The post-2009 influenza pandemic era : time to revisit antibody immunodominance

The current inactivated influenza vaccines rely on the induction of neutralizing antibodies against the head domain of the viral hemagglutinin (HA). The HA head contains five immunodominant antigenic sites, all of which are subject to antigenic drift, thereby limiting vaccine efficacy. Bypassing the immune system's tendency to focus on the most variable regions of the HA may be a step toward more broadly protective influenza vaccines. However, this requires a better understanding of the biological meaning of immunodominance, and of the hierarchy between different antigenic sites. In this issue of the JCI, Liu et al. determined the immunodominance of the five antigenic sites of the HA head in experimentally infected mice, guinea pigs, and ferrets. All three species exhibited different preferences for the five sites of the 2009 pandemic H1N1 strain. Moreover, human subjects exhibited yet a different pattern of immunodominance following immunization with the standard inactivated influenza vaccine. Together, these results have important implications for influenza vaccine design and interpretation of animal models

Cross-protection between antigenically distinct H1N1 swine influenza viruses from Europe and North America

Background An avian-like H1N1 swine influenza virus (SIV) is enzootic in swine populations of Western Europe. The virus is antigenically distinct from H1N1 SIVs in North America that have a classical swine virus-lineage H1 hemagglutinin, as does the pandemic (H1N1) 2009 virus. However, the significance of this antigenic difference for cross-protection among pigs remains unknown. Objectives We examined protection against infection with a North American triple reassortant H1N1 SIV [A/swine/Iowa/H04YS2/04 (sw/IA/04)] in pigs infected with a European avian-like SIV [A/swine/Belgium/1/98 (sw/B/98)] 4 weeks earlier. We also examined the genetic relationships and serologic cross-reactivity between both SIVs and with a pandemic (H1N1) 2009 virus [A/California/04/09 (Calif/09)]. Results After intranasal inoculation with sw/IA/04, all previously uninfected control pigs showed nasal virus excretion, high virus titers in the entire respiratory tract at 4 days post-challenge (DPCh) and macroscopic lung lesions. Most pigs previously infected with sw/B/98 tested negative for sw/IA/04 in nasal swabs and respiratory tissues, and none had lung lesions. At challenge, these pigs had low levels of cross-reactive virus neutralizing and neuraminidase inhibiting (NI) antibodies to sw/IA/04, but no hemagglutination-inhibiting antibodies. They showed similar antibody profiles when tested against Calif/09, but NI antibody titers were higher against Calif/09 than sw/IA/04, reflecting the higher genetic homology of the sw/B/98 neuraminidase with Calif/09. Conclusions Our data indicate that immunity induced by infection with European avian-like H1N1 SIV affords protection for pigs against North American H1N1 SIVs with a classical H1, and they suggest cross-protection against the pandemic (H1N1) 2009 virus

The interior angular momentum of core hydrogen burning stars from gravity-mode oscillations

A major uncertainty in the theory of stellar evolution is the angular momentum distribution inside stars and its change during stellar life. We compose a sample of 67 stars in the core-hydrogen burning phase with a $\log\,g$ value from high-resolution spectroscopy, as well as an asteroseismic estimate of the near-core rotation rate derived from gravity-mode oscillations detected in space photometry. This assembly includes 8 B-type stars and 59 AF-type stars, covering a mass range from 1.4 to 5\,M$_\odot$, i.e., it concerns intermediate-mass stars born with a well-developed convective core. The sample covers projected surface rotation velocities $v\sin\,i \in[9,242]\,$km\,s$^{-1}$ and core rotation rates up to $26\mu$Hz, which corresponds to 50\% of the critical rotation frequency. We find deviations from rigid rotation to be moderate in the single stars of this sample. We place the near-core rotation rates in an evolutionary context and find that the core rotation must drop drastically before or during the short phase between the end of the core-hydrogen burning and the onset of core-helium burning. We compute the spin parameter, which is the ratio of twice the rotation rate to the mode frequency (also known as the inverse Rossby number), for 1682 gravity modes and find the majority (95\%) to occur in the sub-inertial regime. The ten stars with Rossby modes have spin parameters between 14 and 30, while the gravito-inertial modes cover the range from 1 to 15.Comment: Manuscript of 5 pages, including 2 figures, accepted for publication in The Astrophysical Journal Letter

Positronium formation from valence and inner shells in noble gas atoms

When recent experimental positronium (Ps) formation cross sections in noble gases have been compared with the most up-to date theoretical studies, the agreement is qualitative, but not quantitative. In this paper we re-examine this process and show that at low energies Ps formation must be treated nonperturbatively. We also look at Ps formation with inner shell electrons.Comment: 12 pages, 5 figures, to be published in Nuclear Instruments and Methods

The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings

CONTEXT. Gamma Doradus stars (hereafter gamma Dor stars) are known to exhibit gravity- and/or gravito-intertial modes that probe the inner stellar region near the convective core boundary. The non-equidistant spacing of the pulsation periods is an observational signature of the stars' evolution and current internal structure and is heavily influenced by rotation. AIMS. We aim to constrain the near-core rotation rates for a sample of gamma Dor stars, for which we have detected period spacing patterns. METHODS. We combined the asymptotic period spacing with the traditional approximation of stellar pulsation to fit the observed period spacing patterns using chi-squared optimisation. The method was applied to the observed period spacing patterns of a sample of stars and used for ensemble modelling. RESULTS. For the majority of stars with an observed period spacing pattern we successfully determined the rotation rates and the asymptotic period spacing values, though the uncertainty margins on the latter were typically large. This also resulted directly in the identification of the modes corresponding with the detected pulsation frequencies, which for most stars were prograde dipole gravity and gravito-inertial modes. The majority of the observed retrograde modes were found to be Rossby modes. We further discuss the limitations of the method due to the neglect of the centrifugal force and the incomplete treatment of the Coriolis force. CONCLUSION. Despite its current limitations, the proposed methodology was successful to derive the rotation rates and to identify the modes from the observed period spacing patterns. It forms the first step towards detailed seismic modelling based on observed period spacing patterns of moderately to rapidly rotating gamma Dor stars.Comment: 12 pages, 15 figures, 5 tables. Accepted for publication in Astronomy & Astrophysic

Least-squares deconvolution based analysis of stellar spectra

In recent years, astronomical photometry has been revolutionised by space missions such as MOST, CoRoT and Kepler. However, despite this progress, high-quality spectroscopy is still required as well. Unfortunately, high-resolution spectra can only be obtained using ground-based telescopes, and since many interesting targets are rather faint, the spectra often have a relatively low S/N. Consequently, we have developed an algorithm based on the least-squares deconvolution profile, which allows to reconstruct an observed spectrum, but with a higher S/N. We have successfully tested the method using both synthetic and observed data, and in combination with several common spectroscopic applications, such as e.g. the determination of atmospheric parameter values, and frequency analysis and mode identification of stellar pulsations.Comment: Proceedingspaper, 8 pages, 4 figures, appears in "Setting a New Standard in the Analysis of Binary Stars", Eds K. Pavlovski, A. Tkachenko, and G. Torres, EAS Publications Serie

Optimization modelling for analyzing fantasy sport games

In a fantasy sport game, participants act like a team manager building a team of real individual players of a professional sport. The real performances of these players (or their teams) are translated into points for their team managers. The managers’ aim is to collect as many points as possible thereby defeating the fantasy teams of opponents. First, we discuss a number of common game rule characteristics of fantasy sport games. Based on these characteristics, we present a mixed integer programming model to produce and analyze ex-post results for a large variety of fantasy sport games. We discuss how these results create value for both the game organizer and the participants. Finally, we apply our system in practice to a fantasy cycling game