Pimsner algebras and circle bundles

We report on the connections between noncommutative principal circle bundles, Pimsner algebras and strongly graded algebras. We illustrate several results with the examples of quantum weighted projective and lens spaces and theta-deformations.Comment: 24 pages. v3: Updated title. No changes in the scientific content and result

Pimsner algebras and Gysin sequences from principal circle actions

A self Morita equivalence over an algebra B, given by a B-bimodule E, is thought of as a line bundle over B. The corresponding Pimsner algebra O_E is then the total space algebra of a noncommutative principal circle bundle over B. A natural Gysin-like sequence relates the KK-theories of O_E and of B. Interesting examples come from O_E a quantum lens space over B a quantum weighted projective line (with arbitrary weights). The KK-theory of these spaces is explicitly computed and natural generators are exhibited.Comment: 29 pages. v2: Scientific content unchanged. Exposition improved. Added references. To appear in the JNc

The Gysin Sequence for Quantum Lens Spaces

We define quantum lens spaces as `direct sums of line bundles' and exhibit them as `total spaces' of certain principal bundles over quantum projective spaces. For each of these quantum lens spaces we construct an analogue of the classical Gysin sequence in K-theory. We use the sequence to compute the K-theory of the quantum lens spaces, in particular to give explicit geometric representatives of their K-theory classes. These representatives are interpreted as `line bundles' over quantum lens spaces and generically define `torsion classes'. We work out explicit examples of these classes.Comment: 27 pages. v2: No changes in the scientific content and results. Section 5 completely re-written and a final section added; suppressed two appendices; added references; minor changes throughout the paper. To appear in the JNc

Quantum lattice gauge fields and groupoid C*-algebras

We present an operator-algebraic approach to the quantization and reduction of lattice field theories. Our approach uses groupoid C*-algebras to describe the observables and exploits Rieffel induction to implement the quantum gauge symmetries. We introduce direct systems of Hilbert spaces and direct systems of (observable) C*-algebras, and, dually, corresponding inverse systems of configuration spaces and (pair) groupoids. The continuum and thermodynamic limit of the theory can then be described by taking the corresponding limits, thereby keeping the duality between the Hilbert space and observable C*-algebra on the one hand, and the configuration space and the pair groupoid on the other. Since all constructions are equivariant with respect to the gauge group, the reduction procedure applies in the limit as well.Comment: 23 pages, 6 figure

In-vivo effects of flapless osteopuncture-facilitated tooth movement in the maxilla and the mandible

This study aimed to investigate the effects of a minimally invasive, flapless procedure to enhance tooth movement in both jaws and to determine whether this triggers the acceleration when repeated monthly. The sample consisted of thirty-two individuals whose orthodontic treatment required canine retraction. They were divided into an experimental group and control group. Osteopunctures were performed using orthodontic mini-screws at the distal aspects of the canine teeth at the beginning and on the fourth week of distalization in the experimental group. The control group was treated with conventional mechanics. All canines were retracted. The rates of canine distalization, rotation, and tipping were measured on the first, fourth, and eighth weeks of distalization. First molar anchorage loss was also measured. Intergroup and intragroup analyses were performed. Flapless osteopuncture-facilitated tooth movement resulted in greater canine distalization and reduced molar movement in the maxilla in the experimental than in the control group during the first month of distalization. In addition, the extent of upper canine movement was significantly higher in the experimental group in the first month than in the second. No differences in canine and molar movement in the mandible were observed between the two groups. OP, as applied in this study, is an effective method for increasing the rate of tooth movement in the maxilla. Repeating the procedure monthly does not appear to show a major advance of tooth movement

Invadosomi e strutture di membrana sulle Mesodermal Progenitor Cells (MPCs): possibili implicazioni nella somministrazione di cellule multipotenti derivate da midollo osseo.

ABSTRACT Any promising clinical study concerning the use of MSCs is affected by intrinsic data variability given by the heterogeneity of culture procedures, which often compromise a definitive conclusion and comparison between different studies. Many critical parameters have impact of the composition of the cell preparations as serum supplementation, biomaterials and surface coating, as well as passaging. We recently demonstrated that by substituting human pooled AB serum for fetal bovine serum in culture medium it is possible to isolate bone marrow-derived mesodermal progenitor cell (MPC). MPCs are long-telomere cells expressing pluripotency-associated genes and are able to differentiate in early MSCs and endothelial cells. MPCs are often co-isolated in MSC cultures in different percentage and could represent one of the most influencing causes of results variability between studies on clinical applicability of cultured MSCs. Although, in the last years, many studies reported interesting data on tissue regeneration after local administration of cultured MSCs, systemic delivering of these cells has been the focus of interest in new emerging therapeutical approaches. Controversial data were reported about homing and tissue engraftment ability of systemically administered expanded MSCs and this is probably due to heterogeneity of the cell preparations. However, current studies showed that MSC homing is low and this inefficient process is compromised by entrapment of delivered cells into the lungs or liver. Here we present convincing data showing that MPC carry the cell surface machinery necessary to migrate toward the injured site or to the bone marrow and then engraft the tissue by trans-endothelial migration, similarly to leukocytes able of diapedesis. On the contrary MSCs don’t exhibit any morpho-funtional structure sustaining extravasation. Consequently, we hypothesize that reported low percentage of engrafted cells, after MSC systemic infusion is the expression of co-cultured MPC while MSCs were passively retained into filter organs as lungs, liver or spleen