Power-law behaviour evaluation from foreign exchange market data using a wavelet transform method

Numerous studies in the literature have shown that the dynamics of many time series including observations in foreign exchange markets exhibit scaling behaviours. A simple new statistical approach, derived from the concept of the continuous wavelet transform correlation function (WTCF), is proposed for the evaluation of power-law properties from observed data. The new method reveals that foreign exchange rates obey power-laws and thus belong to the class of self-similarity processes. (C) 2009 Elsevier B.V. All rights reserved

Comparison of some Reduced Representation Approximations

In the field of numerical approximation, specialists considering highly complex problems have recently proposed various ways to simplify their underlying problems. In this field, depending on the problem they were tackling and the community that are at work, different approaches have been developed with some success and have even gained some maturity, the applications can now be applied to information analysis or for numerical simulation of PDE's. At this point, a crossed analysis and effort for understanding the similarities and the differences between these approaches that found their starting points in different backgrounds is of interest. It is the purpose of this paper to contribute to this effort by comparing some constructive reduced representations of complex functions. We present here in full details the Adaptive Cross Approximation (ACA) and the Empirical Interpolation Method (EIM) together with other approaches that enter in the same category

Host range of chlamydiaphages fCPAR39 and Chp3

The host range of CPAR39 is limited to four Chlamydophila species: C. abortus, C. caviae, C. pecorum, and C. pneumoniae. Chp3 (a newly discovered bacteriophage isolated from C. pecorum) shares three of these hosts (C. abortus, C. caviae, and C. pecorum) but can additionally infect Chlamydophila felis. The ability to support replication was directly correlated with the binding properties of the respective bacteriophages with their host species. Binding studies also show that CPAR39 and Chp3 use different host receptors to infect the same host cells: cell binding is sensitive to proteinase K treatment, confirming that the chlamydiaphage receptors are proteinaceous in nature

Biological properties and cell tropism of Chp2, a bacteriophage of the obligate intracellular bacterium Chlamydophila abortus

A number of bacteriophages belonging to the Microviridae have been described infecting chlamydiae. Phylogenetic studies divide the Chlamydiaceae into two distinct genera, Chlamydia and Chlamydophila, containing three and six different species, respectively. In this work we investigated the biological properties and host range of the recently described bacteriophage Chp2 that was originally discovered in Chlamydophila abortus. The obligate intracellular development cycle of chlamydiae has precluded the development of quantitative approaches to assay bacteriophage infectivity. Thus, we prepared hybridomas secreting monoclonal antibodies (monoclonal antibodies 40 and 55) that were specific for Chp2. We demonstrated that Chp2 binds both C. abortus elementary bodies and reticulate bodies in an enzyme-linked immunosorbent assay. Monoclonal antibodies 40 and 55 also detected bacteriophage Chp2 antigens in chlamydia-infected eukaryotic cells. We used these monoclonal antibodies to monitor the ability of Chp2 to infect all nine species of chlamydiae. Chp2 does not infect members of the genus Chlamydia (C. trachomatis, C. suis, or C. muridarum). Chp2 can infect C. abortus, C. felis, and C. pecorum but is unable to infect other members of this genus, including C. caviae and C. pneumoniae, despite the fact that these chlamydial species support the replication of very closely related bacteriophages

Significant intra-annual variability in krill distribution and abundance at South Georgia revealed by multiple acoustic surveys during 2000/01

Three separate acoustic surveys of Antarctic krill (Euphausia superba) were conducted around South Georgia in the 2000/01 season: in October 2000 (early-season); during late December/early January 2000/01 (mid-season), and in March 2001 (late-season). The surveys were the first in a newly planned five-year series of observations designed to complement and extend an existing time series regularly maintained by the British Antarctic Survey since 1996 (and on a more ad hoc basis since the early 1980s). We hoped that conducting several surveys in one season would provide information on short-term variability that could be used to set data from more restricted once-per-season 'snap-shot' cruises in a broader context. The early- and late-season surveys were associated with logistic support voyages to South Georgia and were restricted to four transects within a box to the northwest of South Georgia. The dedicated mid-season survey covered that box in more detail (twice as many transects) and, in addition, examined boxes to the north, northeast and southwest of the island. Together these surveys provided temporally and spatially extensive coverage around South Georgia. Krill density in the western box in the early-season survey was very low (3.5 g m(-2)) but rose significantly (P = 0.020) by mid-season (to 34.7 g m(-2)). In a pattern that is consistent with observations from previous years, krill density in the western box in the mid-season survey was less than that in the eastern box (80.4 g m(-2)). Analysis of transect data obtained in the western box in the mid-season survey revealed no significant difference in the mean krill density derived from only those four transects surveyed early- and late-season, or from the full eight transects. Our first occupation of a survey box off the central north coast of South Georgia in mid-season revealed a krill density of 47.2 g m(-2) that was intermediate between the eastern and western areas. The size structure of the krill in the central region also reflected a mix of those to the east (generally small) and west (generally large). Krill density to the southwest of South Georgia was 32.1 g m(-2) in mid-season. By March, krill density in the western survey area had fallen significantly (P = 0.037) from the mid-season high to 7.8 g m(-2). Our multiple surveys at South Georgia have revealed major intra-annual changes in krill density at the island and have shown that the timing of the acoustic survey can affect significantly the estimate of krill density. The multiple estimates of krill density will allow reproductive performance indices for top level predators to be compared to prey availability at more appropriate time-scales than previous single 'snap-shot' acoustic survey data have allowed. This is a crucial step in the elucidation of response functions of dependent species to changes in krill abundance, and could be a useful contribution to ecosystem management

Birth Weight, Stress, and the Metabolic Syndrome in Adult Life

There is now widespread agreement that small size at birth is associated with an increased risk of the metabolic syndrome (glucose intolerance, high blood pressure, and dyslipidemia) and related pathologies, including cardiovascular disease in later life. Evidence is emerging that suggests that programming of hormonal systems in response to an adverse fetal environment may be one of the mechanisms underlying these long-term consequences of growth restriction in early life. In particular, alterations in neuroendocrine responses to stress may be important. Recent research suggests that increased adrenocortical and sympathoadrenal responses are associated with small size at birth. Epidemiological studies show that such physiological alterations in these neuroendocrine systems may have potent effects on risk of cardiovascular disease through their influence on risk factors, such as plasma glucose and lipid concentrations and blood pressur