In 1895 Willhelm Roentgen discovered a type of light that was not only invisible but appeared to pass straight through materials as if they weren’t there. The demonstration of this was the now famous image of the hand of Roentgen’s wife.
This new type of radiation was dubbed “x-rays” and the name stuck. Almost 120 years later, x-rays are still used every day for the diagnosis of a huge range of diseases and also for the treatment of cancer in what is today referred to as radiation therapy. It’s commonly referred to as radiotherapy but this was thought to be confusing as it has nothing to do with radio waves!
Assorted light bulbs, coloured X-ray. Credit: Light: Beyond the Bulb.
Today in developing countries there is still lack of access to basic needs such as electricity. Thus, it is important to teach children how to generate light in a sustainable way, which can benefit the improvement of their living conditions and make an impact on their communities.
The project started in Kenya. The idea was to provide children with safe electricity. Most of them still use kerosene lamps for studying during the night. Such lamps are toxic and highly threatening for their lives and families. Thanks to the support of Siemens Stiftung, the project has now equipped several schools in Africa and South America, among them, one in Peru, with a 10-Watt Solar Light System, a recharging station, and LED lights. Now children learn how to use solar cells and build their own lights.
Students from the school “Fundación Niños del Arco Iris” building the solar system. Credit: Fundación Niños del Arco Iris.
Welcome to the lighting revolution
In lighting applications, the adoption of light-emitting diodes (LEDs) and organic LEDs promises to reduce lighting energy use dramatically over the next few decades. There is an equally marvellous scientific revolution in biology and psychology. In 2002, we learned conclusively that there is a class of photoreceptive cells in the retina, the intrinsically photoreceptive retinal ganglion cells (ipRGCs), that is separate from the rod and cone cells that transduce visual signals (1). Thus, the eye-brain connection is far more complex than previously thought, and the more we learn the more complex we find it to be (2). Ever since this discovery, debate has raged concerning how to apply this knowledge, and how quickly to do so (3).
One reason for caution is that lighting installations serve many functions, and our recommendations reflect this complexity. As I wrote in a previous blog entry, lighting quality exists at the nexus of the needs of individuals, the environmental and economic context, and architectural considerations. Strong evidence is needed to intelligently blend new discoveries into coherent guidance in balance with the other considerations.
Simplified schematic diagram of two eye-brain pathways, taken from CIE 158:2009. Light received by the eye is converted to neural signals that pass via the optic nerve to these visual and non-visual pathways. POT = Primary optic tract. RHT = Retino-hypothalamic tract. LGN/IGL = Lateral geniculate nucleus / Intergeniculate leaflet. SCN = Suprachiasmatic nucleus of the hypothalamus. PVN = Paraventricular nucleus of the hypothalamus. IMLCC = Intermediolateral cell column of the spinal cord. SCG = Superior cervical ganglion. CRH = Corticotropic releasing hormone. ACTH = adrenocorticotropic hormone. (c) CIE, 2009. Used by permission.
What is the image-guided radiotherapy (IGR)?
The combination of medical imaging and radiotherapy constitutes an important research field, for the group “NCM” of UTINAM Institute (Université de Franche Comté, Besançon, France). Our studies aims at rendering radiotherapy more specific by concentrating the dose deposition of the radiation in the tumour while sparing the healthy tissues. For achieving this goal, multifunctional gold nanoparticles are in the heart of our research activities since these nanoparticles exhibit a great potential for radiosensitization and medical imaging. Their presence in the tumor will increase the deleterious effect of the radiation in order to specifically eradicate the cancerous cells. The cells appear therefore more sensitive to the therapeutic radiation. Indeed the preferential absorption of the ionizing radiation (X- or γ-rays) by the gold nanoparticles will produce a shower of highly reactive radicals which will seriously alter the tumor. Owing to the combination of medical imaging and therapy, the most opportune moment (high content of nanoparticles in tumour and low content in healthy tissues) can be determined for activating the therapeutic effect of gold nanoparticles. In other words, the radiotherapy is guided by imaging. The treatment by radiotherapy was based on MRT (Microbeam Radiation Therapy). MRT is a non-conventional irradiation technique performed at the ESRF (European Synchrotron Radiation Facility, Grenoble, France). The therapeutic radiation is constituted by an array of parallel microbeams.
A schematic illustration showing how nanoparticles or other cancer drugs might be used to treat cancer.
If you play a guitar string, you will hear a note, whose tone will depend on the string diameter and on the string tension. This sound is not just made of a pure (“single”) vibration, which would sound rather ugly and boring, but rather to the overlap of several acoustic frequencies playing simultaneously, which makes the note “round” and pleasant. More than that: it makes the note unique. You will be able, in fact, to tell it’s a guitar and not a piano, or even which kind of guitar. The very same concept applies to the voice of people: you can easily distinguish two persons pronouncing the same sentence at the phone because they have a different tone. The ensemble of the vibrating frequencies that form the sound and the voice is called the timbre. In physics, we call it spectrum, and it not only applies to sound but also to light, indicating its various frequency components, i.e. its colors!
This is a typical vibrational spectrum of a cell. The various peaks correspond to the notes of the various molecules present and can be used for the precise characterization of the cell content and cell state. Credit: adapted from J. R. Thomas, Annu. Rev. Biophys. Biomol. Struct. 28, 1 (1999), http://dx.doi.org/10.1146/annurev.biophys.28.1.1.