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Volume 506 Issue 7489, 27 February 2014

Excitons, plasmons and phonons are some of the better known quasiparticles � exotic entities that act in some respects like ordinary particles. New types do not come along all that often but here is one � a fundamentally new many-body particle named the ‘dropleton�. Mackillo Kira and colleagues have identified this new quantum entity, a quantum droplet created when four or more electrons and holes (electronic vacancies) form a tiny correlation bubble via the Coulomb attraction, in direct-gap semiconductors such as gallium arsenide. The cover illustrates the pair-correlation function g(r) of quantum droplets � the central peak of the correlation function shows that electrons and holes are likely to be co-located and the ripples show that otherwise they form regularly spaced shells. (Cover art: Brad Baxley.)

Editorial

  • Our obligation to keep the suffering of laboratory animals to a minimum — both in life and in death — does not apply only to mammals.

    Editorial

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  • A collaborative online mathematics project holds lessons for other disciplines.

    Editorial
  • Putting a private craft into space requires vision, hard work and a big dose of optimism.

    Editorial
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World View

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Research Highlights

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Seven Days

  • The week in science: US bolsters patent system; $25-billion pharma deal the biggest in 5 years; and Europe picks exoplanet-hunting mission for 2024 launch.

    Seven Days
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News

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Correction

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News Feature

  • Researchers are finding that online, crowd-sourced collaboration can speed up their work — if they choose the right problem.

    • Philip Ball
    News Feature
  • A powerful method for deducing microbial relationships has been edging its way into civil and criminal investigations. But courts should proceed with caution.

    • Shaoni Bhattacharya
    News Feature
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Comment

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Books & Arts

  • Sharon Lewin welcomes a book tracing how two men with HIV were functionally cured.

    • Sharon Lewin
    Books & Arts
  • Jay M. Pasachoff and Naomi Pasachoff appraise Alexander Borodin's solar-inspired opera.

    • Jay M. Pasachoff
    • Naomi Pasachoff
    Books & Arts
  • London-based music psychologist John Sloboda explores the subconscious connections and disjunctions between musicians and their audiences. He discusses his experiments on the 'emotional hotspots' experienced by listeners and the surprising power of improvisation.

    • Jascha Hoffman
    Books & Arts
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Correspondence

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News & Views

  • In a study that showcases the potential of semisynthetic drug design, structural modification of an existing antibiotic with little activity against Mycobacterium tuberculosis has generated a new class of effective antitubercular lead.

    • Clifton E. Barry
    News & Views
  • Might it be possible to create mirrors for space telescopes, using nothing but microscopic particles held in place by light? A study that exploits a technique called optical binding provides a step towards this goal.

    • David McGloin
    News & Views
  • Analyses of ependymoma brain tumours reveal a gene rearrangement in one subtype, but no DNA mutations in two others, suggesting that mechanisms for cancer initiation are broader than is typically thought. See Articles p.445 & p.451

    • Rogier Versteeg
    News & Views
    • Andrew Mitchinson
    News & Views
  • A new value for the atomic mass of the electron is a link in a chain of measurements that will enable a test of the standard model of particle physics with better than part-per-trillion precision. See Letter p.467

    • Edmund G. Myers
    News & Views
  • A common variant of the autophagy protein ATG16L1 is a risk factor for Crohn's disease. But the genetic alteration is revealed only when the protein is cleaved by the enzyme caspase 3 during cellular stress. See Article p.456

    • Arthur Kaser
    • Richard S. Blumberg
    News & Views
  • How tiny aerosol particles form and grow from vapours produced by vegetation has been a mystery. The finding that highly oxygenated products form directly from volatile organic compounds may offer the solution. See Letter p.476

    • Gordon McFiggans
    News & Views
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Article

  • Although genetically bland, the posterior fossa group A subgroup of ependymomas, found often in infants and associated with poor prognosis, exhibit widespread epigenetic alterations, namely a CpG island methylator phenotype; these tumours are shown to be susceptible both in vitro and in vivo to various compounds that target epigenetic modifications, such as DNA methylation and H3K27 tri-methylation.

    • S. C. Mack
    • H. Witt
    • M. D. Taylor
    Article
  • At least two-thirds of supratentorial ependymomas contain oncogenic fusions between RELA, the principal effector of nuclear factor-κB (NF-κB) signalling, and uncharacterized gene C11orf95; C11orf95–RELA fusion proteins translocate spontaneously to the nucleus to activate NF-κB target genes, and rapidly transform neural stem cells to form tumours in mice

    • Matthew Parker
    • Kumarasamypet M. Mohankumar
    • Richard J. Gilbertson
    Article
  • The Crohn’s disease risk-conferring T300A variant in the autophagy protein ATG16L1 increases its sensitivity to caspase-3-mediated cleavage; this decreases the induction of autophagy in response to metabolic stress or pathogen infection, leading to increased secretion of inflammatory cytokines.

    • Aditya Murthy
    • Yun Li
    • Menno van Lookeren Campagne
    Article
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Letter

  • The optical spectrum of the star SMSS J031300.36−670839.3 shows no evidence of iron; this, together with comparisons of the star’s observed element abundance pattern with those of models, means that SMSS J031300.36−670839.3 must have been seeded with material from a single supernova with an original mass about 60 times that of the Sun.

    • S. C. Keller
    • M. S. Bessell
    • P. Tisserand
    Letter
  • A very precise measurement of the magnetic moment of a single electron bound to a carbon nucleus, combined with a state-of-the-art calculation in the framework of bound-state quantum electrodynamics, gives a new value of the atomic mass of the electron that is more precise than the currently accepted one by a factor of 13.

    • S. Sturm
    • F. Köhler
    • K. Blaum
    Letter
  • Fast optical pulses create a plasma of electrons and holes in a semiconductor in which excitons (pairs of holes and electrons) and combinations of two excitons emerge; now a stable liquid-like droplet of electrons and holes has been detected and called a ‘dropleton’.

    • A. E. Almand-Hunter
    • H. Li
    • S. W. Koch
    Letter
  • The link between biogenic volatile organic compounds in the atmosphere and their conversion to aerosol particles is unclear, but a direct reaction pathway is now described by which volatile organic compounds lead to low-volatility vapours that can then condense onto aerosol surfaces, producing secondary organic aerosol.

    • Mikael Ehn
    • Joel A. Thornton
    • Thomas F. Mentel
    Letter
  • We lack thermal histories for magma reservoirs, but here the magma under Mount Hood (Oregon, USA) is shown to have been too cold to mobilize for most of the time it has been stored, which implies that magma mobilizes (at which point it can be imaged geophysically) very quickly prior to eruption.

    • Kari M. Cooper
    • Adam J. R. Kent
    Letter
  • Dark melanin pigment was detected in the fossilized skin of three distantly related marine reptiles (a leatherback turtle, mosasaur and ichthyosaur); benefits of thermoregulation and/or crypsis may have contributed to this melanisation, which therefore has implications for our understanding of how these animals may have lived.

    • Johan Lindgren
    • Peter Sjövall
    • Michael J. Polcyn
    Letter
  • Peptidoglycan is an essential structural component of the cell wall in the majority of bacteria, but the obligate intracellular human pathogen Chlamydia trachomatis was thought to be one of the few exceptions; here a click chemistry approach is used to label peptidoglycan in replicating C. trachomatis with novel d-amino acid dipeptide probes.

    • G. W. Liechti
    • E. Kuru
    • A. T. Maurelli
    Letter
  • A study investigating the mechanisms underlying lateral inhibition and lineage plasticity in the mouse small intestine crypts in vivo finds that crypt cells maintain a permissive chromatin state upon which a transcription factor acts to determine lineage specification, and this is the basis of lateral inhibition.

    • Tae-Hee Kim
    • Fugen Li
    • Ramesh A. Shivdasani
    Letter
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Retraction

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Erratum

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Addendum

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Feature

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Career Brief

  • University consortium aims to boost diversity using NSF funds.

    Career Brief
  • Government grant will use fellowships to increase the number of research managers.

    Career Brief
  • Race presents major barrier to advancement in the behavioural sciences, says study.

    Career Brief
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Futures

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Brief Communications Arising

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