1,721,020 research outputs found
AN EXTENDED KALMAN FILTER BASED TECHNIQUE FOR ON-LINE IDENTIFICATION OF UAS PARAMETERS.
No full textThe present article deals with the identification,at the same time, of aircraft stability and control parameters taking into account dynamic damping derivatives.
Such derivatives,due to the rate of change of the angle of attack, are usually neglected. So the damping characteristics of aircraft dynamics are attributed only on pitch rate derivatives.
To cope with the dynamic effects of these derivatives, authors developed devoted procedures to estimate them. In the present paper, a complete model of aerodynamic coefficients has been tuned-up to identify simultaneously the whole set of derivatives. Besides, in spite of the employed reduced order model and/or decoupled dynamics, a six degrees of freedom model has been
postulated without decoupling longitudinal and lateral dynamics.
A recursive non-linear filtering approach via Extended Kalman Filter is proposed, and the filter tuning is performed by inserting the effects of dynamic derivatives into the mentioned mathematical model of the studiedaircraft.
The tuned-up procedure allows determining with noticeable precision the stability and control derivatives. In fact, either by activating maneuvers generated by all the control surfaces or by inserting noticeable measurement noise, the identified derivatives show very small values of standard deviation. The present study shows the possibility to identify simultaneously the aircraft derivatives without using devoted procedures and decoupled dynamics. The proposed technique is particularly suited for on-line parametrical identification of Unmanned Aerial Systems. In fact, to estimate both state and aircraft parameters, low power and time are required even using measurement noises typical of low-cost sensors
ANALISI STRUTTURALE E FUNZIONALE DELLA PROTEINA ERp57: CARATTERIZZAZIONE DEI COMPLESSI NUCLEARI MACROMOLECOLARI IN CUI E' COINVOLTA
No full textMaurizio Paci, Giovanni Antonini, Nazareno Capitani
The DNA-binding activity of protein disulfide isomerase ERp57 is associated with the a’ domain
No full textERp57 belongs to the protein disulfide isomerases, a family of homologous proteins mainly localized in the endoplasmic reticulum and characterized by the presence of a thioredoxin-like folding domain. ERp57 is a protein chaperone with thiol-dependent protein disulfide isomerase and additional activities and recently it has been shown to be involved, in cooperation with calnexin or with calreticulin, in the correct folding of glycoproteins. However, we have demonstrated that the same protein is also present in the nucleus, mainly associated with the internal nuclear matrix fraction. In vitro studies have shown that ERp57 has DNA-binding properties which are strongly dependent on its redox state, the oxidized form being the competent one. A comparison study on a recombinant form of ERp57 and several deletion mutants, obtained as fusion proteins and expressed in Escherichia coli, allowed us to identify the C-terminal a(') domain as directly involved in the DNA-binding activity of ERp57
Green tea catechins can bind and modify ERp57/PDIA3 activity.
No full textBackground
Green tea is a rich source of polyphenols, mainly catechins (flavanols), which significantly contribute to the beneficial health effects of green tea in the prevention and treatment of various diseases. In this study the effects of four green tea catechins on protein ERp57, also known as protein disulfide isomerase isoform A3 (PDIA3), have been investigated in an in vitro model.
Methods
The interaction of catechins with ERp57 was explored by fluorescence quenching and surface plasmon resonance techniques and their effect on ERp57 activities was investigated.
Results
A higher affinity was observed for galloylated cathechins, which bind close to the thioredoxin-like redox-sensitive active sites of the protein, with a preference for the oxidized form. The effects of these catechins on ERp57 properties were also investigated and a moderate inhibition of the reductase activity of ERp57 was observed as well as a strong inhibition of ERp57 DNA binding activity.
Conclusions
Considering the high affinity of galloylated catechins for ERp57 and their capability to inhibit ERp57 binding to other macromolecular ligands, some effects of catechins interaction with this protein on eukaryotic cells may be expected.
General significance
This study provides information to better understand the molecular mechanisms underlying the biological activities of catechins and to design new polyphenol-based ERp57-specific inhibitors
DNA damage and repair: from molecular mechanisms to health implications
No full textDNA is subjected to several modifications, resulting from endogenous and exogenous sources. The cell has developed a network of complementary DNA-repair mechanisms, and in the human genome, >130 genes have been found to be involved. Knowledge about the basic mechanisms for DNA repair has revealed an unexpected complexity, with overlapping specificity within the same pathway, as well as extensive functional interactions between proteins involved in repair pathways. Unrepaired or improperly repaired DNA lesions have serious potential consequences for the cell, leading to genomic instability and deregulation of cellular functions. A number of disorders or syndromes, including several cancer predispositions and accelerated aging, are linked to an inherited defect in one of the DNA-repair pathways. Genomic instability, a characteristic of most human malignancies, can also arise from acquired defects in DNA repair, and the specific pathway affected is predictive of types of mutations, tumor drug sensitivity, and treatment outcome. Although DNA repair has received little attention as a determinant of drug sensitivity, emerging knowledge of mutations and polymorphisms in key human DNA-repair genes may provide a rational basis for improved strategies for therapeutic interventions on a number of tumors and degenerative disorders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Androgen-Escape": the role of STAT3
No full textThe pathophysiological process ‘‘Androgen Escape’’ is a clinical phase in which the tumoral prostatic cells obtain the ability to survive and proliferate without the required signals delivered normally by circulating androgens. Androgen insensitivity reflects the ability to grow without (or with very low) circulating androgens, but it should not be confused with an absence of the intracellular signaling activated downstream of androgen binding to AR. This event occurs when the tumoral prostatic cell can over activates the androgenic pathway by several mechanisms. A convergence point of some of these pathways is the protein STAT3 (Signal Transducer and Activator of Transcription). The phosphorylation of STAT-3 of tyrosine 705 in the cytoplasm, by IL-6 and EGF, leads to its dimerization, translocation into the nucleus, DNA binding, and then, expression of genes that regulate cell proliferation, differentiation, and apoptosis. In prostate cancer (CaP) AR and STAT3 pathway are constitutively activated; they coexist in the hormone-responsive tumor and crosstalk in androgen-refractory tumor. The aim of our study was to investigate the role of STAT3 and its post-translational modifications (PTMs), like phosphorilation, acetilation, glutathionylation, responsible of a functional variability of the protein as transcription factor. To evaluate STAT3 activation and its PTMs we performed Western Blotting analysis on two human prostate cancer cell lines LNCaP, androgen-sensitive, and PC3, androgen-refractory, untreated and stimulated with IL-6 (25 ng/ml), EGF (100 ng/ml) and H2O2 (100 mM). The results showed differences between the profiles of PTMs in the two cell lines and in the different conditions. After, we examined by RT2-PCR, the expression levels of STAT3 target genes, under the same conditions: the data obtained showed a relation between PTMs of STAT3 and P21 – Signal transduction Abstracts FEBS Journal 278 (Suppl. 1) 74–445 (2011) a 2011 The Authors Journal compilation a 2011 Federation of European Biochemical Societies 35
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