1,721,621 research outputs found
Marriage record of Johnson, Andrew and Drew, Stella S.
No full textMarriage license for Andrew Johnson and Stella S. Drew. G.W. Sellers was the officiant
Polyhedral models for generalized associahedra via Coxeter elements
No full textMotivated by the theory of cluster algebras, F. Chapoton, S. Fomin, and
A. Zelevinsky associated to each finite type root system a simple convex polytope,
called generalized associahedron. They provided an explicit realization of this poly-
tope associated with a bipartite orientation of the corresponding Dynkin diagram.
In the first part of this paper, using the parametrization of cluster variables by their
g-vectors explicitly computed by S.-W. Yang and A. Zelevinsky, we generalize the
original construction to any orientation. In the second part we show that our construc-
tion agrees with the one given by C. Hohlweg, C. Lange, and H. Thomas in the setup
of Cambrian fans developed by N. Reading and D. Speyer
Intraoperative sentinel node detection by an innovative imaging probe.
No full textIntraoperative sentinel node detection by an innovative imaging probe.
Campisi C, Soluri A, Stella S, Valenti G, Scopinaro F.
SourceInstitute of Biomedical Technologies, National Research Council, Rome. [email protected]
Abstract
Intraoperative tumor detection has been used in many applications, and today the sentinel node technique is a widely employed surgical procedure in breast cancer. Different detector systems are employed but several problems have been reported in clinical practice, in particular the difficulty to accurately detect the sentinel node within the axillary soft tissue. The problem is even greater for abdominal and thoracic tumors. We propose an innovative Imaging Probe (IP) able to visualize on a monitor the primary tumor and secondary lesions if appropriately radiolabeled. The IP can be optimally applied for minimally invasive surgery in breast cancer treatment, and a preliminary experience related to 15 patients and 20 sentinel nodes is reported here. We compared the results obtained with the IP to those obtained with an Anger camera and a traditional scintillation detector, and found them to be very promising. In particular the surgeon's work is greatly facilitated by direct visual guidance instead of a generic acoustic signal.
PMID:12369557[PubMed - indexed for MEDLINE
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Diagrammatic description of c-vectors and d-vectors of cluster algebras of finite type to the memory of andrei zelevinsky
Full text linkWe provide an explicit Dynkin diagrammatic description of the c-vectors and
the d-vectors (the denominator vectors) of any cluster algebra of finite type with
principal coefficients and any initial exchange matrix. We use the surface realization
of cluster algebras for types An and Dn, then we apply the folding method to Dn+1
and A2n−1 to obtain types Bn and Cn. Exceptional types are done by direct inspec-
tion with the help of a computer algebra software. We also propose a conjecture on
the root property of c-vectors for a general cluster algebra
Dominance Regions for Rank Two Cluster Algebras
Full text linkWe study the polygons defining the dominance order on g-vectors in cluster algebras of rank 2 as in Fig. 1
Diagrammatic description of c-vectors and d-vectors of cluster algebras of finite type to the memory of andrei zelevinsky
Full text linkWe provide an explicit Dynkin diagrammatic description of the c-vectors and the d-vectors (the denominator vectors) of any cluster algebra of finite type with principal coefficients and any initial exchange matrix. We use the surface realization of cluster algebras for types An and Dn, then we apply the folding method to Dn+1 and A2n-1 to obtain types Bn and Cn. Exceptional types are done by direct inspection with the help of a computer algebra software. We also propose a conjecture on the root property of c-vectors for a general cluster algebra
An affine almost positive roots model
Full text linkWe generalize the almost positive roots model for cluster algebras
from finite type to a uniform finite/affine type model. We define a subset
Φc of the root system and a compatibility degree on Φc , given by a formula
that is new even in finite type. The clusters (maximal pairwise compatible
sets of roots) define a complete fan Fanc (Φ). Equivalently, every vector has
a unique cluster expansion. We give a piecewise linear isomorphism from the
subfan of Fanc (Φ) induced by real roots to the g-vector fan of the associated
cluster algebra. We show that Φc is the set of denominator vectors of the
associated acyclic cluster algebra and conjecture that the compatibility degree
also describes denominator vectors for non-acyclic initial seeds. We extend
results on exchangeability of roots to the affine case
Exchange relations for finite type cluster algebras with acyclic initial seed and principal coefficients
No full textWe give an explicit description of all the exchange relations in any finite type
cluster algebra with acyclic initial seed and principal coefficients
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