The Water Dipole Moment in Water Clusters     

JK Gregory  DC Clary  K Liu  MG Brown  RJ Saykally 《Science (New York, N.Y.)》1997,275(5301):814-817

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Effects of size and temperature on metabolic rate     

Gillooly JF  Brown JH  West GB  Savage VM  Charnov EL 《Science (New York, N.Y.)》2001,293(5538):2248-2251

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on metabolic rate. The model fits metabolic rates of microbes, ectotherms, endotherms (including those in hibernation), and plants in temperatures ranging from 0 degrees to 40 degrees C. Mass- and temperature-compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular organisms and plants) is separated from the highest (for endothermic vertebrates) by a factor of about 20. Temperature and body size are primary determinants of biological time and ecological roles.  相似文献   

Slow crack growth in single-crystal silicon     

Connally JA  Brown SB 《Science (New York, N.Y.)》1992,256(5063):1537-1539

Time-dependent crack growth has been measured on a precracked, single-crystal silicon cantilever beam 75 micrometers long that was excited at resonance. Growth of the precrack changes the resonant frequency of the beam, which is correlated to crack length. The measured steady-state crack growth rate was as slow as 2.9 x 10(-13) meter per second, although the apparatus can measure crack growth rates as low as 10(-15) meter per second. It is postulated that static fatigue of the native surface silica layer is the mechanism for crack growth. These experiments demonstrate the possibility of rate-dependent failure of silicon devices and the applicability of linear elastic fracture mechanics to small-scale micromechanical devices. The results indicate that slow crack growth must therefore be considered when evaluating the reliability of thin-film silicon structures.  相似文献   

First transgenic trait for control of plant bugs and thrips in cotton     

Waseem Akbar  Anilkumar Gowda  Jeffrey E Ahrens  Jason W Stelzer  Robert S Brown  Scott L Bollman  John T Greenplate  Jeffrey Gore  Angus L Catchot  Gus Lorenz  Scott D Stewart  David L Kerns  Jeremy K Greene  Michael D Toews  David A Herbert  Dominic D Reisig  Gregory A Sword  Peter C Ellsworth  Larry D Godfrey  Thomas L Clark 《Pest management science》2019,75(3):867-877

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Adenohypophyseal receptors for LHRH, pituitary content of gonadotropins and plasma concentrations of LH in cyclic, pregnant and postpartum beef cows     

C.H. Rahe  J.L. Brown  D.N. Marple  J.L. Sartin  F.F. Bartol  D.R. Mulvaney  J.J. Reeves 《Domestic animal endocrinology》1988,5(4):291-298

Adenohypophyseal concentrations of LHRH receptors, pituitary content of LH and FSH, and plasma concentrations of LH were determined in thirty Hereford, Angus or Hereford-Angus heifers that were randomly assigned by breed and weight to five periods including day 3 of the estrous cycle (CY), pregnant day 120 (P120), 200 (P200), 275 (P275), or day 2 postpartum (PP). Jugular blood samples were collected at 10-min intervals for 8 hr from all cows. Within 2 hr after completion of blood sampling, animals were slaughtered and the pituitary gland frozen at −196 C. LH pulse frequency/8 hr was reduced (P<.05) during gestation (.5, .2, and 1.5 ± .5/8 hr, for P120, P200, and P275, respectively) and PP (.5 ± .5/8 hr) compared to CY (7.8 ± .5/8 hr). Frequency of LH pulses/8 hr was not different (P>.1) among P120, P200 or PP periods but was different (P<.05) between P200 and P275. There were no differences in LH pulse height (P>.1) among periods; however, pulse amplitude was greatest (P<.05) at P120 (1.3 ± .2 ng/ml) and lowest between P200 and PP (.6 to .8 ± .2 ng/ml). Baseline concentrations of plasma LH did not differ (P>.1) among P and PP periods (.3 ± .1 ng/ml), but were lower (P<.05) than in CY animals (.7 ± .1 ng/ml). Concentration of adenohypophyseal LHRH receptors was approximately two-fold greater (P<.05) at P120 (25.85 ± 2.2 fmol/mg) than at all other periods (9.5 to 14.9 ± 2.2 fmol/mg). Pituitary content of LH was greatest at P120 (1.56 ± .11 ug/mg) and lowest (P<.05) at P275 and PP (0.46 to 0.52 ± .11 ug/mg). Pituitary content of FSH was greatest (P<.05) in P (12.7 to 17.0 ± 1.4 ug/mg) and PP (18.3 ± 1.4 ug/mg) vs CY (5.0 ± 1.4 ug/mg) cows and increased from P120 to PP (P<.05). Results indicate that physiological changes occurring during gestation may have an effect on subsequent function of the adenohypophysis in beef cows.  相似文献   

The diagnostic value of the D-xylose absorption test in horses with unexplained chronic weight loss.     

C M Brown 《The British veterinary journal》1992,148(1):41-44

A D-xylose absorption test was performed on 40 horses with chronic weight loss which could not be explained on history, physical findings, dietary evaluation, or initial laboratory data, i.e. unexplained weight loss. Six of the horses had D-xylose malabsorption and at post-mortem examination small intestinal lesions which accounted for the malabsorption were found in five. Five of the horses with normal absorption were examined post mortem and no lesions in any organs were found to account for the weight loss. The other 29 cases were still unexplained, and lost to follow-up.  相似文献   

PERIOD1-associated proteins modulate the negative limb of the mammalian circadian oscillator   总被引：1，自引：0，他引：1  

Brown SA  Ripperger J  Kadener S  Fleury-Olela F  Vilbois F  Rosbash M  Schibler U 《Science (New York, N.Y.)》2005,308(5722):693-696

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Spatial variability of common carp populations in relation to lake morphology and physicochemical parameters in the upper Midwest United States     

M. J. Weber  M. L. Brown  D. W. Willis 《Ecology of Freshwater Fish》2010,19(4):555-565

Weber MJ, Brown ML, Willis DW. Spatial variability of common carp populations in relation to lake morphology and physicochemical parameters in the upper Midwest United States.
Ecology of Freshwater Fish 2010: 19: 555–565. © 2010 John Wiley & Sons A/S Abstract – Common carp (Cyprinus carpio) is a widespread invasive species that is tolerant of a wide range of environmental conditions. Despite the circumpolar distribution of the species, limited information is available describing factors related to spatial variation in population characteristics. Eighty‐four lakes and impoundments in the upper Midwest United States were sampled to investigate the relationships of common carp relative abundance with size structure, condition and growth rates. We also investigated abiotic factors (lake morphology, physical solids and water quality) that may broadly influence common carp populations. Common carp size structure and condition were inversely related to relative abundance. Common carp relative abundance increased and size structure shifted to smaller individuals with increased lake depth, whereas lake surface area, watershed:surface area ratio and physical solids were also important in explaining common carp abundance and size structure. Common carp condition was best explained by water quality parameters and increased with metrics of lake productivity. We conclude that knowledge of factors associated with variation in common carp populations among lakes provides insights into the autecology and broad provisions for management of this generalist invasive species.  相似文献   

Mode of action,crop selectivity,and soil relations of the sulfonylurea herbicides     

Hugh M. Brown 《Pest management science》1990,29(3):263-281

The sulfonylurea herbicides are characterized by broad-spectrum weed control at very low use rates (c. 2–75 g ha^?1), good crop selectivity, and very low acute and chronic animal toxicity. This class of herbicides acts through inhibition of acetolactate synthase (EC 4.1.3.18; also known as acetohydroxyacid synthase), thereby blocking the biosynthesis of the branched-chain amino acids valine, leucine and isoleucine. This inhibition leads to the rapid cessation of plant cell division and growth. Crop-selective sulfonylurea herbicides have been commercialized for use in wheat, barley, rice, corn, soybeans and oilseed rape, with additional crop-selective compounds in cotton, potatoes, and sugarbeet having been noted. Crop selectivity results from rapid metabolic inactivation of the herbicide in the tolerant crop. Under growth-room conditions, metabolic half-lives in tolerant crop plants range from 1–5 h, while sensitive plant species metabolize these herbicides much more slowly, with half-lives > 20 h. Pathways by which sulfonylurea herbicides are inactivated among these plants include aryl and aliphatic hydroxylation followed by glucose conjugation, sulfonylurea bridge hydrolysis and sulfonamide bond cleavage, oxidative O-demethylation and direct conjugation with (homo)glutathione. Sulfonylurea herbicides degrade in soil through a combination of bridge hydrolysis and microbial degradation. Hydrolysis is significantly faster under acidic (pH 5) than alkaline (pH 8) conditions, allowing the use of soil pH as a predictor of soil residual activity. Chemical and microbial processes combine to give typical field dissipation half-lives of 1–6 weeks, depending on the soil type, location and compound. Very short residual sulfonylurea herbicides with enhanced susceptibility to hydrolysis (DPX-L5300) and microbial degradation (thifensulfuron-methyl) have been developed.  相似文献   

Tobacco rattle virus serotypes and associated nematode vector species of Trichodoridae in the bulb-growing areas in the Netherlands   总被引：1，自引：0，他引：1  

A. T. Ploeg  C. J. Asjes  D. J. F. Brown 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(5):311-319

Soil samples from the coastal bulb-growing areas in the provinces of North- and South-Holland and the North-East Polder in the Netherlands were examined for trichodorid nematodes and tobacco rattle virus (TRV) serotypes. At least one of a total of eight species of Trichodoridae, of whichParatrichodorus pachydermus was most prevalent, was found in 93% of the samples from the provinces of North- and South-Holland and TRV, including four serotypes, was obtained from 49% of these samples. In the North-East Polder one of three species of trichodorids, of whichP. teres occurred most frequently, was present in 72% of the samples, and TRV of one serotype was obtained from 28% of these samples. The TRV isolates recovered from these samples reacted serologically with one of four antisera to strains of TRV. Virus transmitted byP. pachydermus reacted to the PRN-, byTrichodorus viruliferus to the RQ-, byP. teres to the N5- and byT. similis, to the TS-antiserum, respectively.  相似文献