3,834 research outputs found

    Analytic Kramer kernels, Lagrange-type interpolation series and de Branges spaces

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    The classical Kramer sampling theorem provides a method for obtaining orthogonal sampling formulas. In particular, when the involved kernel is analytic in the sampling parameter it can be stated in an abstract setting of reproducing kernel Hilbert spaces of entire functions which includes as a particular case the classical Shannon sampling theory. This abstract setting allows us to obtain a sort of converse result and to characterize when the sampling formula associated with an analytic Kramer kernel can be expressed as a Lagrange-type interpolation series. On the other hand, the de Branges spaces of entire functions satisfy orthogonal sampling formulas which can be written as Lagrange-type interpolation series. In this work some links between all these ideas are established

    A novel algorithm for dynamic student profile adaptation based on learning styles

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.E-learning recommendation systems are used to enhance student performance and knowledge by providing tailor- made services based on the students’ preferences and learning styles, which are typically stored in student profiles. For such systems to remain effective, the profiles need to be able to adapt and reflect the students’ changing behaviour. In this paper, we introduce new algorithms that are designed to track student learning behaviour patterns, capture their learning styles, and maintain dynamic student profiles within a recommendation system (RS). This paper also proposes a new method to extract features that characterise student behaviour to identify students’ learning styles with respect to the Felder-Silverman learning style model (FSLSM). In order to test the efficiency of the proposed algorithm, we present a series of experiments that use a dataset of real students to demonstrate how our proposed algorithm can effectively model a dynamic student profile and adapt to different student learning behaviour. The results revealed that the students could effectively increase their learning efficiency and quality for the courses when the learning styles are identified, and proper recommendations are made by using our method

    The Utility of a High-intensity Exercise Protocol to Prospectively Assess ACL Injury Risk.

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    This study investigated the utility of a 5-min high-intensity exercise protocol (SAFT(5)) to include in prospective cohort studies investigating ACL injury risk. 15 active females were tested on 2 occasions during which their non-dominant leg was analysed before SAFT(5) (PRE), immediately after (POST0), 15 min after (POST15), and 30 min after (POST30). On the first occasion, testing included 5 maximum isokinetic contractions for eccentric and concentric hamstring and concentric quadriceps and on the second occasion, 3 trials of 2 landing tasks (i. e., single-leg hop and drop vertical jump) were conducted. Results showed a reduced eccentric hamstring peak torque at POST0, POST15 and POST30 (p<0.05) and a reduced functional HQ ratio (Hecc/Qcon) at POST15 and POST30 (p<0.05). Additionally, a more extended knee angle at POST30 (p<0.05) and increased knee internal rotation angle at POST0 and POST15 (p<0.05) were found in a single-leg hop. SAFT(5) altered landing strategies associated with increased ACL injury risk and similar to observations from match simulations. Our findings therefore support the utility of a high-intensity exercise protocol such as SAFT(5) to strengthen injury screening tests and to include in prospective cohort studies where time constraints apply

    Enzymatic hydrolysis of esters from 2-carboxy-6- methoxy-2,3-dihydrobenzofuran acid

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    In this work we describe the results of the enzymatic hydrolysis of esters from 2-carboxy-6-methoxy-2,3-dihydrobenzofuran acid using Candida antarctica lipase supported on acrylic resin, with enantiomeric excesses ranging between 80 to 99%

    A magnetically collimated jet from an evolved star

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    Planetary nebulae often have asymmetric shapes, which could arise due to collimated jets from evolved stars before evolution to the planetary nebula phase. The source of jet collimation in these stars is unknown. Magnetic fields are thought to collimate outflows that are observed in many other astrophysical sources, such as active galactic nuclei and proto-stars, although hitherto there are no direct observations of both the magnetic field direction and strength in any collimated jet. Theoretical models have shown that magnetic fields could also be the dominant source of collimation of jet in evolved stars. Here we report measurements of the polarization of water vapour masers that trace the precessing jet emanating from the asymptotic giant branch star W43A at 2.6 kpc from the Sun, which is undergoing rapid evolution into a planetary nebula. The masers occur in two clusters at opposing tips of the jets, ~1,000 AU from the star. We find direct evidence that the magnetic field is collimating the jet.Comment: Published in Nature 440 (March 2nd 2006). High-res figures can be found at http://www.jb.man.ac.uk/~wouter/papers/w43a/w43a.htm

    Developing a coding scheme for analysing classroom dialogue across educational contexts

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    The research reported sought to develop a framework for systematically analysing classroom dialogue for application across a range of educational settings. The paper outlines the development and refinement of a coding scheme that attempts to represent and operationalise commonalities amongst some key theorists in the field concerning productive forms of educational dialogue. The team has tested it using video recordings from classroom settings in the UK and Mexico, across age phases, subject areas, and different interactional contexts including whole class, group and paired work. Our Scheme for Educational Dialogue Analysis (SEDA) is situated within a sociocultural paradigm, and draws on Hymes' Ethnography of Communication to highlight the importance of context. We examined how such a tool could be used in practice. We found that concentrating on the ‘communicative act’ to explore dialogue between participants was an appropriate level of granularity, while clustering the 33 resulting codes according to function of the acts helped to highlight dialogic sequences within lessons. We report on the application of the scheme in two different learning contexts and reflect on its fitness for purpose, including perceived limitations. Development of specialised sub-schemes and a version for teachers is underway

    PÉRDIDAS DE CARBONO EN SUELOS DE LA LLANURA COSTERA DE NAYARIT, MÉXICO

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    Se analizaron las pérdidas de carbono orgánico en suelos a partir de 12 perfiles localizados en el delta del río San Pedro y distribuidos por nivel geomorfológico en la llanura costera del estado de Nayarit, México. El estudio se realizó comparando el contenido de carbono de los suelos con mayor conservación bajo bosque y cultivados. Los niveles considerados para este análisis fueron llanura alta, llanura media y sus depresiones, llanura baja y barras costeras. Las reservas de carbono (RCO) se determinaron teniendo en cuenta la densidad aparente (Da), el espesor de cada horizonte y el contenido de carbono. Los resultados se ponderaron para las profundidades 0-20, 0-50 y 0-100 cm. Las pérdidas de carbono identificadas fueron del 36 % para suelos Cambisoles de la llanura alta, 40 % para Feozem y Cambisoles de la llanura media, 60 % en suelos Feozem y Solonetz de las depresiones de la llanura media, 67 % para Cambisoles de la llanura baja y 90 % para Arenosoles de las barras costeras. Se demostró que la actividad agrícola intensiva y continuada, ha ocasionado pérdidas en el contenido de carbono; así mismo, la capa agrícola (20 cm) resulta la más afectada por esta actividad antropogénica

    Unmasking a new prognostic marker and therapeutic target from the GDNF-RET/PIT1/p14ARF/p53 pathway in acromegaly

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    Most of acromegaly is caused by a sporadic somatotropinoma and a couple of novel gene mutations responsible for somatotropinoma have recently been reported. To determine the cause of sporadic somatotropinoma in Japanese patients, we analyzed 61 consecutive Japanese patients with somatotropinoma without apparent family history. Comprehensive genetic analysis revealed that 31 patients harbored guanine nucleotide-binding protein, alpha stimulating (GNAS) mutations (50.8%) and three patients harbored aryl hydrocarbon receptor interacting protein (AIP) mutations (4.9%). No patients had G protein-coupled receptor 101 (GPR101) mutations. The patients in this cohort study were categorized into three groups of AIP, GNAS, and others and compared the clinical characteristics. The AIP group exhibited significantly younger age at diagnosis, larger tumor, and higher nadir GH during oral glucose tolerance test. In all patients with AIP mutation, macro- and invasive tumor was detected and repetitive surgery or postoperative medical therapy was needed. One case showed a refractory response to postoperative somatostatin analogue (SSA) but after the addition of cabergoline as combined therapy, serum IGF-I levels were controlled. The other case showed a modest response to SSA and the switching to cabergoline monotherapy was also effective. These data suggest that although resistance to SSA has been reported in patients with AIP mutations, the response to dopamine agonist (DA) may be retained. In conclusion, the cause of sporadic somatotropinoma in Japanese patients was comparable with the previous reports in Caucasians, patients with AIP mutations showed unique clinical characteristics, and DA may be a therapeutic option for patients with AIP mutations

    Actividad antioxidante de los alcaloides de Bocconia arborea. Estudio sobre seis métodos de análisis

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    Antioxidative activity-guided fractionation together with chemical analysis led to the isolation of three benzophenanthridinealkaloids from methanol extract of the bark of Bocconia arborea. Identification was based on spectroscopic methods.The isolated alkaloids 6-acetonyldihydrochelerythrine, chelerythrine and dihydrochelerythrine were tested for antioxidativeactivity on thiocyanate assays, free radical scavenging activity, b-carotene bleaching method, and deoxyribose assay. Allalkaloids exhibited significant antioxidant activities in linoleic acid and b-carotene. Although afforded protection againstthe damage of deoxyribose, liposome peroxidation and microsomial lipid from peroxidation, also exhibited scavengingeffects on the 1,1-diphenyl-2-picrylhydrazyl radicals.El fraccionamiento de la actividad antioxidante dirigida por actividad, junto con el análisis químico, llevaron alaislamiento de tres alcaloides de benzofenantridina del extracto de metanol de la corteza de Bocconia arborea. Laidentificación se basó en métodos espectroscópicos. Se analizó la actividad antioxidante de los alcaloides aislados 6-acetonildihidroqueleritrina, queleritrina y dihidroqueleritrina en ensayos de tiocianato, la actividad de barrido delos radicales libres, el método de decoloración del b-caroteno y el ensayo de la desoxirribosa. Todos los alcaloidesmostraron actividad antioxidante significativa en ácido linoleico y b-caroteno. Además de conceder protección frentea la desoxirribosa, la peroxidación liposómica y los lípidos microsomiales de la peroxidación, también presentaronefectos de barrido en los radicales de 1,1-difenil-2-picrilhidrazi
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