5,056 research outputs found
Quick-change absorption column
Column has end caps held in place by springs; prefilled packs of absorbent can be exchanged quickly. Both ends of metal or plastic body tube of size which can hold adequate amount of absorbent are machined to provide seat for perforated plate and groove for its spring retainer ring
Sparse image reconstruction on the sphere: analysis and synthesis
We develop techniques to solve ill-posed inverse problems on the sphere by
sparse regularisation, exploiting sparsity in both axisymmetric and directional
scale-discretised wavelet space. Denoising, inpainting, and deconvolution
problems, and combinations thereof, are considered as examples. Inverse
problems are solved in both the analysis and synthesis settings, with a number
of different sampling schemes. The most effective approach is that with the
most restricted solution-space, which depends on the interplay between the
adopted sampling scheme, the selection of the analysis/synthesis problem, and
any weighting of the l1 norm appearing in the regularisation problem. More
efficient sampling schemes on the sphere improve reconstruction fidelity by
restricting the solution-space and also by improving sparsity in wavelet space.
We apply the technique to denoise Planck 353 GHz observations, improving the
ability to extract the structure of Galactic dust emission, which is important
for studying Galactic magnetism.Comment: 11 pages, 6 Figure
Is the Cure Worse Than the Disease? An Overview of the Patent Reform Act of 2005, 5 J. Marshall Rev. Intell. Prop. L. 55 (2005)
As a result of pressures from various groups and issues surrounding the current patent system, representative Lamar Smith introduced a bill which overhauls multiple aspects of patent practice. The patent reform act is designed to please or compromise between various industry groups while at the same time invigorating the patent system. Specifically, the Patent Reform Act proposes changes to the procedures for filing application, how the applications are filed and even how patents are enforced. In addition to the major publicized changes the Patent Reform Act proposes other alterations that, while receiving less notice, have just as much practical effect. This article will discuss the changes proposed by the Patent Reform Act as well as their practical consequences
Spherical Needlets for CMB Data Analysis
We discuss Spherical Needlets and their properties. Needlets are a form of
spherical wavelets which do not rely on any kind of tangent plane approximation
and enjoy good localization properties in both pixel and harmonic space;
moreover needlets coefficients are asymptotically uncorrelated at any fixed
angular distance, which makes their use in statistical procedures very
promising. In view of these properties, we believe needlets may turn out to be
especially useful in the analysis of Cosmic Microwave Background (CMB) data on
the incomplete sky, as well as of other cosmological observations. As a final
advantage, we stress that the implementation of needlets is computationally
very convenient and may rely completely on standard data analysis packages such
as HEALPix.Comment: 7 pages, 7 figure
Sparse Bayesian mass-mapping with uncertainties: hypothesis testing of structure
A crucial aspect of mass-mapping, via weak lensing, is quantification of the
uncertainty introduced during the reconstruction process. Properly accounting
for these errors has been largely ignored to date. We present results from a
new method that reconstructs maximum a posteriori (MAP) convergence maps by
formulating an unconstrained Bayesian inference problem with Laplace-type
-norm sparsity-promoting priors, which we solve via convex
optimization. Approaching mass-mapping in this manner allows us to exploit
recent developments in probability concentration theory to infer theoretically
conservative uncertainties for our MAP reconstructions, without relying on
assumptions of Gaussianity. For the first time these methods allow us to
perform hypothesis testing of structure, from which it is possible to
distinguish between physical objects and artifacts of the reconstruction. Here
we present this new formalism, demonstrate the method on illustrative examples,
before applying the developed formalism to two observational datasets of the
Abel-520 cluster. In our Bayesian framework it is found that neither Abel-520
dataset can conclusively determine the physicality of individual local massive
substructure at significant confidence. However, in both cases the recovered
MAP estimators are consistent with both sets of data
Strength in diversity: enhancing learning in vocationally-orientated, master's level courses
Postgraduate education in geography, especially at the Master’s level, is undergoing significant changes in the developed world. There is an expansion of vocationally-oriented degree programmes, increasing recruitment of international students, integration of work place skills, and the engagement of non-traditional postgraduate students as departments respond to policies for a more ‘inclusive’ higher education. This paper sets the context by outlining some programmatic changes in selected countries (Australia, the UK, and the USA). We briefly reflect on how postgraduate ‘bars’ or ‘levels’ are defined and explore in detail what ‘diversity’ or ‘heterogeneity’ means in these new postgraduate settings. The paper then explores some examples of practice drawn from our own experiences, whilst recognising that relevance will vary in other contexts. Finally we consider how diversity can be harnessed as a strength that has potential to enhance taught elements of contemporary postgraduate education in and beyond the discipline
A Combination Atmospheric Pressure LC/MS:GC/MS Ion Source: Advantages of Dual AP-LC/MS:GC/MS Instrumentation
Modification of commercial LC/MS instrumentation to allow both atmospheric pressure (AP) LC/MS and GC/MS is described. Advantages of this additional capability versus LC/MS alone include higher chromatographic resolution in the GC versus LC mode, greater peak capacity for complex mixture analysis, higher sensitivity for a variety of volatile compounds, and the ability to observe compounds of low polarity that are not readily observed in LC/MS. Advantages over conventional GC/MS include the ability to use higher carrier gas flow and shorter columns for passing less volatile materials through the gas chromatograph, selective ionization, and rapid switching between positive and negative ion modes. Other advantages include application of the enhanced capabilities of LC/MS instrumentation to GC/MS analyses such as cone voltage fragmentation, MSn, high mass resolution, and accurate mass measurement. Limitations of APGC/MS include the inability to observe saturated hydrocarbon and certain other highly nonpolar compounds and less odd-electron fragmentation for computer aided library searching. For some analyses, the limitation related to ionization of highly nonpolar compounds is advantageous, as is the simplified mass spectrum and easy molecular weight identification that results from less fragmentation observed in the AP ionization mode
Sparse image reconstruction on the sphere: implications of a new sampling theorem
We study the impact of sampling theorems on the fidelity of sparse image
reconstruction on the sphere. We discuss how a reduction in the number of
samples required to represent all information content of a band-limited signal
acts to improve the fidelity of sparse image reconstruction, through both the
dimensionality and sparsity of signals. To demonstrate this result we consider
a simple inpainting problem on the sphere and consider images sparse in the
magnitude of their gradient. We develop a framework for total variation (TV)
inpainting on the sphere, including fast methods to render the inpainting
problem computationally feasible at high-resolution. Recently a new sampling
theorem on the sphere was developed, reducing the required number of samples by
a factor of two for equiangular sampling schemes. Through numerical simulations
we verify the enhanced fidelity of sparse image reconstruction due to the more
efficient sampling of the sphere provided by the new sampling theorem.Comment: 11 pages, 5 figure
Implications for compressed sensing of a new sampling theorem on the sphere
A sampling theorem on the sphere has been developed recently, requiring half
as many samples as alternative equiangular sampling theorems on the sphere. A
reduction by a factor of two in the number of samples required to represent a
band-limited signal on the sphere exactly has important implications for
compressed sensing, both in terms of the dimensionality and sparsity of
signals. We illustrate the impact of this property with an inpainting problem
on the sphere, where we show the superior reconstruction performance when
adopting the new sampling theorem compared to the alternative.Comment: 1 page, 2 figures, Signal Processing with Adaptive Sparse Structured
Representations (SPARS) 201
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