2,444 research outputs found
‘Flint and Straw’ Interview with Jonathan Gibbs by Ana Ibarra
No full textELEPHANT 6, The Arts and Visual Culture Magazine, February 2011 – ‘Flint and Straw’ Interview with Jonathan Gibbs by Ana Ibarra, 6 pages, 8 Illustrations
Jonathan C. Gibbs
No full textPhotograph: Photographic reprint of Jonathan C. Gibbs. Jonathan C. Gibbs was the first African American Florida Superintendent of Public Instruction, serving from January 1873 to August 1874. He was also Florida Secretary of State from November 1868 to January 1873. Handwritten on reverse: Jonathan C. Gibbs. Undated.https://digitalcommons.unf.edu/eartha_images/1740/thumbnail.jp
The Collected Poems of Robert Frost with 23 Illustrations by Jonathan Gibbs.
No full textThe Collected Poems of Robert Frost with 23 Illustrations by Jonathan Gibbs.Introduction by Paul Muldoon. Published by Folio Society 2011. 6000 copies published and distributed in EU, USA, Canada & worldwide. <br/
A partially collapsed Gibbs sampler for Bayesian quantile regression
No full textWe introduce a set of new Gibbs sampler for Bayesian analysis of quantile re-gression model. The new algorithm, which partially collapsing an ordinary Gibbs sampler, is called Partially Collapsed Gibbs (PCG) sampler. Although the Metropolis-Hastings algorithm has been employed in Bayesian quantile regression, including
median regression, PCG has superior convergence properties to an ordinary Gibbs sampler. Moreover, Our PCG sampler algorithm, which is based on a theoretic derivation of an asymmetric Laplace as scale mixtures of normal distributions,
requires less computation than the ordinary Gibbs sampler and can significantly reduce the computation involved in approximating the Bayes Factor and marginal likelihood. Like the ordinary Gibbs sampler, the PCG sample can also be used
to calculate any associated marginal and predictive distributions. The quantile regression PCG sampler is illustrated by analysing simulated data and the data of length of stay in hospital. The latter provides new insight into hospital perfor-mance. C-code along with an R interface for our algorithms is publicly available
on request from the first author.
JEL classification: C11, C14, C21, C31, C52, C53
Mary Hester Gibbs Article
No full textA letter to the editor about Mary Hester Gibbs, the great grandmother of the author, Doris J. Millican
Techniques for the synchronisation and demodulation of fast frequency hopped M-ary frequency shift keying
No full textIn this thesis we consider the synchronisation and demodulation of fast frequency hopped M-ary FSK with convolutional coding in the presence of jamming, multiple access noise, frequency uncertainty and random frequency variations. We consider three modulation formats, 4-FSK, 8-FSK and 16-FSK and describe a family of 1/2 rate constraint length 7 symbol-based convolutional codes. We investigate the performance of the proposed systems with 2nd order diversity, in addition to the 1/2 rate encoding, and highlight the worst-case partial-band tone jammer waveform for such schemes. Consideration is given to a receiver based upon the offset FFT, where these transforms are then processed in order to achieve maximum a posteriori carier frequency synchronisation, demodulation and decoding of the received signal. Two hop-by-hop AGC techniques are described, the SNORM and the DMAX techniques; the former normalises the OFFT amplitudes with reference to the total power within the OFFT whilst the latter performs the normalisation based upon the maximum amplitude slot present within the OFFT. The worst-case partial-band tone jammer is generalised for the OFFT receiver when transform sizes exceed the modulation set size. A Viterbi frequency synchroniser is presented. This technique combines frequency synchronisation with the soft decision decoding of the convolutional code. By considering both the mean and the standard deviation of the signal slot amplitudes across the four OFFT slots which comprise each branch metric of the Viterbi decoding process, a novel modified metric is derived. This metric alters the worst-case partial-band jammer from a single tone to a more broad-band dammer waveform. An improvement in the worst-case partial-band tone jamming BER performance is experienced with all modulation formats for large OFFTs and for OFFTs of all sizes for modulation formats where M ≥ 8. The AWGN GER performance is degraded by 0.5-0.7 dB. The Viterbi frequency synchroniser is shown to degrade the BER peformance for 8-FSK by approximately 0.75 dB when compared to perfect carrier frequency synchronisation. The metric is also shown to increase the number of simultaneous users in an FFH 8-FSK multiple access environment, especially when the power control of the different accesses in the system is poor. Implementation of the synchroniser and metric calculation are investigated and the performance of 8-FSK with 4-bit quantisation of the soft decision information is shown to degrade the BER performance by 0.25 dB. Coarse code and carrier frequency synchronisation methods for spread spectrum communications in general are reviewed. The requirement for additional intermediate frequency tones in order to achieve frequency synchronisation is shown to be unnecessary when MFSK detection uses the OFFT. Two techniques for the synchronisation of fast frequency hopped MFSK are described and analysed in AWGN. These are the bandwidth identifcation algorithm and the tone folding detector. These are compared with a Viterbi based detector which exploits the structure which is inherent within the convolutionally encoded data sequence. The superiority of the Viterbi detector is shown and the technique is modified to utilise the modified metric calculation which was developed for demodulation. A jammer classifier is described, based upon mean output of the DMAX AGC in order to allow thresholding to be achieved in the presence of different jammer types.</p
12 Months of Scotland:12 Months of Scotland: le immagini della fantasia annual 2014/Exhibition, Publication, Symposium. Art directed by Monica Monachesi.
No full textCommissioned by SÀRMEDE, Treviso, as a collaborative project with Vivian French (ECA staff), as the writer of twelve texts to be illustrated by twelve illustrators, (students, graduates): Eilidh Muldoon, Laura Darling, Philip Longson, Stella Phipps, Kasia Matyjazsek, Jessica Kettle, Laura Clark, Alexander Jackson, Jonathan Gibbs, Cate James, Natalie Russel
A Hamilton-Jacobi point of view on mean-field Gibbs-non-Gibbs transitions
No full textWe study the loss, recovery, and preservation of differentiability of time-dependent large deviation rate functions. This study is motivated by mean-field Gibbs-non-Gibbs transitions. The gradient of the rate-function evolves according to a Hamiltonian flow. This Hamiltonian flow is used to analyze the regularity of the time-dependent rate function, both for Glauber dynamics for the Curie-Weiss model and Brownian dynamics in a potential. We extend the variational approach to this problem of time-dependent regularity in order to include Hamiltonian trajectories with a finite lifetime in closed domains with a boundary. This leads to new phenomena, such a recovery of smoothness. We hereby create a new and unifying approach for the study of mean-field Gibbs-non-Gibbs transitions, based on Hamiltonian dynamics and viscosity solutions of Hamilton-Jacobi equations
Jonathan C. Gibbs: Florida\u27s Only Negro Cabinet Member
No full textHistorians have contended that during the period of Reconstruction when the Republican party dominated the political stage in Florida, the state was controlled by incompetent, illiterate, and venal Negroes. A critical examination of primary sources, however, shows that this is not a valid conception. Negro office holders were always in a decided minority and among those who held office on the state and local level there were many capable men. The best example of a Florida Negro who disproves the stereotyped freedman politician is Jonathan C. Gibbs, one of the best educated and most cultured persons holding a political office
Blind deconvolution of sparse pulse sequences under a minimum distance constraint: a partially collapsed Gibbs sampler method
No full textFor blind deconvolution of an unknown sparse sequence convolved with an unknown pulse, a powerful Bayesian method employs the Gibbs sampler in combination with a Bernoulli–Gaussian prior modeling sparsity. In this paper, we extend this method by introducing a minimum distance constraint for the pulses in the sequence. This is physically relevant in applications including layer detection, medical imaging, seismology, and multipath parameter estimation. We propose a Bayesian method for blind deconvolution that is based on a modified Bernoulli–Gaussian prior including a minimum distance constraint factor. The core of our method is a partially collapsed Gibbs sampler (PCGS) that tolerates and even exploits the strong local dependencies introduced by the minimum distance constraint. Simulation results demonstrate significant performance gains compared to a recently proposed PCGS. The main advantages of the minimum distance constraint are a substantial reduction of computational complexity and of the number of spurious components in the deconvolution result
- …
