Improved neutrino point source search method for IceCube's high energy starting event sample

High Energy Neutrino Astronomy is a new field that has the potential to solve the mystery of the origin of cosmic ray particles, the highest energy particles that have been observed. The IceCube Neutrino Observatory has recently discovered the existence of a high energy astrophysical neutrino flux. We are able to calculate for our "track-like" sub-population of events a directional origin to within a square degree, yet it remains difficult to establish whether these neutrinos come from bright distinguishable sources or a sea of individual weak neutrino producers. The current goal of neutrino point source analyses is the observation of a bright neutrino source above expected background rates of neutrinos, in our case both from a uniform distribution of astrophysical neutrino sources and background neutrino events produced in cosmic ray interactions with our own atmosphere. This thesis presents a new form of point source analysis that tests the data under the model of the combination of multiple background hypotheses and a single point source hypothesis, where the predicted background distributions can be produced through simulation. We apply this analysis to the High Energy Starting Event sample produced by IceCube, and show how this analysis differs to previous analyses on these events. We find that the fit using a background in the likelihood that does not match the distribution of the events can result in a bias in the fitted strength of a point source, and that the relative power of the analysis compared to the previous point source analysis can depend on the point source location, where the power is seen to be comparable in the southern sky but improved in the northern sky. Our results from applying our new form of point source analysis to the data do not show strong evidence for a point source hypothesis, with p-values of 0.468 for all events in our sample and 0.922 for a subset of shower topology events in our sample.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 201

Multimessenger search for sources of gravitational waves and high-energy neutrinos: Initial results for LIGO-Virgo and IceCub

We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007–2010. These include parts of the 2005–2007 run and the 2009–2010 run for LIGO-Virgo, and IceCube’s observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of 10−2  M⊙c2 at ∼150  Hz with ∼60  ms duration, and high-energy neutrino emission of 1051  erg comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the source rate below 1.6×10−2  Mpc−3 yr−1. We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitational-wave detector era

Physiological Correlates of Volunteering

We review research on physiological correlates of volunteering, a neglected but promising research field. Some of these correlates seem to be causal factors influencing volunteering. Volunteers tend to have better physical health, both self-reported and expert-assessed, better mental health, and perform better on cognitive tasks. Research thus far has rarely examined neurological, neurochemical, hormonal, and genetic correlates of volunteering to any significant extent, especially controlling for other factors as potential confounds. Evolutionary theory and behavioral genetic research suggest the importance of such physiological factors in humans. Basically, many aspects of social relationships and social activities have effects on health (e.g., Newman and Roberts 2013; Uchino 2004), as the widely used biopsychosocial (BPS) model suggests (Institute of Medicine 2001). Studies of formal volunteering (FV), charitable giving, and altruistic behavior suggest that physiological characteristics are related to volunteering, including specific genes (such as oxytocin receptor [OXTR] genes, Arginine vasopressin receptor [AVPR] genes, dopamine D4 receptor [DRD4] genes, and 5-HTTLPR). We recommend that future research on physiological factors be extended to non-Western populations, focusing specifically on volunteering, and differentiating between different forms and types of volunteering and civic participation

Reducing Inter-Organizational Barriers In The Medical Sector With Simulation

This paper describes how a simulation model is successfully being used as a communication tool following the introduction of a new law on research projects involving humans. The law caused some resistance at the local medical ethical research boards, mainly because of their uncertainty about imposed changes. The challenge was to communicate the changes to a large number of organizations. An animation model that explained the communication procedures between local medical ethical boards and the central agency was presented at a workshop attended by representatives of all the local boards. The model proved to be a powerful method of providing the audience with a lot of information in a short time, establishing a joint problem definition, and focusing discussions on the important issues. The animation model was a useful instrument in providing a smooth implementation of the law

Deletion of TnAbaR23 results in both expected and unexpected antibiogram changes in a multidrug-resistant acinetobacter baumannii strain

Since the 2006 discovery of the Acinetobacter baumannii strain AYE AbaR1 resistance island, similar elements have been reported in numerous members of this species. As AbaR1 is distantly related to Tn7, we have renamed it TnAbaR1. TnAbaR transposons are known to carry multiple antibiotic resistance- and efflux-associated genes, although none have been experimentally studied en bloc. We deleted the TnAbaR transposon in A. baumannii A424, which we have designated TnAbaR23, and characterized independent deletion mutants DCO163 and DCO174. The NotI pulsed-field gel electrophoresis (PFGE) profile of strain DCO174 was consistent with targeted deletion of TnAbaR23 alone, but strain DCO163 apparently harbored a second large genomic deletion. Nevertheless, “subtractive amplification” targeting 52 TnAbaR and/or resistance-associated loci yielded identical results for both mutants and highlighted genes lost relative to strain A424. PCR mapping and genome sequencing revealed the entire 48.3-kb sequence of TnAbaR23. Consistent with TnAbaR23 carrying two copies of sul1, both mutants exhibited markedly increased susceptibility to sulfamethoxazole. In contrast, loss of tetAR(A) resulted in only a minor and variable increase in tetracycline susceptibility. Despite not exhibiting a growth handicap, strain DCO163 was more susceptible than strain DCO174 to 9 of 10 antibiotics associated with mutant-to-mutant variation in susceptibility, suggesting impairment of an undefined resistance-associated function. Remarkably, despite all three strains sharing identical gyrA and parC sequences, the ciprofloxacin MIC of DCO174 was >8-fold that of DCO163 and A424, suggesting a possible paradoxical role for TnAbaR23 in promoting sensitivity to ciprofloxacin. This study highlights the importance of experimental scrutiny and challenges the assumption that resistance phenotypes can reliably be predicted from genotypes alone