Who cares about Africa? British and American conservatisms in African development

Stefan Andreasson examines how the Republican and Conservative parties dealt with African development since the late Cold War era. He explains why American input has been more prominent, while the British have come to resign themselves to a managed decline in relations with Africa. Who cares about Africa

A general approach for all-visible-light switching of diarylethenes through triplet sensitization using semiconducting nanocrystals

Coupling semiconducting nanocrystals (NCs) with organic molecules provides an efficient route to generate and transfer triplet excitons. These excitons can be used to power photochemical transformations such as photoisomerization reactions using low energy radiation. Thus, it is desirable to develop a general approach that can efficiently be used to control photoswitches using all-visible-light aiming at future applications in life- and materials sciences. Here, we demonstrate a simple \u27cocktail\u27 strategy that can achieve all-visible-light switchable diarylethenes (DAEs) through triplet energy transfer from the hybrid of CdS NCs and phenanthrene-3-carboxylic acid, with high photoisomerization efficiency and improved fatigue resistance. The size-tunable excitation energies of CdS NCs make it possible to precisely match the clear spectral window of the relevant DAE photoswitch. We demonstrate reversible all-visible-light photoisomerization of a series of DAE derivatives both in the liquid and solid state, even in the presence of oxygen. Our general strategy is promising for fabrication of all-visible-light activated optoelectronic devices as well as memories, and should in principle be adaptable to photopharmacology

Compact medical fluorosensor for minimally invasive tissue characterization

A compact fiber-optic point-measuring fluorosensor fully adapted to clinical studies is described. The system can use two excitation wavelengths, 337 and 405 nm, obtained from a nitrogen laser directly, or after dye laser conversion, respectively. The image intensifier used in the spectrometer can be gated with a variable time delay, allowing also time-resolved spectra to be extracted, with a time resolution of about 4 ns. Moreover, diffusely scattered white light can be spectrally recorded. The system is fully computer controlled enabling short recording times in clinical application, which are illustrated

THz streak camera performance for single-shot characterization of XUV pulses with complex temporal structures

The THz-field-driven streak camera has proven to be a powerful diagnostic-technique that enables the shot-to-shot characterization of the duration and the arrival time jitter of free electron laser (FEL) pulses. Here we investigate the performance of three computational approaches capable to determine the duration of FEL pulses with complex temporal structures from single-shot measurements of up to three simultaneously recorded spectra. We use numerically simulated FEL pulses in order to validate the accuracy of the pulse length retrieval in average as well as in a single-shot mode. We discuss requirements for the THz field strength in order to achieve reliable results and compare our numerical study with the analysis of experimental data that were obtained at the FEL in Hamburg - FLASH. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Antecedents and Covariates of Alcohol Consumption among Swiss Male Conscripts

This study aimed to investigate prevalence and correlates of alcohol consumption frequency in a sample of Swiss conscripts (n=25,611) in order to identify factors that predispose for frequent consumption. A self-report of drinking frequencies, as well as socio-demographic and psychosocial variables, was collected at psychiatric baseline screening. Based on univariate analyses, relevant variables were included in a multivariate multinomial logistic regression model. Six percent were abstainers, 15% reported rarely drinking, 53% occasional drinking, 24% regular drinking and 2% daily drinking. Except for substance use, most associations followed a “J”-shaped curve across the categories of alcohol frequency. Abstinence and frequent drinking can be perceived as deviations from the social norm. Both behaviors are associated with more psychosocial stressors and might be therefore special targets for further studies and new prevention programs

Divergent Paths of Development: The Modern World-System and Democratization in South Africa and Zambia

The 1990s constitute a watershed decade for change in postcolonial Africa as one-party states have crumbled and old authoritarian leaders have stepped down or been removed. The ?rst few years of the 1990s saw about half of the countries in sub-Saharan Africa either install, or prepare for, multiparty rule (Widner 1994:1; van de Walle 1999a:21). Of course, not all change has been positive and it is not clear whether the current democratic wave can be sustained as the latter part of the decade has brought both severe setbacks and continued success (Bratton and van de Walle 1997:3; Diamond 1999:269270; Baker 2000: 9). Considering the precarious nature of African democratization, it is necessary to further investigate its future prospects