4,347 research outputs found
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
Antiproton modulation in the Heliosphere and AMS-02 antiproton over proton ratio prediction
We implemented a quasi time-dependent 2D stochastic model of solar modulation
describing the transport of cosmic rays (CR) in the heliosphere. Our code can
modulate the Local Interstellar Spectrum (LIS) of a generic charged particle
(light cosmic ions and electrons), calculating the spectrum at 1AU. Several
measurements of CR antiparticles have been performed. Here we focused our
attention on the CR antiproton component and the antiproton over proton ratio.
We show that our model, using the same heliospheric parameters for both
particles, fit the observed anti-p/p ratio. We show a good agreement with
BESS-97 and PAMELA data and make a prediction for the AMS-02 experiment
First evidence of protein modulation by polystyrene microplastics in a freshwater biological model
Microplastics (MPs)are now one of the major environmental problems due to the large amount released in aquatic and terrestrial ecosystems, as well as their diffuse sources and potential impacts on organisms and human health. Still the molecular and cellular targets of microplastics\u2019 toxicity have not yet been identified and their mechanism of actions in aquatic organisms are largely unknown. In order to partially fill this gap, we used a mass spectrometry based functional proteomics to evaluate the modulation of protein profiling in zebra mussel (Dreissena polymorpha), one of the most useful freshwater biological model. Mussels were exposed for 6 days in static conditions to two different microplastic mixtures, composed by two types of virgin polystyrene microbeads (size = 1 and 10 \u3bcm)each one. The mixture at the lowest concentration contained 5
7 105 MP/L of 1 \u3bcm and 5
7 105 MP/L of 10 \u3bcm, while the higher one was arranged with 2
7 106 MP/L of 1 \u3bcm and 2
7 106 MP/L of 10 \u3bcm. Proteomics\u2019 analyses of gills showed the complete lack of proteins\u2019 modulation after the exposure to the low-concentrated mixture, while even 78 proteins were differentially modulated after the exposure to the high-concentrated one, suggesting the presence of an effect-threshold. The modulated proteins belong to 5 different classes mainly involved in the structure and function of ribosomes, energy metabolism, cellular trafficking, RNA-binding and cytoskeleton, all related to the response against the oxidative stress
Latitudinal Dependence of Cosmic Rays Modulation at 1 AU and Interplanetary-Magnetic-Field Polar Correction
The cosmic rays differential intensity inside the heliosphere, for energy
below 30 GeV/nuc, depends on solar activity and interplanetary magnetic field
polarity. This variation, termed solar modulation, is described using a 2-D
(radius and colatitude) Monte Carlo approach for solving the Parker transport
equation that includes diffusion, convection, magnetic drift and adiabatic
energy loss. Since the whole transport is strongly related to the
interplanetary magnetic field (IMF) structure, a better understanding of his
description is needed in order to reproduce the cosmic rays intensity at the
Earth, as well as outside the ecliptic plane. In this work an interplanetary
magnetic field model including the standard description on ecliptic region and
a polar correction is presented. This treatment of the IMF, implemented in the
HelMod Monte Carlo code (version 2.0), was used to determine the effects on the
differential intensity of Proton at 1\,AU and allowed one to investigate how
latitudinal gradients of proton intensities, observed in the inner heliosphere
with the Ulysses spacecraft during 1995, can be affected by the modification of
the IMF in the polar regions.Comment: accepted for publication inAdvances in Astronom
Proton Modulation in the Heliosphere for Different Solar Conditions and Prediction for AMS-02
Spectra of Galactic Cosmic Rays (GCRs) measured at the Earth are the
combination of several processes: sources production and acceleration,
propagation in the interstellar medium and propagation in the heliosphere.
Inside the solar cavity the flux of GCRs is reduced due to the solar
modulation, the interaction which they have with the interplanetary medium. We
realized a 2D stochastic simulation of solar modulation to reproduce CR spectra
at the Earth, and evaluated the importance in our results of the Local
Interstellar Spectrum (LIS) model and its agreement with data at high energy.
We show a good agreement between our model and the data taken by AMS-01 and
BESS experiments during periods with different solar activity conditions.
Furthermore we made a prediction for the flux which will be measured by AMS-02
experiment.Comment: Accepted for publication in the Proceedings of the ICATPP Conference
on Cosmic Rays for Particle and Astroparticle Physics, Villa Olmo (Como,
Italy), 7-8 October, 2010, to be published by World Scientific (Singapore
Point clouds turned into finite elements: The umbrella vault of Castel Masegra
The paper presents a workflow for finite element model generation from point clouds acquired via photogrammetry and laser scanning. The case study is a room with an umbrella vault in Castel Masegra, located in Sondrio (Italy). The complexity of the room required an accurate geometric survey from a set of dense point clouds, from which a detailed BIM as well as 2D drawings were generated. Finally, a tetrahedral mesh was derived from the geometric model and was used to run a finite element analysis. The aim of this work is to describe the procedure developed and illustrate the main challenges found
Suprathermal particle addition to solar wind pressure: possible influence on magnetospheric transmissivity of low energy cosmic rays?
Energetic (suprathermal) solar particles, accelerated in the interplanetary
medium, contribute to the solar wind pressure, in particular during high solar
activity periods. We estimated the effect of the increase of solar wind
pressure due to suprathermal particles on magnetospheric transmissivity of
galactic cosmic rays in the case of one recent solar event
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