5,078 research outputs found

    Black Hole as a Wormhole Factory

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    On general grounds, one may argue that a black hole stops radiation at the Planck mass, where the radiated energy is comparable to the black hole's mass. And also, it has been argued that there would be a "wormhole-like" structure, known as "space-time foam", due to large fluctuations below the Planck length. In this paper, as an explicit example, we consider an exact classical solution which represents nicely those two properties in a recently proposed quantum gravity model based on different scaling dimensions between space and time coordinates. The solution, called "Black Wormhole", consists of two different states, depending on its mass M and an IR parameter omega: For the black hole state, a non-traversable wormhole occupies the interior region of the black hole around the singularity at the origin, whereas for the wormhole state, the interior wormhole is exposed to an outside observer as the black hole horizon is disappeared from evaporation. The black hole state becomes thermodynamically stable as it approaches to the merge point where the interior wormhole throat and the black hole horizon merges, and the Hawking temperature vanishes at the exact merge point. This solution suggests the "Generalized Cosmic Censorship" by the existence of a wormhole-like structure which protects the naked singularity even after the black hole evaporation. One could understand the would-be wormholes inside the black hole horizon as the results of microscopic wormholes created by "negative" energy quanta which have entered the black hole horizon in Hawking radiation processes: The quantum black hole could be a wormhole factory. It is found that this speculative picture may be consistent with the recent "ER=EPR" proposal for resolving the recent black hole entanglement debates.Comment: Added some more words on (1) the transition between the black hole phase and wormhole phase and (2) the notion of a wormhole "factory" in Fig. 5. Updated references, Accepted in PL

    Maximizing The Impact Of Improvement Efforts On Customer Satisfaction

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    When a customer satisfaction survey consists of a large number of attributes (questionnaire items), determination of critical attributes that would make the biggest impact on customersā€™ overall satisfaction could be important, but very tedious and time-consuming process. Even though the critical attributes are identified, the improvement efforts toward these attributes are often misdirected and wasted because of the mismatch between the improvement efforts and the critical needs of the affected customer group. This paper introduces a method with which improvement efforts can be tailored to the needs of the customer group who could bring the most impactful influence on improving customer satisfaction. For the critical attribute considered, the percentage of customers who assigned a specific satisfaction rating is obtained, and the cumulative percentages of customers are examined and the target group of customers to whom the improvement efforts would be tailored is identified. The piecewise linear approximation method is also discussed to estimate the non-linear relationship of the attribute, which also may help determine the target customer group. The overall shape of the piecewise function and the slopes at the line segments may be used in determining which attributes are satisfaction-maintaining or satisfaction-enhancing, and where and how the improvement efforts should be focused in order to maximize the effectiveness of the improvement efforts

    Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

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    The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid

    Drawing my office : a study on architectural representation of time.

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    This thesis is an attempt to recover the temporality of architecture. Although many contemporary architects argue their ways of dealing with time in their architecture, their idea of time is confined within narrow-mined assumptions of science, and their methods are locked in the intrinsic limitation of architectural representation. This thesis criticises the idea of time with only successive instants for its incompetence of accommodating our exuberant experience of architecture, and finds the origin of the problem at the conventional architectural representation which cannot show what we are together with, but just what we can confront. As a "research by design", this thesis is led by a desigri experiment, which is simply to represent my office. The experiment tries to catch the time of my office with various strategies, and the theory follows it while weaving a story by analysing and evaluating it. Theoretical arguments, which have been initiated mainly from Deleuze, grope for their way in the dialogue with drawings. The strategy of drawing experiment is to approve material and conceptual substantiality of drawing so that it can 'work' in time. Concerning the material substantiality, physical size, shape, texture and frame of paper, and various qualities of lines and touches are examined. For the conceptual substantiality, metamorphosis of meaning, isolated figures, vibrating picture ground, and forces in drawing are explored. Ironically, the drawing can manifest my office-ness when it is truly itself. Although the experiment may not be executed in a systematic order, I hope that its audience will generate with the drawings his/her own meanings and sensations, which may 'evolve' into his/her architecture

    Transition-pathway models of atomic diffusion on fcc metal surfaces. II. Stepped surfaces

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    Action-derived molecular dynamics was demonstrated in the companion paper (Paper I) to be effective for the analysis of atomic surface diffusion. The method is here applied to the search of minimum-energy paths and the calculation of activation energy barriers in more complex single-adatom diffusion processes on fcc metal surfaces containing steps. Diverse diffusion routes are investigated along and across one- or two-layer steps on different surface orientations. Fundamental diffusion mechanisms near the step corners are also studied. Results are analyzed in relation to the island growth mechanism, which is of importance to surface nanoengineering.open221

    Learning experiences and college access of American workers: Evidence from PIAAC

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    Using the U.S. data from the Program for the International Assessment of Adult Competencies (PIAAC), this study aims to explore how work-related learning experiences of working adults influence their sub-baccalaureate or baccalaureate degree-seeking in higher education institutions (HEIs). Given many jobs in the U.S. that require higher education credentials, we examined how formal and informal work-related learning experiences are associated with the college access of working adults who have a high school diploma. The multinomial logistic regression results show that work flexibility, distance learning, and private learning experience are positively related to working adultsā€™ college access. Based on the findings, implications for policy and practice were discussed on how industry and organizations could support working adultsā€™ learning opportunities in the workplace and HEIs
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