Interaction of free-floating planets with a star-planet pair

The recent discovery of free-floating planets and their theoretical interpretation as celestial bodies, either condensed independently or ejected from parent stars in tight clusters, introduced an intriguing possibility. Namely, that some exoplanets are not condensed from the protoplanetary disk of their parent star. In this novel scenario a free-floating planet interacts with an already existing planetary system, created in a tight cluster, and is captured as a new planet. In the present work we study this interaction process by integrating trajectories of planet-sized bodies, which encounter a binary system consisting of a Jupiter-sized planet revolving around a Sun-like star. To simplify the problem we assume coplanar orbits for the bound and the free-floating planet and an initially parabolic orbit for the free-floating planet. By calculating the uncertainty exponent, a quantity that measures the dependence of the final state of the system on small changes of the initial conditions, we show that the interaction process is a fractal classical scattering. The uncertainty exponent is in the range (0.2-0.3) and is a decreasing function of time. In this way we see that the statistical approach we follow to tackle the problem is justified. The possible final outcomes of this interaction are only four, namely flyby, planet exchange, capture or disruption. We give the probability of each outcome as a function of the incoming planet's mass. We find that the probability of exchange or capture (in prograde as well as retrograde orbits and for very long times) is non-negligible, a fact that might explain the possible future observations of planetary systems with orbits that are either retrograde or tight and highly eccentric.Comment: 19 pages, 12 figure

The Investigation of Flowering Control in Late/Rare Flowering Lolium Perenne

Flowering in Lolium perenne (perennial ryegrass) results in reduced digestibility and its inhibition would enhance forage quality. Flowering regulation has been well studied in Arabidopsis thaliana (Simpson and Dean, 2002) and orthologs of Arabidopsis flowering genes underlying heading date Quantitative Trait Loci (QTL) have been identified in rice (Yano, M et al., 2000). However it is not clear yet how universally applicable such studies are to Lolium. The project goals are to characterise the gene expression profiles of late/rare flowering L. perenne plants to determine factors affecting flowering and to map the genes involved in the flowering process. Initial studies, reported here, have focussed on the ability of 6 plant lines from the Oak Park breeding programme, previously identified as rare or non-flowering under natural day length conditions, to flower in controlled environments

Screening of Perennial Grasses and a Mutant Maize Collection by Fourier-Transformed InfraRed (FTIR) Spectroscopy for Improved Biofuel Traits

Currently the potential of biomass crops, including grasses, is limited because most species have not been bred for this purpose. However traits such as lignification, phenolic cross-linking and carbohydrate accessibility, which are also important for nutritive quality in forage grasses, can affect potential biofuel quality in applications such as combustion, fast-pyrolysis or fermentation. A collection of Lolium and Festuca species known to exhibit a range of lignin, cell wall phenolic and carbohydrate concentrations have been used to test optimum characteristics for biofuel processing. This collection formed a “calibration” set for subsequent high through-put FTIR chemical screening of additional plant lines: (1) A set of Lolium-Festuca substitution lines, in which L. perenne chromosomes or chromosome segments are substituted by homoeologous regions of F. pratensis, that provide the potential to physically map biofuel traits to an individual chromosome or chromosome segment; (2) A maize transposon (Robertson’s Mutator) induced mutant collection, which provides the potential to identify gene sequences underlying important biochemical traits linked to biofuel as determined by FTIR analysis

Construction and Exploitation of a Bacterial Artificial Chromosome (BAC) Library for \u3cem\u3eLolium Perenne\u3c/em\u3e (Perennial Ryegrass)

BAC libraries are an important tool in genomics, enabling physical maps, genome sequencing, marker development and map based cloning strategies. A BAC library has therefore been generated for the temperate grass species Lolium perenne (perennial ryegrass) which compliments an existing BAC library of the closely related species, Festuca pratensis also generated by IGER. Moreover the L. perenne BAC library will provide a useful tool for grass comparative genomics to compliment the existing BAC libraries of cereal crops including rice, wheat, barley, Sorghum and maize. In particular it will allow a comparison of micro-synteny between this large genome forage crop species and the model small genome monocot species Orzya sativa

Guideline on managing thumb ulnar collateral ligament injuries: the British Society of Surgery for the Hand Evidence for Surgical Treatment (BEST) findings and recommendations

The development of the ulnar collateral ligament (UCL) guideline was undertaken in accordance with the British Society for Surgery of the Hand Evidence for Surgical Treatment (BEST) Process Manual, which has been accredited by the National Institute for Health and Care Excellence, UK. This review article serves as a summary of the systematic reviews and the final guideline. The group included two patients, a radiologist, a commissioner, an emergency medicine doctor, hand therapists and hand surgeons. The group’s recommendations are that patients with acute UCL injuries should be assessed with a history, clinical examination and radiographs. Patients without significant joint laxity can be treated non-surgically. Patients with significant joint laxity on clinical examination may be treated with non-surgical joint immobilization or surgical repair and should reach a shared decision with their clinician about the definitive treatment within 2 weeks of presentation

Different Ways of Reading, or Just Making the Right Noises?

What does reading look like? Can learning to read be reduced to the acquisition of a set of isolable skills, or proficiency in reading be equated with the independence of the solitary, silent reader of prose fiction? These conceptions of reading and reading development, which figure strongly in educational policy, may appear to be simple common sense. But both ethnographic data and evidence from literary texts suggest that such paradigms offer, at most, a partial and ahistorical picture of reading. An important dimension, neglected in the dominant paradigms, is the irreducibly social quality of reading practices

Viral vectored hepatitis C virus vaccines generate pan-genotypic T cell responses to conserved subdominant epitopes

Background: Viral genetic variability presents a major challenge to the development of a prophylactic hepatitis C virus (HCV) vaccine. A promising HCV vaccine using chimpanzee adenoviral vectors (ChAd) encoding a genotype (gt) 1b non-structural protein (ChAd-Gt1b-NS) generated high magnitude T cell responses. However, these T cells showed reduced cross-recognition of dominant epitope variants and the vaccine has recently been shown to be ineffective at preventing chronic HCV. To address the challenge of viral diversity, we developed ChAd vaccines encoding HCV genomic sequences that are conserved between all major HCV genotypes and adjuvanted by truncated shark invariant chain (sIitr). / Methods: Age-matched female mice were immunised intramuscularly with ChAd (108 infectious units) encoding gt-1 and -3 (ChAd-Gt1/3) or gt-1 to -6 (ChAd-Gt1-6) conserved segments spanning the HCV proteome, or gt-1b (ChAd-Gt1b-NS control), with immunogenicity assessed 14-days post-vaccination. / Results: Conserved segment vaccines, ChAd-Gt1/3 and ChAd-Gt1-6, generated high-magnitude, broad, and functional CD4+ and CD8+ T cell responses. Compared to the ChAd-Gt1b-NS vaccine, these vaccines generated significantly greater responses against conserved non-gt-1 antigens, including conserved subdominant epitopes that were not targeted by ChAd-Gt1b-NS. Epitopes targeted by the conserved segment HCV vaccine induced T cells, displayed 96.6% mean sequence homology between all HCV subtypes (100% sequence homology for the majority of genotype-1, -2, -4 sequences and 94% sequence homology for gt-3, -6, -7, and -8) in contrast to 85.1% mean sequence homology for epitopes targeted by ChAd-Gt1b-NS induced T cells. The addition of truncated shark invariant chain (sIitr) increased the magnitude, breadth, and cross-reactivity of the T cell response. / Conclusions: We have demonstrated that genetically adjuvanted ChAd vectored HCV T cell vaccines encoding genetic sequences conserved between genotypes are immunogenic, activating T cells that target subdominant conserved HCV epitopes. These pre-clinical studies support the use of conserved segment HCV T cell vaccines in human clinical trials