5,016 research outputs found
The Beam Conditions Monitor of the LHCb Experiment
The LHCb experiment at the European Organization for Nuclear Research (CERN)
is dedicated to precision measurements of CP violation and rare decays of B
hadrons. Its most sensitive components are protected by means of a Beam
Conditions Monitor (BCM), based on polycrystalline CVD diamond sensors. Its
configuration, operation and decision logics to issue or remove the beam permit
signal for the Large Hadron Collider (LHC) are described in this paper.Comment: Index Terms: Accelerator measurement systems, CVD, Diamond, Radiation
detector
Error blindness and motivational significance: Shifts in networks centering on anterior insula co-vary with error awareness and pupil dilation
This investigation aims to further our understanding of the brain mechanisms underlying the awareness of one's erroneous actions. While all errors are registered as such in the rostral cingulate zone, errors enter awareness only when the anterior insula cortex is activated. Aware but not unaware errors elicit autonomic nervous system reactivity. Our aim is to investigate the hypothesis that activation in the insula during error awareness is related to autonomic arousal and to inter-regional interactions with other areas of the brain. To examine the role of the anterior insula in error awareness, we assessed its functional connectivity to other brain regions along with autonomic nervous system reactivity in young healthy participants who underwent simultaneous pupil-diameter and functional magnetic resonance imaging measurements while performing a complex and error-prone task. Error blindness was associated with failures to engage sufficient autonomic reactivity. During aware errors increased pupil-diameter along with increased task-related activation within, and increased connectivity between anterior insula and task-related networks suggested an increased capacity for action-control information transfer. Increased pupil-diameter during aware errors was furthermore associated with decreased activation of the default-mode network along with decreased insular connectivity with regions of the default mode system, possibly reflecting decreased task-irrelevant information processing. This shifting mechanism may be relevant to a better understanding of how the brain and the autonomic nervous system interact to enable efficient adaptive behavior during cognitive challenge
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Characterizing the Spread and Consequences of Mycoplasma ovipneumoniae on Bighorn Sheep (Ovis canadensis) in the Northern Basin and Range Ecosystem
North American bighorn sheep (Ovis canadensis) have experienced significant declines and population extirpations due to novel pathogens such as Mycoplasma ovipneumoniae. This disease continues to limit the population restoration of bighorn sheep. Therefore, understanding the demographic consequences of pathogen presence and the risk of contact between bighorn populations and potential sources of pathogens is vital to managing bighorn sheep populations effectively, especially for pathogens that cause respiratory pneumonia. My dissertation focuses on characterizing the spread and consequences of respiratory disease caused by M. ovipneumoniae in southeastern Oregon and northern Nevada. I carried out four interdisciplinary studies involving extensive fieldwork, epidemiological, genetic, geospatial, and statistical methodologies to determine factors influencing bighorn sheep demography and spatial ecology. My research relied in part on data provided by two state wildlife management agencies, Oregon Department of Fish and Wildlife (ODFW) and Nevada Department of Wildlife (NDOW), that captured adult female and male bighorn sheep, fitted them with GPS collars that generated and remotely transmitted remotely location data, and sampled them to generate diagnostics and genetic testing. I collected additional observational and non-invasive data within the system.
In Chapter 2, I investigated the effect of M. ovipneumoniae on juvenile survival within our study system. I used observational data of juveniles and PCR-testing of juveniles that were found dead to analyze juvenile survival relative to M. ovipneumoniae presence, population genetic diversity, and forage characteristics. That study showed that the presence of M. ovipneumoniae can cause extremely low juvenile survival but found little influence of population genetic diversity or nutritional effects on juvenile survival. In addition, the study showed that even very low prevalence of M. ovipneumoniae in adults can have harmful effects on juveniles and that targeted removals of infected adults should be considered.
In Chapter 3, I investigated the effect of exposure and infection of M. ovipneumoniae and other factors on GPS-collared adults using known-fate models. M. ovipneumoniae-exposed adults had lower survival than unexposed individuals, and I found evidence, albeit weaker, that adult survival was lower for males and in populations where genetic diversity was lower. The low prevalence of M. ovipneumoniae-exposed individuals suggests that chronic shedders and birth pulses maintain the pathogen. While targeted removals have been used as an effective tool to manage juvenile survival in bighorn sheep, these results indicate adults may benefit from this action too. I also recommended that management increase genetic diversity of populations that have suffered from sequential founder effects, although such action would have to be weighed carefully against the risk of increased disease exposure.
For Chapter 4, I used GPS collar data to investigate space and habitat use patterns – key features of host behavior that impact pathogen exposure and transmission, as well as gene flow and metapopulation function. I assessed utilization distributions, site fidelity, social affinity, and resource selection functions separately for male and female bighorn. Although resource selection by both sexes was quite similar within the same seasons, female bighorn sheep exhibited extremely high site fidelity and social affinity, much higher than observed in other systems. Site fidelity and social affinity of male bighorn sheep were significantly lower, with numerous interpopulation movements. Our findings suggest that male bighorn sheep are responsible for disease transmission between the populations and maintain gene flow within the system. Still, females' high site fidelity and social affinity have resulted in the low potential for colonization of unused habitat, and I identified several areas of potential habitat that are unused by females but could increase distribution or enhance connectivity if occupied.
In Chapter 5, I used the methodology of O’Brien et al. (2014) to estimate the risk of contact for each study population with potential sources of M. ovipneumoniae, including domestic sheep grazing allotments, other bighorn sheep populations, or potential sources of domestic sheep and goats. I found that all study populations had some probability of contact with other possible sources of infection risk, although those sources did not include known domestic sheep grazing allotments. This study therefore provides a tool to prioritize outreach to private landowners or management of disease within affected bighorn populations that may pose risk to other populations.
This study highlights the adverse effects of M. ovipneumoniae persistence on bighorn sheep population recovery and the complications of managing metapopulation connectivity in a disease-impacted system. Management options to control pathogen spread must balance connectivity's negative and positive consequences. The management agencies responsible for these bighorn populations have initiated test and remove programs to deal with asymptomatic carriers within the system. However, our findings suggest further actions may be needed to improve genetic diversity and promote habitat colonization while considering disease risks associated with these actions. Hopefully, the data presented
here inform efforts that help mitigate further exposure to novel strains of M. ovipneumoniae while maintaining necessary metapopulation functions
Bovine tuberculosis disturbs parasite functional trait composition in African buffalo
Novel parasites can have wide-ranging impacts, not only on host populations, but also on the resident parasite community. Historically, impacts of novel parasites have been assessed by examining pairwise interactions between parasite species. However, parasite communities are complex networks of interacting species. Here we used multivariate taxonomic and trait-based approaches to determine how parasite community composition changed when African buffalo (Syncerus caffer) acquired an emerging disease, bovine tuberculosis (BTB). Both taxonomic and functional parasite richness increased significantly in animals that acquired BTB than in those that did not. Thus, the presence of BTB seems to catalyze extraordinary shifts in community composition. There were no differences in overall parasite taxonomic composition between infected and uninfected individuals, however. The trait-based analysis revealed an increase in direct-transmitted, quickly replicating parasites following BTB infection. This study demonstrates that trait-based approaches provide insight into parasite community dynamics in the context of emerging infections
Context-dependent costs and benefits of tuberculosis resistance traits in a wild mammalian host
Disease acts as a powerful driver of evolution in natural host populations, yet individuals in a population often vary in their susceptibility to infection. Energetic trade-offs between immune and reproductive investment lead to the evolution of distinct life history strategies, driven by the relative fitness costs and benefits of resisting infection. However, examples quantifying the cost of resistance outside of the laboratory are rare. Here, we observe two distinct forms of resistance to bovine tuberculosis (bTB), an important zoonotic pathogen, in a free-ranging African buffalo (Syncerus caffer) population. We characterize these phenotypes as “infection resistance,” in which hosts delay or prevent infection, and “proliferation resistance,” in which the host limits the spread of lesions caused by the pathogen after infection has occurred. We found weak evidence that infection resistance to bTB may be heritable in this buffalo population (h2 = 0.10) and comes at the cost of reduced body condition and marginally reduced survival once infected, but also associates with an overall higher reproductive rate. Infection-resistant animals thus appear to follow a “fast” pace-of-life syndrome, in that they reproduce more quickly but die upon infection. In contrast, proliferation resistance had no apparent costs and was associated with measures of positive host health—such as having a higher body condition and reproductive rate. This study quantifies striking phenotypic variation in pathogen resistance and provides evidence for a link between life history variation and a disease resistance trait in a wild mammalian host population
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