Results 1 - 10 of 20,556

Detecting Long-Run Abnormal Stock Returns: The Empirical Power and Specification of Test Statistics

by Brad M. Barber, John D. Lyon - Journal of Financial Economics , 1997
"... We analyze the empirical power and specification of test statistics in event studies designed to detect long-run (one- to five-year) abnormal stock returns. We document that test statistics based on abnormal returns calculated using a reference portfolio, such as a market index, are misspecified (em ..."
Abstract - Cited by 548 (9 self) - Add to MetaCart
We analyze the empirical power and specification of test statistics in event studies designed to detect long-run (one- to five-year) abnormal stock returns. We document that test statistics based on abnormal returns calculated using a reference portfolio, such as a market index, are misspecified

Geodesic Active Contours

by Vicent Caselles, Ron Kimmel, Guillermo Sapiro , 1997
"... A novel scheme for the detection of object boundaries is presented. The technique is based on active contours evolving in time according to intrinsic geometric measures of the image. The evolving contours naturally split and merge, allowing the simultaneous detection of several objects and both in ..."
Abstract - Cited by 1425 (47 self) - Add to MetaCart
A novel scheme for the detection of object boundaries is presented. The technique is based on active contours evolving in time according to intrinsic geometric measures of the image. The evolving contours naturally split and merge, allowing the simultaneous detection of several objects and both

Learning Patterns of Activity Using Real-Time Tracking

by Chris Stauffer, W. Eric L. Grimson - IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE , 2000
"... Our goal is to develop a visual monitoring system that passively observes moving objects in a site and learns patterns of activity from those observations. For extended sites, the system will require multiple cameras. Thus, key elements of the system are motion tracking, camera coordination, activit ..."
Abstract - Cited by 898 (10 self) - Add to MetaCart
, activity classification, and event detection. In this paper, we focus on motion tracking and show how one can use observed motion to learn patterns of activity in a site. Motion

W4: Real-time surveillance of people and their activities

by Ismail Haritaoglu, David Harwood, Larry S. Davis - IEEE Transactions on Pattern Analysis and Machine Intelligence , 2000
"... w4 is a real time visual surveillance system for detecting and tracking multiple people and monitoring their activities in an outdoor environment. It operates on monocular gray-scale video imagery, or on video imagery from an infrared camera. W4 employs a combination of shape analysis and tracking t ..."
Abstract - Cited by 709 (9 self) - Add to MetaCart
w4 is a real time visual surveillance system for detecting and tracking multiple people and monitoring their activities in an outdoor environment. It operates on monocular gray-scale video imagery, or on video imagery from an infrared camera. W4 employs a combination of shape analysis and tracking

Data networks

by L. Verger G, E. Gros D'aillon G, P. Major H, G. Németh H , 1992
"... a b s t r a c t In this paper we illustrate the core technologies at the basis of the European SPADnet project (www. spadnet.eu), and present the corresponding first results. SPADnet is aimed at a new generation of MRI-compatible, scalable large area image sensors, based on CMOS technology, that are ..."
Abstract - Cited by 2210 (5 self) - Add to MetaCart
, that are networked to perform gamma-ray detection and coincidence to be used primarily in (Time-of-Flight) Positron Emission Tomography (PET). The project innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction

Predictive reward signal of dopamine neurons

by Wolfram Schultz - Journal of Neurophysiology , 1998
"... Schultz, Wolfram. Predictive reward signal of dopamine neurons. is called rewards, which elicit and reinforce approach behav-J. Neurophysiol. 80: 1–27, 1998. The effects of lesions, receptor ior. The functions of rewards were developed further during blocking, electrical self-stimulation, and drugs ..."
Abstract - Cited by 747 (12 self) - Add to MetaCart
environmental stimuli with appe- Despite their importance, rewards do not influence the brain titive value, predict and detect rewards and signal alerting and motivating events. By failing to discriminate between different

The nesC language: A holistic approach to networked embedded systems

by David Gay, Matt Welsh, Philip Levis, Eric Brewer, Robert Von Behren, David Culler - In Proceedings of Programming Language Design and Implementation (PLDI , 2003
"... We present nesC, a programming language for networked embedded systems that represent a new design space for application developers. An example of a networked embedded system is a sensor network, which consists of (potentially) thousands of tiny, lowpower “motes, ” each of which execute concurrent, ..."
Abstract - Cited by 943 (48 self) - Add to MetaCart
, reactive programs that must operate with severe memory and power constraints. nesC’s contribution is to support the special needs of this domain by exposing a programming model that incorporates event-driven execution, a flexible concurrency model, and component-oriented application design. Restrictions

Managing Energy and Server Resources in Hosting Centers

by Jeffrey S. Chase, Darrell C. Anderson, Prachi N. Thakar, Amin M. Vahdat - In Proceedings of the 18th ACM Symposium on Operating System Principles (SOSP , 2001
"... Interact hosting centers serve multiple service sites from a common hardware base. This paper presents the design and implementation of an architecture for resource management in a hosting center op-erating system, with an emphasis on energy as a driving resource management issue for large server cl ..."
Abstract - Cited by 574 (37 self) - Add to MetaCart
clusters. The goals are to provi-sion server resources for co-hosted services in a way that automati-cally adapts to offered load, improve the energy efficiency of server dusters by dynamically resizing the active server set, and respond to power supply disruptions or thermal events by degrading service

Recognition-by-components: A theory of human image understanding

by Irving Biederman - Psychological Review , 1987
"... The perceptual recognition of objects is conceptualized to be a process in which the image of the input is segmented at regions of deep concavity into an arrangement of simple geometric components, such as blocks, cylinders, wedges, and cones. The fundamental assumption of the proposed theory, recog ..."
Abstract - Cited by 1272 (23 self) - Add to MetaCart
, recognition-by-components (RBC), is that a modest set of generalized-cone components, called geons (N ^ 36), can be derived from contrasts of five readily detectable properties of edges in a two-dimensional image: curvature, collinearity, symmetry, parallelism, and cotermmation. The detection

Brain magnetic resonance imaging with contrast dependent on blood oxygenation.

by S Ogawa , T M Lee , A R Kay , D W Tank - Proc. Natl. Acad. Sci. USA , 1990
"... ABSTRACT Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high fields, we demonstrate in vivo images of brain microvasculature with imag ..."
Abstract - Cited by 648 (1 self) - Add to MetaCart
) the concentration of paramagnetic deoxyhemoglobin and (ii) the orientation of the vessel relative to the main magnetic field (8, 9). Since BOLD contrast depends on the state of blood oxygenation, physiological events that change the oxy/ deoxyhemoglobin ratio should lend themselves to noninvasive detection through
Results 1 - 10 of 20,556