1,286 research outputs found
Generalised Unitarity for Dimensionally Regulated Amplitudes
We present a novel set of Feynman rules and generalised unitarity
cut-conditions for computing one-loop amplitudes via d-dimensional integrand
reduction algorithm. Our algorithm is suited for analytic as well as numerical
result, because all ingredients turn out to have a four-dimensional
representation. We will apply this formalism to NLO QCD corrections.Comment: Presented at SILAFAE 2014, 24-28 Nov, Ruta N, Medellin, Colombi
Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition
Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies
(V) were identified in ZnO nanorods (NRs) grown by low cost chemical bath
deposition. A transient behaviour in the photoluminescence (PL) intensity of
the two V states was found to be sensitive to the ambient environment and
to NR post-growth treatment. The largest transient was found in samples dried
on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for
the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV
exposure exhibited a transient behaviour in full agreement with the PL
transient indicating a clear role of atmospheric O on the surface defect
states. A model for surface defect transient behaviour due to band bending with
respect to the Fermi level is proposed. The results have implications for a
variety of sensing and photovoltaic applications of ZnO NRs
Impact of substrate defects on the equilibrium one-dimensional island size distribution
As long as only first-neighbour interactions are considered, equilibrium island size distributions of monoatomic islands in one dimension follow an exponential law regardless of the strength and the repulsive or attractive character of the adsorbate–adsorbate interactions. However, one- dimensional atomic wires obtained via nucleation at the step edges have a monomodal island size distribution. In this paper, we present a simple one- dimensional Monte Carlo model that shows how the monomodal distribution observed experimentally can be obtained by including surface defects that only suppress the interaction between two successive adsorbates.Fil: Mirabella, D. A.. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y TecnologÃa de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de IngenierÃa; ArgentinaFil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y TecnologÃa de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de IngenierÃa; Argentin
Influence of interface potential on the effective mass in Ge nanostructures
The role of the interface potential on the effective mass of charge carriers
is elucidated in this work. We develop a new theoretical formalism using a
spatially dependent effective mass that is related to the magnitude of the
interface potential. Using this formalism we studied Ge quantum dots (QDs)
formed by plasma enhanced chemical vapour deposition (PECVD) and co-sputtering
(sputter). These samples allowed us to isolate important consequences arising
from differences in the interface potential. We found that for a higher
interface potential, as in the case of PECVD QDs, there is a larger reduction
in the effective mass, which increases the confinement energy with respect to
the sputter sample. We further understood the action of O interface states by
comparing our results with Ge QDs grown by molecular beam epitaxy. It is found
that the O states can suppress the influence of the interface potential. From
our theoretical formalism we determine the length scale over which the
interface potential influences the effective mass
THE CHURCH OF SANT'ANDREA IN BERGAMO: AN INTEGRATED SURVEY FOR KNOWLEDGE AND CONSERVATION
Abstract. The church dedicated to Sant'Andrea (St. Andrew) in Porta Dipinta street in Bergamo city is a treasure that keep inside it a rich heritage of great historical and cultural value, both from the architectural and from the artistic point of view. Lacking of the façade (left unfinished), it is often neglected, despite being on the main road leading to the old town from Sant'Agostino Gate. The approach to an historical building like this requires a multi-disciplinary integration, in order to join the technical competence of engineering sciences to the sensitivity of human and fine arts sciences. For a better understanding of the structural performances of the building, historical research, measurement survey, material and decay condition study have to complement each other.</p
Aquaporins in health and disease: An overview focusing on the gut of different species
Aquaporins (AQPs) play a pivotal role in gut homeostasis since their distribution and
function is modulated both in physiological and in pathophysiological conditions. The transport of
water and solutes through gut epithelia is essential for osmoregulation and digestive and absorptive
functions. This passage is regulated by different AQP isoforms and characterized by their peculiar
distribution in the gastrointestinal tract. To date, AQP localization has been identified in the gut
and associated organs of several mammalian species by different techniques (immunohistochemical,
western blotting, and RT-PCR). The present review describes the modulation of AQP expression,
distribution, and function in gut pathophysiology. At the same time, the comparative description
of AQP in animal species sheds light on the full range of AQP functions and the screening of their
activity as transport modulators, diagnostic biomarkers, and drug targets. Moreover, the phenotype
of knockout mice for several AQPs and their compensatory role and the use of specific AQP inhibitors
have been also reviewed. The reported data could be useful to design future research in both basic
and clinical fields
Effects of castration on the immunoreactivity to NGF, BDNF and their receptors in the pelvic ganglia of the male rat
Nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) and are members of the neurotrophin family, a family of neurotrophic factors that also includes neurotrophin (NT) 3 and NT4/5. Neurotrophins have essential roles in the survival, development and differentiation of neurons in the central and peripheral nervous systems. Neurotrophins exert their effects by binding to corresponding receptors which are formed by the tyrosine protein kinases TrkA, TrkB and TrkC, and the low affinity neurotrophic receptor (p75NTR). In the present study, using immunohistochemistry and quantitative analysis, we have investigated immunoreactivity to BDNF, NGF, TrkB, p75NTR and TrkA in the pelvic ganglia of normal and castrated rats. Neurons of the pelvic ganglia expressed both these neurotrophins and their receptors. After castration the immunoreactivity persisted. However, the number of BDNF- and p75NTR–IR cells statistically significant decreased after castration. These results suggest that castration modulates the expression of neurotrophins and their receptors in pelvic autonomic neurons
Seismic reflection data in the Umbria Marche Region: limits and capabilities to unravel the subsurface structure in a seismically active area
Before seismic data were made available, the subsurface setting of the Umbria-Marche area was mainly derived
from the extrapolation of surface data and from models resulting from analogies with other mountain chains
around the world. During the ‘90s industrial seismic data availability considerably increased, allowing the definition
of new, previously unknown features. Beside the industrial seismic data availability, a deep crustal, near
vertical seismic section trending E-W was acquired (CROP-03) across the Italian peninsula from the Tyrrhenian
to the Adriatic coast. The subsurface data defined the compressional deformation style (thin- Vs thick- skinned)
and the extensional deformation style. A set of east-dipping low-angle-normal faults, which dissect the previous
compressional structures and which are the dominant features controlling the extension of the Apennines were
recognised. The subsequent application of the seismic data interpretation to seismotectonic issues, defined in
more detail the subsurface geometries of the active faults and the relationships between upper crust structure and
seismicity
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