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81.
An electrochemical enzyme-linked immobilized DNA-hybridization assay for the detection of Cryptosporidium parvum in water has been developed. The target molecule was a 121-nucleotide sequence from the C. parvum heat shock protein 70 (hsp70 mRNA from U71181 gene). This analyte offers the possibility of distinguishing dead from live oocysts. The assay involves covalent attachment of a primary DNA probe via its 5'-amine-terminus to self-assembled monolayers of mercaptoundecanoic acid to a gold surface. The primary DNA probe was used to capture the target (sequence 1039-1082 of U71181 gene for the mRNA), by hybridization to a 20-base complementary sequence on the target (at sequence 1063-1082). A secondary DNA probe labeled with alkaline phosphatase (AP) was then hybridized to base sequence 1039-1062 on the target. p-Aminophenol, which is enzymatically generated by the immobilized AP from p-aminophenyl phosphate (PAPP), is detected using electrochemistry. The peak current of cyclic voltammograms from a PAPP solution, in which gold-coated silicon wafer modified with the complete assembly of the assay components was incubated, is linear with concentration of the target (5-50 microg/mL, where P1 and P2-AP concentrations are 50 microg/mL). A detection limit of 2 microg/mL (or 146 nM) of the DNA target was obtained. Cross-reactivity tests showed high selectivity for heat-shocked C. parvum. No signal was obtained for either the synthetic DNA for hsp70 of Campylobacter lari, Escherichia coli, Giardia lamblia, Salmonella typhimurium, and Listeria monocytogenes or for the products of heat-shocked whole organisms of E. coli, G. lamblia, Staphylococcus aureus, and Cryptosporidium muris. 相似文献
82.
The Hydrogeochemistry of Arsenic in
the Clara Mine,Germany 总被引:1,自引:1,他引:0
Yinian?Zhu Broder?J.?MerkelEmail author Ingrid?Stober Kurt?Bucher 《Mine Water and the Environment》2003,22(3):110-117
Abstract.
The oxidative dissolution of primary arsenic-bearing
sulfide minerals in barite-fluorite veins is a potential source
of arsenic in the Clara Mine. Geological structures, especially
the mineral veins, provide potential pathways for the water. The
highest arsenic concentrations are found in ground water within
the eastern part of the mine. Arsenic and major ions are
positively correlated and provide evidence that arsenic is
likely derived locally from the water-vein/water-rock
interaction. Geochemical modeling with PHREEQC shows all the
arsenate mineral phases to be significantly undersaturated,
although secondary arsenate minerals are common in the oxidized
part of the deposit. The mine waters plot near the boundary of
Fe(OH)3 and
Fe2+ in the pH-Eh diagram for the
As-Fe-S-H2O-system. Arsenic occurs as the
5-valent species
and
. Statistical analysis
illustrates a strong association between As, Fe, pH, and
HCO3. Oxidation of the primary As-bearing
minerals, such as pyrite and arsenopyrite, and the subsequent
behavior of the oxyanion, arsenate, generally controls the
distribution and speciation of arsenic. The low concentrations
of dissolved As is due to co-precipitation and adsorption of
arsenate by Fe, Al, and Mn (oxy)hydroxides. 相似文献
83.
84.
Ilies Remus; Fulmer Ingrid Smithey; Spitzmuller Mathias; Johnson Michael 《Canadian Metallurgical Quarterly》2010,95(3):601
Reports an error in "'Personality and citizenship behavior: The mediating role of job satisfaction': Correction" by Remus Ilies, Ingrid Smithey Fulmer, Matthias Spitzmuller and Michael D. Johnson (Journal of Applied Psychology, 2010[Mar], Vol 95[2], 404). The volume number of the original article was incorrectly identified. It should have been identified as Vol. 94. (The following abstract of the original article appeared in record 2010-04488-016.) Reports an error in "Personality and citizenship behavior: The mediating role of job satisfaction" by Remus Ilies, Ingrid Smithey Fulmer, Matthias Spitzmuller and Michael D. Johnson (Journal of Applied Psychology, 2009[Jul], Vol 94[4], 945-959). The path coefficients presented in the figures are slight overestimates. For example, in Figure 1 (p. 952), the paths from Agreeableness and Conscientiousness to Job Satisfaction should be .11 and .23 instead of .12 and .28, the direct effects from Agreeableness and Conscientiousness to Citizenship Behavior should be .10 and .16 instead of .11 and .18, and the paths from Job Satisfaction to Citizenship Behavior should be .28 (.22) instead of .34 (.26). The statistical significance of the path coefficients is correct, and so are the substantive conclusions based on the better fit of the partially mediated models relative to the fully mediated models. Also, the meta-analytic estimates presented in Table 1 (p. 949), Table 2 (p. 950), and Table 3 (p. 951) are correct. (The following abstract of the original article appeared in record 2009-10167-018.) Using meta-analytic path analysis, the authors tested several structural models linking agreeableness and conscientiousness to organizational citizenship behavior (OCB). Results showed that the 2 personality traits had both direct effects and indirect effects—through job satisfaction—on overall OCB. Meta-analytic moderator analyses that distinguished between individual- and organization-targeted citizenship behaviors (OCB-I and OCB-O) showed that agreeableness was more closely related with OCB-I and conscientiousness with OCB-O. Finally, the path analyses predicting OCB-I and OCB-O offered further support for the general hypothesis that these 2 constructs are distinct. That is, the results of these analyses revealed that agreeableness had both direct and indirect effects on OCB-I but only indirect effects on OCB-O, and that for conscientiousness the pattern of direct and indirect effects was exactly opposite (direct and indirect effects on OCB-O but only indirect effects on OCB-I). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
ShaoLing Qin Shu Ge HanChun Yin Lu Liu Ingrid Heynderickx 《Journal of the Society for Information Display》2009,17(8):687-694
Abstract— The effect of experimental methodology on the Just Noticeable Difference (JND) of the black level (BL) is assessed using a set of representative natural images. Two methodologies, known in psychophysics to determine JNDs, are mutually compared: an adapted method of adjustment with a same‐difference task and a one‐up‐two‐down staircase method with a two‐alternative forced‐choice task. Thus far, the literature has shown contradictory results for which of the two methods yields the lower difference thresholds. Experimental results show that the second method yields lower JNDs, but is slightly less efficient. Based on this second method, it was found that the JND of the BL for natural images ranges from 0.2 to 1.0 cd/m2, varying with image content significantly. 相似文献
86.
87.
Consider a heteroscedastic regression model Y=m(X)+σ(X)ε, where m(X)=E(Y|X) and σ
2(X)=Var (Y|X) are unknown, and the error ε is independent of the covariate X. We propose a new type of test statistic for testing whether the regression curve m(⋅) belongs to some parametric family of regression functions. The proposed test statistic measures the distance between the
empirical distribution function of the parametric and of the nonparametric residuals. The asymptotic theory of the proposed
test is developed, and the proposed testing procedure is illustrated by means of a small simulation study and the analysis
of a data set. 相似文献
88.
Michael C. Mulder 《Robotics and Computer》1990,7(3-4):229-242
The theme of this presentation is that technical barriers exist that have prevented widespread industrial use of intelligent robots and manufacturing machines. These barriers must be successfully addressed for major progress to occur in these fields. Each barrier is identified and discussed, current research projects addressing each barrier in that area are presented, and opinions expressed as to how that barrier will be removed. This paper presents some current industry/university cooperative research results that reinforce the author's view; nine selected projects will be highlighted. Areas of special interest are presented including intelligent robots, intelligent machines, adaptive control structures, the potential of neural nets, the influence of cognitive processes, and the potential for autonomous machine operation in the factory of the future. Some comments on the mechanisms needed for successful industry/university cooperative research are offered. 相似文献
89.
The exploration of dynamic stability in bidedal machines requires a great deal of knowledge about the science of balancing, both equilibrium and motion. Recent work in robotic legged locomotion has concentrated on systems that require three or more legs on the ground at any given time. This research focuses on adaptive control strategies for a bipedal machine that will allow balance and controlled motion with one leg and, if not walking, on two legs on the ground at any given time. Our approach is to optimize a set of balance and motion profiles through extensive simulation and to validate the profiles on an experimental testbed. Once validated as capable of providing dynamic stability, the adaptive control model uses these profiles as nominal control. The sensory input is then used to modify the nominal control to allow precise control at each sampling period. Simply stated, our control model continuously measures the rate of fall of the biped, and adjusts torques at the knees and hips to constrain this fall to dynamic balance and controlled motion. As should be suspected at this time, our control model is sensor driven and does not require a solution to the Lagrangian equations of motion. The result is a faster, less complex, adaptive control process. Our experimental bipedal testbed currently, and repeatedly, exhibits 25 + stable steps on a flat but slightly varied terrain. Current technology could not provide the kind of actuation and measurements necessary to implement our control model; therefore, our team has developed new low pressure, servoed hydraulic systems and sensory devices. Our most recent experimentation has used parallel computing methods and devices in the C + + programming language on a transputer (parallel computer) based Cogent XTM parallel computing workstation.
A new dimension to our research is the translation of our knowledge to manufacturing systems and machines. We are currently investigating how our knowledge of limb coordination and reflex can be applied to the coordination of multiple jointed appendages. In addition, we will explore the use of our positioning and balancing technology in the work cell. 相似文献
90.
S Notermans P S Soentoro N M Bolder R W Mulder 《International journal of food microbiology》1991,13(1):55-61
Survival of Listeria species was tested in liquid egg products such as albumen, yolk, whole egg and whole egg containing 25% sucrose. At an incubation temperature of 4 degrees C Listeria survived in all products, and even increased slightly in yolk, whole egg and whole egg containing 25% sucrose. However, at 20-22 degrees C, in whole egg containing sucrose, a rapid an dramatic decrease in numbers of Listeria was observed. Following this initial decrease, an increase in the numbers of Listeria was observed. The ability to grow in liquid egg containing sucrose was maintained upon reinoculation into a freshly prepared product. However, this property disappeared after subculturing in brain heart infusion broth. The significance of these findings is discussed. 相似文献