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sciencenote:
In string theory, as in guitar playing, the string must be stretched under tension in order to become excited. However, the strings in string theory are floating in spacetime, they aren’t tied down to a guitar. Nonetheless, they have tension. The string tension in string theory is denoted by the quantity 1/(2 p a’), where a’ is pronounced “alpha prime”and is equal to the square of the string length scale. If string theory is to be a theory of quantum gravity, then the
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sciencenote:
Sperm Shop
By Roger Wagner, University of Delaware
In mammals, sperm is generated in long, thread-like tubes, called seminiferous tubules (beige). Each tube is lined with an epithelium that contains spermatogonia cells (blue). Over the course of ~64 days, these cells differentiate into mature sperm cells (yellow). The spermatogonia cells divide by mitosis to produce diploid spermatocytes (lavender), which then undergo meiosis to generate two haploid spermatids. Spermatids develop
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sciencenote:
Fatal Contact
By David McDonald and Thomas Hope, Case Western University and Northwestern University
A dendritic cell (left) presents HIV (green) to primary T cells (rigth) in an infectious synapse. HIV is labeled with GFP-Viral Protein R (vpr). Filamentous actin is stained red with phalloidin, and nuclei are stained blue with Dapi. Deconvolved image was captured on a DeltaVision imaging system (API).
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sciencenote:
Rakesh Bhatnagar
University of AlbertaAdvanced Microscopy Facility, Department of Biological SciencesEdmonton, Alberta, Canada
Subject Matter:
Corn stem section
(100x)Technique:
Confocal
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sciencenote:
In 1202, Italian mathematician Leonardo Pisano (also known as Fibonacci, meaning “son of Bonacci”) pondered the question: Given optimal conditions, how many pairs of rabbits can be produced from a single pair of rabbits in one year? This thought experiment dictates that the female rabbits always give birth to pairs, and each pair consists of one male and one female.
Think about it — two newborn rabbits are placed in a fenced-in yard and left to, well, breed like rabbits.
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