Página 11 dos resultados de 1432 itens digitais encontrados em 0.016 segundos

Cyprinid swimming behaviour in response to turbulent flow

Silva, Ana T.; Katopodis, Christos; Santos, José M.; Ferreira, Maria Teresa; Pinheiro, António T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
25.88%
Turbulence is a complex phenomenon which commonly occurs in river and fishway flows. It is a difficult subject to study, especially biologically, yet turbulence may affect fish movements and fish passage efficiency. Studies on quantifying fish responses to turbulence, particularly within fishways, are lacking. This study investigated the swimming behaviour of 140 adult Iberian barbel (Luciobarbus bocagei) of two size-classes (small fish: 15 ≤ TL < 25 cm, large fish: 25 < TL ≤ 35 cm) under turbulent flow conditions created by three submerged orifice arrangements in an experimental pool-type fishway: (i) offset orifices, (ii) straight orifices and (iii) straight orifices with a deflector bar of 0.5bo located at 0.2L from the inlet orifices, where bo is the width of the square orifices ranging from 0.18 to 0.23 m and L is the pool length (1.90 m). Water velocity and turbulence (turbulent kinetic energy, Reynolds shear stress, turbulence intensity and eddy size) were characterized using a 3D Acoustic Doppler Velocimeter (ADV) and were related with fish swimming behaviour. The influence of turbulent flow on the swimming behaviour of barbel was assessed through the number of successful fish passage attempts and associated passage times. The amount of time fish spent in a certain cell of the pool (transit time) was measured and related to hydraulic conditions. The highest rates of passage and the corresponding lowest times were found in experiments conducted with offset orifices. Although size-related behavioural responses to turbulence were observed...

Behavioural and cognitive effects of simvastatin dose used in stimulation of bone regeneration in rats

Sousa,Dircilei Nascimento de; Santana,Washington Macedo de; Ferreira,Vania Moraes; Duarte,Wagner Rodrigues
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2014 Português
Relevância na Pesquisa
25.88%
PURPOSE: To analyze the effects of simvastatin (SVT) in the locomotion, anxiety and memory of rats, as a reflection of the administration of a minimum dose capable of stimulating bone regeneration in defects in the calvariae. METHODS: Surgical procedures were performed in 15 female Wistar rats, 2-month old, to insert the grafting material regenerator (Bone-ceramic(r)) and/or SVT, followed by behavioural and cognitive assessments in the 7th, 30th and 60th days post surgery. RESULTS: The SVT locally applied with the goal of bone regeneration in defects created in rat calvariae does not interfere with locomotion, anxiety levels and/or memories of rats, except for the first week following surgery, when an anxiolytic effect was observed, as a result of a possible central action. CONCLUSION: Failure to provoke any response within 30 and 60 days post surgical procedures suggests that SVT may constitute a good choice in stimulating bone regeneration without affecting the long term neural functions.

Continuous time estimation as a behavioural index of human cerebral ischaemia during temporary occlusion of the internal carotid artery.

Lazar, R M; Marshall, R S; Pile-Spellman, J; Young, W L; Hacein-Bey, L; Sloan, R P; Mohr, J P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1996 Português
Relevância na Pesquisa
25.88%
OBJECTIVE--To determine whether a continuous time estimation task during test occlusions of either internal carotid artery would increase the ability to detect the earliest signs of cerebral ischaemia in the anterior circulation. METHODS--Four patients were involved in real time measurement of their timing accuracy before, during, and after each test occlusion. While under each test condition, patients were instructed to press a mouse button connected to a computer and then to press it again no sooner than 10 seconds from the previous response but no longer than 13 seconds later. While being given automated feedback on accuracy, patients were instructed to continually press the mouse on the target schedule to maximise correct responses until told to stop. RESULTS--The data showed deterioration of timing accuracy during carotid occlusion (P < 0.05), which always preceded the onset of physical signs and correlated in one patient with the presence of reduced regional cerebral blood flow. CONCLUSION--Decline of sustained attention under conditions of test balloon occlusion of either internal carotid artery was an indicator of failure to maintain adequate cerebral blood flow to sustain normal neurological function. The demonstration of the behavioural effects of early cerebral ischaemia shows the feasibility of an experimental model for the study of human brain function...

Autoradiographical and behavioural effects of a chronic infusion of antisense to the α2D-adrenoceptor in the rat

Robinson, E S J; Nutt, D J; Hall, L; Jackson, H C; Hudson, A L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1999 Português
Relevância na Pesquisa
25.88%
The aims of this study were, firstly to use receptor autoradiography to investigate the effect of antisense oligonucleotides to the α2D-adrenoceptor on receptor binding and, secondly to measure behavioural and physiological parameters to determine whether the chronic antisense infusion had any effect on α2-adrenoceptor function in vivo.A 3 day infusion of antisense to the α2D-adrenoceptor significantly reduced specific [3H]-RX821002 binding in the septum (20–30%) and anterior hypothalamic area (20–30%). β-Adrenoceptor expression was unaffected in those brain areas examined, indicating the antisense knockdown was specific to the α2-adrenoceptors.On the second day of the infusion, the hypothermic response to UK 14,304 was significantly attenuated in the antisense-treated group compared with both vehicle and mismatch controls. The effect was fully reversible and a similar decrease in body temperature was observed in all the treatment groups 4 days after the end of infusion.During the second day of the infusion, the effects of UK 14,304 on behaviour were reduced in the antisense-treated rats, but were not significantly lower than those of the vehicle and mismatch, UK 14,304 controls. These trends were not observed 4 days after the end of the infusion.In conclusion...

The effects of putative 5-hydroxytryptamine antagonists on the behaviour produced by administration of tranylcypromine and L-tryptophan or tranylcypromine and L-DOPA to rats.

Deakin, J F; Green, A R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1978 Português
Relevância na Pesquisa
25.88%
1 The putative 5-hydroxytryptamine (5-HT) receptor blocking drugs methysergide (10 mg/kg) and methergoline (5 mg/kg) were found to abolish some components of the hyperactivity syndrome, including head weaving and forepaw treading, which follow administration to rats of tranylcypromine (20 mg/kg) and L-tryptophan (100 mg/kg). Hyperactivity and hyper-reactivity were potentiated with a resultant increase in automated locomotor activity counts. In contrast (-)-propranolol (20 mg/kg) inhibited all features of the syndrome. The same results were obtained with these drugs when the behaviour was elicited by p-chloroamphetamine (10 mg/kg) or by tranylcypromine and tryptamine (10 mg/kg). 2 Methysergide and methergoline had similar effects on the syndrome produced by tranylcypromine and L-DOPA (50 mg/kg) whereas propranolol was without effect. 3 None of the putative 5-HT receptor antagonists affected brain 5-HT turnover as assessed by rate of accumulation of 5-HT following monoamine oxidase inhibition with tranylcypromine. 4 Microinjections of 5,7-dihydroxytryptamine into the spinal cord resulted in a 70% fall in cord 5-HT concentrations without an effect on brain 5-HT concentrations. The behavioural response to the putative 5-HT receptor agonist...

The uses of colour vision: behavioural and physiological distinctiveness of colour stimuli.

Derrington, Andrew M; Parker, Amanda; Barraclough, Nick E; Easton, Alexander; Goodson, G R; Parker, Kris S; Tinsley, Chris J; Webb, Ben S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 29/08/2002 Português
Relevância na Pesquisa
25.88%
Colour and greyscale (black and white) pictures look different to us, but it is not clear whether the difference in appearance is a consequence of the way our visual system uses colour signals or a by-product of our experience. In principle, colour images are qualitatively different from greyscale images because they make it possible to use different processing strategies. Colour signals provide important cues for segmenting the image into areas that represent different objects and for linking together areas that represent the same object. If this property of colour signals is exploited in visual processing we would expect colour stimuli to look different, as a class, from greyscale stimuli. We would also expect that adding colour signals to greyscale signals should change the way that those signals are processed. We have investigated these questions in behavioural and in physiological experiments. We find that male marmosets (all of which are dichromats) rapidly learn to distinguish between colour and greyscale copies of the same images. The discrimination transfers to new image pairs, to new colours and to image pairs in which the colour and greyscale images are spatially different. We find that, in a proportion of neurons recorded in the marmoset visual cortex...

Behavioural models of population growth rates: implications for conservation and prediction.

Sutherland, William J; Norris, Ken
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 29/09/2002 Português
Relevância na Pesquisa
25.88%
Conservation biologists often wish to predict how vertebrate populations will respond to local or global changes in conditions such as those resulting from sea-level rise, deforestation, exploitation, genetically modified crops, global warming, human disturbance or from conservation activities. Predicting the consequences of such changes almost always requires understanding the population growth rate and the density dependence. Traditional means of directly measuring density dependence are often extremely difficult and have the problem that if the environment changes then it is necessary to remeasure the density dependence. We describe an alternative approach that does not require such long datasets and can be used to predict the density dependence under novel conditions. Game theory can be used to describe behavioural decisions that individuals make in response to interference, prey depletion, territorial behaviour or social dominance, and the resultant fitness consequences. It is then possible to predict how survival or reproductive output changes with population size. From this we can then make predictions about the responses of populations to environmental changes. We will illustrate how this can be applied to a range of species and a range of applied problems.

The effects of dihydropyridine compounds in behavioural tests of dopaminergic activity.

Bourson, A.; Gower, A. J.; Mir, A. K.; Moser, P. C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1989 Português
Relevância na Pesquisa
25.88%
1. The effects of the dihydropyridine calcium channel blocker nifedipine and the activator Bay K 8644 were investigated in different behavioural tests involving dopaminergic systems. These were the discriminative stimulus induced by amphetamine, rotational behaviour in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions and apomorphine-induced yawning in rats. 2. The yawning induced by apomorphine (40 micrograms kg-1 s.c.) was significantly potentiated by nifedipine (5-10 mgkg-1 i.p.). Bay K 8644 (0.05-0.5 mgkg-1 i.p.) dose-dependently inhibited yawning induced by apomorphine (80 micrograms kg-1 s.c.) and, at 0.4 mgkg-1, inhibited the nifedipine potentiation of apomorphine-induced yawning. In contrast to their effects on apomorphine-induced yawning, nifedipine and Bay K 8644 had no effect on apomorphine-induced penile erection. 3. Bay K 8644 (0.06-0.5 mgkg-1 i.p.) and nifedipine (5-20 mgkg-1 i.p.) had no dose-related effect on the discrimination performance of rats trained to discriminate amphetamine from saline. However, nifedipine dose-dependently reduced the response rate of amphetamine-treated rats. Bay K 8644 had no effect on this measure except at high doses that also caused disruption. 4. Neither nifedipine (5-10 mgkg-1 i.p.) nor Bay K 8644 (0.06-0.5 mgkg-1 i.p.) affected the turning behaviour induced by amphetamine (1 mgkg-1 i.p.) in rats with unilateral 6-OHDA lesion of the medial forebrain bundle...

5-HT2 receptor characteristics in frontal cortex and 5-HT2 receptor-mediated head-twitch behaviour following antidepressant treatment to mice.

Goodwin, G. M.; Green, A. R.; Johnson, P.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /09/1984 Português
Relevância na Pesquisa
25.9%
The effects of repeated administration of antidepressant drugs or electroconvulsive shock on the binding of [3H]-spiperone to the 5-hydroxytryptamine 2 (5-HT2) receptor in mouse frontal cortex and the 5-HT-mediated head-twitch response have been examined. Repeated electroconvulsive shock increased both the head-twitch response and the number of 5-HT2 binding sites (Bmax). After 35 d but not 24 h or 14 d oral tranylcypromine (5.6 mg kg-1 per day) there was a marked decrease in both the behavioural response and the number of 5-HT2 receptors. Repeated oral doses of zimeldine (20 mg kg-1 per day, 14 days) also decreased the head-twitch response and the number of 5-HT2 binding sites and these effects persisted after 48 h withdrawal. Oral mianserin (2.1 mg kg-1 per day, 14 days) decreased both the behaviour and the number of 5-HT2 binding sites, but this change was also seen after acute (1 day) administration. After 48 h withdrawal from chronic treatment the head-twitch response was still decreased but the Bmax had returned to control values. Desipramine given orally (27 mg kg-1 per day, 14 days) decreased both the behaviour and number of 5-HT2 binding sites. After 48 h withdrawal, binding was still decreased but the head-twitch response was enhanced above control values. In contrast to repeated electroconvulsive shock (ECS)...

Response monitoring, repetitive behaviour and anterior cingulate abnormalities in autism spectrum disorders (ASD)

Thakkar, Katharine N.; Polli, Frida E.; Joseph, Robert M.; Tuch, David S.; Hadjikhani, Nouchine; Barton, Jason J.S.; Manoach, Dara S.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.91%
Autism spectrum disorders (ASD) are characterized by inflexible and repetitive behaviour. Response monitoring involves evaluating the consequences of behaviour and making adjustments to optimize outcomes. Deficiencies in this function, and abnormalities in the anterior cingulate cortex (ACC) on which it relies, have been reported as contributing factors to autistic disorders. We investigated whether ACC structure and function during response monitoring were associated with repetitive behaviour in ASD. We compared ACC activation to correct and erroneous antisaccades using rapid presentation event-related functional MRI in 14 control and ten ASD participants. Because response monitoring is the product of coordinated activity in ACC networks, we also examined the microstructural integrity of the white matter (WM) underlying this brain region using diffusion tensor imaging (DTI) measures of fractional anisotropy (FA) in 12 control and 12 adult ASD participants. ACC activation and FA were examined in relation to Autism Diagnostic Interview-Revised ratings of restricted and repetitive behaviour. Relative to controls, ASD participants: (i) made more antisaccade errors and responded more quickly on correct trials; (ii) showed reduced discrimination between error and correct responses in rostral ACC (rACC)...

Contrast effects in response rate and accuracy of delayed matching to sample

Nevin, John A.; Shahan, Timothy A.; Odum, Amy L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/2008 Português
Relevância na Pesquisa
25.89%
Behavioural contrast is an inverse relation between the response rate in one component of a multiple schedule and the reinforcer rate in an alternated component. To explore possible contrast effects in accuracy as well as response rate, four pigeons were trained in multiple schedules where key pecking produced delayed matching-to-sample trials on a variable-interval schedule. Reinforcer probability for correct matches was constant at .3 in one component, and the conditions of reinforcement were varied in the second component. In Experiment 1, the varied component arranged the same contingencies as the constant component but with reinforcer probabilities of .9 or .1 across conditions. In the varied component, both response rate and accuracy of delayed matching were directly related to reinforcer probability; in the constant component, however, contrast effects on response rate were weak, and there was no evidence of contrast in accuracy of matching. In Experiment 2, the varied component was either variable interval with immediate food reinforcement or extinction. Reliable contrast effects were obtained in both response rate and in accuracy of matching in the constant component, and their magnitudes were correlated within and between subjects. The results of Experiment 2 join previous findings of covariation in the effects of reinforcement on free-operant responding and accuracy of discrimination.

Dissociable correlates of response conflict and error awareness in error-related brain activity

Hughes, Gethin; Yeung, Nick
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.9%
Errors in speeded decision tasks are associated with characteristic patterns of brain activity. In the scalp-recorded EEG, error processing is reflected in two components, the error-related negativity (ERN) and the error positivity (Pe). These components have been widely studied, but debate remains regarding the precise aspects of error processing they reflect. The present study investigated the relation between the ERN and Pe using a novel version of the flanker task to allow a comparison between errors reflecting different causes—response conflict versus stimulus masking. The conflict and mask conditions were matched for overall behavioural performance but differed in underlying response dynamics, as indexed by response time distributions and measures of lateralised motor activity. ERN amplitude varied in relation to these differing response dynamics, being significantly larger in the conflict condition compared to the mask condition. Furthermore, differences in response dynamics between participants were predictive of modulations in ERN amplitude. In contrast, Pe activity varied little between conditions, but varied across trials in relation to participants‘ awareness of their errors. Taken together, these findings suggest a dissociation between the ERN and Pe...

Selective Heterogeneity in Exoprotease Production by Bacillus subtilis

Davidson, Fordyce A.; Seon-Yi, Chung; Stanley-Wall, Nicola R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/06/2012 Português
Relevância na Pesquisa
25.89%
Bacteria have elaborate signalling mechanisms to ensure a behavioural response that is most likely to enhance survival in a changing environment. It is becoming increasingly apparent that as part of this response, bacteria are capable of cell differentiation and can generate multiple, mutually exclusive co-existing cell states. These cell states are often associated with multicellular processes that bring benefit to the community as a whole but which may be, paradoxically, disadvantageous to an individual subpopulation. How this process of cell differentiation is controlled is intriguing and remains a largely open question. In this paper, we consider an important aspect of cell differentiation that is known to occur in the Gram-positive bacterium Bacillus subtilis: we investigate the role of two master regulators DegU and Spo0A in the control of extra-cellular protease production. Recent work in this area focussed the on role of DegU in this process and suggested that transient effects in protein production were the drivers of cell-response heterogeneity. Here, using a combination of mathematical modelling, analysis and stochastic simulations, we provide a complementary analysis of this regulatory system that investigates the roles of both DegU and Spo0A in extra-cellular protease production. In doing so...

Alcohol delays the emergence of the fetal elicited startle response, but only transiently

Hepper, Peter G; Dornan, James C; Lynch, Catherine; Maguire, Jennifer F
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.9%
Prenatal exposure to alcohol may exert a significant detrimental effect on the functioning of the individual’s brain, however few studies have examined this before birth. This longitudinal study examined the effect of maternal alcohol consumption on the elicited startle response of the fetus. Two groups of fetuses were examined: one whose mothers drank alcohol (approximately 10 units per week); the other whose mothers did not drink alcohol. Fetuses were examined at 29, 32 and 35 weeks gestation and their startle response observed using ultrasound in response to 2 presentations of a pink noise (70–250Hz) at 90dB(A) separated by 30 seconds. Fetuses exposed to alcohol exhibited a weaker startle response at 29 weeks gestation than did fetuses not exposed to alcohol. There was no difference in the response at 32 and 35 weeks gestation. To ensure the effects were not due to a more general effect of alcohol on fetal movement, a second experiment compared the spontaneous movements (observed on ultrasound for 45 minutes) of fetuses whose mothers drank alcohol and fetuses of mothers who didn’t drink alcohol. There were no differences in movements exhibited by the fetuses. The results suggest that exposure to alcohol delays the emergence of the elicited startle response at 29 weeks gestation but this delay has disappeared by 32 weeks gestation. The possible role of altered neural development...

Human standing is modified by an unconscious integration of congruent sensory and motor signals

Luu, Billy L; Inglis, J Timothy; Huryn, Thomas P; Van der Loos, H F Machiel; Croft, Elizabeth A; Blouin, Jean-Sébastien
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.9%
We investigate whether the muscle response evoked by an electrically induced vestibular perturbation during standing is related to congruent sensory and motor signals. A robotic platform that simulated the mechanics of a standing person was used to manipulate the relationship between the action of the calf muscles and the movement of the body. Subjects braced on top of the platform with the ankles sway referenced to its motion were required to balance its simulated body-like load by modulating ankle plantar-flexor torque. Here, afferent signals of body motion were congruent with the motor command to the calf muscles to balance the body. Stochastic vestibular stimulation (±4 mA, 0–25 Hz) applied during this task evoked a biphasic response in both soleus muscles that was similar to the response observed during standing for all subjects. When the body was rotated through the same motion experienced during the balancing task, a small muscle response was observed in only the right soleus and in only half of the subjects. However, the timing and shape of this response did not resemble the vestibular-evoked response obtained during standing. When the balancing task was interspersed with periods of computer-controlled platform rotations that emulated the balancing motion so that subjects thought that they were constantly balancing the platform...

Personality, stressful life events, and treatment response in major depression

Bulmash, Eric Lewis
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 212727 bytes; application/pdf
Português
Relevância na Pesquisa
25.9%
Major Depression (MD) currently affects over 17 million individuals in North America (Greenberg et al., 2003). Identifying factors predictive of MD treatment response is important for developing more efficacious treatments and better understanding MD vulnerability. The goal of the present study was to examine the main and interactive effects of personality and stressful life events as predictors of MD treatment response. One hundred and thirty-one clinically depressed participants were randomly assigned to either 16-weeks of cognitive behavioural therapy (CBT), interpersonal psychotherapy (IPT), or pharmacotherapy (PT). Personality in the form of trait self-criticism, neediness, and connectedness was assessed at pre and post-treatment using the Depressive Experiences Questionnaire (DEQ; Blatt et al., 1976). Stressful life events experienced during treatment were assessed using the Life Events and Difficulties Schedule (LEDS; Bifulco et al., 1989). Results revealed that amongst individuals scoring lower in pre-treatment self-criticism, higher pre-treatment connectedness predicted superior treatment response. As well, amongst individuals scoring lower in pre-treatment neediness, higher pre-treatment connectedness predicted superior treatment response. In terms of personality change...

Behavioural responses of iberian midwife toad tadpoles (Alytes cisternasii) to an introduced exotic predator, Procambarus cllarkii: respostas comportamentais dos girinos de sapo parteiro ibérico (Alytes cisternasii) a um predador exótico, Procambarus clarkii

Gonçalves, Vera Lúcia Ramos
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
25.96%
O principal alvo das investigações realizadas em conservação tem sido a perda de biodiversidade, tendo sido identificada a introdução de espécies exóticas como uma das principais causas do declínio e extinção de espécies a nível global. Nas últimas décadas, foi relatado o desaparecimento repentino e a regressão na área de distribuição de numerosas espécies de anfíbios, a nível mundial. Entre os fatores de ameaça mais apontados para este declínio também se encontra a introdução de espécies exóticas predadoras e competidoras. Na Península ibérica, a introdução de Procambarus clarkii, que constitui um predador de ovos e larvas de amóbios (especificamente de todas as espécies do sudoeste peninsular) poderá estar relacionada com a rarefação e desaparecimento de algumas populações. Contudo, a predação, por predadores nativos ou introduzidos, pode também ser uma importante força de seleção, resultando frequentemente na evolução de defesas antipredatórias. Encontram-se descritos alguns comportamentos antipredatórios apresentados por larvas de anfíbios, que podem ser adotados na presença de pistas químicas de predadores, e que parecem ser importantes para a coexistência dos anfíbios com os mesmos. O objetivo desta dissertação foi:avaliar quais as alterações comportamentais adotadas pelos girinos de Alytes cistemasii perante um predador exótico recentemente introduzido...

Does stress response predict return rate in a migratory bird species? A study of American redstarts and their non-breeding habitat

Angelier, Frédéric; Holberton, Rebecca L.; Marra, Peter P.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.9%
In vertebrates, the adrenocortical stress response activates an emergency life-history stage, which is thought to promote survival by helping individuals escape life-threatening situations. Although the adrenocortical stress response promotes many behavioural and physiological changes, it remains unclear whether this stress response actually translates into higher survival in wild vertebrates. We measured the adrenocortical stress response of non-breeding American redstarts (Setophaga ruticilla), a migratory bird that wintered in habitats of either high (mangroves) or low suitability (scrubs), and subsequently monitored their return rate during the following non-breeding seasons. The intensity of the adrenocortical stress response was consistent within individuals across the non-breeding season and was positively correlated with return rates in redstarts that wintered in scrubs, but not in redstarts that wintered in mangroves. Thus, in a context-dependent manner, the ability of an individual to physiologically react to stress determines its ability of returning to its non-breeding territory the following winters. For an individual, the ability to mount an important adrenocortical stress response probably benefits to survival. However...

Courtship and genetic quality: asymmetric males show their best side

Gross, Mart R; Suk, Ho Young; Robertson, Cory T
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.96%
Fluctuating asymmetry (FA), the small random deviations from perfect morphological symmetry that result during development, is ubiquitous throughout the animal kingdom. In many species, FA seems to play a role in mate choice, perhaps because it signals an individual's genetic quality and health. However, the relationship between an individual's FA and behaviour is generally unknown: what do more asymmetric individuals do about their own asymmetry? We now show for the first time that individuals respond behaviourally to their own morphological FA in what appears to be an adaptive manner. During courtship, male guppies exhibiting high FA in ornamental colour, bias their displays towards their more colourful body side, thus potentially increasing their attractiveness by exaggerating the quantity of their orange signal. This appears to be a strictly behavioural male response to cues provided by females, as it does not occur when males court a non-reactive model female. Whether inferior males realize any mating advantage remains uncertain, but our study clearly demonstrates a behavioural response to random morphological asymmetries that appears to be adaptive. We propose that the tendency to show or otherwise use a ‘best side’ is common in nature...

Psychological aspects of survey methodology: Experiments on the response process.

Murphy, Margaret Kathleen
Fonte: London School of Economics and Political Science Thesis Publicador: London School of Economics and Political Science Thesis
Tipo: Thesis; NonPeerReviewed Formato: application/pdf
Publicado em //1996 Português
Relevância na Pesquisa
25.92%
This thesis examines the psychological processes involved in responding to survey questions. Minor variations in questions have been shown to lead to variation in responses. These findings are inconsistent with the assumption that survey questions are tapping stable responses. Recently, psychological theories have been used to provide an explanation for these response effects. Research applying psychological theory to survey response is reviewed, covering research on both behavioural and attitudinal questions. These reviews illustrate a reconceptualisation of the basis of the survey response. The need for more detailed data on the response process is identified. Verbal reports are identified as a potential method for producing process data, yet, uncertainty over their validity is noted. The use of verbal reports as data is then reviewed, covering both their historical and more recent use. In the present research verbal report techniques are first experimentally examined to find an appropriate technique for obtaining process data in surveys. Think-aloud techniques are then used to examine the processes involved in responding to questions. A split-ballot questionnaire was administered, varying a number of questionnaire features where response effects have been hypothesised or shown to occur. Generally...