857 research outputs found

    The Minimal Length of a Lagrangian Cobordism between Legendrians

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    To investigate the rigidity and flexibility of Lagrangian cobordisms between Legendrian submanifolds, we investigate the minimal length of such a cobordism, which is a 11-dimensional measurement of the non-cylindrical portion of the cobordism. Our primary tool is a set of real-valued capacities for a Legendrian submanifold, which are derived from a filtered version of Legendrian Contact Homology. Relationships between capacities of Legendrians at the ends of a Lagrangian cobordism yield lower bounds on the length of the cobordism. We apply the capacities to Lagrangian cobordisms realizing vertical dilations (which may be arbitrarily short) and contractions (whose lengths are bounded below). We also study the interaction between length and the linking of multiple cobordisms as well as the lengths of cobordisms derived from non-trivial loops of Legendrian isotopies.Comment: 33 pages, 9 figures. v2: Minor corrections in response to referee comments. More general statement in Proposition 3.3 and some reorganization at the end of Section

    Erythrocyte antioxidant protection of rose hips (Rosa spp.)

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    Rose hips are popular in health promoting products as the fruits contain high content of bioactive compounds. The aim of this study was to investigate whether health benefits are attributable to ascorbic acid, phenols, or other rose-hip-derived compounds. Freeze-dried powder of rose hips was preextracted with metaphosphoric acid and the sample was then sequentially eluted on a C18 column. The degree of amelioration of oxidative damage was determined in an erythrocyte in vitro bioassay by comparing the effects of a reducing agent on erythrocytes alone or on erythrocytes pretreated with berry extracts. The maximum protection against oxidative stress, 59.4 ± 4.0% (mean standard deviation), was achieved when incubating the cells with the first eluted meta-phosphoric extract. Removal of ascorbic acid from this extract increased the protection against oxidative stress to 67.9 ± 1.9% . The protection from the 20% and 100% methanol extracts was 20.8 ± 8.2% and 5.0 ± 3.2% , respectively. Antioxidant uptake was confirmed by measurement of catechin by HPLC-ESI-MS in the 20% methanol extract. The fact that all sequentially eluted extracts studied contributed to protective effects on the erythrocytes indicates that rose hips contain a promising level of clinically relevant antioxidant protection

    Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

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    We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio and M\"ossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe

    Linking and causality in globally hyperbolic spacetimes

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    The linking number lklk is defined if link components are zero homologous. Our affine linking invariant alkalk generalizes lklk to the case of linked submanifolds with arbitrary homology classes. We apply alkalk to the study of causality in Lorentz manifolds. Let MmM^m be a spacelike Cauchy surface in a globally hyperbolic spacetime (Xm+1,g)(X^{m+1}, g). The spherical cotangent bundle STMST^*M is identified with the space NN of all null geodesics in (X,g).(X,g). Hence the set of null geodesics passing through a point xXx\in X gives an embedded (m1)(m-1)-sphere SxS_x in N=STMN=ST^*M called the sky of x.x. Low observed that if the link (Sx,Sy)(S_x, S_y) is nontrivial, then x,yXx,y\in X are causally related. This motivated the problem (communicated by Penrose) on the Arnold's 1998 problem list to apply link theory to the study of causality. The spheres SxS_x are isotopic to fibers of (STM)2m1Mm.(ST^*M)^{2m-1}\to M^m. They are nonzero homologous and lk(Sx,Sy)lk(S_x,S_y) is undefined when MM is closed, while alk(Sx,Sy)alk(S_x, S_y) is well defined. Moreover, alk(Sx,Sy)Zalk(S_x, S_y)\in Z if MM is not an odd-dimensional rational homology sphere. We give a formula for the increment of \alk under passages through Arnold dangerous tangencies. If (X,g)(X,g) is such that alkalk takes values in Z\Z and gg is conformal to gg' having all the timelike sectional curvatures nonnegative, then x,yXx, y\in X are causally related if and only if alk(Sx,Sy)0alk(S_x,S_y)\neq 0. We show that x,yx,y in nonrefocussing (X,g)(X, g) are causally unrelated iff (Sx,Sy)(S_x, S_y) can be deformed to a pair of Sm1S^{m-1}-fibers of STMMST^*M\to M by an isotopy through skies. Low showed that if (\ss, g) is refocussing, then MM is compact. We show that the universal cover of MM is also compact.Comment: We added: Theorem 11.5 saying that a Cauchy surface in a refocussing space time has finite pi_1; changed Theorem 7.5 to be in terms of conformal classes of Lorentz metrics and did a few more changes. 45 pages, 3 figures. A part of the paper (several results of sections 4,5,6,9,10) is an extension and development of our work math.GT/0207219 in the context of Lorentzian geometry. The results of sections 7,8,11,12 and Appendix B are ne

    Parallel cyclin E and cyclin A expression in neoplastic lesions of the uterine cervix

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    Cyclin E levels are high during late G1 and early S-phase in normal cells. The cyclin E expression over the cell cycle in tumours is not fully known. The impact on patient outcome by high cyclin E levels during other parts of the cell cycle than late G1- and early S-phase is unknown. We set out to study the expression of cyclin E over the cell cycle in cervical carcinomas. Using immunofluorescence staining of cyclin A, digital microscopy, and digital image analysis, we determined which cells in a tissue section that were in S- or G2-phase. M-phase cells were detected by morphology. By simultaneously staining for cyclin E, we investigated the variation in cyclin E levels over the cell cycle in cervical carcinoma lesions. In a case–control study, in which each deceased patient was matched with a patient still alive and well after >5 years of follow-up, we found that the deceased patients had a considerably higher fraction of cyclin A-positive cells staining for cyclin E than the survivors (n=36). We conclude that parallel cyclin E and cyclin A expression is an indicator for poor outcome in cervical carcinomas. In addition, we investigated the expression pattern of cyclin E and cyclin A in consecutive biopsy samples from cervical carcinomas at different stages, as well as in human papillomavirus positive or negative adenocarcinomas in order to further study the cyclin E and cyclin A expression pattern in neoplastic lesions of the uterine cervix

    The Hubble Space Telescope Key Project on the Extragalactic Distance Scale XXIV: The Calibration of Tully-Fisher Relations and the Value of the Hubble Constant

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    This paper presents the calibration of BVRIH$ Tully-Fisher relations based on Cepheid distances to 21 galaxies within 25 Mpc, and 23 clusters within 10,000 km/s. These relations have been applied to several distant cluster surveys in order to derive a value for the Hubble constant, H0, mainly concentrating on an I-band all-sky survey by Giovanelli and collaborators which consisted of total I magnitudes and 50% linewidth data for ~550 galaxies in 16 clusters. For comparison, we also derive the values of H0 using surveys in B-band and V-band by Bothun and collaborators, and in H-band by Aaronson and collaborators. Careful comparisons with various other databases from literature suggest that the H-band data, whose magnitudes are isophotal magnitudes extrapolated from aperture magnitudes rather than total magnitudes, are subject to systematic uncertainties. Taking a weighted average of the estimates of Hubble constants from four surveys, we obtain H0 = 71 +- 4 (random) +- 7 (systematic) km/s/Mpc. We have also investigated how various systematic uncertainties affect the value of H0 such as the internal extinction correction method used, Tully-Fisher slopes and shapes, a possible metallicity dependence of the Cepheid period-luminosity relation and cluster population incompleteness bias.Comment: 34 pages, 13 figure

    Nordic Innovative Trials to Evaluate osteoPorotic Fractures (NITEP) Collaboration: The Nordic DeltaCon Trial protocol-non-operative treatment versus reversed total shoulder arthroplasty in patients 65 years of age and older with a displaced proximal humerus fracture: a prospective, randomised controlled trial

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    Introduction The proximal humerus fracture (PHF) is one of the most common fractures in the elderly. The majority of PHFs are treated non-operatively, while 15%-33% of patients undergo surgical treatment. Recent randomised controlled trial (RCT) and meta-analyses have shown that there is no difference in outcome between non-operative treatment and locking plate or hemi-arthroplasty. During the past decade, reverse total shoulder arthroplasty (RTSA) has gained popularity in the treatment of PHF, although there is a lack of RCTs comparing RTSA to non-operative treatment.Methods This is a prospective, single-blinded, randomised, controlled, multicentre and multinational trial comparing RTSA with non-operative treatment in displaced proximal humeral fractures in patients 65-85 years. The primary outcome in this study is QuickDASH-score measured at 2 years. Secondary outcomes include visual analogue scale for pain, grip strength, Oxford shoulder score, Constant score and the number of reoperations and complications. The hypothesis of the trial is that operative treatment with RTSA produces better outcome after 2 and 5 years measured with QuickDASH.Ethics and dissemination In this protocol, we describe the design, method and management of the Nordic DeltaCon trial. The ethical approval for the trial has been given by the Regional Committee for Medical and Health Research Ethics, Norway. There have been several examples in orthopaedics of innovations that result in failure after medium-term follow-ups. In order to prevent such failures and to increase our knowledge of RSTA, we feel a large-scale study of the effects of the surgery on the outcome that focuses on the complications and reoperations is warranted. After the trial 2-year follow-up, the results will be disseminated in a major orthopaedic publication

    Fusion of secretory vesicles isolated from rat liver

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    Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences
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