Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

This study of Sr-Nd initial isotopic ratios of plutons from the North Patago nian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of mag mas are represented by the Sr-Nd initial isotopic ratios (87Sr/86Sr and 143Nd/144Nd) of the plutonic rocks. Our results support the interpretation that source compo sition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel mélange. Subsequent melting of subducted mélanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast conver gence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk mélanges and the peridotite. Our proposal follows model predictions on the formation of mélange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general

Creative dance can enhance proprioception in older adults

Aim. It has been shown by many authors that proprioception declines with age. However, few studies have examined the effects of exercise interventions on proprioception. The purpose of this study was to investigate the effects of a creative dance program on proprioception of older adults. Methods. Thirty-seven men and women between 55 and 80 years of age, who were not engaged in any exercise program for at least one year, were randomly assigned to an experimental (63.6±5.7 years) or a control group (65.3±7.6 years). The experimental group participated in a creative dance program for 12 weeks with a periodicity of 3 sessions of 90 minutes per week. Measures of knee kinesthesia, knee joint position sense and arm positioning were taken before and after the program. Results. After 12 weeks, knee joint position sense (P=0.005) knee kinesthesia (in flexion) (P=0.04), and arm positioning (P=0.008) significantly improved within the creative dance training group. At 12 weeks follow-up, arm positioning performance was significantly better for the creative dance group when compared with the control group (P=0.043). The control group did not show any significant improvement in proprioception. Conclusion. This study showed that a creative dance program emphasising body awareness can improve proprioception in older adults

Gravitational Collapse: Expanding and Collapsing Regions

We investigate the expanding and collapsing regions by taking two well-known spherically symmetric spacetimes. For this purpose, the general formalism is developed by using Israel junction conditions for arbitrary spacetimes. This has been used to obtain the surface energy density and the tangential pressure. The minimal pressure provides the gateway to explore the expanding and collapsing regions. We take Minkowski and Kantowski-Sachs spacetimes and use the general formulation to investigate the expanding and collapsing regions of the shell.Comment: 12 pages, 4 figures, accepted for publication in Gen. Relativ. Gra

Temperature-responsive nanomagnetic logic gates for cellular hyperthermia

While a continuous monitoring of temperature at the micro- and nano-scales is clearly of interest in many contexts, in many others a yes or no answer to the question "did the system locally exceed a certain temperature threshold?" can be more accurate and useful. This is the case of hard-to-detect events, such as those where temperature fluctuations above a defined threshold are shorter than the typical integration time of micro/nanothermometers and systems where fluctuations are rare events in a wide time frame. Herein we present the synthesis of iron selenide magnetic nanoplatelets and their use as non-volatile logic gates recording the near infrared (NIR) dose that triggers a temperature increase above a critical temperature around 42 °C in prostate cancer cell cultures. This use is based on the bistable behavior shown by the nanoplatelets below a magnetic phase transition at a tunable temperature T C and on their photothermal response under NIR light. The obtained results indicate that the synthesized nanomagnets may be employed in the future as both local heaters and temperature monitoring tools in a wide range of contexts involving systems which, as cells, are temperature-sensitive around the tunable T C

Critical Collapse of Cylindrically Symmetric Scalar Field in Four-Dimensional Einstein's Theory of Gravity

Four-dimensional cylindrically symmetric spacetimes with homothetic self-similarity are studied in the context of Einstein's Theory of Gravity, and a class of exact solutions to the Einstein-massless scalar field equations is found. Their local and global properties are investigated and found that they represent gravitational collapse of a massless scalar field. In some cases the collapse forms black holes with cylindrical symmetry, while in the other cases it does not. The linear perturbations of these solutions are also studied and given in closed form. From the spectra of the unstable eigen-modes, it is found that there exists one solution that has precisely one unstable mode, which may represent a critical solution, sitting on a boundary that separates two different basins of attraction in the phase space.Comment: Some typos are corrected. The final version to appear in Phys. Rev.

Gravitational anomaly and fundamental forces

I present an argument, based on the topology of the universe, why there are three generations of fermions. The argument implies a preferred gauge group of SU(5), but with SO(10) representations of the fermions. The breaking pattern SU(5) to SU(3)xSU(2)xU(1) is preferred over the pattern SU(5) to SU(4)xU(1). On the basis of the argument one expects an asymmetry in the early universe microwave data, which might have been detected already.Comment: Contribution to the 2nd School and Workshop on Quantum Gravity and Quantum Geometry. Corfu, september 13-20 2009. 10 page

Performance Analysis of One-to-Many Data Transformations

Relational Database Systems often support activities like data warehousing, cleaning and integration. All these activities require performing some sort of data transformations. Since data often resides on relational databases, data transformations are often specified using SQL, which is based of relational algebra. However, many useful data transformations cannot be expressed as SQL queries due to limited expressive power of relational algebra. In particular, an important class of data transformations that produces several output tuples for a single input tuple cannot be expressed in that way. In this report, we analyze alternatives to process one-to-many data transformations using Relational Database Systems, and compare them in terms of expressiveness, optimizability and performanc

Non-destructive, dynamic detectors for Bose-Einstein condensates

We propose and analyze a series of non-destructive, dynamic detectors for Bose-Einstein condensates based on photo-detectors operating at the shot noise limit. These detectors are compatible with real time feedback to the condensate. The signal to noise ratio of different detection schemes are compared subject to the constraint of minimal heating due to photon absorption and spontaneous emission. This constraint leads to different optimal operating points for interference-based schemes. We find the somewhat counter-intuitive result that without the presence of a cavity, interferometry causes as much destruction as absorption for optically thin clouds. For optically thick clouds, cavity-free interferometry is superior to absorption, but it still cannot be made arbitrarily non-destructive . We propose a cavity-based measurement of atomic density which can in principle be made arbitrarily non-destructive for a given signal to noise ratio