Alfvén waves, named after the man who suggested them in 1942, are waves that exist in conductive fluids. Normally they are talked about when it comes to plasmas but they were originally shown to exist in mercury as this too is a conductive liquid that a magnetic field can permeate. The magnetic field acts as the restoring force for the oscillations that make the Alfvén waves exist in the first place. For an ideal Alfvén wave the particles receive no energy as the wave propagates and this is close enough to being true for a significant amount of the time. However, as the oscillations increase in speed, or the wave decreases in size, it can begin to excite the ions through the production of its own electric and magnetic fields. This naturally results in a loss of energy from the wave and is actually one of the most important mechanisms is solar physics for the transfer of energy from electromagnetic waves to the kinetic energy of particles.
Magnetite (Fe3O4) is one of the two common ores of iron, the other being haematite (Fe2O3). Of all minerals that naturally occur on Earth, magnetite is the most magnetic and can become its own permanent magnet. When it does so it is known by the name lodestone which is a word more people will be familiar with. There are many interesting theories about nanoparticles of magnetite such as the fact that it may exist in our brains and provide some people with low level magnetic field sensitivity. Today the paper is not focusing so much on the biological occurrences, or even the possible applications of these particles, but more how they form and what structures they take when they do.
Today’s news leads on very well from yesterday’s as it is likewise looking at the physics of secondary low energy electrons, very specifically the effect of these electrons on water, the main components of most cells. Despite the electrons being relatively low energy, with most not surpassing about 10 eV, some acute damage can still be done and it was found about a decade ago that the damage DNA receives does not necessarily scale with energy of the damaging electrons. In order to understand the exact interaction of electrons with the water in cells many experiments have been carried out to attempt to understand the process of the electrons transferring energy. This study aims to improve on this kind of work by offering a more advanced and specialised model for the water that makes it act in a much more similar way the liquid found in cells. Details about the electron configuration along with bonding and antibonding electrons were imputed. The phonons within the water were only given one standing wave state which represents the limited environments the water would be in within a cell.
When an ion is produced by ionising radiation this is normally considered the end of the story at least from the perspective of the ion. The radiation goes flying off and the ion goes to destroy some DNA or something similar. In reality the situation is a bit more complicated than that. The ion, almost always positive, interacts with the electrons in whatever medium it’s found itself in leading to it losing energy. These interactions result in many electrons, called secondary electrons, gaining the energy to ionise the surroundings. This means that following the path of the primary radiation there is a cloud of secondary ionisations called the track structure as represented on the diagram:
Most of the waves that the average person is used to seeing are those on the surface of a lake. These are mechanical waves and as their restoring force (a characteristic of all waves) is provided by gravity they are often specified as surface gravity waves or just gravity waves. Although these waves are very common there is another type of wave very literally hiding under the surface. Inertial waves are waves that are produced in rotating fluids and their restoring force is provided by the Coriolis effect. They are actually produced in the interior of the fluid and so don’t exist at the surface where we would normally see them. There is one very important group of inertial waves that exist high up in the atmosphere called Rossby waves and it is these that today’s paper is studying.
Good evening everyone and I hope you had a happy mother’s day. Last week I was intending to write the weekly roundup on a particular topic but realising I decided to wait until now to tell it. About 1600 years ago, Hypatia of Alexandria, one of the leading mathematicians and astronomers in Egypt, was murdered. This was the result of a religious and political feud going on between the Jewish and Christian inhabitants of Alexandria at the time which unfortunately ended with her murder at the hands of a group of Christian zealots. There is currently a petition being signed to have the 20th of March, the Monday of this week and the supposed date of her death, become a commemoration festival. Whether this petition succeeds or not I believe it is important to remember Hypatia. Not just because, despite being a women in those times, she was able to become one of the most respected natural philosophers, but because her death also symbolises the end of the classical age and the fact that whenever these massive conflicts between opposing groups get under way, there will always be some people caught in the middle.
Until tomorrow, goodnight.
Gallium nitride (GaN) is one of the most commonly used semiconductors because of its wide and effective bandgap. This bandgap makes it especially effective for applications in optoelectronics and so GaN has been found in light emitting diodes for two decades along with other uses in solar cells and high charge transistors. It was actually a gallium nitride substrate that allowed the production of violet lasers to be achieved, a key step in the ultimate development of a white light diode. The latest focus has been trying to use GaN nanotubes as a method for constructing nanoscale electronics with the goal of high quality sensors, but the applications could far surpass this. The problem is that in gallium nitride, and its related materials like indium nitride (InN), aluminium nitride (AlN), and boron nitride (BN), defects and contaminations in the structure can lead to massive drops in performance and that is what this study’s about.