I-Xe analysis of a magnetic separate from Lodranite GRA95209

I-Xe dating of a magnetic mineral separate from lodranite GRA95209 suggests that peak temperatures (and therefore melt migration) occurred early, at least a few million years before closure of the I-Xe system in phosphates from Acapulco

Quantum Kinetic Theory III: Simulation of the Quantum Boltzmann Master Equation

We present results of simulations of a em quantum Boltzmann master equation (QBME) describing the kinetics of a dilute Bose gas confined in a trapping potential in the regime of Bose condensation. The QBME is the simplest version of a quantum kinetic master equations derived in previous work. We consider two cases of trapping potentials: a 3D square well potential with periodic boundary conditions, and an isotropic harmonic oscillator. We discuss the stationary solutions and relaxation to equilibrium. In particular, we calculate particle distribution functions, fluctuations in the occupation numbers, the time between collisions, and the mean occupation numbers of the one-particle states in the regime of onset of Bose condensation.Comment: 12 pages, 15 figure

Parasites, Porotic Hyperostosis, and the Implications of Changing Perspectives

Cribra orbitalia and porotic hyperostosis traditionally have been viewed (at least by archaeologists) as indicators of chronic iron deficiency anemia resulting from a dependency upon maize. Recent interpretations, however, have sought to explain these conditions as an evolutionary, adaptive response to intestinal parasites rather than as a consequence of poor nutrition. Thus diet is eliminated as a contributing factor. This model, however, adopts too simplistic a view of evolution. Furthermore, it concomitantly severs the well-documented link that exists between cranial lesions and cereal-based subsistence. A more realistic approach would be to incorporate both diet and pathogens (bacterial as well as parasitic) into a symbiotic model that acknowledges the important role of parasites in the etiology of cribra orbitalia and porotic hyperostosis, while maintaining the diagnostic value of these conditions as hallmarks of early agriculture

The Role of Adaptation in Archaeological Explanation

Adaptation, a venerable icon in archaeology, often is afforded the vacuous role of being an ex-post-facto argument used to »explain» the appearance and persistence of traits among prehistoric groups- A position that has seriously impeded development of a selectionist perspective in archaeology. Biological and philosophical definitions of adaptation- A nd by extension, definitions of adaptedness-vary considerably, but all are far removed from those usually employed in archaeology. The prevailing view in biology is that adaptations are features that were shaped by natural selection and that increase the adaptedness of an organism. Thus adaptations are separated from other features that may contribute to adaptedness but are products of other evolutionary processes. Analysis of adaptation comprises two stages: Showing that a feature was under selection and how the feature functioned relative to the potential adaptedness of its bearers. The archaeological record contains a wealth of information pertinent to examining the adaptedness of prehistoric groups, but attempts to use it will prove successful only if a clear understanding exists of what adaptation is and is not

Development of a Papua New Guinean onshore carbonate reservoir: A comparative borehole image (FMI) and petrographic evaluation

The depositional and diagenetic controls on carbonate platform evolution are notoriously heterogeneous and difficult to determine from standard subsurface wireline logging techniques. Here, a combined borehole image (FMI e Fullbore Formation MicroImager) and petrographic study allowed evaluation of depositional and diagenetic trends across an Australasian subsurface buildup that is a major recent gas discovery. The Elk and Antelope gas fields are hosted in Tertiary reefal, platformal and associated deep water carbonates in the present day foothills region of the Fold and Thrust Belt in the Gulf Province of Papua New Guinea. A full suite of FMI logs (>2800 m), and 292 thin sections (mainly from sidewall cores and cuttings) from both platform flank and shallow water deposits were evaluated during this study. Despite the obvious scale differences between the datasets there was some correlation between the independent petrography and FMI studies for: a) picking major facies boundaries, and b) interpretation of depositional environments, the latter particularly for slope and deep water deposits. However, thin section petrography proved critical in understanding primary depositional textures and secondary alteration features through the shallow-water carbonates where complex diagenetic overprinting had strongly impacted original fabric, and/or in regions affected by “gas smearing”. The petrographic study allowed more detailed examination of diagenesis and its impact on rock fabric (which links to the FMI textures). Component analysis and depositional textures identified in thin section are good indicators of original depositional environment.Full FMI coverage allowed textural definition on a dm/m scale, identification and characterisation of vertical changes, and likely large-scale variations in depositional environments and sequences. It was clear from combining the results of the two studies that diagenesis as well as depositional fabric had a strong impact on resultant FMI facies. The diagenetic overprinting would have been difficult to extract from the FMI data without the benefit of the petrographic work. This study shows the merits of selective petrographic analysis to calibrate the quality of facies interpretation from FMI images, and proved critical for enhancing and in places revising initial FMI interpretations

A non-local, Lorentz-invariant, hidden-variable interpretation of relativistic quantum mechanics based on particle trajectories

We demonstrate how to construct a lorentz-invariant, hidden-variable interpretation of relativistic quantum mechanics based on particle trajectories. The covariant theory that we propose employs a multi-time formalism and a lorentz-invariant rule for the coordination of the space-time points on the individual particle trajectories. In this way we show that there is no contradiction between nonlocality and lorentz invariance in quantum mechanics. The approach is illustrated for relativistic bosons, using a simple model to discuss the individual non-locally correlated particle motion which ensues when the wavefunction is entangled. A simple example of measurement is described.Comment: 12 pages, 2 figure

A Heterosynaptic Learning Rule for Neural Networks

In this article we intoduce a novel stochastic Hebb-like learning rule for neural networks that is neurobiologically motivated. This learning rule combines features of unsupervised (Hebbian) and supervised (reinforcement) learning and is stochastic with respect to the selection of the time points when a synapse is modified. Moreover, the learning rule does not only affect the synapse between pre- and postsynaptic neuron, which is called homosynaptic plasticity, but effects also further remote synapses of the pre- and postsynaptic neuron. This more complex form of synaptic plasticity has recently come under investigations in neurobiology and is called heterosynaptic plasticity. We demonstrate that this learning rule is useful in training neural networks by learning parity functions including the exclusive-or (XOR) mapping in a multilayer feed-forward network. We find, that our stochastic learning rule works well, even in the presence of noise. Importantly, the mean learning time increases with the number of patterns to be learned polynomially, indicating efficient learning.Comment: 19 page

ELKO Spinor Fields: Lagrangians for Gravity derived from Supergravity

Dual-helicity eigenspinors of the charge conjugation operator (ELKO spinor fields) belong -- together with Majorana spinor fields -- to a wider class of spinor fields, the so-called flagpole spinor fields, corresponding to the class-(5), according to Lounesto spinor field classification based on the relations and values taken by their associated bilinear covariants. There exists only six such disjoint classes: the first three corresponding to Dirac spinor fields, and the other three respectively corresponding to flagpole, flag-dipole and Weyl spinor fields. Using the mapping from ELKO spinor fields to the three classes Dirac spinor fields, it is shown that the Einstein-Hilbert, the Einstein-Palatini, and the Holst actions can be derived from the Quadratic Spinor Lagrangian (QSL), as the prime Lagrangian for supergravity. The Holst action is related to the Ashtekar's quantum gravity formulation. To each one of these classes, there corresponds a unique kind of action for a covariant gravity theory. Furthermore we consider the necessary and sufficient conditions to map Dirac spinor fields (DSFs) to ELKO, in order to naturally extend the Standard Model to spinor fields possessing mass dimension one. As ELKO is a prime candidate to describe dark matter and can be obtained from the DSFs, via a mapping explicitly constructed that does not preserve spinor field classes, we prove that in particular the Einstein-Hilbert, Einstein-Palatini, and Holst actions can be derived from the QSL, as a fundamental Lagrangian for supergravity, via ELKO spinor fields. The geometric meaning of the mass dimension-transmuting operator - leading ELKO Lagrangian into the Dirac Lagrangian - is also pointed out, together with its relationship to the instanton Hopf fibration.Comment: 11 pages, RevTeX, accepted for publication in Int.J.Geom.Meth.Mod.Phys. (2009

Electron mobility in surface- and buried- channel flatband In_0.53Ga_0.47As MOSFETs with ALD Al₂O₃ gate dielectric.

In this paper, we investigate the scaling potential of flatband III-V MOSFETs by comparing the mobility of surface and buried In<sub>0.53</sub>Ga<sub>0.47</sub>As channel devices employing an Atomic Layer Deposited (ALD) Al<sub>2</sub>O<sub>3</sub> gate dielectric and a delta-doped InGaAs/InAlAs/InP heterostructure. Peak electron mobilities of 4300 cm<sup>2</sup>/V·s and 6600 cm<sup>2</sup>/V·s at a carrier density of 3×1012 cm<sup>-2</sup> for the surface and buried channel structures respectively were determined. In contrast to similarly scaled inversion-channel devices, we find that mobility in surface channel flatband structures does not drop rapidly with electron density, but rather high mobility is maintained up to carrier concentrations around 4x10<sup>12</sup> cm<sup>-2</sup> before slowly dropping to around 2000 cm<sup>2</sup>/V·s at 1x10M<sup>13</sup> cm<sup>-2</sup>. We believe these to be world leading metrics for this material system and an important development in informing the III-V MOSFET device architecture selection process for future low power, highly scaled CM