3,876 research outputs found
Contribution to diffuse gamma-ray emission coming from self-confined CRs around their Galactic sources
Recent observations of the diffuse Galactic gamma-ray emission by the
Fermi-LAT satellite have shown significant deviations from models which assume
the same diffusion properties for cosmic rays (CR) throughout the Galaxy. We
explore the possibility that a fraction of this diffuse Galactic emission could
be due to hadronic interactions of CRs self-confined in the region around their
sources. In fact, freshly accelerated CRs that diffuse away from the
acceleration region can trigger the streaming instability able to amplify
magnetic disturbance and to reduce the particle diffusion. When this happen,
CRs are trapped in the near source region for a time longer than expected and
an extended gamma-ray halo is produces around each source. Here we calculate
the contribution to the diffuse gamma-ray background due to the overlap along
lines of sight of several of these extended halos. We find that if the density
of neutrals is low, the halos can account for a substantial fraction of the
diffuse emission observed by Fermi-LAT, depending on the orientation of the
line of sight with respect to the direction of the galactic center.Comment: 8 pages, 2 figs. Proceeding the 35th International Cosmic Ray
Conference (ICRC2017), Bexco, Busan, Kore
Identifying Nearby UHECR Accelerators using UHE (and VHE) Photons
Ultra-high energy photons (UHE, E > 10^19 eV) are inevitably produced during
the propagation of 10^20 eV protons in extragalactic space. Their short
interaction lengths (<20 Mpc) at these energies, combined with the impressive
sensitivity of the Pierre Auger Observatory detector to these particles, makes
them an ideal probe of nearby ultra-high-energy cosmic ray (UHECR) sources. We
here discuss the particular case of photons from a single nearby (within 30
Mpc) source in light of the possibility that such an object might be
responsible for several of the UHECR events published by the Auger
collaboration. We demonstrate that the photon signal accompanying a cluster of
a few > 6x10^19 eV UHECRs from such a source should be detectable by Auger in
the near future. The detection of these photons would also be a signature of a
light composition of the UHECRs from the nearby source.Comment: 4 pages, 2 figures, accepted for publication in PR
Vector Supersymmetry of 2D Yang-Mills Theory
The vector supersymmetry of the 2D topological BF model is extended to 2D
Yang-Mills. The consequences of the corresponding Ward identity on the
ultraviolet behavior of the theory are analyzed.Comment: Some references adde
On Particle Acceleration around Shocks. III. Shock Waves Moving at Arbitrary Speed. The Case of Large-Scale Magnetic Field and Anisotropic Scattering
A mathematical approach to investigate particle acceleration at shock waves moving at arbitrary speed in a medium with arbitrary scattering properties was first discussed in work by Vietri and Blasi. We use this method and somewhat extend it in order to include the effect of a large-scale magnetic field in the upstream plasma, with arbitrary orientation with respect to the direction of motion of the shock. We also use this approach to investigate the effects of anisotropic scattering on spectra and anisotropies of the distribution function of the accelerated particles
EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions III. The flux-limited sample
Theoretical simulations and observations at different angular resolutions
have shown that magnetic fields have a central role in massive star formation.
Like in low-mass star formation, the magnetic field in massive young stellar
objects can either be oriented along the outflow axis or randomly. Measuring
the magnetic field at milliarcsecond resolution (10-100 au) around a
substantial number of massive young stellar objects permits determining with a
high statistical significance whether the direction of the magnetic field is
correlated with the orientation of the outflow axis or not. In late 2012, we
started a large VLBI campaign with the European VLBI Network to measure the
linearly and circularly polarized emission of 6.7 GHz methanol masers around a
sample of massive star-forming regions. This paper focuses on the first seven
observed sources, G24.78+0.08, G25.65+1.05, G29.86-0.04, G35.03+0.35,
G37.43+1.51, G174.20-0.08, and G213.70-12.6. For all these sources, molecular
outflows have been detected in the past. We detected a total of 176 methanol
masing cloudlets toward the seven massive star-forming regions, 19% of which
show linearly polarized emission. The methanol masers around the massive young
stellar object MM1 in G174.20-0.08 show neither linearly nor circularly
polarized emission. The linear polarization vectors are well ordered in all the
other massive young stellar objects. We measured significant Zeeman splitting
toward both A1 and A2 in G24.78+0.08, and toward G29.86-0.04 and G213.70-12.6.
By considering all the 19 massive young stellar objects reported in the
literature for which both the orientation of the magnetic field at
milliarcsecond resolution and the orientation of outflow axes are known, we
find evidence that the magnetic field (on scales 10-100 au) is preferentially
oriented along the outflow axes.Comment: 17 pages, 10 figures, 9 tables, accepted by Astronomy & Astrophysics.
arXiv admin note: text overlap with arXiv:1306.633
General Solution Of Linear Vector Supersymmetry
We give the general solution of the Ward identity for the linear vector
supersymmetry which characterizes all topological models. Such solution, whose
expression is quite compact and simple, greatly simplifies the study of
theories displaying a supersymmetric algebraic structure, reducing to a few
lines the proof of their possible finiteness. In particular, the cohomology
technology usually involved for the quantum extension of these theories, is
completely bypassed. The case of Chern-Simons theory is taken as an example.Comment: 18 pages, LaTeX, no figure
Magic mirror on the wall: Selfie-related behavior as mediator of the relationship between narcissism and problematic smartphone use
Objective: Recent research has suggested that problematic smartphone use is associated with several psychological factors and that mobile apps and smartphone-related behavior (i.e. selfi e behavior) may encourage the development of problematic smartphone use. However, little is known about how the interplay between dysfunctional personality characteristics and selfi e-related behavior can infl uence problematic smartphone use. The aim of this study was to examine the relationship between narcissism and problematic smartphone use, as well as the mediating role of selfi e-related behavior in this relationship among young men and women. Method: In the current study, a total of 627 undergraduate students (283 males and 344 females) completed a cross-sectional survey. A structural equation model was tested separately for males and females in order to evaluate the associations between narcissism, selfi e-related behavior and problematic smartphone use. Results: The results showed that greater narcissism was related to increased selfi e-related behavior, which in turn were positively associated with problematic smartphone use both for males and females. However, selfi e-related behavior mediated the relationship between narcissism and problematic smartphone use only for females. Conclusions: The study provides fresh insight into our understanding of the psychological mechanisms underlying problematic smartphone use, which may inform prevention and treatment interventions
The Ventasso Horse: genetic characterization by microsatellites markers
The genetic structure of Ventasso Horse (VH) was investigated using 12 microsatellites. The analyses were carried out on 117 VH individuals and the results were compared with those obtained analysing 11 other breeds reared in Italy. All microsatellites were polymorphic in VH and in the other breeds. A total of 124 alleles (from 6 to 19 alleles per microsatellite) were detected. Average heterozygosity was 0.743 in VH and ranged from 0.613 to 0.759 in the other breeds. The mean FST value had an average value of 0.0932. Genetic distances were calculated using Nei's standard genetic distance (Ds). The smallest Ds values were found between VH and Anglo-Arab, Thoroughbred, Maremmano and Lipizzan horse breeds. Phylogenetic trees constructed using neighbour-joining method showed two clear separate clusters: the first includes Bardigiano, Haflinger and Italian Heavy Draught Horse, the second contains the other 9 breeds
The tailor-made treatment in a particular case of pulmonary hypertension in thalassaemia intermedia: A case report
Background: Pulmonary hypertension (PH) is a haemodynamic condition, secondary to different causes. Thalassaemia may lead to PH of different origin and needs a comprehensive analysis to be correctly characterized and possibly treated. Case summary: We present a case study of a patient with a non-transfusion-dependent thalassaemia and a previous diagnosis of group 5 PH. A complete diagnostic assessment led to a specific diagnosis of chronic thromboembolic PH. Thus, we were able to start a specific therapy with riociguat that provided an improvement in terms of haemodynamic, imaging, and functional status. Discussion: A correct characterization and treatment of PH are essential in order to change the patient's prognosis. Chronic thromboembolic PH is a treatable cause of PH in thalassemic patients and should be investigated
Quasistationary quaternionic Hamiltonians and complex stochastic maps
We show that the complex projections of time-dependent -quasianti-Hermitian quaternionic Hamiltonian dynamics are complex stochastic
dynamics in the space of complex quasi-Hermitian density matrices if and only
if a quasistationarity condition is fulfilled, i. e., if and only if is
an Hermitian positive time-independent complex operator. An example is also
discussed.Comment: Submitted to J. Phys. A on October 25 200
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