3,719 research outputs found
Probing non-standard decoherence effects with solar and KamLAND neutrinos
It has been speculated that quantum gravity might induce a "foamy" space-time
structure at small scales, randomly perturbing the propagation phases of
free-streaming particles (such as kaons, neutrons, or neutrinos). Particle
interferometry might then reveal non-standard decoherence effects, in addition
to standard ones (due to, e.g., finite source size and detector resolution.) In
this work we discuss the phenomenology of such non-standard effects in the
propagation of electron neutrinos in the Sun and in the long-baseline reactor
experiment KamLAND, which jointly provide us with the best available probes of
decoherence at neutrino energies E ~ few MeV. In the solar neutrino case, by
means of a perturbative approach, decoherence is shown to modify the standard
(adiabatic) propagation in matter through a calculable damping factor. By
assuming a power-law dependence of decoherence effects in the energy domain
(E^n with n = 0,+/-1,+/-2), theoretical predictions for two-family neutrino
mixing are compared with the data and discussed. We find that neither solar nor
KamLAND data show evidence in favor of non-standard decoherence effects, whose
characteristic parameter gamma_0 can thus be significantly constrained. In the
"Lorentz-invariant" case n=-1, we obtain the upper limit gamma_0<0.78 x 10^-26
GeV at 95% C.L. In the specific case n=-2, the constraints can also be
interpreted as bounds on possible matter density fluctuations in the Sun, which
we improve by a factor of ~ 2 with respect to previous analyses.Comment: Minor changes. Version accepted for publication in Phys. Rev.
Geo-neutrinos: A systematic approach to uncertainties and correlations
Geo-neutrinos emitted by heat-producing elements (U, Th and K) represent a
unique probe of the Earth interior. The characterization of their fluxes is
subject, however, to rather large and highly correlated uncertainties. The
geochemical covariance of the U, Th and K abundances in various Earth
reservoirs induces positive correlations among the associated geo-neutrino
fluxes, and between these and the radiogenic heat. Mass-balance constraints in
the Bulk Silicate Earth (BSE) tend instead to anti-correlate the radiogenic
element abundances in complementary reservoirs. Experimental geo-neutrino
observables may be further (anti)correlated by instrumental effects. In this
context, we propose a systematic approach to covariance matrices, based on the
fact that all the relevant geo-neutrino observables and constraints can be
expressed as linear functions of the U, Th and K abundances in the Earth's
reservoirs (with relatively well-known coefficients). We briefly discuss here
the construction of a tentative "geo-neutrino source model" (GNSM) for the U,
Th, and K abundances in the main Earth reservoirs, based on selected
geophysical and geochemical data and models (when available), on plausible
hypotheses (when possible), and admittedly on arbitrary assumptions (when
unavoidable). We use then the GNSM to make predictions about several
experiments ("forward approach"), and to show how future data can constrain - a
posteriori - the error matrix of the model itself ("backward approach"). The
method may provide a useful statistical framework for evaluating the impact and
the global consistency of prospective geo-neutrino measurements and Earth
models.Comment: 17 pages, including 4 figures. To appear on "Earth, Moon, and
Planets," Special Issue on "Neutrino Geophysics," Proceedings of Neutrino
Science 2005 (Honolulu, Hawaii, Dec. 2005
Day-night asymmetry of high and low energy solar neutrino events in Super-Kamiokande and in the Sudbury Neutrino Observatory
In the context of solar neutrino oscillations among active states, we briefly
discuss the current likelihood of Mikheyev-Smirnov-Wolfenstein (MSW) solutions
to the solar neutrino problem, which appear to be currently favored at large
mixing, where small Earth regeneration effects might still be observable in
Super-Kamiokande (SK) and in the Sudbury Neutrino Observatory (SNO). We point
out that, since such effects are larger at high (low) solar neutrino energies
for high (low) values of the mass square difference \delta m^2, it may be
useful to split the night-day rate asymmetry in two separate energy ranges. We
show that the difference \Delta of the night-day asymmetry at high and low
energy may help to discriminate the two large-mixing solutions at low and high
\delta m^2 through a sign test, both in SK and in SNO, provided that the
sensitivity to \Delta can reach the (sub)percent level.Comment: 6 pages (RevTeX) + 4 figures (PostScript). Final version, to appear
in Phys. Rev.
Observables sensitive to absolute neutrino masses: A reappraisal after WMAP-3y and first MINOS results
In the light of recent neutrino oscillation and non-oscillation data, we
revisit the phenomenological constraints applicable to three observables
sensitive to absolute neutrino masses: The effective neutrino mass in single
beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless
double beta decay (m_2beta); and the sum of neutrino masses in cosmology
(Sigma). In particular, we include the constraints coming from the first Main
Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson
Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other
relevant cosmological data and priors. We find that the largest neutrino
squared mass difference is determined with a 15% accuracy (at 2-sigma) after
adding MINOS to world data. We also find upper bounds on the sum of neutrino
masses Sigma ranging from ~2 eV (WMAP-3y data only) to ~0.2 eV (all
cosmological data) at 2-sigma, in agreement with previous studies. In addition,
we discuss the connection of such bounds with those placed on the matter power
spectrum normalization parameter sigma_8. We show how the partial degeneracy
between Sigma and sigma_8 in WMAP-3y data is broken by adding further
cosmological data, and how the overall preference of such data for relatively
high values of sigma_8 pushes the upper bound of Sigma in the sub-eV range.
Finally, for various combination of data sets, we revisit the (in)compatibility
between current Sigma and m_2beta constraints (and claims), and derive
quantitative predictions for future single and double beta decay experiments.Comment: 18 pages, including 7 figure
Global analysis of neutrino masses, mixings and phases: entering the era of leptonic CP violation searches
We perform a global analysis of neutrino oscillation data, including
high-precision measurements of the neutrino mixing angle theta_13 at reactor
experiments, which have confirmed previous indications in favor of theta_13>0.
Recent data presented at the Neutrino 2012 Conference are also included. We
focus on the correlations between theta_13 and the mixing angle theta_23, as
well as between theta_13 and the neutrino CP-violation phase delta. We find
interesting indications for theta_23< pi/4 and possible hints for delta ~ pi,
with no significant difference between normal and inverted mass hierarchy.Comment: Updated version, including recent data released at the Neutrino 2012
Conference. Some references adde
The Impact of Formula Choice for the Management of Pediatric Cow's Milk Allergy on the Occurrence of Other Allergic Manifestations: The Atopic March Cohort Study
Objectives: To compare the impact of different formulas on the occurrence of other atopic manifestations and the time of immune tolerance acquisition. Study design: In a 36-month prospective cohort study, the occurrence of other atopic manifestations (eczema, urticaria, asthma, and rhinoconjunctivitis) and the time of immune tolerance acquisition were comparatively evaluated in immunoglobulin E–mediated children with cow's milk allergy (CMA) treated with extensively hydrolyzed casein formula containing the probiotic L. rhamnosus GG (EHCF + LGG), rice hydrolyzed formula, soy formula, extensively hydrolyzed whey formula (EHWF), or amino acid–based formula. Results: In total, 365 subjects were enrolled into the study, 73 per formula cohort. The incidence of atopic manifestations was 0.22 (Bonferroni-corrected 95% CI 0.09-0.34) in the EHCF + LGG cohort; 0.52 (0.37-0.67) in the rice hydrolyzed formula cohort; 0.58 (0.43-0.72) in the soy formula cohort; 0.51 (0.36-0.66) in the EHWF cohort; and 0.77 (0.64-0.89) in the amino acid–based formula cohort. The incidence of atopic manifestations in the rice hydrolyzed formula, soy formula, EHWF, and amino acid–based formula cohorts vs the EHCF + LGG cohort was always greater than the prespecified absolute difference of 0.25 at an alpha-level of 0.0125, with corresponding risk ratios of 2.37 (1.46-3.86, P < .001) for rice hydrolyzed formula vs EHCF + LGG; 2.62 (1.63-4.22, P < .001) for soy formula vs EHCF + LGG; 2.31 (1.42-3.77, P < .001) for EHWF vs EHCF + LGG; and 3.50 (2.23-5.49, P < .001) for amino acid–based formula vs EHCF + LGG. The 36-month immune tolerance acquisition rate was greater in the EHCF + LGG cohort. Conclusions: The use of EHCF + LGG for CMA treatment is associated with lower incidence of atopic manifestations and greater rate of immune tolerance acquisition
Global fits to neutrino oscillation data
I summarize the determination of neutrino oscillation parameters within the
three-flavor framework from world neutrino oscillation data with date of May
2006, including the first results from the MINOS long-baseline experiment. It
is illustrated how the determination of the leading "solar" and "atmospheric"
parameters, as well as the bound on emerge from an interplay of
various complementary data sets. Furthermore, I discuss possible implications
of sub-leading three-flavor effects in present atmospheric neutrino data
induced by and for the bound on
and non-maximal values of , emphasizing, however, that these
effects are not statistically significant at present. Finally, in view of the
upcoming MiniBooNE results I briefly comment on the problem to reconcile the
LSND signal.Comment: 5 pages, 5 figures, talk presented at the SNOW2006 workshop,
Stockholm, 2-6 May 200
Observables sensitive to absolute neutrino masses: Constraints and correlations from world neutrino data
In the context of three-flavor neutrino mixing, we present a thorough study
of the phenomenological constraints applicable to three observables sensitive
to absolute neutrino masses: The effective neutrino mass in Tritium beta decay
(m_beta); the effective Majorana neutrino mass in neutrinoless double beta
decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). We
discuss the correlations among these variables which arise from the combination
of all the available neutrino oscillation data, in both normal and inverse
neutrino mass hierarchy. We set upper limits on m_beta by combining updated
results from the Mainz and Troitsk experiments. We also consider the latest
results on m_2beta from the Heidelberg-Moscow experiment, both with and without
the lower bound claimed by such experiment. We derive upper limits on Sigma
from an updated combination of data from the Wilkinson Microwave Anisotropy
Probe (WMAP) satellite and the 2 degrees Fields (2dF) Galaxy Redshifts Survey,
with and without Lyman-alpha forest data from the Sloan Digital Sky Survey
(SDSS), in models with a non-zero running of the spectral index of primordial
inflationary perturbations. The results are discussed in terms of
two-dimensional projections of the globally allowed region in the
(m_beta,m_2beta,Sigma) parameter space, which neatly show the relative impact
of each data set. In particular, the (in)compatibility between Sigma and
m_2beta constraints is highlighted for various combinations of data. We also
briefly discuss how future neutrino data (both oscillatory and non-oscillatory)
can further probe the currently allowed regions.Comment: 17 pages (RevTeX) + 7 figures (PostScript). Minor changes in text;
references added; results unchanged. To appear in PR
A Video Processing and Data Retrieval Framework for Fish Population Monitoring
In this work we present a framework for fish population monitoring through the analysis of underwater videos. We specifically focus on the user information needs, and on the dynamic data extraction and retrieval mechanisms that support them. Sophisticated though a software tool may be, it is ultimately important that its interface satisfies users' actual needs and that users can easily focus on the specific data of interest. In the case of fish population monitoring, marine biologists have to interact with a system which not only provides information from a biological point of view, but also offers instruments to let them guide the video processing task for both video and algorithm selection. This paper aims at describing the system's underlying video processing and workflow low-level details, and their connection to the user interface for on-demand data retrieval by biologists
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