Civil Rights
Movements, leaders, victories and the continuing fight for equality.
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Aluminium (the Commonwealth and preferred IUPAC name) or aluminum (North American English) is a chemical element; it has symbol Al and atomic number 13. It has a density lower than other common metals, about one-third that of steel. Aluminium has a great affinity toward oxygen, forming a protective layer of oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, nonmagnetic, and ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the 12th-most abundant element in the universe. The radioactivity of 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it has more polarizing power, and bonds formed by aluminium have a more covalent character. The strong affinity of aluminium for oxygen leads to the common occurrence of its oxides in nature. Aluminium is found on Earth primarily in rocks in the crust, where it is the third-most abundant element after oxygen and silicon, rather than in the mantle, and virtually never as the free metal. It is obtained industrially by mining bauxite, a sedimentary rock rich in aluminium minerals. The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted. The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and the mass production of aluminium led to its extensive use in industry and everyday life. In 1954, aluminium became the most produced non-ferrous metal, surpassing copper. In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan. The standard atomic weight of aluminium is low in comparison with many other metals, giving it the low density responsible for many of its uses. Despite its prevalence in the environment, no living thing is known to metabolize aluminium salts, but aluminium is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of interest, and studies are ongoing.
Use of Free and Open-Source Software (FOSS) in the U.S. Department of Defense is a 2003 report by The MITRE Corporation that documented widespread use of and reliance on free software (termed "FOSS") within the United States Department of Defense (DoD). The report helped end a debate about whether FOSS should be banned from U.S. DoD systems, and helped redirect the discussion towards the current official U.S. DoD policy of treating FOSS and proprietary software as equals.
Free climbing is a form of rock climbing in which the climber can use rock-climbing equipment for their protection, but not as an artificial aid to help them in ascending a climbing route. Free climbing, therefore, cannot use any of the mechanical tools that are widely used in aid climbing to help the climber overcome the obstacles they encounter while ascending a route (e.g., aiders or skyhooks). The development of free climbing was a transformational moment in the history of rock climbing, including the concept and definition of what determined a first free ascent (or FFA) of a climbing route by a climber. Free climbing can be performed in several different rock-climbing formats that vary with the type of climbing protection which the free-climber used. For example, free climbing can be done as lead climbing in either a traditional climbing style (temporary and removable climbing protection) or a sport climbing style (permanently fixed in-situ climbing protection). Free climbing can also be performed as bouldering or as free solo climbing—both of which use no climbing protection whatsoever. Free climbing is sometimes misunderstood as relating only to the formats of free-solo climbing or of solo climbing, which is not correct.
Free and open-source software (FOSS) is software available under a license that gives users the right to use, share, modify, and distribute the software — modified or not — to everyone and provides the means to exercise those rights using the software's source code. FOSS is an inclusive umbrella term encompassing free software and open-source software. The rights guaranteed by FOSS originate from the "Four Essential Freedoms" of The Free Software Definition and the criteria of The Open Source Definition. All FOSS has publicly available source code, but not all source-available software is FOSS. FOSS is the opposite of proprietary software, which is licensed restrictively or has undisclosed source code. The historical precursor to FOSS was the hobbyist and academic public domain software ecosystem of the 1960s to 1980s. Free and open-source operating systems such as Linux distributions and descendants of BSD are widely used, powering millions of servers, desktops, smartphones, and other devices. Free-software licenses and open-source licenses have been adopted by many software packages. Reasons for using FOSS include decreased software costs, increased security against malware, stability, privacy, opportunities for educational usage, and giving users more control over their own hardware. The free software movement and the open-source software movement are online social movements behind widespread production, adoption and promotion of FOSS, with the former preferring to use the equivalent term free/libre and open-source software. FOSS is supported by a loosely associated movement of multiple organizations, foundations, communities and individuals who share basic philosophical perspectives and collaborate practically, but may diverge in detail questions.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.