787 research outputs found
Non-commutative geometry and irreversibility
A kinetics built upon -calculus, the calculus of discrete dilatations, is
shown to describe diffusion on a hierarchical lattice. The only observable on
this ultrametric space is the "quasi-position" whose eigenvalues are the levels
of the hierarchy, corresponding to the volume ofphase space available to the
system at any given time. Motion along the lattice of quasi-positions is
irreversible.Comment: 15 pages, 2 figures, Revtex formatte
The Wigner function associated to the Rogers-Szego polynomials
We show here that besides the well known Hermite polynomials, the q-deformed
harmonic oscillator algebra admits another function space associated to a
particular family of q-polynomials, namely the Rogers-Szego polynomials. Their
main properties are presented, the associated Wigner function is calculated and
its properties are discussed. It is shown that the angle probability density
obtained from the Wigner function is a well-behaved function defined in the
interval [-Pi,Pi), while the action probability only assumes integer values
greater or equal than zero. It is emphasized the fact that the width of the
angle probability density is governed by the free parameter q characterizing
the polynomial.Comment: 12 pages, 2 (mathemathica) figure
Theories of violation of statistics
I discuss theories of violations of statistics, including intermediate
statistics, parastatistics, parons, and quons. I emphasize quons, which allow
small violations of statistics. I analyze the quon algebra and its
representations, implications of the algebra including the observables allowed
by the superselection rule separating inequivalent representations of the
symmetric group, the conservation of statistics rules, and the rule for
composite systems of quons. I conclude by raising the question of possible
origins of violations of statistics and of the level at which violations should
be expected if they exist.Comment: 16 pages, talk given at the International Conference on the
Spin-Statistics Connection and Commutation Relations: Experimental Tests and
Theoretical Implications, Capri, Italy, May 31-June 4, 2000. Dedication
added. Minor misprints correcte
Low impact weight-bearing exercise in an upright posture achieves greater lumbopelvic stability than overground walking
The aim of this study was to determine the kinematic differences between movements on a new exercise device (EX) that promotes a stable trunk over a moving, unstable base of support, and overground walking (OW). Sixteen male participants performed EX and OW trials while their movements were tracked using a 3D motion capture system. Trunk and pelvis range of motion (ROM) were similar between EX and OW in the sagittal and frontal planes, and reduced for EX in the transverse plane. The pelvis was tilted anteriorly, on average, by about 16 degrees in EX compared to OW. Hip and knee ROM were reduced in EX compared to OW. The exercise device appears to promote similar or reduced lumbopelvic motion, compared to walking, which could contribute to more tonic activity of the local lumbopelvic musculature
Loss of TRAIL-receptors is a recurrent feature in pancreatic cancer and determines the prognosis of patients with no nodal metastasis after surgery.
Agonistic antibodies targeting TRAIL-receptors 1 and 2 (TRAIL-R1 and TRAIL-R2) are being developed as a novel therapeutic approach in cancer therapy including pancreatic cancer. However, the cellular distribution of these receptors in primary pancreatic cancer samples has not been sufficiently investigated and no study has yet addressed the issue of their prognostic significance in this tumor entity.
Applying tissue microarray (TMA) analysis, we performed an immunohistochemical assessment of TRAIL-receptors in surgical samples from 84 consecutive patients affected by pancreatic adenocarcinoma and in 26 additional selected specimens from patients with no lymph nodes metastasis at the time of surgery. The prognostic significance of membrane staining and staining intensity for TRAIL-receptors was evaluated.
The fraction of pancreatic cancer samples with positive membrane staining for TRAIL-R1 and TRAIL-R2 was lower than that of cells from surrounding non-tumor tissues (TRAIL-R1: p<0.001, TRAIL-R2: p = 0.006). In addition, subgroup analyses showed that loss of membrane staining for TRAIL-R2 was associated with poorer prognosis in patients without nodal metastases (multivariate Cox regression analysis, Hazard Ratio: 0.44 [95% confidence interval: 0.22-0.87]; p = 0.019). In contrast, analysis of decoy receptors TRAIL-R3 and -R4 in tumor samples showed an exclusively cytoplasmatic staining pattern and no prognostic relevance.
This is a first report on the prognostic significance of TRAIL-receptors expression in pancreatic cancer showing that TRAIL-R2 might represent a prognostic marker for patients with early stage disease. In addition, our data suggest that loss of membrane-bound TRAIL-receptors could represent a molecular mechanism for therapeutic failure upon administration of TRAIL-receptors-targeting antibodies in pancreatic cancer. This hypothesis should be evaluated in future clinical trials
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