Civil Rights
Movements, leaders, victories and the continuing fight for equality.
q2K BHP
Black History Portal
THE BHP WIRE —
HIDDEN TRUTHS
What's New!
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.
In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
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
The slice preparation or brain slice is a laboratory technique in electrophysiology that allows the study of neurons from various brain regions in isolation from the rest of the brain, in an ex-vivo condition. Brain tissue is initially sliced via a tissue slicer then immersed in artificial cerebrospinal fluid (aCSF) for stimulation and/or recording.[1] The technique allows for greater experimental control, through elimination of the effects of the rest of the brain on the circuit of interest, careful control of the physiological conditions through perfusion of substrates through the incubation fluid, to precise manipulation of neurotransmitter activity through perfusion of agonists and antagonists. However, the increase in control comes with a decrease in the ease with which the results can be applied to the whole neural system.[2]
Free hand sectioning is a type of preparation techniques where a skilled operator uses razor blade for slicing. The blade is wetted with an isotonic solution before cutting to avoid tissue smudging during cutting. This method has several drawbacks such as sample size limitation and difficult to observe progress. Modern microtome devices such as Compresstome microtomes are used to prepare slices as these devices have less limitations.[3]
When investigating mammalian CNS activity, slice preparation has several advantages and disadvantages when compared to in vivo study. Slice preparation is both faster and cheaper than in vivo preparation, and does not require anaesthesia beyond the initial sacrifice. The removal of the brain tissue from the body removes the mechanical effects of heartbeat and respiration, which allows for extended intracellular recording. The physiological conditions of the sample, such as oxygen and carbon dioxide levels, or pH of the extracellular fluid can be carefully adjusted and maintained. Slice work under a microscope also allows for careful placement of the recording electrode, which would not be possible in the closed in vivo system. Removing the brain tissue means that there is no blood–brain barrier, which allows drugs, neurotransmitters or their modulators, or ions to be perfused throughout the neural tissue. Furthermore, the slice preparation method can also be used as a brain-injury model.[4] Finally, whilst the circuit isolated in a brain slice represents a simplified model of the circuit in situ, it maintains structural connections that are lost in cell cultures, or homogenised tissue.
Slice preparation also has some drawbacks. Most obviously, an isolated slice lacks the usual input and output connections present in the whole brain. Further, the slicing process may itself compromise the tissue. To minimize complications in the slicing process, a more sophisticated tissue slicer may be used such as the Compresstome, a type of vibrating microtome used to maximizes the amount of viable tissue cells. Additionally, slicing of the brain can damage the top and bottom of the section, but beyond that, the process of decapitation and extraction of the brain before the slice is placed in solution may have effects on the tissue which are not yet understood. The slice preparation procedure itself induces a rapid and robust phenotype change in microglia, the consequences of which need to be taken into consideration when interpreting results.[4] During recording, the tissue also "ages", degrading at a faster rate than in the intact animal. Finally, the artificial composition of the bathing solution means that the presence and relative concentrations of the necessary compounds may not be present.[5]
| Concepts | |
|---|---|
| People | |
| Methods | |
| Systems | |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The slice preparation or brain slice is a laboratory technique in electrophysiology that allows the study of neurons from various brain regions in isolation from the rest of the brain, in an ex-vivo condition. Brain tissue is initially sliced via a tissue slicer then immersed in artificial cerebrospinal fluid (aCSF) for stimulation and/or recording. The technique allows for greater experimental control, through elimination of the effects of the rest of the brain on the circuit of interest, careful control of the physiological conditions through perfusion of substrates through the incubation fluid, to precise manipulation of neurotransmitter activity through perfusion of agonists and antagonists. However, the increase in control comes with a decrease in the ease with which the results can be applied to the whole neural system.
An egg slicer is a food preparation utensil used to slice peeled, hard-boiled eggs quickly and evenly. An egg slicer consists of a slotted dish for holding the egg and a hinged plate of wires or blades that can be closed to slice. The wire egg slicer was invented and patented by Willy Abel, a German inventor (1875–1951), in 1912, who also invented the bread cutter. The first egg slicers were produced in Berlin-Lichtenberg. Dutch comedic duo Van Kooten en De Bie created a mock documentary about a Dutch egg slicer factory in 1983. Aside from egg slicer, there is also egg wedger. Egg wedger uses criss-cross wires instead of parallel wires for slicing.
A microtome (from the Greek mikros, meaning "small", and temnein, meaning "to cut") is a cutting tool used to produce extremely thin slices of material known as sections, with the process being termed microsectioning. Important in science, microtomes are used in microscopy for the preparation of samples for observation under transmitted light or electron radiation. Microtomes use steel, glass or diamond blades depending upon the specimen being sliced and the desired thickness of the sections being cut. Steel blades are used to prepare histological sections of animal or plant tissues for light microscopy. Glass knives are used to slice sections for light microscopy and to slice very thin sections for electron microscopy. Industrial grade diamond knives are used to slice hard materials such as bone, teeth and tough plant matter for both light microscopy and for electron microscopy. Gem-quality diamond knives are also used for slicing thin sections for electron microscopy. Microtomy is a method for the preparation of thin sections for materials such as bones, minerals and teeth, and an alternative to electropolishing and ion milling. Microtome sections can be made thin enough to section a human hair across its breadth, with section thickness between 50 nm and 100 μm.
A kitchen utensil is a hand-held, typically small tool that is designed for food-related functions. Food preparation utensils are a specific type of kitchen utensil, designed for use in the preparation of food. Some utensils are both food preparation utensils and eating utensils; for instance some implements of cutlery – especially knives – can be used for both food preparation in a kitchen and as eating utensils when dining (though most types of knives used in kitchens are unsuitable for use on the dining table). In the Western world, utensil invention accelerated in the 19th and 20th centuries. It was fuelled in part by the emergence of technologies such as the kitchen stove and refrigerator, but also by a desire to save time in the kitchen, in response to the demands of modern lifestyles.
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 →Mae Jemison, aboard Space Shuttle Endeavour in 1992.
