How was the Hubble sequence 6 Gyrs ago?

The way galaxies assemble their mass to form the well-defined Hubble sequence is amongst the most debated topic in modern cosmology. One difficulty is to link distant galaxies to those at present epoch. We aim at establishing how were the galaxies of the Hubble sequence, 6 Gyrs ago. We intend to derive a past Hubble sequence that can be causally linked to the present-day one. We selected samples of nearby galaxies from the SDSS and of distant galaxies from the GOODS survey. We verified that each sample is representative of galaxies. We further showed that the observational conditions necessary to retrieve their morphological classification are similar in an unbiased way. Morphological analysis has been done in an identical way for all galaxies in the two samples. We found an absence of number evolution for elliptical and lenticular galaxies, which strikingly contrasts with the strong evolution of spiral and peculiar galaxies. Spiral galaxies were 2.3 times less abundant in the past, that is exactly compensated by the strong decrease by a factor 5 of peculiar galaxies. It strongly suggests that more than half of the present-day spirals had peculiar morphologies, 6 Gyrs ago, and this has to be accounted by any scenario of galactic disk evolution and formation. The past Hubble sequence can be used to test these scenarios as well as to test evolution of fundamental planes for spirals and bulges.Comment: Version accepted by Astronomy and Astrophysics, October 21 2009. Including low resolution images. 11 pages, 8 figure

Correlated enhancement of Hc2 and Jc in carbon nanotube-doped MgB2

The use of MgB2 in superconducting applications still awaits for the development of a MgB2-based material where both current-carrying performance and critical magnetic field are optimized simultaneously. We achieved this by doping MgB2 with double-wall carbon nanotubes (DWCNT) as a source of carbon in polycrystalline samples. The optimum nominal DWCNT content for increasing the critical current density, Jc is in the range 2.5-10%at depending on field and temperature. Record values of the upper critical field, Hc2(4K) = 41.9 T (with extrapolated Hc2(0) ~ 44.4 T) are reached in a bulk sample with 10%at DWCNT content. The measured Hc2 vs T in all samples are successfully described using a theoretical model for a two-gap superconductor in the dirty limit first proposed by Gurevich et al.Comment: 12 pages, 3 figure

Convolutional sparse coding for high dynamic range imaging

Current HDR acquisition techniques are based on either (i) fusing multibracketed, low dynamic range (LDR) images, (ii) modifying existing hardware and capturing different exposures simultaneously with multiple sensors, or (iii) reconstructing a single image with spatially-varying pixel exposures. In this paper, we propose a novel algorithm to recover high-quality HDRI images from a single, coded exposure. The proposed reconstruction method builds on recently-introduced ideas of convolutional sparse coding (CSC); this paper demonstrates how to make CSC practical for HDR imaging. We demonstrate that the proposed algorithm achieves higher-quality reconstructions than alternative methods, we evaluate optical coding schemes, analyze algorithmic parameters, and build a prototype coded HDR camera that demonstrates the utility of convolutional sparse HDRI coding with a custom hardware platform

Hidden geometric correlations in real multiplex networks

Real networks often form interacting parts of larger and more complex systems. Examples can be found in different domains, ranging from the Internet to structural and functional brain networks. Here, we show that these multiplex systems are not random combinations of single network layers. Instead, they are organized in specific ways dictated by hidden geometric correlations between the individual layers. We find that these correlations are strong in different real multiplexes, and form a key framework for answering many important questions. Specifically, we show that these geometric correlations facilitate: (i) the definition and detection of multidimensional communities, which are sets of nodes that are simultaneously similar in multiple layers; (ii) accurate trans-layer link prediction, where connections in one layer can be predicted by observing the hidden geometric space of another layer; and (iii) efficient targeted navigation in the multilayer system using only local knowledge, which outperforms navigation in the single layers only if the geometric correlations are sufficiently strong. Our findings uncover fundamental organizing principles behind real multiplexes and can have important applications in diverse domains.Comment: Supplementary Materials available at http://www.nature.com/nphys/journal/v12/n11/extref/nphys3812-s1.pd

The age of data-driven proteomics : how machine learning enables novel workflows

A lot of energy in the field of proteomics is dedicated to the application of challenging experimental workflows, which include metaproteomics, proteogenomics, data independent acquisition (DIA), non-specific proteolysis, immunopeptidomics, and open modification searches. These workflows are all challenging because of ambiguity in the identification stage; they either expand the search space and thus increase the ambiguity of identifications, or, in the case of DIA, they generate data that is inherently more ambiguous. In this context, machine learning-based predictive models are now generating considerable excitement in the field of proteomics because these predictive models hold great potential to drastically reduce the ambiguity in the identification process of the above-mentioned workflows. Indeed, the field has already produced classical machine learning and deep learning models to predict almost every aspect of a liquid chromatography-mass spectrometry (LC-MS) experiment. Yet despite all the excitement, thorough integration of predictive models in these challenging LC-MS workflows is still limited, and further improvements to the modeling and validation procedures can still be made. In this viewpoint we therefore point out highly promising recent machine learning developments in proteomics, alongside some of the remaining challenges

Study of the Effects on Turbocharger Performance Generated by the Presence of Foreign Objects at the Compressor Intake

The study performed on this work consists of evaluating the consequences of the introduction of various foreign objects at the compressor inlet of a turbocharger. The most plausible objects were selected. A specific test bench was set up in order to perform the experiment and measure the compression ratio and compressor efficiency evolution. Measurements were performed before (healthy compressor) and after the object introduction (damaged compressor). Results obtained indicate that losses in performance can be very important, but also that the compressor can swallow hard objects without visible damage. Therefore the experiments were filmed with a high speed camera. Visual information has helped to better understand the phenomenon, to explain the measurements and it has been taken into account in order to perform final diagnosis. As expected, the harder the object is and the longer it hits compressor wheel before being swallowed, the most severe is the damage. Nevertheless, softer material can reach abnormal performance but in randomly manner and such incipient damage can be detected easily in high air flow rates than in lower.The authors wish to thank Spanish Grant TRA2007-65433/TAIR from Ministerio de Educacion y Ciencia. D.G. Investigacion for supporting this work.Serrano Cruz, JR.; Tormos Martínez, BV.; Gargar, KL.; Bouffaud, F. (2013). Study of the Effects on Turbocharger Performance Generated by the Presence of Foreign Objects at the Compressor Intake. Experimental Techniques. 37(2):30-40. https://doi.org/10.1111/j.1747-1567.2011.00795.xS3040372Watson, N., & Janota, M. S. (1982). Turbocharging the Internal Combustion Engine. doi:10.1007/978-1-349-04024-7Gjika , K. Larue , G.D. “Dynamic Behaviour of Rotor-Bearing Systems Involving Two Oil Films in Series-Application to High-Speed Turbochargers,” IMechE Conference Transactions C602/021/2002. Seventh International Conference on Turbochargers and Turbocharging 2002Galindo, J., Serrano, J. R., Guardiola, C., & Cervelló, C. (2006). Surge limit definition in a specific test bench for the characterization of automotive turbochargers. Experimental Thermal and Fluid Science, 30(5), 449-462. doi:10.1016/j.expthermflusci.2005.06.002Engels , B. “Lifetime Prediction for Turbocharger Compressor Wheels-Why Use Titanium?” IMechE Conference Transactions C602/037/2002. Seventh International Conference on Turbochargers and Turbocharging 2002Ahdad , F. Soare , M.A. “Prediction of Duration of Life of Automotive Components under Thermomechanical Fatigue,” IMechE Conference Transactions C602/020/2002. Seventh International Conference on Turbochargers and Turbocharging 2002Holmes , R. “Turbocharger Vibration - A Case Study,” IMechE Conference Transactions C692/031/2002. Seventh International Conference on Turbochargers and Turbocharging 2002Zhao , X. He , H. Xu , S. “Influence of the Floating-Ring Bearing Parameters on Stability of Turbocharger Rotor-Bearing System,” Proceedings of the Fourth International Symposium of Fluid Machinery and Fluid Engineering. 421 425 2008SAE J1826 Turbocharger Gas Stand Test Code, Recommended Practice 1995Luján , J.M. Bermudez , V. Serrano , J.R. Cervelló , C. “Test Bench for Turbocharger Groups Characterization,” SAE Paper 2002-01-0163.Serrano , J.R. Guardiola , C. Dolz , V. Tiseira , A. Cervelló , C. “Experimental Study of the Turbine Inlet Gas temperature influence on Turbocharger Performance,” SAE Paper 2007-01-1559.Macián, V., Luján, J. M., Bermúdez, V., & Guardiola, C. (2004). Exhaust pressure pulsation observation from turbocharger instantaneous speed measurement. Measurement Science and Technology, 15(6), 1185-1194. doi:10.1088/0957-0233/15/6/020The International Council on Combustion Engines (CIMAC) Turbocharging Efficiencies - Definitions and Guidelines for Measurements and Calculation 200