858 research outputs found

    Presence and task performance:an approach in the light of cognitive style

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    The paper highlights the relationship between each of four bi-polar dimensions of personality cognitive style, such as extraversion–introversion, sensing–intuition, thinking–feeling and judging–perceiving, and the level of sense of presence experienced. Findings indicate that individuals who are more sensitive, more feeling or more introverted experience a higher level of presence. While not reaching statistical significance, differing cognitive styles appear to impact on task performance. The apparent negative relationship discovered between sense of presence and task performance should be considered in the light of task characteristics. We discuss the implications of these findings and how they contribute to an understanding of the complex relationship that exists between presence and task performance and how this subsequently ought to influence the design of virtual environments

    Heteroleptic Calcium Complexes Supported by a Phenoxy-Imine NON Ligand: Polymerization of Cyclic Esters by a Ligand-Assisted, Activated-Monomer Mechanism

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    Phenoxy-imine NON pro-ligands HR,DippL [1-OH-2,6-(HCNDipp)-4-R-C6H2, where R = H, Me, or t Bu] were deprotonated using KH to afford the corresponding potassium salts R,DippLK·thf x [R = H (1·thf x ), Me (2·thf x ), and t Bu (3·thf x )]. The addition of crown ether (18-c-6) to these salts allowed for the structures of the resulting adducts to be elucidated in the solid state: [1­(18-c-6)] n , [2­(18-c-6)] n , and [3­(18-c-6)­(thf)]. The derivatives with the smaller para-substituents were found to be 1D coordination polymers stabilized by unusual non-covalent interactions between the diisopropyl-methyl groups and the potassium center. Heteroleptic calcium complexes R,DippLCaI­(thf)3 [R = H (4), Me (5), and t Bu (6)] were prepared by the salt metathesis reaction of 1–3·thf x with CaI2. Complexes 4–6 were evaluated as initiators for the ring-opening polymerization of lactide monomers and were all found to be active; the addition of benzyl alcohol resulted in large rate increases, e.g., ∼12-fold difference for 6 (0.70 vs 0.06 h–1). The propagation rate constants were found to lie within the range 88–135 M–1 h–1. Variation of co-initiator concentration revealed only a fractional dependence; this agrees with the other experimental observations, which suggest that the heteroleptic catalysts work via a “ligand-assisted, activated monomer” mechanism

    Axion minivoids and implications for direct detection

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    In the scenario in which QCD axion dark matter is produced after inflation, the Universe is populated by large inhomogeneities on very small scales. Eventually, these fluctuations will collapse gravitationally to form dense axion miniclusters that trap up to ∼75% of the dark matter within asteroid-mass clumps. Axion miniclusters are physically tiny however, so haloscope experiments searching for axions directly on Earth are much more likely to be probing “minivoids”—the space in between miniclusters. This scenario seems like it ought to spell doom for haloscopes, but while these minivoids might be underdense, they are not totally devoid of axions. Using Schrödinger-Poisson and N-body simulations to evolve from realistic initial field configurations, we quantify the extent to which the local ambient dark matter density is suppressed in the postinflationary scenario. We find that a typical experimental measurement will sample an axion density that is only around 10% of the expected galactic dark matter density. Our results are taken as conservative estimates and have implications for experimental campaigns lasting longer than a few years, as well as broadband haloscopes that have sensitivity to transient signatures. We show that for a Oð(year)-long integration times, the measured dark matter density should be expected to vary by 20%–30%

    A systematic review of the literature on community-level child protection in low- and middle-income countries

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    This systematic review synthesizes the current state of literature on community-level child protection in LMICs. The aim of the review is to present available evidence and effective strategies that implementing agencies can use to support community-level structures, practices, resources and processes. Multiple database searches were conducted, using search terms to capture community-level approaches to child protection in LMICs. The search identified 1,549 unique published articles and 1,745 grey literature resources. After a screening process based on pre-defined inclusion and exclusion criteria, 38 published articles and 204 grey literature resources were analyzed. The review highlights (1) a practice-research gap related to community-level approaches generally and more specifically in humanitarian settings; (2) the important role of different socio-ecological levels when implementing community-level interventions; and (3) a number of recommended strategies that implementing agencies can adopt in their work, such as ensuring ownership at community level increasing the potential of sustainability of an approach; linking with existing processes and structures; being inclusive in the approach; and carefully negotiating possible tension between traditional mechanisms and rights-based frameworks. Further studies, with a focus on outcomes for children, families and communities, are needed to broaden the current evidence-base and research on the applicability and effectiveness of community-level approaches in humanitarian settings is recommended to steer implementation in the sector

    Government revenue, quality of governance and child and maternal survival

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    This paper considers the effect of government revenue and the quality of governance on the under-five and maternal survival rates. A non-linear panel data study was undertaken using annual data for every country in the world. The study’s broad conclusion is that while government resources, measured as total revenue received by a country’s government, is essential, the quality of governance is even more critical in determining a good outcome for both mother and child.The Prof Sonia Buist Global Child Health Research Fund; Scottish Funding Council.https://www.tandfonline.com/loi/rael20hj2022Economic

    A survey of agent-oriented methodologies

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    This article introduces the current agent-oriented methodologies. It discusses what approaches have been followed (mainly extending existing object oriented and knowledge engineering methodologies), the suitability of these approaches for agent modelling, and some conclusions drawn from the survey

    Studying the effects of thalamic interneurons in a thalamocortical neural mass model

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    Neural mass models of the thalamocortical circuitry are often used to mimic brain activity during sleep and wakefulness as observed in scalp electroencephalogram (EEG) signals [1]. It is understood that alpha rhythms (8-13 Hz) dominate the EEG power-spectra in the resting-state [2] as well as the period immediately before sleep [3]. Literature review shows that the thalamic interneurons (IN) are often ignored in thalamocortical population models; the emphasis is on the connections between the thalamo cortical relay (TCR) and the thalamic reticular nucleus (TRN). In this work, we look into the effects of the IN cell population on the behaviour of an existing thalamocortical model containing the TCR and TRN cell populations [4]. A schematic of the extended model used in this work is shown in Fig.1. The model equations are solved in Matlab using the Runge-Kutta method of the 4th/5th order. The model shows high sensitivity to the forward and reverse rates of reactions during synaptic transmission as well as on the membrane conductance of the cell populations. The input to the model is a white noise signal simulating conditions of resting state with eyes closed, a condition well known to be associated with dominant alpha band oscillations in EEG e.g. [5]. Thus, the model parameters are calibrated to obtain a set of basal parameter values when the model oscillates with a dominant frequency within the alpha band. The time series plots and the power spectra of the model output are compared with those when the IN cell population is disconnected from the circuit (by setting the inhibitory connectivity parameter from the IN to the TCR to zero). We observe (Fig. 2 inset) a significant difference in time series output of the TRN cell population with and without the IN cell population in the model; this in spite of the IN having no direct connectivity to and from the TRN cell population (Fig. 1). A comparison of the power spectra behaviour of the model output within the delta (1-3.5Hz), theta (3.75-7.5Hz), alpha (7.75-13.5Hz) and beta (13.75-30.5Hz) bands is shown in Fig. 2. Disconnecting the IN cell population shows a significant drop in the alpha band power and the dominant frequency of oscillation now lies within the theta band. An overall ‘slowing’ (left-side shift) of the power spectra is observed with an increase within the delta and theta bands and a decrease in the alpha and beta bands. Such a slowing of EEG is a signature of slow wave sleep in healthy individuals, and this suggests that the IN cell population may be centrally involved in the phase transition to slow wave sleep [6]. It is also characteristic of the waking EEG in Alzheimer’s disease, and may help us to understand the role of the IN cell population in modulating TCR and TRN cell behaviour in pathological brain conditions

    The impact of training non-physician clinicians in Malawi on maternal and perinatal mortality : a cluster randomised controlled evaluation of the enhancing training and appropriate technologies for mothers and babies in Africa (ETATMBA) project

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    Background: Maternal mortality in much of sub-Saharan Africa is very high whereas there has been a steady decline in over the past 60 years in Europe. Perinatal mortality is 12 times higher than maternal mortality accounting for about 7 million neonatal deaths; many of these in sub-Saharan countries. Many of these deaths are preventable. Countries, like Malawi, do not have the resources nor highly trained medical specialists using complex technologies within their healthcare system. Much of the burden falls on healthcare staff other than doctors including non-physician clinicians (NPCs) such as clinical officers, midwives and community health-workers. The aim of this trial is to evaluate a project which is training NPCs as advanced leaders by providing them with skills and knowledge in advanced neonatal and obstetric care. Training that will hopefully be cascaded to their colleagues (other NPCs, midwives, nurses). Methods/design: This is a cluster randomised controlled trial with the unit of randomisation being the 14 districts of central and northern Malawi (one large district was divided into two giving an overall total of 15). Eight districts will be randomly allocated the intervention. Within these eight districts 50 NPCs will be selected and will be enrolled on the training programme (the intervention). Primary outcome will be maternal and perinatal (defined as until discharge from health facility) mortality. Data will be harvested from all facilities in both intervention and control districts for the lifetime of the project (3–4 years) and comparisons made. In addition a process evaluation using both quantitative and qualitative (e.g. interviews) will be undertaken to evaluate the intervention implementation. Discussion: Education and training of NPCs is a key to improving healthcare for mothers and babies in countries like Malawi. Some of the challenges faced are discussed as are the potential limitations. It is hoped that the findings from this trial will lead to a sustainable improvement in healthcare and workforce development and training. Trial registration: ISRCTN6329415

    Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management

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    Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems
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