Warped Functional Analysis of Variance

This article presents an Analysis of Variance model for functional data that explicitly incorporates phase variability through a time-warping component, allowing for a unified approach to estimation and inference in presence of amplitude and time variability. The focus is on single-random-factor models but the approach can be easily generalized to more complex ANOVA models. The behavior of the estimators is studied by simulation, and an application to the analysis of growth curves of flour beetles is presented. Although the model assumes a smooth latent process behind the observed trajectories, smoothness of the observed data is not required; the method can be applied to the sparsely observed data that is often encountered in longitudinal studies

Permutation tests for the equality of covariance operators of functional data with applications to evolutionary biology

In this paper, we generalize the metric-based permutation test for the equality of covariance operators proposed by Pigoli et al. (2014) to the case of multiple samples of functional data. To this end, the non-parametric combination methodology of Pesarin and Salmaso (2010) is used to combine all the pairwise comparisons between samples into a global test. Different combining functions and permutation strategies are reviewed and analyzed in detail. The resulting test allows to make inference on the equality of the covariance operators of multiple groups and, if there is evidence to reject the null hypothesis, to identify the pairs of groups having different covariances. It is shown that, for some combining functions, step-down adjusting procedures are available to control for the multiple testing problem in this setting. The empirical power of this new test is then explored via simulations and compared with those of existing alternative approaches in different scenarios. Finally, the proposed methodology is applied to data from wheel running activity experiments, that used selective breeding to study the evolution of locomotor behavior in mice.A. Cabassi was supported by the MRC (project reference MC_UP_0801/1) and by a “Tesi all’estero” scholarship from Politecnico di Milano, Italy. The authors also wish to thank The Washington State University College of Arts and Sciences, Office of International Programs and Office of Research for travel grants to P.A. Carter

Dynamical Stability of Witten Rings

The dynamical stability of cosmic rings, or vortons, is investigated for the particular equation of state given by the Witten bosonic model. It is found that there exists a finite range of the state parameter for which the vorton states are actually stable against dynamical perturbations. Inclusion of the electromagnetic self action into the equation of state slightly shrinks the stability region but otherwise yields no qualitative difference. If the Witten bosonic model represents a good approximation for more realistic string models, then the cosmological vorton excess problem can only be solved by assuming either that strings are formed at low energy scales or that some quantum instability may develop at a sufficient rate.Comment: 11 pages, LaTeX-ReVTeX (v.3), 2 figures available upon request, DAMTP R-94/1

Seagrasses in the Mississippi and Chandeleur Sounds and Problems Associated with Decadal-Scale Change Detection

Seagrass mapping data from a multitude of previous projects in the Mississippi and Chandeleur sounds were gathered and combined to provide information on seagrass change from 1940 to 2011. Seagrasses generally occur in three groups: (1) along the Mississippi mainland coastline dominated by Ruppia maritima, (2) on the north side of Mississippi Sound barrier islands dominated by Halodule wrightii, and (3) on the west side of the Chandeleur Islands dominated by Thalassia testudinum co-occurring with other seagrass species. The study area generally lost seagrasses over the 71-yr period, ostensibly due to loss or reduction of protective island barriers and reductions in water quality. An example of how the time series of maps generated in this project can be utilized to further investigate seagrass change was demonstrated with data from Horn Island, including problems associated with calculating change in seagrass area using data from previous investigations. Comparisons of seagrass area among various studies that used different mapping methods (seagrass extent vs. seagrass coverage vs. vegetated seagrass area) can result in overestimation of area change and misleading conclusions

SURFACE CURRENT-CARRYING DOMAIN WALLS

Domain walls, arising from the spontaneous breaking of a discrete symmetry, can be coupled to charge carriers. In much the same way as the Witten model for superconducting cosmic string, an investigation is made here in the case of $U(1)\times Z_2 \to U(1)$, where a bosonic charge carrier is directly coupled to the wall-forming Higgs field. All internal quantities, such as the energy per unit surface and the surface current, are calculated numerically to provide the first complete analysis of the internal structure of a surface current-carrying domain wall.Comment: 11 pages, LaTeX-ReVTeX v.3, 2 figures available upon reques

Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes

In [arXiv:0803.3259] the equations describing the parallel transport of orthonormal frames along timelike (spacelike) geodesics in a spacetime admitting a non-degenerate principal conformal Killing-Yano 2-form h were solved. The construction employed is based on studying the Darboux subspaces of the 2-form F obtained as a projection of h along the geodesic trajectory. In this paper we demonstrate that, although slightly modified, a similar construction is possible also in the case of null geodesics. In particular, we explicitly construct the parallel-transported frames along null geodesics in D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport along principal null directions in these spacetimes. Such directions coincide with the eigenvectors of the principal conformal Killing-Yano tensor. Finally, we show how to obtain a parallel-transported frame along null geodesics in the background of the 4D Plebanski-Demianski metric which admits only a conformal generalization of the Killing-Yano tensor.Comment: 17 pages, no figure

Current-carrying cosmic string loops 3D simulation: towards a reduction of the vorton excess problem

The dynamical evolution of superconducting cosmic string loops with specific equations of state describing timelike and spacelike currents is studied numerically. This analysis extends previous work in two directions: first it shows results coming from a fully three dimensional simulation (as opposed to the two dimensional case already studied), and it now includes fermionic as well as bosonic currents. We confirm that in the case of bosonic currents, shocks are formed in the magnetic regime and kinks in the electric regime. For a loop endowed with a fermionic current with zero-mode carriers, we show that only kinks form along the string worldsheet, therefore making these loops slightly more stable against charge carrier radiation, the likely outcome of either shocks or kinks. All these combined effects tend to reduce the number density of stable loops and contribute to ease the vorton excess problem. As a bonus, these effects also may provide new ways of producing high energy cosmic rays.Comment: 11 pages, RevTeX 4 format, 8 figures, submitted to PR

Dilatonic current-carrying cosmic strings

We investigate the nature of ordinary cosmic vortices in some scalar-tensor extensions of gravity. We find solutions for which the dilaton field condenses inside the vortex core. These solutions can be interpreted as raising the degeneracy between the eigenvalues of the effective stress-energy tensor, namely the energy per unit length U and the tension T, by picking a privileged spacelike or timelike coordinate direction; in the latter case, a phase frequency threshold occurs that is similar to what is found in ordinary neutral current-carrying cosmic strings. We find that the dilaton contribution for the equation of state, once averaged along the string worldsheet, vanishes, leading to an effective Nambu-Goto behavior of such a string network in cosmology, i.e. on very large scales. It is found also that on small scales, the energy per unit length and tension depend on the string internal coordinates in such a way as to permit the existence of centrifugally supported equilibrium configuration, also known as vortons, whose stability, depending on the very short distance (unknown) physics, can lead to catastrophic consequences on the evolution of the Universe.Comment: 10 pages, ReVTeX, 2 figures, minor typos corrected. This version to appear in Phys. Rev.

Navigating the “No Man\u27s Land” of TKI-Failed EGFR-Mutated Non– Small Cell Lung Cancer (NSCLC): A Review

As the leading cause of cancer-related mortality, lung cancer is a worldwide health issue that is overwhelmingly caused by smoking. However, a substantial minority (~25%) of patients with non–small cell lung cancer (NSCLC) has never smoked. In these patients, activating mutations of the epidermal growth factor receptor (EGFR) are more likely, which render their tumors susceptible for a finite period to treatment with EGFR tyrosine kinase inhibitors (TKIs) and confer a better prognosis than EGFR wild-type NSCLC. On progression, due to the inevitable insurgence of resistance, TKIs are generally followed by second- or third-line salvage chemotherapy until treatment failure, after which no standard treatment options are available, resulting in a poor prognosis and a high risk of death. With the focus of clinical attention on treatment with TKIs, few studies on optimal salvage therapies, including cytotoxic chemotherapy, after failure of EGFR TKIs have been reported. Despite a paucity of available data, the aim of this review is to summarize the “no-man\u27s land” of TKI-failed EGFR-mutated NSCLC and expand on alternative strategies as well as potential future directions