“Sierra Leone’s Former Child Soldiers: A Longitudinal Study of Risk, Protective Factors, and Mental Health” (2010), by Theresa S. Betancourt, Robert T. Brennan, Julia Rubin-Smith, Garrett M. Fitzmaurice, and Stephen E. GilmanIn 2010, Theresa S. Betancourt, Robert T. Brennan,
Julia Rubin-Smith, Garrett M. Fitzmaurice, and Stephen E. Gliman,
published “Sierra Leone’s Former Child Soldiers: A Longitudinal
Study of Risk, Protective Factors, and Mental Health” in the
Journal
of the American Academy of Child and Adolescent Psychiatry. The
paper describes the results of a longitudinal study of former
Sierra Leone child soldiers that examines how protective and risk
factors affect children’s post-conflict mental health outcomes
over several years of development. Researchers from Harvard
University in Cambridge, Massachusetts, conducted the study in
Equilibrium Density Gradient Centrifugation in Cesium Chloride Solutions Developed by Matthew Meselson and Franklin StahlMatthew Meselson, Franklin Stahl, and Jerome Vinograd, developed cesium chloride, or CsCl, density gradient centrifugation in the 1950s at the
California Institute of Technology, or Caltech, in Pasadena, California. Density gradient centrifugation enables scientists to separate substances based on size, shape, and density. Meselson and Stahl invented a specific type of density gradient centrifugation, called isopycnic centrifugation that used a solution of cesium chloride to separate DNA molecules based on density alone.
David Reimer and
John Money Gender Reassignment Controversy: The John/Joan CaseIn the mid-1960s, psychologist John Money encouraged the
gender reassignment of David Reimer, who was born a biological male
but suffered irreparable damage to his penis as an infant. Born in
1965 as Bruce Reimer, his penis was irreparably damaged during
infancy due to a failed circumcision. After encouragement from
Money, Reimer’s parents decided to raise Reimer as a girl. Reimer
underwent surgery as an infant to construct rudimentary female
genitals, and was given female
hormones during puberty. During
childhood, Reimer was never told he was biologically male and
regularly visited Money, who tracked the progress of his gender
reassignment. Reimer unknowingly acted as an experimental subject in
Pfeffer Cell ApparatusThe
Pfeffer Zelle (
Pfeffer Cell Apparatus), invented by
Wilhelm Pfeffer in 1877, measured the minimum pressure needed to
prevent a pure solvent from passing into a solution across a
semi-permeable membrane, called osmotic pressure. The apparatus
provided Pfeffer with a way to quantitatively measure osmotic
pressure. Pfeffer devised the apparatus in the 1870s at the
University of Basel in Basel, Switzerland, and he described the
Pfeffer Cell Apparatus in his 1877 book
Osmotische
Untersuchungen: Studien Zur Zellmechanik (
Osmotic
Investigations: Studies on Cell Mechanics). Pfeffer relied on
nineteenth century experiments of Moritz Traube in Germany, who
HIP Randomized Breast Cancer Screening Trial (1963–1982)From 1963 to 1982, researchers in New York City, New York, carried
out a randomized trial of mammography screening. Mammography is the use
of X-ray technology to find breast cancer at early stages. The private
insurance company Health Insurance Plan of Greater New York, or HIP,
collaborated with researchers Sam Shapiro, Philip Strax, and Louis Venet
on the trial. The researchers’ goal was to determine whether mammography
screening reduced breast cancer mortality in women. The study included
sixty thousand women aged forty to sixty-four. Half of the women
received two annual breast examinations that involved mammography, a
breast exam, and an interview. The rest of the women were not invited
for annual examinations. After follow up, the researchers found that of
The Jane Collective (1969–1973) The Jane Collective was an underground
organization that provided illegal
abortion services in Chicago, Illinois, from 1969 until abortions became legal in 1973. Formally called the Abortion Counseling Service of Women’s Liberation, the Jane Collective was a member
organization and working group within Chicago Women’s Liberation Union that challenged the Illinois state legislature by providing abortions before they were legal in the US.
"Altruism and the Origin of the Worker Caste" from The Ants (1990), by Bert Hölldobler and Edward Osborne Wilson
In "Altruism and the Origin of the Worker Caste," Bert Hölldobler and Edward Osborne Wilson explore the evolutionary origins of worker ants. "Altruism and the Origin of the Worker Caste" is the fourth chapter of Hölldobler and Wilson's book,
The Ants, which was published by The Belknap Press of
Harvard University in Cambridge, Massachusetts, in 1990. In "Altruism and the Origin of the Worker Caste," Hölldobler and Wilson evaluate various explanations for how a non-reproductive caste of ant evolved. Their investigation into the evolutionary origins of worker ants synthesized research on the reproductive practices of ants to provide an analysis of how sterile groups of organisms persist in a population.
Meselson, Stahl, and the Replication of DNA: A History of "The Most Beautiful <a href="/search?text=Experiment" title="" class="lexicon-term">Experiment</a> in Biology" (2001), by Frederic Lawrence HolmesIn 2001,
Yale University Press published Frederic Lawrence Holmes'
book,
Meselson, Stahl, and the Replication of DNA: A History of "The
Most Beautiful Experiment in Biology" (Replication of DNA), which
chronicles the 1950s debate about how DNA replicates. That experiment
verified that DNA replicates semi-conservatively as originally proposed
by Watson and Crick. Rather than focusing solely on experiments and
findings, Holmes's book presents the investigative processes of
Franklin William Stahl (1929– )Franklin William Stahl studied DNA replication, bacteriophages, and genetic recombination in the US during the mid-twentieth and early twenty-first centuries. With his colleague Matthew Meselson, Stahl performed an experiment called the Meselson-Stahl experiment, which provided evidence for a process called semi-conservative DNA replication. Semi-conservative replication is a process in which each strand of a parental DNA double helix serves as a template for newly replicated daughter strands, so that one parental strand is conserved in every daughter double helix.
In a series of experiments in the late 1970s, Alec J. Jeffreys in the UK and Richard A. Flavell in the Netherlands developed a technique to detect variations in the DNA of different individuals. They compared fragments of DNA from individuals’ beta-globin genes, which produce a protein in hemoglobin. Previously, to identify biological material, scientists focused on proteins rather than on genes. But evidence about proteins enabled scientists only to exclude, but not to identify, individuals as the sources of the biological samples. By 1979, Jeffrey’s experiments on beta-globin genes shifted the analytical approach of scientific identification from proteins to genes to identify an individual’s genetic identity. The ability to match a person to a biological sample developed in the 1980s and impacted many fields including paternity testing, forensics, immigration, and body identification.
