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Biomedical subjects

M Anbar

Publications and source records attributed to M Anbar.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Determination of the concentration of explosives in air by isotope dilution analysis.

The concentrations in air of dinitrotoluene (DNT), trinitrotoluene (TNT), nitroglycerin (NG), ethylene glycol dinitrate (EGDN), and pentaerythritol tetranitrate (PETN) were measured at 25 degrees C under equilibrium conditions, and that of cyclomethylene trinitramine (RDX) was measured at elevated temperature by means of an isotope dilution technique. Isotopically multi-labeled compounds were synthesized and used as diluents. Field ionization mass spectrometry was used to measure the abundance ratios of the unlabeled materials. The concentrations in air at 25 degrees C of DNT, TNT, NG, EDGN, PETN, and RDX are 184, 4, 31, 37,000, 7, and 0.8 ppb v/v, respectively. The data obtained may be used for the assessment of the required sensitivity of air-monitoring detection systems.

Air Pollutants↗
PubMedDate not supplied

Identification of nitric oxide (NO) in human blood.

The amount of nitric oxide (NO) in the blood of residents of urban and suburban areas was measured under steady-state conditions by isotopic dilution with N15O, followed by field-ionization mass spectrometry. Approximately 20 nmoles of NO per ml of blood was characteristic of both smokers and nonsmokers, except for one of the eight subjects who had a significantly lower level. Monkeys (Macaca speciosa) had values comparable to those of seven human subjects, and rats had values like that of the unique human subject. Whether the origin of the NO was endogenous or exogenous was not determined.

Animals↗
PubMedDate not supplied

What is life?

Life is a composite process in nature that is as fundamental as the laws of physics that govern the behavior of the inanimate world. The laws of physics change qualitatively as we go from the macroscopic to the atomic and subatomic domains. Likewise, the behavior of living systems changes dramatically when a certain level of complexity, including social organization, has been reached. Moreover, live systems may change the projected course of the inanimate world, as they are already doing on our tiny planet. In brief, life does not only "make the world turn around," it can do this for the whole universe. Consequently, life is probably the most significant process in nature; it is also the least predictable. The behavior of live systems is unpredictable. Unlike the inanimate universe that can be readily modeled using a limited number of parameters, the perpetually increasing complexity of living systems defies modeling. If we would have used all the information available about the behavior of live systems on this planet just five million years ago, we could never have come up with a model describing human civilization of today. Such a prediction would have been, obviously, much harder if we knew everything about living systems on this planet five hundred million years ago. The nonpredictability of the behavior of living systems is not solely due to its stochastic nature. The behavior of live systems is unpredictable because it is based on interactions among millions of independent or partially dependent stochastic processes involving both live and inanimate systems. The number of different pathways constituting such behavior is virtually infinite. This makes the predictability of such behavior qualitatively different from that of conventional stochastic behavior, which is based on a finite number of parameters, each with a finite number of degrees of freedom. Furthermore, unlike statistical mechanics, which are applicable to inanimate systems, the behavior of living systems cannot be delimited by an analog to Heisenberg's uncertainty principle. The answer to the question "What is life?" is, in brief: Life is a multifunctional process in nature that is as fundamental as the basic "laws" of physics, used to model the behavior of the inanimate world. Like those "laws," life can control the behavior of our universe, including its lifespan.

Biological Evolution↗