Quick minds don't blink: electrophysiological correlates of individual differences in attentional selection.

A well-established phenomenon in the study of attention is the attentional blink-a deficit in reporting the second of two targets when it occurs 200-500 msec after the first. Although the effect has been shown to be robust in a variety of task conditions, not every individual participant shows the effect. We measured electroencephalographic activity for "nonblinkers" and "blinkers" during execution of a task in which two letters had to be detected in an sequential stream of digit distractors. Nonblinkers showed an earlier P3 peak, suggesting that they are quicker to consolidate information than are blinkers. Differences in frontal selection positivity were also found, such that nonblinkers showed a larger difference between target and distractor activation than did blinkers. Nonblinkers seem to extract target information better than blinkers do, allowing them to reject distractors; more easily and leaving sufficient resources available to report both targets

The UK National Homicide Therapeutic Service: a retrospective naturalistic study among 929 bereaved individuals

Homicidal bereavement puts survivors at risk of developing a broad range of lasting and severe mental health problems. Previous research has often relied on relatively small and homogenous samples. Still, little is known about what factors influence the expression of symptoms following homicidal bereavement. Preventive and curative treatments often do not consider the complex coherence between the emotional, judicial, financial, and societal challenges that likely arise following a homicide. Despite the severity of its consequences on mental health, no gold standard for the preventative and curative treatment of mental health issues in homicide survivors exists. We aimed to introduce a time-limited, traumatic grief-focused outreaching model of care designed specifically for homicide survivors, and to examine its potential effectiveness. Furthermore, we aimed to investigate what factors influence the severity of mental health problems and response to treatment. In the current study, self-reported data on five different outcome measures, namely, symptoms of posttraumatic stress, prolonged grief, depression, anxiety, and functional impairment were available from 929 homicidally bereaved treatment receiving adults. We used Latent Growth Modeling to analyze our repeated measures data and to classify individuals into distinct groups based on individual response patterns. Results showed that the current model of care is likely to be effective in reducing mental health complaints following homicidal bereavement. Having a history of mental illness, being younger of age and female, and having lost either a child or spouse consistently predicted greater symptom severity and functional impairment at baseline. For change in symptom severity and functional impairment during treatment, having a history of mental illness was the only consistent predictor across all outcomes. This study was limited by its reliance on self-reported data and cross-sectional design without a control group. Future prospective, longitudinal research across different cultures is needed in order to replicate the current findings and enhance generalizability. That notwithstanding, findings provide a first step toward evaluating a novel service-delivery approach for homicide survivors and provide further insight in the development of mental health complaints following bereavement by homicide

Stresses in isostatic granular systems and emergence of force chains

Progress is reported on several questions that bedevil understanding of granular systems: (i) are the stress equations elliptic, parabolic or hyperbolic? (ii) how can the often-observed force chains be predicted from a first-principles continuous theory? (iii) How to relate insight from isostatic systems to general packings? Explicit equations are derived for the stress components in two dimensions including the dependence on the local structure. The equations are shown to be hyperbolic and their general solutions, as well as the Green function, are found. It is shown that the solutions give rise to force chains and the explicit dependence of the force chains trajectories and magnitudes on the local geometry is predicted. Direct experimental tests of the predictions are proposed. Finally, a framework is proposed to relate the analysis to non-isostatic and more realistic granular assemblies.Comment: 4 pages, 2 figures, Corrected typos and clkearer text, submitted to Phys. Rev. Let

Exploring the structural diversity in inhibitors of alpha-Synuclein amyloidogenic folding, aggregation, and neurotoxicity

Published: 25 May 2018Aggregation of α-Synuclein (αS) protein to amyloid fibrils is a neuropathological hallmark of Parkinson's disease (PD). Growing evidence suggests that extracellular αS aggregation plays a pivotal role in neurodegeneration found in PD in addition to the intracellular αS aggregates in Lewy bodies (LB). Here, we identified and compared a diverse set of molecules capable of mitigating protein aggregation and exogenous toxicity of αSA53T, a more aggregation-prone αS mutant found in familial PD. For the first time, we investigated the αS anti-amyloid activity of semi-synthetic flavonoid 2′, 3′, 4′ trihydroxyflavone or 2-D08, which was compared with natural flavones myricetin and transilitin, as well as such structurally diverse polyphenols as honokiol and punicalagin. Additionally, two novel synthetic compounds with a dibenzyl imidazolidine scaffold, Compound 1 and Compound 2, were also investigated as they exhibited favorable binding with αSA53T. All seven compounds inhibited αSA53T aggregation as demonstrated by Thioflavin T fluorescence assays, with modified fibril morphology observed by transmission electron microscopy. Ion mobility-mass spectrometry (IM-MS) was used to monitor the structural conversion of native αSA53T into amyloidogenic conformations and all seven compounds preserved the native unfolded conformations of αSA53T following 48 h incubation. The presence of each test compound in a 1:2 molar ratio was also shown to inhibit the neurotoxicity of preincubated αSA53T using phaeochromocytoma (PC12) cell viability assays. Among the seven tested compounds 2-D08, honokiol, and the synthetic Compound 2 demonstrated the highest inhibition of aggregation, coupled with neuroprotection from preincubated αSA53T in vitro. Molecular docking predicted that all compounds bound near the lysine-rich region of the N-terminus of αSA53T, where the flavonoids and honokiol predominantly interacted with Lys 23. Overall, these findings highlight that (i) restricted vicinal trihydroxylation in the flavone B-ring is more effective in stabilizing the native αS conformations, thus blocking amyloidogenic aggregation, than dihydroxylation aggregation in both A and B-ring, and (ii) honokiol, punicalagin, and the synthetic imidazolidine Compound 2 also inhibit αS amyloidogenic aggregation by stabilizing its native conformations. This diverse set of molecules acting on a singular pathological target with predicted binding to αSA53T in the folding-prone N-terminal region may contribute toward novel drug-design for PD.Sukanya Das, Tara L. Pukala and Scott D. Smi

The importance of harmonising diagnostic criteria sets for pathological grief

Five diagnostic criteria sets for pathological grief are currently used in research. Studies evaluating their performance indicate that it is not justified to generalise findings regarding prevalence rates and predictive validity across studies using different diagnostic criteria of pathological grief. We provide recommendations to move the bereavement field forward

Static avalanches and Giant stress fluctuations in Silos

We propose a simple model for arch formation in silos. We show that small pertubations (such as the thermal expansion of the beads) may lead to giant stress fluctuations on the bottom plate of the silo. The relative amplitude $\Delta$ of these fluctuations are found to be power-law distributed, as $\Delta^{-\tau}$, $\tau \simeq 1.0$. These fluctuations are related to large scale `static avalanches', which correspond to long-range redistributions of stress paths within the silo.Comment: 10 pages, 4 figures.p