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Recent uprisings in the Middle East have increased interest in the roots of moderate as well as severe political and social conflicts. One popular explanation for upticks in violence is the "youth bulge," the presence of disproportionately large youth cohorts. We refine that model using a panel dataset that includes more countries and years than previous literature and implement new measurement techniques to capture the relationship between large youth populations and violence. Contrary to prior literature, we find that the mere presence of a "youth bulge" is not enough to generate violence, but instead the causal roots of violence lie in the pressure youth cohorts exert on the total labor force. We use a new variable, the Youth Risk Factor (the ratio of the youth population to the total labor force), to measure the stress youth cohorts exert on labor markets, and find a significant and large effect on violence. These results have policy implications for countries that currently face large youth cohorts and help explain why conventional policy measures such as increasing educational access are likely not the answer to reducing violence.

Recent uprisings in the Middle East have increased interest in the roots of moderate as well as severe political and social conflicts. One popular explanation for upticks in violence is the 'youth bulge,' the presence of disproportionately large youth cohorts. We refine that model using a panel dataset that includes more countries and years than previous literature and implement new measurement techniques to capture the relationship between large youth populations and violence. Contrary to prior literature, we find that the mere presence of a 'youth bulge' is not enough to generate violence, but instead the causal roots of violence lie in the pressure youth cohorts exert on the total labor force. We use a new variable, the Youth Risk Factor (the ratio of the youth population to the total labor force), to measure the stress youth cohorts exert on labor markets, and find a significant and large effect on violence. These results have policy implications for countries that currently face large youth cohorts and help explain why conventional policy measures such as increasing educational access are likely not the answer to reducing violence. Adapted from the source document.

In vivo imaging is a platform technology with the power to put function in its natural structural context. With the drive to translate stem cell therapies into pre-clinical and clinical trials, early selection of the right imaging techniques is paramount to success. There are many instances in regenerative medicine where the biological, biochemical, and biomechanical mechanisms behind the proposed function of stem cell therapies can be elucidated by appropriate imaging. Imaging techniques can be divided according to whether labels are used and as to whether the imaging can be done in vivo. In vivo human imaging places additional restrictions on the imaging tools that can be used. Microscopies and nanoscopies, especially those requiring fluorescent markers, have made an extraordinary impact on discovery at the molecular and cellular level, but due to their very limited ability to focus in the scattering tissues encountered for in vivo applications they are largely confined to superficial imaging applications in research laboratories. Nanoscopy, which has tremendous benefits in resolution, is limited to the near-field (e.g. near-field scanning optical microscope (NSNOM)) or to very high light intensity (e.g. stimulated emission depletion (STED)) or to slow stochastic events (photo-activated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM)). In all cases, nanoscopy is limited to very superficial applications. Imaging depth may be increased using multiphoton or coherence gating tricks. Scattering dominates the limitation on imaging depth in most tissues and this can be mitigated by the application of optical clearing techniques that can impose mild (e.g. topical application of glycerol) or severe (e.g. CLARITY) changes to the tissue to be imaged. Progression of therapies through to clinical trials requires some thought as to the imaging and sensing modalities that should be used. Smoother progression is facilitated by the use of comparable imaging modalities throughout the discovery and trial phases, giving label-free techniques an advantage wherever they can be used, although this is seldom considered in the early stages. In this paper, we will explore the techniques that have found success in aiding discovery in stem cell therapies and try to predict the likely technologies best suited to translation and future directions. ; This work was supported by the National Biophotonics Imaging Platform (NBIP) Ireland funded under the Higher Education Authority PRTLI Cycle 4, co-funded by the Irish Government and the European Union—Investing in your future. The photoacoustic research was supported by the Science Foundation Ireland (SFI). HZ is supported by a Hardiman Fellowship from NUI Galway. ; peer-reviewed