Variable grouping in multivariate time series via correlation

The decomposition of high-dimensional multivariate time series (MTS) into a number of low-dimensional MTS is a useful but challenging task because the number of possible dependencies between variables is likely to be huge. This paper is about a systematic study of the “variable groupings” problem in MTS. In particular, we investigate different methods of utilizing the information regarding correlations among MTS variables. This type of method does not appear to have been studied before. In all, 15 methods are suggested and applied to six datasets where there are identifiable mixed groupings of MTS variables. This paper describes the general methodology, reports extensive experimental results, and concludes with useful insights on the strength and weakness of this type of grouping metho

Mechanism of how augmin directly targets the γ-tubulin ring complex to microtubules

Microtubules (MTs) must be generated from precise locations to form the structural frameworks required for cell shape and function. MTs are nucleated by the γ-tubulin ring complex (γ-TuRC), but it remains unclear how γ-TuRC gets to the right location. Augmin has been suggested to be a γ-TuRC targeting factor and is required for MT nucleation from preexisting MTs. To determine augmin's architecture and function, we purified Xenopus laevis augmin from insect cells. We demonstrate that augmin is sufficient to target γ-TuRC to MTs by in vitro reconstitution. Augmin is composed of two functional parts. One module (tetramer-II) is necessary for MT binding, whereas the other (tetramer-III) interacts with γ-TuRC. Negative-stain electron microscopy reveals that both tetramers fit into the Y-shape of augmin, and MT branching assays reveal that both are necessary for MT nucleation. The finding that augmin can directly bridge MTs with γ-TuRC via these two tetramers adds to our mechanistic understanding of how MTs can be nucleated from preexisting MTs

Miura type transformations and homogeneous spaces

We relate Miura type transformations (MTs) over an evolution system to its zero-curvature representations with values in Lie algebras g. We prove that certain homogeneous spaces of g produce MTs and show how to distinguish these spaces. For a scalar translation-invariant evolution equation this allows to classify all MTs in terms of homogeneous spaces of the Wahlquist-Estabrook algebra of the equation. For other evolution systems this allows to construct some MTs. As an example, we study MTs over the KdV equation, a 5th order equation of Harry-Dym type, and the coupled KdV-mKdV system of Kersten and Krasilshchik.Comment: 17 pages; v3, v2: minor improvement

Auras in patients with temporal lobe epilepsy and mesial temporal sclerosis.

We investigated auras in patients with drug-resistant temporal lobe epilepsy (TLE) and mesial temporal sclerosis (MTS). We also investigated the clinical differences between patients with MTS and abdominal auras and those with MTS and non-mesial temporal auras. All patients with drug-resistant TLE and unilateral MTS who underwent epilepsy surgery at Jefferson Comprehensive Epilepsy Center from 1986 through 2014 were evaluated. Patients with good postoperative seizure outcome were investigated. One hundred forty-nine patients (71 males and 78 females) were studied. Thirty-one patients (20.8%) reported no auras, while 29 patients (19.5%) reported abdominal aura, and 30 patients (20.1%) reported non-mesial temporal auras; 16 patients (10.7%) had sensory auras, 11 patients (7.4%) had auditory auras, and five patients (3.4%) reported visual auras. A history of preoperative tonic-clonic seizures was strongly associated with non-mesial temporal auras (odds ratio 3.8; 95% CI: 1.15-12.98; p=0.02). About one-fifth of patients who had MTS in their MRI and responded well to surgery reported auras that are historically associated with non-mesial temporal structures. However, the presence of presumed non-mesial temporal auras in a patient with MTS may herald a more widespread epileptogenic zone

Cooperative Local Caching under Heterogeneous File Preferences

Local caching is an effective scheme for leveraging the memory of the mobile terminal (MT) and short range communications to save the bandwidth usage and reduce the download delay in the cellular communication system. Specifically, the MTs first cache in their local memories in off-peak hours and then exchange the requested files with each other in the vicinity during peak hours. However, prior works largely overlook MTs' heterogeneity in file preferences and their selfish behaviours. In this paper, we practically categorize the MTs into different interest groups according to the MTs' preferences. Each group of MTs aims to increase the probability of successful file discovery from the neighbouring MTs (from the same or different groups). Hence, we define the groups' utilities as the probability of successfully discovering the file in the neighbouring MTs, which should be maximized by deciding the caching strategies of different groups. By modelling MTs' mobilities as homogeneous Poisson point processes (HPPPs), we analytically characterize MTs' utilities in closed-form. We first consider the fully cooperative case where a centralizer helps all groups to make caching decisions. We formulate the problem as a weighted-sum utility maximization problem, through which the maximum utility trade-offs of different groups are characterized. Next, we study two benchmark cases under selfish caching, namely, partial and no cooperation, with and without inter-group file sharing, respectively. The optimal caching distributions for these two cases are derived. Finally, numerical examples are presented to compare the utilities under different cases and show the effectiveness of the fully cooperative local caching compared to the two benchmark cases