19,622 research outputs found

    Continuous turning slip ring assembly Patent

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    Development of slip ring assembly with inner and outer peripheral surfaces used as electrical contacts for brushe

    Typical Event Horizons in AdS/CFT

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    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

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

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    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

    Age of the Rotoehu Ash. Comment.

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    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

    The development of the professional values and practice standard in the secondary graduate initial teacher training route in England

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    The paper reports on a pilot research project to investigate how trainee teachers develop an understanding of the competences that must be reached in the area of professional practice and values , which is one of the standards that needs to be met before the award of Qualified Teacher Status in England. Data were collected from secondary trainee teachers, their placement mentors in schools and university tutors. Data have been interpreted in the context of potential threats to the professionalism of teachers, through the introduction of managerialist influences in public funded education. The main findings are: that trainees think that the most dominant influence on developing understanding of professional values are their school placements ; there were little differences in the responses from four subject areas studied ; mentors and other lead teachers play an important role in the development of understanding of professional values; the grades awarded by mentors when assessing professional practice and values varies between the four subjects studied. The explanation for these findings is complex and is related to the understanding and interpretation of the standard by both mentors and trainee teachers. The findings highlight some of the difficulties in attempting to assess competency standards in an area that is underpinned by values and suggest that initial teacher training can best assist the development of the standard when it is approached in a critical way by all parties.</p

    Low-Shot Learning with Imprinted Weights

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    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

    Sedimentological and stratigraphic evolution of the southern part of the Barberton greenstone belt: A case of changing provenance and stability

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    The sedimentological and stratigraphic evolution of the 3.5 to 3.3 Ga Barberton Greenstone Belt can be divided into three principal stages: (1) the volcanic platform stage during which at least 8 km of mafic and ultramafic volcanic rocks, minor felsic volcanic units, and thin sedimentary layers (Onverwacht Group) accumulated under generally anorogenic conditions; (2) a transitional stage of developing instability during which widespread dacitic volcanism and associated pyroclastic and volcaniclastic sedimentation was punctuated by the deposition of terrigenous debris derived by uplift and shallow erosion of the belt itself (Fig Tree Group); (3) an orogenic stage involving cessation of active volcanism, extensive thrust faulting, and widespread deposition of clastic sediments representing deep erosion of the greenstone belt sequence as well as sources outside of the belt (Moodies Group)

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

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    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

    Chondrule-like particles provide evidence of early Archean meteorite impacts, South Africa and western Australia

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    The evolution of the Earth and the Earth crust was studied. Two layers, that contain abundant unusual spherical particles which closely resemble chondroules were identified. Chondrules occur on small quantities in lunar soil, however, they are rare in terrestrial settings. Some chondrules in meteorites were formed on the surfaces of planet sized bodies during impact events. Similar chondrule like objects are extremely rare in the younger geologic record and these abundances are unknown in ancient deposits, except in meteorites. It is suggested that a part of the Earth's terminal bombardment history, and conditions favoring chondrule formation existed on the early Earth
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