The complex network of global cargo ship movements

Transportation networks play a crucial role in human mobility, the exchange of goods, and the spread of invasive species. With 90% of world trade carried by sea, the global network of merchant ships provides one of the most important modes of transportation. Here we use information about the itineraries of 16,363 cargo ships during the year 2007 to construct a network of links between ports. We show that the network has several features which set it apart from other transportation networks. In particular, most ships can be classified in three categories: bulk dry carriers, container ships and oil tankers. These three categories do not only differ in the ships' physical characteristics, but also in their mobility patterns and networks. Container ships follow regularly repeating paths whereas bulk dry carriers and oil tankers move less predictably between ports. The network of all ship movements possesses a heavy-tailed distribution for the connectivity of ports and for the loads transported on the links with systematic differences between ship types. The data analyzed in this paper improve current assumptions based on gravity models of ship movements, an important step towards understanding patterns of global trade and bioinvasion.Comment: 7 figures Accepted for publication by Journal of the Royal Society Interface (2010) For supplementary information, see http://www.icbm.de/~blasius/publications.htm

Impacts Des Technologies De l’Information Et De La Communication (TIC) Sur Les Rendements Scolaires Des Apprenants De La Ville De Dassa-Zoumé Dans Le Département Des Collines Au Bénin

L’usage des TIC consiste à l’accès et à l’utilisation des technologies de l’information et de la communication dans l’éducation. L’objectif global de cette recherche est de montrer les répercutions socio-éducatives des usages des TIC sur le rendement des apprenants des établissements publics de Dassa-Zoumé. L’approche méthodologique adoptée se subdivise en trois points à savoir : la recherche documentaire, la collecte de données, le traitement des informations et l’analyse des résultats.Les résultats obtenus sur le terrain ont révélé que 37 % des enseignants ont estimé que les TIC facilitent les recherches et 65 % de ceux-ci pensent que cela contribue à l’amélioration des résultats scolaires. L’usage des TIC pour des recherches documentaires est adopté par 65 % des enquêtés. 14 % ont affirmé que cela affaiblit le niveau scolaire des apprenants parce qu’ils l’utilisent pour des fins peu orthodoxes. Malgré les multiples avantages que procurent l’usage des TIC en milieu scolaire, des défis restent à relever à savoir : la non-maîtrise des outils informatiques, le coût d’accès élevés, l’éloignement des lieux d’accès et la privation formelle de l’usage des smartphones par les parents. Enfin 18 % ont énuméré l’indisponibilité des services offerts par les TIC

Longevity Record for a Wild Allegheny Woodrat (Neotama magister) in West Virginia

The Allegheny woodrat (Neotoma magister) is found throughout much of the central and southern Appalachians and adjacent portions of the Interior Highlands. Allegheny woodrats have declined in the northern portions of their range and are state-listed as threatened, endangered or sensitive species of concern in every state where they occur. Until recently, biologists have had to rely on biological data collected from the closely related eastern woodrat (N. floridana) because of limited research on the Allegheny woodrat. We have been studying the ecology and natural history of woodrats in Virginia and West Virginia since 1990. On 8 August 1997 we caught and ear-tagged a juvenile female woodrat. She was caught a total of 24 times in the same outcrop from 1997 through 2002. A conservative estimate of her age on 25 January 2002 was 1,734 days or 57.8 months. This extends the record longevity for a wild Allegheny woodrat by 70 days or 2.3 months. Regardless, her known time alive (from first capture to last) of 1,630 days still surpasses previous estimates of longevity for the Allegheny woodrat

Characterization, reactivity and rheological behaviour of metakaolin and Meta-halloysite based geopolymer binders

The type of aluminosilicate precursor used in the synthesis of geopolymer binders plays a huge role in the resulting performance. Thus, it is critical to understand the properties of precursors and how they influence the corresponding performance of geopolymer binders. In this study, metakaolin and meta halloysite are used as the aluminosilicate precursor in the synthesis of geopolymer binders. These precursors are obtained locally in order to propel the sustainable development and application of geopolymers. The precursors were characterized and the corresponding influence on the reactivity, rheology and setting times of geopolymers was investigated. In addition to the influence of precursor type on the properties of the geopolymers, the effect of two silica moduli (i.e. 1.3 and 1.5) was also evaluated. The results from this study indicated that increasing the activator silica modulus from 1.3 to 1.5 extended the setting times and increased the stress strain of the geopolymer binders. Characterization of the precursors indicated that metakaolin has a higher amorphous content compared to that of meta halloysite. However, the finer particles of meta halloysite embodied it with the ability to participate in a faster geopolymerization and result in more formation of activation products

Colonial coinage and financial development

Abstract. Until the 21st century, Africa remains the only region in the world where there are countries whose currency is derived from the colonial system. Very far from political and geostrategic considerations, the question has always been asked in order to know the effect of this lack of monetary sovereignty on the evolution of economic activity. Therefore, this study investigates the relationship between Colonial coinage and financial development by applying Generalised Method of Moments. The importance of this approach, is to deal with heterogeneity and endogeneity problems. The sample consist of 48 African countries data over 10 years. This study findings are like-minded with those of economic literature around the law, finance and endowment theory. They suggest that in sub-Saharan Africa, the quality of institutions has a very large influence on access to domestic credit. Moreover, the main enclave for the development of the financial system due to colonial coinage is the sluggish stability of the latter colonial coinage in Africa.Keywords. Colonial coinage, Cliometrics, Financial development, Institutions.JEL. E50, G20, K40

Impact of Climate Change on Priority Plant Species Conservation in The Forests Under ONAB (the National Wood Office of Benin) Management

The sustainable conservation of forest resources in a context of climate change and population growth would be compromised in their current form of exploitation by rural communities. The objective of this study is to assess the impact of climate change on the dynamics of habitats favorable to species of conservation priority in the forests under ONAB management as these species are heavily used by the populations living along the shores of these forests. The study will consist of: Khaya senegalensis, Afzelia africana, Khaya grandifoliola, Pterocarpus erinaceus, Anogeissus leiocarpa, Milicia excelsa, Albizia zygia, Vitex doniana, Antidesma laciniatum and Bombax costatum. Techniques based on the principle of maximum entropy (Maxent) combined with GIS were used to project the favorable habitats of these ten species under current and future climatic conditions (Horizon 2050). Species occurrence data were collected and combined with bioclimatic data derived from the Worldclim database and the edaphic (soil) variable. Two climate models were used for future projections (CNRM-CM5, HadGEM-ES models) under the IPCC A2 scenario, and the partial ROC approach was used for the evaluation of the predictions of ecological niche models. Variables such as cec2 (cation exchange capacity, horizon 5-15cm), bio17 (precipitation of the driest quarter), bio12 (annual precipitation), bio3 (isothermality), bio6 (minimum temperature of the coldest month) and bio7 (annual thermal amplitude) were found to be the most relevant respectively for the distribution of Khaya grandifoliola, Albizia zygia, Anogeissus leiocarpa, Antidesma laciniatum, Afzelia africana and Khaya senegalensis. Under current conditions, only 7% of the Beninese territory would be very favorable to the conservation of Khaya senegalensis and the CNRM-CM5 model predicts an increase of 27.5% and 13.2% respectively of these very favorable and moderately favorable areas by 2050 through conversion of unfavorable areas (7.4%). On the other hand, this model predicts an opposite trend at the level of Afzelia africana where it predicts a decrease of 8.1% and 1.8% respectively of the very favorable and moderately favorable areas and an increase of 5.1% of the unfavorable areas. Ecological niche modeling has basically revealed the conversion of some currently unfavorable habitats into very favorable habitats for conservation (this is the case of Khaya grandifoliola, Khaya senegalensis and Vitex doniana) and the extension of some habitats unfavorable to conservation (Anogeissus leiocarpa, Bombax costatum, and Pterocarpus erinaceus) by 2050. This study provides scientific support for planning and is a decision support tool for the conservation of these species at the socio-economic level

A multi-method characterization of Elasmobranch & Cheloniidae communities of the north-eastern Red Sea and Gulf of Aqaba

The Red Sea is particularly biodiverse, hosting high levels of endemism and numerous populations whose extinction risk is heightened by their relative isolation. Elasmobranchs and sea turtles have likely suffered recent declines in this region, although data on their distribution and biology are severely lacking, especially on the eastern side of the basin in Saudi Arabian waters. Here, we present sightings of elasmobranchs and sea turtles across the north-eastern Red Sea and Gulf of Aqaba collected through a combination of survey methods. Over 455 survey hours, we recorded 407 sightings belonging to 26 elasmobranch species and two sea turtle species, more than 75% of which are of conservation concern. We identified 4 species of rays and 9 species of sharks not previously recorded in Saudi Arabia and report a range extension for the pink whipray (Himantura fai) and the round ribbontail ray (Taeniurops meyeni) into the Gulf of Aqaba. High density of sightings of conservation significance, including green and hawksbill sea turtles and halavi guitarfish were recorded in bay systems along the eastern Gulf of Aqaba and the Saudi Arabian coastline bordering the north-eastern Red Sea, and many carcharhinid species were encountered at offshore seamounts in the region. Our findings provide new insights into the distribution patterns of megafaunal assemblages over smaller spatial scales in the region, and facilitate future research and conservation efforts, amidst ongoing, large-scale coastal developments in the north-eastern Red Sea and Gulf of Aqaba

Selective Constraints on Amino Acids Estimated by a Mechanistic Codon Substitution Model with Multiple Nucleotide Changes

Empirical substitution matrices represent the average tendencies of substitutions over various protein families by sacrificing gene-level resolution. We develop a codon-based model, in which mutational tendencies of codon, a genetic code, and the strength of selective constraints against amino acid replacements can be tailored to a given gene. First, selective constraints averaged over proteins are estimated by maximizing the likelihood of each 1-PAM matrix of empirical amino acid (JTT, WAG, and LG) and codon (KHG) substitution matrices. Then, selective constraints specific to given proteins are approximated as a linear function of those estimated from the empirical substitution matrices. Akaike information criterion (AIC) values indicate that a model allowing multiple nucleotide changes fits the empirical substitution matrices significantly better. Also, the ML estimates of transition-transversion bias obtained from these empirical matrices are not so large as previously estimated. The selective constraints are characteristic of proteins rather than species. However, their relative strengths among amino acid pairs can be approximated not to depend very much on protein families but amino acid pairs, because the present model, in which selective constraints are approximated to be a linear function of those estimated from the JTT/WAG/LG/KHG matrices, can provide a good fit to other empirical substitution matrices including cpREV for chloroplast proteins and mtREV for vertebrate mitochondrial proteins. The present codon-based model with the ML estimates of selective constraints and with adjustable mutation rates of nucleotide would be useful as a simple substitution model in ML and Bayesian inferences of molecular phylogenetic trees, and enables us to obtain biologically meaningful information at both nucleotide and amino acid levels from codon and protein sequences.Comment: Table 9 in this article includes corrections for errata in the Table 9 published in 10.1371/journal.pone.0017244. Supporting information is attached at the end of the article, and a computer-readable dataset of the ML estimates of selective constraints is available from 10.1371/journal.pone.001724

Towards Visual Feedback Loops for Robot-Controlled Additive Manufacturing

Robotic additive manufacturing methods have enabled the design and fabrication of novel forms and material systems that represent an important step forward for architectural fabrication. However, a common problem in additive manufacturing is to predict and incorporate the dynamic behavior of the material that is the result of the complex confluence of forces and material properties that occur during fabrication. While there have been some approaches towards verification systems, to date most robotic additive manufacturing processes lack verification to ensure deposition accuracy. Inaccuracies, or in some instances critical errors, can occur due to robot dynamics, material self-deflection, material coiling, or timing shifts in the case of multi-material prints. This paper addresses that gap by presenting an approach that uses vision-based sensing systems to assist robotic additive manufacturing processes. Using online image analysis techniques, occupancy maps can be created and updated during the fabrication process to document the actual position of the previously deposited material. This development is an intermediary step towards closed-loop robotic control systems that combine workspace sensing capabilities with decision-making algorithms to adjust toolpaths to correct for errors or inaccuracies if necessary. The occupancy grid map provides a complete representation of the print that can be analyzed to determine various key aspects, such as, print quality, extrusion diameter, adhesion between printed parts, and intersections within the meshes. This valuable quantitative information regarding system robustness can be used to influence the system’s future actions. This approach will help ensure consistent print quality and sound tectonics in robotic additive manufacturing processes, improving on current techniques and extending the possibilities of robotic fabrication in architecture

Colonial coinage and financial development

Until the 21st century, Africa remains the only region in the world where there are countries whose currency is derived from the colonial system. Very far from political and geostrategic considerations, the question has always been asked in order to know the effect of this lack of monetary sovereignty on the evolution of economic activity. Therefore, this study investigates the relationship between Colonial coinage and financial development by applying Generalised Method of Moments. The importance of this approach, is to correct heterogeneity and endogeneity problems. The sample consist of 48 African countries data over 10 years. This study findings are like-minded with those of economic literature around the law, finance and endowment theory. They suggest that in sub-Saharan Africa, the quality of institutions has a very large influence on access to domestic credit. Moreover, the main enclave for the development of the financial system due to colonial coinage is the sluggish stability of the latter colonial coinage in Africa