248 research outputs found
Revisiting the T2K data using different models for the neutrino-nucleus cross sections
We present a three-flavour fit to the recent \nu\mu --> \nu e and \nu\mu -->
\nu\mu T2K oscillation data with different models for the neutrino-nucleus
cross section. We show that, even for a limited statistics, the allowed regions
and best fit points in the (\theta_{13},\delta_{CP}) and (\theta_{23},\Delta
m^2_{atm}) planes are affected if, instead of using the Fermi Gas model to
describe the quasielastic cross section, we employ a model including the
multinucleon emission channel.Comment: 13 pages, 12 figures. A new section on the inverted hierarchy added.
Version matching the published one in PL
Cannabinoid derivate-loaded PLGA nanocarriers for oral administration: formulation, characterization, and cytotoxicity studies
Planet-star interactions with precise transit timing. III. Entering the regime of dynamical tides
Hot Jupiters on extremely short-period orbits are expected to be unstable to
tidal dissipation and spiral toward their host stars. That is because they
transfer the angular momentum of the orbital motion through tidal dissipation
into the stellar interior. Although the magnitude of this phenomenon is related
to the physical properties of a specific star-planet system, statistical
studies show that tidal dissipation might shape the architecture of hot Jupiter
systems during the stellar lifetime on the main sequence. The efficiency of
tidal dissipation remains poorly constrained in star-planet systems. Stellar
interior models show that the dissipation of dynamical tides in radiation zones
could be the dominant mechanism driving planetary orbital decay. These
theoretical predictions can be verified with the transit timing method. We
acquired new precise transit mid-times for five planets. They were previously
identified as the best candidates for which orbital decay might be detected.
Analysis of the timing data allowed us to place tighter constraints on the
orbital decay rate. No statistically significant changes in their orbital
periods were detected for all five hot Jupiters in systems HAT-P-23, KELT-1,
KELT-16, WASP-18, and WASP-103. For planets HAT-P-23 b, WASP-18 b, and WASP-103
b, observations show that the mechanism of the dynamical tides dissipation
probably does not operate in their host stars, preventing them from rapid
orbital decay. This finding aligns with the models of stellar interiors of
F-type stars, in which dynamical tides are not fully damped due to convective
cores. For KELT-16 b, the span of transit timing data was not long enough to
verify the theoretical predictions. KELT-1 b was identified as a potential
laboratory for studying the dissipative tidal interactions of inertial waves in
a convective layer.Comment: Accepted for publication in A&
MiniBooNE and LSND data: non-standard neutrino interactions in a (3+1) scheme versus (3+2) oscillations
The recently observed event excess in MiniBooNE anti-neutrino data is in
agreement with the LSND evidence for electron anti-neutrino appearance. We
propose an explanation of these data in terms of a (3+1) scheme with a sterile
neutrino including non-standard neutrino interactions (NSI) at neutrino
production and detection. The interference between oscillations and NSI
provides a source for CP violation which we use to reconcile different results
from neutrino and anti-neutrino data. Our best fit results imply NSI at the
level of a few percent relative to the standard weak interaction, in agreement
with current bounds. We compare the quality of the NSI fit to the one obtained
within the (3+1) and (3+2) pure oscillation frameworks. We also briefly comment
on using NSI (in an effective two-flavour framework) to address a possible
difference in neutrino and anti-neutrino results from the MINOS experiment.Comment: 28 pages, 9 figures, discussion improved, new appendix added,
conclusions unchange
Immobilization of Aspergillus niger lipase on chitosan-coated magnetic nanoparticles using two covalent-binding methods
Aspergillus niger lipase immobilization by covalent binding on chitosan-coated magnetic nanoparticles (CMNP), obtained by one-step co-precipitation, was studied. Hydroxyl and amino groups of support were activated using glycidol and glutaraldehyde, respectively. Fourier transform infrared spectrometry, high-resolution transmission electron microscopy and thermogravimetric analysis confirmed reaction of these coupling agents with the enzyme and achievement of a successful immobilization. The derivatives showed activities of 309.5 ± 2.0 and 266.2 ± 2.8 U (g support)(-1) for the CMNP treated with glutaraldehyde and with glycidol, respectively. Immobilization enhanced the enzyme stability against changes of pH and temperature, compared to free lipase. Furthermore, the kinetic parameters K m and V max were determined for the free and immobilized enzyme. K m value quantified for enzyme immobilized by means of glutaraldehyde was 1.7 times lowers than for free lipase. High storage stability during 50 days was observed in the immobilized derivatives. Finally, immobilized derivatives retained above 80% of their initial activity after 15 hydrolytic cycles. The immobilized enzyme can be applied in various biotechnological processes involving magnetic separation.Fil: Osuna, Yolanda. Universidad Autónoma de Coahuila; MéxicoFil: Sandoval, José. Universidad Autónoma de Coahuila; MéxicoFil: Saade, Hened. Centro de Investigación en Química Aplicada; MéxicoFil: López, Raúl G.. Centro de Investigación en Química Aplicada; MéxicoFil: Martinez, José L.. Universidad Autónoma de Coahuila; MéxicoFil: Colunga, Edith M.. Universidad Autónoma de Coahuila; MéxicoFil: de la Cruz, Gabriela. Universidad Autónoma de Coahuila; MéxicoFil: Segura, Elda P.. Universidad Autónoma de Coahuila; MéxicoFil: Arevalo, Fernando Javier. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ilyina, Anna. Universidad Autónoma de Coahuila; Méxic
The minimal 3+2 neutrino model versus oscillation anomalies
We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscillation data including the anomalies better than the standard 3ν model and similarly to the 3+2 phenomenological models, even though the number of free parameters is much smaller than in the latter. Accounting for the anomalies in the minimal model favours a normal hierarchy of the light states and requires a large reactor angle, in agreement with recent measurements. Our analysis of the model employs a new parametrization of seesaw models that extends the Casas-Ibarra one to regimes where higher order corrections in the light-heavy mixings are significant
Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC experiment at SNOLAB
We present results of a dark matter search performed with a 0.6 kg day
exposure of the DAMIC experiment at the SNOLAB underground laboratory. We
measure the energy spectrum of ionization events in the bulk silicon of
charge-coupled devices down to a signal of 60 eV electron equivalent. The data
are consistent with radiogenic backgrounds, and constraints on the
spin-independent WIMP-nucleon elastic-scattering cross section are accordingly
placed. A region of parameter space relevant to the potential signal from the
CDMS-II Si experiment is excluded using the same target for the first time.
This result obtained with a limited exposure demonstrates the potential to
explore the low-mass WIMP region (<10 GeV/) of the upcoming DAMIC100, a
100 g detector currently being installed in SNOLAB.Comment: 11 pages, 11 figure
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