4,049 research outputs found
Novel Molecular Mechanisms of Resistance to Somatostatin Analog Treatment in Pituitary Adenomas
__Abstract__
In this thesis we confirmed the pivotal role of somatostatin receptor (SSTR) subtype 2 (sst2) receptor expression in driving the biochemical responsiveness to “classical” somatostatin analog (SSA) treatment in GH-secreting adenomas.
Moreover, since the variable expression of SSTRs in pituitary adenomas has been proposed as another factor affecting SSA efficacy, we showed that sst2 and sst5 are co-expressed in TSH-secreting adenomas. Differently from GH-secreting adenomas, TSHoma patients with high tumor sst5/sst2 mRNA ratio showed a good biochemical response to long-term SSA treatment. This difference between TSH- and GH-secreting adenomas points out the concept of cell type specificity.
Furthermore, for the first time, we characterized the expression of GRK2 and, in particular, of Ăź-arrestins in different pituitary adenoma histotypes. Indeed, these molecules have been highlighted to play a pivotal role in the SSTR desensitization and trafficking processes. We highlighted the important role of these molecules as determinants of tumor responsiveness to SSA treatment in GH-secreting adenomas, both in vitro and in vivo.
As far as ACTH-secreting adenomas, by use of the AtT20 cell line, w
Effective Lagrangian for Heavy and Light Mesons: Semileptonic Decays
We introduce an effective lagrangian including negative and positive parity
heavy mesons containing a heavy quark, light pseudoscalars, and light vector
resonances, with their allowed interactions, using heavy quark spin-flavour
symmetry, chiral symmetry, and the hidden symmetry approach for light vector
resonances. On the basis of such a lagrangian, by considering the allowed weak
currents and by including the contributions from the nearest unitarity poles we
calculate the form factors for semileptonic decays of and mesons into
light pseudoscalars and light vector resonances. The available data, together
with some additional assumptions, allow for a set of predictions in the
different semileptonic channels, which can be compared with those following
{}from different approaches. A discussion of non-dominant terms in our
approach, which attempts at including a rather complete dynamics, will however
have to wait till more abundant data become available.Comment: LaTeX (style article), 19 pages, UGVA-DPT 1992/11-790, BARI-TH/92-12
Hot Quark Matter with an Axial Chemical Potential
We analyze the phase diagram of hot quark matter in presence of an axial
chemical potential, . The latter is introduced to mimic the chirality
transitions induced, in hot Quantum Chromodynamics, by the strong sphaleron
configurations. In particular, we study the curvature of the critical line at
small , the effects of a finite quark mass and of a vector interaction.
Moreover, we build the mixed phase at the first order phase transition line,
and draw the phase diagram in the chiral density and temperature plane. We
finally compute the full topological susceptibility in presence of a background
of topological charge.Comment: 12 pages, 7 figures. Few references added, short discussion included.
Final version appearing on Phys. Rev.
Analysis of Narrow s-channel Resonances at Lepton Colliders
The procedures for studying a single narrow s-channel resonance or nearly
degenerate resonances at a lepton collider, especially a muon collider, are
discussed. In particular, we examine four methods for determining the
parameters of a narrow s-channel resonance: scanning the resonance, measuring
the convoluted cross section, measuring the Breit-Wigner area, and sitting on
the resonance while varying the beam energy resolution. This latter procedure
is new and appears to be potentially very powerful. Our focus is on computing
the errors in resonance parameters resulting from uncertainty in the beam
energy spread. Means for minimizing these errors are discussed. The discussion
is applied to the examples of a light SM-Higgs, of the lightest pseudogoldstone
boson of strong electroweak breaking, and of the two spin-1 resonances of the
Degenerate BESS model (assuming that the beam energy spread is less than their
mass splitting). We also examine the most effective procedures for nearly
degenerate resonances, and apply these to the case of Degenerate BESS
resonances with mass splitting of order the beam energy spread.Comment: 63 pages, 16 figure
A Strong Electroweak Sector at Future mu^+ mu^- Colliders
We discuss the prospects for detecting at a muon collider the massive new
vector resonances V and light pseudo-Nambu-Goldstone bosons P of a typical
strongly interacting electroweak sector (as represented by the BESS model).
Expected sensitivities to V's at a high energy collider are evaluated and the
excellent prospects for discovering P's via scanning at a low energy collider
are delineated.Comment: LaTeX, uses aipproc.cls, aipproc.sty, 10 pages, 6 figures, presented
at the Workshop on Physics at the First Muon Collider, Fermilab, November
1997, to appear in the Proceedings, some references added and minor changes
in the tex
Electromagnetic analysis and performance comparison of fully 3D-printed antennas
In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts
A complex relationship between immunity and metabolism in Drosophila diet-induced insulin resistance
Monitoring within-field variability of corn yield using sentinel-2 and machine learning techniques
Monitoring and prediction of within-field crop variability can support farmers to make the right decisions in different situations. The current advances in remote sensing and the availability of high resolution, high frequency, and free Sentinel-2 images improve the implementation of Precision Agriculture (PA) for a wider range of farmers. This study investigated the possibility of using vegetation indices (VIs) derived from Sentinel-2 images and machine learning techniques to assess corn (Zea mays) grain yield spatial variability within the field scale. A 22-ha study field in North Italy was monitored between 2016 and 2018; corn yield was measured and recorded by a grain yield monitor mounted on the harvester machine recording more than 20,000 georeferenced yield observation points from the study field for each season. VIs from a total of 34 Sentinel-2 images at different crop ages were analyzed for correlation with the measured yield observations. Multiple regression and two different machine learning approaches were also tested to model corn grain yield. The three main results were the following: (i) the Green Normalized Difference Vegetation Index (GNDVI) provided the highest R2 value of 0.48 for monitoring within-field variability of corn grain yield; (ii) the most suitable period for corn yield monitoring was a crop age between 105 and 135 days from the planting date (R4-R6); (iii) Random Forests was the most accurate machine learning approach for predicting within-field variability of corn yield, with an R2 value of almost 0.6 over an independent validation set of half of the total observations. Based on the results, within-field variability of corn yield for previous seasons could be investigated from archived Sentinel-2 data with GNDVI at crop stage (R4-R6)
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