Lo spazio dodecaedrico di Poincaré

Si descrive lo spazio di Poincaré tramite la sua descrizione come dodecaedro con identificazioni sul bordo. A tal proposito sono analizzate le proprietà di gruppo su S^3 (quaternioni) e le proprietà dei politopi regolari in 4 dimensioni. Infine sono calcolati gruppo fondamentale e omologia dello spazio, si dimostra che è una sfera d'omologia e vengono descritte le sue principali proprietà ponendo l'accento sull'importanza storica e matematica di questo spazio.

Il teorema di Poincaré sulla stabilità di orbite periodiche

In questa tesi si introduce l'analisi della stabilità delle orbite periodiche mostrandone un risultato fondamentale: il Teorema di Poinaré. A tal fine sono preliminarmente riportati alcune definizioni e risultati riguardanti la stabilità delle soluzioni e l'esistenza di soluzioni periodiche

Self-adjoint extensions for confined electrons: From a particle in a spherical cavity to the hydrogen atom in a sphere and on a cone

In a recent study of the self-adjoint extensions of the Hamiltonian of a particle confined to a finite region of space, in which we generalized the Heisenberg uncertainty relation to a finite volume, we encountered bound states localized at the wall of the cavity. In this paper, we study this situation in detail both for a free particle and for a hydrogen atom centered in a spherical cavity. For appropriate values of the self-adjoint extension parameter, the bound states localized at the wall resonate with the standard hydrogen bound states. We also examine the accidental symmetry generated by the Runge–Lenz vector, which is explicitly broken in a spherical cavity with general Robin boundary conditions. However, for specific radii of the confining sphere, a remnant of the accidental symmetry persists. The same is true for an electron moving on the surface of a finite circular cone, bound to its tip by a 1/r1/r potential.

Isolation of sphere-forming stem cells from the mouse inner ear

The mammalian inner ear has very limited ability to regenerate lost sensory hair cells. This deficiency becomes apparent when hair cell loss leads to hearing loss as a result of either ototoxic insult or the aging process. Coincidently, with this inability to regenerate lost hair cells, the adult cochlea does not appear to harbor cells with a proliferative capacity that could serve as progenitor cells for lost cells. In contrast, adult mammalian vestibular sensory epithelia display a limited ability for hair cell regeneration, and sphere-forming cells with stem cell features can be isolated from the adult murine vestibular system. The neonatal inner ear, however, does harbor sphere-forming stem cells residing in cochlear and vestibular tissues. Here, we provide protocols to isolate sphere-forming stem cells from neonatal vestibular and cochlear sensory epithelia as well as from the spiral ganglion. We further describe procedures for sphere propagation, cell differentiation, and characterization of inner ear cell types derived from spheres. Sphere-forming stem cells from the mouse inner ear are an important tool for the development of cellular replacement strategies of damaged inner ears and are a bona fide progenitor cell source for transplantation studies.

Cloud Computing in the EU Policy Sphere Interoperability, Vertical Integration and the Internal Market

Cloud computing is a new development that is based on the premise that data and applications are stored centrally and can be accessed through the Internet. Thisarticle sets up a broad analysis of how the emergence of clouds relates to European competition law, network regulation and electronic commerce regulation, which we relate to challenges for the further development of cloud services in Europe: interoperability and data portability between clouds; issues relating to vertical integration between clouds and Internet Service Providers; and potential problems for clouds to operate on the European Internal Market. We find that these issues are not adequately addressed across the legal frameworks that we analyse, and argue for further research into how to better facilitate innovative convergent services such as cloud computing through European policy – especially in light of the ambitious digital agenda that the European Commission has set out.

Modulus and Poincaré Inequalities on Non-Self-Similar Sierpiński Carpets

A carpet is a metric space homeomorphic to the Sierpiński carpet. We characterize, within a certain class of examples, non-self-similar carpets supporting curve families of nontrivial modulus and supporting Poincaré inequalities. Our results yield new examples of compact doubling metric measure spaces supporting Poincaré inequalities: these examples have no manifold points, yet embed isometrically as subsets of Euclidean space.

The Jews of Philadelphia : their history from the earliest settlements to the present time. A record of events and institutions, and of leading members of the Jewish community in every sphere of activity

Henry Samuel Morais

Cisplatin-resistant cells in malignant pleural mesothelioma cell lines show ALDH(high)CD44(+) phenotype and sphere-forming capacity

BACKGROUND Conventional chemotherapy in malignant pleural mesothelioma (MPM) has minimal impact on patient survival due to the supposed chemoresistance of cancer stem cells (CSCs). We sought to identify a sub-population of chemoresistant cells by using putative CSC markers, aldehyde dehydrogenase (ALDH) and CD44 in three MPM cell lines; H28, H2052 and Meso4. METHODS The Aldefluor assay was used to measure ALDH activity and sort ALDH(high) and ALDH(low) cells. Drug-resistance was evaluated by cell viability, anchorage-independent sphere formation, flow-cytometry and qRT-PCR analyses. RESULTS The ALDH(high) - and ALDH(low) -sorted fractions were able to demonstrate phenotypic heterogeneity and generate spheres, the latter being less efficient, and both showed an association with CD44. Cis- diamminedichloroplatinum (II) (cisplatin) treatment failed to reduce ALDH activity and conferred only a short-term inhibition of sphere generation in both ALDH(high) and ALDH(low) fractions of the three MPM cell lines. Induction of drug sensitivity by an ALDH inhibitor, diethylaminobenzaldehyde (DEAB) resulted in significant reductions in cell viability but not a complete elimination of the sphere-forming cells, suggestive of the presence of a drug-resistant subpopulation. At the transcript level, the cisplatin + DEAB-resistant cells showed upregulated mRNA expression levels for ALDH1A2, ALDH1A3 isozymes and CD44 indicating the involvement of these markers in conferring chemoresistance in both ALDH(high) and ALDH(low) fractions of the three MPM cell lines. CONCLUSIONS Our study shows that ALDH(high) CD44(+) cells are implicated in conveying tolerance to cisplatin in the three MPM cell lines. The combined use of CD44 and ALDH widens the window for identification and targeting of a drug-resistant population which may improve the current treatment modalities in mesothelioma.

Functionalization of PAMAM dendrimers with nitronyl nitroxide radicals as models for the outer-sphere relaxation in dentritic potential MRI contrast agents

PAMAM dendrimers functionalized with nitronyl nitroxide radicals were characterized. Quantitative determination of substitution with radicals was performed using EPR and electrochemical methods. The study of the 1H NMR relaxation of the surrounding water showed how the outer-sphere contribution to the relaxivity may be limited by the presence of the dendrimer core.

European Public Sphere

Political communication scholars have investigated whether a public sphere emerges that adapts to the new supra- and intergovernmental European reality in the course of European Union integration. Such European public sphere(s) might link EU politics to citizens. The entry discusses not only how such Europeanized public sphere might affect the quality of democracy as well as the political process but also what a European public sphere could look like and how we might measure it. Our empirical knowledge on the existence or nonexistence of a European Public Sphere is summarized in five theses. The article concludes with future paths for research.