The role of subsidies in promoting italian joint ventures in least developed and transition economies

This paper analyses the impact of subsidies to promote Italian joint ventures (JVs) with firms in LDC and transition economies. The empirical analysis is carried out on a unique dataset of 172 JVs interviewed during 1998 by means of a closed-answer qualitative-quantitative questionnaire. The main finding of the study is that although there is a significant deadweight component in incentive policy, subsidised firms are significantly more likely to grow. Moreover, JVs comprising new firms (which need to grow to survive) also achieve a higher-than- average employment performance, and so too do (labour intensive) JVs motivated by the search for lower labour costs, and JVs in East European countries

Testing Local Lorentz and Position Invariance and Variation of Fundamental Constants by searching the Derivative of the Comparison Frequency Between a Cryogenic Sapphire Oscillator and Hydrogen Maser

The cryogenic sapphire oscillator (CSO) at the Paris Observatory has been continuously compared to various Hydrogen Masers since 2001. The early data sets were used to test Local Lorentz Invariance in the Robertson-Mansouri-Sexl (RMS) framework by searching for sidereal modulations with respect to the Cosmic Microwave Background, and represent the best Kennedy-Thorndike experiment to date. In this work we present continuous operation over a period of greater than six years from September 2002 to December 2008 and present a more precise way to analyze the data by searching the time derivative of the comparison frequency. Due to the long-term operation we are able to search both sidereal and annual modulations. The results gives P_{KT} = \beta_{RMS}-\alpha_{RMS}-1 = -1.7(4.0) \times 10^{-8} for the sidereal and -23(10) \times 10^{-8} for the annual term, with a weighted mean of -4.8(3.7) \times 10^{-8}, a factor of 8 better than previous. Also, we analyze the data with respect to a change in gravitational potential for both diurnal and annual variations. The result gives \beta_{H-Maser} - \beta_{CSO} = -2.7(1.4) \times 10^{-4} for the annual and -6.9(4.0) \times 10^{-4} for the diurnal terms, with a weighted mean of -3.2(1.3) \times 10^{-4}. This result is two orders of magnitude better than other tests that use electromagnetic resonators. With respect to fundamental constants a limit can be provided on the variation with ambient gravitational potential and boost of a combination of the fine structure constant (\alpha), the normalized quark mass (m_q), and the electron to proton mass ratio (m_e/m_p), setting the first limit on boost dependence of order 10^{-10}.Comment: Fixed typo

A new technique for thermal resistance measurement in power electron devices

A simple technique is proposed for the thermal resistance measurement of electron devices. The new approach is based on the standard measurements which are normally carried out for the electrical characterization of power devices, without requiring special-purpose instrumentation and/or physics-based temperature-dependent electrical device models. Experimental results, which confirm the validity of the new method, are provided

Ultralow frequency noise laser by locking to an optical fiber delay line

International audienceWe report the frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto optic modulator allowing heterodyne detection. The frequency noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz^2/Hz over the whole range. It reaches 10^{-2} Hz^2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the frequency noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple and compact alternative to cavity stabilization for short term linewidth reduction

Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules

High-resolution optical frequency dissemination on a telecommunication network with data traffic

We transferred the frequency of an ultra-stable laser over a 108 km urban fiber link comprising 22 km of optical communications network fiber simultaneously carrying Internet data traffic. The metrological signal and the digital data signal are transferred on two different frequency channels in a dense wavelength division multiplexing scheme. The metrological signal is inserted into and extracted from the communications network by using bidirectional off-the-shelf optical add-drop multiplexers. The link-induced phase noise is measured and cancelled with round-trip technique using an all-fiber-based interferometer. The compensated link shows an Allan deviation of a few 10-16 at one second and below 10-19 at 10,000 seconds. This opens the way to a wide dissemination of ultra stable optical clock signals between distant laboratories via the Internet network

I.C.E.: a Transportable Atomic Inertial Sensor for Test in Microgravity

We present our the construction of an atom interferometer for inertial sensing in microgravity, as part of the I.C.E. (\textit{Interf\'{e}rom\'{e}trie Coh\'{e}rente pour l'Espace}) collaboration. On-board laser systems have been developed based on fibre-optic components, which are insensitive to mechanical vibrations and acoustic noise, have sub-MHz linewidth, and remain frequency stabilised for weeks at a time. A compact, transportable vacuum system has been built, and used for laser cooling and magneto-optical trapping. We will use a mixture of quantum degenerate gases, bosonic $^{87}$Rb and fermionic $^{40}$K, in order to find the optimal conditions for precision and sensitivity of inertial measurements. Microgravity will be realised in parabolic flights lasting up to 20s in an Airbus. We show that the factors limiting the sensitivity of a long-interrogation-time atomic inertial sensor are the phase noise in reference frequency generation for Raman-pulse atomic beam-splitters and acceleration fluctuations during free fall

Accurate pHEMT nonlinear modeling in the presence of low-frequency dispersive effects

Low-frequency (LF) dispersive phenomena due to device self-heating and/or the presence of "traps" (i.e., surface state densities and bulk spurious energy levels) must be taken into account in the large-signal dynamic modeling of III-V field-effect transistors when accurate performance predictions are pursued, since these effects cause important deviations between direct current (dc) and dynamic drain current characteristics. In this paper, a new model for the accurate characterization of these phenomena above their cutoff frequencies is presented, which is able to fully exploit, in the identification phase, large-signal current-voltage (I-V) measurements carried out under quasi-sinusoidal regime using a recently proposed setup. Detailed experimental results for model validation under LF small- and large-signal operating conditions are provided. Furthermore, the I-V model proposed has been embedded into a microwave large-signal pseudomorphic high electron-mobility transistor (pHEMT) model in order to point out the strong influence of LF modeling on the degree of accuracy achievable under millimeter-wave nonlinear operation. Large-signal experimental validation at microwave frequencies is provided for the model proposed, by showing the excellent intermodulation distortion (IMD) predictions obtained with different loads despite the very low power level of IMD products involved. Details on the millimeter-wave IMD measurement setup are also provided. Finally, IMD measurements and simulations on a Ka-band highly linear power amplifier, designed by Ericsson using the Triquint GaAs 0.25-/spl mu/m pHEMT process, are shown for further model validation

Tackling the Limits of Optical Fiber Links

International audienceWe theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. We derive the unsuppressed delay noise for three configurations of optical links: two-way method, Sagnac interferometry, and actively compensated link, respectively designed for frequency comparison, rotation sensing, and frequency transfer. We also consider an alternative two-way setup allowing real-time frequency comparison and demonstrate its effectiveness on a proof-of-principle experiment with a 25-km fiber spool. For these three configurations, we analyze the noise arising from uncommon fiber paths in the interferometric ensemble and design optimized interferometers. We demonstrate interferometers with very low temperature sensitivity of respectively -2.2, -0.03 and 1 fs/K. We use one of these optimized interferometers on a long haul compensated fiber link of 540 km. We obtain a relative frequency stability of 3x10^-20 after 10,000 s of integration time