383 research outputs found
Land use history (1840â2005) and physiography as determinants of southern boreal forests
Land use history has altered natural disturbance dynamics, causing widespread modifications of the earth's forests. The aim of this study is to reconstruct a regional, spatially-explicit, fire and logging history for a large southern boreal forest landscape (6,050 km2) of eastern Canada. We then examined the long-term influence of land use history, fires, and physiographical gradients on the area's disturbances regimes, present-day age structure and tree species composition. Spatially-explicit fire (1820-2005) and logging (1900-2005) histories were reconstructed from forestry maps, terrestrial forest inventories and historical records (local newspapers, travel notes, regional historical reviews). Logistic regression was used to model the occurrence of major boreal tree species at the regional scale, in relation to their disturbance history and physiographical variables. The interplay of elevation and fire history was found to explain a large part of the present-day distribution of the four species studied. We conclude that human-induced fires following the colonization activities of the nineteenth and twentieth centuries have increased fire frequency and the dominance of fire-adapted species at lower elevations. At higher elevations, the low historical fire frequency has fostered the dominance of fire-sensitive species. Twentieth-century forestry practices and escaped settlement fires have generated a forest landscape dominated by younger forest habitats than in presettlement times. The expected increase of wildfire activity in North America's eastern boreal forest, in conjunction with continued forest management, could have significant consequences on the resilience of boreal forests
How do GP practices and patient characteristics influence the prescription of antidepressants? A cross-sectional study
BACKGROUND: Under-prescription of antidepressants (ADs) among people meeting the criteria for major depressive episodes and excessive prescription in less symptomatic patients have been reported. The reasons influencing general practitionersâ (GPs) prescription of ADs remain little explored. This study aimed at assessing the influence of GP and patient characteristics on AD prescription. METHODS: This cross-sectional study was based on a sample of 816 GPs working within the main health care insurance system in the Seine-Maritime district of France during 2010. Only GPs meeting the criteria for full-time GP practice were included. The ratio of AD prescription to overall prescription volume, a relative measure of AD prescription level, was calculated for each GP, using the defined daily dose (DDD) concept. Associations of this AD prescription ratio with GPsâ age, gender, practice location, number of years of practice, number of days of sickness certificates prescribed, number of home visits and consultations, number and mean age of registered patients, mean patient income, and number of patients with a chronic condition were assessed using univariate and multivariate analysis. RESULTS: The high prescribers were middle-aged (40â59) urban GPs, with a moderate number of consultations and fewer low-income and chronic patients. GPsâ workload (e.g., volume of prescribed drug reimbursement and number of consultations) had no influence on the AD prescription ratio. GPs with more patients with risk factors for depression prescribed fewer ADs, however, which could suggest the medications were under-prescribed among the at-risk population. CONCLUSIONS: Our study described a profile of the typical higher AD prescriber that did not include heavy workload. In future work, a more detailed assessment of all biopsychosocial components of the consultation and other influences on GP behavior such as prior training would be useful to explain AD prescription in GPâs practice. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12991-015-0041-7) contains supplementary material, which is available to authorized users
Antinuclear Antibodies in Patients with Psoriatic Arthritis Treated or Not with Biologics
International audienceBackground:With the emergence of biotherapies, accurate diagnosis in early arthritis is needed. At this time, there is no biological marker of psoriatic arthritis.Objective:To test whether antinuclear antibodies (ANA) can be used as a diagnostic tool in psoriatic arthritis (PsA), we evaluated the prevalence of ANA in biologic-naĂŻve PsA patients and in healthy blood donors.Methods:232 patients from the Rheumatology department, St Marguerite's Hospital, Marseilles, who fulfilled the CASPAR criteria for PsA, underwent clinical and laboratory investigations. Antinuclear antibodies (ANA), anti-extractable nuclear antigen antibodies (ENA), rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) were assayed. Ninety-one healthy blood donors were also tested.Results:Detection of ANA by indirect immunofluorescence was significantly more frequent in sera from PsA patients than those from controls at serum dilution of 1:100 (57% compared with 40%, Odds Ratio (OR) 1.98 (1.2-3.4) p<0.02) and 1:160 (52% compared with 24%, OR 3,7 (1.9-7.2) p<0.001). No patients had lupus specific autoantibodies, 15 % had RF (34/232), and 1.7 % had ACPA (4/232).Conclusions:Detection of ANA was more frequent in sera from PsA patients than in those from healthy controls. This suggests that ANA could be a diagnosis orientation tool in PsA. Nevertheless, the specificity of these antibodies still remains to be investigated
Patientsâ high acceptability of a future therapeutic HIV vaccine in France: a French paradox?
International audienc
Naturalness assessment performed using forestry maps to validate forest management sustainability
One-quarter of forest areas worldwide are managed for forestry purposes. Depending upon the type of practice and intensity of management, forestry may alter forests to various degrees and raise sustainability issues. To mitigate the alteration of natural forests by forestry and to promote sustainability, ecosystem management has been implemented widely over the past quarter century. A need remains for the development of comprehensive and operational assessment approaches to validate its effectiveness. Naturalness assessment could be used to validate effectiveness of ecosystem management since this concept relates to the degree to which a natural state has been altered. We developed an approach that integrates stand- and landscape- scale traits of naturalness into a single comprehensive assessment that can be performed using only forestry maps. To illustrate our approach, we assessed naturalness in four managed forest landscapes (2184 km2), representing a management gradient of increasing intensity from passive restoration to plantation forestry. We defined four naturalness classes, i.e., natural, semi-natural, altered and artificial. Assessment was performed in two steps. At step one, we attributed a class to each managed stand by comparing its current composition with natural stand compositions of its potential natural vegetation. At the landscape scale, certain developmental stages or forest types could be in excess in managed forest landscapes compared with natural forest landscapes. At step two, we transferred numbers of stages or types in excess from the natural class to more altered classes. We demonstrated that naturalness decreased as management intensity increased. Passive restoration and extensive management generated a landscape where semi-natural forests predominated in mixtures with a lower abundance of natural forests. Intensive management generated a largely semi-natural forest landscape. Plantation forestry generated a landscape where semi-natural and altered forests predominated. In conclusion, it should now be possible to validate the effectiveness of different practices and intensity of ecosystem management in promoting sustainability, by performing our assessment approach periodically following every update of forestry maps. Our approach could also allow for more comprehensive assessment of forest management strategies developed to mitigate global change by putting into better perspective their potential effects upon forest alteration of various forestry practices that have been implemented to sequester carbon
Autoantibodies to BRAF, a new family of autoantibodies associated with rheumatoid arthritis
International audienceBRAF (v raf murine sarcoma viral oncogene homologue B1) is a serine-threonine kinase involved in the mitogen-activated protein kinase (MAPK) signalling pathway, known to be implicated in the production of pro-inflammatory cytokines.We have observed that sera from rheumatoid arthritis (RA) patients recognize the BRAF's catalytic domain, which encompasses amino acids 416 to 766. Here, we identify peptide targets of anti-BRAF autoantibodies and test whether anti-BRAF autoantibodies may interfere with BRAF kinase activity.METHODS:Anti-BRAF autoantibodies were detected by ELISA (enzyme-linked immunosorbent assay) in the serum of RA patients and controls, using 40 overlapping 20mer peptides encompassing the catalytic domain of BRAF as immunosorbents. To test whether autoantibodies to BRAF influence BRAF kinase activity, we developed an in vitro phosphorylation assay of MEK1 (mitogen extracellular regulated kinase), a major BRAF substrate. MEK1 phosphorylation by BRAF was tested in the presence of purified anti-BRAF autoantibodies from RA patients or control antibody.RESULTS:We found that one BRAF peptide, P25 (656 to 675), is specifically recognized by autoantibodies from RA patients. Of interest, anti-P25 autoantibodies are detected in 21% of anti-CCP (cyclic citrullinated peptides) negative RA patients. Anti-BRAF autoantibodies activate the in vitro phosphorylation of MEK1 mediated by BRAF.CONCLUSIONS:Anti-BRAF autoantibodies from RA patients preferentially recognize one BRAF peptide: P25. Autoantibody responses to P25 are detected in 21% of anti-CCP negative RA patients. Most anti-BRAF autoantibodies activate BRAF kinase activity
Optimization of culture conditions for porcine corneal endothelial cells
Purpose : To optimize the growth condition of porcine corneal endothelial cells (PCEC), we evaluated the effect of coculturing with a feeder layer (irradiated 3T3 fibroblasts) with the addition of various exogenous factors, such as epidermal growth factor (EGF), nerve growth factor (NGF), bovine pituitary extract (BPE), ascorbic acid, and chondroitin sulfate, on cell proliferation, size, and morphology.
Methods : PCEC cultures were seeded at an initial cell density of 400 cells/cm2 in the presence or absence of 20,000 murine-irradiated 3T3 fibroblast/cm2 in the classic media Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 20% fetal bovine serum (FBS). Mean cell size and bromodeoxyuridine incorporation was assessed at various passages. Growth-promoting factors were studies by seeding PCEC at 8,000 cells/cm2 in DMEM with 20% FBS or Opti-MEM I supplemented with 4% FBS and one of the following additives: EGF (0.5, 5, 25 ng/ml), NGF (5, 20, 50 ng/ml), BPE (25, 50, 100, 200 ÎŒg/ml), ascorbic acid (10, 20, 40 ÎŒg/ml) and chondroitin sulfate (0.03, 0.08, 1.6%), alone or in combination. Cell number, size and morphology of PCEC were assessed on different cell populations. Each experiment was repeated at least twice in three sets. In some cases, cell cultures were maintained after confluence to observe post-confluence changes in cell morphology.
Results : Co-cultures of PCEC grown in DMEM 20% FBS with a 3T3 feeder layer improved the preservation of small polygonal cell shape. EGF, NGF, and chondroitin sulfate did not induce proliferation above basal level nor did these additives help maintain a small size. However, chondroitin sulfate did help preserve a good morphology. BPE and ascorbic acid had dose-dependent effects on proliferation. The combination of BPE, chondroitin sulfate, and ascorbic acid significantly increased cell numbers above those achieved with serum alone. No noticeable changes were observed when PCEC were cocultured with a 3T3 feeder layer in the final selected medium.
Conclusions : Improvements have been made for the culture of PCEC. The final selected medium consistently allowed the growth of a contact-inhibited cell monolayer of small, polygonal-shaped cells
IoT and information processing in smart energy applications.
The articles in this special section address smart energy applications from the perspective of the Internet of Things (IoT). For smart grid applications, we need to predict the electrical load so that the underlying smart grid can effectively balance the power supply and demand. In general, predictions are made based on the data obtained using IoT and smart meter technologies. The (IoT) could accelerate establishment of such infrastructures. With IoT technologies, many more devices could be controlled and managed through the Internet; data pertaining to the grid, commercial buildings, and residential premises can readily be collected and utilized. To derive valuable information from the data, further information and data processing become essential
Factors influencing black spruce reproductive potential in the northern boreal forest of Quebec
Abstract
The reproductive ecology of the semi-serotinous species black spruce (Picea mariana (Mill.) BSP) in northern boreal forests remains poorly understood. There is a general lack of data on cone/seed production and viability as a function of biotic tree-level characteristics and abiotic variables. No studies currently exist to quantify these differences over a large gradient in temperature, elevation, and precipitation. Extensive physical, ecological, dendrometric, and reproductive data were collected from young to very old black spruce stands in northern Quebec. ANOVA and general linear mixed models were used to examine interannual cone production, and the relative importance of the biotic and abiotic explanatory factors in determining total cone production; length of the cone-bearing zone; filled seeds per cone; proportion of filled seeds; and seed viability. The results illustrate that the reproductive ecology of black spruce in northern cold forests is mainly explained by biotic variables such as age and diameter at breast height, and by abiotic variables related to temperature such as elevation, length of the growing season, and growing degree-days. Black spruce exhibits a lower reproductive potential in northern cold forests, making it possibly less resilient to increased fire frequency, particularly in unproductive and very young or very old stands.
Résumé
L'Ă©cologie de la reproduction de l'espĂšce semi-serotineuse, l'Ă©pinette noire (Picea mariana (Mill.) BSP) dans les forĂȘts borĂ©ales froides est encore peu documentĂ©e. Il existe un manque gĂ©nĂ©ral de donnĂ©es sur la production des cĂŽnes/graines et leur viabilitĂ© en fonction des caractĂ©ristiques biotiques au niveau de l'arbre et des variables abiotiques. Aucune Ă©tude nâexiste actuellement pour quantifier ces diffĂ©rences sur un large gradient de tempĂ©rature, d'altitude, et de prĂ©cipitations. De nombreuses donnĂ©es physiques, Ă©cologiques, dendromĂ©triques et reproductives ont Ă©tĂ© recueillies dans des peuplements dâĂ©pinette noire jeunes Ă trĂšs ĂągĂ©s dans le nord du QuĂ©bec. Des ANOVA et des modĂšles mixtes linĂ©aires gĂ©nĂ©raux ont Ă©tĂ© utilisĂ©s pour examiner la production annuelle de cĂŽnes et l'importance relative des facteurs explicatifs biotiques et abiotiques dans la dĂ©termination de la production totale de cĂŽnes; la longueur de la cime comportant des cĂŽnes; le nombre de graines pleines par cĂŽne; la proportion de graines pleines; et leur taux de germination. Les rĂ©sultats indiquent que l'Ă©cologie de la reproduction de l'Ă©pinette noire dans les forĂȘts borĂ©ales nordiques est expliquĂ©e par des variables biotiques telles que l'Ăąge et le DHP, et des variables abiotiques liĂ©es Ă la somme thermique rĂ©gionale telles que l'altitude, la durĂ©e de la saison de croissance, et les degrĂ©s-jours de croissance. L'Ă©pinette noire prĂ©sente un potentiel reproductif plus faible dans les forĂȘts froides du nord, ce qui la rend moins rĂ©sistante Ă l'augmentation de la frĂ©quence des feux, particuliĂšrement dans les peuplements improductifs et trĂšs jeunes ou trĂšs vieux
Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea
Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980â2013 and a detailed multi-indicator description of the period 2007â2013. Then a 1980â2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the dense water volume, increase in the bottom water density) despite an underestimation of the salinity and density trends. These deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the Gulf of Lions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. The salinity increase in the near Atlantic Ocean surface layers seems to be the external forcing that finally leads to these deep trends. In the future, our results may allow to better understand the behaviour of the DWF phenomenon in Mediterranean Sea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. The robustness of the obtained results must be however confirmed in multi-model studies
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