250 research outputs found
On the asymptotic and practical complexity of solving bivariate systems over the reals
This paper is concerned with exact real solving of well-constrained,
bivariate polynomial systems. The main problem is to isolate all common real
roots in rational rectangles, and to determine their intersection
multiplicities. We present three algorithms and analyze their asymptotic bit
complexity, obtaining a bound of \sOB(N^{14}) for the purely projection-based
method, and \sOB(N^{12}) for two subresultant-based methods: this notation
ignores polylogarithmic factors, where bounds the degree and the bitsize of
the polynomials. The previous record bound was \sOB(N^{14}).
Our main tool is signed subresultant sequences. We exploit recent advances on
the complexity of univariate root isolation, and extend them to sign evaluation
of bivariate polynomials over two algebraic numbers, and real root counting for
polynomials over an extension field. Our algorithms apply to the problem of
simultaneous inequalities; they also compute the topology of real plane
algebraic curves in \sOB(N^{12}), whereas the previous bound was
\sOB(N^{14}).
All algorithms have been implemented in MAPLE, in conjunction with numeric
filtering. We compare them against FGB/RS, system solvers from SYNAPS, and
MAPLE libraries INSULATE and TOP, which compute curve topology. Our software is
among the most robust, and its runtimes are comparable, or within a small
constant factor, with respect to the C/C++ libraries.
Key words: real solving, polynomial systems, complexity, MAPLE softwareComment: 17 pages, 4 algorithms, 1 table, and 1 figure with 2 sub-figure
Uniform convergence of discrete curvatures from nets of curvature lines
We study discrete curvatures computed from nets of curvature lines on a given
smooth surface, and prove their uniform convergence to smooth principal
curvatures. We provide explicit error bounds, with constants depending only on
properties of the smooth limit surface and the shape regularity of the discrete
net.Comment: 21 pages, 8 figure
Does training with amplitude modulated tones affect tone-vocoded speech perception?
Temporal-envelope cues are essential for successful speech perception. We asked here whether training on stimuli containing temporal-envelope cues without speech content can improve the perception of spectrally-degraded (vocoded) speech in which the temporal-envelope (but not the temporal fine structure) is mainly preserved. Two groups of listeners were trained on different amplitude-modulation (AM) based tasks, either AM detection or AM-rate discrimination (21 blocks of 60 trials during two days, 1260 trials; frequency range: 4Hz, 8Hz, and 16Hz), while an additional control group did not undertake any training. Consonant identification in vocoded vowel-consonant-vowel stimuli was tested before and after training on the AM tasks (or at an equivalent time interval for the control group). Following training, only the trained groups showed a significant improvement in the perception of vocoded speech, but the improvement did not significantly differ from that observed for controls. Thus, we do not find convincing evidence that this amount of training with temporal-envelope cues without speech content provide significant benefit for vocoded speech intelligibility. Alternative training regimens using vocoded speech along the linguistic hierarchy should be explored
A new method for 2D gel spot alignment: application to the analysis of large sample sets in clinical proteomics
<p>Abstract</p> <p>Background</p> <p>In current comparative proteomics studies, the large number of images generated by 2D gels is currently compared using spot matching algorithms. Unfortunately, differences in gel migration and sample variability make efficient spot alignment very difficult to obtain, and, as consequence most of the software alignments return noisy gel matching which needs to be manually adjusted by the user.</p> <p>Results</p> <p>We present Sili2DGel an algorithm for automatic spot alignment that uses data from recursive gel matching and returns meaningful Spot Alignment Positions (SAP) for a given set of gels. In the algorithm, the data are represented by a graph and SAP by specific subgraphs. The results are returned under various forms (clickable synthetic gel, text file, etc.). We have applied Sili2DGel to study the variability of the urinary proteome from 20 healthy subjects.</p> <p>Conclusion</p> <p>Sili2DGel performs noiseless automatic spot alignment for variability studies (as well as classical differential expression studies) of biological samples. It is very useful for typical clinical proteomic studies with large number of experiments.</p
Troubles du comportement après traumatisme crânien : quels symptômes et quelles évaluations ?
Non-pharmacological treatment for behavioural troubles in brain injury patients. Review of literature
Survey of the analysis of continuous conformational variability of biological macromolecules by electron microscopy
Single-particle analysis by electron microscopy is a well established technique
for analyzing the three-dimensional structures of biological macromolecules.
Besides its ability to produce high-resolution structures, it also provides insights
into the dynamic behavior of the structures by elucidating their conformational
variability. Here, the different image-processing methods currently available to
study continuous conformational changes are reviewedThe authors would like to acknowledge support from the
Spanish Ministry of Economy and Competitiveness through
grants BIO2013-44647-R and BIO2016-76400-R (AEI/
FEDER, UE), Comunidad Autonoma de Madrid through
grant S2017/BMD-3817, Instituto de Salud Carlos III through
grants PT13 /0001/0009 and PT17/0009/0010,the European
Union (EU) and Horizon 2020 through West-Life (EINFRA-
2015-1, Proposal 675858), CORBEL (INFRADEV-1-2014-1,
Proposal 654248), ELIXIR–EXCELERATE (INFRADEV-3-
2015, Proposal 676559), iNEXT (INFRAIA-1-2014-2015,
Proposal 653706), EOSCpilot (INFRADEV-04-2016,
Proposal 739563) and the National Institutes of Health (P41
GM 103712) (IB
The screen test 1915–1930:how stars were born
This article examines the emergence of the screen test as a cultural phenomenon during the silent era in the US and Europe and its role in the development of the star system. The lore that grew up around the screen test almost from its inception held out the possibility for members of the public to cross a threshold into the rarefied world of celebrity. The screen test itself is situated in the liminal space not only between audience and actor, but also between fiction and non-fiction, Europe and Hollywood, the silent era and the talkies, and the public and private spheres. In order to trace the ways in which the screen test as such was narrativized and conceptualized in its foundational stages, this article will analyse accounts from Hollywood and European fan magazines of the silent era, including articles, short fiction, and early cinema apocrypha. The article culminates in a discussion of the film Prix de Beauté / Beauty Prize (Augusto Genina, 1930), which starred Louise Brooks, herself a transnational film icon whose film career spanned the divide between Hollywood and Europe. The film’s final scene, in which a beauty queen is shot dead by her jealous husband as she watches a screen test of herself, has been invoked by a number of film scholars as an allegory of the work performed by cinema, which preserves and disseminates the image of the star far beyond the actor’s physical presence. Speaking to historical conditions of star-making while also capturing its resonance in cultural mythology, the conclusion of Prix de Beauté allows us to consider the origins and functions of screen test discourse itself
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