A seismic study of the Iceland-Faeroes ridge

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Exploring Vision-Based Interfaces: How to Use Your Head in Dual Pointing Tasks

The utility of vision-based face tracking for dual pointing tasks is evaluated. We first describe a 3-D face tracking technique based on real-time parametric motion-stereo, which is non-invasive, robust, and self-initialized. The tracker provides a real-time estimate of a ?frontal face ray? whose intersection with the display surface plane is used as a second stream of input for scrolling or pointing, in paral-lel with hand input. We evaluated the performance of com-bined head/hand input on a box selection and coloring task: users selected boxes with one pointer and colors with a second pointer, or performed both tasks with a single pointer. We found that performance with head and one hand was intermediate between single hand performance and dual hand performance. Our results are consistent with previously reported dual hand conflict in symmetric pointing tasks, and suggest that a head-based input stream should be used for asymmetric control

Plan-view Trajectory Estimation with Dense Stereo Background Models

In a known environment, objects may be tracked in multiple views using a set of back-ground models. Stereo-based models can be illumination-invariant, but often have undefined values which inevitably lead to foreground classification errors. We derive dense stereo models for object tracking using long-term, extended dynamic-range imagery, and by detecting and interpolating uniform but unoccluded planar regions. Foreground points are detected quickly in new images using pruned disparity search. We adopt a 'late-segmentation' strategy, using an integrated plan-view density representation. Foreground points are segmented into object regions only when a trajectory is finally estimated, using a dynamic programming-based method. Object entry and exit are optimally determined and are not restricted to special spatial zones

Substrate noise analysis and techniques for mitigation in mixed-signal RF systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 151-158).Mixed-signal circuit design has historically been a challenge for several reasons. Parasitic interactions between analog and digital systems on a single die are one such challenge. Switching transients induced by digital circuits inject noise into the common substrate creating substrate noise. Analog circuits lack the large noise margins of digital circuits, thus making them susceptible to substrate voltage variations. This problem is exacerbated at higher frequencies as the effectiveness of standard isolation technique diminishes considerably. Historically, substrate noise was not a problem because each system was fabricated in its own package shielding it from such interactions. The work in this thesis spans all areas of substrate noise: generation, propagation, and reception. A set of guidelines in designing isolation structures was developed to assist designers in optimizing these structures for a particular application. Furthermore, the effect of substrate noise on two key components of the RF front end, the voltage controlled oscillator (VCO) and the low noise amplifier (LNA), was analyzed. Finally, a CAD tool (SNAT) was developed to efficiently simulate large digital designs to determine substrate noise performance.(cont.) Existing techniques have prohibitively long simulation times and are only suitable for final verification. Determination of substrate noise coupling during the design phase would be extremely beneficial to circuit designers who can incorporate the effect of the noise and re-design accordingly before fabrication. This would reduce the turn around time for circuits and prevent costly redesign. SNAT can be used at any stage of the design cycle to accurately predict (less than 12% error when compared to measurements) the substrate noise performance of any digital circuit with a large degree of computational efficiency.by Nisha Checka.Ph.D

Activity maps for location-aware computing

The Problem: Location-based context is important for many applications. Previous systems offered only coarse room-level features or used manually specified room regions to determine fine-scale features. We propose a location context mechanism based on activity maps, which define regions of similar context based on observations of 3-D patterns of location and motion in an environment. We describe an algorithm for obtaining activity maps in real time using the spatio-temporal clustering of visual tracking data. Motivation: In many cases, fine grain location based information is preferred. One example would be to control lights and air conditioning, e.g. the desk lamp might light up and the air conditioning starts whenever a user is sitting at his desk. In addition the phone might become activated and the computer screen get invoked from stand-by mode. Similarly in a small group meeting the system could know where and how many people are in the room and could make appropriate settings for lights, air conditioning, and computer tools. For each of these tasks, location context information is important [3]. Simply considering the instantaneous 3-D location of users is useful, but alone is insufficient as context information. Applications have to generalize context information from previous experience, and an application writer would like to access categorical context information, such as what activity

Effect of mammographic screening from age 40 years on breast cancer mortality (UK Age trial):final results of a randomised, controlled trial

Copyright © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.BACKGROUND: The appropriate age range for breast cancer screening remains a matter of debate. We aimed to estimate the effect of mammographic screening at ages 40-48 years on breast cancer mortality. METHODS: We did a randomised, controlled trial involving 23 breast screening units across Great Britain. We randomly assigned women aged 39-41 years, using individual randomisation, stratified by general practice, in a 1:2 ratio, to yearly mammographic screening from the year of inclusion in the trial up to and including the calendar year that they reached age 48 years (intervention group), or to standard care of no screening until the invitation to their first National Health Service Breast Screening Programme (NHSBSP) screen at approximately age 50 years (control group). Women in the intervention group were recruited by postal invitation. Women in the control group were unaware of the study. The primary endpoint was mortality from breast cancers (with breast cancer coded as the underlying cause of death) diagnosed during the intervention period, before the participant's first NHSBSP screen. To study the timing of the mortality effect, we analysed the results in different follow-up periods. Women were included in the primary comparison regardless of compliance with randomisation status (intention-to-treat analysis). This Article reports on long-term follow-up analysis. The trial is registered with the ISRCTN registry, ISRCTN24647151. FINDINGS: 160 921 women were recruited between Oct 14, 1990, and Sept 24, 1997. 53 883 women (33·5%) were randomly assigned to the intervention group and 106 953 (66·5%) to the control group. Between randomisation and Feb 28, 2017, women were followed up for a median of 22·8 years (IQR 21·8-24·0). We observed a significant reduction in breast cancer mortality at 10 years of follow-up, with 83 breast cancer deaths in the intervention group versus 219 in the control group (relative rate [RR] 0·75 [95% CI 0·58-0·97]; p=0·029). No significant reduction was observed thereafter, with 126 deaths versus 255 deaths occurring after more than 10 years of follow-up (RR 0·98 [0·79-1·22]; p=0·86). INTERPRETATION: Yearly mammography before age 50 years, commencing at age 40 or 41 years, was associated with a relative reduction in breast cancer mortality, which was attenuated after 10 years, although the absolute reduction remained constant. Reducing the lower age limit for screening from 50 to 40 years could potentially reduce breast cancer mortality. FUNDING: National Institute for Health Research Health Technology Assessment programme.Peer reviewe

A system for tracking and characterizing acoustic impacts on large interactive surfaces

Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references.by Nisha Checka.M.Eng.and S.B