Science

Displaying 31 - 40 of 479 items.

Experiments on the Reproductive Costs of a Pure Capital Breeder, the Children’s Python (Antaresia childreni) (2013), by Olivier Lourdais, Sophie Lorioux, and Dale F. DeNardo

By Brittany Kaminsky

In 2013, Olivier Lourdais, Sophie Lorioux, and Dale DeNardo conducted a study on the impact of the reproductive effort on the muscle size and the constriction strength of female Children’s pythons. Children’s pythons are pure capital breeders, meaning that they do not eat during vitellogenesis, a process in which egg-laying or oviparous species allocate bodily resources including fat, water, and protein to follicles in the ovary that develop into eggs.

Format: Articles

Subject: Experiments

“Of Pregnancy and Progeny” (1980), by Norbert Freinkel

By Blaise Castagnetti

Norbert Freinkel’s lecture Of Pregnancy and Progeny was published by the American Diabetes Association’s journal Diabetes in December of 1980. In the lecture, Freinkel argued that pregnancy changes the way that the female body breaks down and uses food. Through experiments that involved pregnant women as well as infants, Freinkel established the body’s maternal metabolism and how it affects both the mother and the infant. Freinkel’s main focus of research in the latter part of his life was diabetes, specifically in pregnant women.

Format: Articles

Subject: Publications

The Debate over DNA Replication Before the Meselson-Stahl Experiment (1953–1957)

By Victoria Hernandez

Between 1953 and 1957, before the Meselson-Stahl experiment verified semi-conservative replication of DNA, scientists debated how DNA replicated. In 1953, James Watson and Francis Crick proposed that DNA was composed of two helical strands that wound together in a coil. Their model suggested a replication mechanism, later termed semi-conservative replication, in which parental DNA strands separated and served as templates for the replication of new daughter strands.

Format: Articles

Subject: Theories

"RNA-Guided Human Genome Engineering via Cas 9" (2013), by Prashant Mali, Luhan Yang, Kevin M. Esvelt, John Aach, Marc Guell, James E. DiCarlo, Julie E. Norville, and George M. Church

By Meilin Zhu

In 2013, George Church and his colleagues at Harvard University in Cambridge, Massachusetts published RNA-Guided Human Genome Engineering via Cas 9, in which they detailed their use of RNA-guided Cas 9 to genetically modify genes in human cells. Researchers use RNA-guided Cas 9 technology to modify the genetic information of organisms, DNA, by targeting specific sequences of DNA and subsequently replacing those targeted sequences with different DNA sequences. Church and his team used RNA-guided Cas 9 technology to edit the genetic information in human cells.

Format: Articles

Subject: Publications

Ponseti's Treatment for Congenital Clubfoot (1963)

By Katherine Gandee

In 1963, Ignacio Ponseti and Eugene Smoley experimentally determined an effective and minimally invasive method of treating congenital clubfoot. Congenital clubfoot is a disorder in which a newborn’s foot is rigidly turned inwards and upwards. During the early 1960s, orthopedists often relied on invasive surgical procedures to treat clubfoot.

Format: Articles

Subject: Experiments

Roger Sperry’s Split Brain Experiments (1959–1968)

By Dina A. Lienhard

In the 1950s and 1960s, Roger Sperry performed experiments on cats, monkeys, and humans to study functional differences between the two hemispheres of the brain in the United States. To do so he studied the corpus callosum, which is a large bundle of neurons that connects the two hemispheres of the brain. Sperry severed the corpus callosum in cats and monkeys to study the function of each side of the brain. He found that if hemispheres were not connected, they functioned independently of one another, which he called a split-brain.

Format: Articles

Subject: Experiments

Christopher Polge and Lionel Edward Aston Rowson’s Experiments on the Freezing of Bull Spermatozoa (1950–1952)

By Renee Bailey

In 1952, researchers Christopher Polge and Lionel Edward Aston Rowson, who worked at the Animal Research Center in Cambridge, England, detailed several experiments on protocols for freezing bull semen for use in the artificial insemination of cows. Freezing sperm extends the life of a viable sperm sample and allows it to be used at later times, such as in artificial insemination. The researchers examined the effects of freezing conditions on bull sperm and how well they produce fertilized embryos once thawed.

Format: Articles

Subject: Experiments

“The History of Twins, As a Criterion of the Relative Powers of Nature and Nurture” (1875), by Francis Galton

By Mudhaffar Bahjat

In the article “The History of Twins, As a Criterion of the Relative Powers of Nature and Nurture,” Francis Galton describes his study of twins. Published in 1875 in Fraser’s Magazine in London, England, the article lays out Galton’s use of twins to examine and distinguish between the characteristics people have at birth and the characteristics they receive from the circumstances of life and experience. Galton calls those factors nature and nurture. Based on his study, Galton concluded that nature has a larger effect than nurture on development.

Format: Articles

Subject: Publications

Equilibrium Density Gradient Centrifugation in Cesium Chloride Solutions Developed by Matthew Meselson and Franklin Stahl

By Victoria Hernandez

Matthew 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.

Format: Articles

Subject: Technologies

What Every Girl Should Know (1916), by Margaret Sanger

By Lakshmeeramya Malladi

What Every Girl Should Know was published in 1916 in New York City, New York, as a compilation of articles written by Margaret Sanger from 1912 to 1913. The original articles appeared in the newspaper New York Call, under the tile “What Every Girl Should Know.” The articles, which are organized into chapters and individual parts in the book, describe sex education, human reproduction, and sexually transmitted infections.

Format: Articles

Subject: Publications