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121.
CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart) are widespread security measures on the World Wide Web that prevent automated programs from abusing online services. They do so by asking humans to perform a task that computers cannot yet perform, such as deciphering distorted characters. Our research explored whether such human effort can be channeled into a useful purpose: helping to digitize old printed material by asking users to decipher scanned words from books that computerized optical character recognition failed to recognize. We showed that this method can transcribe text with a word accuracy exceeding 99%, matching the guarantee of professional human transcribers. Our apparatus is deployed in more than 40,000 Web sites and has transcribed over 440 million words. 相似文献
122.
Absorption lines in the v, band of water vapor at 6.3 micrometers have been fully resolved by using a tunable semiconductor laser. Three attnospheric water vapor lines near 5.32 micrometers were studied in detail and found to have linle widths two to four times narrower than the width calculated by Benedict and Kaplan. 相似文献
123.
Children absorb tris-BP flame retardant from sleepwear: urine contains the mutagenic metabolite, 2,3-dibromopropanol 总被引:4,自引:0,他引:4
A Blum M D Gold B N Ames F R Jones E A Hett R C Dougherty E C Horning I Dzidic D I Carroll R N Stillwell J P Thenot 《Science (New York, N.Y.)》1978,201(4360):1020-1023
The flame retardant, tris(2,3-dibromopropyl)phosphate (tris-BP), which is a mutagen and causes cancer and sterility in animals is absorbed from fabric by people. 2,3-Dibromopropanol, a metboloite of tris-BP and a mutagen itself, has been found in the urine samples of ten children who were wearing or who had worn tris-BP-treated sleepwear. Eight of these children were wearing well-washed sleepwear and the possibility of absorption of tris-BP from well-washed sleepwear discussed. 2,3-Dibromopropanol was not found in the urines of one child and one adult who had never worn tris-BP-treated garments. 相似文献
124.
Detection of two viral genomes in single cells by double-label hybridization in situ and color microradioautography 总被引:5,自引:0,他引:5
A T Haase D Walker L Stowring P Ventura A Geballe H Blum M Brahic R Goldberg K O'Brien 《Science (New York, N.Y.)》1985,227(4683):189-192
Double labeling and color microradioautography were used in a new method of hybridization in situ to identify different genes in individual cells. The method is based on the unequal penetration of 3H and 35S into two layers of nuclear track emulsion separated by a thin barrier film. Hybridization of a 35S-labeled probe specific for one kind of gene results in silver grains over cells in both layers of emulsion; a 3H-labeled probe for a second gene provides grains only in the first layer of emulsion. Silver grains are converted to magenta-colored grains in the first layer and to cyan-colored grains in the second to facilitate enumeration of grains in each layer. This technique should be widely applicable in analyses of differential gene expression in single cells or in discrete populations of cells. 相似文献
125.
Brand JM Duffield RM Macconnell JG Blum MS Fales HM 《Science (New York, N.Y.)》1973,179(4071):388-389
Three caste-specific substances new to arthropod glandular secretions occur in the mandibular glands of male ants of five species in the genus Camponotus. These volatile compounds, which are not found in alate females or workers, have been identified as methyl 6-methyl salicylate, 2,4-dimethyl-2-hexenoic acid, and methyl anthranilate. The free acid has not been described previously. 相似文献
126.
Wolfe-Simon F Switzer Blum J Kulp TR Gordon GW Hoeft SE Pett-Ridge J Stolz JF Webb SM Weber PK Davies PC Anbar AD Oremland RS 《Science (New York, N.Y.)》2011,332(6034):1163-1166
Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions. Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, that is able to substitute arsenic for phosphorus to sustain its growth. Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins. Exchange of one of the major bio-elements may have profound evolutionary and geochemical importance. 相似文献
127.
128.
Colostrum intake influences growth and development of the gastrointestinal tract (GIT) in several species and colostral insulin-like growth factors I and II (IGF-I and IGF-II), and insulin are involved in neonatal intestinal tissue growth. We have studied IGF type 1, IGF type 2, and insulin receptors in the intestine of 8-day-old calves fed different amounts of colostrum or only milk replacer. Calves were fed colostrum of the first six milkings on the first 3 days and then milk replacer (GrC(6)) or colostrum only once and then milk replacer (GrC(1)) or they were fed only milk replacer from the beginning, i.e., no colostrum (GrM). Competitive binding studies and ligand blots confirmed the presence of IGF type 1, IGF type 2, and insulin receptors in mucosal cell membranes of duodenum, jejunum, ileum, and colon. The IGF type 1 receptor number in ileum and total intestine in GrC(6) was greater (P<0.05) than in GrC(1) and in GrM, and IGF type 2 receptor number in total intestine was greater (P<0.05) in GrC(6) than in GrM. Insulin binding was best fitted by a model with two binding sites. High affinity insulin receptor numbers in duodenum, ileum, and total intestine were greater (P<0.05) in GrC(6) than in GrM. The data demonstrate that IGF type 1, IGF type 2, and insulin receptors in intestinal mucosa of neonatal calves are influenced by feeding. 相似文献
129.
Taru Lehtinen Guðrún Gísladóttir Georg J. Lair Jeroen P. van Leeuwen Winfried E.H. Blum Jaap Bloem 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):246-263
Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future. 相似文献
130.
Journal of Plant Diseases and Protection - The forest cockchafer Melolontha hippocastani is a serious forest pest whose infestation levels have been increasing in South-West Germany since the... 相似文献