# Drawing resistance

What’s happening?

Your veins have a rather nifty way of stopping blood from flowing back the wrong way – small flaps called ‘valves’ maintain a direction of blood-flow through your body. Some electronics also need to ensure the current only ever flows in a single direction. To do this, they use a component called a diode that acts a bit like an electrical valve. Continue reading Drawing resistance

# Tumbling probability

What’s happening?

Combination locks like these ones require a code with a string of digits that look something like ’3 – 16 – 7’. To unlock, the dial needs to be turned clockwise all the way around at least twice until the dial is pointing straight up (at the ‘twelve o’clock’ position). This ensures the tumblers are lined up correctly.
The first turn takes the dial from the starting position to point at number 2. It pushes the back tumbler so its gap (our black line) lines up with a release mechanism, or the latch. The second turn goes back the other way – anticlockwise – five places. This pushes the middle tumbler so its gap lines up as well. The third turn goes clockwise again by four places, rotating the front tumbler so all three gaps are together. This forms a space for the release mechanism to lift into, allowing you to lift the latch and open the lock. Continue reading Tumbling probability

# Spin cycle

What’s happening?

Before Isaac Newton, nobody gave too much thought to what made us fall back to Earth after we jump, or why we can’t float into the sky. This 17th century English philosopher had an interesting thought – he wondered if it had something to do with the reason planets stayed in orbits around the Sun. He came up with some rules about gravity and forces, explaining how all things moved. Continue reading Spin cycle

# Solar tea

#### What’s happening?

If you were to take all of the stuff that makes up our solar system, 99.86 per cent of it would be from the Sun, and consist of mostly hydrogen and helium. It’s not only a big object (109 planet Earths sitting side-by-side could fit across its diameter), its mass gives it a lot of gravity to squeeze all of that hydrogen and helium together.
All of that squeezing makes the Sun’s particles bump into one another rather energetically. In fact, the particles are pushed together so tightly, the forces that help hydrogen atoms stick together can reach out to one another and grab onto other atoms, making even bigger atoms. This is called nuclear fusion and is how hydrogen can turn into the slightly bigger element, helium. Continue reading Solar tea

# Lava fizz

#### What’s happening?

Water and oil aren’t exactly the best of friends. Because of their shape and the way their atoms stick together, they prefer keeping to themselves rather than mixing with one another. The Greek root for water is ‘hydro’, so we say that water is ‘hydrophilic’ (loves water) while oil is ‘hydrophobic’ (afraid of water). Because a drop of water has more mass than the same sized drop of oil, gravity pulls on it with more force, pulling it to the bottom. Continue reading Lava fizz

# Jellyfish tentacles

#### What’s happening?

You are watching fluid dynamics in motion. Fluid dynamics is the science of moving fluids. A fluid is something that flows and takes the shape of its container. Liquids like water, shampoo and volcanic lava are fluids. Even gases are fluids, although we can’t always see them flowing about. Continue reading Jellyfish tentacles

# Cloud crystals packed with life

Next time you’re outside, look up. Is there a cloud in the sky? You might know that these clouds are made of drops of water or ice, but that’s not all. Scientists in the US have now directly measured the biological material and mineral dust in the ice crystals found in clouds.
When the temperature is just right, clouds form around aerosols such as dust, smoke, salt, bacteria, plant matter and even the spores of fungi. Water and ice in the atmosphere grow around these aerosols and eventually this leads to rain or snow.
The scientists sampled clouds while flying at high speeds in an aircraft to find out more about these aerosols. They had a scientific instrument onboard called a mass spectrometer. This allowed them to measure the chemicals that make up ice particles in the clouds.

“By determining the chemical composition of the very cores of individual ice particles, they discovered that both mineral dust and, surprisingly, biological particles play a major role in the formation of clouds,” says Anne-Marie Schmoltner of the National Science Foundation’s Division of Atmospheric Sciences. Previously this could only be predicted from laboratory experiments and measurements on the ground.
The team of scientists found that biological matter made up 33 per cent of the particles in ice crystals and mineral dust made up 50 per cent.
It was impossible for the scientists to determine whether the plant matter, fungal spores and bacteria they found were alive. This is because the mass spectrometer they used ionised the samples, smashing the samples to bits, in order to work out what chemicals were in the ice crystals.
Working out the exact composition of clouds will help scientists produce more accurate predictions about climate change. It may also lead to new ways of producing rain clouds to lessen drought.

Article and photo source: CSIRO Science by Email

# The squeaky sounds of city living

Nature never feels further away than when you are in the middle of a city. Growling traffic, expanses of hot concrete and the countless tall buildings seem like another world far away from lush rainforests or tranquil mountain streams. You’d never think of a city as an ecosystem. Yet many animals have adapted to the hustle and bustle of the urban environment.
Birds and frogs use complicated songs to communicate with one another, usually to mark their territory or to attract a mate. Birds of the same species will often sing in different dialects just as we learn to speak in different languages. A study conducted in the US city of San Francisco has found the range of dialects sung by the white-crowned sparrow has changed over the past thirty years, while a study conducted by the University of Melbourne has found a similar change in frogs.
In both cases, the researchers wondered if the noise of the city influenced the species’ calls. Traffic, building construction and the effect concrete has on sound means the loudest noises in the city are low-pitched. Therefore high-pitched songs can be heard much more clearly.
In the American study, three different types of sparrow dialect were studied over three decades. The one with the lowest pitch disappeared by 1998, while the other two not only became more common, but seemed to increase in pitch when compared with their country cousins.
It’s unusual for bird dialects to change on their own so quickly, leading the researchers to believe the increasing noise of the city favoured white-capped sparrows who sang in higher pitches.
For frogs, the distance over which they can communicate can be reduced to as little as twenty metres if there’s noisy traffic around. To compensate, the males being studied seem to be croaking in a higher pitch to get the girls to listen. The question now is: do the ladies like the squeakier sounds?
Cities are important landscapes not just for humans, but for the animals who share it. While many species will adapt, and even thrive, others won’t do so well. It’s important to remember that nature isn’t always about forests, oceans and fields, but is often about what happens in our own backyard.

# News: Dino sores wreck Rex

Tyrannosaurus rex might be well known as the ‘tyrant lizard king’, but it seems not even this royal reptile was immune to nature’s tiniest organisms. Once thought to be caused by the bite of a fellow T. rex, holes in the jaws of a number of skeletons around the world are now suspected to be caused by a type of microscopic parasite.
Modern day pigeons can suffer from mouth infections caused by a single-celled organisms called Trichomonas gallinae. If left untreated, this microbe can move through the body and shut down major organs, killing the bird. This bird illness has been a major concern for pigeon racers in the past.
Serious infections caused by trichomonas parasite can often cause degeneration of nearby bone, which has led some US and Australian palaeontologists to question if such markings on the jaws of Tyrannosaurus rex remains could be caused by a similar parasite. Given that birds share a branch of the family tree with dinosaurs, this similarity could be rather significant.
This is not the first time bones have provided clues on a possible disease. Contagious diseases such as syphilis, leprosy and even tuberculosis have left marks on human skeletons, helping anthropologists gain a better understanding of the lifestyle and health of people who lived during ancient times.
Discoveries such as these can tell us a lot about how dinosaurs lived and died. As with pigeons, a T. rex with an infected jaw would find it difficult to eat and may starve to death. No other dinosaurs have been found with similar markings, and it has been proposed that it may have been spread via direct contact between fighting tyrannosaurs or even through cannibalism.
When studying extinct species, scientists typically have very little to go on other than a couple of bones or an occasional footprint. Even a tiny hole or mark on a bone can tell an interesting story.

# Galactic Suite Space Resort on Target

The Galactic Suite Project is a unique combination of commercialization and exploration. Directors Xavier Claramunt and Marsal Gifra have combined the expertise of three Spanish firms and one American company to bring this project to fruition. The Spanish firms are Equip XCL, Aerospace Research and Technology Center, and Global Business Technologies. The American firm, 4 Frontiers Corporation, brings with it the technology they are developing for the exploration of Mars. Headquarters of Galactic Suite is in Barcelona.

There are three phases which must be completed. First is the development of a spaceport on a yet-to-be-named Caribbean Island. The spaceport will feature a magnetic catapult to provide the initial supersonic boost to the spacecraft. There will be a runway for landing the spacecraft as the Space Shuttle does. Also on the island is a luxury hotel which will house the space travelers and their guests during the 18 week training period.

The spacecraft will be powered by hybrid rocket engines in two stages. After the catapult launch to supersonic speed, the rockets will accelerate the craft to its orbital speed of 18,000 miles per hour. The spacecraft will then maneuver to an orbital height of 300 miles, where the Galactic Suite module will be waiting. Crew on the ship will be four guests and two pilot/astronauts.

The Galactic Suite orbital hotel will have four modules joined to a central common area. Each “bedroom” module will feature a large window providing fantastic views of the earth and the stars. Floating in weightless conditions, the guests will enjoy 15 sunsets on each of the trip’s four days. At the end of the trip the crew and guests will board the spacecraft for the return to earth. The spacecraft will remain docked to the orbital hotel during the entire stay to provide an additional measure of safety and security.

The Galactic Suite Project’s initial goal of first flight in 2012 has been pushed back to 2015. The ownership continues to remain optimistic, though, and the bulk of the financing is already in place. A three billion euro initial investment by an undisclosed space enthusiast has the whole organization moving briskly toward success. Prices are expected to hold steady at four million dollars per guest, which includes the luxury accommodations at the spaceport and the training. The future of commercial space tourism has never looked brighter than it does today.

# Decision sparks dissent on donor debate

Half a century ago, the very idea of transplanting an organ from one person into another was considered by many as somewhat ghastly. Whispers of head transplants and Frankenstein-style monsters could be heard as people feared what might possibly come from such new technology. Today, countless people owe their lives to this relatively common form of surgery.
But are we prepared to use animals for their body parts instead? That is the question being asked as we look for new ways to meet the need for organ transplants.
The Australian National Health and Medical Research Council (NHMRC) has recently announced it would permit trials on ‘xenotransplantation’ – the process of replacing a person’s organs with those from another species. Given animals such as pigs have organs that are rather similar to our own, it could provide a way of saving the lives of those who would otherwise never find a compatible donor. Continue reading Decision sparks dissent on donor debate

# DNA thief goes green to feed

If you had a pair of boxes labelled ‘plant’ and ‘animal’, how challenging would it be to find items to put in each of them? Easy, you’d say! A frog could go into ‘animal’ because it chases and eats flies. You could put a daisy into the ‘plant’ box because it gets energy by absorbing light and not other organisms.

Where would you put the aquatic slug, Elysia chlorotica? Well, it’s a slug, so you’d assume it would get its energy by eating algae or plant material. Obviously it’s an animal. Yet its dusky green colouration reveals quite an interesting trick – this slippery gastropod can also soak up the sun to feed itself. Continue reading DNA thief goes green to feed

# How the emu got grounded

Old man emu isn’t well known for his swimming ability, nor is his cassowary cousin. The flightless African rhea can’t operate small aircraft, ostriches aren’t very good at teleportation and as large as the extinct New Zealand moa was, it’s unlikely it got there by jumping across the Tasman.

They are all related as a group of birds called ‘ratites’. Biologists from the Australian National University wondered just how it was that these birds managed to spread to different parts of the globe if they couldn’t fly. Yet the DNA of the moa revealed an interesting secret – its closest ancestor is a small South American bird called a ‘tinamous’. Continue reading How the emu got grounded

# Better pipes made flowers a blooming success

Flowering plants aren’t just pretty to look at; if they had never evolved, the human species probably wouldn’t have either. The brains of our primate ancestors grew large on a diet of fruit and flowers provided by a group of plants known as ‘angiosperms’.

But over 140 million years ago there was no such thing as a flower – plants such as conifers and ferns used other methods other than flowers to reproduce. A few million years after the last dinosaur walked the planet, flowering plants took over conifers as the most common type of tree. Today there are thought to be between 250 000 and 400 000 species of flowering plant. Continue reading Better pipes made flowers a blooming success

# Fleck specks keep track

Pinching the mug of the Science by Email editor should be considered a crime. Fortunately, it has been returned, and no harm was done. But if it could only talk! What adventures did it have? Where did it go? Who stole it in the first place?

If it had have been armed with a small device called a FLECK nano, such questions might have been answered.

A few years ago, CSIRO developed a wireless device called a FLECK, consisting of a central processing unit, flash memory and a radio transceiver. FLECKs could be outfitted with a range of different sensors to record conditions in their surroundings, such as the temperature or moisture. Continue reading Fleck specks keep track