Utilisation of Processing and Stability Maps in the Definition of the Hot Forming Condition of Al-MMCs

none3P. CAVALIERE; FORCELLESE A; ROBERTS S.MCavaliere, Pasquale Daniele; Forcellese, A; Roberts, S. M

Static and Dynamic Analysis of Magnetic Tunnel Junctions With Wedged MgO Barrier

partially_open11This paper deals with the experimental characterization of CoFeB-based magnetic tunnel junctions with wedged MgO barrier. We perform both static hysteresis loop measurements by means of an alternating gradient force magnetometer and magnetization dynamics analysis via vector network analyzer ferromagnetic resonance spectroscopy in a wide field range. The results, supported by theoretical models based on coherent rotation assumption, put in evidence the role of the tunnel barrier thickness on the exchange coupling between free and reference layers. In presence of strong ferromagnetic interaction, the easy-axis hysteresis loop does not exhibit the typical low-field plateau associated with antiparallel alignment, indicating a simultaneous reversal of the two layers. Moreover, a stronger asymmetry is observed in the ferromagnetic resonance spectrum map at low bias fields.partially_openCaprile, A.; Manzin, A.; Coisson, M.; Pasquale, M; Schumacher, ; Hw, H.W.; Liebing, N.; Sievers, S.; Ferreira, R.; Serrano-Guisan, S.; Paz, E.Caprile, A.; Manzin, Alessandra; Coisson, Marco; Pasquale, Massimo; Schumacher, ; Hw, H. W.; Liebing, N.; Sievers, S.; Ferreira, R.; Serrano Guisan, S.; Paz, E

The "plus" side of epilepsy phenotyping

No abstract available

The late-time afterglow of the extremely energetic short burst GRB 090510 revisited

The discovery of the short GRB 090510 has raised considerable attention mainly because it had a bright optical afterglow and it is among the most energetic events detected so far within the entire GRB population. The afterglow was observed with swift/UVOT and swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to an excess of optical flux at late times. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times.Comment: submitted to Astronomy & Astrophysics, accepted for publication on Dec 24, 201

Redescribing Health Privacy: The Importance of Health Policy

Current conversations about health information policy often tend to be based on three broad assumptions. First, many perceive a tension between regulation and innovation. We often hear that privacy regulations are keeping researchers, companies, and providers from aggregating the data they need to promote innovation. Second, aggregation of fragmented data is seen as a threat to its proper regulation, creating the risk of breaches and other misuse. Third, a prime directive for technicians and policymakers is to give patients ever more granular methods of control over data. This article questions and complicates those assumptions, which I deem (respectively) the Privacy Threat to Research, the Aggregation Threat to Privacy, and the Control Solution. This article is also intended to enrich our concepts of “fragmentation” and “integration” in health care. There is a good deal of sloganeering around “firewalls” and “vertical integration” as idealized implementations of “fragmentation” and “integration” (respective). The problem, though, is that terms like these (as well as “disruption”) are insufficiently normative to guide large-scale health system change. They describe, but they do not adequately prescribe. By examining those instances where: a) regulation promotes innovation, and b) increasing (some kinds of) availability of data actually enhances security, confidentiality, and privacy protections, this article attempts to give a richer account of the ethics of fragmentation and integration in the U.S. health care system. But, it also has a darker side, highlighting the inevitable conflicts of values created in a “reputation society” driven by stigmatizing social sorting systems. Personal data control may exacerbate social inequalities. Data aggregation may increase both our powers of research and our vulnerability to breach. The health data policymaking landscape of the next decade will feature a series of intractable conflicts between these important social values

Time and frequency pump-probe multiplexing to enhance the signal response of Brillouin optical time-domain analyzers

© 2014 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibitedA technique to enhance the response and performance of Brillouin distributed fiber sensors is proposed and experimentally validated. The method consists in creating a multi-frequency pump pulse interacting with a matching multi-frequency continuous-wave probe. To avoid nonlinear cross-interaction between spectral lines, the method requires that the distinct pump pulse components and temporal traces reaching the photodetector are subject to wavelength-selective delaying. This way the total pump and probe powers launched into the fiber can be incrementally boosted beyond the thresholds imposed by nonlinear effects. As a consequence of the multiplied pump-probe Brillouin interactions occurring along the fiber, the sensor response can be enhanced in exact proportion to the number of spectral components. The method is experimentally validated in a 50 km-long distributed optical fiber sensor augmented to 3 pump-probe spectral pairs, demonstrating a signal-to-noise ratio enhancement of 4.8 dB.The authors would like to thank Mr. Javier Urricelqui from Universidad Publica de Navarra (Spain) for the valuable discussions and help in relation to the noise characteristics of BOTDA sensors. This work was performed in the framework and with the support of the COST Action TD1001 OFSeSa. M. A. Soto and L. Thevenaz acknowledge the support from the Swiss Commission for Technology and Innovation (Project 13122.1), and from the Swiss State Secretariat for Education, Research and Innovation (SERI) through the project COST C10.0093. UPVLC group acknowledges the support from the Spanish MICINN and the Valencia Government through the projects TEC2011-29120-C05-05 and ACOMP/2013/146, respectively. L. Zhang acknowledges the support from the China Scholarship Council during his stay at EPFL in Switzerland.Soto, MA.; Ricchiuti, AL.; Zhang, L.; Barrera Vilar, D.; Sales Maicas, S.; Thevenaz, L. (2014). Time and frequency pump-probe multiplexing to enhance the signal response of Brillouin optical time-domain analyzers. Optics Express. 22(23):28584-28595. https://doi.org/10.1364/OE.22.028584S28584285952223Horiguchi, T., Shimizu, K., Kurashima, T., Tateda, M., & Koyamada, Y. (1995). Development of a distributed sensing technique using Brillouin scattering. Journal of Lightwave Technology, 13(7), 1296-1302. doi:10.1109/50.400684Soto, M. A., & Thévenaz, L. (2013). Modeling and evaluating the performance of Brillouin distributed optical fiber sensors. Optics Express, 21(25), 31347. doi:10.1364/oe.21.031347Foaleng, S. M., & Thévenaz, L. (2011). Impact of Raman scattering and modulation instability on the performances of Brillouin sensors. 21st International Conference on Optical Fiber Sensors. doi:10.1117/12.885105Alem, M., Soto, M. A., & Thévenaz, L. (2014). Modelling the depletion length induced by modulation instability in distributed optical fibre sensors. 23rd International Conference on Optical Fibre Sensors. doi:10.1117/12.2058862Thévenaz, L., Mafang, S. F., & Lin, J. (2013). Effect of pulse depletion in a Brillouin optical time-domain analysis system. Optics Express, 21(12), 14017. doi:10.1364/oe.21.014017Minardo, A., Bernini, R., & Zeni, L. (2009). A Simple Technique for Reducing Pump Depletion in Long-Range Distributed Brillouin Fiber Sensors. IEEE Sensors Journal, 9(6), 633-634. doi:10.1109/jsen.2009.2019372Soto, M. A., Bolognini, G., Di Pasquale, F., & Thévenaz, L. (2010). Simplex-coded BOTDA fiber sensor with 1 m spatial resolution over a 50 km range. Optics Letters, 35(2), 259. doi:10.1364/ol.35.000259Soto, M. A., Bolognini, G., & Di Pasquale, F. (2010). Analysis of pulse modulation format in coded BOTDA sensors. Optics Express, 18(14), 14878. doi:10.1364/oe.18.014878Rodriguez-Barrios, F., Martin-Lopez, S., Carrasco-Sanz, A., Corredera, P., Ania-Castanon, J. D., Thevenaz, L., & Gonzalez-Herraez, M. (2010). Distributed Brillouin Fiber Sensor Assisted by First-Order Raman Amplification. Journal of Lightwave Technology, 28(15), 2162-2172. doi:10.1109/jlt.2010.2051141Martin-Lopez, S., Alcon-Camas, M., Rodriguez, F., Corredera, P., Ania-Castañon, J. D., Thévenaz, L., & Gonzalez-Herraez, M. (2010). Brillouin optical time-domain analysis assisted by second-order Raman amplification. Optics Express, 18(18), 18769. doi:10.1364/oe.18.018769Soto, M. A., Bolognini, G., & Di Pasquale, F. (2011). Optimization of long-range BOTDA sensors with high resolution using first-order bi-directional Raman amplification. Optics Express, 19(5), 4444. doi:10.1364/oe.19.004444Soto, M. A., Taki, M., Bolognini, G., & Pasquale, F. D. (2012). Simplex-Coded BOTDA Sensor Over 120-km SMF With 1-m Spatial Resolution Assisted by Optimized Bidirectional Raman Amplification. IEEE Photonics Technology Letters, 24(20), 1823-1826. doi:10.1109/lpt.2012.2212183Jia, X.-H., Rao, Y.-J., Yuan, C.-X., Li, J., Yan, X.-D., Wang, Z.-N., … Peng, F. (2013). Hybrid distributed Raman amplification combining random fiber laser based 2nd-order and low-noise LD based 1st-order pumping. Optics Express, 21(21), 24611. doi:10.1364/oe.21.024611Soto, M. A., Angulo-Vinuesa, X., Martin-Lopez, S., Chin, S.-H., Ania-Castanon, J. D., Corredera, P., … Thevenaz, L. (2014). Extending the Real Remoteness of Long-Range Brillouin Optical Time-Domain Fiber Analyzers. Journal of Lightwave Technology, 32(1), 152-162. doi:10.1109/jlt.2013.2292329Soto, M. A., Bolognini, G., & Pasquale, F. D. (2009). Distributed optical fibre sensors based on spontaneous Brillouin scattering employing multimode Fabry-Pérot lasers. Electronics Letters, 45(21), 1071. doi:10.1049/el.2009.2381Li, C., Wang, F., Lu, Y., & Zhang, X. (2012). SNR enhancement in Brillouin optical time domain reflectometer using multi-wavelength coherent detection. Electronics Letters, 48(18), 1139-1141. doi:10.1049/el.2012.1248Voskoboinik, A., Wang, J., Shamee, B., Nuccio, S. R., Zhang, L., Chitgarha, M., … Tur, M. (2011). SBS-Based Fiber Optical Sensing Using Frequency-Domain Simultaneous Tone Interrogation. Journal of Lightwave Technology, 29(11), 1729-1735. doi:10.1109/jlt.2011.2145411Voskoboinik, A., Yilmaz, O. F., Willner, A. W., & Tur, M. (2011). Sweep-free distributed Brillouin time-domain analyzer (SF-BOTDA). Optics Express, 19(26), B842. doi:10.1364/oe.19.00b842Chaube, P., Colpitts, B. G., Jagannathan, D., & Brown, A. W. (2008). Distributed Fiber-Optic Sensor for Dynamic Strain Measurement. IEEE Sensors Journal, 8(7), 1067-1072. doi:10.1109/jsen.2008.926107Nikles, M., Thevenaz, L., & Robert, P. A. (1997). Brillouin gain spectrum characterization in single-mode optical fibers. Journal of Lightwave Technology, 15(10), 1842-1851. doi:10.1109/50.633570Jacobs, I. (1995). Dependence of optical amplifier noise figure on relative-intensity-noise. Journal of Lightwave Technology, 13(7), 1461-1465. doi:10.1109/50.400712Bolognini, G., Soto, M. A., & Di Pasquale, F. (2009). Fiber-Optic Distributed Sensor Based on Hybrid Raman and Brillouin Scattering Employing Multiwavelength Fabry–PÉrot Lasers. IEEE Photonics Technology Letters, 21(20), 1523-1525. doi:10.1109/lpt.2009.202889

Weyl calculus and dual pairs

We consider a dual pair $(G,G')$, in the sense of Howe, with $G$ compact acting on $L^2(\mathbb R^n)$ for an appropriate $n$ via the Weil Representation. Let $\widetilde{G}$ be the preimage of $G$ in the metaplectic group. Given a genuine irreducible unitary representation $\Pi$ of $\widetilde{G}$ we compute the Weyl symbol of orthogonal projection onto $L^2(\mathbb R^n)_\Pi$, the $\Pi$-isotypic component. We apply the result to obtain an explicit formula for the character of the corresponding irreducible unitary representation $\Pi'$ of $\widetilde{G'}$ and to compute of the wave front set of $\Pi'$ by elementary means