166 research outputs found

    Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

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    Bound states in the continuum (BICs) are ubiquitous in many areas of physics, attracting especial interest for their ability to confine waves with infinite lifetimes. Metasurfaces provide a suitable platform to realize them in photonics; such BICs are remarkably robust, being however complex to tune in frequency-wavevector space.Here we propose a scheme to engineer BICs and quasi-BICs with single magnetic-dipole resonance meta-atoms. Upon changing the orientation of the magnetic-dipole resonances, we show that the resulting quasi-BICs,emerging from the symmetry-protected BIC at normal incidence, become transparent for plane-wave illumination exactly at the magnetic-dipole angle, due to a Brewster-like effect. While yielding infinite Q-factors at normalincidence(canonical BIC), these are termed Brewster quasi-BICs since a transmission channel is always allowed that slightly widens resonances at oblique incidences. This is demonstrated experimentally through reflectance measurements in the microwave regime with high-refractive-index mm-disk metasurfaces. Such Brewster-inspired configuration is a plausible scenario to achieve quasi-BICs throughout the electromagnetic spectrum inaccessible through plane-wave illumination at given angles, which could be extrapolated to other kind of waves.Comment: 15 pages, 7 figures; typos corrected, Figs. 3 & 5 modified, new Fig. 7 & references adde

    A Rad-hard On-chip CMOS Charge Detector with High Dynamic Range

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    This article introduces a CMOS charge detector tailored for measuring ionizing radiation in a wide range of fluences. It represents an entirely on-chip solution based on capacitive sensing. It was fabricated using a standard 0.18 μm CMOS process and employs Metal-insulator-Metal (MiM) capacitor arrays to attain high matching, low leakage, and minimal process variations. The sensing area was radhardened with a post-CMOS layer of metal deposited with a Focus Ion Beam (FIB) that removes the use of external metallic plates. Experimental testing under the electron beam of a scanning electron microscope (SEM) demonstrated radiation hardness at energies up to 10 keV, with a very high dynamic range of up to 138 dB (externally adjustable), and with a sensitivity of 1.43 μV/e-. By harnessing the detection of relative charge variations instead of relying on absolute values, this approach proves highly suitable for particle event detection and facilitates future integrations compatible with the Address Event Representation (AER) communication protocol.Ministerio de Ciencia, Innovación y Universidades PGC2018-101538-A-I00, PID2021-128009OBC31, VERSO AT21_00096, P20_0120

    Transcriptional regulation by Poly(ADP-ribose) polymerase-1 during T cell activation

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    <p>Abstract</p> <p>Background</p> <p>Accumulating evidence suggests an important role for the enzyme poly(ADP-ribose) polymerase-1 (PARP-1) as an integral part of the gene expression regulatory machinery during development and in response to specific cellular signals. PARP-1 might modulate gene expression through its catalytic activity leading to poly(ADP-ribosyl)ation of nuclear proteins or by its physical association with relevant proteins. Recently, we have shown that PARP-1 is activated during T cell activation. However, the proposed role of PARP-1 in reprogramming T cell gene expression upon activation remains largely unexplored.</p> <p>Results</p> <p>In the present study we use oligonucleotide microarray analysis to gain more insight into the role played by PARP-1 during the gene expression reprogramming that takes place in T cells upon activation with anti-CD3 stimulation alone, or in combination with anti-CD28 co-stimulation. We have identified several groups of genes with expression modulated by PARP-1. The expression of 129 early-response genes to anti-CD3 seems to be regulated by PARP-1 either in a positive (45 genes) or in a negative manner (84 genes). Likewise, in the presence of co-stimulation (anti-CD3 + anti-CD28 stimulation), the expression of 203 genes is also regulated by PARP-1 either up (173 genes) or down (30 genes). Interestingly, PARP-1 deficiency significantly alters expression of genes associated with the immune response such as chemokines and genes involved in the Th1/Th2 balance.</p> <p>Conclusion</p> <p>This study provides new insights into changes in gene expression mediated by PARP-1 upon T cell activation. Pathway analysis of PARP-1 as a nuclear signalling molecule in T cells would be of relevance for the future development of new therapeutic approaches targeting PARP-1 in the acquired immune response.</p

    Estado del arte en el desarrollo de pequeños generadores eólicos

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    El trabajo presenta un estudio sobre el estado del arte del desarrollo de pequeños aerogeneradores. El relevamiento consistió en la búsqueda de fabricantes de pequeños aerogeneradores a nivel mundial. El medio de exploración se remitió a internet y el contacto directo con los proveedores. El objeto de la búsqueda fue recopilar la mayor cantidad de datos sobre las características técnicas constructivas de los equipos, analizando cuestiones como: tipo de generador y rotor utilizados, mecanismos de orientación, de acoplamiento entre generador y rotor, etcétera. Se relevaron también los precios. Si bien existe una dispersión en las características se observa una tendencia general a adoptar un modelo tipo. Se observa también una dispersión importante de precios por unidad de potencia. También puede observarse una dificultad a la hora de presentar la información técnica de los mismos debido a la falta de criterios comunes.This work presents a study about the state of the art development of small wind turbines. The survey was to search for manufacturers of small wind turbines worldwide. The research was made via internet and also via direct contact with the suppliers. The object of the search was to gather as much data as possible on the equipment´s construction techniques, analyzing issues such as: type of generator and rotor used, mechanisms of orientation, of coupling between generator and rotor, and so on. The scope of the research also includes the prices. While there is a dispersion in the characteristics, we can observed a general tendency to adopt a model type, an important dispersion of prices per unit of power, and also we could observed that there is a difficulty in presenting the technical information of them due to the lack of common criteria.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    The scattering of SH waves by a finite crack with a superposition based diffraction technique

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    The problem of diffraction of cylindrical and plane SH waves by a finite crack is revisited -- We construct an approximate solution by the addition of independent diffracted terms -- We start with the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of generalized wedge -- This building block is then used to compute the diffraction of the main incident waves -- The interaction between the opposite edges of the crack is then considered one term at a time until a desired tolerance is reached -- We propose a recipe to determine the number of required interactions as a function of frequency -- The solution derived with the superposition technique can be applied at low and high frequencie

    Aging of ECG characteristics over a five year period

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    The aim of this work was to find evidence of aging of ECG indicators in a population of young adults (52 subjects of age 19 ± 0.6 in 2002). For this purpose, an application which analyzes ECG signals was designed and implemented. The data consist in four different series for each subject of the studied population. Two ECG signals of 5 minute duration (one at rest and one after a mild effort) were taken in 2002 and the exact same procedure was repeated for each subject five years later in 2007. All these electrocardiographic signals were examined by computational techniques in order to extract the RR and QT intervals and the energy content of the T-wave. Next, we have compared all the data using first return maps and measured the data dispersion by evaluating the covariance ellipses. Relations between each of the four data series were studied. The analysis also included the gender and the categorical aspect “practicing sport”

    The role of retinal fluid location in atrophy and fibrosis evolution of patients with neovascular age-related macular degeneration long-term treated in real world

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    Purpose: To assess the effect of clinical factors on the development and progression of atrophy and fibrosis in patients with neovascular age-related macular degeneration (nAMD) receiving long-term treatment in the real world. Methods: An ambispective 36-month multicentre study, involving 359 nAMD patients from 17 Spanish hospitals treated according to the Spanish Vitreoretinal Society guidelines, was designed. The influence of demographic and clinical factors, including the presence and location of retinal fluid, on best-corrected visual acuity (BCVA) and progression to atrophy and/or fibrosis were analysed. Results: After 36 months of follow-up and an average of 13.8 anti-VEGF intravitreal injections, the average BCVA gain was +1.5 letters, and atrophy and/or fibrosis were present in 54.8% of nAMD patients (OR = 8.54, 95% CI = 5.85-12.47, compared to baseline). Atrophy was associated with basal intraretinal fluid (IRF) (OR = 1.87, 95% CI = 1.09-3.20), whereas basal subretinal fluid (SRF) was associated with a lower rate of atrophy (OR = 0.40, 95% CI = 0.23-0.71) and its progression (OR = 0.44, 95% CI = 0.26-0.75), leading to a slow progression rate (OR = 0.34, 95% CI = 0.14-0.83). Fibrosis development and progression were related to IRF at any visit (p < 0.001). In contrast, 36-month SRF was related to a lower rate of fibrosis (OR = 0.49, 95% CI = 0.29-0.81) and its progression (OR = 0.50, 95% CI = 0.31-0.81). Conclusion: Atrophy and/or fibrosis were present in 1 of 2 nAMD patients treated for 3 years. Both, especially fibrosis, lead to vision loss. Subretinal fluid (SRF) was associated with good visual outcomes and lower rates of atrophy and fibrosis, whereas IRF yields worse visual results and a higher risk of atrophy and especially fibrosis in routine clinical practice

    Endemic and epidemic human alphavirus infections in eastern Panama: An analysis of population-based cross-sectional surveys

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    Madariaga virus (MADV) has recently been associated with severe human disease in Panama, where the closely related Venezuelan equine encephalitis virus (VEEV) also circulates. In June 2017, a fatal MADV infection was confirmed in a community of Darien Province. We conducted a cross-sectional outbreak investigation with human and mosquito collections in July 2017, where sera were tested for alphavirus antibodies and viral RNA. In addition, by applying a catalytic, force-of-infection (FOI) statistical model to two serosurveys from Darien Province in 2012 and 2017, we investigated whether endemic or epidemic alphavirus transmission occurred historically. In 2017, MADV and VEEV IgM seroprevalences were 1.6% and 4.4%, respectively; IgG antibody prevalences were MADV: 13.2%, VEEV: 16.8%, Una virus (UNAV): 16.0%, and Mayaro virus: 1.1%. Active viral circulation was not detected. Evidence of MADV and UNAV infection was found near households, raising questions about its vectors and enzootic transmission cycles. Insomnia was associated withMADVand VEEV infections, depression symptoms were associated with MADV, and dizziness with VEEV and UNAV. Force-of-infection analyses suggest endemic alphavirus transmission historically, with recent increased human exposure to MADV and VEEV in Aruza and Mercadeo, respectively. The lack of additional neurological cases suggests that severe MADV and VEEV infections occur only rarely. Our results indicate that over the past five decades, alphavirus infections have occurred at low levels in eastern Panama, but that MADV and VEEV infections have recently increased-potentially during the past decade. Endemic infections and outbreaks of MADV and VEEV appear to differ spatially in some locations of eastern Panama.National Institute for Health ResearchRevisión por pare
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