Mosses from the Mascarenes - 6

Sixty taxa of mosses, mainly pleurocarps, are reported from the Mascarenes. Two are new to Afr.3 sensu Index Muscorum, i.e., Brachythecium plumosum (Hedwig) Schimper in BSG and Palamocladium sericeum (Jaeger) C.Müller. Nine are new to the Mascarenes, i.e., Brachythecium decurrens Cardot, Callicostella parvocellulata Demaret & P.Varde, Helicodontium lanceolatum (Hampe & C.Müller) Jaeger, Lepidopilum carrougeauanum Thér. & P.Varde, Mittenothamnium microthamnioides (Geh.) Wijk & Marg., Orthostichopsis longinervis (Ren. & Cardot) Broth., Plagiothecium nitens Dixon, Rhynchostegium comorae (C.Müller) Jaeger and Trachypus bicolor var. hispidulus (C.Müller) Cardot. One is new to Mauritius and Réunion, but known from Rodrigues, i.e., Meiothecium madagascariense (Bridel) Broth. Five taxa are new to Mauritius, i.e., Callicostella salaziae (Besch.) Broth., Lopidium struthiopteris (Bridel) Fleischer, Macrohymenium acidodon (Mont.) Dozy & Molk., Orthostichella pentasticha (Bridel) Buck and Vesicularia lepervanchei (Besch.) Broth

Mosses from the Mascarenes : 3

37 species of mosses are reported from the Mascarenes. Of these 19 belong to the genus Campylopus and 8 to Leucoloma. Three are new to the Mascarenes i.e. Campylopus leucochlorus (C.Müll.) Par., C. paludicola Broth. and C. subperichaetialis Biz. & Kilb., two are new to Mauritius i.e. Bryum truncorum (Brid.) Brid. and Leucoloma cinclidotioides Besch. and four are new to Réunion i.e. Campylopus incacorralis Herz. C. praetermissus J.-P. Frahm, C. trachyblepharon (C. Müll.) Mitt. ssp. comatus (Ren. & Card.) J.- P. Frahm and Leucoloma rutenbergii (Geh.) Wright var. elatum Ren. The variety is new to the Mascarenes

Any Dark Saying:Louis MacNeice in the Nineteen Fifties

The contours of Louis MacNeice's career are rarely contested: from the high point of his nineteen thirties work, reaching a crescendo with Autumn Journal (1939), he drifted into a slump, reaching a nadir with two collections from the early nineteen fifties, Ten Burnt Offerings (1952) and Autumn Sequel (1954), before reviving to develop a startling new style at the end of the decade. The historical moment clearly demanded stylistic renegotiation, both for poets living in Ireland and those outside it, but in comparison with the new styles developed coterminously by Clarke and Kavanagh, MacNeice's late work is stark, suggestive of nightmarish solipsism and a breakdown of social cohesion. If the failure of his volumes from the early Fifties suggested a symbolic break between self and society, his subsequent inward turn affirms the self as the ground of lyric poetry. MacNeice's late work should be understood as symptomatic of an encroaching dissolution of communality that would profoundly affect the cultures of both islands as the twentieth century progressed. This essay explores MacNeice's stylistic evolution at mid century and considers the extent to which these developments were an essential foundation for the creation of his remarkable late style. </jats:p

Sparse and Unique Nonnegative Matrix Factorization Through Data Preprocessing

Nonnegative matrix factorization (NMF) has become a very popular technique in machine learning because it automatically extracts meaningful features through a sparse and part-based representation. However, NMF has the drawback of being highly ill-posed, that is, there typically exist many different but equivalent factorizations. In this paper, we introduce a completely new way to obtaining more well-posed NMF problems whose solutions are sparser. Our technique is based on the preprocessing of the nonnegative input data matrix, and relies on the theory of M-matrices and the geometric interpretation of NMF. This approach provably leads to optimal and sparse solutions under the separability assumption of Donoho and Stodden (NIPS, 2003), and, for rank-three matrices, makes the number of exact factorizations finite. We illustrate the effectiveness of our technique on several image datasets.Comment: 34 pages, 11 figure

Robustness Analysis of Hottopixx, a Linear Programming Model for Factoring Nonnegative Matrices

Although nonnegative matrix factorization (NMF) is NP-hard in general, it has been shown very recently that it is tractable under the assumption that the input nonnegative data matrix is close to being separable (separability requires that all columns of the input matrix belongs to the cone spanned by a small subset of these columns). Since then, several algorithms have been designed to handle this subclass of NMF problems. In particular, Bittorf, Recht, R\'e and Tropp (`Factoring nonnegative matrices with linear programs', NIPS 2012) proposed a linear programming model, referred to as Hottopixx. In this paper, we provide a new and more general robustness analysis of their method. In particular, we design a provably more robust variant using a post-processing strategy which allows us to deal with duplicates and near duplicates in the dataset.Comment: 23 pages; new numerical results; Comparison with Arora et al.; Accepted in SIAM J. Mat. Anal. App

Damping of thermoelastic structures

Report ascertains the effects of thermoelastic damping on the propagation of longitudinal waves in cylindrical rods. Review of results of wave propagation in unbounded elastic solids and in elastic cylinders precedes consideration of thermal modification of elastic properties