4,716 research outputs found
Failure analysis of a steel motorcycle kickstand
Copyright @ 2009 Springer US.A fractured steel motorcycle kickstand was metallurgically investigated using a range of failure analysis tools [visual examination, energy dispersive X-ray (EDX) analysis, electron microprobe analysis (EPMA), scanning electron microscopy (SEM), fractography, optical microscopy, hardness testing and non-destructive testing (NDT)]. The steel kickstandâs composition, its microstructure, electron fractographs, and mechanical test results have been critically interpreted. Some evidence of wear damage, in the failed kickstand, was observed. The microstructural and fractographic analyses showed pre-existing micro-cracks which were believed to have grown to result in ductile failure followed by acceleration of corrosion. Recommendations have been made to avoid the failure of the motorcycle kickstand
Efficient synthesis of plate-like crystalline hydrated tungsten trioxide thin films with highly improved electrochromic performance
Cataloged from PDF version of article.Plate-like hydrated tungsten trioxide (3WO(3)center dot H(2)O) films were grown on a fluorine doped tin oxide (FTO) coated transparent conductive substrate via an efficient, facile and template-free hydrothermal method. The film exhibited a fast coloration/bleaching response (t(c90%) = 4.3 s and t(b90%) = 1.4 s) and a high coloration efficiency (112.7 cm(2) C(-1)), which were probably due to a large surface area
All-optical mapping of barrel cortex circuits based on simultaneous voltage-sensitive dye imaging and channelrhodopsin-mediated photostimulation
© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Neurophotonics 2 (2015): 021013, doi:10.1117/1.NPh.2.2.021013.We describe an experimental approach that uses light to both control and detect neuronal activity in mouse barrel cortex slices: blue light patterned by a digital micromirror array system allowed us to photostimulate specific layers and columns, while a red-shifted voltage-sensitive dye was used to map out large-scale circuit activity. We demonstrate that such all-optical mapping can interrogate various circuits in somatosensory cortex by sequentially activating different layers and columns. Further, mapping in slices from whisker-deprived mice demonstrated that chronic sensory deprivation did not significantly alter feedforward inhibition driven by layer 5 pyramidal neurons. Further development of voltage-sensitive optical probes should allow this all-optical mapping approach to become an important and high-throughput tool for mapping circuit interactions in the brain.This work was supported by the World Class Institute (WCI) program of the National Research Foundation of Korea (NRF) funded by Ministry of Education, Science and Technology of Korea (MEST) (NRF) Grant No. WCI 2009-003 and by the Competitive Research Programme (CRP) of NRF (Singapore) Grant No. NRF 2008 NRF-CRP 002-082
Effects of Nonlinear Dispersion Relations on Non-Gaussianities
We investigate the effect of non-linear dispersion relations on the
bispectrum. In particular, we study the case were the modified relations do not
violate the WKB condition at early times, focusing on a particular example
which is exactly solvable: the Jacobson-Corley dispersion relation with quartic
correction with positive coefficient to the squared linear relation. We find
that the corrections to the standard result for the bispectrum are suppressed
by a factor where is the scale where the modification
to the dispersion relation becomes relevant. The modification is {\it mildly}
configuration-dependent and equilateral configurations are more suppressed with
respect to the local ones, by a factor of one percent. There is no
configuration leading to enhancements. We then analyze the results in the
framework of particle creation using the approximate gluing method of
Brandenberger and Martin, which relates more directly to the modeling of the
trans-Planckian physics via modifications of the vacuum at a certain cutoff
scale. We show that the gluing method overestimates the leading order
correction to the spectrum and bispectrum by one and two orders, respectively,
in . We discuss the various approximation and conclude that for
dispersion relations not violating WKB at early times the particle creation is
small and does not lead to enhanced contributions to the bispectrum. We also
show that in many cases enhancements do not occur when modeling the
trans-Planckian physics via modifications of the vacuum at a certain cutoff
scale. Most notably they are only of order O(1) when the Bogolyubov
coefficients accounting for particle creation are determined by the Wronskian
condition and the minimization of the uncertainty between the field and its
conjugate momentum.Comment: v1: 11 pages, 2 figures; v2: references update
Efficient synthesis of plate-like crystalline hydrated tungsten trioxide thin films with highly improved electrochromic performance
Plate-like hydrated tungsten trioxide (3WO3·H 2O) films were grown on a fluorine doped tin oxide (FTO) coated transparent conductive substrate via an efficient, facile and template-free hydrothermal method. The film exhibited a fast coloration/bleaching response (tc90% = 4.3 s and tb90% = 1.4 s) and a high coloration efficiency (112.7 cm2 C-1), which were probably due to a large surface area
Excited-state optically detected magnetic resonance of spin defects in hexagonal boron nitride
Negatively charged boron vacancy (VB-) centers in hexagonal boron nitride
(hBN) are promising spin defects in a van der Waals crystal. Understanding the
spin properties of the excited state (ES) is critical for realizing dynamic
nuclear polarization. Here, we report zero-field splitting in the ES of DES =
2160 MHz and an optically detected magnetic resonance (ODMR) contrast of 12% at
cryogenic temperature. The ES has a g-factor similar to the ground state. The
ES photodynamics is further elucidated by measuring the level anti-crossing of
the VB- defects under varying external magnetic fields. In contrast to nitrogen
vacancy (NV-) centers in diamond, the emission change caused by excited-state
level anti-crossing (ESLAC) is more prominent at cryo-temperature than at room
temperature. Our results provide important information for utilizing the spin
defects of hBN in quantum technology
Thermoplastic Green Machining for Textured Dielectric Substrate for Broadband Miniature Antenna
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65902/1/j.1551-2916.2005.00089.x.pd
Cosmological perturbations in a healthy extension of Horava gravity
In Horava's theory of gravity, Lorentz symmetry is broken in exchange for
renormalizability, but the original theory has been argued to be plagued with
problems associated with a new scalar mode stemming from the very breaking of
Lorentz symmetry. Recently, Blas, Pujolas, and Sibiryakov have proposed a
healthy extension of Horava gravity, in which the behavior of the scalar mode
is improved. In this paper, we study scalar modes of cosmological perturbations
in extended Horava gravity. The evolution of metric and density perturbations
is addressed analytically and numerically. It is shown that for vanishing
non-adiabatic pressure of matter the large scale evolution of cosmological
perturbations converges to that described by a single constant, , which
is an analog of a curvature perturbation on the uniform-density slicing
commonly used in usual gravitational theories. The subsequent evolution is thus
determined completely by the value of .Comment: 10 pages, 4 figures; v2: published versio
The impact of environmental, social, and governance disclosure on firm value: The role of CEO power
Using a large cross-sectional dataset comprising of FTSE 350 listed firms, this study investigates whether superior environmental, social and corporate governance (ESG) disclosure affects firm value. We find a positive association between ESG disclosure level and firm value, suggesting that improved transparency and accountability and enhanced stakeholder trust play a role in boosting firm value. We also report that higher CEO power enhances the ESG disclosure effect on firm value, indicating that stakeholders associate ESG disclosure from firms with higher CEO power with greater commitment to ESG practice. This evidence is strong and consistent for three different measures of ESG-related disclosure: the ESG, environmental and social disclosure scores. The results are robust to the use of an instrumental variable approach, and the Heckman two-stage estimation procedure
Saving tropical forests by knowing what we consume
Oil palm agriculture threatens tropical forests and biodiversity. Previous studies focused on finding ways to reduce the impacts of oil palm on biodiversity and the environment. However, the actual uptake of sustainable practices depends in part on economic demand. We undertook the first investigation on consumer attitudes and willingnessâtoâpay (WTP) for deforestationâfree sustainable palm oil. In a sample of 251 consumers in Singapore, we found little consumer bias against palm oil per se. However, consumers had strong negative opinions toward products that cause deforestation. On average, consumers stated a WTP of 8.2â9.9% more for common palm oilâcontaining products that are deforestationâfree. Given the current premium for segregated certified sustainable palm oil (CSPO; 1.5â5%), there is an incentive for manufacturers to use CSPO. Educational campaigns by environmental organizations and prominent advertising of CSPO usage through sustainability labels can potentially improve the economic demand for sustainable practices in oil palm agriculture.Xingli Giam, Letchumi Mani, Lian Pin Koh and Hugh T.W. Ta
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