Automatic Wrapper Adaptation by Tree Edit Distance Matching

Information distributed through the Web keeps growing faster day by day,\ud and for this reason, several techniques for extracting Web data have been suggested\ud during last years. Often, extraction tasks are performed through so called wrappers,\ud procedures extracting information from Web pages, e.g. implementing logic-based\ud techniques. Many fields of application today require a strong degree of robustness\ud of wrappers, in order not to compromise assets of information or reliability of data\ud extracted.\ud Unfortunately, wrappers may fail in the task of extracting data from a Web page, if\ud its structure changes, sometimes even slightly, thus requiring the exploiting of new\ud techniques to be automatically held so as to adapt the wrapper to the new structure\ud of the page, in case of failure. In this work we present a novel approach of automatic wrapper adaptation based on the measurement of similarity of trees through\ud improved tree edit distance matching techniques

Design of Automatically Adaptable Web Wrappers

Nowadays, the huge amount of information distributed through the Web motivates studying techniques to\ud be adopted in order to extract relevant data in an efficient and reliable way. Both academia and enterprises\ud developed several approaches of Web data extraction, for example using techniques of artificial intelligence or\ud machine learning. Some commonly adopted procedures, namely wrappers, ensure a high degree of precision\ud of information extracted from Web pages, and, at the same time, have to prove robustness in order not to\ud compromise quality and reliability of data themselves.\ud In this paper we focus on some experimental aspects related to the robustness of the data extraction process\ud and the possibility of automatically adapting wrappers. We discuss the implementation of algorithms for\ud finding similarities between two different version of a Web page, in order to handle modifications, avoiding\ud the failure of data extraction tasks and ensuring reliability of information extracted. Our purpose is to evaluate\ud performances, advantages and draw-backs of our novel system of automatic wrapper adaptation

Atoms with bosonic "electrons" in strong magnetic fields

We study the ground state properties of an atom with nuclear charge $Z$ and $N$ bosonic ``electrons'' in the presence of a homogeneous magnetic field $B$. We investigate the mean field limit $N\to\infty$ with $N/Z$ fixed, and identify three different asymptotic regions, according to $B\ll Z^2$, $B\sim Z^2$, and $B\gg Z^2$. In Region 1 standard Hartree theory is applicable. Region 3 is described by a one-dimensional functional, which is identical to the so-called Hyper-Strong functional introduced by Lieb, Solovej and Yngvason for atoms with fermionic electrons in the region $B\gg Z^3$; i.e., for very strong magnetic fields the ground state properties of atoms are independent of statistics. For Region 2 we introduce a general {\it magnetic Hartree functional}, which is studied in detail. It is shown that in the special case of an atom it can be restricted to the subspace of zero angular momentum parallel to the magnetic field, which simplifies the theory considerably. The functional reproduces the energy and the one-particle reduced density matrix for the full $N$-particle ground state to leading order in $N$, and it implies the description of the other regions as limiting cases.Comment: LaTeX2e, 37 page

Computational models for listener-specific predictions of spatial audio quality

International audienceMillions of people use headphones every day for listening to music, watching movies, or communicating with others. Nevertheless, sounds presented via headphones are usually perceived inside the head instead of being localized at a naturally external position. Besides externalization and localization, spatial hearing also involves perceptual attributes like apparent source width, listener envelopment, and the ability to segregate sounds. The acoustic basis for spatial hearing is described by the listener-specific head-related transfer functions (HRTFs, Møller et al., 1995). Binaural virtual acoustics based on listener-specific HRTFs can create sounds presented via headphones being indistinguishable from natural sounds (Langendijk and Bronkhorst, 2000). In this talk, we will focus on the dimensions of sound localization that are particularly sensitive to listener-specific HRTFs, that is, along sagittal planes (i.e., vertical planes being orthogonal to the interaural axis) and near distances (sound externalization/internalization). We will discuss recent findings from binaural virtual acoustics and models aiming at predicting sound externalization (Hassager et al., 2016) and localization in sagittal planes (Baumgartner et al., 2014) considering the listener’s HRTFs. Sagittal-plane localization seems to be well understood and its model can already now reliably predict the localization performance in many listening situations (e.g., Marelli et al., 2015; Baumgartner and Majdak, 2015). In contrast, more investigation is required in order to better understand and create a valid model of sound externalization (Baumgartner et al., 2017). We aim to shed light onto the diversity of cues causing degraded sound externalization with spectral distortions by conducting a model-based meta-analysis of psychoacoustic studies. As potential cues we consider monaural and interaural spectral-shapes, spectral and temporal fluctuations of interaural level differences, interaural coherences, and broadband inconsistencies between interaural time and level differences in a highly comparable template-based modeling framework. Mere differences in sound pressure level between target and reference stimuli were used as a control cue. Our investigations revealed that the monaural spectral-shapes and the strengths of time-intensity trading are potent cues to explain previous results under anechoic conditions. However, future experiments will be required to unveil the actual essence of these cues.ReferencesBaumgartner, R., Majdak, P. (2015): Modeling Localization of Amplitude-Panned Virtual Sources in Sagittal Planes, in: Journal of Audio Engineering Society 63, 562-569.Baumgartner, R., Majdak, P., and Laback, B. (2014). “Modeling sound-source localization in sagittal planes for human listeners,” The Journal of the Acoustical Society of America 136, 791–802.Baumgartner, R., Reed, D. K., Tóth, B., Best, V., Majdak, P., Colburn, H. S., and Shinn-Cunningham, B. (2017). “Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias,” Proceedings of the National Academy of Sciences 114, 9743–9748.Hassager, H. G., Gran, F., and Dau, T. (2016). “The role of spectral detail in the binaural transfer function on perceived externalization in a reverberant environment,” The Journal of the Acoustical Society of America 139, 2992–3000.Langendijk, E. H., and Bronkhorst, A. W. (2000). “Fidelity of three-dimensional-sound reproduction using a virtual auditory display,” J Acoust Soc Am 107, 528–37.Marelli, D., Baumgartner, R., and Majdak, P. (2015). “Efficient Approximation of Head-Related Transfer Functions in Subbands for Accurate Sound Localization,” IEEE Transactions on Audio, Speech, and Language Processing 23, 1130–1143.Møller, H., Sørensen, M. F., Hammershøi, D., and Jensen, C. B. (1995). “Head-related transfer functions of human subjects,” J Audio Eng Soc 43, 300–321

VALIDATING CONTINGENT VALUATION WITH SURVEYS OF EXPERTS

Contingent-valuation estimates for white-water boating passengers are compared with Likert ratings by river guides. The approach involves asking whether passengers and their guides ordinally rank alternative flows the same. The National Oceanic and Atmospheric Administration's Contingent Valuation Panel (1993) suggested "one might want to compare its (contingent-valuation's) outcome with that provided by a panel of experts." River guides constitute a counterfactual panel of "experts." For commercial trips, optimum flows are 34,000 cfs and 31,000 cfs for passengers and guides, and the comparable figures for private trips are 28,000 cfs and 29,000 cfs. In the NOAA Panel framework, passengers can evaluate the consequences of various river flows and translate this into contingent-valuation responses.Resource /Energy Economics and Policy,

Rapid, Precise, and High-Sensitivity Acquisition of Paleomagnetic and Rock-Magnetic Data: Development of a Low-Noise Automatic Sample Changing System for Superconducting Rock Magnetometers

Among Earth sciences, paleomagnetism is particularly linked to the statistics of large sample sets as a matter of historical development and logistical necessity. Because the geomagnetic field varies over timescales relevant to sedimentary deposition and igneous intrusion, while the fidelity of recorded magnetization is modulated by original properties of rock units and by alteration histories, "ideal" paleomagnetic results measure remanent magnetizations of hundreds of samples at dozens of progressive demagnetization levels, accompanied by tests of magnetic composition on representative sister specimens. We present an inexpensive, open source system for automating paleomagnetic and rock magnetic measurements. Using vacuum pick-and-place technology and a quartz-glass sample holder, the system can in one hour measure remanent magnetizations, as weak as a few pAm2, of ~30 specimens in two vertical orientations with measurement errors comparable to those of the best manual systems. The system reduces the number of manual manipulations required per specimen ~8 fold