2,097 research outputs found

    Drought Legacy in Sub-Seasonal Vegetation State and Sensitivity to Climate Over the Northern Hemisphere

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    Droughts affect ecosystems at multiple time scales, but their sub-seasonal legacy effects on vegetation activity remain unclear. Combining the satellite-based enhanced vegetation index MODIS EVI with a novel location-specific definition of the growing season, we quantify drought impacts on sub-seasonal vegetation activity and the subsequent recovery in the Northern Hemisphere. Drought legacy effects are quantified as changes in post-drought greenness and sensitivity to climate. We find that greenness losses under severe drought are partially compensated by a similar to+5% greening within 2-6 growing-season months following the droughts, both in woody and herbaceous vegetation but at different timings. In addition, post-drought sensitivity of herbaceous vegetation to hydrological conditions increases noticeably at high latitudes compared with the local normal conditions, regardless of the choice of drought time scales. In general, the legacy effects on sensitivity are larger in herbaceous vegetation than in woody vegetation

    A quantum optical study of thresholdless lasing features in high-β nitride nanobeam cavities

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    Exploring the limits of spontaneous emission coupling is not only one of the central goals in the development of nanolasers, it is also highly relevant regarding future large-scale photonic integration requiring energy-efficient coherent light sources with a small footprint. Recent studies in this field have triggered a vivid debate on how to prove and interpret lasing in the high-β regime. We investigate close-to-ideal spontaneous emission coupling in GaN nanobeam lasers grown on silicon. Such nanobeam cavities allow for efficient funneling of spontaneous emission from the quantum well gain material into the laser mode. By performing a comprehensive optical and quantum-optical characterization, supported by microscopic modeling of the nanolasers, we identify high-β lasing at room temperature and show a lasing transition in the absence of a threshold nonlinearity at 156 K. This peculiar characteristic is explained in terms of a temperature and excitation power-dependent interplay between zero-dimensional and two-dimensional gain contributions.EC/FP7/615613/EU/External Quantum Control of Photonic Semiconductor Nanostructures/EXQUISIT

    Gallium nitride L3 photonic crystal cavities with an average quality factor of 16,900 in the near infrared

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    Photonic crystal point-defect cavities were fabricated in a GaN free-standing photonic crystal slab. The cavities are based on the popular L3 design, which was optimized using an automated process based on a genetic algorithm, in order to maximize the quality factor. Optical characterization of several individual cavity replicas resulted in an average unloaded quality factor Q = 16,900 at the resonant wavelength {\lambda} 1.3\sim 1.3 {\mu}m, with a maximal measured Q value of 22,500. The statistics of both the quality factor and the resonant wavelength are well explained by first-principles simulations including fabrication disorder and background optical absorption.Comment: 3 figure

    Expression of Semaphorin-3A and its receptors in endochondral ossification: potential role in skeletal development and innervation.

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    Bone tissue is densely innervated, and there is increasing evidence for a neural control of bone metabolism. Semaphorin-3A is a very important regulator of neuronal targeting in the peripheral nervous system as well as in angiogenesis, and knockout of the Semaphorin-3A gene induces abnormal bone and cartilage development. We analyzed the spatial and temporal expression patterns of Semaphorin-3A signaling molecules during endochondral ossification, in parallel with the establishment of innervation. We show that osteoblasts and chondrocytes differentiated in vitro express most members of the Semaphorin-3A signaling system (Semaphorin-3A, Neuropilin-1, and Plexins-A1 and -A2). In vitro, osteoclasts express most receptor chains but not the ligand. In situ, these molecules are all expressed in the periosteum and by resting, prehypertrophic and hypertrophic chondrocytes in ossification centers before the onset of neurovascular invasion. They are detected later in osteoblasts and also osteoclasts, with differences in intensity and regional distribution. Semaphorin-3A and Neuropilin-1 are also expressed in the bone marrow. Plexin-A3 is not expressed by bone cell lineages in vitro. It is detected early in the periosteum and hypertrophic chondrocytes. After the onset of ossification, this chain is restricted to a network of cell processes in close vicinity to the cells lining the trabeculae, similar to the pattern observed for neural markers at the same stages. After birth, while the density of innervation decreases, Plexin-A3 is strongly expressed by blood vessels on the ossification front. In conclusion, Semaphorin-3A signaling is present in bone and seems to precede or coincide at the temporal but also spatial level with the invasion of bone by blood vessels and nerve fibers. Expression patterns suggest Plexin-A3/Neuropilin-1 as a candidate receptor in target cells for the regulation of bone innervation by Semaphorin-3A

    Defecting or not defecting: how to "read" human behavior during cooperative games by EEG measurements

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    Understanding the neural mechanisms responsible for human social interactions is difficult, since the brain activities of two or more individuals have to be examined simultaneously and correlated with the observed social patterns. We introduce the concept of hyper-brain network, a connectivity pattern representing at once the information flow among the cortical regions of a single brain as well as the relations among the areas of two distinct brains. Graph analysis of hyper-brain networks constructed from the EEG scanning of 26 couples of individuals playing the Iterated Prisoner's Dilemma reveals the possibility to predict non-cooperative interactions during the decision-making phase. The hyper-brain networks of two-defector couples have significantly less inter-brain links and overall higher modularity - i.e. the tendency to form two separate subgraphs - than couples playing cooperative or tit-for-tat strategies. The decision to defect can be "read" in advance by evaluating the changes of connectivity pattern in the hyper-brain network

    Estrogens Regulate Placental Angiogenesis in Horses

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    A sufficient vascular network within the feto-maternal interface is necessary for placental function. Several pregnancy abnormalities have been associated with abnormal vascular formations in the placenta. We hypothesized that growth and expansion of the placental vascular network in the equine (Equus caballus) placenta is regulated by estrogens (estrogen family hormones), a hormone with a high circulating concentration during equine gestation. Administration of letrozole, a potent and specific inhibitor of aromatase, during the first trimester (D30 to D118), decreased circulatory estrone sulfate concentrations, increased circulatory testosterone and androstenedione concentrations, and tended to reduce the weight of the fetus (p \u3c 0.1). Moreover, the gene expression of CYP17A1 was increased, and the expression of androgen receptor was decreased in the D120 chorioallantois (CA) of letrozole-treated mares in comparison to that of the control mares. We also found that at D120, the number of vessels tended to decrease in the CAs with letrozole treatment (p = 0.07). In addition, expression of a subset of angiogenic genes, such as ANGPT1, VEGF, and NOS2, were altered in the CAs of letrozole-treated mares. We further demonstrated that 17β-estradiol increases the expression of ANGPT1 and VEGF and increases the angiogenic activity of equine endothelial cells in vitro. Our results from the estrogen-suppressed group demonstrated an impaired placental vascular network, suggesting an estrogen-dependent vasculogenesis in the equine CA during the first trimester

    Optical Coherence Tomography Angiography to estimate early retinal blood flow changes after uncomplicated cataract surgery

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    Background: To investigate macular microvascular changes after uncomplicated phacoemulsification surgery according to the cataract severity grade. Methods: Retrospective, cross-sectional study involving 23 eyes of 23 patients who underwent elective cataract extraction. All patients underwent routine ophthalmologic examination, including optical coherence tomography angiography (OCTA) at baseline (preoperative visit, T0) and seven days postoperatively (T7). OCTA scans were obtained with the spectral domain system Cirrus 5000 (Carl Zeiss Meditec, Inc., Dublin, CA, USA), and 3 mm × 3 mm raster fovea-centered scans were obtained to evaluate the superficial capillary plexus (SCP) vessel density, perfusion density, and foveal avascular zone (FAZ) parameters. Results: SCP perfusion density significantly increased from 28.3 ± 5.73% to 33.74 ± 4.13% after the surgery (p < 0.001). Similarly, SCP vessel density significantly increased from 15.14 ± 3.41 mm-1 to 18.14 ± 2.57 mm-1 after surgery (p < 0.001). The mean preoperative FAZ area significantly increased from 0.27 ± 0.12 mm to 0.24 ± 0.11 mm seven days postoperatively (p = 0.008). When comparing softer and harder cataracts, no significant variations in SCP vessel density, as well as SCP perfusion density parameters and the FAZ area, perimeter, and circularity index, were noted before and after surgery. Conclusions: Macular SPC vessel density and macular SCP perfusion density increase after uncomplicated cataract surgery regardless of the cataract severity

    Serological Response to BNT162b2 Anti-SARS-CoV-2 Vaccination in Patients with Inflammatory Rheumatic Diseases: Results From the RHEUVAX Cohort

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    Objective: In the light of the current COVID-19 epidemic and the availability of effective vaccines, this study aims to identify factors associated with non-response to anti-SARS-CoV-2 vaccines as immunological alteration associated with immune rheumatic diseases (IRD) and immunosuppressive medications may impair the response to vaccination. Methods: Volunteers in the health profession community with IRD, age, and sex-matched controls (CTRL) who underwent vaccination with two doses of BNT162b2 were recruited for this study. Anti-Trimeric Spike protein antibodies were assayed eight ± one weeks after the second vaccine dose. Univariate and logistic regression analyses were performed to identify factors independently associated with non-response and low antibody titers. Results: Samples were obtained from 237 IRD patients (m/f 73/164, mean age 57, CI 95% [56-59]): 4 autoinflammatory diseases (AI), 62 connective tissue diseases (CTD), 86 rheumatoid arthritis (RA), 71 spondylarthritis (SpA) and 14 vasculitis (Vsc). 232 CTRL were recruited (m/f 71/161, mean age 57, CI 95% [56-58]). Globally, IRD had a lower seroconversion rate (88.6% vs 99.6%, CI 95% OR [1.61-5.73], p<0.001) and lower antibody titer compared to controls (median (IQR) 403 (131.5-1012) versus 1160 (702.5-1675), p<0.001). After logistic regression, age, corticosteroid (CCS), Abatacept and Mycophenolate Mofetil (MMF) use were associated with non-response. Lower antibody titer was associated with the use of MMF, ABA, CCS, Rituximab, tumor necrosis factor inhibitor, JAK inhibitors, and higher age. Conclusion: The response to anti-SARS-CoV-2 vaccines is often impaired in IRD patients under treatment and may pose them at higher risk of severe COVID-19. Specific vaccination protocols are desirable for these patients

    Planar Wideband Antenna Designs for Wireless Applications in Portable Devices

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    [EN] This paper summarizes the research that has been developed by the authors for the last six years, concerning the design of planar wideband antennas for portable devices. Basic structures combining electric and magnetic elements are proposed, which lead to antennas with large bandwidth. Thus, by using these basic structures, a polarization diversity antenna, a wideband antenna for DVB-H applications and a wideband MIMO antenna have been proposed for wireless applications in mobile terminals. Prototypes of all the antennas have been fabricated and measured at iTEAM and/or CWC facilities.This work was supported by the Spanish Ministerio de Economía y Competitividad under the projects TEC2010-20841-C04-01 and CSD2008-00068, and by the Finnish Funding Agency for Technology and Innovation (Tekes projects AATE and MIMOTA) and its industrial partners, EB, ETS Lindgren, Nokia Devices Oulu and Pulse Finland Inc. Mr. Sonkki also would like to thank the Nokia Foundation and the Infotech Oulu Doctoral Program for financially supporting his PhD studies.Antonino Daviu, E.; Sonkki, M.; Cabedo Fabrés, M.; Ferrando Bataller, M.; Salonen, ET.; Sánchez Escuderos, D.; Herranz Herruzo, JI.... (2014). Planar Wideband Antenna Designs for Wireless Applications in Portable Devices. Waves. 6:17-28. http://hdl.handle.net/10251/52905S1728
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