4.25 Sulfur, the ocean, and the sun. Sulfur in the atmosphere affects
climate by influencing formation of clouds. The main natural source of sulfur
is dimethyl sulfide (DMS) produced by small organisms in the upper layers of
the oceans. DMS production is in turn influenced by the amount of energy
the upper ocean receives from sunlight. Here are monthly data on solar
radiation dose (SRD, in watts per square meter) and surface DMS
concentration (in nanomolars) for a region in the Mediterranean:13
(a) Make a scatterplot that shows how DMS responds to SRD.
(b) Describe the overall pattern of the data. Find the correlation r between
DMS and SRD. Because SRD changes with the seasons of the year, the
close relationship between SRD and DMS helps explain other seasonal
patterns.
4.37 Does social rejection hurt? We often describe our emotional reaction
to social rejection as “pain.” Does social rejection cause activity in areas of
the brain that are known to be activated by physical pain? If it does, we
really do experience social and physical pain in similar ways. Psychologists
first included and then deliberately excluded individuals from a social
activity while they measured changes in brain activity. After each activity,
the subjects filled out questionnaires that assessed how excluded they felt.
Here are data for 13 subjects:19
The explanatory variable is “social distress” measured by each subject’s
questionnaire score after exclusion relative to the score after inclusion. (So
values greater than 1 show the degree of distress caused by exclusion.) The
response variable is change in activity in a region of the brain that is
activated by physical pain. Discuss what the data show.