Contact complete integrability

Complete integrability in a symplectic setting means the existence of a Lagrangian foliation leaf-wise preserved by the dynamics. In the paper we describe complete integrability in a contact set-up as a more subtle structure: a flag of two foliations, Legendrian and co-Legendrian, and a holonomy-invariant transverse measure of the former in the latter. This turns out to be equivalent to the existence of a canonical $\R\ltimes \R^{n-1}$ structure on the leaves of the co-Legendrian foliation. Further, the above structure implies the existence of $n$ contact fields preserving a special contact 1-form, thus providing the geometric framework and establishing equivalence with previously known definitions of contact integrability. We also show that contact completely integrable systems are solvable in quadratures. We present an example of contact complete integrability: the billiard system inside an ellipsoid in pseudo-Euclidean space, restricted to the space of oriented null geodesics. We describe a surprising acceleration mechanism for closed light-like billiard trajectories

The quality of sliced carrots affected by modified polyethylene foil and storage temperatures

The aim of this study was to examine the influence of different additive contents for oxygen absorption (5, 10 and 15%) in low-density polyethylene (PELD) plastic foils and storage temperatures (4 and 28 °C) on the quality and shelf-life of sliced carrots during storage. Quality and storage-life of packaged carrots slices were determined by observing changes of mass, total carotenoide pigments, microbial counts (mesophilic aerobic bacteria, enterobacteria, sulphite-reducing clostridia, yeast and moulds), sensory quality and texture by the use of penetrometer. The PELD foils modified with 10 and 15% of oxygen absorber (O2, CO2 and N2 permeability at 4 °C of around 700 ml m-2d-1atm-1) were the most suitable for the storage and prevention of deterioration of minimally processed carrots. Findings indicated that in these foils the best quality and shelf-life of carrot were maintained by 6 days of storage at 4 °C, without significant changes in parameters studied. The absorber for oxygen added to the foil had no influence on the permeability to CO2, O2and N2. The permeability of foils, which were used for carrot packaging increased by the increase of storage temperature to 28 °C and decreased by decreasing the temperature to 4 °C, and was not significantly affected by the additive content either. In the same time the diffusion constants of unused and used PELD foils for carrot packaging at 4 °C and 28 °C changed according to the change of film permeability during storage at those temperatures

On Nonperturbative Calculations in Quantum Electrodynamics

A new approach to nonperturbative calculations in quantum electrodynamics is proposed. The approach is based on a regular iteration scheme for solution of Schwinger-Dyson equations for generating functional of Green functions. The approach allows one to take into account the gauge invariance conditions (Ward identities) and to perform the renormalization program. The iteration scheme can be realized in two versions. The first one ("perturbative vacuum") corresponds to chain summation in the diagram language. In this version in four-dimensional theory the non-physical singularity (Landau pole) arises which leads to the triviality of the renormalized theory. The second version ("nonperturbative vacuum") corresponds to ladder summation and permits one to make non-perturbative calculations of physical quantities in spite of the triviality problem. For chiral-symmetrical leading approximation two terms of the expansion of the first-step vertex function over photon momentum are calculated. A formula for anomalous magnetic moment is obtained. A problem of dynamical chiral symmetry breaking (DCSB) is considered, the calculations are performed for renormalized theory in Minkowsky space. In the strong coupling region DCSB-solutions arise. For the renormalized theory a DCSB-solution is also possible in the weak coupling region but with a subsidiary condition on the value of $\alpha$.Comment: 31 pages, Plain LaTex, no figures. Journal version: some discussion and refs. are adde

Release of oxidizing fluids in subduction zones recorded by iron isotope zonation in garnet

Subduction zones are key regions of chemical and mass transfer between the Earth’s surface and mantle. During subduction, oxidized material is carried into the mantle and large amounts of water are released due to the breakdown of hydrous minerals such as lawsonite. Dehydration accompanied by the release of oxidizing species may play a key role in controlling redox changes in the subducting slab and overlying mantle wedge. Here we present measurements of oxygen fugacity, using garnet–epidote oxybarometry, together with analyses of the stable iron isotope composition of zoned garnets from Sifnos, Greece. We find that the garnet interiors grew under relatively oxidized conditions whereas garnet rims record more reduced conditions. Garnet δ56Fe increases from core to rim as the system becomes more reduced. Thermodynamic analysis shows that this change from relatively oxidized to more reduced conditions occurred during lawsonite dehydration. We conclude that the garnets maintain a record of progressive dehydration and that the residual mineral assemblages within the slab became more reduced during progressive subduction-zone dehydration. This is consistent with the hypothesis that lawsonite dehydration accompanied by the release of oxidizing species, such as sulfate, plays an important and measurable role in the global redox budget and contributes to sub-arc mantle oxidation in subduction zones

Placental Vesicles Carry Active Endothelial Nitric Oxide Synthase and Their Activity is Reduced in Preeclampsia.

Preeclampsia (PE), a multi-system hypertensive disorder of pregnancy, is associated 25 with increased systemic vascular resistance. Placentae from PE patients have 26 reduced levels of endothelial nitric oxide synthase (eNOS) and thus less nitric oxide 27 (NO). Syncytiotrophoblast extracellular vesicles (STBEV), comprised of microvesicles 28 (STBMV) and exosomes (STBEX), carry signals from the STB to the mother. We 29 hypothesized that STBEV bound eNOS (STBEV-eNOS), capable of producing NO, 30 are released into the maternal circulation. Dual-lobe ex vivo placental perfusion and 31 differential centrifugation was used to isolate STBEV from PE (n=8) and normal 32 pregnancies (NP) (n=11). Plasma samples of gestational age matched PE and NP 33 (n=6) were used to isolate circulating STBMV. STBEV expressed placental alkaline 34 phosphatase (PlAP), confirming placental origin. STBEV co-expressed eNOS, but not 35 iNOS, confirmed using Western blot, flow cytometry and immuno-depletion. STBEV-36 eNOS produced NO which was significantly inhibited by L-NAME (eNOS inhibitor, 37 *p<0.05), but not 1400W (iNOS inhibitor). STBEV-eNOS catalytic activity was 38 confirmed by visualising eNOS dimerization. STBEV-eNOS was more abundant in 39 uterine vein compared to peripheral blood, indicating placental origin. STBEV isolated 40 from PE perfused placentae had lower levels of STBEV-eNOS (STBMV; *p<0.05) and 41 overall lower NO activity (STBMV, ns; STBEX, *p<0.05) compared to NP. Circulating 42 plasma STBMV from PE women had lower STBEV-eNOS expression compared to NP 43 women (**p<0.01). This is the first observation of functional eNOS expressed on 44 STBEV from NP and PE placentae, as well as in plasma. The lower STBEV-eNOS 45 NO production seen in PE may contribute to the decreased NO bioavailability in this 46 disease

Population prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in the Netherlands. should asymptomatic persons be tested during Population-based chlamydia Screening also for gonorrhoea or only if chlamydial infection is found?

BACKGROUND: Screening and active case finding for Chlamydia trachomatis (CT) is recommended to prevent reproductive morbidity. However insight in community prevalence of gonococcal infections and co-infections with Neisseria gonorrhoea (NG) is lacking. METHODS: Nested study within a large population-based Chlamydia Screening Pilot among 21.000 persons 15–29 year. All CT-positive (166) and a random sample of 605 CT-negative specimens were as well tested for gonococcal infection. RESULTS: Overall Chlamydia prevalence in the Pilot was 2.0% (95% CI: 1.7–2.3), highest in very urban settings (3.2%; 95% CI: 2.4–4.0) and dependent of several risk factors. Four gonococcal infections were found among 166 participants with CT infection (4/166 = 2.4%; 95% CI: 0.1%–4.7%). All four had several risk factors and reported symptoms. Among 605 CT-negative persons, no infection with NG could be confirmed. CONCLUSION: A low rate of co-infections and a very low community prevalence of gonococcal infections were found in this population based screening programme among young adults in the Netherlands. Population screening for asymptomatic gonococcal infections is not indicated in the Netherlands. Although co-infection with gonorrhoea among CT-positives is dependent on symptoms and well-known algorithms for elevated risks, we advise to test all CT-positives also for NG, whether symptomatic or asymptomatic

Microvesicles Derived from Mesenchymal Stem Cells Enhance Survival in a Lethal Model of Acute Kidney Injury

Several studies demonstrated that treatment with mesenchymal stem cells (MSCs) reduces cisplatin mortality in mice. Microvesicles (MVs) released from MSCs were previously shown to favor renal repair in non lethal toxic and ischemic acute renal injury (AKI). In the present study we investigated the effects of MSC-derived MVs in SCID mice survival in lethal cisplatin-induced AKI. Moreover, we evaluated in vitro the effect of MVs on cisplatin-induced apoptosis of human renal tubular epithelial cells and the molecular mechanisms involved. Two different regimens of MV injection were used. The single administration of MVs ameliorated renal function and morphology, and improved survival but did not prevent chronic tubular injury and persistent increase in BUN and creatinine. Multiple injections of MVs further decreased mortality and at day 21 surviving mice showed normal histology and renal function. The mechanism of protection was mainly ascribed to an anti-apoptotic effect of MVs. In vitro studies demonstrated that MVs up-regulated in cisplatin-treated human tubular epithelial cells anti-apoptotic genes, such as Bcl-xL, Bcl2 and BIRC8 and down-regulated genes that have a central role in the execution-phase of cell apoptosis such as Casp1, Casp8 and LTA. In conclusion, MVs released from MSCs were found to exert a pro-survival effect on renal cells in vitro and in vivo, suggesting that MVs may contribute to renal protection conferred by MSCs