Marine Propulsion by the Injection of Compressed Air

International audienc

New insights on the relative sea level change during Holocene along the coasts of Tunisia and western Libya from archaeological and geomorphological markers

New data of sea level changes for the Mediterranean region along the coasts of northern Africa are presented. Data are inferred from archaeological sites of Punic-Roman age located along the coast of Tunisia, between Tunis and Jerba island and along the western coast of Libya, between Sabratha and Leptis Magna. Data are based on precise measures of presently submerged archaeological markers that are good indicators of past sea-level elevation. Nineteen selected archaeological sites were studied in Tunisia and four in Libya, all aged between w2.0 and w1.5 ka BP. The functional elevations of significant archaeological markers were measured with respect to the sea level at the time of measurements, applying corrections for tide and atmospheric pressure values. The functional elevations of specific architectural parts of the sites were interpreted, related to sea level at the time of their construction providing data on the relative changes between land and sea. Observations were compared against sea level change predictions derived from the glacio-hydro-isostatic model associated with the Last Glacial cycle. The results indicate that local relative sea level change along the coast of Tunisia and Libya, has increased 0.2 O 0.5 m since the last w2 ka. Besides minor vertical tectonic movements of the land, the observed changes are produced by eustatic and glacio-hydro-isostatic variations acting in the Mediterranean basin since the end of the last glacial maximum

Organisation et fonctionnement d’un écosystème côtier du Maroc : la lagune de Khnifiss

La lagune de Khnifiss, située au sud du Maroc, est une réserve biologique d’intérêt mondial pour l’avifaune. Des études pluridisciplinaires portant sur la physico-chimie des eaux, la biologie, la sédimentologie et les courants ont été réalisées par l’INRH dans la lagune en septembre 1998 et février 2001. Les résultats du courant obtenus montrent que la circulation des eaux à l’intérieur de la lagune est gérée par un courant alternatif et bidirectionnel : les courants du jusant sont plus importants que ceux du flot et varient également en fonction du rythme de la marée vive-eau/morte-eau. Ce mode de circulation des eaux attribue à la lagune une richesse en éléments azotés et phosphatés, surtout en période de vive-eau. La biomasse chlorophyllienne, assez importante dans la lagune, est causée par la richesse du milieu en éléments nutritifs et le phénomène d’upwelling qui se manifeste en été et au printemps dans la zone sud du Maroc. Ces études ont montré que la lagune de Khnifiss est un milieu propice à la conchyliculture. Néanmoins, l’installation de tout projet aquacole dans le site devra tenir compte de sa capacité trophique et de son équilibre écologique.The Moroccan coastal marine area has several zones that are targets for exploitation but must simultaneously be protected. Lagoons are considered to be among the most productive natural systems in the world, but they are also vulnerable systems due to natural and human constraints. Lagoons can also be a target of economic expansion. This is why an understanding about the state of these ecosystems is important in order to proceed with rational use of the resource. The Khnifiss lagoon, situated on the South Atlantic coast of Morocco, is a potential site for aquaculture and tourism if planned with an ecological awareness. The large surface area and high biological production for the avifauna qualify it to be among the four protected sites by the RAMSAR convention for humid zone conservation (lagoons of Khnifiss and Moulay Bousselham, lakes of Sidi Boughaba and Afennourir). The objective of this work was to complete previous studies and to estimate the nutritive richness of the Khnifiss lagoon. To understand the spatio-temporal variability in the water currents, and the physico-chemical and biological and characteristics of this lagoon, two surveys were organized in September 1998 and February 2001.The Khnifiss lagoon (20 km long and 65 km2 surface area) is situated between Tantan and Tarfaya (28°02'54'' N, 12°13'66'' W). It opens up into the Atlantic ocean by a narrow inlet called ''Foum Agouitir'', about 100 m wide. The lagoon continues upstream beyond a salt marsh, called "Sebkha Tazra". Physical, chemical and biological variables were monitored: temperature and salinity; dissolved oxygen, nitrates and phosphates; chlorophyll a. The current (direction and intensity) and the sediment were also studied. Samples were collected four times from the surface and bottom waters during spring tide (ST), neap tide (NT), low tide (LT) and high tide (HT) during two seasons (September 1998 and February 2001). Seven hydrological stations were sampled, representing the lagoon system and one reference station in a neighbouring zone (Hréf), which represents the marine zone of the lagoon. Temperature and salinity were measured with a multi-sensor probe. The chemical analyses were carried out according to methods suggested by AMINOT & CHAUSSEPIED (1983). Thirty (30) sediment samples were also collected. Currents were measured at two fixed points by two current-meters.Based on the hydrological characteristics of the lagoon, especially temperature, salinity, water circulation and the nature of sediment, three zones were identified :1. Zone I (downstream from the lagoon) was dominated by the ocean’s influence and included the Hréf, H1 and H2 stations. Maximum depths varied from 2.5 to 6.6 m, depending on the tide and location. The concentrations of the different hydrological parameters were controlled by the plug effect of the oceanic environment. The most important current in the lagoon was recorded in this zone in the spring tide (ST: 110 cm.s-1). The sediment was coarse and important water - sediment exchange was caused by the strong current recorded in this zone.2. Zone II (middle of the lagoon) was a transition zone with an intermediate oceanic influence. It was situated between the H3 and H5 stations. The size of the inlet and the important exchanges governed by currents caused by strong tides resulted in concentrations of the various parameters being similar to those in Zone I. Depths varied from 2.64 to 8.7 m. Waters were more saline during the LT and NT periods (36-41 practical salinity unit, or psu). The current decreased relative to that is zone I (56 cm.s-1 in September 1998 and 78 cm.s-1 in February 2001). In this zone the current moved preferentially towards the right strand at high tide and toward the left strand at low tide.3. Zone III (upstream in the lagoon) covered a different biotope compared to the first two zones. The waters were less deep (2.64 to 5.3 m) and included the stations H6, H7 and the upper part of the lagoon. This zone was characterized by a very low oceanic influence. Water temperature and salinity were higher, 24-26°C and 41-44 psu respectively, during the LT and NT periods.On the basis of the hydrological zonation, the conjunction of the climate descriptors (moderate wind, rare precipitation, absence of storms, moderate air temperature) of the lagoon and the strong hydrodynamic influence in the lagoon suggest that the Knifiss lagoon is a relatively unconfined ecosystem. The hydrodynamics of this lagoon permit a fast water renewal rate and insure a good environmental quality. In addition, studies carried out on the healthiness of this lagoon demonstrated not only a healthy environment, but also healthy shellfish. This diagnosis seemed to be related to the geographical location and important rates of water exchange. However, the absence of continental freshwater sources leads to an important increase in salinity and temperature at the level of the upstream zone (zone III). Zone III therefore cannot be considered for shellfish breeding.On the basis of the biological zones: With respect to the bathymetry of the lagoon (depths varied from 2.5 to 8.7 m), shellfish, in contrast to fish, require less water depth. Therefore, it is sufficient to search for a less turbulent zone, which offers sufficient planktonic food for the shellfish growth. In the Khnifiss lagoon, the taxonomy of the phytoplankton has not been yet studied. However, BENNOUNA (1999) demonstrated that the phytoplankton community was dominated by dinoflagellates and diatoms in the Oualidia and Sidi Moussa lagoons. RHARBI (2000) found that picophytoplankton were the principal breeding food source of oysters and clams in Oualidia lagoon. The source of shellfish for breeding is located in the neighbouring upwelling marine waters. Development projects planned for the lagoon must include an awareness programme for fishermen about the role that moderate and responsible shellfish breeding programs can play in the preservation and reconstitution of the marine resource as well as in the improvement of their incomes

Seasonal Migration and Home Ranges of Female Elk in the Black Hills of South Dakota and Wyoming

Understanding the movement and dispersion patterns of elk (Cervus elaphus) on public lands and the underlying factors that affect each will facilitate elk management and help resolve conflicts between management that benefit elk and other uses of land resources. Consequently, there is a need to identify and examine the movement and dispersion patterns of elk in the Black Hills of South Dakota and Wyoming. Our study quantified seasonal movements, determined home ranges of female elk in two areas of the Black Hills, and examined underlying factors associated with each. Elk in the northern area did not demonstrate seasonal migration patterns. Rather, winter ranges in the northern area were contained mostly within the boundaries of the summer range. Elk in the southern area exhibited a north-south migration pattern that coincided with seasonal patterns of snowfall. These elk migrated to winter range in late November and returned to summer range in late April. Home ranges of elk in the southern area were larger (P \u3c 0.01) than home ranges in the northern area. Landscape characteristics with marginally-significant correlations to elk home range area included road density (P = 0.10), and forage:cover ratio (P = 0.08); density of primary and secondary roads and average slope were significantly correlated with elk home range area (P \u3c 0.01). Managers can use this information to develop strategies that meet population goals and reduce conflicts between management for elk and with other resources

Cavernome intramedullaire: a propos d’un cas

Le cavernome intramédullaire, malformation vasculaire rare, représente environ 5 à 12 % des malformations vasculaires spinales et 3 % des malformations vasculaires intra-durales. Il peut être longtemps asymptomatique ou se manifester par une altération brutale ou progressive des fonctions médullaires. Le diagnostic repose sur l’imagerie par résonance magnétique (IRM) médullaire et l’anatomopathologie. La chirurgie représente l’essentiel de la prise en charge, néanmoins elle n’est pas dénudée de complications. Nous rapportons un cas de cavernome intramédullaire chez une patiente de 24 ans, admise dans un tableau de compression médullaire dorsale lente avec une paraparésie évoluant depuis 2 ans. L’IRM médullaire a objectivé une lésion intramédullaire en regard deT7-T8. La patiente a bénéficié d’une exérèse totale de la tumeur et l’histologie a confirmé le cavernome intramédullaire. L’évolution a été marquée par une aggravation partielle du déficit moteur. A travers cette observation, les auteurs discutent les aspects cliniques, radiologiques ainsi que la prise en charge de cette pathologie rare.Mots clés: Cavernome, intramédullaire, malformation vasculair

Role of accelerated aging in limb muscle wasting of patients with COPD

Purpose: Skeletal muscle wasting is an independent predictor of health-related quality of life and survival in patients with COPD, but the complexity of molecular mechanisms associated with this process has not been fully elucidated. We aimed to determine whether an impaired ability to repair DNA damage contributes to muscle wasting and the accelerated aging phenotype in patients with COPD. Patients and methods: The levels of phosphorylated H2AX (γH2AX), a molecule that promotes DNA repair, were assessed in vastus lateralis biopsies from 10 COPD patients with low fat-free mass index (FFMI; COPDL), 10 with preserved FFMI and 10 age- and gender-matched healthy controls. A panel of selected markers for cellular aging processes (CDKN2A/p16ink4a, SIRT1, SIRT6, and telomere length) were also assessed. Markers of oxidative stress and cell damage and a panel of pro-inflammatory and anti-inflammatory cytokines were evaluated. Markers of muscle regeneration and apoptosis were also measured. Results: We observed a decrease in γH2AX expression in COPDL, which occurred in association with a tendency to increase in CDKN2A/p16ink4a, and a significant decrease in SIRT1 and SIRT6 protein levels. Cellular damage and muscle inflammatory markers were also increased in COPDL. Conclusion: These data are in keeping with an accelerated aging phenotype as a result of impaired DNA repair and dysregulation of cellular homeostasis in the muscle of COPDL. These data indicate cellular degeneration via stress-induced premature senescence and associated inflammatory responses abetted by the senescence-associated secretory phenotype and reflect an increased expression of markers of oxidative stress and inflammation