Accounting for differences in the bioactivity and bioavailability of vitamers

Essentially all vitamins exist with multiple nutritionally active chemical species often called vitamers. Our quantitative understanding of the bioactivity and bioavailability of the various members of each vitamin family has increased markedly, but many issues remain to be resolved concerning the reporting and use of analytical data. Modern methods of vitamin analysis rely heavily on chromatographic techniques that generally allow the measurement of the individual chemical forms of vitamins. Typical applications of food analysis include the evaluation of shelf life and storage stability, monitoring of nutrient retention during food processing, developing food composition databases and data needed for food labeling, assessing dietary adequacy and evaluating epidemiological relationships between diet and disease. Although the usage of analytical data varies depending on the situation, important issues regarding how best to present and interpret the data in light of the presence of multiple vitamers are common to all aspects of food analysis. In this review, we will evaluate the existence of vitamers that exhibit differences in bioactivity or bioavailability, consider when there is a need to address differences in bioactivity or bioavailability of vitamers, and then consider alternative approaches and possible ways to improve the reporting of data. Major examples are taken from literature and experience with vitamin B6 and folate

Essay: Iran and the Military Option

When politicians, pundits, and prognosticators discuss the military option for Iran it is important to understand that it will in all likelihood result in a full scale international armed conflict. If the military option mission is to eliminate Iran\u27s nuclear capabilities, there is no one target to destroy, bomb, or obliterate that will render Iran\u27s nuclear program dead therefore making such an option unlikely to be quick or efficient. A conflict with Iran would involve an extensive air campaign and probably result in Iran launching missiles at Israel and Eastern Europe. The Persian Gulf would effectively be closed off as a result of maritime combat and the worldwide threat of terrorist attacks would have far reaching consequences. The cost of armed conflict with Iran is incalculable with the potential to further destabilize the region as well as the global economy

Aerosols from biomass burning over the tropical South Atlantic region: Distributions and impacts

The NASA Global Tropospheric Experiment (GTE) Transport and Atmospheric Chemistry Near the Equator-Atlantic (TRACE A) expedition was conducted September 21 through October 26, 1992, to investigate factors responsible for creating the seasonal South Atlantic tropospheric ozone maximum. During these flights, fine aerosol (0.1-3.0 μm) number densities were observed to be enhanced roughly tenfold over remote regions of the tropical South Atlantic and greater over adjacent continental areas, relative to northern hemisphere observations and to measurements recorded in the same area during Ac wet season. Chemical and meteorological analyses as well as visual observations indicate that the primary source of these enhancements was biomass burning occurring within grassland regions of north central Brazil and southeastern Africa. These fires exhibited fine aerosol (N) emission ratios relative to CO (dN/dCO) of 22.5 ± 9.7 and 23.6 ± 15.1 cm-3 parts per billion by volume (ppbv)-1 over Brazil and Africa, respectively. Convection coupled with counterclockwise flow around the South Atlantic subtropical anticyclone subsequently distributed these aerosols throughout the remote South Atlantic troposphere. We calculate that dilute smoke from biomass burning produced an average tenfold enhancement in optical depth over the continental regions as well as a 50% increase in this parameter over the middle South Atlantic Ocean; these changes correspond to an estimated net cooling of up to 25 W m-2 and 2.4 W m-2 during clear-sky conditions over savannas and ocean respectively. Over the ocean our analyses suggest that modification of CCN concentrations within the persistent eastern Atlantic marine stratocumulus clouds by entrainment of subsiding haze layers could significantly increase cloud albedo resulting in an additional surface radiative cooling potentially greater in magnitude than that caused by direct extinction of solar radiation by the aerosol particles themselves

Understanding the Changing Nature of Cluster Drivers

Many cluster examples from around the world offerinsights into cluster success, however there is relatively much lessattention given to the factors which drive the development andexistence of clusters. This paper examines cluster driversreported as part of the cluster literature, as well as examiningcluster drivers identified within the Australian AerospaceCluster. The findings of this research outline that existing clusterliterature offers a somewhat static view of cluster drivers thatdoes not adequately capture the impact of complex interrelationshipswhich exist between cluster drivers. The paperidentifies a number of inter-relationships between cluster driverswithin the Australian Aerospace Cluster