797 research outputs found
The momentum distribution of J/psi in B decays
The discrepancy between theory and data in the momentum distribution of slow
J/psi in B decays has been several times addressed as a puzzle. Using the most
recent results on exclusive B decays into J/psi and heavy kaons or exotic
mesons and reconsidering the non-relativistic-QCD calculation of the color
octet fragmentation component, we show that an improvement in the comparison
between data and theory can be obtained. There is still room for a better fit
to data and this may imply that new exotic mesons of the XYZ kind have yet to
be discovered.Comment: 4 pages, 2 figures, 2 tables. To appear in Physical Review
DAMA/NaI results
The DAMA/NaI set-up of the DAMA experiment has been operative during seven
annual cycles and has investigated several rare processes. In particular, it
has been realised in order to investigate the model independent annual
modulation signature for Dark Matter particles in the galactic halo. With the
total exposure collected in the seven annual cycles (107731 kg day) a model
independent evidence for the presence of a Dark Matter particle component in
the galactic halo has been pointed out at 6.3 sigma C.L.. Some of the many
possible corollary model dependent quests for the candidate particle have been
presented as well.Comment: Contributed paper to the Rencontres de Moriond "Electroweak
Interactions and Unified Theories", La Thuile, Aosta Valley, Italy, March
200
QTLs for Morphogenetic Traits in Medicago Truncatula
Plant morphogenesis that includes growth, development and flowering date, drives a large number of agronomical important traits in both grain and forage crops. Quantitative trait locus (QTL) mapping is a way to locate zones of the genome that are involved in the variations observed in a segregating population. Co-location of QTLs and candidate genes is an indication of the involvement of the genes in the variation. The objective of this study was to analyse segregation of aerial morphogenetic traits in a mapping population of recombinant inbred lines of the model legume species M. truncatula , to locate QTLs and candidate genes
Joint Application of the Target Trial Causal Framework and Machine Learning Modeling to Optimize Antibiotic Therapy: Use Case on Acute Bacterial Skin and Skin Structure Infections due to Methicillin-resistant Staphylococcus aureus
Bacterial infections are responsible for high mortality worldwide.
Antimicrobial resistance underlying the infection, and multifaceted patient's
clinical status can hamper the correct choice of antibiotic treatment.
Randomized clinical trials provide average treatment effect estimates but are
not ideal for risk stratification and optimization of therapeutic choice, i.e.,
individualized treatment effects (ITE). Here, we leverage large-scale
electronic health record data, collected from Southern US academic clinics, to
emulate a clinical trial, i.e., 'target trial', and develop a machine learning
model of mortality prediction and ITE estimation for patients diagnosed with
acute bacterial skin and skin structure infection (ABSSSI) due to
methicillin-resistant Staphylococcus aureus (MRSA). ABSSSI-MRSA is a
challenging condition with reduced treatment options - vancomycin is the
preferred choice, but it has non-negligible side effects. First, we use
propensity score matching to emulate the trial and create a treatment
randomized (vancomycin vs. other antibiotics) dataset. Next, we use this data
to train various machine learning methods (including boosted/LASSO logistic
regression, support vector machines, and random forest) and choose the best
model in terms of area under the receiver characteristic (AUC) through
bootstrap validation. Lastly, we use the models to calculate ITE and identify
possible averted deaths by therapy change. The out-of-bag tests indicate that
SVM and RF are the most accurate, with AUC of 81% and 78%, respectively, but
BLR/LASSO is not far behind (76%). By calculating the counterfactuals using the
BLR/LASSO, vancomycin increases the risk of death, but it shows a large
variation (odds ratio 1.2, 95% range 0.4-3.8) and the contribution to outcome
probability is modest. Instead, the RF exhibits stronger changes in ITE,
suggesting more complex treatment heterogeneity.Comment: This is the Proceedings of the KDD workshop on Applied Data Science
for Healthcare (DSHealth 2022), which was held on Washington D.C, August 14
202
A novel integral representation for the Adler function
New integral representations for the Adler D-function and the R-ratio of the
electron-positron annihilation into hadrons are derived in the general
framework of the analytic approach to QCD. These representations capture the
nonperturbative information encoded in the dispersion relation for the
D-function, the effects due to the interrelation between spacelike and timelike
domains, and the effects due to the nonvanishing pion mass. The latter plays a
crucial role in this analysis, forcing the Adler function to vanish in the
infrared limit. Within the developed approach the D-function is calculated by
employing its perturbative approximation as the only additional input. The
obtained result is found to be in reasonable agreement with the experimental
prediction for the Adler function in the entire range of momenta .Comment: 11 pages, 3 figure
Investigating electron interacting dark matter
Some extensions of the Standard Model provide Dark Matter candidate particles
which can have a dominant coupling with the lepton sector of the ordinary
matter. Thus, such Dark Matter candidate particles () can be directly
detected only through their interaction with electrons in the detectors of a
suitable experiment, while they are lost by experiments based on the rejection
of the electromagnetic component of the experimental counting rate. These
candidates can also offer a possible source of the 511 keV photons observed
from the galactic bulge. In this paper this scenario is investigated. Some
theoretical arguments are developed and related phenomenological aspects are
discussed. Allowed intervals and regions for the characteristic
phenomenological parameters of the considered model and of the possible
mediator of the interaction are also derived considering the DAMA/NaI data.Comment: 16 pages, 6 figures. Accepted for publication in PRD. One typo
correcte
Investigating halo substructures with annual modulation signature
Galaxy hierarchical formation theories, numerical simulations, the discovery
of the Sagittarius Dwarf Elliptical Galaxy (SagDEG) in 1994 and more recent
investigations suggest that the dark halo of the Milky Way can have a rich
phenomenology containing non thermalized substructures. In the present
preliminary study, we investigate the case of the SagDEG (the best known
satellite galaxy in the Milky Way crossing the solar neighbourhood) analyzing
the consequences of its dark matter stream contribution to the galactic halo on
the basis of the DAMA/NaI annual modulation data. The present analysis is
restricted to some WIMP candidates and to some of the astrophysical, nuclear
and particle Physics scenarios. Other candidates such as e.g. the light bosonic
ones, we discussed elsewhere, and other non thermalized substructures are not
yet addressed here.Comment: 17 pages, 10 figures, to appear in Eur. Phys. J.
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