Editors' Choice

Science  16 Jun 2017:
Vol. 356, Issue 6343, pp. 1135
  1. Geophysics

    Finding foreshocks in the damage zone

    1. Brent Grocholski

    Damage done by a 2005 earthquake in Balakot, Pakistan

    PHOTO: AGENCJA FOTOGRAFICZNA CARO/ALAMY STOCK PHOTO

    Foreshocks are small earthquakes that precede much larger and more damaging earthquakes. The role that these small quakes play in nucleating the mainshock is unclear, but unraveling the relationship could provide clues about future earthquakes. Savage et al. obtained precise locations of foreshocks and aftershocks from the 2011 earthquake in Prague, Oklahoma. The foreshocks occurred in a broad region known as the damage zone before localizing near the main fault rupture. This behavior suggests that determining the precise location of foreshocks may be a promising tool for earthquake forecasting.

    Geophys. Res. Lett. 10.1002/2017GL073226 (2017).

  2. Stem Cells

    Immune control of hair growth

    1. Lisa D. Chong

    Hair follicles in mammalian skin undergo cycles of quiescence and regeneration. Hair follicle stem cells play a role in the regeneration phase. Ali et al. have found that regulatory T cells (Tregs), immune cells known to suppress inflammation, colocalize with stem cells in hair follicles. In a mouse model of hair regeneration, depletion of Tregs reduced hair growth. Analysis of gene expression revealed that Tregs promote the proliferation and differentiation of hair follicle stem cells. Tregs express a high level of Jagged, a ligand of the cell-cell communication system called the Notch signaling pathway that controls stem cell self-renewal and differentiation. The findings may have implications for treating individuals with alopecia areata, a hair loss condition.

    Cell 10.1016/j.cell.2017.05.002 (2017).

  3. Psychology

    Thinking about what others believe is hard work

    1. Gilbert Chin

    In a remarkable set of studies, Powell and Carey marry two previously unlinked lines of research. Executive function refers to the ability to make decisions, such as being able to switch from pressing the keyboard down (up) arrow when seeing a down (up) arrow on the computer screen to pressing the up (down) arrow when seeing a down (up) arrow. A person's ability to carry out such a task diminishes after being forced to exercise self-control (for example, for a child, waiting to open a box of toys). Theory of mind involves predicting another's behavior on the basis of understanding that person's beliefs. After suffering through the delayed-gratification exercise, 4- and 5-year-old children displayed impaired theory-of-mind capabilities.

    Cognition 164, 150 (2017).

  4. Development

    TET function in development

    1. Beverly A. Purnell

    In development, cell fate commitment enables the generation of the body's specialized cells. When one fate is targeted, other paths must be prevented. DNA methylation of CpG dinucleotides is key for such molecular repression. However, the erasure of DNA methylation is also critical in development and occurs at specific times, such as during embryonic postimplantation. The ten-eleven translocation (TET) genes perform this role. Khoueiry et al. now identify a methylation-independent role for TET1 to repress genes involved in the differentiation of epiblast and extraembryonic ectoderm through regulation of the transcriptional repressor JMJD8. Embryonic defects result if TET1 is removed. Hence, the well-known demethylase has critical functions in normal development through both catalytic and noncatalytic activities.

    Nat. Gen. 10.1038/ng.3868 (2017).

  5. Animal Cognition

    I know what you know

    1. Sacha Vignieri

    Dogs recognize that individuals have distinct perspectives.

    PHOTO: GOLDENKB/ISTOCKPHOTO

    Theory of mind involves recognizing that others have a distinct perspective. Such an ability is difficult to identify in species that cannot tell you about their thoughts, but research over the past decade or so has shown that it is not unique to humans, being present in at least apes and corvids. Dogs, which coevolved with humans, are excellent at reading our cues but have not been shown experimentally to “read” our minds. Catala et al. tested pet dogs for their ability to recognize when a particular observer has important knowledge through a classic knower-guesser test. They found that dogs followed the gaze of an observer whom they saw witness the hiding of a reward, rather than one who was guessing about its location. Thus, the dogs recognized that the observer knew something they did not, and that it was of value to pay attention to the information conveyed. This recognition of other knowledge is a first step toward a full theory of mind, an ability that would be adaptive across the animal kingdom.

    Anim. Cogn. 10.1007/s10071-017-1082-x (2017).

  6. Optical Imaging

    Revealing the hidden movers

    1. Ian S. Osborne

    Radar and lidar use pulses of electromagnetic radiation (typically microwaves or laser light) to track and range stationary or moving objects. However, when the object is obscured or hidden from view within a scattering medium, these technologies are ineffective. Akhlaghi and Dogariou have devised an imaging process that can track a hidden target as it moves within a scattering medium. Illuminating one side of the scattering medium with coherent light creates a speckle pattern on the other side. By monitoring changes in the speckle pattern, they show that the spatial and temporal movement of the target can be reconstructed. The technique could find application in biomedical imaging and remote sensing, as well as being applicable to other areas such as acoustics and microwaves.

    Optica 4, 447 (2017).

  7. Molecular Devices

    Bipolar light-emitting junctions

    1. Phil Szuromi

    Molecular junctions formed from Ru(bpy)3 oligomers (bpy, 2,2′-bipyridine) transition with increasing thickness from transporting electrons to emitting light. Tefashe et al. used electrochemical deposition to grow Ru(bpy)3 oligomers along with PF6 counterions on conducting carbon, which was then capped with conducting carbon to form a junction. Films thicker than 4 nm emitted light at wavelengths between 600 and 900 nm for biases above 2.7 V. Unlike previous devices based on Ru(bpy)3, the emission is bipolar (occurs for both positive and negative bias) and has a rapid onset (5 ms) and long persistence (10 hours). The authors argue that both hole and electron injection occur through a resonant process involving a metal-to-ligand charge transition.

    J. Am. Chem. Soc. 10.1021/jacs.7b02563 (2017).

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