Activity of 50 Long-Period Comets Beyond 5.2 AU

Remote investigations of the ancient solar system matter has been traditionally carried out through the observations of long-period (LP) comets that are less affected by solar irradiation than the short-period counterparts orbiting much closer to the Sun. Here we summarize the results of our decade-long survey of the distant activity of LP comets. We found that the most important separation in the dataset is based on the dynamical nature of the objects. Dynamically new comets are characterized by a higher level of activity on average: the most active new comets in our sample can be characterized by afrho values >3--4 higher than that of our most active returning comets. New comets develop more symmetric comae, suggesting a generally isotropic outflow. Contrary to this, the coma of recurrent comets can be less symmetrical, ocassionally exhibiting negative slope parameters, suggesting sudden variations in matter production. The morphological appearance of the observed comets is rather diverse. A surprisingly large fraction of the comets have long, teniouos tails, but the presence of impressive tails does not show a clear correlation with the brightness of the comets.Comment: 21 pages, 4 figures, accepted for publication in A

Levels of extra-pair paternity are associated with parental care in penduline tits (Remizidae)

In most passerine birds, individuals attempt to maximise their fitness by providing parental care while also mating outside their pair bond. A sex-specific trade-off between these two behaviours is predicted to occur since the fitness benefits of extra-pair mating differs between the sexes. We use nest observations and parentage analysis to reveal a negative association between male care and the incidence of extra-pair paternity across three species of penduline tit (Remizidae)

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to dominate flow behavior, in some cases producing double circulation loops in the weld pool

ABSTRACT. A mathematical model has been developed to account for convection and temperature distributions in stationary arc weld pools driven by buoyancy, electromagnetic and surface tension forces. It is shown that the electromagnetic and surface tension forces dominate the flow behavior. In some cases, these forces produce double circulation loops, which are indirectly confirmed by experimental measurements of segregation in the weld pool. It is also shown that the surface tension driven flows are very effective in dissipating the incident energy flux on the pool surface which, in turn, reduces the vaporization from the weld pool

A prospective seroepidemiological study of human herpesvirus-8 infection and the risk of multiple myeloma

Presence of the Human Herpesvirus 8 (HHV8) genome has been reported in the bone marrow of multiple myeloma (MM) patients. So far, serological studies of HHV8 and MM have been inconsistent but have not included prospective epidemiological studies. We evaluated whether HHV8 infection is associated with increased risk for MM in a prospective population-based study of 39 000 Finnish subjects who donated serum samples in the period 1968–72. Serum samples from 47 subjects who developed MM during a 23-year follow-up and 224 age, area of residence and sex-matched subjects who remained healthy over a similar follow-up period were evaluated for HHV8 antibodies at enrolment, as assayed both with an immunofluorescence assay (IFA) for lytic and latent HHV8 antigens and by Western blot (WB) with three recombinant HHV8 proteins (ORFs 65, 73 and K8.1A). HHV8 seropositivity for at least one HHV8 protein on WB was found in 7% of the Finnish population and was not associated with the risk of developing MM (Relative Risk (RR) = 0.89, Confidence Interval (CI): 0.25–3.25). HHV8 seropositivity for lytic and latent antigens in the IFA was found in 16% and 0.4% of the Finnish population and tended to associate with risk of MM (RR = 2.02, CI: 0.94–4.33 and RR = 10.00, CI: 0.91–110.29, respectively). In conclusion, no statistically significant evidence for an association between HHV8 infection and the risk of future MM was found. © 2001 Cancer Research Campaign http://www.bjcancer.co

Modelling the distribution of wetland birds on the Red Sea coast in the Kingdom of Saudi Arabia

Species distribution modelling is useful for addressing knowledge gaps for poorly studied geographical areas by identifying potentially suitable habitats for species across landscapes. This study was undertaken to identify areas containing wetland habitats to support actions aimed at the conservation of wetland bird species on the Red Sea coast of the Kingdom of Saudi Arabia (KSA). We used a maximum entropy approach to build habitat suitability models for 22 wetland bird species (gulls, shorebirds, and terns). Ten variables relating to topography, habitat, latitude, coast complexity, man-made structures, and human settlements were used to produce individual habitat suitability models for each of the bird species. The areas under the curve (AUC) for the final model were 0.9013 and 0.879 for the training and testing data, respectively, and the jackknife analyses suggested that the models generally performed well. Using the modelled distributions of the 22 species along the Red Sea coast, the analysis suggested 17 core areas where the habitat and landscape configuration were suitable for supporting high species richness. Of these 17 sites, one is already protected, and there is a need to protect the remaining sites. The use of these models to inform conservation strategies in the Red Sea region of the KSA is discussed