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1.
Brody Gene H.; Ge Xiaojia; Kim Su Yeong; Murry Velma McBride; Simons Ronald L.; Gibbons Frederick X.; Gerrard Meg; Conger Rand D. 《Canadian Metallurgical Quarterly》2003,71(2):211
Data from 296 sibling pairs (mean ages 10 and 13 years), their primary caregivers, and census records were used to test the hypothesis that African American children's likelihood of developing conduct problems associated with harsh parenting, a lack of nurturant-involved parenting, and exposure to an older sibling's deviance-prone attitudes and behavior would be amplified among families residing in disadvantaged neighborhoods. A latent construct representing harsh-inconsistent parenting and low levels of nurturant-involved parenting was positively associated with younger siblings' conduct disorder symptoms, as were older siblings' problematic attitudes and behavior. These associations were strongest among families residing in the most disadvantaged neighborhoods. Future research and prevention programs should focus on the specific neighborhood processes associated with increased vulnerability for behavior problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
ABSTRACT Several investigators have developed hierarchically structured maximal covering location problems, especially for hierarchies with two levels such as clinics and hospitals: Moore and ReVelle developed and applied a hierarchical covering model to a medical service delivery problem in Houduras; and Church and Falon developed two alternate model forms of hierarchical covering that were applied to a medical services planning, problem in Colombia. In this paper, we proposed a hybrid formulation that encompasses all three of these previous models and which allows for the trade-off of up of four different objectives. This new model formulation is also an improvement in that it has a significantly more efficient and compact structure, even while encompassing a more complete location problem, of which the three previous works are special cases. Example solutions are given for two different data sels involving regions in Colombia and Uganda. In addition, two further model formulations of a closely related nature are presented without computational results. 相似文献
3.
Nicholas P. Petropolis Harrison M. Petropolis Nicole E. MacNeil Taylor M. Doucet D. Gerrard Marangoni 《Journal of surfactants and detergents》2021,24(1):51-66
The critical micelle concentrations (CMC) values and counterion dissociation (α values) have been determined for a number of mixed micellar systems consisting of two typical ionic surfactants and glycol ethers (glymes) as cosurfactants, namely diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. Conductance experiments were used to determine the CMC and α values of the mixed micelles as a function of glyme concentration in the aqueous mixed solvent. Favorable interactions between sodium dodecyl sulfate micelles and glyme cosurfactants were deduced from the decreases in the CMC values and the large increase in the α values of these systems as a function of increasing glyme concentration in the mixed solvents. In contrast to the anionic surfactant/glyme systems, in general, there appeared to be little favorable interactions between the surfactant and glymes when micelles of the cationic surfactant dodecyltrimethylammonium bromide were formed in water/glyme solvent systems containing an increasing amount of the glymes. The interaction of glymes with the surfactant micelles was examined closely via 13C nuclear magnetic resonance (NMR) chemical shifts for both surfactant and glyme carbons; these chemical shifts changes were interpreted in terms of the distribution and the localization of the glymes in the aggregates. Finally, partition constants, determined from two-dimensional diffusion-oriented spectroscopy (2D-DOSY) experiments, were used to calculate thermodynamic quantities of transfer of the glymes between the bulk phase and the self-assembled aggregates. All these results are interpreted in terms of the key contributions that both the glyme ethoxylated groups and alkyl endgroups make to the hydrophobic interactions. 相似文献
4.
Claire E. Gerrard John McCall George M. Coghill Christopher Macleod 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2014,18(10):1899-1912
The Artificial Reaction Network (ARN) is a Cell Signalling Network inspired connectionist representation belonging to the branch of A-Life known as Artificial Chemistry. Its purpose is to represent chemical circuitry and to explore computational properties responsible for generating emergent high-level behaviour associated with cells. In this paper, the computational mechanisms involved in pattern recognition and spatio-temporal pattern generation are examined in robotic control tasks. The results show that the ARN has application in limbed robotic control and computational functionality in common with Artificial Neural Networks. Like spiking neural models, the ARN can combine pattern recognition and complex temporal control functionality in a single network, however it offers increased flexibility. Furthermore, the results illustrate parallels between emergent neural and cell intelligence. 相似文献
5.
W. Gerrard 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1972,22(5):623-650
The solubilities of hydrogen sulphide, dimethyl ether, methyl chloride, and sulphur dioxide expressed as the mole ratio, Xgas, at different temperatures and 1 bara are given for a number of liquid compounds of types commonly used in operational chemistry. Representative curves showing the variations of Xgas, and Ngas (mole fraction), with pressure, pgas, are discussed with reference to Henry's law and Raoult's law. With the exception of hydrogen halides and ammonia, the Xgas (at a stated t° and pgas) for water is much less than for any other liquid reported as examined. The primary factor determining the Xgas value at 1 bar is the boiling point of the gas (He to SO2) at 1 bar; the Raoult's law Xgas value emerges from this, and places the gases in the same order as the overlapping ranges of real Xgas values. The actual Xgas value within a particular range for a chosen gas is, for a chosen liquid, seemingly determined by acid-base functions as defined herein. The prediction of the Xgas value is discussed in these terms. 相似文献
6.
Extent of postmortem pH decline influences meat quality development. To better understand physiological determination of ultimate pH (pHu), we utilized female and castrated male pigs from a line whose selection index includes differentiated pHu. All genotypes of AMP-activated protein kinase γ3 subunit (AMPKγ3) V199I site were present. The mutant 199II genotype increased pHu, but only in castrated males. Genotype affected glycolytic potential (GP), but GP was weakly associated with pHu. A subset of animals was selected based on low (− Gly) and high (+ Gly) residual glycogen content, and compared with AMPKγ3 200Q, which is associated with low pHu. Both + Gly and 200Q muscle contained glycolytic substrate at 24 h; however, 200Q muscle generated low pHu and greater lactate compared to + Gly. Additionally,− Gly and + Gly groups exhibited similar pHu despite a large difference in GP. In conclusion, high GP does not appear to directly impact the extent of postmortem pH decline. 相似文献
7.
Abstract: Picture sorts were used to investigate perceptions of women's office clothes, with a sample of ten male and ten female subjects who normally worked in an office environment. The pictures on the cards were taken from catalogues, and showed women's outfits which might be worn in an office. The subjects sorted the cards repeatedly and generated criteria and categories of their own choice. Some of the criteria and categories had not been previously reported in the clothing research literature. Over half of the male subjects, but none of the female subjects, used ‘married/unmarried woman’ as a sorting criterion, although only one of the images sorted showed a wedding ring. A significantly higher proportion of male than of female subjects used dichotomous categorization (i.e. sorting the cards into two piles for one or more of the criteria). The reasons for this are obscure, but do not appear to be a simple outcome of males not knowing much about female clothing. Previous research into clothing has tended to involve researcher‐centred approaches such as semiotics; the results from this study suggest that there would be advantages in wider use of subject‐centred approaches such as card sorts, both in this domain and elsewhere. It was concluded that card sorts were a useful method and should be more widely used. 相似文献
8.
2,2'-dipyridyl, a chelator of ferrous iron and inhibitor of platelet aggregation, was studied together with several similar compounds to determine the mechanism of their effects on platelets. All of these compounds were more potent inhibitors of arachidonic-acid-mediated aggregation (IC50, 0.17-1.8 mM) than of ADP-mediated aggregation (IC50, 7.6-19.7 mM). At low concentrations required to inhibit arachidonic-acid-mediated aggregation, 2,2'-dipyridyl, 4,4'-dipyridyl and 2-chloropyridine specifically inhibited the platelet cyclo-oxygenase. The mechanism of inhibition of ADP-induced aggregation was investigated, but was not explained. At concentrations needed to inhibit ADP-induced aggregation, 2,2'-dipyridyl did not alter cell ultrastructure, serotonin or nucleotide content or interfere with release of [14C]arachidonic acid or calcium movements. Therefore, our results indicate that 2,2'-dipyridyl and related compounds have two effects on platelets, both due to the unprotonated form. The inhibition of cyclo-oxygenase by low concentrations of these compounds is not due to bidentate iron chelation, since 4,4'-dipyridyl was almost as effective as 2,2'-dipyridyl, but is compatible with binding of these inhibitors to the iron in the heme of the cyclo-oxygenase. 相似文献
9.
Carcasses from 64 gilts were subjected to electrical stimulation (ES) at 3, 15, 25, 35, 45, and 55 min postmortem or were untreated (NS). Temperature and pH of longissimus muscles were recorded at 1, 7, 14, 20, 30, 40, 50, and 60 min, and 24 h postmortem. Muscle samples were collected at 1, 30 and 60 min, and 24 h for determining glycolytic metabolite concentrations. ES at 3, 15, and 25 min resulted in lower (P<0.05) muscle pH, but stimulation after 25 min had no effect on muscle pH. Likewise, ES prior to 25 min resulted in greater (P<0.05) muscle temperatures. Muscle lactate concentrations were greater (P<0.05) in carcasses stimulated before 45 min postmortem. Glucose 6-phosphate concentration decreased (P<0.05) during the first hr postmortem and increased (P<0.05) thereafter. ES of carcasses at 45 and 55 min resulted in higher (P<0.05) concentrations of muscle glucose 6-phosphate at 24 h compared with NS and early-stimulated carcasses. Muscle glycogen concentrations at 30 min in carcasses stimulated at 3, 15 and 25 min were lower (P<0.05) than NS carcasses. Carcasses stimulated at 3 and 15 min exhibited lower (P<0.05) concentrations of muscle glycogen at 60 min than NS carcasses. Carcasses stimulated at 3 and 15 min postmortem exhibited lower (P<0.05) color and firmness scores, while ES at 3 and 25 min postmortem resulted in lower (P<0.05) water holding capacity. ES had no significant effect on CIE L(?), a(?), b(?), or 24 h muscle pH. These data show that ES of pork carcasses during the first 25 min postmortem creates PSE-like quality characteristics and suggest that ES is a potential model for studying pork quality development. 相似文献
10.
Color image features were computed to characterize the skeletal maturity of beef carcasses based on cartilage ossification in the thoracic vertebrae. A trained neural network was tested for predicting USDA beef maturity grades from image features of ossification. A feature curve was defined to characterize the color variations of an isolated cartilage-bone object. Both RGB and HSL color systems were used to derive image features. The maturity grades were assigned by an official USDA grader. Two sets of samples were obtained from two different meat-processing plants. The first set contained samples of only A and B maturity grades whereas the second set had all five maturity classifications (A through E). The hue value was the most useful color feature. The mean hue values of cartilage differed (P<0.05) among the maturity grades and the feature curve based on the hue value was used as neural network input for maturity prediction. The accuracy of prediction was 75% for the first set of samples and 65.9% for the second set of samples. The results data show the potential of computer vision techniques for beef maturity assessment. 相似文献