Synergy and other ineffective mixture risk definitions

A substantial effort has been spent over the past few decades to label toxicologic interaction outcomes as synergistic, antagonistic, or additive. Although useful in influencing the emotions of the public and the press, these labels have contributed fairly little to our understanding of joint toxic action. Part of the difficulty is that their underlying toxicological concepts are only defined for two chemical mixtures, while most environmental and occupational exposures are to mixtures of many more chemicals. Furthermore, the mathematical characterizations of synergism and antagonism are inextricably linked to the prevailing definition of 'no interaction,' instead of some intrinsic toxicological property. For example, the US EPA has selected dose addition as the no-interaction definition for mixture risk assessment, so that synergism would represent toxic effects that exceed those predicted from dose addition. For now, labels such as synergism are useful to regulatory agencies, both for qualitative indications of public health risk as well as numerical decision tools for mixture risk characterization. Efforts to quantify interaction designations for use in risk assessment formulas, however, are highly simplified and carry large uncertainties. Several research directions, such as pharmacokinetic measurements and models, and toxicogenomics, should promote significant improvements by providing multi-component data that will allow biologically based mathematical models of joint toxicity to replace these pairwise interaction labels in mixture risk assessment procedures.     

Salmonella spp. shedding by alberta beef cattle and the detection of Salmonella spp. in ground beef

Breeder cows, cattle recently arrived at feedlots, and cattle about to be shipped for slaughter were tested for Salmonella spp. No Salmonella spp. were detected in fecal samples from breeding cows. Nineteen of 1,000 (1.9%) fecal samples from recently arrived feedlot cattle were positive for Salmonella spp. compared to only 2 of 1,000 (0.2%) fecal samples taken within 2 weeks of slaughter. The positive fecal samples were collected in 5 of 50 (10%) "recent arrival" pens tested and in 1 of 50 (2%) pens tested within 2 weeks of slaughter. The serotypes isolated were Salmonella Agona, Salmonella Enteritidis, Salmonella Typhimurium DT104, and Salmonella 4,5,12:i:-. Ground beef samples purchased from retail outlets throughout Alberta were processed for Salmonella spp. Thirteen of 1,002 (1.3%) samples were positive for Salmonella spp. The serotypes isolated from ground beef were Salmonella Anatum, Salmonella Heidelberg, Salmonella Montevideo, Salmonella Typhimurium, Salmonella Typhimurium var. Copenhagen, and Salmonella Rough-O:i:1,2. The antibiotic resistance and pulsed-field electrophoresis gel macrorestriction patterns of all isolates were compared.     

Polymerase chain reaction amplification of DNA from aged blood stains: quantitative evaluation of the "suitability for purpose" of four filter papers as archival media

In collaboration with the Armed Forces Institute of Pathology's Department of Defense DNA Registry, the National Institute of Standards and Technology recently evaluated the performance of a short tandem repeat multiplex with dried whole blood stains on four different commercially available identification card matrixes. DNA from 70 stains that had been stored for 19 months at ambient temperature was extracted or directly amplified and then processed using routine methods. All four storage media provided fully typeable (qualitatively identical) samples. After standardization, the average among-locus fluorescence intensity (electropherographic peak height or area) provided a suitable metric for quantitative analysis of the relative amounts of amplifiable DNA in an archived sample. The amounts of DNA in Chelex extracts from stains on two untreated high-purity cotton linter pulp papers and a paper treated with a DNA-binding coating were essentially identical. Average intensities for the aqueous extracts from a paper treated with a DNA-releasing coating were somewhat lower but also somewhat less variable than for the Chelex extracts. Average intensities of directly amplified punches of the DNA-binding paper were much larger but somewhat more variable than the Chelex extracts. Approximately 25% of the observed variation among the intensity measurements is shared among the four media and thus can be attributed to intrinsic variation in white blood count among the donors. All of the evaluated media adequately "bank" forensically useful DNA in well-dried whole blood stains for at least 19 months at ambient temperature.     

A tandem mass spectrometer for improved transmission and analysis of large macromolecular assemblies

We report the design and first applications of a tandem mass spectrometer (a quadrupole time-of-flight mass spectrometer) optimized for the transmission and analysis of large macromolecular assemblies. Careful control of the pressure gradient in the different pumping stages of the instrument has been found to be essential for the detection of macromolecular particles. Such assemblies are, however, difficult to analyze by tandem-MS approaches, because they give rise to signals above m/z 3,000-4,000, the limit for commercial quadrupoles. By reducing the frequency of the quadrupole to 300 kHz and using it as a narrow-band mass filter, we show that it is possible to isolate ions from a single peak at m/z 22,000 in a window as narrow as 22 m/z units. Using cesium iodide cluster signals, we show that the mass range in the time-of-flight (TOF) analyzer extends beyond m/z 90,000, in theory to more than m/z 150,000. We also demonstrate that the resolution of the instrument is greater than 3,000 at m/z 44,500. Tandem-MS capabilities are illustrated by separating components from heterooligomeric assemblies formed between tetrameric transthyretin, thyroxine, retinol-binding protein, and retinol. Isolation of a single charge state at m/z 5,340 in the quadrupole and subsequent collision-induced dissociation (CID) in the gas-filled collision cell leads to the formation of ions from individual subunits and subcomplexes, identified by their mass and charge in the TOF analyzer.     

Easily constructed spectroelectrochemical cell for batch and flow injection analyses

The design and performance of an easily constructed spectroelectrochemical cell suitable for batch and flow injection measurements are described. The cell is fabricated from a commercially available 5-mm quartz cuvette and employs 60 ppi reticulated vitreous carbon as the working electrode, resulting in a reasonable compromise between optical sensitivity and thin-layer electrochemical behavior. The spectroelectrochemical traits of the cell in both batch and flow modes were evaluated using aqueous ferricyanide and compare favorably to those reported previously for similar cells.     

Efficacy of a tailored tobacco control program on long-term use in a population of U.S. Military troops.

The authors evaluated the effect of a brief tailored smoking control intervention delivered during basic military training on tobacco use in a population of military personnel (N = 33,215). Participants were randomized to either a tobacco use intervention (smoking cessation, smokeless tobacco use cessation, or prevention depending on tobacco use history) or a health education control condition. Results indicated that smokers who received intervention were 1.16 (95% confidence interval [CI] = 1.04, 1.30) times (7-day point prevalence) and 1.23 (95% CI = 1.07, 1.41) times (continuous abstinence) more likely to be abstinent than controls from smoking cigarettes at the 1-year follow-up (p p     

Exemplary efforts in psychology to recruit and retain graduate students of color.

Many psychology departments are striving for a greater representation of students of color within their graduate preparation programs with the aim of producing a more diverse pool of psychological service providers, scientists, and educators. To help improve the minority pipeline in psychology, the authors identify and describe recruitment and retention strategies used at 11 departments and programs considered to be making exemplary efforts to attract and retain minority students of color. The strategies most consistently used included engaging current minority faculty and students in recruitment activities, offering attractive financial aid packages, having faculty members make personal contacts with prospective students, creating linkages with historical institutions of color, having (or approached having) a critical mass of faculty and students of color, offering a diversity issues course, and engaging students in diversity issues research. Despite the similarities, the programs and departments were each distinctive and innovative in their overall approaches to student recruitment and retention. Highlighting the strategies used at successful institutions may help others develop plans for improving the minority pipeline within their own departments and programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

“双重授权”的开源新模式

开源并不是一个新观念。科学界从根本上看就是以这种观念为基础的,他们为了促进科学发展,公开共享最重要的信息。科学进步之所以能达到今天这样的速度,就是因为信息能够在全世界的科学家之间共享,他们共同参与测试、验证和改进工作。科学家们极少从头开始、而是以以前的发现和研究为基础进行新的探索,继续做出改进和完善。如果没有前人的工作,每隔一段时间就出现的那些重大科学突破是不可能发生的。与此相同的模式在软件开发领域也存在。这个领域的“科学家”是软件开发人员,他们的主要工作是利用像Qt这样的工具来开发软件代码。从微波炉到…     

Double-blind photoarray administration as a safeguard against investigator bias.

[Correction Notice: An erratum for this article was reported in Vol 85(2) of Journal of Applied Psychology (see record 2007-17253-001). On page 947, the graphs within Figure 1 were incorrectly labeled. The corrected figure appears in this erratum.] This experiment examined whether a photoarray administrator's knowledge of a suspect's identity increased false identification rates. Fifty participant–administrators (PAs) presented 50 participant–witnesses (PWs) two perpetrator-absent photoarrays following a live staged crime involving two perpetrators. For one photoarray per trial, the experimenter revealed the suspect's identity to the PA. Each PA presented the photoarrays sequentially or simultaneously in the presence or absence of an observer. When the observer was present, PA knowledge of the suspect's identity had a biasing effect in sequential photoarrays only. This pattern did not emerge when the observer was absent. The experimental manipulations did not affect PAs' and PWs' ratings of photoarray fairness or PWs' ratings of pressure to make an identification. These data suggest that only administrators who are blind to the suspect's identity should present sequential photoarrays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-Speed Tools for Global Information Management.II. Specifications and Uses of the Transparent Query Language (TQL) Part IIF. Additional Uses of TQL, Data Structures, Concise Definitions, Conclusions and Acknowledgments

This part, PART IIF [6], concludes the document HIGH-SPEED TOOLS FOR GLOBAL INFORMATION MANAGEMENT. II. Specifications and Uses of the Transparent Query Language (TQL) [1–6]. It describes novel applications of TQL, the key data structures, and contains a dictionary of Transparent Query Language terms. PART IIF references PART IIA [1], PART IIB [2], PART IIC [3], PART IID [4], and PART IIE [5] and contains Conclusions and Acknowledgements.