4,788 research outputs found
Time Dilation and Quasar Variability
The timescale of quasar variability is widely expected to show the effects of
time dilation. In this paper we analyse the Fourier power spectra of a large
sample of quasar light curves to look for such an effect. We find that the
timescale of quasar variation does not increase with redshift as required by
time dilation. Possible explanations of this result all conflict with widely
held consensus in the scientific community.Comment: 6 pages including 3 figures. Accepted for publication in ApJ Letter
Modelling of droplet impacts on dry and wet surfaces using depth-averaged form
An efficient time-adaptive multigrid algorithm is used to solve a range of normal and oblique droplet impacts on dry surfaces and liquid films using the Depth-Averaged Form (DAF) method of the governing unsteady NavierâStokes equations. The dynamics of a moving three-phase contact line on dry surfaces is predicted by a precursor film model. The method is validated against a variety of experimental results for droplet impacts, looking at factors such as crown height and diameter, spreading diameter and splashing for a range of Weber, Reynolds and Froude numbers along with liquid film thicknesses and impact angles. It is found that, while being a computationally inexpensive methodology, the DAF method produces accurate predictions of the crown and spreading diameters as well as conditions for splash, however, underpredicts the crown height as the vertical inertia is not included in the model
Reducing Plastic Pollution in the Ocean: MycoBuoys as a Potential Solution
Natural mushroom mycelium-based MycoBuoys are an alternative to ubiquitous plastic flotation devices used in Maine aquaculture, fisheries and harbors. They fit perfectly into a circular economic model where natural resources are borrowed for a specific purpose and are returned as elements at the end of product life. MycoBuoys may be composted or used as mulch where 100% of the material enhances soil nutrients upon decomposition. In contrast to this cradle-to-cradle product, currently ubiquitous Stryofoam buoys have expensive end life costs in terms of ecosystem and organismal health consequences. Styrene is a known carcinogen, and the foam particles degrade into smaller fragments, but never go away. With the end of subsidies for fossil fuels (necessary to reach climate resilient goals), and with extended producer responsibility (EPR) for all manufactured products, plastic foams used for buoys will no longer be economically or environmentally feasible
The racist bodily imaginary: the image of the body-in-pieces in (post)apartheid culture
This paper outlines a reoccurring motif within the racist imaginary of (post)apartheid culture: the black body-in-pieces. This disturbing visual idiom is approached from three conceptual perspectives. By linking ideas prevalent in Frantz Fanonâs description of colonial racism with psychoanalytic concepts such as Lacanâs notion of the corps morcelĂ©, the paper offers, firstly, an account of the black body-in-pieces as fantasmatic preoccupation of the (post)apartheid imaginary. The role of such images is approached, secondly, through the lens of affect theory which eschews a representational âreadingâ of such images in favour of attention to their asignifying intensities and the role they play in effectively constituting such bodies. Lastly, Judith Butlerâs discussion of war photography and the conditions of grievability introduces an ethical dimension to the discussion and helps draw attention to the unsavory relations of enjoyment occasioned by such images
High Multiplicity Searches at the LHC Using Jet Masses
This article introduces a new class of searches for physics beyond the
Standard Model that improves the sensitivity to signals with high jet
multiplicity. The proposed searches gain access to high multiplicity signals by
reclustering events into large-radius, or "fat," jets and by requiring that
each event has multiple massive jets. This technique is applied to
supersymmetric scenarios in which gluinos are pair-produced and then
subsequently decay to final states with either moderate quantities of missing
energy or final states without missing energy. In each of these scenarios, the
use of jet mass improves the estimated reach in gluino mass by 20 % to 50 %
over current LHC searches.Comment: 9 pages, 6 figures; v3 corrects a few small typo
A Synoptic, Multiwavelength Analysis of a Large Quasar Sample
We present variability and multi-wavelength photometric information for the
933 known quasars in the QUEST Variability Survey. These quasars are grouped
into variable and non-variable populations based on measured variability
confidence levels. In a time-limited synoptic survey, we detect an
anti-correlation between redshift and the likelihood of variability. Our
comparison of variability likelihood to radio, IR, and X-ray data is consistent
with earlier quasar studies. Using already-known quasars as a template, we
introduce a light curve morphology algorithm that provides an efficient method
for discriminating variable quasars from periodic variable objects in the
absence of spectroscopic information. The establishment of statistically robust
trends and efficient, non-spectroscopic selection algorithms will aid in quasar
identification and categorization in upcoming massive synoptic surveys.
Finally, we report on three interesting variable quasars, including variability
confirmation of the BL Lac candidate PKS 1222+037.Comment: AJ, accepted for publication 15 Dec 200
Shakespeare 1564-1964
A Guide to an Exhibition of Rare Books Relating to Shakespeare
Upon the Occasion of the Quadricentennial of His Birth
Rare Book Room, Lehigh University Library, Bethlehem, Pa.
April 1, 196
Perserverance measures and attainment in first year computing science students.
We investigate the link between concepts of perseverance such as conscientiousness and grit, and the academic attainment of first year computing students. We review the role that perseverance plays in learning models, as well as describing the trait of conscientiousness in the Five Factor Model of personality. We outline research that links this trait with academic success, before focussing on more recent, narrower conceptualisations of perseverance such as academic tenacity and grit. We describe one of the questionnaire tools that have been used to assess the construct of grit. We give details of an investigation that looked for correlations between student responses to Duckworth's Grit Survey, the Big Five Inventory (BFI) Personality Survey and summative attainment scores in a first year programming course. The results suggest a weak but significant correlation between conscientiousness, grit and programming achievement. We discuss these results as well as the limitations of the method used. Finally, we make some observations about the importance of these concepts in Computer Science education and outline further work in this area
Associations between inattention and impulsivity ADHD symptoms and disordered eating risk in a community sample of young adults
BACKGROUND: Symptoms of attention deficit hyperactivity disorder (ADHD) and trait impulsivity have been associated with disordered eating but are seldom assessed in community studies, or longitudinally and little is known about the mediating mechanisms. METHODS: We tested associations between ADHD symptoms and disordered eating cross-sectionally and between trait impulsivity and disordered eating longitudinally. We utilised data from a normative cohort of young adults (642 participants: 65% female, M(age) = 23 years). Participants were classified as high risk or low risk for disordered eating using the SCOFF instrument. In the first two steps of both cross-sectional and longitudinal hierarchical logistic regression models, demographics and covariates were entered. For the cross-sectional regression, Adult ADHD self-report scale (ASRS) scores, separated into inattentive and hyperactive/impulsive symptoms, were entered in the third step. In a separate longitudinal model, Barratt impulsivity scale subscales (attentional, motor and non-planning impulsivity) were entered in the third step. Depression, as assessed by the moods and feelings questionnaire (MFQ), was examined as a mediator. RESULTS: Cross-sectionally, sex, MFQ score and inattentive symptoms predicted disordered eating risk (model R(2) = 20%). Longitudinally, sex, MFQ score and attentional impulsivity predicted disordered eating risk (model R(2) = 16%). The relationship between inattentive symptoms and the disordered eating risk was partially mediated by MFQ score, whereas the relationship between attentional impulsivity and the disordered eating risk was fully mediated by MFQ scores. CONCLUSIONS: These data highlight (1) a specific role for inattentive symptoms of ADHD and (2) the importance of both depression and impulsivity in predicting eating disorder risk
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