Category Archives: Everyday Physics

Periodic table gets updates for some atomic weights

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New Scientist: The order of the elements listed in the periodic table is dependent on the number of protons in the nucleus. However, each element has a variety of isotopes with varying numbers of neutrons in the nucleus, so each isotope has a slightly different mass. What’s more, the relative concentrations of each isotope can vary in different locations and environments. The International Union of Pure and Applied Chemistry (IUPAC) defines the standard atomic weight of the elements as listed on the periodic table based on the weighted mean of the stable isotopes of each element. Two years ago the IUPAC began listing a range of weights instead of a single value for elements that have varying concentrations depending on location and environment. And with the new change it is now listing both bromine and magnesium with ranges. Updates were also made to the weights of germanium, indium, and mercury.

Accurately measuring the power of a tsunami

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BBC: When an underwater earthquake generates a tsunami, every second counts because it takes only a few minutes before a wall of water can hit a shoreline. The current early warning system for tsunamis relies on seismographs to measure Earth movement and hence calculate the amount of energy dissipated into wave energy, but the technique is not reliable. A team from the GFZ German Research Centre for Geosciences says that GPS sensors placed around the coastlines of vulnerable countries could make highly precise measurements of how underwater tremors shift the ground. In turn, the data could be used to reconstruct the source of the earthquake and calculate its magnitude. ”You can then predict the tsunami and see how high a wave could be expected, with some accuracy,” says Andreas Hoechner, one of the researchers.

Using lasers to make wooden music records

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Daily Mail: Amanda Ghassaei, a software engineer from California, has previously shown how to use 3D printers to make vinyl music records. Now she has posted online instructions for an alternative method that uses a laser cutter to cut records out of wood. The process involves converting an MP3 into a digital waveform, which is then saved as a pdf. The pdf becomes the “vector cutting path” that the laser cutter follows to carve the pattern into the wood. Because the laser’s resolution is relatively low, the groove is twice as thick as a normal record groove. Hence, only about three minutes of music will fit on a standard-sized record, and the sound fades to static the closer the needle moves to the center as the sampling rate decreases. If no laser cutter is available, Ghassaei says that a computer numerically controlled (CNC) mill or CNC razor-blade paper cutter could also be used. Because of the lower resolution, the technique works best with songs that are dominated by low- to mid-range sounds. Ghassaei provided a video of one of the records playing Radiohead’s “Idioteque.”

Better online shopping recommendations thanks to particle physics

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MIT Technology Review: Online shopping sites make use of various algorithms to suggest items for you to purchase based on what you and other users have purchased in the past. One effect of such recommendations is that some locales or products suffer from the sudden influx of people directed to them by the recommendation. To try to avoid this problem, a team of researchers led by Stanislao Gualdi of the University of Fribourg in Switzerland has applied a feature of particle physics. At the atomic level, particles tend to occupy the most energetically favorable states; but the number of particles that can occupy any given state depends on the type of particle. Gualdi drew a parallel between this concept and that of commercial products, which can be shared by either many or just a few people. The team developed a model that can limit the number of users allowed for a given product. When testing their model against empirical data of DVD rentals, they found that limiting rentals ensures that a wider range of DVDs get rented. And the more DVDs rented, the broader the range and accuracy of the ensuing recommendations. The overall effect was a healthier rental system. However, whether the model would work for actual retailers, who focus on maximizing their profits, is uncertain.

Smartphone apps turn users into citizen scientists

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Marketplace: Smartphone apps are now being used by researchers as a mechanism for collecting large amounts of data. With Project Budburst, for example, nature lovers can help scientists monitor plants through the seasons by taking photos of them. The app records the exact locations and observation times and can even allow the user to add notes. With some 13 000 participants, Project Budburst adds significantly to the amount of ecological data available to researchers. In a Marketplace audio file, Liyna Anwar interviews UCLA student Sophie Gerrick about her contributions as a citizen scientist.

Mathematical model developed for foldable rings

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Nature: Flexible rings that fold up on themselves into saddle shapes or stacks of interlinked loops are most recognizable in such everyday items as pop-up tents and laundry baskets. A group of researchers led by Alain Jonas of the Catholic University of Leuven in Belgium has determined that the way these rings behave depends on a single characteristic known as overcurvature, or how much more curved the ring is than a flat circle of the same circumference. By modeling overcurvature, the researchers were able to predict what shape a given ring would take and the path it would take to get there, which depends on how much energy was applied. A three-ring stack of interlocked loops required more energy at the start, but settled into position much more easily than forms that required less energy at the start. Jonas believes that his team’s findings regarding overcurvature may also apply to molecular rings such as plasmids or various polymers.

Tracking the spread of information and disease

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Wired: Determining the origin of a bit of information, or of a disease outbreak, has often required the backwards, step-by-step tracing of the transmission. However, a new process can calculate the most likely source using only a fraction of the information required by earlier methods. Researchers at ETH Zürich recently estimated, and then combined, the most likely paths of transmission to individual nodes within a network. When they applied their technique to a known cholera outbreak in South Africa in 2000, the researchers could narrow down the source by using information about the presence of cholera in just 20% of the network’s nodes — in this case, communities in the region. The same technique was used  to determine the identity of the leader of a terrorist group and the spread of contamination in a subway system.

Seeing the structure of restored paintings

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BBC: Infrared scanning of artwork has been around for a while, but the heat caused by the light source can damage delicate paintings. A new adaption of the scanning technique, reported in Optics Express and called thermal quasi-reflectography (TQR), uses a less-damaging low-power halogen light to generate the IR. A TQR analysis of a 15th-century fresco called The Resurrection by Piero della Francesca showed retouches, unevenness in the painting of a shield, and even changes in the painting technique that do not show up in a near-IR image. More research is needed, say the authors, before TQR can identify pigments to help with restoration rather than just showing that different pigments or techniques were employed.

Brain injuries from roadside blasts are similar to football injuries

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ABC News: In a study published in the journal Science Translational Medicine, researchers found that improvised explosive devices, such as those used in terrorist or guerrilla attacks, can cause long-term brain damage. The researchers compared brain-tissue samples from four soldiers with those from three amateur American football players and a professional wrestler. All were known to have suffered blast exposure or concussive injury. The results showed that the brain damage observed in blast-exposed veterans is similar to the brain injuries in football players who have sustained repetitive concussive head injuries. The finding is significant because it demonstrates a common link between what had previously been believed to be two disparate injury mechanisms.

Subway grids exhibit mathematical properties

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BBC: From Beijing to Barcelona, all subway networks share similar generic features, according to a study published yesterday in the Journal of the Royal Society Interface. Despite differences in when they were built and where, all systems seem to evolve and self-organize in mathematically similar ways: “The number of branches scales roughly as the square root of the number of stations, the current proportion of branches represents about half of the total number of stations, and the average diameter of branches is about twice the average radial extension of the core,” write Camille Roth and coauthors in their paper. They surmise “the existence of dominant, universal mechanisms governing the evolution of these structures.”