24 research outputs found
Social Memory and the Resilience of Communities Affected by Land Degradation
Based on evidence collected in 22 village communities from nine study sites situated in Spain, Italy, Greece, Morocco and China, this study analyses the complex interlinkages between social memory, community resilience and land degradation. Social memory is seen as an important explanation regarding the ability of a local community to manage and cope with land degradation. Emphasis is placed on the importance of three components of social memory – rites, traditions and social learning processes – for shaping community resilience in coping with land degradation processes. The study argues that, although there are subtle differences between the 22 village communities, the loss of social memory and learning pathways associated with managing land degradation is emerging as a critical factor constraining stakeholders from effectively responding to land degradation issue
Secretion of mast cell inflammatory mediators is enhanced by CADM1-dependent adhesion to sensory neurons
Neuroimmune interactions are important in the pathophysiology of many chronic inflammatory diseases, particularly those associated with alterations in sensory processing and pain. Mast cells and sensory neuron nerve endings are found in areas of the body exposed to the external environment; both are specialized to sense potential damage by injury or pathogens and signal to the immune system and nervous system respectively, to elicit protective responses. Cell adhesion molecule 1 (CADM1), also known as SynCAM1, has previously been identified as an adhesion molecule which may couple mast cells to sensory neurons however, whether this molecule exerts a functional as well as structural role in neuroimmune cross-talk is unknown. Here we show, using a newly developed in vitro co-culture system consisting of murine bone marrow derived mast cells (BMMC) and adult sensory neurons isolated from dorsal root ganglions (DRG), that CADM1 is expressed in mast cells and adult sensory neurons and mediates strong adhesion between the two cell types. Non-neuronal cells in the DRG cultures did not express CADM1, and mast cells did not adhere to them. The interaction of BMMCs with sensory neurons was found to induce mast cell degranulation and IL-6 secretion and to enhance responses to antigen stimulation and activation of FcεRI receptors. Secretion of TNFα in contrast was not affected, nor was secretion evoked by compound 48/80. Co-cultures of BMMCs with HEK 293 cells, which also express CADM1, while also leading to adhesion did not replicate the effects of sensory neurons on mast cells, indicative of a neuron-specific interaction. Application of a CADM1 blocking peptide or knockdown of CADM1 in BMMCs significantly decreased BMMC attachment to sensory neurites and abolished the enhanced secretory responses of mast cells. In conclusion, CADM1 is necessary and sufficient to drive mast cell-sensory neuron adhesion and promote the development of a microenvironment in which neurons enhance mast cell responsiveness to antigen; this interaction could explain why the incidence of painful neuroinflammatory disorders such as irritable bowel syndrome (IBS) are increased in atopic patients
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Timahdit sheep production and behavior at three stocking rates in the Moyen Atlas of Morocco
Liveweight (LW) changes and behavior of growing rams were measured in 1981, 1982, 1985, and 1986 at the Timahdit Experiment Station in the Middle Atlas, Morocco, at stocking rates of 2.78, 4.17, and 6.67 rams/ha during the growing season. Maximum animal production would have occurred at a stocking rate greater than any imposed in the study in all years except 1982. Increased variable costs should drive stocking rates down while increased selling price would provide an incentive to increase stocking rates. Mean grazing time of animals stocked at tight, moderate, and heavy rates was 410, 436, and 504 minutes/day, respectively. Mean resting time was 206, 174, and 106 minutes/day, respectively. Rams under light, moderate, and heavy stocking rates walked 2.1, 2.4, and 3.1 km/day, respectively. Diet IVDMD was highest early in the grazing season and lowest in the nongrowing season, and was not affected by stocking rates. Early in the spring, diet diversity was low, increased during active growth, and then deciined as the season advanced. Selectivity was lowest when forage was abundant. Dry matter intake varied with season in 1985 but not 1986. There was less opportmdty to be adaptive under heavy than under light stocking, resulting in a stocking rate by season interaction in 1986. Under heavy stocking, forage intake (G/kg LW/min) was 61 and 83% of intake under light and moderate stocking, respectively, and forage intake per km walked was 71 and 84%, respectivelyThis material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
Etude analytique et numérique de la réponse en vibration à hautes fréquences d'éprouvettes de fatigue vibratoire des métaux. Application aux aciers
In the present paper, the so-called " ultrasonic fatigue "
or fatigue at very high frequency has been studied in the materials elastic
behaviour case while neglecting the thermal effects that influence the
mechanical fields. The determination of mechanical fields and specimen
resonance length has been done both analytically and numerically. The numerical
method used for this calculation is the finite element method (FEM).
Martensitic steel " Soleil A2 " and austenitic steel " ICL 472 BC " have
been considered in order to compare the two methods (analytical and numerical).
It is shown that a perfect convergence is obtained between the two solutions.Dans le présent travail, la fatigue vibratoire a été étudiée
dans le cas du comportement élastique des matériaux en négligeant les effets
thermiques pouvant influencer les champs mécaniques. La détermination de ces
champs et de la longueur de résonance des éprouvettes de fatigue a été faite
analytiquement et numériquement. Le calcul numérique effectué se base sur la
méthode des éléments finis. Dans le but d'une comparaison des solutions
analytiques et numériques, deux aciers ont été considérés : un acier
martensitique (Soleil A2) et un acier austénitique de type 18-10 (ICL 472 BC).
Une parfaite convergence est obtenue entre les deux solutions
A case study of rangeland vegetation changes from 1979 to 2016 in the Middle Atlas Mountains of Morocco
This case study assessed changes in vegetation composition of a 0.8 ha rangeland site over the past four decades, in relation to changes in temperature and to an increase in grazing pressure. The frequency and standing crop (biomass) of species and functional groups were sampled in the spring of 1979 and 2016. Mean annual temperature increased, whereas changes in frequency varied between species and functional groups. Species that decreased included perennial plants, whereas species that increased were comprised mostly of annuals and unpalatable herbaceous plants. An NMDS ordination showed significant differences in species composition between 1979 and 2016. Total biomass, as well as the biomass of annual and perennial grasses and forbs did not differ between 1979 and 2016. Shrub biomass, however, decreased by 60% between years. Biomass of the ‘graminoids’ (e.g. Carex divisa), on the other hand, increased fourfold between 1979 and 2016. Species richness and the Shannon–Weaver diversity index H′ declined in 2016. This, together with a decline in the frequency of palatable species and a shift in species composition, could signal a decline in resilience over the long term. Changes in vegetation were most likely driven by a combination of higher temperatures and increased grazing pressure.
Keywords: climate change, plant community ecology, rangeland condition, resilienc
Changes in plant vegetation structure and diversity with distance from herder shelters in the Middle Atlas Mountains
Livestock grazing intensity gradients associated with sheep holder shelters influenced the longevity of rangelands vegetation. This study aimed to examine the effects of livestock grazing pressure on vegetation structure and diversity with distance from herder shelters. Six shelters were sampled. From each herder shelter, a grazing gradient was set aligned to the contour lines. Along each grazing gradient, we surveyed seven 100-m transects between 10 and 800 m from the herder shelter. The standing crop biomass (dry matter = DM) along the gradient from the shelters, bare soil, cover of vegetation functional groups and plant species diversity were determined using the point intercept method along each transect. Bare soil cover increased as we approached herder shelter. The total standing crop biomass (DM) (in g DM m−2) increased with the distance from the shelter. Shrub biomass decreased when approaching shelters, as so did the percentage of shrub cover. Cover of perennial forbs and grass also increased with distance from shelter, whereas annual cover increased as we approached the shelter. Species richness and diversity increased when moving away from the shelter. Changes in vegetation structure were not linear. Strong changes were detectable within the first 200 m, whereas little responses were found behind this threshold. The 200 m threshold should be used to monitor the main keystone species that preserved these rangelands