244 research outputs found
Day-to-day variation of salivary cortisol and dehydroepiandrosterone (DHEA) in children from a rural Dominican community
This study examines day-to-day patterns of salivary cortisol and dehydroepiandrosterone (DHEA) under baseline conditions and in response to mild stress among 59 children residing in a rural Caribbean village. Cortisol secretion showed the typical circadian variation with high levels in the morning. Children showed significant increases of cortisol before and during a videotaped interview when compared to routine days. DHEA levels were positively associated with cortisol levels; however, within-day secretion of salivary DHEA was more stable than cortisol and DHEA levels did not change significantly during the day. Average DHEA concentrations were positively associated with age but did not show the sharp increase that is usually observed at the onset of adrenarche. These results highlight both similarities and differences in the secretion of cortisol and DHEA during childhood among rural and industrialized human populations
Social network centrality and hormones: The interaction of testosterone and cortisol
In this study we tested whether testosterone and cortisol interacted in predicting social network centrality within a male rugby team. Using social network analysis (SNA), three measures of centrality were investigated: popularity (i.e., the number of incoming ties a participant receives), gregariousness (i.e., the number of ties leaving from a participant and reaching out to others), and betweenness (i.e., the number of times a person lies between two other individuals). In line with the idea that testosterone and cortisol jointly regulate the emergence of social status, we found that individuals with high basal testosterone and low basal cortisol were more popular and more likely to act as connectors among other individuals (i.e., betweenness). The same hormonal profile was not predictive of gregariousness. However, in line with the small literature on the topic, we found that cortisol was inversely correlated with gregariousness. Despite the cross-sectional and correlational nature of our research design, these findings represent the first empirical evidence that testosterone and cortisol interact to predict complex measures of social hierarchy position derived from social network analyses
Levy distribution and long correlation times in supermarket sales
Sales data in a commodity market (supermarket sales to consumers) has been
analysed by studying the fluctuation spectrum and noise correlations. Three
related products (ketchup, mayonnaise and curry sauce) have been analysed. Most
noise in sales is caused by promotions, but here we focus on the fluctuations
in baseline sales. These characterise the dynamics of the market. Four hitherto
unnoticed effects have been found that are difficult to explain from simple
econometric models. These effects are: (1) the noise level in baseline sales is
much higher than can be expected for uncorrelated sales events; (2) weekly
baseline sales differences are distributed according to a broad non-Gaussian
function with fat tails; (3) these fluctuations follow a Levy distribution of
exponent alpha = 1.4, similar to financial exchange markets and in stock
markets; and (4) this noise is correlated over a period of 10 to 11 weeks, or
shows an apparent power law spectrum. The similarity to stock markets suggests
that models developed to describe these markets may be applied to describe the
collective behaviour of consumers.Comment: 19 pages, 7 figures, accepted for publication in Physica
The hyperornithinemia-hyperammonemia-homocitrullinuria syndrome
Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare autosomal recessive disorder of the urea cycle. HHH has a panethnic distribution, with a major prevalence in Canada, Italy and Japan. Acute clinical signs include intermittent episodes of vomiting, confusion or coma and hepatitis-like attacks. Alternatively, patients show a chronic course with aversion for protein rich foods, developmental delay/intellectual disability, myoclonic seizures, ataxia and pyramidal dysfunction. HHH syndrome is caused by impaired ornithine transport across the inner mitochondrial membrane due to mutations in SLC25A15 gene, which encodes for the mitochondrial ornithine carrier ORC1. The diagnosis relies on clinical signs and the peculiar metabolic triad of hyperammonemia, hyperornithinemia, and urinary excretion of homocitrulline. HHH syndrome enters in the differential diagnosis with other inherited or acquired conditions presenting with hyperammonemia
Consumers don't play dice, influence of social networks and advertisements
Empirical data of supermarket sales show stylised facts that are similar to
stock markets, with a broad (truncated) Levy distribution of weekly sales
differences in the baseline sales [R.D. Groot, Physica A 353 (2005) 501]. To
investigate the cause of this, the influence of social interactions and
advertisements are studied in an agent-based model of consumers in a social
network. The influence of network topology was varied by using a small-world
network, a random network and a Barabasi-Albert network. The degree to which
consumers value the opinion of their peers was also varied. On a small-world
and random network we find a phase-transition between an open market and a
locked-in market that is similar to condensation in liquids. At the critical
point, fluctuations become large and buying behaviour is strongly correlated.
However, on the small world network the noise distribution at the critical
point is Gaussian, and critical slowing down occurs which is not observed in
supermarket sales. On a scale-free network, the model shows a transition
between a gas-like phase and a glassy state, but at the transition point the
noise amplitude is much larger than what is seen in supermarket sales. To
explore the role of advertisements, a model is studied where imprints are
placed on the minds of consumers that ripen when a decision for a product is
made. The correct distribution of weekly sales returns follows naturally from
this model, as well as the noise amplitude, the correlation time and
cross-correlation of sales fluctuations. For particular parameter values,
simulated sales correlation shows power law decay in time. The model predicts
that social interaction helps to prevent aversion, and that products are viewed
more positively when their consumption rate is higher.Comment: Accepted for publication in Physica
Cortisol, Temperament and Serotonin in Karate Combats: An Evolutionary Psychobiological Perspective
Objectives: There is evidence suggesting that in martial arts competitions athletes characterized by higher anxiety and harm avoidance may be more likely to lose a fight. This psychological profile has been hypothesized to explain in part the observation that cortisol is higher in losers before and in response to a competition. An important research target that needs further exploration is the identification of phenotypic traits that can be helpful in predicting athletes’ performance. Here we present a brief description of the theoretical bases that drives our research in the evolutionary psychobiology of sports and illustrate preliminary data on the relationship between the 5HTTLPR genotype, salivary cortisol, temperament and competition. Methods: Sixty-five healthy male non-professional athletes provided saliva samples 10 min before and after a kumite session and filled out the Tridimensional Personality Questionnaire. Results: Salivary cortisol levels 10 min before the competition were higher in losers and in athletes with the S allele. Temperament was associated with competition outcome and cortisol: losers were characterized by higher scores of harm avoidance and harm avoidance was positively correlated with cortisol levels. Conclusions: The results confirm previous findings linking temperamental traits, pre-and post- competition physiological stress response with competition outcome in kumite fight. Moreover, they indicate an association between the 5HTTLPR polymorphism and pre-competition salivary cortisol, thus providing a preliminary but non-conclusive evidence on the role played by the 5HTTLPR genotype as a vulnerability factor in sport competition
Studies of the limit order book around large price changes
We study the dynamics of the limit order book of liquid stocks after
experiencing large intra-day price changes. In the data we find large
variations in several microscopical measures, e.g., the volatility the bid-ask
spread, the bid-ask imbalance, the number of queuing limit orders, the activity
(number and volume) of limit orders placed and canceled, etc. The relaxation of
the quantities is generally very slow that can be described by a power law of
exponent . We introduce a numerical model in order to understand
the empirical results better. We find that with a zero intelligence deposition
model of the order flow the empirical results can be reproduced qualitatively.
This suggests that the slow relaxations might not be results of agents'
strategic behaviour. Studying the difference between the exponents found
empirically and numerically helps us to better identify the role of strategic
behaviour in the phenomena.Comment: 19 pages, 7 figure
Tick size and price diffusion
A tick size is the smallest increment of a security price. It is clear that
at the shortest time scale on which individual orders are placed the tick size
has a major role which affects where limit orders can be placed, the bid-ask
spread, etc. This is the realm of market microstructure and there is a vast
literature on the role of tick size on market microstructure. However, tick
size can also affect price properties at longer time scales, and relatively
less is known about the effect of tick size on the statistical properties of
prices. The present paper is divided in two parts. In the first we review the
effect of tick size change on the market microstructure and the diffusion
properties of prices. The second part presents original results obtained by
investigating the tick size changes occurring at the New York Stock Exchange
(NYSE). We show that tick size change has three effects on price diffusion.
First, as already shown in the literature, tick size affects price return
distribution at an aggregate time scale. Second, reducing the tick size
typically leads to an increase of volatility clustering. We give a possible
mechanistic explanation for this effect, but clearly more investigation is
needed to understand the origin of this relation. Third, we explicitly show
that the ability of the subordination hypothesis in explaining fat tails of
returns and volatility clustering is strongly dependent on tick size. While for
large tick sizes the subordination hypothesis has significant explanatory
power, for small tick sizes we show that subordination is not the main driver
of these two important stylized facts of financial market.Comment: To be published in the "Proceedings of Econophys-Kolkata V
International Workshop on "Econophysics of Order-driven Markets" March 9-13,
2010, The New Economic Windows series of Springer-Verlag Italia
syk inhibitors interfere with erythrocyte membrane modification during p falciparum growth and suppress parasite egress
Key Points
Inhibitors of human Syk kinase suppress parasite egress. Syk inhibitors prevent the tyrosine phosphorylation of band 3 in P falciparum parasitized red blood cells, reducing the release of microparticles
Klassische Moderne. Un paradigma del Novecento
Il libro, che pubblica gli atti del convegno internazionale, svoltosi a Roma nel maggio del 2007 nell’ambito della ricerca PRIN-2005 (Università di Roma La Sapienza, Trento, Bari e Urbino), analizza il periodo della cultura tedesca della fine-secolo con particolare attenzione ai personaggi e ai movimenti che si sono collocati negli “spazi intermedi”, intesi non solo e non tanto come zone di confine in senso territoriale, quanto piuttosto come zone di interscambio culturale e disciplinare, come tentativi di “superamento” degli ordini mentali e culturali costituiti. L’ambito cronologico che il gruppo di ricerca prende in esame va da 1888 al 1933. La periodizzazione proposta vuole rinviare a quella serie di movimenti e di pensatori che hanno dato il via alla messa in discussione di quei valori costituiti, dalla cui frammentazione è nata la cultura del “secolo breve”.
In questo periodo, a partire dalla Jahrhundertwende, sono state elaborate e sperimentate nella prassi letteraria e artistica, una serie di teorie, una serie di “visioni del mondo” che implicavano tanto una pratica produttiva quanto un ruolo dell’artista e dell’arte quanto una visione più generale dei cambiamenti epocali e dell’epoca moderna. Tali teorie e pratiche artistiche, di vario genere e di vario livello, costituiscono un patrimonio concettuale perché in esse si trovano sperimentate e a volte anticipate molte questioni che oggi sono di estrema attualità: dal rapporto uomo-macchina al rapporto parola-immagine, dalla definizione degli spazi urbani alla questione della guerra, dalla ricerca della identità monoculturale alla presa d’atto dell’esistenza dell’estraneo. Queste varie problematiche sono state espresse in termini linguistici nuovi giacché gli autori si sono posti – teoricamente e praticamente – il problema del linguaggio artistico e ne hanno modificato (a volte radicalmente) i codici espressivi.
Il libro di divide in tre parti: I: Per una definizione della Klassische Moderne che presenta l’ampia e animata discussione sulla stessa definizione teorica del movimento artistico-culturale, sia sui termini cronologici di questa nuova periodizzazione. Questa parte raccoglie i contributi di Aldo Venturelli, Helmut Kiesel e Fabrizio Cambi. II: La rivoluzione delle forme, che analizza la produzione delle avanguardie (sia pure definite “marginali” ) e prende in considerazione anche aspetti della produzione musicale, nonché forme di narratologia e nuove forme di scrittura. Questa seconda parte pubblica i saggi di Mauro Ponzi, Rosmarie Keller, Silvio Vietta, Hans Dieter Zimmermann, Elio Matassi e Sabine Meine. III: La fucina dei nuovi linguaggi che analizza l’innovazione dei linguaggi artistici sull’esempio di autori meno radicali che quelli delle avanguardie storiche. Questi autori, tipici esponenti della Klassische Moderne, hanno cercato di coniugare l’innovazione dei linguaggi con il recupero di alcuni aspetti della tradizione. Nella terza parte del volume vengono pubblicati i saggi di Alain Montandon, Giovanni Tateo, Gouseppe Farese, Gabriella Rovagnati, Sabine Schneider e Alessandro Fambrini
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