat capacity Cm of polycrystalline fullerite C₆₀ doped with nitrogen has been measured in the temperature interval 2–13 K. The contributions to the heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C₆₀ molecules (Einstein contribution), and from the motion of the N₂ molecules in the octahedral cavities of the C₆₀ lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first-order phase transformation that had been detected earlier in the dilatometric investigation of the orientational N₂–C₆₀ glass. A possible explanation of this fact is proposed

Point-contact Andreev reflection spectroscopy of a magnetic superconductor Dy₀.₆Y₀.₄Rh₃.₈₅Ru₀.₁₅B₄

The Andreev reflection spectra dI/dV(V) of the magnetic superconductor Dy₀.6Y₀.₄Rh₃.₈₅Ru₀.₁₅B₄ have been investigated. Pronounced stimulation of superconductivity by an external magnetic field has been observed for the first time. The effect showed up as enhancement of the gap structure (and hence the gap itself) in the spectra and its shift towards higher voltages with an increasing field. In the intermediate fields the structure also behaved strangely: instead of the usual smooth decrease with a grooving field, the gap features dropped abruptly near the critical point Hc₂. Of interest is also the abnormally high relative gap value 2∆/kBTc ≈ 4 (as compared to conventional singlet superconductors) which was found for some contacts from a comparison of experimental spectra and the modified Blonder–Tinkham–Klapwiyk theory. We attribute the features revealed in the point-contact spectroscopic investigations of Dy₀.6Y₀.₄Rh₃.₈₅Ru₀.₁₅B₄ in a magnetic field to the triplet-type Cooper pairing in the compound because only in this case one can expect the stimulation of superconductivity in the stationary magnetic fields up to ~ 0.7Hc₂.The Andreev reflection spectra dI/dV(V) of the magnetic superconductor Dy₀.₆Y₀.₄Rh₃.₈₅Ru₀.₁₅B₄ have been investigated. Pronounced stimulation of superconductivity by an external magnetic field has been observed for the first time. The effect showed up as enhancement of the gap structure (and hence the gap itself) in the spectra and its shift towards higher voltages with an increasing field. In the intermediate fields the structure also behaved strangely: instead of the usual smooth decrease with a grooving field, the gap features dropped abruptly near the critical point Hc₂. Of interest is also the abnormally high relative gap value 2∆/kBTc ≈ 4 (as compared to conventional singlet superconductors) which was found for some contacts from a comparison of experimental spectra and the modified Blonder–Tinkham–Klapwiyk theory. We attribute the features revealed in the point-contact spectroscopic investigations of Dy₀.₆Y₀.₄Rh₃.₈₅Ru₀.₁₅B₄ in a magnetic field to the triplet-type Cooper pairing in the compound because only in this case one can expect the stimulation of superconductivity in the stationary magnetic fields up to ~ 0.7Hc₂

Investigation of energy and mass balance “Trimyx-3M” Galatea multipole magnetic trap

In the work using Rogowski loop, measurements of the diamagnetic current, generating in the plasma volume of the “Trimyx-3M” Galatea multipole magnetic trap under its filling by plasmoids have been carried out. These measurements are confirmed by signals from diamagnetic probes. The mean value of the energy in plasma volume in the process of the trap filling by plasma and during plasma decay have been determined by the magnitude of diamagnetic current. These measurements are carried out simultaneously with the measurement of the time dependence of mean plasma density by microwave interferometer.За допомогою поясу Роговського здійснено виміри діамагнітного струму, що виникає в плазмовому об’ємі мультипольної магнітної пастки-Галатеї "Трімікс-3М" при наповненні її плазмовими згустками. Ці виміри підтверджені сигналами з діамагнітних зондів. За величиною діамагнітного струму визначалася величина енергії в плазмовому об’ємі і її зміна в процесі заповнення пастки плазмою і її розпаду. Виміри проведено одночасно з вимірами за допомогою СВЧ-інтерферометра часової залежності середньої концентрації плазми.С помощью пояса Роговского произведены измерения диамагнитного тока, возникающего в плазменном объеме мультипольной магнитной ловушки-Галатеи «Тримикс-3М» при наполнении ее плазменными сгустками. Эти измерения подтверждены сигналами с диамагнитных зондов. По величине диамагнитного тока определялась величина энергии в плазменном объеме и ее изменение в процессе заполнения ловушки плазмой и её распада. Измерения проведены одновременно с измерением с помощью СВЧ-интерферометра временной зависимости средней концентрации плазмы

Healthcare-associated tubo-ovarian infections in Ukraine: results of a multicenter study (2020-2022)

To determine the current prevalence of healthcare-associated tubo-ovarian infections in female and antimicrobial resistance of the responsible pathogens in Ukraine

United classification of cosmic gamma-ray bursts and their counterparts

United classification of gamma-ray bursts and their counterparts is established on the basis of measured characteristics: photon energy E and emission duration T. The founded interrelation between the mentioned characteristics of events consists in that, as the energy increases, the duration decreases (and vice versa). The given interrelation reflects the nature of the phenomenon and forms the E-T diagram, which represents a natural classification of all observed events in the energy range from 10E9 to 10E-6 eV and in the corresponding interval of durations from about 10E-2 up to 10E8 s. The proposed classification results in the consequences, which are principal for the theory and practical study of the phenomenon.Comment: Keywords Gamma rays: burst

Fiber-Optic Thermosensor Based on Shape Memory Effect

A fiber-optic thermosensor using thin shape memory ribbons of rapidly quenched TiNiCu alloy as thermosensitive element is described. It is shown that the developed thermosensor is optically passive, resistant to corrosion and to radio and electromagnetic noise. Also it has a fast response (less than 1 sec), a high reliability and durability (more than 105 cycles), a small size and high simplicity of thermosensitive part. Its switching temperature can be varied in a wide region (273-353 K) with alloy composition

NEW DATA ON THE RESULTS OF THE MOLOGA-SHEKSNA LOWLAND LAKES RESEARCH (VOLOGDA REGION, RUSSIA)

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