• Human sperm have been caught twirling in an elaborate dance. A new three-dimensional imaging technique has revealed spiraling movements that had previously only been inferred from two-dimensional data.

    The study, published today in the Proceedings of the National Academy of Sciences, describes the first large-scale, high-resolution recordings of human sperm in three dimensions, tracking more than 1,500 cells over several hours. Human sperm have eluded such detailed observation in the past. Their heads are just 3–4 micrometers long and can only be seen under high magnification, but the cells zoom around at up to 100 micrometers per second, ducking in and out of focus or darting out of range in an instant.

    “Our intention was to create something not bounded by conventional optics,” says Aydogan Ozcan, a bioengineer at the University of California, Los Angeles, who led the study. “This is the first observation of something that was entirely hidden.”

    The research team watched the wily sperm not with a conventional microscope lens, but with a light-sensing chip — measuring about 4 by 6 millimeters — placed underneath the translucent samples. A red light-emitting diode (LED) shines down on the sperm, forming a hazy shadow on the chip that follows the head of each cell as it moves horizontally. A second, blue LED illuminates the sperm from a different angle, casting shadows that change with each sperm head’s vertical position. Imaging cells en masse at about 90 frames per second allowed the researchers to characterize sperm movement more precisely than ever before.

    More than 90% of the sperm moved along slightly curved paths, wiggling their heads slightly from side to side. A small fraction — 4–5% — traveled in near-perfect spirals, forming helices between 0.5 and 3 micrometers in radius. Most of the helices were right-handed, but Ozcan says that it is too early to know whether this preference serves any physiological function.

    Susan Suarez, a sperm researcher at Cornell University in Ithaca, New York, is curious about the significance of the swimming patterns. She hopes that the method can be used to study sperm swimming under a wider range of physiological conditions, including the pH and fluid conditions encountered by the sperm en route to an egg.

    Chip-based imaging could one day lead to cheaper and more portable ways for fertility researchers to look at sperm movement, replacing costly computer systems that analyze microscope images. But Ozcan says that his technique — which can be used only on translucent materials — could also be used to study bacteria and other swimming microorganisms.

    David Brady, head of the Duke Imaging and Spectroscopy Program at Duke University in Durham, North Carolina, says that the sperm imaging is “a great demonstration of an application” in the growing field of lens-free imaging. Smaller and more powerful technologies have emerged in the past 5–10 years, he says, that have yet to cross over into mainstream experimental biology. The authors have come up with an application that will “get people talking”.

    Some sperm biologists think that the technique could also open up research avenues. “I’ve been trying to find a way to look at sperm — moving sperm — and this seems like it would be a good method,” says David Clapham of Boston Children’s Hospital in Massachusetts. “The beauty of this is that it’s done so quickly and on so many cells at once.” However, Clapham says, the method tracks only sperm heads, so can’t capture the complex tail movements that are crucial to understanding sperm function — and dysfunction.


  • power Integrations has announced a reference design kit for a 150W, 48V power supply for LED streetlights and other industrial / infrastructure lighting systems. The driver circuit is more than 93% efficient at 230VAC input and above 91% at 110VAC. The design delivers a system power factor of greater than 0.97, THD of less than 10%, and easily meets EN61000-3-2 C. Designs can be scaled from 75W to 400W, using the same platform, simply by choosing different HiperPFS (PFC) and HiperLCS (LLC) family members and sizing power components appropriately.

    The company’s RDK-292 reference design kit requires fewer than 125 components to implement the driver’s PFC, LLC and standby power supply circuits, resulting in low BOM cost and exceptional reliability. The design utilizes a combination of Power Integrations’ highly-integrated HiperPFS power-factor-correction IC and the HiperLCS resonant converter IC, which together save up to 35 components compared with conventional LLC solutions. HiperLCS also permits the use of smaller magnetics and output filter capacitors than typical LLC designs. The design incorporates a Qspeed merged PIN-Schottky diode as well, boosting CCM PFC efficiency by delivering greatly reduced diode recovery losses when compared with conventional ultra-fast silicon PFC diodes.

    For installations with remote lighting-control systems, the design implements highly-efficient standby power-supply functionality based on Power Integrations’ LinkSwitch-TN ICs. The addition of a CAPZero(tm) X-capacitor discharge IC delivers further power savings, reducing no-load consumption to around 800mW at 264VAC input.

    Andrew Smith, product marketing manager, Power Integrations, said: “LED lighting can deliver significant cost savings for municipalities and commercial/industrial enterprises, but these savings cannot be fully realized without efficient, reliable, low-cost driver circuits. Power Integrations offers a full range of products – showcased in RDK-292 – to give designers of high-power LED lighting systems a strong competitive edge.”

    The groundbreaking technology centers support demand for Cree products and services throughout China and demonstrate Cree’s commitment to accelerate broader market adoption of LED lighting. TEMPO Services provide LED lighting manufacturers a comprehensive suite of evaluation services for LED luminaires – ensuring customers have information needed to design and market quality LED products.

    “Cree delivers our customers end-to-end development support and the opening of our new technology centers in Shenzhen and Shanghai is further evidence of our commitment to their success,” said Tang Guoqing, senior advisor, Cree Hong Kong Limited. “TEMPO Services can give manufacturers competitive advantages by helping them avoid costly design mistakes and by providing access to a broad range of test environments that are, in many cases, cost-prohibitive for them to build and operate.”

    Effective LED luminaire thermal design is essential to ensure reliability and optimum performance. TEMPO Thermal Simulation predicts the thermal behavior of LED-based fixtures, including junction temperature, heat sink temperature, temperature profile and airflow profile. TEMPO SPOT gives customers access to complex, costly equipment to measure the photometric performance of luminaires and replacement lamps. Every TEMPO Service delivers an accurate, easy-to-understand TEMPO report that includes all testing results and relevant performance data.


  • Drive’s Seon Creedon is impressed by the design, feel and fuel efficiency of Hyundai’s latest estate model.

    Anybody who has ever put a bet on a horse will know that favourites don’t always win. And just because the favourite you backed didn’t win, doesn’t make your selection a bad horse; just that it was beaten by a horse in better form on the day.

    Backing favourites came to mind last week, while I tested the Tourer or Estate version of the Hyundai’s i40, which was favourite to win the Irish Car of the Year award last November. On the day, the majority of the Irish Motor Writers Association jury opted for the Kia Rio and, while Hyundai’s connections were naturally disappointed, they knew that their spacious car will have another day at the races, as it goes before the Irish car-buying public.

    First impressions are lasting and my initial and abiding impression of the i40, which replaces the Sonata, was the length of this estate.

    Like the Jaguar that I tested the previous week, the test car was black and Henry Ford’s favourite colour, coupled with two neat roof rails, gave the car an elongated look.

    Naturally, in a car this long there is plenty of boot space, with a useful luggage floor rail system and a ‘mini’ spare wheel. There are no parking sensors, but you do get a reversing camera, which is very cleverly located in the corner of the rear view mirror.

    The Jaguar has very attractive LED lights and while the LED lights in the i40 are a different shape to the Jaguar’s, they are also gorgeous. It looks like car designers are now working hard on giving us very attractive designs for LED lights.

    I haven’t driven many cars with 1.7 engines, but this diesel version was excellent and frugal also. Indeed, Hyundai hopes that this thrifty engine will be one of the car’s strong selling points and Hyundai’s Sarah Hayes says the firm is very happy with sales of the Tourer and Saloon versions.

    Although most people initially believed that stop-start technology would consume more fuel, it has been proven that this new technology is a fuel-saver. The stop-start technology also reduces C02 emissions and brings the i40 into the lowest tax band, which used to be 104, but was increased to 160 in the recent budget.

    Inside, the décor is predominantly black with a cream roof. There dash has a very attractive curvaceous design, which gives the interior a spacious feel. All the controls on the dash are easy to use and you get plenty of slave controls on the sporty-looking steering wheel.

    The only slightly annoying thing in the cabin is the electric handbrake, which, in my model, didn’t release automatically when I drove off, but then, I suppose, it’s better to be safe than sorry.

    Prices start at 26,495 for the Comfort model, while the high spec Executive model that I drove costs 27,995. Normally in Ireland we get the saloon version first, with the estate coming later, but Hyundai has done it differently this time, with the saloon model available now, for a starting price of 24,995.

    The i40 Tourer is a massive motor for a very competitive sector of Irish motor market. But I think it will be well able to take on the opposition and in horse racing parlance the car will run well on any kind of ground. And you won’t have to make many pit stops as it seems to go forever on a full tank of diesel.

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  • On Monday night, I caught myself, while waiting at a crosswalk, squinting at the oncoming traffic and studying the difference intensities of light coming off of car headlights. I was trying to figure out which headlights were LEDs and which ones were incandescents. I missed my signal to cross and had to wait for the next light change because of my musings.

    My musings were inspired by a 90-minute walk through a hilly region of the city led by Robin Marks. Robin, a biochemist, science journalist and former science tinkerer at the Exploratorium, started Discovery Street Tours this past July.

    The website describes the tours as “more than just a walking tour. It’s an urban investigation of the science under your feet, in your food, and in your life. You’ll demo the science for yourself with hands-on activities, eat some tasty treats, and meet other folks like yourself—curious, active, and a little beyond the ordinary.”

    Science got festive on the night of Sunday, December 11th as 18 of us, bundled against the cold and misting fog headed up 20th Street for the The Science of (Holiday) Light preview tour. Through the up-and-down mile and half route, we took frequent stops to admire holiday handiwork, discuss the history of holiday lights, view the different types and understand how our brains were taking in light signals.

    My favorite part of the tour was when we stopped at a corner house strung with both LED and incandescent holiday lights. We were encouraged to look closely and notice the difference in both the quality and brightness of light. While incandescent bulbs use a filament to produce light and heat, LEDs (light emitting diodes) are lower energy semi-conducters.

    LEDs shoot out light in a straight line. After learning this, I was able to identify the LED string of lights not only by the light but the crystal cut bulbs around the light that enabled the straight line of light to be refracted — making the iconic twinkling glow associated with holiday lights.

    As a nerd herder and being generally inquisitive about science, this was a very satisfying tour. I was able to ramble through the city taking in wonderful panoramic scenes in one instance and then turn around and look closer at the mundane with awe at how I was seeing it with new insight and understanding.

    My fellow tour-goers raised other questions about light and color, as our curiosity was further sparked by what we were seeing and learning. One conversation that got started involved pollinators; which insects and birds are attracted to the red over white flowers, and the effects the visible spectrum they see have on how they pollinate species of flowers.

    As this was a preview, the inquisitive can still put science in their step. Robin will be leading The Science of (Holiday) Light tour several more times in December, including Christmas Eve and the evening of Christmas Day. Tours start at 6:30pm and all the dates, more details and booking information can be found online.

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  • HOW many light bulbs in your house did the State Government pay for?

    And also the shower head and the funny energy monitor thing.

    But frankly, I’d rather the money was spent on something like … perhaps the hospital.

    If I take a trip into my son’s bedroom, again there are more gifts from the government.

    Their school bags were picked up at the Nambour Show. And I can’t tell you the number of pens I’ve collected over the years.

    It’s not just the State Government that seems to love to give handouts.

    We have Kevin Rudd to thank for insulation. Sorry, that wasn’t a “handout” that was a part of a stimulus package wasn’t it?

    I have a few gifts from our council too.

    Go to a council function and guaranteed you will be able to pick up some nice folders, pens and so on.

    And let’s not forget the many free activities the council organises.

    I love the free council buses over Christmas, but I doubt I’d use it enough to make me feel happy about the amount I pay on a public transport levy.

    I know the levy subsidises a lot more than the free buses, but I do wish instead of free buses we could do more to improve the bus network across the Coast.

    I think the tourists would also prefer something more regular and concise than a freebie.

    I’m one of those who signed up for the State Government and council-organised bicycle event things - where they hire a professional bike shop to offer a free course on how to maintain your bike. It was very interesting.

    And how my enjoyment of it justified its expense.

    I’d far rather that money was spent on building more bicycle paths so cycling from my house was a safe option for my family.

    Now I see the council is going to offer school students the opportunity to learn how to meditate at their local library.

    It’s supposed to be about teaching “kids to meditate their way to success” and help free their minds from worry.

    I wish they were offering free swimming lessons instead.

    But why the need to engage in PR stunts?

    There has to be a strong connection between a free activity and the overarching community benefit. Pens, light bulbs and meditation classes don’t do it for me.

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