The Role of Industry Dynamics in the Persistence of First Mover Advantages

We advance first mover advantages literature by adding novel insights into the conditions that affect the persistence of first mover profitability and market share. We investigate the role of two industry dynamics — market growth and technological discontinuity — and we argue that they will negatively affect the persistence of first mover performance. We test our hypotheses in the context of the European mobile communications industry, by estimating System GMM models on a longitudinal panel of 65 companies in 19 markets, over the period 1998–2008. Model estimations confirm that industry dynamics affect the persistence of first mover advantages. For instance, we find robust empirical evidence that technological discontinuity is detrimental to both first movers’ market share and profitability

Multi Scale Curriculum CNN for Context-Aware Breast MRI Malignancy Classification

Classification of malignancy for breast cancer and other cancer types is usually tackled as an object detection problem: Individual lesions are first localized and then classified with respect to malignancy. However, the drawback of this approach is that abstract features incorporating several lesions and areas that are not labelled as a lesion but contain global medically relevant information are thus disregarded: especially for dynamic contrast-enhanced breast MRI, criteria such as background parenchymal enhancement and location within the breast are important for diagnosis and cannot be captured by object detection approaches properly. In this work, we propose a 3D CNN and a multi scale curriculum learning strategy to classify malignancy globally based on an MRI of the whole breast. Thus, the global context of the whole breast rather than individual lesions is taken into account. Our proposed approach does not rely on lesion segmentations, which renders the annotation of training data much more effective than in current object detection approaches. Achieving an AUROC of 0.89, we compare the performance of our approach to Mask R-CNN and Retina U-Net as well as a radiologist. Our performance is on par with approaches that, in contrast to our method, rely on pixelwise segmentations of lesions.Comment: Accepted to MICCAI 201

In vitro cell cytotoxicity profile and morphological response to polyoxometalate-stabilised gold nanoparticles

The size and redox properties of molecular polyoxometalates (POMs) make them extremely relevant for bioapplications: from disrupting tumour growth and enzyme inhibition, to DNA-intercalating agents and antimicrobial applications. Their unique ability to reversibly dominate and receive electrons, coupled with their high anionic charge, also makes them suitable for the preparation of zero-valent state metal nanoparticles (NPs) from molecular precursors. Polyoxometalate-stabilised nanoparticles (NPs@POM) are therefore an ideal delivery vehicle for bioactive POMs. Here we show how POM-stabilised gold NPs (AuNPs@POM) are massively internalised into Vero (kidney epithelial) and B16 (skin melanoma) cell lines with variable cytotoxic effects. Cell viability assays and quantification of cytoplasmic membrane composition revealed that the Vero cell line was unaltered by the internalisation of these hybrid particles; while their internalisation in B16 tumour cells produced mild cytotoxic effects and an antiproliferative cell cycle arrest in the G0/G1 and G2/M phases. The observed perturbation of the tumour cell line combined with the high degree of internalisation means that these (or similar) NPs@POM could serve as candidates for a range of bioapplications in diagnostics or therapy

Magnetic actuator based on giant magnetostrictive material Terfenol-D with strain and temperature monitoring using FBG optical sensor

We have designed a temperature and strain monitoring system for a magnetic actuator based on the giant magnetostrictive material Terfenol-D (Tb0.3 Dy0.7Fe1.92) with Fiber Bragg grating (FBG) sensors. Magneto-elastic properties of Terfenol-D depend on magnetization, stress pre-history, and temperature. In order to simultaneously monitor these effects, we have implemented a system based on a cylindrical Terfenol-D rod monitored with four FBGs that allows making the appropriate compensations on the strain measurement due to temperature drift. We have measured the magnetostriction in the axial and the transverse directions for the Terfenol-D rod with two perpendicular FBGs, and calculated the Poisson ratio. An additional mechanical system for strain amplification has been designed in order to increase sensitivity, by a factor of 4, in the strain measurement with the FBG sensor.García Miquel, ÁH.; Barrera Vilar, D.; Amat, R.; Kurlyandskaya, GV.; Sales Maicas, S. (2016). Magnetic actuator based on giant magnetostrictive material Terfenol-D with strain and temperature monitoring using FBG optical sensor. Measurement. 80(2):201-206. doi:10.1016/j.measurement.2015.11.035S20120680

Region proposals for saliency map refinement for weakly-supervised disease localisation and classification

First Online: 29 September 2020The deployment of automated systems to diagnose diseases from medical images is challenged by the requirement to localise the diagnosed diseases to justify or explain the classification decision. This requirement is hard to fulfil because most of the training sets available to develop these systems only contain global annotations, making the localisation of diseases a weakly supervised approach. The main methods designed for weakly supervised disease classification and localisation rely on saliency or attention maps that are not specifically trained for localisation, or on region proposals that can not be refined to produce accurate detections. In this paper, we introduce a new model that combines region proposal and saliency detection to overcome both limitations for weakly supervised disease classification and localisation. Using the ChestX-ray14 data set, we show that our proposed model establishes the new state-of-the-art for weakly-supervised disease diagnosis and localisation. We make our code available at https://github.com/renato145/RpSalWeaklyDet.Renato Hermoza, Gabriel Maicas, Jacinto C. Nascimento, Gustavo Carneir

Fast Incoherent OFDR Interrogation of FBG Arrays Using Sparse Radio Frequency Responses

[EN] We present two implementations of fast, discrete incoherent optical frequency-domain reflectometers (I-OFDR) for the interrogation of equally spaced fiber Bragg grating (FBG) arrays, based on the determination of the array's radio frequency (RF) response at a sparse number of frequencies. FBG reflectivities are determined by use of the inverse discrete Fourier transform (IDFT) of the sparse RF response, in a dynamic range limited by crosstalk induced by FBG positioning errors. The first implementation employs the complete, vector RF response at a number of frequencies equal to the number N of FBGs in the array. In the second, the introduction of a reference reflector allows for an interrogation using the power (phaseless) RF response in 4N - 1 frequencies. Demodulation based on IDFT leads to total interrogation times determined by the network analyzer scan time, which can be as low as 10 mu s per FBG. Depending on the interrogation technique, electrical bandwidth requirements are 12 GHz in our array with 10-cm separation. We implemented both techniques in a N = 10 array, inducing decays in reflectivity by 10 dB in one or several FBGs. Unambiguous detection of FBG decays was obtained in both interrogation methods. Additional tests performed on the measured reflectivities also show that measurement linearity is preserved in the 10-dB decay range. As discrete I-OFDR systems, the proposed techniques show the possibility to reach compromises between interrogation time and dynamic range or accuracy in reflectivity measurements, using the number of interrogation frequencies and the sensor topology.This work was supported in part by Infraestructura GVA-FEDER operative program 2007-2013 and in part by the Spanish MINECO through Project TEC2017-88029-R. The work of J. Clement Bellido was supported by the GVA VALi+d scholarship ACIF/2016/214. The work of J. Hervas was supported by the Spanish MEC scholarship FPU13/04675.Clement, J.; Hervás-Peralta, J.; Madrigal-Madrigal, J.; Maestre, H.; Torregrosa, G.; Fernandez-Pousa, CR.; Sales Maicas, S. (2018). Fast Incoherent OFDR Interrogation of FBG Arrays Using Sparse Radio Frequency Responses. Journal of Lightwave Technology. 36(19):4393-4400. https://doi.org/10.1109/JLT.2018.2821199S43934400361

All-Optical Fiber Hanbury Brown & Twiss Interferometer to study 1300 nm single photon emission of a metamorphic InAs Quantum Dot

[EN] New optical fiber based spectroscopic tools open the possibility to develop more robust and efficient characterization experiments. Spectral filtering and light reflection have been used to produce compact and versatile fiber based optical cavities and sensors. Moreover, these technologies would be also suitable to study N-photon correlations, where high collection efficiency and frequency tunability is desirable. We demonstrated single photon emission of a single quantum dot emitting at 1300 nm, using a Fiber Bragg Grating for wavelength filtering and InGaAs Avalanche Photodiodes operated in Geiger mode for single photon detection. As we do not observe any significant fine structure splitting for the neutral exciton transition within our spectral resolution (46 mu eV), metamorphic QD single photon emission studied with our all-fiber Hanbury Brown & Twiss interferometer could lead to a more efficient analysis of entangled photon sources at telecom wavelength. This all-optical fiber scheme opens the door to new first and second order interferometers to study photon indistinguishability, entangled photon and photon cross correlation in the more interesting telecom wavelengths.G Munoz-Matutano thanks the Spanish Juan de la Cierva program (JCI-2011-10686). We acknowledge the support of the Spanish MINECO through projects TEC2014-53727-C2-1-R & TEC2014-60378-C2-1-R, the Research Excellency Award Program GVA PROMETEO 2013/012 PROMETEOII/2014/059 and the Explora Ciencia Tecnologia TEC2013-50552-EXP MULTIFUN project, and the Nanoscale Quantum Optics MPNS COST Action MP1403.Muñoz Matutano, G.; Barrera Vilar, D.; Fernandez-Pousa, CR.; Chulia-Jordan, R.; Seravalli. L.; Trevisi, G.; Frigeri, P.... (2016). All-Optical Fiber Hanbury Brown & Twiss Interferometer to study 1300 nm single photon emission of a metamorphic InAs Quantum Dot. Scientific Reports. 6(2721):1-9. https://doi.org/10.1038/srep27214S1962721Walmsley, I. A. 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Parallel Recording of Single Quantum Dot Optical Emission Using Multicore Fibers

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Single Indium Arsenide Quantum Dot emission spectra have been recorded using a four-core, crosstalk-free, multicore fiber placed at the collection arm of a confocal microscope. We developed two different measurement set-ups depending on the relative configuration of the excitation and collection spots. In the single-matched mode, the emission from the excited area is collected by a single core in the multicore fiber, whereas the three remaining cores capture the emission from neighboring, non-excited areas. This procedure allows for the recording of the Quantum Dot emission from carrier diffusion between sample positions separated by more than 6 μm. In the multiple-matched mode, the excitation spot overlaps the four cores emission area. This configuration permits the acquisition of the micro-photoluminescence spectra at different sample positions without scanning. These results show the possibilities offered by multicore fibers for the spectroscopic analysis of single semiconductor Quantum Dot optical emission.This work was supported in part by the Research Excellency Award Program GVA PROMETEO under Grant 2013/012, in part by the Explora Ciencia Tecnologia through the MULTIFUN Project under Grant TEC2013-50552-EXP, in part by the Research Excellency Award Program GVA PROMETEOII under Grant 2014/059, and in part by the Ministerio de Economia y Competitividad under Grant TEC2014-53727-C2-1-R and Grant TEC2014-60378-C2-1-R. The work of G. Munoz-Matutano was supported by the Spanish Ministerio de Economia y Competitividad through the Juan de la Cierva Program under Grant JCI-2011-10686. The work of I. Gasulla was supported by the Spanish Ministerio de Economia y Competitividad through the Ramon y Cajal Program under Grant RyC-2014-16247.Muñoz-Matutano, G.; Barrera Vilar, D.; Fernandez-Pousa, CR.; Chulia-Jordan, R.; Martinez-Pastor, J.; Gasulla Mestre, I.; Seravalli, L.... (2016). Parallel Recording of Single Quantum Dot Optical Emission Using Multicore Fibers. IEEE Photonics Technology Letters. 28(11):1257-1260. https://doi.org/10.1109/LPT.2016.2538302S12571260281