1,424 research outputs found
Experimental test for interpreting the increase in sensibility of doped CR-39
In recent years the sensibility of CR-39 to nuclear tracks has been increased by doping the corresponding monomer with dioctyl phtalate. At this regard, two theoretical approaches are current managed to explain this phenomenon: either the doping react with the active radicals in the chain blocking them, stopping crosslinking between chains, or alternatively that the doping gets between them giving wider space between the crosslinkined chains
Study of non-thermal photon production under different scenarios in solar flares. 2: The Compton inverse and Bremsstrahlung models and fittings
Energy spectra of photons emitted from Bremsstrahlung (BR) of energetic electrons with matter, is obtained from the deconvolution of the electron energy spectra. It can be inferred that the scenario for the production of X-rays and gamma rays in solar flares may vary from event to event. However, it is possible in many cases to associated low energy events to impulsive acceleration, and the high energy phase of some events to stochastic acceleration. In both cases, flare particles seem to be strongly modulated by local energy losses. Electric field acceleration, associated to neutral current sheets is a suitable candidate for impulsive acceleration. Finally, that the predominant radiation process of this radiation is the inverse Compton effect due to the local flare photon field
Study of photon emission by electron capture during solar nuclei acceleration, 1: Temperature-dependent cross section for charge changing processes
The study of charge changing cross sections of fast ions colliding with matter provides the fundamental basis for the analysis of the charge states produced in such interactions. Given the high degree of complexity of the phenomena, there is no theoretical treatment able to give a comprehensive description. In fact, the involved processes are very dependent on the basic parameters of the projectile, such as velocity charge state, and atomic number, and on the target parameters, the physical state (molecular, atomic or ionized matter) and density. The target velocity, may have also incidence on the process, through the temperature of the traversed medium. In addition, multiple electron transfer in single collisions intrincates more the phenomena. Though, in simplified cases, such as protons moving through atomic hydrogen, considerable agreement has been obtained between theory and experiments However, in general the available theoretical approaches have only limited validity in restricted regions of the basic parameters. Since most measurements of charge changing cross sections are performed in atomic matter at ambient temperature, models are commonly based on the assumption of targets at rest, however at Astrophysical scales, temperature displays a wide range in atomic and ionized matter. Therefore, due to the lack of experimental data , an attempt is made here to quantify temperature dependent cross sections on basis to somewhat arbitrary, but physically reasonable assumptions
Beyond Mean Field Confrontation of Different Models with High Transverse Momentum Proton Spectra
Several models have been proposed to simulate heavy ion reactions beyond the
mean field level. The lack of data in phase space regions which may be
sensitive to different treatments of fluctuations made it difficult to judge
these approaches. The recently published high energy proton spectra, measured
in the reaction 94 AMeV Ar + Ta, allow for the first time for a comparison of
the models with data. We find that these spectra are reproduced by Quantum
Molecular Dynamics (QMD) and Boltzmann Uehling Uhlenbeck (BUU) calculations.
Models like Boltzmann Langevin (BL) in which additional fluctuations in
momentum space are introduced overpredict the proton yield at very high
energies. The BL approach has been successfully used to describe the recently
measured very subthreshold kaon production assuming that the fluctuations
provide the necessary energy to overcome the threshold in two body collisions.
Our new findings suggest that the very subthreshold kaon production cannot be
due to two body scattering and thus remains a open problem.Comment: 5 pages, 3 figures (eps), revte
A simple thermodynamical witness showing universality of macroscopic entanglement
We show that if the ground state entanglement exceeds the total entropy of a
given system, then this system is in an entangled state. This is a universal
entanglement witness that applies to any physical system and yields a
temperature below which we are certain to find some entanglement. Our witness
is then applied to generic bosonic and fermionic many body systems to derive
the corresponding "critical" temperatures that have a very broad validity.Comment: 3 pages, Torun conference, June 25-28, 200
Switching to lanthanum carbonate monotherapy provides effective phosphate control with a low tablet burden
Background. Despite recognized risks associated with hyperphosphataemia in patients with chronic kidney disease (CKD) Stage 5 on dialysis, the achievement of target levels of serum phosphate is poor. It is likely that this is partly due to poor adherence by patients to their phosphate-binder treatment regimens, which often comprise large daily tablet burdens
Morphotectonic evolution of the Jebel Bou Naceur in the South Middle Atlas Fault Zone (Morocco)
International audienceIn eastern Morocco, fault-related folds develop above the South Middle Atlas fault that separates the J. Bou Naceur 'pop-up' structure and the Missour Basin, filled with alluvial sediments. Using a combination of surfaces, field observations and digital topographic information, we have investigated several geomorphic criteria and geometry of depositional surfaces governed by the relief's growth. The propagation of the deformation is recorded by warped segmented fans that moved southeastward and wellpreserved geomorphological features of tectonic origin. Uplift of the anticline hinges and acceleration of valley incision since the Late Pliocene are considered a consequence of the ongoing NW-SE convergence between Africa and Eurasia. A scenario of morphotectonic evolution of this active mountain front is proposed
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