Past trauma and future choices: Differences in discounting in low-income, urban African Americans

AbstractBackgroundExposure to traumatic events is surprisingly common, yet little is known about its effect on decision making beyond the fact that those with post-traumatic stress disorder are more likely to have substance-abuse problems. We examined the effects of exposure to severe trauma on decision making in low-income, urban African Americans, a group especially likely to have had such traumatic experiences.MethodParticipants completed three decision-making tasks that assessed the subjective value of delayed monetary rewards and payments and of probabilistic rewards. Trauma-exposed cases and controls were propensity-matched on demographic measures, treatment for psychological problems, and substance dependence.ResultsTrauma-exposed cases discounted the value of delayed rewards and delayed payments, but not probabilistic rewards, more steeply than controls. Surprisingly, given previous findings that suggested women are more affected by trauma when female and male participants’ data were analyzed separately, only the male cases showed steeper delay discounting. Compared with nonalcoholic males who were not exposed to trauma, both severe trauma and alcohol-dependence produced significantly steeper discounting of delayed rewards.ConclusionsThe current study shows that exposure to severe trauma selectively affects fundamental decision-making processes. Only males were affected, and effects were observed only on discounting delayed outcomes (i.e. intertemporal choice) and not on discounting probabilistic outcomes (i.e. risky choice). These findings are the first to show significant differences in the effects of trauma on men's and women's decision making, and the selectivity of these effects has potentially important implications for treatment and also provides clues as to underlying mechanisms.</jats:sec

Dialogues with a talking face for web-based services and transactions

In this paper we discuss our research on interactions in a virtual theatre that has been built using VRML and therefore can be accessed through Web pages. In\ud the virtual environment we employ several agents. The virtual theatre allows navigation input through keyboard and mouse, but there is also a navigation\ud agent which listens to typed input and spoken commands. Feedback of the system is given using speech synthesis. We also have an information agent which allows a natural language dialogue with the system where the input is keyboard-driven and the output is both with tables as with template driven natural language generation. In development are several talking faces for the different agents in the virtual world. At this moment an avatar with a cartoon-like talking face driven by a text-to-speech synthesizer can provide users with information about performances in the theatre

The formation of higher-order hierarchical systems in star clusters

We simulate open clusters containing up to 182 stars initially in the form of singles, binaries and triples. Due to the high interaction rate a large number of stable quadruples, quintuples, sextuples, and higher-order hierarchies form during the course of the simulations. For our choice of initial conditions, the formation rate of quadruple systems after about 2 Myr is roughly constant with time at $\sim 0.008$ per cluster per Myr. The formation rate of quintuple and sextuple systems are about half and one quarter, respectively, of the quadruple formation rate, and both rates are also approximately constant with time. We present reaction channels and relative probabilities for the formation of persistent systems containing up to six stars. The reaction networks for the formation and destruction of quintuple and sextuple systems can become quite complicated, although the branching ratios remain largely unchanged during the course of the cluster evolution. The total number of quadruples is about a factor of three smaller than observed in the solar neighbourhood.Comment: Accepted for publication in MNRA

Constitutive expression of the pre-TCR enables development of mature T cells

Expression and signalling through the pre-TCR and the TCRαβ resemble two critical checkpoints during T cell development. We investigated to which extent a pre-TCR can functionally replace mature TCRα chains during T cell development. For this purpose, transgenic mice were generated expressing the pre-TCRα (pTα) under the transcriptional control of TCRβ regulatory elements. We report here on the interesting finding that constitutive pTα expression allows complete T cell maturation. The pre-TCR complex permits a subset of β-selected thymocytes to mature in the absence of TCRα into peripheral T cells (βT cells) comprising up to 10% of all lymphocytes. Lymphopenia-driven proliferation of these βT cells is similar to that of conventional αβT cells. Furthermore, βT cells proliferated and acquired effector function upon stimulation with allogeneic MH