952 research outputs found
Nuclear re-interaction effects in quasi-elastic neutrino nucleus scattering
The quasi-elastic neutrino-nucleus cross section has been calculated by using
a Fermi gas model corrected to consider the re-scattering between the emitted
nucleon and the rest nucleus. As an example of the relevance of this effect we
show results for the muon production cross section on 16O target.Comment: 7 pages, 4 Postscript figures, Contribution to NuInt01 Workshop, KEK,
Tsukuba, Japa
Identification of Showers with Cores Outside the ARGO-YBJ Detector
In any EAS array, the rejection of events with shower cores outside the
detector boundaries is of great importance. A large difference between the true
and the reconstructed shower core positions may lead to a systematic
miscalculation of some shower characteristics. Moreover, an accurate
determination of the shower core position for selected internal events is
important to reconstruct the primary direction using conical fits to the shower
front, improving the detector angular resolution, or to performe an efficient
gamma/hadron discrimination. In this paper we present a procedure able to
identify and reject showers with cores outside the ARGO-YBJ carpet boundaries.
A comparison of the results for gamma and proton induced showers is reported.Comment: 4 pages, to be published in the Proceedings of the 28th International
Cosmic Ray Conference (Tsukuba, Japan 2003
Expected sensitivity of ARGO-YBJ to detect point gamma-ray sources
ARGO-YBJ is a full coverage air shower detector currently under construction
at the Yangbajing Laboratory (4300 m a.s.l., Tibet, China). First data obtained
with a subset of the apparatus will be available in summer 2003 while the full
detector operation is expected in 2005. One of the main aims of ARGO-YBJ is the
observation of gamma-ray sources, at an energy threshold of a few hundreds GeV.
In this paper we present the expected sensitivity to detect point gamma ray
sources, with particular attention to the Crab Nebula. According to our
simulations a Crab-like signal could be detected in one year of operation with
a statistical significance of 10 standard deviations, without any gamma/hadron
discrimination.Comment: 4 pages, 2 Postscript figure
Final state interaction effects in neutrino-nucleus quasielastic scattering
We consider the charged-current quasielastic scattering of muon neutrinos on
an Oxygen 16 target, described within a relativistic shell model and, for
comparison, the relativistic Fermi gas. Final state interactions are described
in the distorted wave impulse approximation, using both a relativistic mean
field potential and a relativistic optical potential, with and without
imaginary part. We present results for inclusive cross sections at fixed
neutrino energies in the range 200 MeV - 1 GeV, showing that final
state interaction effects can remain sizable even at large energies.Comment: 4 pages, 4 figures; poster session of the Third International
Workshop on Neutrino-Nucleus Interactions in the Few GeV Region (NuInt04),
Gran Sasso (Italy), March 17-21, 2004; to appear in the proceeding
The Pierre Auger Observatory ultra-high energy neutrino follow-up of the LIGO gravitational-waves events
In early 2016 the LIGO and Virgo Collaborations reported the breakthrough observation of the first gravitational-wave transient with the twin detectors of Advanced LIGO in September 2015 (event GW150914), followed three months later by the detection of GW151226. Both events were produced by the coalescence of black holes. Although no electromagnetic emission is generally expected from such events, in the presence of magnetic fields and debris from the formation of black holes, radiation of ultra-high energy (UHE) neutrinos might be possible and, if detected, could help constrain the direction of the source of the events. The Pierre Auger Observatory is capable of identifying air-shower events initiated by ultra-high energy neutrinos, using the data from its surface detector. The emission of neutrinos with energy > 1017 eV can be detected from point-like sources contained in the equatorial declination band between −65 and +60 degrees, including a portion of the 90% CL inferred position for GW150914 and GW151226. A search for neutrinos in temporal and directional proximity with the GW events (and for the GW candidate event LVT151012) was performed. Constraints to the energy radiated in UHE neutrinos are derived from the non-detection of neutrinos in the search windows
Immunosenescence, Inflammaging, and Frailty: Role of Myeloid Cells in Age-Related Diseases
The immune system is the central regulator of tissue homeostasis, ensuring tissue regeneration and protection against both pathogens and the neoformation of cancer cells. Its proper functioning requires homeostatic properties, which are maintained by an adequate balance of myeloid and lymphoid responses. Aging progressively undermines this ability and compromises the correct activation of immune responses, as well as the resolution of the inflammatory response. A subclinical syndrome of “homeostatic frailty” appears as a distinctive trait of the elderly, which predisposes to immune debilitation and chronic low-grade inflammation (inflammaging), causing the uncontrolled development of chronic and degenerative diseases. The innate immune compartment, in particular, undergoes to a sequela of age-dependent functional alterations, encompassing steps of myeloid progenitor differentiation and altered responses to endogenous and exogenous threats. Here, we will review the age-dependent evolution of myeloid populations, as well as their impact on frailty and diseases of the elderly
Myeloid-derived suppressor cells: Ductile targets in disease
Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells with major regulatory functions and rise during pathological conditions, including cancer, infections and autoimmune conditions. MDSC expansion is generally linked to inflammatory processes that emerge in response to stable immunological stress, which alter both magnitude and quality of the myelopoietic output. Inability to reinstate physiological myelopoiesis would fall in an "emergency state" that perpetually reprograms myeloid cells toward suppressive functions. While differentiation and reprogramming of myeloid cells toward an immunosuppressive phenotype can be considered the result of a multistep process that originates in the bone marrow and culminates in the tumor microenvironment, the identification of its driving events may offer potential therapeutic approaches in different pathologies. Indeed, whereas expansion of MDSCs, in both murine and human tumor bearers, results in reduced immune surveillance and antitumor cytotoxicity, placing an obstacle to the effectiveness of anticancer therapies, adoptive transfer of MDSCs has shown therapeutic benefits in autoimmune disorders. Here, we describe relevant mechanisms of myeloid cell reprogramming leading to generation of suppressive MDSCs and discuss their therapeutic ductility in disease
Effects of nuclear re-interactions in quasi-elastic neutrino-nucleus scattering
The effects of nuclear re-interactions in the quasi-elastic neutrino-nucleus
scattering are investigated with a phenomenological model. We found that the
nuclear responses are lowered and their maxima are shifted towards higher
excitation energies. This is reflected on the total neutrino-nucleus cross
section in a general reduction of about 15% for neutrino energies above 300
MeV.Comment: 15 pages, 5 figures. Submitted to AstroParticle Physic
Atmospheric Calorimetry above 10 eV: Shooting Lasers at the Pierre Auger Cosmic-Ray Observatory
The Pierre Auger Cosmic-Ray Observatory uses the earth's atmosphere as a
calorimeter to measure extensive air-showers created by particles of
astrophysical origin. Some of these particles carry joules of energy. At these
extreme energies, test beams are not available in the conventional sense. Yet
understanding the energy response of the observatory is important. For example,
the propagation distance of the highest energy cosmic-rays through the cosmic
microwave background radiation (CMBR) is predicted to be strong function of
energy. This paper will discuss recently reported results from the observatory
and the use of calibrated pulsed UV laser "test-beams" that simulate the
optical signatures of ultra-high energy cosmic rays. The status of the much
larger 200,000 km companion detector planned for the northern hemisphere
will also be outlined.Comment: 6 pages, 11 figures XIII International Conference on Calorimetry in
High Energy Physic
- …