248 research outputs found

    How do venture capitalists inform their investors on the investment portfolio? An empirical investigation of the Belgian private equity market.

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    Venture capital investments are valued for a variety of reasons. In particular, venture capital managers periodically need to reconsider the valuation of the investment portfolio in view of their proper corporate disclosure activities. After all, investors in venture capital funds require such valuation information to assess the value of their investment in the venture capital fund and to appraise the performance of the venture capital fund's management. How the valuation is determined as well as what information disclosing the valuation process is reported remains obviously a controversial subject. Nonetheless, one can identify two distinct levels of guidance regarding the valuation and reporting problem with which venture capitalists are confronted. On the one hand, they are subject, just as any other company, to the accounting and corporate regulation. On the other hand, a set of more detailed and specific guidelines was issued by the industry itself. Whereas an earlier study (Thoen, 2002) discussed in detail the precise consequences following from this double set of prescriptions and recommendations for practitioners, the objective of the present study was to examine the actual business practice. In fact, we were interested in testing the extent to which Belgian venture capitalists comply with both sets of requirements and guidelines. Therefore, an empirical study was carried out by means of a survey, the main results of which are discussed here.Accounting; Companies; Disclosure; Empirical study; Industry; Information; Investment; Investment portfolio; Investments; Management; Managers; Market; Performance; Portfolio; Processes; Recommendations; Regulation; Reporting; Requirements; Studies; Valuation; Value; Venture capital;

    Probing dynamics of an electron-spin ensemble via a superconducting resonator

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    We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing magnetic field (80-300 mT). Measurements exploit mode- and temperature-dependent coupling of hyperfine-split sub-ensembles to the resonator. Temperature-independent spin linewidth and relaxation time suggest that spin diffusion limits spin relaxation. Depolarization of one sub-ensemble by resonant pumping of another indicates fast cross-relaxation compared to spin diffusion, with implications on use of sub-ensembles as independent quantum memories.Comment: 5 pages, 5 figures, and Supplementary Information (2 figures

    Development and testing of a fast fourier transform high dynamic-range spectral diagnostics for millimeter wave characterization

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    A fast Fourier transform (FFT) based wide range millimeter wave diagnostics for spectral characterization of scattered millimeter waves in plasmas has been successfully brought into operation. The scattered millimeter waves are heterodyne downconverted and directly digitized using a fast analog-digital converter and a compact peripheral component interconnect computer. Frequency spectra are obtained by FFT in the time domain of the intermediate frequency signal. The scattered millimeter waves are generated during high power electron cyclotron resonance heating experiments on the TEXTOR tokamak and demonstrate the performance of the diagnostics and, in particular, the usability of direct digitizing and Fourier transformation of millimeter wave signals. The diagnostics is able to acquire 4 GHz wide spectra of signals in the range of 136-140 GHz. The rate of spectra is tunable and has been tested between 200 000 spectra/s with a frequency resolution of 100 MHz and 120 spectra/s with a frequency resolution of 25 kHz. The respective dynamic ranges are 52 and 88 dB. Major benefits of the new diagnostics are a tunable time and frequency resolution due to postdetection, near-real time processing of the acquired data. This diagnostics has a wider application in astrophysics, earth observation, plasma physics, and molecular spectroscopy for the detection and analysis of millimeter wave radiation, providing high-resolution spectra at high temporal resolution and large dynamic range

    Ultrafast optical generation of coherent phonons in CdTe1-xSex quantum dots

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    We report on the impulsive generation of coherent optical phonons in CdTe0.68Se0.32 nanocrystallites embedded in a glass matrix. Pump probe experiments using femtosecond laser pulses were performed by tuning the laser central energy to resonate with the absorption edge of the nanocrystals. We identify two longitudinal optical phonons, one longitudinal acoustic phonon and a fourth mode of a mixed longitudinal-transverse nature. The amplitude of the optical phonons as a function of the laser central energy exhibits a resonance that is well described by a model based on impulsive stimulated Raman scattering. The phases of the coherent phonons reveal coupling between different modes. At low power density excitations, the frequency of the optical coherent phonons deviates from values obtained from spontaneous Raman scattering. This behavior is ascribed to the presence of electronic impurity states which modify the nanocrystal dielectric function and, thereby, the frequency of the infrared-active phonons

    El pie de un diabético

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    Paciente de 38 años de edad, con antecedentes personales de diabetes mellitus tipo 1 desde los 14 años e IRC en tratamiento en diálisis, que acude a nuestra unidad en mayo del 2005 por UPP en sacro de III grado (clasificación de la National pressure ulcer advisorypanel), y dehiscencia quirúrgica necrosada en pierna izquierda por safenectomía y ya ambas cicatrizada. El paciente tiene un largo historial clínico debido a su enfermedad metabólica y a la mala aceptación de la misma desde que era joven. En los informes se hacen varias referencias a este hecho: era fumador, no acudía a las revisiones con el endocrino, no se realizaba controles sistemáticos de lo niveles de glucemia, ni llevaba una dieta acorde con su enfermedad. Todos estos hechos favorecieron la aparición precoz de las consecuencias derivadas de la diabetes: vasculopatía de pequeños y de grandes vasos.Enfermerí

    Superconducting Coplanar Waveguide Filters for Submillimeter Wave On-Chip Filterbank Spectrometers

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    We show the first experimental results which prove that superconducting NbTiN coplanar-waveguide resonators can achieve a loaded Q factor in excess of 800 in the 350 GHz band. These resonators can be used as narrow band pass filters for on-chip filter bank spectrometers for astronomy. Moreover, the low-loss coplanar waveguide technology provides an interesting alternative to microstrip lines for constructing large scale submillimeter wave electronics in general
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