Ca II triplet spectroscopy of RGB stars in NGC 6822: kinematics and metallicities

We present a detailed analysis of the chemistry and kinematics of red giants in the dwarf irregular galaxy NGC 6822. Spectroscopy at 8500 Angstroms was acquired for 72 red giant stars across two fields using FORS2 at the VLT. Line of sight extinction was individually estimated for each target star to accommodate the variable reddening across NGC 6822. The mean radial velocity was found to be v_helio = (52.8 +/- 2.2) km/s with dispersion rms = 24.1 km/s, in agreement with other studies. Ca II triplet equivalent widths were converted into [Fe/H] metallicities using a V magnitude proxy for surface gravity. The average metallicity was [Fe/H] = (-0.84 +/- 0.04) with dispersion rms = 0.31 dex and interquartile range 0.48. Our assignment of individual reddening values makes our analysis more sensitive to spatial variations in metallicity than previous studies. We divide our sample into metal-rich and metal-poor stars; the former are found to cluster towards small radii with the metal-poor stars more evenly distributed across the galaxy. The velocity dispersion of the metal-poor stars is higher than that of the metal-rich stars; combined with the age-metallicity relation this indicates that older populations have either been dynamically heated or were born in a less disclike distribution. The low ratio (v_rot/v_rms) suggests that within the inner 10', NGC 6822's stars are dynamically decoupled from the HI gas, possibly in a thick disc or spheroid.Comment: 15 pages, 12 figures, includes tabular dat

Perception of affect in unfamiliar music

This thesis comprises a body of work that investigates affect perception of unfamiliar music, with a focus on both the role of potentially culture-independent psychoacoustic features that are intrinsic to a musical signal (e.g. roughness, harmonicity, spectral entropy, and average pitch) and extrinsic culture-dependent features (e.g. familiarity through exposure and evaluative conditioning). Much previous research in music perception has suggested that extrinsic features are of more importance than intrinsic features, but has not systematically tested the impact of intrinsic features on responses to unfamiliar music. The thesis discusses four experiments conducted to test the role of the above mentioned features using musical stimuli that are unfamiliar to participants. By using musical stimuli that are unfamiliar to participants, additional evidence can be provided for the cultural- independence of the tested intrinsic features. In order to achieve this unfamiliarity, two approaches were used. The first approach examined affective responses to chords from the unfamiliar microtonal Bohlen-Pierce system in Western listeners, the second approach tested affective responses to Western musical harmony in remote villages in Papua New Guinea, with varying levels of familiarity with Western music. The results of the listening experiments using Bohlen-Pierce suggest that the tested underlying culture-independent psychoacoustic features consistently impact affective rat- ings more strongly than do the experimentally manipulated culture-dependent factors of familiarity and evaluative conditioning. The results from the cross-cultural experiment suggest a strong role of familiarity on valence ratings of Western cadences and melodies. In summary, by using unfamiliar music (through the use of an unfamiliar microtonal system or through cross-cultural research) we can show that, in addition to extrinsic culture-dependent features, intrinsic features are fundamental for affect perception in music

Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies

Spectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to unambiguously determine the evolutionary histories of galaxies. Using FORS1 in Multi-Object Spectroscopy mode on ANTU (UT1) at the ESO-VLT on Paranal we obtained near infrared spectra from which we measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of Red Giant Branch stars, selected from ESO-NTT optical (I, V-I) photometry of three nearby, Local Group, galaxies: the Sculptor Dwarf Spheroidal, the Fornax Dwarf Spheroidal and the Dwarf Irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption line feature, centered at 8500A, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991) and Rutledge, Hesser & Stetson (1997). We measured metallicities for 37 stars in Sculptor, 32 stars in Fornax, and 23 stars in NGC 6822, yielding more precise estimates of the metallicity distribution functions for these galaxies than it is possible to obtain photometrically. In the case of NGC 6822, this is the first direct measurement of the abundances of the intermediate-age and old stellar populations. We find metallicity spreads in each galaxy which are broadly consistent with the photometric width of the Red Giant Branch, although the abundances of individual stars do not always appear to correspond to their colour. This is almost certainly predominantly due to a highly variable star formation rate with time in these galaxies, which results in a non-uniform, non-globular-cluster-like, evolution of the Ca/Fe ratio.Comment: Accepted for publication in MNRA

The role of partisan cues in voter mobilization campaigns: evidence from a randomized field experiment

The transmission of partisan appeals during election campaigns is widely believed to aid the formation of citizens' candidate preferences, or to serve as rallying cries, thereby increasing turnout. While laboratory and survey experiments show that partisan cues help citizens decide between candidates, and partisan elections see higher turnout than non-partisan elections, it is unclear if party labels and partisan rhetoric cause voters to turn out in higher numbers in real-world elections. We exploit a low-information election in the UK to randomly assign whether campaign phone messages include strong partisan cues or promote the same candidate without such cues. Whereas we find no significant difference in the overall effectiveness of messages with and without partisan cues at increasing turnout, the effectiveness of the former is moderated by party preference: Consistent with the use of acceptance-rejection heuristics, campaign calls with partisan cues are more likely to mobilize party supporters than rival partisans

All in the Family: Partisan Disagreement and Electoral Mobilization in Intimate Networks - a Spillover Experiment

We advance the debate about the impact of political disagreement in social networks on electoral participation by addressing issues of causal inference common in network studies, focusing on voters' most important context of interpersonal influence: the household. We leverage a randomly assigned spillover experiment conducted in the United Kingdom, combined with a detailed database of pretreatment party preferences and public turnout records, to identify social influence within heterogeneous and homogeneous partisan households. Our results show that intrahousehold mobilization effects are larger as a result of campaign contact in heterogeneous than in homogeneous partisan households, and larger still when the partisan intensity of the message is exogenously increased, suggesting discussion rather than behavioral contagion as a mechanism. Our results qualify findings from influential observational studies and suggest that within intimate social networks, negative correlations between political heterogeneity and electoral participation are unlikely to result from political disagreement

Sulphur in the Sculptor dwarf spheroidal galaxy - Including NLTE corrections

In Galactic halo stars, sulphur has been shown to behave like other $\alpha$-elements, but until now, no comprehensive studies have been done on this element in stars of other galaxies. Here, we use high-resolution ESO VLT/FLAMES/GIRAFFE spectra to determine sulphur abundances for 85 stars in the Sculptor dwarf spheroidal galaxy, covering the metallicity range $-2.5\leq \text{[Fe/H]} \leq-0.8$. The abundances are derived from the S~I triplet at 9213, 9228, and 9238~\AA. These lines have been shown to be sensitive to departure from local thermodynamic equilibrium, i.e. NLTE effects. Therefore, we present new NLTE corrections for a grid of stellar parameters covering those of the target stars. The NLTE-corrected sulphur abundances in Sculptor show the same behaviour as other $\alpha$-elements in that galaxy (such as Mg, Si, and Ca). At lower metallicities ($\text{[Fe/H]}\lesssim-2$) the abundances are consistent with a plateau at $\text{[S/Fe]}\approx+0.16$, similar to what is observed in the Galactic halo, $\text{[S/Fe]}\approx+0.2$. With increasing [Fe/H], the [S/Fe] ratio declines, reaching negative values at $\text{[Fe/H]}\gtrsim-1.5$. The sample also shows an increase in [S/Mg] with [Fe/H], most probably because of enrichment from Type Ia supernovae.Comment: 9 pages, 11 figures, 2 tables + 3 online tables, accepted in A&

Malaria intervention scale-up in Africa : effectiveness predictions for health programme planning tools, based on dynamic transmission modelling

Scale-up of malaria prevention and treatment needs to continue to further important gains made in the past decade, but national strategies and budget allocations are not always evidence-based. Statistical models were developed summarizing dynamically simulated relations between increases in coverage and intervention impact, to inform a malaria module in the Spectrum health programme planning tool.; The dynamic Plasmodium falciparum transmission model OpenMalaria was used to simulate health effects of scale-up of insecticide-treated net (ITN) usage, indoor residual spraying (IRS), management of uncomplicated malaria cases (CM) and seasonal malaria chemoprophylaxis (SMC) over a 10-year horizon, over a range of settings with stable endemic malaria. Generalized linear regression models (GLMs) were used to summarize determinants of impact across a range of sub-Sahara African settings.; Selected (best) GLMs explained 94-97 % of variation in simulated post-intervention parasite infection prevalence, 86-97 % of variation in case incidence (three age groups, three 3-year horizons), and 74-95 % of variation in malaria mortality. For any given effective population coverage, CM and ITNs were predicted to avert most prevalent infections, cases and deaths, with lower impacts for IRS, and impacts of SMC limited to young children reached. Proportional impacts were larger at lower endemicity, and (except for SMC) largest in low-endemic settings with little seasonality. Incremental health impacts for a given coverage increase started to diminish noticeably at above ~40 % coverage, while in high-endemic settings, CM and ITNs acted in synergy by lowering endemicity. Vector control and CM, by reducing endemicity and acquired immunity, entail a partial rebound in malaria mortality among people above 5 years of age from around 5-7 years following scale-up. SMC does not reduce endemicity, but slightly shifts malaria to older ages by reducing immunity in child cohorts reached.; Health improvements following malaria intervention scale-up vary with endemicity, seasonality, age and time. Statistical models can emulate epidemiological dynamics and inform strategic planning and target setting for malaria control

V4: Sub-basin management and governance of rainwater and small reservoirs

A strong international consensus has been created regarding the need for Integrated Water Resources Management (IWRM) and what it means. The river basin is then invariably singled out as the natural unit for organizing water management. Two main reasons for these shortcomings are generally presented: a lack of political will and socio-political externalities. Calls for more reforms follow but they rarely question policy models themselves. As a consequence, they face the same shortcomings they were meant to address. This project aims at understanding the processes that govern IWRM policy-making, practices and research in the Volta Basin (Ghana and Burkina Faso)

Mortality changes after grants from the Global Fund to Fight AIDS, tuberculosis and malaria: An econometric analysis from 1995 to 2010

Background: Since its founding in 2002, the Global Fund to Fight AIDS, Tuberculosis, and Malaria (Global Fund) has become the dominant multilateral health financier in low- and middle-income countries. The health impact of the Global Fund remains unknown because existing evaluations measure intermediate outcomes or do not account for preexisting and counterfactual trends. Methods: We conducted an econometric analysis of data from all countries eligible to receive Global Fund grants from 1995 to 2010, prior to and during the Global Fund's activities. We analyzed three outcomes: all-cause adult (15-59 years), all-cause under-five, and malaria-specific under-five mortality. Our main exposure was a continuous longitudinal measure of Global Fund disbursements per capita. We used panel fixed effect regressions, and analyzed mortality trends controlling for health spending, health worker density (a measure of health system capacity), gross domestic product, urbanization, and country fixed-effects. Results and discussion: We find that following Global Fund disbursements, adult mortality rate declined by 1.4 % per year faster with every $10 per capita increase in disbursements (p∈=∈0.005). Similarly, malaria-specific under-five mortality declined by 6.9$10 high per capita Global Fund disbursements. However, we find no association between Global Fund support and all-cause under-five mortality. These findings were consistent after subanalyses by baseline HIV prevalence, adjusting for effects of concurrent health aid from other donors, and varying time lags between funding and mortality changes. Conclusions: Grants from the Global Fund are closely related to accelerated reductions in all-cause adult mortality and malaria-specific under-five mortality. However, up to 2010 the Global Fund has not measurably contributed to reducing all-cause under-five mortality

Crossing the Line: Evidence for the Categorization Theory of Spatial Voting

Bølstad and Dinas (2017) propose a model of spatial voting, based on social identity theory, that suggests supporting a candidate/policy on the other side of the ideological spectrum has a disutility that is not accounted for by common spatial models. Unfortunately, the data they use cannot speak directly to whether the disutility arises because individuals perceive their ideology as a social identity. We present the results of an experimental study that measures the norm against crossing the ideological spectrum; tests the cost of doing so, controlling for spatial effects; and demonstrates that this cost increases with the salience and strength of identity norms. By demonstrating the norm mechanism for the disutility of crossing the ideological spectrum, we provide strong support for B&D\u27s model