Vector chiral order in frustrated spin chains

By means of a numerical analysis using a non-Abelian symmetry realization of the density matrix renormalization group, we study the behavior of vector chirality correlations in isotropic frustrated chains of spin S=1 and S=1/2, subject to a strong external magnetic field. It is shown that the field induces a phase with spontaneously broken chiral symmetry, in line with earlier theoretical predictions. We present results on the field dependence of the order parameter and the critical exponents.Comment: 8 pages, 9 figure

Modeling Marsh‐Forest Boundary Transgression in Response to Storms and Sea‐Level Rise

The lateral extent and vertical stability of salt marshes experiencing rising sea levels depend on interacting drivers and feedbacks with potential for nonlinear behaviors. A two‐dimensional transect model was developed to examine changes in marsh and upland forest lateral extent and to explore controls on marsh inland transgression. Model behavior demonstrates limited and abrupt forest retreat with long‐term upland boundary migration rates controlled by slope, sea‐level rise (SLR), high water events, and biotic‐abiotic interactions. For low to moderate upland slopes the landward marsh edge is controlled by the interaction of these inundation events and forest recovery resulting in punctuated transgressive events. As SLR rates increase, the importance of the timing and frequency of water‐level deviations diminishes, and migration rates revert back to a slope‐SLR‐dominated process

Measurement of Transverse Polarization of Electrons Emitted in Free Neutron Decay

The final analysis of the experiment determining both components of the transverse polarization of electrons ($\sigma_{T_{1}}$, $\sigma_{T_{2}}$) emitted in the $\beta$-decay of polarized, free neutrons is presented. The T-odd, P-odd correlation coefficient quantifying $\sigma_{T_{2}}$, perpendicular to the neutron polarization and electron momentum, was found to be $R=$ 0.004$\pm0.012\pm$0.005. This value is consistent with time reversal invariance, and significantly improves both earlier result and limits on the relative strength of imaginary scalar couplings in the weak interaction. The value obtained for the correlation coefficient associated with $\sigma_{T_{1}}$, $N=$ 0.067$\pm0.011\pm$0.004, agrees with the Standard Model expectation, providing an important sensitivity test of the experimental setup. The present result sets constraints on the imaginary part of scalar and tensor couplings in weak interaction. Implications for parameters of the leptoquark exchange model and minimal supersymmetric model (MSSM) with R-parity violation are discussed

Subject-oriented plural method meets BPMN: a case study

Subject-oriented approach to business process management focuses on the subjects and their interactions with the aim to capture more accurate process information with increased fidelity. In a common setting, business processes are modeled by process engineers or modeling experts who often create their processes in a top-down fashion. However, this may pose risks to the acceptance and adoption of these models in practice, particularly in knowledge-centric environments. The Plural method follows a subject-oriented approach and allows process participants, rather than a centralized group of process engineers, to model and maintain their processes in a decentralized way. It guides process participants to focus on the roles and their interactions in terms of message exchanges. This study investigates the use of BPMN 2.0 for the Plural method. With the aim to show the applicability of the notation for a subject-oriented approach and report on the benefits and limitations of the new edition of the Plural method in general, we performed a case study in an industry company. Guided by a coordinator, 11 process participants modeled four processes that they participate by following the Plural method. These models were also compared with the classical models developed prior to the application of the Plural method to better understand the influence. Analyses showed that the application of the Plural resulted in more complete process models. However, there are concerns regarding the understandability of these models when compared with their classical counterparts. It has been shown that the Plural method is a powerful tool for process discovery and modeling, but an improvement on its models is needed to obtain full value of the framework

Inelastic interaction mean free path of negative pions in tungsten

The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm

Parameter Estimation and Quantitative Parametric Linkage Analysis with GENEHUNTER-QMOD

Objective: We present a parametric method for linkage analysis of quantitative phenotypes. The method provides a test for linkage as well as an estimate of different phenotype parameters. We have implemented our new method in the program GENEHUNTER-QMOD and evaluated its properties by performing simulations. Methods: The phenotype is modeled as a normally distributed variable, with a separate distribution for each genotype. Parameter estimates are obtained by maximizing the LOD score over the normal distribution parameters with a gradient-based optimization called PGRAD method. Results: The PGRAD method has lower power to detect linkage than the variance components analysis (VCA) in case of a normal distribution and small pedigrees. However, it outperforms the VCA and Haseman-Elston regression for extended pedigrees, nonrandomly ascertained data and non-normally distributed phenotypes. Here, the higher power even goes along with conservativeness, while the VCA has an inflated type I error. Parameter estimation tends to underestimate residual variances but performs better for expectation values of the phenotype distributions. Conclusion: With GENEHUNTER-QMOD, a powerful new tool is provided to explicitly model quantitative phenotypes in the context of linkage analysis. It is freely available at http://www.helmholtz-muenchen.de/genepi/downloads. Copyright (C) 2012 S. Karger AG, Base

Response to ranibizumab therapy in neovascular AMD - an evaluation of good and bad responders

Background: Treatment of neovascular age-related macular degeneration (AMD) with Lucentis® shows a broad spectrum regarding the course of visual acuity (VA). While some patients show a good response (increase in VA), others disclose much less promising results. Patients and Methods: A retrospective data analysis of all eyes treated for neovascular AMD at the University Hospital of Zurich, Switzerland for at least 12 months was carried out. The courses of VA between the 90th (good responders, GR) and the 10th (bad responders, BR) percentiles were compared at 3, 12 and 24 months from baseline. An analysis regarding demographic data, lesion type and size as well as injection frequency and visits was done and predictive factors for GR and BR were evaluated. Results: Marked differences in the course of VA between GR (n = 30) and BR (n = 30) are already observed 3 months from baseline. In GR the gains in VA after 3, 12 and 24 were 15.7 ± 9 letters ETDRS, 25.3 ± 7 and 14.0 ± 14. BR showed a deterioration of 8.3 ± 11 letters ETDRS after 3, 22.1 ± 8 after 12 and 23.6 ± 13 after 24 months. The gender distribution was equal with a higher percentage of female patients (64 % in BR and 66 % in GR). The baseline VA was statistically significantly lower in GR (45.7 ± 10 vs. 55.4 ± 11, p < 0.05) than in BR. No other significant differences in baseline data were found, and no predictor for group membership could be identified. Conclusions: Only the course of VA in the first three months seems to be of value for an estimation of the response to treatment. In the future the response to treatment in the early phase may influence the treatment algorithm and the injection frequency

Search for the Hypothetical pi -> mu x Decay

The KARMEN collaboration has reported the possible observation of a hitherto unknown neutral and weakly interacting particle x, which is produced in the decay pi -> mu + x with a mass m(x) = 33.9 MeV. We have searched for this hypothetical decay branch by studying muons from pion decay in flight with the LEPS spectrometer at the piE3 channel at PSI and find branching ratios BR(pi- to mu- anti-x) < 4e-7 and BR(pi+ to mu+ x) < 7e-8 (95\% C.L.). Together with the limit BR > 2e-8 derived in a recent theoretical paper our result would leave only a narrow region for the existence of x if it is a heavy neutrino.Comment: 10 pages, TeX (uses epsf), 3 Postscript figures uu-encode