5,815 research outputs found
Two distance-regular graphs
We construct two families of distance-regular graphs, namely the subgraph of
the dual polar graph of type B_3(q) induced on the vertices far from a fixed
point, and the subgraph of the dual polar graph of type D_4(q) induced on the
vertices far from a fixed edge. The latter is the extended bipartite double of
the former
Some locally Kneser graphs
The Kneser graph is the graph on the -subsets of an -set,
adjacent when disjoint. Clearly, is locally . Hall showed
for that there are no further examples. Here we give other
examples of locally graphs for , and some further sporadic
examples. It follows that Hall's bound is best possible
Measuring the unmeasurable: a country's non-R and D expenditure on product and service innovation
Knowledge about non-R and D expenditure on innovation activities such as patenting and licensing, design, trial production, tooling-up, manpower training,market research and investment in fixed assets, is still extremely sparse. Questions about the latter were very poorly answered in the recent CommunityInnovation Survey (CIS). With the aid of information regarding the quality of replies, we estimate missing values and then reach a national estimate of1992 innovation expenditure in the manufacturing and service industries of the Netherlands. For policy discussions as well as for modelling, it isinteresting to note that expenditure on product-related R and D (6,24 billion guilders) represents about 26% of total product (and service) innovationexpenditure, the latter including 125 billion guilders for investment in fixed assets
Near polygons and Fischer spaces
In this paper we exploit the relations between near polygons with lines of size 3 and Fischer spaces to classify near hexagons with quads and with lines of size three. We also construct some infinite families of near polygons
On the Veldkamp Space of GQ(4, 2)
The Veldkamp space, in the sense of Buekenhout and Cohen, of the generalized
quadrangle GQ(4, 2) is shown not to be a (partial) linear space by simply
giving several examples of Veldkamp lines (V-lines) having two or even three
Veldkamp points (V-points) in common. Alongside the ordinary V-lines of size
five, one also finds V-lines of cardinality three and two. There, however,
exists a subspace of the Veldkamp space isomorphic to PG(3, 4) having 45 perps
and 40 plane ovoids as its 85 V-points, with its 357 V-lines being of four
distinct types. A V-line of the first type consists of five perps on a common
line (altogether 27 of them), the second type features three perps and two
ovoids sharing a tricentric triad (240 members), whilst the third and fourth
type each comprises a perp and four ovoids in the rosette centered at the
(common) center of the perp (90). It is also pointed out that 160 non-plane
ovoids (tripods) fall into two distinct orbits -- of sizes 40 and 120 -- with
respect to the stabilizer group of a copy of GQ(2, 2); a tripod of the
first/second orbit sharing with the GQ(2, 2) a tricentric/unicentric triad,
respectively. Finally, three remarkable subconfigurations of V-lines
represented by fans of ovoids through a fixed ovoid are examined in some
detail.Comment: 6 pages, 7 figures; v2 - slightly polished, subsection on fans of
ovoids and three figures adde
Andreev reflection from non-centrosymmetric superconductors and Majorana bound state generation in half-metallic ferromagnets
We study Andreev reflection at an interface between a half metal and a
superconductor with spin-orbit interaction. While the absence of minority
carriers in the half metal makes singlet Andreev reflection impossible, the
spin-orbit interaction gives rise to triplet Andreev reflection, i.e., the
reflection of a majority electron into a majority hole or vice versa. As an
application of our calculation, we consider a thin half metal film or wire
laterally attached to a superconducting contact. If the half metal is disorder
free, an excitation gap is opened that is proportional to the spin-orbit
interaction strength in the superconductor. For electrons with energy below
this gap a lateral half-metal--superconductor contact becomes a perfect triplet
Andreev reflector. We show that the system supports localized Majorana end
states in this limit.Comment: 14 pages, 3 figure
The effect of three years of TNF alpha blocking therapy on markers of bone turnover and their predictive value for treatment discontinuation in patients with ankylosing spondylitis: a prospective longitudinal observational cohort study
INTRODUCTION: The aim of this study was to investigate the effect of three years of tumor necrosis factor-alpha (TNF-alpha) blocking therapy on bone turnover as well as to analyze the predictive value of early changes in bone turnover markers (BTM) for treatment discontinuation in patients with ankylosing spondylitis (AS). METHODS: This is a prospective cohort study of 111 consecutive AS outpatients who started TNF-alpha blocking therapy. Clinical assessments and BTM were assessed at baseline, three and six months, as well as at one, two, and three years. Z-scores of BTM were calculated to correct for age and gender. Bone mineral density (BMD) was assessed yearly. RESULTS: After three years, 72 patients (65%) were still using their first TNF-alpha blocking agent. In these patients, TNF-alpha blocking therapy resulted in significantly increased bone-specific alkaline phosphatase, a marker of bone formation; decreased serum collagen-telopeptide (sCTX), a marker of bone resorption; and increased lumbar spine and hip BMD compared to baseline. Baseline to three months decrease in sCTX Z-score (HR: 0.394, 95% CI: 0.263 to 0.591), AS disease activity score (ASDAS; HR: 0.488, 95% CI: 0.317 to 0.752), and physician's global disease activity (HR: 0.739, 95% CI: 0.600 to 0.909) were independent inversely related predictors of time to treatment discontinuation because of inefficacy or intolerance. Early decrease in sCTX Z-score correlated significantly with good long-term response regarding disease activity, physical function and quality of life. CONCLUSIONS: Three years of TNF-alpha blocking therapy results in a bone turnover balance that favors bone formation, especially mineralization, in combination with continuous improvement of lumbar spine BMD. Early change in sCTX can serve as an objective measure in the evaluation of TNF-alpha blocking therapy in AS, in addition to the currently used more subjective measures
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