1,190 research outputs found
On a class of time-Fractional continuous-State branching processes
We propose a class of non-Markov population models with continuous or discrete state space via a limiting procedure involving sequences of rescaled and randomly time-changed Galton – Watson processes. The class includes as specific cases the classical continuous-state branching processes and Markov branching processes. Several results such as the expressions of moments and the branching inequality governing the evolution of the process are presented and commented. The generalized Feller branching diffusion and the fractional Yule process are analyzed in detail as special cases of the general model
Analysis of Metal Cutting Acoustic Emissions by Time Series Models
We analyse some acoustic emission time series obtained from a lathe machining
process. Considering the dynamic evolution of the process we apply two classes
of well known stationary stochastic time series models. We apply a preliminary
root mean square (RMS) transformation followed by an ARMA analysis; results
thereof are mainly related to the description of the continuous part (plastic
deformation) of the signal. An analysis of acoustic emission, as some previous
works show, may also be performed with the scope of understanding the evolution
of the ageing process that causes the degradation of the working tools. Once
the importance of the discrete part of the acoustic emission signals (i.e.
isolated amplitude bursts) in the ageing process is understood, we apply a
stochastic analysis based on point processes waiting times between bursts and
to identify a parameter with which to characterise the wear level of the
working tool. A Weibull distribution seems to adequately describe the waiting
times distribution
Modulation of microRNA editing, expression and processing by ADAR2 deaminase in glioblastoma.
Background: ADAR enzymes convert adenosines to inosines within double-stranded RNAs, including microRNA
(miRNA) precursors, with important consequences on miRNA retargeting and expression. ADAR2 activity is impaired
in glioblastoma and its rescue has anti-tumoral effects. However, how ADAR2 activity may impact the miRNome
and the progression of glioblastoma is not known.
Results: By integrating deep-sequencing and array approaches with bioinformatics analyses and molecular studies,
we show that ADAR2 is essential to edit a small number of mature miRNAs and to significantly modulate the
expression of about 90 miRNAs in glioblastoma cells. Specifically, the rescue of ADAR2 activity in cancer cells recovers
the edited miRNA population lost in glioblastoma cell lines and tissues, and rebalances expression of onco-miRNAs and
tumor suppressor miRNAs to the levels observed in normal human brain. We report that the major effect of ADAR2 is
to reduce the expression of a large number of miRNAs, most of which act as onco-miRNAs. ADAR2 can edit miR-222/221
and miR-21 precursors and decrease the expression of the corresponding mature onco-miRNAs in vivo and in vitro, with
important effects on cell proliferation and migration.
Conclusions: Our findings disclose an additional layer of complexity in miRNome regulation and provide information
to better understand the impact of ADAR2 editing enzyme in glioblastoma. We propose that ADAR2 is a key factor for
maintaining edited-miRNA population and balancing the expression of several essential miRNAs involved in cancer
Glyco-gold nanoparticles: Synthesis and applications
Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design
A New Derivation of the CPT and Spin-Statistics Theorems in Non-Commutative Field Theories
We propose an alternative axiomatic description for non-commutative field
theories (NCFT) based on some ideas by Soloviev to nonlocal quantum fields. The
local commutativity axiom is replaced by the weaker condition that the fields
commute at sufficiently large spatial separations, called asymptotic
commutativity, formulated in terms of the theory of analytic functionals. The
question of a possible violation of the CPT and Spin-Statistics theorems caused
by nonlocality of the commutation relations
is investigated. In spite of this
inherent nonlocality, we show that the modification aforementioned is
sufficient to ensure the validity of these theorems for NCFT. We restrict
ourselves to the simplest model of a scalar field in the case of only
space-space non-commutativity.Comment: The title is new, and the analysis in the manuscript has been made
more precise. This revised version is to be published in J.Math.Phy
The indigenous settlement of Monte Iato (western Sicily): an ethnoarchaeometric approach for outlining local Archaic ceramic productions
An ethnoarchaeometric approach has been followed to identify the textural and compositional characteristics of the ceramic pastes produced in ancient Iaitas/Ietas, an indigenous site located in western Sicily on Monte Iato, a few tens of kilometres from Palermo. This approach was primarily motivated by the lack of discovered Archaic kilns or production sites/workshops and the inability to identify reference groups. Raw clays were sampled in the territory of San Cipirello and San Giuseppe Iato (today\u2019s municipalities both sited on the northern slopes of Monte Iato), together with representative historic tiles and bricks locally produced until fairly recently. Grain-size analysis and experimental firings were performed on the clay samples. A significant number of archaeological ceramic samples (incised and painted indigenous pottery dating back to the seventh\u2013fifth centuries BCE) from stratigraphic excavations on Monte Iato, and hypothesized as local productions on a stylistic-morphological basis, was carefully selected for archaeometric analysis. This set of samples (90 in total, comprising raw clays, historic tiles/bricks and archaeological ceramics) underwent a combined chemical and mineralogical-petrographic analysis to identify any possible compositional matching. This approach enabled the identification of minero-petrographic and chemical markers pertinent to the indigenous Archaic pottery produced at Monte Iato, although no evidence of coeval ceramic kilns has been found so far. Local raw clay sources have been documented and some significant points of the cha\ueene op\ue9ratoire adopted in antiquity have been noted (clay mixing and tempering practices). Attesting Monte Iato as a centre of ceramic production and defining both the microscopic fabric and the average composition of local pastes open up new perspectives in the complex issue concerning the production and regional circulation of incised and painted indigenous ceramics in Archaic Sicily
Effects of zinc supplementation on cognitive function in healthy middle-aged and older adults: the ZENITH study
A randomised double-blind placebo-controlled design was employed to investigate the effects of Zn supplementation on cognitive function in 387 healthy adults aged 55–87 years. Several measures of visual memory, working memory, attention and reaction time were obtained using the Cambridge Automated Neuropsychological Test Battery at baseline and then after 3 and 6 months of 0 (placebo), 15 or 30 mg Zn/d. Younger adults (70 years), and performance improved with practice on some measures. For two out of eight dependent variables, there were significant interactions indicating a beneficial effect (at 3 months only) of both 15 and 30 mg/d on one measure of spatial working memory and a detrimental effect of 15 mg/d on one measure of attention. Further work is required to establish whether these findings generalise to older adults in poorer mental and physical health and with less adequate Zn intake and status than the present sample
Effects of mixed of a ketogenic diet in overweight and obese women with polycystic ovary syndrome
Polycystic ovary syndrome (PCOS) is a commonly occurring endocrine disorder characterized by hirsutism, anovulation, and polycystic ovaries. Often comorbid with insulin resistance, dyslipidemia, and obesity, it also carries significant risk for the development of cardiovascular and metabolic sequelae, including diabetes and metabolic syndrome. The relationship between central obesity and the development of insulin resistance is widely verified. Adipose tissue excess and the coexistent dysregulation of adipocyte functions directly contribute to the pathogenesis of the metabolic complications observed in women with PCOS. In the light of these evidence, the most therapeutic option prescribed to obese women with PCOS, regardless of the phenotype e from the severity of clinical expression, is lifestyle correction by diet and physical activity. The aim of this study is to evaluate the beneficial effects of ketogenic diet in 17 obese women with PCOS. Our results showed that the ketogenic diet inducing therapeutic ketosis, improves the anthropometric and many biochemical parameters such as LH, FSH, SHBG, insulin sensitivity and HOMA index. In addition, it induces a reduction in androgenic production, whereas the contextual reduction of fat mass reduced the acyclic production of estrogens deriving from the aromatization in the adipose tissue of the androgenic excess, with an improvement of the LH/FSH ratio. This is the first study on the effects of the ketogenic diet on PCOS, however, further studies are needed to elucidate the mechanism underlying ketogenic diet effects
Speciation in Western North America: Lomatium as an Example of Diversification and Convergent Evolution
Species delimitations and understanding the processes that drive speciation are essential to nearly all aspects of human endeavor. Determining species boundaries traditionally used morphology. Phylogenetic analyses based on DNA sequence data provide a means to resolve species boundaries, as well as test hypotheses regarding the evolutionary processes. Numerous species radiations have occurred in Western North America. Among these are several plant groups such as Astragalus, Artemisia, and Lomatium. Recent phylogenetic analyses of Lomatium and related genera have demonstrated that many of the morphological characters used to delimit taxa have arisen multiple times and that most taxa are para- or polyphyletic. Here we examine one of the clades recovered in the Lomatium group of taxa that includes Lomatium triternatum and L. grayi. The several subspecific taxa of L. triternatum have not been recovered as monophyletic and L. grayi has a widespread habitat distribution that may indicate cryptic speciation. Previous analyses have not fully resolved phylogenetic relationships with strong support. In the present study we sample an additional four loci (three chloroplast and one nuclear ribosomal) to improve the support for evolutionary relationships across this clade, resolve species boundaries, and test hypotheses on the evolution of morphological traits
Relação entre o sistema renina angiotensina e as respostas cardiovasculares promovidas pelo exercício físico
Introduction and Objective: The renin angiotensin system (RAS) has an important function in the homeostasis of cardiovascular system, and the activation of the classical pathway results in the formation of angiotensin II which lead to increased blood pressure (BP). Whereas exercice interferes in cardiovascular responses to angiotensin II and consequently reduces the BP. Whereas exercice interferes in cardiovascular responses, this study aimed to review the literature regarding the possible relationship of physical training with the RAS.Methods: The work was divided into sessions of studies involving animals and studies involving humans. Searches were performed in Medline database, and the main criteria were samples with animals ou humans and articles published in English. After applied the inclusion and exclusion criteria, we selected 12 articles involving animals and 8 involving humans.Results: The studies involving animals and humans have shown that there is a relationship between physical training and RAS, and cardiovascular responses observed after exercice may have some relationship with the RAS. Furthermore, studies in humans have shown that polymorphisms in some genes of the RAS may also be crucial to the cardiovascular responses found after exercice. Conclusion: Given the recent research linking cardiovascular responses after exercice with the SRA, this relationship seems to be important to consider the mechanism responsible for promoting certain cardiovascular responses after exercise, such as hypotension.Introdução e objetivos: O sistema renina angiotensina (SRA) apresenta importante função na homeostase do sistema cardiovascular, e a ativação da via clássica resulta na formação de angiotensina II, que leva ao aumento da pressão arterial (PA). No entanto, novos estudos tem evidenciado a ativação da via da angiotensina (1-7), a qual apresenta respostas contrárias a Angiotensina II e consequentemente reduz a PA. Considerando que o exercício físico interfere nas repostas cardiovasculares, este estudo teve o propósito de revisar a literatura quanto a possível relação do treinamento físico com o SRA.Métodos: o trabalho foi dividido em sessões de estudos que envolveram animais e estudos com seres humanos. A busca destes estudos foi realizada na base Medline e os principais critérios foram amostras com animais ou seres humanos e artigos publicados em inglês. Depois de aplicados os critérios de inclusão e exclusão, foram encontrados 12 artigos envolvendo animais e oito envolvendo seres humanos.Resultados: Os estudos demonstraram que existe uma relação entre o treinamento físico e o SRA, sendo que as respostas cardiovasculares observadas após o exercício físico pode apresentar alguma relação com o SRA. Além disso, estudos com seres humanos demonstraram que polimorfismos em alguns genes do SRA podem ser determinantes para as respostas cardiovasculares encontradas após o exercício físico. Considerações finais: Tendo em vista as recentes investigações que relacionam as respostas cardiovasculares após o exercício físico com o SRA, esta relaçação parece ser importante ao considerar os mecanismos responsáveis por promover determinadas respostas cardiovasculares após o exercício físico como a hipotensão.
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