29
April
2007
29-Apr-2007 The only nerve cells in the body to run directly from the brain to the outside world, olfactory cells – which give us our sense of smell – are in constant danger of being killed by harsh chemicals in the air.
Researchers have now identified a backup supply of stem cells that can repair the most severe damage to these nerves. These reservists normally lie around doing nothing, but jump into action when smell cells die.
“These stem cells act like the Army Reserves of our nose, supporting a class of active-duty stem cells that help repair normal wear and tear,” explains lead author Randall Reed. “They don’t come in until things are really bad.”
19-Apr-2007 For the first time scientists predict the effect of small changes in a molecule on its scent. The results prove that it is “the electronic surface structure of a molecule” that defines its fragrance, say the researchers.
26-Dec-2006 Exposure to scents helps the brain to distinguish other similar scents. Researchers presented a single odour to human subjects for a few minutes. Half got a minty odour, the other half a flowery one. This brief sensory exposure created mint or floral expertise, respectively, at least for a time. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
27
April
2007
26-Apr-2007 Strange things happen in the twilight zone. Carbon dioxide absorbed by photosynthesizing marine plants near the sunlit ocean surface does not all sink to the depths.
Instead the carbon on sinking marine particles is often consumed by animals and bacteria, and recycled in the twilight zone—100 to 1,000 meters below the surface—so it never reaches the deep ocean.
Using new technology, a multi-national team has discovered that the twilight zone acts as a gate, allowing more sinking particles through in some regions and fewer in others. This makes it more difficult for the moment to predict the ocean’s role in offsetting the impacts of greenhouse gases.
3-Apr-2007 Coral reefs around the world are being exploited unsustainably. To support current levels of fishing an additional area almost four times that of Australia’s Great Barrier Reef would be needed. These figures will nearly triple by 2050.
2-Nov-2006 Research shows that all stocks of fish and seafood in the oceans will collapse within forty years. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
26
April
2007
23-Apr-2007 One of the weirdest organisms that ever lived, Prototaxites had tree-like trunks that stood more than 20 feet high, making it the largest known land organism of its time – 420 to 350 million years ago. It has been classed as a conifer, a lichen and various types of algae. But carbon isotope analysis of the fossil and the plants that lived in the same environment has shown that Prototaxites “displayed a much wider variation in its ratio of carbon-12 to carbon-13 content than would be expected in any plant.”
This supports the idea that the beast was actually a “humongous fungus“, says Carol Hotton of the National Museum of Natural History.
This is an application of the same technology, derived from the difference between C3 and C4 photosynthesis, as the previous story
9-Jan-2007 Paranthropus is an ancestor of modern humans who has often been seen a a specialist who lacked a varied diet. That is why Paranthropus went extinct, it was thought, as the climate changed and Africa became drier, while tool-wielding Homo, with a highly varied diet, survived. But a new study, using carbon isotope analysis of four fossil teeth, shows that Paranthropus also ate a variety of foods and the explanation for extinction must go deeper. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
26
April
2007
How photosynthesis tells us what our ancestors ate
1 We can learn an incredible amount about the nature and behaviour of plant, animal and even human life in the distant past by studying the ratio of carbon-13 to carbon-12 in their fossils. It works like this (explanation originally written for older kids):
2 One of the most important gases in the atmosphere is carbon dioxide.
3 Green plants absorb carbon dioxide from the atmosphere and release oxygen.
4 This is called photosynthesis.
5 It is the source of all food on Earth and of the oxygen we breathe.
6 The carbon in carbon dioxide occurs in two slightly different forms: carbon-12 and carbon-13.
7 These are called isotopes of carbon.
8 The carbon-13 isotope makes up 1% of the carbon in the atmosphere.
9 The other 99% of carbon in the atmosphere is carbon-12.
10 So you might expect the carbon in plants and trees to have these same proportions.
11 But photosynthesis is a complex and inefficient process.
12 It slightly prefers the lighter carbon-12.
13 So the carbon trapped in plants and trees has a greater fraction of carbon-12 than the atmosphere.
14 And a lower fraction of carbon-13
15 Now it gets slightly more complicated:
16 Normal photosynthesis is even more inefficient in hot, dry conditions.
17 So a slightly different form of photosynthesis appeared in some tropical plants around 65 million years ago.
18 Tropical grasses, sugar-cane and maize (often called corn) use this newer method of photosynthesis.
19 These are called C4 plants.
20 The vast majority of green plants and trees continue to use the old method.
21 These are called C3 plants.
22 C4 plants prefer carbon-12 to carbon-13, just as C3 plants do.
23 But they don’t prefer it quite as strongly.
24 So C4 plants end up with a slightly greater fraction of carbon-13 than C3 plants.
25 This means that the carbon trapped in tropical grass (a C4 plant) on the savannah, has a greater fraction of carbon-13 than does the carbon trapped in the forest trees (C3 plants).
26 The last steps come from noticing that the carbon in plants that are eaten goes to build bodies.
27 So the carbon isotope proportions of hair, nails, teeth and bones reflect the carbon isotope proportions of the plants that have been eaten.
28 They still reflect those fractions after the animal or human are long dead.
29 So a scientist sitting in a lab in Utah can tell what an early human was eating by studying pieces of his 2 million-year-old tooth.
30 The scientist can even tell what the early human was eating at different times of the year by studying different parts of the tooth.
31 Notice that whether the early human was eating tropical grass or animals grazing on that grass, the carbon isotope proportions will show that he or she had a C4 diet.
32 Note: This whole method works because both carbon-12 and carbon-13 are stable isotopes.
33 This means they are not radioactive and so don’t change as time passes.
34 Carbon-14, which is used in carbon dating, is not stable – it is radioactive and does change with time.
35 But neither carbon-14 nor radiocarbon dating has anything to do with the science of this story.
Posted: News updates
20
April
2007
20-Apr-2007 A new undersea chimney emitting hot springs of iron-darkened water – a black smoker – has been discovered 8,500 feet down in the Pacific Ocean off Costa Rica. Living there the scientists have found a pink form of the jellyfish order stauromedusae, which may be a new species. The jellyfish looks a bit like Medusa, the serpent-haired monster of Greek mythology, said expedition leader Emily Klein. So they have now named this part of the sea-floor the Medusa Hydrothermal Vent Field.
12-Apr-2007 Scientists have reported one of the world’s greatest mass death of corals, caused directly by the earthquake in Indonesia on 28 March 2005.
2-Apr-2007 A high-tech villa, designed to resist earthquakes by self-healing cracks in its walls and monitoring vibrations through intelligent sensors, will be built on a Greek mountainside.
29-Mar-2007 Scientists show that lightning is a good indicator of volcanic activity by observing “spectacular lightning sequences” at Mount Augustine, Alaska.
4-Dec-2006 Tsunami story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
19
April
2007
19-Apr-2007 A new study of dark matter haloes shows they are shaped like frisbees, not rugby balls as had been suggested.
3-Apr-2007 Scientists propose a new model of large-scale gravitation in which the force on dark matter is different to that experienced by normal matter.
The Abnormally Weighting Energy hypothesis achieves a number of scientifically satisfactory outcomes: It agrees well with observation, particularly of distant supernovae. It does not require negative pressures. It predicts an age of the universe 3 billion years greater than current models. And unlike previous theories of dark matter, it does not lead to an exponentially expanding universe, but rather a normal Einstein-de Sitter space, in which expansion is slowed by gravitation.
Best of all, AWE explains with minimal change to existing physics the otherwise deeply mysterious “dark energy”.
4-Dec-2006 Observations from Hubble Space Telescope show that dark energy has been speeding up the expansion of the universe for the largest part of its existence. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
18
April
2007
18-Dec-2006 How does a school of fish or flock of birds know how to move instantly from one pattern to another? New research from the University of Alberta shows how movements by a single individual ripple through the whole group.
18-Dec-2006 Flotillas of smart dust particles could be the first emissaries from Earth to visit extra-solar planets. Story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
18
April
2007
Teaching resources (UK US) designed specifically for this story at Real Science
The story
Tiny, shape-shifting devices that are carried on the wind like dust, but are smart enough to communicate, fly in formation and take scientific measurements. Sounds like science fiction? Not at all, say engineers at the University of Glasgow, who are designing a new breed of planet explorers.
Smart dust particles contain a computer chip one millimetre across. This is surrounded by a polymer sheath that a small voltage can make wrinkled or smooth.
Roughening the surface makes the drag on the smart dust particle increase and it floats higher in the air. Smoothing out the surface causes the particle to sink. Simulations show that by switching between rough and smooth, the smart dust particles can hop towards a target.
Professor John Barker will talk about possible applications of smart dust at the RAS National Astronomy Meeting in Preston today, 18 April. “The concept of using smart dust swarms for planetary exploration has been talked about for some time,” he said.
“But this is the first time anyone has looked at how it could actually be achieved. Computer chips of the size and sophistication needed to make a smart dust particle now exist.”
He and his team are studying a variety of polymers to find one that can give a large deformation for a small voltage, he added.
Smart dust particles would use wireless to communicate with each other and form swarms, Professor Barker explains. Most particles in the swarm can only talk to their nearest neighbours. But a few can communicate at much longer distances.
“In our simulations we’ve shown that a swarm of 50 smart dust particles can organise themselves into a star formation, even in turbulent winds.
“The ability to fly in formation means that the smart dust could form a phased array. It would then be possible to process information between the distributed computer chips, and collectively beam a signal back to an orbiting spacecraft.”
For smart dust to explore a planet, the particles need to carry sensors. Today’s chemical sensors are too big for the thin Martian atmosphere. This could only support particles the size of sand grains.
But the atmosphere of Venus is much denser. It could carry smart sensors up to a few centimetres in size. “Scientific studies could theoretically be carried out on Venus using the technology we have now,” says Professor Barker.
“However miniaturisation is coming on rapidly.”
By 2020 chips will be available with components just a few nanometres across, he said. “This means our smart particles would behave more like macro-molecules diffusing through an atmosphere, rather than dust grains.”
The Glasgow group believes it will be some years before smart dust is ready to be launched into space. “We are still at an early stage, working on simulations and components,” said Professor Barker. “We have a lot of obstacles to overcome before we are even ready to physically test our designs.
“However, the potential applications of smart dust for space exploration are very exciting. Our first close-up studies of extra-solar planets could come from a smart dust swarm delivered to another solar system by ion drive.”
Topics for group discussion or pupil presentations
1. Figuring out exactly what scientists have been doing on the basis of news stories is often quite difficult. A useful starting point is an activity that asks students to classify the different types of statement in a story. In groups students should look for all the occurrences of just two types of statement in this story: a) technology and methods used by the scientists, and b) new findings or developments they have made.
Students should then try to answer the following questions:
- In as much detail as possible, what do these Glasgow scientists actually do when they come into work each day?
- How has what they have been doing made the manufacture of smart dust more likely?
2. In groups, students should assess the merits of manned versus unmanned space exploration. Human spaceflight is costly, dangerous, and a complete waste of time and money, say critics. Supporters point out that the urge to explore is part of what makes us human. The key difference between people and robots (including smart dust) in space is that we care about people. It is hard to identify with the adventures of dust, no matter how smart it might be. So space exploration needs people up there to win support and funding from governments and the general unscientific public. Discuss.
3. One of the most astonishing sights in nature is a flock of starlings at evening-time, flying in formation, swooping and swirling in mesmerising patterns that seem to be controlled by just one mind. It’s one example of a phenomenon called emergent behaviour, which is quite widespread in the natural world. The scientists in this story are aiming to exploit the emergent behaviour of smart dust particles.
Students should find as many examples in the natural world as they can, and prepare a short presentation which touches on how one controlling mind can seem to emerge when individuals communicate only with their nearest neighbours.
Links to free activities, resources and lessons
This story is about science just beyond the limits of today’s technology, so the Web offers few relevant classroom activities. The following is a set of sources of accessible information on smart dust and its applications.
Professor Barker on smart dust research at Glasgow University. Includes entries on space applications, shape changing and the analogy with blown sand.
City-swallowing sand dunes. Nice illustrated story and audio of how particles of sand move by a method known as saltation. This is the most likely mode of travel for the first generation of smart dust.
“Swarms of smart dust might be packed into nose cones of planetary probes and subsequently ejected into the atmosphere of a planet where they would be carried by the wind. For a planet such as Mars smart dust motes would each be of the size of a grain of sand.” From Professor Barker’s website.
Notes and thoughts on a smart dust project at Berkeley.
Website of a company set up to commercialise smart dust.
“We have considered the collective movement of motes towards a target located in a portion of the Martian surface that extends over a range of several kilometres.” Professor Barker again.
The smart dust project. “Smart dust was developed by Kris Pister, Joe Kahn, Bernhard Boser at the University of Berkley, California, between 1998 and 2001 with the aim of demonstrating a complete sensor/communication system that can be integrated into a cubic millimetre package.” Glasgow University is a member of a large consortium dealing with a practical variant called Smart Specks.
Daily tip for science class discussions and groupwork
Listening to each other is not merely a matter of being quiet when another person speaks; listening requires a response to what is being said. Teachers could develop procedural guidelines to give structure to group talk so that children become used to questioning and challenging each other. The consistency in performance of one group in the study suggests that the children may have developed certain ground rules for the argumentation process, as they knew how to work together collaboratively. The inconsistent performance shown by other groups suggests that although they were capable of high levels of argumentation, they had no such ground rules. If children are able to scaffold small-group discussions themselves then the teacher input could be directed towards children who are not yet capable of doing this.
Simon, S. and Maloney, J. (2007) Activities for promoting small group discussion and argumentation. School Science Review, 88 (324), pp. 49-57
Posted: Technology
17
April
2007
Teaching resources (UK US) designed specifically for this story at Real Science
The story
Scientists at Washington University, with the help of a keen-eyed student, are paving the way for the Phoenix Mission to make a smooth landing on Mars.
The team has been analysing images of the surface of the red planet. Their aim is to make sure the Phoenix, which is due to launch in August, lands in a rock-free spot on the northern plains of Mars.
The craft has to land in a place that won’t have steep slopes or big rocks, said Raymond Arvidson, professor in arts and sciences, and chair of the Washington University earth and planetary sciences department.
“We’ve been looking for locations big enough and homogeneous enough for a high probability of a successful landing. The issue isn’t slopes. The issue is rocks.”
If the lander came down in a place with rocks as big as itself, the whole craft could tilt or tip over. Another problem is the craft’s solar panels. Big rocks would stop these unfurling. Without solar power, which drives seven Phoenix mission instruments, there isn’t much of a mission.
At the heart of the painstaking task of finding a smooth landing is a 21-year-old student at Washington University. Tabatha Heet began working with Arvidson as a work-study student in 2005. She started counting Martian rocks in October 2006.
“Ray asked if I would count some rocks in the original landing area, and I got started, thinking it was going to be a one-time thing,” said Heet. “But it’s turned into a big project. I’ve counted thousands of rocks now.”
Arvidson and his colleagues had settled on a region called Region B for the future landing. But images from an instrument called HIRISE, a feature of the Mars Reconnaissance Orbiter Mission, made them think again.
“The first images for Region B were scary,” Arvidson said. “There are rocks there bigger than the lander – too many big rocks sitting on craters to fit in a landing site.”
With the help of HIRISE images, they looked elsewhere. Heet produced data on the abundance of rocks at different places on the northern plains. This allowed the mission scientists to “zero in on the safe havens”, Arvidson said.
Heet used a software package called ENVI. This shows images and makes measurements.
“All you have to do is draw a line on the image,” she said. “Then ENVI will tell you how long the line is in meters. I go through the image and pick just a small area, because the HIRISE images are too big for one person to count. I’ll make a little subset and then go count every rock in the subset, just by drawing a line where I see the shadow of the rock.
“It’s very slow and makes your eyes go crazy.”
She counted rocks in little areas of the large images. She then made cumulative frequency plots. These showed the number of rocks bigger than any given diameter.
Heet flew out to the Jet Propulsion Laboratory in February. She received a warm round of applause at her introduction to JPL researchers. They questioned her on her technique and stamina. Later, she met a team of automated rock counters who “aggressively” questioned the way she had been counting rocks.
At the meeting, the automated rock counters calibrated their computed numbers to Heet’s hand counts. They are considered ‘ground truth,’ on which all later data are based. She has since corresponded with the group regularly to help make the automated counts more precise.
The automated rock counters map the shape of the shadows, said Arvidson. “From knowing where the sun is, they can compute the rock height and width.
“But they need very intense validation. Tab was the point contact for all of that. We’ve cross-calibrated against the automated counts, because the hand-derived ones are considered anchors.
A human can do a better job with fewer errors “as long as the person is not fatigued”, he added.
Heet’s work has led to the discovery of several possible landing sites. These have at least ten times fewer rocks than the original Region B. They include one desirable location 50 kilometres wide and 250 meters deep. The scientists call it Green Valley.
As data come in from the actual mission, Heet will be at JPL, gathering and interpreting the data, Arvidson said. Just as former Rhodes scholar Bethany Ehlmann, now pursuing a PhD at Brown University, did for the Mars Exploration Rover.
After all her dedicated, painstaking work, Heet often thinks of the mission and the thrill of the Phoenix launch and landing.
“I will certainly be excited when Phoenix launches. I will also probably feel a little bit of pride knowing that I helped make the launch possible. I suspect I’ll be slightly nervous when Phoenix is landing, wondering if I did something wrong and am going to be responsible for making Phoenix crash in a field of huge boulders. Once the lander is on the surface it will be interesting to find out just how accurate all of our predictions were.
“I’m looking forward to it all.”
Topics for group discussion or pupil presentations
1. Research and present current and past thinking about the chances of finding life on Mars.
2. In groups discuss what effect the discovery of life on other planets would have on how people think about science. Would the subject become more popular? Would religions with their view that humans are special disappear? Would the answers to these two questions be different if the extraterrestrial life we discovered were intelligent beings like us or “just” micro-organisms?
3. There are now scientists called astrobiologists who aim to discover if there is life on other planets, by analysing the light that comes from them. Amazingly they are working towards doing this for planets around other stars, as well as in our own solar system. Separating the light of these “exoplanets” and the light of their star has been compared to separating a candle 1000 kilometres away from a lighthouse beside it. Students should read the interview with Giovanna Tinetti then discuss and explain what an astrobiologist actually does.
Links to free activities, resources and lessons
Phoenix mission homepage. Scheduled for launch in August 2007, the Phoenix Mars Mission is designed to study the history of water and habitability potential in the Martian Arctic’s ice-rich soil.
The Phoenix Classroom. Activities and materials to aid understanding of fundamental concepts in science, technology, engineering and mathematics. Includes programs for teacher and student participation.
Ask the Phoenix Mars Mission team a question.
“Spacecraft visiting Mars have returned intriguing images of the surface of the Red Planet for over forty years. Many of these images suggest liquid water once flowed on the surface of Mars. The online video Mars: The Search for Water, the Search for Life looks at some of these images, compares them to similar features on Earth, and looks at the consequences of finding liquid water on Mars.
Phoenix mission fact sheet.
Introduction to what we know and hope to discover about Mars. Learn about the Red Planet by comparing similarities and differences to Earth.
The Phoenix Student Interns Program is an opportunity for high school teachers and students to become part of the science team for the 2007-2008 Phoenix Mars Lander Mission. Selected teachers and students will work with scientists to prepare for surface operations on Mars, analyse data during the mission, and reach out to other students, teachers, and the public through presentations, articles, and web sites. Apply by April 25, 2007
Learn how to organise data in a cumulative frequency table.
Design, construct and test an original model of a bouncing lander. Hold a classroom contest to see which landers work best to keep the cargo from breaking.
Links to more links
Space games and quizzes.
Daily tip for science class discussions and groupwork
Only exceptional lecturers are capable of holding students’ attention for an entire lecture period. It is even more difficult to provide adequate opportunity for students to critically think through the arguments being developed. Consequently, lectures simply reinforce students’ feelings that the most important step in mastering the material is memorizing a zoo of apparently unrelated examples.
In order to address these misconceptions about learning, we developed a method, Peer Instruction, which involves students in their own learning during lecture and focuses their attention on underlying concepts. Lectures are interspersed with conceptual questions, called ConcepTests, designed to expose common difficulties in understanding the material. The students are given one to two minutes to think about the question and formulate their own answers; they then spend two to three minutes discussing their answers in groups of three to four, attempting to reach consensus on the correct answer. This process forces the students to think through the arguments being developed, and enables them (as well as the instructor) to assess their understanding of the concepts even before they leave the classroom.
From Peer Instruction
Posted: Physics
14
April
2007
14-Apr-2007 A new model of the physics of neutron stars helps explain the ’superbursts’ of X-rays that these exotic collapsed stars (one teaspoon of which weighs a billion tons) emit much more regularly than previous models predicted.
9-Apr-2007 When it comes to eerie astrophysical effects, magnetars are hard to beat. News story and science teaching resources (US or UK English) posted at www.realscience.org.uk
Posted: News updates
