3,739 research outputs found
Aplicación de la topología molecular en la predicción de la inhibición de Trypanosoma cruzi Hexokinasa y un grupo de derivados bifosfonatos
A topological-mathematical model has been arranged to search for new derivatives of bisphosphonate compounds actingas inhibitors against Trypanosoma cruzi hexokinase. By using linear discriminant analysis, a four-variable function wasachieved allowing an accurate prediction of the IC50 for each compound of the training and test series. After carryingout a virtual screening based upon such a model, new structures potentially actives against T. cruzi are proposedSe ha desarrollado un modelo topológico-matemático para la búsqueda de nuevos derivados bisfosfonatos activosfrente a la hexokinasa de Trypanosoma cruzi. Utilizando el análisis lineal discriminante se ha seleccionado una funcióncon cuatro variables capaz de predecir adecuadamente la CI50 para cada compuesto de las series de entrenamientoy test. El modelo propuesto se ha aplicado a una librería molecular y se han propuesto nuevas estructuraspotencialmente activas frente a T. cruzi
H spectroscopy of the high-inclination black hole transient Swift J1357.2-0933 during quiescence
Swift J1357.2-0933 is a transient low-mass X-ray binary hosting a
stellar-mass black hole. The source exhibits optical dips and very broad
emission lines during both outburst and quiescence, which are thought to be the
result of a high orbital inclination. We present phase-resolved spectroscopy
obtained with the 10.4m Gran Telescopio Canarias (GTC). The spectra focus on
the spectral region during X-ray quiescence. The emission line is
exceptionally broad (full width at half maximum, FWHM > 4000 \AA), in agreement
with previous studies focused on . A two-Gaussian fit to the
prominent double-peaked profile reveals a periodic variability in the centroid
position of the line. We also produced a diagnostic diagram aimed at
constraining additional orbital parameters. Together, they allow us to
independently confirm the orbital period of the system using a new dataset
obtained five years after the previous outburst. However, our estimates for
both the systemic velocity and the radial velocity semi-amplitude of the black
hole reveal larger values than those found in previous studies. We argue that
this could be explained by the precession of the disc and the presence of a
hotspot. We found evidence of a narrow inner core in the double-peaked H
emission profile. We studied its evolution across the orbit, finding that it is
likely to result from the occultation of inner material by the outer rim bulge,
further supporting the high orbital inclination hypothesis.Comment: 6 pages, 4 figure
NATALIA: a satcom phased array in Ku-band
This article presents the prototype of an electronically steerable receive-only array antenna realised within the ESA-project NATALIA. This project is funded under contract number 18612/04/NL/US. The antenna is conceived for the reception of mobile satellite services in Ku-band and its design targets the market of automotive applications. The design of the prototype is based on an innovative polarisation agile phased array concept and exhibits an excellent RF-performance as well as a very compact envelope
Predictive score and probability of CTX-like toxicity in fish samples from the official control of ciguatera in the Canary Islands
This research identifies factors associated with the contamination by ciguatoxins (CTXs) in a population of fish and proposes a predictive score of the presence of CTX-like toxicity in amberjack samples from the official control program of ciguatera in the Canary Islands of the Directorate-General (DG) Fisheries (Canary Government). Out of the 970 samples of fish studied, 177 (18.2%) samples showed CTX-like toxicity. The fish were classified according to the species, amberjack (Seriola dumerili and S. rivoliana) (n = 793), dusky grouper (Epinephelus marginatus) (n = 145) and wahoo (Acanthocybium solandri) (n = 32). The data were separated by species category and statistically examined, resulting in 137 (17.3%) amberjack and 39 (26.9%) grouper samples showing CTX-like toxicity; regarding wahoo species, only 1 toxic sample (3.1%) was found. According to fishing location the contamination rates suggested grouping the islands in four clusters; namely: {El Hierro: HI; La Gomera: LG; La Palma: LP}, {Gran Canaria: GC; Tenerife: TF}, {Fuerteventura: FU} and {Lanzarote: LZ}. For the amberjack species, the multivariate logistic regression showed the factors that maintained independent association with the outcome, which were the warm season (OR = 3.617; 95% CI = 1.249–10.474), the weight (per kg, 1.102; 95% CI = 1.069–1.136) and the island of fish catching. A prediction score was obtained for the probability of contamination by CTX in amberjack fish samples. The area under de curve (AUC) obtained using the validation data was 0.747 (95% CI = 0.662–0.833). Regarding grouper species, the island of fishing was the only factor that showed significant differences associated with the presence of CTX-like toxicity. We provide herein data for a better management and prediction of ciguatera in the Canary Islands, suggesting a review of the minimum limits of fish weight established by the Canary Government for the control program.info:eu-repo/semantics/acceptedVersio
Transcriptome-Based Identification of a Functional Fasciola hepatica Carboxylesterase B
Bioinformatics analysis of the complete transcriptome of Fasciola hepatica, identified a total of ten putative carboxylesterase transcripts, including a 3146 bp mRNA transcript coding a 2205 bp open reading frame that translates into a protein of 735 amino acids, resulting in a predicted protein mass of 83.5 kDa and a putative carboxylesterase B enzyme. The gene coding for this enzyme was found in two reported F. hepatica complete genomes stretching 23,230 bp, containing two exons of 1282 and 1864 bp, respectively, as well as a 20,084 bp intron between the exons. The enzymatic activity was experimentally assayed on F. hepatica protein extracts by SDS-PAGE zymograms using synthetic chromogenic substrates, confirming both the theoretical molecular weight and carboxylesterase enzymatic activity. Further bioinformatics predicted that this enzyme is an integral component of the cellular membrane that should be active as a 167 kDa homodimer complex and polyacrylamide gel electrophoresis (PAGE) zymograms experiments confirmed the analysis. Additional bioinformatics analysis showed that DNA sequences that code for this particular enzyme are highly conserved in other parasitic trematodes, although they are labeled hypothetical proteins.Fil: Pedroza Gómez, Yaretzi J.. Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias; MéxicoFil: Cossio Bayugar, Raquel. Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias; MéxicoFil: Aguilar Díaz, Hugo. Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias; MéxicoFil: Scarcella, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Reynaud, Enrique. Universidad Nacional Autónoma de México; MéxicoFil: del Rayo Sanchez Carbente, María. Universidad Nacional Autónoma de México; MéxicoFil: Narváez Padilla, Verónica. Universidad Nacional Autónoma de México; MéxicoFil: Miranda Miranda, Estefan. Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias; Méxic
On measuring the covariance matrix of the nonlinear power spectrum from simulations
We show how to estimate the covariance of the power spectrum of a
statistically homogeneous and isotropic density field from a single periodic
simulation, by applying a set of weightings to the density field, and by
measuring the scatter in power spectra between different weightings. We
recommend a specific set of 52 weightings containing only combinations of
fundamental modes, constructed to yield a minimum variance estimate of the
covariance of power. Numerical tests reveal that at nonlinear scales the
variance of power estimated by the weightings method substantially exceeds that
estimated from a simple ensemble method. We argue that the discrepancy is
caused by beat-coupling, in which products of closely spaced Fourier modes
couple by nonlinear gravitational growth to the beat mode between them.
Beat-coupling appears whenever nonlinear power is measured from Fourier modes
with a finite spread of wavevector, and is therefore present in the weightings
method but not the ensemble method. Beat-coupling inevitably affects real
galaxy surveys, whose Fourier modes have finite width. Surprisingly, the
beat-coupling contribution dominates the covariance of power at nonlinear
scales, so that, counter-intuitively, it is expected that the covariance of
nonlinear power in galaxy surveys is dominated not by small scale structure,
but rather by beat-coupling to the largest scales of the survey.Comment: 19 pages, 4 figures. To appear in Monthly Notices of the Royal
Astronomical Society. Revised to match accepted versio
The PAU Survey: Photometric redshifts using transfer learning from simulations
In this paper we introduce the \textsc{Deepz} deep learning photometric
redshift (photo-) code. As a test case, we apply the code to the PAU survey
(PAUS) data in the COSMOS field. \textsc{Deepz} reduces the
scatter statistic by 50\% at compared to existing algorithms.
This improvement is achieved through various methods, including transfer
learning from simulations where the training set consists of simulations as
well as observations, which reduces the need for training data. The redshift
probability distribution is estimated with a mixture density network (MDN),
which produces accurate redshift distributions. Our code includes an
autoencoder to reduce noise and extract features from the galaxy SEDs. It also
benefits from combining multiple networks, which lowers the photo- scatter
by 10 percent. Furthermore, training with randomly constructed coadded fluxes
adds information about individual exposures, reducing the impact of photometric
outliers. In addition to opening up the route for higher redshift precision
with narrow bands, these machine learning techniques can also be valuable for
broad-band surveys.Comment: Accepted versio
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