318 research outputs found

    Multipower variation for Brownian semistationary processes

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    In this paper we study the asymptotic behaviour of power and multipower variations of processes YY:Yt=ftytg(ts)σsW(ds)+Zt,Y_t=\int_{-\in fty}^tg(t-s)\sigma_sW(\mathrm{d}s)+Z_t, where g:(0,)Rg:(0,\infty)\rightarrow\mathbb{R} is deterministic, σ>0\sigma >0 is a random process, WW is the stochastic Wiener measure and ZZ is a stochastic process in the nature of a drift term. Processes of this type serve, in particular, to model data of velocity increments of a fluid in a turbulence regime with spot intermittency σ\sigma. The purpose of this paper is to determine the probabilistic limit behaviour of the (multi)power variations of YY as a basis for studying properties of the intermittency process σ\sigma. Notably the processes YY are in general not of the semimartingale kind and the established theory of multipower variation for semimartingales does not suffice for deriving the limit properties. As a key tool for the results, a general central limit theorem for triangular Gaussian schemes is formulated and proved. Examples and an application to the realised variance ratio are given.Comment: Published in at http://dx.doi.org/10.3150/10-BEJ316 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

    Riemannian barycentres and geodesic convexity

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    Abstract Consider a closed subset of a complete Riemannian manifold, such that all geodesics with end-points in the subset are contained in the subset and the subset has boundary of codimension one. Is it the case that Riemannian barycentres of probability measures supported by the subset must also lie in the subset? It is shown that this is the case for 2-manifolds but not the case in higher dimensions : a counterexample is constructed which is a conformally-Euclidean 3-manifold, for which geodesics never self-intersect and indeed cannot turn by too much (so small geodesic balls satisfy a geodesic convexity condition), but is such that a probability measure concentrated on a single point has a barycentre at another point

    A Systematic Review on the Effects of L-theanine and Caffeine Combination on Human Mood and Cognition

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    Caffeine is one of the most widely ingested psychoactive drugs in the world. However, this central nervous system stimulant has raised concerns because of its inauspicious effects on health that come with its overconsumption. Recent scientific advancements have allowed for the theoretical regulation of these side effects through the combination of caffeine and Ltheanine, an amino acid that promotes relaxation and improves mental function. This minireview aims to extend current knowledge by synthesizing both beneficial and detrimental effects of the administration of the combination of caffeine and L-theanine to the human brain and cognition. Information was extensively reviewed, analyzed, and compiled from a sample of 50 works of literature published from 2014 to 2020 in the DLSU Library Databases, as well as referenced studies excluded from the given timeframe that contain highly relevant information that help structuralize the review. Dosage was found to be important in attaining benefits on mood and cognition such as suppressed anxiety and stress, positive mental state, neurochemically fostered changes in neurotransmitter systems, improved accuracy, improved semantic and recognition memory, and heightened mental alertness. On the other hand, Ltheanine was found to reduce arousal more than it regulates elevated emotions caused by caffeine while some literature found that induced cognitive effects were only independent for each substance. In summary, existing studies support the hypothesis that the combination benefits human mood and cognition. As such, future research may gear towards a build-up on knowledge and innovations on the topic

    Plan de negocio para la comercializaci?n de una plataforma online de recaudaci?n de regalo bodas

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    La presente investigaci?n se inicia por la identificaci?n de la oportunidad de los nuevos h?bitos de los millenials que hoy en d?a son el grupo mayoritario que contrae matrimonio de acuerdo a estadisticas del INEI. As? mismo de acuerdo a fuente de OSIPTEL se comprueba que en lima metropolitana m?s de 5 millones son usuarios activos de smartphone y de acuerdo a los estudios cuantitativos se demuestra que este grupo en su mayor?a ya cuentan con la experiencia de compra por internet. El plan de neogcio se ha orientado en hacer un match entre esta experiencia digital con los nuevos h?bitos de las personas entre 25 a 34 a?os que contraen matrimonio y por ende nace la oportunidad de una plataforma digital Boda Clic que conllevar? a complementar una nueva experiencia de celebrar las bodas de los millenials en el Per? con alta probabilidad de expansi?n geogr?fica

    Inhibition of ATPase from chloroplasts by a hydroxamic acid from Gramineae.

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    Abstract-DIMBOA (2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one), a hydroxamic acid from the Gramineae involved in the resistance of cereals to aphids, inhibits energy transfer reactions. In this paper the effect of DIMBOA on the ATPase activity of chloroplast coupling factor 1 (CF,) was studied. A rapid inactivation of the enzyme was observed which increased with the concentration of DIMBOA. This inactivation was reversed by dilution and by filtration of the inhibitor. The inactivation was partially prevented by pre-treatment of the enzyme with iodoacetamide. A slower simultaneous inactivation was observed which followed pseudo-first order kinetics. It is suggested that part of the rapid inhibition of CF, ATPase caused by DIMBOA is due to its reaction with sulthydryl groups on the enzyme. These reactions of DIMBOA may explain some of the inhibitory properties of DIMBOA on a wide range of organisms

    New reference ranges for interpreting forced expiratory manoeuvres in infants and implications for clinical interpretation: a multicentre collaboration

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    The raised volume rapid thoracoabdominal compression (RVRTC) technique is commonly used to obtain full forced expiratory manoeuvres from infants, but reference equations derived from 'in-house' equipment have been shown to be inappropriate for current commercially available devices

    Interactions of Bacillus Mojavensis and Fusarium Verticillioides With a Benzoxazolinone (Boa) and Its Transformation Product, Apo

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    En:Journal of Chemical Ecology (2007, vol. 33, n. 10, p. 1885-1897)The benzoxazolinones, specifically benzoxazolin-2(3H)-one (BOA), are important transformation products of the benzoxazinones that can serve as allelochemicals providing resistance to maize from pathogenic bacteria, fungi, and insects. However, maize pathogens such as Fusarium verticillioides are capable of detoxifying the benzoxazolinones to 2-aminophenol (AP), which is converted to the less toxic N-(2-hydroxyphenyl) malonamic acid (HPMA) and 2-acetamidophenol (HPAA). As biocontrol strategies that utilize a species of endophytic bacterium, Bacillus mojavensis, are considered efficacious as a control of this Fusarium species, the in vitro transformation and effects of BOA on growth of this bacterium was examined relative to its interaction with strains of F. verticillioides. The results showed that a red pigment was produced and accumulated only on BOA-amended media when wild type and the progeny of genetic crosses of F. verticillioides are cultured in the presence of the bacterium. The pigment was identified as 2-amino-3H-phenoxazin-3-one (APO), which is a stable product. The results indicate that the bacterium interacts with the fungus preventing the usual transformation of AP to the nontoxic HPMA, resulting in the accumulation of higher amounts of APO than when the fungus is cultured alone. APO is highly toxic to F. verticillioides and other organisms. Thus, an enhanced biocontrol is suggested by this in vitro study. =580 $aEn:Journal of Chemical Ecolog

    Brain functional abnormality in schizo-affective disorder: an fMRI study.

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    Background.Schizo-affective disorder has not been studied to any significant extent using functional imaging. The aim of this study was to examine patterns of brain activation and deactivation in patients meeting strict diagnostic criteria for the disorder. METHOD: Thirty-two patients meeting research diagnostic criteria (RDC) for schizo-affective disorder (16 schizomanic and 16 schizodepressive) and 32 matched healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups. RESULTS: Controls showed activation in a network of frontal and other areas and also deactivation in the medial frontal cortex, the precuneus and the parietal cortex. Schizo-affective patients activated significantly less in prefrontal, parietal and temporal regions than the controls, and also showed failure of deactivation in the medial frontal cortex. When task performance was controlled for, the reduced activation in the dorsolateral prefrontal cortex (DLPFC) and the failure of deactivation of the medial frontal cortex remained significant. CONCLUSIONS: Schizo-affective disorder shows a similar pattern of reduced frontal activation to schizophrenia. The disorder is also characterized by failure of deactivation suggestive of default mode network dysfunction
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