550 research outputs found

    Spherical and cylindrical particle resonator as a cloak system

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    The concept of dielectric spherical or cylindrical particle in resonant mode as a cloak system is offered. In fundamental modes (modes with the smallest volume correspond to |m| = l, and s = 1) the field is concentrated mostly in the equatorial plane and at the surface of the sphere. Thus under resonance modes, such perturbation due to cuboid particle inserted in the spherical or cylindrical particle has almost no effect on the field forming resonance regardless of the value of internal particle material (defect) as long as this material does not cover the region where resonance takes place

    Using genotype abundance to improve phylogenetic inference

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    Modern biological techniques enable very dense genetic sampling of unfolding evolutionary histories, and thus frequently sample some genotypes multiple times. This motivates strategies to incorporate genotype abundance information in phylogenetic inference. In this paper, we synthesize a stochastic process model with standard sequence-based phylogenetic optimality, and show that tree estimation is substantially improved by doing so. Our method is validated with extensive simulations and an experimental single-cell lineage tracing study of germinal center B cell receptor affinity maturation

    'Photonic Hook' based optomechanical nanoparticle manipulator

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    Specialized electromagnetic fields can be used for nanoparticle manipulation along a specific path, allowing enhanced transport and control over the particle’s motion. In this paper, we investigate the optical forces produced by a curved photonic jet, otherwise known as the “photonic hook”, created using an asymmetric cuboid. In our case, this cuboid is formed by appending a triangular prism to one side of a cube. A gold nanoparticle immersed in the cuboid’s transmitted field moves in a curved trajectory. This result could be used for moving nanoparticles around obstacles; hence we also consider the changes in the photonic hook’s forces when relatively large glass and gold obstacles are introduced at the region where the curved photonic jet is created. We show, that despite the obstacles, perturbing the field distribution, a particle can move around glass obstacles of a certain thickness. For larger glass slabs, the particle will be trapped stably near it. Moreover, we noticed that a partial obstruction of the photonic jet’s field using the gold obstacle results in a complete disruption of the particle’s trajectory

    Importance of private and communal lands to sustainable conservation of Africa's rhinoceroses

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    A new path for rhinoceros (rhino) conservation is needed. Recent data signal the alarming impact of poaching on populations in Africa's rhino stronghold, the state-run Kruger National Park (South Africa), which today supports one quarter the rhinos than a decade ago. We aggregated African rhino population data, highlighting the growing role of private and community rhino custodians, who likely now conserve >50% of Africa's rhinos. Their contribution has been enabled by a supportive policy and economic environment, but this arrangement is becoming more difficult to sustain as costs associated with protecting rhinos skyrocket and revenue-generating options become insufficient. Some privately held rhino populations are small or intensively managed, raising questions about their conservation value. As the role of private and community custodianship becomes increasingly central to the protection of Africa's remaining rhinos, its resilience must be strengthened through implementation of adaptive policies that incentivize rhino conservation. We outline policy pathways to provide an enabling environment for rhino conservation beyond state parks.Peer reviewe

    3D CAMERAS ACQUISITIONS FOR THE DOCUMENTATION OF CULTURAL HERITAGE

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    Abstract. Photography has always been considered as a valid tool to acquire information about reality. Nowadays, its versatility, together with the development of new techniques and technologies, allows to use it in different fields of application. Particularly, in the digitization of built heritage, photography not only enables to understand and document historical and architectural artifacts but also to acquire morphological and geometrical data about them with automated digital photogrammetry. Nowadays, photogrammetry enables many tools to give virtual casts of reality by showing it in the way of point cloud. Although they can have metric reliability and visual quality, traditional instruments &amp;ndash; such as monoscopic cameras &amp;ndash; involve a careful planning of the campaign phase and a long acquisition and processing time. On the contrary, the most recent ones, based on the integration of different sensors and cameras, try to reduce the gap between time and results. The latter include some systems of indoor mapping who, thanks to 360&amp;deg; acquisitions and SLAM technology, reconstruct the original scene in real time in great detail and with a photorealistic rendering. This study is aimed at reporting a research evaluating metric reliability and the level of survey detail with a Matterport Pro2 3D motorized rotating camera, equipped with SLAM technology, whose results have been compared with point clouds obtained by image-based and range-based processes.</p
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