119,295 research outputs found
Geometries arising from trilinear forms on low-dimensional vector spaces
No full textLet Gk(V) be the k-Grassmannian of a vector space V with dimV=n. Given a hyperplane H of Gk(V), we define in [I. Cardinali, L. Giuzzi, A. Pasini, A geometric approach to alternating k-linear forms, J. Algebraic Combin. doi: 10.1007/s10801-016-0730-6] a point-line subgeometry of PG(V) called the geometry of poles of H. In the present paper, exploiting the classification of alternating trilinear forms in low dimension, we characterize the possible geometries of poles arising for k=3 and n≤7 and propose some new constructions. We also extend a result of [J.Draisma, R. Shaw, Singular lines of trilinear forms, Linear Algebra Appl. doi: 10.1016/j.laa.2010.03.040] regarding the existence of line spreads of PG(5,K) arising from hyperplanes of G3(V)
Minimum distance of Orthogonal Line-Grassmann Codes in even characteristic
No full textIn this paper we determine the minimum distance of orthogonal line-Grassmann codes for q even. The case q odd was solved in "I. Cardinali, L. Giuzzi, K. Kaipa, A. Pasini, Line Polar Grassmann Codes of Orthogonal Type, J. Pure Applied Algebra (doi:10.1016/j.jpaa.2015.10.007 )" We also show that for q even all minimum weight codewords are equivalent and that symplectic line-Grassmann codes are proper subcodes of codimension 2n of the orthogonal ones
On orthogonal polar spaces
No full textLet be a non-degenerate polar space. In [I. Cardinali, L. Giuzzi, A.
Pasini, "The generating rank of a polar grassmannian", Adv. Geom. 21:4 (2021),
515-539 doi:10.1515/advgeom-2021-0022 (arXiv:1906.10560)] we introduced an
intrinsic parameter of , called the anisotropic gap, defined as the
least upper bound of the lengths of the well-ordered chains of subspaces of
containing a frame; when is orthogonal, we also defined two
other parameters of , called the elliptic and parabolic gap, related to
the universal embedding of .
In this paper, assuming is an orthogonal polar space, we prove that
the elliptic and parabolic gaps can be described as intrinsic invariants of
without making recourse to the embedding.Comment: 20 pages/revised versio
Line polar Grassmann codes of orthogonal type
No full textPolar Grassmann codes of orthogonal type have been introduced in I. Cardinali and L. Giuzzi, \emph{Codes and caps from orthogonal Grassmannians}, {Finite Fields Appl.} {\bf 24} (2013), 148-169. They are subcodes of the Grassmann code arising from the projective system defined by the Pl\"ucker embedding of a polar Grassmannian of orthogonal type. In the present paper we fully determine the minimum distance of line polar Grassmann Codes of orthogonal type for q odd
Line Polar Grassmann Codes of Orthogonal type
No full textPolar Grassmann codes of orthogonal type have been introduced in I. Cardinali and L. Giuzzi, \emph{Codes and caps from orthogonal Grassmannians}, {Finite Fields Appl.} {\bf 24} (2013), 148-169. They are subcodes of the Grassmann code arising from the projective system defined by the Pl\"ucker embedding of a polar Grassmannian of orthogonal type. In the present paper we fully determine the minimum distance of line polar Grassmann Codes of orthogonal type for q odd
Falcioni L, Gallotta MC, Baldari C, Cardinali L, Campanella M, Ferrari D, Guidetti L, Meucci M. Influence of training status on cardiac and vascular functioning in young recreational and competitive male rowers. Frontiers in Pediatrics, section Pediatric Cardiology
No full textIntroduction: The aim of the study was to investigate the influence of training
status on cardiovascular function in young male recreational and competitive
rowers.
Methods: Ejection duration in percentage to the heart rate period (ED%),
subendocardial viability ratio (SEVR), augmentation index at 75 bpm (AIx75) and
carotid to femoral pulse wave velocity (cf-PWV) of competitive rowers (CR) (age
17.6 ± 4.1 years), recreational rowers (RR) (age 16.7 ± 2.70 years) and athletes
practicing other recreational sports (ORS) (age 15.3 ± 1.4 years) were assessed.
Results: ED% was lower in CR compared to ORS (31.9 ± 3.9% vs. 38.4 ± 4.8%; p =
0.026) and cf-PWV was higher in CR compared to ORS (5.5 ± 1.0 m/s vs. 4.7 ±
0.5 m/s; p = 0.032). SEVR was higher in CR compared to RR and ORS (165.8 ±
33.7% vs. 127.4 ± 30.4% and 128.3 ± 27.8%; p = 0.022) and AIx75 was lower in CR
compared to RR and ORS (−15.7 ± 8.6% vs. 1.2 ± 9.9% and 1.5 ± 9.1; p = 0.001).
Discussion: Healthy, young competitive male rowers reported higher myocardial
performance and better cardiovascular health than recreational athletes.
Interpretations of cf-PWV in competitive rowers should be performed alongside
other cardiovascular indicators
Recensione a : C. Santini, I frammenti di L. Cassio Emina. Introduzione, testo, traduzione e commento, Pisa 1995, pp. 225.
No full textIl contributo ha per oggetto la recensione al volume dedicato da Carlo Santini ai frammenti di L. Cassio Emina. Nel mettere in luce i vari pregi dell'ampio ed articolato lavoro di Santini, vengono tuttavia avanzate riserve circa l'estensione dell'opera di Emina prospettata da Santini, mentre rispetto alla traduzione, di cui si rileva la sostanziale puntualità, ed al commento, di cui si mostra la ricchezza e l'esaustività, vengono evidenziate talune lievi inesattezze ed alcuni passaggi, in cui l'argomentazione svolta desta qualche perplessità
Some results on caps and codes related to orthogonal Grassmannians --- a preview
No full textIn this note we offer a short summary of some recent
results, to be contained in a
forthcoming paper \cite{CG}, on projective caps and linear
error correcting codes arising from the Grassmann embedding
of an orthogonal Grassmannian More precisely, we consider the codes arising from the projective system determined by
and determine some of their parameters.
We also investigate special sets of points of which are met
by any line of in at most points proving that their image under the Grassmann embedding is a projective cap
Implementing line-Hermitian Grassmann codes
No full textIn [6] we introduced line Hermitian Grassmann codes and determined their parameters. The aim of this paper is to present (in the spirit of [4]) an algorithm for the point enumerator of a line Hermitian Grassmannian which can be usefully applied to get efficient encoders, decoders and error correction algorithms for the aforementioned codes
Codes and caps from orthogonal Grassmannians
No full textIn this paper we investigate linear error correcting codes and
projective caps related to the Grassmann embedding of an
orthogonal Grassmannian. In particular, we determine some of
the parameters of the codes arising from the projective system
determined by such an embedding. We also study special sets of points of
which are met by any line of k in subsets of cardinality at most 2 and
we show that their image under the Grassmann embedding is
a projective cap
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