Entries - Entry Category: Science and Technology - Starting with D

DeGray Dam and Lake

DeGray Dam, located about eight miles northwest of Arkadelphia (Clark County), impounds the 13,400-acre DeGray Lake on the Caddo River. It was built by the U.S. Army Corps of Engineers (USACE) for purposes of electricity generation and flood control, as well as establishing a drinking water supply for Arkadelphia, and is the first “pump back capable impoundment” in the Corps’s history. A reregulation dam forms a 400-acre impoundment below the main lake, providing a supply of water that can be pumped back into DeGray Lake during times of drought and used again for hydropower generation and to provide a steady flow of water on the Caddo River. The site where DeGray Dam stands had been considered for a dam since …

Dellinger, Samuel Claudius

Samuel Claudius Dellinger was curator of the University of Arkansas Museum in Fayetteville (Washington County) and head of the Department of Zoology for over thirty years. As curator, he built the museum’s archaeology collection into one of the best in the nation. In Dellinger’s view, the museum was, first and foremost, an educational resource for the people of Arkansas, and he worked to generate interest in it from the university community and the general public. Samuel Dellinger was born on January 14, 1892, in Iron Station (later Lincolntown), North Carolina, to Robert H. and Laura Loftin Dellinger. After graduating from high school, Dellinger attended Trinity College (later Duke University), where he was a varsity wrestler and swimmer. Dellinger earned his …

Derechos, Squall Lines, Downbursts/Microbursts, and “Rogue” Winds

While Arkansas makes national news far more often for its tornadoes, the state suffers its fair share of what are commonly known as straight-line winds. For example, on June 5, 2014, a weather event originating in Colorado crossed northeastern Arkansas, killing two people, derailing a train in Craighead County, and leaving thousands without power. A derecho (pronounced “deh-REY-cho”) is an event that consists of winds that create a swath of damage that extends for more than 240 miles, has minimal wind gusts of at least fifty-eight miles per hour (mph) for most of this swath, and includes multiple hurricane-force (seventy-five mph or greater) gusts. Derechos originate from what are commonly called “bow echoes,” named for their curved radar signature. About …

Diplurans

aka: Two-Pronged Bristletails
The primitive insects known as diplurans belong to the phylum Arthropoda, subphylum Hexapoda, class Insecta and order Diplura. They are considered to have three lineages: the Campodeoidea, Japygoidea, and Projapygoidea. These superfamilies are defined morphologically by three different types of cerci (paired appendages) found across all the dipluran families. There are ten families in this cosmopolitan order distributed from the tropics to the temperate zones. Diplurans belong to one of the four groups of Hexapoda, with other primitive apterygote insects, including springtails (Collembola) and coneheads (Protura). There are about 800 described species, of which around seventy (9%) occur in North America, twelve (2%) in the United Kingdom, and two (0.3%) in Australia. In 2016, species of diplurans were reported from …

Dipteran Parasites

aka: Parasitic Dipterans
aka: flies
aka: mosquitos
aka: gnats
The order Diptera belongs to the Phylum Arthropoda and Class Insecta. The order ranks number two among all insect orders—only behind beetles (Coleoptera)—with about 125,000 described species (there are an estimated 1,000,000 total species), many of which are considered parasitic or serve as vectors for diseases. There are two main groups (suborders): the Nematocera with seven infraorders and Brachycera with six infraorders. Dipterans—including the sixty species of mosquitoes that occur in Arkansas and Missouri—can be irritating to humans and harmful to livestock and other animals. A major repository of voucher specimens of dipterans in Arkansas is the Entomology Arthropod Museum at the University of Arkansas in Fayetteville (Washington County). It houses the largest research and reference collection of insects and …

Dog Heartworms

aka: Dirofilaria immitis
The canine heartworm (Dirofilaria immitis) is a filarial parasite that belongs to the Phylum Nematoda, Class Secertenea, Order Spirurida, and Family Onchocercidae. There are two subgenera: Dirofilaria and Nochtiella. This parasite is often found in wild and domestic canids throughout the world, especially in the United States where it is endemic from the East to the Midwest, the southeastern Atlantic seaboard, and the southern Gulf Coast. Transmission of the parasite occurs throughout the United States (even Alaska) and in the warmer regions of Canada. In the United States, the highest infection rates are found within 241 km (150 mi.) of the coast from Texas northeast to New Jersey, and along the Mississippi River Valley and its major tributaries. The parasite …

Duke, Charles Sumner

A trailblazing African-American architect and engineer, Charles Sumner Duke not only designed unique public structures, but he also fought for housing rights and educational opportunities for African Americans. His powerful legacy continues in the buildings he designed, as well as in the organization he formed to facilitate the development of engineering and technological skills in youth of color. Charles Sumner Duke was born in Selma, Alabama, on July 21, 1879. His father, Jesse Duke, was the editorial writer and publisher for a local newspaper, The Herald. His mother, Willie Black Duke, was from a family of established businessmen. It was a financially secure family, allowing Duke and his siblings to take advantage of opportunities that many others in the black …