Large-scale fluctuations in the cosmic ionising background: the impact of beamed source emission

When modelling the ionisation of gas in the intergalactic medium after reionisation, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that large-scale ionisation rate fluctuations can have an observable impact on statistics of the Lyman-alpha forest. We extend such calculations to include beaming of sources, which has previously been neglected but which is expected to be important if quasars dominate the ionising photon budget. Beaming has two effects: first, the physical number density of ionising sources is enhanced relative to that directly observed; and second, the radiative transfer itself is altered. We calculate both effects in a hard-edged beaming model where each source has a random orientation, using an equilibrium Boltzmann hierarchy in terms of spherical harmonics. By studying the statistical properties of the resulting ionisation rate and HI density fields at redshift $z\sim 2.3$, we find that the two effects partially cancel each other; combined, they constitute a maximum $5\%$ correction to the power spectrum $P_{\mathrm{HI}}(k)$ at $k=0.04 \, h/\mathrm{Mpc}$. On very large scales ($k<0.01\, h/\mathrm{Mpc}$) the source density renormalisation dominates; it can reduce, by an order of magnitude, the contribution of ionising shot-noise to the intergalactic HI power spectrum. The effects of beaming should be considered when interpreting future observational datasets.Comment: 8 pages, 4 figure

Bursty star formation feedback and cooling outflows

We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circumgalactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disk can be modelled as a rapidly moving bubble of hot gas at $\mathrm{\sim1\;kpc}$ above disk, then ask what happens as it moves out further into the halo around the galaxy on $\mathrm{\sim 100\;kpc}$ scales. To do this we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the 'burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in the CGM may therefore change in response to the detailed historical pattern of star formation. For instance, outflows generated by star formation with short, intense bursts contain up to 60 per cent of their gas mass at temperatures $<5 \times 10^4\,\mathrm{K}$; for near-continuous star formation the figure is $\lesssim$ 5 per cent. Further study of cosmological simulations, and of idealised simulations with e.g., metal-cooling, magnetic fields and/or thermal conduction, will help to understand the precise signature of bursty outflows on observed ion abundances.Comment: 8 pages, 6 figures, accepted in MNRA

Antkey: a web-based tool for the identification and study of invasive, introduced and commonly intercepted ants

Dissertação de mestrado em Biocinética, apresentada à Faculdade de Ciências do Desporto e Educação Física da Universidade de CoimbraO Relative Age Effect (RAE), é a diferença de idade cronológica que existe de uma criança ou adolescente que nasceu perto do início do ano de competição para aquela que nasceu perto do final desse mesmo ano. No futebol, esta diferença dentro do mesmo escalão de competição leva a que existam jogadores que compitam entre si com diferentes níveis de maturity-status. Levando por sua vez a uma tendência na seleção e identificação de jogadores mais velhos em prol dos jogadores mais novos, apenas pelas diferenças maturacionais e não pelas diferenças na qualidade de jogo. É objetivo deste trabalho verificar a existência do RAE nos principais campeonatos europeus, nos escalões de formação Portugueses, e por fim no Campeonato da Europa de futebol UEFA Euro2012, desde os escalões seniores aos sub-17. Metodologia: A amostra recolhida para este estudo totaliza 5592 jogadores federados de diferentes países e níveis de competição, todos eles do sexo masculino com idades compreendidas entre 14-43 anos. Para dar resposta às diferentes questões criadas para este estudo dividiu-se a amostra total em dois grupos distintos: O grupo Internacional (n=658) e o grupo Nacional (n=4934). Foi considerado valores estatisticamente significativos quando o grau de significância era igual ou menor que 0,05 (p≤0,05). Resultados: Foi encontrado diferenças estatisticamente significativas para todos campeonatos seniores, exceto os campeonatos seniores portugueses de nível competitivo mais baixo. Todos os campeonatos jovens portugueses apresentaram diferenças estatisticamente significativas. Relativamente às competições internacionais, apenas os campeonatos Sub19 e Sub17 apresentaram um RAE estatisticamente significativo. Conclusões: Com este trabalho verifica-se que o RAE está bastante presente tanto em Portugal como na Europa. Verifica-se igualmente que quanto mais alto o nível competitivo, maior a presença do RAE. Sendo as competições relativas aos escalões de formação as que apresentam dados com maior relevância estatística. Abstract The time spacing between the chronological age from one child/adolescent and another, leads to substantial differences in their maturity-status. This phenomenon is known as Relative Age Effect (RAE). In soccer, the existence of this phenomenon in children within the same level of competition provides to the older children more opportunities of competing and better training facilities. This happens only because the mechanisms of talent identification from the clubs chose the older children instead of their pears, identifying them as most talented based only in their physical and physiological attributes without consideration of their level of maturation, growth and development. Methodology: The total sample for this study contains 5592 registered players from different countries and different levels of competition. All subjects from the sample were male aged 14-43 years. To respond to the different questions of the study, the sample was divided in two distinct groups: The International group (n=658) and the National group (n=4934). Results were considered statistically significant when the level of significance was equal to or less than 0,05 (p≤0,05). Results: Has been found statistically significant differences for all senior competition, except the Portuguese senior competitions with the lower competitive level. All Portuguese youth competition had results statistically different. Concerning to the International competitions, only the U19 and U17 competitions had a significant RAE. Conclusions: With this study, it appears that the RAE is very present both in Portugal and Europe. It also appears, the higher their competitive level, greater the presence of the RAE. Being the competitions relating to youth teams that present data with greater statistical significance

Prevalence, impacts, and implications of odorous house ant colonies within active American robin nests

The odorous house ant (Tapinoma sessile Say) is a cosmopolitan ant species in the Midwest known to nest in a variety of habitats. Polygynous and seasonally polydomous, it can be found nesting in both urban and natural areas, including within homes and bird nests. While previous studies have noted T. sessile colonies in active bird nests, no studies have been conducted examining the prevalence of this phenomenon and the impact it may have on nesting dynamics. In this study, we examine the prevalence of T. sessile colonies inhabiting nests of American robins from Midwestern Illinois and considered the potential relationships between the presence of colonies and the fledging success of nestlings, nest parasite loads, and presence of other nest dwelling arthropod species. Robin nests were located at multiple field sites, urban and rural, and monitored until the nestlings fledged or perished. Following abandonment nests were collected, frozen, and later sieved to collect all arthropods within the nest which were identified to order and morphospecies. We compare our findings to ongoing studies on the prevalence and impacts of T. sessile colonies in other species of Midwestern birds. Future work will examine properties of bird nests that are attractive to T. sessile colonies and relationships between the presence of T. sessile colonies and nestling immune function and stress.Ope

Rhode Island State Council on the Arts (1979-1992): Report 02

.csv file with the outcome data for predatory trials in the restraint experimen

Assessing the impact of very large volcanic eruptions on the risk of extreme climate events

Very large volcanic eruptions have substantial impacts on the climate, causing global cooling and major changes to the hydrological cycle. While most studies have focused on changes to mean climate, here we use a large ensemble to assess the impact on extreme climate for three years following tropical and extratropical eruptions of different sulfur emission strength. We focus on the impact of an extremely large eruption, injecting 40 Tg sulfur into the stratosphere, which could be expected to occur approximately twice a millennium. Our findings show that the eruption would have a profound effect on large areas of the globe, resulting in extremely rare drought events that under normal circumstances would occur once every century becoming very likely. Several regions such as West Africa, South and East Asia and the Maritime continent are particularly affected with the expected climate shifting well outside the usual range, by up to five standard deviations. These results have important consequences as they indicate that a severe drought in multiple breadbasket regions should be expected following a large eruption. The risk of heavy rainfall tends to decrease over the same regions but by a reduced amount, heatwaves become extremely rare, however the chance of extreme Winter cold surges do not increase by a corresponding amount, since widespread parts of the Northern Hemisphere display a winter warming. Our results show that the location of the eruption is crucial for the change in extremes, with overall changes larger for a Northern Hemisphere eruption than a tropical and Southern Hemisphere eruption, although there is a regional dependency. Simulations of different eruptions with similar forcing distributions but with different sizes are consistent with a linear relationship, however for smaller eruptions the internal variability tends to become dominant and the effect on extreme climate less detectable