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Biomedical subjects

M Lilley

Publications and source records attributed to M Lilley.

6 recordsLinked to original sources
PubMed2003

Large particle number limit in rain.

The way we conceptualize rain is fundamental in many branches of science since it provides the basis not only for rain modeling notably in meteorology and hydrology, but also for interpreting rain data (from gauges and radars). In order to empirically address this question, we use stereophotographic data to measure the positions and volumes of raindrops from approximately 10 m(3) regions containing 5000-15,000 of these drops. By determining the drop statistics in spheres of increasing size, we conduct a basic continuum mechanics thought experiment. We show that-presumably due to turbulence-there is no microscale-macroscale separation. We find that the large particle number (N) limit in rain is not a homogeneous continuum, but rather it is nonclassical, strongly inhomogeneous, and approaching a multifractal discontinuum.

Journal Article↗
PubMed1991

Composite materials for x-ray protection.

We have developed and tested a radiation protection material that provides similar attenuation for diagnostic x-ray spectra to that of conventional Pb apron materials with approximately 30% reduced weight. By combining a number of elements with different K absorption energies, such as Ba, W, and Pb, energy attenuation for given spectra can be optimized with respect to total cross-sectional mass loading. Alternatively, garments with much higher protective factors at equivalent weight to conventional garments could be produced. The reduction in the amount of Pb used also reduces problems associated with the toxicity of the material during manufacture and disposal. Back strain can be reduced for personnel performing special radiological procedures that require wearing protective garments for long periods of time.

Barium↗
PubMed1980

Purification of the insecticidal toxin in crystals of Bacillus thuringiensis.

Crystals were purified from four serotypes of the insect pathogen Bacillus thuringiensis. Crystals from these serotypes were similar in amino acid and N-terminal analyses, but differed in their toxicity to two species of Lepidoptera and in their immunological properties. Toxic polypeptides were obtained following trypsin digestion of solutions of the crystals. In two strains (serotypes 3 and 9) this fraction contained only one polypeptide. Similar results were obtained when dissolved crystals were digested with other proteolytic enzymes or with gut contents from Pieris brassicae. The trypsin-resistant polypeptide was further purified by gel and ion-exchange chromatograhy and had a molecular weight of about 70,000, estimated by gel chromatogrpahy and gel electrophoresis. No evidence was obtained for a toxin of lower molecular weight. This purified toxin accounted for most, if not all, of the toxic activity originally present in the crystal solution and was active by injection and ingestion. The purified toxic fraction from serotype 1 appeared to contain two polypeptides, one of which corresponded to that found with serotypes 3 and 9. There were no major differences in the composition of crystals from different serotypes of B. thuringiensis and it is concluded that the trypsin-resistant polypeptide represents the active insecticidal toxin of the crystal.

Amino Acids↗