The Engineers That Time Forgot [Guest Bytes]

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Biosynthesis of Phenolic Glycosides from Phenylpropanoid and Benzenoid Precursors in <Emphasis Type="Italic">Populus</Emphasis>

Salicylate-containing phenolic glycosides (PGs) are abundant and often play a dominant role in plant-herbivore interactions of Populus and Salix species (family Salicaceae), but the biosynthetic pathway to PGs remains unclear. Cinnamic acid (CA) is thought to be a precursor of the salicyl moiety of PGs. However, the origin of the 6-hydroxy-2-cyclohexen-on-oyl (HCH) moiety found in certain PGs, such as salicortin, is not known. HCH is of interest because it confers toxicity and antifeedant properties against herbivores. We incubated Populus nigra leaf tissue with stable isotope-labeled CA, benzoates, and salicylates, and measured isotopic incorporation levels into both salicin, the simplest PG, and salicortin. Labeling of salicortin from [¹³C₆]-CA provided the first evidence that HCH, like the salicyl moiety, is a phenylpropanoid derivative. Benzoic acid and benzaldehyde also labeled both salicyl and HCH, while benzyl alcohol labeled only the salicyl moiety in salicortin. Co-administration of unlabeled benzoates with [¹³C₆]-CA confirmed their contribution to the biosynthesis of the salicyl but not the HCH moiety of salicortin. These data suggest that benzoate interconversions may modulate partitioning of phenylpropanoids to salicyl and HCH moieties, and hence toxicity of PGs. Surprisingly, labeled salicyl alcohol and salicylaldehyde were readily converted to salicin, but did not result in labeled salicortin. Co-administration of unlabeled salicylates with labeled CA suggested that salicyl alcohol and salicylaldehyde may have inhibited salicortin biosynthesis. A revised metabolic grid model of PG biosynthesis in Populus is proposed, providing a guide for functional genomic analysis of the PG biosynthetic pathway.     

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Assessing the effects of soil grading on the moisture content-dependent thermal conductivity of stabilised rammed earth materials

New data for both the dry-state and the moisture content-dependent thermal conductivity of cement-stabilised rammed earth (SRE) materials is presented. For highly compacted SRE materials, no correlation was found between thermal conductivity and dry density or void ratio. The thermal conductivity of SRE materials increases linearly with the saturation ratio, S_r of the material and can be expressed as λ¹, the moisture content-dependent thermal conductivity. The sensitivity of λ¹ to an increase in the saturation ratio of SRE materials varies according to soil grading. The influence of grading parameters on λ¹ can cause material variations of approximately 0.8 m² K/W. The experimental data has been applied to standard SRE wall design configurations and the effect of wall moisture content on the total thermal resistance has been shown. The R-value of an SRE wall irrespective of cavity insulation can vary by as much as 0.13 m² K/W.     

Diversity gain from a single-port adaptive antenna using switchedparasitic elements illustrated with a wire and monopole prototype

A new concept in single-port adaptive antennas using parasitic elements with switched terminating impedances is presented including results from a concept prototype. Each parasitic element can be effectively terminated in three impedance values. The antenna concept provides multiple radiation patterns with a single RF signal port without the need for RF switches or phase shifters in the direct RF signal path. Impedance variations in the active antenna element are minimized by use of only rotationally symmetric configurations. Measured patterns are used to demonstrate the performance improvement expected using switched diversity combining in a simulated uniform scattering scenario. The concept prototype having one active element and four parasitic elements, is shown to have equivalent diversity performance to between three and four uncorrelated branches     

Gestalt perspectives on cognitive science and on experimental psychology.

At the 1st author's request, the 2nd author was interviewed on Gestalt psychology's origins and utility for modern experimental psychology. Wertheimer's connections with Gestalt psychologists Max Wertheimer and Wolfgang K?hler and his study of Gestalt problems and methods, give him a special perspective on these issues. Several points for modern psychology emerge from the Gestalt perspective. Phenomena should be studied within their full context; there is a need to acknowledge the domain specificity of principles in experimental psychology; it is wise to study phenomena that either exist in the real world or have close real-world analogues; psychology must recognize interchanges between organisms and surroundings as determinants of behavior; and a data-driven perspective must complement, and sometimes replace, theory driven searches for broadly applicable, nondomain-specific principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Recurrence in major depression: A conceptual analysis": Correction to Monroe and Harkness (2011).

Reports an error in "Recurrence in major depression: A conceptual analysis" by Scott M. Monroe and Kate L. Harkness (Psychological Review, Advanced Online Publication, Sep 5, 2011, np). An incorrect version of Figure 2 was published, and Figure 3 was published in color instead of Figure 4. Also, in Table 1, the acronym “(FLED)” should not have been included in the Recurrence section, under Confusion to avoid, following “Not to be confused with a first lifetime recurrence.” All versions of this article have been corrected. (The following abstract of the original article appeared in record 2011-20042-001.) Theory and research on major depression have increasingly assumed a recurrent and chronic disease model. Yet not all people who become depressed suffer recurrences, suggesting that depression is also an acute, time-limited condition. However, few if any risk indicators are available to forecast which of the initially depressed will or will not recur. This prognostic impasse may be a result of problems in conceptualizing the nature of recurrence in depression. In the current paper we first provide a conceptual analysis of the assumptions and theoretical systems that presently structure thinking on recurrence. This analysis reveals key concerns that have distorted views about the long-term course of depression. Second, as a consequence of these theoretical problems we suggest that investigative attention has been biased toward recurrent forms of depression and away from acute, time-limited conditions. Third, an analysis of how these theoretical problems have influenced research practices reveals that an essential comparison group has been omitted from research on recurrence: people with a single lifetime episode of depression. We suggest that this startling omission may explain why so few predictors of recurrence have as yet been found. Finally, we examine the reasons for this oversight, document the validity of depression as an acute, time-limited disorder, and provide suggestions for future research with the goal of discovering early risk indicators for recurrent depression. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Does mentioning “some people” and “other people” in a survey question increase the accuracy of adolescents' self-reports?

A great deal of developmental research has relied on self-reports solicited using the “some/other” question format (“Some students think that… but other students think that…”). This article reports tests of the assumptions underlying its use: that it conveys to adolescents that socially undesirable attitudes, beliefs, or behaviors are not uncommon and legitimizes reporting them, yielding more valid self-reports than would be obtained by “direct” questions, which do not mention what other people think or do. A meta-analysis of 11 experiments embedded in four surveys of diverse samples of adolescents did not support the assumption that the some/other form increases validity. Although the some/other form led adolescents to think that undesirable attitudes, beliefs, or behaviors were more common and resulted in more reports of those attitudes and behaviors, answers to some/other questions were lower in criterion validity than were answers to direct questions. Because some/other questions take longer to ask and answer and require greater cognitive effort from participants (because they involve more words), and because they decrease measurement accuracy, the some/other question format seems best avoided. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The influence of delaying judgments of learning on metacognitive accuracy: A meta-analytic review.

Many studies have examined the accuracy of predictions of future memory performance solicited through judgments of learning (JOLs). Among the most robust findings in this literature is that delaying predictions serves to substantially increase the relative accuracy of JOLs compared with soliciting JOLs immediately after study, a finding termed the delayed JOL effect. The meta-analyses reported in the current study examined the predominant theoretical accounts as well as potential moderators of the delayed JOL effect. The first meta-analysis examined the relative accuracy of delayed compared with immediate JOLs across 4,554 participants (112 effect sizes) through gamma correlations between JOLs and memory accuracy. Those data showed that delaying JOLs leads to robust benefits to relative accuracy (g = 0.93). The second meta-analysis examined memory performance for delayed compared with immediate JOLs across 3,807 participants (98 effect sizes). Those data showed that delayed JOLs result in a modest but reliable benefit for memory performance relative to immediate JOLs (g = 0.08). Findings from these meta-analyses are well accommodated by theories suggesting that delayed JOL accuracy reflects access to more diagnostic information from long-term memory rather than being a by-product of a retrieval opportunity. However, these data also suggest that theories proposing that the delayed JOL effect results from a memorial benefit or the match between the cues available for JOLs and those available at test may also provide viable explanatory mechanisms necessary for a comprehensive account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)