The largest earthquakes in Algeria in the modern period: the El Asnam and Zemmouri-Boumerd s faults

Algeria has experienced many destructive earthquakes during the last few centuries (e.g., Ayadi and Bezzeghoud, 2015). The city of El Asnam (formerly Orléanville, today Chlef) was severely damaged in 1954 and 1980 by magnitude 6.7 and 7.3 earthquakes, respectively. On October 10, 1989, a magnitude 5.9 earthquake struck the Mont Chenoua-Tipasa coastal area approximately 150 km west of Zemmouri, which is where the May 21, 2003 earthquake occurred (Mw6.8). Many other large historical and instrumental earthquakes have severely damaged the coastal cities of Algeria over the last few centuries (i.e., around Algiers, Oran, Mascara, Djidjelli, Constantine and Bejaia). These earthquakes suggest active deformation of the margin in conjunction with the clear offshore extent of active coastal faults. According to several studies, the main active geological structures around El Asnam, Algiers, Zemmouri and Boumerdès have experienced several disastrous earthquakes. Many other earthquakes have occurred in and around the Chlef and Mitidja Basins, underlining the seismic activity in the area. In this chapter, we highlight the main characteristics of the two largest earthquakes that have occurred in Algeria in the modern period: the El Asnam earthquakes of September 9 (Mw6.7) and October 10 1980 (Mw7.3), and the Zemmouri-Boumerdès earthquake of May 21, 2003, (Mw6.8)

Arabic Text Classification Framework Based on Latent Dirichlet Allocation

In this paper, we present a new algorithm based on the LDA (Latent Dirichlet Allocation) and the Support Vector Machine (SVM) used in the classification of Arabic texts.Current research usually adopts Vector Space Model to represent documents in Text Classification applications. In this way, document is coded as a vector of words; n-grams. These features cannot indicate semantic or textual content; it results in huge feature space and semantic loss. The proposed model in this work adopts a “topics” sampled by LDA model as text features. It effectively avoids the above problems. We extracted significant themes (topics) of all texts, each theme is described by a particular distribution of descriptors, then each text is represented on the vectors of these topics. Experiments are conducted using an in-house corpus of Arabic texts. Precision, recall and F-measure are used to quantify categorization effectiveness. The results show that the proposed LDA-SVM algorithm is able to achieve high effectiveness for Arabic text classification task (Macro-averaged F1 88.1% and Micro-averaged F1 91.4%)

Toxoplasma gondii infection and toxoplasmosis in North Africa: a review

Toxoplasmosis is an important zoonosis caused by an obligate intracellular parasitic protozoan, Toxoplasma gondii. The disease is distributed worldwide and can affect all warm-blooded vertebrates, including humans. The present review aimed to collect, compile and summarize the data on the prevalence of T. gondii infection in humans and animals in the five North African countries (Morocco, Algeria, Tunisia, Libya and Egypt). Published data from national and international databases were used. Distribution patterns and risk factors for T. gondii infection are discussed, focusing on biotic and abiotic factors. This review is a comprehensive epidemiological analysis of T. gondii infection in North Africa and will therefore be a useful tool for researchers. It can also be used to propose or enhance appropriate national toxoplasmosis control programs

A biclustering algorithm based on a Bicluster Enumeration Tree: application to DNA microarray data

<p>Abstract</p> <p>Background</p> <p>In a number of domains, like in DNA microarray data analysis, we need to cluster simultaneously rows (genes) and columns (conditions) of a data matrix to identify groups of rows coherent with groups of columns. This kind of clustering is called <it>biclustering</it>. Biclustering algorithms are extensively used in DNA microarray data analysis. More effective biclustering algorithms are highly desirable and needed.</p> <p>Methods</p> <p>We introduce <it>BiMine</it>, a new enumeration algorithm for biclustering of DNA microarray data. The proposed algorithm is based on three original features. First, <it>BiMine </it>relies on a new evaluation function called <it>Average Spearman's rho </it>(ASR). Second, <it>BiMine </it>uses a new tree structure, called <it>Bicluster Enumeration Tree </it>(BET), to represent the different biclusters discovered during the enumeration process. Third, to avoid the combinatorial explosion of the search tree, <it>BiMine </it>introduces a parametric rule that allows the enumeration process to cut tree branches that cannot lead to good biclusters.</p> <p>Results</p> <p>The performance of the proposed algorithm is assessed using both synthetic and real DNA microarray data. The experimental results show that <it>BiMine </it>competes well with several other biclustering methods. Moreover, we test the biological significance using a gene annotation web-tool to show that our proposed method is able to produce biologically relevant biclusters. The software is available upon request from the authors to academic users.</p

The history of seismology and historical seismicity in Algeria: an overview

Algeria is one of the most seismically active areas along the Nubia-Eurasia convergent plates boundary. It is well known that the instrumental records of seismic events are incomplete because of inadequate instrumentation and the poor coverage of seismogenic areas from 1900 until the installation in 1992 of the Algerian Telemetered Seismological Network. The available catalogues of the seismicity of Algeria, including several published research papers on the same topic, reported numerous destructive earthquakes striking several regions, particularly along the coast [Oran, Mascara, Chlef (Former Orléansville and El Asnam), Tipasa-Chenoua, Algiers, Zemmouri, Constantine, Béjaia, Djidjelli (5.9 < M < 7.3; IX < Io < X]. This seismicity is the result of the collision between the Nubia and Eurasian plates and is located within the Algerian Tell Atlas. To properly study the seismicity of Algeria, we must consider three periods in relation to the installation of the seismic instrumentation over the Algerian territory: (1) the pre-1910 period with the first published seismic catalogues, (2) the post-1910 period with the beginning of the instrumental seismicity and, finally, (3) the post-1980 period with the installation of the Algerian Teleseismic Network in 1990 and its upgrade following the Zemmouri earthquake of May 21st 2003

A novel interpolation method for InSAR atmospheric wet delay correction

The accuracy and capability of Differential interferometric Synthetic Aperture Radar (DInSAR) depends on the phase errors. In particular, errors associated with Atmospheric Wet Delay (AWD) should be reduced to ensure reliable results from the interferometric process. This paper addresses a new method for AWD estimation based on MEdium Resolution Imaging Spectrometer (MERIS) water vapor image which is used as an auxiliary data to correct AWD effects on ENVIronment SATellite (ENVISAT) Advanced Synthetic Aperture Radar (ASAR) interferogram. We also explore the possibility of using MERIS data under cloudy conditions and we propose a novel method for the interpolation of water vapor in the presence of clouds using a hybrid technique we name Three Dimensional Inverse Distance Weighted (3D-IDW). It is shown that the proposed method succeeds to provide a quite realistic prediction of MERIS water vapor distribution on cloudy area. Obtained results show that 3D-IDW method succeeds to estimate IWV for each cloudy pixel with RMSE not exceeding 0.094 g/cm2 over area masked by 90% of cloud. The proposed method was tested on Mitidja region (north central Algeria), using a couple of Advanced Synthetic Aperture Radar (ASAR) and MERIS images on the 65 descending track. The results demonstrates an improvement of 15% in the standard deviation of interferogram after ADW correction. Finally, the obtained surface deformation reveals the presence of subsiding districts which may be linked to seasonal water level fluctuation and overdrafting groundwater confirming the results of previous study