A STIS Survey for OVI Absorption Systems at 0.12 < z < 0.5 I.: The Statistical Properties of Ionized Gas

We have conducted a systematic survey for intervening OVI absorbers in available echelle spectra of 16 QSOs at z_QSO = 0.17-0.57. These spectra were obtained using HST/STIS with the E140M grating. Our search uncovered a total of 27 foreground OVI absorbers with rest-frame absorption equivalent width W_r(1031) > 25mA. Ten of these QSOs exhibit strong OVI absorbers in their vicinity. Our OVI survey does not require the known presence of Lya, and the echelle resolution allows us to identify the OVI absorption doublet based on their common line centroid and known flux ratio. We estimate the total redshift survey path, \Delta z, using a series of Monte-Carlo simulations, and find that \Delta z=1.66, 2.18, and 2.42 for absorbers of strength W_r = 30, 50 and 80mA, respectively, leading to a number density of dN(W > 50mA)/dz = 6.7 +/- 1.7 and dN(W > 30mA)/dz = 10.4 +/- 2.2. In contrast, we also measure dN/dz = 27 +/- 9 for OVI absorbers of W_r > 50mA at |\Delta v|< 5000 kms from the background QSOs. Using the random sample of OVI absorbers with well characterized survey completeness, we estimate a mean cosmological mass density of the OVI gas \Omega(OVI)h = 1.7 +/- 0.3 x 10^-7. In addition, we show that <5% of OVI absorbers originate in underdense regions that do not show a significant trace of HI. Furthermore, we show that the neutral gas column N(HI) associated with these OVI absorbers spans nearly five orders of magnitude, and show moderate correlation with N(OVI). Finally, while the number density of OVI absorbers varies substantially from one sightline to another, it also appears to be inversely correlated with the number density of HI absorbers along individual lines of sight.Comment: 12 pages. ApJ accepte

Granule Cell Dispersion in Human Temporal Lobe Epilepsy: Proteomics investigation of neurodevelopmental migratory pathways

Granule cell dispersion (GCD) is a common pathological feature observed in the hippocampus of patients with Mesial Temporal Lobe Epilepsy (MTLE). Pathomechanisms underlying GCD remain to be elucidated, but one hypothesis proposes aberrant reactivation of neurodevelopmental migratory pathways, possibly triggered by febrile seizures. This study aims to compare the proteomes of basal and dispersed granule cells in the hippocampus of eight MTLE patients with GCD to identify proteins that may mediate GCD in MTLE. Quantitative proteomics identified 1882 proteins, of which 29% were found in basal granule cells only, 17% in dispersed only and 54% in both samples. Bioinformatics analyses revealed upregulated proteins in dispersed samples were involved in developmental cellular migratory processes, including cytoskeletal remodelling, axon guidance and signalling by Ras homologous (Rho) family of GTPases (P<0.01). The expression of two Rho GTPases, RhoA and Rac1, was subsequently explored in immunohistochemical and in situ hybridisation studies involving eighteen MTLE cases with or without GCD, and three normal post mortem cases. In cases with GCD, most dispersed granule cells in the outer-granular and molecular layers have an elongated soma and bipolar processes, with intense RhoA immunolabelling at opposite poles of the cell soma, while most granule cells in the basal granule cell layer were devoid of RhoA. A higher density and percentage of cells expressing RhoA was observed in cases with GCD than without GCD (P<0.004). In GCD cases, the density and percentage of cells expressing RhoA was significantly higher in the inner molecular layer than granule cell layer (P<0.026), supporting proteomic findings. In situ hybridisation studies using probes against RHOA and RAC1 mRNAs revealed fine peri- and nuclear puncta in granule cells of all cases. The density of cells expressing RHOA mRNAs were significantly higher in the inner molecular layer of cases with GCD than without GCD(P=0.05). In summary, our study has found limited evidence for ongoing adult neurogenesis in the hippocampus of patients with MTLE, but evidence of differential dysmaturation between dispersed and basal granule cells has been demonstrated, and elevated expression of Rho GTPases in dispersed granule cells may contribute to the pathomechanisms underpinning GCD in MTLE

Observation and inverse problems in coupled cell networks

A coupled cell network is a model for many situations such as food webs in ecosystems, cellular metabolism, economical networks... It consists in a directed graph $G$, each node (or cell) representing an agent of the network and each directed arrow representing which agent acts on which one. It yields a system of differential equations $\dot x(t)=f(x(t))$, where the component $i$ of $f$ depends only on the cells $x_j(t)$ for which the arrow $j\rightarrow i$ exists in $G$. In this paper, we investigate the observation problems in coupled cell networks: can one deduce the behaviour of the whole network (oscillations, stabilisation etc.) by observing only one of the cells? We show that the natural observation properties holds for almost all the interactions $f$

Minimising biases in Full Configuration Interaction Quantum Monte Carlo

We show that Full Configuration Interaction Quantum Monte Carlo (FCIQMC) is a Markov Chain in its present form. We construct the Markov matrix of FCIQMC for a two determinant system and hence compute the stationary distribution. These solutions are used to quantify the dependence of the population dynamics on the parameters defining the Markov chain. Despite the simplicity of a system with only two determinants, it still reveals a population control bias inherent to the FCIQMC algorithm. We investigate the effect of simulation parameters on the population control bias for the neon atom and suggest simulation setups to in general minimise the bias. We show a reweighting scheme to remove the bias caused by population control commonly used in Diffusion Monte Carlo [J. Chem. Phys. 99, 2865 (1993)] is effective and recommend its use as a post processing step.Comment: Supplementary material available as 'Ancillary Files

The role of training in IBA implementation beyond primary health care settings in the UK

There has been a considerable drive to encourage a wide range of professional groups to incorporate alcohol screening (or identification) and brief advice (IBA) into their everyday practice. This article aims to examine the role of training in promoting IBA delivery in contexts outside primary care and other health settings. The data are drawn mainly from a structured online survey supplemented by illustrative material from nine qualitative interviews and insights from an expert workshop. Findings support the results from other research that issues relating to role relevance and role security continue to act as barriers to professional change. Furthermore, issues of organisational commitment and organisational barriers are insufficiently addressed in strategy to promote wider use of IBA. The article concludes that development of appropriate training for alcohol IBA needs to take account of the role of IBA within a complex interactive system of related services and help seeking pathways and consider how training can contribute to changing both professional attitudes and behaviours and organisational approaches to implementing and sustaining IBA in everyday professional practice

Delivering alcohol IBA: is there a case for mainstreaming? Insights from an expert workshop and from the published literature

Identification and brief advice (IBA) has been widely advocated as a cost effective intervention to address problem drinking. Evidence for the effectiveness of IBA comes largely from primary care studies. Research in pharmacies, educational settings and criminal justice settings has indicated the possibilities for successful delivery of IBA but there is little solid evidence to support mainstreaming IBA beyond core medical facilities. Furthermore, even in primary health care settings there are continuing difficulties around implementing IBA (see: Thom et al., 2014) and continuing debate about the research findings (Heather, 2014). A number of key questions around the drive towards wider implementation of IBA were debated at an expert workshop in Birmingham in November 2014. The questions debated were: 1. What are the challenges and barriers to broadening the contexts in which alcohol IBA is delivered? 2. How can these challenges and barriers be addressed? 3. Should delivery of alcohol IBA in wider contexts (mainstreaming) be a policy goal? This monograph provides insights from this expert workshop and from the published literature on theses questions

Hippocampus and Human Disease

This chapter focuses on two disorders in which the role of the hippocampus has been extensively investigated: Alzheimer's disease and temporal lobe epilepsy. Although in Alzheimer's disease the disease eventually results in widespread destruction of the cerebral cortex, the damage in the earliest stages of disease is restricted to the entorhinal cortex and the hippocampus, and the memory impairment that results from this disruption of the hippocampal formation represents one of the common characteristics of early onset Alzheimer's disease. In temporal lobe epilepsy, the pathological damage is often restricted to the hippocampus in the form of hippocampal sclerosis. However, unlike Alzheimer's disease, in which the hippocampal damage is secondary to the underlying pathological process, the hippocampus in temporal lobe epilepsy is not only sensitive to damage by seizure activity but can also act as the substrate for epileptic seizure generation

Crowding in Peripheral Vision: Why Bigger Is Better

SummaryWe enjoy the illusion that visual resolution is high across the entire field of vision. However, this illusion can be easily dispelled by trying to identify objects in a cluttered environment out of the corner of your eye. This reflects, in part, the well-known decline in visual resolution in peripheral vision; however, the main bottleneck for reading or object recognition in peripheral vision is crowding. Objects that can be easily identified in isolation seem indistinct and jumbled in clutter. Crowding is thought to reflect inappropriate integration of the target and flankers in peripheral vision [1, 2]. Here, we uncover and explain a paradox in peripheral crowding: under certain conditions, increasing the size or number of flanking rings results in a paradoxical decrease in the magnitude of crowding—i.e., the bigger or more numerous the flanks, the smaller the crowding. These surprising results are predicted by a model in which crowding is determined by the centroids of ≈4–8 independent features within ≈0.5× the target eccentricity. These features are then integrated into a texture beyond the stage of feature analysis. We speculate that this process may contribute to the illusion of high resolution across the field of vision