498 research outputs found
From music to mathematics and backwards: introducing algebra, topology and category theory into computational musicology
International audienceDespite a long historical relationship between mathematics and music, the interest of mathematicians is a recent phenomenon. In contrast to statistical methods and signal-based approaches currently employed in MIR (Music Information Research), the research project described in this paper stresses the necessity of introducing a structural multidisciplinary approach into computational musicology making use of advanced mathematics. It is based on the interplay between three main mathematical disciplines: algebra, topology and category theory. It therefore opens promising perspectives on important prevailing challenges, such as the automatic classification of musical styles or the solution of open mathematical conjectures, asking for new collaborations between mathematicians, computer scientists, musicologists, and composers. Music can in fact occupy a strategic place in the development of mathematics since music-theoretical constructions can be used to solve open mathematical problems. The SMIR project also differs from traditional applications of mathematics to music in aiming to build bridges between different musical genres, ranging from contemporary art music to popular music, including rock, pop, jazz and chanson. Beyond its academic ambition, the project carries an important societal dimension stressing the cultural component of 'mathemusical' research, that naturally resonates with the underlying philosophy of the âImagine Mathsâconference series. The article describes for a general public some of the most promising interdisciplinary research lines of this project
Combinatorial activity of flavonoids with antibiotics against drug resistant Staphylococcus aureus
The use of resistance-modifying agents is a potential strategy that is used to prolong the effective life of antibiotics in the face of increasing antibiotic resistance. Since certain flavonoids are potent bacterial efflux pump inhibitors, we assessed morin, rutin, quercetin, hesperidin, and (+)-catechin for their combined activity with the antibiotics ciprofloxacin, tetracycline, erythromycin, oxacillin, and ampicillin against drug-resistant strains of Staphylococcus aureus, including methicillin-resistant S. aureus. Four established methods were used to determine the combined efficacy of each combination: microdilution checkerboard assays, time-kill determinations, the Etest, and dual disc-diffusion methods. The cytotoxicity of the flavonoids was additionally evaluated in a mouse fibroblast cell line. Quercetin and its isomer morin decreased by 3- to 16-fold the minimal inhibitory concentration of ciprofloxacin, tetracycline, and erythromycin against some S. aureus strains. Rutin, hesperidin, and (+)-catechin did not promote any potentiation of antibiotics. Despite the potential cytotoxicity of these phytochemicals at a high concentration (fibroblast IC50 of 41.8 and 67.5mg/L, respectively), quercetin is commonly used as a supplement for several therapeutic purposes. All the methods, with exception of the time-kill assay, presented a high degree of congruence without any apparent strain specificity.This work was supported by Operational Program for
Competitiveness FactorsâCOMPETE, FCT/MEC (PIDDAC),
and FEDER through Projects BioresistâPTDC/EBB-EBI/
105085/2008; PhytodisinfectantsâPTDC/DTP-SAP/1078/
2012 (COMPETE: FCOMP-01-0124-FEDER-028765) and
the PhD grants awarded to Ana Abreu (SFRH/BD/84393/
2012) and Anabela Borges (SFRH/BD/63398/2009). The
authors are very grateful to Professor Simon Gibbons (De-
partment of Pharmaceutical and Biological Chemistry, The
School of Pharmacy, UCL School of Pharmacy, London) for
providing the bacterial strains.info:eu-repo/semantics/publishedVersio
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
First observation of the decay and a measurement of the ratio of branching fractions
The first observation of the decay using
data collected by the LHCb detector at a centre-of-mass energy of 7 TeV,
corresponding to an integrated luminosity of 36 pb, is reported. A
signal of events is obtained and the absence of signal is
rejected with a statistical significance of more than nine standard deviations.
The branching fraction is measured relative to
that of : , where the first uncertainty is statistical, the second systematic and
the third is due to the uncertainty on the ratio of the and
hadronisation fractions.Comment: 10 pages, 3 figures, submitted to Phys. Lett. B; ISSN 0370-269
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Model-independent search for CP violation in D0âKâK+ÏâÏ+ and D0âÏâÏ+Ï+Ïâ decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states KâK+ÏâÏ+ and ÏâÏ+Ï+Ïâ is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fbâ1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the KâK+ÏâÏ+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the ÏâÏ+Ï+Ïâ final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
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