Some persistent misconceptions

As understanding of terrestrial noble gas geochemistry has evolved, various erroneous conclusions have persisted both within the field and in related fields. 

1) The very radiogenic Ar and Xe isotope ratios of the upper mantle demand early degassing of the mantle. This is a model-dependent conclusion based on the assumption that upper mantle noble gases are residual from atmosphere degassing. However, Xe isotope systematics precludes such a relationship (Ozima et al. 1985). Since other models, while not necessarily correct, can account for the observed Xe isotope variations, it is clear that the isotopic evidence can be interpreted in various ways. Nonetheless, early transfer of volatiles to the atmosphere probably did occur and was caused by impact degassing. 

2) Subduction of heavy noble gases must be very limited. This has been based on models of the isolation of the upper mantle or arguments about preservation of 

3) The processes that have dominantly formed the atmosphere continue at present. Although primordial noble gases continue to degas, their isotopic compositions do not match those of the atmosphere and limit their contribution to a small fraction of the present atmospheric inventory. Volatile species continue to be added to the atmosphere, but the dominant inputs occurred earlier. The formation of the atmosphere cannot be easily extrapolated from the present, but must be understood by quantitative modeling of past processes. 

There are, of course, many questions regarding terrestrial noble gases that remain to be explored. Some of the issues that are critical to making advances in global models of noble gas behavior are  

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The two main determinants for medicine deposition in the respiratory tract are the aerodynamic size distribution of the aerosol and the manoeuvre with which the aerosol is inhaled. They govern the mechanisms that are respraisible for particle deposition in the lungs. By varying the inhalation manoeuvre, not only the distribution in the airways for the same aerosol is changed in many cases also the amount and properties of the delivered fine particle dose are affected. The complex interplay between inhalation manoeuvre, aerosol properties and site of deposition has led to many misconceptions regarding the best inhaler choice for individual patients and the way these inhalers need to be operated to achieve optimal therapy for the patient. In this chapter the medicine deposition mechanisms for inhaled aerosols are explained as functions of the variables involved. In addition, the working principles of different inhaler types are described and it is discussed how their performance depends on many inhalation variables. Finally, some persistent misconceptions in the literature about the most preferable dry powder inhaler properties and performance are umaveUed. 

Most of the individual age data for mare samples are from Apollo 11, 12, 15, and 17, and these data gave rise to an early misconception (which still to some extent persists e.g., Snyder et al., 2000b) that among mare basalts, titanium content correlates with antiquity. If anything, the overall database, including photogeologic... 

On a final note, it is hoped that the contents of this book will serve to rectify some of the misconception that persist about the inadequacy of water as reaction medium, and that water will soon become a not only viable but also attractive option to the synthetic chemist in the planning of new synthetic processes. 

We now understand in more detail that fish immunity is at the crossroads between reliance of the innate and adaptive immunity (Tort et al, 2003 Huntingford et al, 2006). Some fish have the capacity to produce specific antibodies but the range of antibodies produced is far less diverse when compared with mammals or birds (Press, 1998). One relatively common misconception among non-specialists is that this reliance on the innate immunity is in some way less effective than a reliance on specific antibodies. The prevalence and diversity of invertebrates (98% of animal species) and fish (more than half of all vertebrates), in addition to their persistence through evolutionary history (Coelacanth relatively unchanged for 400 million years Johanson et al, 2006), demonstrate beyond any reasonable doubt that the innate immune system is very effective. 

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