Taken from www.victorianmicroscopeslides.com
Taken from www.victorianmicroscopeslides.com
I am delving into dark currents, the scientific poetry of video. This is what mimesis seeks to screen out: the medium. Or more specifically, the primacy of the pheno-text. I would even call it the accountability of the image. The video image is imagined as immaterial, and yet the material itself is expressive — literally. As Roland Barthes put it, "The 'grain' is the body in the voice as it sings, the hand as it writes, the limb as it performs." (IMAGE/MUSIC/TEXT, p.188)
In physics and in electronic engineering, dark current is the relatively small electric current that flows through photosensitive devices such as a photomultiplier tube, photodiode, or charge-coupled device even when no photons are entering the device. It is referred to as reverse bias leakage current in non-optical devices and is present in all diodes. Physically, dark current is due to the random generation of electrons and holes within the depletion region of the device that are then swept by the high electric field.
The charge generation rate is related to specific crystallographic defects within the depletion region. Dark-current spectroscopy can be used to determine the defects present by monitoring the peaks in the dark current histogram's evolution with temperature.
Dark current is one of the main sources for noise in image sensors such as charge-coupled devices. The pattern of different dark currents can result in a fixed-pattern noise; dark frame subtraction can remove an estimate of the mean fixed pattern, but there still remains a temporal noise, because the dark current itself has a shot noise. (WIKIPEDIA)
The Epley maneuver:
The Brandt-Daroff maneuver:
Vertigo is a disorder of the middle ear, caused by small crystals that have colonized in a sensitive part of the inner ear. These crystals become displaced, causing the dizziness of vertigo. Usually a physician who specializes in dizziness and balance disorders will perform The Epley or Semont maneuver to help settle the displaced crystals. The Semont maneuver is a calculated and rapid moving exercise, performed only by a doctor in the safety of a doctor's office. Brandt-Daroff exercises are similar to the Epley maneuver, but they can be done at home. These exercises can benefit anyone with dizziness, vertigo, imbalance, lightheadedness or faintness. They are safe and easy to perform.
From the October, 2008 issue of Semiconductor International:
The proverb admonishes, “Look to the ant, thou sluggard, consider her ways and be wise.” The same sentiment can be applied to another member of the Insecta class, a green iridescent Brazilian beetle with the unwieldy moniker of Lamprocyphus augustus. Just by doing what comes naturally, this inch-long weevil has accomplished a task that to date has eluded the Hominidae class's best researchers: the evolution of a structure considered as the ideal architecture for the long-sought-after photonic crystal.
To produce ultrafast optical computers, it is first necessary to produce an ideal photonic crystal that will enable exacting manipulation of light. Currently, light in near-infrared and visible wavelengths carries data and communications through fiber-optic cables, but this photonic information must be converted back to electrons before it can be processed by a computer.
“Photonic crystals are a completely new class of optical materials that enable the manipulation of light in non-classic ways,” explained Michael Bartl, assistant professor of chemistry and adjunct professor of physics at the University of Utah (Salt Lake City). “Some colors [wavelengths] of light can pass through such a crystal at various speeds, while others are reflected as if the crystal were acting as a mirror.”
Colored glass models, Unsigned, first half 20th century
Wooden models of twinned feldspar crystals, G.E. Kayser, Berlin, 1834
Wooden models, Unsigned, late 19th century
Wooden models, Unsigned, mid 20th century
Porcelain models, Unsigned [John Joseph Griffin], England, ca. 1841
There are far too many beautiful examples of glass, porcelain and wooden crystal models from the 18th and 19th century to display here — much more information can be found at The Virtual Museum of the History of Mineralogy. These once functional objects have long since been replaced in the teaching of mineralogy by computer models, but their present-day obsolescence only heightens their mysterious and sublime aura. Such interactive sculptures surely must have been seen and relished by the Surrealists, as Taglioni's Jewel Casket by Joseph Cornell reveals. Outside of their scientific context, there is even a prefiguration of minimalist sculpture — an unironic yet non-literal juxtaposition of organic processes and geometric perfection. There is, for me, a fascinating contradiction in the innocence of their toylike size and sentimental presentation given that crystallography — though largely esoteric and academic in its early phases — became the foundation for the most impactful material sciences of chemical and molecular engineering in the twentieth century, as well as the more potentially transfiguring twenty-first century developments in application of topography, virtual three-dimensional modeling systems, rapid prototyping and nanotechnology. The early crystallographic model is the self-anachronistic object par excellance.
The Wieliczka Salt Mine, near the Polish city of Krakow, is a salt mine that has been in continuous operation since the 13th century, and still is producing table salt today. The mine stretches to a depth of 327 meters and is more than 300 km long. In addition to its purpose as a mine, Wieliczka features a oturist route lined with statues of historical and mythical figures (all of them sculptured out of salt by miners), chambers and chapels lined with salt crystal chandeliers, underground lakes, and exhibits showing the history of salt-mining.
The Crystal Cave was accidentally discovered in 2000 by miners working in the silver and lead mine at Naica, Mexico. It lies almost 300 meters (900 feet) below the surface of the Earth and it contains the largest crystals known in the world, by far. The largest crystals are over 11 meters long (36 feet) and weigh 55 tons. The crystals themselves are made of selenite which is crystallized gypsum, the same material used in drywall construction. Except these crystals formed over a span of about half a million years in a hot water solution, saturated with minerals. The temperature inside the cave remained very consistently hot for the entire time the crystals were growing.