Recently disturbed and ‘control’ (i.e. less recently disturbed) soils in the Mojave Desert were compared for their vulnerability to wind erosion, using a wind tunnel, before and after being experimentally trampled. Before trampling, control sites had greater cyanobacterial biomass, soil surface stability, threshold friction velocities (TFV; i.e. the wind speed required to move soil particles), and sediment yield than sites that had been more recently disturbed by military manoeuvres. After trampling, all sites showed a large drop in TFVs and a concomitant increase in sediment yield. Simple correlation analyses showed that the decline in TFVs and the rise in sediment yield were significantly related to cyanobacterial biomass (as indicated by soil chlorophyll a). However, chlorophyll a amounts were very low compared to chlorophyll a amounts found at cooler desert sites, where chlorophyll a is often the most important factor in determining TFV and sediment yield. Multiple regression analyses showed that other factors at Fort Irwin were more important than cyanobacterial biomass in determining the overall site susceptibility to wind erosion. These factors included soil texture (especially the fine, medium and coarse sand fractions), rock cover, and the inherent stability of the soil (as indicated by subsurface soil stability tests). Thus, our results indicate that there is a threshold of biomass below which cyanobacterial crusts are not the dominant factor in soil vulnerability to wind erosion. Most undisturbed soil surfaces in the Mojave Desert region produce very little sediment, but even moderate disturbance increases soil loss from these sites. Because current weathering rates and dust inputs are very low, soil formation rates are low as well. Therefore, soil loss in this region is likely to have long‐term effects. Published in 2006 by John Wiley & Sons, Ltd.

Potatoes of a number of varieties of contrasting levels of resistance were planted in pure or mixed stands in lour experiments over 3 years. Three experiments compared the late blight severity and progress in mixtures with that in pure stands. Disease on susceptible or moderately resistant varieties typical of those in commercial use was similar in mixtures and pure stands. In 2 of 3 years, there were slight reductions oil cv. Same, which is moderately susceptible, in mixture with cv. Cara, which is moderately resistant. Cara was unaffected by this mixture. Mixtures of an immune or near-immune partner with Cara or Same substantially reduced disease on the latter. The effect of the size of plots of individual varieties or mixtures on blight severity was compared in two experiments. Larger plots had a greater area under the disease progress curve, but the average rate of disease progress was greater in smaller plots; this may be because most disease progress took place later, under more favourable conditions, in the smaller plots. in one experiment, two planting densities were used. Density had no effect on disease and did not interact with mixture effects. The overall conclusion is that, while mixtures of potato varieties may be desirable for other reasons, they do not offer any improvement on the average of the disease resistance of the components.

Plants bred for monoculture require inputs for high fertility, and to control weeds, pests and diseases. Plants that are bred for such monospecific communities are likely to be incompatible with the deployment of biodiversity to improve resource use and underpin ecosystem services. Two different approaches to breeding for agricultural diversity are described: (1) the use of composite cross populations and (2) breeding for improved performance in crop mixtures.

Summers on the Colorado Plateau (USA) are typified by harsh conditions such as high temperatures, brief soil hydration periods, and high UV and visible radiation. We investigated whether community composition, physiological status, and pigmentation might vary in biological soil crusts as a result of such conditions. Representative surface cores were sampled at the ENE, WSW, and top microaspects of 20 individual soil crust pedicels at a single site in Canyonlands National Park, Utah, in spring and fall of 1999. Frequency of cyanobacterial taxa, pigment concentrations, and dark adapted quantum yield [F(v)/F(m)] were measured for each core. The frequency of major cyanobacterial taxa was lower in the fall compared to spring. The less-pigmented cyanobacterium Microcoleus vaginatus showed significant mortality when not in the presence of Nostoc spp. and Scytonema myochrous (Dillw.) Agardh. (both synthesizers of UV radiation-linked pigments) but had little or no mortality when these species were abundant. We hypothesize that the sunscreen pigments produced by Nostoc and Scytonema in the surface of crusts protect other, less-pigmented taxa. When fall and spring samples were compared, overall cyanobacterial frequency was lower in fall, while sunscreen pigment concentrations, chlorophyll a concentration, and F(v)/F(m) were higher in fall. The ratio of cyanobacterial frequency/chlorophyll a concentrations was 2-3 times lower in fall than spring. Because chlorophyll a is commonly used as a surrogate measure of soil cyanobacterial biomass, these results indicate that seasonality needs to be taken into consideration. In the fall sample, most pigments associated with UV radiation protection or repair were at their highest concentrations on pedicel tops and WSW microaspects, and at their lowest concentrations on ENE microaspects. We suggest that differential pigment concentrations between microaspects are induced by varying UV radiation dosage at the soil surface on these different microaspects.

Global change caused by anthropogenic activities may significantly modify the abundance, structure, and function of biological soil crusts. The components of global change can be grouped into (1) those that impact discreet sites but are occurring on a global scale, such as land-use change and invasive species, and (2) those that alter atmospheric chemistry resulting in changes in CO2 concentration, UV radiation, temperature, and precipitation (Vitousek 1994). In this chapter we will examine how land-use change, invasive species, elevated atmospheric CO2, increased UV radiation, and climate change may affect biological soil crusts and the ecosystems which they inhabit.

Extracts of bovine stalk-median eminence fragments (SME) equivalent to 3–5 glands were infused into the carotid artery of young sheep. Plasma GH increased from 4.8 at zero time to 17.7 mμg/ml 30 min after infusion had begun. Infusion of saline or cerebrum extracts had no effect on plasma GH. SME extracts also caused an elevation of plasma glucose and insulin which preceded the rise in GH. Evidence is presented which indicates that the rise in plasma GH levels is not a response to insulin but is a direct effect of a releasing factor in the SME extracts. (Endocrinology80: 205, 1967)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPotentiostatic Determination of Diffusion Coefficient of Oxygen in Absence and Presence of Surfactants.S. L. PhillipsCite this: Anal. Chem. 1966, 38, 12, 1714–1719Publication Date (Print):November 1, 1966Publication History Published online1 May 2002Published inissue 1 November 1966https://pubs.acs.org/doi/10.1021/ac60244a021https://doi.org/10.1021/ac60244a021research-articleACS PublicationsRequest reuse permissionsArticle Views164Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplication of Adsorption Electroanalysis to the Trace Determination of Tetrabutylammonium Ion.S. L. PhillipsCite this: Anal. Chem. 1966, 38, 2, 343–344Publication Date (Print):February 1, 1966Publication History Published online1 May 2002Published inissue 1 February 1966https://pubs.acs.org/doi/10.1021/ac60234a044https://doi.org/10.1021/ac60234a044research-articleACS PublicationsRequest reuse permissionsArticle Views27Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolarographic Reduction of Tin(IV) in the Presence of 3-Mercaptopropionic Acid.S. L. Phillips and R. A. ToomeyCite this: Anal. Chem. 1965, 37, 4, 607–609Publication Date (Print):April 1, 1965Publication History Published online1 May 2002Published inissue 1 April 1965https://pubs.acs.org/doi/10.1021/ac60223a051https://doi.org/10.1021/ac60223a051research-articleACS PublicationsRequest reuse permissionsArticle Views50Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplication of Stripping Analysis to the Trace Determination of Tin.S. L. Phillips and Irving ShainCite this: Anal. Chem. 1962, 34, 2, 262–265Publication Date (Print):February 1, 1962Publication History Published online1 May 2002Published inissue 1 February 1962https://pubs.acs.org/doi/10.1021/ac60182a034https://doi.org/10.1021/ac60182a034research-articleACS PublicationsRequest reuse permissionsArticle Views99Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolarographic Determination of Tin in Stannic OxideS. L. PhillipsCite this: Anal. Chem. 1960, 32, 9, 1062–1064Publication Date (Print):August 1, 1960Publication History Published online1 May 2002Published inissue 1 August 1960https://pubs.acs.org/doi/10.1021/ac60165a002https://doi.org/10.1021/ac60165a002research-articleACS PublicationsRequest reuse permissionsArticle Views33Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts