Does perceived social mobility shape attitudes toward government and family educational investment?

Education is considered a key driver of intergenerational social mobility in the United States. However, the past several decades have witnessed a dramatic increase in the costs of college attendance, which puts political pressure on what the roles of government and families in education financing ought to be. In this study, we examine how individuals' perception of society's intergenerational mobility affects their willingness to financially support children in college, as well as their opinion on whether the government should take a smaller or bigger role. Perceptions of mobility matter because they reflect individuals' estimated opportunity structure and thereby an important component of returns to education. Using data from a nationally representative online survey and a novel design to measure perceived mobility, we show that (1) individuals who believe to live in a more mobile society exhibit more aversion toward government spending and a preference for students relying on family support; (2) these associations are stronger among higher-SES groups; and (3) information treatments randomly assigning objective social mobility facts make individuals who overestimate the level of social mobility even more eager to contribute to tuition costs. These findings suggest that learning about factual levels of mobility reinforces existing beliefs and possibly their consequences for educational investment

Social mobility in the Tang Dynasty as the Imperial Examination rose and aristocratic family pedigree declined, 618-907 CE.

Data from the distant past are fertile ground for testing social science theories of education and social mobility. In this study, we construct a dataset from 3,640 tomb epitaphs of males in Chinas Tang Dynasty (618-907 CE), which contain granular and extensive information about the ancestral origins, family background, and career histories of the deceased elites. Our statistical analysis of the complete profiles yields evidence of the transition away from an aristocratic society in three key trends: 1) family pedigree (i.e., aristocracy) mattered less for career achievement over time, 2) passing the Imperial Examination (Keju) became an increasingly important predictor of ones career achievement, and 3) fathers position always mattered throughout the Tang, especially for men who did not pass the Keju. The twilight of medieval Chinese aristocracy, according to the data, began in as early as the mid-seventh century CE

How different freezing morphologies of impacting droplets form

Freezing morphologies of impacting water droplets depend on the interaction between droplet spreading and solidification. The existing studies showed that the shape of frozen droplets mostly is of spherical cap with a singular tip, because of much shorter timescale of the droplet spreading than that of the solidification. Here, we create the experimental conditions of extended droplet spreading and greatly enhanced heat transfer for fast solidification, thereby allowing to study such droplet freezing process under the strong coupling of the droplet spreading and solidification.Ministry of Education (MOE)This work was supported by the Ministry of Education of Singapore via Tier 2 Academic Research Fund (MOE2016- T2-1-114)

Self-peeling of frozen water droplets upon impacting a cold surface

Freezing of water droplets impacting a cold substrate is a commonly encountered circumstance impairing the performance and safety of various applications. Active methods of ice removal such as heating or mechanical means are energy intensive and inconvenient. Here, we report a passive ice removal method via harvesting the thermal-mechanical stress of ice, leading to the self-peeling of frozen water droplets upon impacting a cold substrate. We find that the frozen ice completely self-peels and is then easily removable from a cold hydrophobic surface whiles the ice exhibits cracking and remains firmly sticky to a hydrophilic surface. The peeling behaviors of frozen water droplets are then scrutinized by varying the subcooling degree, impact parameters and wettability. Moreover, we develop a theoretical model to characterize the peeling and bending behaviors of the ice and also provides a simple criterion to predict the occurrence of complete self-peeling, facilitating the design of anti-icing surfaces.Ministry of Education (MOE)Published versionThis work was supported by National Postdoctoral Program for Innovative Talents (No. BX2021235) and the Ministry of Education of Singapore via Tier 2 Academic Research Fund (MOE2016-T2-1-114)(awarded to C.Y.). W.Z.F. thanks the fund supported by Key Laboratory of Icing and Anti/De-icing of CARDC (Grant No. IADL20210105). L.Z. thanks the start-up grant (Grant No. R-265-000-696-133) given by the National University of Singapore

Freezing morphologies of impact water droplets on an inclined subcooled surface

Freezing of impact water droplets is ubiquitous in nature. Prior studies mostly focus on the freezing shapes of droplets impinging perpendicularly to a cold surface. In this work, we investigate how the frozen morphologies of impact water droplets are formed on a subcooled inclined (45 °) surface. To enhance the coupling between droplet impact dynamics and solidification, we hereby conduct the experiments on superhydrophilic surfaces under various substrate temperatures (-45 °C ≤ Ts ≤ -25 °C) and droplet impact velocities (1.33 m/s ≤ V0 ≤ 3.96 m/s) where the cooling rate is significantly improved. Intriguingly, we discover four types of frozen droplet morphologies, namely elliptical cap, half ring + cap Ⅰ, half ring + cap Ⅱ, and half ring + single ring, depending upon the impact velocity and substrate temperature. The formation of such morphologies resulted from the competition between the timescales associated with droplet solidification and impact hydrodynamics are appreciably altered by the inclined impact due to symmetry breaking as compared to the normal impact. To unravel the underlying physics, based on scaling analyses we propose a phase diagram to show how frozen morphologies are controlled by droplet impact and freezing related timescales, and find that such phase diagram can corroborate with the experimental findings.Ministry of Education (MOE)Nanyang Technological UniversityWe gratefully acknowledge the financial support from the Ministry of Education of Singapore via Tier 2 Academic Research Fund (No. MOE2016-T2-1-114), the Nanyang Technological University Ph.D. Scholarship to F.Q.Z, and the Experiments for Space Exploration Program and the Qian Xuesen Laboratory, China Academy of Space Technology (Grant No. 202001001)

Water condensate morphologies on a cantilevered microfiber

Water collection via fiber-based coalescers shows promise in mitigating increasing water scarcity, and most studies usually focus on the water collection by accumulating water through successive coalescences of fog in the absence of condensation. Here, we report on non-uniform condensate morphologies observed during air–vapor mixture condensation on a cantilevered microfiber. Due to the competition between thermal conduction resistance within the fiber and condensation heat transfer resistance on the fiber surface, the vapor diffusive flux along the fiber varies accordingly, engendering three representative condensate morphologies. We systematically examine the effects of fiber length, diameter, and material (constantan, 316L steel, and alumel) on these condensate morphologies. Scaling analyses are also provided to reveal the underlying physics. Our experimental investigations and theoretical analyses reported in this work shed more light on air–vapor mixture condensation mechanisms that could pave the way to future condensation-associated applications.Ministry of Education (MOE)Published versionWe thank the financial support from the Ministry of Education of Singapore via Tier 2 Academic Research Fund (No. MOE2016-T2-1-114) and the Nanyang Technological University Ph.D. Scholarship to F.Z., H.Z., and Z.Z

Frontier and Hot Topics of Pulsed Fiber Lasers via CiteSpace Scientometric Analysis: Passively Mode-Locked Fiber Lasers with Real Saturable Absorbers Based on Two-Dimensional Materials

Pulsed fiber lasers, with high peak power and narrow pulse widths, have been proven to be an important tool for a variety of fields of application. In this work, frontier and hot topics in pulsed fiber lasers were analyzed with 11,064 articles. Benefitting from the scientometric analysis capabilities of CiteSpace, the analysis found that passively mode-locked fiber lasers with saturable absorbers (SAs) based on two-dimensional (2D) materials have become a hot research topic in the field of pulsed fiber lasers due to the advantages of self-starting operation, high stability, and good compatibility. The excellent nonlinear optical properties exhibited by 2D materials at nanometer-scale thicknesses have become a particularly popular research topic; the research has paved the way for exploring its wider applications. We summarize the performance of several typical 2D materials in ultrafast fiber lasers, such as graphene, topological insulators (TIs), transition metal dichalcogenides (TMDs), and black phosphorus (BP). Meanwhile, we review and analyze the direction of the development of 2D SAs for ultrafast fiber lasers