Temperature dependent graphene suspension due to thermal Casimir interaction

Thermal effects contributing to the Casimir interaction between objects are usually small at room temperature and they are difficult to separate from quantum mechanical contributions at higher temperatures. We propose that the thermal Casimir force effect can be observed for a graphene flake suspended in a fluid between substrates at the room temperature regime. The properly chosen materials for the substrates and fluid induce a Casimir repulsion. The balance with the other forces, such as gravity and buoyancy, results in a stable temperature dependent equilibrium separation. The suspended graphene is a promising system due to its potential for observing thermal Casimir effects at room temperature.Comment: 5 pages, 4 figures, in APL production 201

Strong exciton-plasmon coupling in semiconducting carbon nanotubes

We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong exciton-surface-plasmon coupling. The exciton absorption line shape exhibits Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. We also show that the quantum confined Stark effect may be used as a tool to control the exciton binding energy and the nanotube band gap in carbon nanotubes in order, e.g., to bring the exciton total energy in resonance with the nearest interband plasmon mode. The exciton-plasmon Rabi splitting we predict here for an individual carbon nanotube is close in its magnitude to that previously reported for hybrid plasmonic nanostructures artificially fabricated of organic semiconductors on metallic films. We expect this effect to open up paths to new tunable optoelectronic device applications of semiconducting carbon nanotubes.Comment: 22 pages, 8 figures, accepted for PR

Spontaneous decay of excited atomic states near a carbon nanotube

Spontaneous decay process of an excited atom placed inside or outside (near the surface) a carbon nanotube is analyzed. Calculations have been performed for various achiral nanotubes. The effect of the nanotube surface has been demonstrated to dramatically increase the atomic spontaneous decay rate -- by 6 to 7 orders of magnitude compared with that of the same atom in vacuum. Such an increase is associated with the nonradiative decay via surface excitations in the nanotube.Comment: 8 pages, 3 figure

Структура нерестової популяції ляща (Abramis brama) водойм Дніпровсько-Орільського природного заповідника

The population state of important food fish Abramis brama L. in the Dniprovsko-Orelsky Nature Reserve is under consideration . Basic population parameters of the species have been studied. Assessment of modern state and determination of perspectives of further existence of the roach in the Reserve’s basins have been done

Population structure of the spawning roach Rutilus rutilus in water bodies of the Dniprovs’ko-Orilsky nature reserve

Розглянуто стан популяції фонового виду іхтіофауни заповідника – Rutilus rutilus Linnaeus, 1758. Вивчено базові популяційні параметри виду. Надано оцінку сучасному стану та визначено перспективи подальшого існування плітки у водоймах заповідника.Розглянуто стан популяції фонового виду іхтіофауни заповідника – Rutilus rutilus Linnaeus, 1758. Вивчено базові популяційні параметри виду. Надано оцінку сучасному стану та визначено перспективи подальшого існування плітки у водоймах заповідника.The population state of Rutilus rutilus Linnaeus, 1758, which is a common species in the reserve, is under consideration. Basic population parameters of the species have been studied. Assessment of modern state and determination of further perspectives of the roach existence in the reserve’s basins have been done

Структура нерестової популяції ляща (Abramis brama) водойм Дніпровсько-Орільського природного заповідника

The population state of important food fish Abramis brama L. in the Dniprovsko-Orelsky Nature Reserve is under consideration . Basic population parameters of the species have been studied. Assessment of modern state and determination of perspectives of further existence of the roach in the Reserve’s basins have been done.Розглянуто стан популяції цінного промислового виду іхтіофауни Дніпровського водосховища – Abramis brama Linnaeus, 1758 на акваторії Дніпровсько-Орільського природного заповідника. Визначено основні популяційні характеристики виду у водоймах заповідника. Надано оцінку сучасному стану нерестової популяції та розглянуто перспективи подальшого існування ляща на акваторії заповідника. Розглянуто стан популяції цінного промислового виду іхтіофауни Дніпровського водосховища – Abramis brama Linnaeus, 1758 на акваторії Дніпровсько-Орільського природного заповідника. Визначено основні популяційні характеристики виду у водоймах заповідника. Надано оцінку сучасному стану нерестової популяції та розглянуто перспективи подальшого існування ляща на акваторії заповідника.

Фауна риб прибережної зони дншровсько-орільського заповідника на сучасному етапі розвитку Іхтюценозу

Status of groups of coastal fish in water bodies ofthenaturereserve, anddynamicsoftheirquantitativeandqualitativeparameters isconsidered. Responses of fish communities to changes occurring in floodplain lakes were recorded,with thedeterminationoftheirunderlyingfactors, andmeasuresonmaintaininghomeostasis of this group of aquatic organisms and optimizationoftheirrecoveryandreproductionarerecommended.Розглянуто стан угруповань риб прибережної зони водойм заповідника, динаміку їх кількі- сних та якісних параметрів. Відмічено реакції іхтіоценозів на зміни, які відбуваються в заплав- них озерах, та визначено вплив факторів, що їх обумовлюють. Рекомендовано заходи щодо під- тримки гомеостазу цієї групи водних організмів та оптимізаціїїх відновлення і відтворення.Розглянуто стан угруповань риб прибережної зони водойм заповідника, динаміку їх кількі- сних та якісних параметрів. Відмічено реакції іхтіоценозів на зміни, які відбуваються в заплав- них озерах, та визначено вплив факторів, що їх обумовлюють. Рекомендовано заходи щодо під- тримки гомеостазу цієї групи водних організмів та оптимізаціїїх відновлення і відтворення

Automated Generation of Instance Segmentation Labels for Traffic Surveillance Models

This paper focuses on instance segmentation and object detection for real-time traffic surveillance applications. Although instance segmentation is currently a hot topic in literature, no suitable dataset for traffic surveillance applications is publicly available and limited work is available with real-time performance. A custom proprietary dataset is available for training, but it contains only bounding-box annotations and lacks segmentation annotations. The paper explores methods for automated generation of instance segmentation labels for custom datasets that can be utilized to finetune state-of-the-art segmentation models to specific application domains. Real-time performance is obtained by adopting the recent YOLACT instance segmentation with the YOLOv7 backbone. Nevertheless, it requires modification of the loss function and an implementation of ground-truth matching to overcome handling imperfect instance labels in custom datasets. Experiments show that it is possible to achieve a high instance segmentation performance using a semi-automatically generated dataset, especially when using the Segment Anything Model for generating the labels.</p

Triboelectric Backgrounds to radio-based UHE Neutrino Exeperiments

The triboelectric effect broadly includes any process in which force applied at a boundary layer results in displacement of surface charge, leading to the generation of an electrostatic potential. Wind blowing over granular surfaces, such as snow, can induce a potential difference, with subsequent coronal discharge. Nanosecond timescale discharges can lead to radio-frequency emissions with characteristics similar to piezoelectric-induced discharges. For Antarctic-sited experiments seeking detection of radio-frequency signals generated by collisions of cosmic rays or neutrinos with atmospheric or englacial molecular targets, triboelectric emissions from the surface pose a potential background. This is particularly true for experiments in which radio antennas are buried ~(1--100) m below the snow surface, and seeking to validate neutrino detection strategies by measurement of down-coming radio-frequency emissions from extensive air showers. Herein, after summarizing extant evidence for wind-induced triboelectric effects previously reported elsewhere, we detail additional analysis using archival data collected with the RICE and AURA experiments at the South Pole. We broadly characterize those radio-frequency emissions based on source location, and time-domain and also frequency-domain characteristics. We find that: a) For wind velocities in excess of 10-12 m/s, triboelectric background triggers can dominate data-taking, b) frequency spectra for triboelectric events are generally shifted to the low-end of the regime to which current radio experiments are typically sensitive (100-200 MHz), c) there is an apparent preference for tribo-electric discharges from metal surface structures, consistent with a model in which localized, above-surface structures provide a repository for transported charge