256 research outputs found
Tricalcium phosphate endosseous implants in dentistry: ultrastructural findings
ÎČ-Tricalcium phosphate magnesium substitued (ÎČ-TCMP), consisting of one part small unsintered and one part large sintered granules was placed in upper and lower jaw surgical cavities of monkeys. At light and transmission electron microscope the biopsies taken at 2, 4, 8 and 24 weeks showed that both sintered and unsintered granules were well tolerated by the host tissue and result biodegradable over time.ÎČ-TCMP may stimulate the direction of bone growth enhancing osteoblasts activity and new bone deposition in direct contact and in the micropores of the biomaterial. ÎČ-TCMP containing Mg ions reabsorbs slowly when in sintered granules form and rapidly as unsintered granules. When it is placed in bone cavities, if bone reabsorption is biologically necessary, the biomaterial can be reabsorbed with bone, while if osteogenesis is required ÎČ-TCMP provides a more durable matrix to support new bone growth.Le ÎČ-phosphate tricalcique contenant Ă ions Mg (ÎČ-TCMP) et constituĂ© Ă parts Ă©gales de fins granules non frittĂ©s et de larges granules frittĂ©s, est introduit dans des cavitĂ©s chirurgicales pratiquĂ©es dans les maxillaires supĂ©rieurs et infĂ©rieurs de singes.Des biopsies pratiquĂ©es Ă 2, 4, 8 et 24 semaines ont Ă©tĂ© examinĂ©es au microscope optique et Ă©lectronique Ă transmission.Les granules frittĂ©s et non frittĂ©s sont bien tolĂ©rĂ©s par les tissus hĂŽtes et sont biodĂ©gradĂ©s avec le temps.Les observations histologiques montrent aussi que le ÎČ-TCMP peut orienter la direction de la croissance osseuse en stimulant lâactivitĂ© des ostĂ©oblastes et le dĂ©pĂŽt dâos nouveau aussi bien autour des biomatĂ©riaux que dans leur micropores. Le ÎČ-TCMP contenant les ions Mg est rĂ©absorbĂ© lentement lorsquâil se prĂ©sente sous la forme de granules frittĂ©s, et rapidement lorsquâil est sous la forme de granules non frittĂ©s.Lorsquâil est introduit dans les cavitĂ©s osseuses, si la rĂ©absorption osseuse est biologiquement nĂ©cessaire, le biomatĂ©riau peut ĂȘtre rĂ©absorbĂ© avec lâos, tandis que si câest lâostĂ©ogenĂšse qui est sollicitĂ©e, ÎČ-TCMP fournit une matrice durable comme support Ă la croissance dâos nouveau
Probability density functions of photochemicals over a coastal area of Northern Italy
The present paper surveys the findings of experimental studies and analyses of statistical probability density functions (PDFs) applied to air pollutant concentrations to provide an interpretation of the ground-level distributions of photochemical oxidants in the coastal area of Ravenna (Italy). The atmospheric pollution data set was collected from the local environmental monitoring network for the period 1978-1989. Results suggest that the statistical distribution of surface ozone, once normalised over the solar radiation PDF for the whole measurement period, follows a log-normal law as found for other pollutants. Although the Weibull distribution also offers a good fit of the experimental data, the areaâs meteorological features seem to favour the former distribution once the statistical index estimates have been analysed. Local transport phenomena are discussed to explain the data tail trends
Seasonal budgets of ozone and oxidant precursors in an industrial coastal area of northern Italy
The seasonal budgets and evolution of photochemical oxidants reported for greater Ravenna's urban-industrial area in the present study were calculated using the combined data from on-site systematic surveys (1978-1989) and from the monitoring network of the local environmental authorities. The notable differences in the concentrations of ozone and nitrogen oxides depended on season, and meteorological variables showed a marked correlation to the seasonal budget of trace constituents. The weak local circulation, the land-sea breeze system, and high solar radiation in summer, which may persist at length because of the anticyclonic conditions, can produce episodes of intense photochemical reactions. In winter, by contrast, low solar radiation and the absence of the breeze system results in very different evolutions of both pollutant concentrations and their seasonal budget
Topological mass mechanism and exact fields mapping
We present a class of mappings between models with topological mass mechanism
and purely topological models in arbitrary dimensions. These mappings are
established by directly mapping the fields of one model in terms of the fields
of the other model in closed expressions. These expressions provide the
mappings of their actions as well as the mappings of their propagators. For a
general class of models in which the topological model becomes the BF model the
mappings present arbitrary functions which otherwise are absent for
Chern-Simons like actions. This work generalizes the results of [1] for
arbitrary dimensions.Comment: 11 page
Synthesis of novel structural hybrids between aza-heterocycles and azelaic acid moiety with a specific activity on osteosarcoma cells
Nine compounds bearing pyridinyl (or piperidinyl, benzimidazolyl, benzotriazolyl) groups bound to an azelayl moiety through an amide bond were synthesized. The structural analogy with some histone deacetylase inhibitors inspired their syntheses, seeking new selective histone deacetylase inhibitors (HDACi). The azelayl moiety recalls part of 9-hydroxystearic acid, a cellular lipid showing antiproliferative activity toward cancer cells with HDAC as a molecular target. Azelayl derivatives bound to a benzothiazolyl moiety further proved to be active as HDACi. The novel compounds were tested on a panel of both normal and tumor cell lines. Non-specific induction of cytotoxicity was observed in the normal cell line, while three of them induced a biological effect only on the osteosarcoma (U2OS) cell line. One of them induced a change in nuclear shape and size. Cell-cycle alterations are associated with post-transcriptional modification of both H2/H3 and H4 histones. In line with recent studies, revealing unexpected HDAC7 function in osteoclasts, molecular docking studies on the active molecules predicted their proneness to interact with HDAC7. By reducing side effects associated with the action of the first-generation inhibitors, the herein reported compounds, thus, sound promising as selective HDACi
Renormalization of the mass gap
The full gluon propagator relevant for the description of the truly
non-perturbative QCD dynamics, the so-called intrinsically non-perturbative
gluon propagator has been derived in our previous work. It explicitly depends
on the regularized mass gap, which dominates its structure at small gluon
momentum. It is automatically transversal in a gauge invariant way. It is
characterized by the presence of severe infrared singularities at small gluon
momentum, so the gluons remain massless, and this does not depend on the gauge
choice. In this paper we have shown how precisely the renormalization program
for the regularized mass gap should be performed. We have also shown how
precisely severe infrared singularities should be correctly treated. This
allowed to analytically formulate the exact and gauge-invariant criteria of
gluon and quark confinement. After the renormalization program is completed,
one can derive the gluon propagator applicable for the calculation of physical
observables processes, etc., in low-energy QCD from first principles.Comment: 16 pages, no figures, no tables, some minor changes are introduce
Quantum control and the Strocchi map
Identifying the real and imaginary parts of wave functions with coordinates
and momenta, quantum evolution may be mapped onto a classical Hamiltonian
system. In addition to the symplectic form, quantum mechanics also has a
positive-definite real inner product which provides a geometrical
interpretation of the measurement process. Together they endow the quantum
Hilbert space with the structure of a K\"{a}ller manifold. Quantum control is
discussed in this setting. Quantum time-evolution corresponds to smooth
Hamiltonian dynamics and measurements to jumps in the phase space. This adds
additional power to quantum control, non unitarily controllable systems
becoming controllable by ``measurement plus evolution''. A picture of quantum
evolution as Hamiltonian dynamics in a classical-like phase-space is the
appropriate setting to carry over techniques from classical to quantum control.
This is illustrated by a discussion of optimal control and sliding mode
techniques.Comment: 16 pages Late
On the symmetry of the vacuum in theories with spontaneous symmetry breaking
We review the usual account of the phenomena of spontaneous symmetry breaking
(SSB), pointing out the common misunderstandings surrounding the issue, in
particular within the context of quantum field theory. In fact, the common
explanations one finds in this context, indicate that under certain conditions
corresponding to the situation called SSB, the vacuum of the theory does not
share the symmetries of the Lagrangian. We explain in detail why this statement
is incorrect in general, and in what limited set of circumstances such
situation could arise. We concentrate on the case of global symmetries, for
which we found no satisfactory exposition in the existing literature, and
briefly comment on the case of gauge symmetries where, although insufficiently
publicized, accurate and complete descriptions exist. We briefly discuss the
implications for the phenomenological manifestations usually attributed to the
phenomena of spontaneous symmetry breaking, analyzing which might be affected
by our analysis and which are not. In particular we describe the mass
generation mechanism in a fully symmetric scheme (i.e., with a totally
symmetric vacuum), and briefly discuss the implications of this analysis to the
problem of formation of topological defects in the early universe
Geometrization of Quantum Mechanics
We show that it is possible to represent various descriptions of Quantum
Mechanics in geometrical terms. In particular we start with the space of
observables and use the momentum map associated with the unitary group to
provide an unified geometrical description for the different pictures of
Quantum Mechanics. This construction provides an alternative to the usual GNS
construction for pure states.Comment: 16 pages. To appear in Theor. Math. Phys. Some typos corrected.
Definition 2 in page 5 rewritte
Indole derivative interacts with estrogen receptor beta and inhibits human ovarian cancer cell growth
Ovarian cancer remains the leading cause of mortality among gynecological tumors. Estrogen receptor beta (ERÎČ) expression has been suggested to act as a tumor suppressor in epithelial ovarian cancer by reducing both tumor growth and metastasis. ERÎČ expression abnormalities represent a critical step in the development and progression of ovarian cancer: for these reasons, its reâexpression by genetic engineering, as well as the use of targeted ERÎČ therapies, still constitute an important therapeutic approach. 3â{[2âchloroâ1â(4âchlorobenzyl)â5âmethoxyâ6-methylâ1Hâindolâ3âyl]methylene}â5âhydroxyâ6âmethylâ1,3âdihydroâ2Hâindolâ2âone, referred to here as compound 3, has been shown to have cytostatic as well cytotoxic effects on various hormone-dependent cancer cell lines. However, the mechanism of its antiâcarcinogenic activity is not well understood. Here, we offer a possible explanation of such an effect in the human ovarian cancer cell line IGROV1. Chromatin binding protein assay and liquid chromatography mass spectrometry were exploited to localize and quantify compound 3 in cells. Molecular docking was used to prove compound 3 binding to ERÎČ. Mass spectrometryâbased approaches were used to analyze histone postâtranslational modifications. Finally, gene expression analyses revealed a set of genes regulated by the ERÎČ/3 complex, namely CCND1, MYC, CDKN2A, and ESR2, providing possible molecular mechanisms that underline the observed antiproliferative effects
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