5,768 research outputs found
Inference of mixed information in Formal Concept Analysis
Negative information can be considered twofold: by means
of a negation operator or by capturing the absence of information. In
this second approach, a new framework have to be developed: from the syntax to the semantics, including the management of such generalized knowledge representation. In this work we traverse all these issues in the framework of formal concept analysis, introducing a new set of inference rules to manage mixed (positive and negative) attributes.TIN2014-59471-P of the Science and Innovation
Ministry of Spain, co-funded by the European Regional Development Fund
(ERDF). UNIVERSIDAD DE MÁLAGA. Campus de Excelencia Internacional Andalucía Tech
Least action description of dynamic pairing correlations in the fission of Curium and Californium isotopes based on the Gogny energy density functional
The impact of dynamic pairing correlations and their interplay with Coulomb
antipairing effects on the systematic of the spontaneous fission half-lives for
the nuclei Cm and Cf is analyzed, using a hierarchy of
approximations based on the parametrization D1M of the Gogny energy density
functional (EDF). First, the constrained Hartree-Fock-Bogoliubov (HFB)
approximation is used to compute deformed mean-field configurations, zero-point
quantum corrections and collective inertias either by using the Slater
approximation to Coulomb exchange and neglecting Coulomb antipairing or by
fully considering the exchange and pairing channels of the Coulomb interaction.
Next, the properties of the {\it{least action}} and {\it{least energy}} fission
paths are compared. In the {\it{least action}} case, pairing is identified as
the relevant degree of freedom in order to minimize the action entering the
Wentzel-Kramers-Brillouin (WKB) approximation to the tunneling probability
through the fission barrier. Irrespective of the treatment of Coulomb exchange
and antipairing, it is shown that the {\it{least action}} path obtained taking
into account the pairing degree of freedom leads to stronger pairing
correlations that significantly reduce the spontaneous fission half-lives
improving thereby the comparison with the experiment by several orders
of magnitude. It is also shown that the Coulomb antipairing effect is, to a
large extent, washed out by the {\it{least action}} procedure and therefore the
values obtained by the two different treatments of the Coulomb
exchange and pairing are of similar quality.Comment: 13 pages, 8 figure
Symmetry-projected wave functions in quantum Monte Carlo calculations
We consider symmetry-projected Hartree-Fock trial wave functions in constrained-path Monte Carlo (CPMC) calculations. Previous CPMC calculations have mostly employed Hartree-Fock (HF) trial wave functions, restricted or unrestricted. The symmetry-projected HF approach results in a hierarchy of wave functions with increasing quality: the more symmetries that are broken and restored in a self-consistent manner, the higher the quality of the trial wave function. This hierarchy is approximately maintained in CPMC calculations: the accuracy in the energy increases and the statistical variance decreases when further symmetries are broken and restored. Significant improvement is achieved in CPMC with the best symmetry-projected trial wave functions over those from simple HF. We analyze and quantify the behavior using the two-dimensional repulsive Hubbard model as an example. In the sign-problem-free region, where CPMC can be made exact but a constraint is deliberately imposed here, spin-projected wave functions remove the constraint bias. Away from half filling, spatial symmetry restoration in addition to that of the spin leads to highly accurate results from CPMC. Since the computational cost of symmetry-projected HF trial wave functions in CPMC can be made to scale algebraically with system size, this provides a potentially general approach for accurate calculations in many-fermion systems
Ultimate response dynamics achieved with gas sensors based on self-heated nanowires
Bias current applied to conductometric gas sensors consisting of individual metal oxide nanowires can be used to heat them up to the temperature necessary for sensing. This approach in combination with the good sensitivity and stability of metal-oxide nanowires, can be used to develop prototypes with low power requirements (few tens of microwatts). Here, we present new sensors devices based on this approach that display fast dynamic performance only limited by the gas-solid interaction kinetics,. © 2009
Preparation of Dipteran Larvae for Scanning Electron Microscopy with Special Reference to Myiasigen Dipteran Species
Although controversy exists concerning the role of chemical fixatives in scanning electron microscopy (SEM) studies of Dipteran larvae, we have observed that filtered 10% formaldehyde solution gives excellent results as a preservative. After immersing in vivo in formaldehyde, the larvae material is preserved for prolonged periods (up to 8 months), before examination with SEM. As a fixative, formaldehyde preserves the structure of the larval cuticle and produces no visible artifacts. Moreover, postfixation is not necessary.
Due to pecularities of the way of life of Wohlfahrtia magnifica (principally the accumulations of necrotic tissue, purulent particles, and other types of substances that often adhere to the numerous spines of larvae), this species must be cleaned before examination by SEM. Manual cleaning with alternating bidistilled water and 0.9% saline solution proved to be a rapid, easy and inexpensive method that gave good results.
Both lyophilization drying and critical point drying were used before sputtering the material. While lyophilization drying proved to be the most effective method for instars II and III, critical point drying was the best technique for study of specimens belonging to instar I. The optimum time for drying and conditions for lyophilization and sputter-coating with gold were determined experimentally. Samples were mounted on SEM stubs with double-sided adhesive and silver conductive paint.
The method proposed is easy and effective for the SEM study of larvae myiasis-producing diptera
Meta-Analysis of the Impact of the Learning Curve in Robotic Rectal Cancer Surgery on Histopathologic Outcomes
Ethical challenges in genetic research among Philippine Indigenous Peoples: Insights from fieldwork in Zamboanga and the Sulu Archipelago
The Philippines, with the recent discovery of an archaic hominin in Luzon and an extensive ethnolinguistic diversity of more than 100 Indigenous peoples, is crucial to understanding human evolution and population history in Island Southeast Asia. Advances in DNA sequencing technologies enable the rapid generation of genomic data to robustly address questions about origins, relatedness, and population movements. With the increased genetic sampling in the country, especially by international scientists, it is vital to revisit ethical rules and guidelines relevant to conducting research among Indigenous peoples. Our team led fieldwork expeditions between 2019 and February 2020 in Zamboanga and the Sulu Archipelago, a chain of islands connecting the Mindanao and Borneo landmasses. The trips concluded with a collection of 2,149 DNA samples from 104 field sites. We present our fieldwork experience among the mostly sea-oriented Sama-Bajaw and Tausug-speaking communities and propose recommendations to address the ethical challenges of conducting such research. This work contributes toward building an enabling research environment in the Philippines that respects the rights and autonomy of Indigenous peoples, who are the rightful owners of their DNA and all genetic information contained therein
A protocol for measuring cassava bacterial blight disease progression, using machine-learning image analysis
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