On different cascade-speeds for longitudinal and transverse velocity increments

We address the problem of differences between longitudinal and transverse velocity increments in isotropic small scale turbulence. The relationship of these two quantities is analyzed experimentally by means of stochastic Markovian processes leading to a phenomenological Fokker- Planck equation from which a generalization of the Karman equation is derived. From these results, a simple relationship between longitudinal and transverse structure functions is found which explains the difference in the scaling properties of these two structure functions.Comment: 4 pages, 5 figures, now with corrected postscrip

Regeneration of Stochastic Processes: An Inverse Method

We propose a novel inverse method that utilizes a set of data to construct a simple equation that governs the stochastic process for which the data have been measured, hence enabling us to reconstruct the stochastic process. As an example, we analyze the stochasticity in the beat-to-beat fluctuations in the heart rates of healthy subjects as well as those with congestive heart failure. The inverse method provides a novel technique for distinguishing the two classes of subjects in terms of a drift and a diffusion coefficients which behave completely differently for the two classes of subjects, hence potentially providing a novel diagnostic tool for distinguishing healthy subjects from those with congestive heart failure, even at the early stages of the disease development.Comment: 5 pages, two columns, 7 figs. to appear, The European Physical Journal B (2006

Ion acceleration in plasmas emerging from a helicon-heated magnetic-mirror device

Using laser-induced fluorescence, measurements have been made of metastable argon-ion, Ar{sup +}*(3d{sup 4} f{sub 7/2}), velocity distributions on the major axis of an axisymmetric magnetic-mirror device whose plasma is sustained by helicon wave absorption. Within the mirror, these ions have sub-eV temperature and, at most, a subthermal axial drift. In the region outside the mirror coils, conditions are found where these ions have a field-parallel velocity above the acoustic speed, to an axial energy of {approx}30 eV, while the field-parallel ion temperature remains low. The supersonic Ar{sup +}*(3d{sup 4} f{sub 7/2}) are accelerated to one-third of their final energy within a short region in the plasma column, {le}1 cm, and continue to accelerate over the next 5 cm. Neutral gas density strongly affects the supersonic Ar{sup +}*(3d{sup 4} f{sub 7/2}) density

Risk factors for adverse perinatal outcomes in imprisoned pregnant women: a systematic review

BACKGROUND: Imprisoned pregnant women constitute an important obstetric group about whom relatively little is known. This systematic review was conducted to identify the risk factors associated with adverse pregnancy outcome present in this group of women. METHODS: The review was conducted according to a prespecified protocol. Studies of any design were included if they described information on any of the pre-specified risk factors. We calculated the results as summary percentages or odds ratios where data was available on both cases and population controls. RESULTS: The search strategy identified 27 relevant papers of which 13 met the inclusion criteria, involving 1504 imprisoned pregnant women and 4571 population control women. Imprisoned women are more likely to be single, from an ethnic minority, and not to have completed high school. They are more likely to have a medical problem which could affect the pregnancy outcome and yet less likely to receive adequate antenatal care. They are also more likely to smoke, drink alcohol to excess and take illegal drugs. CONCLUSION: Imprisoned women are clearly a high risk obstetric group. These findings have important implications for the provision of care to this important group of women

The influence of thermal cycles on the microstructure of grade 92 steel

The microstructure in the heat-affected zone (HAZ) of welds made from the 9 wt pct chromium martensitic Grade 92 steel is complex and has not yet been completely understood. There is a lack of systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel welds as a function of the welding process. In this study, the microstructure in the HAZ of an as-fabricated single-pass bead-on-plate weld on a parent metal of Grade 92 steel was systematically investigated by using an extensive range of electron and ion-microscopy-based techniques. A dilatometer was used to apply controlled thermal cycles to simulate the microstructures in the different regions of the HAZ. A wide range of microstructural properties in the simulated materials were then characterized and compared with the experimental observations from the weld HAZ. It was found that the microstructure in the HAZ of a single-pass Grade 92 steel weld can be categorized as a function of a decreasing peak temperature reached as (1) the completely transformed (CT) region, in which the original matrix is completely reaustenitized with complete dissolution of the pre-existing secondary precipitate particles; (2) the partially transformed (PT) region, where the original matrix is partially reaustenitized along with a partial dissolution of the secondary precipitate particles from the original matrix; and (3) the overtempered (OT) region, where the pre-xisting precipitate particles coarsen. The PT region is considered to be the susceptible area for damage in the commonly reported HAZ failures in weldments constructed from these types of steels

Fractional solubility of aerosol iron : synthesis of a global-scale data set

Aerosol deposition provides a major input of the essential micronutrient iron to the open ocean. A critical parameter with respect to bioavailability is the proportion of aerosol iron that enters the oceanic dissolved iron pool – the so-called fractional solubility of aerosol iron (%FeS). Here we present a global-scale compilation of total aerosol iron loading (FeT) and %FeS values for ~1100 samples collected over the open ocean, the coastal ocean, and some continental sites, including new data from the Atlantic Ocean. The global-scale compilation reveals a remarkably consistent trend in the fractional solubility of aerosol iron as a function of total aerosol iron loading, with the great bulk of the data falling along an inverse hyperbolic trend. The large dynamic range in %FeS (0-95%) varies with FeT in a manner similar to that identified for aerosols collected in the Sargasso Sea by Sedwick et al. (2007), who posit that the trend reflects near-conservative mixing between air masses that carry lithogenic mineral dust (with high FeT and low %FeS) and non-soil-dust aerosols such as anthropogenic combustion emissions (with low FeT and high %FeS), respectively. An increasing body of empirical evidence points to the importance of aerosol source and composition in determining the fractional solubility of aerosol iron, such that anthropogenic combustion emissions appear to play a critical role in determining this parameter in the bulk marine aerosol. The robust global-scale relationship between %FeS and FeT may provide a simple heuristic method for estimating aerosol iron solubility at the regional to global scale

Independent evolution of shape and motility allows evolutionary flexibility in Firmicutes bacteria

Functional morphological adaptation is an implicit assumption across many ecological studies. However, despite a few pioneering attempts to link bacterial form and function, functional morphology is largely unstudied in prokaryotes. One intriguing candidate for analysis is bacterial shape, as multiple lines of theory indicate that cell shape and motility should be strongly correlated. Here we present a large-scale use of modern phylogenetic comparative methods to explore this relationship across 325 species of the phylum Firmicutes. In contrast to clear predictions from theory, we show that cell shape and motility are not coupled, and that transitions to and from flagellar motility are common and strongly associated with lifestyle (free-living or host-associated). We find no association between shape and lifestyle, and contrary to recent evidence, no indication that shape is associated with pathogenicity. Our results suggest that the independent evolution of shape and motility in this group might allow a greater evolutionary flexibility

New Directions in the Development of Population Estimates in the United States?

The advent of a continuously updated Master Area File (MAF) following the 2000 census represents an information resource that can be tapped for purposes of developing timely, cost-effective, and precise population estimates for even the smallest of geographical units (e.g., census blocks). We argue that the MAF can be enhanced (EMAF) for these purposes. In support of our argument we describe a set of activities needed to develop EMAF, each of which is well within the current capabilities of the U.S. Census Bureau and discuss various costs and benefits of each. We also describe how EMAF would provide population estimates containing a wide range of demographic (e.g., age, race, and sex) and socio-economic characteristics (e.g., educational attainment, income, and employment). As such, it could largely negate and eliminate the need for many of the traditional demographic methods of population estimation and possibly reduce the number of sample surveys. We identify important challenges that must be surmounted in order to realize EMAF and make suggestions for doing so. We conclude by noting that the idea of the EMAF could be of interest to other countries with MAF files and strong administrative records systems that, like the United States, are facing the challenge of producing good population information in the face of increasing census costs

Identifying Canadian Freshwater Fishes through DNA Barcodes

BACKGROUND: DNA barcoding aims to provide an efficient method for species-level identifications using an array of species specific molecular tags derived from the 5' region of the mitochondrial cytochrome c oxidase I (COI) gene. The efficiency of the method hinges on the degree of sequence divergence among species and species-level identifications are relatively straightforward when the average genetic distance among individuals within a species does not exceed the average genetic distance between sister species. Fishes constitute a highly diverse group of vertebrates that exhibit deep phenotypic changes during development. In this context, the identification of fish species is challenging and DNA barcoding provide new perspectives in ecology and systematics of fishes. Here we examined the degree to which DNA barcoding discriminate freshwater fish species from the well-known Canadian fauna, which currently encompasses nearly 200 species, some which are of high economic value like salmons and sturgeons. METHODOLOGY/PRINCIPAL FINDINGS: We bi-directionally sequenced the standard 652 bp "barcode" region of COI for 1360 individuals belonging to 190 of the 203 Canadian freshwater fish species (95%). Most species were represented by multiple individuals (7.6 on average), the majority of which were retained as voucher specimens. The average genetic distance was 27 fold higher between species than within species, as K2P distance estimates averaged 8.3% among congeners and only 0.3% among concpecifics. However, shared polymorphism between sister-species was detected in 15 species (8% of the cases). The distribution of K2P distance between individuals and species overlapped and identifications were only possible to species group using DNA barcodes in these cases. Conversely, deep hidden genetic divergence was revealed within two species, suggesting the presence of cryptic species. CONCLUSIONS/SIGNIFICANCE: The present study evidenced that freshwater fish species can be efficiently identified through the use of DNA barcoding, especially the species complex of small-sized species, and that the present COI library can be used for subsequent applications in ecology and systematics