4,745 research outputs found

    Integrable Minisuperspace Models with Liouville Field: Energy Density Self-Adjointness and Semiclassical Wave Packets

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    The homogeneous cosmological models with a Liouville scalar field are investigated in classical and quantum context of Wheeler-DeWitt geometrodynamics. In the quantum case of quintessence field with potential unbounded from below and phantom field, the energy density operators are not essentially self-adjoint and self-adjoint extensions contain ambiguities. Therefore the same classical actions correspond to a family of distinct quantum models. For the phantom field the energy spectrum happens to be discrete. The probability conservation and appropriate classical limit can be achieved with a certain restriction of the functional class. The appropriately localized wave packets are studied numerically using the Schrodinger's norm and a conserved Mostafazadeh's norm introduced from techniques of pseudo-Hermitian quantum mechanics. These norms give a similar packet evolution that is confronted with analytical classical solutions.Comment: Main points emphasized, less important material shortened; 24 pages, 13 figure

    The density-functional theory of quantum droplets

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    In quantum droplets, the mean-field energy is comparable to the Lee-Huang-Yang (LHY) energy. In the Bogoliubov theory, the LHY energy of the quantum droplet has an imaginary part, but it is neglected for practical purposes. So far, most theoretical studies of quantum droplets have been based on the extended Gross-Pitaevskii (GP) equation obtained by adding the LHY energy to the GP equation. In this article, we present the density-functional theory of quantum droplets. In our approach, the quantum fluctuations in quantum droplets, as described by an effective action, generate the correlation energy which is real and can be determined self-consistently. Our results are consistent with the extended GP equation in the dilute limit, and the implications to current experiments on quantum droplets are discussed

    Learning Visual Features from Snapshots for Web Search

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    When applying learning to rank algorithms to Web search, a large number of features are usually designed to capture the relevance signals. Most of these features are computed based on the extracted textual elements, link analysis, and user logs. However, Web pages are not solely linked texts, but have structured layout organizing a large variety of elements in different styles. Such layout itself can convey useful visual information, indicating the relevance of a Web page. For example, the query-independent layout (i.e., raw page layout) can help identify the page quality, while the query-dependent layout (i.e., page rendered with matched query words) can further tell rich structural information (e.g., size, position and proximity) of the matching signals. However, such visual information of layout has been seldom utilized in Web search in the past. In this work, we propose to learn rich visual features automatically from the layout of Web pages (i.e., Web page snapshots) for relevance ranking. Both query-independent and query-dependent snapshots are considered as the new inputs. We then propose a novel visual perception model inspired by human's visual search behaviors on page viewing to extract the visual features. This model can be learned end-to-end together with traditional human-crafted features. We also show that such visual features can be efficiently acquired in the online setting with an extended inverted indexing scheme. Experiments on benchmark collections demonstrate that learning visual features from Web page snapshots can significantly improve the performance of relevance ranking in ad-hoc Web retrieval tasks.Comment: CIKM 201

    Semi-classical predictions of cosmological wave-packets from ridge-lines

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    We introduce a concept of ridge-lines to investigate the semi-classical prediction from wave-packets with arbitrary width in conventional quantum mechanics and the Wheeler--DeWitt quantum cosmology. Two primary approaches are applied to the exact calculation of the ridge-lines, namely the contour and the stream approach. Moreover, aspects of these are discussed and compared to other scenarios and approaches, i.e. the narrow WKB wave-packets and the first-derivative test. As the main result, we show that the semi-classical predictions in toy models have more abundant solutions than in the classical theory, and most interestingly they may deviate from classical solutions due to the quantum corrections.Comment: 44 pages, 14 figures, 3 table

    Japan Sea Thermohaline Structure and Circulation. Part II: A Variational P-Vector Method

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    The second part of this work investigates the seasonal variabilities of the Japan/East Sea (JES) circulation using the U.S. Navy Generalized Digital Environmental Model (GDEM) climatological temperature and salinity dataset (public domain) on a 0.5° x 0.5° grid. A variational P-vector method was developed to invert the velocity field. The GDEM for the JES was built up on historical (1930–97) 136 509 temperature and 52 572 salinity profiles. The climatological mean and seasonal variability of the current systems are well inverted, especially the Tsushima Warm Current and its bifurcation, the East Korean Warm Current (EKWC), the Japan nearshore branch, the confluence of the EKWC, and the North Korean Cold Current near the Korean coast and flows northeastward along the subpolar front, and a mesoscale anticyclonic eddy in the Ulleng/Tsushima Basin. Furthermore, this method has the capability to invert flow reasonably well across the shallow straits such as the Tsushima/Korea, Tsugaru, and Soya Straits. The GDEM temperature and salinity and the inverted velocity fields provide balanced initial fields for JES numerical modeling and simulation.Office of Naval ResearchNaval Oceanographic OfficeNaval Postgraduate SchoolN0001401WR2021

    Career development impact on architecture undergrads’ employment: learning motivation mediation

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    This study, utilizing the expectancy-value theory, examines the relationship between career development, learning motivation, and employment capabilities among Chinese architecture undergraduates. Surveying 319 students from five Chinese universities, the research reveals that career development has a positive impact on both employment capabilities and learning motivation. Learning motivation, in turn, positively affects employment capabilities and acts as a mediator between career development and employment capabilities. These findings underscore the significance of proactive career planning, goal setting, and intrinsic learning motivation in enhancing students' employment capabilities. For practical applications, educational institutions can design comprehensive career development programs to assist students in defining career goals and igniting intrinsic motivation for learning, thereby fostering career success and employability among architecture students
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