Short-term memory load and pronunciation rate

In a test of short-term memory recall, two subjects attempted to recall various lists. For unpracticed subjects, the time it took to read the list is a better predictor of immediate recall than the number of items on the list. For practiced subjects, the two predictors do about equally well. If the items that must be recalled are unfamiliar, it is advantageous to keep the items short to pronounce. On the other hand, if the same items will be encountered over and over again, it is advantageous to make them distinctive, even at the cost of adding to the number of syllables

Additive factors and stages of mental processes in task networks.

To perform a task a subject executes mental processes. An experimental manipulation, such as a change in stimulus intensity, is said to selectively influence a process if it changes the duration of that process leaving other process durations unchanged. For random process durations a definition of a factor selectively influencing a process by increments is given in terms of stochastic dominance (also called “the usual stochastic order”. A technique for analyzing reaction times, Sternberg\u27s Additive Factor Method, assumes all the processes are in series. When all processes are in series, each process is called a stage. With the Additive Factor Method, if two experimental factors selectively influence two different stages by increments, the factors will have additive effects on reaction time. An assumption of the Additive Factor Method is that if two experimental factors interact, then they influence the same stage. We consider sets of processes in which some pairs of processes are sequential and some are concurrent (i. e., the processes are partially ordered). We propose a natural definition of a stage for such sets of processes. For partially ordered processes, with our definition of a stage, if two experimental factors selectively influence two different processes by increments, each within a different stage, then the factors have additive effects. If each process selectively influenced by increments is in the same stage, then an interaction is possible, although not inevitable

Paleomagnetism of Jurassic Rocks in the Western Sierra Nevada Metamorphic Belt and its Bearing on the Structural Evolution of the Sierra Nevada Block

The western metamorphic belt of the Sierra Nevada consists of two eugeosynclinal terranes separated by the Melones and Sonora faults. Subvertical, bedded Mesozoic volcanic rocks metamorphosed to low greenschist facies predominate to the west, whereas Paleozoic metamorphic rocks of higher grade and greater structural complexity predominate to the east. In order to study the structural development of the faults, 121 samples of basalt and diabase were collected for paleomagnetic analysis from three Jurassic formations, the Logtown Ridge and Penon Blanco formations west of the Melones fault and the Sonora dike swarm to the east of the Sonora fault. A northwesterly, downward directed magnetization occurs in each unit. Three fold tests and a conglomerate test on the two formations west of the faults show that the magnetization is secondary, postdating Nevadan (Late Jurassic) folding and is probably coeval with peak metamorphism. An average of five paleomagnetic poles from the Sierra Nevada, three derived from the secondary magnetizations given herein and two previously published, all of probable Kimmeridgian age, yields λ′=67.2°N, ϕ′=161.2°E, and α95 =6.5°. Southeasterly magnetizations also occur in the Logtown Ridge Formation and Sonora dike swarm. Directions from the Sonora dikes are approximately antipodal to the secondary directions and are reversed; magnetizations from the Logtown Ridge Formation yield similar results only if corrected for the tilt of bedding. The Logtown Ridge magnetizations (tilt-corrected) yield a pole position near to that expected for North America. The data from the Sonora dikes require a tilt correction of 25°-30° toward the south-southwest about a horizontal axis parallel to the regional structure in order to yield a North American pole position. We conclude that the eastern wall rocks of the Melones and Sonora faults have been rotated 25°-30° in response to Nevadan deformation in contrast to the western wall rocks, which have been rotated about 90°

Magnitude of crustal extension across the northern Basin and Range province: constraints from paleomagnetism

The magnitude of crustal extension across the northern Basin and Range province is a matter of longstanding controversy; estimates range from 10 to 300%. Recently published estimates of extension across the southern Basin and Range province (36[deg]N) are in the range of 80-100%. Thus, the larger values suggested for the northern part of the province (40[deg]N) seem to require substantial counterclockwise rotation of the Sierra Nevada during Tertiary extension. Paleomagnetic data from the range, however, limit rotation to 4 +/- 10[deg] at the 95% confidence level. These limits, combined with estimates of extension near the Garlock fault, allow severe constraints to be placed on the magnitude of extension across more northerly parts of the province. We conclude that the maximum extension at 40[deg]N is about 50% and that values of 39 +/- 12% (188 +/- 43 km) are likely.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25578/1/0000122.pd

Evidence of Uppermost Proterozoic to Lower Cambrian miogeoclinal rocks and the Mojave-Snow Lake Fault: Snow Lake Pendant, central Sierra Nevada, California

This is the published version. Copyright 2010 American Geophysical Union. All Rights Reserved.Displaced uppermost Precambrian to Lower Cambrian miogeoclinal strata occur within Snow Lake pendant in the central Sierra Nevada. These rocks have been correlated with the Stirling Quartzite, the Wood Canyon Formation, the Zabriskie Quartzite, and the Carrara Formation in the western Mojave Desert and the San Bernardino Mountains (Lahren and Schweickert, 1989; Lahren, 1989). This correlation is based on new, updated, and previously reported data including (1) lithologic similarities, (2) overall stratigraphic sequence, (3) vertical sequence within individual formations, (4) approximate stratigraphic thicknesses, (5) Skolithos in the correct stratigraphie position, (6) depositional environments, and (7) petrographic character and provenance of quartz arenites. The correlation is strengthened by the fact that Snow Lake pendant and the western Mojave share many other close similarities including (1) initial 87Sr/86Sr ratios of associated granitic rocks >0.706, (2) passive margin tectonic setting of Precambrian to Cambrian miogeoclinal rocks, (3) dikes of the Independence dike swarm, (4) possible Lower Triassic overlap sequence, the Fairview Valley Formation, (5) petrographically similar gabbroic complexes of the same age, (6) associated eugeoclinal rocks, and (7) identical(?) pre-Tertiary structural configuration. New U/Pb zircon geochronology unequivocally shows that dikes at Snow Lake pendant are coeval with the Independence dike swarm of the eastern Sierra and the western Mojave desert and that associated gabbroic complexes in both the Mojave and Snow Lake pendant are the same age. Correlation of Snow Lake pendant with the western Mojave requires about 400 km of dextral displacement of the rocks of Snow Lake pendant, together with associated rocks (Snow Lake block), from the western Mojave Desert along the Mojave-Snow Lake fault. Displacement most likely occurred after 150 Ma, the age of the Independence dike swarm, and before about 110 Ma, the age of major plutons within the Sierra Nevada batholith. This interpretation, if correct, holds major implications for allochthonous terranes west of Snow Lake pendant, which were probably attached to the Snow Lake block before its northward transport. In addition, a number of Paleozoic and Mesozoic tectonic features in western Nevada and eastern California may have been offset dextrally along the proposed Mojave-Snow Lake fault

ATP4 and ciliation in the neuroectoderm and endoderm of Xenopus embryos and tadpoles

AbstractDuring gastrulation and neurulation, foxj1 expression requires ATP4a-dependent Wnt/β-catenin signaling for ciliation of the gastrocoel roof plate (Walentek et al. Cell Rep. 1 (2012) 516–527.) and the mucociliary epidermis (Walentek et al. Dev. Biol. (2015)) of Xenopus laevis embryos. These data suggested that ATP4a and Wnt/β-catenin signaling regulate foxj1 throughout Xenopus development. Here we analyzed whether foxj1 expression was also ATP4a-dependent in other ciliated tissues of the developing Xenopus embryo and tadpole. We found that in the floor plate of the neural tube ATP4a-dependent canonical Wnt signaling was required for foxj1 expression, downstream of or in parallel to Hedgehog signaling. In the developing tadpole brain, ATP4-function was a prerequisite for the establishment of cerebrospinal fluid flow. Furthermore, we describe foxj1 expression and the presence of multiciliated cells in the developing tadpole gastrointestinal tract. Our work argues for a general requirement of ATP4-dependent Wnt/β-catenin signaling for foxj1 expression and motile ciliogenesis throughout Xenopus development

Paleotectonic and paleogeographic significance of the Calaveras Complex, western Sierra Nevada, California

The Calaveras Complex of the western Sierra Nevada, as defined here, consists of a 375 km long, 35 km wide belt of metasedimentary and metavolcanic rocks, bounded on the west by the Melones fault zone and Kings-Kaweah suture, and on the east by the Sierra Nevada batholith. The Calaveras Complex forms a continuous northwest-trending belt between the Placerville area and the Merced River area. South of the Merced River the belt extends in numerous roof pendants at least as far south as the Tule River. A sequence of four lithologic units is recognized, each of which is thousands of meters thick. Precise original stratigraphic thicknesses cannot be measured because of intense soft-sediment and post-consolidation deformation. The lowest unit consists of mafic pillow lava, breccia, tuff, and argilllte, and may represent layer 2 of oceanic crust. This basal unit is overlain by a predominantly chaotic unit of argillite with variable amounts of chert and siltstone often occurring as clasts in a diamictite. Olistoliths of shallow water limestone are locally an important component of this argillite unit. The overlying chert unit contains abundant large olistoliths of rhythmically bedded chert and locally important limestone olistoliths in a matrix of streaky argillite and diamictite. The highest unit included within the Calaveras Complex contains abundant, well-bedded quartzite with abundant interbedded olistostromes containing quartzite clasts and limes tone olistoliths. Fossils from limestone olistoliths reported here indicate a maximum Permo-Carboniferous age for the upper part of the argillite unit, and a maximum late Permian age for the over lying chert unit. Published fossil data indicate the upper parts of the quartzite unit are late Triassic to early Jurassic. The argillite and chert units apparently comprise numerous olistostromes that accumulated on oceanic crust in a marginal basin that was broad enough to have been relatively free of elastic detritus derived from the basin margins. Olistostromes apparently were shed from tectonically elevated areas within the marginal basin that were denuded of their pelagic and hemi pelagic cover. The quartzite unit may represent an early Mesozoic northwestward progradation of mature continent-derived sand across the western end of the late Paleozoic marginal basin. The marginal basin is considered to have been situated between the Cordilleran miogeocline to the southeast and a volcanic arc terrane to the northwest. The late Paleozoic Havallah sequence of north-central Nevada is believed to have accumulated in the same marginal basin. The Melones fault zone and Kings-Kaweah suture represent a zone of early Mesozoic tectonic truncation a long which the Calaveras Complex is juxtaposed against upper Paleozoic ophiolitic rocks and Jurassic volcanic and epiclastic rocks. Thus, we infer that the Calaveras Complex represents the westernmost exposure of the late Paleozoic marginal basin