Naresuan University Journal
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Striatal and midbrain connectivity with the hippocampus selectively boosts memory for contextual novelty
No full textThe role of contextual expectation in processing familiar and novel stimuli was investigated in a series of experiments combining eye tracking, functional magnetic resonance imaging, and behavioral methods. An experimental paradigm emphasizing either familiarity or novelty detection at retrieval was used. The detection of unexpected familiar and novel stimuli, which were characterized by lower probability, engaged activity in midbrain and striatal structures. Specifically, detecting unexpected novel stimuli, relative to expected novel stimuli, produced greater activity in the substantia nigra/ventral tegmental area (SN/VTA), whereas the detection of unexpected familiar, relative to expected, familiar stimuli, elicited activity in the striatum/globus pallidus (GP). An effective connectivity analysis showed greater functional coupling between these two seed areas (GP and SN/VTA) and the hippocampus, for unexpected than for expected stimuli. Within this network of midbrain/striatal–hippocampal interactions two pathways are apparent; the direct SN–hippocampal pathway sensitive to unexpected novelty and the perirhinal–GP–hippocampal pathway sensitive to unexpected familiarity. In addition, increased eye fixations and pupil dilations also accompanied the detection of unexpected relative to expected familiar and novel stimuli, reflecting autonomic activity triggered by the functioning of these two pathways. Finally, subsequent memory for unexpected, relative to expected, familiar, and novel stimuli was characterized by enhanced recollection, but not familiarity, accuracy. Taken together, these findings suggest that a hippocampal–midbrain network, characterized by two distinct pathways, mediates encoding facilitation and most critically, that this facilitation is driven by contextual novelty, rather than by the absolute novelty of a stimulus. This contextually sensitive neural mechanism appears to elicit increased exploratory behavior, leading subsequently to greater recollection of the unexpected stimulus
People Like Us Don’t Have Babies.’ Learning Disability, Prospective Parenthood and Legal Transformations
No full textStructural Break Inference using Information Criteria in Models Estimated by Two Stage Least Squares
No full textThis paper makes two contributions in relation to the use of information criteria for inference on structural breaks when the coefficients of a linear model with endogenous regressors may experience multiple changes. Firstly, we show that suitably defined information criteria yield consistent estimators of the number of breaks, when employed in the second stage of a two-stage least squares (2SLS) procedure with breaks in the reduced form taken into account in the first stage. Secondly, a Monte Carlo analysis investigates the finite sample performance of a range of criteria based on BIC, HQIC and AIC for equations estimated by 2SLS. Versions of the consistent criteria BIC and HQIC perform well overall when the penalty term weights estimation of each break point more heavily than estimation of each coefficient, while AIC is inconsistent and badly over-estimates the number of true breaks
Butyrolactone signalling circuits for synthetic biology
No full textSignalling circuits based on quorum sensing mechanisms have been popular tools for synthetic biology. Recent advances in our understanding of the analogous systems regulating antibiotics production in soil bacteria suggest that these might provide useful complementary tools to increase the complexity of possible circuit designs. Here we discuss the diversity of these natural circuits, which use γ-butyrolactones (GBLs) as their main inter-cellular signal, highlighting the range of new building blocks they could provide, as well as a number of exciting recent applications of GBL-based circuits in heterologous systems. We conclude by presenting examples of the novel circuit complexity that could become accessible through the use of GBL-based designs
Neuroinflammation in schizophrenia and effects of antipsychotic medication - a PET study.
No full textSchizophrenia is thought to be associated with inflammation [1]. Microglial activation, a measure of neuroinflammation, can be quantified using PET ligands specific for the 18kDa translocator protein (TSPO) which is overexpressed by activated microglia. Initial PET studies [2,3] indicate the presence of microglial activation in schizophrenia but these studies might be confounded by medication effects. We present preliminary findings from a study investigating neuroinflammation in both medicated and unmedicated schizophrenic patients.Ten patients with schizophrenia and ten matched controls underwent a PET scan with TSPO tracer [11C](R)-PK11195 using the High Resolution Research Tomograph (HRRT). A grey matter cerebellum input function was used to generate parametric maps of BPND using the simplified reference tissue method [4]. Of the 10 patients, 7 were antipsychotic-free (>= 3 months) and 3 were receiving antipsychotic medication (risperidone long-acting injection).Globally, cortical BPND was higher in schizophrenia patients compared to controls, with a significant main effect of group (p <0.001) across 7 cortical ROIs. Post-hoc t-tests showed significantly higher binding in the anterior cingulate (p=0.002) in patients. On subgroup analysis, mean cortical BPND values were higher in medicated compared to antipsychotic-free patients (p=0.001). Globally, BPND did not differ between antipsychotic-free patients and healthy controls (p=0.208). However, the increased binding in the anterior cingulate remained significant (p=0.012).The increased microglial activation inpatients seems to be being driven by the subgroup of medicated patients. However, when comparing antipsychotic-free patients with controls, increased microglial activation is present in the anterior cingulate, suggesting that this focal neuroinflammation may be disease-related as opposed to medication-related.References[1] Potvin S, Stip E, Sepehry AA, Gendron A, Bah R, Kouassi E (2008): Inflammatory cytokine alterations in schizophrenia: A systematic quantitative review. Biological Psychiatry. 63: 801–808.[2] van Berckel BN, Bossong MG, Boellaard R, Kloet R, Schuitemaker A, Caspers E, et al. (2008): Microglia Activation in Recent-Onset Schizophrenia: A Quantitative (R)-C-11 PK11195 Positron Emission Tomography Study. Biological Psychiatry. 64: 820–822.[3] Doorduin J, de Vries EFJ, Willemsen ATM, de Groot JC, Dierckx RA, Klein HC (2009): Neuroinflammation in Schizophrenia-Related Psy-chosis: A PET Study. Journal of Nuclear Medicine. 50: 1801–1807.[4] Lammertsma AA, Hume SP (1996): Simplified reference tissue model for PET receptor studies. Neuroimage. 4: 153–158
Acquisition of second language grammar under incidental learning conditions: the role of frequency and working memory
No full textAlthough frequency is recognized as an important factor in second language (L2) acquisition, it has remained relatively underinvestigated in terms of its impact on the acquisition of grammatical knowledge under incidental learning conditions. This article reports the results of an experiment where 100 novice adult learners were exposed to a complex noun–adjective agreement pattern in Russian under four incidental learning conditions in which type and token frequencies of the stimuli were manipulated. The results show that accuracy was greater in the low type/low token condition and that low token frequency played a more significant role than low type frequency, supporting a “starting small” approach for productive knowledge acquisition. Working memory was differentially involved in production of acquired knowledge in different conditions and not engaged when learning was facilitated by frequency
Arenas of Service and the Development of the Hindu Nationalist Subject in India
No full textThe study of the relationship between Hindu nationalism and Hindu activist traditions of seva (selfless service) has been principally organised into three approaches: firstly, the instrumentalist deployment of the practice, secondly, the political appropriation of traditions of seva, and thirdly, that these related associational spaces are internally homogenous and distinct from alternative ‘legitimate’ religious arenas. These frameworks largely reflect approaches to Hindu nationalism which place emphasis on its forms of political statecraft and relationship to spectacular violence. These approaches raise manifold concerns.This thesis retheorizes the relationship between Hindu nationalism and seva with reference to primary and secondary sources, together with field research in the seva projects of the Vanavasi Kalyan Kendra (VKK), a Hindu nationalist association. Through deploying a reworked understanding of Fraser’s (1990) approach to associational space and Butler’s (1993, 2007) theorisation of performative acts and subject formation, this thesis contributes to rethinking Hindu nationalism and seva. I demonstrate firstly that the colonial encounter worked to produce a series of social imaginaries which were drawn upon to transform traditions of seva. Through their articulation in shared religious languages, practices of seva were productive of porously structured Hindu activist spaces in which the tradition was contested with regard to ‘radical’ and ‘orthodox’ orientations to Hinduism’s boundaries. Increasingly, articulations of seva which invoked a sangathanist ‘orthodoxy’ came to gain hegemony in Hindu activist arenas. This influenced the early and irregular Hindu nationalist practices of seva. Fractures in Hindu nationalist articulations developed as a result of the Rashtriya Swayamsevak Sangh’s (RSS) sangathanist organisational idioms, allowing the association to inscribe its practices with pro-active meanings. In the post-independence period the alternative arenas of Hindu nationalist seva projects expanded greatly, a point evident in the degrees of dialogue between the Sangh and the sarvodaya movement. The importance of porous associational boundaries is further demonstrated through noting how engagement in visibilized arenas of popular Hindu religiosity worked to both broaden the fields of reference and vernacularize Hindu nationalist practices of seva. With reference to field research, I demonstrate that central to the expansion of the VKK’s arenas of service into spaces associated with Ayurvedic care is the incorporation of both refocused and transgressive practices. In the educational projects of the VKK, I note how seva works to inscribe daily practices of hygiene, the singing of bhajans and daily assemblies with Hindu nationalist meanings, and so works to regulate conduct through the formation of an ‘ethical Hindu self’. However, arenas of seva are also a location where we can witness subjects negotiating power. I demonstrate this through examining how participants in the VKK’s rural development projects rearticulate Othering practices of seva, with actors using the discourse to position themselves as active subjects, break gendered restrictions on public space, and advance an ‘ethically Hindu’ grounded claim on development and critique of power.This work illustrates that far from being of inconsequence to the circulation of Hindu nationalist identities, alternative arenas of seva operate as spaces where discourses are performatively enacted, refocused, transgressed and rearticulated. These acts contribute to the consolidation and disturbance of Hindu nationalist subject formations
An incompressible SPH scheme with improved pressure predictions for free-surface generalised Newtonian flows
No full textNon-Newtonian flows are of great scientific interest due to their distinctive rheological behaviour. Free-surface non-Newtonian flows are encountered in many environmental and industrial applications, such as mud flows and moulding flows. Smoothed particle hydrodynamics (SPH) is an excellent technique for describing free-surface flows, but traditionally suffers from an inaccurate pressure field. The diffusion-based incompressible SPH (ISPH) method which was first introduced by Lind et al. (2012), following the original shifting methodology of Xu et al. (2009), combines the benefits of the SPH methodology with a virtually noise-free pressure field. In this work the diffusion-based ISPH method is extended to solve inelastic non-Newtonian flows, introducing standard viscosity calculation techniques for the non-Newtonian fluids and adopting a new viscous term which is more suitable for the calculation of such flows. The new approach is validated against internal flows and free-surface flows by comparing with analytical and experimental results respectively. Furthermore, comparisons with other computational techniques were conducted and showed that in addition to the accurate prediction of free-surface flows, the proposed methodology can significantly improve the prediction of the pressure field. ? 2015 Elsevier B.V
