Search

Abstract: Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3–5μm thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ∼105 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the possibility of this amorphous layer on feldspar surface. [Copyright &y& Elsevier]

Presents a method for evaluating the pH of hydrothermal fluids from analyses of halogen concentrations in hydrous minerals. Theoretical relation between mineral chlorine concentrations and fluid pH; Application of the relation to the studies of Salton Sea geothermal system.

Background: The term 'pandemic paranoia' has been coined to refer to heightened levels of mistrust and suspicion towards other people specifically due to the COVID-19 pandemic. In this study, we examine the international prevalence of pandemic paranoia in the general population and its associated sociodemographic profile. Methods: A representative international sample of general population adults (N = 2510) from five sites (USA N = 535, Germany N = 516, UK N = 512, Australia N = 502 and Hong Kong N = 445) were recruited using stratified quota sampling (for age, sex, educational attainment) and completed the Pandemic Paranoia Scale (PPS). Results: The overall prevalence rate of pandemic paranoia was 19%, and was highest in Australia and lowest in Germany. On the subscales of the PPS, prevalence was 11% for persecutory threat, 29% for paranoid conspiracy and 37% for interpersonal mistrust. Site and general paranoia significantly predicted pandemic paranoia. Sociodemographic variables (lower age, higher population size and income, being male, employed and no migrant status) explained additional variance and significantly improved prediction of pandemic paranoia. Conclusions: Pandemic paranoia was relatively common in a representative sample of the general population across five international sites. Sociodemographic variables explained a small but significant amount of the variance in pandemic paranoia. [ABSTRACT FROM AUTHOR]

• Front-of-Package (FOP) nutrition labeling has been introduced in the U.S. over the last decade. • A random coefficients logit model is estimated with data from the U.S. ready-to-eat cereal market. • FOP Participation increases consumer valuation while non-participation lowers it. • Participation and spillover effects are positive and stronger for healthier products. • FOP labeling can play a positive role in improving the healthfulness of consumer food choices. Voluntary nutrition labeling, a means of nutrition quality disclosure, was introduced in the U.S. over the last decade by leading food manufacturers, primarily in the form of front-of-package (FOP) labeling. This article examines how consumer responses to FOP labeling via product participation and information spillovers shift consumer demand across competing products. Applying a random coefficient logit demand model to sales data from the U.S. ready-to-eat cereal market (RTEC) empirically confirms a positive participation effect of FOP and a strong negative spillover effect on non-participating products. Further results indicate that the participation and spillover effects are stronger for healthy RTECs than they are for unhealthy ones. Moreover, ignoring such effects leads to underestimation of consumer valuation of FOP labeling for participating products, higher own-price elasticities of demand and lower price-cost margins. The findings also suggest that an incentive in a firm's voluntary participation in self-regulated labeling programs is to avoid negative treatment externalities and that less health-conscious consumers are not influenced by spillover effects. Overall, this article highlights the importance of including spillover effects in the evaluation of FOP programs and that FOP can play a positive role in improving the healthfulness of consumer choices. [ABSTRACT FROM AUTHOR]

Flight delays in passenger air transportation systems may cause numerous troubles to people's daily life. Empirical works show that at the microscopic level there exist different kinds of inter-correlations, while at the macroscopic level the complex system obeys a simple law similar with that for gases. The constructed theoretical models are not consistent with each other, leading to some debates. How the macroscopic law emerges from the detailed cross-correlations is an open question. And an empirical benchmark to end the debates is also required. In the present work, the cosine correlations between airports for three kinds of flight delays are calculated, the relationships of which versus delay time can be re-scaled by the average number of flights H per month to a universal scaling relation, 〈 C o s θ λ 〉 H p = f λ (〈 T λ 〉 H q) , where p and q are exponents. Hence, the system can work in two kinds of critical phases, namely, the stable phases in the durations from 1995 to 2000 and from 2005 to 2019, and the transition phases in the durations from 2001 to 2004 and within the year 2020. The results provide an empirical benchmark for building models. • American domestic passenger flight records from 1995 to 2020 are downloaded. • Three kinds of cosine correlations and delay time are defined from data. • Scaling relations are obtained by rescaling flight number H per month. • The air transportation systems are confirmed to be in critical states. • Two stable phases and two transition phases are identified. [ABSTRACT FROM AUTHOR]

Flight delays have negative impacts on passengers, carriers, and airports. To reduce these unpopular influence, we need to find the statistical law of the collective behavior of passenger flights. We use a mean-field approach to analyze big data listing the departure and arrival records of all American domestic passenger flights in 20 years. We treat passenger flights as particle gases and define their dimensionless velocity, quasi-thermodynamic quantities — pressure, volume, temperature, and mole number, respectively. By introducing phenomenological parameters a and b to set up van der Waals-like state equations, we erect a universal gaseous constant R for actually operated passenger flights, their counterparts on schedule, and "delayor gases" defined as the difference between them. We find that the attractive coefficient of "delayor gases" positively correlates with the average delay per flight on airports. Rescaling state equations for passenger flights across all 20 years, we find a universal function. This is a significant step toward understanding flight delays and dealing with temporal big data with the tools of statistical physics. • The air transportation is studied with departure/arrival records for 20 years from statistical physics perspective. • The passenger flights are treated as particle gases, and a van der Waals-like state equation is set up. • The universal form of the state equation is found by rescaling those for different years. • A novel virtual particle gas - "delayor gas" is defined to promote the research on flight delays. [ABSTRACT FROM AUTHOR]