Nuevas aplicaciones de la cápsula endoscópica: PILLCAM™ ESO

ABSTRACT Capsule endoscopy has opened a new era in small bowel examination. Its indications are now welldefined and currently, wireless capsule endoscopy is considered as the first-line imaging tool for the diagnosis of small bowel diseases. ECE has been shown to be feasible, safe and a good alternative technique in patients refusing conventional endoscopy. Although results reported in both GERD and cirrhotic patients are encouraging, great differences in terms of accuracy (particularly in GERD patients) have been found in published studies. These differences have been attributed to study designs, the lack of adequate experience and inconvenience of ingestion protocols. In summary, more large-scale studies evaluating the new 14-fps capsule, adequate ECE-experience and new modified ingestion protocols are still needed

Continuously-variable survival exponent for random walks with movable partial reflectors

We study a one-dimensional lattice random walk with an absorbing boundary at the origin and a movable partial reflector. On encountering the reflector, at site x, the walker is reflected (with probability r) to x-1 and the reflector is simultaneously pushed to x+1. Iteration of the transition matrix, and asymptotic analysis of the probability generating function show that the critical exponent delta governing the survival probability varies continuously between 1/2 and 1 as r varies between 0 and 1. Our study suggests a mechanism for nonuniversal kinetic critical behavior, observed in models with an infinite number of absorbing configurations.Comment: 5 pages, 3 figure

Mapping of the human visual cortex using image-guided transcranial magnetic stimulation

We describe a protocol using transcranial magnetic stimulation (TMS) to systematically map the visual sensations induced by focal and non-invasive stimulation of the human occipital cortex. TMS is applied with a figure of eight coil to 28 positions arranged in a 232-cm grid over the occipital area. A digitizing tablet connected to a PC computer running customized software, and audio and video recording are used for detailed and accurate data collection and analysis of evoked phosphenes. A frameless image-guided neuronavigational device is used to describe the position of the actual sites of the stimulation coils relative to the cortical surface. Our results show that TMS is able to elicit phosphenes in almost all sighted subjects and in a proportion of blind subjects. Evoked phosphenes are topographically organized. Despite minor inter-individual variations, the mapping results are reproducible and show good congruence among different subjects. This procedure has potential to improve our understanding of physiologic organization and plastic changes in the human visual system and to establish the degree of remaining functional visual cortex in blind subjects. Such a non-invasive method is critical for selection of suitable subjects for a cortical visual prosthesis.This research has been carried out with financial support from the Commission of the European Communities, specific RTD programme ‘Quality of Life and Management of Living Resources’, QLK6-CT-2001-00279 and by the Ministerio de Ciencia y Tecnologıa(MAT2000-1049)Fondo de Investigaciones de la Seguridad Social (FISS 01-0674)National Institute of Mental Health (MH60734, MH57980)National Eye Institute (EYEY12091)Harvard-Thorndike General Clinical Research Center at Beth Israel Deaconess Medical Center (NCRR MO1 RR01032).Medicin

CHK1 expression in gastric cancer is modulated by p53 and RB1/E2F1: Implications in chemo/radiotherapy response

Radiation has a limited but relevant role in the adjuvant therapy of gastric cancer (GC) patients. Since Chk1 plays a critical function in cellular response to genotoxic agents, we aimed to analyze the role of Chk1 in GC as a biomarker for radiotherapy resistance. We analyzed Chk1 expression in AGS and MKN45 human GC cell lines by RT-QPCR and WB and in a small cohort of human patient’s samples. We demonstrated that Chk1 overexpression specifically increases resistance to radiation in GC cells. Accordingly, abrogation of Chk1 activity with UCN-01 and its expression with shChk1 increased sensitivity to bleomycin and radiation. Furthermore, when we assessed Chk1 expression in human samples, we found a correlation between nuclear Chk1 accumulation and a decrease in progression free survival. Moreover, using a luciferase assay we found that Chk1’s expression is controlled by p53 and RB/E2F1 at the transcriptional level. Additionally, we present preliminary data suggesting a posttranscriptional regulation mechanism, involving miR-195 and miR-503, which are inversely correlated with expression of Chk1 in radioresistant cells. In conclusion, Chk1/microRNA axis is involved in resistance to radiation in GC, and suggests Chk1 as a potential tool for optimal stratification of patients susceptible to receive adjuvant radiotherapy after surgeryThis work was supported by Instituto de Salud Carlos III–Fondo de Investigación Sanitaria (PS09/1988 to ISP; PI11-00949, pI014-1495 and Feder Funds to RP); Comunidad Autónoma de Madrid-Universidad Autónoma de Madrid (CCG10-UAM/BIO-5871 to ISP); Fundación Leticia Castillejo Castillo and Ministerio de Ciencia e Innovación (SAF2012-30862 to RSP), Spain

Enantioselective Synthesis of 2-Amino-1,1-diarylalkanes Bearing a Carbocyclic Ring Substituted Indole through Asymmetric Catalytic Reaction of Hydroxyindoles with Nitroalkenes

[EN] An asymmetric catalytic reaction of hydroxyindoles with nitroalkenes leading to the Friedel-Crafts alkylation in the carbocyclic ring of indole is presented. The method is based on the activating/directing effects of the hydroxy group situated in the carbocyclic ring of the indole providing nitroalkylated indoles functionalizated at the C-4, C-5, and C-7 positions with high yield, regio-, and enantioselectivity. The optically enriched nitroalkanes were transformed efficiently in optically enriched 2-amino-1,1-diarylalkanes bearing a carbocyclic ring substituted indole.Financial support from the MINECO (Gobierno de Espana; CTQ2017-84900-P) is gratefully acknowledged. C.V. thanks MINECO for a JdC contract. J.R.-B. thanks the Ministry of Education for a Collaboration grant. Access to NMR, MS, and X-ray facilities from the Servei Central de Suport a la Investigacio Experimental (SCSIE)-UV is also acknowledgedVila, C.; Rostoll-Berenguer, J.; Sánchez-García, R.; Blay, G.; Fernandez, I.; Muñoz Roca, MDC.; Pedro, JR. (2018). Enantioselective Synthesis of 2-Amino-1,1-diarylalkanes Bearing a Carbocyclic Ring Substituted Indole through Asymmetric Catalytic Reaction of Hydroxyindoles with Nitroalkenes. The Journal of Organic Chemistry. 83(12):6397-6407. https://doi.org/10.1021/acs.joc.8b0061263976407831

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. Quantum optics: Science and technology in a new light. Science 348, 525–530 (2015).Eisaman, M. D., Fan, J., Migdall, A. & Polyakov, S. Invited review article: single-photon sources and detectors. Rev. Sci. Instrum. 82, 071101 (2011).Lu, C.-L. & Pan, J.-W. Push-button photon entanglement. Nat. Photonics 8, 174–176 (2014).Benson, O., Santori, C., Pelton, M. & Yamamoto, Y. Regulated and entangled photons from a single quantum dot. Phys. Rev. Lett. 84, 2513–2516 (2000).Yuan, Z. et al. Electrically driven single-photon source. Science 295, 102–105 (2002).Salter, C. L. et al. An entangled-light-emitting diode. Nature 465, 594–597 (2010).Brunner, D. et al. A coherent single-hole spin in a semiconductor. Science 325, 70–72 (2009).Müller, M., Bounouar, S., Jöns, K. D., Glässl, M. & Michler, P. On-demand generation of indistinguishable polarization-entangled photon pairs. Nat. Photonics 8, 234–238 (2014).Seguin, R. et al. Size-dependent fine-structure splitting in self-organized InAs/GaAs quantum dots. Phys. Rev. Lett. 95, 257402 (2005).Hadfield, R. H. Single-photon detectors for optical quantum information applications. Nat. Photonics 3, 696–705 (2009).Zinoni, C. et al. Time-resolved and antibunching experiments on single quantum dots at 1300nm. Appl. Phys. Lett. 88, 131102 (2006).Liu, X. et al. Single-photon emission in telecommunication band from an InAs quantum dot grown on InP with molecular-beam epitaxy. Appl. Phys. Lett. 103, 061114 (2013).Benyoucef, M., Yacob, M., Reithmaier, J. P., Kettler, J. & Michler, P. Telecom-wavelength (1.5 μm) single-photon emission from InP-based quantum dots. Appl. Phys. Lett. 103, 162101 (2013).Ward, M. et al. Coherent dynamics of a telecom-wavelength entangled photon source. Nat. Commun. 5, 3316 (2014).Rakher, M. T. et al. Quantum transduction of telecommunications-band single photons from a quantum dot by frequency upconversion. Nat. Photonics 4, 786–791 (2010).Muñoz-Matutano, G. et al. Time resolved emission at 1.3 μm of a single InAs quantum dot by using a tunable fibre Bragg grating. Nanotechnology 25, 035204 (2014).Ediger, M. et al. Peculiar many-body effects revealed in the spectroscopy of highly charged quantum dots. Nature Phys. 3, 774–779 (2007).Gerardot, B. D. et al. Laser spectroscopy of individual quantum dots charged with a single hole. Appl. Phys. Lett. 99, 243112 (2011).Gomis-Bresco, J. et al. Random population model to explain the recombination dynamics in single InAs/GaAs quantum dots under selective optical pumping. New J. Phys. 13, 023022 (2011).Ediger, M. et al. Fine structure of negatively and positively charged excitons in semiconductor quantum dots: electron-hole asymmetry. Phys. Rev. Lett. 98, 036808 (2007).Warming, T. et al. Hole-hole and electron-hole exchange interactions in single InAs/GaAs quantum dots. Phys. Rev. B 79, 125316 (2009).Benny, Y. et al. Excitation spectroscopy of single quantum dots at tunable positive, neutral and negative charge states. Phys. Rev. B 86, 085306 (2012).Muñoz-Matutano, G. et al. Selective optical pumping of charged excitons in unintentionally doped InAs quantum dots. Nanotechnology 19, 145711 (2008).Ha, N. et al. Size-dependent line broadening in the emission spectra of single GaAs quantum dots: Impact of surface charge on spectral diffusion. Phys. Rev. B 92, 075306 (2015).Moskalenko, E. S. et al. Influence of excitation energy on charged exciton formation in self-assembled InAs single quantum dots. Phys. Rev. B 64, 085302 (2001).Rivas, D. et al. Two-color single-photon emission from InAs quantum dots: toward logic information management using quantum light. Nano Lett. 14, 456–463 (2014).Dekel, E. et al. Cascade evolution and radiative recombination of quantum dot multiexcitons studied by time-resolved spectroscopy. Phys. Rev. B 62, 11038 (2000).Wimmer, M., Nair, S. & Shumway, J. Biexciton recombination rates in self-assembled quantum dots. Phys. Rev. B 73, 165305 (2006).Dalgarno, P. A. et al. Coulomb interactions in single charged self-assembled quantum dots: Radiative lifetime and recombination energy. Phys. Rev. B 77, 245311 (2008).Muñoz-Matutano, G. et al. Exciton, biexciton and trion recombination dynamics in a single quantum dot under selective optical pumping. Physica E 40, 2100–2103 (2008).Birkedal, D., Leosson, K. & Hvam, J. M. Long lived coherence in self-assembled quantum dots. Phys. Rev. Lett. 87, 227401 (2001).Tartakovskii, A. et al. Effect of thermal annealing and strain engineering on the fine structure of quantum dot excitons. Phys. Rev. B 70, 193303 (2004).Goldmann, E., Barthel, S., Florian, M., Schuh, K. & Jahnke, F. Excitonic fine-structure splitting in telecom-wavelength InAs/GaAs quantum dots: statistical distribution and height-dependence. Appl. Phys. Lett. 103, 242102 (2004).Seravalli, L., Trevisi, G. & Frigeri, P. 2D–3D growth transition in metamorphic InAs/InGaAs quantum dots. Cryst. Eng. Comm. 14, 1155–1160 (2012).Akimov, I., Kavokin, K., Hundt, A. & Henneberger, F. Electron-hole exchange interaction in a negatively charged quantum dot. Phys. Rev. B 71, 075326 (2005).Brouri, R., Beveratos, A., Poizat, J. & Grangier, P. Photon antibunching in the fluorescence of individual color centers in diamond. Opt. Lett. 25, 1294–1296 (2000).Mandel, L. & Wolf, E. Optical Coherence and Quantum Optics. Cambridge University Press (1995).Seravalli, L., Frigeri, P., Trevisi, G. & Franchi, S. 1.59 μm room temperature emission from metamorphic InAs∕InGaAsInAs∕InGaAs quantum dots grown on GaAs substrates. Appl. Phys. Lett. 92, 213104 (2008).Gonzalez-Tudela, A., Laussy, F. P., Tejedor, C., Hartmann, M. J. & del Valle, E. Two-photon spectra of quantum emitters. New J. Phys. 15, 033036 (2013).Peiris, M. et al. Two-color photon correlations of the light scattered by a quantum dot. Phys. Rev. B 91, 195125 (2015).Venghaus, L. Wavelength Filters in Fibre Optics. Springer Series in Optical Sciences Vol 123 (2006).Seravalli, L. et al. Single quantum dot emission at telecom wavelengths from metamorphic InAs/InGaAs nanostructures grown on GaAs substrates. Appl. Phys. Lett. 98, 173112 (2011).Seravalli, L. et al. Quantum dot strain engineering of InAs∕InGaAsInAs∕InGaAs nanostructures. J. Appl. Phys. 101, 024313 (2007).Seravalli, L., Trevisi, G. & Frigeri, P. Design and growth of metamorphic InAs/InGaAs quantum dots for single photon emission in the telecom window. Crys. Eng. Comm. 14, 6833–6838 (2012).Seravalli, L., Frigeri, P., Nasi, L., Trevisi, G. & Bocchi, C. Metamorphic quantum dots: quite different nanostructures. J. Appl. Phys. 108, 064324 (2010)

An in-depth view of the microscopic dynamics of Ising spin glasses at fixed temperature

Using the dedicated computer Janus, we follow the nonequilibrium dynamics of the Ising spin glass in three dimensions for eleven orders of magnitude. The use of integral estimators for the coherence and correlation lengths allows us to study dynamic heterogeneities and the presence of a replicon mode and to obtain safe bounds on the Edwards-Anderson order parameter below the critical temperature. We obtain good agreement with experimental determinations of the temperature-dependent decay exponents for the thermoremanent magnetization. This magnitude is observed to scale with the much harder to measure coherence length, a potentially useful result for experimentalists. The exponents for energy relaxation display a linear dependence on temperature and reasonable extrapolations to the critical point. We conclude examining the time growth of the coherence length, with a comparison of critical and activated dynamics.Comment: 38 pages, 26 figure