Within every cell of our bodies is a chaotic symphony of molecular and chemical interactions that are difficult or impossible to see with the naked eye.  Scientists rely on experimental ’snapshots’ to give them an idea of what’s happening at the microscopic level. Then they work backwards, reconstructing a sequence of events from these rather abstract clues.

The field of biomedical animation helps us to visualize what can never be observed by the naked eye.  Animators  take the scientist’s mental model of events and render out a real-time 3D visual representation. With the advent of cheaper and faster computers, biomedical animators are producing startlingly life-like animations that rival those found in Hollywood movies (often with a soundtrack to match). Below are three beautiful examples that caught my eye.

Which biomedical animations have caught your eye? Post your favorites in the comments.

Also check out:

Scitimes Video: How the Flu Virus Jumps Species (my own attempt at 2D biomedical animation)

Used with permission of the National Media Museum

A study published this week in the journal Nature brings into question the prevailing wisdom about how a country’s development impacts its population growth. Previously, social scientists thought that indicators such as health, standard of living and human capital, collectively called the Human Development Index, could reliably predict negative population growth.

In the past, data showed that wealthier, better educated and healthier countries had lower  fertility rates. This rate is defined as the total number of children the average woman bears through her reproductive years. For example, the US has a Development Index of about 0.9 (one being the highest) and an fertility rate of about 2 children per woman. This is the magic number where  the man and woman who conceived the child are replaced. Whereas for Niger, an undeveloped African country with a Development Index of about 0.3, the fertility rate is 7 children per woman. This means that the average Nigerian couple replace themselves more than 3 times over!

However, the study authors found that once a country’s Development Index surpassed 0.9, that the fertility rate begins to increase. For example,  the US fertility rate is 0.25 higher than it was in 1976 . This increase is true for over 20 other well-developed countries that have passed the 0.9 mark.  For countries currently experiencing population decline this may be of some comfort, as a decline is associated with deflation and the collapse of social welfare systems.

For more on this study, check out Andy Revkin’s New York Times blog post which explores some of the environmental implications  in regards to world population growth. In addition, here is a neat Java Script application developed by Loren Cobb of the University of Colorado, which helps visualize population growth based on different parameters–like fertility rates.

[Visit Science of the Times to view video]

TRANSCRIPT:

NARRATOR:

The flu virus can infect all kinds of animals from ducks to chickens, pigs, humans and even whales.

NARRATOR:

But scientists think that flu viruses in all of these animals, originally came from aquatic birds, like ducks.

DUCK:

Quack!

NARRATOR:

So how can a flu virus jump species, from birds, to other animals and ultimately to humans?

NARRATOR:

To answer this question,we need to look at the structure of the virus and how it survives.

NARRATOR:

Influenza is an RNA virus, meaning that it’s filled with strands of RNA,a genetic material similar to DNA. The outside of the virus is coated in proteins.

NARRATOR:

In order to infect a cell, the virus must dock up and deliver it’s RNA. A protein on the outside of the virus, known as hemagglutinin, sticks to receptors embedded in the cell’s outer membrane.

NARRATOR:

Once inside the cell, the viral RNA goes to work, co-opting the cell’s own molecular machinery in order to replicate itself and create proteins that will form new viruses. These new viruses, known as virions, disperse and infect other cells.

NARRATOR:

Humans CAN contract flu viruses from birds, but this rarely leads to an infection. The receptor proteins in birds and humans are different ENOUGH that the virus can’t easily dock to a cell.

NARRATOR:

However, viral RNA is not static. During replication, errors can accumulate and these can change the hemaglutinin protein just enough. Now the bird virus can infect the cells of other creatures, including humans.

NARRATOR:

But typically, that other creature is the humble pig. A pig’s cells have both the human-type and bird-type receptors. This means that both bird AND human flu viruses can infect a pigs cells. In other words, pigs act as a kind of viral middleman.

NARRATOR:

And it’s no coincidence that most flu pandemics of recent years are thought to have originated in South East Asia, where people often keep pigs and birds in close proximity.

NARRATOR:

What’s more, is that inside of a pig, flu viruses can become more infectious. Cells infected with both bird and human strains of influenza become incubators for new viral strains. The RNA can reshuffle, which could lead to new viruses with the worst traits of the two original strains.

NARRATOR:

Flu vaccines are a defense against viral infection. They stimulate antibodies against the proteins on the virus’ surface. This prevents it from docking and unloading its RNA.

NARRATOR:

But as long as the flu virus survives SOMEWHERE, in pigs for example, it can mutate again, changing its outer proteins and a newly infectious strain is born.