Input-Output Budgets of Inorganic Nitrogen for 24 Forest Watersheds in the Northeastern United States: A Review     

Campbell  John L.  Hornbeck  James W.  Mitchell  Myron J.  Adams  Mary Beth  Castro  Mark S.  Driscoll  Charles T.  Kahl  Jeffrey S.  Kochenderfer  James N.  Likens  Gene E.  Lynch  James A.  Murdoch  Peter S.  Nelson  Sarah J.  Shanley  James B. 《Water, air, and soil pollution》2004,151(1-4):373-396

Input-output budgets for dissolved inorganic nitrogen (DIN) are summarized for 24 small watersheds at 15 locations in the northeasternUnited States. The study watersheds are completely forested, free of recent physical disturbances, and span a geographical region bounded by West Virginia on the south and west, and Maine on the north and east. Total N budgets are not presented; however, fluxes of inorganic N in precipitation and streamwater dominate inputs and outputs of N at these watersheds. The range in inputs of DIN in wet-only precipitation from nearby National Atmospheric Deposition Program (NADP) sites was 2.7 to 8.1 kg N ha^-1 yr^-1 (mean = 6.4 kg N ha^-1 yr^-1; median = 7.0 kg N ha^-1 yr^-1). Outputs of DIN in streamwater ranged from 0.1 to 5.7 kg N ha^-1 yr^-1 (mean = 2.0 kg N ha^-1 yr^-1; median = 1.7 kg N ha^-1 yr^-1). Precipitation inputs of DIN exceeded outputs in streamwater at all watersheds, with net retention of DIN ranging from 1.2 to 7.3 kg N ha^-1 yr^-1 (mean = 4.4 kg N ha^-1 yr^-1; median = 4.6 kg N ha^-1 yr^-1). Outputs of DIN in streamwater were predominantly NO₃-N (mean = 89%; median = 94%). Wet deposition of DIN was not significantly related to DIN outputs in streamwater for these watersheds. Watershed characteristics such as hydrology, vegetation type, and land-use history affect DIN losses and may mask any relationship between inputs and outputs. Consequently, these factors need to be included in the development of indices and simulation models for predicting 'nitrogen saturation' and other ecological processes.  相似文献   

Effects of expanded mosquito range     

Bevins SN 《Science (New York, N.Y.)》2008,321(5896):1634

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Mapping human brain monoamine oxidase A and B with 11C-labeled suicide inactivators and PET   总被引：1，自引：0，他引：1  

J S Fowler  R R MacGregor  A P Wolf  C D Arnett  S L Dewey  D Schlyer  D Christman  J Logan  M Smith  H Sachs 《Science (New York, N.Y.)》1987,235(4787):481-485

The regional distributions of monoamine oxidase (MAO) types A and B have been identified in human brain in vivo with intravenously injected 11C-labeled suicide enzyme inactivators, clorgyline and L-deprenyl, and positron emission tomography. The rapid brain uptake and retention of radioactivity for both 11C tracers indicated irreversible trapping. The anatomical distribution of 11C paralleled the distribution of MAO A and MAO B in human brain in autopsy material. The corpus striatum, thalamus, and brainstem contained high MAO activity. The magnitudes of uptake of both [11C]clorgyline and L-[11C]deprenyl were markedly reduced in one subject treated with the antidepressant MAO inhibitor phenelzine. A comparison of the brain uptake and retention of the 11C-labeled inactive (D-) and active (L-) enantiomers of deprenyl showed rapid clearance of the inactive enantiomer and retention of the active enantiomer within MAO B-rich brain structures, in agreement with the known stereoselectivity of MAO B for L-deprenyl. Prior treatment with unlabeled L-deprenyl prevented retention of L-[11C]deprenyl. Thus, suicide enzyme inactivators labeled with positron emitters can be used to quantitate the distribution and kinetic characteristics of MAO in human brain structures.  相似文献   

Cross-linked fibrinogen dimers demonstrate a feature of the molecular packing in fibrin fibers   总被引：7，自引：0，他引：7  

W E Fowler  H P Erickson  R R Hantgan  J McDonagh  J Hermans 《Science (New York, N.Y.)》1981,211(4479):287-289

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Reverse leasing and power dynamics among blue agave farmers in western Mexico     

Sarah Bowen  Peter R. W. Gerritsen 《Agriculture and Human Values》2007,24(4):473-488

We examine changing production relations in the Mexican tequila industry to explore the ways in which large industrial firms are using “reverse leasing arrangements,” a form of contract farming, to extend their control over small agave farmers. Under these arrangements, smallholders rent their parcels to contracting companies who bring in capital, machinery, labor, and other agricultural inputs. Smallholders do not have access to their land, nor do they make any of the management decisions. We analyze the factors that have led some producers to participate in reverse leasing arrangements, while allowing other producers to continue farming independently. In addition, we look at the ways in which farmers are responding to these new production relations and constraints and the strategies that they are using to regain control over the production process.

Sarah BowenEmail:

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Preschool program improves cognitive control     

Diamond A  Barnett WS  Thomas J  Munro S 《Science (New York, N.Y.)》2007,318(5855):1387-1388

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An empirical test of recruitment limitation in a coral reef fish     

Doherty P  Fowler T 《Science (New York, N.Y.)》1994,263(5149):935-939

A long-term, large-scale empirical test of the recruitment limitation hypothesis was done by sampling fish populations from the southern Great Barrier Reef after having monitored their recruitment histories for 9 years. After adjustment for demographic differences, recruitment patterns explained over 90 percent of the spatial variation in abundance of a common damselfish among seven coral reefs. The age structures from individual reefs also preserved major temporal variations in the recruitment signal over at least 10 years. Abundance and demography of this small fish at these spatial and temporal scales can be explained almost entirely as variable recruitment interacting with density-independent mortality.  相似文献   

AN ANTIGEN-ANTIBODY REACTION WITH TETRAHYMENA WHICH RESULTS IN DYSTOMY     

Harrison JA  Fowler EH 《Science (New York, N.Y.)》1945,102(2638):65-66

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Inactivation of TNF signaling by rationally designed dominant-negative TNF variants     

Steed PM  Tansey MG  Zalevsky J  Zhukovsky EA  Desjarlais JR  Szymkowski DE  Abbott C  Carmichael D  Chan C  Cherry L  Cheung P  Chirino AJ  Chung HH  Doberstein SK  Eivazi A  Filikov AV  Gao SX  Hubert RS  Hwang M  Hyun L  Kashi S  Kim A  Kim E  Kung J  Martinez SP  Muchhal US  Nguyen DH  O'Brien C  O'Keefe D  Singer K  Vafa O  Vielmetter J  Yoder SC  Dahiyat BI 《Science (New York, N.Y.)》2003,301(5641):1895-1898

Tumor necrosis factor (TNF) is a key regulator of inflammatory responses and has been implicated in many pathological conditions. We used structure-based design to engineer variant TNF proteins that rapidly form heterotrimers with native TNF to give complexes that neither bind to nor stimulate signaling through TNF receptors. Thus, TNF is inactivated by sequestration. Dominant-negative TNFs represent a possible approach to anti-inflammatory biotherapeutics, and experiments in animal models show that the strategy can attenuate TNF-mediated pathology. Similar rational design could be used to engineer inhibitors of additional TNF superfamily cytokines as well as other multimeric ligands.  相似文献   

A homolog of Drosophila grainy head is essential for epidermal integrity in mice   总被引：1，自引：0，他引：1  

Ting SB  Caddy J  Hislop N  Wilanowski T  Auden A  Zhao LL  Ellis S  Kaur P  Uchida Y  Holleran WM  Elias PM  Cunningham JM  Jane SM 《Science (New York, N.Y.)》2005,308(5720):411-413

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