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Mamyshev oscillators (MOs) demonstrate extraordinarily superior performance compared with fiber laser counterparts. However, the realization of a fully fiberized, monolithic laser system without pulse degradation remains a key challenge. Here we present a high-energy MO using large mode area Yb-doped fiber and fiber-integrable interferometric super-Gaussian spectral filters that directly generates a nearly diffraction-limited beam with approximately 9.84 W average power and 533 nJ pulse energy. By implementing pre-chirp management with anti-resonant hollow-core fiber (AR-HCF), the adverse effects of super-Gaussian filtering on pulse quality are effectively mitigated, enabling pulse compression to 1.23 times the transform limit. Furthermore, AR-HCF is employed to provide negative dispersion to compensate for the positive chirp of output pulses, resulting in approximately 37 fs de-chirped pulses with approximately 10 MW peak power. This approach represents a significant step toward the development of monolithic fiber lasers capable of generating and flexible delivery of sub-50-fs pulses with tens of megawatts peak power.
Caused by multiple risk factors, heavy burden of major depressive disorder (MDD) poses serious challenges to public health worldwide over the past 30 years. Yet the burden and attributable risk factors of MDD were not systematically known. We aimed to reveal the long-term spatio-temporal trends in the burden and attributable risk factors of MDD at global, regional and national levels during 1990–2019.
Methods
We obtained MDD and attributable risk factors data from Global Burden of Disease Study 2019. We used joinpoint regression model to assess the temporal trend in MDD burden, and age–period–cohort model to measure the effects of age, period and birth cohort on MDD incidence rate. We utilized population attributable fractions (PAFs) to estimate the specific proportions of MDD burden attributed to given risk factors.
Results
During 1990–2019, the global number of MDD incident cases, prevalent cases and disability-adjusted life years (DALYs) increased by 59.10%, 59.57% and 58.57%, respectively. Whereas the global age-standardized incidence rate (ASIR), age-standardized prevalence rate (ASPR) and age-standardized DALYs rate (ASDR) of MDD decreased during 1990–2019. The ASIR, ASPR and ASDR in women were 1.62, 1.62 and 1.60 times as that in men in 2019, respectively. The highest age-specific incidence, prevalence and DALYs rate occurred at the age of 60–64 in women, and at the age of 75–84 in men, but the maximum increasing trends in these age-specific rates occurred at the age of 5–9. Population living during 2000–2004 had higher risk of MDD. MDD burden varied by socio-demographic index (SDI), regions and nations. In 2019, low-SDI region, Central sub-Saharan Africa and Uganda had the highest ASIR, ASPR and ASDR. The global PAFs of intimate partner violence (IPV), childhood sexual abuse (CSA) and bullying victimization (BV) were 8.43%, 5.46% and 4.86% in 2019, respectively.
Conclusions
Over the past 30 years, the global ASIR, ASPR and ASDR of MDD had decreased trends, while the burden of MDD was still serious, and multiple disparities in MDD burden remarkably existed. Women, elderly and populations living during 2000–2004 and in low-SDI regions, had more severe burden of MDD. Children were more susceptible to MDD. Up to 18.75% of global MDD burden would be eliminated through early preventing against IPV, CSA and BV. Tailored strategies-and-measures in different regions and demographic groups based on findings in this studywould be urgently needed to eliminate the impacts of modifiable risk factors on MDD, and then mitigate the burden of MDD.
As a common mineral phase on Earth and Martian regolith, natural rutile was reported as a potential candidate for use as a Fenton catalyst in this study. The influences of Fe and V in various chemical states on the generation of reactive oxygen species (ROSs) and the catalytic activity of rutile were examined. A series of rutile samples with various surface and bulk states of Fe and V were obtained initially by hydrogen annealing of natural rutile at ~773–1173 K. X-ray diffraction, electron paramagnetic resonance spectra, and X-ray photoelectron spectroscopy demonstrated that the atomic fractions of Fe(III) and V(V) decreased sharply with increasing temperature, along with the accumulation of surface Fe(II) and bulk V(III). All as-prepared materials showed enhanced Fenton degradation efficiency on methylene blue (MB) compared with P25-TiO2, and the treated samples exhibited up to 3.5-fold improvement in efficiency at pH 3 compared to the untreated sample. The improved efficiency was attributed mainly to Fenton catalysis involving Fe(II) and V(III). The dissolved Fe2+ played a crucial role in the homogeneous Fenton reaction, while the bound V(III) favored adsorption primarily and may have facilitated heterogeneous Fenton reaction and the regeneration of Fe2+. The pH regulated the reaction mechanism among homogeneous (pH = 3) and heterogeneous (pH = 3.7) Fenton catalysis and physical adsorption (pH = 5, 6). The aim of the present study was to improve the understanding of the potential role of natural rutile with advanced oxidation functions in Earth systems and even on Mars, which also provide an inspiration for screening natural rutile and any other similar, Earth-abundant, low-cost minerals for environmental application.
Chapter 5 puts the reconfiguration of Pacific Asia into global perspective in four respects. First, in contrast to the divergences that characterized the modern era, in this century there has been a multi-dimensional convergence between developed and developing countries. 2008 marked the first time since the nineteenth century that the production of the developing world was greater than that of the developed world. Second, the unipolar world order of the post-Cold War has shifted to a multinodal world order. Without a defining global power, the multinodal order has a “certainty vacuum” rather than a power vacuum, and it is best filled by partnerships rather than by alliances. Third, Pacific Asia has become a global powerhouse. In 2020 its GDP equaled that of the US and the EU combined, and it is integrated by global value chains. Fourth, China reaches beyond its region. Despite the headwinds of Covid-19, trade bottlenecks, and global tensions, China and Pacific Asia have arrived. If a bipolar configuration develops, it is likely to differ from the Cold War camps by being closer to a developed/developing country split, with less unity of leadership on either side.
Given China’s position in Pacific Asia, defining its regional centrality might seem a simple task. But centralities grander than merely geographical have been alleged and contested. Currently some maintain that China is the central kingdom because of its power. But it was conquered by the Mongols and the Manchus, and its present centrality is due more to its economic mass and connectivity than to its military. Others claim that hierarchy is natural to Asian culture, and China is the apex. But neighbors were often cynical about China’s moral stature, and China’s soft power is now at a low ebb. I argue that China was the center of regional attention in the premodern era, and that it has returned to center stage since 2008. The three basic reasons for China’s original centrality and its return were situational: presence, population, and production. The salience of all three disappeared with Western imperialism’s global presence, the devaluation of mere demography, and industrial production. Traditional and current centrality created asymmetric relationships between China and its neighbors, but the regional situations differ fundamentally.
Pacific Asia, comprised of Northeast Asia, Greater China, and Southeast Asia, has surpassed the combined production of the United States and Europe, and its intraregional economic cohesiveness exceeds that of either the EU or North America. Pacific Asia has emerged gradually and without major conflict, but it should be taken seriously as a region. China is primarily a regional power, but in a prosperous region deeply interconnected to the rest of the world. The United States tends to view China as a lone global competitor, but its global presence and strength rest on its centrality to Pacific Asia. Understanding China in its region is the first task of this book, followed by the challenge of rethinking the global order in terms of a multinodal matrix rather than a bipolar competition of great powers. This requires background on the evolution of the Pacific Asian configuration, including China’s premodern centrality as well as the splintering of the region by European colonialism. Rethinking is aided by commentaries from four of Asia’s leading thinkers about international relationships.
Wu Yu-Shan, a distinguished Taiwanese political scientist, points out that Western success was based on power, undergirded by technology and organization. In response, Pacific Asia attempted to achieve modernization by four routes. Western liberalism was stillborn in China, as was Meiji-style conservative modernization. Mao’s approach could best be called “confused modernization,” a mix of state socialism and disastrous experiments like the Great Leap Forward and Cultural Revolution. What worked in Korea and Taiwan was authoritarian politics and state capitalism, and with Deng Xiaoping this became China’s path as well.
Qin Yaqing, China’s foremost theorist of international relations, concentrates on the complexities of the new multinodal world order. He argues against centrality, pointing out that international relationships are now complex and flat rather than binary and hierarchical. The nodes of the international multinodal complex are internally as well as externally complex. Moreover, the successful regional initiatives of ASEAN demonstrate the capacity of smaller nodes to play leading roles in configuring order.
Prior to the Opium War China was central to Pacific Asia, but it was not in control of its neighborhood. The mobility of the various nomadic groups threatened China’s northern and western frontiers, and Vietnam’s successful resistance to Ming annexation set a southern boundary-stone. While China’s centrality was not hegemonic, its location, demographic preponderance, and artisanal production made China the center of regional attention. Conversely, because of China’s demographic and production centrality, China was more interested in defending what it had than in imperial adventures abroad. Its foreign policy was one of controlling exposure in relationships—thin connectivity. By the Ming Dynasty this evolved into the tribute system, whose core was a ritualized exchange of deference by the neighbor for acknowledgement of autonomy by China.
Evelyn Goh is well known for her emphasis on order transition rather than power transition in world politics, and in her commentary she stresses the compatibility of a multinodal framing that recognizes the continuing significance of power in a post-hegemonic context. While China’s reemergence is a key event for Pacific Asia, she cautions that regional centrality does not preclude global relevance, either for China or for the Pacific Asian region. China is not just regional, and neither is Pacific Asia. But becoming global implies new challenges of global governance and global responsibility. The overall tendency is toward “a multinodal Asia in a multinodal international system.”
While Pacific Asia had China as a “solid center,” a place in the middle where most of the people and production was, the West had a “liquid center,” the Mediterranean. Wealth could be pursued and neighbors conquered in different places in the West, leading to competitive, distinct empires rather than to dynastic cycles.