Compressible magnetohydrodynamic (MHD) turbulence is a common feature of astrophysical systems such as the solar atmosphere and interstellar medium. Such systems are rife with shock waves that can redistribute and dissipate energy. For an MHD system, three broad categories of shocks exist (slow, fast, and intermediate); however, the occurrence rates of each shock type are not known for turbulent systems. Here, we present a method for detecting and classifying the full range of MHD shocks applied to the Orszag–Tang vortex. Our results show that the system is dominated by fast and slow shocks, with far less-frequent intermediate shocks appearing most readily near magnetic reconnection sites. We present a potential mechanism that could lead to the formation of intermediate shocks in MHD systems, and study the coherency and abundances of shocks in compressible MHD turbulence.

Coral bleaching is associated with large income shocks and a substantial decrease in protein consumption among the affected fishery households in Indonesia [Chaijaroen (2019) Long-lasting income shocks and adaptations: evidence from coral bleaching in Indonesia. Journal of Development Economics136, 119–136]. According to the health and economics literature, early childhood exposures to shocks such as those from coral bleaching can have long-lasting effects on health, schooling, and other later-life outcomes. This paper explores how the mass coral bleaching in 1998 affected household decisions on fertility and child development. Using the Indonesian Family Life Survey (IFLS) and a triple differences approach, results from 2000 suggest an increase in fertility and an increased likelihood of severe childhood stunting among the affected households. For comparison, rainfall shocks are associated with a decrease in fertility and smaller adverse effects on child health and schooling outcomes. This study suggests that the effects of coral bleaching might have been underestimated, and our findings yield more targeted policy recommendations on climate shock mitigation.

The theoretical investigation of shocks and solitary structures in a dense quantum plasma containing electrons at finite temperature, nondegenerate cold electrons, and stationary ions has been carried out. A linear dispersion relation is derived for the corresponding electron acoustic waves. The solitary structures of small nonlinearity have been studied by using the standard reductive perturbation method. We have considered collisions to be absent, and the shocks arise out of viscous force. Furthermore, with the help of a standard reductive perturbation technique, a KdV–Burger equation has been derived and analyzed numerically. Under limiting cases, we have also obtained the KdV solitary profiles and studied the parametric dependence. The results are important in explaining the many phenomena of the laser–plasma interaction of dense plasma showing quantum effects.

We examine a model of network formation in single-layer and multiplex networks in which individuals have positive incentives for social ties, closed triangles, and spillover edges. In particular, we investigate the influence of shocks to the network in which the cost of social ties changes after an initial equilibrium. We highlight the emergence of structural entrenchment: the retention of structural features, such as closed triangles and spillover edges, which are formed under historically different conditions from those currently driving network evolution. This work has broad implications for understanding path dependence in the structure and dynamics of single-layer and multiplex networks.

Far-infrared spectroscopy reveals gas cooling and its underlying heating due to physical processes taking place in the surroundings of protostars. These processes are reflected in both the chemistry and excitation of abundant molecular species. Here, we present the Herschel-PACS far-IR spectroscopy of 90 embedded low-mass protostars from the WISH (van Dishoeck et al. 2011), DIGIT (Green et al. 2013), and WILL surveys (Mottram et al. 2017). The 5 × 5 spectra covering the ∼50″ × 50″ field-of-view include rotational transitions of CO, H2O, and OH lines, as well as fine-structure [O I] and [C II] in the ∼50-200 μm range. The CO rotational temperatures are typically ∼300 K, with some sources showing additional components with temperatures as high as ∼1000 K. The H2O / CO and H2O / OH flux ratios are low compared to stationary shock models, suggesting that UV photons may dissociate some H2O and decrease its abundance. Comparison to C shock models illuminated by UV photons show a good agreement between the line emission and the models for pre-shock densities of 105 cm−3 and UV fields 0.1-10 times the interstellar value. The far-infrared molecular and atomic lines are the unique diagnostic of shocks and UV fields in deeply-embedded sources.

A Barro-type economic growth model is estimated for the 50 states in the U.S. using data for three decades beginning in 1960. Frontier estimation techniques are used to test for the presence of state-specific shocks to economic growth that are independent of the usual, normally-distributed random errors. We find that large, positive shocks to growth occurred during the period 1960-90. Our results indicate that the error term structure assumed under OLS may not be appropriate for modeling economic growth.

This paper uses spectral theory to develop the following two testable hypotheses in a unified framework for the predictions of business-cycle and endogenous growth models: (i) financial development affects only business-cycle volatility; and (ii) shocks affect both business-cycle volatility and long-run volatility of GDP growth. In other words, volatility caused by shocks is more persistent than that caused by financial underdevelopment. We decompose the business-cycle and long-run volatility by the spectral method and then test the hypotheses at the cross-country level. Empirical evidence provides support for both hypotheses. Higher private credit, a bank-based measure of financial development, dampens business-cycle volatility but not long-run volatility. Volatility of shocks, as measured by the volatility of changes in the terms of trade, magnifies both business-cycle and long-run volatility. The results are robust to accounting for endogeneity, a market-based measure of financial development, and an alternative method of volatility decomposition.

We review the theory of shock drift acceleration, developing the theory in detail for gyrophaseaveraged particles. It is shown howboth the upstream and downstream velocity spaces separate into different regions according to the interaction of the particles with the shock (reflection, transmission, head-on, overtaking). The effects of the cross-shock electric field and of the magnetic overshoot are discussed. The effectiveness of acceleration is estimated for Maxwellian and power law distributions. The condition for a beam instability to be generated by reflected particles is determined and found to be independent of the distribution function for isotropic inflowing electrons.

This paper tests the three leading specifications of asymmetric and possibly nonlinear feedback from the real price of oil to U.S. industrial production and its sectoral components. We show that the evidence for such feedback is sensitive to the estimation period. Support for a nonlinear model is strongest for samples starting before 1973. Instead, using post-1973 data only, the evidence against symmetry becomes considerably weaker. For example, at the aggregate level, there is no evidence against the hypothesis of symmetric responses to oil price innovations of typical magnitude, consistent with results of Kilian and Vigfusson [Quantitative Economics, 2(3), 419–453 (2011)] for U.S. real GDP. There is strong evidence of asymmetries at the disaggregate level, however, especially for industries that are energy-intensive in production (such as chemicals) or that produce goods that are energy-intensive in use (such as transportation equipment). Our analysis suggests that these asymmetries may be obscured in the aggregate data and highlights the importance of developing multisector models of the transmission of oil price shocks.

We report on the investigation of strong radiative shocks generated with the high energy, sub-nanosecond iodine laser at PALS. These shock waves are characterized by a developed radiative precursor and their dynamics is analyzed over long time scales (~50 ns), approaching a quasi-stationary limit. We present the first preliminary results on the rear side XUV spectroscopy. These studies are relevant to the understanding of the spectroscopic signatures of accretion shocks in Classical T Tauri Stars.

Les prothèses de hanche en biocéramique sont résistantes à l'usure mais, du fait de leur fragilité intrinsèque, sont susceptibles de se rompre. Le phénomène de décoaptation, séparation de faible amplitude de la tête et de la cupule, a été mis en évidence lors de la marche, et le choc mécanique en résultant peut fortement augmenter les risques de rupture. Un modèle par éléments-finis a été développé et les résultats ont été exploités afin de simuler l'évolution de la probabilité de rupture de cupules en zircone au cours du temps. Les résultats s'accordent bien avec l'expérience, même si des améliorations sont nécessaires afin de prendre en compte l'érosion des surfaces de contact.