Cont-Bouchaud percolation model including Tobin tax

The Tobin tax is an often discussed method to tame speculation and get a source of income. The discussion is especially heated when the financial markets are in crisis. In this article we refer to foreign exchange markets. The Tobin tax should be a small international tax affecting all currency transactions and thus consequently reducing the destabilizing speculations. In this way this tax should take over a control function. By including Tobin tax in the microscopic model of Cont and Bouchaud one finds that Tobin tax could be the right method to control foreign exchange operations and get a good source of incomeComment: Expanded for of paper to be published in Int. J. Mod. Phys. C 13 (2002

Anti-TNF-alpha therapy induces a distinct regulatory T cell population in patients with rheumatoid arthritis via TGF-beta

The induction of regulatory T (T reg) cells holds considerable potential as a treatment for autoimmune diseases. We have previously shown that CD4(+)CD25(hi) T reg cells isolated from patients with active rheumatoid arthritis (RA) have a defect in their ability to suppress proinflammatory cytokine production by CD4(+)CD25(-) T cells. This defect, however, was overcome after anti-tumor necrosis factor (TNF)-alpha antibody (infliximab) therapy. Here, we demonstrate that infliximab therapy gives rise to a CD4(+)CD25(hi)FoxP3(+) T reg cell population, which mediates suppression via transforming growth factor (TGF)-beta and interleukin 10, and lacks CD62L expression, thereby distinguishing this T reg cell subset from natural T reg cells present in healthy individuals and patients with active RA. In vitro, infliximab induced the differentiation of CD62L(-) T reg cells from CD4(+)CD25(-) T cells isolated from active RA patients, a process dependent on TGF-alpha. In spite of the potent suppressor capacity displayed by this CD62L(-) T reg cell population, the natural CD62L(+) T reg cells remained defective in infliximab-treated patients. These results suggest that anti-TNF-alpha therapy in RA patients generates a newly differentiated population of T reg cells, which compensates for the defective natural T reg cells. Therefore, manipulation of a proinflammatory environment could represent a therapeutic strategy for the induction of T reg cells and the restoration of tolerance

The Development of In-Group Favoritism: Between Social Reality and Group Identity

This study examined how social reality restricts children’s tendency for in-group favoritism in group evaluations. Children were faced with social reality considerations and with group identity concerns. Using short stories, in this experimental study, conducted among 3 age groups (6-, 8-, and 10-year-olds), the authors examined the trait attribution effects of reality constraints on eye-color differences and national group differences. The results show that the trait attributions of all age groups were restricted by the acceptance of socially defined reality. In addition, when the information about reality was not considered accurate, only the youngest children showed positive in-group favoritism. It is argued that these findings are useful in trying to reconcile some of the divergent and contrasting findings in the developmental literature on children’s intergroup perceptions and evaluations.

Takens-Bogdanov bifurcation of travelling wave solutions in pipe flow

The appearance of travelling-wave-type solutions in pipe Poiseuille flow that are disconnected from the basic parabolic profile is numerically studied in detail. We focus on solutions in the 2-fold azimuthally-periodic subspace because of their special stability properties, but relate our findings to other solutions as well. Using time-stepping, an adapted Krylov-Newton method and Arnoldi iteration for the computation and stability analysis of relative equilibria, and a robust pseudo-arclength continuation scheme we unfold a double-zero (Takens-Bogdanov) bifurcating scenario as a function of Reynolds number (Re) and wavenumber (k). This scenario is extended, by the inclusion of higher order terms in the normal form, to account for the appearance of supercritical modulated waves emanating from the upper branch of solutions at a degenerate Hopf bifurcation. These waves are expected to disappear in saddle-loop bifurcations upon collision with lower-branch solutions, thereby leaving stable upper-branch solutions whose subsequent secondary bifurcations could contribute to the formation of the phase space structures that are required for turbulent dynamics at higher Re.Comment: 26 pages, 15 figures (pdf and png). Submitted to J. Fluid Mec

Carbon sink geopolitics

This paper explores an example of global politics in action by attending to the modalities and outcomes of United Nations negotiations on global warming. More precisely, the paper ethnographically traces how the capacity of tropical forests to act as carbon sinks is turned into a matter of global concern. The focus is on a negotiated policy called Reducing Emissions from Deforestation and forest Degradation (REDD+) and its anchoring in the Democratic Republic of the Congo, whose territory contains the second largest area of rainforest after Brazil. The paper discusses the importance of the promissory in climate actions, the multivalence of what is at stake and the porosity and resilience of national demarcation. To do so, it identifies three moments and sites of geopolitical re-composition: the formulation of international consensus, the work of preparatory agents and the quest for metrological inclusiveness. These moments and sites point to the theatricality and semi-secrecy of United Nations negotiations, the mobilizing activities of expatriate consultants hired with overseas aid funding and the unstable evidential grounds on which emission reduction efforts are based. The paper suggests that, through this series of processes, the carbon stored by tropical forests becomes a matter of global exigency

Nonlinear disturbance evolution in a two-dimensional boundary layer along an elastic plate and induced radiated sound

The interaction between a boundary-layer flow and an elastic plate is addressed by direct numerical simulation, taking into account the full coupling between the fluid flow and the flexible wall. The convectively unstable flow state is harmonically forced and two-dimensional nonlinearly saturated wavelike disturbances are computed along archetype-plates with respect to stiffness and natural frequencies. In the aim of determining the low-Mach-number radiated sound for the system, the simulation data are used to solve the Lighthill’s equation in terms of a Green’s function in the wavenumber-frequency space. Different degrees of fluid-structure coupling are implemented in the radiated sound model and the resulting acoustic pressure levels are compared. The sound radiation levels are shown to be increased in the presence of flexible walls with however significant differences in the radiated pressure levels for different coupling assumptionsThe authors gratefully acknowledge Thales Underwater Systems and DCNS for their financial support to this work

The friction of the mundane: on the problematic marketization of the carbon stored by trees in the tropics

Carbon dioxide released from the burning of fossil fuels is a major concern of our times. There is now a political agreement that these emissions must decrease. So far one way forward has been to design and maintain carbon markets. As part of this process, trees in the tropics have been enrolled in peculiar transactions: actions such as reforesting a land of degraded savannah or preserving a piece of forest can produce tradable emission credits to offset against CO2 emissions in distant locations. Based on a multi-sited investigation of carbon offsetting, including fieldwork in the Congo, the paper presents a journey across different marketization sites where the enrolment of forest carbon into market exchanges can be seen to be at stake. Several operations are foregrounded, from United Nations negotiations and the measurement of carbon stocks, to business venture and legal work. The paper proposes a focus on the mundane that attends to details and frictions. This provides a deflationary story of the marketization of forest carbon, a story of contingencies and unexpected ramifications

Association of Apgar scores with death and neurologic disability

Apgar score was devised with the aim to standardize the assessment of newborns. It has been used worldwide to evaluate infants’ condition immediately after birth, to determine their need for resuscitation, and to evaluate the effectiveness of resuscitation. Apgar score was never intended for prediction of outcome beyond the immediate postnatal period; however, since low scores correlate with prenatal and perinatal adversities, multiple studies have examined the relation between the value of Apgar score and duration of low (<7) Apgar score and subsequent death or neurologic disability. This article reviews such studies. The author concludes that the overall evidence shows consistent association of low Apgar scores with increased risks of neonatal and infant death and with neurologic disability, including cerebral palsy, epilepsy, and cognitive impairment. Dose-response patterns have been shown for the value of Apgar score and duration of low score and the outcomes of mortality and neurologic disability. The association of Apgar score <7 at five minutes with increased risks of neurologic disability seems to persist many years postnatally. Some corresponding relative risk estimates are large (eg, four to seven for epilepsy or more than 20 for cerebral palsy), while others are modest (eg, 1.33 for impaired cognitive function). The absolute risks, however, are low (<5% in for most neurologic conditions), and majority of surviving babies with low Apgar scores grow up without disability. The low magnitude of absolute risks makes Apgar score a poor clinical predictor of long-term outcome. Nevertheless, the observed associations point to the importance of fetal and perinatal periods for neurodevelopment