1,332 research outputs found
Influence of Water Temperature on the MXR Activity and P-glycoprotein Expression in the Freshwater Snail, Physa acuta (Draparnaud, 1805)
P-glycoprotein (P-gp) mediated multixenobioticresistance (MXR) is a mechanism analogous to multidrug resistance, which has been extensivelycharacterized in mammalian tumours. The expression and function of the MXR mechanism hasbeen demonstrated in numerous aquatic organisms and has been proposed as a biomarker forpollution assessment. A close relationship between thermal stress and MXR response has beenreported in some aquatic organisms. Seasonal studies in freshwater organisms are scarce andconducted mainly in zebra mussel (Dreissena polymorpha), whose presence has not been reportedin South America. The general purpose of the present study was to evaluate seasonal variation of abiomarker, the MXR mechanism, in the worldwide distributed freshwater snail P. acuta. Weanalyzed the in situ influence of temperature on the biomarker response over an 18-month fieldstudy. MXR defence system was evaluated by a combination of functional assays (RB accumulation)and molecular approaches to analyse P-gp expression. The results demonstrated a linear correlationbetween MXR response, at activity and expression level, and water temperature at sample site, in P.acuta snails. The characterization of the MXR system in worldwide distributed species, includingthe study of their seasonal fluctuations, could contribute to the increasing interest to incorporate thisbiomarker to provide an integrated assessment of mussel health status. This work supports thepossible use of P. acuta snails with this purpose and also highlights that the occurrence of variationsin MXR response related to water temperature has to be taken into account in the interpretation ofin situ monitoring studiesFil: Horak, Cristina Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia ; ArgentinaFil: Assef, Yanina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia ; Argentin
Predicting customer's gender and age depending on mobile phone data
In the age of data driven solution, the customer demographic attributes, such
as gender and age, play a core role that may enable companies to enhance the
offers of their services and target the right customer in the right time and
place. In the marketing campaign, the companies want to target the real user of
the GSM (global system for mobile communications), not the line owner. Where
sometimes they may not be the same. This work proposes a method that predicts
users' gender and age based on their behavior, services and contract
information. We used call detail records (CDRs), customer relationship
management (CRM) and billing information as a data source to analyze telecom
customer behavior, and applied different types of machine learning algorithms
to provide marketing campaigns with more accurate information about customer
demographic attributes. This model is built using reliable data set of 18,000
users provided by SyriaTel Telecom Company, for training and testing. The model
applied by using big data technology and achieved 85.6% accuracy in terms of
user gender prediction and 65.5% of user age prediction. The main contribution
of this work is the improvement in the accuracy in terms of user gender
prediction and user age prediction based on mobile phone data and end-to-end
solution that approaches customer data from multiple aspects in the telecom
domain
Customer churn prediction in telecom using machine learning and social network analysis in big data platform
Customer churn is a major problem and one of the most important concerns for
large companies. Due to the direct effect on the revenues of the companies,
especially in the telecom field, companies are seeking to develop means to
predict potential customer to churn. Therefore, finding factors that increase
customer churn is important to take necessary actions to reduce this churn. The
main contribution of our work is to develop a churn prediction model which
assists telecom operators to predict customers who are most likely subject to
churn. The model developed in this work uses machine learning techniques on big
data platform and builds a new way of features' engineering and selection. In
order to measure the performance of the model, the Area Under Curve (AUC)
standard measure is adopted, and the AUC value obtained is 93.3%. Another main
contribution is to use customer social network in the prediction model by
extracting Social Network Analysis (SNA) features. The use of SNA enhanced the
performance of the model from 84 to 93.3% against AUC standard. The model was
prepared and tested through Spark environment by working on a large dataset
created by transforming big raw data provided by SyriaTel telecom company. The
dataset contained all customers' information over 9 months, and was used to
train, test, and evaluate the system at SyriaTel. The model experimented four
algorithms: Decision Tree, Random Forest, Gradient Boosted Machine Tree "GBM"
and Extreme Gradient Boosting "XGBOOST". However, the best results were
obtained by applying XGBOOST algorithm. This algorithm was used for
classification in this churn predictive model.Comment: 24 pages, 14 figures. PDF https://rdcu.be/budK
The Angular Clustering of WISE-Selected AGN: Different Haloes for Obscured and Unobscured AGN
We calculate the angular correlation function for a sample of 170,000 AGN
extracted from the Wide-field Infrared Survey Explorer (WISE) catalog, selected
to have red mid-IR colors (W1 - W2 > 0.8) and 4.6 micron flux densities
brighter than 0.14 mJy). The sample is expected to be >90% reliable at
identifying AGN, and to have a mean redshift of z=1.1. In total, the angular
clustering of WISE-AGN is roughly similar to that of optical AGN. We
cross-match these objects with the photometric SDSS catalog and distinguish
obscured sources with (r - W2) > 6 from bluer, unobscured AGN. Obscured sources
present a higher clustering signal than unobscured sources. Since the host
galaxy morphologies of obscured AGN are not typical red sequence elliptical
galaxies and show disks in many cases, it is unlikely that the increased
clustering strength of the obscured population is driven by a host galaxy
segregation bias. By using relatively complete redshift distributions from the
COSMOS survey, we find obscured sources at mean redshift z=0.9 have a bias of b
= 2.9 \pm 0.6 and are hosted in dark matter halos with a typical mass of
log(M/M_odot)~13.5. In contrast, unobscured AGN at z~1.1 have a bias of b = 1.6
\pm 0.6 and inhabit halos of log(M/M_odot)~12.4. These findings suggest that
obscured AGN inhabit denser environments than unobscured AGN, and are difficult
to reconcile with the simplest AGN unification models, where obscuration is
driven solely by orientation.Comment: Accepted for publication in ApJ. 13 pages, 15 figure
Solution of Two Dimensional Poisson Equation Using Finite Difference Method with Uniform and Non-uniform Mesh Size
This study focus on the finite difference approximation of two dimensional Poisson equation with uniform and non-uniform mesh size. The Poisson equation with uniform and non-uniform mesh size is a very powerful tool for modeling the behavior of electro-static systems, but unfortunately may not be solved analytically for very simplified models. Consequently, numerical simulation must be utilized in order to model the behavior of complex geometries with practical value. In most engineering problems are also coming from steady reaction-diffusion and heat transfer equation, in elasticity, fluid mechanics, electrostatics etc. the solution of meshing grid is non-uniform and uniform where fine grid is identified at the sensitive area of the simulation and coarse grid at the normal area.The discretization of non-uniform grid is done using Taylor expansion series. The purpose of such discretization is to transform the calculus problem to numerical form (as discrete equation). Therefore, in this study the two dimensional Poisson equation is discretazi with uniform and non-uniform mesh size using finite difference method for the comparison purpose. More over we also examine the ways that the two dimensional Poisson equation can be approximated by finite difference over non-uniform meshes, As result we obtain that for uniformly distributed gird point the finite difference method is very simple and sufficiently stable and converge to the exact solution whereas in non-uniformly distributed grid point the finite difference method is less stable, convergent and time consuming than the uniformly distributed grid points. Keywords: Finite difference method, two dimensional Poisson equations, Uniform mesh size, Non-uniform mesh size, Convergence, Stability, Consistence. DOI: 10.7176/APTA/79-01 Publication date:September 30th 2019
De FC à MAC : un algorithme paramétrable pour la résolution des CSP
http://www710.univ-lyon1.fr/~csolnonBeaucoup d'algorithmes de résolution de Problèmes de Satisfaction de Contraintes ont été proposés ces dernières années. Parmi ces algorithmes nous pouvons mentionner les deux les plus populaires et les plus étudiés : le Forward-Checking (FC) et Maintaining Arc-Consistency (MAC). Dans ce papier, nous étudions ces deux algorithmes et nous réévaluons leurs performances sur des problèmes générés aléatoirement. Précisément, nous montrons expérimentalement que FC est meilleur que MAC sur des CSP difficiles dont le graphe de contraintes est très dense et la dureté des contraintes est faible. En revanche, MAC se montre plus performant que FC sur des problèmes difficiles avec un graphe de contraintes peu dense et une dureté élevée. Ces résultats montrent que le maintien de l'Arc-consistance pendant la recherche peut être une perte de temps. Ensuite, Nous proposons une approche générique qui permet, pendant la recherche, un maintien partiel et paramétrable de la consistance locale
Gap and Overlap Detection in Automated Fiber Placement
The identification and correction of manufacturing defects, particularly gaps
and overlaps, are crucial for ensuring high-quality composite parts produced
through Automated Fiber Placement (AFP). These imperfections are the most
commonly observed issues that can significantly impact the overall quality of
the composite parts. Manual inspection is both time-consuming and
labor-intensive, making it an inefficient approach. To overcome this challenge,
the implementation of an automated defect detection system serves as the
optimal solution. In this paper, we introduce a novel method that uses an
Optical Coherence Tomography (OCT) sensor and computer vision techniques to
detect and locate gaps and overlaps in composite parts. Our approach involves
generating a depth map image of the composite surface that highlights the
elevation of composite tapes (or tows) on the surface. By detecting the
boundaries of each tow, our algorithm can compare consecutive tows and identify
gaps or overlaps that may exist between them. Any gaps or overlaps exceeding a
predefined tolerance threshold are considered manufacturing defects. To
evaluate the performance of our approach, we compare the detected defects with
the ground truth annotated by experts. The results demonstrate a high level of
accuracy and efficiency in gap and overlap segmentation
Evolution of the UV Excess in Early-Type Galaxies
We examine the UV emission from luminous early-type galaxies as a function of
redshift. We perform a stacking analysis using Galaxy Evolution Explorer
(GALEX) images of galaxies in the NOAO Deep Wide Field Survey (NDWFS) Bo\"otes
field and examine the evolution in the UV colors of the average galaxy. Our
sample, selected to have minimal ongoing star formation based on the optical to
mid-IR SEDs of the galaxies, includes 1843 galaxies spanning the redshift range
. We find evidence that the strength of the UV excess
decreases, on average, with redshift, and our measurements also show moderate
disagreement with previous models of the UV excess. Our results show little
evolution in the shape of the UV continuum with redshift, consistent either
with the binary model for the formation of Extreme Horizontal Branch (EHB)
stars or with no evolution in EHB morphology with look-back time. However, the
binary formation model predicts that the strength of the UV excess should also
be relatively constant, in contradiction with our measured results. Finally, we
see no significant influence of a galaxy's environment on the strength of its
UV excess.Comment: 30 pages, 10 figures; accepted by ApJ. Modified from original version
to reflect referee's comment
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