322 research outputs found

    Preconditioning for Allen-Cahn variational inequalities with non-local constraints

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    The solution of Allen-Cahn variational inequalities with mass constraints is of interest in many applications. This problem can be solved both in its scalar and vector-valued form as a PDE-constrained optimization problem by means of a primal-dual active set method. At the heart of this method lies the solution of linear systems in saddle point form. In this paper we propose the use of Krylov-subspace solvers and suitable preconditioners for the saddle point systems. Numerical results illustrate the competitiveness of this approach

    \u3ci\u3eEuscorpius sulfur\u3c/i\u3e sp. n. (Scorpiones: Euscorpiidae), a new cave scorpion from Albania and northwestern Greece

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    A new species of cave scorpion, Euscorpius sulfur sp. n. (Scorpiones: Euscorpiidae) from Albania and northwestern Greece is described, fully complemented with color photographs of both live and preserved specimens, as well as their habitats

    Standing genetic variation as a potential mechanism of novel cave phenotype evolution in the freshwater isopod, Asellus aquaticus

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    Novel phenotypes can come about through a variety of mechanisms including standing genetic variation from a founding population. Cave animals are an excellent system in which to study the evolution of novel phenotypes such as loss of pigmentation and eyes. Asellus aquaticus is a freshwater isopod crustacean found in Europe and has both a surface and a cave ecomorph which vary in multiple phenotypic traits. An orange eye phenotype was previously revealed by F2 crosses and backcrosses to the cave parent within two examined Slovenian cave populations. Complete loss of pigmentation, both in eye and body, is epistatic to the orange eye phenotype and therefore the orange eye phenotype is hidden within the cave populations. Our goal was to investigate the origin of the orange eye alleles within the Slovenian cave populations by examining A. aquaticus individuals from Slovenian and Romanian surface populations and Asellus aquaticus infernus individuals from a Romanian cave population. We found orange eye individuals present in lab raised surface populations of A. aquaticus from both Slovenia and Romania. Using a mapping approach with crosses between individuals of two surface populations, we found that the region known to be responsible for the orange eye phenotype within the two previously examined Slovenian cave populations was also responsible within both the Slovenian and the Romanian surface populations. Complementation crosses between orange eye Slovenian and orange eye Romanian surface individuals suggest that the same gene is responsible for the orange eye phenotype in both surface populations. Additionally, we observed a low frequency phenotype of eye loss in crosses generated between the two surface populations and also in the Romanian surface population. Finally, in a cave population from Romania, A. aquaticus infernus, we found that the same region is also responsible for the orange eye phenotype as the Slovenian cave populations and the Slovenian and Romanian surface populations. Therefore, we present evidence that variation present in the cave populations could originate from standing variation present in the surface populations and/or transgressive hybridization of different surface phylogenetic lineages rather than de novo mutations

    Chronogaster troglodytes sp n (Nemata, Chronogasteridae) from Mobile cave, with a review of cavernicolous nematodes

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    Summary -Chronogaster lroglodytes sp. n. (Nemata : Chronogasteridae) is described as the first true cavernicolous nematode which was recovered from Movile Cave in Romania. This species is adapted for survival in floating fungal mats growing in hydrogen sulfide-rich thermomineral waters. Populations are composed of hermaphroditic females which feed on bacteria associated with the fungal mats. A review of cavernicolous nematodes, and their relationship to epigean freshwater and soil forms, is presented

    Strong Gravitational Lensing and Dark Energy Complementarity

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    In the search for the nature of dark energy most cosmological probes measure simple functions of the expansion rate. While powerful, these all involve roughly the same dependence on the dark energy equation of state parameters, with anticorrelation between its present value w_0 and time variation w_a. Quantities that have instead positive correlation and so a sensitivity direction largely orthogonal to, e.g., distance probes offer the hope of achieving tight constraints through complementarity. Such quantities are found in strong gravitational lensing observations of image separations and time delays. While degeneracy between cosmological parameters prevents full complementarity, strong lensing measurements to 1% accuracy can improve equation of state characterization by 15-50%. Next generation surveys should provide data on roughly 10^5 lens systems, though systematic errors will remain challenging.Comment: 7 pages, 5 figure

    Quantitative ultrasound to monitor the vascular response to tocilizumab in giant cell arteritis.

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    OBJECTIVES To characterize the effect of ultra-short glucocorticoids followed by Tocilizumab monotherapy on the intima-media thickness (IMT) in GCA. METHODS 18 GCA patients received 500mg methylprednisolone intravenously on days 0-2, followed by Tocilizumab (8mg/kg) intravenously on day 3 and thereafter weekly subcutaneous Tocilizumab injections (162 mg) over 52 weeks. Ultrasound of temporal (TA), axillary (AA) and subclavian (SA) arteries was performed at baseline, on days 2-3, at week 4, 8, 12, 24 and 52. The largest IMT of all segments and IMT at landmarks of AA/SA were recorded. IMT was scaled by mean normal values and averaged. Each segment was classified according to diagnostic cut-offs. RESULTS 16 patients had TA and 6 had extracranial large artery involvement. The IMT showed a sharp decline on day 2/3 in the TA and AA/SA. In TA, this was followed by an increase to baseline levels at week 4 and a subsequent slow decrease, which was paralleled by decreasing symptoms and achievement of clinical remission. The AA/SA showed a new signal of vasculitis at week 4 in three patients with an IMT increase up to week 8. CONCLUSIONS Glucocorticoid pulse therapy induced a transient decrease of the IMT in TA and AA/SA. Tocilizumab monotherapy resulted in a slow and steady decrease in IMT of the TA and a smaller and delayed effect on the AA/SA. The data strongly support a remission-inducing effect of Tocilizumab and argue for an important role of ultrasound in monitoring disease activity in GCA

    Evaluating the approximation of the affinity laws and improving the efficiency estimate for variable speed pumps

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    Affinity laws relate to the characteristics of pumps operating at different speeds, and in a water distribution context, are usually used to predict the pump curve of variable speed pumps (VSPs). VSPs can adjust the pump curve to meet the network requirements more efficiently with resultant savings of energy. The estimation of the effectiveness of a VSP is based on hydraulic simulations, in which the behavior of VSPs is described using the affinity laws. The affinity laws, however, contain approximations because they do not take into account factors that do not scale with velocity. In particular, the approximation inherent in the affinity law that computes power and efficiency can produce a misleading result, especially for small-size pumps. The research reported in this paper estimates the error in efficiency for a wide range of pump sizes and tests the use of a previously proposed formula as an alternative to the affinity law. Results show that a better estimation can be achieved for the efficiency of small- and medium-size pumps. Moreover the formula can be easily implemented in hydraulic solvers. © 2013 American Society of Civil Engineers.Angus R. Simpson and Angela March

    Dynamics of Void and its Shape in Redshift Space

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    We investigate the dynamics of a single spherical void embedded in a Friedmann-Lema\^itre universe, and analyze the void shape in the redshift space. We find that the void in the redshift space appears as an ellipse shape elongated in the direction of the line of sight (i.e., an opposite deformation to the Kaiser effect). Applying this result to observed void candidates at the redshift z~1-2, it may provide us with a new method to evaluate the cosmological parameters, in particular the value of a cosmological constant.Comment: 19 pages, 11 figure

    Time-Varying Dark Energy Constraints From the Latest SN Ia, BAO and SGL

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    Based on the latest SNe Ia data provided by Hicken et al. (2009) with using MLCS17 light curve fitter, together with the Baryon Acoustic Oscillation(BAO) and strong gravitational lenses(SGL), we investigate the constraints on the dark energy equation-of-state parameter ww in the flat universe, especially for the time-varying case w(z)=w0+wzz/(1+z)w(z)=w_0+w_zz/(1+z). The constraints from SNe data alone are found to be: (a) (ΩM,w)=(0.358,−1.09)(\Omega_M, w)=(0.358, -1.09) as the best-fit results; (b) (w0,wz)=(−0.73−0.97+0.23,0.84−10.34+1.66)(w_0, w_z)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34}) for the two parameters in the time-varying case after marginalizing the parameter ΩM\Omega_M; (c) the likelihood of parameter wzw_z has a high non-Gaussian distribution; (d) an extra restriction on ΩM\Omega_M is necessary to improve the constraint of the SNe Ia data on the parameters (w0w_0, wzw_z). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between ww and ΩM\Omega_M, and leads to the interesting maximum likelihoods w0=−0.94w_0 = -0.94 and wz=0w_z = 0. When marginalizing the parameter ΩM\Omega_M, the fitting results are found to be (w0,wz)=(−0.95−0.18+0.45,0.41−0.96+0.79)(w_0, w_z)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96}). After adding the splitting angle statistic of SGL data, a consistent constraint is obtained (ΩM,w)=(0.298,−0.907)(\Omega_M, w)=(0.298, -0.907) and the constraints on time-varying dark energy are further improved to be (w0,wz)=(−0.92−0.10+0.14,0.35−0.54+0.47)(w_0, w_z) = (-0.92^{+0.14}_{-0.10}, 0.35^{+0.47}_{-0.54}), which indicates that the phantom type models are disfavored.Comment: 24 pages, 9 figures, to be published in JCA
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