Temporal coupling between stimulus-evoked neural activity and hemodynamic responses from individual cortical columns

Using previously published data from the whisker barrel cortex of anesthetized rodents (Berwick et al 2008 J. Neurophysiol. 99 787–98) we investigated whether highly spatially localized stimulus-evoked cortical hemodynamics responses displayed a linear time-invariant (LTI) relationship with neural activity. Presentation of stimuli to individual whiskers of 2 s and 16 s durations produced hemodynamics and neural activity spatially localized to individual cortical columns. Two-dimensional optical imaging spectroscopy (2D-OIS) measured hemoglobin responses, while multi-laminar electrophysiology recorded neural activity. Hemoglobin responses to 2 s stimuli were deconvolved with underlying evoked neural activity to estimate impulse response functions which were then convolved with neural activity evoked by 16 s stimuli to generate predictions of hemodynamic responses. An LTI system more adequately described the temporal neuro-hemodynamics coupling relationship for these spatially localized sensory stimuli than in previous studies that activated the entire whisker cortex. An inability to predict the magnitude of an initial 'peak' in the total and oxy- hemoglobin responses was alleviated when excluding responses influenced by overlying arterial components. However, this did not improve estimation of the hemodynamic responses return to baseline post-stimulus cessation.

Information communication technologies and distance education in Sri Lanka: a case study of two universities

Sri Lanka's participation rates in higher education are low and have risen only slightly in the last few decades; the number of places for higher education in the state university system only caters for around 3% of the university entrant age cohort. The literature reveals that the highly competitive global knowledge economy increasingly favours workers with high levels of education who are also lifelong learners. This lack of access to higher education for a sizable proportion of the labour force is identified as a severe impediment to Sri Lanka‟s competitiveness in the global knowledge economy. The literature also suggests that Information and Communication Technologies are increasingly relied upon in many contexts in order to deliver flexible learning, to cater especially for the needs of lifelong learners in today‟s higher educational landscape. The government of Sri Lanka invested heavily in ICTs for distance education during the period 2003-2009 in a bid to increase access to higher education; but there has been little research into the impact of this. To address this lack, this study investigated the impact of ICTs on distance education in Sri Lanka with respect to increasing access to higher education. In order to achieve this aim, the research focused on Sri Lanka‟s effort from three perspectives: policy perspective, implementation perspective and user perspective. A multiple case study research using an ethnographic approach was conducted to observe Orange Valley University‟s and Yellow Fields University‟s (pseudonymous) implementation of distance education programmes using questionnaires, qualitative interviewing and document analysis. In total, data for the analysis was collected from 129 questionnaires, 33 individual interviews and 2 group interviews. The research revealed that ICTs have indeed increased opportunities for higher education; but mainly for people of affluent families from the Western Province. Issues identified were categorized under the themes: quality assurance, location, language, digital literacies and access to resources. Recommendations were offered to tackle the identified issues in accordance with the study findings. The study also revealed the strong presence of a multifaceted digital divide in the country. In conclusion, this research has shown that iii although ICT-enabled distance education has the potential to increase access to higher education the present implementation of the system in Sri Lanka has been less than successful.

Measuring students' emotions in the early years: the Achievement Emotions Questionnaire-Elementary School (AEQ-ES)

This article reports about the development and validation of a measurement instrument assessing elementary school students' achievement emotions (Achievement Emotions Questionnaire-Elementary School, AEQ-ES). Specifically, the instrument assesses students' enjoyment, anxiety, and boredom pertaining to three types of academic settings (i.e., attending class, doing homework, and taking tests and exams). Scale construction was based on Pekrun's (2006) control-value theory of achievement emotions. The instrument was tested using samples from German and American elementary school classrooms. The results of Study 1 (German sample) corroborate the reliability and structural validity of the new emotion measure. Moreover, they show that students' achievement emotions were linked with their control and value appraisals as well as their academic performance, thus supporting the external validity of the measure as well as propositions of Pekrun's (2006) control-value theory of achievement emotions. Study 2 (American sample) corroborated the cross-cultural equivalence of the measure and the generalizability of findings across the German and American samples. Implications for research on achievement emotions and educational practice are discussed. (PsycINFO Database Record (c) 2013 APA, all rights reserved)(journal abstract)

Heterosite effects in novel heteronuclear clusters [OS2Ru(CO)(11)(PPh3)] and Os2Ru(CO)(10)(2-acetylpyridine-N-isopropylimine)]

A new synthetic route towards the mixed-metal cluster [OS2Ru(CO)(12)] is described together with the syntheses of its PPh3 and iPr-AcPy (iPr-AcPy = 2-acetylpyridine-N-isopropylimine) derivatives. The molecular structures of the novel clusters [Os2Ru(CO)(11)(PPh3)] and [Os2Ru(CO)(10)(iPr-AcPy)] were determined on the basis of crystalline solid solutions of the Os2Ru and corresponding Os-3 species. The structures reveal that coordination of the Lewis bases occurs exclusively at the ruthenium site of [Os2Ru(CO)(12)], which is in agreement with density functional theory (DFT) calculations on several structural isomers of these compounds. According to the time-dependent DFT results, the lowest optically accessible excited state of [Os2Ru(CO)(10)(iPr-AcPy)] has a prevailing sigma(Ru-Os-2)pi*(iPr-AcPy) character, with a partial sigma sigma*(Ru-Os-2) contribution. In weakly coordinating 2-chlorobutane, the excited state has a lifetime tau = 10.4 +/- 1.2 ps and produces biradicals considerably faster than observed for [Os-3(CO)10(iPr-AcPy) (tau = 25.3 +/- 0.7ps)]. In coordinating acetonitrile, the excited state of [Os2Ru(CO)(10)(iPr-AcPy)] decays mono-exponentially with a lifetime tau = 2.1 +/- 0.2 ps. In contrast to [Os-3(CO)(10)(iPr-AcPy)] that forms biradicals as the main primary photoproduct even in strongly coordinating solvents, zwitterion formation from the solvated lowest excited state is observed for the heterometallic cluster. This is concluded from time-resolved absorption studies in the microsecond time domain. Due to the lower tendency of the coordinatively unsaturated Ru+(CO)(2)(iPr-AcPy-/0) moiety to bind a Lewis base, the heteronuclear biradical and zwitterionic photoproducts live significantly shorter than their triosmium counterparts. The influence of the weaker Os-2-Ru(iPr-AcPy) bond on the redox reactivity is clearly reflected in very reactive radical anions formed upon electrochemical reduction of [Os2Ru(CO)(10)(iPr-AcPy)]. The dimer [-OS(CO)(4)-Os(CO)(4)-Ru(CO)(2)(iPr-AcPy)](2)(2-) is the only IR-detectable intermediate reduction product. The dinuclear complex [Os-2(CO)(8)](2-) and insoluble [Ru(CO)(2)(iPr-AcPy)](n), are the ultimate reduction products, proving fragmentation of the OS2Ru core.

Marked influence of the bridging carbonyl ligands on the photo- and electrochemistry of the clusters [Ru-3(CO)(8)(mu-CO)(2)-(alpha-diimine)] (alpha-diimine = 2,2 '-bipyridine, 4,4 '-dimethyl-2,2 '-bipyridine and 2,2 '-bipyrimidine)

Bonding, photochemical and electrochemical properties of the clusters [Ru-3(CO)(8)(mu-CO)(2)(alpha-diimine)] (alpha-diimine=2,2'-bipyridine (1), 4,4'-dimethyl-2,2'-bipyridine (2) and 2,2'-bipyrimidine (3)) are strongly influenced by the presence of bridging carbonyl ligands. Irradiation at 471 nm initially results in the population of a sigma(Ru-3)pi*(alpha-diimine) excited state. From this state, fast decay takes place to the optically hardly directly accessible pi(Ru/mu-CO) pi*(alpha-diimine) lowest excited state. These assignments agree with theoretical (TD-DFT) results, resonance Raman and picosecond time-resolved infrared spectra. The involvement of the bridging carbonyl ligands in the electron transfer increases the energetic barrier for the formation of open-structure photoproducts such as biradicals and zwitterions. Zwitterions were therefore only obtained in strongly coordinating media such as pyridine at 250 K. The bridging carbonyl ligands also stabilize the radical anions produced upon one-electron reduction of the clusters [Ru-3(CO)(8)(mu-CO)(2)(alpha-diimine)] and observed with cyclic voltammetry, EPR and IR spectroelectrochemistry (for alpha-diimine=2,2'-bipyrimidine). In contrast, open-triangle intermediates formed along the reduction path to [Ru(CO)(2)(alpha-diimine)](n) and [Ru-2(CO)(8)](2-) are more reactive than their triosmium analogues.

Case study part 2: probabilistic modelling of long-term effects of pesticides on individual breeding success in birds and mammals

Abstract: Long-term exposure of skylarks to a fictitious insecticide and of wood mice to a fictitious fungicide were modelled probabilistically in a Monte Carlo simulation. Within the same simulation the consequences of exposure to pesticides on reproductive success were modelled using the toxicity-exposure-linking rules developed by R.S. Bennet et al. (2005) and the interspecies extrapolation factors suggested by R. Luttik et al.(2005). We built models to reflect a range of scenarios and as a result were able to show how exposure to pesticide might alter the number of individuals engaged in any given phase of the breeding cycle at any given time and predict the numbers of new adults at the season’s end.

Individual differences in the effects of perceived controllability on pain perception: critical role of the prefrontal cortex

The degree to which perceived controllability alters the way a stressor is experienced varies greatly among individuals. We used functional magnetic resonance imaging to examine the neural activation associated with individual differences in the impact of perceived controllability on self-reported pain perception. Subjects with greater activation in response to uncontrollable (UC) rather than controllable (C) pain in the pregenual anterior cingulate cortex (pACC), periaqueductal gray (PAG), and posterior insula/SII reported higher levels of pain during the UC versus C conditions. Conversely, subjects with greater activation in the ventral lateral prefrontal cortex (VLPFC) in anticipation of pain in the UC versus C conditions reported less pain in response to UC versus C pain. Activation in the VLPFC was significantly correlated with the acceptance and denial subscales of the COPE inventory [Carver, C. S., Scheier, M. F., & Weintraub, J. K. Assessing coping strategies: A theoretically based approach. Journal of Personality and Social Psychology, 56, 267–283, 1989], supporting the interpretation that this anticipatory activation was associated with an attempt to cope with the emotional impact of uncontrollable pain. A regression model containing the two prefrontal clusters (VLPFC and pACC) predicted 64% of the variance in pain rating difference, with activation in the two additional regions (PAG and insula/SII) predicting almost no additional variance. In addition to supporting the conclusion that the impact of perceived controllability on pain perception varies highly between individuals, these findings suggest that these effects are primarily top-down, driven by processes in regions of the prefrontal cortex previously associated with cognitive modulation of pain and emotion regulation.

Individual Differences in Amygdala and Ventromedial Prefrontal Cortex Activity are Associated with Evaluation Speed and Psychological Well-being

Using functional magnetic resonance imaging, we examined whether individual differences in amygdala activation in response to negative relative to neutral information are related to differences in the speed with which such information is evaluated, the extent to which such differences are associated with medial prefrontal cortex function, and their relationship with measures of trait anxiety and psychological well-being (PWB). Results indicated that faster judgments of negative relative to neutral information were associated with increased left and right amygdala activation. In the prefrontal cortex, faster judgment time was associated with relative decreased activation in a cluster in the ventral anterior cingulate cortex (ACC, BA 24). Furthermore, people who were slower to evaluate negative versus neutral information reported higher PWB. Importantly, higher PWB was strongly associated with increased activation in the ventral ACC for negative relative to neutral information. Individual differences in trait anxiety did not predict variation in judgment time or in amygdala or ventral ACC activity. These findings suggest that people high in PWB effectively recruit the ventral ACC when confronted with potentially aversive stimuli, manifest reduced activity in subcortical regions such as the amygdala, and appraise such information as less salient as reflected in slower evaluative speed.

Ab initio and tight-binding calculations of noncollinear magnetism in manganese clusters

Combining ab initio and tight-binding calculations, we have studied the noncollinear magnetism in manganese clusters. The oscillations in the per-atom moments observed experimentally are reproduced theoretically. The tendency of antiferromagnetic coupling between near neighbors leads to noncollinear coupling between atoms within the clusters. For clusters containing 12, 13, 15, 19, and 23 atoms, the geometrical structures were optimized from ab initio calculations with collinear coupled spin moments among different atomic sites. For larger clusters such as Mn-36 and Mn-55, the geometries are taken as portions of an fcc structure. Although the local atomic moments have high values close to 4 mu(B), the net moments lie in the range of 0.4-1.2 mu(B)/atom. Taking the noncollinear coupling into account brings the calculated magnetic moments much closer to the experimental results.

Early social experience and individual differences in infants' joint attention

Fifty-nine healthy infants were filmed with their mothers and with a researcher at two, four, six and nine months in face-to-face play, and in toy-play at six and nine months. During toy-play at both ages, two indices of joint attention (JA)—infant bids for attention, and percent of time in shared attention—were assessed, along with other behavioural measures. Global ratings were made at all four ages of infants’ and mothers’ interactive style. The mothers varied in psychiatric history (e.g., half had experienced postpartum depression) and socioeconomic status, so their interactive styles were diverse. Variation in nine-month infant JA — with mother and with researcher — was predicted by variation in maternal behaviour and global ratings at six months, but not at two or four months. Concurrent adult behaviour also influenced nine-month JA, independent of infant ratings. Six-month maternal behaviours that positively predicted later JA (some of which remained important at nine months) included teaching, conjoint action on a toy, and global sensitivity. Other behaviours (e.g., entertaining) negatively predicted later JA. Findings are discussed in terms of social-learning and neurobiological accounts of JA emergence.

Developmental changes in the germinability, desiccation tolerance, hardseededness, and longevity of individual seeds of Trifolium ambiguum

Background and Aims: Using two parental clones of outcrossing Trifolium ambiguum as a potential model system, we examined how during seed development the maternal parent, number of seeds per pod, seed position within the pod, and pod position within the inflorescence influenced individual seed fresh weight, dry weight, water content, germinability, desiccation tolerance, hardseededness, and subsequent longevity of individual seeds. Methods: Near simultaneous, manual reciprocal crosses were carried out between clonal lines for two experiments. Infructescences were harvested at intervals during seed development. Each individual seed was weighed and then used to determine dry weight or one of the physiological behaviour traits. Key Results: Whilst population mass maturity was reached at 33–36 days after pollination (DAP), seed-to-seed variation in maximum seed dry weight, when it was achieved, and when maturation drying commenced, was considerable. Individual seeds acquired germinability between 14 and 44 DAP, desiccation tolerance between 30 and 40 DAP, and the capability to become hardseeded between 30 and 47 DAP. The time for viability to fall to 50 % (p50) at 60 % relative humidity and 45 °C increased between 36 and 56 DAP, when the seed coats of most individuals had become dark orange, but declined thereafter. Individual seed f. wt at harvest did not correlate with air-dry storage survival period. Analysing survival data for cohorts of seeds reduced the standard deviation of the normal distribution of seed deaths in time, but no sub-population showed complete uniformity of survival period. Conclusions: Variation in individual seed behaviours within a developing population is inherent and inevitable. In this outbreeder, there is significant variation in seed longevity which appears dependent on embryo genotype with little effect of maternal genotype or architectural factors.

Initial results from Phase 2 of the international urban energy balance model comparison

Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an international comparison project to evaluate 32 urban land surface schemes are presented. This is the first large-scale systematic evaluation of these models. In four stages, participants were given increasingly detailed information about an urban site for which urban fluxes were directly observed. At each stage, each group returned their models' calculated surface energy balance fluxes. Wide variations are evident in the performance of the models for individual fluxes. No individual model performs best for all fluxes. Providing additional information about the surface generally results in better performance. However, there is clear evidence that poor choice of parameter values can cause a large drop in performance for models that otherwise perform well. As many models do not perform well across all fluxes, there is need for caution in their application, and users should be aware of the implications for applications and decision making.