on the average of its own heading plus the headings of its \neighbors." In their paper, Vicsek et. al. provide simulation results which demonstrate that the nearest neighbor rule they are studying can cause all agents to eventually move in the same direction despite the absence of centralized

, on-line groups are becoming increasingly prominent due to the growth of community and social networking sites such as MySpace and LiveJournal. However, the challenge of collecting and analyzing large-scale timeresolved data on social groups and communities has left most basic questions about

This paper considers causal inference and sample selection bias in non-experimental settings in which: (i) few units in the non-experimental comparison group are comparable to the treatment units; and (ii) selecting a subset of comparison units similar to the treatment units is difficult because

are refined to embody these conceptions. Three measures are developed for each concept, one absolute and one relative measure of the ~entra~~t~ ~ of ~os~tio~ls in a network, and one relenting the degree of centralization of the entire network. The implications of these measures for the experimental study

written in Java 1.4.x and Java 1.5.x to identify the distribution of groups used by developers. We use the data from the study to create prediction models that would allow developers to estimate the number of different groups of classes, fields and methods that are expected to be generated for large Java

Anxiety Checklist. A series of analyses was used to reduce the item pool. The resulting Beck Anxiety Inventory (BAI) is a 21-item scale that showed high internal consistency (a =.92) and test-retest reliability over 1 week, r(81) =.75. The BAI discriminated anxious diagnostic groups (panic disorder

Awareness of individual and group activities is critical to successful collaboration and is commonly supported in CSCW systems by active, information generation mecha-nisms separate from the shared workspace. These mechanisms pena~ise information providers, presuppose rel-evance to the recipient

's convergent and discriminant validity. Study 3 uses the inventory to assess coping responses among a group of undergraduates who were attempting to cope with a specific stressful episode. This study also allowed an initial examination of associations between dispositional and situational coping tendencies

Two studies investigated the tendency of people to be unrealistically optimistic about future life events. In Study 1, 258 college students estimated how much their own chances of experiencing 42 events differed from the chances of their classmates. Overall, they rated their own chances

time-course study. mines the input copy number, usually by relating the PCR signal Absolute quantification should be performed in situ-to a standard curve. Relative quantification relates the PCR signal ations where it is necessary to determine the absolute of the target transcript in a treatment group