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This issue features a special on the circular economy�, a term coined by Swiss architect-engineer Walter Stahel, who has been a leader in developing the concept of sustainability as applied to industrialized economies. In a Comment piece, Stahel outlines the key principles of a waste-free� world: reuse, repair, remanufacture and upgrading. The ultimate goal, he writes, is to recycle atoms. John Mathews and Hao Tan track Chinas progress towards a circular economy, a process that needs to be tracked using more sophisticated metrics, they suggest. In a third Comment, developmental psychologist Bruce Hood asks why we hoard possessions to enhance our social status and highlights the need to make recycled goods more socially desirable. Finally, Books & Arts focuses on how eco-design can make circular economy principles work. Cover art: Viktor Koen
The Chinese government’s professed commitment to transparency and responsiveness has had a rocky start. That bodes ill for the desire to attract the best science brains from around the world.
The country consumes the most resources in the world and produces the most waste — but it also has the most advanced solutions, say John A. Mathews and Hao Tan.
In linear economics, objects of desire from skyscrapers to paperclips are waste waiting to happen. Now, linearity is reaching the end of the line: designers are looking to the loop and redefining refuse as resource.
Enhancing synaptic connections between neurons in the brain's hippocampus that are normally activated during memory formation rescues memory deficits in a mouse model of early Alzheimer's disease. See Letter p.508
Migratory birds are declining globally. A broad study of European migratory birds finds that species that disperse widely during the non-breeding season are less likely to be in decline than are species with more restricted dispersion.
Alkenyl halides are some of the most useful building blocks for synthesizing small organic molecules. A catalyst has now allowed their direct preparation from widely available alkenes using the cross-metathesis reaction. See Article p.459
The finding that marine environments with high levels of host microbes have fewer viruses per host than when host abundance is low challenges a theory on the relative roles of lysogenic and lytic viral-survival strategies. See Article p.466
The presence of ice at two positions on opposite sides of the Moon suggests that the satellite's orientation was once shifted away from its present spin axis — a finding that has implications for the Moon's volcanic history. See Letter p.480
A cross-cultural experiment involving thousands of people worldwide shows that the prevalence of rule violations in a society, such as tax evasion and fraudulent politics, is detrimental to individuals' intrinsic honesty. See Letter p.496
One shortcoming of olefin metathesis has been that acyclic alkenyl halides could not be generated efficiently and stereoselectively; but now halo-substituted molybdenum alkylidene species are shown to be able to participate in high-yielding olefin metathesis reactions that afford acyclic 1,2-disubstituted Z-alkenyl halides.
An analysis of 24 coral reef viromes challenges the view that lytic phage are believed to predominate when the density of their hosts increase and shows instead that lysogeny is more important at high host densities; the authors also show that this model is consistent with predator–prey dynamics in a range of other ecosystems, such as animal-associated, sediment and soil systems.
The loss of the TP53 gene is often involved in the development of human cancer; here, the deletion of other genes in the vicinity is shown also to contribute to cancer progression in a mouse model.
Deep γ-ray observations of the Galactic Centre with arcminute angular resolution show traces of petaelectronvolt protons within the central ten parsecs of our Galaxy; the accelerator of these particles could have provided a substantial contribution to Galactic cosmic rays in the past.
Polar hydrogen deposits on the Moon provide evidence that its spin axis has shifted; analysis of the locations of these deposits and of the lunar figure suggests that the shift occurred as a result of changes in the Moon’s moments of inertia caused by a low-density thermal anomaly beneath the Procellarum region.
Incomplete premelting at the edges of monolayer colloidal crystals is triggered by a bulk solid–solid phase transition and truncated by a mechanical instability that induces homogeneous bulk melting of the crystal; these observations challenge existing theories of two-dimensional melting.
Synthesis of atomically precise zigzag edges in graphene nanoribbons is demonstrated using a bottom-up strategy based on surface-assisted arrangement and reaction of precursor monomers; these nanoribbons have edge-localized states with large energy splittings.
Variability in North African dust dispersal, which affects air quality and the amount of radiation reaching the ground, is captured by the wind patterns over the Sahara; climate models suggest a downward trend in dust concentration with increasing greenhouse gas emissions.
To test whether there is a relationship between the level of national corruption and the intrinsic honesty of individuals, a behavioural test of the honesty of people from 23 countries was conducted; the authors found that high national scores on an index of rule-breaking are linked with reduced personal honesty.
The genus Homo had considerably smaller cheek teeth, chewing muscles and jaws than earlier hominins; here, the introduction of raw but processed meat, from which energy could more easily be extracted, is shown to have possibly been responsible for this change.
Nuclear DNA sequences from Middle Pleistocene Sima de los Huesos hominins show they were more closely related to Neanderthals than to Denisovans, and indicate a population divergence between Neanderthals and Denisovans that predates 430,000 years ago.
Experiments in transgenic mouse models of early Alzheimer’s disease show that the amnesia seen at this stage of the disease is probably caused by a problem with memory retrieval from the hippocampus rather than an encoding defect.
Tracing the fate of circulating tumour cells by intravital two-photon lung imaging shows that tumours produce microparticles as they arrive and these migrate along the lung vasculature and are mostly taken up by interstitial myeloid cells, in a process that contributes to metastatic seeding; a minor subset of microparticles is engulfed by conventional dendritic cells, which are thought to contribute to the initiation of an anti-tumour immune response in lung-draining lymph nodes.
A known oncogene, MITF, resides in a region of chromosome 3 that is amplified in melanomas and associated with poor prognosis; now, a long non-coding RNA gene, SAMMSON, is shown to also lie in this region, to also act as a melanoma-specific survival oncogene, and to be a promising therapeutic target for anti-melanoma therapy.
The GCN2 kinase is shown to have a protective role in the regulation of intestinal inflammation during amino acid starvation in a mouse model of colitis.
PGC1α protects against kidney injury by upregulating enzymes that enhance nicotinamide adenine dinucleotide (NAD) and driving local accumulation of the fatty acid breakdown product β-hydroxybutyrate, which leads to increased production of the renoprotective prostaglandin E2.
A hybrid crystal structure of Mycobacterium smegmatis mycocerosic acid synthase, a multienzyme involved in the biosynthesis of mycobacterial branched-chain fatty acids, exemplifies the organization of fully-reducing polyketide synthases.