46,316 research outputs found
Some remarks on flocks
No full textNew proofs are given of the fundamental results of Bader,
Lunardon and Thas relating flocks of the quadratic
cone in pg(3,q), q odd, and BLT-sets of Q(4,q). We also
show that there is a unique BLT-set of H(3,9). The model of
Penttila for Q(4,q) q odd, is extended to
Q(2m,q) to construct partial flocks of size qm/2+m/2-1 of the
cone K in pg(2m-1,q) with vertex a point and base
Q(2m-2,q) , where q is congruent to 1 or 3 modulo 8 and m
is even. These
partial flocks are larger than the largest previously known
for m>2 . Also, the
example of O'Keefe and Thas of a partial
flock of K in pg(5,3) of size 6 is generalised to a
partial flock of the cone K of pg(2pn-1,p) of size 2pn , for any prime p congruent to 1 or 3 modulo 8,
with the corresponding partial BLT-set of
Q(2pn,p) admitting the symmetric group of degree 2pn+1
Arcs and ovals in infinite K-clan geometry
No full textSi completa l'estensione ai campi infiniti delle problematiche legate alle geometrie di K-clan, discutendo la costruzione di archi e ovali (che generalizzano le herd) di PG(2,K) a partire da flock, anche parziali. Per ottenere tali costruzioni e' necessario fare alcune ipotesi addizionali sul campo (e.g. perfetto o full) che sono sempre soddisfatte dai campi finiti. Infine, si ottengono le ovali anche direttamente da opportuni sottoquadrangoli, come nel caso finito
Biomechanical signals and the C-type natriuretic peptide counteract catabolic activities induced by IL-1? in chondrocyte/agarose constructs
No full textIntroduction: The present study examined the effect of C-type natriuretic peptide (CNP) on the anabolic and catabolic activities in chondrocyte/agarose constructs subjected to dynamic compression. Methods: Constructs were cultured under free-swelling conditions or subjected to dynamic compression with low (0.1 to 100 pM) or high concentrations (1 to 1,000 nM) of CNP, interleukin-1? (IL-1?), and/or KT-5823 (inhibits cyclic GMP-dependent protein kinase II (PKGII)). Anabolic and catabolic activities were assessed as follows: nitric oxide (NO) and prostaglandin E2 (PGE2) release, and [3H]-thymidine and 35SO4 incorporation were quantified by using biochemical assays. Gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), aggrecan, and collagen type II were assessed with real-time quantitative PCR (qPCR). Two-way ANOVA and the post hoc Bonferroni-corrected t tests were used to examine data. Results: CNP reduced NO and PGE2 release and partially restored [3H]-thymidine and 35SO4 incorporation in constructs cultured with IL-1?. The response was dependent on the concentration of CNP, such that 100 pM increased [3H]-thymidine incorporation (P < 0.001). This is in contrast to 35SO4 incorporation, which was enhanced with 100 or 1000 nM CNP in the presence and absence of IL-1? (P < 0.001). Stimulation by both dynamic compression and CNP and/or the PKGII inhibitor further reduced NO and PGE2 release and restored [3H]-thymidine and 35SO4 incorporation. In the presence and absence of IL-1?, the magnitude of stimulation for [3H]-thymidine and 35SO4 incorporation by dynamic compression was dependent on the concentration of CNP and the response was inhibited with the PKGII inhibitor. In addition, stimulation by CNP and/or dynamic compression reduced IL-1?-induced iNOS and COX-2 expression and restored aggrecan and collagen type II expression. The catabolic response was not further influenced with the PKGII inhibitor in IL-1?-treated constructs. Conclusions: Treatment with CNP and dynamic compression increased anabolic activities and blocked catabolic effects induced by IL-1?. The anabolic response was PKGII mediated and raises important questions about the molecular mechanisms of CNP with mechanical signals in cartilage. Therapeutic agents like CNP could be administered in conjunction with controlled exercise therapy to slow the OA disease progression and to repair damaged cartilage. The findings from this research provide the potential for developing novel agents to slow the pathophysiologic mechanisms and to treat OA in the young and old. <br/
Holey Segre varieties
No full textgeneralizzando le varieta' di Segre (classiche), si introducono le varieta' di Segre "Holey", prodotto tensoriale di PG(n,q) e PG(m,q^k), fornendone una descrizione algebrica e studiandone la struttura geometrica. Inoltre, per particolari valori dei parametri, si prova che una varieta' di Segre holey ammette una partizione in varieta' di Segre classiche, e che alcune varieta' di Segre holey sono sottogeometrie non canoniche immerse in opportune varieta' di Segre
∑_(l+m=k,l,m≥0) ((α+l-1)¦l) ((β+m-1)¦m)=((α+β+k-1)¦k) and its application to negative binomial distribution
No full textWe prove here the following equation: ∑_(l+m=k,l,m≥0) ((α+l-1)¦l) ((β+m-1)¦m)=((α+β+k-1)¦k) and give its application to prove the reproductive property of the negative binomial distribution.
These finite sum equation involving binomial coefficients and proof of the reproductive property are not known as far as the author knows.論文(Article)departmental bulletin pape
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Biometrical and economical relationships between growth rate and feed consumption of steers
No full textData from the Gulf Coast Beef Cattle Pasture Research Station, Angleton, Texas and records collected by the author at the Beef Cattle facilities, Texas A&M University, College Station, Texas were included in this study. Preweaning and postweaning weights, sire and dam weights and feed consumption observations were taken on 59 steer calves of five different breed groups, namely; Hereford, Brahman, 3/4 Brahman-1/4 Hereford, 3/4 Hereford-1/4 Brahman and 1/2 Santa Gertrudis-1/4 Angus-1/8 Brahman-1/8 Hereford. Primary objectives of this study were to evaluate a method to estimate individual feed intake of group fed steers, to compute weight-age relationships and to estimate optimal slaughter weight from weight gain-feed intake and TDN/steer price relationships. A feeding arrangement similar to a balanced incomplete block design was introduced as a possible method to estimate individual feed consumption of group fed steers. ..
On the flocks of the quadratic cone
No full textSi dimostra che il piano di traslazione
costruito da M. L. Narayana Rao, K. Satyanarayana e G. Vithal Rao
[Discrete Math. 66 (1987), 175-190] e' il piano associato al
flock definito da W. M. Kantor per q=2 (mod.5) [Math. Z. 192
(1986), 45-50] e quindi i piani di Narayana Rao, Satyanarayana
e Vithal Rao sono derivati dei piani definiti da S. D. Cohen e M.
J. Ganley [Quart. J. Math. Oxford (2) 35 (1984), 101-113]
Arcs and ovals in infinite Kappa-clan geometry
No full textFor a finite field GF(q); to a q-clan of matrices there are associated generalized quadrangles, flocks of quadratic cones in PG(3, q), translation planes and, for q even, ovals in PG(2, q). The connections with generalized quadrangles, flocks and translation planes have recently been extended to the case of an infinite field K, under certain extra assumptions. In this note we extend the theory of ovals in PG(2, q) associated with q-clans, q even, to ovals in PG(2,K) associated with K-clans for (infinite) fields K of characteristic 2. Again, certain extra assumptions on the field K are made.Laura Bader, Christine M. O'Keef
Viscoelastic Cell Mechanics and actin remodelling are dependent on the rate of applied pressure
No full textBackground: living cells are subjected to external and internal mechanical stresses. The effects of these stresses on the deformation and subsequent biological response of the cells remains unclear. This study tested the hypothesis that the rate at which pressure (or stress) is applied influence the viscoelastic properties of the cell associated with differences in the dynamics of the actin cytoskeleton.Principal finding: micropipette aspiration was used to determine the instantaneous and equilibrium moduli and the viscosity of isolated chondrocytes based on the standard linear solid (SLS) model and a variation of this incorporating Boltzmann superposition. Cells were visualised for 180 seconds following aspiration to 7 cmH2O at 0.35, 0.70 and 5.48 cmH2O/sec. Cell recovery was then examined for a further 180 seconds once the pressure had been removed. Reducing the rate of application of pressure reduced the levels of cell deformation and recovery associated with a significant increase in modulus and viscosity. Using GFP transfection and confocal microscopy, we show that chondrocyte deformation involves distortion, disassembly and subsequent reassembly of the cortical actin cytoskeleton. At faster pressure rates, cell deformation produced an increase in cell volume associated with membrane bleb formation. GFP-actin transfection inhibited the pressure rate dependent variation in cell mechanics indicating that this behaviour is regulated by GFP-sensitive actin dynamics.Conclusion: we suggest that slower rates of aspiration pressure enable greater levels of cortical actin distortion. This is partially inhibited by GFP or faster aspiration rates leading to membrane bleb formation and an increase in cell volume. Thus the rate of application of pressure regulates the viscoelastic mechanical properties of living cells through pressure rate sensitive differences in actin dynamics. Therefore cells appear softer when aspirated at a faster rate in contrast to what is expected of a normal viscoelastic materia
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