Immobilized enzyme-linked DNA-hybridization assay with electrochemical detection for Cryptosporidium parvum hsp70 mRNA

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.     

The Hydrogeochemistry of Arsenic in the Clara Mine,Germany

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.     

Correction to correction to Ilies et al. (2009).

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)     

Effect of experimental methodology on the JND of the black level for natural images

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.     

Goodness-of-fit tests in parametric regression based on the estimation of the error distribution

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.     

Elliptic curve cryptography on embedded multicore systems

The increasing use of network-connected embedded devices and online transactions creates a growing demand of network security for embedded systems. The security requirements, such as authentication, confidentiality and integrity, always make computationally intensive processes and can easily become the bottleneck of the related applications. In this paper we implement Elliptic Curve Cryptography (ECC) (Miller in Lecture Notes in Computer Science, vol. 218, pp. 417–426, 1985; Koblitz in Math. Comput. 48:203–209, 1987) on an embedded multicore system, and explore the task scheduling methods in different levels. First, we propose an instruction scheduling method that utilizes all the cores to perform one modular operation in parallel. Second, we perform multiple modular operations with multiple cores in parallel. The performance of those two implementations is compared and a scheduling method combining these two types of parallelism is proposed. We discuss the details of our proposed method by using an FPGA implementation of ECC over a prime field.