5,690 research outputs found

    White-collar crime and stock return: Empirical study from announcement effect

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    White-collar crime continues to hit the headlines across Malaysia and it remains a serious issue influencing organizations globally. A share price event study is thus conducted on a group of public listed companies in Malaysia to examine the announcement effect of white-collar crime. The period of the study is from 1996 to 2010, covering both the Asian Financial Crisis in 1997/98 and the sub-prime mortgage crisis in 2008/09. Results indicate the existence of significant negative abnormal share price reaction on 10 trading days subsequent to the day of announcement. It means that the stock market in Malaysia is not efficient. However, it implies that the market possesses the power to discipline unethical companies as the shareholders drive down their value by disposing their stocks following the announcement.Share Price, Event Study; White-Collar Crime

    Causal connectability between quantum systems and the black hole interior in holographic duality

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    In holographic duality an eternal AdS black hole is described by two copies of the boundary CFT in the thermal field double state. This identification has many puzzles, including the boundary descriptions of the event horizons, the interiors of the black hole, and the singularities. Compounding these mysteries is the fact that, while there is no interaction between the CFTs, observers from them can fall into the black hole and interact. We address these issues in this paper. In particular, we (i) present a boundary formulation of a class of in-falling bulk observers; (ii) present an argument that a sharp bulk event horizon can only emerge in the infinite NN limit of the boundary theory; (iii) give an explicit construction in the boundary theory of an evolution operator for a bulk in-falling observer, making manifest the boundary emergence of the black hole horizons, the interiors, and the associated causal structure. A by-product is a concept called causal connectability, which is a criterion for any two quantum systems (which do not need to have a known gravity dual) to have an emergent sharp horizon structure.Comment: 29 pages, 11 figures. Clarifications in Sec. II and Sec. VI. References adde

    Subalgebra-subregion duality: emergence of space and time in holography

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    In holographic duality, a higher dimensional quantum gravity system emerges from a lower dimensional conformal field theory (CFT) with a large number of degrees of freedom. We propose a formulation of duality for a general causally complete bulk spacetime region, called subalgebra-subregion duality, which provides a framework to describe how geometric notions in the gravity system, such as spacetime subregions, different notions of times, and causal structure, emerge from the dual CFT. Subalgebra-subregion duality generalizes and brings new insights into subregion-subregion duality (or equivalently entanglement wedge reconstruction). It provides a mathematically precise definition of subregion-subregion duality and gives an independent definition of entanglement wedges without using entropy. Geometric properties of entanglement wedges, including those that play a crucial role in interpreting the bulk as a quantum error correcting code, can be understood from the duality as the geometrization of the additivity anomaly of certain algebras. Using general boundary subalgebras rather than those associated with geometric subregions makes it possible to find duals for general bulk spacetime regions, including those not touching the boundary. Applying subalgebra-subregion duality to a boundary state describing a single-sided black hole also provides a precise way to define mirror operators.Comment: 104 pages, 29 figure

    Developing interest to share and craft based on the Technology Acceptance Model

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    The Malaysian Ministry of Education aims to increase interest in learning Science, Technology, Engineering and Mathematics, through Science2Action. Among these initiatives in Science2Action, is the use of Art(s). By combining the Internet, technology and crafts, e-crafting is formed. This e-crafting project aims to increase awareness about what interests the audience through sharing of and development of craft, hopefully towards possibilities of ideation and mixing crafts, extending from the original craft such as origami. Designed based on the Technology Acceptance Model, findings are positive

    Identification of a Delta 4 fatty acid desaturase from Thraustochytrium sp. involved in the biosynthesis of docosahexanoic acid by heterologous expression in Saccharomyces cerevisiae and Brassica juncea.

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    The existence of Delta 4 fatty acid desaturation in the biosynthesis of docosahexanoic acid (DHA) has been questioned over the years. In this report we describe the identification from Thraustochytrium sp. of two cDNAs, Fad4 and Fad5, coding for Delta 4 and Delta 5 fatty acid desaturases, respectively. The Delta 4 desaturase, when expressed in Saccharomyces cerevisiae, introduced a double bond at position 4 of 22:5(n-3) and 22:4(n-6) resulting in the production of DHA and docosapentanoic acid. The enzyme, when expressed in Brassica juncea under the control of a constitutive promoter, desaturated the exogenously supplied substrate 22:5(n-3), resulting in the production of DHA in vegetative tissues. These results support the notion that DHA can be synthesized via Delta 4 desaturation and suggest the possibility that DHA can be produced in oilseed crops on a large scale

    Development of the MICROMEGAS Detector for Measuring the Energy Spectrum of Alpha Particles by using a 241-Am Source

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    We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting {\alpha} particles emitted from an 241-Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of {\alpha} particles from the 241-Am source can be varied by changing the flight path of the {\alpha} particle from the 241 Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the {\alpha} particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for {\alpha} particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that {\alpha} particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGAS detector for {\alpha} particles under the present conditions is found to be ~ 97.3 %

    A fiber optic spectrometry system for measuring irradiance distributions in sea ice environments

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    Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 31 (2014): 2844–2857, doi:10.1175/JTECH-D-14-00108.1.A fiber optic–based spectrometry system was developed to enable automated, long-term measurements of spectral irradiance in sea ice environments. This system utilizes a single spectrometer module that measures the irradiance transmitted by multiple optical fibers, each coupled to the input fiber of the module via a mechanical rotary multiplexer. Small custom-printed optical diffusers, fixed to the input end of each fiber, allow these probes to be frozen into ice auger holes as small as 5 cm in diameter. Temperature-dependent biases in the spectrometer module and associated electronics were examined down to −40°C using an environmental chamber to identify any artifacts that might arise when operating these electronic and optical components below their vendor-defined lower temperature limits. The optical performance of the entire system was assessed by freezing multiple fiber probes in a 1.2-m-tall ice column, illuminating from above with a light source, and measuring spectral irradiance distributions at different depths within the ice column. Results indicated that the radiometric sensitivity of this fiber-based system is comparable to that of commercially available oceanographic spectroradiometers.This research was supported by the Joint Initiative Awards Fund from the Andrew W. Mellon Foundation, through Woods Hole Oceanographic Institution’s internal Interdisciplinary Study Award program (S. R. L. and T. M.), and by a China scholarship council (CSC) scholarship and the Program for Zhejiang Leading Team of S&T Innovation (Grant 2010R50036) provided to H. W.2015-06-0

    Ab initio theory of polarons: formalism and applications

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    We develop a theoretical and computational framework to study polarons in semiconductors and insulators from first principles. Our approach provides the formation energy, excitation energy, and wavefunction of both electron and hole polarons, and takes into account the coupling of the electron or hole to all phonons. An important feature of the present method is that it does not require supercell calculations, and relies exclusively on electron band structures, phonon dispersions, and electron-phonon matrix elements obtained from calculations in the crystal unit cell. Starting from the Kohn-Sham (KS) equations of density-functional theory, we formulate the polaron problem as a variational minimization, and we obtain a nonlinear eigenvalue problem in the basis of KS states and phonon eigenmodes. In our formalism the electronic component of the polaron is expressed as a coherent superposition of KS states, in close analogy with the solution of the Bethe-Salpeter equation for the calculation of excitons. We demonstrate the power of the methodology by studying polarons in LiF and Li2O2. We show that our method describes both small and large polarons, and seamlessly captures Frohlich-type polar electron-phonon coupling and non-Frohlich coupling to acoustic and optical phonons. To analyze in quantitative terms the electron-phonon coupling mechanisms leading to the formation of polarons, we introduce spectral decompositions similar to the Eliashberg spectral function. We validate our theory using both analytical results and direct calculations on large supercells. This study constitutes a first step toward complete ab initio many-body calculations of polarons in real materials.Comment: 26 pages, 8 figure
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