scholarly journals Annual pattern of calanoid copepod abundance, prosome length and minor role in pelagic carbon flux in the Solent, UK

1999 ◽  
Vol 177 ◽  
pp. 133-146 ◽  
Author(s):  
AG Hirst ◽  
M Sheader ◽  
JA Williams
Keyword(s):  
Carbon Flux ◽  
Calanoid Copepod ◽  
Minor Role ◽  
Prosome Length ◽  
Copepod Abundance

scholarly journals Direct observation of the setular web that fuses thoracopodal setae of a calanoid copepod into a collapsible fan

2019 ◽  
Author(s):  
George von Dassow ◽  
Richard B. Emlet
Keyword(s):  
Food Webs ◽  
Carbon Flux ◽  
High Speed ◽  
Calanoid Copepod ◽  
Swimming Performance ◽  
Structure And Function ◽  
High Speed Video ◽  
Aquatic Food ◽  
And Function ◽  
Oceanic Carbon

SummaryCopepods are numerically dominant planktonic grazers throughout the waters of Earth, preyed upon in turn by a wide diversity of pelagic animals (1,2). Their feeding and swimming performance thus has global importance to aquatic food webs and oceanic carbon flux. These crustaceans swim and feed using cuticle-covered, segmented, muscular appendages whose reach is extended greatly by setae, extracellular chitinous extensions with diverse structure and function (3). Plumose setae, with subsidiary setules arranged like barbs on a feather, have well-documented roles in generating feeding and swimming currents (4,5). Recent work showed that plumose setae of barnacle cyprid thoracopods are permanently linked by setules into a single fan that opens and closes as one sheet during high-speed swimming (6). Intersetular linkage across cyprid thoracopods may greatly decrease leakage between extended setae, ensure even spread of setae within the fan, and promote ordered collapse of the fan to avoid entanglement of adjacent appendages. Here we demonstrate similar setular webbing amongst thoracopod setae in the calanoid copepod Acartia sp. High-speed video directly documents the existence of such links, and reveals that individuals experience apparently-irreparable degradation of the setal array due to de-linkage, with likely consequences for swimming performance.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Produktivkraft als Versprechen

2016 ◽  
Vol 46 (185) ◽  
pp. 621-638 ◽  
Author(s):  
Christian Siefkes
Keyword(s):  
Private Consumption ◽  
Minor Role ◽  
Progressive Reduction ◽  
Internal Forces ◽  
A Minor

The ‘Fragment on Machines’ from Marx’s Grundrisse is often cited as an argument that the internal forces of capitalism will lead to its doom. But the argument that the progressive reduction of labor must doom capitalism lacks a proper foundation, as a comparison with the ‘Schemes of Reproduction’ given in Capital II shows. The latter, however, aren’t fully convincing either. In reality, more depends on the private consumption of capitalists than either model recognizes. Ultimately, most can be made of the ‘Fragment on Machines’ by reading it not as an exposure of capitalism’s internal contractions, but as a discussion of a possible communist future where labor (or work) will play but a minor role.

Effects of Different Types of Educational Tracking on Achievement and Achievement Variance

2013 ◽  
Vol 9 ◽  
Author(s):  
Erika Anne Leicht
Keyword(s):  
International Student ◽  
Educational Opportunity ◽  
Educational Achievement ◽  
Student Assessment ◽  
Minor Role ◽  
Highly Educated ◽  
International Student Assessment ◽  
Educational Backgrounds ◽  
Different Types ◽  
Educational Tracking

Despite their stated intention of providing equal educational opportunity for all, many democratic countries separate their students into different classes or even different schools based on their demonstrated academic ability and likely future career. This practice is often referred to as “tracking or “ability grouping.” This study aims to determine whether different types of educational tracking have different effects on students’ academic achievement. Specifically, this study investigates whether disparities in educational achievement between students of highly educated versus minimally educated parents are greater in countries that practice more explicit and complete forms of tracking. It also explores tracking’s effects on average achievement and overall achievement variance. Analysis of data from the 2009 Programme for International Student Assessment (PISA) indicates that tracking generally does increase score disparities between children from different educational backgrounds. Tracking is also associated with higher overall variance of scores. At the same time, tracking may have a slight positive effect on average achievement. However, results are not consistent across all countries, and patterns are different in different subject areas and for different types of tracking. The results of this study neither condemn nor extol tracking. Rather, they indicate that tracking plays a relatively minor role in determining the quality and equity of an education system.

Sign in / Sign up

Export Citation Format

Share Document