Magnetic Resonance Imaging (MRI)


my brains - let me show you themA few days ago I received a request from a reader (Thanks Paulo Zan) for information about magnetic resonance. The request did not specify more than that so I took the liberty of deciding that perhaps the request was due to coming across the term before and as such it is quite possible that a lot of us would have heard of magnetic resonance in the context of MRI scans.

Well, an MRI scan stands for “Magnetic Resonance Imaging” Scan and it is a widely-used technique to obtain images of the brain. The full name of the imaging technique is actually nuclear magnetic resonance imaging but it seems that the first word in that mouthful is sometimes avoided as it may have negative connotations for some. Other names include MRT or magnetic resonance tomography. MRI scanners use strong magnetic fields and radio waves to form images of the body.

As I mentioned above, the full name should include the word nuclear because the physical phenomenon exploited by the scanner is actually the absorption and emission of electromagnetic radiation by nuclei in a strong magnetic field. The absorption and emission of energy related to the frequency of the radiation in question and depending on the properties of the atoms, certain frequencies cause larger oscillations.Those frequencies are called resonance frequencies. An important feature of the phenomenon is that the resonance frequency of a particular substance is directly proportional to the strength of the applied magnetic field. In an MRI scanner it is this property the one that enables the imaging: if a sample is subjected to a non-uniform magnetic field then the resonance frequencies of the nuclei that make up the sample depend on where in the field they are located. The resolution of the images obtained depend on the  magnitude of magnetic field gradient and this strong fields are required. In a lot of scanners the detectors pick up radio signals emitted by excited hydrogen atoms in the body (remember that water is 2 parts hydrogen and 1 part oxygen). Due to the use of large magnets in the machines, the patients are required not to carry out metallic objects while in the same room as the scanner.

Positron Emission Tomography – Sci-advent – Day 14


positron emmision tomographyOne may think that anti-matter features only in theoretical physics textbooks or in sci-fi devices, nonetheless it is very much in current use. Positrons are the anti-particle of electrons and their existence was proposed theoretically by Paul Dirac in 1928 and they were observed experimentally a year later. Nowadays positrons have a number of applications, including medical imaging.

Positron Emission Tomography (PET) is a three-dimensional imaging technique that works by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide introduced into the body. The radioactive tracer is usually injected into the subject, once inside the body it undergoes positron emission decay and it emits a positron. The positron travels in tissue for a short distance, losing kinetic energy until it is able to interact with an electron. The positron-electron interaction annihilates the pair generating gamma rays which are detected by the scanner.  Finally the images are built with the aid of computers.


Large Hadron Collider – Sci-advent – Day 5



The Large Hadron Collider (LHC) is the world’s largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN). It has become a prominent facility due to the work that is being carried there to prove or disprove the existence of the Higgs boson and of the large family of new particles predicted by supersymmetric theories.

The LHC was built in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories. It lies in a tunnel 27 kilometres in circumference, as deep as 175 metres (574 ft) beneath the Franco-Swiss border near Geneva, Switzerland.


原発くん – Nuclear Boy

Kazuhiko Yatani created a cartoon character called 原発くん(げんぱつくん)aka Nuclear Boy to explain to his kid the Fukushima nuclear power plant situation. This has quickly turned into an animation that has been doing the rounds in some reports to try to explain the situation.  The explanation is not technical, but it tries to put the situation in a context that young kids can understand…

It stars Genpatsu-kun (Genpatsu is slang for a nuclear power plant, and -kun is a suffix used to address young boys), who has a bad stomach ache. Other characters inlcude  Three Mile Island in America, and Chernobyl-chan (-chan is a suffix used for kids of both genders).

What do you think? Is this helpful information? Or not?

Here is the original:

The Large Hadron Collider – Quantum Tunnel Podcast

Large Hadron Collider tunnel and dipole magnets.
Image via Wikipedia

You can download this podcast in iTunesFeedburner.

The Large Hadron Collider is located 300 feet underneath the French-Swiss border outside Geneva and is the world’s biggest and most expensive particle accelerator. It is designed to accelerate  protons to energies of 7 trillion electron volts and then smash them together to recreate the conditions that last prevailed when the universe was less than a trillionth of a second old.

The collider started smashing particles on March 30th, 2010, after 16 years and $10 billion. The new hadron collider will take physics into a realm of energy and time where the current reigning theories simply do not apply, corresponding to an era when cosmologists think that the universe was still differentiating itself, evolving from a primordial blandness and endless potential into the forces and particles that constitute modern reality.

One prime target is a particle called the Higgs boson that is thought to endow other particles with mass, according to the reigning theory of particle physics, known as the Standard Model.

The LHC is part of CERN, which born amid vineyards and farmland in the countryside outside Geneva in 1954 out of the rubble of postwar Europe. It had a twofold mission of rebuilding European science and of having European countries work together. Today, it has 20 countries as members. It was here that the World Wide Web was born in the early 1990s. The lab came into its own scientifically in the early 80s, when Carlo Rubbia and Simon van der Meer won the Nobel Prize by colliding protons and antiprotons there to produce the particles known as the W and Z bosons, which are responsible for the so-called weak nuclear force that causes some radioactive decays.

Bosons are quanta that, according to the rules of quantum mechanics transmit forces as they are tossed back and forth in a sort of game of catch between matter particles. The W’s and Z’s are closely related to photons, which transmit electromagnetic forces, or light.

The innings of the collider are some 1,232 electromagnets, weighing in at 35 tons apiece, strung together like an endless train stretching around the gentle curve of the CERN tunnel. In order to bend 7-trillion-electron-volt protons around in such a tight circle these magnets have to produce magnetic fields of 8.36 Tesla, more than 100,000 times the Earth’s field, requiring in turn a current of 13,000 amperes through the magnet’s coils. To make this possible the entire ring is bathed in 128 tons of liquid helium to keep it cooled to 1.9 degrees Kelvin, at which temperature the niobium-titanium cables are superconducting and pass the current without resistance.

Running through the core of this train, surrounded by magnets and cold, are two vacuum pipes, one for protons going clockwise, the other counterclockwise. Traveling in tight bunches along the twin beams, the protons will cross each other at four points around the ring, 30 million times a second. During each of these violent crossings, physicists expect that about 20 protons, or the parts thereof – quarks or gluons – will actually collide and spit fire.

Two of the detectors are specialized. One, called Alice, is designed to study a sort of primordial fluid, called a quark-gluon plasma, that is created when the collider smashes together lead nuclei. The other, LHCb, will hunt for subtle differences in matter and antimatter that could help explain how the universe, which was presumably born with equal amounts of both, came to be dominated by matter.

The other two, known as Atlas and the Compact Muon Solenoid, or C.M.S. for short, are the designated rival workhorses of the collider, designed expressly to capture and measure every last spray of particle and spark of energy from the proton collisions.


Key breast cancer driver found

Cancer experts have identified a gene which can cause a particularly aggressive form of breast cancer to develop. The name given to this new oncogene is ZNF703 and it is overactive in one of 12 breast cancers. Scientists working for Cancer Research UK carried out the research and they mention that the gene was “prime candidate” for the development of new breast cancer drugs. The study was published in the EMBO Molecular Medicine Journal.

Physicists reverse the laser

We are very familiar with laser light, and as such it would seem very odd to thing about a laser that sucks in a bright beam rather than emitting it. However, scientists from Yale have recently reported in Science the development of a device that converts laser beams into heat.

Cao and co-workers uses a 110-micrometre silicon wafer and a tunable infraread laser in their experiments. They split the laser beam into two and shine it into both sides of the silicon wafer. The front and back of the silicon slice act as mirrors and the silicon in between would be similar to the medium inside a laser cavity. By tuning the frequency of the incoming laser beam as well as other properties, the photons are trapped between the surfaces of the silicon. As the photons bounce back and forth, the silicon absorbs them until all photons are sucked up by the device and converted into heat.

Smelling quantum vibrations

It has been widely believed that the different shapes of molecules provide the clues that our brain registers as smells. However, it has recently been reported that some fruit flies can distinguish between two molecules with identical shapes, providing the first experimental evidence to support a controversial theory that the sense of smell can operate by detecting molecular vibrations.

Efthimios Skoulakis of the Alexander Fleming Biomedical Sciences Research Center in Vari, Greece, carried out the experiments on fruit flies. The team initially placed fruit flies in a simple maze that let them choose between two arms, one containing a fragrant chemical such as acetophenone, a common perfume ingredient, the other containing a deuterated version. If the flies were sensing odours using shape alone, they should not be able to tell the difference between the two. In fact, the researchers found that flies preferred ordinary acetophenone.

Brazilian dam project blocked

In the previous episode we reported on the approval of the construction of a controversial dam in the Amazon, the Belo Horizonte hydroelectric plant, the third largest plant of it’s kind in the world. The plans have now been suspended by a Brazilian judge over environmental concerns.

Judge Ronaldo Desterro halted the plans for the construction because environmental requirements have not been met, also, the national development bank has been prohibited from financing the project.

Science Communication Conference in London

The British Science Association has recently announced its annual two-day Science Communication Conference. The event aims to address some of the key issues facing science communicators in the UK. In order to do that, the conference brings together people involved in public engagement with a range of backgrounds including scientists, charities, universities, press offices and policymakers.
The event will take place on the 25th and 26th of May at King’s Place in King’s Cross in London.  Registration opened on February 14 and will close on May 13th. For more information please visit their website.