94,020 research outputs found
Stochasticity effects in quantum radiation reaction
When an ultrarelativistic electron beam collides with a sufficiently intense
laser pulse, radiation-reaction effects can strongly alter the beam dynamics.
In the realm of classical electrodynamics, radiation reaction has a beneficial
effect on the electron beam as it tends to reduce its energy spread. Here, we
show that when quantum effects become important, radiation reaction induces the
opposite effect, i.e., the electron beam spreads out after interacting with the
laser pulse. We identify the physical origin of this opposite tendency in the
intrinsic stochasticity of photon emission, which becomes substantial in the
full quantum regime. Our numerical simulations indicated that the predicted
effects of the stochasticity can be measured already with presently available
lasers and electron accelerators.Comment: 5 pages, 2 figure
Anti-transpirant effects on vine physiology, berry and wine composition of cv. Aglianico (Vitis vinifera L.) Grown in South Italy
In viticulture, global warming requires reconsideration of current production models. At the base of this need there are some emerging phenomena: modification of phenological phases; acceleration of the maturation process of grapes, with significant increases in the concentration of sugar musts; decoupling between technological grape maturity and phenolic maturity. The aim of our study was to evaluate the effect of a natural anti-transpirant on grapevine physiology, berry, and wine composition of Aglianico cultivar. For two years, Aglianico vines were treated at veraison with the anti-transpirant Vapor Gard and compared with a control sprayed with only water. A bunch thinning was also applied to both treatments. The effectiveness of Vapor Gard were assessed through measurements of net photosynthesis and transpiration and analyzing the vegetative, productive and qualitative parameters. The results demonstrate that the application of antitranspirant reduced assimilation and transpiration rate, stomatal conductance, berry sugar accumulation, and wine alcohol content. No significant differences between treatments were observed for other berry and wine compositional parameters. This method may be a useful tool to reduce berry sugar content and to produce wines with a lower alcohol content
Constraining auto-interaction terms in α-attractor supergravity models of inflation
The inflationary mechanism has become the paradigm of modern cosmology over the last thirty years. However, there are several aspects of inflationary physics that are still to be addressed, like the shape of the inflationary potential. Regarding this, the so-called α-attractor models show interesting properties. In this work, the reconstruction of the effective potential around the global minimum of these particular potentials is provided, assuming a detection of permille-order for the tensor-to-scalar-ratio by forthcoming cosmic microwave background or gravitational waves experiments
Reconstruction of -attractor supergravity models of inflation
In this paper, we apply reconstruction techniques to recover the potential
parameters for a particular class of single-field models, the
-attractor (supergravity) models of inflation. This also allows to
derive the inflaton vacuum expectation value at horizon crossing. We show how
to use this value as one of the input variables to constrain the
postaccelerated inflationary phase. We assume that the tensor-to-scalar ratio
is of the order of , a level reachable by the expected
sensitivity of the next-generation CMB experiments.Comment: 10 pages, LaTeX, some typos correcte
Medical use of cannabis: italian and european legislation
This review illustrates some brief
considerations of the medical use of cannabis recently
issued in Italy. History and uses of cannabis
throughout centuries and different countries
are illustrated together with a description of botany
and active phytocannabinoids. Then, medical
use of cannabis anti-pain treatment for patients
resistant to conventional therapies is described
in case of chronic neuropathic pain, spasticity,
for anticinetosic and antiemetic effect in nausea
and vomiting caused by chemotherapy, for appetite
stimulating effect in cachexia, anorexia, loss
of appetite in cancer patients or patients with
AIDS and in anorexia nervosa, hypotensive effect
in glaucoma resistant to conventional therapies
and for reduction of involuntary body and facial
movements in Gilles de la Tourette syndrome.
Italian most recent legislation on medical cannabis
is detailed with some law proposals, also
showing the inconsistent legislation within European
Union. Some final considerations of future
studies are also reported
Distance Metric Learning using Graph Convolutional Networks: Application to Functional Brain Networks
Evaluating similarity between graphs is of major importance in several
computer vision and pattern recognition problems, where graph representations
are often used to model objects or interactions between elements. The choice of
a distance or similarity metric is, however, not trivial and can be highly
dependent on the application at hand. In this work, we propose a novel metric
learning method to evaluate distance between graphs that leverages the power of
convolutional neural networks, while exploiting concepts from spectral graph
theory to allow these operations on irregular graphs. We demonstrate the
potential of our method in the field of connectomics, where neuronal pathways
or functional connections between brain regions are commonly modelled as
graphs. In this problem, the definition of an appropriate graph similarity
function is critical to unveil patterns of disruptions associated with certain
brain disorders. Experimental results on the ABIDE dataset show that our method
can learn a graph similarity metric tailored for a clinical application,
improving the performance of a simple k-nn classifier by 11.9% compared to a
traditional distance metric.Comment: International Conference on Medical Image Computing and
Computer-Assisted Interventions (MICCAI) 201
Investigation of classical radiation reaction with aligned crystals
Classical radiation reaction is the effect of the electromagnetic field
emitted by an accelerated electric charge on the motion of the charge itself.
The self-consistent underlying classical equation of motion including
radiation-reaction effects, the Landau-Lifshitz equation, has never been tested
experimentally, in spite of the first theoretical treatments of radiation
reaction having been developed more than a century ago. Here we show that
classical radiation reaction effects, in particular those due to the near
electromagnetic field, as predicted by the Landau-Lifshitz equation, can be
measured in principle using presently available facilities, in the energy
emission spectrum of electrons crossing a
- thick diamond crystal in the axial channeling regime. Our
theoretical results indicate the feasibility of the suggested setup, e.g., at
the CERN Secondary Beam Areas (SBA) beamlines.Comment: 8 pages, 5 figure
Thermoelectric phenomena in disordered open quantum systems
Using a stochastic quantum approach, we study thermoelectric transport
phenomena at low temperatures in disordered electrical systems connected to
external baths. We discuss three different models of one-dimensional disordered
electrons, namely the Anderson model of random on-site energies, the
random-dimer model and the random-hopping model - also relevant for random-spin
models. We find that although the asymptotic behavior of transport in open
systems is closely related to that in closed systems for these noninteracting
models, the magnitude of thermoelectric transport strongly depends on the
boundary conditions and the baths spectral properties. This shows the
importance of employing theories of open quantum systems in the study of energy
transport.Comment: 5 pages, 2 figures, revised versio
Total thyroidectomy associated to chemotherapy in primary squamous cell carcinoma of the thyroid
Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare malignant disease with rapid fatal prognosis. The onset is generally characterized by sudden bilateral latero-cervical lymphadenopathy. The Authors report patient of 58-year-old who referred for evaluation of rapidly aggravating bilateral latero-cervical lymphadenopathy. The US highlighted the presence of a hypoechoic nodular lesion characterized by peri and intra-nodular vascularization. Multilayer CT showed diffused involvement of mediastinal and bilateral latero-cervical lymph nodes, with no evidence of primary pulmonary neoplasia or elsewhere. The patient underwent total thyroidectomy. The peri-isthmic tissue was removed due to the presence of a small roundish formation, that was due to lymph node metastasis at histological examination. Histological diagnosis: PSCCT. The immunohistochemical panel of the thyroid lesion was indispensable for the differential diagnosis between PSCCT, medullary carcinoma, anaplastic carcinoma, and thyroid metastasis of neoplasia with unknown primitiveness. The patient underwent chemotherapeutic treatment with Carboplatin and Paclitaxel with modest improvement of dysphagia symptoms and reduction of 10-15% of the target lesions. The clinical course was characterized by loco-regional progression of the disease with exitus in 10 months after diagnosis. Survival and quality of life after surgical therapy and chemotherapy were like that of patients undergoing only chemotherapy. Due to the extreme rarity of the neoplasia, 60 cases described in Literature, no exclusive guidelines are reported for PSCCT. More extensive case studies are needed to evaluate the effects of total thyroidectomy with intent R0/R1 on improving survival and quality of life of patients with PSCCT
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