Electromyographic response of the labial muscles during normal liquid swallows using a spoon, a straw, and a cup

PURPOSE: To determine if ethnic and gender differences in smoking (lifetime prevalence and 30-day prevalence) exist among a cohort of Asian, black, Hispanic, and white inner-city adolescents during the 3-year middle school period. METHODS: Students in 22 urban schools completed self-report questionnaires and provided carbon monoxide breath samples at three annual assessments. Chi-square analyses were conducted to test for associations between ethnic group (Asian, black, Hispanic, and white) and smoking and to test for gender differences in smoking within each ethnic group. Additional analyses examined differences in smoking between two Hispanic subgroups (Puerto Rican and Dominican). RESULTS: Ethnicity was associated with lifetime smoking prevalence at all three assessment points but was only associated with 30-day smoking prevalence at the 2-year follow-up. However, there were no differences in smoking between Puerto Rican and Dominican youth. Black girls reported higher lifetime smoking prevalence than black boys at all three assessments. At the 2-year follow-up, Asian boys reported higher lifetime smoking prevalence than Asian girls; Hispanic girls reported higher 30-day prevalence than Hispanic boys. CONCLUSIONS: White and Hispanic adolescents were at higher risk for smoking relative to Asian and black adolescents. With the exception of white youth, gender differences were found within each ethnic group.     

A simplified modeling approach using microbial growth kinetics for predicting exposure concentrations of organic chemicals in treated wastewater effluents

Various mathematical relationships have been used to assess exposure concentrations of organic chemicals when emissions occur via wastewater treatment. These relationships range from a simple removal factor calculation to more sophisticated approaches using kinetic based mathematical models. While these existing approaches have been used by decision makers to screen new chemicals for exposure assessments, they all have limitations in the predictive capabilities. Thus, a simplified modeling approach grounded in sound scientific fundamentals that utilizes relatively easy to obtain input parameters is needed. In this paper a simplified modeling approach that utilizes microbial growth kinetics was developed for predicting effluent concentrations in secondary biological wastewater treatment systems. Receiving water predicted exposure concentrations (PEC) are assessed by using a dilution factor. One advantage of this approach is that it allows for wastewater treatment plant effluent concentrations, and therefore receiving water exposure levels, to be predicted with a minimum amount of experimental data. It also provides quantitative data that can be used to assess the relative biodegradability of different chemicals for use in regulatory and risk assessment activities.     

Algorithms for roundoff error analysis —A relative error approach

Methods are presented for performing various error analyses of numerical algorithms. These analyses include forward, backward, and B-analysis (a combination of forward and backward). These analyses additionally provide alternative criteria by which different algorithms that solve the same problem may be compared. The conclusions of various comparison criteria are related to the correlation of errors in each algorithm. Finally, the analysis of a composite algorithm, which is made up of concatenated sub-algorithms, is given in terms of analyses done on its parts.

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Zusammenfassung In dieser Arbeit werden Methoden vorgestellt, die es gestatten, verschiedene Fehleranalysen numerischer Algorithmen zu vollziehen. Darunter befinden sich Vorwärts- und Rückwärtsanalyse (forward and backward analysis) sowie beidseitige Analyse (B-analysis, eine Kombination von forward and backward) ein. Diese Analysen liefern zusätzlich weitere Kriterien, durch welche verschiedene Algorithmen, die dasselbe Problem lösen, verglichen werden können. Die Aussagen der verschiedenen Vergleichskriterien beziehen sich auf die Fehlerkorelation in jedem Algorithmus. Schließlich wird die Analyse zusammengesetzter Algorithmen, welche aus verketteten Subalgorithmen bestehen, mit Hilfe der Analysen, die an den Teilen vollzogen wurden, dargestellt.

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This work was supported in part by the National Science Foundation under NSF Grant MCS 75-21758.     

Electrical conduction phenomena in thin tetracene films

Thin film aluminium oxide capacitors using anodic Al₂O₃ as the dielectric are described. The dependence of oxide thickness and dielectric loss on anodization voltage was studied. Variation of capacitance with temperature and frequency was also investigated. The capacitors were used in conjunction with tantalum resistors to fabricate an astable multivibrator circuit and the waveforms were recorded. The combination of aluminium oxide capacitors and tantalum resistors has some advantages over all-tantalum RC networks.     

The FT-30 seawater reverse osmosis membrane--element test results

A thin-film composite reverse osmosis (RO) membrane has been developed that provides excellent performance when used in single-pass seawater systems. This membrane, designated FT-30, gives superior performance in such areas as flux, salt rejection, chemical stability, and microbiological resistance. In addition, it is resistant to some oxidizing disinfectant agents, although it is not fully resistant to chlorine; elements fabricated from the membrane have shown damage after 2,000 to 2,500 hours exposure to seawater at 0.5 milligrams per liter (mg/l) active chlorine. It appears that the membrane can operate continuously at active chlorine concentrations below 0.2 mg/l.Several long-term studies were carried out at the OWRT Wrightsville Beach Test Facilities. In actual trials in seawater systems, salt rejections as high as 99.5 percent and fluxes of 23 gfd have been obtained when tested at 800 psi and 25°C. Some of the elements have been in continuous operation for over 4, 000 hours with no deterioration in salt rejection and with only the normal flux decline usually associated with compaction and scaling. Other elements have been installed in small seawater systems with normal intermittant use for almost two years with no serious loss in performance.     

Decolorization of alkaline TNT hydrolysis effluents using UV/H(2)O(2)

Effects of H(2)O(2) dosage (0, 10, 50, 100 and 300 mg/l), reaction pH (11.9, 6.5 and 2.5) and initial color intensity (85, 80 and 60 color unit) on decolorization of alkaline 2,4,6-trinitrotoluene (TNT) hydrolysis effluents were investigated at a fixed UV strength (40 W/m(2)). Results indicated that UV/H(2)O(2) oxidation could efficiently achieve decolorization and further mineralization. Pseudo first-order decolorization rate constants, k, ranged between 2.9 and 5.4 h(-1) with higher values for lower H(2)O(2) dosage (i.e., 10 mg/l H(2)O(2)) when the decolorization occurred at the reaction pH of 11.9, whereas a faster decolorization was achieved with increase in H(2)O(2) dosage at both pH 6.5 and 2.5, resulting in the values of k as fast as 15.4 and 26.6 h(-1) with 300 mg/l H(2)O(2) at pH 6.5 and 2.5, respectively. Difference in decolorization rates was attributed to the reaction pH rather than to the initial color intensity, resulting from the scavenging of hydroxyl radical by carbonate ion. About 40% of spontaneous mineralization was achieved with addition of 10 mg/l H(2)O(2) at pH 6.5. Efficient decolorization and extension of H(2)O(2) longevity were observed at pH 6.5 conditions. It is recommended that the colored effluents from alkaline TNT hydrolysis be neutralized prior to a decolorization step.     

Evolutionary techniques for updating query cost models in a dynamic multidatabase environment

Deriving local cost models for query optimization in a dynamic multidatabase system (MDBS) is a challenging issue. In this paper, we study how to evolve a query cost model to capture a slowly-changing dynamic MDBS environment so that the cost model is kept up-to-date all the time. Two novel evolutionary techniques, i.e., the shifting method and the block-moving method, are proposed. The former updates a cost model by taking up-to-date information from a new sample query into consideration at each step, while the latter considers a block (batch) of new sample queries at each step. The relevant issues, including derivation of recurrence updating formulas, development of efficient algorithms, analysis and comparison of complexities, and design of an integrated scheme to apply the two methods adaptively, are studied. Our theoretical and experimental results demonstrate that the proposed techniques are quite promising in maintaining accurate cost models efficiently for a slowly changing dynamic MDBS environment. Besides the application to MDBSs, the proposed techniques can also be applied to the automatic maintenance of cost models in self-managing database systems.Received: 25 November 2002, Accepted: 20 May 2003, Published online: 30 September 2003Edited by: L. LiuResearch supported by the US National Science Foundation under Grant # IIS-9811980 and The University of Michigan under OVPR and UMD grants.     

The topical anti-inflammatory effects of piroxicam in rodents

Piroxicam is a structurally novel, long-acting anti-inflammatory drug with potent activity following oral administration in animal models of inflammation and in human inflammatory diseases. The present studies, performed in rats, demostrate that topically applied piroxicam is a potent inhibitor of inflammation induced by either carrageenin or complete Freund's adjuvant. Comparable potencies (ED50 approximately 1--5 mg/kg) were obtained for topically and orally administered piroxicam in these models of inflammation. The potency of topical piroxicam exceeds that of topically applied bufexamac or phenylbutazone in the rat adjuvant arthritis model.     

Distinct requirements for zebrafish angiogenesis revealed by a VEGF-A morphant

Angiogenesis is a fundamental vertebrate developmental process that requires signalling by the secreted protein vascular endothelial growth factor-A (VEGF-A). VEGF-A functions in the development of embryonic structures, during tissue remodelling and for the growth of tumour-induced vasculature. The study of the role of VEGF-A during normal development has been significantly complicated by the dominant, haplo-insufficient nature of VEGF-A-targeted mutations in mice. We have used morpholino-based targeted gene knock-down technology to generate a zebrafish VEGF-A morphant loss of function model. Zebrafish VEGF-A morphant embryos develop with an enlarged pericardium and with major blood vessel deficiencies. Morphological assessment at 2 days of development indicates a nearly complete absence of both axial and intersegmental vasculature, with no or reduced numbers of circulating red blood cells. Molecular analysis using the endothelial markers fli-1 and flk-1 at 1 day of development demonstrates a fundamental distinction between VEGF-A requirements for axial and intersegmental vascular structure specification. VEGF-A is not required for the initial establishment of axial vasculature patterning, whereas all development of intersegmental vasculature is dependent on VEGF-A signalling. The zebrafish thus serves as a quality model for the study of conserved vertebrate angiogenesis processes during embryonic development.     

Children's differentiation between beliefs about matters of fact and matters of opinion.

Two experiments investigated children's implicit and explicit differentiation between beliefs about matters of fact and matters of opinion. In Experiment 1, 8- to 9-year-olds' (n = 88) explicit understanding of the subjectivity of opinions was found to be limited, but their conformity to others' judgments on a matter of opinion was considerably lower than their conformity to others' views regarding an ambiguous fact. In Experiment 2, children aged 6, 8, or 10 years (n = 81) were asked to make judgments either about ambiguous matters of fact or about matters of opinion and then heard an opposing judgment from an expert. All age groups conformed to the opposing judgments on factual matters more than they did to the experts' views on matters of opinion. However, only the oldest children explicitly recognized that opinions are subjective and cannot be "wrong." Implications of these results for models of children's reasoning about epistemic states are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)