Cellular stress replication is a general term covering a wide range of molecular changes that cells undergo in replication to environmental stressors, including extremes of temperature, exposure to toxins, and mechanical damage. Cellular stress replications are primarily mediated through stress proteins. Stress proteins often are further subdivided into two general categories: those that only are activated by stress, or those that are involved both in stress replications and in mundane cellular functioning. A journal is a periodical publication intended to further progress of science, customarily by reporting incipient research. Most journals are highly specialized, albeit some of the oldest journals publish articles, reviews, editorials, short communications, letters, and scientific papers across a wide range of scientific fields. Journals contain articles that peer reviewed, in an endeavour to ascertain that articles meet the journal's standards of quality, and scientific validity.