In this article, we study the role that media plays during a speculative bubble on an emerging market, and in particular the London financial press’s relation to the West African mining bubble of the early twentieth century. The focus is on the leading company in this sector at the time, Ashanti Goldfields Corporation. The London financial press lacked access to independent, reliable information on the ground, so it often failed to provide readers with relevant factual information. In some instances, the press might have even fueled the speculative cycles through the reporting it provided.

Superbubbles are acyclic induced subgraphs of a digraph with single entrance and exit that naturally arise in the context of genome assembly and the analysis of genome alignments in computational biology. These structures can be computed in linear time and are confined to non-symmetric digraphs. We demonstrate empirically that graph parameters derived from superbubbles provide a convenient means of distinguishing different classes of real-world graphical models, while being largely unrelated to simple, commonly used parameters.

We numerically model the dynamics of the Enceladus plume ice grains and define our nominal plume model as having a particle size distribution n(R) ~ R−q with q = 4 and a total particulate mass rate of 16 kg s−1. This mass rate is based on average plume brightness observed by Cassini across a range of orbital positions. The model predicts sample volumes of ~1600 µg for a 1 m2 collector on a spacecraft making flybys at 20–60 km altitudes above the Enceladus surface. We develop two scenarios to predict the concentration of amino acids in the plume based on these assumed sample volumes. We specifically consider Glycine, Serine, α-Alanine, α-Aminoisobutyric acid and Isovaline. The first ‘abiotic’ model assumes that Enceladus has the composition of a comet and finds abundances between 2 × 10−6 to 0.003 µg for dissolved free amino acids and 2 × 10−5 to 0.3 µg for particulate amino acids. The second ‘biotic’ model assumes that the water of Enceladus's ocean has the same amino acid composition as the deep ocean water on Earth. We compute the expected captured mass of amino acids such as Glycine, Serine, and α-Alanine in the ‘biotic’ model to be between 1 × 10−5 to 2 × 10−5 µg for dissolved free amino acids and dissolved combined amino acids and about 0.0002 µg for particulate amino acids. Both models consider enhancements due to bubble bursting. Expected captured mass of amino acids is calculated for a 1 m2 collector on a spacecraft making flybys with a closest approach of 20 km during mean plume activity for the given nominal particle size distribution.

The warm ionised medium (WIM), also referred to as diffuse ionised gas (DIG), contains most of the mass of interstellar medium in ionised form, contributing as much as 30% of the total atomic gas mass in the solar neighborhood. The advent of CCDs has enabled unprecedented study of this medium in external galaxies, probing a variety of environments. In particular, we can derive the morphology of the WIM, its distribution across disks, and the correlation with other Population I material. Spectroscopy of the WIM makes it possible to test various ionisation models. I will review here our current understanding of the properties of the WIM in spiral galaxies. A perhaps unexpected result is that the Hα emission from the WIM contributes about 40% of the total observed Hα luminosity from spirals. This places severe constraints on possible sources of ionisation, since only photoionisation by OB stars meets this requirement. Spectroscopic measurements of forbidden line strengths appear in reasonable agreement with photoionisation models. It is not yet clear if the Lyman continuum photons that ionise the WIM are mostly from OB stars located inside traditional HII regions, or from field OB stars.

N131 is an infrared dust bubble residing in a molecular filament. We aim to study the formation and fragmentation of this bubble with multi-wavelength dust and gas observations. Towards the bubble N131, we analyzed archival multi-wavelength observations including 3.6, 4.5, 5.8, 8.0, 24, 70, 160, 250, 350, 500 μm, 1.1 mm, and 21 cm. In addition, we performed new observations of CO (2-1), CO (1-0), and 13CO (1-0) with the IRAM 30-m telescope. Multi-wavelength dust and gas observations reveal a ringlike shell with compact fragments, two filamentary structures, and a secondary bubble N131-A. The bubble N131 is a rare object with a large hole at 24 μm and 21 cm in the direction of its center. The dust and gas clumps are compact and might have been compressed at the inner edge of the ringlike shell, while they are extended and might be pre-existing at the outer edge. The column density, excitation temperature, and velocity show a potentially hierarchical distribution from the inner to outer edge of the ringlike shell. We also detected the front and back sides of the secondary bubble N131-A in the direction of its center. The derived Lyman-continuum ionizing photon flux within N131-A is equivalent to an O9.5 star. Based on the above, we suggest that the bubble N131 might be triggered by the strong stellar winds from a group of massive stars inside the bubble. We propose a scenario in which the bubble N131 forms from the disruption of a gas filament by expansion of H II region, strong stellar winds, and fragments under self-gravity.

This study provides an infinite-horizon model of rational bubbles in a production economy. A bubble can arise when the pursuit of status is modeled explicitly, capturing the notion of “the spirit of capitalism.” Using a parameterized model, I demonstrate the specific conditions for the existence of bubbles and their implications. Bubbles crowd out investment, stimulate consumption, and slow economic growth. I also discuss a stochastic bubble that bursts with an exogenous probability. I show that there could be multiple stochastic bubbly equilibria. Moreover, I suggest that taxing wealth properly can eliminate bubbles and achieve the social optimum.

This article argues that the promotion boom which occurred in the railway industry during the mid 1840s was amplified by the issue of derivative-like assets, which let investors take highly leveraged positions in the shares of new railway companies. The partially paid shares which the new railway companies issued allowed investors to obtain exposure to an asset by paying only a small initial deposit. The consequence of this arrangement was that investor returns were substantially amplified, and many schemes could be financed simultaneously. However, when investors were required to make further payments it put a negative downward pressure on prices.

Nous étudions expérimentalement et numériquement la dynamique de bulles d’air isoléestraversant l’interface initialement plane entre deux liquides newtoniens. Les liquidesutilisés dans les expériences nous permettent d’obtenir des rapports de viscosité quipeuvent varier de deux ordres de grandeur entre les deux couches et dans une moindremesure, de faire varier le contraste de densité et la tension interfaciale rencontrés parla bulle lors de la traversée de l’interface. Deux dispositifs d’injection différents sontutilisés afin d’obtenir des bulles dont les diamètres s’échelonnent typiquement entre 1 mmet 2 cm et dont les plus grosses adoptent une forme torique. Nous réalisons en parallèledes simulations numériques axisymétriques à l’aide de deux approches distinctes baséespour l’une sur un modèle de capture d’interface (de type VOF mais sans reconstructiond’interface), pour l’autre sur un modèle de Cahn-Hilliard couplé aux équations deNavier-Stokes.

Irradiation of an amorphous layer of dried sodium phosphate buffer (pH = 7.0) by transmission electron microscopy (100–120 kV) causes rapid formation of numerous small spherical bubbles [10–100 Å (= 1–10 nm)] containing an unknown gas. Bubbling is detected even with the first low-dose exposure. In a thin layer (ca. 100–150 Å), bubbling typically goes through nucleation, growth, possible fusion, and end-state, after which further changes are not apparent; co-irradiated adjacent areas having a slightly smaller thickness never develop bubbles. In moderately thicker regions (ca. over 200 Å), there is no end-state. Instead, a complex sequence of microstructural changes is elicited during continued intermittent high-dose irradiation: nucleation, growth, early simple fusions, a second round of extensive multiple fusions, general reduction of matrix thickness (producing flattening and expansion of larger bubbles, occasional bubble fission, and formation of very large irregularly-shaped bubbles by a third round of compound fusion events), and slow shrinkage of all bubbles. The ongoing lighter appearance of bubble lumens, maintenance of their rounded shape, and extensive changes in size and form indicate that gas content continues throughout their surprisingly long lifetime; the thin dense boundary layer surrounding all bubbles is proposed to be the main mechanism for their long lifetime.

This paper investigates the possible formation of informational cascades by traders in a random sample of 8,000 NYSE stock-days experiencing extreme price changes during 1998–2001. Our cascade measure is designed to detect informational cascades in high-frequency stock market prices. First, we find evidence of cascades on approximately 12% of the days when the NYSE experiences, on average, large price increases. This percentage increases to about 20% on days experiencing large price decreases, on average. Second, we find evidence that the interarrival times of trades in those stocks exhibiting significant informational cascades are generated by a nonlinear stochastic process. Third, the evidence supporting cascades is largely confined to smaller stocks and to stocks followed by fewer security analysts. Last, the occurrence of cascades appears to correlate with the incorporation of fundamental information into security prices.