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Cilial pumping is a powerful strategy used by biological organisms to control and manipulate fluids at the microscale. However, despite numerous recent advances in optically, magnetically and electrically driven actuation, development of an engineered cilial platform with the potential for applications has remained difficult to realize1–6. Here we report on active metasurfaces of electronically actuated artificial cilia that can create arbitrary flow patterns in liquids near a surface. We first create voltage-actuated cilia that generate non-reciprocal motions to drive surface flows at tens of microns per second at actuation voltages of 1 volt. We then show that a cilia unit cell can locally create a range of elemental flow geometries. By combining these unit cells, we create an active cilia metasurface that can generate and switch between any desired surface flow pattern. Finally, we integrate the cilia with a light-powered complementary metal–oxide–semiconductor (CMOS) clock circuit to demonstrate wireless operation. As a proof of concept, we use this circuit to output voltage pulses with various phase delays to demonstrate improved pumping efficiency using metachronal waves. These powerful results, demonstrated experimentally and confirmed using theoretical computations, illustrate a pathway towards fine-scale microfluidic manipulation, with applications from microfluidic pumping to microrobotic locomotion.

The neocortex is disproportionately expanded in human compared with mouse1,2, both in its total volume relative to subcortical structures and in the proportion occupied by supragranular layers composed of neurons that selectively make connections within the neocortex and with other telencephalic structures. Single-cell transcriptomic analyses of human and mouse neocortex show an increased diversity of glutamatergic neuron types in supragranular layers in human neocortex and pronounced gradients as a function of cortical depth3. Here, to probe the functional and anatomical correlates of this transcriptomic diversity, we developed a robust platform combining patch clamp recording, biocytin staining and single-cell RNA-sequencing (Patch-seq) to examine neurosurgically resected human tissues. We demonstrate a strong correspondence between morphological, physiological and transcriptomic phenotypes of five human glutamatergic supragranular neuron types. These were enriched in but not restricted to layers, with one type varying continuously in all phenotypes across layers 2 and 3. The deep portion of layer 3 contained highly distinctive cell types, two of which express a neurofilament protein that labels long-range projection neurons in primates that are selectively depleted in Alzheimer’s disease4,5. Together, these results demonstrate the explanatory power of transcriptomic cell-type classification, provide a structural underpinning for increased complexity of cortical function in humans, and implicate discrete transcriptomic neuron types as selectively vulnerable in disease.

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere1. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe2. Any changes in river floods would have lasting implications for the design of flood protection measures and flood risk zoning. However, existing studies have been unable to identify a consistent continental-scale climatic-change signal in flood discharge observations in Europe3, because of the limited spatial coverage and number of hydrometric stations. Here we demonstrate clear regional patterns of both increases and decreases in observed river flood discharges in the past five decades in Europe, which are manifestations of a changing climate. Our results—arising from the most complete database of European flooding so far—suggest that: increasing autumn and winter rainfall has resulted in increasing floods in northwestern Europe; decreasing precipitation and increasing evaporation have led to decreasing floods in medium and large catchments in southern Europe; and decreasing snow cover and snowmelt, resulting from warmer temperatures, have led to decreasing floods in eastern Europe. Regional flood discharge trends in Europe range from an increase of about 11 per cent per decade to a decrease of 23 per cent. Notwithstanding the spatial and temporal heterogeneity of the observational record, the flood changes identified here are broadly consistent with climate model projections for the next century4,5, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management. Analysis of a comprehensive European flood dataset reveals regional changes in river flood discharges in the past five decades that are consistent with models suggesting that climate-driven changes are already happening.

The human retina is unmyelinated, but structural similarities have been noted between Müller cells, the main glial cell type of retina, and oligodendrocytes, the myelin-forming cells of the central nervous system1. We now show that antibodies against myelin-associated glycoprotein, a minor component of central and peripheral myelin so far found only in myelin and myelin-forming cells2–4, also stain Müller cells. Immunoblot analysis of retinal proteins indicates that the antigen detected is myelin associated glycoprotein. These results suggest a closer relationship between Müller cells and oligodendrocytes than previously suspected and raise questions about the functional role of myelin-associated glycoprotein.

Here we describe Australia's first known Mesozoic mammal and the first known early Cretaceous mammal from Gondwanaland. Steropodon galmani n. gen. and sp., discovered in early Cretaceous sediments at Lightning Ridge, New South Wales, Australia, appears to represent an ornithorhynchid-like monotreme. This discovery represents the first record of a fossil mammal from Australia that is older than 22.4±0.05 Myr1,2and the specimen is, by more than 85Myr, the oldest known monotreme. As the oldest monotreme, it will necessitate a radical revision of present understanding about dental homology in the middle Miocene Obdurodon insignis, the only fossil monotreme previously known to have had teeth3. The structure of S. galmani supports one current view4that monotremes, one of three groups of living mammals (the other two being marsupials and placentals), are phylogenetically close to the other groups of living mammals.

A simple analogy is made between the tectonics of Asia and deformation in a rigidly indented rigid–plastic solid. India is analogous to the indenter and the great strike-slip faults correspond to slip lines. For various indentation geometries, the sense and linearity (or curvature) of strike-slip faults, convergence at the Burma arc and the existence of the Himalayan Burman Syntax, the conjugate strike-slip faults in Mongolia and the extension at the Baikal and Shansi graben can be predicted. Given the horizontal force necessary to support Tibet, an average shear stress of a few to several hundred bars along faults in Asia is predicted, corresponding to the yield stress of rigid–plastic material.

Combinations of global plate reconstructions reveal average velocities for the last 50 to 65 million years of 10 to 20 mm yr−1between the Hawaiian hotspot and those beneath Iceland, Tristan da Cunha, Réunion, St. Paul's Island, and Kerguelen. Therefore hotspots do not define a fixed reference frame. Uncertainties in these reconstructions are less than the errors incurred by assuming fixed hotspots and less than the differences among various proposed frames of reference of fixed hotspots1–3.

Cygnus X-3 is a poorly understood but interesting galactic X-ray source. It is unusual in that it shows variable low-state (Sv<1 Jy) radio emission1as well as spectacular radio flares (Sv∼20 Jy). The spectacular flares have long been interpreted as synchrotron emission from an expanding source2; more recent work3implies that Cyg X-3 may be one of the few identified radio jets in the Galaxy. Flux-density variations with a period of 4.8 h have been discovered at X-ray4and IR5wavelengths, and possibly at γ-ray energies6,7from 108eV to 1016eV. The X-ray emission is probably produced in a binary system composed of a low-mass star orbiting a compact object with an accretion disk and an accretion disk corona8. As interstellar absorption9(Av= 19) precludes study of the optical emission, the applicability of this model to Cyg X-3 rests heavily on analogy with other sources with similar X-ray properties (such as, 4U1822-37 and 4U2129+47). We report here observations with the Very Large Array (VLA) of Cyg X-3 at several radio wavelengths which show that the radio emission in its low state may be interpreted as arising entirely from the superposition of a series of flares that are wavelength dependent with an apparent period near the 4.8-h X-ray period10. A model of the source, in which each flare represents the injection of relativistic particles into a small volume which subsequently expands at constant velocity, is qualitatively consistent with the data.

The success of plate tectonics required an acceptance of continental drift, and thus a reinterpretation of the large-scale geological history of most of the Earth. But the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors, where buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity.

Reanalysis of early Tertiary magnetic anomalies on the Pacific plate south of the Campbell Plateau indicates that in early Tertiary time there was a previously unrecognized triple junction of the Pacific, the Antarctic, and a third plate now beneath the Bellingshausen sea. Corresponding revised parameters for Pacific–Antarctica motion do not require early Tertiary displacements within Antarctica or New Zealand, but suggest a change in direction of the Pacific plate over the hotspots of approximately the same sense and timing as the Hawaiian–Emperor bend.

The 1985 Chinese/British expedition to the Tibetan Plateau attempted to solve the question of the origin of the very thick crustal rocks in this region. Continuing northwards movement of the Indian plate over the past 38 Myr has given rise to severe folding and thrust faulting, causing crustal thickening by internal deformation. Previous collisions of microplate terranes derived from Gondwanaland occurred during Mesozoic times but the Kun Lun terrane of northern Tibet was already part of Laurasia by the Carboniferous.

Reconstruction of the major lithospheric plates 21 and 38 m.y. ago implies that linear island chains and aseismic ridges were not generated by localised sources of volcanism (hot spots) that have been fixed with respect to one another. If the linear volcanic chains are formed over mantle hot spots, the spots move at rates of 0.8 to 2 cm yr−1with respect to one another.

Downgoing slabs of lithosphere may exert a pull on the portions of plate left at the surface.

The relative motion between the plates on each side of the East African Rift Valley can be obtained from the opening of the Red Sea and the Gulf of Aden. The calculated direction of relative motion agrees well with fault plane solutions for earthquakes north of the equator.

Differences in the spectra of seismic surface waves provide important discriminants between underground explosions and earthquakes.

PALAEOMAGNETIC studies of late Cretaceous–early Tertiary red beds in southern Tibet indicate that they were magnetised at about 8°N and, therefore, that they subsequently moved north about 22° (ref. 1). Xiangyuan et al.1collected 12 samples across the thickness of red beds which overlies an early late-Cretaceous stratum (Tsu mulong group) in Linzhou. Fossils of late Cretaceous marine fauna were found within the red bed itself, and Foraminifera (Lockhatia sp.) of early Tertiary age were found near an outcrop of the volcanic assembly that unconformably overlies the red beds. Three of their samples were tested for stability using alternating field demagnetisation with an applied field of 50–300 oersted. No obvious secondary magnetisation was found. These red beds are north of the Indus–Tsangpo suture2. Xiangyuan et al.1compared the virtual geomagnetic pole from Tibet with those from rocks of the same age in India to show that this portion of Tibet was indeed not part of India in the late Cretaceous–early Tertiary. We show here that these new palaeomagnetic data also require about 2,500–3,500 km of north–south shortening in Asia since its collision with India.

IF reconstructions of plate tectonic movement based on magnetic anomaly data are found to be inconsistent with reconstructions based on palaeomagnetic data (see refs 1–3) it may indicate that one or more of the basic assumptions of the plate tectonic model is erroneous; the age or identification of a particular anomaly may be incorrect, the pole positions or sample ages may be unreliable, or there may be an error in assessing plate rigidity. We present an example of inconsistency between the two types of data and explore its implications for the chronology of magnetic reversals during the late Cretaceous and early Tertiary and for the age of the Deccan Traps.

IN February 1975, the Chinese Seismological Bureau successfully predicted a magnitude 7.3 earthquake near Haicheng, Liaoning Province. From their reports, it is obvious that many methods such as radon count, abnormal animal behaviour, seismic velocity, and tilt and telluric current anomalies were considered in making the long term prediction1. The short term prediction, however, was based primarily on foreshock activity2,3. That foreshocks were important in the prediction raises the question of how common they are. We here analyse the frequency of foreshocks before shallow earthquakes with magnitudes greater than 7. Our findings show that 44% of all large shallow events in the world from 1950 to 1973 had fore-shocks large enough to be teleseismidally recorded, and that 21% of the large earthquakes that occurred in China between 1900 and 1949 had foreshocks large enough to be noted in local records.

RHODOPSIN, the visual pigment of the retinal rods, is a doubly conjugated protein constituting about 80% of the total protein of the rod disk membrane in the frog1. The two prosthetic groups of rhodopsin are the visual chromophore retinal, and a single oligosaccharide chain comprising six sugar residues2,3

Current classification of birds recognizes four subclasses: the Archaeornithes, the Enantiornithes, the Odontornithes and the Neornithes. Three of these subclasses were proposed during the nineteenth century, but the Enantiornithes was proposed only five years ago, based on material from the Lecho Formation (Maas-trichtian) of Salt a Province in Argentina1. Further material from Asia (Mongolia) and North America (Mexico) has been referred to the Enantiornithes2, all of it from the Campanian. Now, in addition, a small tibiotarsus found in the Lower Cretaceous (Albian) of Queensland not only represents the first bony material of Mesozoic birds from Australia, but is also the first reported occurrence of an enantiornithine bird in the Lower Cretaceous.

We report here the first evidence of pterosaurs from Australia. Our report is based on fragmentary material from marine Lower Cretaceous sediments, of the Eromanga Basin, western Queensland. These fragments represent at least one pterosaur allied to the well-known Pteranodon1,2, and establish a new southern limit of distribution for Cretaceous flying reptiles.

GRIFFITHS1suggested that the computer fits of Australia and Antarctica2–4are not supported by geology and that a better fit can be obtained by moving Australia 250 km westwards along the coast of Antarctica in the computer fitted reconstructions. Griffiths's revised fit eliminates the overlap of the South Tasman Rise, now known to be of continental origin5, and the Iselin plateau. Laird et al.6showed that new geological evidence from Tasmania and East Antarctica favour such a revised reconstruction over the older computer fits. We present a slight modification to the fits given by Griffiths and by Laird et al. that, in addition, allows a good fit of magnetic anomaly lineations and fracture zone trends on the India7and Antarctic8plates (Fig. 1). This revised reconstruction thus implies that India and Australia have been parts of the same plate since the time of anomaly 22 (about 50 Myr ago). It also substantially reduces the size of the postulated Greater India9–11(Fig. 2).

The large width, the importance of crustal shortening and the likelihood of thick crust in the late Palaeozoic Hercynian (or Variscan) belt of southern Europe suggest a tectonic evolution analogous to the evolution of the Tibetan Plateau and its neighbouring Himalaya1, and of the Altiplano and other high plateaux of the Andes. Here we extend Dewey and Burke's analogy1of the Hercynian chain with Tibet to include the subsequent stage of pervasive normal faulting and crustal extension and thinning, which characterize the active tectonics of Tibet, parts of the high Andes, and the Basin and Range province of western North America. It appears that normal faulting and rifting also characterize the late Palaeozoic tectonic activity of the Hercynian chain.

Ion-specific channels in artificial membranes have been formed by the addition of gramicidin A1, alamethicin2, polyene antibiotics3and some proteins4to the solution surrounding the bilayer lipid membrane. Until now there have been no reports of single-ion channels in unmodified lipid membranes. We have now studied the electrical conductance of planar lipid bilayers membranes made of synthetic distearoylphosphorylcholine (DSPC). Current fluctuations of amplitude ∼1pA and duration ∼1s have been discovered at phase transition temperature, which shows that the appearance of ionic channels may be the result of lipid domain interactions. This would explain the dramatic increase in ion permeability observed in liposomes during phase transition. We suggest that these channels could conduct the transmembrane ionic current in biological membranes without the involvement of peptides and proteins.

IN accord with H. B. F. Dixon and M. P. Stack-Dunne1, who studied the behaviour of adrenocorticotropic hormone on a chromatographic column of a carboxy-type ion-exchange resin, we have found that the crude substance (I) prepared, according to the method of Lyons2, from dry hypophysis powder previously desiccated by acetone is different from the crude preparation (II) extracted from fresh hypophysis by the same acid–acetone solvent. These preparations show different behaviour when we attempt their purification.

IT has long been known that small round corpuscles may be found around the blood vessels of the central nervous system in subjects of advanced age. As the staining properties of these bodies are similar to those of starch, Virchow called them corpora amylacea. Several authors have examined them in attempts to determine their origin, but without definite result. The present contribution describes an attempt to define the morphology and some of the chemical properties of corpora amylacea, using the polarizing microscope as well as the periodic acid–leucofuchsin method1.