4,554 research outputs found
Alien Registration- Della Torre, Ormond A. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/24554/thumbnail.jp
Possible Contribution to Electron and Positron Fluxes from Pulsars and their Nebulae
The AMS-02 experiment confirms the excess of positrons in cosmic rays (CRs)
for energy above 10 GeV with respect to the secondary production of positrons
in the interstellar medium. This is interpreted as evidence of the existence of
a primary source of these particles. Possible candidates are dark matter or
astrophysical sources. In this work we discuss the possible contribution due to
pulsars and their nebulae. Our key assumption is that the primary spectrum of
electrons and positrons at the source is the same of the well known photon
spectrum observed from gamma-rays telescopes. Using a diffusion model in the
Galaxy we propagate the source spectra up to the Solar System. We compare our
results with the recent experiments and with the LIS modelComment: To appear in the Proceedings of the 14th ICATPP Conference, Villa
Olmo 23-27 September 201
Pulsar Wind Nebulae as a source of the observed electron and positron excess at high energy: the case of Vela-X
We investigate, in terms of production from pulsars and their nebulae, the
cosmic ray positron and electron fluxes above GeV, observed by the
AMS-02 experiment up to 1 TeV. We concentrate on the Vela-X case. Starting from
the gamma-ray photon spectrum of the source, generated via synchrotron and
inverse Compton processes, we estimated the electron and positron injection
spectra. Several features are fixed from observations of Vela-X and unknown
parameters are borrowed from the Crab nebula. The particle spectra produced in
the pulsar wind nebula are then propagated up to the Solar System, using a
diffusion model. Differently from previous works, the omnidirectional intensity
excess for electrons and positrons is obtained as a difference between the
AMS-02 data and the corresponding local interstellar spectrum. An equal amount
of electron and positron excess is observed and we interpreted this excess
(above 100 GeV in the AMS-02 data) as a supply coming from Vela-X. The
particle contribution is consistent with models predicting the gamma-ray
emission at the source. The input of a few more young pulsars is also allowed,
while below 100 GeV more aged pulsars could be the main contributors.Comment: Accepted for publication in Journal of High Energy Astrophysics
(2015
CFD investigation of the radiative heat transfer effects on the adoption of an electrical heated catalyst to increase the abatement efficiency
Molecular evidence of incipient speciation within Anopheles gambiae s.s. in West Africa
We karyotyped and identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis Anopheles gambiae s.s. samples collected in several African countries. The data show the existence of two non-panmictic molecular forms, named S and M, whose distribution extended from forest to savannahs, Mosquitoes of the S and M forms are homosequential standard for chromosome-2 inversions in forest areas. In dry savannahs, S is characterized mainly by inversion polymorphisms typical of Savanna and Bamako chromosomal forms, while M shows chromosome-2 arrangements typical of Mopti and/or Savanna and/or Bissau, depending on its geographical origin. Chromosome-2 inversions therefore seem to be involved in ecotypic adaptation rather than in mate-recognition systems. Strong support for the reproductive isolation of S and M in Ivory Coast comes from the observation that the kdr allele is found at high frequencies in S specimens and not at all in chromosomal identical M specimens. However, the kdr allele does not segregate with molecular forms in Benin
CFD characterization of flow regimes inside open cell foam substrates
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.In this work a combination of micro-CT, image-based modeling and CFD has been applied to investigate the pressure drop in open-cell foams. The analysis covers a range of flow regimes and is aimed at determining the effects of important morphological parameters on the pressure drop. The adoption of micro-CT technology along with detailed CFD modeling allows the investigation of phenomena occurring in real foam micro-structures. Moreover, by means of image processing tools, the geometry can be artificially modified in order to investigate the effects of mathematical transformation of the geometrical parameters of a real foam, one parameter at a time, e.g. varying pore size without affecting the porosity. Non-dimensional coefficients have been defined for the analysis of the results, with the purpose of describing the pressure drop as a function of the Reynolds number. The proposed formulation allows us to relate the permeability properties of an open-cell foam to its morphology alone, without any dependence on the properties of the fluid adopted or on the effective characteristic dimension of the foam micro-structure (pore or cell size). Comparison with experimental results available in the literature is also provided for one of the cases studied
A preliminary computational analysis towards the use of Electrically Heated Mixing Catalyst for innovative SCR after-treatment systems
Classification of multi-layered plaster in St. Abbondio Cloister at Como, Italy: an analytical tool for architectural archaeology
Spatial and temporal hot spots of Aedes albopictus abundance inside and outside a South European metropolitan area
Aedes albopictus is a tropical invasive species which in the last decades spread worldwide,
also colonizing temperate regions of Europe and US, where it has become a public health
concern due to its ability to transmit exotic arboviruses, as well as severe nuisance problems
due to its aggressive daytime outdoor biting behaviour. While several studies have
been carried out in order to predict the potential limits of the species expansions based on
eco-climatic parameters, few studies have so far focused on the specific effects of these
variables in shaping its micro-geographic abundance and dynamics. The present study
investigated eco-climatic factors affecting Ae. albopictus abundance and dynamics in metropolitan
and sub-urban/rural sites in Rome (Italy), which was colonized in 1997 and is nowadays
one of the most infested metropolitan areas in Southern Europe. To this aim,
longitudinal adult monitoring was carried out along a 70 km-transect across and beyond the
most urbanized and densely populated metropolitan area. Two fine scale spatiotemporal
datasets (one with reference to a 20m circular buffer around sticky traps used to collect
mosquitoes and the second to a 300m circular buffer within each sampling site) were
exploited to analyze the effect of climatic and socio-environmental variables on Ae. albopictus
abundance and dynamics along the transect. Results showed an association between
highly anthropized habitats and high adult abundance both in metropolitan and sub-urban/
rural areas, with “small green islands” corresponding to hot spots of abundance in the metropolitan
areas only, and a bimodal seasonal dynamics with a second peak of abundance in
autumn, due to heavy rains occurring in the preceding weeks in association with permissive
temperatures. The results provide useful indications to prioritize public mosquito control
measures in temperate urban areas where nuisance, human-mosquito contact and risk of
local arbovirus transmission are likely higher, and highlight potential public health risks also
after the summer months typically associated with high mosquito densities
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