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One of the most famous examples of adaptive radiation is that of the Galápagos finches, where skull morphology, particularly the beak, varies with feeding ecology. Yet increasingly studies are questioning the strength of this correlation between feeding ecology and morphology in relation to the entire neornithine radiation, suggesting that other factors also significantly affect skull evolution. Here, we broaden this debate to assess the influence of a range of ecological and life history factors, specifically habitat density, migration, and developmental mode, in shaping avian skull evolution. Using 3D geometric morphometric data to robustly quantify skull shape for 354 extant species spanning avian diversity, we fitted flexible phylogenetic regressions and estimated evolutionary rates for each of these factors across the full dataset. The results support a highly significant relationship between skull shape and both habitat density and migration, but not developmental mode. We further found heterogenous rates of evolution between different character states within habitat density, migration, and developmental mode, with rapid skull evolution in species which occupy dense habitats, are migratory, or are precocial. These patterns demonstrate that diverse factors impact the tempo and mode of avian phenotypic evolution, and that skull evolution in birds is not simply a reflection of feeding ecology.Impact summaryAlmost 200 years ago, Darwin found that the beaks of Galápagos finches were different shapes in birds with different diets. Nowadays, it is well established that phylogeny, allometry, and ecology can also be key factors in shaping skulls. Yet, the influence of specific aspects of ecology, as well as life history, on morphological evolution remain poorly constrained. Here, we examined whether three novel factors also influence the shape of bird skulls and rates of evolution: habitat density, migration, or developmental mode. To do so, we combine high resolution 3D quantification of skull shape with dense taxonomic sampling across living birds. Our analyses revealed that skull shape varies in birds based on the density of vegetation in their habitats and on the extent to which they migrate. However, how independent birds are when they are born does not appear to influence overall skull shape. Despite these differences in how much they influence the shape of the skull, habitat density, migration and life history all influence the rate at which bird skulls evolve. Birds evolved fastest if they live in densely vegetated habitats, migrate long distances, or are precocial. These results add to the growing body of evidence that skull evolution in birds is impacted by a diverse range of factors, and suggests that habitat density, migration and life history should be considered in future analyses on drivers of phenotypic evolution.

Notosuchians are an extinct clade of terrestrial crocodyliforms with a particularly rich record in the late Early to Late Cretaceous (approx. 130–66 Ma) of Gondwana. Although much of this diversity comes from South America, Africa and Indo-Madagascar have also yielded numerous notosuchian remains. Three notosuchian species are currently recognized from the early Late Cretaceous (approx. 100 Ma) Kem Kem Group of Morocco, including the peirosauridHamadasuchus rebouli. Here, we describe two new specimens that demonstrate the presence of at least a fourth notosuchian species in this fauna.Antaeusuchus taouzensisn. gen. n. sp. is incorporated into one of the largest notosuchian-focused character-taxon matrices yet to be compiled, comprising 443 characters scored for 63 notosuchian species, with an increased sampling of African and peirosaurid species. Parsimony analyses run under equal and extended implied weighting consistently recoverAntaeusuchusas a peirosaurid notosuchian, supported by the presence of two distinct waves on the dorsal dentary surface, a surangular which laterally overlaps the dentary above the mandibular fenestra, and a relatively broad mandibular symphysis. Within Peirosauridae,Antaeusuchusis recovered as the sister taxon ofHamadasuchus. However, it differs fromHamadasuchuswith respect to several features, including the ornamentation of the lateral surface of the mandible, the angle of divergence of the mandibular rami, the texture of tooth enamel and the shape of the teeth, supporting their generic distinction. We present a critical reappraisal of the non-South American Gondwanan notosuchian record, which spans the Middle Jurassic–late Eocene. This review, as well as our phylogenetic analyses, indicate the existence of at least three approximately contemporaneous peirosaurid lineages within the Kem Kem Group, alongside other notosuchians, and support the peirosaurid affinities of the ‘trematochampsid’Miadanasuchus oblitafrom the Maastrichtian of Madagascar. Furthermore, the Cretaceous record demonstrates the presence of multiple lineages of approximately contemporaneous notosuchians in several African and Madagascan faunas, and supports previous suggestions regarding an undocumented pre-Aptian radiation of Notosuchia. By contrast, the post-Cretaceous record is depauperate, comprising rare occurrences of sebecosuchians in north Africa prior to their extirpation.

The finished sequence of human chromosome 10 comprises a total of 131,666,441 base pairs. It represents 99.4% of the euchromatic DNA and includes one megabase of heterochromatic sequence within the pericentromeric region of the short and long arm of the chromosome. Sequence annotation revealed 1,357 genes, of which 816 are protein coding, and 430 are pseudogenes. We observed widespread occurrence of overlapping coding genes (either strand) and identified 67 antisense transcripts. Our analysis suggests that both inter- and intrachromosomal segmental duplications have impacted on the gene count on chromosome 10. Multispecies comparative analysis indicated that we can readily annotate the protein-coding genes with current resources. We estimate that over 95% of all coding exons were identified in this study. Assessment of single base changes between the human chromosome 10 and chimpanzee sequence revealed nonsense mutations in only 21 coding genes with respect to the human sequence.

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Chromosome 6 is a metacentric chromosome that constitutes about 6% of the human genome. The finished sequence comprises 166,880,988 base pairs, representing the largest chromosome sequenced so far. The entire sequence has been subjected to high-quality manual annotation, resulting in the evidence-supported identification of 1,557 genes and 633 pseudogenes. Here we report that at least 96% of the protein-coding genes have been identified, as assessed by multi-species comparative sequence analysis, and provide evidence for the presence of further, otherwise unsupported exons/genes. Among these are genes directly implicated in cancer, schizophrenia, autoimmunity and many other diseases. Chromosome 6 harbours the largest transfer RNA gene cluster in the genome; we show that this cluster co-localizes with a region of high transcriptional activity. Within the essential immune loci of the major histocompatibility complex, we find HLA-B to be the most polymorphic gene on chromosome 6 and in the human genome.

Nature 441, 315–321 (2006) We inadvertently omitted the names of the following authors: R. Banerjee, S. P. Bryant, D. C. Burford, W. D. H. Burrill, S. M. Clegg, P. Dhami, O. Dovey, L. M. Faulkner, S. M. Gribble, C. F. Langford, R. D. Pandian, K. M. Porter and E. Prigmore.

Measurements are reported of the dielectric properties of three laterally substituted dicyano compounds with large molecular dipole moments perpendicular to the long molecular axis. Results are given for the materials in solution, in the isotropic liquid state, and for one compound in the nematic state. There is evidence of a high degree of local ferroelectric order in all phases, and dipole correlation factors in excess of 3 were obtained. The significance of these observations for macroscopic ferroelectrically ordered and biaxial liquid-crystalline phases is considered.

The present rapid expansion of the nuclear power programme is based largely on slightly enriched thermal reactor types with poor plutonium production, and could exhaust the rich uranium reserves well before the end of the century, whilst producing an inadequate plutonium inventory for a future fast breeder programme. A more gradual expansion of the thermal reactor programme based on “near‐breeder” reactors would extend the rich reserves to the year 2000 and build up an adequate plutonium inventory for a significant fast breeder programme, with the possibility of introducing the thorium fuel cycle early in the 21st century.

To clear up a discrepancy in the existing absolute measurements of (p. gamma ) resonances, the proton energies at which strong fluorine and aluminum (p. gamma ) resonances occur were measured using a 36-in. radius absolute electrostatic analyzer and compared with previous measurements for the lowest energy fluorine resonance using a 12-in. absolute electrostatic analyzer. An accuracy of one part in a thousand is claimed for both instruments and the disagreement was found to be less than 1.5 parts in a thousand. Weighted mean values of fluorine resonances. based on two analyzers. were found to be 340.7 plus or minus 0.3, 484.3 plus or minus 0.3, 873.5 plus or minus 0.7, 1347.7 plus or minus 1.0, and 1373.7 plus or minus 0.8 kev. These are compared with the values obtained by other workers in this field, and found to be in good agreement with those of Herb et al. and Bondelid et al. but discrepancies exist between the present measurements and those of Bumiller et al. (auth)

The energy of the proton beam from an air insulated Van de Graaff generator was measured absolutely by an electrostatic analyser, and the resonant energies for proton capture by 24Mg and 25Mg were determined by observing the positron yields. The following resonances were observed: 24Mg (p, γ)25Al 225.5 ± 0.3 and 418.4 ± 0.4 keV of half widths 6.0 ± 1.0 and 2.5 ± 0.5 keV respectively. 25Mg (p, γ)26Al 316.7 ± 0.7, 391.5 ± 0.5, 495.6 ± 0.6, 513.4 ± 0.7 and 530.4 ± 0.7 keV, of half widths 12.0 ± 1.0, 8.0 ± 1.0, 5.0 ± 1.0, 3.0 ± 1.0 and 3.0 ± 1.0 keV respectively. The half lives of the positron decay of 25Al and 26Al were measured as 7.62 ± 0.13 and 6.68 ± 0.11 seconds respectively.

The mean energies of protons observed at 45° and 135° to the direction of positive gas current flow in the toroidal pinched discharge apparatus SCEPTRE III and the energy spread of these protons indicate that they originate from fusing deuterons having a range of centre-of-mass velocities in the Φ direction The experimental results can be explained in terms of a fast tail of deuterons with velocities between 4 × 107 cm sec-1 and 16×107 cm sec-1 fusing with a much larger number of deuterons travelling at lower velocities. The proton yield indicates that the deuteron population falls off roughly exponentially with increasing velocity, about 1 in 103 of the total deuterons present having velocities of between 4 and 16×107 cm sec-1. Such a distribution is consistent with a very high proportion of the deuterons present having velocities of less than 107 cm sec-1 in the Φ direction, as is indicated by spectroscopic measurements. The proton energy measurements also indicate that the deuterons are moving in the θ sense and the effect of this motion is also considered

In this paper a review is given of the main experimental results obtained with the Sceptre IV discharge. The torus was toroidally machined from high quality copper and has an initial magnetic field accurately matched to the tube wall. With capacitor bank energies up to 106 J, discharge currents up to 500 kA have been studied. Many of the properties of the discharge, including the electron temperature, the average magnetic field profiles and the fusion reaction rates are similar to those obtained with other experiments (Zeta, Sceptre III), there being no appreciable change in these properties with either the improved geometrical shape or with the increase in energy. Differences from the earlier experiments include larger magnetic field fluctuations, less reproducibility, somewhat lower ion temperatures (Doppler broadening) and a different radial profile for the ion temperature. These differences are possibly due to the magnetic fields generated at the gaps by eddy currents when the gas current is flowing. New measurements include a study of the θ as well as motion of the reacting deuterons, and a new method of measuring the electron temperature. A summary is given of the theories which have been put forward to explain the electron energy loss, the positive ion heating and the magnetic field profiles.

The development of the Van de Graaff accelerator over the past three decades is briefly reviewed with particular reference to the work of Van de Graaff and his colleagues, and an attempt is made to illustrate briefly how the special characteristics of this type of accelerator have contributed to advances in our knowledge of low energy nuclear physics. A brief mention is made of the application of Van de Graaff accelerators to other fields of physics, and to engineering, chemistry, medicine and the biological sciences.

Thick targets of copper, silver, gold, tungsten, molybdenum, titanium, tantalum and tin were irradiated by protons in the energy range 0.6 to 2.8 MeV and the total γ-ray yield measured as a function of proton energy. The γ-ray spectra were also measured for a fixed proton energy of 2.2 MeV. The total γ-ray yields of the materials were found to decrease in the order given above, indicating that tungsten backings produce less total γ-ray background than any other. If high energy γ-rays are being investigated it may be advisable to use tin or gold backings since the γ-ray spectrum from these is concentrated towards the lower energies and can consequently be biased out in the counting equipment, but both materials are rather fragile under heavy proton irradiation.

The upper limit to the voltage attained by Van de Graaff accelerators is often set by the flow of electrons towards the positive terminal of the tube, producing large X-ray fluxes and ionisation currents in the gas between the high voltage terminal and the earthed pressure vessel. By designing the internal electrodes of the tube to trap retrograde electrons a voltage of 3.7 MV has been obtained across a nine foot long tube, with immeasurably small electron currents. The performance of this tube is compared with that of tubes employing other internal electrode designs.

12C and 24Mg targets were irradiated by protons of energy 456.8 keV and 225.5 keV corresponding to the formation of excited levels in 13N and 25Al of energy 2.37 and 2.50 MeV respectively. The gamma-ray spectra were investigated using a 20 mm cube sodium iodide crystal and photomultiplier feeding into a Hutchinson-Scarrott type pulse height analyser. A single gamma ray was observed from the 2.37 MeV state in 13N. Peaks observed from 25Al could best be explained in terms of excited levels at 0.46, 1.54 and 2.5 MeV. A search was made for γ-radiation accompanying the positron decay of 25Al to 25Mg. The only peak observed was one at 0.51 MeV corresponding to annihilation radiation. It therefore seems probable that a simple positron transition between the 25Al and 25Mg ground state takes place.

A polymeric nicotinamide system of defined structure and properties is described. Some preliminary studies of the effect of the structure of groups vicinal to the dihydronicotinamide system on its H -donor properties and particularly on the rate of H -transfer are reported.

The energy of a proton beam from a pressurized electrostatic generator was measured absolutely by means of an electrostatic analyzer, and used to irradiate thin targets containing fluorine. The $\ensuremath{\gamma}$-ray yield was observed as a function of proton energy and the energies for resonant proton capture were determined to an accuracy of one part in a thousand in most cases. The width of each resonance at half-maximum yield was also measured.

Ein direkter Zusammenhang zwischen der crsten Phase (K1) und der zweiten Phase (K2) der fraktionellen Senkung des Bromsulphthaleinspiegels hat sich an von hepatoxischcn Krankheiten befallenen Kuhen und Schafen erwiesen. Es ist anzunehmen, dass die K2-Werte empfindlichere Nachweise der Lebertatigkeit in diesen Tieren aufweisen als die K1-Werte.

Neutron Radiography Methods, Capabilities and Applications. By Harold Berger. Pp. vi + 146. (Amsterdam, London and New York: Elsevier Publishing Company, 1965.) 50s.

DISCRETE energy-levels have been observed in arsenic-75 at excitation energies between about 8.0 and 10.0 MeV. The experimental procedure was as follows. Targets of separated germanium-74 of thickness 100 µgm./cm.2 and 10 µgm./cm.2 deposited on tungsten backings (prepared at the Atomic Energy Research Establishment, Harwell) were irradiated by the proton beam from a pressurized electrostatic generator1, and the γ-rays emitted were detected by means of a thallium-activated sodium iodide crystal 36 mm. diameter by 25 mm. long coupled optically to a photomultiplier of type 6262A. The output from the photomultiplier was fed into a scaler via a cathode follower and linear amplifier of type 1008.

Measurement of the Energy Spectrum of Protons Emitted from the Fusion Reaction in Sceptre III

The preparation and properties of various methylene- and ethylene-bridged dimeric and polymeric benzoquinones are described. The influence of substitution and bridging group on the extent of vicinal interaction in polyquinone chain segments, as evidenced by variations in their ultraviolet spectra, is examined.

The variations in reaction cross-section of the 63Cu (n,2n)62Cu and the 27Al (n,p)27Mg reactions as a function of neutron energy have been measured in the 13·5 to 14·9-MeV range, which is commonly used for 14-MeV neutron activation.The cross-section of the 63Cu (n, 2n)62Cu reaction was found to increase approximately linearly with a gradient of 140 ± 10 mb MeV–1, and that of the 27Al (n, p)27Mg reaction to be approximately constant. It is, therefore, suggested that the 27Al (n, p)27Mg reaction is more suitable for measuring the numerical value of a 14-MeV neutron flux, in spite of its lower cross-section.It is also suggested that to obtain 14-MeV neutron-activation measurements that are independent of neutron energy, the energy dependence of the flux-measuring foil and irradiated specimen should be matched. The 27Al (n, p)27Mg reaction appears to be suitable for all (n, p) reactions, while the 63Cu (n, 2n)62Cu reaction may be more suitable for (n, 2n) reactions.

4-HYDROXYisoPHTHALIC acid is a by-product of the manufacture of salicylic acid by the Kolbe–Schmitt reaction and has been found to be a major constituent of the ‘brown dust’ residues from the sublimation process for the purification of salicylic acid1. Analysis of a typical sample of ‘brown dust’ showed it to contain 10 per cent of salicylic, 82 per cent of 4-hydroxyisophthalic and 3 per cent of 2-hydroxyisophthalic acids, together with some inorganic material. From this source there is thus potentially available a considerable quantity of 4-hydroxyisophthalic acid, the chemistry of which is being investigated as part of a research programme on the Kolbe–Schmitt reaction at the Chemical Research Laboratory2. From a consideration of its structural similarity to salicylic acid, it was suggested at the Chemical Research Laboratory that 4-hydroxyisophthalic acid might also possess similar pharmacological properties. Accordingly, in February 1954, a pharmacological investigation was initiated at Ware and, since the findings were favourable, biochemical studies were also undertaken.

THE decay of the positron-emitters aluminium-26, aluminium-25 and nitrogen-13 was measured using a nine-channel sealer, which recorded the counts received from a Geiger–Muller tube in nine successive equal periods. These periods were 2 sec. each for the two aluminium isotopes and 200 sec. each for the nitrogen isotope. The isotopes were produced by resonant capture of protons by magnesium-25, magnesium-24 and carbon-12, respectively. The proton beam was switched off when counting began, and the switching from one channel to the next was done by an electronic timer, accurate to one part in a thousand.