Editors' Choice

Science  18 Dec 2015:
Vol. 350, Issue 6267, pp. 1488
  1. Tornado Forecasting

    Gaining momentum for anticipating storms

    1. H. Jesse Smith

    A 2011 tornado in Nebraska

    PHOTO © MIKE HOLLINGSHEAD/CORBIS

    Tornados cause many deaths and costly damage to property every year, so being able to predict them farther in advance could save both human lives and money. Gensini and Marinaro show that that tornadoes are more likely to occur when the base state of atmospheric angular momentum is low and less likely to occur when it is high. Differences in atmospheric angular momentum, expressed as the global wind oscillation, can explain nearly an order of magnitude of variability in boreal spring tornado occurrence in the United States during the period from 1994 to 2013. This observation thereby suggests a pathway to better springtime tornado forecasting.

    Mon. Weather Rev. 10.1175/MWR-D-15-0289.1 (2015).

  2. Cell Migration

    Moving forward by localized translation

    1. Beverly A. Purnell

    Proper development and morphogenesis requires many cells to coordinate movements that are influenced by local forces, or from the migration of cells under their own power. In mesenchymal cell migration, actin filaments at the front push the cell forward while the back portion is retracted. By comparing mRNA localization and translation rate in the forwardlocated protrusions relative to trailing section, Mardakheh et al. identify the mechanism by which front-back cell asymmetry is maintained. Protein translation in the front of the cell is critical to stabilize the protrusion and produce the cell's polarized morphology. Analyses reveal specific cis-regulatory mRNA UTR motifs and RNA-binding proteins, such as the exosome core complex, as important for cell migration asymmetry.

    Dev. Cell. 35, 344 (2015).

  3. Planetary Science

    What counts as a planet?

    1. Keith T. Smith

    In 2006, the International Astronomical Union formally defined the term “planet” in such a way that bodies such as Pluto, Ceres, and Eris do not qualify. The definition was controversial, partly because the criteria are somewhat subjective and cannot be directly applied to planets around other stars (exoplanets). Margot has proposed an alternative objective mathematical definition of a planet. Within our solar system, the calculation clearly separates the eight planets from all other bodies. It can also be calculated from data that are already available for 99% of known exoplanets. It remains to be seen whether the new metric will catch on.

    Astron. J. arXiv:1507.06300 (2015).

  4. Political Science

    Predicting protests via tweets

    1. Barbara R. Jasny

    Although many investigations have attempted to link the use of social media with protests, they have usually been based on events occurring in one country. Steinert-Threlkeld et al. collected nearly 14 million tweets and protest records from 16 countries in the Middle East and North Africa from 1 November 2010, through 31 December 2011, which includes the period of the Arab Spring protests. They studied the coordination of tweets (i.e., the progressive use of smaller numbers of protest-related hashtags by multiple users) and found that increased coordination was strongly associated with increased protests the next day. This was not the result of a few highly tweeted events or a few digital activists or international attempts to draw attention to the events.

    EPJ Data Sci. 10.1140/epjds/s13688-015-0056-y (2015).

  5. Lipid Biochemistry

    A parasite's phospholipid

    1. Caroline Ash

    Evolution of a new phospholid led Toxoplasma gondii to parasitism

    PHOTO: EYE OF SCIENCE/SCIENCE SOURCE

    The phospholipid repertoire used in animal cell membranes is surprisingly limited, but another candidate has emerged. During investigations on virulence in the ubiquitous animal and human protist parasite Toxoplasma gondii, Arroyo-Olarte et al. identified phosphatidylthreonine (PtdThr) as an abundant constituent. A small evolutionary accident seems to have allowed T. gondii to become parasitic by shifting from phosphatidylserine- to phosphatidylthreonine-based membranes. Although mutant parasites lacking PtdThr can replicate, they are paralyzed and neither able to enter nor exit host cells. PtdThr mutants provoke strong immune responses and look promising as vaccine candidates. Because the synthetic enzyme PtdThr synthase was also characterized, there is scope for drug interventions too.

    PLOS Biol. 10.13 71/journal.pbio.1002288 (2015).

  6. Psychology

    Reading minds across the ocean

    1. Gilbert Chin

    Natives of different cultures often have trouble figuring out what the other believes—a sought-after experience for the traveler visiting faraway lands, yet a hindrance for the immigrant adjusting to her new environment. Perez-Zapata et al. identify a high-level contributory factor by presenting social and cognitive scenarios to Australians (in English) and to Chileans (in Spanish). The cognitive scenarios depicting activities involving either Australians or Chileans were understood equally well by natives of both countries. In contrast, Australians more accurately inferred what one Australian believed about another Australian in comparison to a conversation between two Chileans; likewise, Chileans found it easier to read the minds of other Chileans.

    Cognition 146, 410 (2016).

  7. Policy Experiment

    Cashing in on clean air

    1. Brad Wible

    Exposure to air pollution early in life could undermine earnings as an adult. Isen et al. studied 5.7 million people born in hundreds of counties across the United States, within a few years before and after those counties reduced ambient levels of total suspended particulates (TSPs) under the Clean Air Act (CAA) in the early 1970s. U.S. Census Bureau data were used to link date and location of birth with labor market outcomes decades later. Although those born 1 to 3 years before the CAA improvements still enjoyed cleaner air beginning at ages one to three, they were exposed to more pollutants from conception until age one. Compared to them, those born after the CAA induced a 10% decline in TSP levels earned roughly 1% more at age 30, possibly due to improved cognitive ability and health.

    J. Polit. Econ., http://faculty.haas.berkeley.edu/rwalker/research/caalongtermhealth.pdf (2015).