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Biomedical subjects

M Victoria

Publications and source records attributed to M Victoria.

10 recordsLinked to original sources
PubMed2002

Computer simulation of displacement cascades in nanocrystalline ni.

Large-scale molecular dynamics of cascade production of the primary damage state are performed in fcc nanocrystalline Ni of average grain diameters of 5 and 12 nm. Primary knock-on atom kinetic energies of 5-30 keV are simulated. During the thermal spike phase, significant atomic motion towards the surrounding grain boundary structure is observed, characterized by many replacement-collision sequences. Upon resolidification, the excess volume condenses to form vacancy dominated defects with a complex partial dislocation network forming at higher energies.

Journal Article↗
PubMed2000

Multiscale modelling of plastic flow localization in irradiated materials

The irradiation of metals by energetic particles causes significant degradation of the mechanical properties, most notably an increased yield stress and decreased ductility, often accompanied by plastic flow localization. Such effects limit the lifetime of pressure vessels in nuclear power plants, and constrain the choice of materials for fusion-based alternative energy sources. Although these phenomena have been known for many years, the underlying fundamental mechanisms and their relation to the irradiation field have not been clearly demonstrated. Here we use three-dimensional multiscale simulations of irradiated metals to reveal the mechanisms underlying plastic flow localization in defect-free channels. We observe dislocation pinning by irradiation-induced clusters of defects, subsequent unpinning as defects are absorbed by the dislocations, and cross-slip of the latter as the stress is increased. The width of the plastic flow channels is limited by the interaction among opposing dislocation dipole segments and the remaining defect clusters.

Journal Article↗
PubMed1980

A comparative study of the old tuberculin tine test and the PPD-tine test.

Forty-one children suspected of having tuberculosis were simultaneously given an intermediate strength Mantoux test, an old tuberculin tine test (OT), and a purified protein derivative (PPD) tine test. Each test was read at 48 hours, and the largest diameter of induration was recorded. Twenty-nine patients had a positive reaction to the Mantoux test, 20 patients had a positive reaction to the OT tine test, and 16 patients had a positive reaction to the PPD-tine test. There were seven instances of a doubtful reaction to the OT tine test and nine to the PPD-tine test. Two children with positive Mantoux tests had negative OT tine tests, and four with positive Mantoux tests had negative PPD-tine test reactions. There was a significant difference between the number of positive reactors to the Mantoux test and both tine tests. If all tine test reactions of 2 mm or more were considered positive (doubtful plus positive reactors), there was no significant difference between any of the tuberculin tests. All suggestively positive tine reactors should, therefore, be retested with a Mantoux test to avoid false-negative interpretation of the tines.

Adolescent↗
PubMed1975

Cromolyn sodium in the treatment of children with asthma.

We have reported our experience with cromolyn sodium in the management of fifteen children with chronic, intractable asthma. The overall improvement in 80% of children is in accordance with some of the studies reported in the literature. The most significant effect of the drug was in either reducing the dose of steroid needed for management or eliminating its requirement by the patient.

Adolescent↗