Sporting contests: seeing red? Putting sportswear in context

The shirt colour worn by sportsmen can affect the behaviour of the competitors, but Hill and Barton show that it may also influence the outcome of contests. By analysing the results of men's combat sports from the Athens 2004 Olympics, they found that more matches were won by fighters wearing red outfits than by those wearing blue; they suggest that red might confer success because it is a sign of dominance in many animal species and could signal aggression in human contests. Here we use another data set from the 2004 Olympics to show that similar winning biases occur in contests in which neither contestant wears red, indicating that a different mechanism may be responsible for these effects.     

Forensic palaeontology: The Archaeoraptor forgery

The Archaeoraptor fossil was announced as a 'missing link' and purported to be possibly the best evidence since Archaeopteryx that birds did, in fact, evolve from certain types of carnivorous dinosaur. It reportedly came from Early Cretaceous beds of China that have produced other spectacular fossils transitional between birds and extinct non-avian dinosaurs. But Archaeoraptor was revealed to be a forgery in which bones of a primitive bird and a non-flying dromaeosaurid dinosaur had been combined. Here we use high-resolution X-ray computed tomography (CT) to determine the nature and extent of the forgery, as well as how it was built, by imaging the fracture pattern and distribution of materials through the entire specimen.     

Epstein-Barr virus-positive Burkitt's lymphoma cells not recognized by virus-specific T-cell surveillance

The pathogenesis of Epstein-Barr (EB) virus-positive Burkitt's lymphoma (BL) appears to involve the combined actions of virus-induced B-cell proliferation, and a rare chromosomal translocation juxtaposing c-myc and immunoglobulin gene loci in a single B cell; holoendemic malarial infection in some way facilitates the oncogenic process. Outgrowth of the EB virus-positive tumour suggests either breakdown or evasion of those immune controls, in particular cytotoxic T-cell responses against the virus-induced lymphocyte-detected membrane antigen LYDMA, which limit virus-infected B-cell numbers in healthy virus carriers. Immunosuppression, such as that which malarial infection may induce, cannot itself be a sufficient explanation in this regard since our studies have identified a number of BL patients who retain detectable LYDMA-specific T-cell surveillance. The present work shows that in many cases of virus-associated BL, the emerging malignant clone is insensitive to such surveillance. Several EB virus-positive BL cell lines, recently established in vitro and expressing the class I histocompatibility locus antigens (HLAs) which restrict cytotoxic T-cell function, were not killed by HLA-matched LYDMA-specific effector populations in assays where the EB virus-positive lymphoblastoid cell line (LCL), derived from normal B cells of the same patient, sustained high levels of lysis.     

Experimental entanglement of four particles

Quantum mechanics allows for many-particle wavefunctions that cannot be factorized into a product of single-particle wavefunctions, even when the constituent particles are entirely distinct. Such 'entangled' states explicitly demonstrate the non-local character of quantum theory, having potential applications in high-precision spectroscopy, quantum communication, cryptography and computation. In general, the more particles that can be entangled, the more clearly nonclassical effects are exhibited--and the more useful the states are for quantum applications. Here we implement a recently proposed entanglement technique to generate entangled states of two and four trapped ions. Coupling between the ions is provided through their collective motional degrees of freedom, but actual motional excitation is minimized. Entanglement is achieved using a single laser pulse, and the method can in principle be applied to any number of ions.