131,339 research outputs found

    Trade-time based measures of liquidity

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    Dramatic microstructure changes in equity markets have made standard liquidity measures less accurate proxies for trading costs. We develop trade-time liquidity measures that reflect per-dollar price impacts of fixed-dollar volumes. Our measures better capture institutional trading costs and better explain the cross-section of returns than do standard measures, especially in recent years. Despite improvements in measures of market quality, expected trading costs have explanatory power for the cross-section of expected returns: we obtain monthly liquidity premium estimates of 5.3 bp for expected returns and 2.4 bp for risk-adjusted returns. Estimated premiums rise after the financial crisis and remain high thereafter

    Time-based selection in complex displays : visual marking does not occur in multi-element asynchronous dynamic (MAD) search

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    In visual search, a preview benefit occurs when half of the distractor items (the preview set) are presented before the remaining distractor items and the target (the search set). Separating the display across time allows participants to prioritize the search set, leading to increased search efficiency. To date, such time-based selection has been examined using relatively simple types of search displays. However, recent research has shown that when displays better mimic real-world scenes by including a combination of stationary, moving and luminance-changing items (Multi-element Asynchronous Dynamic [MAD] displays), previous search principles reported in the literature no longer apply. In the current work, we examined time-base selection in MAD search conditions. Overall the findings illustrated an advantage for processing new items based on overall RTs but no advantage in terms of search rates. In the absence of a speed–accuracy trade-off no preview benefit emerged when using more complex MAD stimuli

    Data Structure for a Time-Based Bandwidth Reservations Problem

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    We discuss a problem of handling resource reservations. The resource can be reserved for some time, it can be freed or it can be queried what is the largest amount of reserved resource during a time interval. We show that the problem has a lower bound of Ω(logn)\Omega(\log n) per operation on average and we give a matching upper bound algorithm. Our solution also solves a dynamic version of the related problems of a prefix sum and a partial sum

    Learning to ignore : the development of time-based visual attention in children

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    Adults can ignore old and prioritize newly arriving visual stimuli, enabling optimal goal-directed search (visual marking; Watson & Humphreys, 1997). However, the ability to use time of appearance to enhance visual search is currently absent in work on attentional development in children. Experiment 1 examined children’s (6-, 8-, and 12-year-olds) and adults’ ability to ignore old and prioritize new stimuli and the relationship of this ability to executive functions. Experiment 2 examined whether the components involved in ignoring old items (encoding and maintenance) change across age, by presenting old stimuli for relatively short (500 ms), medium (1,000 ms) or long (1,500 ms) durations. On average, all age groups could ignore old items presented for 1,000 ms to some degree, however 25% of 6-year-olds were not able to prioritize new items effectively. No relationship was observed between the development of this ability and measures of executive function. On average, all age groups could ignore old items presented for short durations, however, 6-year-olds had difficulty ignoring stimuli presented for long durations. The findings suggest that the ability to ignore old items in order to prioritize search through new information is relatively weak in 6-year-olds, especially when ignoring items over longer durations. Furthermore, the findings indicate that the encoding and maintenance components involved in prioritizing new items might follow distinct developmental trajectories. (PsycINFO Database Record (c) 2018 APA, all rights reserved

    A time-based concept for terminal-area traffic management

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    An automated air-traffic-management concept that has the potential for significantly increasing the efficiency of traffic flows in high-density terminal areas is discussed. The concept's implementation depends on the techniques for controlling the landing time of all aircraft entering the terminal area, both those that are equipped with on-board four dimensional guidance systems as well as those aircraft types that are conventionally equipped. The two major ground-based elements of the system are a scheduler which assigns conflict-free landing times and a profile descent advisor. Landing times provided by the scheduler are uplinked to equipped aircraft and translated into the appropriate four dimensional trajectory by the on-board flight-management system. The controller issues descent advisories to unequipped aircraft to help them achieve the assigned landing times. Air traffic control simulations have established that the concept provides an efficient method for controlling various mixes of four dimensional-equipped and unequipped, as well as low-and high-performance, aircraft

    Continuous Monitoring of Distributed Data Streams over a Time-based Sliding Window

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    The past decade has witnessed many interesting algorithms for maintaining statistics over a data stream. This paper initiates a theoretical study of algorithms for monitoring distributed data streams over a time-based sliding window (which contains a variable number of items and possibly out-of-order items). The concern is how to minimize the communication between individual streams and the root, while allowing the root, at any time, to be able to report the global statistics of all streams within a given error bound. This paper presents communication-efficient algorithms for three classical statistics, namely, basic counting, frequent items and quantiles. The worst-case communication cost over a window is O(kϵlogϵNk)O(\frac{k} {\epsilon} \log \frac{\epsilon N}{k}) bits for basic counting and O(kϵlogNk)O(\frac{k}{\epsilon} \log \frac{N}{k}) words for the remainings, where kk is the number of distributed data streams, NN is the total number of items in the streams that arrive or expire in the window, and ϵ<1\epsilon < 1 is the desired error bound. Matching and nearly matching lower bounds are also obtained.Comment: 12 pages, to appear in the 27th International Symposium on Theoretical Aspects of Computer Science (STACS), 201

    SMIL State: an architecture and implementation for adaptive time-based web applications

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    In this paper we examine adaptive time-based web applications (or presentations). These are interactive presentations where time dictates which parts of the application are presented (providing the major structuring paradigm), and that require interactivity and other dynamic adaptation. We investigate the current technologies available to create such presentations and their shortcomings, and suggest a mechanism for addressing these shortcomings. This mechanism, SMIL State, can be used to add user-defined state to declarative time-based languages such as SMIL or SVG animation, thereby enabling the author to create control flows that are difficult to realize within the temporal containment model of the host languages. In addition, SMIL State can be used as a bridging mechanism between languages, enabling easy integration of external components into the web application. Finally, SMIL State enables richer expressions for content control. This paper defines SMIL State in terms of an introductory example, followed by a detailed specification of the State model. Next, the implementation of this model is discussed. We conclude with a set of potential use cases, including dynamic content adaptation and delayed insertion of custom content such as advertisements. © 2009 Springer Science+Business Media, LLC
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