14,815 research outputs found
Troubling the “WE” in art education: Slam poetry as subversive duoethnography
Scholarly dialogues are filled with discussions of teacher’s personal perspectives, experiences, and challenges - but rarely do these dialogues include the narratives that lie beneath the surface. The subversive tales confronting stories of microagressions, alternate histories, and institutionalized norms that shape the educational landscape we navigate daily. This paper is focused on bringing to the surface a call and response lament of two social justice-oriented art educators--one Black, the other White. Using the dialogic methodology of duoethnography and the performative aspects of slam poetry, we share our racialized-teaching accounts as a multisensory experience, where text and performative orality share a chimeric relationship. The slam poem format, along with a critical arts-based perspective, allows us to speak/perform with urgency alongside one another to share tales of an educational landscape rife with racialized inequities. Using the metaphor of eyesight, and its subsequent limitations, our poem references the challenges of human interaction within the rubric of racial categorization. We see slam poetry as a democratic means of performing identity and as a way to subvert the limitations of traditional hegemonic forms and norms and frame our poetic call and response as verses from below. This form of poetic lament frames our socio-political interaction around the concepts of Whiteness and Blackness in and through teaching and learning in art education. We close with brief considerations for how this approach might be generative in critically framing personal and educational interactions between/among/across difference
A Nonparametric Bayesian Approach to Uncovering Rat Hippocampal Population Codes During Spatial Navigation
Rodent hippocampal population codes represent important spatial information
about the environment during navigation. Several computational methods have
been developed to uncover the neural representation of spatial topology
embedded in rodent hippocampal ensemble spike activity. Here we extend our
previous work and propose a nonparametric Bayesian approach to infer rat
hippocampal population codes during spatial navigation. To tackle the model
selection problem, we leverage a nonparametric Bayesian model. Specifically, to
analyze rat hippocampal ensemble spiking activity, we apply a hierarchical
Dirichlet process-hidden Markov model (HDP-HMM) using two Bayesian inference
methods, one based on Markov chain Monte Carlo (MCMC) and the other based on
variational Bayes (VB). We demonstrate the effectiveness of our Bayesian
approaches on recordings from a freely-behaving rat navigating in an open field
environment. We find that MCMC-based inference with Hamiltonian Monte Carlo
(HMC) hyperparameter sampling is flexible and efficient, and outperforms VB and
MCMC approaches with hyperparameters set by empirical Bayes
Calculating the transfer function of noise removal by principal component analysis and application to AzTEC observations
Instruments using arrays of many bolometers have become increasingly common
in the past decade. The maps produced by such instruments typically include the
filtering effects of the instrument as well as those from subsequent steps
performed in the reduction of the data. Therefore interpretation of the maps is
dependent upon accurately calculating the transfer function of the chosen
reduction technique on the signal of interest. Many of these instruments use
non-linear and iterative techniques to reduce their data because such methods
can offer improved signal-to-noise over those that are purely linear,
particularly for signals at scales comparable to that subtended by the array.
We discuss a general approach for measuring the transfer function of principal
component analysis (PCA) on point sources that are small compared to the
spatial extent seen by any single bolometer within the array. The results are
applied to previously released AzTEC catalogues of the COSMOS, Lockman Hole,
Subaru XMM-Newton Deep Field, GOODS-North and GOODS-South fields. Source flux
density and noise estimates increase by roughly +10 per cent for fields
observed while AzTEC was installed at the Atacama Submillimeter Telescope
Experiment and +15-25 per cent while AzTEC was installed at the James Clerk
Maxwell Telescope. Detection significance is, on average, unaffected by the
revised technique. The revised photometry technique will be used in subsequent
AzTEC releases.Comment: 14 pages, 4 figure
The triggered behavior of a controlled corona stabilised cascade switch
Corona stabilised switches have been shown to have advantages in pulse power switching applications due to their high repetition rates and low jitter. Work performed in recent years by the High Voltage Technologies Group within the Department of Electronic and Electrical Engineering at the University of Strathclyde has shown that the operating voltage range of such switches can be extended by using a multi-gap cascade configuration. One particular multi-gap topology was shown to operate under pressure at 100 kV with a switching jitter of 2ns. It has since been shown that by modifying the topology of the corona sources on the electrodes, it is possible to control the grading of the voltage distribution across the gaps in the cascade. The voltages across each gap and the self-break behaviour of the cascade were found to be in close agreement with the values predicted from the corona emission characteristics for the tested electrode topologies. This paper reports on a further examination of the behaviour of the corona controlled switching topology, where triggered operation of the switch has been investigated for different voltage distributions across the cascade gaps
Age, growth, mortality, and radiometric age validation of gray snapper (Lutjanus griseus) from Louisiana
The gray snapper (Lutjanus griseus) is a temperate and tropical reef fish that is found along the Gulf of Mexico and Atlantic coasts of the southeastern United States. The recreational fishery for gray snapper has developed rapidly in south Louisiana with the advent of harvest and seasonal
restrictions on the established red snapper (L. campechanus) fishery. We examined the age and growth of
gray snapper in Louisiana with the use of cross-sectioned sagittae. A total of 833 specimens, (441 males, 387
females, and 5 of unknown sex) were opportunistically sampled from the recreational fishery from August 1998 to August 2002. Males ranged in size from 222 to 732 mm total length (TL) and from 280 g to 5700 g total weight (TW) and females ranged from 254 to 756 mm TL and from 340 g to 5800 g TW. Both edge analysis and bomb radiocarbon analyses were used to validate otolith-based age estimates. Ages were estimated for 718 individuals; both males and females ranged
from 1 to 28 years. The von Bertalanffy growth models derived from TL at age were Lt = 655.4{1–e[–0.23(t)]}
for males, Lt = 657.3{1–e[– 0.21(t)]} for females, and L t = 656.4{1–e[– 0.22 (t)]} for all specimens of known sex. Catch curves were used to produce a total mortality (Z) estimate of 0.17. Estimates of M calculated with various
methods ranged from 0.15 to 0.50; however we felt that M= 0.15 was the most appropriate estimate based on our estimate of Z. Full recruitment to the gray snapper recreational fishery began at age 4, was completed by age
8, and there was no discernible peak in the catch curve dome
Paleoecological Significance of Holocene Insect Fossil Assemblages from the North Coast of Alaska
Two peat sections containing insect fossil remains from the eastern coastal plain of the Alaskan North Slope were analyzed in comparison with pollen studies. The sections span a period from 10,400 B.P. to 1,320 B.P., providing information on the post-glacial distributions of some of the beetles species that were a part of the Beringian refugium fauna. The fossil insect evidence suggests climatic conditions similar to modern parameters, especially in the early Holocene, in general agreement with paleobotanical and vertebrate fossil interpretations for the coastal plain and elsewhere in eastern Beringia.Key words: Holocene, paleoenvironments, insect fossils, AlaskaMots clés: Holocène, paléoenvironnements, fossiles d'insectes, Alask
Design of a microwave radiometer for monitoring high voltage insulator contamination level
Microwave radiometry is a novel method for monitoring contamination levels on high voltage insulators. The microwave radiometer described measures energy emitted from the contamination layer and could provide a safe, reliable, contactless monitoring method that is effective under dry conditions. The design of the system has focused on optimizing accuracy, stability and sensitivity using a relatively low cost architecture. Experimental results demonstrate that the output from the radiometer is able to clearly distinguish between samples with different contamination levels under dry conditions. This contamination monitoring method could potentially provide advance warning of the future failure of wet insulators in climates where insulators can experience dry conditions for extended periods
The central density of a neutron star is unaffected by a binary companion at linear order in
Recent numerical work by Wilson, Mathews, and Marronetti [J. R. Wilson, G. J.
Mathews and P. Marronetti, Phys. Rev. D 54, 1317 (1996)] on the coalescence of
massive binary neutron stars shows a striking instability as the stars come
close together: Each star's central density increases by an amount proportional
to 1/(orbital radius). This overwhelms any stabilizing effects of tidal
coupling [which are proportional to 1/(orbital radius)^6] and causes the stars
to collapse before they merge. Since the claimed increase of density scales
with the stars' mass, it should also show up in a perturbation limit where a
point particle of mass orbits a neutron star. We prove analytically that
this does not happen; the neutron star's central density is unaffected by the
companion's presence to linear order in . We show, further, that the
density increase observed by Wilson et. al. could arise as a consequence of not
faithfully maintaining boundary conditions.Comment: 3 pages, REVTeX, no figures, submitted to Phys Rev D as a Rapid
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Anti-CD20 therapy depletes activated myelin-specific CD8+ T cells in multiple sclerosis.
CD8+ T cells are believed to play an important role in multiple sclerosis (MS), yet their role in MS pathogenesis remains poorly defined. Although myelin proteins are considered potential autoantigenic targets, prior studies of myelin-reactive CD8+ T cells in MS have relied on in vitro stimulation, thereby limiting accurate measurement of their ex vivo precursor frequencies and phenotypes. Peptide:MHC I tetramers were used to identify and validate 5 myelin CD8+ T cell epitopes, including 2 newly described determinants in humans. The validated tetramers were used to measure the ex vivo precursor frequencies and phenotypes of myelin-specific CD8+ T cells in the peripheral blood of untreated MS patients and HLA allele-matched healthy controls. In parallel, CD8+ T cell responses against immunodominant influenza epitopes were also measured. There were no differences in ex vivo frequencies of tetramer-positive myelin-specific CD8+ T cells between MS patients and control subjects. An increased proportion of myelin-specific CD8+ T cells in MS patients exhibited a memory phenotype and expressed CD20 compared to control subjects, while there were no phenotypic differences observed among influenza-specific CD8+ T cells. Longitudinal assessments were also measured in a subset of MS patients subsequently treated with anti-CD20 monoclonal antibody therapy. The proportion of memory and CD20+ CD8+ T cells specific for certain myelin but not influenza epitopes was significantly reduced following anti-CD20 treatment. This study, representing a characterization of unmanipulated myelin-reactive CD8+ T cells in MS, indicates these cells may be attractive targets in MS therapy
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