659 research outputs found
Interactions of Jets with Inhomogeneous Cloudy Media
We present two-dimensional slab-jet simulations of jets in inhomogeneous
media consisting of a tenuous hot medium populated with a small filling factor
by warm, dense clouds. The simulations are relevant to the structure and
dynamics of sources such as Gigahertz Peak Spectrum and Compact Steep Spectrum
radio galaxies, High Redshift Radio Galaxies and radio galaxies in cooling
flows. The jets are disrupted to a degree depending upon the filling factor of
the clouds. With a small filling factor, the jet retains some forward momentum
but also forms a halo or bubble around the source. At larger filling factors
channels are formed in the cloud distribution through which the jet plasma
flows and a hierarchical structure consisting of nested lobes and an outer
enclosing bubble results. We suggest that the CSS quasar 3C48 is an example of
a low filling factor jet - interstellar medium interaction whilst M87 may be an
example of the higher filling factor type of interaction. Jet disruption occurs
primarily as a result of Kelvin-Helmholtz instabilities driven by turbulence in
the radio cocoon not through direct jet-cloud interactions, although there are
some examples of these. In all radio galaxies whose morphology may be the
result of jet interactions with an inhomogeneous interstellar medium we expect
that the dense clouds will be optically observable as a result of radiative
shocks driven by the pressure of the radio cocoon. We also expect that the
radio galaxies will possess faint haloes of radio emitting material well beyond
the observable jet structure.Comment: 21 pages, 16 figures, submitted to MNRAS. A version with full
resolution figures is available at:
http://www.mssl.ucl.ac.uk/~cjs2/pdf/cloudy_hue.pd
The Effect of Hydrogen Bonding on the Hindered Rotation of the Hydroxyl Group in Alcohols
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69594/2/JCPSA6-20-12-1977-1.pd
Effect of Hydrogen Bonding on the Deformation Frequencies of the Hydroxyl Group in Alcohols
The effects of hydrogen bonding on the infrared spectra of aliphatic alcohols have been studied in the range 4000 to 350 cm—1. Twenty‐six alcohols were investigated of which 10 were primary, 7 were branched primary, 6 were secondary, and 3 were tertiary. Attention was concentrated on the region of the spectrum between 1500 cm—1 and 350 cm—1 where the deformation vibrations of the OH group occur. Spectra were obtained of the alcohols (a) in dilute solution in nonpolar solvents, (b) in the liquid state, and (c) in the vapor state, the degree of association being followed by observation of the well‐known effect of hydrogen bonding in the OH stretching vibration near 3.0μ. Methanol, ethanol, and hexanol‐1 were also investigated after deuteration of the OH group. All the alcohols exhibited a broad diffuse association band with a maximum near 650 cm—1. This has been assigned to the out‐of‐plane deformation vibration of the H atom in the COH group. All the alcohols also exhibited a broad association band which usually had 2 maxima near 1410 cm—1 and 1330 cm—1. This band (which appears to have been missed by previous workers) is assigned to the in‐plane deformation vibration of the H atom in the COH group. The corresponding monomeric band varies between 1200 cm—1 and 1330 cm—1 in undeuterated alcohols and between 870 cm—1 and 930 cm—1 in deuterated alcohols. There is in addition a very narrow association band which lies near 1100 cm—1 in primary and secondary alcohols and near 1165 cm—1 in tertiary alcohols. This is assigned to the effect of hydrogen bonding on the skeletal vibrations, which involve stretching of the CO bond. It appears that the effects of hydrogen bonding on the deformation motions of the OH group are quite complex and that steric effects, rotational isomerism, and interaction with C ☒ H deformation frequencies may all be involved to some extent.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71317/2/JCPSA6-24-3-559-1.pd
VARIABILITY OF BALL RELEASE PROPERTIES AND PITCH LENGTH ACCURACY IN CRICKET FAST BOWLING
Accurate ball pitch length in cricket fast bowling is potentially achieved from a redundant combination of four ball release parameters. Yet, it is unknown how parameter co-variations affect pitch accuracy. This study investigates whether pitch length variance is determined by coordinated ball release parameter co-variability. Twelve fast bowlers performed 18 trials at a target length and ball kinematics were captured from an indoor 3D camera setup. Multi-linear regression analysis showed that the four release parameters accounted for 79% of pitch length variance, where vertical velocity variance accounted for the most variance. When each release parameter was independently shuffled across trials, a pitch length model showed no indication of coordinated co-variability between input parameters. Therefore, pitch length accuracy was achieved by independent control of vertical velocity
Ontological co-belonging in Peter Sloterdijk's spherological philosophy of mediation
(Winner of the 2017 Paragraph annual essay prize competition, on the theme of ‘Belongings’)
This article examines the ontology and politics of Peter Sloterdijk's Spheres trilogy, focusing in particular upon the notion of microspherical enclosure explicated in the first volume of this series. Noting Sloterdijk's unusual alignment of his philosophy with media theory, three main contentions are put forward. Firstly, that Sloterdijk's reconfiguration of Heidegger's fundamental ontology represents a largely unacknowledged renunciation of the primacy of Being-towards-death in the authentic existence of Dasein, foregrounding instead an originary co-belonging between mother and child. Secondly, that Sloterdijk borrows from media theory a concern regarding the facticity of all communication, grounding philosophical discourse in the determinate locality of its origin, but does so while exalting a pre-natal communicative immediacy that would seem to disparage the everydayness of Dasein. Finally, that Sloterdijk's oft-justified scepticism regarding globalization often retreats into an anti-cosmopolitanism that, in its nostalgia for the comfort, security and immediacy of the matrixial co-belonging (and the various attempts by humans to replicate this enclosure), evinces a covert but potentially noxious politics of exclusion
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Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates
Terrestrial Mammal Conservation provides a thorough summary of the available scientific evidence of what is known, or not known, about the effectiveness of all of the conservation actions for wild terrestrial mammals across the world (excluding bats and primates, which are covered in separate synopses). Actions are organized into categories based on the International Union for Conservation of Nature classifications of direct threats and conservation actions. Over the course of fifteen chapters, the authors consider interventions as wide ranging as creating uncultivated margins around fields, prescribed burning, setting hunting quotas and removing non-native mammals.This book is written in an accessible style and is designed to be an invaluable resource for anyone concerned with the practical conservation of terrestrial mammals.The authors consulted an international group of terrestrial mammal experts and conservationists to produce this synopsis. Funding was provided by the MAVA Foundation, Arcadia and National Geographic Big Cats Initiative.Terrestrial Mammal Conservation is the seventeenth publication in the Conservation Evidence Series, linked to the online resource www.ConservationEvidence.com. Conservation Evidence Synopses are designed to promote a more evidence-based approach to biodiversity conservation. Others in the series include Bat Conservation, Primate Conservation, Bird Conservation and Forest Conservation and more are in preparation. Expert assessment of the evidence summarised within synopses is provided online and within the annual publication What Works in Conservation
The views of five participating undergraduate students of the Student Associates Scheme in England
This paper reports findings from a study which explored undergraduate perceptions of the Student Associates Scheme in England (SAS). The scheme was established by the Training and Development Agency for Schools in an attempt to increase the number of graduates entering the teaching profession, particularly in shortage subjects such as the physical sciences and mathematics. The scheme places undergraduate students on short-term placements in secondary schools throughout England to provide them with experiences that may encourage them to consider teaching as a career option. Findings show that the SAS school placements were a positive experience for the students participating in this study. However, a question emerged as to whether or not the scheme is targeting students who have yet to decide upon teaching as a career or just reinforcing the existing aspirations of students who have already decided to teach. As the scheme is attempting to increase the number of teachers entering the profession this question has important implications for this study and further work which will focus on undergraduates who think that their career ambitions would not be fulfilled by teaching
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