278 research outputs found

    Differential orthogonality: Laguerre and Hermite cases with applications

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    Let μ be a finite positive Borel measure supported on R , L[f]=xf′′+(α+1−x)f′ with α>−1 , or L[f]=12f′′−xf′ , and m a natural number. We study algebraic, analytic and asymptotic properties of the sequence of monic polynomials {Qn}n>m that satisfy the orthogonality relations ∫L[Qn](x)xkdμ(x)=0for all0≤k≤n−1. Turn MathJax off We also provide a fluid dynamics model for the zeros of these polynomials.The authors thank the comments and suggestions made by the referees which helped improve the manuscript. First author’s research was partially supported by FAPESP of Brazil, under grant 2012/21042-0. First and second authors’ research was partially supported by Ministerio de Economía y Competitividad of Spain, under grant MTM2012-36732-C03-01

    On the effect of COVID-19 pandemic in the excess of human mortality. The case of Brazil and Spain

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    Excess of deaths is a technique used in epidemiology to assess the deaths caused by an unexpected event. For the present COVID-19 pandemic, we discuss the performance of some linear and nonlinear time series forecasting techniques widely used for modeling the actual pandemic and provide estimates for this metric from January 2020 to April 2021. We apply the results obtained to evaluate the evolution of the present pandemic in Brazil and Spain, which allows in particular to compare how well (or bad) these countries have managed the pandemic. For Brazil, our calculations refute the claim made by some officials that the present pandemic is "a little flu". Some studies suggest that the virus could be lying dormant across the world before been detected for the first time. In that regard, our results show that there is no evidence of deaths by the virus in 2019This work was supported in the form of funding in part by Ministerio de Ciencia e Innovacio´n of Spain (Grant No. PID2019-108079GB-C22/AEI/10.13039/501100011033)awarded to N

    Orthogonal polynomials with respect to differential operators and matrix orthogonal polynomials

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    En esta tesis concierne con el concepto de polinomios ortogonales con respecto a un operador diferencial, el estudio del comportamiento asintótico fuerte de las funciones propias polinomiales de operadores exactamente solubles y polinomios ortogonales matriciales

    Evaluation of a Low-Cost Virtual Reality Surround-Screen Projection System

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    [EN] Two of the most popular mediums for virtual reality are head-mounted displays and surround-screen projection systems, such as CAVE Automatic Virtual Environments. In recent years, HMDs suffered a significant reduction in cost and have become widespread consumer products. In contrast, CAVEs are still expensive and remain accessible to a limited number of researchers. This study aims to evaluate both objective and subjective characteristics of a CAVE-like monoscopic low-cost virtual reality surround-screen projection system compared to advanced setups and HMDs. For objective results, we measured the head position estimation accuracy and precision of a low-cost active infrared (IR) based tracking system, used in the proposed low-cost CAVE, relatively to an infrared marker-based tracking system, used in a laboratory-grade CAVE system. For subjective characteristics, we investigated the sense of presence and cybersickness elicited in users during a visual search task outside personal space, beyond arms reach, where the importance of stereo vision is diminished. Thirty participants rated their sense of presence and cybersickness after performing the VR search task with our CAVE-like system and a modern HMD. The tracking showed an accuracy error of 1.66 cm and .4 mm of precision jitter. The system was reported to elicit presence but at a lower level than the HMD, while causing significant lower cybersickness. Our results were compared to a previous study performed with a laboratory-grade CAVE and support that a VR system implemented with low-cost devices could be a viable alternative to laboratory-grade CAVEs for visual search tasks outside the users personal space.This work was supported by the Fundação para a Ciência e Tecnologia through the AHA project (CMUPERI/HCI/0046/2013), by the INTERREG program through the MACBIOIDI project (MAC/1.1.b/098), LARSyS (UIDB/50009/2020), NOVA-LINCS (UID/CEC/04516/2019), by Fundació la Marató de la TV3 (201701-10), and the European Union through the Operational Program of the European Regional Development Fund (ERDF) of the Valencian Community 2014-2020 (IDIFEDER/2018/029)Gonçalves, A.; Borrego, A.; Latorre, J.; Llorens Rodríguez, R.; Bermúdez, S. (2021). Evaluation of a Low-Cost Virtual Reality Surround-Screen Projection System. IEEE Transactions on Visualization and Computer Graphics. 1-12. https://doi.org/10.1109/TVCG.2021.3091485S11

    AS REGIÕES CENTRAL E SUL DA ZONA DE OSSA-MORENA

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    Síntese da estrutura, magmatismo e evolução tectono-estratigráfica da Zona de Ossa-Morena

    Serum markers of B cell activation in pregnant women with atopic asthma

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    PROBLEM: As maternal atopy represents a risk factor for the development of atopy in offspring, we aimed to assess how pregnancy affects B cell activation markers in women with atopic asthma and whether they correlate with risk manifestations for allergy in newborns from mothers with atopic asthma. METHOD OF STUDY: Pregnant women with atopic asthma (AP) in the third trimester of gestation and nonpregnant women with atopic asthma (ANP) were prospectively recruited and compared to respective healthy counterparts (HP and HNP). All pregnant women were also assessed during the postpartum period until 6 weeks after delivery (HP/PP and AP/PP). Newborns were clinically evaluated at the age of 6 months. Peripheral blood samples were taken from each woman at each time point. Soluble CD23 (sCD23), B cell activating factor (BAFF), IgA, IgG, IgM, kappa (κ) and lambda (λ) free light chains (FLC) were quantified in serum samples. RESULTS: The AP group presented increased sCD23 (P <0.05) and BAFF (P <0.001) levels compared to the ANP group and even higher levels of sCD23 during the postpartum period (P <0.001). Moreover, the cut-offs of 6.74 g/L for IgG (sensitivity 90.9%, specificity 77.8%) and of 11.30 mg/L for λ FLC (sensitivity 81.8%, specificity 88.9%) in the AP group were predictive factors for the manifestation of allergy in their offspring. CONCLUSIONS: After delivery, the dynamics of sCD23 and BAFF changed significantly in the AP group. Furthermore, we found novel predictive factors for allergy manifestations in the children of these women, with potential clinical application.publishersversionpublishe

    Genotypic resistance profiles of HIV-2 infected patients from Cape Verde failing first-line antiretroviral therapy

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    The pol gene from HIV-2 infected patients from Cape Verde experiencing virologic failure was sequenced and drug resistance mutations were determined. Most patients were taking a first line regimen of AZT, 3TC and LPV/r. Resistance mutations were found in most patients (11/17, 64.7%) especially I82F (4/7, 57.1%) and M184 V (10/17, 58.8%). Resistance to all reverse transcriptase and protease inhibitors was found in 58.8% (10/17) of the patients. Integrase inhibitors are warranted to treat these patients.info:eu-repo/semantics/acceptedVersio

    The Role of NK and T Cells in Endometriosis

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    Endometriosis, a debilitating condition, affects one in ten women of reproductive age. Its pathophysiology remains unclear, though deficiencies in immune surveillance are thought to create an environment conducive to the evasion of ectopic endometrial cells from the immune system. Our research explores the immunological impact of endometriosis both locally and systemically, emphasizing natural killer (NK) and T cell subpopulations. We incorporated 62 female patients who underwent laparoscopic surgery; of those, 47 had endometriosis, and 15 were controls. We collected peritoneal fluid (PF) and peripheral blood (PB) samples which were tagged with monoclonal antibodies and subsequently scrutinized using flow cytometry. Our findings revealed significant differences in immunological profiles based on demographic factors and symptomatology. In the endometriosis cohort, there was an increase in PB CD56 HiCD16 dim and PF CD8 + CD56 dimCD16 Hi NK cells. CD16 + CD4 T cell levels were significantly lower in the PB of endometriosis patients who smoke. Individuals with more severe disease displayed significantly higher levels of PB CD16 + CD8 T cells, which also increased in those with non-menstrual pelvic pain. Dysmenorrhea severity correlated with a progressive increase in PF CD8 + CD56 dimCD16 Hi NK cells. These variations in specific lymphocyte subsets, namely, within NK and T cells, suggest potential immunological mechanisms in the evolution and clinical presentation of endometriosis.publishersversionpublishe

    Impact of land use on urban mobility patterns, emissions and air quality in a Portuguese medium-sized city

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    The main objective of this work was to evaluate the impact of urban development trends in mobility patterns of a medium sized Portuguese city and air quality consequences, using a sequential modeling process, comprising i) land use and transportation, TRANUS model; ii) road traffic air pollutants emissions, TREM model and; iii) air quality, TAPM model. This integrated methodology was applied to a medium sized Portuguese city. In order to evaluate the implementation of the methodology, a preliminary study was performed, which consisted on the comparison of modeled mobility patterns and CO and PM(10) concentrations with measured data used in the definition of the current scenario. The comparison between modeled and monitored mobility patterns at the morning peak hour for a weekday showed an RMSE of 31%. Regarding CO concentrations, an underestimation of the modeled results was observed. Nevertheless, the modeled PM(10) concentrations were consistent with the monitored data. Overall, the results showed a reasonable consistency of the modeled data, which allowed the use of the integrated modeling system for the study scenarios. The future scenarios consisted on the definition of different mobility patterns and vehicle technology characteristics, according to two main developing trends: (1) "car pooling" scenario, which imposes a mean occupancy rate of 3 passengers by vehicle and (2) the "Euro 6" scenario, which establishes that all vehicles accomplish at least the Euro 6 standard technology. Reductions of 54% and 83% for CO, 44% and 95% for PM(10), 44% and 87% for VOC and 44% and 79% for NO(x) emissions were observed in scenarios 1 and 2, respectively. Concerning air quality, a reduction of about 100 mug m(-3) of CO annual average concentration was observed in both scenarios. The results of PM(10) annual concentrations showed a reduction of 1.35 mug m(-3) and 2.7 mug m(-3) for scenarios 1 and 2 respectively
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