1,942 research outputs found

    Finitely fibered Rosenthal compacta and trees

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    We study some topological properties of trees with the interval topology. In particular, we characterize trees which admit a 2-fibered compactification and we present two examples of trees whose one-point compactifications are Rosenthal compact with certain renorming properties of their spaces of continuous functions.Comment: Small changes, mainly in the introduction and in final remark

    A Bayesian inference framework to reconstruct transmission trees using epidemiological and genetic data

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    The accurate identification of the route of transmission taken by an infectious agent through a host population is critical to understanding its epidemiology and informing measures for its control. However, reconstruction of transmission routes during an epidemic is often an underdetermined problem: data about the location and timings of infections can be incomplete, inaccurate, and compatible with a large number of different transmission scenarios. For fast-evolving pathogens like RNA viruses, inference can be strengthened by using genetic data, nowadays easily and affordably generated. However, significant statistical challenges remain to be overcome in the full integration of these different data types if transmission trees are to be reliably estimated. We present here a framework leading to a bayesian inference scheme that combines genetic and epidemiological data, able to reconstruct most likely transmission patterns and infection dates. After testing our approach with simulated data, we apply the method to two UK epidemics of Foot-and-Mouth Disease Virus (FMDV): the 2007 outbreak, and a subset of the large 2001 epidemic. In the first case, we are able to confirm the role of a specific premise as the link between the two phases of the epidemics, while transmissions more densely clustered in space and time remain harder to resolve. When we consider data collected from the 2001 epidemic during a time of national emergency, our inference scheme robustly infers transmission chains, and uncovers the presence of undetected premises, thus providing a useful tool for epidemiological studies in real time. The generation of genetic data is becoming routine in epidemiological investigations, but the development of analytical tools maximizing the value of these data remains a priority. Our method, while applied here in the context of FMDV, is general and with slight modification can be used in any situation where both spatiotemporal and genetic data are available

    Transmission dynamics and prospects for the elimination of canine rabies

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    Rabies has been eliminated from domestic dog populations in Western Europe and North America, but continues to kill many thousands of people throughout Africa and Asia every year. A quantitative understanding of transmission dynamics in domestic dog populations provides critical information to assess whether global elimination of canine rabies is possible. We report extensive observations of individual rabid animals in Tanzania and generate a uniquely detailed analysis of transmission biology, which explains important epidemiological features, including the level of variation in epidemic trajectories. We found that the basic reproductive number for rabies, R<sub>0</sub>, is very low in our study area in rural Africa (∼1.2) and throughout its historic global range (<2). This finding provides strong support for the feasibility of controlling endemic canine rabies by vaccination, even near wildlife areas with large wild carnivore populations. However, we show that rapid turnover of domestic dog populations has been a major obstacle to successful control in developing countries, thus regular pulse vaccinations will be required to maintain population-level immunity between campaigns. Nonetheless our analyses suggest that with sustained, international commitment, global elimination of rabies from domestic dog populations, the most dangerous vector to humans, is a realistic goal

    An uncertainty principle for star formation -- III. The characteristic emission time-scales of star formation rate tracers

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    We recently presented a new statistical method to constrain the physics of star formation and feedback on the cloud scale by reconstructing the underlying evolutionary timeline. However, by itself this new method only recovers the relative durations of different evolutionary phases. To enable observational applications, it therefore requires knowledge of an absolute 'reference time-scale' to convert relative time-scales into absolute values. The logical choice for this reference time-scale is the duration over which the star formation rate (SFR) tracer is visible because it can be characterised using stellar population synthesis (SPS) models. In this paper, we calibrate this reference time-scale using synthetic emission maps of several SFR tracers, generated by combining the output from a hydrodynamical disc galaxy simulation with the SPS model SLUG2. We apply our statistical method to obtain self-consistent measurements of each tracer's reference time-scale. These include Hα{\alpha} and 12 ultraviolet (UV) filters (from GALEX, Swift, and HST), which cover a wavelength range 150-350 nm. At solar metallicity, the measured reference time-scales of Hα{\alpha} are 4.320.23+0.09{4.32^{+0.09}_{-0.23}} Myr with continuum subtraction, and 6-16 Myr without, where the time-scale increases with filter width. For the UV filters we find 17-33 Myr, nearly monotonically increasing with wavelength. The characteristic time-scale decreases towards higher metallicities, as well as to lower star formation rate surface densities, owing to stellar initial mass function sampling effects. We provide fitting functions for the reference time-scale as a function of metallicity, filter width, or wavelength, to enable observational applications of our statistical method across a wide variety of galaxies.Comment: 24 pages, 18 figures, 7 tables (including Appendices); published in MNRA

    PROPULSION IN ELITE LOW-POINT CLASSIFICATION RUGBY WHEELCHAIR ATHLETES

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    Wheelchair propulsion kinematics have been demonstrated to be dependent on chair configuration, although this knowledge is still limited in wheelchair rugby. This study monitored the propulsion kinematics during sprint performance in elite low-point wheelchair rugby athletes, with correlations between kinematics, athlete experience and configuration investigated. Increased experience was correlated with decreasing contact and push angles for the second push, as well as trends for the first and third pushes. Configuration parameters such as seat depth, seat angle, and seat depth-to-thigh length, were also shown to be correlated with kinematic variables. Findings provide important information for the configuration of wheelchairs to utilise efficient regions of their stroke and optimise sprint performance

    Integrating serological and genetic data to quantify cross-species transmission: brucellosis as a case study

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    Epidemiological data are often fragmented, partial, and/or ambiguous and unable to yield the desired level of understanding of infectious disease dynamics to adequately inform control measures. Here, we show how the information contained in widely available serology data can be enhanced by integration with less common type-specific data, to improve the understanding of the transmission dynamics of complex multi-species pathogens and host communities. Using brucellosis in Northern Tanzania as a case-study, we developed a latent process model based on serology data obtained from the field, to reconstruct Brucella transmission dynamics. We were able to identify sheep and goats as a more likely source of human and animal infection than cattle; however, the highly cross-reactive nature of Brucella spp. meant that it was not possible to determine which Brucella species (B. abortus or B. melitensis) is responsible for human infection. We extended our model to integrate simulated serology and typing data, and show that although serology alone can identify the host source of human infection under certain restrictive conditions, the integration of even small amounts (5%) of typing data can improve understanding of complex epidemiological dynamics. We show that data integration will often be essential when more than one pathogen is present and when the distinction between exposed and infectious individuals is not clear from serology data. With increasing epidemiological complexity, serology data become less informative. However, we show how this weakness can be mitigated by integrating such data with typing data, thereby enhancing the inference from these data and improving understanding of the underlying dynamics

    Genetic Deletion of the Clathrin Adaptor GGA3 Reduces Anxiety and Alters GABAergic Transmission

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    Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) is a monomeric clathrin adaptor that has been shown to regulate the trafficking of the Beta-site APP-cleaving enzyme (BACE1), which is required for production of the Alzheimer’s disease (AD)-associated amyloid βpeptide. Our previous studies have shown that BACE1 is degraded via the lysosomal pathway and that depletion of GGA3 results in increased BACE1 levels and activity owing to impaired lysosomal trafficking and degradation. We further demonstrated the role of GGA3 in the regulation of BACE1 in vivo by showing that BACE1 levels are increased in the brain of GGA3 null mice. We report here that GGA3 deletion results in novelty-induced hyperactivity and decreased anxiety-like behaviors. Given the pivotal role of GABAergic transmission in the regulation of anxiety-like behaviors, we performed electrophysiological recordings in hippocampal slices and found increased phasic and decreased tonic inhibition in the dentate gyrus granule cells (DGGC). Moreover, we found that the number of inhibitory synapses is increased in the dentate gyrus of GGA3 null mice in further support of the electrophysiological data. Thus, the increased GABAergic transmission is a leading candidate mechanism underlying the reduced anxiety-like behaviors observed in GGA3 null mice. All together these findings suggest that GGA3 plays a key role in GABAergic transmission. Since BACE1 levels are elevated in the brain of GGA3 null mice, it is possible that at least some of these phenotypes are a consequence of increased processing of BACE1 substrates

    Automated Foosball Table

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    This project is the second iteration of an automated foosball table for Yaskawa America as a trade show display. The table is meant to provide an interactive experience which highlights the speed and precision of the Yaskawa hardware. The first iteration of the project was mainly focused on creating the physical hardware for the system and to begin the basic programming for the system. This phase of the project was focused on finalizing the physical hardware of the system, implementing the vision system and to continue the basic programing of the system AI. A third team will be assigned to bring the project to completion by fully implementing the AI system and making any required changes to the physical hardware which are required. The automated Foosball system is comprised of two major system elements. The first element is the motor cabinet, which houses the PLC, motors and amplifiers used to actuate the system. It also acts as a display case for the motors system. The other major element is the foosball table itself, which is comprised of several subsystem components. The foosball table system contains a vision arch which houses the vision system, a playfield cover which prevents users from injury, and a roof which blocks direct lighting on the table. Several hardware components were created or modified during this phase of the project. The roof structure was designed and built complete this quarter, as were brackets which connected the motor cabinet and foosball table. A gap cover was also designed and built to cover an exposed portion of the motor cabinet. While not fully completed, the hardware used in the safety system has been begun and should be completed by the future team. The scoring system for the table was also approached during this phase of the project, and it was concluded that the current scoreboard should be redesigned. The original vision system started by the first team was found to be insufficient to meet the requirements of the foosball system. To simplify the process of creating the vision system, a Cognex Insight 7400 camera system was donate d to the project by Cognex. This camera system was found to be sufficient to meet the minimum requirements of the project with relatively little work. Future teams should focus on improving the frame rate of the vision system. The AI program developed during this phase is working and playable, though it is relatively crude. Future iterations of the AI program should use sequential function charts to organize the program and predictive play should be implemented. More sophisticated play strategies can also be implemented to improve the playability of the system
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