University of California, Irvine

About: University of California, Irvine is a education organization based out in Irvine, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 47031 authors who have published 113602 publications receiving 5521832 citations. The organization is also known as: UC Irvine & UCI.

A Motivational Theory of Life-Span Development

Abstract: This article had four goals. First, the authors identified a set of general challenges and questions that a life-span theory of development should address. Second, they presented a comprehensive account of their Motivational Theory of Life-Span Development. They integrated the model of optimization in primary and secondary control and the action-phase model of developmental regulation with their original life-span theory of control to present a comprehensive theory of development. Third, they reviewed the relevant empirical literature testing key propositions of the Motivational Theory of Life-Span Development. Finally, because the conceptual reach of their theory goes far beyond the current empirical base, they pointed out areas that deserve further and more focused empirical inquiry.

Probabilistic Topic Models

Abstract: Many chapters in this book illustrate that applying a statistical method such as latent semantic analysis (LSA; Landauer & Dumais, 1997; Landauer, Foltz, & Laham, 1998) to large databases can yield insight into human cognition. The LSA approach makes three claims: that semantic information can be derived from a word-document co-occurrence matrix; that dimensionality reduction is an essential part of this derivation; and that words and documents can be represented as points in Euclidean space. This chapter pursues an approach that is consistent with the first two of these claims, but differs in the third, describing a class of statistical models in which the semantic properties of words and documents are expressed in terms of probabilistic topics.

Analysis of daily, monthly, and annual burned area using the fourth‐generation global fire emissions database (GFED4)

Abstract: [1] We describe the fourth generation of the Global Fire Emissions Database (GFED4) burned area data set, which provides global monthly burned area at 0.25° spatial resolution from mid-1995 through the present and daily burned area for the time series extending back to August 2000. We produced the full data set by combining 500 m MODIS burned area maps with active fire data from the Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) and the Along-Track Scanning Radiometer (ATSR) family of sensors. We found that the global annual area burned for the years 1997 through 2011 varied from 301 to 377Mha, with an average of 348Mha. We assessed the interannual variability and trends in burned area on the basis of a region-specific definition of fire years. With respect to trends, we found a gradual decrease of 1.7Mhayr − 1 ( − 1.4%yr − 1) in Northern Hemisphere Africa since 2000, a gradual increase of 2.3Mhayr − 1 (+1.8%yr − 1) in Southern Hemisphere Africa also since 2000, a slight increase of 0.2Mhayr − 1 (+2.5%yr − 1) in Southeast Asia since 1997, and a rapid decrease of approximately 5.5Mhayr − 1 ( − 10.7%yr − 1) from 2001 through 2011 in Australia, followed by a major upsurge in 2011 that exceeded the annual area burned in at least the previous 14 years. The net trend in global burned area from 2000 to 2012 was a modest decrease of 4.3Mhayr − 1 ( − 1.2%yr − 1). We also performed a spectral analysis of the daily burned area time series and found no vestiges of the 16 day MODIS repeat cycle.

Stress and glucocorticoids impair retrieval of long-term spatial memory

Abstract: Extensive evidence from animal and human studies indicates that stress and glucocorticoids influence cognitive function. Previous studies have focused exclusively on glucocorticoid effects on acquisition and long-term storage of newly acquired information. Here we report that stress and glucocorticoids also affect memory retrieval. We show that rats have impaired performance in a water-maze spatial task after being given footshock 30 min before retention testing but are not impaired when footshock is given 2 min or 4 h before testing. These time-dependent effects on retention performance correspond to the circulating corticosterone levels at the time of testing, which suggests that the retention impairment is directly related to increased adrenocortical function. In support of this idea, we find that suppression of corticosterone synthesis with metyrapone blocks the stress-induced retention impairment. In addition, systemic corticosterone administered to non-stressed rats 30 min before retention testing induces dose-dependent retention impairment. The impairing effects of stress and glucocorticoids on retention are not due to disruption of spatial navigation per se. Our results indicate that besides the well described effects of stress and glucocorticoids on acquisition and consolidation processes, glucocorticoids also affect memory retrieval mechanisms.