Financial Crises: Recent Experience in U.S. and International Markets

macroeconomics, financial crisis, crises, U.S. markets, international markets

Planet formation models: the interplay with the planetesimal disc

According to the sequential accretion model, giant planet formation is based first on the formation of a solid core which, when massive enough, can gravitationally bind gas from the nebula to form the envelope. In order to trigger the accretion of gas, the core has to grow up to several Earth masses before the gas component of the protoplanetary disc dissipates. We compute the formation of planets, considering the oligarchic regime for the growth of the solid core. Embryos growing in the disc stir their neighbour planetesimals, exciting their relative velocities, which makes accretion more difficult. We compute the excitation state of planetesimals, as a result of stirring by forming planets, and gas-solid interactions. We find that the formation of giant planets is favoured by the accretion of small planetesimals, as their random velocities are more easily damped by the gas drag of the nebula. Moreover, the capture radius of a protoplanet with a (tiny) envelope is also larger for small planetesimals. However, planets migrate as a result of disc-planet angular momentum exchange, with important consequences for their survival: due to the slow growth of a protoplanet in the oligarchic regime, rapid inward type I migration has important implications on intermediate mass planets that have not started yet their runaway accretion phase of gas. Most of these planets are lost in the central star. Surviving planets have either masses below 10 ME or above several Jupiter masses. To form giant planets before the dissipation of the disc, small planetesimals (~ 0.1 km) have to be the major contributors of the solid accretion process. However, the combination of oligarchic growth and fast inward migration leads to the absence of intermediate mass planets. Other processes must therefore be at work in order to explain the population of extrasolar planets presently known.Comment: Accepted for publication in Astronomy and Astrophysic

Cantilever-based Resonant Microsensors with Integrated Temperature Modulation for Transient Chemical Analysis

This work introduces a resonant cantilever platform with integrated temperature modulation for real-time chemical sensing. Embedded heaters allow for rapid thermal cycling of individual sensors, thereby enabling real-time transient signal analysis without the need for a microfluidic setup to switch between analyte and reference gases. Compared to traditional mass-sensitive microsensors operating in steady state, the on-chip generation of signal transients provides additional information for analyte discrimination

Transient Analysis of Analyte Desorption Due to Thermal Cycling with Varying Pulse Duration

This paper introduces heating pulse duration modulation on a chemically sensitive, polymer-coated resonant cantilever platform for analyte discrimination during the desorption phase. As in our previous work, the embedded heaters enable real-time measurements of analyte sorption into the polymer film, without the need for traditional valve systems and reference gases [1-2]. This work particularly looks at the effects of varying pulse lengths on the sensor responses, while holding the heating power constant. A model differential equation is developed for the sensor response based on both the device sensitivity and transient response. This model can then be used together with estimation theory for analyte identification and quantification, even in mixtures

Group versus individual approach? A meta-analysis of the effectiveness of interventions to promote physical activity

The purpose of the study was to conduct a meta-analysis to empirically compare the relative merits of different contexts typically employed in the physical activity intervention literature for five categories of outcomes: adherence, social interaction, quality of life, physiological effectiveness, and functional effectiveness. \ud Four contexts were examined: home-based programmes not involving contact from researchers or health-care professionals, home-based programmes that involved some contact, standard exercise classes, and exercise classes where group-dynamics principles were used to increase cohesiveness (‘true groups’). Standard literature searches produced 44 relevant studies containing 214 effect sizes. Results revealed a common trend across dependent variables; exercising in a true group was superior to exercising in a standard exercise class, which in turn, did not differ from exercising at home with contact. Furthermore, exercising at home with contact was superior to exercising at home without contact. These results have implications for practitioners in terms of the importance of contact and social support in physical activity interventions

Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam

For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 microsecond pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are investigated for the accelerating structure design: the "Tapered Damped Structure" developed for the CLIC main beam, and the "Slotted Iris - Constant Aperture" structure. Both use 4 SiC loads per cell for effective higher-order mode damping. A full-size prototype of the TDS structure has been built and tested successfully at full power. A first prototype of the SICA structure is being built.Comment: Contribution to Linac 2000 Conference, TUA16 (Poster

Cohesion, team mental models, and collective efficacy: Towards an integrated framework of team dynamics in sport

A nomological network on team dynamics in sports consisting of a multi-framework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMM), collective-efficacy (CE), and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMM, CE and PPP. Results are congruent with the theoretical conceptualization of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMM and CE beliefs. TMM and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams’ season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined