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Diminutive dinosaur stalked the Arctic

Fossils of a pint-sized tyrannosaur from Alaska suggests seasonal variation may have influenced its body size.

• Alexandra Witze

12 March 2014

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70-million-year-old Arctic tyrannosaur

The newly discovered Nanuqsaurus may be the first uncontested example of a pint-sized tyrannosaur

KAREN CARR

High above the Arctic Circle, along an Alaskan river, palaeontologists have unearthed fossils of the first known tyrannosaur species at either pole.

• Co-author of paper on acid-bath stem cells calls for its retraction
• Grey wolf's return sparks debate over predators' role in ecosystems
• Sun's passage through dark-matter disk could trigger mass extinctions

The new animal comes from so far north that it is named Nanuqsaurushoglundi, after the Inupiat word for polar bear (nanuq). Its existence near the top of the world shows that relatives of Tyrannosaurus rex survived and even thrived in extreme polar environments, some 70 million years ago.

Perhaps more significantly, Nanuqsaurus may be the first uncontested example of a pint-sized tyrannosaur. In life, the Alaskan dinosaur measured some 7 metres long — small when compared to T. rex, which stretched 12 metres from nose to tail.

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http://www.nature.com/news/diminutive-dinosaur-stalked-the-arctic-1.14859

Artificial Muscles from Fishing Line and Sewing Thread

 

Science 21 February 2014:Vol. 343 no. 6173 pp. 845-846 
DOI: 10.1126/science.1250471
PERSPECTIVE

MATERIALS SCIENCE

Fibers Do the Twist

1. Jinkai Yuan, 
2. Philippe Poulin

+Author Affiliations

1. Centre de Recherche Paul Pascal, CNRS, Université de Bordeaux, 115 Avenue Schweitzer, 33600 Pessac, France.

1. E-mail: poulin@crpp-bordeaux.cnrs.fr

In a rubber band–powered airplane, a pretwisted band untwists when the hook used to initially balance its torque is released (see the figure). Such an actuation is based on the elastic recovery of the stretched polymer chains. The material has to be mechanically retwisted to operate but the method is simple and efficient, because the rubber band delivers almost as much energy as needed to twist it. Unfortunately, soft rubber cannot easily provide large stress and cannot be used in modern applications such as robotics, artificial muscles, smart textiles, and new medical devices. But as Haines et al. show on page 868 of this issue (1), the concept of twisted fibers can nevertheless be useful in demanding actuator applications.

http://www.sciencemag.org/content/343/6173/845.summary

Science 21 February 2014: 
Vol. 343 no. 6173 pp. 868-872 
DOI: 10.1126/science.1246906
REPORT

Artificial Muscles from Fishing Line and Sewing Thread

1. Carter S. Haines1, 
2. Márcio D. Lima1, 
3. Na Li1, 
4. Geoffrey M. Spinks2, 
5. Javad Foroughi2, 
6. John D. W. Madden3,
7. Shi Hyeong Kim4, 
8. Shaoli Fang1, 
9. Mônica Jung de Andrade1, 
10. Fatma Göktepe5, 
11. Özer Göktepe5,
12. Seyed M. Mirvakili3, 
13. Sina Naficy2, 
14. Xavier Lepró1, 
15. Jiyoung Oh1, 
16. Mikhail E. Kozlov1, 
17. Seon Jeong Kim4,
18. Xiuru Xu1,6, 
19. Benjamin J. Swedlove1, 
20. Gordon G. Wallace2, 
21. Ray H. Baughman1,*

+Author Affiliations

1. ¹The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083, USA.
2. ²Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales 2522, Australia.
3. ³Department of Electrical and Computer Engineering and Advanced Material and Process Engineering Laboratory, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
4. ⁴Center for Bio-Artificial Muscle and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
5. ⁵Department of Textile Engineering, Çorlu Engineering Faculty, Namık Kemal University, Çorlu-Tekirdağ, Turkey.
6. ⁶Alan G. MacDiarmid Institute, Jilin University, Changchun 130012, China.

1. ↵*Corresponding author. E-mail: ray.baughman@utdallas.edu

• ABSTRACT
• EDITOR'S SUMMARY

The high cost of powerful, large-stroke, high-stress artificial muscles has combined with performance limitations such as low cycle life, hysteresis, and low efficiency to restrict applications. We demonstrated that inexpensive high-strength polymer fibers used for fishing line and sewing thread can be easily transformed by twist insertion to provide fast, scalable, nonhysteretic, long-life tensile and torsional muscles. Extreme twisting produces coiled muscles that can contract by 49%, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram of muscle weight, similar to that produced by a jet engine. Woven textiles that change porosity in response to temperature and actuating window shutters that could help conserve energy were also demonstrated. Large-stroke tensile actuation was theoretically and experimentally shown to result from torsional actuation.

http://www.sciencemag.org/content/343/6173/868

Paying Graduate School's Mental Toll

Science Home » Science Careers » Career Magazine » Previous Issues » 2014 » February 04

Life and Career

Paying Graduate School's Mental Toll

By

Carrie Arnold

February 04, 2014

About 60% of graduate students said that they felt overwhelmed, exhausted, hopeless, sad, or depressed nearly all the time. One in 10 said they had contemplated suicide in the previous year.

Like nearly all science graduate students, chemistry blogger See Arr Oh was no stranger to stress. But one afternoon during his third year of a Ph.D. program in organic chemistry, as he sat in his car, he decided the stress might actually be killing him. "All of a sudden I would just be blurred out and tense all over. Everything just seemed to rush at me at once," he says. He went to the emergency room and was told he was suffering from panic attacks.

http://sciencecareers.sciencemag.org/career_magazine/previous_issues/articles/2014_02_04/caredit.a1400031

Science 24 January 2014: 
Vol. 343 no. 6169 p. 357 
DOI: 10.1126/science.343.6169.357

• NEWS & ANALYSIS

U.S. SPENDING

NIH Is Losing Its Funding Edge, 2014 Budget Suggests

1. Jeffrey Mervis

The 2014 budget suggests that the National Institutes of Health (NIH) is losing its place as first among equals when Congress has additional money to spend on research. Agencies that support the physical sciences grew much faster than did NIH, which receives nearly half of all federal research dollars, and some analysts think that pattern could repeat in 2015.

http://www.sciencemag.org/content/343/6169/357

How do animals see color?

Science 24 January 2014: 
Vol. 343 no. 6169 pp. 381-382 
DOI: 10.1126/science.1249614

• PERSPECTIVE

PHYSIOLOGY

Extraordinary Color Vision

1. Michael F. Land, 
2. Daniel Osorio

+Author Affiliations

1. School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.

1. E-mail: d.osorio@sussex.ac.uk

How do animals see color? We may never know how another animal experiences red or blue, but we do know that sensitivity to ultraviolet light allows bees to see patterns on flowers where we see plain yellow or white. In fact, bee and human color vision are much alike. Both have three spectral types of photoreceptor whose signals are compared by neural “opponent” mechanisms, which are sensitive to the relative amounts of light at different wavelengths, allowing the animal to distinguish the spectrum of a light source from its brightness. Thomas Young (1) recognized in 1802 that having multiple receptors each with a different spectral sensitivity at each point in the image is essential for color vision, but inevitably impairs spatial resolution. He proposed three spectral receptors as the likely compromise. In fact, theory predicts that two to four receptor types are optimal for discriminating the spectra of natural materials and maximizing the number of objects that could be distinguished by color (2). The eyes of many animals seem to follow these principles, with a retina containing two to four spectral receptors combined with a neural mechanism to compare the responses of different receptor types (the color opponent process). It is therefore fascinating to find an animal that sees color in a fundamentally different way, as reported by Thoen et al. on page 411 of this issue (3).

http://www.sciencemag.org/content/343/6169/381

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Science 24 January 2014: 
Vol. 343 no. 6169 pp. 411-413 
DOI: 10.1126/science.1245824

REPORT

A Different Form of Color Vision in Mantis Shrimp

1. Hanne H. Thoen1,*, 
   
2. Martin J. How1, 
   
3. Tsyr-Huei Chiou2, 
   
4. Justin Marshall1

+Author Affiliations

1. ¹Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia.
2. ²Department of Life Sciences, National Cheng Kung University, Tainan City 70101, Taiwan, Republic of China.

1. ↵*Corresponding author. E-mail: h.thoen@uq.edu.au

• ABSTRACT
• EDITOR'S SUMMARY

One of the most complex eyes in the animal kingdom can be found in species of stomatopod crustaceans (mantis shrimp), some of which have 12 different photoreceptor types, each sampling a narrow set of wavelengths ranging from deep ultraviolet to far red (300 to 720 nanometers) (1–3). Functionally, this chromatic complexity has presented a mystery (3–5). Why use 12 color channels when three or four are sufficient for fine color discrimination? Behavioral wavelength discrimination tests (Δλ functions) in stomatopods revealed a surprisingly poor performance, ruling out color vision that makes use of the conventional color-opponent coding system (6–8). Instead, our experiments suggest that stomatopods use a previously unknown color vision system based on temporal signaling combined with scanning eye movements, enabling a type of color recognition rather than discrimination.

http://www.sciencemag.org/content/343/6169/411