296 research outputs found

    Angel network affiliation and business angels' investment practices

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    This paper provides preliminary evidence on the effects of membership in a business angel network (BAN) on the investment decisions of the members. Using a novel dataset containing qualitative and quantitative information on 810 angel or angel-group backed investments in 619 companies by 330 unique business angels from 2008 to 2014, we show that BAN membership generates valuable information, networking, monitoring, and risk reduction effects, which ultimately affect the share of personal wealth committed by each angel investor and their equity stake in the targeted company. These results extend our knowledge of the investment behavior and characteristics of business angels, a relatively opaque funding source that is rapidly gaining prominence in support of new ventures and the development of the global economy

    Spreading of a local excitation in a Quantum Hierarchical Model

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    We study the dynamics of the quantum Dyson hierarchical model in its paramagnetic phase. An initial state made by a local excitation of the paramagnetic ground state is considered. We provide analytical predictions for its time evolution, solving the single-particle dynamics on a hierarchical network. A localization mechanism is found and the excitation remains close to its initial position at arbitrary times. Furthermore, a universal scaling among space and time is found related to the algebraic decay of the interactions as r−1−σr^{-1-\sigma}. We compare our predictions to numerics, employing tensor network techniques, for large magnetic fields, discussing the robustness of the mechanism in the full many-body dynamics

    Site-Controlled Quantum Emitters in Dilute Nitrides and their Integration in Photonic Crystal Cavities

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    We review an innovative approach for the fabrication of site-controlled quantum emitters (i.e., single-photon emitting quantum dots) based on the spatially selective incorporation and/or removal of hydrogen in dilute nitride semiconductors (e.g., GaAsN). In such systems, the formation of stable N-H complexes removes the effects that nitrogen has on the alloy properties, thus enabling the in-plane engineering of the band bap energy of the system. Both a lithographic approach and/or a near-field optical illumination—coupled to the ultra-sharp diffusion profile of H in dilute nitrides—allow us to control the hydrogen implantation and/or removal on a nanometer scale. This, eventually, makes it possible to fabricate site-controlled quantum dots that are able to emit single photons on demand. The strategy for a deterministic spatial and spectral coupling of such quantum emitters with photonic crystal cavities is also presented

    TECNICHE DI RICOSTRUZIONE DELLA SUPERFICIE POSTERIORE DEL PADIGLIONE AURICOLARE E DELLAMASTOIDE CON LEMBI LOCALI

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    B a c k g ro u n d. Reconstruction of the posterior auricular surface and of the mastoid has never been given much attention and there are no techniques described. The authors describe two techniques for reconstruction of these areas after cancer excision with local flaps. M e t h o d s . 13 patients have been treated after cancer resection with an advancement flap from the posterior auricular surface and a bilobed flap from the mastoid. R e s u l t s. All flaps healed uneventfully with a satisfactory aesthetic outcome. No relevant complications have been o b s e r v e d . C o n c l u s i o n s. Reconstruction of the posterior auricular surface and of the mastoid with the techniques described allows satisfactory defect closure even in complex situations such as cartilage or bone exposure

    NECK DISSECTIONS: MISCONCEPTIONS, MALPRACTICE AND COMMON CONTROVERSIES

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    B a c k g ro u n d. Neck metastases are the single most important prognostic factor in Head and Neck Squamous Cell Carcinoma. Wise approach to neck treatment is then mandatory to give a chanche for cure. Still, there are some issues about neck dissection that need to be clarified. M e t h o d s. Through a review of the literature and of everyday clinical observations, the following issues are discussed: Functional Neck Dissection, biopsies, nodal levels, Selective Neck Dissections, Spinal Accessory Nerve, neck dissection classification. R e s u l t s. Integration of historical, anatomical, clinical and surgical concepts and up-to-date knowledge can allow to understand how to behave in diverse clinical situations. Conclusions. Standardized guidelines are far to be achieved. Wise behaviour, however, may allow to avoid some mistakes. The aim of this paper is to make the above mentioned issues clear and hopefully give more diffusion to concepts that too often seem to be overlooked

    Hydrogenation of GaSb/GaAs quantum rings

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    We present the results of photoluminescence measurements on hydrogenated type-II GaSb/GaAs quantum dot/ring (QD/QR) samples at temperatures ranging from 4.2K to 400 K. Hydrogenation is found to suppress optically induced charge depletion (associated with the presence of carbon acceptors in this system). A redshift of the QD\QR emission energy of a few tens of meV is observed at temperatures 300 K, consistent with a reduction in average occupancy by 1 hole. These effects are accompanied by a reduction in PL intensity post-hydrogenation. We conclude that although hydrogenation may have neutralized the carbon acceptors, multiple hole occupancy of type-II GaSb/GaAs QD/QRs is very likely a precondition for intense emission, which would make extending the wavelength significantly beyond 1300 nm at room temperature difficult

    MAPPING LOCAL CLIMATE ZONES WITH MULTIPLE GEODATA AND THE OPEN DATA CUBE: INSIGHTS OF DOMAIN USER REQUIREMENTS AND OUTLOOKS OF THE LCZ-ODC PROJECT

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    Rapid urbanization and climate change are intensifying the urban heat island (UHI) phenomenon across cities worldwide. There is a pressing need to implement evidence-based mitigation and adaptation strategies as well as to develop tools for effectively measuring the impact of such actions on UHI patterns. In this context, the Local Climate Zone (LCZ) concept is a well-established classification system commonly used for the assessment of UHI. With this in mind, we present here the LCZ-ODC project aiming to develop a methodology for LCZ mapping in the Metropolitan City of Milan (northern Italy) by leveraging multiple geospatial data and cutting-edge software tools, including the Open Data Cube (ODC). A key aim of the project is to develop user-oriented solutions facilitating the exploitation of the generated LCZ maps for different application tasks. In this paper, we first present a brief overview of the methodologies and data sources used in the literature for LCZ mapping. Then, we introduce the LCZ-ODC project, with a focus on the end-user requirements which were gathered through a questionnaire distributed to a sample of potential stakeholders. The primary objective of the survey was to collect insights and consolidate requirements related to the key features of LCZ maps that will be produced within the project. The outcomes of the survey play a pivotal role in guiding the project’s development phase, ensuring that the project outputs will effectively address the identified end-user needs

    Optical detection and spatial modulation of mid-infrared surface plasmon polaritons in a highly doped semiconductor

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    Highly doped semiconductors (HDSCs) are promising candidates for plasmonic applications in the mid-infrared (MIR) spectral range. This work examines a recent addition to the HDSC family, the dilute nitride alloy In(AsN). Post-growth hydrogenation of In(AsN) creates a highly conducting channel near the surface and a surface plasmon polariton detected by attenuated total reflection techniques. The suppression of plasmonic effects following a photo-annealing of the semiconductor is attributed to the dissociation of the N-H bond. This offers new routes for direct patterning of MIR plasmonic structures by laser writing

    Peculiarities of the hydrogenated In(AsN) alloy

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    The electronic properties of In(AsN) before and after post-growth sample irradiation with increasing doses of atomic hydrogen have been investigated by photoluminescence. The electron density increases in In(AsN) but not in N-free InAs, until a Fermi stabilization energy is established. A hydrogen ε+/− transition level just below the conduction band minimum accounts for the dependence of donor formation on N, in agreement with a recent theoretical report highlighting the peculiarity of InAs among III–V compounds. Raman scattering measurements indicate the formation of N–H complexes that are stable under thermal annealing up to ∼500 K. Finally, hydrogen does not passivate the electronic activity of N, thus leaving the band gap energy of In(AsN) unchanged, once more in stark contrast to what has been reported in other dilute nitride alloys
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