This Week in Science

Science  08 Jun 2012:
Vol. 336, Issue 6086, pp. 1206
  1. Extending Quantum Memory

    Practical applications in quantum communication and quantum computation require the building blocks—quantum bits and quantum memory—to be sufficiently robust and long-lived to allow for manipulation and storage (see the Perspective by Boehme and McCarney). Steger et al. (p. 1280) demonstrate that the nuclear spins of 31P impurities in an almost isotopically pure sample of 28Si can have a coherence time of as long as 192 seconds at a temperature of ∼1.7 K. In diamond at room temperature, Maurer et al. (p. 1283) show that a spin-based qubit system comprised of an isotopic impurity (13C) in the vicinity of a color defect (a nitrogen-vacancy center) could be manipulated to have a coherence time exceeding one second. Such lifetimes promise to make spin-based architectures feasible building blocks for quantum information science.

  2. To the Next Level

    CREDIT: KEVIN GOTRIK

    Block copolymers will spontaneously separate into a range of microstructures that depend on the polymer block lengths and chemical compositions, and have been used as a templating material because one can selectively etch or functionalize one of the blocks. However, creating a template that is more than one layer thick is challenging. Tavakkoli K. G. et al. (p. 1294) used an array of posts to provide independent and simultaneous control of the morphology and orientation of two layers of block copolymers and were able to create local variations in the curvature and spacing of the domains.

  3. From Long to Short

    When you play a string instrument, you raise the frequency, or pitch, of the note by shortening the vibrating portion of the string: Drop the length in half, and you hear a harmonic at double the frequency. It is possible to do essentially the same thing with light waves by using selective excitation and relaxation processes of the electrons in crystals or high-pressure gases through which the beam of light is directed to produce light harmonics. Over the past decade, researchers have been optimizing the conversion of red light to the far edge of the ultraviolet, which corresponds to tens of harmonics. Popmintchev et al. (p. 1287) now show that mid-infrared light can undergo a process in high-pressure gas to generate ultrahigh harmonics up to orders greater than 5000 in the x-ray regime.

  4. Hammering Home the Lesson

    CREDIT: SILKE BARON

    Stomatopods are marine crustaceans that use hammerlike claws for defense and to attack their prey. The claws undergo repeated high-velocity and high-force impacts. Weaver et al. (p. 1275; see the Perspective by Tanner) used a variety of techniques to examine the structure, mechanical behavior, and toughening mechanisms of the claw of the Peacock Mantis shrimp. The claw's composite structure is optimized for toughness, which helps to prevent the complete failure that might arise from the claw's repetitive hammering.

  5. No Shock Ahead of the Sun

    The boundary of the heliosphere is the region where the solar wind interacts with interstellar space, and it marks the edge of our solar system. Based on observations from NASA's Interstellar Boundary Explorer, McComas et al. (p. 1291, published online 10 May; see the Perspective by Redfield) determined values for local interstellar parameters—such as speed, direction, and temperature—and show that these and other recent constraints are not consistent with a bow shock ahead of the heliosphere, as previously believed.

  6. Pluses and Minuses

    Because of their high surface area and tunable electronic structure, nanoparticles are of interest for next-generation photocatalysis and light-harvesting applications. Many of these applications involve electron transfer events at the particle surface after light absorption. Schrauben et al. (p. 1298) now show, through a series of radical trap kinetic studies, that proton transfer can concurrently accompany electron transfer at the solvent interfaces of two common nanoparticle formulations (oxides of titanium and of zinc). The results may help in the optimization of particle structure and energetics.

  7. The Rains of Change

    Approximately 500 to 400 thousand years ago, a fundamental change in the nature of glacial cycles occurred, including a shift to larger amplitude variations in atmospheric carbon dioxide concentrations and global temperatures. Meckler et al. (p. 1301, published online 3 May; see the Perspective by Kurita) present a stalagmite record from Borneo which provides a record of precipitation from 550,000 to 200,000 years ago. The amount of regional precipitation was similar during all four of the interglacials during that interval, and drying events during glacial terminations corresponded with cooling events in high northern latitudes.

  8. Actin Up

    Actomyosin interactions lie at the heart of fundamental cellular processes—including morphogenesis, establishment of polarity, and overall motility—but the general principles driving the spatiotempotal orchestration of these interactions have remained elusive. Working in vitro, using micropatterned substrates, Reymann et al. (p. 1310) demonstrate that myosins can use a “selection orientation” mechanism to pull selectively on actin filaments, contract the actin network and disassemble it, or walk on the filaments, align them, allow their growth, and control filament orientation.

  9. The Mycobiome

    In the past few years, much attention has been given to the trillions of bacterial inhabitants in our guts and the myriad of ways in which they influence our overall health. But what about fungi? Iliev et al. (p. 1314) now report that mice and humans, along with several other mammals, contain a resident intestinal population of fungi. Deletion of Dectin-1, which acts as a major innate immune sensor for fungi, led to enhanced susceptibility and worse pathology in a chemically induced model of colitis in mice. A polymorphism in the gene that encodes Dectin-1 has been observed in patients with ulcerative colitis, which hints that, besides the traditional bacterial microbiome, alterations in the “mycobiome” may also play a role in health and disease.

  10. Keeping Mitochondria in the Pink

    Pink1 is a mitochondrial kinase, and loss of Pink1 function in flies and mice results in the accumulation of inefficient mitochondria. In a screen for modifiers of the Parkinson-associated gene, pink1, Vos et al. (p. 1306, published online 10 May; see the Perspective by Bhalerao and Clandinin) identified the fruit fly homolog of UBIAD1, “Heix.” UBIAD1 was localized in mitochondria and was able to convert vitamin K1 into vitamin K2/menaquinone (MK-n, n the number of prenylgroups). In bacteria, vitamin K2/MK-n acts as an electron carrier in the membrane and, similarly, in Drosophila, mitochondrial vitamin K2 appeared to act as an electron carrier to facilitate adenosine triphosphate production. Fruit flies that lack heix showed severe mitochondrial defects that could be rescued by administering vitamin K2.

  11. Keeping Baby Safe

    Because half the genes from a developing fetus are inherited from the father, from the mother's perspective, a fetus is “foreign.” How, then, does the maternal immune system tolerate the fetus? Nancy et al. (p. 1317) found that careful regulation of cellular recruitment signals allowed for fetal tolerance in mice. Although high numbers of T cells localized to the myometrium layer of the uterine wall in pregnant mice, very few T cells were found in the decidua, the uterine tissue that encapsulates the fetus and placenta. Thus, in pregnancy, regulation of immune cell localization may allow for organ-specific immune tolerance.

  12. Honey Bees Beware of the Mite

    CREDIT: ETHEL VILLALOBOS

    The emergence of a virulent form of a viral disease that has long been associated with the world-wide death of honey bees has occurred in the Hawaiian archipelago. Martin et al. (p. 1304) exploited this unique situation to study the mechanisms behind the emergence. Honey bee populations have long been established on the isolated Hawaiian Islands but only recently have some islands become infested with the Varroa mite. This mite has selected for a single viral pathogen-deformed wing virus among the honey bee population, with the appearance of a single dominant virus strain, which has now spread worldwide. Thus, a normally benign viral pathogen has become one of the most widely distributed and contagious insect viruses on the planet.

  13. Protecting Against a Barrier Breach

    In order to coexist peacefully, a “firewall” exists that keeps the commensal bacteria that reside in our intestines and associated lymphoid tissue contained. Several diseases and infections, however, lead to a breach in this barrier, which leads to chronic inflammation and pathology. Sonnenberg et al. (p. 1321) found that in mice, innate lymphoid cells (ILCs) are critically important for the anatomical containment of commensal bacteria in an interleukin-22 (IL-22)–dependent manner. ILC depletion or blockade of IL-22 led to loss of bacterial containment and systemic inflammation.

  14. Establishing an Enteric Infection

    Complex and highly regulated interactions are required to keep the peace between the bacteria that reside in our gut and the immune system. How do pathogenic bacteria, such as the strains of Escherichia coli that cause gastroenteritis, get a foothold to establish an infection, and what is the role of resident bacteria in this process? Kamada et al. (p. 1325, published online 10 May; see the Perspective by Sperandio) infected mice orally with Citrobacter rodentium and found that mice with normal commensal microflora, which were better able to contain the infection than mice that lacked the commensals, which were not able to clear the infection.

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