Subduction dynamics and the origin of Andean orogeny and the Bolivian orocline.

The building of the Andes results from the subduction of the oceanic Nazca plate underneath the South American continent. However, how and why the Andes and their curvature, the Bolivian orocline, formed in the Cenozoic era (65.5 million years (Myr) ago to present), despite subduction continuing since the Mesozoic era (251.0-65.5 Myr ago), is still unknown. Three-dimensional numerical subduction models demonstrate that variations in slab thickness, arising from the Nazca plate's age at the trench, produce a cordilleran morphology consistent with that observed. The age-dependent sinking of the slab in the mantle drives traction towards the trench at the base of the upper plate, causing it to thicken. Thus, subducting older Nazca plate below the Central Andes can explain the locally thickened crust and higher elevations. Here we demonstrate that resultant thickening of the South American plate modifies both shear force gradients and migration rates along the trench to produce a concave margin that matches the Bolivian orocline. Additionally, the varying forcing along the margin allows stress belts to form in the upper-plate interior, explaining the widening of the Central Andes and the different tectonic styles found on their margins, the Eastern and Western Cordilleras. The rise of the Central Andes and orocline formation are directly related to the local increase of Nazca plate age and an age distribution along the margin similar to that found today; the onset of these conditions only occurred in the Eocene epoch. This may explain the enigmatic delay of the Andean orogeny, that is, the formation of the modern Andes.

Cenozoic tectonics of western North America controlled by evolving width of Farallon slab.

Subduction of oceanic lithosphere occurs through two modes: subducting plate motion and trench migration. Using a global subduction zone data set and three-dimensional numerical subduction models, we show that slab width (W) controls these modes and the partitioning of subduction between them. Subducting plate velocity scales with W(2/3), whereas trench velocity scales with 1/W. These findings explain the Cenozoic slowdown of the Farallon plate and the decrease in subduction partitioning by its decreasing slab width. The change from Sevier-Laramide orogenesis to Basin and Range extension in North America is also explained by slab width; shortening occurred during wide-slab subduction and overriding-plate-driven trench retreat, whereas extension occurred during intermediate to narrow-slab subduction and slab-driven trench retreat.

Diagnostic utility of the Quick Inventory of Depressive Symptomatology (QIDS-C16 and QIDS-SR16) in the elderly.

OBJECTIVE: To evaluate psychometric properties and comparability ability of the Montgomery-Asberg Depression Rating Scale (MADRS) vs. the Quick Inventory of Depressive Symptomatology-Clinician-rated (QIDS-C(16)) and Self-report (QIDS-SR(16)) scales to detect a current major depressive episode in the elderly. METHOD: Community and clinic subjects (age >or=60 years) were administered the Mini-International Neuropsychiatric Interview (MINI) for DSM-IV and three depression scales randomly. Statistics included classical test and Samejima item response theories, factor analyzes, and receiver operating characteristic methods. RESULTS: In 229 elderly patients (mean age = 73 years, 39% male, 54% current depression), all three scales were unidimensional and with nearly equal Cronbach alpha reliability (0.85-0.89). Each scale discriminated persons with major depression from the non-depressed, but the QIDS-C(16) was slightly more accurate. CONCLUSION: All three tests are valid for detecting geriatric major depression with the QIDS-C(16) being slightly better. Self-rated QIDS-SR(16) is recommended as a screening tool as it is least expensive and least time consuming.

Evolution and diversity of subduction zones controlled by slab width.

Subducting slabs provide the main driving force for plate motion and flow in the Earth's mantle, and geodynamic, seismic and geochemical studies offer insight into slab dynamics and subduction-induced flow. Most previous geodynamic studies treat subduction zones as either infinite in trench-parallel extent (that is, two-dimensional) or finite in width but fixed in space. Subduction zones and their associated slabs are, however, limited in lateral extent (250-7,400 km) and their three-dimensional geometry evolves over time. Here we show that slab width controls two first-order features of plate tectonics-the curvature of subduction zones and their tendency to retreat backwards with time. Using three-dimensional numerical simulations of free subduction, we show that trench migration rate is inversely related to slab width and depends on proximity to a lateral slab edge. These results are consistent with retreat velocities observed globally, with maximum velocities (6-16 cm yr(-1)) only observed close to slab edges (<1,200 km), whereas far from edges (>2,000 km) retreat velocities are always slow (<2.0 cm yr(-1)). Models with narrow slabs (< or =1,500 km) retreat fast and develop a curved geometry, concave towards the mantle wedge side. Models with slabs intermediate in width ( approximately 2,000-3,000 km) are sublinear and retreat more slowly. Models with wide slabs (> or =4,000 km) are nearly stationary in the centre and develop a convex geometry, whereas trench retreat increases towards concave-shaped edges. Additionally, we identify periods (5-10 Myr) of slow trench advance at the centre of wide slabs. Such wide-slab behaviour may explain mountain building in the central Andes, as being a consequence of its tectonic setting, far from slab edges.

Management of spontaneous inhibitors in children with porcine factor VIII.

Acquired factor VIII (FVIII) inhibitors are rare, typically occurring in the postpartum period or in the elderly. Their occurrence in childhood is distinctly unusual. Acquired FVIII inhibitors are often life-threatening and refractory to treatment with high doses of human FVIII concentrate. Alternative strategies for control of haemostasis include the use of products with FVIII "bypassing" activity or porcine FVIII (pFVIII) concentrate if the pFVIII titre is sufficiently low (<10-20 porcine Bethesda Units). Corticosteroids and other immunosuppressive therapies are inconsistently effective in eliminating FVIII inhibitors. Accordingly, acquired FVIII inhibitors often require long-term haemostatic management.

[Peak pulse blood volume and topical antiglaucoma drugs in rhesus monkeys with experimental open angle glaucoma]. / Pulsgipfelblutvolumen und topische Antiglaukomatosa bei Rhesusaffen mit experimentellem Offenwinkelglaukom.

BACKGROUND: The present study was designed to investigate the effect of topical antiglaucoma drugs on Peak Pulse Blood Volume (PPBV; German abbreviation: PGBV) in cynomolgus monkey eyes without (CMNG; German abbreviation: RA-KTL) and with lasersurgically induced glaucoma (CMG; German abbreviation: RA-LHDG). METHODS: CMG unilaterally received 2-3 laser treatments so as to develop the lasered-eye glaucoma model. Intraocular pressure (IOP; German abbreviation: IOD) and Ocular Pulse Amplitude were measured and PPBV was determined until the glaucoma model had stabilized. Consecutively topical antiglaucoma drugs (epinephrine, paraaminoclonidine, pilocarpine, timolol) were investigated in 4-8 animals in CMNG and CMG eyes. RESULTS: IOP and PPBV were not significantly altered in CMNG. In the CMG eyes epinephrine and paraaminoclonidine did not significantly alter IOP or PPBV, whereas pilocarpine and timolol sig. (p < 0.01) reduced IOP and significantly (p < 0.05) increased PPBV. CONCLUSION: With respect to improved PPBV in the CMG eye the rank order of drug effectiveness is timolol > pilocarpine > paraaminoclonidine > epinephrine.

Studies of the ocular pulse in primates.

Ocular pulse amplitude (OPA) and intraocular pressure (IOP) were measured in groups of human subjects with primary open-angle glaucoma (POAG), ocular hypertension (OHT), low-tension glaucoma (LTG), retinal degenerations (RD), in OHT volunteers treated with single doses of 2% epinephrine, 4% pilocarpine, 0.5% timolol or 1% p-amino-clonidine, and in normal subjects before and after exercise. Compared to normal controls, OHT subjects showed significantly higher IOP and OPA, while OPA was significantly lower in ocular normotensive LTG and RD subjects groups. All drug treatments lowered IOP in OHT subjects, but did not change OPA significantly. Exercise in normal volunteers increased calculated ocular perfusion pressure by 22.5%, lowered IOP by 32%, but showed no significant change in OPA. When IOP was elevated > or = 5 mmHg in lasered monkey eyes peak pulse volume (PPV) was increased significantly in the unlasered eyes. Epinephrine 2% or 1% p-aminoclonidine lowered IOP moderately with no change in PPV, while treatment with 4% pilocarpine or 0.5% timolol reduced IOP and increased PPV significantly. The findings suggest that LTG may be associated with an ocular vascular abnormality. OPA in OHT or normal human subjects did not change when IOP was decreased by antiglaucoma drug treatments or exercise, respectively. These results indicate that OPA may be physiologically autoregulated in human subjects with IOPs in the 11-21 mmHg range. However, laser-induced glaucomatous monkey eyes with higher IOP (30-35 mmHg) did not autoregulate, but showed a low peak pulse volume, which increased when IOP was reduced 5 mmHg or more by means of antiglaucoma drug treatment.