Clay minerals in South Australian Holocene basaltic volcanogenic soils and implications for halloysite genesis and structure

The clay mineralogical composition was determined of 8 soils formed from pyroclastic ejecta (tephra) from adjacent 5000-year old basaltic volcanoes at Mounts Gambier and Schank in South Australia. Both nanocrystalline (short-range order) and crystalline aluminosilicates and also Fe oxides and hydroxides were identified in the soils. Allophane generally occurred to a greater extent in the 4 soils derived from glass-rich Mt Schank tephra than in most of those from glass-poor Mt Gambier tephra. Ferrihydrite occurred along with allophane. Smectite, kaolinite, illite, and an interstratified kaolinite-smectite comprised the crystalline minerals in these soils. There was no evidence for halloysite. Unlike in New Zealand, decreased leaching resulted in Si-rich allophane, rather than halloysite, forming in place of the Al-rich form of the same mineral. This result may indicate that ferrous iron is an essential impurity in halloysite. It was likely absent from these soils because their high pH due to underlying calcareous rocks precludes its occurrence. The probable requirement of Fe(II) as an essential component of halloysites may have been overlooked because of oxidation consequent upon the inevitable drying of samples prior to analyses

Typical Event Horizons in AdS/CFT

We consider the construction of local bulk operators in a black hole background dual to a pure state in conformal field theory. The properties of these operators in a microcanonical ensemble are studied. It has been argued in the literature that typical states in such an ensemble contain firewalls, or otherwise singular horizons. We argue this conclusion can be avoided with a proper definition of the interior operators.Comment: 8 pages, 2 figures. arXiv admin note: text overlap with arXiv:1310.799

Age of the Rotoehu Ash. Comment.

Suggests that the article by Whitehead & Ditchburn (1994), although presenting useful new data on 230Th/232Th analyses, is flawed and misleading in suggesting that the Rotoiti Tephra is considerably younger than c. 50 ka

Low-Shot Learning with Imprinted Weights

Human vision is able to immediately recognize novel visual categories after seeing just one or a few training examples. We describe how to add a similar capability to ConvNet classifiers by directly setting the final layer weights from novel training examples during low-shot learning. We call this process weight imprinting as it directly sets weights for a new category based on an appropriately scaled copy of the embedding layer activations for that training example. The imprinting process provides a valuable complement to training with stochastic gradient descent, as it provides immediate good classification performance and an initialization for any further fine-tuning in the future. We show how this imprinting process is related to proxy-based embeddings. However, it differs in that only a single imprinted weight vector is learned for each novel category, rather than relying on a nearest-neighbor distance to training instances as typically used with embedding methods. Our experiments show that using averaging of imprinted weights provides better generalization than using nearest-neighbor instance embeddings.Comment: CVPR 201

Holocene volcanic soils in the Mt. Gambier region, South Australia

Volcanic soils derived from mid-Holocene basaltic tephra in the Mt. Gambier region of South Australia have developed in a xeric moisture regime. We studied two soils, one at Mt Gambier (MTG) and the other at nearby Mt Schank (MTS). Both volcanoes were active ca. 6000 cal. years ago. The MTG soil has a high content of CaCO₃ (incorporated during eruption through limestone) and other exotic materials intermixed with basaltic tephra containing low amounts of glass. The MTS soil is derived mainly from basaltic tephra with high glass content and much less CaCO₃ than at MTG. These parent mineralogies have led to markedly different clay compositions and chemical properties: the MTS soil contains abundant allophane (mainly) and ferrihydrite with few layer silicate clays, whereas the MTG soil is dominated by layer silicate clays and low allophane or ferrihydrite. Both soils are near neutral or alkaline. The MTS soil has a melanic horizon and andic properties and is classed as a Melanoxerand. The MTG soil has weak andic properties with insufficient glass to enable it to be classed in the Andisols, and is instead a Calcixeroll

Parent materials of Yellow-brown loams in the Waikato-Coromandel district.

The yellow-brown loams of the Waikato-Coromandel region are derived from weathered airfall volcanic materials. These materials may be either direct airfall deposits, or erosion products of these deposits, described as reworked ash in some publications. In the erosion products small amounts of other rocks may be included in the parent materials, and these additions may modify to a slight degree the chemical and physical properties of the soil as a yellow-brown loam. In larger amounts these additions result in the formation of intergrades to yellow-brown earths or gley soils

Unsupervised Learning of Depth and Ego-Motion from Video

We present an unsupervised learning framework for the task of monocular depth and camera motion estimation from unstructured video sequences. We achieve this by simultaneously training depth and camera pose estimation networks using the task of view synthesis as the supervisory signal. The networks are thus coupled via the view synthesis objective during training, but can be applied independently at test time. Empirical evaluation on the KITTI dataset demonstrates the effectiveness of our approach: 1) monocular depth performing comparably with supervised methods that use either ground-truth pose or depth for training, and 2) pose estimation performing favorably with established SLAM systems under comparable input settings.Comment: Accepted to CVPR 2017. Project webpage: https://people.eecs.berkeley.edu/~tinghuiz/projects/SfMLearner

Discovery of halloysite books in a ~270,000 year-old buried tephra deposit in northern New Zealand

As part of a wider study examining the geomechanical properties, especially sensitivity, of sequences of Quaternary pyroclastic and associated deposits and buried soils in the landslide-prone western Bay of Plenty area near Tauranga, eastern North Island, we examined the mineralogy of a pale pinkish-grey tephra deposit directly beneath non-welded, siliceous Te Ranga Ignimbrite (~2 m thick) in a ~25 m high cutting at Tauriko.http://www.smectech.com.au/ACMS/ACMS_Conferences/ACMS21/ACMS%202010%20Abstracts/ACMS%202010%20S1A6_Wyatt%20et%20al%20(Lowe).pd