Response inhibition is linked to emotional devaluation: behavioural and electrophysiological evidence

To study links between the inhibition of motor responses and emotional evaluation, we combined electrophysiological measures of prefrontal response inhibition with behavioural measures of affective evaluation. Participants first performed a Go-Nogo task in response to Asian and Caucasian faces (with race determining their Go or Nogo status), followed by a trustworthiness rating for each face. Faces previously seen as Nogo stimuli were rated as less trustworthy than previous Go stimuli. To study links between the efficiency of response inhibition in the Go-Nogo task and subsequent emotional evaluations, the Nogo N2 component was quantified separately for faces that were later judged to be high versus low in trustworthiness. Nogo N2 amplitudes were larger in response to low-rated as compared to high-rated faces, demonstrating that trial-by-trial variations in the efficiency of response inhibition triggered by Nogo faces, as measured by the Nogo N2 component, co-vary with their subsequent affective evaluation. These results suggest close links between inhibitory processes in top-down motor control and emotional responses

Impact of the Black-Tailed Jackrabbits (Lepus Californicus) on Vegetation in Curlew Valley, Northern Utah

The interrelations of black- tailed jackrabbits and the desertshrub vegetation on which they were feeding were studied in Curlew Valley, Northern Utah. The vegetation was described as a threecornered continuum, the corners being types dominated respectively by Artemisia tridentata, Atriplex ~ onfertifolia, and Sarcobatus vermiculatus. Jackrabbit diet was studied by microscopic analysis of plant fragments in stomachs from shot animals. The method was inaccurate, apparently because the ratio of identifiable tissues to all ingested tissues was very low, and varied between plant taxa, and seasonally. This problem seems intractable for desert shrub vegetation. The diet was similar to that reported by other workers on this species, with perennial grasses and forbs most important in sprlng and summer, shrubs in autumn and win ter. Features new to this vegetat ion were large percentages of Halogeton glomeratus, particularly in autumn and winter, and intense selection for Kochia americana. Attempts to explain the foods chosen ln terms of t heir nutrient contents were partically successful. Diet selection by large generalist herbivores was conceptualized as optimization of nutrient intake, mediated by long-delay learning, and constrained by food availability only at very low levels of availaoility. Spatial variation in jackrabbit diets confirmed this cut-offll response to ava i 1 all i 1 i ty . Percentage utilization was estimated indirectly as jackrabbit density, times yearly food consumption per jackrabbit, times yearround percentage of each taxon in the diet, div i ded by available biomass of each taxon. Less abundant plants were more intensely used, which is expected if consumption does not vary continuously with availability. Perennial grasses, Kochia americana and possibly Grayia spinosa seemed to be under damaging pressure at high jackrabbit densities. Kochia had almost disappeared from outside a sheep- and jackrabbitproof exclosure since the 1950 1 s. In other exc1osures, the presence or absence of jackrabbits seemed to make no difference to the rate of vegetation recovery over 5-7 years after exclusion of sheep. Jackrabbit use of a crested wheatgrass seeding was concentrated ln a 300 m band around its edge

Alternative splicing and single-cell RNA-sequencing: a feasibility assessment

We know little about how isoform choice is regulated in individual cells for most spliced genes. In theory, single-cell RNA-sequencing (scRNA-seq) could enable us to investigate isoform choice at cellular resolution. Therefore, scRNA-seq could give insight into the fundamental molecular biology process of how alternative splicing is regulated within cells. However, scRNA-seq is a relatively new technology, and at the start of my PhD it was not clear whether existing bioinformatics approaches would enable accurate splicing analyses. In my PhD I consider what the limitations are when attempting to study alternative splicing using scRNA-seq and what can be done to overcome them. Alternative splicing is commonly analysed using bulk RNA sequencing (bulk RNA-seq) data with isoform quantification software. It was not clear whether isoform quantification software designed for bulk RNA-seq would perform well when run on scRNA-seq data. To address this, I performed a simulation-based benchmark of isoform quantification software developed for bulk RNA-seq when run on scRNA-seq. I made two important findings. Firstly, I found that isoform quantification software performs poorly when run on Drop-seq data, but performs better when run on scRNA-seq data generated using full-length transcript protocols (eg. SMART-seq and SMART-seq2). Secondly, I found that for the most part, isoform quantification software performs almost as well when run on full-length scRNA-seq as it does when run on bulk RNA-seq. Based on these findings, I concluded that software tools to accurately quantify the reads from full-length scRNA-seq experiments exist, theoretically enabling alternative splicing to be analysed using scRNA-seq. Encouraged by this result, I embarked on a series of experiments designed to answer questions such as ‘How many isoforms does a gene typically produce per cell?’. This is a key basic biology question that could in theory be answered using scRNA-seq. Unfortunately, I found that the results of these experiments were largely impossible to interpret because I was unable to distinguish between biological signal and technical noise. I realised that without a solid understanding of the technical noise and confounding factors associated with scRNA-seq, distinguishing biological signal from technical noise would be challenging and might not be possible. To address this, I embarked on a second simulation-based study, this time investigating the impact of technical noise on our ability to study alternative splicing using scRNA-seq. I simulated four situations: a situation where every gene expressed one isoform per cell, a situation where all genes expressed two isoforms per cell, a situation where all genes expressed three isoforms per cell and a situation where all genes expressed four isoforms per cell. Importantly, I explicitly simulated isoform choice, dropouts and quantification errors. The results of the four simulated situations were not trivial to distinguish from each other, raising concerns about the feasibility of resolving the more complex splicing patterns that probably exist in reality using scRNA-seq data. I concluded that attempts to study alternative splicing using scRNA-seq are currently substantially confounded by a high rate of dropouts and a lack of understanding about the mechanism of isoform choice. Importantly, improvements to isoform quantification software accuracy alone were insufficient to correct for confounding effects caused by dropouts. I propose that to enable accurate alternative splicing analyses using scRNA-seq, further research into accurately modelling dropouts is required, or alternatively, scRNA-seq technologies should be improved to increase their capture efficiency. Additionally, research into how isoform choice is regulated at a cellular level is necessary to enable accurate analyses. Overall, I find that it is not currently possible to accurately perform alternative splicing analyses using scRNA-seq. However, I am optimistic that with further research, it may become possible in the future

Images from Old Norse Mythology and Legend on Anglo-Scandinavian and Scandinavian Stone Sculpture and some Wood Objects

The objective of this thesis was to survey the various stone and wood monuments (that include images from Old Norse mythology and legend) in the north of England and Scandinavia during the so-called Viking Age. Chapter One examines the English material, with a particular focus on the myths involving Völundr the smith, Sigurðr, Ragnarök, Þórr and the Miðgarðsormr and some other more obscure figures. Chapter Two explores the relationship between the form of pre-Christian religion of the Vikings and Christianity. In this instance, the stone sculpture from northern England became the grounds for examination, although I have also invoked many of the relevant texts from the Old Norse-Icelandic literary record. Chapter Three is an examination of the material from Scandinavia (Sweden, Norway and Denmark) and the Isle of Man. This chapter has been divided into three sections – one for each country with further subdivisions on the basis of myth. Chapter Three is similar to the first in presentation, although more independent analysis has been undertaken as language barriers have prevented me from reading the Scandinavian written records with complete accuracy. My arguments include the following: (a) that the relationship between Old Norse paganism and Christianity has been largely underestimated and has yet to be properly researched; (b) that this relationship has deep roots on many levels as evidenced by the Viking Age sculpture and Old Norse literature; (c) many of the Scandinavian myths and legends were thought continuous within the broad Christian framework and were embraced, hence their appearance on the monuments; (d) there is an old tradition of image making in Scandinavia and the British Isles that connects the two areas together, despite the vastness of the sea; (e) many of the monuments in both areas share aspects of composition, style and content and should be viewed as belonging to the same overarching tradition but, in some cases, as having arisen independently

Images from Old Norse Mythology and Legend on Anglo-Scandinavian and Scandinavian Stone Sculpture and some Wood Objects

The objective of this thesis was to survey the various stone and wood monuments (that include images from Old Norse mythology and legend) in the north of England and Scandinavia during the so-called Viking Age. Chapter One examines the English material, with a particular focus on the myths involving Völundr the smith, Sigurðr, Ragnarök, Þórr and the Miðgarðsormr and some other more obscure figures. Chapter Two explores the relationship between the form of pre-Christian religion of the Vikings and Christianity. In this instance, the stone sculpture from northern England became the grounds for examination, although I have also invoked many of the relevant texts from the Old Norse-Icelandic literary record. Chapter Three is an examination of the material from Scandinavia (Sweden, Norway and Denmark) and the Isle of Man. This chapter has been divided into three sections – one for each country with further subdivisions on the basis of myth. Chapter Three is similar to the first in presentation, although more independent analysis has been undertaken as language barriers have prevented me from reading the Scandinavian written records with complete accuracy. My arguments include the following: (a) that the relationship between Old Norse paganism and Christianity has been largely underestimated and has yet to be properly researched; (b) that this relationship has deep roots on many levels as evidenced by the Viking Age sculpture and Old Norse literature; (c) many of the Scandinavian myths and legends were thought continuous within the broad Christian framework and were embraced, hence their appearance on the monuments; (d) there is an old tradition of image making in Scandinavia and the British Isles that connects the two areas together, despite the vastness of the sea; (e) many of the monuments in both areas share aspects of composition, style and content and should be viewed as belonging to the same overarching tradition but, in some cases, as having arisen independently

The prevalence of AGN feedback in massive galaxies at z~1

We use the optical--infrared imaging in the UKIDSS Ultra Deep Survey field, in combination with the new deep radio map of Arumugam et al., to calculate the distribution of radio luminosities among galaxies as a function of stellar mass in two redshift bins across the interval 0.4<z<1.2. This is done with the use of a new Bayesian method to classify stars and galaxies in surveys with multi-band photometry, and to derive photometric redshifts and stellar masses for those galaxies. We compare the distribution to that observed locally and find agreement if we consider only objects believed to be weak-lined radio-loud galaxies. Since the local distribution is believed to be the result of an energy balance between radiative cooling of the gaseous halo and mechanical AGN heating, we infer that this balance was also present as long ago as z~1. This supports the existence of a direct link between the presence of a low-luminosity ('hot-mode') radio-loud active galactic nucleus and the absence of ongoing star formation.Comment: 10 pages, MNRAS, in pres

On Limits to Seed Production

Organismic and Evolutionary Biolog

Suicide Exposure in a Polymediated Age

With growing evidence that media plays a vital role in shaping public understanding of suicidality and influencing behaviours, media portrayals of suicidality have for some time been the focus of suicide prevention efforts. Traditional media has changed, and now exists alongside and within an instantaneous, interactive sharing of information created and controlled by anyone; the way most people use it today incorporates a wide variety of online communication media. Polymedia describes media communication as both a product and process, where anyone can contribute and act as producers, consumers, audiences, and critics. In a “Polymediated age,” media exposure becomes much more complex. To understand how media exposure to suicide influences and impacts on others, it is important to take into account the communicative ecology of media technologies and the different interactions we can have with them. We researched the effects of this type of exposure by conducting in-depth interviews with a purposive sample of individuals who have lived experience and/or knowledge of suicide exposure via polymediated communication in the aftermath of a suicide. Using thematic analysis, our data demonstrates how exposure to suicide has become more complex as a result of new communicative media technology: it can be both a gift and a curse, difficult to distinguish, predict or control. Polymedia has the power to determine new forms of narrative and new forms of behaviour that on the one hand can provide support and prevention efforts, while on the other hand can promote conflict and cast an adverse influence on suicidal behaviour. Polymedia provides novel affordances for very intimate collective exposure to suicide. Our findings shed important new light on how the interplay between news media and social media has transformed our relationship with the information to which we’re exposed. We highlight important suggestions for those working in suicide prevention to develop (1) media strategies that recognise the multiple ways in which users are exposed and impacted, and (2) mechanisms for a strategic amplification and moderation of specific types of content. Media organisations and users of social media alike can contribute to maximising the beneficial capacity of polymediated exposure to suicide