384 research outputs found
Feedback control of unstable cellular solidification fronts
We present a numerical and experimental study of feedback control of unstable
cellular patterns in directional solidification (DS). The sample, a dilute
binary alloy, solidifies in a 2D geometry under a control scheme which applies
local heating close to the cell tips which protrude ahead of the other. For the
experiments, we use a real-time image processing algorithm to track cell tips,
coupled with a movable laser spot array device, to heat locally. We show,
numerically and experimentally, that spacings well below the threshold for a
period-doubling instability can be stabilized. As predicted by the numerical
calculations, cellular arrays become stable, and the spacing becomes uniform
through feedback control which is maintained with minimal heating.Comment: 4 pages, 4 figures, 1 tabl
A Comparative Look at Plea Bargaining in Australia, Canada, England, New Zealand, and the United States
In a world where the vast majority of criminal cases are resolved through some means other than the popularly depicted criminal trial, it is fundamental to a comprehensive understanding of comparative criminal procedure to study and appreciate the different mechanisms for criminal case resolution in different nations. This Article developed through a series of conversations (and ultimately a panel discussion) between six international criminal justice professionals - practicing attorneys, scholars, and judges - regarding the nature and effects of plea bargaining (and its comparative substitutes) in their respective countries. Providing a comparative look at different mechanisms for criminal case resolution, this Article examines the applicable practices and procedures in the common law nations of Australia, Canada, England, New Zealand, and the United States
A Comparative Examination of Police Interrogation of Criminal Suspects in Australia, Canada, England and Wales, New Zealand, and the United States
The interrogation process is central to the investigation and resolution of criminal matters throughout the world. It is fundamental to a comprehensive understanding of comparative criminal procedure to study and appreciate the different approaches to the interrogation process in different nations. This Article developed through a series of conversations between six international criminal justice professionals— practicing attorneys, scholars, and judges—regarding the interrogation practices and rules in their respective countries. Providing a comparative look at this important area, this Article examines the applicable practices and procedures in the common law nations of Australia, Canada, England and Wales, New Zealand, and the United States
Resolution of Linear Algebra for the Discrete Logarithm Problem Using GPU and Multi-core Architectures
In cryptanalysis, solving the discrete logarithm problem (DLP) is key to
assessing the security of many public-key cryptosystems. The index-calculus
methods, that attack the DLP in multiplicative subgroups of finite fields,
require solving large sparse systems of linear equations modulo large primes.
This article deals with how we can run this computation on GPU- and
multi-core-based clusters, featuring InfiniBand networking. More specifically,
we present the sparse linear algebra algorithms that are proposed in the
literature, in particular the block Wiedemann algorithm. We discuss the
parallelization of the central matrix--vector product operation from both
algorithmic and practical points of view, and illustrate how our approach has
contributed to the recent record-sized DLP computation in GF().Comment: Euro-Par 2014 Parallel Processing, Aug 2014, Porto, Portugal.
\<http://europar2014.dcc.fc.up.pt/\>
Complexity transitions in global algorithms for sparse linear systems over finite fields
We study the computational complexity of a very basic problem, namely that of
finding solutions to a very large set of random linear equations in a finite
Galois Field modulo q. Using tools from statistical mechanics we are able to
identify phase transitions in the structure of the solution space and to
connect them to changes in performance of a global algorithm, namely Gaussian
elimination. Crossing phase boundaries produces a dramatic increase in memory
and CPU requirements necessary to the algorithms. In turn, this causes the
saturation of the upper bounds for the running time. We illustrate the results
on the specific problem of integer factorization, which is of central interest
for deciphering messages encrypted with the RSA cryptosystem.Comment: 23 pages, 8 figure
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Energy and eventhood: the infrastructural set piece
‘Energy and Eventhood’ considers the relationship between infrastructure and the cinematic set piece. It proposes a working definition of the set piece as a distinctly (and perhaps excessively) effortful passage or sequence, and reflects on the tendency for narrative films to incorporate infrastructural sites and structures—such as bridges, dams and pipelines—into such set pieces. A number of writers on infrastructure, as both a cultural phenomenon and a representational object, have noted the aesthetic challenge of rendering it as visible and locatable; this article examines how that difficulty becomes manifest in the infrastructural set piece. It takes as its case studies Unstoppable (2010) and Night Moves (2013), two films noted for their distinctive rhythmic expressiveness, and each one deploying the convention of the set piece in ways which exemplify and reflect on the resistance of infrastructure to narrative containment
The effect of network topology on the stability of discrete state models of genetic control
Boolean networks have been proposed as potentially useful models for genetic
control. An important aspect of these networks is the stability of their
dynamics in response to small perturbations. Previous approaches to stability
have assumed uncorrelated random network structure. Real gene networks
typically have nontrivial topology significantly different from the random
network paradigm. In order to address such situations, we present a general
method for determining the stability of large Boolean networks of any specified
network topology and predicting their steady-state behavior in response to
small perturbations. Additionally, we generalize to the case where individual
genes have a distribution of `expression biases,' and we consider
non-synchronous update, as well as extension of our method to non-Boolean
models in which there are more than two possible gene states. We find that
stability is governed by the maximum eigenvalue of a modified adjacency matrix,
and we test this result by comparison with numerical simulations. We also
discuss the possible application of our work to experimentally inferred gene
networks.Comment: 25 pages, 4 figures; added supplementary information, fixed typos and
figure, reformatte
Mitral regurgitation due to caseous calcification of the mitral annulus: two case reports
Caseous calcification is a rare variant of mitral annular calcification, occurring in about 0.06% of echocardiographic studies performed. It is usually a benign lesion, but it should be differentiated by abscess and tumors. Echocardiography is the most sensitive method to identify caseous calcification which appears typically as a round, calcified mass with an echo-lucent, liquid-like inner part
Changes in visual function after intraocular pressure reduction using antiglaucoma medications
Purpose To evaluate the change in visual function after starting glaucoma treatment and correlate this to a decrease in intraocular pressure (IOP) in primary open-angle glaucoma patients.Methods A prospective, randomized clinical trial was carried out involving 54 glaucoma patients (54 eyes). After inclusion, patients randomly received timolol maleate 0.5%, brimonidine tartrate 0.2%, or travoprost 0.004% in one randomly selected eye. Patients underwent Goldmann applanation tonometry, visual acuity test, standard automated perimetry (SAP), visual quality perception test (visual analogue scale), and contrast sensitivity (CS) test, in a random order before and after the 4-week glaucoma treatment.Results There were statistically significant changes in IOP (mean change [standard deviation], 7.8 [3.6] mmHg, P 0.001), SAP mean deviation index (0.84 [2.45] dB, P = 0.02), visual quality perception (0.56 [1.93], P = 0.045), and CS at frequencies of 12 cycles/degree (0.10 [0.37], P = 0.03) and 18 cycles/degree (0.18 [0.42], P = 0.02) after the 4-week treatment when compared with baseline. No statistically significant differences were found between the treatment groups in visual function changes after treatment (P > 0.40). No significant correlations between IOP reduction and changes in visual function were found (P > 0.30).Conclusions Visual quality perception, visual field mean deviation index, and CS at higher frequencies improve after starting glaucoma therapy. However, no correlation was found between IOP reduction and changes in visual function, and no differences were found in visual function when the three medications studied were compared. Eye (2009) 23, 1081-1085; doi:10.1038/eye.2008.226; published online 1 August 2008Universidade Federal de São Paulo, Glaucoma Serv, Dept Ophthalmol, BR-01404001 São Paulo, BrazilUniversidade Federal de São Paulo, Glaucoma Serv, Dept Ophthalmol, BR-01404001 São Paulo, BrazilWeb of Scienc
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