77 research outputs found

    Higher secant varieties of Pn×Pm\mathbb{P}^n \times \mathbb{P}^m embedded in bi-degree (1,d)(1,d)

    Get PDF
    Let X(1,d)(n,m)X^{(n,m)}_{(1,d)} denote the Segre-Veronese embedding of Pn×Pm\mathbb{P}^n \times \mathbb{P}^m via the sections of the sheaf O(1,d)\mathcal{O}(1,d). We study the dimensions of higher secant varieties of X(1,d)(n,m)X^{(n,m)}_{(1,d)} and we prove that there is no defective sths^{th} secant variety, except possibly for nn values of ss. Moreover when (m+dd){m+d \choose d} is multiple of (m+n+1)(m+n+1), the sths^{th} secant variety of X(1,d)(n,m)X^{(n,m)}_{(1,d)} has the expected dimension for every ss.Comment: 8 page

    Secant varieties to osculating varieties of Veronese embeddings of PnP^n.

    Get PDF
    A well known theorem by Alexander-Hirschowitz states that all the higher secant varieties of Vn,dV_{n,d} (the dd-uple embedding of \PP n) have the expected dimension, with few known exceptions. We study here the same problem for Tn,dT_{n,d}, the tangential variety to Vn,dV_{n,d}, and prove a conjecture, which is the analogous of Alexander-Hirschowitz theorem, for n9n\leq 9. Moreover. we prove that it holds for any n,dn,d if it holds for d=3d=3. Then we generalize to the case of Ok,n,dO_{k,n,d}, the kk-osculating variety to Vn,dV_{n,d}, proving, for n=2n=2, a conjecture that relates the defectivity of σs(Ok,n,d)\sigma_s(O_{k,n,d}) to the Hilbert function of certain sets of fat points in \PP n

    Use of Microsatellites to Study Agricultural Biodiversity and Food Traceability

    Get PDF
    Molecular markers are useful tools for measuring the genetic diversity among agricultural species. In plants, microsatellites are still the most used markers for germplasm characterization, conservation, and traceability purposes, while in the livestock sector, although having represented the standard for at least two decades, they are still used only for minor farm animal species. In this work, together with a review on the use of microsatellites in livestock, we also illustrate the use of these markers for the characterization of agricultural diversity and food traceability through two case studies: (i) the analysis of genetic diversity in ancient fruit tree cultivars of apple (Malus × domestica Borkh.), pear (Pyrus communis L.), sweet cherry (Prunus avium L.), and sour cherry (Prunus cerasus L.) from Northern Italy and (ii) the molecular authentication of wheat food chain. In the former case, a high genetic variability as well as the presence of different ploidy levels were detected, while in the latter microsatellite markers were shown to be useful for traceability and product authentication along the whole food chain. Overall, the presented evidence confirms the versatility of microsatellites as markers for both agrobiodiversity characterization and food traceability in cultivated plants and farm animals

    Educação transpessoal : integrando o saber ao ser no processo educativo

    Get PDF
    Orientador : Carlos Alberto Vidal FrançaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de EducaçãoDoutorad

    Evaluación del aspecto propedéutico del aprendizaje matemático en el ciclo medio

    Get PDF
    En este trabajo se muestra la implementación, los resultados y las conclusiones de una prueba piloto para evaluar el valor propedéutico del aprendizaje matemático de todo el ciclo medio, teniendo en cuenta los requerimientos del ingreso universitario

    Growing Up with Type 1 narcolepsy: Its anthropometric and endocrine features

    Get PDF
    Study Objectives: To evaluate the effect of type 1 narcolepsy (NT1) on anthropometric and endocrine features in childhood/adolescence, focusing on patterns and correlates of weight, pubertal development, and growth in treated and untreated patients. Methods: We collected anthropometric (height, weight, body mass index (BMI) z-scores), pubertal, metabolic, and endocrine data from 72 NT1 patients at diagnosis and all available premorbid anthropometric parameters of patients from their pediatric files (n = 30). New measurements at 1-y reassessment in patients undergoing different treatments were compared with baseline data. Results: We detected a high prevalence of overweight (29.2%), obesity (25%), metabolic syndrome (18.8%), and precocious puberty (16.1%), but no signs of linear growth alterations at diagnosis. According to anthropometric records, weight gain started soon after NT1 onset. At 1-y follow-up reassessment, sodium oxybate treatment was associated with a significant BMI z-score reduction (-1.29 \ub1 0.30, p < 0.0005) after adjusting for baseline age, sex, sleepiness, and BMI. Conclusions: NT1 onset in children/adolescents is associated with rapid weight gain up to overweight/obesity and precocious puberty without affecting growth. In our study, sodium oxybate treatment resulted in a significant weight reduction in NT1 overweight/obese patients at 1-y follow-up

    CFTR Modulation Reduces SARS-CoV-2 Infection in Human Bronchial Epithelial Cells

    Get PDF
    People with cystic fibrosis should be considered at increased risk of developing severe symptoms of COVID-19. Strikingly, a broad array of evidence shows reduced spread of SARS-CoV-2 in these subjects, suggesting a potential role for CFTR in the regulation of SARS-CoV-2 infection/replication. Here, we analyzed SARS-CoV-2 replication in wild-type and CFTR-modified human bronchial epithelial cell lines and primary cells to investigate SARS-CoV-2 infection in people with cystic fibrosis. Both immortalized and primary human bronchial epithelial cells expressing wt or F508del-CFTR along with CRISPR/Cas9 CFTR-ablated clones were infected with SARS-CoV-2 and samples were harvested before and from 24 to 72 h post-infection. CFTR function was also inhibited in wt-CFTR cells with the CFTR-specific inhibitor IOWH-032 and partially restored in F508del-CFTR cells with a combination of CFTR modulators (VX-661+VX-445). Viral load was evaluated by real-time RT-PCR in both supernatant and cell extracts, and ACE-2 expression was analyzed by both western blotting and flow cytometry. SARS-CoV-2 replication was reduced in CFTR-modified bronchial cells compared with wild-type cell lines. No major difference in ACE-2 expression was detected before infection between wild-type and CFTR-modified cells, while a higher expression in wild-type compared to CFTR-modified cells was detectable at 72 h post-infection. Furthermore, inhibition of CFTR channel function elicited significant inhibition of viral replication in cells with wt-CFTR, and correction of CFTR function in F508del-CFTR cells increased the release of SARS-CoV-2 viral particles. Our study provides evidence that CFTR expression/function is involved in the regulation of SARS-CoV-2 replication, thus providing novel insights into the role of CFTR in SARS-CoV-2 infection and the development of therapeutic strategies for COVID-19

    Grassmann secants, identifiability, and linear systems of tensors

    Get PDF
    For any irreducible non-degenerate variety XPrX\subset \mathbb{P}^r, we give a criterion for the (k,s)(k,s)-identifiability of XX. If ks1<rk\leq s-1 <r, then the (k,s)(k,s)-identifiability holds for XX if and only if the ss-identifiability holds for the Segre product Seg(Pk×X)Seg(\mathbb{P}^k\times X). Moreover, if the ss-th secant variety of XX is not defective and it does not fill the ambient space, then we can produce a family of pairs (k,s)(k,s) for which the (k,s)(k,s)-identifiability holds for XX.Comment: Accepted for the publication: Linear Algebra and its Application

    Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

    Full text link
    We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals
    corecore