Evolution of vorticity and enstrophy in the intracluster medium

Turbulence generated by large-scale motions during structure formation affects the evolution of the thermal and non-thermal components of the intracluster medium. As enstrophy is a measure of the magnitude of vorticity, we study the generation and evolution of turbulence by analysing the Lagrangian history of enstrophy. For this purpose we combine cosmological simulations carried out with the ENZO-code with our Lagrangian post-processing tool CRaTer. This way we are able to quantify the individual source terms of enstrophy in the course of the accretion of groups onto galaxy clusters. Here we focus on the redshift range from $z=1$ to $z=0$. Finally, we measure the rate of dissipation of turbulence and estimate the resulting amplification of intracluster magnetic fields. We find that compressive and baroclinic motions are the main sources of enstrophy, while stretching motions and dissipation affect most of the ensuing enstrophy evolution. The rate of turbulent dissipation is able to sustain the amplification of intracluster magnetic fields to observed levels.Comment: 14 pages, 17 Figures, accepted for publication in MNRA

Competitive ability of creeping bentgrass cultivars and their potential for renovating existing putting greens through interseeding

Golf is a key industry that generates jobs, commerce, economic development, and tax revenues for communities throughout the United States. A survey conducted in Iowa showed that golf generated 769.6 million dollars in total economic output while providing over 10,000 jobs to the state. The integrity of turf swards is routinely compromised by invasion from annual bluegrass (Poa annua L.), and higher levels of inputs are needed to maintain acceptable quality. New cultivars of creeping bentgrass (Agrostis stolonifera L.) offer improved agronomic characteristics and are better able to resist invasion from annual bluegrass. The overall objective of this research was to evaluate the culture of creeping bentgrass cultivars and assess the practice of interseeding as a means of converting existing putting greens to recently developed cultivars. Recently developed cultivars of creeping bentgrass possess finer leaf texture and more upright leaf architecture. These morphological characteristics allow for increased shoot densities. Results from our research suggest that a greater number of shoots hinders the plant\u27s ability to recuperate from injury. Our work also demonstrated that cultivars of creeping bentgrass displayed varying lateral spread rates and stolon and internode lengths. Growth analysis revealed that low shoot density cultivars allocate more dry matter into stolons than leaves. Difference in dry matter partitioning could partially explain differences in lateral spread among cultivars of creeping bentgrass. Higher shoot density cultivars may be better suited for areas where low populations of annual bluegrass are desired. Alternatively, lower shoot density cultivars may be better suited for areas where mechanical damage is frequent and recuperative potential is important. The vegetative characteristics should be matched with desired site usage requirements for optimum performance when selecting cultivars of creeping bentgrass. The ability of established facilities to utilize recently developed cultivars is limited as few conversion methods exist. Current renovation methods require a facility to incur significant financial loss. Interseeding has been proposed as an alternative conversion method with less financial burden. Germination studies showed that recently developed cultivars of creeping bentgrass possess greater vigor and may be better suited for interseeding compared with older cultivars. Our interseeding studies suggest that the level of maintenance and overall quality of the putting surface influence the success of conversion. Conversion through interseeding in this study was not successful when the plots were maintained under golf course conditions. Interseeding was only successful when conditions of the putting green were allowed to deteriorate below acceptable levels. The overall conditioning of the putting surface in order to permit interseeding needs to be weighed against the cost of a traditional conversion when deciding on a renovation program

Old Hispanic notation and the early written transmission of chant:a study of British Library, Additional Manuscript 30845

In this dissertation, I examine music writing and chant transmission in medieval Iberia through the lens of one manuscript – London, British Library Add. MS 30845 (BL45). BL45 contains chants, prayers and readings for the public services of the Old Hispanic rite from June to November. Through close study of the codicology of the manuscript, its liturgical and musical contents, and identification of the scribes who copied the manuscript I investigate the processes of producing this manuscript. The origins of many Old Hispanic manuscripts cannot be securely attributed. Through an interdisciplinary approach to the contents of BL45, I firmly position BL45 as a product of the monastery of San Millán de la Cogolla, allowing me to situate BL45 within the broader liturgical, notational and melodic culture of the monastery across the 10th and 11th centuries. The findings of my research challenge the prevailing narrative of homogenous house style in Iberian scriptoria, as well as the existing chronological and geographical narratives regarding the development and transmission of Old Hispanic notation and melodies. As I will show, it is necessary to engage with each of the main features of an Old Hispanic manuscript to gain a fine-grained understanding of Old Hispanic cultural practices from the perspective of the individuals who preserved them in writing. By situating my findings within the broader context of the Old Hispanic materials, I aim to deepen the understanding of this underexplored branch of medieval Christian devotion

Emotional modulation of visual cortex activity: A functional nearinfrared spectroscopy study

Functional neuroimaging and electroencephalography reveal emotional effects in early visual cortex. Here, we used fNIRS to examine haemodynamic responses evoked by neutral, positive and negative emotional pictures, matched for brightness, contrast, hue, saturation, spatial frequency and entropy. Emotion content modulated amplitude and latency of oxy-, deoxy- and total haemoglobin response peaks, and induced peripheral autonomic reactions. The processing of positive and negative pictures enhanced haemodynamic response amplitude, and this effect was paralleled by blood pressure changes. The processing of positive pictures was reflected in reduced haemodynamic response peak latency. Together these data suggest early visual cortex holds amplitude-dependent representation of stimulus salience and latency-dependent information regarding stimulus valence, providing new insight into affective interaction with sensory processing

Evolution of the subcortical circuits controlling goal-directed behaviour

The aim of the work presented in this thesis was to reconstruct the minimal neural hardware that vertebrates use for goal-directed behaviour. By studying lamprey, one of the phylogenetically oldest vertebrates, we were able to identify the neural circuitry that has been conserved since jawed and jawless vertebrates diverged over 560 million years ago. Specifically we examined the conservation of the subcortical circuits involving the optic tectum, basal ganglia and habenula. These structures are responsible for steering, action selection and motivation in mammals. Optic tectum; this structure is essential for visually guiding purposeful movements to either avoid or approach objects of interest. Using a combination of tract tracing and stereology we demonstrated that the pattern of sensory innervation is conserved as the retinotectal connection in lamprey is arranged in a retinotopic manner. By analyzing the spatial arrangement between this retinotopic map and the underlying motor map (Saitoh et al., 2007) we revealed that optic tectum can guide lamprey towards or away from the source of visual input. This suggests that tectal circuits controlling both approach and avoidance were present at the dawn of vertebrate evolution and have subsequently been conserved. Furthermore, our result indicate that there are two independent retinal circuits in lamprey; one that may contact the photoreceptors directly and transmit information to the pretectum with a minimal delay for reflexive behaviours and another that contacts the image forming part of the retina (inner plexiform layer) that sends projections to the optic tectum to control goal-directed visual behaviours. Basal ganglia; these nuclei play a key role in action selection in mammals. We showed, using immunohistochemistry, tract tracing, and whole-cell recordings, that all parts of the mammalian basal ganglia (striatum, globus pallidus interna [GPi] and externa [GPe], and subthalamic nucleus [STN]) are present in the lamprey forebrain. In addition, the circuit features, molecular markers, and physiological activity patterns are conserved. Thus, GABAergic striatal neurons expressing substance P project directly to the pallidal output layer, whereas enkephalin- expressing striatal neurons project indirectly via nuclei homologous to the GPe and STN. These results show for the first time that both the “direct” and “indirect” pathways are present in a lower (anamniote) vertebrate. Our results suggest that this circuitry has been conserved in all vertebrates, most likely as a mechanism for action selection, for over 560 million years. Extending our analysis we revealed that the phylogenetically oldest basal ganglia include the pedunculopontine nucleus and a separate habenula projecting pallidal nucleus. This later nucleus differs from other pallidal nuclei, as its neurons project to a reward-related structure, are glutamatergic and differ from other pallidal neurons in their molecular expression, connectivity and electrophysiological properties. These results suggest that this nucleus may represent the output of a previously unappreciated pathway through the basal ganglia. Habenulae; the medial (MHb) and lateral (LHb) habenulae are a small group of nuclei that contribute to a range of cognitive and motor functions by regulating the neuromodulatory systems. Based on connectivity and molecular expression, we show that the MHb and LHb circuitry is conserved in the lamprey. As in mammals, neurons in the LHb homolog project indirectly to dopamine and serotonin neurons through a nucleus homologous to the GABAergic rostromedial mesopontine tegmental nucleus. This suggests that the LHb may exert an inhibitory influence on the neuromodulatroy systems to regulate reinforcement learning and motivation as it does in mammals. The efferents of the MHb homolog selectively target the interpeduncular nucleus, which in turn projects to regions involved in innate behavioral responses such as fight or flight. In contrast to mammals, the MHb afferents arise from sensory (medial olfactory bulb, parapineal, and pretectum) and not limbic areas. This suggests that the “context” in which this circuitry is recruited but not the role of the circuit may have changed during evolution. Our results indicate that the habenular nuclei provide a common vertebrate circuitry to adapt behavior in response to rewards, stress, and other motivating factors

HM 23: New Interpretations in Naval History

Selected Papers from the Seventeenth McMullen Naval History Symposium Held at the United States Naval Academy, 15–16 September 2011.https://digital-commons.usnwc.edu/usnwc-historical-monographs/1022/thumbnail.jp

Engaged: A teacher resource based on fun factor

The purpose of this project was to develop a teacher resource in which content is both standards based and student demonstrated as fun in which to participate. The form of this resource is a website called Engaged. It will ultimately consist of several folioed and interconnected web pages. Academic content is to be all teacher supplied. At risk youth are in danger of being left behind, not only in schools, but by society as a whole. Through classroom teachers it has the potential to provide at-risk-youth a vital bridge across the digital divide

HM 23: New Interpretations in Naval History

Selected Papers from the Seventeenth McMullen Naval History Symposium Held at the United States Naval Academy, 15–16 September 2011.https://digital-commons.usnwc.edu/usnwc-historical-monographs/1022/thumbnail.jp

Lipid Metabolism and Comparative Genomics

Unilever asked the Study Group to focus on two problems. The first concerned dysregulated lipid metabolism which is a feature of many diseases including metabolic syndrome, obesity and coronary heart disease. The Study Group was asked to develop a model of the kinetics of lipoprotein metabolism between healthy and obese states incorporating the activities of key enzymes. The second concerned the use of comparative genomics in understanding and comparing metabolic networks in bacterium. Comparative genomics is a method to make inferences on the genome of a new organism using information of a previously charaterised organism. The first mathematical question is how one would quantify such a metabolic map in a statistical sense, in particular, where there are different levels of confidence for presense of different parts of the map. The next and most important question is how one can design a measurement strategy to maximise the confidence in the accuracy of the metabolic map