University of Memphis

About: University of Memphis is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 7710 authors who have published 20082 publications receiving 611618 citations. The organization is also known as: U of M.

Differential effects of aging on memory for content and context: a meta-analysis.

Abstract: The authors reviewed the evidence of age differences in episodic memory for content of a message and the context associated with it. Specifically, the authors tested a hypothesis that memory for context is more vulnerable to aging than memory for content. In addition, the authors inquired whether effort at encoding and retrieval and type of stimulus material moderate the magnitude of age differences in both memory domains. The results of the meta-analysis of 46 studies confirmed the main hypothesis: Age differences in context memory are reliably greater than those in memory for content. Tasks that required greater effort during retrieval yielded larger age differences in content but not in context memory. The greatest magnitude of age differences in context memory was observed for those contextual features that were more likely to have been encoded independently from content. Possible mechanisms that may underlie age differences in context memory-attentional deficit, reduced working memory capacity, and failure of inhibitory processing are discussed.

Comorbidity of chronic insomnia with medical problems.

Abstract: Study Objectives: Determine the comorbidity of insomnia with medical problems. Design: Cross-sectional and retrospective. Participants: Community-based population of 772 men and women, aged 20 to 98 years old. Measurements: Self-report measures of sleep, health, depression, and anxiety. Results: People with chronic insomnia reported more of the following than did people without insomnia: heart disease (21.9% vs 9.5%), high blood pressure (43.1% vs 18.7%), neurologic disease (7.3% vs 1.2%), breathing problems (24.8% vs 5.7%), urinary problems (19.7% vs 9.5%), chronic pain (50.4% vs 18.2%), and gastrointestinal problems (33.6% vs 9.2%). Conversely, people with the following medical problems reported more chronic insomnia than did those without those medical problems: heart disease (44.1% vs 22.8%), cancer (41.4% vs 24.6%), high blood pressure (44.0% vs 19.3%), neurologic disease (66.7% vs 24.3%), breathing problems (59.6% vs 21.4%), urinary problems (41.5% vs 23.3%), chronic pain (48.6% vs 17.2%), and gastrointestinal problems (55.4% vs 20.0%). When all medical problems were considered together, only patients with high blood pressure, breathing problems, urinary problems, chronic pain, and gastrointestinal problems continued to have statistically higher levels of insomnia than those without these medical disorders. Conclusion: This study demonstrates significant overlap between insomnia and multiple medical problems. Some research has shown it is possible to treat insomnia that is comorbid with select psychiatric (depression) and medical (eg, pain and cancer) disorders, which in turn increases the quality of life and functioning of these patients. The efficacy of treating insomnia in many of the above comorbid disorders has not been tested, indicating a need for future treatment research.

Agency conflict and corporate strategy: the effect of divestment on corporate value

Abstract: Among the various stakeholders of a firm, senior managers are the most likely targets for private and public political pressures. Other stakeholder groups are less visible and may be perceived as less influential in corporate strategy formulation and implementation. In some situations, consequently, senior executives may adopt corporate strategies in response to political pressures even if these strategies may be costly to shareholders. In this study, a special case is examined: the effect of divestment of South African business units on firm value. Using data from 1984 through 1990, we examine the impact that announcements of divestments have upon the stock return behavior of publicly traded firms. Our results indicate that significant and negative excess returns accrue to shares of companies announcing divestments of South African operations. These results are supportive of the premise that noneconomic pressures may influence managerial strategies rather than value-enhancement goals. © 1997 by John Wiley & Sons, Ltd.

Rule discovery from time series

Abstract: We consider the problem of finding rules relating patterns in a time series to other patterns in that series, or patterns in one series to patterns in another series A simple example is a rule such as "a period of low telephone call activity is usually followed by a sharp rise in call volume" Examples of rules relating two or more time series are "if the Microsoft stock price goes up and Intel falls, then IBM goes up the next day," and "if Microsoft goes up strongly for one day, then declines strongly on the next day, and on the same days Intel stays about level, then IBM stays about level" Our emphasis is in the discovery of local patterns in multivariate time series, in contrast to traditional time series analysis which largely focuses on global models Thus, we search for rules whose conditions refer to patterns in time series However, we do not want to define beforehand which patterns are to be used; rather, we want the patterns to be formed from the data in the context of rule discovery We describe adaptive methods for finding rules of the above type from time-series data The methods are based on discretizing the sequence by methods resembling vector quantization We first form subsequences by sliding a window through the time series, and then cluster these subsequences by using a suitable measure of time-series similarity The discretized version of the time series is obtained by taking the cluster identifiers corresponding to the subsequence Once the time-series is discretized, we use simple rule finding methods to obtain rules from the sequence We present empirical results on the behavior of the method