2,311 research outputs found
Non-perturbative effective interactions from fluxes
Motivated by possible implications on the problem of moduli stabilization and
other phenomenological aspects, we study D-brane instanton effects in flux
compactifications. We focus on a local model and compute non-perturbative
interactions generated by gauge and stringy instantons in a N = 1 quiver theory
with gauge group U(N_0) x U(N_1) and matter in the bifundamentals. This model
is engineered with fractional D3-branes at a C^3/(Z_2 x Z_2) singularity, and
its non-perturbative sectors are described by introducing fractional
D-instantons. We find a rich variety of instanton-generated F- and D-term
interactions, ranging from superpotentials and Beasley-Witten like
multi-fermion terms to non-supersymmetric flux-induced instanton interactions.Comment: 37 pages, 7 figures. Final version published on JHEP. Section 4
modified in several points regarding string corrections in absence of fluxes;
in particular, section 4.3 is removed. Some other minor changes and two
references adde
El magnetómetro por gradiente alternante de campo: una nueva herramienta para la caracterización de nanopartículas magnéticas en biofluidos y tejidos biológicos
Las aplicaciones que ofrecen las nanopartículas magnéticas basadas en sus interacciones con los campos magnéticos estáticos o variantes en el tiempo, son uno de los principales y más prometedores focos de investigación biomédica en la actualidad. La caracterización magnética de las partículas y de su comportamiento en el interior de materiales biológicos es un aspecto susceptible de numerosas mejoras, siendo además uno de los pasos preliminares fundamentales a la realización de cualquiera de los experimentos que las empleen. En este artículo se presenta una nueva herramienta que facilitará esta tarea, además de presentar futuras líneas de acción que ofrecerán nuevas posibilidades en el mundo de la nanobioingeniería, partiendo de una breve introducción teórica en la que se presentarán los principios físicos que se encuentran en la base de las aplicaciones biomédicas de las nanopartículas. Las aplicaciones que ofrecen las nanopartículas magnéticas basadas en sus interacciones con los campos magnéticos estáticos o variantes en el tiempo, son uno de los principales y más prometedores focos de investigación biomédica en la actualidad. La caracterización magnética de las partículas y de su comportamiento en el interior de materiales biológicos es un aspecto susceptible de numerosas mejoras, siendo además uno de los pasos preliminares fundamentales a la realización de cualquiera de los experimentos que las empleen. En este artículo se presenta una nueva herramienta que facilitará esta tarea, además de presentar futuras líneas de acción que ofrecerán nuevas posibilidades en el mundo de la nanobioingeniería, partiendo de una breve introducción teórica en la que se presentarán los principios físicos que se encuentran en la base de las aplicaciones biomédicas de las nanopartículas
The cefazolin inoculum effect is associated with increased mortality in methicillin-susceptible staphylococcus aureus bacteremia
Background. Recent studies have favored the use of cefazolin over nafcillin for the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. The clinical influence of the cefazolin inoculum effect (CzIE) in the effectiveness of cephalosporins for severe MSSA infections has not been evaluated. Methods. We prospectively included patients from 3 Argentinian hospitals with S. aureus bacteremia. Cefazolin minimum inhibitory concentrations (MICs) were determined at standard (105 colony-forming units [CFU]/mL) and high (107 CFU/mL) inoculum. The CzIE was defined as an increase of MIC to ≥16 µg/mL when tested at high inoculum. Whole-genome sequencing was performed in all isolates. Results. A total of 77 patients, contributing 89 MSSA isolates, were included in the study; 42 patients (54.5%) had isolates with the CzIE. In univariate analysis, patients with MSSA exhibiting the CzIE had increased 30-day mortality (P = .034) and were more likely to have catheter-associated or unknown source of bacteremia (P = .033) compared with patients infected with MSSA isolates without the CzIE. No statistically significant difference between the groups was observed in age, clinical illness severity, place of acquisition (community vs hospital), or presence of endocarditis. The CzIE remained associated with increased 30-day mortality in multivariate analysis (risk ratio, 2.65; 95% confidence interval, 1.10-6.42; P = .03). MSSA genomes displayed a high degree of heterogeneity, and the CzIE was not associated with a specific lineage. Conclusions. In patients with MSSA bacteremia where cephalosporins are used as firstline therapy, the CzIE was associated with increased 30-day mortality. Clinicians should be cautious when using cefazolin as firstline therapy for these infections.Fil: Goss, William Miller. University of Texas; Estados UnidosFil: Seas, Carlos. Universidad Peruana Cayetano Heredia; PerúFil: Carvajal, Lina P.. Universidad El Bosque; ColombiaFil: Diaz, Lorena. Universidad El Bosque; Colombia. UTHealth McGovern Medical School; Estados UnidosFil: Echeverri, Aura M.. Universidad El Bosque; ColombiaFil: Ferro, Carolina. Universidad El Bosque; ColombiaFil: Rios, Rafael. Universidad El Bosque; ColombiaFil: Porras, Paola. Universidad El Bosque; ColombiaFil: Luna, Carlos. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Gotuzzo, Eduardo. Universidad Peruana Cayetano Heredia; PerúFil: Munita, Jose M.. Universidad del Desarrollo. Facultad de Medicina Clínica Alemana; ChileFil: Nannini, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Inmunología Clinica y Experimental de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Médicas. Instituto de Inmunología Clinica y Experimental de Rosario; ArgentinaFil: Carcamo, Cesar. Universidad Peruana Cayetano Heredia; PerúFil: Reyes, Jinnethe. Universidad El Bosque; ColombiaFil: Arias, Cesar A.. University of Texas; Estados Unido
Cerebral venous thrombosis due to vaccine-induced immune thrombotic thrombocytopenia after a second ChAdOx1 nCoV-19 dose.
© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.Cerebral venous thrombosis (CVT) is the most common and severe manifestation of vaccine-induced immune thrombotic thrombocytopenia (VITT), which is a rare side effect of the SARS-CoV-2 vaccine ChAdOx1 nCoV-19 (Vaxzevria, AstraZeneca/Oxford). The absolute risk of VITT and VITT-related CVT is estimated at 20 and 8 per million first doses of ChAdOx1 nCoV-19, respectively.
So far, no definite VITT cases occurring after a second ChAdOx1 nCoV-19 vaccine dose have been reported, raising the question of whether VITT only occurs after a first dose. Two pharmacovigilance studies reported cases of thrombosis with thrombocytopenia after a second ChAdOx1 nCoV-19 dose, but because of lack of clinical data, none of these could be classified as VITT. Knowledge on whether VITT can occur after a second ChAdOx1 nCoV-19 dose is relevant for clinicians and policymakers, especially in low- and middle-income countries, which are currently the main users of adenovirus-based vaccines.
We used data from the “CVT after SARS-CoV-2 vaccination” registry to identify VITT-related CVT cases occurring after a second ChAdOx1 nCoV-19 dose.
Details of this registry have been published. Briefly, this ongoing study collects data on patients with CVT with symptom onset ≤28 days from SARS-CoV-2 vaccination, regardless of the type and dose of vaccine. The study is endorsed by the European Academy of Neurology and the European Stroke Organization. Investigators are instructed to report consecutive cases from their hospitals. The ethical review board of the Academic Medical Centre issued a waiver of formal approval for this observational study. Each center obtained local permission to carry out the study and acquired informed consent for the use of pseudonymized care data according to national law.
We used the case definition criteria of the United Kingdom expert hematology panel to classify cases as definite, probable, possible, or unlikely VITT after ChAdOx1 nCoV-19 administration among CVT cases reported until 1 December 2021.This work was supported by The Netherlands Organisation for Health Research and Development (ZonMw, grant number 10430072110005) (J.M.C.) and the Dr. C. J. Vaillant Foundation (J.M.C.).info:eu-repo/semantics/publishedVersio
Post-SARS-CoV-2-vaccination cerebral venous sinus thrombosis : an analysis of cases notified to the European Medicines Agency
Background and purpose Cerebral venous sinus thrombosis (CVST) has been described after vaccination against SARS-CoV-2. The clinical characteristics of 213 post-vaccination CVST cases notified to the European Medicines Agency are reported. Methods Data on adverse drug reactions after SARS-CoV-2 vaccination notified until 8 April 2021 under the Medical Dictionary for Regulatory Activities Term 'Central nervous system vascular disorders' were obtained from the EudraVigilance database. Post-vaccination CVST was compared with 100 European patients with CVST from before the COVID-19 pandemic derived from the International CVST Consortium. Results In all, 213 CVST cases were identified: 187 after AstraZeneca/Oxford (ChAdOx1 nCov-19) vaccination and 26 after a messenger RNA (mRNA) vaccination (25 with Pfizer/BioNTech, BNT162b2, and one with Moderna, mRNA-1273). Thrombocytopenia was reported in 107/187 CVST cases (57%, 95% confidence interval [CI] 50%-64%) in the ChAdOx1 nCov-19 group, in none in the mRNA vaccine group (0%, 95% CI 0%-13%) and in 7/100 (7%, 95% CI 3%-14%) in the pre-COVID-19 group. In the ChAdOx1 nCov-19 group, 39 (21%) reported COVID-19 polymerase chain reaction tests were performed within 30 days of CVST symptom onset, and all were negative. Of the 117 patients with a reported outcome in the ChAdOx1 nCov-19 group, 44 (38%, 95% CI 29%-47%) had died, compared to 2/10 (20%, 95% CI 6%-51%) in the mRNA vaccine group and 3/100 (3%, 95% CI 1%-8%) in the pre-COVID-19 group. Mortality amongst patients with thrombocytopenia in the ChAdOx1 nCov-19 group was 49% (95% CI 39%-60%). Conclusions Cerebral venous sinus thrombosis occurring after ChAdOx1 nCov-19 vaccination has a clinical profile distinct from CVST unrelated to vaccination. Only CVST after ChAdOx1 nCov-19 vaccination was associated with thrombocytopenia.Peer reviewe
Detection and identification of Xanthomonas pathotypes associated with citrus diseases using comparative genomics and multiplex PCR
Background. In Citrus cultures, three species of Xanthomonas are known to cause distinct diseases. X. citri subsp. citri patothype A, X. fuscans subsp. aurantifolii pathotypes B and C, and X. alfalfae subsp. citrumelonis, are the causative agents of cancrosis A, B, C, and citrus bacterial spots, respectively. Although these species exhibit different levels of virulence and aggressiveness, only limited alternatives are currently available for proper and early detection of these diseases in the fields. The present study aimed to develop a new molecular diagnostic method based on genomic sequences derived from the four species of Xanthomonas. Results. Using comparative genomics approaches, primers were synthesized for the identification of the four causative agents of citrus diseases. These primers were validated for their specificity to their target DNA by both conventional and multiplex PCR. Upon evaluation, their sensitivity was found to be 0.02 ng/mu l in vitro and 1.5 x 10(4) CFU ml(-1) in infected leaves. Additionally, none of the primers were able to generate amplicons in 19 other genomes of Xanthomonas not associated with Citrus and one species of Xylella, the causal agent of citrus variegated chlorosis (CVC). This denotes strong specificity of the primers for the different species of Xanthomonas investigated in this study. Conclusions. We demonstrated that these markers can be used as potential candidates for performing in vivo molecular diagnosis exclusively for citrus-associated Xanthomonas. The bioinformatics pipeline developed in this study to design specific genomic regions is capable of generating specific primers. It is freely available and can be utilized for any other model organism.7CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIG481226/2013-3CFP 51/2013; 3385/2013APQ-02387-1
Frequency of Thrombocytopenia and Platelet Factor 4/Heparin Antibodies in Patients With Cerebral Venous Sinus Thrombosis Prior to the COVID-19 Pandemic
IMPORTANCE Cases of cerebral venous sinus thrombosis in combination with thrombocytopenia have recently been reported within 4 to 28 days of vaccination with the ChAdOx1 nCov-19 (AstraZeneca/Oxford) and Ad.26.COV2.S (Janssen/Johnson & Johnson) COVID-19 vaccines. An immune-mediated response associated with platelet factor 4/heparin antibodies has been proposed as the underlying pathomechanism. OBJECTIVE To determine the frequencies of admission thrombocytopenia, heparin-induced thrombocytopenia, and presence of platelet factor 4/heparin antibodies in patients diagnosed with cerebral venous sinus thrombosis prior to the COVID-19 pandemic. DESIGN, SETTING, AND PARTICIPANTS This was a descriptive analysis of a retrospective sample of consecutive patients diagnosed with cerebral venous sinus thrombosis between January 1987 and March 2018 from 7 hospitals participating in the International Cerebral Venous Sinus Thrombosis Consortium from Finland, the Netherlands, Switzerland, Sweden, Mexico, Iran, and Costa Rica. Of 952 patients, 865 with available baseline platelet count were included. In a subset of 93 patients, frozen plasma samples collected during a previous study between September 2009 and February 2016 were analyzed for the presence of platelet factor 4/heparin antibodies. EXPOSURES Diagnosis of cerebral venous sinus thrombosis. MAIN OUTCOMES AND MEASURES Frequencies of admission thrombocytopenia (platelet count 0.4, in a subset of patients with previously collected plasma samples). RESULTS Of 865 patients (median age, 40 years [interquartile range, 29-53 years], 70% women), 73 (8.4%; 95% CI, 6.8%-10.5%) had thrombocytopenia, which was mild (100-149 x10(3)/mu L) in 52 (6.0%), moderate (50-99 x10(3)/mu L) in 17 (2.0%), and severe ( CONCLUSIONS AND RELEVANCE In patients with cerebral venous sinus thrombosis prior to the COVID-19 pandemic, baseline thrombocytopeniawas uncommon, and heparin-induced thrombocytopenia and platelet factor 4/heparin antibodieswere rare. These findings may inform investigations of the possible association between the ChAdOx1 nCoV-19 and Ad26.COV2.S COVID-19 vaccines and cerebral venous sinus thrombosis with thrombocytopenia.Peer reviewe
Properties of Graphene: A Theoretical Perspective
In this review, we provide an in-depth description of the physics of
monolayer and bilayer graphene from a theorist's perspective. We discuss the
physical properties of graphene in an external magnetic field, reflecting the
chiral nature of the quasiparticles near the Dirac point with a Landau level at
zero energy. We address the unique integer quantum Hall effects, the role of
electron correlations, and the recent observation of the fractional quantum
Hall effect in the monolayer graphene. The quantum Hall effect in bilayer
graphene is fundamentally different from that of a monolayer, reflecting the
unique band structure of this system. The theory of transport in the absence of
an external magnetic field is discussed in detail, along with the role of
disorder studied in various theoretical models. We highlight the differences
and similarities between monolayer and bilayer graphene, and focus on
thermodynamic properties such as the compressibility, the plasmon spectra, the
weak localization correction, quantum Hall effect, and optical properties.
Confinement of electrons in graphene is nontrivial due to Klein tunneling. We
review various theoretical and experimental studies of quantum confined
structures made from graphene. The band structure of graphene nanoribbons and
the role of the sublattice symmetry, edge geometry and the size of the
nanoribbon on the electronic and magnetic properties are very active areas of
research, and a detailed review of these topics is presented. Also, the effects
of substrate interactions, adsorbed atoms, lattice defects and doping on the
band structure of finite-sized graphene systems are discussed. We also include
a brief description of graphane -- gapped material obtained from graphene by
attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic
Importance of genotype for risk stratification in arrhythmogenic right ventricular cardiomyopathy using the 2019 ARVC risk calculator
none41siTo study the impact of genotype on the performance of the 2019 risk model for arrhythmogenic right ventricular cardiomyopathy (ARVC).Protonotarios, Alexandros; Bariani, Riccardo; Cappelletto, Chiara; Pavlou, Menelaos; García-García, Alba; Cipriani, Alberto; Protonotarios, Ioannis; Rivas, Adrian; Wittenberg, Regitze; Graziosi, Maddalena; Xylouri, Zafeirenia; Larrañaga-Moreira, José M; de Luca, Antonio; Celeghin, Rudy; Pilichou, Kalliopi; Bakalakos, Athanasios; Lopes, Luis Rocha; Savvatis, Konstantinos; Stolfo, Davide; Dal Ferro, Matteo; Merlo, Marco; Basso, Cristina; Freire, Javier Limeres; Rodriguez-Palomares, Jose F; Kubo, Toru; Ripoll-Vera, Tomas; Barriales-Villa, Roberto; Antoniades, Loizos; Mogensen, Jens; Garcia-Pavia, Pablo; Wahbi, Karim; Biagini, Elena; Anastasakis, Aris; Tsatsopoulou, Adalena; Zorio, Esther; Gimeno, Juan R; Garcia-Pinilla, Jose Manuel; Syrris, Petros; Sinagra, Gianfranco; Bauce, Barbara; Elliott, Perry MProtonotarios, Alexandros; Bariani, Riccardo; Cappelletto, Chiara; Pavlou, Menelaos; García-García, Alba; Cipriani, Alberto; Protonotarios, Ioannis; Rivas, Adrian; Wittenberg, Regitze; Graziosi, Maddalena; Xylouri, Zafeirenia; Larrañaga-Moreira, José M; de Luca, Antonio; Celeghin, Rudy; Pilichou, Kalliopi; Bakalakos, Athanasios; Lopes, Luis Rocha; Savvatis, Konstantinos; Stolfo, Davide; Dal Ferro, Matteo; Merlo, Marco; Basso, Cristina; Freire, Javier Limeres; Rodriguez-Palomares, Jose F; Kubo, Toru; Ripoll-Vera, Tomas; Barriales-Villa, Roberto; Antoniades, Loizos; Mogensen, Jens; Garcia-Pavia, Pablo; Wahbi, Karim; Biagini, Elena; Anastasakis, Aris; Tsatsopoulou, Adalena; Zorio, Esther; Gimeno, Juan R; Garcia-Pinilla, Jose Manuel; Syrris, Petros; Sinagra, Gianfranco; Bauce, Barbara; Elliott, Perry
Risks of Ventricular Arrhythmia and Heart Failure in Carriers of RBM20 Variants
BACKGROUND: Variants in RBM20 are reported in 2% to 6% of familial cases of dilated cardiomyopathy and may be associated with fatal ventricular arrhythmia and rapid heart failure progression. We sought to determine the risk of adverse events in RBM20 variant carriers and the impact of sex on outcomes. METHODS: Consecutive probands and relatives carrying RBM20 variants were retrospectively recruited from 12 cardiomyopathy units. The primary end point was a composite of malignant ventricular arrhythmia (MVA) and end-stage heart failure (ESHF). MVA and ESHF end points were also analyzed separately and men and women compared. Left ventricular ejection fraction (LVEF) contemporary to MVA was examined. RBM20 variant carriers with left ventricular systolic dysfunction (RBM20LVSD) were compared with variant-elusive patients with idiopathic left ventricular systolic dysfunction. RESULTS: Longitudinal follow-up data were available for 143 RBM20 variant carriers (71 men; median age, 35.5 years); 7 of 143 had an MVA event at baseline. Thirty of 136 without baseline MVA (22.0%) reached the primary end point, and 16 of 136 (11.8%) had new MVA with no significant difference between men and women (log-rank P=0.07 and P=0.98, respectively). Twenty of 143 (14.0%) developed ESHF (17 men and 3 women; log-rank P<0.001). Four of 10 variant carriers with available LVEF contemporary to MVA had an LVEF >35%. At 5 years, 15 of 67 (22.4%) RBM20LVSD versus 7 of 197 (3.6%) patients with idiopathic left ventricular systolic dysfunction had reached the primary end point (log-rank P<0.001). RBM20 variant carriage conferred a 6.0-fold increase in risk of the primary end point. CONCLUSIONS: RBM20 variants are associated with a high risk of MVA and ESHF compared with idiopathic left ventricular systolic dysfunction. The risk of MVA in male and female RBM20 variant carriers is similar, but male sex is strongly associated with ESHF.</p
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