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1.
The changes in species composition between habitat patches (beta diversity) are likely related to a number of factors, including environmental heterogeneity, connectivity, disturbance and productivity. Here, we used data from aquatic environments in five Brazilian regions over two years and two seasons (rainy and dry seasons or high and low water level periods in floodplain lakes) in each year to test hypotheses underlying zooplankton beta diversity variation. The regions present different levels of hydrological connectivity, where three regions present lakes that are permanent and connected with the main river, while the water bodies of the other two regions consist of permanent lakes and temporary ponds, with no hydrological connections between them. We tested for relationships between zooplankton beta diversity and environmental heterogeneity, spatial extent, hydrological connectivity, seasonality, disturbance and productivity. Negative relationships were detected between zooplankton beta diversity and both hydrological connectivity and disturbance (periodic dry-outs). Hydrological connectivity is likely to affect beta diversity by facilitating dispersal between habitats. In addition, the harsh environmental filter imposed by disturbance selected for only a small portion of the species from the regional pool that were able to cope with periodic dry-outs (e.g., those with a high production of resting eggs). In summary, this study suggests that faunal exchange and disturbance play important roles in structuring local zooplankton communities.  相似文献   

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The grounded cognition framework proposes that sensorimotor brain areas, which are typically involved in perception and action, also play a role in linguistic processing. We assessed oscillatory modulation during visual presentation of single verbs and localized cortical motor regions by means of isometric contraction of hand and foot muscles. Analogously to oscillatory activation patterns accompanying voluntary movements, we expected a somatotopically distributed suppression of beta and alpha frequencies in the motor cortex during processing of body-related action verbs. Magnetoencephalographic data were collected during presentation of verbs that express actions performed using the hands (H) or feet (F). Verbs denoting no bodily movement (N) were used as a control. Between 150 and 500 msec after visual word onset, beta rhythms were suppressed in H and F in comparison with N in the left hemisphere. Similarly, alpha oscillations showed left-lateralized power suppression in the H-N contrast, although at a later stage. The cortical oscillatory activity that typically occurs during voluntary movements is therefore found to somatotopically accompany the processing of body-related verbs. The combination of a localizer task with the oscillatory investigation applied to verb reading as in the present study provides further methodological possibilities of tracking language processing in the brain.  相似文献   

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Going back to Kohlberg, moral development research affirms that people progress through different stages of moral reasoning as cognitive abilities mature. Individuals at a lower level of moral reasoning judge moral issues mainly based on self-interest (personal interests schema) or based on adherence to laws and rules (maintaining norms schema), whereas individuals at the post-conventional level judge moral issues based on deeper principles and shared ideals. However, the extent to which moral development is reflected in structural brain architecture remains unknown. To investigate this question, we used voxel-based morphometry and examined the brain structure in a sample of 67 Master of Business Administration (MBA) students. Subjects completed the Defining Issues Test (DIT-2) which measures moral development in terms of cognitive schema preference. Results demonstrate that subjects at the post-conventional level of moral reasoning were characterized by increased gray matter volume in the ventromedial prefrontal cortex and subgenual anterior cingulate cortex, compared with subjects at a lower level of moral reasoning. Our findings support an important role for both cognitive and emotional processes in moral reasoning and provide first evidence for individual differences in brain structure according to the stages of moral reasoning first proposed by Kohlberg decades ago.  相似文献   

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南岭国家级自然保护区林下植物分布的地形相关性   总被引:3,自引:0,他引:3  
以南岭国家级自然保护区山地森林群落林下植物为研究对象,探讨地形因子对林下植物分布的影响。该区3个海拔高度下的山地常绿阔叶林林下植物组成丰富,但个体多度在样方中的分布存在很大的空间异质性。在9000m^2的样地中设置的450个4m^2小样方,共记录到林下维管植物255种,隶属于95科、181属,总的物种个体多度为18203株。多响应置换过程(MRPP)分析表明,坡向和海拔(p〈0.0001)及坡度(p〈0.05)这3个地形因子对林下植被分布有显著的影响,其影响程度大小排序为:海拔〉坡向〉坡度。指示种分析(ISA)进一步确定了不同地形条件下具有显著指示值(IV≥50)的指示种。本项研究表明林下植物的空间分布会同时受到多个地形因子的影响,因此需综合各因子间的相互作用全面考虑;同时,MRPP结合ISA对于揭示群落植物分布的空间异质性及其与环境因子作用的相互关系、生物多样性保育、森林恢复以及造林引种等方面均有着重要的理论意义和实践价值。  相似文献   

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The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. Modulations in beta power were already evident prior to the expected onset times of the tones. These findings suggest that expectation and attention jointly modulate sensory processing.  相似文献   

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Separate lines of research have noted recruitment of parietal cortex during tasks involving visuo-spatial processes and empathy. To explore the relationship between these two functions, a self-other perspective transformation task and a task of spatial attention (line bisection) were administered to 40 healthy participants (19 women). Performance on these tasks was examined in relation to self-reported empathy. Rightward biases in line bisection correlated positively with trait-level self-reported empathic concern, suggesting a left hemisphere mediation of this prosocial personality trait. Unexpectedly, speed of perspective taking in the self-other transformation task correlated negatively with empathic concern, but only in women, which we interpret in light of gender differences in empathy and strategies for egocentric mental transformations. Together, the findings partially support the commonalities in visuo-spatial attention, perspective-taking and empathy. More broadly, they shed additional light on the relationship between basic cognitive functions and complex social constructs.  相似文献   

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BackgroundThere is emerging evidence that the supplementation of omega-3 contributes to a decrease in aggressive behaviour in prison populations. A challenge of such research is achieving statistical power against effect sizes which may be affected by the baseline omega-3 index. There are no published data on the blood omega-3 index with studies of this kind to assess the variability of the blood omega-3 index in conjunction with aggression and attention deficit assessments.ObjectiveTo determine if the variance of the omega-3 index is correlated with aggressive and attention deficit behaviour in a prison population.Design136 adult male prisoners were recruited from South Coast Correctional Centre (SCCC), NSW Australia. A 7 point categorisation was used to quantify levels of aggressive behaviour (4 weeks) from individual SCCC case notes, whereby higher scores correspond to increasingly aggressive behaviour. Study participants completed the Aggression Questionnaire (AQ) and the Brown’s Attention Deficit Disorder Scales (BADDS), provided a blood sample for erythrocyte fatty acid analysis using gas chromatography and the omega-3 index was calculated.ResultsThe baseline omega-3 index ranged from 2.3% to 10.3%, indicating that some participants already had substantial omega-3 intake, however a median of 4.7% indicated a lower overall omega-3 intake than the general Australian population. Assessment of aggressive and attention deficit behaviour shows that there were negative correlations between baseline omega-3 index and baseline aggression categorisation scores (r = −0.21, P = 0.016); total AQ score (r = −0.234, P = 0.011); Anger (r = -0.222 p = 0.016); Hostility AQ (r = −0.239, P = 0.009); indirect aggression (r = −0.188 p = 0.042); total BADDS (r = −0.263, p = 0.005); Activation (r = −0.224, p = 0.016); Attention (r = −0.192, p = 0.043); Effort (r = −0.253, p = 0.007); Affect (r = −0.330, p = 0.000) and Memory (r = −0.240, p = 0.010).ConclusionsThere is a high variability in omega-3 status of a NSW prison population, and inmates with lower omega-3 index were more aggressive and had higher ADD scores.  相似文献   

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Introduction

In idiopathic generalized epilepsy (IGE), a normal electroencephalogram between generalized spike and wave (GSW) discharges is believed to reflect normal brain function. However, some studies indicate that even excluding GSW-related errors, IGE patients perform poorly on sustained attention task, the deficit being worse as a function of disease duration. We hypothesized that at least in a subset of structures which are normally involved in sustained attention, resting-state functional connectivity (FC) is different in IGE patients compared to controls and that some of the changes are related to disease duration.

Method

Seeds were selected based on a sustained attention study in controls. Resting-state functional magnetic resonance imaging (fMRI) data was obtained from 14 IGE patients and 14 matched controls. After physiological noise removal, the mean time-series of each seed was used as a regressor in a general linear model to detect regions that showed correlation with the seed. In patients, duration factor was defined based on epilepsy duration. Between-group differences weighted by the duration factor were evaluated with mixed-effects model. Correlation was then evaluated in IGE patients between the FC, averaged over each significant cluster, and the duration factor.

Results

Eight of 18 seeds showed significant difference in FC across groups. However, only for seeds in the medial superior frontal and precentral gyri and in the medial prefrontal area, average FC taken over significant clusters showed high correlation with the duration factor. These 3 seeds showed changes in FC respectively with the premotor and superior frontal gyrus, the dorsal premotor, and the supplementary motor area plus precentral gyrus.

Conclusion

Alterations of FC in IGE patients are not limited to the frontal areas. However, as indicated by specificity analysis, patients with long history of disease show changes in FC mainly within the frontal areas.  相似文献   

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Background

Observational studies have reported higher mortality among older adults treated with first-generation antipsychotics (FGAs) versus second-generation antipsychotics (SGAs). A few studies examined risk for medical events, including stroke, ventricular arrhythmia, venous thromboembolism, myocardial infarction, pneumonia, and hip fracture.

Objectives

1) Review robust epidemiologic evidence comparing mortality and medical event risk between FGAs and SGAs in older adults; 2) Quantify how much these medical events explain the observed mortality difference between FGAs and SGAs.

Data sources

Pubmed and Science Citation Index.

Study eligibility criteria, participants, and interventions

Studies of antipsychotic users that: 1) evaluated mortality or medical events specified above; 2) restricted to populations with a mean age of 65 years or older 3) compared FGAs to SGAs, or both to a non-user group; (4) employed a “new user” design; (5) adjusted for confounders assessed prior to antipsychotic initiation; (6) and did not require survival after antipsychotic initiation. A separate search was performed for mortality estimates associated with the specified medical events.

Study appraisal and synthesis methods

For each medical event, we used a non-parametric model to estimate lower and upper bounds for the proportion of the mortality difference—comparing FGAs to SGAs—mediated by their difference in risk for the medical event.

Results

We provide a brief, updated summary of the included studies and the biological plausibility of these mechanisms. Of the 1122 unique citations retrieved, we reviewed 20 observational cohort studies that reported 28 associations. We identified hip fracture, stroke, myocardial infarction, and ventricular arrhythmias as potential intermediaries on the causal pathway from antipsychotic type to death. However, these events did not appear to explain the entire mortality difference.

Conclusions

The current literature suggests that hip fracture, stroke, myocardial infarction, and ventricular arrhythmias partially explain the mortality difference between SGAs and FGAs.  相似文献   

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B N Singh  S Mohanty 《Génome》1990,33(4):592-595
Two linked inversions, AL and ZE, located in the opposite limbs of the second chromosome of Drosophila ananassae are separated from each other by nearly 32% of the total length of the second chromosome. Crossing-over between these inversions when heterozygous was studied in females and males by the salivary-gland smear technique using karyotypically homozygous stocks. The results of recombination experiments show that there is a strong suppression of recombination between inversions when heterozygous, in spite of a large euchromatic distance available for crossing-over between them. Thus there is no correlation between chromosome distance and crossing-over between heterozygous inversions in the second chromosome of D. ananassae when studied cytologically.  相似文献   

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正Besides upper tract urothelial cell carcinoma(UTUCs),a recent study published in Science Translational Medicine has indicated that liver cancer may be associated with the exposure of aristolochic acids and similar derivatives(collectively,AA).However,according to our research,this study needs more number of samples for further verification which should be sampled from a wider range of people.  相似文献   

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Different assemblages of intertidal biota may be associated with the hardness of the rock type that comprises the seashore. However, very few published studies have investigated mobile and sessile assemblage differences between hardness classes. To remedy this, we investigated the physical attributes and biotic assemblages of 12 rock platforms across two bioregions, encompassing seven rock types categorised into either the soft (≤4 using Moh’s scale of scratch hardness) or hard (>4 on Moh’s scale) classes. Rock types from the soft versus hard classes differed physically, but the biotic assemblages showed few general differences between hardness classes. Instead, most biotic differences associated with rock hardness were specific to just one of the marine bioregions sampled, not both. Hardness-related assemblage differences were only weakly-to-moderately correlated with hardness differences in mineralogy or microhabitat density. The detection of bioregion-specific hardness differences for intertidal assemblages, rather than general hardness class trends, indicate that the type of rock comprising the seashore in each bioregion may be more strongly associated with the biotic patterns identified than hardness per se.  相似文献   

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