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Selected AbstractsPredictions and tests of climate-based hypotheses of broad-scale variation in taxonomic richnessECOLOGY LETTERS, Issue 12 2004David J. Currie Abstract Broad-scale variation in taxonomic richness is strongly correlated with climate. Many mechanisms have been hypothesized to explain these patterns; however, testable predictions that would distinguish among them have rarely been derived. Here, we examine several prominent hypotheses for climate,richness relationships, deriving and testing predictions based on their hypothesized mechanisms. The ,energy,richness hypothesis' (also called the ,more individuals hypothesis') postulates that more productive areas have more individuals and therefore more species. More productive areas do often have more species, but extant data are not consistent with the expected causal relationship from energy to numbers of individuals to numbers of species. We reject the energy,richness hypothesis in its standard form and consider some proposed modifications. The ,physiological tolerance hypothesis' postulates that richness varies according to the tolerances of individual species for different sets of climatic conditions. This hypothesis predicts that more combinations of physiological parameters can survive under warm and wet than cold or dry conditions. Data are qualitatively consistent with this prediction, but are inconsistent with the prediction that species should fill climatically suitable areas. Finally, the ,speciation rate hypothesis' postulates that speciation rates should vary with climate, due either to faster evolutionary rates or stronger biotic interactions increasing the opportunity for evolutionary diversification in some regions. The biotic interactions mechanism also has the potential to amplify shallower, underlying gradients in richness. Tests of speciation rate hypotheses are few (to date), and their results are mixed. [source] Symmetric Galerkin BEM for multi-connected bodiesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2001J. J. Pérez-Gavilán In this paper, it is shown that the symmetric Galerkin boundary element formulation cannot be used in its standard form for multiple connected bodies. This is because the traction integral equation used for boundaries with Neuman boundary condition give non-unique solutions. While this fact is well known from the classical theory of integral equations, the problem has not been fully addressed in the literature related to symmetric Galerkin formulations. In this paper, the problem is reviewed and a general way to deal with it is proposed. The details of the numerical implementation are discussed and an example is solved to demonstrate the effectiveness of the proposed solution. Copyright © 2001 John Wiley & Sons, Ltd. [source] A stabilized SPH method for inviscid shallow water flows,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2005Riadh Ata Abstract In this paper, the smoothed particle hydrodynamics (SPH) method is applied to the solution of shallow water equations. A brief review of the method in its standard form is first described then a variational formulation using SPH interpolation is discussed. A new technique based on the Riemann solver is introduced to improve the stability of the method. This technique leads to better results. The treatment of solid boundary conditions is discussed but remains an open problem for general geometries. The dam-break problem with a flat bed is used as a benchmark test. Copyright © 2004 John Wiley & Sons, Ltd. [source] Extending the Frisch scheme for errors-in-variables identification to correlated output noiseINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2008Torsten Söderström Abstract Several estimation methods have been proposed for identifying errors-in-variables systems, where both input and output measurements are corrupted by noise. One of the promising approaches is the so-called Frisch scheme. In its standard form, it is designed to handle white measurement noise on the input and output sides. As the output noise comprises both effects of measurement errors and of process disturbances, it is much more realistic to allow correlated output noise. It is described in the paper how the Frisch scheme can be extended to such cases. Copyright © 2007 John Wiley & Sons, Ltd. [source] Models of non-smooth switches in electrical systemsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 3 2005Christoph Glocker Abstract Idealized modelling of diodes, relays and switches in the framework of linear complementarity is introduced. Within the charge approach, the classical electromechanical analogy is extended to passively and actively switching components in electrical circuits. The associated branch relations are expressed in terms of set-valued functions, which allow to formulate the circuit's dynamic behaviour as a differential inclusion. This approach is demonstrated by the example of the DC,DC buck converter. A difference scheme, known in mechanics as time stepping, is applied for numerical approximation of the evolution problem. The discretized inclusions are formulated as a linear complementarity problem in standard form, which implicitly takes care of all switching events by its solution. State reduction, which requires manipulation of the set-valued branch relations in order to obtain a minimal model, is performed on the example of the buck converter. Copyright © 2005 John Wiley & Sons, Ltd. [source] Tikhonov regularization in standardized and general form for multivariate calibration with application towards removing unwanted spectral artifactsJOURNAL OF CHEMOMETRICS, Issue 1-2 2006Forrest Stout Abstract Tikhonov regularization (TR) is an approach to form a multivariate calibration model for y,=,Xb. It includes a regulation operator matrix L that is usually set to the identity matrix I and in this situation, TR is said to operate in standard form and is the same as ridge regression (RR). Alternatively, TR can function in general form with L,,,I where L is used to remove unwanted spectral artifacts. To simplify the computations for TR in general form, a standardization process can be used on X and y to transform the problem into TR in standard form and a RR algorithm can now be used. The calculated regression vector in standardized space must be back-transformed to the general form which can now be applied to spectra that have not been standardized. The calibration model building methods of principal component regression (PCR), partial least squares (PLS) and others can also be implemented with the standardized X and y. Regardless of the calibration method, armed with y, X and L, a regression vector is sought that can correct for irrelevant spectral variation in predicting y. In this study, L is set to various derivative operators to obtain smoothed TR, PCR and PLS regression vectors in order to generate models robust to noise and/or temperature effects. Results of this smoothing process are examined for spectral data without excessive noise or other artifacts, spectral data with additional noise added and spectral data exhibiting temperature-induced peak shifts. When the noise level is small, derivative operator smoothing was found to slightly degrade the root mean square error of validation (RMSEV) as well as the prediction variance indicator represented by the regression vector 2-norm thereby deteriorating the model harmony (bias/variance tradeoff). The effective rank (ER) (parsimony) was found to decrease with smoothing and in doing so; a harmony/parsimony tradeoff is formed. For the temperature-affected data and some of the noisy data, derivative operator smoothing decreases the RMSEV, but at a cost of greater values for . The ER was found to increase and hence, the parsimony degraded. A simulated data set from a previous study that used TR in general form was reexamined. In the present study, the standardization process is used with L set to the spectral noise structure to eliminate undesirable spectral regions (wavelength selection) and TR, PCR and PLS are evaluated. There was a significant decrease in bias at a sacrifice to variance with wavelength selection and the parsimony essentially remains the same. This paper includes discussion on the utility of using TR to remove other undesired spectral patterns resulting from chemical, environmental and/or instrumental influences. The discussion also incorporates using TR as a method for calibration transfer. Copyright © 2006 John Wiley & Sons, Ltd. [source] Joint tracking controller for multi-link flexible robot using disturbance observer and parameter adaptation schemeJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8 2002Joono Cheong An improved composite controller of singular perturbation approach is designed for controlling a multi-link flexible robot with uncertainties. We adopt the standard form of a singular perturbation approach for modeling. To reduce the coupling effect from flexibility, the bandwidth of a slow subsystem is modulated by considering the fundamental frequency. The disturbance observer provides a means for defining the bandwidth of a slow subsystem as well as compensating disturbances. At the same time, uncertainties in the fast subsystem are updated to enhance the capability for vibration suppression in conjunction with PID (Proportional-integrative derivative) modal feedback. We draw conditions for Lyapunov stability of the modal feedback and adaptive scheme. A numerical simulation will support the validity of our research results. © 2002 Wiley Periodicals, Inc. [source] 'Anything you can do, tu can do better': tu and vous as substitutes for indefinite on in FrenchJOURNAL OF SOCIOLINGUISTICS, Issue 2 2003Aidan Coveney Research on Montreal French (Laberge and Sankoff 1979; Thibault 1991) has shown a spectacular rise in the use of indefinite tu (or vous) in recent decades, at the expense of the standard form on. Although grammars of French have traditionally passed over indefinite tu/vous in silence, Ashby's study of Tours French (1992) confirmed that the phenomenon exists in metropolitan French also. The historical time-depth of indefinite tu/vous has apparently not been explored previously, though Posner (1997) has suggested that indefinite tu is a modern feature, found especially in Canada. A survey of indefinite tu/vous in earlier periods and in a range of varieties forms the first part of this paper. Secondly, drawing on a corpus of French spoken in Picardy, northern France, the paper investigates the extent to which this use of the 2nd person pronouns: (i) helps to avoid ambiguity; (ii) co-occurs with another grammatical variable. Unlike the surveys of Montreal and Tours, the Picardy corpus includes a large majority of informants who used tu to address the interviewer, and this too is explored as a potential influence on speakers' use of 2nd person pronouns with indefinite reference. [source] Solution-precipitation creep , micromechanical modelling and numerical resultsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Sandra Ili Our aim is to present a continuum mechanical model for solution-precipitation creep as well as to compare the numerical results based on that model with experimental observations. The formulation of the problem is based on the minimization of a Lagrangian consisting of elastic power and dissipation. Elastic energy is chosen to be in a standard form but dissipation is strongly adapted to the solution-precipitation process by introducing two new quantities: the velocity of material transport within the crystallite-interfaces and the normal velocity of precipitation or solution respectively. The model enables one to give an analytical solution for the case of a single crystal and numerical solution based on a finite element method for more complex, polycrystalline materials. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Debt v. Foreign Direct Investment: The Impact of Sovereign Risk on the Structure of International Capital FlowsECONOMICA, Issue 273 2002Monika Schnitzer The paper compares the two standard forms of international investment in developing countries, debt and foreign direct investment (FDI), from a finance perspective. The sovereign risks associated with debt finance are shown to be generally less severe than the ones that come with FDI. FDI is chosen only if the foreign investor is more efficient in running the project, if the project is risky, and if the foreign investor has a good outside option which deters creeping expropriation. The sovereign risk problem of FDI can be alleviated if the host country and the foreign investor form a joint venture. [source] Cost of Alzheimer's disease in a developing country settingINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 7 2005M. Zencir Abstract Purpose To evaluate the economic impact of AD in Denizli, Turkey. Design and Methods This observational study was conducted with 42 AD patients and their primary caregivers. During the initial interview, demographic data and medical histories were collected with questionnaires. For an observational period of 15 days, data on time spent for patient care were collected using standard forms. Calculations on direct cost (e.g. per day medication, outpatient physician visits during the last 3 months), indirect cost (e.g. time spent for care by caregiver for daily living (ADL) and instrumental activity of daily living (IADL)) were made by summing up and taking averages of the appropriate items. ANOVA, and linear regressions were the methods for comparisons. Results The primary caregivers of the patients mainly were their children and/or spouses. The maximum mean time spent (h/week) was 21.0 (17.5) for severely damaged cognition. The average annual cost per case was between $1,766 [95% Confidence Intervals (CI); 1.300,2.231] and $4,930 (95% CI; 3.3714,6.147). The amount of caregiver cost was the most significant item in the overall cost and it showed an increase with the declining cognitive function of patients. Daily medication cost reflected the same pattern. In contrast, cost of outpatient physician was the lowest among the patients with the worst cognition. Conclusions These results suggest that recently AD has become a significant cost for developing countries. This pilot study gives an idea of the cost of AD in developing countries where determining the actual cost can be difficult. Copyright © 2005 John Wiley & Sons, Ltd. [source] Temporary workers in Washington StateAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2010Caroline K. Smith MPH Abstract Background Evidence regarding the unequal burden of occupational injuries between workers employed by temporary agencies and those in standard employment arrangements is unclear. Studies range from no significant differences in risk to substantial increased risk for temporary workers. The purpose of this study is to compare the workers' compensation experience of a large cohort of temporary agency employed workers with those in standard forms of employment. Methods Washington State Fund workers' compensation data were obtained for claims with injury dates from January 1, 2003 to June 30, 2006, resulting in 342,540 accepted claims. General descriptive statistics, injury rates (per 10,000 FTE), and rate ratios (temp agency/standard employer) were computed by injury type and industry. Results Temporary agency employed workers had higher rates of injury for all injury types, and higher median time loss (40 vs. 27 days) but lower time loss costs (median $1,224 vs. $1,914, P,<,0.001) and lower medical costs ($3,026 vs. $4,087, P,<,0.001) than standard arrangement workers. Temporary agency workers had substantially higher rates for "caught in" and "struck by" injuries in the construction (IRR 4.93; 95% CI 2.80,8.08) and manufacturing (IRR 4.05; 95% CI 3.25, 5.00) industry sectors. Conclusion Temporary agency employed workers have higher claims incidence rates than those in standard employment arrangements. The rate ratios are twofold higher in the construction and manufacturing industry sectors. More research is needed to explore potential reasons for this disparity in occupational injuries. Industry or some measure of job exposure should be included when comparing injury rates in different types of employment in order to better identify areas for prevention. Am. J. Ind. Med. 53:135,145 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||