644 research outputs found

    Emerging trends in entrepreneurial finance

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    The emergence of new sources of financing in the aftermath of the financial crisis has substantially increased the funding options available to new entrepreneurial ventures. Technology parks, startup incubators and accelerators, business angels and angel investment organizations, equity crowdfunding platforms, venture capital funds, corporate seed funds and institutional investors directly investing in new ventures, have significantly increased the menu of funding channels, in many cases by leveraging the disrupting effects of Fintech companies and the emergence of internet-based segments of the capital market. As a consequence, a new financing eco-system for new ventures has emerged in recent years that has significant implications for both investors and entrepreneurs, impacting on entrepreneurial growth paths and creating new policy challenges at both the national and global scales. The substantially larger set of funding channels has not only been instrumental in the unprecedented growth in the number of early stage companies but has also raised new questions that have challenged scholars and practitioners and policymakers alike. Idiosyncratic risk-return profiles and investment philosophies, unorthodox investment practices, innovative value-adding contributions to portfolio companies ventures and structurally different exit options are some of the areas that require urgent investigation. The first \u201cEmerging Trends in Entrepreneurial Finance\u201d Conference, 1\u20132 June 2017 organized by the Stevens School of Business, the University of Piemonte Orientale and the Editors of Venture Capital: an International Journal of Entrepreneurial Finance at the Stevens Institute of Technology (Hoboken, NJ, USA) with the sponsorship of Hanlon Financial Systems Center and the Stevens Venture Center, aimed at gathering world-class scholars in the field of entrepreneurial finance to stimulate a debate on the evolution of the financing ecosystem for new ventures. From the close to 75 submissions, of which 16 were accepted for presentation. the Guest Editors of this special Issue have selected six outstanding papers that address crucial topics and recent developments

    Excitonic Effects in Quantum Wires

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    We review the effects of Coulomb correlation on the linear and non-linear optical properties of semiconductor quantum wires, with emphasis on recent results for the bound excitonic states. Our theoretical approach is based on generalized semiconductor Bloch equations, and allows full three-dimensional multisubband description of electron-hole correlation for arbitrary confinement profiles. In particular, we consider V- and T-shaped structures for which significant experimental advances were obtained recently. Above band gap, a very general result obtained by this approach is that electron-hole Coulomb correlation removes the inverse-square-root single-particle singularity in the optical spectra at band edge, in agreement with previous reports from purely one-dimensional models. Strong correlation effects on transitions in the continuum are found to persist also at high densities of photoexcited carriers. Below bandgap, we find that the same potential- (Coulomb) to kinetic-energy ratio holds for quite different wire cross sections and compositions. As a consequence, we identify a shape- and barrier-independent parameter that governs a universal scaling law for exciton binding energy with size. Previous indications that the shape of the wire cross-section may have important effects on exciton binding are discussed in the light of the present results.Comment: Proc. OECS-5 Conference, G\"ottingen, 1997 (To appear in Phys. Stat. Sol. (b)

    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

    Nouvelles trappes à sédiment destinées aux milieux peu profonds vidangeables

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    Les mesures de taux de sĂ©dimentation en milieux aquatiques peu profonds sont rares et sont souvent rĂ©alisĂ©es Ă  l'aide de mĂ©thodes inadaptĂ©es. Les trappes Ă  sĂ©diment utilisĂ©es ont au minimum 25 cm de haut. Par consĂ©quent, pour beaucoup de milieux peu profonds, plus de 25 % de la colonne d'eau ne sont pas Ă©chantillonnĂ©s. Nous avons palliĂ© ce problĂšme en dĂ©veloppant un rĂ©ceptacle mis en place dans les sĂ©diments et destinĂ© Ă  recevoir des trappes Ă  sĂ©diment cylindriques. Le sommet des trappes peut alors ĂȘtre situĂ© Ă  moins de 5 cm de la surface des sĂ©diments. Ce systĂšme est utilisable pour des milieux de profondeur infĂ©rieure Ă  cinq mĂštres. Nos rĂ©sultats montrent que les trappes Ă  sĂ©diments gĂ©nĂ©ralement utilisĂ©es sous-estiment de 35 Ă  79 % du taux de sĂ©dimentation. Les particules nĂ©gligĂ©es proviennent des flux sĂ©dimentaires primaire et secondaire.Sediment traps are a unique tool that can be used to investigate particle settling flux throughout the water column, whereas other methods such as sediment dating can only measure accumulation rates of bottom sediments. Several works on trapping efficiency have shown that cylindrical traps with height/diameter ratio greater than to 5 (10 in turbulent systems) are the more appropriate instruments to correctly measure the downward settling flux of particulate matter. Furthermore, traps with a diameter narrower than 5 cm should be avoided. It is well documented that bottle-type vessels overestimate the settling sediment whereas funnels and flat containers underestimate it. All this support the idea that an ideal trap must be at least 25 cm high, and in this sense, numerous studies investigating shallow aquatic systems have neglected a large proportion of the water column. Consequently, mechanical and biological processes occurring in this layer of the water column have not been taken into accountWe have overcome this problem with a structure composed of two parts (figure 2).The first part is a receptacle (bucket) buried in the sediment and intended to receive cylindrical traps. The top of the receptacle is placed 2 cm above the sediment. A guide made of a rope covered with a PVC tube is placed in the centre of the receptacle. This receptacle is intended to receive cylindrical traps whose tops stand less than 5 cm higher than the surface of the sediments.The second part is composed of seven cylinders (height/diameter ratio=10) which are fixed in a PVC disc 600 mm in diameter and 15 mm deep. The cylinders are placed around the central axis of the PVC disc. The bottom of the cylinders is closed with a removable polyethylene cap. Another cylinder, through which the guide can slide, is placed on the central axis. The bottom part of this last cylinder is ballasted with concrete. The stability of this second part, during both deposition and removal steps, is ensured by the low density of the PVC disc, the ballast at the bottom of the central cylinder, and the symmetry of the structure. This removable part may be lifted from the receptacle with three 2 mm diameter ropes attached to the PVC disc and fixed to a float. This apparatus may be used as deep as five meters.The sediment traps were tested in two extensively-managed fish ponds in North-Eastern France. Our investigations showed that tubes with a diameter between 26 and 140 mm could be efficiently used to estimate the sedimentation rate, whereas cylinders with a narrower diameter missed a large amount of particles. The use of tubes with a diameter above 50 mm, which is preferable for the study of turbulent systems, seems to allow the collection of sufficient sediment during a short period of time. We selected tubes with a diameter of 57 mm, which made it possible to handle them easily during the removal. Our investigations showed that in turbulent systems and for high sedimentation rates (> 5 kg·m-2 ·month-1), the top of the cylinders must be placed 1 cm above the top of the PVC disc. When considering low sedimentation rates (< 5 kg·m-2 ·month-1), we did not observe any significant differences between the cylinders placed 0 and 1 cm above the PVC disc.Complementary investigations were conducted in order to compare sedimentation rates estimated 1) by the apparatus we designed, in which the top of the cylinders was placed 5 cm above the sediment surface, 2) by traditional traps (57 mm in diameter and a height/diameter ratio of 5) in which the top of the cylinders was 28.5 cm above the sediment surface.These results showed that in shallow systems (1.2 m deep), traditional traps underestimate the downward settling flux of particulate matter by 35 to 79%. Furthermore, we compared the organic matter content of the sediment collected by the two types of traps with the organic matter content of bottom sediment, suspended particles, and submerged macrophytes. Results showed that the underestimation of particles was not only due to the resuspension of bottom sediment, but also to the sedimentation of phytoplankton and submerged macrophyte fragments which are not collected by the traditional traps

    Multilayer Plasmonic Nanostructures for Improved Sensing Activities Using a FEM and Neurocomputing-Based Approach

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    In order to obtain optimized elementary devices (photovoltaic modules, power transistors for energy efficiency, high-efficiency sensors) it is necessary to increase the energy conversion efficiency of these devices. A very effective approach to achieving this goal is to increase the absorption of incident radiation. A promising strategy to increase this absorption is to use very thin regions of active material and trap photons near these surfaces. The most effective and cost-effective method of achieving such optical entrapment is the Raman scattering from excited nanoparticles at the plasmonic resonance. The field of plasmonics is the study of the exploitation of appropriate layers of metal nanoparticles to increase the intensity of radiation in the semiconductor by means of near-field effects produced by nanoparticles. In this paper, we focus on the use of metal nanoparticles as plasmonic nanosensors with extremely high sensitivity, even reaching single-molecule detection. The study conducted in this paper was used to optimize the performance of a prototype of a plasmonic photovoltaic cell made at the Institute for Microelectronics and Microsystems IMM of Catania, Italy. This prototype was based on a multilayer structure composed of the following layers: glass, AZO, metal and dielectric. In order to obtain good results, it is necessary to use geometries that orthogonalize the absorption of light, allowing better transport of the photocarriers—and therefore greater efficiency—or the use of less pure materials. For this reason, this study is focused on optimizing the geometries of these multilayer plasmonic structures. More specifically, in this paper, by means of a neurocomputing procedure and an electromagnetic fields analysis performed by the finite elements method (FEM), we established the relationship between the thicknesses of Aluminum-doped Zinc oxide (AZO), metal, dielectric and their main properties, characterizing the plasmonic propagation phenomena as the optimal wavelengths values at the main interfaces AZO/METAL and METAL/DIELECTRIC

    QGIS AND OPEN DATA CUBE APPLICATIONS FOR LOCAL CLIMATE ZONES ANALYSIS LEVERAGING PRISMA HYPERSPECTRAL SATELLITE DATA

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    Climate change poses a significant threat to humans and biodiversity, impacting various aspects of livelihoods, infrastructure, and ecosystems. Understanding climate change and its interaction with the environment is crucial for achieving Sustainable Development Goals. Local Climate Zones (LCZ) play a key role in comprehending climate change by categorizing urban areas also based on their thermal characteristics. This study presents prototype open-source software tools developed to integrate ground and satellite data for LCZ analysis in the Metropolitan City of Milan (Northern Italy). These tools consist of a QGIS plugin to access and preprocess ground-based meteorological sensor data and a client-server platform, based on the Open Data Cube and Docker technologies, for the exploitation of multispectral and hyperspectral satellite data in LCZ mapping and analysis. The tools’ architecture, data retrieval methods, and analysis capabilities are described in detail. The QGIS plugin facilitates the access and preprocessing of ground-based sensor data within the user-friendly QGIS environment. The platform enables seamless ground-sensor and satellite data management and analysis, using Jupyter Notebooks as an interface to support programmatic operations on the data. The proposed tools provide a framework for studying climate change and its local impacts on urban environments, with the potential of empowering users to effectively analyze and mitigate its effects

    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 Δ+/− 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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