Performance Evaluation of Routing Protocols in Wireless Sensor Networks

The efficiency of sensor networks strongly depends on the routing protocol used. In this paper, we analyze three different types of routing protocols: LEACH, PEGASIS, and VGA. Sensor networks are simulated using Sensoria simulator. Several simulations are conducted to analyze the performance of these protocols including the power consumption and overall network performance. The simulation results, using same limited sensing range value, show that PEGASIS outperforms all other protocols while LEACH has better performance than VGA. Furthermore, the paper investigates the power consumption for all protocols. On the average, VGA has the worst power consumption when the sensing range is limited, while VGA is the best when the sensing range is increased

Environmental Impact Assessment of a Flood Control Channel in Sfax City, Tunisia

The objective of this study is to evaluate water and sediment quality in the southern branch of a flood control channel in Sfax city, as well as its neighboring sites. This artificial channel, located 4km away from downtown Sfax, was implemented in 1984 to protect the city against floods. Even though it contributed to reduce the harmful flood effects, this channel also resulted in new environmental problems that may cause a public health threat. Indeed, artificial surfaces pose a greater risk of infection due to bacteria, fungi and other microorganisms. A total of 19 water samples (9 from the channel and 10 from groundwater wells) were collected in a dry period and analyzed in the laboratory. Furthermore, 12 sediment samples were taken from the bottom of the channel. Water quality data were used to examine the spatial variability of the different water quality parametrs. The resultant maps revealed an important contamination and illustrated that the degree of contamination differs from one site to another, depending on the distance from the pollution source (industrial, domestic or agricultural activity), the depth of the groundwater table and also the maintenance of the well and its surroundings

Contribution to the study of the chemical composition of Lemon Verbena: Aloysia triphylla (Hert). Britt. cultivated in Morocco

By combining gas chromatography and mass spectrometry we have identified the main constituents of the essential oil of verbena tea (Alyosia triphylla) grown in Morocco. Harvests carried out at different stages of development of the plant allowed to characterize the qualitative variations of the active substances of the essential oil. The comparison of our results with the data of the literature gives some details on the different chemo types and the chemical diversity of this aromatic plant with high medicinal and economic value

Flying PIV measurements in a 4-valve IC engine water analogue to characterize the near-wall flow evolution

For a deeper understanding of the highly unsteady near-wall boundary layer flows in internal combustion (IC) engines, PIV-based flow field measurements close to the inner cylinder and piston walls within transparent engines are required. The herein described flying PIV method in combination with a scanning light-sheet provides time-resolved PIV measurements in a transparent IC engine water analogue in a radial plane 1.5 mm apart from the planar piston crown while the piston is moving. The light-sheet is parallel to the piston surface and moves with the piston thanks to the scanning technique that synchronizes the sheet motion with the non-linear piston motion. A compact high speed camera is positioned within the piston shaft below the transparent piston head and records the particle fields within the illuminated plane in time-resolved manner. The measurements are realized in a water-analogue of a 4-valve engine at 950 rpm engine speed in real situation. Instantaneous pictures are compared to phase-averaged velocity maps and allowed to localize regions of high cycle-to-cycle fluctuations

The Polycomb protein, Bmi1, regulates insulin sensitivity

Objective: The Polycomb Repressive Complexes (PRC) 1 and 2 function to epigenetically repress target genes. The PRC1 component, Bmi1, plays a crucial role in maintenance of glucose homeostasis and beta cell mass through repression of the Ink4a/Arf locus. Here we have explored the role of Bmi1 in regulating glucose homeostasis in the adult animal, which had not been previously reported due to poor postnatal survival of Bmi1−/− mice. Methods: The metabolic phenotype of Bmi1+/− mice was characterized, both in vivo and ex vivo. Glucose and insulin tolerance tests and hyperinsulinemic-euglycemic clamps were performed. The insulin signaling pathway was assessed at the protein and transcript level. Results: Here we report a negative correlation between Bmi1 levels and insulin sensitivity in two models of insulin resistance, aging and liver-specific insulin receptor deficiency. Further, heterozygous loss of Bmi1 results in increased insulin sensitivity in adult mice, with no impact on body weight or composition. Hyperinsulinemic-euglycemic clamp reveals increased suppression of hepatic glucose production and increased glucose disposal rate, indicating elevated glucose uptake to peripheral tissues, in Bmi1+/− mice. Enhancement of insulin signaling, specifically an increase in Akt phosphorylation, in liver and, to a lesser extent, in muscle appears to contribute to this phenotype. Conclusions: Together, these data define a new role for Bmi1 in regulating insulin sensitivity via enhancement of Akt phosphorylation

Effect of a Saccharomyces cerevisiae preparation on in vitro ruminal fermentation of four fibrous substrates

Yeast cultures, especially Saccharomyces cerevisiae, are beneficial in the rumen, and have been progressively introduced into the feed industry. They can affect microbial activities, thus improving fiber digestion, modifying VFA production and increasing animal performance