The Internet could change the lives of average citizens as much as did the telephone in the early part of the 20th century and television in the 1950s and 1960s. Researchers and social critics are debating whether the Internet is improving or harming participation in community life and social relationships. This research examined the social and psychological impact of the Internet on 169 people in 73 households during their first 1 to 2 years on-line. We used longitudinal data to examine the effects of the Internet on social involvement and psychological well-being. In this sample, the Internet was used extensively for communication. Nonetheless, greater use of the Internet was associated with declines in participants' communication with family members in the household, declines in the size of their social circle, and increases in their depression and loneliness. These findings have implications for research, for public policy and for the design of technology.
AbstracL.Computations can generally be separated into stages, which are distinguish(d fl'nm one aaother by {,iHn,r frequency of executiou or availability of data. Precomtn~hzffo~and)eT~enegred~c~ioninvnlvemovingcnnu)utadon among a co]lectiou of stages so that work is done as early as possib]e (so iess time is required in later steps) and as infrcquent!y as possible (to reduce overall time).We present, by means of examples, several general eransformadon techniques for carrying out precomputation tra.l~sA~rmations. We illustrate the techniques by deriving fragments ef simple compi]ers from interpreters: including an example of I~rotog compilation, but the techniques are applicable in a })road range of circumstances. Our aim is to demcmsvrate how perspicuous accouuts ofprecomputation and frequency reduction can be given for a wide range of applications using a small number of relatively straightiorward techniques.I{elatart by th~ ()i]ice of Navn] R~:s~'arch u~d~.r co~;~ract NO0014-84-1{-0415 and in !The views :111,] conc]usior~s contained in this document are t]Io~e of the a,ldlor:~ m~l should ~of be interpr,.ted as rep~es{'nting tile official policies, Giber expressed or implied, d DARPA or the U.S, Go'¢ernment,Permission Io copy without fee all or part of this ma~eriat is granted provided ~ha~ the copies are not made or distribmcd for direct commercial advamage, ~he ACM copyright no,ice and d-m tide of the publication and its date appear, and no,ice is given that copying is by permissior~ of the Association for Cornpming Machinery. To copy otherwise, or to repuMish, requires a fee and/or specific permission.La this paper we suggest program trm~sformadon tcchniques that can be used to provide explicit and prucise accounts of certain kinds of program improvcnmnfs rdated to these staging opthnizations. A sllrprisingly diwwse eo]h'ction of program structures alld progranlo~];lg t(:(ln/iqlnts ca11 t)e explained in these terms. It is the i)m'pos( , of [his ~,x(,rdse ~o give a hint of this diversity, to demonstrat(, how programs of great complexity can often be
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