408 research outputs found
Aging and decision making: a comparison between neurologically healthy elderly and young individuals
We report the results of experiments on economic decisions with two populations, one of healthy elderly individuals (average age 82) and one of younger students (average age 20). We examine confidence, decisions under uncertainty, differences between willingness to pay and willingness to accept and the theory of mind (strategic thinking). Our findings indicate that the older adultsā decision behavior is similar to that of young adults, contrary to the notion that economic decision making is impaired with age. Moreover, some of the demonstrated decision behaviors suggest that the elderly individuals are less biased than the younger individuals
Separation of Notch1 promoted lineage commitment and expansion/transformation in developing T cells
Internet over a Bi-Directional Satellite Link
Various issues associated with "Internet over a Bi-Directional Satellite Link" are presented in viewgraph form. Specific topics include: 1) Comarison of HTTP over several network channels; 2) Improved performance of HTTP when compared to off-the-shelf software; 3) Demonstration setup of the link between Sheraton Airport Hotel, Dulles and NASA LeRC; and 4) HTTP comparison pages
Hydrogeochemical variability of the acidic springs in the Rio Tinto headwaters
This research was funded by MICINN grant PID2019-1048126GB-I00.PeƱa de Hierro, located in southwest Spain, encompasses the springs and headwaters for the Rio Tinto River that emerge above normal faults and has been mined for its rich sulfide ore since 2500 BC. The springs are typically characterized by an orange coloration, typical pH of ~2.33, and contain elevated concentrations of heavy metals that are produced by acid rock drainage (ARD). ARD is a natural phenomenon that results from chemolithoautotrophs metabolizing the sulfide ore. Mining has amplified the magnitude of the acidity and concentrations of heavy metals evidenced within sedimentary cores from the Huelva estuary. Acidity, redox state, hydrochemistry and isotopic analyses were examined for the purpose of characterizing the subsurface flows and determining the interconnectivity of the groundwaters. Previous studies have documented the geochemistry of the springs, dating a select few, yet many springs remain uncharacterized. Acidity presented spatial variability throughout the field area, caused by extensive sulfide interactions which generated and modified the pH. Redox exhibited a large range of values due to oxygen diffusivity though the fracture network. The surrounding geology is highly heterogeneous because of intensive deformation during the Variscan and Tertiary periods, and this heterogeneity is shown in the varied aqueous chemistry. Fractionation patterns observed in Ī“2H and Ī“18O values predominantly reflected enrichment by intensive evaporation and depletion in Ī“18O as a result of the proposed sulfatic-water model for Rio Tintoās hydrogeology. The analysis illustrates minimal hydrologic interconnectivity, evidenced by the extensive physical and chemical contrasts within such a small proximity.Publisher PDFPeer reviewe
Aging and decision making: A comparison between neurologically healthy elderly and young individuals
We report the results of experiments on economic decisions with two populations,
one of healthy elderly individuals (average age 82) and one of younger students (average
age 20). We examine confidence, decisions under uncertainty, differences between
willingness to pay and willingness to accept and the theory of mind (strategic thinking).
Our findings indicate that the older adultsā decision behavior is similar to that of young
adults, contrary to the notion that economic decision making is impaired with age.
Choices over lotteries do not reflect the age differences previously reported in the
psychology and biology literature. Moreover, some of the demonstrated decision
behaviors suggest that the elderly individuals are less biased than the younger
individuals.(1)There is a greater prevalence of overconfident behavior in the younger
population. (2) Our results show no significant support for a theory of an endowment
effect in either population. (3) Both populations perform similarly on the beauty contest
task, although there is a modest indication of a higher incidence of confused behavior by
the older
Mental Processes and Strategic Equilibration: An fMRI Study of Selling Strategies in Second Price Auctions
This study is the first to attempt to isolate a relationship between cognitive activity and equilibration to a Nash Equilibrium. Subjects, while undergoing fMRI scans of brain activity, participated in second price auctions against a single competitor following predetermined strategy that was unknown to the subject. For this auction there is a unique strategy that will maximize the subjects' earnings, which is also a Nash equilibrium of the associated game theoretic model of the auction. As is the case with all games, the bidding strategies of subjects participating in second price auctions most often do not reflect the equilibrium bidding strategy at first but with experience, typically exhibit a process of equilibration, or convergence toward the equilibrium. This research is focused on the process of convergence
Bone Marrow Microenvironmental Changes Underlie Reduced RAG-mediated Recombination and B Cell Generation in Aged Mice
During aging, adaptive immunity is severely compromised, due in part to decreased production of B lymphocytes and loss of immunoglobulin (Ig) diversity. However, the molecular mechanisms that underlie age-associated diminished B cell production remain unclear. Using in vivo labeling, we find that this reduction in marrow preāB cells reflects increased attrition during passage from the proāB to preāB cell pool. Analyses of reciprocal bone marrow chimeras reveal that the magnitude and production rates of preāB cells are controlled primarily by microenvironmental factors, rather than intrinsic events. To understand changes in proāB cells that could diminish production of preāB cells, we evaluated rag2 expression and V(D)J recombinase activity in proāB cells at the single cell level. The percentage of proāB cells that express rag2 is reduced in aged mice and is correlated with both a loss of V(D)J recombinase activity in proāB cells and reduced numbers of preāB cells. Reciprocal bone marrow chimeras revealed that the aged microenvironment also determines rag2 expression and recombinase activity in proāB cells. Together, these observations suggest that extrinsic factors in the bone marrow that decline with age are largely responsible for less efficient V(D)J recombination in proāB cells and diminished progression to the preāB cell stage
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