Although Kenya is often considered an African success story, its political climate became increasingly repressive under its second president, Daniel arap Moi. Widner charts the transformation of the ...Kenya African National Union (KANU) from a weak, loosely organized political party under Jomo Kenyatta into an arm of the president's office, with "watchdog" youth wings and strong surveillance and control functions, under Moi. She suggests that single-party systems have an inherent tendency to become "party-states," or single-party regimes in which the head of state uses the party as a means of control. The speed and extent of these changes depend on the countervailing power of independent interest groups, such as business associations, farmers, or professionals. Widner's study offers important insights into the dynamics of party systems in Africa.
We show that individuals’ macroeconomic expectations are influenced by their socioeconomic status (SES). People with higher income or higher education are more optimistic about future macroeconomic ...developments, including business conditions, the national unemployment rate, and stock market returns. The spread in beliefs between highand low-SES individuals diminishes significantly during recessions. A comparison with professional forecasters and historical data reveals that the beliefs wedge reflects excessive pessimism on the part of low-SES individuals. SES-driven expectations help explain why higher-SES individuals are more inclined to invest in the stock market and more likely to consider purchasing homes, durable goods, or cars.
It is now well established that globular clusters (GCs) exhibit star-to-star light-element abundance variations (known as multiple populations, MPs). Such chemical anomalies have been found in ...(nearly) all the ancient GCs (more than 10 Gyr old) of our Galaxy and its close companions, but so far no model for the origin of MPs is able to reproduce all the relevant observations. To gain new insights into this phenomenon, we have undertaken a photometric Hubble Space Telescope survey to study clusters with masses comparable to that of old GCs, where MPs have been identified, but with significantly younger ages. Nine clusters in the Magellanic Clouds with ages between similar to 1.5 and 11 Gyr have been targeted in this survey. We confirm the presence of MPs in all clusters older than 6 Gyr and we add NGC 1978 to the group of clusters for which MPs have been identified. With an age of similar to 2 Gyr, NGC 1978 is the youngest cluster known to host chemical abundance spreads found to date. We do not detect evident star-to-star variations for slightly younger massive clusters (similar to 1.7 Gyr), thus pointing towards an unexpected age dependence for the onset of MPs. This discovery suggests that the formation of MPs is not restricted to the early Universe and that GCs and young massive clusters share common formation and evolutionary processes.
Abstract
We have recently shown that the ∼2 Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations in N/Fe. These can be seen as ...a splitting or spread in the subgiant and red giant branches (SGB and RGB) when certain photometric filter combinations are used. Because of its relative youth, NGC 1978 can be used to place stringent limits on whether multiple bursts of star formation have taken place within the cluster, as predicted by some models for the origin of multiple populations. We carry out two distinct analyses to test whether multiple star formation epochs have occurred within NGC 1978. First, we use ultraviolet colour--magnitude diagrams (CMDs) to select stars from the first and second population along the SGB, and then compare their positions in optical CMDs, where the morphology is dominantly controlled by age as opposed to multiple population effects. We find that the two populations are indistinguishable, with age differences of 1 ± 20 Myr between them. This is in tension with predictions from the asymptotic giant branch scenario for the origin of multiple populations. Second, we estimate the broadness of the main-sequence turn-off (MSTO) of NGC 1978 and we report that it is consistent with the observational errors. We find an upper limit of ∼65 Myr on the age spread in the MSTO of NGC 1978. This finding is in conflict with the age spread scenario as origin of the extended MSTO in intermediate-age clusters, while it fully supports predictions from the stellar rotation model.
We use over 20 yrs (1996–2017) of the European Space Agency's (ESA) radar interferometry (InSAR) observations to investigate the postseismic deformation of the Tabas fold segment following the 1978 ...Mw 7.3 Tabas-e-Golshan earthquake in eastern Iran. We generated maps of satellite line-of-sight (LOS) velocity using two ERS descending tracks (1996–1999), one Envisat descending track (2003–2010), one Sentinel-1A descending track (2014–2017) and one Sentinel-1A ascending track (2014–2017). The LOS velocity shows afterslip continuing for at least 40 yrs after the earthquake. Elastic dislocation modelling based on the InSAR measurements reveals a decrease in postseismic velocities from 5.0 ± 0.8 mm/yr in 1996–1999 to 3.9 ± 0.6 mm/yr in 2003–2005, 3.0 ± 0.4 mm/yr in 2006–2010, and a present rate of 2.3 ± 0.6 mm/yr in 2014–2017. The rates decay with time, t, as 1/t, consistent with the predictions of a simple block-slider model. We then combine the InSAR rates and our previous estimates of the total earthquake slip derived from optical image matching and DEM differencing to explore the frictional behaviour of the Tabas fold. We obtained a rate-and-state parameter a−b≈0.003, indicating rate-strengthening frictional behaviour of the Tabas fault. We also inferred a minimum coseismic slip of 4.7 m, which might have driven bedding-plane shear at shallow depth, resulting in distributed fold growth and secondary faulting observed in the field. The results imply that both coseismic slip and afterslip have occurred in the same location. One possible mechanism to explain such a phenomenon is that the frictional parameter a−b is small enough to allow dynamic ruptures to propagate into rate-strengthening regions.
•We measured postseismic slip 40 years after the 1978 Tabas earthquake using InSAR.•Sentinel-1 measurements show a mean afterslip rate of 2.3 ± 0.6 mm/yr in 2014–2017.•The rates of afterslip decay with time, t, as 1/t.•We obtained a rate-and-state parameter a−b≈0.003, i.e. rate-strengthening behaviour.•Small frictional parameters allow seismic ruptures in rate-strengthening regions.
ABSTRACT
Nearly all of the well-studied ancient globular clusters (GCs), in the Milky Way and in nearby galaxies, show star-to-star variations in specific elements (e.g. He, C, N, O, Na, and Al), ...known as ‘multiple populations’ (MPs). However, MPs are not restricted to ancient clusters, with massive clusters down to ∼2 Gyr showing signs of chemical variations. This suggests that young and old clusters share the same formation mechanism but most of the work to date on younger clusters has focused on N variations. Initial studies even suggested that younger clusters may not host spreads in other elements beyond N (e.g. Na), calling into question whether these abundance variations share the same origin as in the older GCs. In this work, we combine Hubble Space Telescope (HST) photometry with Very Large Telescope (VLT)/Multi-Unit Spectroscopic Explorer (MUSE) spectroscopy of a large sample of red giant branch (RGB) stars (338) in the Large Magellanic Cloud cluster NGC 1978, the youngest globular to date with reported MPs in the form of N spreads. By combining the spectra of individual RGB stars into N-normal and N-enhanced samples, based on the ‘chromosome map’ derived from HST, we search for mean abundance variations. Based on the NaD line, we find a Na difference of ΔNa/Fe = 0.07 ± 0.01 between the populations. While this difference is smaller than typically found in ancient GCs (which may suggest a correlation with age), this result further confirms that the MP phenomenon is the same, regardless of cluster age and host galaxy. As such, these young clusters offer some of the strictest tests for theories on the origin of MPs.
Militarizing Sri Lanka is a study of the militarization that has buttressed the war between the Sri Lankan state and the LTTE for over two decades. It highlights militarization as a process through ...which the ideology of militarism is shaped and shared in a manner that makes militant solutions to conflict a part of institutional structures and ways of thought. It foregrounds militarization as activity and agency, capable of adaptation and transforming society in significant ways; and as a deeply gendered, contingent and shifting process. It also analyzes both the construction and resistance to militarization and militarism, but in a manner that draws attention to their relationality rather than as self-evidently oppositional categories.
On December 12, 1963, people across Kenya joyfully celebrated independence from British colonial rule, anticipating a bright future of prosperity and social justice. As the nation approaches the ...fiftieth anniversary of its independence, however, the people's dream remains elusive. During its first five decades Kenya has experienced assassinations, riots, coup attempts, ethnic violence, and political corruption. The ranks of the disaffected, the unemployed, and the poor have multiplied. In this authoritative and insightful account of Kenya's history from 1963 to the present day, Daniel Branch sheds new light on the nation's struggles and the complicated causes behind them.
Branch describes how Kenya constructed itself as a state and how ethnicity has proved a powerful force in national politics from the start, as have disorder and violence. He explores such divisive political issues as the needs of the landless poor, international relations with Britain and with the Cold War superpowers, and the direction of economic development. Tracing an escalation of government corruption over time, the author brings his discussion to the present, paying particular attention to the rigged election of 2007, the subsequent compromise government, and Kenya's prospects as a still-evolving independent state.
PDF
