284 research outputs found
Honeywell's Compact, Wide-angle Uv-visible Imaging Sensor
Honeywell is currently developing the Earth Reference Attitude Determination System (ERADS). ERADS determines attitude by imaging the entire Earth's limb and a ring of the adjacent star field in the 2800-3000 A band of the ultraviolet. This is achieved through the use of a highly nonconventional optical system, an intensifier tube, and a mega-element CCD array. The optics image a 30 degree region in the center of the field, and an outer region typically from 128 to 148 degrees, which can be adjusted up to 180 degrees. Because of the design employed, the illumination at the outer edge of the field is only some 15 percent below that at the center, in contrast to the drastic rolloffs encountered in conventional wide-angle sensors. The outer diameter of the sensor is only 3 in; the volume and weight of the entire system, including processor, are 1000 cc and 6 kg, respectively
Wall of Noise, Web of Silence
The Artist Formerly Known as David Pledger will release his first concept album WALL OF NOISE WEB OF SILENCE with LINER NOTES Using the moniker, dp, the artist takes his lead from all those brave artists who embraced the challenge of the concept album, from Brian Wilson of The Beach Boys through to Radiohead and Bjork. “The concept album best serves my ambition to create a kind of knowledge in which aesthetics and scholarship operate in a complementary and expansive mode, so that argument may be understood simultaneously through the processes of thinking and feeling.” dp is renowned for his exploratory and experimental artistic adventures that include The Austral/Asian Post-Cartoon: sports edition (1997), Blowback (2004), The Strangeland Triptych (2006-9), Ampersand et al (2010) and David Pledger Is Running For Office (2015). Side 1 is dp’s thesis on democracy in the age of neo-liberalism through the lens of the arts. Side 2 is its antithesis, an atmosphere of democracy in which artistic practice is the prevailing determinant. Noise and silence are the aesthetic frames. The arts, society and politics provide the windows. “On Side 1, you’ll play ‘concept’ tracks, a mini-EP and three 12-inch 45s backgrounded by the beautiful sounds and disturbing speeches of my artistic oeuvre. On Side 2, I take you on a journey that aspires to ‘listen’ a way towards a ‘solution’ to our deepest problem: what to do about democracy?” Two sides riffing off each other and a comprehensive clutch of Liner Notes that reflect on what it means for dp’s artistic practice. “For thirty years, my life as an artist has been a procession of master shots of Western culture from different vantage points: minor pop culture personality, writer, performer, director, producer, arts leader, cultural activist. These are the band members on my new album taking the lead on some tracks, playing back-up on others. The most ambitious and comprehensive explication of my practice to date, Wall of Noise, Web of Silence poses the perfect question: what next, dp, what next….
Mixture models for distance sampling detection functions
Funding: EPSRC DTGWe present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used âkey function plus series adjustmentâ (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set.Publisher PDFPeer reviewe
The First Optical Spectra of Wolf Rayet Stars in M101 Revealed with Gemini/GMOS
Deep narrow-band HST imaging of the iconic spiral galaxy M101 has revealed over a thousand new Wolf Rayet (WR) candidates. We report spectrographic confirmation of 10 HeII emission line sources hosting 15 WR stars. We find WR stars present at both sub- and super-solar metalicities with WC stars favouring more metal-rich regions compared to WN stars. We investigate the association of WR stars with HII regions using archival HST imaging and conclude that the majority of WR stars are in or associated with HII regions. Of the 10 emission lines sources, only one appears to be unassociated with a star-forming region. Our spectroscopic survey provides confidence that our narrow-band photometric candidates are in fact bonafide WR stars, which will allow us to characterise the progenitors of any core-collapse supernovae that erupt in the future in M101
Persistence of the mitogenic response to platelet-derived growth factor (competence) does not reflect a long-term interaction between the growth factor and the target cell.
A multi-nation examination of the fatigue and recovery time course during the inaugural Under-18 Six Nations rugby union competition
The purpose of this study was to investigate the neuromuscular and perceptual fatigue responses of elite rugby players during the inaugural Under-18 (U18) Six Nations Festival. One hundred and thirty-three male players from five national squads (73 forwards, 60 backs) were examined during the competition. Each national squad was involved in three matches separated by 96 h each. Over the competition, players completed a daily questionnaire to monitor perceived well-being (WB) and performed daily countermovement jumps (CMJ) to assess neuromuscular function (NMF). Reductions in WB were substantial 24 h after the first and second match in forwards (d=0.77 ±0.21, p<0.0001; d=0.84±0.22, p< 0.001) and backs (d=0.89±0.22, p <0.0001; d=0.58±0.23, p<0.0001) but reached complete recovery in time for the subsequent match. Reductions in CMJ height were substantial 24 h after the first and second match for forwards (d=0.31±0.15, p=0.001; d=0.25±0.17, p=0.0205) and backs (d=0.40±0.17, p=0.0001; d=0.28±0.17, p=0.0062) and recovered at 48 h after match-play. Average WB and CMJ height attained complete recovery within matchday cycles in the investigated international competition. The findings of this study can be useful for practitioners and governing bodies involved with fixture scheduling and training prescription during competitive period
Bayesian analysis of Jolly-Seber type models; Incorporating heterogeneity in arrival and departure
We propose the use of finite mixtures of continuous distributions in modelling the process by which new individuals, that arrive in groups, become part of a wildlife population. We demonstrate this approach using a data set of migrating semipalmated sandpipers (Calidris pussila) for which we extend existing stopover models to allow for individuals to have different behaviour in terms of their stopover duration at the site. We demonstrate the use of reversible jump MCMC methods to derive posterior distributions for the model parameters and the models, simultaneously. The algorithm moves between models with different numbers of arrival groups as well as between models with different numbers of behavioural groups. The approach is shown to provide new ecological insights about the stopover behaviour of semipalmated sandpipers but is generally applicable to any population in which animals arrive in groups and potentially exhibit heterogeneity in terms of one or more other processes
Caste-specific demography and phenology in bumblebees; modelling BeeWalk data
We present novel dynamic mixture models for the monitoring of bumblebee populations on an
unprecedented geographical scale, motivated by the UK citizen science scheme BeeWalk. The models
allow us for the First time to estimate bumblebee phenology and within-season productivity, defined as
the number of individuals in each caste per colony in the population in that year, from citizen science
data. All of these parameters are estimated separately for each caste, giving a means of considerable
ecological detail in examining temporal changes in the complex life-cycle of a social insect in the wild.
Due to the dynamic nature of the models, we are able to produce population trends for a number of
UK bumblebee species using the available time-series. Via an additional simulation exercise, we show
the extent to which useful information will increase if the survey continues, and expands in scale,
as expected. Bumblebees are extraordinarily important components of the ecosystem, providing
pollination services of vast economic impact and functioning as indicator species for changes in climate
or land-use. Our results demonstrate the changes in both phenology and productivity between years
and provide an invaluable tool for monitoring bumblebee populations, many of which are in decline,
in the UK and around the world
Effects of growth rate, size, and light availability on tree survival across life stages: a demographic analysis accounting for missing values and small sample sizes.
The data set supporting the results of this article is available in the Dryad repository, http://dx.doi.org/10.5061/dryad.6f4qs. Moustakas, A. and Evans, M. R. (2015) Effects of
growth rate, size, and light availability on tree survival across life stages: a demographic analysis accounting for missing values.Plant survival is a key factor in forest dynamics and survival probabilities often vary across life stages. Studies specifically aimed at assessing tree survival are unusual and so data initially designed for other purposes often need to be used; such data are more likely to contain errors than data collected for this specific purpose
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