18,183 research outputs found
Message passing and Monte Carlo algorithms: connecting fixed points with metastable states
Mean field-like approximations (including naive mean field, Bethe and Kikuchi
and more general Cluster Variational Methods) are known to stabilize ordered
phases at temperatures higher than the thermodynamical transition. For example,
in the Edwards-Anderson model in 2-dimensions these approximations predict a
spin glass transition at finite . Here we show that the spin glass solutions
of the Cluster Variational Method (CVM) at plaquette level do describe well
actual metastable states of the system. Moreover, we prove that these states
can be used to predict non trivial statistical quantities, like the
distribution of the overlap between two replicas. Our results support the idea
that message passing algorithms can be helpful to accelerate Monte Carlo
simulations in finite dimensional systems.Comment: 6 pages, 6 figure
Helioseismology and the solar age
The problem of measuring the solar age by means of helioseismology hasbeen
recently revisited by Guenther & Demarque (1997) and by Weiss & Schlattl
(1998). Different best values for and different assessment of
the uncertainty resulted from these two works. We show that depending on the
way seismic data are used, one may obtain the value
Gy, close to the age of the oldest meteorites, Gy, like in
the first paper, or above 5 Gy like in the second paper. The discrepancy in the
seismic estimates of the solar age may be eliminated by assuming higher than
the standard metal abundance and/or an upward revision of the opacities in the
solar radiative interior.We argue that the most accurate and robust seismic
measure of the solar age are the small frequency separations,
, for spherical harmonic degrees
and radial orders .The seismic age inferred by
minimization of the sum of squared differences between the model and the solar
small separations is , a number consistent with
meteoritic data.Our analysis supports earlier suggestions of using small
frequency separations as stellar age indicators.Comment: 8 pages + 4 ps figures included, LaTeX file with l-aa.sty, submitted
to Astronomy and Astrophysic
Addressing Item-Cold Start Problem in Recommendation Systems using Model Based Approach and Deep Learning
Traditional recommendation systems rely on past usage data in order to
generate new recommendations. Those approaches fail to generate sensible
recommendations for new users and items into the system due to missing
information about their past interactions. In this paper, we propose a solution
for successfully addressing item-cold start problem which uses model-based
approach and recent advances in deep learning. In particular, we use latent
factor model for recommendation, and predict the latent factors from item's
descriptions using convolutional neural network when they cannot be obtained
from usage data. Latent factors obtained by applying matrix factorization to
the available usage data are used as ground truth to train the convolutional
neural network. To create latent factor representations for the new items, the
convolutional neural network uses their textual description. The results from
the experiments reveal that the proposed approach significantly outperforms
several baseline estimators
Strangeness Production in pp,pA,AA Interactions at SPS Energies.HIJING Approach
In this report we have made a systematic study of strangeness production in
proton-proton(pp),proton-nucleus(pA) and nucleus- nucleus(AA) collisions at
CERN Super Proton Synchroton energies, using \\ (version ). Numerical results for mean
multiplicities of neutral strange particles ,as well as their ratios to
negatives hadrons() for
p-p,nucleon-nucleon(N-N),\,\,p-S,\,\,p-Ag,\,\,p-Au('min. bias')collisions and
p-Au,\,\,S-S,\,\,S-Ag,\,\,S-Au ('central')collisions are compared to
experimental data available from CERN experiments and also with recent
theoretical estimations given by others models. Neutral strange particle
abundances are quite well described for p-p,N-N and p-A interactions ,but are
underpredicted by a factor of two in A-A interactions for
in symmetric collisions(S-S,\,\,Pb-Pb)and for
in asymmetric ones(S-Ag,\,\,S-Au,\,\,S-W). A
qualitative prediction for rapidity, transverse kinetic energy and transverse
momenta normalized distributions are performed at 200 GeV/Nucleon in
p-S,S-S,S-Ag and S-Au collisions in comparison with recent experimental data.
HIJING model predictions for coming experiments at CERN for S-Au, S-W and Pb-Pb
interactions are given. The theoretical calculations are estimated in a full
phase space.Comment: 33 pages(LATEX),18 figures not included,available in hard copy upon
request , Dipartamento di Fisica Padova,report DFPD-94-NP-4
Stellar archeology of the nearby LINER galaxies NGC 4579 and NGC 4736
Stellar archeology of nearby LINER galaxies may reveal if there is a stellar
young population that may be responsible for the LINER phenomenon. We show
results for the classical LINER galaxies NGC 4579 and NGC 4736 and find no
evidence of such populations.Comment: 2 pages, 2 figures, to be published in the Proceedings of the IAU
Symposium no. 26
Metronomic Chemotherapy with Vinorelbine Produces Clinical Benefit and Low Toxicity in Frail Elderly Patients Affected by Advanced Non-Small Cell Lung Cancer
Lung cancer is the leading cause of death worldwide. The treatment choice for advanced stage of lung cancer may depend on histotype, performance status (PS), age, and comorbidities. In the present study, we focused on the effect of metronomic vinorelbine treatment in elderly patients with advanced unresectable non-small cell lung cancer (NSCLC). Methods. From January 2016 to December 2016, 44 patients affected by non-small cell lung cancer referred to our oncology day hospital were progressively analyzed. The patients were treated with oral vinorelbine 30 mg x 3/wk or 40 mg x 3/wk meaning one day on and one day off. The patients were older than 60, stage IIIB or IV, ECOG PS ≥ 1, and have at least one important comorbidity (renal, hepatic, or cardiovascular disease). The schedule was based on ECOG-PS and comorbidities. The primary endpoint was progression-free survival (PFS). PFS was used to compare patients based on different scheduled dosage (30 or 40 mg x3/weekly) and age (more or less than 75 years old) as exploratory analysis. We also evaluated as secondary endpoint toxicity according to Common Toxicity Criteria Version 2.0. Results. Vinorelbine showed a good safety profile at different doses taken orally and was effective in controlling cancer progression. The median overall survival (OS) was 12 months. The disease control rate (DCR) achieved 63%. The median PFS was 9 months. A significant difference in PFS was detected comparing patients aged below with those over 75, and the HR value was 0.72 (p<0.05). Not significant was the difference between groups with different schedules. Conclusions. This study confirmed the safety profile of metronomic vinorelbine and its applicability for patients unfit for standard chemotherapies and adds the possibility of considering this type of schedule not only for very elderly patients
What information could the main actors of liquid biopsy provide? A representative case of non-small cell lung cancer (NSCLC)
In non-small cell lung cancer (NSCLC), there is a consensus regarding the use of liquid biopsy, generally, to detect "druggable" mutations and, in particular, to monitor tyrosine kinase inhibitor (TKI) treatments. However, whether circulating tumor cells (CTCs) are better tools than cell-free DNA (cfDNA), is still a matter of debate, mainly concerning which antigen(s) we should use to investigating simultaneously both epithelial and epithelial-to-mesenchymal transient (EMT) phenotype in the same sample of CTCs. To address this item, we exploited here a single-tube liquid biopsy, to detect both epithelial cell adhesion molecule (EpCAM)-positive CTCs and EpCAM-low/negative CTCs, because down-modulation of EpCAM is considered the first step in EMT. Furthermore, we analyzed the DNA from CTCs of four different phenotypes (ctcDNA), according to their EpCAM expression and cytokeratin pattern, and circulating tumor DNA (ctDNA) by droplet digital PCR (ddPCR), in order to disclose activating and resistancedriving mutations. Liquid biopsy reflected spatial and temporal heterogeneity of the tumor under treatment pressure. We provide the proof-of-concept that the complementary use of ctDNA and ctcDNA represents a reliable, minimally invasive and dynamic tool for a more comprehensive view of tumor evolution
Mapping low and high density clouds in astrophysical nebulae by imaging forbidden line emission
Emission line ratios have been essential for determining physical parameters
such as gas temperature and density in astrophysical gaseous nebulae. With the
advent of panoramic spectroscopic devices, images of regions with emission
lines related to these physical parameters can, in principle, also be produced.
We show that, with observations from modern instruments, it is possible to
transform images taken from density sensitive forbidden lines into images of
emission from high and low-density clouds by applying a transformation matrix.
In order to achieve this, images of the pairs of density sensitive lines as
well as the adjacent continuum have to be observed and combined. We have
computed the critical densities for a series of pairs of lines in the infrared,
optical, ultraviolet and X-rays bands, and calculated the pair line intensity
ratios in the high and low-density limit using a 4 and 5 level atom
approximation. In order to illustrate the method we applied it to GMOS-IFU data
of two galactic nuclei. We conclude that this method provides new information
of astrophysical interest, especially for mapping low and high-density clouds;
for this reason we call it "the ld/hd imaging method".Comment: 7 pages, 4 figures, accepted for publication on MNRA
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