15,956 research outputs found
Effect of cooking on arsenic concentration in rice
This study assessed the effect of rinsing and boiling on total content of As (tAs) and of its inorganic and organic forms in different types of rice (polished and brown) from Spain and Ecuador. Rice was subjected to five different treatments. The results showed that the treatment consisting of three grain rinsing cycles followed by boiling in excess water showed a significant decrease in tAs content compared with raw rice. Regarding As species, it is worth noting that the different treatments significantly reduced the content of the most toxic forms of As. The estimated lifetime health risks indicate that pre-rinsing alone can reduce the risk by 50%, while combining it with discarding excess water can reduce the risk by 83%; therefore, the latter would be the preferable method.Universidad de las Fuerzas Armadas-ESPE through Project 2015- PIC-017, Xunta de Galicia-ConsellerÃa de Educación, Universidades e Formación Profesional, Plan Galego IDT, Consolidation of competitive research groups (ref. ED31C2018/12), and Cross-Research in Environmental Technologies (CRETUS, AGRUP2015/02, ref. 2018-PG100). XLOP is grateful for the financial support from the Proyecto PROMETEO (SENESCYT Ecuador).info:eu-repo/semantics/publishedVersio
Asymptotic normalization of mirror states and the effect of couplings
Assuming that the ratio between asymptotic normalization coefficients of
mirror states is model independent, charge symmetry can be used to indirectly
extract astrophysically relevant proton capture reactions on proton-rich nuclei
based on information on stable isotopes. The assumption has been tested for
light nuclei within the microscopic cluster model. In this work we explore the
Hamiltonian independence of the ratio between asymptotic normalization
coefficients of mirror states when deformation and core excitation is
introduced in the system. For this purpose we consider a phenomenological rotor
+ N model where the valence nucleon is subject to a deformed mean field and the
core is allowed to excite. We apply the model to 8Li/8B, 13C/13N, 17O/17F,
23Ne/23Al, and 27Mg/27P. Our results show that for most studied cases, the
ratio between asymptotic normalization coefficients of mirror states is
independent of the strength and multipolarity of the couplings induced. The
exception is for cases in which there is an s-wave coupled to the ground state
of the core, the proton system is loosely bound, and the states have large
admixture with other configurations. We discuss the implications of our results
for novae.Comment: 8 pages, 2 figures, submitted to PR
Energy dependence of non-local potentials
Recently a variety of studies have shown the importance of including
non-locality in the description of reactions. The goal of this work is to
revisit the phenomenological approach to determining non-local optical
potentials from elastic scattering. We perform a analysis of neutron
elastic scattering data off Ca, Zr and Pb at energies MeV, assuming a Perey and Buck or Tian, Pang, and Ma non-local
form for the optical potential. We introduce energy and asymmetry dependencies
in the imaginary part of the potential and refit the data to obtain a global
parameterization. Independently of the starting point in the minimization
procedure, an energy dependence in the imaginary depth is required for a good
description of the data across the included energy range. We present two
parameterizations, both of which represent an improvement over the original
potentials for the fitted nuclei as well as for other nuclei not included in
our fit. Our results show that, even when including the standard Gaussian
non-locality in optical potentials, a significant energy dependence is required
to describe elastic-scattering data.Comment: 6 pages, 3 figures, accepted by Phys. Rev. C Rapid Communicatio
Contextual Sensitivity in Grounded Theory: The Role of Pilot Studies
Grounded Theory is an established methodological approach for context specific inductive theory building. The grounded nature of the methodology refers to these specific contexts from which emergent propositions are drawn. Thus, any grounded theory study requires not only theoretical sensitivity, but also a good insight on how to design the research in the human activity systems to be studied. The lack of this insight may result in inefficient theoretical sampling or even erroneous purposeful sampling. These problems would not necessarily be critical, as it could be argued that through the elliptical process that characterizes grounded theory, remedial loops would always bring the researcher to the core of the theory. However, these elliptical remedial processes can take very long periods of time and result in catastrophic delays in research projects. As a strategy, this paper discusses, contrasts and compares the use of pilot studies in four different grounded theory projects. Each pilot brought different insights about the context, resulting in changes of focus, guidance to improve data collection instruments and informing theoretical sampling. Additionally, as all four projects were undertaken by researchers with little experience of inductive approaches in general and grounded theory in particular, the pilot studies also served the purpose of training in interviewing, relating to interviewees, memoing, constant comparison and coding. This last outcome of the pilot study was actually not planned initially, but revealed itself to be a crucial success factor in the running of the projects. The paper concludes with a theoretical proposition for the concept of contextual sensitivity and for the inclusion of the pilot study in grounded theory research designs
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