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6. Comparative risk of thrombosis with thrombocytopenia syndrome or thromboembolic events associated with different covid-19 vaccines

Author

Li, X, Burn, E, Duarte-Salles, T, Yin, C, Reich, C, Delmestri, A, Verhamme, K, Rijnbeek, P, Suchard, MA, Li, K, Mosseveld, M, John, LH, Mayer, M-A, Ramirez-Anguita, J-M, Cohet, C, Strauss, V, Prieto-Alhambra, D, Medical Informatics, and Epidemiology

Subjects
Adult, Venous Thrombosis, COVID-19 Vaccines, Adolescent, Ad26COVS1, COVID-19, Thrombosis, General Medicine, Thrombocytopenia, Cohort Studies, SDG 3 - Good Health and Well-being, Thromboembolism, Humans, BNT162 Vaccine
Abstract

Objective To quantify the comparative risk of thrombosis with thrombocytopenia syndrome or thromboembolic events associated with use of adenovirus based covid-19 vaccines versus mRNA based covid-19 vaccines. Design International network cohort study. Setting Routinely collected health data from contributing datasets in France, Germany, the Netherlands, Spain, the UK, and the US. Participants Adults (age ≥18 years) registered at any contributing database and who received at least one dose of a covid-19 vaccine (ChAdOx1-S (Oxford-AstraZeneca), BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), or Ad26.COV2.S (Janssen/Johnson & Johnson)), from December 2020 to mid-2021. Main outcome measures Thrombosis with thrombocytopenia syndrome or venous or arterial thromboembolic events within the 28 days after covid-19 vaccination. Incidence rate ratios were estimated after propensity scores matching and were calibrated using negative control outcomes. Estimates specific to the database were pooled by use of random effects meta-analyses. Results Overall, 1 332 719 of 3 829 822 first dose ChAdOx1-S recipients were matched to 2 124 339 of 2 149 679 BNT162b2 recipients from Germany and the UK. Additionally, 762 517 of 772 678 people receiving Ad26.COV2.S were matched to 2 851 976 of 7 606 693 receiving BNT162b2 in Germany, Spain, and the US. All 628 164 Ad26.COV2.S recipients from the US were matched to 2 230 157 of 3 923 371 mRNA-1273 recipients. A total of 862 thrombocytopenia events were observed in the matched first dose ChAdOx1-S recipients from Germany and the UK, and 520 events after a first dose of BNT162b2. Comparing ChAdOx1-S with a first dose of BNT162b2 revealed an increased risk of thrombocytopenia (pooled calibrated incidence rate ratio 1.33 (95% confidence interval 1.18 to 1.50) and calibrated incidence rate difference of 1.18 (0.57 to 1.8) per 1000 person years). Additionally, a pooled calibrated incidence rate ratio of 2.26 (0.93 to 5.52) for venous thrombosis with thrombocytopenia syndrome was seen with Ad26.COV2.S compared with BNT162b2. Conclusions In this multinational study, a pooled 30% increased risk of thrombocytopenia after a first dose of the ChAdOx1-S vaccine was observed, as was a trend towards an increased risk of venous thrombosis with thrombocytopenia syndrome after Ad26.COV2.S compared with BNT162b2. Although rare, the observed risks after adenovirus based vaccines should be considered when planning further immunisation campaigns and future vaccine development.

Published
2022

9. Transfusion service management of sickle-cell disease patients

Author

Yazer, M. H., Lozano, M., Crighton, G., Greenway, A., Comande, M., Savoia, H., Wood, E., Gilli, S., Castilho, L., Saad, Sara T.O., Galactéros, F., Noizat-Pirenne, F., Pazgal, I., Stark, P., Orlin, Y., Perseghin, P., Masera, N., Cela, E., Anguita, J., Wikman, A., and Delaney, M.

Published
2016
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13. HAPLOIDENTICAL STEM CELL TRANSPLANTATION (HAPLO-HSCT) WITH HIGH DOSE CYLOPHOSPHAMIDE POST-TRANSPLANT (PT-CY) AS GVHD PROPHYLAXIS IN HIGH RISK HEMATOLOGIC MALIGNANCIES: MULTICENTRIC SPANISH EXPERIENCE: PH-P377

Author

Gayoso, J., Balsalobre, P., Kwon, M., Pascual, Jesús M., Castilla, C., Serrano, D., López-Corral, L., Pérez-Simón, Antonio J., Bermúdez, A., Rovira, M., Pérez-Corral, A., Anguita, J., Heras, I., Solano, C., Figuera, A., Sampol, Antonia M., Ferrá, C., Herrera, P., González, Sonia M., Montesinos, P., Buño, I., and Díez-Martín, Luis J.

Published
2014

27. Cardiopoietic cell therapy for advanced ischemic heart failure : results at 39 weeks of the prospective, randomized, double blind, sham-controlled CHART-1 clinical trial

Author

Bartunek, Jozef, Terzic, Andre, Davison, Beth A, Filippatos, Gerasimos S, Radovanovic, Slavica, Beleslin, Branko, Merkely, Bela, Musialek, Piotr, Wojakowski, Wojciech, Andreka, Peter, Horvath, Ivan G, Katz, Amos, Dolatabadi, Dariouch, El Nakadi, Badih, Arandjelovic, Aleksandra, Edes, Istvan, Seferovic, Petar M, Obradovic, Slobodan, Vanderheyden, Marc, Jagic, Nikola, Petrov, Ivo, Atar, Shaul, Halabi, Majdi, Gelev, Valeri L, Shochat, Michael K, Kasprzak, Jaroslaw D, Sanz Ruiz, Ricardo, Heyndrickx, Guy R, Nyolczas, Noémi, Legrand, Victor, Guédès, Antoine, Heyse, Alex, Moccetti, Tiziano, Fernandez Aviles, Francisco, Jimenez Quevedo, Pilar, Bayes Genis, Antoni, Hernandez Garcia, Jose Maria, Ribichini, Flavio, Gruchala, Marcin, Waldman, Scott A, Teerlink, John R, Gersh, Bernard J, Povsic, Thomas J, Henry, Timothy D, Metra, Marco, Hajjar, Roger J, Tendera, Michal, Behfar, Atta, Alexandre, Bertrand, Seron, Aymeric, Stough, Wendy Gattis, Sherman, Warren, Cotter, Gad, Wijns, W. i. l. l. i. a. m. Collaborators Clinical investigators, Dens, sites Belgium: Ziekenhuis Oost Limburg: J., Dupont, M., Mullens, W., Janssens, M., Dolatabadi, Hoˆpital Civil de Charleroi: D., De Bruyne, Y., Lalmand, J., Dubois, P., El Nakadi, B., Aminian, A., De Vuyst, E., Gurnet, P., Gujic, M., Blankoff, I., Guedes, CHU Mont Godinne UCL: A., Gabriel, L., Seldrum, S., Doyen, C., Andre´, M., Heyse, AZ Glorieux: A., Van Durme, F., Verschuere, J., Legrand, Domaine Universitaire du Sart Tilman: V., Gach, O., D’Orio, V., Davin, L., Lancellotti, P., Baudoux, E., Ancion, A., Dulgheru, R., Vanderheyden, OLV Ziekenhuis Aalst – Cardiologie: M., Bartunek, J., Wijns, W., Verstreken, S., Penicka, . M., Gelev, P. Meeus Bulgaria: Tokuda Hospital Sofia: V., Zheleva Kichukova, I., Parapunova, R., Melamed, R., Sardovski, S., Radev, O., Yordanov, A., Radinov, A., Nenov, D., Amine, I., Petrov, City Hospital Clinic Cardiology Center: I., Kichukov, K., Nikitasov, L., Stankov, Z., Stoyanov, H., Tasheva Dimitrova, I., Angelova, M., Dimitrov, E., Minchev, M., Garvanski, I., Botev, C., Polomski, P., Alexandrovska University Hospital, Vassilev, Sofia: D., Karamfiloff, K., Tarnovska Kadreva, R., Vladimirova, L., Dimitrov, G., Hadzhiev, E., Tzvetkova, G., Andreka, . M. Atanasova Hungary: Gottsegen Gyo¨ rgy Orszagos Kardiologiai Inte´zet: P., Fontos, G., Fabian, J., Csepregi, A., Uzonyi, G., Gelei, A., Edes, Debreceni Egyetem Orvos e´s Ege´szse´gtudomanyi Centrum Altalanos Orvostudomanyi Kar Kardiologia Inte´zet: I., Balogh, L., Vajda, G., Darago, A., Gergely, S., Fulop, T., Jenei, C., Horvath, Pe´csi Tudomanyegyetem Klinikai Ko¨zpont Szıvgyogyaszati Klinika: I., Magyari, B., Nagy, A., Cziraki, A., Faludi, R., Kittka, B., Alizadeh, H., Merkely, Semmelweis Egyetem Varosmajori Szıv e´s Ergyogyaszati Klinika: B., Geller, L., Farkas, P., Szombath, G., Foldes, G., Skopal, J., Kovacs, A., Kosztin, A., Gara, E., Sydo, N., Nyolczas, MH Ege´szse´gu¨gyi Ko¨zpont Kardiologiai Osztaly: N., Kerecsen, G., Korda, A., Kiss, . M., Borsanyi, T., Polgar, B., Muk, B., Sharif, Z. Bari Ireland: HRB Clinical Research Facility: F., Atar, Y. M. Smyth Israel:Western Galilee Hospital: S., Shturman, A., Akria, L., Kilimnik, M., Brezins, M., Halabi, Ziv Medical Center: M., Dally, N., Goldberg, A., Aehab, K., Rosenfeld, I., Levinas, T., Saleem, D., Katz, Barzilai Medical Center: A., Plaev, T., Drogenikov, T., Nemetz, A., Barshay, Y., Jafari, J., Orlov, I., Nazareth Hospital EMMS: M. Omory, N. Kogan Nielsen, Shochat, Hillel Yaffe Medical Center: M., Shotan, A., Frimerman, A., Meisel, S., Asif, A., Sofer, O., Blondheim, D. S., Vazan, A., Metra, L. Arobov Italy: A. O. Spedali Civili di Brescia: M., Bonadei, I., Inama, L., Chiari, E., Lombardi, C., Magatelli, M., Russo, D., Lazzarini, V., Carubelli, V., Vassanelli, AOUI Verona – Borgo Trento Hospital: C., Ribichini, Flavio Luciano, Bergamini, C., Krampera, Mauro, Cicoria, M. A., Zanolla, L., Dalla Mura, D., Gambaro, A., Rossi, A., Pesarini Poland: Jagiellonian University Department of Cardiac, G., Musialek, Vascular Diseases at John Paul II Hospital in Krakow: P., Mazurek, A., Drabik, L., Ka˛dzielski, A., Walter, Z., Dzieciuch Rojek, M., Rubis, P., Plazak, . W., Tekieli, L., Podolec, J., Orczyk, W., Sutor, U., Zmudka, K., Olszowska, M., Podolec, P., Gruchala, Uniwersyteckie Centrum Kliniczne: M., Ciecwierz, D., Mielczarek, M., Burakowski, S., Chmielecki, M., Zielinska, M., Frankiewicz, A., Wdowczyk, J., Stopczynska, I., Bellwon, J., Mosakowska, K., Nadolna, R., Wroblewska, J., Rozmyslowska, M., Rynkiewicz, M., Marciniak, I., Raczak, G., Tarnawska, M., Taszner, M., Kasprzak, Bieganski Hospital: J., Plewka, M., Fiutowska, D., Rechcinski, T., Lipiec, P., Sobczak, M., Weijner Mik, P., Wraga, M., Krecki, R., Markiewicz, M., Haval Qawoq, D., Wojakowski, Gornosla˛skie Centrum Medyczne Sla˛skie j. Akademii Medycznej: W., Ciosek, J., Dworowy, S., Gaszewska Zurek, E., Ochala, A., Cybulski, W., Jadczyk, T., Wanha, W., Parma, Z., Kozlowski, M., Dzierzak, M., Markiewicz Serbia: Clinical Hospital Center Zvezdara, M., Arandjelovic, Cardiology Clinic: A., Sekularac, N., Boljevic, D., Bogdanovic, A., Zivkovic, S., Cvetinovic, N., Loncar, G., Clinical Centre of Serbia, Beleslin, Cardiology Clinic: B., Nedeljkovic, M., Trifunovic, D., Giga, V., Banovic, M., Nedeljkovic, I., Stepanovic, J., Vukcevic, V., Djordjevic Dikic, A., Dobric, M., Obrenovic Kircanski, B., Seferovic, Cardiology Clinic: P., Orlic, D., Tesic, M., Petrovic, O., Milinkovic, I., Simeunovic, D., Jagic, Clinical Center of Kragujevac: N., Tasic, M., Nikolic, D., Miloradovic, V., Djurdjevic, P., Sreckovic, M., Zornic, N., Clinical Hospital Center Bezanijska Kosa, Radovanovic, Cardiology Department: S., Saric, J., Hinic, S., Djokovic, A., Ðordevic, S., Bisenic, V., Markovic, O., Stamenkovic, S., Malenkovic, V., Tresnjak, J., Misic, G., Cotra, D., Tomovic, L., Vuckovic, V., Clinic of Emergency Internal Medicine, Obradovic, Military Medical Academy: S., Jovic, Z., Vukotic, S., Markovic, D., Djenic, N., Ristic Andjelkov, A., Bayes Genis, D. Ljubinka Spain: Hospital Universitario Germans Trias I. Pujol: A., Rodriguez Leor, O., Labata, C., Vallejo, N., Ferrer, E., Batlle, M., Fernandez Aviles, Hospital General Universitario Gregorio Mara~non: F., Sanz Ruiz, R., Casado, A., Loughlin, G., Zatarain, E., Anguita, J., Ferna ndez Santos, M. E., Pascual, C., Bermejo, J., Hernandez Garcia, Hospital Clinico Universitario Virgen de la Victoria: J. M., Jimenez Navarro, M., Dominguez, A., Carrasco, F., Mu~noz, A., Garcia Pinilla, J. M., Ruiz, J., Queipo de Llano, M. P., Hernandez, A., Fernandez, A., Jimenez Quevedo, Hospital Clinico San Carlos: P., Guerra, R., Biagioni, C., Gonzalez, R. A., Gomez deDiego, J. J., Mansson Broberg, L. Perez de Isla Sweden: Karolinska University Hospital: A., Sylve´n, C., Leblanc, K., Winter, R., Blomberg, P., Gunyeli, E., Ruck, A., Silva, C., Fo¨rstedt Switzerland: CardioCentro Ticino, J., Moccetti, Switzerland: T., Rossi, M., Pasotti, E., Petrova, I., Crljenica, C., Monti, C., Murzilli, R., Su¨rder, D., Moccetti, M., Turchetto, L., Locicero, V., Chiumiento, L., Maspoli, S., Mombelli, M., Anesini, A., Biggiogero, M., Ponti, G., Camporini, C., Polledri, S., Hill, G. Dolci United Kingdom: Kings College Hospital: J., Plymen, C., Amin Youssef, G., Mcdonagh, T., Drasar, E., Mijovic, A., Jouhra, F., Mcloman, D., Dworakowski, R., Webb, I., Byrne, J., and Potter, V.

Subjects
0301 basic medicine, Male, Cardiopoiesis, Cardiovascular disease, Disease severity, Marker, Precision medicine, Regenerative medicine, Stem cell, Target population, Adult, Aged, Double-Blind Method, Female, Heart Failure, Humans, Mesenchymal Stem Cell Transplantation, Middle Aged, Myocardial Ischemia, Prospective Studies, Treatment Outcome, Young Adult, Cardiology and Cardiovascular Medicine, Cell- and Tissue-Based Therapy, mesenchymal stem-cells, 030204 cardiovascular system & hematology, Cardiorespiratory Medicine and Haematology, outcomes, Fast-Track Clinical Research, Sudden cardiac death, 0302 clinical medicine, Ischemia, cardiovascular disease, Clinical endpoint, target population, CHART Program, Ejection fraction, bone-marrow, Heart Failure/Cardiomyopathy, 3. Good health, Cohort, Cardiology, Fast Track, disease severity, delivery, medicine.medical_specialty, precision medicine, Clinical Sciences, regenerative medicine, 03 medical and health sciences, cardiopoiesis, Internal medicine, medicine, Adverse effect, marker, disease, business.industry, medicine.disease, mortality, Confidence interval, Clinical trial, stem cell, Editor's Choice, 030104 developmental biology, predictors, Cardiovascular System & Hematology, Heart failure, business
Abstract

Altres ajuts: This work was supported by Celyad, SA (Mont-Saint-Guibert, Belgium). Celyad has received research grants from the Walloon Region (Belgium, DG06 funding). Cardiopoietic cells, produced through cardiogenic conditioning of patients' mesenchymal stem cells, have shown preliminary efficacy. The Congestive Heart Failure Cardiopoietic Regenerative Therapy (CHART-1) trial aimed to validate cardiopoiesis-based biotherapy in a larger heart failure cohort. This multinational, randomized, double-blind, sham-controlled study was conducted in 39 hospitals. Patients with symptomatic ischaemic heart failure on guideline-directed therapy (n = 484) were screened; n = 348 underwent bone marrow harvest and mesenchymal stem cell expansion. Those achieving > 24 million mesenchymal stem cells (n = 315) were randomized to cardiopoietic cells delivered endomyocardially with a retention-enhanced catheter (n = 157) or sham procedure (n = 158). Procedures were performed as randomized in 271 patients (n = 120 cardiopoietic cells, n = 151 sham). The primary efficacy endpoint was a Finkelstein–Schoenfeld hierarchical composite (all-cause mortality, worsening heart failure, Minnesota Living with Heart Failure Questionnaire score, 6-min walk distance, left ventricular end-systolic volume, and ejection fraction) at 39 weeks. The primary outcome was neutral (Mann–Whitney estimator 0.54, 95% confidence interval [CI] 0.47–0.61 [value > 0.5 favours cell treatment], P = 0.27). Exploratory analyses suggested a benefit of cell treatment on the primary composite in patients with baseline left ventricular end-diastolic volume 200–370 mL (60% of patients) (Mann–Whitney estimator 0.61, 95% CI 0.52–0.70, P = 0.015). No difference was observed in serious adverse events. One (0.9%) cardiopoietic cell patient and 9 (5.4%) sham patients experienced aborted or sudden cardiac death. The primary endpoint was neutral, with safety demonstrated across the cohort. Further evaluation of cardiopoietic cell therapy in patients with elevated end-diastolic volume is warranted.

Published
2017

29. Strong near-field optical localization on an array of gold nanodisks.

Author

Aigouy, Lionel, Prieto, P., Vitrey, A., Anguita, J., Cebollada, A., González, M. U., García-Martín, A., Labéguerie-Egéa, J., and Mortier, M.

Subjects
ELECTROMAGNETIC fields, ELECTRIC fields, NEAR-field microscopy, FINITE differences, NUMERICAL analysis
Abstract

By scanning near-field optical microscopy, we measured the localization of the electromagnetic field on an array of gold nanodisks illuminated in a transmission mode. We experimentally observed that the field is localized between the disks, with a pattern oriented along the incident polarization direction. We also observed that the electromagnetic field rapidly decays above the nanodisks, showing a strong vertical localization. The experimental results are in good agreement with numerical simulations performed by a finite difference time domain method. This study provides quantitative information about the local optical properties of closely-packed nanodisks that can be used for applications in biochemical sensors and nanolithography. [ABSTRACT FROM AUTHOR]

Published
2011
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30. Magnetic coupling in epitaxial TM/MgO/Fe(001) (TM=FeCo, Fe/Co, Fe) macroscopic and microscopic trilayers.

Author

Boubeta, C. Martínez, de Teresa, J.M., Costa-Krämer, J.L., Anguita, J., Serrate, D., Arnaudas, J.I., Ibarra, M.R., Cebollada, A., and Briones, F.

Subjects
HETEROSTRUCTURES, FERROMAGNETIC materials, ELECTRON diffraction
Abstract

Reports on the epitaxial growth of multilayered TM/MgO/Fe heterostructures to study the dependence of the magnetic coupling between the two ferromagnetic electrodes on the insulating MgO barrier width and the lateral dimensions of the structures. Investigation of the crystal quality by reflection high-energy electron diffraction in situ at different growth stages of the heterostructures.

Published
2003

32. Photoluminescence form polymer-like hydrogenated and nitrogenated amorphous carbon films.

Author

Anguita, J. V., Silva, S. R. P., and Young, W.

Subjects
*PHOTOLUMINESCENCE, *AMORPHOUS substances
Abstract

Studies the photoluminescence (PL) form polymer-like hydrogenated and nitrogenated amorphous carbon films grown by radio frequency driven plasma enhanced chemical vapor deposition. Effect of nitrogen flow rate during growth and postgrowth; Ex situ annealing on PL properties of films; Correlation of the PL spectra to the electronic structure of films.

Published
2000
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33. Effect of reactive ion beam etching on the photoluminescence of CdTe epitaxial layers

Author

Martinez-Pastor, J., Fuster, D., Abellan, M., Anguita, J., and Sochinskii, N.V.

Subjects
Photoluminescence -- Analysis, Ion bombardment -- Analysis, Tellurium -- Optical properties, Physics
Abstract

The influence of reactive ion beam etching (RIBE) process on the photoluminescence (PL) properties of CdTe/sapphire metal organic vapor phase epitaxy layers is demonstrated. The results revealed that at optimum conditions, the RIBE attack does not make significant morphological changes but it results in an increase of the concentration of acceptor impurities.

Published
2008

39. Resonant Raman scattering study of InSb etched by reactive ion beam etching.

Author

Sendra, J. R., Armelles, G., Utzmeier, T., Anguita, J., and Briones, F.

Subjects
SEMICONDUCTORS, SOLID state electronics
Abstract

Presents information on a Raman study of InSb etched by reactive ion beam etching using a CH[sub4]/H[sub2]/N[sub2] plasma generated by electron cyclotron resonance. Experimental procedure; Results and discussion.

Published
1996
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40. THU-301 - MCJ/DnaJC15, the Mitochondrial Foe in Liver Injury

Author

Torres, L.B., Iruzubieta, P., Taibo, D., Cardoso, T., Navasa, N., Ramos, D.F., Rey, M.V., de Juan, V.G., Tussy, P.F., Franco, I.Z., Alvarez, M.I.H., Andrade, R., Medina, I., Monte, M.J., Marín, J.J.G., Crespo, J., Zorzano, A., Mato, J.M., Anguita, J., Rincon, M., and Chantar, M.L.M.

Published
2016
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42. Experimental Vortex Ratchet Effect in Nanostructured Superconductors.

Author

Villegas, J. E., Gonzalez, E. M., Gonzalez, M. P., Nunez, N. O., Anguita, J. V., and Vicent, J. L.

Subjects
SUPERCONDUCTORS, VORTEX motion, ADIABATIC demagnetization, MAGNETIC fields, MAGNETORESISTANCE
Abstract

Superconducting Nb thin films were grown on different arrays of triangle-shape metallic islands. The vortex lattice dynamics could be strongly modified by these asymmetric vortex traps. These asymmetric pinning potentials lead to a rectification effect on the vortex motion: Injecting an ac supercurrent on the sample yields a net dc vortex flow. This vortex ratchet effect is adiabatic and reversible: The effect is frequency independent and the polarity of the dc voltage output could be tuned by the applied magnetic fields and the input ac currents. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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44. Electron Field Emission From Carbon Thin Films.

Author

Silva, S. R. P., Forrest, R. D., Burden, A. P., Anguita, J., Shannon, J. M., Sealy, B. J., Munindradasa, D. A. I., Amaratunga, G. A. J., and Okano, K.

Subjects
CARBON films, ELECTRON field emission, CHEMICAL vapor deposition, HYDROGENATION, ELECTRIC properties of materials
Published
1998

46. Transverse ratchet effect and superconducting vortices: simulation and experiment.

Author

Dinis, L., de Lara, D. Perez, Gonzalez, E. M., Anguita, J. V., Parrondo, J. M. R., and Vicent, J. L.

Subjects
ELECTRON beam lithography, ELECTRON optics, PHOTOLITHOGRAPHY, SUPERCONDUCTORS, ELECTRON beams
Abstract

A transverse ratchet effect has been measured in magnetic/ superconducting hybrid films fabricated by electron beam lithography and magnetron sputtering techniques. The samples are Nb films grown on top of an array of Ni nanotriangles. Injecting an ac current parallel to the triangle reflection symmetry axis yields an output dc voltage perpendicular to the current, due to a net motion of flux vortices in the superconductor. The effect is reproduced by numerical simulations of vortices as Langevin particles with realistic parameters. Simulations provide an intuitive picture of the ratchet mechanism, revealing the fundamental role played by the random intrinsic pinning of the superconductor. [ABSTRACT FROM AUTHOR]

Published
2009
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47. Information Theoretic Limits for Free-Space Optical Channels With and Without Memory.

Author

Denic, S.Z., Djordjevic, I., Anguita, J., Vasic, B., and Neifeld, M.A.

Abstract

The availability of Channel State Information (CSI) and the effects of channel memory on the capacities and the achievable rates of free-space optical communication channels are investigated. For memoryless channels, the capacities and achievable rates are computed and compared for both uniform and ldquopositiverdquo Gaussian inputs subject to different assumptions on the CSI availability. For the strong turbulence regime, it is shown that the knowledge of CSI both at the transmitter and the receiver increases the achievable rates for low-to-moderate Signal-to-Noise Ratios (SNRs) in comparison to the cases for which the CSI is known only at the receiver. For the weak turbulence regime however, the availability of CSI at both ends of the link does not provide any improvement over a system with CSI known at the receiver alone, and we find that a simple channel inversion technique suffices. In addition, for low SNRs, Pulse Amplitude Modulation (PAM) with M ges 4 levels outperforms Gaussian-distributed inputs regardless of the knowledge of CSI at the transmitter. For high SNRs, a Gaussian distribution gives superior results, implying the need for new, more efficient positive signal constellations. For channels with memory and without knowledge of CSI, a change in the channel quasifrequency has negligible effects on the capacity for any turbulence regime. [ABSTRACT FROM PUBLISHER]

Published
2008
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48. LDPC-Coded MIMO Optical Communication Over the Atmospheric Turbulence Channel.

Author

Djordjevic, I.B., Denic, S., Anguita, J., Vasic, B., and Neifeld, M.A.

Abstract

In this paper, coded multiple-input-multiple-output (MIMO) communication schemes for data transmission over the optical atmospheric turbulence channels are studied. Two strategies are proposed and compared. The first is based on repetition coding, and the second on space-time (ST) coding. Both approaches employ low-density parity-check (LDPC) codes. The LDPC codes are designed using the concept of pairwise balanced design (PBD), balanced incomplete block design (BIBBD), and block-circulant (array) codes. To improve the spectral efficiency, we employ a bit-interleaved (BI) LDPC-coded modulation based on the pulse amplitude modulation (PAM). A better bit error rate (BER) performance is achieved by the iteration of extrinsic information between a demapper and LDPC decoder. The simulations show that the LDPC-coded MIMO schemes can operate under a strong atmospheric turbulence and at the same time provide excellent coding gains compared with the transmission of uncoded data. To verify the efficiency of the proposed coding schemes, achievable information rates are computed when the turbulence is modeled by a gamma-gamma distribution. [ABSTRACT FROM PUBLISHER]

Published
2008
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50. Lattice effects and current reversal in superconducting ratchets.

Author

Dinis, L., González, E. M., Anguita, J. V., Parrondo, J. M. R., and Vicent, J. L.

Subjects
LATTICE theory, HYDRODYNAMICS, VORTEX motion, FORCE & energy, SUPERCONDUCTORS, PHYSICS
Abstract

Competition between the vortex lattice and a lattice of asymmetric artificial defects is shown to play a crucial role in ratchet experiments in superconducting films. We present a novel and collective mechanism for current reversal based on a reconfiguration of the vortex lattice. In contrast to previous models of vortex current reversal, the mechanism is based on the global response of the vortex lattice to external forces. [ABSTRACT FROM AUTHOR]

Published
2007
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