62 research outputs found
The Rise of Community-Based Natural Resource Management Strategies as Explained by Transaction Costs
Community-based natural resource management (CBNRM) is favored over its predecessor, the fortress approach, for common pool resource (CPR) management. We strive to identify variables associated with successful CBNRM programs, and analyze whether their presence transaction costs can explain the shift in favored conservation strategy. By examining nine case studies of large mammals in Africa, we found that out of eight variables, moderate monitoring and adequate program incentives were the most critical various factors in determining CBNRM program outcomes. Furthermore, these variables, as well as others, contributed to a decrease in transaction costs
Spatial characterization of wildfire orientation patterns in California
Using 100 years of fire perimeter maps, we investigate the existence of
geographical patterns in fire orientation across California. We computed fire perimeter
orientation, at the watershed level, using principal component analysis. Circular statistics
were used to test for the existence of preferential fire perimeter orientations. Where
perimeters displayed preferential orientation, we searched for evidence of orographic
channeling by comparing mean fire orientation with watershed orientation. Results show
that in California, 49% of the burnt area is associated with watersheds, where fires displayed
preferential orientation. From these, 25% of the burnt area is aligned along the NE/SW
orientation and 18% in the E/W orientation. In 27 out of 86 watersheds with preferential
fire alignment, there is also correspondence between mean fire orientation and watershed
orientation. Topographic influence on fire spread and dominant wind patterns during the fire
season can account for the consistency in fire perimeter orientation in these regions. Our
findings highlight the historical pattern of fire perimeter orientation and identify watersheds
with potential orographic channelingThis paper was supported
by the Fundação para a Ciência e Tecnologia Ph.D. Grant SFRH/BD/40398/2007. JMCP participated in
this research under the framework of research projects “Forest fire under climate, social and economic
changes in Europe, the Mediterranean and other fire-affected areas of the world (FUME)”, EC FP7 Grant
Agreement No. 243888
Mapping changing distributions of dominant species in oil-contaminated salt marshes of Louisiana using imaging spectroscopy
The April 2010 Deepwater Horizon (DWH) oil spill was the largest coastal spill in U.S. history. Monitoring subsequent change in marsh plant community distributions is critical to assess ecosystem impacts and to establish future coastal management priorities. Strategically deployed airborne imaging spectrometers, like the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), offer the spectral and spatial resolution needed to differentiate plant species. However, obtaining satisfactory and consistent classification accuracies over time is a major challenge, particularly in dynamic intertidal landscapes.Here, we develop and evaluate an image classification system for a time series of AVIRIS data for mapping dominant species in a heavily oiled salt marsh ecosystem. Using field-referenced image endmembers and canonical discriminant analysis (CDA), we classified 21 AVIRIS images acquired during the fall of 2010, 2011 and 2012. Classification results were evaluated using ground surveys that were conducted contemporaneously to AVIRIS collection dates. We analyzed changes in dominant species cover from 2010 to 2012 for oiled and non-oiled shorelines.CDA discriminated dominant species with a high level of accuracy (overall accuracy=82%, kappa=0.78) and consistency over three imaging dates (overall2010=82%, overall2011=82%, overall2012=88%). Marshes dominated by Spartina alterniflora were the most spatially abundant in shoreline zones (â¤28m from shore) for all three dates (2010=79%, 2011=61%, 2012=63%), followed by Juncus roemerianus (2010=11%, 2011=19%, 2012=17%) and Distichlis spicata (2010=4%, 2011=10%, 2012=7%).Marshes that were heavily contaminated with oil exhibited variable responses from 2010 to 2012. Marsh vegetation classes converted to a subtidal, open water class along oiled and non-oiled shorelines that were similarly situated in the landscape. However, marsh loss along oil-contaminated shorelines doubled that of non-oiled shorelines. Only S. alterniflora dominated marshes were extensively degraded, losing 15% (354,604m2) cover in oiled shoreline zones, suggesting that S. alterniflora marshes may be more vulnerable to shoreline erosion following hydrocarbon stress, due to their landscape position
Genus Paracoccidioides: Species Recognition and Biogeographic Aspects
Background: Paracoccidioidomycosis is a systemic mycosis caused by Paracoccidioides brasiliensis (species S1, PS2, PS3), and Paracoccidioides lutzii. This work aimed to differentiate species within the genus Paracoccidioides, without applying multilocus sequencing, as well as to obtain knowledge of the possible speciation processes. Methodology/Principal Findings:
Single nucleotide polymorphism analysis on GP43, ARF and PRP8 intein genes successfully distinguished isolates into four different species. Morphological evaluation indicated that elongated conidia were observed exclusively in P. lutzii isolates, while all other species (S1, PS2 and PS3) were indistinguishable. To evaluate the biogeographic events that led to the current geographic distribution of Paracoccidioides species and their sister species, Nested Clade and Likelihood Analysis of Geographic Range Evolution (LAGRANGE) analyses were applied. The radiation of Paracoccidioides started in northwest South America, around 11–32 million years ago, as calculated on the basis of ARF substitution rate, in the BEAST program. Vicariance was responsible for the divergence among S1, PS2 and P. lutzii and a recent dispersal generated the PS3 species, restricted to Colombia. Taking into account the ancestral areas revealed by the LAGRANGE analysis and the major geographic distribution of L. loboi in the Amazon basin, a region strongly affected by the Andes uplift and marine incursions in the Cenozoic era, we also speculate about the effect of these geological events on the vicariance between Paracoccidioides and L. loboi. Conclusions/Significance: The use of at least 3 SNPs, but not morphological criteria, as markers allows us to distinguish among the four cryptic species of the genus Paracoccidioides. The work also presents a biogeographic study speculating on how these species might have diverged in South America, thus contributing to elucidating evolutionary aspects of the genus Paracoccidioides
Integrins promote axonal regeneration after injury of the nervous system.
Integrins are cell surface receptors that form the link between extracellular matrix molecules of the cell environment and internal cell signalling and the cytoskeleton. They are involved in several processes, e.g. adhesion and migration during development and repair. This review focuses on the role of integrins in axonal regeneration. Integrins participate in spontaneous axonal regeneration in the peripheral nervous system through binding to various ligands that either inhibit or enhance their activation and signalling. Integrin biology is more complex in the central nervous system. Integrins receptors are transported into growing axons during development, but selective polarised transport of integrins limits the regenerative response in adult neurons. Manipulation of integrins and related molecules to control their activation state and localisation within axons is a promising route towards stimulating effective regeneration in the central nervous system
Bile acid effects are mediated by ATP release and purinergic signalling in exocrine pancreatic cells
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