Advanced Geometry in SW American Prehistory
Imagine you are about to plan and construct a building that involves several complicated geometrical shapes, but you aren’t allowed to write down any numbers or notes as you do it. For most of us, this would be impossible. Yet, new research from Arizona State University has revealed that the ancient Southwestern Pueblo people, who had no written language or written number system, were able to do just that—and used these skills to build sophisticated architectural complexes.
Dr. Sherry Towers, a professor with the Arizona State University Simon A. Levin Mathematical, Computational and Modeling Sciences Center, uncovered these findings while spending several years studying the Sun Temple archaeological site in Mesa Verde National Park in Colorado, constructed around AD 1200.
“The site is known to have been an important focus of ceremony in the region for the ancestral Pueblo peoples, including solstice observations,” Towers says. “My original interest in the site involved looking at whether it was used for observing stars as well.”
However, as Towers delved deeper into the site’s layout and architecture, interesting patterns began to emerge.
“I noticed in my site survey that the same measurements kept popping up over and over again,” she says. “When I saw that the layout of the site’s key features also involved many geometrical shapes, I decided to take a closer look.”
The geometrical shapes used within this location would be familiar to any high school student: equilateral triangles, squares, 45-degree right triangles, Pythagorean triangles, and the “golden rectangle,” which was well known to architects in ancient Greece and Egypt and is often used in Western art due to its pleasing proportions.
With some geometrical know-how, a straightedge, a compass or cord, and a unit of measurement, all of the shapes are fairly easy to construct. But, unlike the ancient Greeks, Egyptians and Maya, the ancestral Pueblo people had no written language or number system to aid them when they built the site. Incredibly, their measurements were still near perfect, with a relative error of less than one percent.
“This is what I find especially amazing,” Towers says. “The genius of the site’s architects cannot be underestimated. If you asked someone today to try to reconstruct this site and achieve the same precision that they had using just a stick and a piece of cord, it’s highly unlikely they’d be able to do it, especially if they couldn’t write anything down as they were working.”
During her research, Towers discovered that the site was laid out using a common unit of measurement just over 30 centimeters in length—equal to about one modern-day foot. She also found evidence that some of the same geometrical constructs from the Sun Temple were used in at least one other ancestral Puebloan ceremonial site, Pueblo Bonito, located in New Mexico’s Chaco Culture National Historic Park.
“Further study is needed to see if that site also has the same common unit of measurement,” she says. “It’s a task that will keep us busy for some years to come.”
New Materials Could Turn Water into the Fuel of the Future
Researchers at Caltech and Lawrence Berkeley National Laboratory (Berkeley Lab) have—in just two years—nearly doubled the number of materials known to have potential for use in solar fuels.
They did so by developing a process that promises to speed the discovery of commercially viable solar fuels that could replace coal, oil, and other fossil fuels.
Solar fuels, a dream of clean-energy research, are created using only sunlight, water, and carbon dioxide (CO2). Researchers are exploring a range of target fuels, from hydrogen gas to liquid hydrocarbons, but producing any of these fuels involves splitting water.
Each water molecule comprises an oxygen atom and two hydrogen atoms. The hydrogen atoms are extracted and then can be reunited to create highly flammable hydrogen gas or combined with CO2 to create hydrocarbon fuels, creating a plentiful and renewable energy source. The problem, however, is that water molecules do not simply break down when sunlight shines on them—if they did, the oceans would not cover most of the planet. They need a little help from a solar-powered catalyst.
To create practical solar fuels, scientists have been trying to develop low-cost and efficient materials, known as photoanodes, that are capable of splitting water using visible light as an energy source. Over the past four decades, researchers identified only 16 of these photoanode materials. Now, using a new high-throughput method of identifying new materials, a team of researchers led by Caltech’s John Gregoire and Berkeley Lab’s Jeffrey Neaton and Qimin Yan have found twelve promising new photoanodes.
A paper about the method and the new photoanodes appears the week of March 6 in the online edition of the Proceedings of the National Academy of Sciences. The new method was developed through a partnership between the Joint Center for Artificial Photosynthesis (JCAP) at Caltech and Berkeley Lab’s Materials Project, using resources at the Molecular Foundry and the National Energy Research Scientific Computing Center (NERSC).
The research, Gregoire says, reveals how different choices for this third element can produce materials with different properties and how to “tune” those properties to make a better photoanode.
Improving Memory with Magnets
The ability to remember sounds, and manipulate them in our minds, is incredibly important to our daily lives—without it we would not be able to understand a sentence, or do simple arithmetic. New research is shedding light on how sound memory works in the brain, and is even demonstrating a means to improve it.
Scientists previously knew that a neural network of the brain called the dorsal stream was responsible for aspects of auditory memory. Inside the dorsal stream were rhythmic electrical pulses called theta waves, yet the role of these waves in auditory memory were until recently a complete mystery.
To learn precisely the relationship between theta waves and auditory memory, and to see how memory could be boosted, researchers at the Montreal Neurological Institute of McGill University gave seventeen individuals auditory memory tasks that required them to recognize a pattern of tones when it was reversed. Listeners performed this task while being recorded with a combination of magnetoencephalography (MEG) and electroencephalography (EEG). The MEG/EEG revealed the amplitude and frequency signatures of theta waves in the dorsal stream while the subjects worked on the memory tasks. It also revealed where the theta waves were coming from in the brain.
Using that data, researchers then applied transcranial magnetic stimulation (TMS) at the same theta frequency to the subjects while they performed the same tasks, to enhance the theta waves and measure the effect on the subjects’ memory performance.
They found that when they applied TMS, subjects performed better at auditory memory tasks. This was only the case when the TMS matched the rhythm of natural theta waves in the brain. When the TMS was arrhythmic, there was no effect on performance, suggesting it is the manipulation of theta waves, not simply the application of TMS, which alters performance.
“For a long time the role of theta waves has been unclear,” says Sylvain Baillet, one of the study’s co-senior authors. “We now know much more about the nature of the mechanisms involved and their causal role in brain functions. For this study, we have built on our strengths at The Neuro, using MEG, EEG and TMS as complementary techniques.”
The most exciting aspect of the study is that the results are very specific and have a broad range of applications, according to Philippe Albouy, the study’s first author.
“Now we know human behavior can be specifically boosted using stimulation that matched ongoing, self-generated brain oscillations,” he says. “Even more exciting is that while this study investigated auditory memory, the same approach can be used for multiple cognitive processes such as vision, perception, and learning.”
The successful demonstration that TMS can be used to improve brain performance also has clinical implications. One day this stimulation could compensate for the loss of memory caused by neurodegenerative diseases such as Alzheimer’s.
“The results are very promising, and offer a pathway for future treatments,” says Robert Zatorre, one of the study’s co-senior authors. “We plan to do more research to see if we can make the performance boost last longer, and if it works for other kinds of stimuli and tasks. This will help researchers develop clinical applications.”
This study was published in the journal Neuron on March 23, and was a result of collaboration between the Neuroimaging/Neuroinformatics and Cognition research groups of the MNI.
Michelangelo’s Medici Chapel May Contain Hidden Symbols of Female Anatomy
Michelangelo often surreptitiously inserted pagan symbols into his works of art, many of them possibly associated with anatomical representations. A new analysis suggests that Michelangelo may have concealed symbols associated with female anatomy within his famous work in the Medici Chapel.
For example, the sides of tombs in the chapel depict bull/ram skulls and horns with similarity to the uterus and fallopian tubes, respectively.
Numerous studies have offered interpretations of the link between anatomical figures and hidden symbols in works of art not only by Michelangelo but also by other Renaissance artists.
“This study provides a previously unavailable interpretation of one of Michelangelo’s major works, and will certainly interest those who are passionate about the history of anatomy,” said Dr. Deivis de Campos, lead author of the Clinical Anatomy article. Another recent analysis by Dr. de Campos and his colleagues revealed similar hidden symbols in Michelangelo’s Sistine Chapel.
CAPTION: A) Side of Medici tomb. B) Skull and horns resemble uterus and fallopian tubes. C) Shell in image A clearly resembles the shell in Botticelli’s “The Birth of Venus.” Credit: Clinical Anatomy