Reconsidering the black hole final state in Dirac fields

We extend Horowitz and Maldacena's proposal about black hole final state to Dirac fields and find that if annihilation of the infalling positrons and the collapsed electrons inside the horizon is considered, then the nonlinear evolution of collapsing quantum state will be avoided. We further propose that annihilation also plays the central role in the process of black hole information escaping in both Dirac and scalar fields. The computation speed of a black hole is also briefly discussed.Comment: 7pages; Phys. Lett. B 2005 (in press

Shape Modeling with Spline Partitions

Shape modelling (with methods that output shapes) is a new and important task in Bayesian nonparametrics and bioinformatics. In this work, we focus on Bayesian nonparametric methods for capturing shapes by partitioning a space using curves. In related work, the classical Mondrian process is used to partition spaces recursively with axis-aligned cuts, and is widely applied in multi-dimensional and relational data. The Mondrian process outputs hyper-rectangles. Recently, the random tessellation process was introduced as a generalization of the Mondrian process, partitioning a domain with non-axis aligned cuts in an arbitrary dimensional space, and outputting polytopes. Motivated by these processes, in this work, we propose a novel parallelized Bayesian nonparametric approach to partition a domain with curves, enabling complex data-shapes to be acquired. We apply our method to HIV-1-infected human macrophage image dataset, and also simulated datasets sets to illustrate our approach. We compare to support vector machines, random forests and state-of-the-art computer vision methods such as simple linear iterative clustering super pixel image segmentation. We develop an R package that is available at \url{https://github.com/ShufeiGe/Shape-Modeling-with-Spline-Partitions}

The role of strain hardening in the transition from dislocation-mediated to frictional deformation of marbles within the Karakoram Fault Zone, NW India

The onset of frictional failure and potentially seismogenic deformation in carbonate rocks undergoing exhumation within fault zones depends on hardening processes that reduce the efficiency of aseismic dislocation-mediated deformation as temperature decreases. However, few techniques are available for quantitative analysis of dislocation slip system activity and hardening in natural tectonites. Electron backscatter diffraction maps of crystal orientations offer one such approach via determination of Schmid factors, if the palaeostress conditions can be inferred and the critical resolved shear stresses of slip systems are constrained. We analyse calcite marbles deformed in simple shear within the Karakoram Fault Zone, NW India, to quantify changes in slip system activity as the rocks cooled during exhumation. Microstructural evidence demonstrates that between ∼300 °C and 200–250 °C the dominant deformation mechanisms transitioned from dislocation-mediated flow to twinning and frictional failure. However, Schmid factor analysis, considering critical resolved shear stresses for yield of undeformed single crystals, indicates that the fraction of grains with sufficient resolved shear stress for glide apparently increased with decreasing temperature. Misorientation analysis and previous experimental data indicate that strain-dependent work hardening is responsible for this apparent inconsistency and promoted the transition from dislocation-mediated flow to frictional, and potentially seismogenic, deformation.David Wallis and Lars Hansen acknowledge support from the Natural Environment Research Council grant NE/M000966/1

Syntectonic quartz vein evolution during progressive deformation

Two models to explain the progressive deformation of syntectonic quartz veins are derived from conventional theories for simple and pure shears. The simple-shear model is based on reorientation and changes in length of linear vein elements, and predicts initial orientations of veins for imposed shear strains, elongations and strain ratios. The pure-shear model considers changes in length of lines variably orientated relative to the maximum compression direction, and yields estimates of elongation strains and strain ratios. Expectations of both models are different, as illustrated by analysis of quartz veins from the Rhoscolyn Anticline, Anglesey, NW Wales. The simple-shear model recognizes three distinct initial orientations, which predict different strains across the fold; the pure-shear model suggests veins were initially sub-parallel to the principal compression direction and predicts effectively constant strains across the fold. In addition, both models predict different patterns of fold vergence: for simple shear, vergence depends on magnitude and direction of shearing and may exhibit complex patterns; for pure shear, vergence patterns are predicted to be essentially constant. In general, the predictions of either model are critically dependent on the origin of the veins, particularly relative to the formation of the Rhoscolyn Anticline

Evolution of a shear zone before, during and after melting

Partial melt in the deforming mid- or lower continental crust causes a strength decrease and drives formation of lithological heterogeneities. However, mechanisms of formation of syn-melt deformation zones and strain partitioning in partially molten rock remain poorly understood. We use field and microstructural observations to unravel the evolution of a partial melt shear zone, Seiland Igneous Province, northern Norway. The Øksfjord shear zone (ØSZ) is one of several paragneiss shear zones present within gabbros of the Seiland Igneous Province, formed by syn-intrusive deep crustal shearing during lithospheric extension related to continental rifting. Microstructures from the ØSZ show evidence for different deformation conditions. The first phase was active pre-melt and involved deformation at high subsolidus temperatures. This was followed by syn-melt deformation of the shear zone causing a relative strength increase towards the shear zone centre upon crystallization. The third phase nucleated two parallel shear zones at the edges of the ØSZ; melt textures are absent and microstructures indicate deformation at lower temperatures and higher stresses. In effect, melt migration towards the shear zone centre ultimately led to strengthening of the shear zone core, with post-crystallization deformation focusing along shear zone margins where significant heterogeneities are present

Scaling Transformations and the Origins of Light Relics Constraints from Cosmic Microwave Background Observations

We use here a family of scaling transformations, that scale key rates in the evolution equations, to analytically understand constraints on light relics from cosmic microwave background (CMB) maps, given cosmological models of varying degrees of complexity. We describe the causes of physical effects that are fundamentally important to the constraining power of the data, with a focus on the two that are most novel. We use as a reference model a cosmological model that admits a scaling transformation that increases light relic energy density while avoiding all of these causes. Constraints on light relics in a given model can then be understood as due to the differences between the given model and the reference model, as long as the additional light relics only interact gravitationally with the Standard Model components. This understanding supports the development of cosmological models that can evade light relics constraints from CMB maps.Comment: 17 pages + references, 12 figures. Published in PR

Development of crystal lattice preferred orientation and seismic properties in Bhavani shear zone, Southern India.

Shear markers and shear sense indicators from the Bhavani shear zone (BSZ), a member of the south Indian Proterozoic shear system, separating the northern Archaean and southern Pan African granulite terranes, suggest multiphase reactivation. There is a progressive increase in mylonitisation corresponding to a progression in strain. The LS fabrics indicate near vertical principal flattening plane trending ENE-WSW, but with subvertical as well as subhorizontal stretching lineations implying a possible reactivation history with opposing movement vectors. Whilst the SEM-EBSD derived LPO of amphibole, biotite and feldspars suggest plastic deformation through the activation of intracrystalline slip systems, diffusional creep accommodated deformation can be inferred from the quartz LPO. All LPO suggest modifications in the fabric due to both retrograde and prograde reactivation during the tectono-thermal history of the BSZ over a period of nearly 2.0Ga. Petrofabric-derived seismic properties for the BSZ suggest that it exhibits a considerable seismic anisotropy, which reflects the petrofabrics of hornblende and biotite. Both LPO and seismic property observations imply conflicting tectonic X and Y directions, indicating possible superposition of contrasting X and Y vectors during different phases of the shear zone reactivation

Quantum teleprotation with sonic black holes

We show a new property of sonic black holes. After deriving the metric of a sonic black hole from the Schrodinger equation and quantizing the perturbation fields near the sonic event horizon, we show particles of Hawking radiation can act as a source of entanglement: two-mode squeezed entanglement is produced near the event horizon, which can be used in quantum teleportation. The fidelity of the teleportation is closely related to the temperature of the sonic black holes, but high fidelity seems difficult to reach in our case.Comment: 9 pages, no figure, to appear in Physics Letters

Random Tessellation Forests

Space partitioning methods such as random forests and the Mondrian process are powerful machine learning methods for multi-dimensional and relational data, and are based on recursively cutting a domain. The flexibility of these methods is often limited by the requirement that the cuts be axis aligned. The Ostomachion process and the self-consistent binary space partitioning-tree process were recently introduced as generalizations of the Mondrian process for space partitioning with non-axis aligned cuts in the two dimensional plane. Motivated by the need for a multi-dimensional partitioning tree with non-axis aligned cuts, we propose the Random Tessellation Process (RTP), a framework that includes the Mondrian process and the binary space partitioning-tree process as special cases. We derive a sequential Monte Carlo algorithm for inference, and provide random forest methods. Our process is self-consistent and can relax axis-aligned constraints, allowing complex inter-dimensional dependence to be captured. We present a simulation study, and analyse gene expression data of brain tissue, showing improved accuracies over other methods.Comment: 11 pages, 4 figure

A cool dark sector, concordance, and a low σ8\sigma_8

We investigate a cosmological model in which a fraction of the dark matter is atomic dark matter (ADM). This ADM consists of dark versions of the electron and of the proton, interacting with each other and with dark photons just as their light sector versions do, but interacting with everything else only gravitationally. We find constraints given current cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data, with and without an $H_0$ prior, and with and without enforcing a big bang nucleosynthesis consistent helium abundance. We find that, at low dark photon temperature, one can have consistency with BAO and CMB data, with a fraction of dark matter that is ADM ($f_{\rm adm}$) as large as $\sim 0.1$. Such a large $f_{\rm adm}$ leads to a suppression of density fluctuations today on scales below about 60 Mpc that may be of relevance to the $\sigma_8$ tension. Our work motivates calculation of nonlinear corrections to matter power spectrum predictions in the ADM model. We forecast parameter constraints to come from future ground-based CMB surveys, and find that if ADM is indeed the cause of the $\sigma_8$ tension, the influence of the ADM, primarily on CMB lensing, will likely be detectable at high significance.Comment: 16 pages + references, 9 figures. Comments welcom