897 research outputs found
Identifying explanatory factors of bitcoin price with artificial neural networks
This study aims to develop a new model that allows determining with high precision the factors that explain the price of bitcoin. To do this, an extensive database of variables related to bitcoin and artificial neural network techniques has been used. The results obtained have made it possible to identify that aspects related to the number of forum posts, the volume of transactions on the blockchain, and the hash rate provide an excellent strategy for predicting the price of bitcoi
Evaluating functional diversity conservation for freshwater fishes resulting from terrestrial protected areas
Protected areas are one of the hammers in conservation toolkits, yet few protected areas exist that were designed to protect freshwater ecosystems. This is problematic as freshwater ecosystems are among the most threatened systems on earth. Nonetheless, terrestrial protected areas (TPAs) may afford spillâover benefits to freshwater ecosystems included within their boundaries, but evaluations of these potential benefits for the protection of freshwater fish diversity are lacking.Using fish community data from 175 lakes inside, outside, or bordering TPAs in Ontario, Canada, we sought to determine if TPAs preserve fish functional diversity. We focused on functional diversity because previous work indicated no taxonomic differences between these lakes, but a difference in normalisedâlength sizeâspectra slopes inside versus outside TPAs (indicator of unique predatorâprey ratios and trophic energy transfer). We expected that communities inside TPAs would show greater functional diversity (i.e. functional dispersion and functional richness) and have more extreme trait combinations (i.e. functional divergence) than communities outside or bordering TPAs. We also tested for differences in the rarity of speciesâspecific functional traits between fish communities inside, outside, or bordering TPAs, between thermal guilds, and across average body size and overall prevalence of the species.Our results indicated no significant differences in functional diversity among lake fish communities inside, outside, or bordering TPAs. However, fish communities inside TPAs had more extreme trait combinations than outside TPAs because abundant species in lake communities outside TPAs had more ubiquitous trait combinations than abundant fishes inside TPAs.Smallâbodied species showed greater functional rarity than largeâbodied species, indicating that smallâbodied fishes fill functionally unique roles while the most prevalent, largeâbodied species possess a more generalist set of traits.Overall, the similarity of functional diversity metrics for lake fish communities inside, outside, or bordering TPAs in Ontario suggests that TPAs capture the functional diversity of Ontarioâs lake fish communities. However, we encourage similar evaluations in regions where environmental conditions and stressors are more distinct across TPA boundaries than they are in Ontario, as these types of evaluations will inform guidelines for the design of freshwater protected areas and monitoring of their effectiveness in the future.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151997/1/fwb13395.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151997/2/fwb13395_am.pd
PDE8 controls CD4(+) T cell motility through the PDE8A-Raf-1 kinase signaling complex
The levels of cAMP are regulated by phosphodiesterase enzymes (PDEs), which are targets for the treatment of inflammatory disorders. We have previously shown that PDE8 regulates T cell motility. Here, for the first time, we report that PDE8A exerts part of its control of T cell function through the V-raf-1 murine leukemia viral oncogene homolog 1 (Raf-1) kinase signaling pathway. To examine T cell motility under physiologic conditions, we analyzed T cell interactions with endothelial cells and ligands in flow assays. The highly PDE8-selective enzymatic inhibitor PF-04957325 suppresses adhesion of in vivo myelin oligodendrocyte glycoprotein (MOG) activated inflammatory CD4(+) T effector (Teff) cells to brain endothelial cells under shear stress. Recently, PDE8A was shown to associate with Raf-1 creating a compartment of low cAMP levels around Raf-1 thereby protecting it from protein kinase A (PKA) mediated inhibitory phosphorylation. To test the function of this complex in Teff cells, we used a cell permeable peptide that selectively disrupts the PDE8A-Raf-1 interaction. The disruptor peptide inhibits the Teff-endothelial cell interaction more potently than the enzymatic inhibitor. Furthermore, the LFA-1/ICAM-1 interaction was identified as a target of disruptor peptide mediated reduction of adhesion, spreading and locomotion of Teff cells under flow. Mechanistically, we observed that disruption of the PDE8A-Raf-1 complex profoundly alters Raf-1 signaling in Teff cells. Collectively, our studies demonstrate that PDE8A inhibition by enzymatic inhibitors or PDE8A-Raf-1 kinase complex disruptors decreases Teff cell adhesion and migration under flow, and represents a novel approach to target T cells in inflammation
Ultrasonographic assessment of urinary tract lesions due to Schistosoma haematobium in Niger after four consecutive years of treatment with praziquantel
Une Ă©tude comparative sur l'Ă©tendue des lĂ©sions du tractus urinaire dĂ©tectĂ©es par Ă©chographie a Ă©tĂ© entreprise dans 2 villages du Niger situĂ©s prĂšs de pĂ©rimĂštres irriguĂ©s. La prĂ©valence de la schistosomiase urinaire Ă©tait respectivement de 64,3 % et de 58,8 %. AprĂšs un traitement au praziquantel de 4 annĂ©es consĂ©cutives, les lĂ©sions vĂ©sicales atteignaient 20 % dans le village traitĂ© et 54 % dans le tĂ©moin, les lĂ©sions rĂ©nales 6 % dans le village traitĂ© et 36 % dans le tĂ©moin. Ces rĂ©sultats montrent que la morbiditĂ© de la schistosomiase urinaire peut ĂȘtre rĂ©duite par un traitement annuel sur plusieurs annĂ©es sans autre forme d'interventio
Multimode solutions of first-order elliptic quasilinear systems obtained from Riemann invariants
Two new approaches to solving first-order quasilinear elliptic systems of
PDEs in many dimensions are proposed. The first method is based on an analysis
of multimode solutions expressible in terms of Riemann invariants, based on
links between two techniques, that of the symmetry reduction method and of the
generalized method of characteristics. A variant of the conditional symmetry
method for constructing this type of solution is proposed. A specific feature
of that approach is an algebraic-geometric point of view, which allows the
introduction of specific first-order side conditions consistent with the
original system of PDEs, leading to a generalization of the Riemann invariant
method for solving elliptic homogeneous systems of PDEs. A further
generalization of the Riemann invariants method to the case of inhomogeneous
systems, based on the introduction of specific rotation matrices, enables us to
weaken the integrability condition. It allows us to establish a connection
between the structure of the set of integral elements and the possibility of
constructing specific classes of simple mode solutions. These theoretical
considerations are illustrated by the examples of an ideal plastic flow in its
elliptic region and a system describing a nonlinear interaction of waves and
particles. Several new classes of solutions are obtained in explicit form,
including the general integral for the latter system of equations
- âŠ