How does working memory enable number-induced spatial biases?

Number-space associations are a robust observation, but their underlying mechanisms remain debated. Two major accounts have been identified. First, spatial codes may constitute an intrinsic part of number representations stored in the brain – a perspective most commonly referred to as the Mental Number Line account. Second, spatial codes may be generated at the level of working memory when number (or other) representations are coordinated in function of a specific task. The aim of the current paper is twofold. First, whereas a pure Mental Number Line account cannot capture the complexity of observations reported in the literature, we here explore if and how a pure working memory account can suffice. Second, we make explicit (more than in our earlier work) the potential building blocks of such a working memory account, thereby providing clear and concrete foci for empirical efforts to test the feasibility of the account

Turning the mind’s eye inward: the interplay between selective attention and working memory

Historically, cognitive sciences have considered selective attention and working memory as largely separated cognitive functions. That is, selective attention as a concept is typically reserved for the processes that allow for the prioritization of specific sensory input, while working memory entails more central structures for maintaining (and operating on) temporary mental representations. However, over the last decades various observations have been reported that question such sharp distinction. Most importantly, information stored in working memory has been shown to modulate selective attention processing – and vice versa. At the theoretical level, these observations are paralleled by an increasingly dominant focus on working memory as (involving) the attended part of long-term memory, with some positions considering that working memory is equivalent to selective attention turned to long-term memory representations – or internal selective attention. This questions the existence of working memory as a dedicated cognitive function and raises the need for integrative accounts of working memory and attention. The next step will be to explore the precise implications of attentional accounts of WM for the understanding of specific aspects and characteristics of WM, such as serial order processing, its modality-specificity, its capacity limitations, its relation with executive functions, as well as the nature of attentional mechanisms involved. This research topic in Frontiers in Human Neuroscience aims at bringing together the latest insights and findings about the interplay between working memory and selective attention

Can we predict community-wide effects of herbicides from toxicity tests on macrophyte species?

Macrophyte communities play an essential role in the way freshwater ecosystems function. It is thus of great concern to understand how environmental factors, especially anthropogenic ones, influence their composition and diversity. The aim of this study was to examine whether the effects of a herbicide mixture (50% atrazine, 35% isoproturon, 15% alachlor) on single macrophyte species can be used to predict its impact at a community level. In a first experiment we tested the sensitivity of six species (Azolla filiculoides, Ceratophyllum demersum, Elodea canadensis, Lemna minor, Myriophyllum spicatum and Vallisneria spiralis) grown separately and exposed to 0.6–600 gL−1 of the herbicide mixture. In a second experiment, conducted in microcosms, we tested the effects of herbicides on macrophyte assemblages composed of the same six species exposed to 0, 6 or 60 gL−1 of the herbicide mixture. Species grown separately exhibited growth inhibition at 60 and 600 gL−1. At 600 gL−1 the sensitivity differed significantly between species. V. spiralis was the most resistant species, C. demersum, M. spicatum and E. canadensis exhibited intermediate sensitivities, and A. filiculoides and L. minor were the most sensitive species. In microcosms, community biomass and Shannon evenness index were reduced after 8 weeks at 60 gL−1. Communities also exhibited changes in their composition: the relative and absolute abundance of C. demersum increased at 6 gL−1, while the relative abundance of V. spiralis increased at 60 gL−1. These results are in agreement with the individual responses of these species to the herbicides. It is therefore concluded that short-term effects of herbicides on simple macrophyte communities can be predicted from the sensitivity of individual species. However, further investigations are required to examine whether longer term effects can be predicted as well, especially in more complex communities

Toward a unified approach to testing for weak separability

In this paper we propose a unified framework for testing weak separability. We present a new three-step procedure, which is a joint test of necessary and sufficient conditions that takes account of possible measurement error and incomplete adjustment. We illustrate the operational capability of the procedure with an empirical example. Our procedure works well in medium sized samples, but at the present time may not be practical for datasets with extremely large sample sizes. As computing technology continues to advance, however, high-powered methods like the one we propose should supplant testing approaches that were originally designed to circumvent computational limitations.

Flux control of cytochrome c oxidase in human skeletal muscle

In the present work, by titrating cytochrome c oxidase (COX) with the specific inhibitor KCN, the flux control coefficient and the metabolic reserve capacity of COX have been determined in human saponin-permeabilized muscle fibers. In the presence of the substrates glutamate and malate, a 2.3 ± 0.2-fold excess capacity of COX was observed in ADP-stimulated human skeletal muscle fibers. This value was found to be dependent on the mitochondrial substrate supply. In the combined presence of glutamate, malate, and succinate, which supported an approximately 1.4-fold higher rate of respiration, only a 1.4 ± 0.2-fold excess capacity of COX was determined. In agreement with these findings, the flux control of COX increased, in the presence of the three substrates, from 0.27 ± 0.03 to 0.36 ± 0.08. These results indicate a tight in vivo control of respiration by COX in human skeletal muscle. This tight control may have significant implications for mitochondrial myopathies. In support of this conclusion, the analysis of skeletal muscle fibers from two patients with chronic progressive external ophthalmoplegia, which carried deletions in 11 and 49% of their mitochondrial DNA, revealed a substantially lowered reserve capacity and increased flux control coefficient of COX, indicating severe rate limitations of oxidative phosphorylation by this enzyme

Commentary: Coding of serial order in verbal, visual and spatial working memory

Published: 21 November 201

Monitoring of the performance of an air-to-water heat pump under real operating conditions

Bakalářská práce na téma „Měření provozu tepelného čerpadla vzduch-voda za reálných podmínek“ se zabývá vyhodnocením provozu tepelného čerpadla v rodiném domě s následným zjištěním závislosti topného faktoru a tepelného výkonu na teplotě vzduchu. První část je věnovaná teorii tepelných čerpadel, jejich rozdělení a vysvětlení základních pojmů. Dále jsou porovnány vykonové charakteristiky a topný faktor různých výrobců tepelných čerpadel. V druhé části je popsán způsob měření reálného tepelného čerpadla, které je použito v rodinném domě, použité měřící přístroje a měřící postupy. V třetí části jsou naměřené hodnoty vyneseny do grafů a je provedené vyhodnocení naměřených veličin a tepelné čerpadlo je zkontrolováno z hlediska vhodnosti použití.he Bachelor´s thesis on „Monitoring of the performance of an air-to-water heat pump under real operating conditions“ deals with the evaluation of a heat pump operation in a family house with a subsequent finding of the dependence of the heating factor and thermal performance on air temperature. The first part is dedicated to the theory of heat pumps, their categorization and explanation of the basic concepts. Next, we compare the performance characteristics and the coefficient of performance of heat pumps from different manufacturers. In the second part we describe measurements of a real heat pump which is used in a family house, the measuring instruments used, and particular measuring procedures. The third part shows the measured values plotted on charts, the measured values are analyzed, and the heat pump is checked for its suitability.