Sizes of pentagonal clusters in fullerenes

Stability and chemistry, both exohedral and endohedral, of fullerenes are critically dependent on the distribution of their obligatory 12 pentagonal faces. It is well known that there are infinitely many IPR-fullerenes and that the pentagons in these fullerenes can be at an arbitrarily large distance from each other. IPR-fullerenes can be described as fullerenes in which each connected cluster of pentagons has size 1. In this paper we study the combinations of cluster sizes that can occur in fullerenes and whether the clusters can be at an arbitrarily large distance from each other. For each possible partition of the number 12, we are able to decide whether the partition describes the sizes of pentagon clusters in a possible fullerene, and state whether the different clusters can be at an arbitrarily large distance from each other. We will prove that all partitions with largest cluster of size 5 or less can occur in an infinite number of fullerenes with the clusters at an arbitrarily large distance of each other, that 9 partitions occur in only a finite number of fullerene isomers and that 15 partitions do not occur at all in fullerenes

Constraints on Nucleon Decay via "Invisible" Modes from the Sudbury Neutrino Observatory

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to ``invisible'' modes, such as n -> 3 nu. The analysis was based on a search for gamma-rays from the de-excitation of the residual nucleus that would result from the disappearance of either a proton or neutron from O16. A limit of tau_inv > 2 x 10^{29} years is obtained at 90% confidence for either neutron or proton decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton decay modes and 400 times more stringent than similar neutron modes.Comment: Update includes missing efficiency factor (limits change by factor of 2) Submitted to Physical Review Letter

First Neutrino Observations from the Sudbury Neutrino Observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

Heterogeneity of the humoral immune response following Staphylococcus aureus bacteremia

Expanding knowledge on the humoral immune response in Staphylococcus aureus-infected patients is a mandatory step in the development of vaccines and immunotherapies. Here, we present novel insights into the antibody responses following S. aureus bacteremia. Fifteen bacteremic patients were followed extensively from diagnosis onwards (median 29 days, range 9-74). S. aureus strains (median 3, range 1-6) and serial serum samples (median 16, range 6-27) were collected. Strains were genotyped by pulsed-field gel electrophoresis (PFGE) and genes encoding 19 staphylococcal proteins were detected by polymerase chain reaction (PCR). The levels of IgG, IgA, and IgM directed to these proteins were determined using bead-based flow cytometry. All strains isolated from individual patients were PFGE-identical. The genes encoding clumping factor (Clf) A, ClfB, and iron-responsive surface-determinant (Isd) A were detected in all isolates. Antigen-specific IgG levels increased more frequently than IgA or IgM levels. In individual patients, different proteins induced an immune response and the dynamics clearly differed. Anti-ClfB, anti-IsdH, and anti-fibronectin-binding protein A IgG levels increased in 7 of 13 adult patients (p < 0.05). The anti-IsdA IgG level increased in 12 patients (initial to peak level: 1.13-10.72 fold; p < 0.01). Peak level was reached 7-37 days after diagnosis. In a bacteremic 5-day-old newborn, antistaphylococcal IgG levels declined from diagnosis onwards. In conclusion, each bacteremic patient develops a unique immune response directed to different staphylococcal proteins. Therefore, vaccines should be based on multiple components. IsdA is immunogenic and, therefore, produced in nearly all bacteremic patients.

A revision of the status of Lepadogaster lepadogaster (Teleostei : Gobiesocidae): sympatric subspecies or a long misunderstood blend of species?

Molecular (partial mitochondrial 12S ribosomal DNA sequences), morphological and meristic analysis of Lepadogaster lepadogaster lepadogaster, L. l. purpurea and L. zebrina were performed to investigate the relationships between these taxa. On the western shore of mainland Portugal, where the two subspecies of L. lepadogaster occur sympatrically, they differ in microhabitat preferences and their breeding seasons are largely out of phase. This information, combined with data on distribution patterns, led to the following conclusions: Lepadogaster l. purpurea is considered to be a valid species, L. purpurea (Bonnaterre, 1788), different from L. l. lepadogaster, now designated L. lepadogaster (Bonnaterre, 1788). L. zebrina was found to be a synonym of L. lepadogaster. The two newly defined species were found to be in sympatry at Madeira and the Canary islands, the Atlantic coast of the Iberian Peninsula, and the Mediterranean at least as far as Genoa (Italy). Diagnostic characters and a list of synonyms are provided. (C) 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 76, 327-338

The Leiognathus splendens complex (Perciformes: Leiognathidae) with the description of a new species, Leiognathus kupanensis Kimura and Peristiwady

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes the Leiognathus splendens complex comprising four valid species: L. jonesi James, 1971, widely distributed in the Indo-West Pacific, from Mauritius to Papua New Guinea, north to Hainan I. (China), and south to Brisbane, Australia; L. kupanensis sp. nov., currently known only from Kupang, Timor, Indonesia; L. rapsoni Munro, 1964, currently known only from India, Indonesia, and Papua New Guinea, and L. splendens Cuvier, 1829, widely distributed in the eastern Indian and western Pacific oceans, from India to Papua New Guinea, and from southern Japan to northern Australia. The L. splendens complex can be defined by the following combination of characters: body depth 42–60% of standard length; mouth protruding downward; slender, minute teeth uniserially on jaws; lower margin of orbit above the horizontal through the gape when mouth closed; breast almost completely scaled; lateral line complete, and a dark blotch on top of spinous dorsal fin. Diagnostic characters of the members are as follows: L. jonesi —anterior dorsolateral body surface with a semicircular naked area on nape, and a paler dark blotch on spinous dorsal fin; L. kupanensis —anterior dorsolateral body surface widely naked; L. rapsoni —cheek scaled; L. splendens —anterior dorsolateral body surface completely scaled and a jet black blotch on spinous dorsal fin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41595/1/10228_2005_Article_283.pd

Identification of Trypanosoma brucei RMI1/BLAP75 Homologue and Its Roles in Antigenic Variation

At any time, each cell of the protozoan parasite Trypanosoma brucei expresses a single species of its major antigenic protein, the variant surface glycoprotein (VSG), from a repertoire of >2,000 VSG genes and pseudogenes. The potential to express different VSGs by transcription and recombination allows the parasite to escape the antibody-mediated host immune response, a mechanism known as antigenic variation. The active VSG is transcribed from a sub-telomeric polycistronic unit called the expression site (ES), whose promoter is 40–60 kb upstream of the VSG. While the mechanisms that initiate recombination remain unclear, the resolution phase of these reactions results in the recombinational replacement of the expressed VSG with a donor from one of three distinct chromosomal locations; sub-telomeric loci on the 11 essential chromosomes, on minichromosomes, or at telomere-distal loci. Depending on the type of recombinational replacement (single or double crossover, duplicative gene conversion, etc), several DNA-repair pathways have been thought to play a role. Here we show that VSG recombination relies on at least two distinct DNA-repair pathways, one of which requires RMI1-TOPO3α to suppress recombination and one that is dependent on RAD51 and RMI1. These genetic interactions suggest that both RAD51-dependent and RAD51-independent recombination pathways operate in antigenic switching and that trypanosomes differentially utilize recombination factors for VSG switching, depending on currently unknown parameters within the ES

Designing programmes of physical activity through sport: Learning from a widening participation intervention, 'City of Football'

Background: Implementation profoundly influences how well new audiences engage with sport-based physical activity programmes. Recognising that effective implementation relies on concurrently generating supportive contexts, systems and networks for the least engaged ‘target’ groups; this paper aims to address what underpins children’s (non) engagement with football-based physical activity. Methods: An observational research design, using a non-probability sample of N=594 primary and secondary schoolchildren assessed outcomes of a three-year ‘City of Football’ (CoF) programme. Pupils self-reported football participation, personal friendship networks and exposure to six concurrent sources of influence (SoI). A 2-step hierarchical cluster analysis and univariate analyses assessed between-cluster differences. Results: Girls played football least regularly (χ2 [4] = 86.722, p = 0.000). Overall, participation was significantly associated with personal networks engaged in football. Boys’ personal networks were more stable and structurally effective. Football participation was also positively and linearly association with SoI scores. Girls and pupils with no personal networks around football reported the lowest SoI scores. Three clusters emerged, dominated by social network influences. The Traditional Market (n=157, 27.7%) comprised 81.7% boys; they regularly played football, had the most effective network structure and scored highly across all six domains of SoI. The Sporadically Engaging Socialisers (n=190, 33.5%) comprised 52.9% girls who rarely played football, reported low SoI scores and an inferior network structure. In the Disconnected cluster (n=220, 38.8%), 59.3% were non-footballing girls who reported the lowest motivation and ability SoI scores; and no personal networks engaged in football. Conclusions: This study reveals new insights about the primacy of social network effects for engaging children in football-based physical activity programmes. With little or no attention to these social-oriented issues, such interventions will struggle to attract ‘target’ children, but will readily engage already well-connected, experienced football-playing boys. The challenge for drawing non-footballing children into football-based interventions lies with engaging children – especially girls - whose social networks are not football-focused, while they also find football neither personally motivating nor easy to do

Apoptosis-inducing factor deficiency decreases the proliferation rate and protects the subventricular zone against ionizing radiation

Cranial radiotherapy in children often leads to progressive cognitive decline. We have established a rodent model of irradiation-induced injury to the young brain. A single dose of 8 Gy was administered to the left hemisphere of postnatal day 10 (P10) mice. Harlequin (Hq) mice, carrying the hypomorphic apoptosis-inducing factor AIFHq mutation, express 60% less AIF at P10 and displayed significantly fewer dying cells in the subventricular zone (SVZ) 6 h after IR, compared with wild type (Wt) littermates. Irradiated cyclophilin A-deficient (CypA−/−) mice confirmed that CypA has an essential role in AIF-induced apoptosis after IR. Hq mice displayed no reduction in SVZ size 7 days after IR, whereas 48% of the SVZ was lost in Wt mice. The proliferation rate was lower in the SVZ of Hq mice. Cultured neural precursor cells from the SVZ of Hq mice displayed a slower proliferation rate and were more resistant to IR. IR preferentially kills proliferating cells, and the slower proliferation rate in the SVZ of Hq mice may, at least partly, explain the protective effect of the Hq mutation. Together, these results indicate that targeting AIF may provide a fruitful strategy for protection of normal brain tissue against the detrimental side effects of IR