5,095 research outputs found
New physics from ultrahigh energy cosmic rays
Cosmic rays from outer space enter the atmosphere with energies of up to
10^{11} GeV. The initial particle or a secondary hadron inside the shower may
then interact with an air nucleon to produce nonstandard particles. In this
article we study the production of new physics by high energy cosmic rays,
focusing on the long-lived gluino of split-SUSY models and a WIMP working as
dark matter. We first deduce the total flux of hadron events at any depth in
the atmosphere, showing that secondary hadrons can not be neglected. Then we
use these results to find the flux of gluinos and WIMPs that reach the ground
after being produced inside air showers. We also evaluate the probability of
producing these exotic particles in a single proton shower of ultrahigh energy.
Finally we discuss the possible signal in current and projected experiments.
While the tiny flux of WIMPs does not seem to have any phenomenological
consequences, we show that the gluinos could modify substantially the profile
of a small fraction of extensive air showers. In particular, they could produce
a distinct signal observable at AUGER in showers of large zenith angle.Comment: 9 pages, version to appear in PR
Nonzero and Neutrino Masses from Modified Neutrino Mixing Matrix
The nonzero and relatively large have been reported by Daya
Bay, T2K, MINOS, and Double Chooz Collaborations. In order to accommodate the
nonzero , we modified the tribimaximal (TB), bimaxima (BM), and
democratic (DC) neutrino mixing matrices. From three modified neutrino mixing
matrices, two of them (the modified BM and DC mixing matrices) can give nonzero
which is compatible with the result of the Daya Bay and T2K
experiments. The modified TB neutrino mixing matrix predicts the value of
greater than the upper bound value of the latest experimental
results. By using the modified neutrino mixing matrices and impose an
additional assumption that neutrino mass matrices have two zeros texture, we
then obtain the neutrino mass in normal hierarchy when
for the neutrino mass matrix from the
modified TB neutrino mixing matrix and for
the neutrino mass matrix from the modified DC neutrino mixing matrix. For these
two patterns of neutrino mass matrices, either the atmospheric mass squared
difference or the solar mass squared difference can be obtained, but not both
of them simultaneously. From four patterns of two zeros texture to be
considered on the obtained neutrino mass matrix from the modified BM neutrino
mixing matrix, none of them can predict correctly neutrino mass spectrum
(normal or inverted hierarchy).Comment: 13 pages, no figure, some references added, and slight revision due
to reviewer(s) comments, to be published in IJMP
Impact of nuclear effects on the determination of the nucleon axial mass
We analize the influence of nuclear effects on the determination of the
nucleon axial mass from nuclear cross sections. Our work is based on a
formalism widely applied to describe electron-nucleus scattering data in the
impulse approximation regime. The results of numerical calculations show that
correlation effects, not taken into account by the relativistic Fermi gas
model, sizably affect the -dependence of the cross section. However, their
inclusion does not appear to explain the large values of the axial mass
recently reported by the K2K and MiniBooNE collaborations.Comment: 4 pages, three figure
SOME PERINATAL ENDOCRINE AND MORPHOLOGICAL ASPECTS OF CANINE SPECIES
Despite the huge literature about dog medicine, the perinatal period of growth and development and possible perturbations of the health of fetuses and newborns are still scarcely investigated, but with a recent, increasing scientific interest. The present thesis was therefore aimed to investigate some perinatal aspects of canine perinatology. Firstly, the study focused on the presence of some growth and metabolic factors and protective substances in dog fetal fluids at term of normal pregnancy. About growth and metabolic factors, the first study showed that insulin-like growth factors I (IGF-I) were higher in amniotic (AM) than allantoic (AL) fluid and the effect of breed size, even if opposite, on both IGF-I and non-esterified fatty acids (NEFA) was evidenced. The findings suggested that AM IGF-I could be used as an indicator of growth potential in canine species, whereas AM NEFA could work as a marker of fat mobilization for an energy request. The second study on fetal fluids, aimed to assess AM and AL IgG and lysozyme concentrations, documented higher IgG levels in AM than AL fluid, as a consequence of a supposed direct fetal IgG production, whereas no significant differences were found in lysozyme values between the two fluids. Maternal parity was demonstrated to affect IgG concentrations. A second area of study was the assessment of newborns hair and nails usefulness as the newest non invasive matrices for a long-term retrospective investigation of the Hypothalamic-Pituitary-Adrenal axis activation, by cortisol (C) concentrations analysis. The study evidenced that C was detectable in both matrices, with significant higher values in premature puppies compared to term-born dead puppies or puppies dead within the first 30 days of age. Furthermore, because of the newborn puppy high susceptibility to bacterial infection, often followed by death, the fourth study investigated the bacterial involvement in canine neonatal mortality, demonstrating that bacterial infections, above all by E. coli, alone or in association with other bacteria, represent an important cause of neonatal losses. In addition, the study highlighted the importance of the antimicrobial susceptibility test in case of suspected neonatal bacterial infection for a more targeted therapy of surviving litter-mates and for a better management of further gestations in bitch with previous neonatal mortality. The last study was designed to investigate some aspects of skeletal development during the neonatal period in the attempt to provide further knowledge about the first month of skeletal growth in puppies, but also aimed to assess the possible use of some radiographic, morphometric, and anatomic parameters for the age estimation in newborn dogs. The study proved that the neonatal growth occurs gradually as the age progresses, and simultaneously in the body, limbs, and skull. The radiographic evaluation of the ossification centers appearance resulted a useful tool to estimate the neonatal age in puppies, even if during the first 14 days of age significant skeletal changes were not observed. In this respect, the radiographic and anatomic measures of the hindlimb long bones and skull length seem to provide better guarantees; specifically, the neurocranium width as well as tibial and femoral lengths resulted the most correlated measurements with the age. Thus, in the future radiographic and/or anatomical morphometry of limbs and skull could become the best tool for neonatal age estimation
Hair and Claw Dehydroepiandrosterone Concentrations in Newborn Puppies Spontaneously Dead within 30 Days of Age
The latest intrauterine fetal developmental stage and the neonatal period represent the most challenging phases for mammalian offspring. Toward the term of pregnancy, during parturition, and after birth, the hypothalamic–pituitary–adrenal axis (HPA) is a key system regulating several physiologic processes, through the production of cortisol and dehydroepiandrosterone (DHEA). This study was aimed to assess DHEA concentrations in hair and claws of 126 spontaneously dead newborn puppies, classified as premature puppies (PRE-P), stillborn puppies (STILL-P) and puppies that died from the 1st to the 30th day of life (NEON-P). The possible influence of newborn sex, breed body size, and timing of death on DHEA concentrations in both matrices was evaluated. Claw DHEA concentrations were higher in the PRE-P group when compared to STILL-P and NEON-P puppies (p < 0.05), whilst no significant differences were found in hair for all the studied factors. The results confirm the hypothesis that higher amounts of DHEA are produced during the intrauterine life in dogs, also in puppies that will die soon after birth
Tailoring confining jacket for concrete column using ultra high performance-fiber reinforced cementitious composites (UHP-FRCC) with high volume fly ash (HVFA)
Ultra-High Performance Fibre-Reinforced Cementitious Composites (UHP-FRCC) show excellent mechanical performances in terms of strength, ductility, and durability. Therefore, these cementitious materials have been successfully used for repairing, strengthening, and seismic retrofitting of old structures. However, UHP-FRCCs are not always environmental friendly products, especially in terms of the initial cost, due to the large quantity of cement that is contained in the mixture. Different rates of fly ash substitute herein part of the cement, and the new UHP-FRCCs are used to retrofit concrete columns to overcome this problem. To simulate the mechanical response of these columns, cylindrical specimens, which are made of normal concrete and reinforced with different UHP-FRCC jackets, are tested in uniaxial compression. Relationships between the size of the jacket, the percentage of cement replaced by fly ash, and the strength of the columns are measured and analyzed by means of the eco-mechanical approach. As a result, a replacement of approximately 50% of cement with fly ash, and a suitable thickness of the UHP-FRCC jacket, might ensure the lowest environmental impact without compromising the mechanical performances
Silvicultural strategies for introduced tree species in Northern Italy
The bio-deterioration of the historical heritage by fast growing and vigorous introduced tree species, and the reduction of native diversity, mostly in riparian, forest, wetland, and coastal habitats are considered amongst particularly relevant impacts for Italy. According to a recent survey of EU Life+ projects, the introduced tree species most often targeted for eradication by conservation projects across Europe are black locust (Robinia pseudoacacia L.), tree of heaven (Ailanthus altissima (Mill.) Swingle), red oak (Quercus rubra L.), and black cherry (Prunus serotina Ehrh.). In this chapter, we report on the few field experiences and success stories of silvicultural control of these introduced tree species in urban and natural habitats in northern Italy
Atmospheric lepton fluxes at ultrahigh energies
In order to estimate the possibility to observe exotic physics in a neutrino
telescope, it is essential to first understand the flux of atmospheric
neutrinos, muons and dimuons. We study the production of these leptons by
high-energy cosmic rays. We identify three main sources of muons of energy E >
10^6 GeV: the weak decay of charm and bottom mesons and the electromagnetic
decay of unflavored mesons. Contrary to the standard assumption, we find that
eta mesons, not the prompt decay of charm hadrons, are the dominant source of
atmospheric muons at these energies. We show that, as a consequence, the ratio
between the neutrino and muon fluxes is significantly reduced. For dimuons,
which may be a background for long-lived staus produced near a neutrino
telescope, we find that pairs of E ~ 10^7 GeV forming an angle above 10^-6 rad
are produced through D (80%) or B (10%) meson decay and through Drell-Yan
proceses (10%). The frequency of all these processes has been evaluated using
the jet code PYTHIA.Comment: 10 pages, 4 figures; published versio
Predicting leptonic CP violation in the light of Daya Bay result
In the light of the recent Daya Bay result the reactor angle is about 9
degrees, we reconsider the model presented in arXiv:1005.3482 showing that,
when all neutrino oscillation parameters are taken at their best fit values of
Schwetz et al and the reactor angle to be the central value of Daya Bay, the
predicted value of the CP phase is approximately 45 degrees.Comment: 4 pages, 2 figures, update of arXiv:1005.348
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