No abstract

No abstract

A bounded linear operator T on a Hilbert space H is called an misometry for a positive integer m if m k=0 (−1) m−k m k T * k T k = 0. We prove some properties concerning the behaviour of the orbit of an m-isometry. For example, every orbit of an m-isometry is eventually norm increasing and some m-isometries can not be N -supercyclic, that is, there does not exist an Ndimensional subspace EN such that the orbit of T at EN is dense in H.

Academic performance during the first year of university is correlated with future academic success, and is considered to be a determining factor in the reduction of dropouts. In the present study, we describe a new academic performance indicator for the first term of first‐year science degrees students at La Laguna University in Spain. We are interested in identifying the most important previous academic factors for predicting the success of first‐year students at university. Specifically, multiple linear regression models were used to identify such predictors of academic success. We report that, for all of the analyzed science degrees, the best predictor of academic success is high school grade point average. In addition, we obtained predictive models for estimating the value of the new academic performance indicator. Using these models, we can predict future academic success, which may help identify students at risk of failure at the beginning of the course. This in turn would ensure early implementation of educational interventions or strategies to increase academic achievement of such students.

In this paper we give structure theorems for the elements of the ZEMANIAN spaces SP and Also, bounded sets and convergent sequences in pP,o are characterized through representations as derivatives of measurable functions. Finally, we analyze the HANKEL convolution on the above spaces. 1.Math. Nachr. 160 (1993) 278 vestigate the structure of the members of &,a. Finally we characterize bounded sets and convergent sequences in /3h,o through representations of their elements. J. de SOUSA PINTO 11 11 started to investigate the generalized HANKEL convolution. He defined in spaces of distributions the convolution already introduced by F. M. CHOLEWINSKI [l] and I. 1. HIRSCHMAN [6]. Recently [9], the authors have improved the results of J. de SOUSA PINTO by extending the class of generalized functions on which the HANKEL convolution is defined. In Sections 3 and 4 of this work we study the HANKEL convolution on p, and &, respectively.Throughout this paper C will always denote a suitable positive constant (not necessarily the same in each occurrence). Also, to simplify the writing we introduce the function b,(z) = z-'J,(z) ( z E I). The spaces and fl,, and their dualsThe spaces p,,; and 8, were defined by A. H. ZEMANIAN [ 141. For every p E IR and a > 0, the space /3,,,o is constituted by all those smooth functions 4 = 4 ( x ) on I such that 4(x) = 0, for x 2 a, and When endowed with the topology generated by the family of seminorms { Y ; }~~~, becomes a FRECHET space. It is clear that Brsa c fic,b provided that a 5 b. This fact allows to define p, = u /3r,o as the inductive limit of {/3,,,o)o>o. Then fi, is a dense Now, we introduce on fi,,,a new families of seminorms which generate on pp,o the Let 1 I p < 03 and r E N. For every 4 E pp,a, we define subspace of X,. a > O same topology as {Y;}k.N. Proposition 2.1. Let a > 0 and 1 I p I 03. IJ ~E I R respectively p 2system of seminorms { 11 . l l , , , p, , }, EN (respectively {I . I p, p, r } , EN) generates on fic:a the same topology as {YfilLN.