University of the Philippines

About: University of the Philippines is a education organization based out in Quezon City, Philippines. It is known for research contribution in the topics: Population & Health care. The organization has 4589 authors who have published 4437 publications receiving 114846 citations. The organization is also known as: UP.

Deformed symmetrical volcanoes

Abstract: Analog modeling of volcanic cones traversed by strike-slip faulting was conducted, and the cones were analyzed for deformation characteristics. The study shows that symmetrical volcanoes that have undergone basal strike-slip offset may be deformed internally without manifesting any change in their conical shape. Volcanoes deformed by strike-slip faulting may already have well-developed fractures in their interior, yet still appear as a symmetrical cone, exhibiting concentric contours when viewed on a topographic map. Moreover, slight changes in the basal shape of the cone induced by strike-slip movement can be restored by the relatively faster resurfacing and reshaping processes from the deposition of younger eruptive products. These findings pose a subtle but significant point in the assessment of volcanic landslide hazards: not all perfect cones are undisturbed. The detection of concealed deformation is important because fractures induce further instability in volcanoes and act as slip planes during volcano-collapse events. There are many examples of symmetrical volcanoes in nature. The faultless appearance of such perfect cones can be misleading, which requires careful attention in hazards assessment.

αS-Conotoxin RVIIIA: A Structurally Unique Conotoxin That Broadly Targets Nicotinic Acetylcholine Receptors†

Abstract: We report the purification and characterization of a new conotoxin from the venom of Conus radiatus. The peptide, αS-conotoxin RVIIIA (αS-RVIIIA), is biochemically unique with respect to its amino acid sequence, post-translational modification, and molecular targets. In comparison to other nicotinic antagonists from Conus venoms, αS-RVIIIA exhibits an unusually broad targeting specificity for nicotinic acetylcholine receptor (nAChR) subtypes, as assayed by electrophysiology. The toxin is paralytic to mice and fish, consistent with its nearly irreversible block of the neuromuscular nAChR. Similar to other antagonists of certain neuronal nAChRs, the toxin also elicits seizures in mice upon intracranial injection. The only previously characterized conotoxin from the S superfamily, σ-conotoxin GVIIIA, is a specific competitive antagonist of the 5-HT3 receptor; thus, αS-RVIIIA defines a novel family of nicotinic antagonists within the S superfamily. All previously characterized competitive conotoxin nAChR anta...