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Two common approaches to identify subgroups of patients with bipolar disorder are clustering methodology (mixture analysis) based on the age of onset, and a birth cohort analysis. This study investigates if a birth cohort effect will influence the results of clustering on the age of onset, using a large, international database.
The database includes 4037 patients with a diagnosis of bipolar I disorder, previously collected at 36 collection sites in 23 countries. Generalized estimating equations (GEE) were used to adjust the data for country median age, and in some models, birth cohort. Model-based clustering (mixture analysis) was then performed on the age of onset data using the residuals. Clinical variables in subgroups were compared.
There was a strong birth cohort effect. Without adjusting for the birth cohort, three subgroups were found by clustering. After adjusting for the birth cohort or when considering only those born after 1959, two subgroups were found. With results of either two or three subgroups, the youngest subgroup was more likely to have a family history of mood disorders and a first episode with depressed polarity. However, without adjusting for birth cohort (three subgroups), family history and polarity of the first episode could not be distinguished between the middle and oldest subgroups.
These results using international data confirm prior findings using single country data, that there are subgroups of bipolar I disorder based on the age of onset, and that there is a birth cohort effect. Including the birth cohort adjustment altered the number and characteristics of subgroups detected when clustering by age of onset. Further investigation is needed to determine if combining both approaches will identify subgroups that are more useful for research.
We propose that pressure anisotropy causes weakly collisional turbulent plasmas to self-organize so as to resist changes in magnetic-field strength. We term this effect ‘magneto-immutability’ by analogy with incompressibility (resistance to changes in pressure). The effect is important when the pressure anisotropy becomes comparable to the magnetic pressure, suggesting that in collisionless, weakly magnetized (high-
) plasmas its dynamical relevance is similar to that of incompressibility. Simulations of magnetized turbulence using the weakly collisional Braginskii model show that magneto-immutable turbulence is surprisingly similar, in most statistical measures, to critically balanced magnetohydrodynamic turbulence. However, in order to minimize magnetic-field variation, the flow direction becomes more constrained than in magnetohydrodynamics, and the turbulence is more strongly dominated by magnetic energy (a non-zero ‘residual energy’). These effects represent key differences between pressure-anisotropic and fluid turbulence, and should be observable in the
turbulent solar wind.
In collisionless and weakly collisional plasmas, such as hot accretion flows onto compact objects, the magnetorotational instability (MRI) can differ significantly from the standard (collisional) MRI. In particular, pressure anisotropy with respect to the local magnetic-field direction can both change the linear MRI dispersion relation and cause nonlinear modifications to the mode structure and growth rate, even when the field and flow perturbations are very small. This work studies these pressure-anisotropy-induced nonlinearities in the weakly nonlinear, high-ion-beta regime, before the MRI saturates into strong turbulence. Our goal is to better understand how the saturation of the MRI in a low-collisionality plasma might differ from that in the collisional regime. We focus on two key effects: (i) the direct impact of self-induced pressure-anisotropy nonlinearities on the evolution of an MRI mode, and (ii) the influence of pressure anisotropy on the ‘parasitic instabilities’ that are suspected to cause the mode to break up into turbulence. Our main conclusions are: (i) The mirror instability regulates the pressure anisotropy in such a way that the linear MRI in a collisionless plasma is an approximate nonlinear solution once the mode amplitude becomes larger than the background field (just as in magnetohyrodynamics). This implies that differences between the collisionless and collisional MRI become unimportant at large amplitudes. (ii) The break up of large-amplitude MRI modes into turbulence via parasitic instabilities is similar in collisionless and collisional plasmas. Together, these conclusions suggest that the route to magnetorotational turbulence in a collisionless plasma may well be similar to that in a collisional plasma, as suggested by recent kinetic simulations. As a supplement to these findings, we offer guidance for the design of future kinetic simulations of magnetorotational turbulence.
The presence of multiple fields during inflation might seed a detectable amount of non-Gaussianity in the curvature perturbations, which in turn becomes observable in present data sets like the cosmic microwave background (CMB) or the large scale structure (LSS). Within this proceeding we present a fully analytic method to infer inflationary parameters from observations by exploiting higher-order statistics of the curvature perturbations. To keep this analyticity, and thereby to dispense with numerically expensive sampling techniques, a saddle-point approximation is introduced whose precision has been validated for a numerical toy example. Applied to real data, this approach might enable to discriminate among the still viable models of inflation.
The interaction of barotropic tidal currents and baroclinic geostrophic eddies is considered theoretically and numerically to determine whether energy can be transferred to an internal wave field by this process. The eddy field evolves independently of the tide, suggesting that it acts catalytically in facilitating energy transfer from the barotropic tide to the internal wave field, without exchanging energy with the other flow components. The interaction is identically zero and no waves are generated when the barotropic tidal current is horizontally uniform. Optimal internal wave generation occurs when the scales of tide and eddy fields satisfy resonant conditions. The most efficient generation is found if the tidal current horizontal scale is comparable to that of the eddies, with a weak maximum when the scales differ by a factor of two. Thus, this process is not an effective mechanism for internal wave excitation in the deep ocean, where tidal current scales are much larger than those of eddies, but it may provide an additional source of internal waves in coastal areas where horizontal modulation of the tide by topography can be significant.
It has been hypothesised that organically grown vegetables are healthier than conventionally produced ones due to a higher content of phytochemicals. However, few data from controlled human studies exist. The aim of the present study was to compare the carotenoid content and antioxidant capacity of organically and conventionally produced carrots under defined conditions. Furthermore, a human intervention study was conducted to compare bioavailability, plasma antioxidant capacity, endogenous DNA strand breaks and immune parameters in healthy men ingesting carrots from different agricultural systems. Thirty-six volunteers consumed either organically or conventionally produced blanched carrots (200 g/d; 2 weeks) or no carrots in a double-blind, randomised intervention study. No statistically significant differences were observed in the total carotenoid contents (121 (sd 7) μg/g organic v. 116 (sd 13) μg/g conventional) and the antioxidant capacities (0·43 (sd 0·08) μmol Trolox equivalents/g organic v. 0·32 (sd 0·07) μmol Trolox equivalents/g conventional) of the carrots administered to the volunteers. Intake of organically or conventionally produced carrots significantly increased (P < 0·001) plasma α- and β-carotene concentrations in both intervention groups without differences in plasma carotenoid concentrations. Consumption of carrots did not lead to significant changes in the plasma antioxidant status, endogenous DNA strand breaks and parameters of the immune system in all groups. Therefore, these results indicate that the agricultural system has neither an effect on the carotenoid content, the antioxidant capacity of carrots, nor on the bioavailability of carotenoids and on antioxidant, antigenotoxic and immunological effects as assessed in a human intervention study.
Magnetic fields can be generated during an inflationary phase in the early universe
by amplification of perturbations of the electromagnetic field. The resulting magnetic fields can have interesting field strengths if the conformal invariance of Maxwell's equations is broken. Two particular models are discussed, one based on extra dimensions and one on nonlinear electrodynamics.
The interaction of Sr(II) with CSH phases has been investigated to distinguish adsorption from co-precipitation processes and to assess the relevance of these processes for performance assessments. Batch-type sorption experiments were carried out to study the adsorption of Sr(II) on synthetic CSH phases at different C:S ratios. Co-precipitation experiments were conducted by precipitating CSH phases in the presence of Sr(II) at two different precipitation rates.
Distribution ratios (Rd) of Sr(II) obtained from the sorption and co-precipitation studies were found to be similar in value. The results indicate that co-precipitation processes do not enhance Sr(II) uptake by CSH compared to adsorption. In both the co-precipitation and adsorption experiments the same sorption sites are accessible to Sr(II). The precipitation rate of the CSH phases has no significant influence on the Rd values.
Apple fruits and grapevine leaves were inoculated with four wild-type strains of Botrytis cinerea. Two types of symptoms were
observed on apple, firm or soft rot. Extracts from infected tissues were analysed for polygalacturonase (PG) and pectin
methylesterase (PME) isozyme profiles. They showed that different specific PG isozymes occur in grapevine leaves and in soft rot on
apple fruit. PG and PME profiles were also studied in genetic transformants altered in their colonization ability and/or the type of
rot that they caused on apple fruit. No PG activity was found in apples infected by firm-rotting wild-type strains or transformants,
whereas two neutral PG isozymes (pIs 7.3 and 7.6) were expressed in soft-rotting strains. No association was found between the
production of these PG isozymes and the colonization level. The PME patterns were not correlated with the rotting type nor the
colonization level. In vitro, firm-rotting strains and transformants showed no PG activity in glucose medium whereas soft-rotting
ones produced several PG isozymes. In polygalacturonic acid cultures, all strains and transformants produced a single, common acidic
isozyme. Unlike PG, no variation in the PME isozyme patterns in vitro could be correlated with the culture substrate on apple or the
rotting type. The variation in pectinase profiles between in vitro and in planta contexts and the role of PGs in B. cinerea
pathogenicity on apple fruit is discussed. We suggest that neutral PG isozymes are involved in the soft-rotting type on apple fruit.
The metabolic response of dairy cows to high as opposed to low altitude conditions (2000 m v. 400 m above sea level) was determined. In the first experiment, four cows were subjected to a series of measurements before, during and after transport from lowland to high altitude pasture. During transport, cortisol, l-lactate and non-esterified fatty acids were significantly elevated but decreased within 1 to 3 days to initial levels. After transport, β-hydroxybutyrate and the thyroid hormones immediately increased and returned within 3 weeks to initial levels. Plasma urea increased during transport and subsequently was at an intermediate level due to the different diet. There were no direct carry-over effects of transport on metabolic traits during pasturing.
In the second experiment, three groups of six different dairy cows were either grazed in one of two consecutive years or kept inside (2nd year only). Lowland sojourn lasted for 4 weeks, and high altitude period for 8 weeks. At the end of high altitude sojourn, both outside and inside groups were found still to have significantly higher plasma cortisol values than at lowland. Thyroid hormones and ketosis related metabolites sharply increased at the start of the alpine period and were elevated for 1 to 3 weeks thereafter. According to the hormonal and metabolic profiles, the permanently housed cows did not benefit from the less adverse climatic conditions and the lower physical strain. Plasma urea closely reflected dietary changes in the ratio of nitrogen to fermentable organic matter. Plasma protein, albumin, creatinine, and liver enzyme activities were not affected by transport or high altitude sojourn in both experiments. The results indicate that the metabolic response to transport and high altitude conditions can be mostly explained by the efforts to cover the additional energy requirements. Overall the data suggest a wide but nevertheless limited ability of early-lactating cows to adapt to high altitude conditions.
We use the second derivative of intertwining operators to realize a unitary structure for the irreducible subrepresentations in the reducible spherical principal series of U(1, n). These representations can also be realized as the kernels of certain invariant first-order differential operators acting on sections of homogeneous bundles over the hyperboloid (U(1) × U(n))/U(1, n).
Concurrent engineering is a systematic approach to the integrated, concurrent design of products and the related processes of manufacturing and support. This approach is intended to cause the developers, from the outset, to consider all elements of the product life cycle from concept through disposal, including quality, cost, schedule, and user requirements. To achieve successful concurrent-engineering design, one needs an integrated framework, a well-organized design team, and adequate design tools. The research on concurrent engineering to date has focused on developing communication infrastructure, design tools, and product data representations. Little attention has been paid to developing tools to address the organizational issues involved in concurrent engineering. The authors’ research on the Virtual Design Team (VDT) attempts to develop a computerized analysis tool to sup-port the systematic design of organization structures for concurrent engineering projects. VDT is a computer simulation system. It takes descriptions of design tasks, actors (i.e., designers and managers), and organization structure as input, and produces predicted historical records of the actors’ design and coordination behavior, project du-ration, cost, and design process quality as output. VDT has been applied to model more than ten realistic engineering projects, and the results are qualitatively consistent with the predictions from theory and project managers. The VDT framework for modeling concurrent-engineering teams is described, and examples of VDT applications are presented to demonstrate the effectiveness of the Virtual Design Team approach to modeling the organizational behavior of concurrent design teams.
By studying the topography of crazes and shear deformation zones in polymer films with the Atomic Force Microscope (AFM), it was found that crazes and shear deformation zones grew by a micro-necking process. This discovery indicates that when a glassy polymer undergoes local deformations, the material drawn into the deformation zones continues to be deformed until a much later time than that previously understood. Details of the craze micro-necking mechanism and its important implications will be discussed. Based on the necking mechanics, it was shown that craze initiation and growth can be examined using a modified Considere construction, and the stress distribution within a micro-deformation zone was investigated by assuming the Bridgman's theory. The results of the stress analysis are in excellent agreement with the breakdown behavior of crazes observed experimentally. The Young's moduli of the crazed and sheared polymers within the tiny deformation zones were also measured using a simple new AFM technique. Evidence of strain softening was clearly observed in that both the Young's moduli of crazes and shear deformation zones were very low compared to that in the bulk.
Photoreactions in polyalkylsilyne thin films induced by ArFlaser (193 nm) irradiation have been examined. Photoexcitation of the σ-conjugated Si-network at 193 nm (6.42 eV) results in Si-Si bond scission and alkyl-group desorption when irradiated in a vacuum. In addition to these processes, efficient (up to 7% quantum efficiency) insertion of oxygen into the Si backbone occurs when the irradiation is performed in air, resulting in the formation of a siloxane. Both infrared and X-ray photoelectron spectroscopies indicate a higher oxygen coordination about the Si atoms in the oxidized product than observed for linear polysilanes. This higher oxygen coordination indicates a siloxane network. The polysilynes have been demonstrated as deep UV photoresists and may have additional applications as precursors for thin film or binary optical components.
This paper develops a philosophy for the use of Artificial Intelligence (AI) techniques as aids in engineering project management.
First, we propose that traditional domain-independent, ‘means–and’ planners, may be valuable aids for planning detailed subtasks on projects, but that domain-specific planning tools are needed for work package or executive level project planning. Next, we propose that hybrid computer systems, using knowledge processing techniques in conjunction with procedural techniques such as decision analysis and network-based scheduling, can provide valuable new kinds of decision support for project objective-setting and project control, respectively. Finally we suggest that knowledge-based interactive graphics, developed for providing graphical explanations and user control in advanced knowledge processing environments, can provide powerful new kinds of decision support for project management.
The first claim is supported by a review and analysis of previous work in the area of automated AI planning techniques. Our experience with PLATFORM I, II and III, a series of prototype AI-leveraged project management systems built using the IntelliCorp Knowledge Engineering Environment (KEE™), provides the justification for the latter two claims.
The distribution and seasonal abundance of Stomoxys nigra nigra Macq. and S. calcitrans (L.) in Mauritius was determined by field surveys in 1973–74. S. nigra, the species of major importance, is most common throughout the wetter, higher elevations where it becomes a major pest of cattle. S. calcitrans occurs throughout the island to a much lesser extent. Coastal areas with less than 60 inches of rain are generally free of damaging infestations of both species. Seasonal infestation levels were determined by making counts of flies feeding on animals and of flies on resting surfaces. Populations of up to 200 S. nigra per animal were highest during the warm, wet, sugar-cane cropping season but declined to generally non-damaging levels during the cool season. S. calcitrans increased up to 145 flies/animal during the cool, drier season and virtually disappeared during the wet season. S. nigra accounted for up to 98% of the total Stomoxys infestation with S. calcitrans making up 62 % of the total at one study site during the study.
Sugar-cane debris in fields was found to be the primary breeding source for 5. nigra, whereas decaying manure and organic matter provided the source for S. calcitrans. Generation-to-generation increases were usually below five-fold for both species. Both species exhibit two feeding peaks throughout the day at temperatures of 14°C or above.