376 research outputs found
Perceptual Oscillations in Gender Classification of Faces, Contingent on Stimulus History
Perception is a proactive ââpredictiveââ process, in which the brain takes advantage of past experience to make informed guesses about the world to test against sensory data. Here we demonstrate that in the judgment of the gender of faces, beta rhythms play an important role in communicating perceptual experience. Observers classified in forced choice as male or female, a sequence of face stimuli, which were physically constructed to be male or female or androgynous (equal morph). Classification of the androgynous stimuli oscillated rhythmically between male and female, following a complex waveform comprising 13.5 and 17 Hz. Parsing the trials based on the preceding stimulus showed that responses to androgynous stimuli preceded by male stimuli oscillated reliably at 17 Hz, whereas those preceded by female stimuli oscillated at 13.5 Hz. These results suggest that perceptual priors for face perception from recent perceptual memory are communicated through frequency-coded beta rhythms
The role of individual and social variables in task performance.
This paper reports on a data-based study in which we explored - as part of a larger-scale British-Hungarian research project - the effects of a number of affective and social variables on foreign language (L2) learnersâ engagement in oral argumentative tasks. The assumption underlying the investigation was that studentsâ verbal behaviour in oral task situations is partly determined by a number of non-linguistic and non-cognitive factors whose examination may constitute a potentially fruitful extension of existing task-based research paradigms. The independent variables in the study included various aspects of L2 motivation and several factors characterizing the learner groups the participating students were members of (such as group cohesiveness and intermember relations), as well as the learnersâ L2 proficiency and âwillingness to communicateâ in their L1. The dependent variables involved objective measures of the studentsâ language output in two oral argumentative tasks (one in the learnersâ L1, the other in their L2): the quantity of speech and the number of turns produced by the speakers. The results provide insights into the interrelationship of the multiple variables determining the learnersâ task engagement, and suggest a multi-level construct whereby some independent variables only come into force when certain conditions have been met
Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium
The electrooxidation of Gamma Hydroxybutyric Acid (GHB) on a polycrystalline platinum electrode is studied by cyclic voltammetry in acidic medium. Two oxidation peaks, A and B, are obtained in the positive scan within the potential range of the double layer region and of the platinum oxide region, respectively. In the negative going potential sweep an inverted oxidation peak with an onset partially overlapping with the tail of the cathodic peak for the reduction of the platinum oxide formed during the anodic scan is obtained (peak C). This inverted peak can be observed at a potential close to +0.2 V (vs Ag/AgCl at pH 2) and separated 0.4 and 0.8 V from the two other oxidation peaks obtained during the anodic scan and in such conditions that the surface is particularly activated to favour this electrochemical process. The response obtained in the electronic current for the different peaks when GHB concentration and scan rate were changed to allows inferring that these are the result of a potential dependent mechanism. The behaviour observed is according with the oxidation of the alcohol group to the corresponding aldehyde and carboxylic acid (succinic acid) as main products
Personality, conventional Christian belief and unconventional paranormal belief : a study among teenagers
A sample of 10,851 pupils (5493 males and 5358 females) attending Year 9 classes (13- to 14-year-olds) and a sample of 9494 pupils (4787 males and 4707 females) attending Year 10 classes (14- to 15-year-olds) in non-denominational state-maintained secondary schools in England and Wales completed questions concerned with conventional Christian belief and unconventional paranormal belief, alongside the short-form Junior Eysenck Personality Questionnaire. The data demonstrated that conventional Christian belief and unconventional paranormal belief occupy different locations in relation to the Eysenckian model of personality in respect of the psychoticism scale and the lie scale. While conventional Christian belief is associated with lower psychoticism scores and higher lie scale scores (greater social conformity), unconventional paranormal belief is associated with higher psychoticism scores and lower lie scale scores (lower social conformity)
Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species
Characterising interspecific interaction strengths, combined with population abundances of prey and their novel predators, is critical to develop predictive invasion ecology. This is especially true of aquatic invasive species, which can pose a significant threat to the structure and stability of the ecosystems to which they are introduced. Here, we investigated consumer-resource dynamics of two globally-established aquatic invasive species, European green crab (Carcinus maenas) and brown trout (Salmo trutta). We explored the mediating effect of prey density on predatory impact in these invaders relative to functionally analogous native rock crab (Cancer irroratus) and Atlantic salmon (Salmo salar), respectively, feeding on shared prey (Mytilus sp. and Tenebrio molitor, respectively). We subsequently combined feeding rates with each predator's regional abundance to forecast relative ecological impacts. All predators demonstrated potentially destabilising Type II functional responses towards prey, with native rock crab and invasive brown trout exhibiting greater per capita impacts relative to their trophic analogues. Functional Response Ratios (attack rates divided by handling times) were higher for both invasive species, reflecting greater overall per capita effects compared to natives. Impact projections that incorporated predator abundances with per capita effects predicted severe impacts by European green crabs. However, brown trout, despite possessing higher per capita effects than Atlantic salmon, are projected to have low impact owing to currently low abundances in the sampled watershed. Should brown trout density increase sixfold, we predict it would exert higher impact than Atlantic salmon. Such impact-forecasting metrics and methods are thus vital tools to assist in the determination of current and future adverse impacts associated with aquatic invasive species
Caracterização e ocorrĂȘncia do distĂșrbio do amolecimento precoce em mamĂ”es 'Golden'
The occurrence of green skin and soft pulp in 'Golden' papaya fruit during certain seasons has been reported by farmers in the northern of the state of Espirito Santo, Brazil. The objective of this study was to characterize and determine the occurrence of this disorder, which was referred as "early softening disorder". Fruits were harvested weekly for 11 months (from September to July). The fruits were stored at 10°C, and then fruit flesh firmness and skin color were analyzed. The results of the firmness test were submitted to regression analysis assuming a linear trendline. The slope of the curve was called the 'softening index' (SI). Fruits with early softening are characterized by a loss of firmness in less than 10 days, even when stored under refrigeration. Although softened, the skin of the fruit remains partially green. Fruits with the disorder occurred more frequently from mid-summer to mid-autumn (February to May). It is not possible to distinguish early softening disorder fruits from those without the disorder by skin color and flesh firmness analysis at the time of the harvest.Tem sido relatado por produtores da regiĂŁo norte do EspĂrito Santo a ocorrĂȘncia de mamĂ”es 'Golden' com casca verde e polpa mole, em determinadas Ă©pocas do ano. O objetivo deste trabalho foi caracterizar e determinar a ocorrĂȘncia deste distĂșrbio denominado de amolecimento precoce. Foram realizadas coletas semanais durante 11 meses (perĂodo de setembro a julho). Os frutos foram armazenados a 10°C e analisados quanto Ă firmeza da polpa e Ă cor da casca. Os resultados de firmeza da polpa foram submetidos Ă anĂĄlise de regressĂŁo, assumindo-se que a equação Ă© do tipo linear, e o Ăąngulo de inclinação da curva foi chamado Ăndice de Amolecimento (IA). Frutos com o distĂșrbio caracterizaram-se pela perda da firmeza em menos de 10 dias, mesmo quando armazenados sob refrigeração. Embora amolecidos, a coloração da casca manteve-se parcialmente verde. A maior frequĂȘncia de frutos com o distĂșrbio ocorreu de meados de verĂŁo a meados de outono (fevereiro a maio). NĂŁo Ă© possĂvel distinguir frutos com o distĂșrbio do amolecimento precoce daqueles normais pela anĂĄlise da cor da casca e da firmeza da polpa, no momento da colheita
A review of the use of blood and blood products in HIV-infected patients
Despite numerous publications on the appropriate use of blood and blood products, few specifically consider the role of transfusion in the management of HIV. This review is a synthesis of conditions encountered in the management of HIV-infected patients where the transfusion of blood or blood products may be indicated. A consistent message emerging from the review is that the principles of transfusion medicine do not differ between HIV-negative and -positive patients. The aim of the review is to provide clinicians witha practical and succinct overview of the haematological abnormalities and clinical circumstances most commonly encountered in the HIV setting, while focusing on the rational and appropriate use of blood and blood products forHIV patients. Important ethical considerations in dealing with both the collection and transfusion blood and blood products in the HIV era have also been addressed
Atmospheric Muon Flux at Sea Level, Underground, and Underwater
The vertical sea-level muon spectrum at energies above 1 GeV and the
underground/underwater muon intensities at depths up to 18 km w.e. are
calculated. The results are particularly collated with a great body of the
ground-level, underground, and underwater muon data. In the hadron-cascade
calculations, the growth with energy of inelastic cross sections and pion,
kaon, and nucleon generation in pion-nucleus collisions are taken into account.
For evaluating the prompt muon contribution to the muon flux, we apply two
phenomenological approaches to the charm production problem: the recombination
quark-parton model and the quark-gluon string model. To solve the muon
transport equation at large depths of homogeneous medium, a semi-analytical
method is used. The simple fitting formulas describing our numerical results
are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially
all underground data on the muon intensity correlate with each other and with
predicted depth-intensity relation for conventional muons to within 10%.
However, the high-energy sea-level data as well as the data at large depths are
contradictory and cannot be quantitatively decribed by a single nuclear-cascade
model.Comment: 47 pages, REVTeX, 15 EPS figures included; recent experimental data
and references added, typos correcte
Comparative study of gamma-hidroxybutiric acid (GHB) and other derivative compounds by spectroelectrochemistry raman (SERS) on platinum surface.
The electrochemical behaviour of gamma-hydroxybutyric acid (GHB), the cyclic lactone derivative (GBL), 1-butanol, butyric acid and succinic acid on a platinum electrode in acidic medium has been studied by means of Raman spectroelectrochemistry using the SERS effect. Only GHB and 1-butanol were found to be electroactive substances that can form the acid product mainly and other species in minor proportion through the electro-catalytic oxidation reaction of alcohol group. The interaction of all these molecules with the platinum and platinum oxides, generated
during the electrodic process has been investigated in a wide interval of potentials.
Succinic acid was found to play the role of both intermediate (to produce the conjugate derivative) and product in GHB electrocatalytic oxidation. Likewise, the electrooxidation of 1-butanol produced butyric acid predominantly. The carbon (CH2) and the ring skeletons presented a predominant interaction with the platinum oxide surface for 1-butanol and GBL, respectively
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