Advent calendar 2013

24.12.2012

Fascination research - count down the days to December 24 with our advent calendar with a difference! We will open a door for you each day to reveal an image from science.

Mass is mass is mass

Birth of a galaxy cluster

Digital photograph

Digital photograph Max Planck Institute for Physics, Munich
© CERN

The particle physicists from all over the world who work together at the CERN European accelerator centre in Geneva had great cause for celebration: they finally succeeded in detecting the long-sought Higgs particle. According to the Standard Model of particle physics, this particle gives mass to all other elementary particles. Peter Higgs and François Englert predicted its existence as far back as 1964 – and have now been awarded the Nobel Prize in Physics 2013 for their work. However, direct evidence of the Higgs particle cannot be provided; its existence is calculated from the measurements made at the Large Hadron Collider (LHC), the world’s biggest particle accelerator. The image shows a view of the interior of the Hadronic End-Cap Calorimeter in the ATLAS detector at the LHC: this is one of the measuring devices that record the particle tracks that arise when two opposing proton beams are shot at each other in the ring tunnel of the LHC.
Read more here: Higgs or not Higgs?

Thinking in orderly structures

Caught in the act

Diffusion-weighted magnetic resonance imaging (MRI);
depiction via visualisation software Fibernavigator 2

Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig
Ralph Schurade, Alfred Anwander

What is 17 multiplied by 146? Or 111 plus 97? Complex cognitive skills such as calculation wouldn't be possible without complicated connections of neuronal circuits in various brain regions. With the help of diffusion-weighted magnetic resonance imaging (MRI), neuroscientists are able to uncover how these nerve fibre bundles connect different regions of the brain. To this end, the scientists use the natural magnetism of the particles in the brain in order to measure the diffusion movement of water molecules in the tissue. This enables them to draw conclusions on the pathways and signal orientation of the large nerve fibre bundles. The researchers translate the measured diffusion gradients into bright colour patterns, with the colours corresponding to the direction of the fibres (red: left-right; green: front-back; blue: top-bottom).

Metallic liaison

In the sights of the ornithologists

Reflected-light microscope image in polarised light

Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf
Angelika Bobrowski

Making high-quality steel is something of an art. To this effect, materials scientists experiment with different alloys. For example, the combination of iron and chrome increases the tensile strength of the steel and its resistance to corrosion and wear. In order to find the optimum mixing ratio, the researchers vary the chrome content and test the hardness of the material with the help of a Brinell impression measurement system. To do this, they apply an exactly defined test force to the surface of the material, using a carbide ball with a diameter of 2.5 millimetres; the size of the resulting indentation is a measure of the material’s hardness. The image shows the microstructure of a chrome-iron alloy. The circular Brinell indentation can be seen on the bottom right. So-called slip lines arise on the edge of the indentation through plastic deformation.

Cosmic panorama

Colourful cocktail of scents

Visualisation of satellite data

Max Planck Institute for Astrophysics, Garching
Marco Selig

The keyboard of light extends across numerous octaves. It ranges from long-wave radio radiation to the visible range and high-energy gamma photons. This is precisely what was captured here by a telescope on board the Fermi satellite. What’s more, the image is the product of all of the data collected by the US satellite over a period of around four-and-a-half years. It shows the sky with the heart of the Milky Way in the centre. The galactic disk, in which our sun – just one of 200 billion stars – orbits, extends to the left and right. The north galactic pole is on the upper edge of the image and the south galactic pole on the lower edge. The diffuse structures in the image are part of the Milky Way. Numerous point sources are also visible; some of these belong to our solar system, others belong to remote galaxies. Three bright “stars” are particularly noticeable - the Vela pulsar in the middle of the right hand half of the image and the Geminga and Crab Nebula pulsars on the extreme right side of the picture.

An enzyme that warms the climate

Chemistry in slow motion

Electron microscopy image, 3D reconstruction

Max Planck Institute of Biophysics, Frankfurt am Main

Methane is over 20 times stronger in its effect as a greenhouse gas than carbon dioxide. It is formed when certain microbes from the Archaea group of bacteria decompose organic material under the exclusion of air – for example, in rice fields, bogs and cows’ stomachs. The enzyme Frh, a hydrogenase, plays a key role in the process: it splits hydrogen, which can then react with carbon dioxide to form the methane. The Frh protein consists of a total of twelve trimers, each of which has three subunits, here in blue green and purple. It contains several iron-sulphur clusters – shown as yellow structures in the image – and nickel and iron in the active centres, where the reaction takes place. The structure and function of this enzyme are not only of interest to climate researchers: the molecule could provide a model for the development of catalysts for hydrogen production.

Read more here: New insight into biochemical methane production
 

The place to be

The key to art

Scanning electron microscope image, partly coloured

Max Planck Institute for Developmental Biology, Tübingen
Jürgen Berger, Gáspár Jékely

Whether corals, worms or mussels: Many marine invertebrates begin their lives as part of the plankton. This is also the case with the annelid or ragworm Platynereis dumerilii, which has become an important model organism in evolutionary developmental biology in recent years. The larva controls its movement with the help of a prominent, regularly beating belt consisting of thousands of tiny hairs or cilia. But how does it find a place that can offer the adult worm ideal conditions for its rather stationary existence? A simple organ at the head end of the larva, known as the apical organ, plays a crucial role. Neurons located here perceive environmental stimuli and produce a neuropeptide in response, which alters the beat of the cilia. The larvae start to sink, and then crawl along, surveying the sea floor. They can presumably detect food in this way, and thereby find a suitable habitat.

Read more here: The neurobiology of house-hunting at sea

Sugared with silver

View through a kaleidoscope

Scanning electron microscope image

Max Planck Institute of Colloids and Interfaces
Bat El Pinchasik

The Roman god Janus served as godfather to these silicon dioxide microparticles. Like the two-headed deity, these particles have two faces. One half is covered with silver, and the other is not. To produce these Janus particles, the researchers fix silicon balls in a soft film and coat the free side with silver. The metal is then chemically reduced and catalytically active silver particles are formed. When the particles are placed in water, they move: the splitting of the hydrogen peroxide causes tiny oxygen bubbles to form on the silver-coated side which lift and propel the particles. A similar kind of propelling mechanism is also found in the animal kingdom: the violet snail, for example, glides through the oceans with the help of small bubbles.

Annunciation

View of a planetary fossil

Digital photograph: Fresco von Alessandro Allori, Annunciation, 1560/1564,
Florence, SS. Annunziata, Cappella di San Gerolamo
[Photothek: Inv. Nr. 599129, Dig. Nr. fld0003491]

Kunsthistorisches Institut in Florenz – Max Planck Institute

The Florentine painter Alessandro Allori was commissioned to design the chapel of the Montauti family in the city’s Basilica della Santissima Annunziata in 1560. Allori created a fresco cycle with scenes from the life of Christ, including the Annunciation of the birth of Christ to Mary by the Archangel Gabriel as the ceiling image. The angel is shown here appearing to a humble Mary in a room furnished only with a lectern; an open door provides a view of the distant countryside. As a symbol of the angel’s celestial origin, he is presented floating on a cloud; the white lily with seven blossoms in his hand and the white cloth in which Mary is wrapped, refer to her virginity. Viewers of this Annunciation are struck by the angel’s strongly sculptural male form. The muscular depiction is reminiscent of works by Michelangelo, which provided important models for Allori’s work. This image was produced as part of a photographic project carried out by the Photo Library of the Kunsthistorisches Institut in Florenz on the completion of the chapel restoration project in 2010.

Fish eye in focus

Model plant in a starry sky

Fluorescence microscope image

Max Planck Institute of Molecular Cell Biology and Genetics, Dresden
Jaroslav Icha

Although humans and zebra fish appear to have little in common at a first glance, an astonishing number of parallels can be observed in their development and the structure of their organs. For example, the retina of the eyes in both species is structured very similarly. For this reason, the small fish is a popular model organism for studying the development of our visual organ. The image shows a cross-section of the retina of a three-day-old zebrafish embryo. The researchers made different cell types visible using fluorescent proteins. This enables them to trace the way in which the cells rearrange themselves while the initially simple tissue layer develops into a multi-layered structure. Part of the cell skeleton can be seen here in green, and the cell walls of the photoreceptors and the optic nerve, which conveys information to the brain, are bright pink.

Waves in virtual space

Algal powerhouse

Numerical simulation

Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Potsdam-Golm
Numerical simulation: Bruno Giacomazzo, Luciano Rezzolla (AEI)
Scientific visualisation: Ralf Kähler (AEI & Zuse Institute Berlin)

Take half a million earths, compress them into a ball of just 20 kilometres in diameter and make it rotate faster than a kitchen mixer. This is precisely what occurs in a neutron star, the remnant of a massive sun that has exploded during a supernova event. Such star corpses sometimes arise in pairs, in other words they circle around a joint centre of gravity. If they come too close to each other, they melt into a black hole in a matter of milliseconds. This process cannot be observed directly in nature. However, researchers can simulate such events in a virtual universe. The computer simulation provides the solution to Einstein’s equations in the form of columns of numbers. To visualise the processes, these data are transformed into graphics, images and films and then coloured. In this way, a clear image is produced of the disaster, during which “spiral” gravitational waves are also released – witnesses of a cosmic dance of death.

Read more here: The ripples in space-time.

Becoming a cellular jack-of-all-trades

Fly brain branches out in colour

Flourescence microscope image

Max Planck Institute for Molecular Biomedicine, Münster
Guangming Wu

Skin cells, cardiac cells, liver cells - our body cells are specialised to carry out specific tasks. However, under certain circumstances, cells can be reprogrammed in the laboratory into pluripotent stem cells – similar ‘all-rounders’ as embryonic stem cells. A protein called Oct4 is crucial to this process. But Oct4 does not appear to play a major role in early embryonic development: the embryonic node, from which the foetus develops, can also be formed without the Oct4 protein. The images show a normal mouse embryo (left), an embryo without maternal Oct4 (centre) and an embryo that entirely lacks Oct4 (right). The cells of the embryonic node are coloured green, those of the trophoblast, which later become part of the placenta, are bright red. Consequently, nature takes a different route than the stem cell researchers.

Read more here: Two distinct types of reprogramming

Extremely cold and incredibly empty

Turbulence at the flick of a switch

Photograph

Max Planck Institute for Nuclear Physics, Heidelberg
Christian Föhr

Life is difficult for chemical reaction partners in outer space – due to the low temperature and density of mass in the interstellar realm, there are only slim chances of getting together. To gain a better understanding of this special chemistry, researchers use very complex technology to simulate the conditions in space on earth. A new cryogenic storage ring, one of a kind in the world, is currently being constructed in Heidelberg. Even sensitive, highly-charged molecule-ions can be stored for up to several hours and examined in detail in this storage ring, which has a temperature of just 2° above absolute zero and an extremely powerful vacuum with less than one billionth of normal air pressure. The image shows a quadrupole, part of the ion optical elements, which trap the ions to be studied on a defined path. Unlike the usually used magnets, this electrostatic guiding of the ion beam also enables the storage of very large, heavy ions up to biomolecules and clusters. The electrodes of the ion optical elements are gilded to ensure optimal surface quality.

Short-lived beauty at the beach

Law lecture at a medieval university

Photograph

Max Planck Institute for Meteorology and Klimacampus University of Hamburg
Christian Klepp
The cover photograph of our Advent Calendar which shows a large ice cave in Iceland,
was also taken by Christian Klepp.

An impressive spectacle can be seen every day in south Iceland: at the foot of the Vatnajökull glacier, there is a large lagoon, in which numerous glaciers swim. At high tide, sea water flows into the glacial lake via a short river and the glaciers rotate in large circles in the current. At low tide, the water flows away again and sweeps even large glaciers with it to the sea. They are battered in the rough waves, but fragments often remain stranded on the jet black lava beach. The turquoise colour of this 2.5 metre-tall block of ice testifies to its advanced age – the snowflakes that formed the ice fell around 1000 years ago on the plateau of Vatnajökull. The cracks in the ice are traces of the enormous pressure and tension to which it was subjected during its journey through the glacier. These are the weak points at which the glacier will disintegrate in the waves of the next high tide. Researchers from Hamburg study precipitation over the oceans from the tropics to the polar regions. Precipitation is an important component of the climate system.

Owls in the sleep laboratory

Short flashes of light

Photograph

Max Planck Institute for Ornithology, Seewiesen
Fabrizio Sergio

The two baby barn owls shown in the image look very much awake, however, like human babies, they still need a lot of sleep. Owls have the same sleeping pattern as mammals: as babies they spend more time in REM sleep (rapid eye movement) than they do as adults. In the REM sleep phase dreams occur and brain activity is similar to that of the waking state. However, scientists remain in the dark about the function of this sleep phase: because it predominates in early life and then declines, they assume that it plays an important role in brain development. Scientists are also baffled by another rather curious phenomenon relating to owls and sleep: the sleeping behaviour of the barn owls is closely linked with the activity of a gene, which is responsible for black spots on the plumage of the adult bird. The scientists would like to discover how sleep, brain development and pigmentation are linked.

Read more here: Baby owls sleep like baby humans

A delicate balance

Tenants rearrange the furniture

Confocal microscope image

Max Planck Institute for Biology of Ageing, Cologne
Sara A. Wickström, Alexander Meves

Our skin has an astonishing capacity for regeneration and renews itself continuously throughout our lifetime. To do this, new skin cells must form continually from stem cells. It is important, however, that the number of cells remains constant. The delicate balance between cell renewal and differentiation can be thrown out of kilter, and eczema, psoriasis and tumours can arise as a result. The skin’s regeneration capacity also declines with age, a phenomenon that manifests, for example, in poorer wound healing. The factors that influence this balance and the role aging plays are important questions that researchers are investigating with the help of cytological methods, among others. The image shows a section through a mouse skin sample with three hair follicles. The stem cell area was stained red, the precursor cells of the top layer of skin (epidermis) are bright green. The cell nuclei are labelled blue.

Planet in the halo

Planet in the halo

Near-infrared colour composite image

Max Planck Institute for Astronomy, Heidelberg
© NAOJ

These colourful rays with the black circle in the middle are exactly what they appear to be: a star! However, for once, this was not the focus of the astronomers’ interest. Therefore, they covered the star using every technical tool available to them. The residual light generates the star-shaped pattern. The bright spot on the top right of the image only came to light with the help of this trick – concealed behind it lies nothing less than a second Jupiter. This celestial object, which is known as GJ504b and is 60 light years away, is the coldest and probably lowest-mass exoplanet that has been photographed up to now. The image, which was obtained using the Subaru telescope on Hawaii, provides information about physical and chemical state variables like atmospheric characteristics and temperature. The estimation of the exoplanet’s mass is based on models of the planet’s cooling since its formation; most researchers support the estimate of its mass as being around three times that of Jupiter. The distance of GJ 504b from its star is 44 times the average distance of the earth from the sun – around six billion kilometres.

Signposts for nerve cells

Black holes in the virtual laboratory

Fluorescence microscope image

Max Planck Institute of Neurobiology, Martinsried
Falco Hampel, Rüdiger Klein

The cerebral cortex is the site of our thinking, consciousness and personality. Billions of neurons form a dense network here. How this highly complex structure develops remains a mystery in some respects: for example how do the individual cells ‘know’ the direction in which they must send their extensions to connect with the correct partner cells? The FLRT proteins on the cell surface are important signposts. They can split off small elements which act as stop signals for other cells. When a cell recognises the signal, it withdraws its extension and grows in a different direction. This behaviour can also be observed in a cell culture. The directional FLRTs are only present here in the blue areas. Like the guard rails on a motorway, the strips ensure that the growing cell extensions do not go astray.

Between tradition and market forces

Colourful brain waves

Photograph

Max Planck Institute for Social Anthropology, Halle (Saale)
Kirsten Endres

The everyday garb of the Flower Hmong women in the north-western uplands of Vietnam includes a coloured blouse, which is richly embellished with embroidered bands and beaded fringes. In the past, the women worked by hand for months to create the fabrics for their own use. Today, mechanically mass-produced versions from China are available at the market in the border city of Lao Cai. The opening of the border in the 1990s brought flourishing trade to the previously isolated region, and has given a huge boost to the provincial capital. This is reflected, for example, in the expensive cars that are now a common sight of the city’s streetscape. Nevertheless, small markets and street trading also remain prominent. Ethnologists are interested in processes of social change; one of the Research Groups at the Max Planck Institute for Social Anthropology investigates trade relations in northern Vietnam on the border with China.

A great spectacle on an atomic scale

A plasma makes waves

Electron diffraction image

Max Planck Institute for the Structure and Dynamics of Matter, Hamburg
© Lai Chung (Nelson) Liu, University of Toronto

Researchers have long dreamed of being able to see the movements of atoms while matter is transformed from one state into another. To achieve this, ultra-rapid processes must be recorded in dimensions of less than one-millionth of the thickness of a hair. To this end, the scientists shoot electrons at high energy through the material sample. The electrically-charged particles are scattered on the crystal lattice and a characteristic diffraction image forms. The trick lies in the correct interpretation of this often complex spread pattern. Here, the researchers bombarded an organic salt crystal (EDO-TTF) with electrons. The height and colour of the peaks reflect the different intensities of the reflexes. The structure of the material can be identified from their distribution. Many such snapshots and the changes in intensity observed in them combine to produce a film that demonstrates the dynamics of the atoms in the crystal.

A wholehearted perspective

3D printer in action

Light sheet fluorescence microscopy image

Max Planck Institute of Molecular Cell Biology and Genetics, Dresden
Michaela Mickoleit

Congenital heart defects are not an affliction exclusive to humans – they can also affect zebrafish. In order to understand how such defects arise, the small striped animal is a particularly suitable model organism, as the embryonic development of humans and fish is very similar. But due to the very high heart rate of the developing heart – around 120 beats per minute – recording images of the live embryonic heart poses a real challenge. With the help of light sheet fluorescence microscopy and powerful image-processing software, researchers actually manage to produce 3D reconstructions. For this image, however, they immobilised the heart by switching off a protein that plays an important role in cardiac muscle contraction. The blood vessels are shown in red and the cardiac muscle in blue.

Turbulent analysis

A peacock in stone

Computer simulation

Max Planck Institute for Informatics, Saarbrücken
Tino Weinkauf, Holger Theisel (University of Magdeburg)

The flow of liquids or gases plays a very important role in many technical processes, also economically, for example, in the development of vehicles with lower fuel consumption. To describe the characteristics of a flow, researchers analyse the movement of the individual particles. An important feature here is the so-called streak line, which arises from a multitude of particles that are introduced successively into the flow from the same location. This process is easy to research in the laboratory using smoke, which is blown continually from a nozzle and moves with the flow. To date, it has not been very easy to simulate this in a computer-based visualisation. However, thanks to a new mathematical approach, it is now possible to describe streak lines by means of standard differential equations and compute their characteristics much faster. The streak lines in this image were calculated in less than one minute using the new process; it would take over two hours using the classical algorithm.

Gas station in Space

Brain wave

Numerical simulation

Max Planck Institute for Astronomy, Heidelberg
Gregory Stinson, Andrea. V. Macciò

Galaxies need to refuel, too. Especially at the beginning of their existence, huge numbers of new stars form in them – and they need the matter necessary for this. Thus, it would appear that when they formed around ten billion years ago, galaxies like our Milky Way attracted large volumes of cosmic material from gigantic hydrogen reservoirs. This hydrogen has been drifting in the expanses of intergalactic space since the earliest days of the universe. But how does the material enter the galaxies? Simulations carried out on a super computer show cold streams of gaseous matter that flow into a galaxy (centre of image). One of the streams is illuminated from behind by a remote quasar (bottom left). Like the stars in the background, the quasar – a highly luminous young galaxy that produces a lot of energy – was added to the image by hand.

Read more here: A galaxy refuels

The pretty side of tobacco

Oh Christmas tree, Oh Christmas tree

Confocal laser scanning microscopy image, partly superimposed shots

Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm /Sandra Stegemann

A long time ago, chloroplasts, the solar power plants of the plant cell, were independent organisms – until they were taken over by bigger cells. Since then, they have relinquished their independence, but still have their own genetic make-up. To find out whether chloroplast genes can be transferred from one plant to another, scientists mark tobacco plants with different fluorescent dyes: the yellow YFP marks a protein in the cell plasma (centre of image); the bright green GFP only marks the chloroplasts (top left). The latter also emit red autofluorescence. If two tobacco plants – one with yellow fluorescent plasma and the other with green fluorescent chloroplasts – are grafted onto each other, cells that fluoresce in both green and yellow (centre right) arise when the plants have grown together. The genome of the chloroplasts has, therefore, actually migrated into the other plant. Because plants also fuse under natural conditions, this approach enables the study of evolutionary processes and the investigation of new possibilities for plant breeding.

Magical optics

A wandering star

Photograph

Max Planck Institute for the Science of Light, Erlangen
Klaus Mantel, David Ausserhofer

Spherical lenses are widely used in research, for example as front lenses in microscope objectives. A special kind of such lenses are solid immersion lenses (SIL), hemispherical lenses made of material with a particularly high refractive index. These lenses play an important role in many areas of physics, biology and medicine today, as very high spatial resolution can be attained with their help. The image shows an SIL, the surface of which is being measured in a Twyman-Green interferometer for the purpose of quality assessment. The lens consists of gallium phosphide (GaP), a material that is transparent for light of certain wavelengths and has a very high refractive index. By this means, the light focusing required for high-resolution tests can be attained. The SIL in the photograph appears to hover in the air as a sphere; however, this impression is misleading: the hemispherical lens and the objective of the interferometer are reflected in the “object carrier”, a metal mirror, on which the lens is placed.

 
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