Hydrographic network extraction and watersheds delimitation software of the South Oran (North Wester Algeria)

The development of space technology has allowed a better understanding and effective use of water resources through the use of Digital Terrain Models (DTM) Mapping the river system from DTM has two objectives, namely identifying first topography  descriptors like hills, ridges and valleys of watersheds and second hydrological parameters to map areas of runoff recovery for a more efficient development and also a better representation of the actual land occupation. Our work is part of a methodological approach to satellite imagery processing and mapping of topographic and hydrographic parameters of watersheds. Thus, from DTM one was able to extract the full river system of the region. The results show a remarkable evolution of human activities and  especially in areas of high water recovery capacity.Keywords: remote sensing, DTM, network hydrology, geographic, steppe, west of  Algeria

Dynamics of the anatomical variability of Artemisia herba-alba in Algeria

In this work, the anatomical variability in Artemisia herba-alba Asso was studied based on 90 individuals taken from three different bioclimatic zones of Algeria (inferior semi arid, arid and Saharan) as well as the relationships of the dynamics of this variability with the distribution and adaptation of the species. The interpretation of the results of this study through the analysis of variance and the ascending hierarchical classification allowed us to detect a very high intra- and inter-specific anatomical variability, as well as the presence of a parenchyma of water reserves observed in individuals of each studied region. The existence of relationships between environmental conditions and the dynamics of anatomical variability have been established. The broad morphological structural variability thus determined and the genetic variability observed concur well with the results of our two other previous studies. This anatomical polymorphism could help in the selection of the most effective ecotypes to restore this species in degraded steppe ecosystems of Algeria and North Africa. Thus, this choice will allow us to keep their seeds in a bank of grains in order to preserve the species for possible future use

Neutrophil depletion reduces edema formation and tissue loss following traumatic brain injury in mice

Background: Brain edema as a result of secondary injury following traumatic brain injury (TBI) is a major clinical concern. Neutrophils are known to cause increased vascular permeability leading to edema formation in peripheral tissue, but their role in the pathology following TBI remains unclear. Methods: In this study we used controlled cortical impact (CCI) as a model for TBI and investigated the role of neutrophils in the response to injury. The outcome of mice that were depleted of neutrophils using an anti-Gr-1 antibody was compared to that in mice with intact neutrophil count. The effect of neutrophil depletion on blood-brain barrier function was assessed by Evan's blue dye extravasation, and analysis of brain water content was used as a measurement of brain edema formation (24 and 48 hours after CCI). Lesion volume was measured 7 and 14 days after CCI. Immunohistochemistry was used to assess cell death, using a marker for cleaved caspase-3 at 24 hours after injury, and microglial/macrophage activation 7 days after CCI. Data were analyzed using Mann-Whitney test for non-parametric data. Results: Neutrophil depletion did not significantly affect Evan's blue extravasation at any time-point after CCI. However, neutrophil-depleted mice exhibited a decreased water content both at 24 and 48 hours after CCI indicating reduced edema formation. Furthermore, brain tissue loss was attenuated in neutropenic mice at 7 and 14 days after injury. Additionally, these mice had a significantly reduced number of activated microglia/macrophages 7 days after CCI, and of cleaved caspase-3 positive cells 24 h after injury. Conclusion: Our results suggest that neutrophils are involved in the edema formation, but not the extravasation of large proteins, as well as contributing to cell death and tissue loss following TBI in mice

Neurogenic inflammation after traumatic brain injury and its potentiation of classical inflammation

Background: The neuroinflammatory response following traumatic brain injury (TBI) is known to be a key secondary injury factor that can drive ongoing neuronal injury. Despite this, treatments that have targeted aspects of the inflammatory pathway have not shown significant efficacy in clinical trials. Main body: We suggest that this may be because classical inflammation only represents part of the story, with activation of neurogenic inflammation potentially one of the key initiating inflammatory events following TBI. Indeed, evidence suggests that the transient receptor potential cation channels (TRP channels), TRPV1 and TRPA1, are polymodal receptors that are activated by a variety of stimuli associated with TBI, including mechanical shear stress, leading to the release of neuropeptides such as substance P (SP). SP augments many aspects of the classical inflammatory response via activation of microglia and astrocytes, degranulation of mast cells, and promoting leukocyte migration. Furthermore, SP may initiate the earliest changes seen in blood-brain barrier (BBB) permeability, namely the increased transcellular transport of plasma proteins via activation of caveolae. This is in line with reports that alterations in transcellular transport are seen first following TBI, prior to decreases in expression of tight-junction proteins such as claudin-5 and occludin. Indeed, the receptor for SP, the tachykinin NK1 receptor, is found in caveolae and its activation following TBI may allow influx of albumin and other plasma proteins which directly augment the inflammatory response by activating astrocytes and microglia. Conclusions: As such, the neurogenic inflammatory response can exacerbate classical inflammation via a positive feedback loop, with classical inflammatory mediators such as bradykinin and prostaglandins then further stimulating TRP receptors. Accordingly, complete inhibition of neuroinflammation following TBI may require the inhibition of both classical and neurogenic inflammatory pathways.Frances Corrigan, Kimberley A. Mander, Anna V. Leonard and Robert Vin

Role of the lesion scar in the response to damage and repair of the central nervous system

Traumatic damage to the central nervous system (CNS) destroys the blood-brain barrier (BBB) and provokes the invasion of hematogenous cells into the neural tissue. Invading leukocytes, macrophages and lymphocytes secrete various cytokines that induce an inflammatory reaction in the injured CNS and result in local neural degeneration, formation of a cystic cavity and activation of glial cells around the lesion site. As a consequence of these processes, two types of scarring tissue are formed in the lesion site. One is a glial scar that consists in reactive astrocytes, reactive microglia and glial precursor cells. The other is a fibrotic scar formed by fibroblasts, which have invaded the lesion site from adjacent meningeal and perivascular cells. At the interface, the reactive astrocytes and the fibroblasts interact to form an organized tissue, the glia limitans. The astrocytic reaction has a protective role by reconstituting the BBB, preventing neuronal degeneration and limiting the spread of damage. While much attention has been paid to the inhibitory effects of the astrocytic component of the scars on axon regeneration, this review will cover a number of recent studies in which manipulations of the fibroblastic component of the scar by reagents, such as blockers of collagen synthesis have been found to be beneficial for axon regeneration. To what extent these changes in the fibroblasts act via subsequent downstream actions on the astrocytes remains for future investigation

Shear viscosities of liquid sodium and potassium using Green-Kubo and “first principles” pseudopotential formalisms

International audienceThis article presents an original work on velocity and stress autocorrelation functions, memory functions, spectral densities and atomic transport properties of two liquid alkali metals (sodium and potassium). For this, we carried out molecular dynamics (MD) simulations using Green-Kubo relation under the condition of very long-time duration to obtain reliable and accurate results.An originality of the present work is that the interatomic forces are described by pair potentials built within the “first principles” pseudopotential formalism using the non-local and energy dependent model potential of Shaw. It is completely free of adjustable parameters since the energy dependent parameters are determined self-consistently at the Fermi energy on an absolute energy scale. The Green-Kubo relationship is the main theoretical tool that allows us determining the atomic transport coefficients from appropriate time-autocorrelation functions. An important new result concerns the memory function. We demonstrate, for the first time to our knowledge, that it can be depicted as a sum of wavelets. The wavelets with their amazing features emphasize the nature of dynamic processes at the microscopic level. We also compared, for the first time to our knowledge, the spectral density associated to the velocity autocorrelation function (VACF), to experimental values obtained by incoherent inelastic neutron scattering. Finally, the temperature dependence of the self-diffusion coefficient (our previous study) and that of shear viscosity (present work) are both in excellent agreement with experiment

Static structure and dynamic properties in liquid Sn-96.2 Ag-3.8 lead free solder: Structure factor, diffusion coefficients and viscosity

International audienceStarting from the pseudopotential formalism, we developed a new pseudopotential able to describe accurately both heavy metals like tin and noble metals like copper and silver which are the basic elements of the new lead free solders. The pseudopotential describes the interaction between electrons and ions. To describe the atomic structure it is necessary to use an effective pair potential describing the interaction between ions taking into account the electron screening cloud. This pair potential is deduced from our new pseudopotential. It enters into a simulation program using molecular dynamics. First we calculate the atomic structure factor that has been compared to that measured experimentally by neutron or X ray scattering. In the case of a binary alloy, we determined three partial structure factors describing the system. These can be calculated but in general cannot be obtained experimentally. To do a comparison we must combine adequately the calculated partial structure factors and compare it to the experimental total structure factor. By molecular dynamics we can follow the individual movement of particles to obtain the different diffusion coefficients which, as partial structure factors, are very difficult to measure accurately. We followed the collective movement of all particles and got the shear viscosity by Green-Kubo formalism. We compared our results to the existing experimental viscosity which is a little easier to measure. However, in the bibliography, we observe high discrepancies between the different authors. It is thus important to be able to calculate accurately these properties as functions of temperature and composition

Effect of the ordering potential on the structure of liquid alloys

The concept of “ordering or alloying potential” (J. Hafneri: from Hamiltonians to phase diagrams: Springer Berlin 1987 and R. N. Singh and F. Sommerii Rep. Prog. Phys. 60 (1997) 57–150) enables the understanding of the different kind of alloys: hetero-coordinated one’s leading to compounds, homocoordinated ones leading to miscibility gap systems and substitutional alloys. The ordering potential is based on the comparison of identical atom interionic potentials (V11 and V22) and different atom interionic potential (V12) It allows the description of the demixing properties of some alloys. In order to understand the concepts, we developed our calculations by using a Lennard-Jones potential, the atomic structure being calculated by molecular dynamics simulation. We obtained surprising and unexpected results putting in evidence the time of simulation and the strength of the ordering potential