mucholderthen:

Illustration
the visible spectrum as part of the electromagnetic spectrum
(Credit:  Abrisa Glass & Coatings, 2005)

X-rays, light, and radio waves are examples of electromagnetic waves.

Light is what we call the part of the electromagnetic spectrum that we can detect with our eyes. The cone photoreceptors in our eyes have evolved so that they are most sensitive at different regions of the visible spectrum. This forms the basis for our sensation of color 

At the blue end of the visible spectrum, the wavelength of light is shorter — about 400 nanometers.

A nanometer is 1 billionth of a meter, or 1 × 10−9 meter.  The abbreviation for nanometer is ‘nm’.

At the red end of the spectrum, the wavelength of light is longer — about 700 nm.

Cone photoreceptors have evolved into three different types. Each one is most sensitive to a different region of the visible spectrum. One type responds best to shorter wavelengths; another responds best to wavelengths towards the middle of the spectrum; and the third type responds best to longer wavelengths.

The different cone photoreceptors are not sharply tuned to a particular color, however. So a short-wavelength cone photoreceptor can still respond to longer-wavelength light that falls on it. It is more likely to respond to shorter wavelength light, but it is still possible for it to respond to mid- and long-wavelength light.

The signals from the three different types of cones are combined in the retina and in the brain, eventually giving rise to the sensation of color.

[ via Mixing Light ]

amolecularmatter:

The cerebral vasculature is a complex network that allows only 18% of the total blood volume of the body through the delicate tissues of the brain. This allows the transport of oxygen and nutrients that are essential to brain function. In the wide field, plane-projection confocal image above, the superficial cerebral vasculature of a mouse - specifically the actin, α-N-acetylgalactosamine residues, and DNA in cell nuclei - are labeled in situ.

Image Source: The Cell Picture Show.

fuckyeahmolecularbiology:

Mycoplasma genitalium, the owner of the title ‘world’s smallest genome of any living organism’ at a measly 525 genes, made headlines this week as it was replicated by a computer.

Researchers at Stanford University created a computer model of the organism, basing it on over 900 scientific papers. The overall tally of experimentally determined parameters in the model was 1,900; those were split into 28 algorithms, which stepped in for certain biological processes.

Scientists hope that one day biologists can test hypotheses that wouldn’t normally be possible in the real world and expand the digitising technology used on the bacterium into larger creatures. But there’s a whole lot of genes between Mycoplasma genitalium and anything else. 

The paper was originally published in the journal Cell.

Image is of Mycoplasma genitalium.

fuckyeahmolecularbiology:

Connect the Dots?

This computer model shows the connectivity of the 10,000 neurons and 30 million connections that make up a single neocortical column (the basic building block of the cortex). The different colours correspond to different levels of electrical activity.

The image comes as part of a project that began in 2005 to create a computer model of our entire brain, so neuroscience research can be carried out in silico. The project was originally scheduled for completion in 10 years - do you think we’ll see a whole-brain model by 2015?

fuckyeahmolecularbiology:

Coloured x-ray image of a healthy human stomach.

Image Credit: Science Photo Library.

fuckyeahmolecularbiology:

Scientists at the University of California - Berkeley are revolutionising the way we look at the growth and development of neurons as they form connections with each other to allow our brains to process information. They’ve developed the next best thing to cracking open a skull and peering inside at the brain: A three-dimensional, artificial neural network, constructed with tiny beads. 

Ehud Isacoff, a biophysicist with a dual appointment at Berkeley Lab’s Physical Biosciences and Materials Science division and UC Berkeley’s Department of Molecular and Cell Biology, developed the idea (along with Sophie Pautot and Claire Wyart, both of the Department of Molecular and Cell Biology), because he believes the more realistic the method of studying neural networks, the better our understanding of the brain. “The brain is a multilayered structure, with billions of neurons interconnected in complicated ways,” he reminds us. “Some neurons have 100,000 connections.”

The scientists grew neurons on beads measuring several dozen microns in diameter. These beads assemble themselves into hexagonal sheets, which can be layered on top of each other - a bit like a stack of pancakes - to produce a three-dimensional scaffolding. This scaffolding allows the observation of neuronal growth just as it would occur in the brain: Scientists can watch neurons grow, connect, and communicate with other neurons in all directions. This technique is a dramatic improvement over current lab-based methods of studying neural networks, in which neurons are grown on two dimensional plates - providing a very crude approximation of the actual network structure forming in our three-dimensional brains.

“Our 3D neural network will help us understand how connectivity emerges when neurons grow, and how these connections change over time,” said Isacoff.

In fact, being able to create a 3D neural network at all is an exceptional feat. Previous attempts at growing a three-dimensional neural network have been wildly unsuccessful, mostly because neurons are very finicky - they’ll die if they’re ripped from their surface and stacked atop another neuron, or they’ll just settle back into the surface. Although the two-dimensional models have increased scientists’ understanding of how neurons reach out and connect with each other, Isacoff and his colleagues realised a better model was needed - simply because the brain is a three-dimensional structure. “We knew that neurons grow on a flat surface,” said Isacoff. “So we thought we could trick them and grow them on a spherical bead that appears flat to a neuron, just like Earth appears flat to us.”

The finicky neurons obliged, and grew on the tiny beads, which were then placed in solution to order themselves into a highly structured, two-dimensional array. These arrays of beads were then stacked on top of each other, forming the three-dimensional scaffolding that allows neurons to connect with each other in three dimensions. Fluorescence microscopy imaging of the structure revealed the development of a three-dimensional web of neurons, as densely packed as neural networks in the brain.

“Of course, the brain is much more complicated, but this is a start,” said Isacoff.

If the complexity of the brain can be mirrored in an easy-to-develop system, we could gain fundamental insights into how neural networks enable phenomena of everyday life: Seeing, hearing, kicking a football, or reading this blog. Such a system could be used to gauge the effectiveness of drug therapies that target neurodegenerative diseases like Alzheimer’s and Parkinson’s. It could also help design computer processor architectures that mimic the brain’s ability to optimise neural networks as new skills are learned.

The full paper, entitled “Colloid-guided assembly of oriented 3D neural networks”, can be found here. 

The image above shows a computer simulation of their results from their paper, originally published in Nature.

valuablelesson:

6^th Prize - Thomas J. Deerinck

National Center for Microscopy & Imaging Research - University of California - San Diego - La Jolla, California, USA

Specimen: Rat retina astrocytes and blood vessels (160x)

Technique: Fluorescence and Confocal

Astrocytes (yellow) are glial cells in the brain and spinal cord. They are so named for their “star” shape. They are the most abundant types of cell in their cell and give it its physical structure. Among other biochemical and metabolic processes, they are associated with neural synapses that help the brain communicate with itself, and other parts of the body.

(The red and blue stains are blood vessels that supply the area with oxygen and neutrients.)

(via valuablescience)

bioguru:

X-ray done with an injection of radio-opaque dye to show the carotid artery and other major blood vessels of the head.

geneticist:

What healing wound looks like on a microscopic level (via)

(via physicsmajor)

Ghosts ‘All in the Mind’

Ghosts are the mind’s way of interpreting how the body reacts to certain surroundings, say UK psychologists.

A chill in the air, low-light conditions and even magnetic fields may trigger feelings that “a presence” is in a room - but that is all they are, feelings.

This explanation of ghosts is the result of a large study in which researchers led hundreds of volunteers around two of the UK’s supposedly most haunted locations - Hampton Court Palace, England, and the South Bridge Vaults in Edinburgh, Scotland.

Dr Richard Wiseman, of the University of Hertfordshire, and his colleagues say their work has thrown up some interesting data to suggest why so many people can be spooked in the same building but provides no evidence that ghosts are real.

Clustered experiences

In Hampton Court - alleged to contain the ghost of the executed Catherine Howard, 5th wife of Henry VIII - the volunteers were asked to face their fear. They had to record any unusual experiences, such as hearing footsteps, feeling cold or a presence in the room, as well as marking the location and intensity of the experience on a floor plan. Before this, candidates were also asked to reveal any prior knowledge of hauntings at the site. The researchers then examined the distribution of unusual experiences.

In a “normal” setting, you would expect the ghostly encounters to be evenly spaced, but in classic haunting, they would be clustered around certain places. The results were striking: participants did record a higher number of unusual experiences in the most classically haunted places of Hampton Court, areas such as the Georgian rooms and the Haunted Gallery.

Sensitive people

Making detailed measurements at each place, such as temperature, light intensity and room space, Dr Wiseman thinks that people are responding unconsciously to environmental cues and the general “spookiness” of their surroundings. He cites examples of mediums successfully indicating haunted areas of buildings with no prior knowledge of them.

Spiritualists interpret this as evidence that the ghosts are there, but another explanation is that the mediums are simply more sensitive to the environmental cues that result in haunted feelings - not sensitivity to the ghosts themselves.

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(via ikenbot)