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61.
Martha Kaddumukasa David Nsubuga Fredrick J. Muyodi 《Lakes & Reservoirs: Research and Management》2012,17(4):291-299
Vibrio cholerae, a bacterium that causes cholera, poses a human health risk when consumed via untreated or contaminated water. Monthly investigations into the presence of V. cholerae from Lakes Albert, George and Victoria were conducted, with the goal being to examine the relationship between the occurrences of V. cholerae with various water quality parameters at fish landing sites in major water bodies in Uganda. The pH, temperature and electrical conductivity were measured at three fishing sites in each of the three study lakes; namely Gabba in Lake Victoria, Butiaba in Lake Albert and Kayanzi in Lake George. The pH values varied from 7.76 to 9.36 at Butiaba, 8.68 to 9.85 at Kayanzi and 6.6 to 9.88 at Ggaba. The temperature ranged from 17.9 to 32.3 °C at Butiaba, 22.5 to 29 °C at Kayanzi and 18.2 to 30.5 °C at Ggaba. The electrical conductivity ranged from 129.2 to 984 μS cm?1 at Butiaba, 658 to 1090 μS cm?1 at Kayanzi and 119 to 218 μS cm?1 at Ggaba, for Lakes Albert, George and Victoria, respectively. Enrichment techniques were used to detect culturable V. cholerae on TCBS culture media. Seventy‐five (75%) of the samples (n = 90) were positive for V. cholera. The occurrence of V. cholerae was positively associated with water quality parameters over the 10‐month period of study. Vibrio cholerae was more frequently detected during the dry season (warmer) than during the wet season. These study results suggest the investigated study lakes are natural reservoirs for V. cholerae. 相似文献
62.
Developing conceptual understanding and procedural skill in mathematics: An iterative process. 总被引:3,自引:0,他引:3
Rittle-Johnson Bethany; Siegler Robert S.; Alibali Martha Wagner 《Canadian Metallurgical Quarterly》2001,93(2):346
The authors propose that conceptual and procedural knowledge develop in an iterative fashion and that improved problem representation is 1 mechanism underlying the relations between them. Two experiments were conducted with 5th- and 6th-grade students learning about decimal fractions. In Experiment 1, children's initial conceptual knowledge predicted gains in procedural knowledge, and gains in procedural knowledge predicted improvements in conceptual knowledge. Correct problem representations mediated the relation between initial conceptual knowledge and improved procedural knowledge. In Experiment 2, amount of support for correct problem representation was experimentally manipulated, and the manipulations led to gains in procedural knowledge. Thus, conceptual and procedural knowledge develop iteratively, and improved problem representation is 1 mechanism in this process. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
A diagnosis of antisocial personality disorder (ASPD) requires a conduct disorder (CD) diagnosis. A CD diagnosis is often obtained retrospectively. This study tested the influence of current behavior on CD recall and the association between recent behavior change and inconsistencies in contemporaneous and retrospective CD reports. Five hundred young adults reported ASPD; retrospective CD; current problem behavior; and, at ages 12 to 15 years, contemporaneous CD. True-positive, true-negative, false-positive, and false-negative CD and ASPD groups were identified. The results supported the hypotheses. Participants whose current behavior agreed with past behavior provided reliable retrospective CD reports. Inaccurate diagnoses occurred among participants whose current behavior was inconsistent with past behavior, either becoming more problematic (CD and ASPD false positives) or less problematic (CD and ASPD false negatives) over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
The thermal, optical and electrochemical properties of trans-poly(1-ethynylpyrene) (trans-PEP) and cis-poly(1-ethynylpyrene) (cis-PEP) have been studied as a function of polymer backbone configuration and internal stacking. Absorption spectra of the polymers showed that trans-PEP possesses a higher degree of conjugation than its homologue, cis-PEP. Intramolecular interactions occur between adjacent pendant pyrene units (associated pyrenes) present in each polymer, giving rise to static excimer emissions, strongest in cis-PEP because of the shorter distances between aromatic rings. Data resulting from excitation spectra and fluorescence decay profiles proved that such interactions take place in the ground state. Cyclic voltammetry of trans- and cis-PEP exhibited irreversible behaviors with different oxidation potentials as a result of their dissimilar geometry. 相似文献
65.
We evaluated Henley's (1973, 1977) and Goffman's (1976, 1979) theories about the relation between gender, nonverbal behavior, and perceived dominance in three studies. Our ratings of 1,106 media portrayals (Study 1) and observations of 1,257 people in public settings (Study 2) revealed few gender differences in frequency of head canting or body canting but some gender differences in frequency of smiling. In Study 3, we rated 96 advertisements that included all levels of gender, head cant, body cant, and smiling on five personality dimensions; we obtained only one predicted relation with dominance. It may be that the head canting, body canting, and smiling behaviors of females and males are actually more similar than was previously recognized and, contrary to hypotheses, dominance may not be strongly associated with these behaviors. We used previously suggested notions of gender as a categorizing strategy and as a diffuse status characteristic to explain why hypotheses that associate nonverbal behaviors with dominance and gender have had an acceptance unwarranted by the data. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Mohammed Es‐Souni Martha Es‐Souni Salah Habouti Nicole Pfeiffer Abdelilah Lahmar Matthias Dietze Claus‐Henning Solterbeck 《Advanced functional materials》2010,20(3):377-385
TiO2? Ag‐nanocomposites exhibit various desirable properties that make them suitable for a variety of applications, for example in photocatalysis and as bactericidal coatings. In this work, a new method for processing TiO2? Ag nanocomposites is presented. The nanocomposite films are fabricated from one precursor solution with high silver loading of up to 50%. The resulting films exhibit a microstructure consisting of TiO2? AgxO nanocomposites with a largely XRD‐amorphous TiO2 matrix containing brookite nanocrystals. This specific microstructure absorbs in the visible range so that photoreduction of Ag ions can be accomplished by using visible light. The thin films can be patterned using simple shadow masks. The illuminated areas show a high density of self‐organized nanoparticles (SNPs) and nanorods (SNRs), which are templated by the TiO2 porous network. The particle size can be tuned by varying the irradiation time. Most of the SNPs and SNRs form faceted crystals, which are mostly a combination of {111} and {110}. The application of these films as substrates for surface‐enhanced Raman scattering is shown. Enhancement factors as high as 4.6 × 106 could be obtained using rhodamine 6G dye molecules. More applications should involve photocatalytic water purification using visible light. 相似文献
67.
Pirooz Darabi Tingwen Li Konstantin Pougatch Martha Salcudean Dana Grecov 《Chemical engineering science》2010,65(15):4472-4483
A simplified mathematical model and numerical simulations of the governing Navier–Stokes equations are used to predict the shape evolution, rupture distance, and liquid distribution of stretching pendular liquid bridges between two equal-sized spherical solid particles. In the simplified model, the bridge shape is approximated with a parabola, and it is assumed that the surface tension effects dominate the viscous, inertial, and gravitational effects. For the numerical simulations, a commercial Computational Fluid Dynamics (CFD) software package – FLUENT – is used. The rupture distance predictions obtained with both models are compared with experimental data and a reasonable agreement is found. The results of the numerical investigations show that for simulations with negligible viscous, inertial, and gravitational effects, the rupture distance approaches an asymptotic value, which is close to the value predicted by the simplified model. The bridge profiles predicted using the simplified model and the numerical simulation are compared. It is found that a second-order polynomial appropriately represents the stable bridge shape for particles with identical contact angles; however, for liquid bridges between particles with different contact angles, the numerical simulations of the governing Navier–Stokes equations should be used. 相似文献
68.
Hernández-Ceruelos A Madrigal-Santillán E Morales-González JA Chamorro-Cevallos G Cassani-Galindo M Madrigal-Bujaidar E 《International journal of molecular sciences》2010,11(10):3793-3802
Chamomilla recutita (L.) Rauschert (Asteraceae), popularly known as chamomile, is a plant used in traditional medicine for various therapeutic purposes. Chamomile essential oil (CEO) is particularly known to inhibit the genotoxic damage produced by mutagens in mice somatic cells. The aim of this research was to determine the inhibitory potential of CEO on the genotoxic damage produced by daunorubicin (DAU) in mice germ cells. We evaluated the effect of 5, 50, and 500 mg/kg of essential oil on the rate of sister chromatid exchange (SCE) induced in spermatogonia by 10 mg/kg of the mutagen. We found no genotoxicity of CEO, but detected an inhibition of SCE after the damage induced by DAU; from the lowest to the highest dose of CEO we found an inhibition of 47.5%, 61.9%, and 93.5%, respectively. As a possible mechanism of action, the antioxidant capacity of CEO was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method and ferric thiocyanate assays. In the first test we observed a moderate scavenging potential of the oil; nevertheless, the second assay showed an antioxidant capacity similar to that observed with vitamin E. In conclusion, we found that CEO is an efficient chemoprotective agent against the damage induced by DAU in the precursor cells of the germinal line of mice, and that its antioxidant capacity may induce this effect. 相似文献
69.
Rothke Steven E.; Friedman Alan F.; Jaffe Alan M.; Greene Roger L.; Wetter Martha W.; Cole Patricia; Baker Kathryn 《Canadian Metallurgical Quarterly》2000,12(3):335
Data from several clinical samples and the Minnesota Multiphasic Personality Inventory–2 standardization group are presented to familiarize the reader with response patterns of different groups on a new validity scale designed to assist in the identification of exaggeration or fabrication of psychological disturbance. Sensitivity-specificity analyses are included along with suggestions for use of the F(p) Scale with other validity scales. Cautions about setting single cutoff scores are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.
We find much of interest, and little to disagree with, in the commentaries on our article. We take issue only with the suggestion that our article was provocative and submit that the attempt to understand the use of stimulants as smart pills does not imply an endorsement of the practice. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献