A partial skeleton of an enantiornithine bird from the early Cretaceous of northwestern China

Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the continent remains poorly understood. In 2004, a collaborative field effort directed by personnel from the Chinese Academy of Geological Sciences and Carnegie Museum of Natural History recovered multiple partial to nearly complete avian skeletons from outcrops of the Lower Cretaceous Xiagou Formation exposed in the Changma Basin of northwestern Gansu Province, China. Here we describe a thrush-sized partial skeleton comprised of a fragmentary pelvic girdle and largely complete hind limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical characters places the specimen in Enantiomithes, and within that clade, in Enenantiomithes. When coupled with additional recent discoveries from the Changma Basin, the new skeleton improves our understanding of early avian evolution and diversification in central Asia

Structural transformation of natural graphite by passage of an electric current

Transmission electron microscopy is used to investigate the effect of passage of an electric current on the structure of a natural graphite. It is shown that the passage of a current can produce structures apparently consisting of hollow three-dimensional graphitic shells bounded by curved and faceted planes, typically made up of 2 graphene layers. A high degree of alignment is often found between these structures, in contrast to the material produced when synthetic graphite is treated in a similar way. The transformed carbon frequently contains small bilayer nanotubes, which are sometimes seamlessly joined to the larger graphene structures. In other cases the nanotubes are encapsulated inside larger graphene structures. A possible mechanism for the formation of these encapsulated tubes is proposed. Studies of the kind described here may help to understand the failure of graphene devices by Joule heating. The transformed carbon might also have a number of potential applications

Interface Depinning in a Disordered Medium - Numerical Results

We propose a lattice model to study the dynamics of a driven interface in a medium with random pinning forces. For driving forces F smaller than a threshold force F_c the whole interface gets pinned. The depinning transition can be characterized by a set of critical exponents: the static and dynamical roughness exponent, the velocity exponent defined by the scaling of the velocity of the interface with F-F_c, and a correlation length exponent. The critical exponents are determined numerically in 1+1 and 2+1 dimensions. Our findings are compared with recent numerical and analytical results for a Langevin equation with quenched noise, which is expected to be in the same universality class. Our results support a recent functional renormalization group calculation by T.Nattermann et.al. (J.Phys.II France 2, 1483 (1992)).Comment: 12 pages, (10 figures will be mailed upon request), Plain TeX, RUB-TP3-93-0

Zirconia-Based Compositions for Use in Passive NO\u3csub\u3ex\u3c/sub\u3e Adsorber Devices

A passive NOx adsorbent includes: palladium, platinum or a mixture thereof and a mixed or composite oxide including the following elements in percentage by weight, expressed in terms of oxide: 10-90% by weight zirconium and 0.1-50% by weight of least one of the following: a transition metal or a lanthanide series element other than Ce. Although the passive NOx adsorbent can include Ce in an amount ranging from 0.1 to 20% by weight expressed in terms of oxide, advantages are obtained particularly in the case of low-Ce or a substantially Ce-free passive NOx adsorbent

Embedding of printed electronic interconnections in additively manufactured metal components

Ultrasonic Additive Manufacturing (UAM) is an advanced hybrid manufacturing technology, which enables the embedding of electronic components and interconnections within solid metal structures, due to the low temperature/high plastic flow encountered during ultrasonic bonding. The UAM process is based on the ultrasonic metal welding of thin metal foils in a layer-by-layer fashion. This work summarises the recent advances made towards the integration of UAM with printed electronics and other advanced manufacturing technologies for the encapsulation of conductive tracks between the interfaces of the welded foils. Two different approaches were followed: Screen printing was utilized in the first approach, for the deposition of an insulating polymer layer and silver-loaded conductive adhesive tracks on the surface of an aluminium substrate prepared with UAM. In the second approach, the aluminium foils were surface modified prior to welding, in order to selectively create an insulating ceramic layer directly onto the foil surface. These modified foils were bonded using UAM and a syringe system was used for the dispensing of the silver conductive tracks. The effectiveness and advantages of each of these two methodologies are illustrated and commented upon. The results of this ongoing research project are promising and showcase the successful integration of advanced manufacturing technologies for the fabrication of intricate metal structural electronic components

Narrowing the Range of Future Climate Projections Using Historical Observations of Atmospheric CO2

This is the final version. Available from American Meteorological Society via the DOI in this recordUncertainty in the behavior of the carbon cycle is important in driving the range in future projected climate change. Previous comparisons of model responses with historical CO2 observations have suggested a strong constraint on simulated projections that could narrow the range considered plausible. This study uses a new 57-member perturbed parameter ensemble of variants of an Earth system model for three future scenarios, which 1) explores a wider range of potential climate responses than before and 2) includes the impact of past uncertainty in carbon emissions on simulated trends. These two factors represent a more complete exploration of uncertainty, although they lead to a weaker constraint on the range of future CO2 concentrations as compared to earlier studies. Nevertheless, CO2 observations are shown to be effective at narrowing the distribution, excluding 30 of 57 simulations as inconsistent with historical CO2 changes. The perturbed model variants excluded are mainly at the high end of the future projected CO2 changes, with only 8 of the 26 variants projecting RCP8.5 2100 concentrations in excess of 1100 ppm retained. Interestingly, a minority of the high-end variants were able to capture historical CO2 trends, with the large-magnitude response emerging later in the century (owing to high climate sensitivities, strong carbon feedbacks, or both). Comparison with observed CO2 is effective at narrowing both the range and distribution of projections out to the mid-twenty-first century for all scenarios and to 2100 for a scenario with low emissions.This work was supported by the Joint U.K. DECC/DEFRA Met Office Hadley Centre Climate Programme (GA01101). Chris Jones’s contribution was supported by the CRESCENDO project under the European Union's Horizon 2020 research and innovation programme, Grant Agreement 641816. Jo House was supported by a Leverhulme Early Career Fellowship and EU FP7 Project LUC4C (603542). Stephen Sitch was supported by the EU FP7 through Project LUC4C (GA603542)

Notch signaling from tumor cells: a new mechanism of angiogenesis.

Notch signaling is an evolutionarily conserved pathway and plays key roles in embryonic vascular development and angiogenesis. Multiple components of the Notch pathway are expressed in vasculature, and mice deficient for a variety of these components display embryonic lethality with vascular remodeling defects. Alteration of Notch signaling in various endothelial cells generates profound effects on angiogenesis in vitro. New evidence shows that Notch signaling from tumor cells is able to activate endothelial cells and trigger tumor angiogenesis in vitro and in a xenograft mouse tumor model. Selective interruption of Notch signaling within tumors may provide an antiangiogenic strategy

Targeting DLL4 in tumors shows preclinical activity but potentially significant toxicity.

Evaluation of: Yan M, Callahan CA, Beyer JC et al.: Chronic DLL4 blockade induces vascular neoplasms. Nature 463, E6-E7 (2010). Delta-like ligand 4 (DLL4) is a Notch ligand that is critical in the formation of a functional vascular network in tumors. Blockade of DLL4-mediated Notch signaling strikingly increases nonproductive angiogenesis, but significantly inhibits tumor growth in preclinical mouse models. Thus, DLL4 has emerged as an attractive target for cancer therapy. Anti-DLL4 antibodies have recently entered clinical trials. However, the potential toxic effects of anti-DLL4 are poorly understood. In this article, Yan et al. reported that chronic DLL4 blockade abnormally activates endothelial cells, causes pathological changes of multiple organs and induces vascular neoplasms. The findings need confirmation in further studies using different tumor-bearing animals but, nevertheless, raise important safety concerns regarding the use of anti-DLL4 agents and warrant monitoring for these effects in clinical trials for targeting DLL4

The potential of new tumor endothelium-specific markers for the development of antivascular therapy.

Angiogenesis is a hallmark of solid tumors, and disruption of tumor vasculature is an active anticancer therapy in some cases. Several proteins expressed on the surface of tumor endothelium have been identified during the last decade. However, due to the expression in both physiological and tumor angiogenesis, only a few targets have been developed for clinical therapeutics. By thorough SAGE analysis of mouse endothelial cells isolated from various normal resting tissues, regenerating liver, and liver-metastasized tumor, Seaman and colleagues in this issue of Cancer Cell have demonstrated organ-specific endothelial markers, physiological angiogenesis endothelial markers, and tumor endothelial markers and revealed striking differences between physiological and pathological angiogenesis