Decreasing water pressure cues ‘bailout’ in seaweed-associated crustaceans

2020 ◽  
Vol 653 ◽  
pp. 121-129
Author(s):  
RB Taylor ◽  
S Patke
Keyword(s):  
Water Pressure ◽  
Rapid Change ◽  
Brown Seaweed ◽  
Model System ◽  
Rate Of Change ◽  
Suitable Habitat ◽  
Changing Light ◽  
Surface Increase ◽  
Reduced Water ◽  
Transparent Chamber

Small mobile crustaceans are abundant on seaweeds. Many of these crustaceans rapidly abandon their host if it is detached from the seafloor and floats towards the surface, but the trigger for this ‘bailout’ behaviour is unknown. We tested 2 potential cues, i.e. rapid change in light and rapid change in water pressure, using >1 mm epifauna on the brown seaweed Carpophyllum plumosum as a model system. Bailout occurred in response to reduced water pressure, but not to changing light, as (1) bailout occurred at similar rates in light and dark, (2) bailout occurred on the seafloor when water pressure was reduced within a transparent chamber by the equivalent of ~0.5 m depth or more, and (3) little bailout occurred when water pressure was held constant within the chamber while seaweeds were raised to the surface. Increase in pressure (simulating sinking) did not induce bailout. The rate of bailout increased with increasing magnitude of pressure reduction but was not influenced greatly by the rate of change of pressure within the range tested (up to an equivalent of 0.4 m depth s-1). The use of pressure rather than light as a cue for bailout is consistent with the need for seaweed-associated crustaceans to rapidly abandon a detached host and relocate to suitable habitat during both day and night.

scholarly journals Ice-marginal lake hydrology and the seasonal dynamical evolution of Kennicott Glacier, Alaska

2020 ◽  
Vol 66 (259) ◽  
pp. 699-713 ◽  
Author(s):  
William H. Armstrong ◽  
Robert S. Anderson
Keyword(s):  
Water Pressure ◽  
Rapid Change ◽  
Dynamical Evolution ◽  
Rate Of Change ◽  
Channel System ◽  
Rapid Changes ◽  
Glacier Velocity ◽  
Lake Stage ◽  
Glacier Motion ◽  
Subglacial Drainage

AbstractGlacier basal motion is responsible for the majority of ice flux on fast-flowing glaciers, enables rapid changes in glacier motion and provides the means by which glaciers shape alpine landscapes. In an effort to enhance our understanding of basal motion, we investigate the evolution of glacier velocity and ice-marginal lake stage on Kennicott Glacier, Alaska, during the spring–summer transition, a time when subglacial drainage is undergoing rapid change. A complicated record of > 50 m fill-and-drain sequences on a hydraulically-connected ice-marginal lake likely reflects the punctuated establishment of efficient subglacial drainage as the melt season begins. The rate of change of lake stage generally correlates with diurnal velocity maxima, both in timing and magnitude. At the seasonal scale, the up-glacier progression of enhanced summer basal motion promotes uniformity of daily glacier velocity fluctuations throughout the 10 km study reach, and results in diurnal velocity patterns suggesting increasingly efficient meltwater delivery to and drainage from the subglacial channel system. Our findings suggest the potential of using an ice-marginal lake as a proxy for subglacial water pressure, and show how widespread basal motion affects bulk glacier behavior.

Punctuation

2003 ◽  
Author(s):  
Mary Jane West-Eberhard
Keyword(s):  
Large Population ◽  
Rapid Change ◽  
Biological Species ◽  
Rate Of Change ◽  
Quantum Evolution ◽  
Stabilizing Selection ◽  
Intended Meaning ◽  
Rate Of Evolution ◽  
Directional Change ◽  
Punctuated Evolution

In punctuated evolution (Eldredge and Gould, 1972) periods of relatively little change (“stasis”) are punctuated by episodes of relatively rapid change in the rate of evolution of a quantitative morphological trait, as seen in the fossil record of morphology. According to Simpson (1984), the term quantum evolution, refers to the same thing. Like Eldredge and Gould, Simpson contrasted quantum evolution with phyletic change, or sustained directional evolution without branching; considered that it could be associated with speciation (though also with phyletic evolution; p. 206); and even mentioned interrupted equilibra “In phyletic evolution equilibrium of the organism-environment system is continuous, or nearly so, although the point of equilibrium may and usually does shift. In quantum evolution equilibrium is lost, and a new equilibrium is reached”. I use the term “punctuation” rather than “quantum” because it less ambiguously describes change in rate of evolution. In its original meaning (from the Latin quantus), quantum means quantity. But quantum change, as mentioned by Simpson, is identified with the “quanta” of physics, which are discrete units of energy. This could encourage mistaken identification of punctuated change with the origin of discrete novelties, not the intended meaning of punctuated evolution, which is periodically altered rate of change in a continuously variable, quantitative trait. Mayr, Eldredge, Gould, and others (e.g., Stanley, 1979, 1981) explain stasis and punctuation in terms of speciation. Speciational punctuation hypotheses see stasis as due to the characteristics of established biological species, such as gene flow within interbreeding populations, large population size, heterogeneity of the species environment that retards directional change, developmental integration, canalization, coadapted genomes, stabilizing selection, and frequently reversing evolution over time within established species (Eldredge and Gould, 1997). These factors have been summarized by the term “gene-pool cohesiveness” (Mayr, 1989) or “developmental coherences” (Gould, 1989b), though the causes of stasis under the speciational hypothesis are admittedly vague and debatable (for reviews of other possible causes of stasis, see Williamson, 1987; Coyne and Charlesworth, 1997; Van Valen, 1982a; Spicer, 1993).

The varying influence of social and linguistic factors on language stability and change: The case of Eskilstuna

2009 ◽  
Vol 21 (1) ◽  
pp. 97-133 ◽  
Author(s):  
Eva Sundgren
Keyword(s):  
Large Scale ◽  
Language Change ◽  
Rapid Change ◽  
Rate Of Change ◽  
Social Forces ◽  
Trend Study ◽  
Continuity And Change ◽  
Gender And Age ◽  
Regional Dialect ◽  
Empirical Material

AbstractContinuity and Change in Present-Day Swedish: Eskilstuna Revisited is a large-scale study of language change in real time. In this article, the focus is on the results of a trend study and the analysis of how extralinguistic and linguistic factors influence how language varies and changes.The empirical material consists of informal conversationlike interviews, in which seven morphological and morphophonological variables have been analyzed in terms of the traditional extralinguistic factors of social group, gender, and age, as well as in terms of social networks. These morpho(phono)logical variables are sociolinguistically marked and have been hypothesized to show a process of more or less rapid change from regional dialect toward spoken standard. The rate of change at the level of the community has been slow, however. Comparisons between the influence of extralinguistic and linguistic factors indicate that social forces are more influential than linguistic ones.

Grazing intensity and vegetation change

1994 ◽  
Vol 18 ◽  
pp. 23-29
Author(s):  
J. A. Milne
Keyword(s):  
Vegetation Change ◽  
Management Practices ◽  
Production Systems ◽  
Rapid Change ◽  
Grazing Intensity ◽  
Abundant Species ◽  
Rate Of Change ◽  
Large Herbivores ◽  
Current State ◽  
The Uk

AbstractChange in the semi-natural vegetation of the hills and uplands of the UK is a relatively slow process. Whilst exogenous influences, such as climate and air quality, can influence the rate of change, the principal means whereby more rapid change can occur is through the actions of man in managing such resources to meet a range of objectives. Burning and grazing by large herbivores are the two most important management practices adopted and their interaction is central to the maintenance of vegetation in its current state and to its direction of change. This paper reviews how vegetation change associated with grazing occurs, how it can be measured, what the critical levels of grazing are for the most abundant species and what the implications of grazing are for nutrient supply for animal production systems.

Local Analytical Solution of One Dimension Consolidation Equation

2011 ◽  
Vol 243-249 ◽  
pp. 3113-3116
Author(s):  
Bo Feng ◽  
Run Tao Zhan ◽  
Feng Zhou
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Simple Relation ◽  
Solution Procedure ◽  
Rate Of Change ◽  
One Dimension ◽  
Fractional Differential

One dimension consolidation equation can be transformed into a fractional differential equation by Laplace transform. The transformed equation can leads to a simple relation between pore water pressure and its time revolution. When local rate of change of the pore water pressure is determined, the local pore water pressure can be obtained without having to solve the consolidation equation within the entire domain. The simplicity of the solution procedure is highlighted considering by a example..

scholarly journals Morphometry-Driven Divergence in Decadal Changes of Sediment Property in Floodplain Water Bodies

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 469
Author(s):  
Pongpet Pongsivapai ◽  
Junjiro N. Negishi ◽  
Hokuto Izumi ◽  
Paolo A. Garrido ◽  
Kanta Kuramochi
Keyword(s):  
Temporal Changes ◽  
Controlling Factors ◽  
Rate Of Change ◽  
Partial Least Square ◽  
Least Square ◽  
Water Bodies ◽  
Suitable Habitat ◽  
Internal Source ◽  
Sediment Properties ◽  
Source Management

Sediments are potentially the internal source that supply nutrients to water in lentic to semi-lentic ecosystems. The understanding of factors that cause temporal changes in sediment properties is critical for the internal source management. This study investigated the spatial variations and temporal changes in sediment properties in relation to their controlling factors in water bodies of the Ishikari River, Northern Japan. Sediment data in 29 water bodies were measured twice (around 2005 and 2019) to study the temporal changes in sediment properties, and were compared using Generalized Linear Mixed Models (GLMMs). The controlling factors of sediment properties including catchment and morphometry were examined by partial least square (PLS) regression. Our results showed that the temporal change in sediment properties over decades was largely driven by morphometry, while land use in the catchment played a relatively minor role in those changes. The rate of change in organic matter (OM) differed among water bodies depending on their morphometry. The small and shallow water bodies provided suitable habitat for macrophytes that led to OM deposits, resulting to an increase in OM and OM to total nitrogen (TN) ratio over time. The consequences of these changes are important for internal source management and biodiversity conservation.

Possible chemical controls of illite/smectite composition during diagenesis

1985 ◽  
Vol 49 (352) ◽  
pp. 387-391 ◽  
Author(s):  
B. Velde
Keyword(s):  
Oxidation State ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Mineral Assemblage ◽  
Rapid Change ◽  
Rate Of Change ◽  
Burial Diagenesis ◽  
Clay Mineral Assemblage ◽  
Layer Mineral

AbstractRe-interpretation of the significance of phase assemblages present in two sequences of rocks having experienced similar burial diagenesis allows one to establish that the change of oxidation state of iron in sediments could have the effect of changing the smectite content of the mixed layer mineral. This is used to explain an almost isothermal change in the composition of a sequence while others do not show such a rapid change. An indicator of the reaction is seen in the composition of the chlorite present in the rocks which is iron-rich and alumina-poor compared to chlorites in rocks showing a slower rate of change in the smectite content of the mixed-layered mineral. In order to reveal such a relation, one must make an analysis of the clay mineral assemblage, especially in the number of phases present during the course of diagenesis.

Exploring linguistic malleability across the life span: Age-specific patterns in quotative use

2015 ◽  
Vol 44 (4) ◽  
pp. 457-496 ◽  
Author(s):  
Isabelle Buchstaller
Keyword(s):  
Life Span ◽  
Language Ideologies ◽  
Rapid Change ◽  
Rate Of Change ◽  
Small Scale ◽  
Low Frequencies ◽  
Trend Data ◽  
Age Grading ◽  
The Moment ◽  
The Individual

AbstractThis article explores the degree and kind of lability that occurs throughout the life span of the individual during ongoing rapid change in the quotative system. Two comparative analyses trace speakers' use ofbe likeacross a shorter and a longer time span. Trend data reveal that the robust change is arrested in the middle age brackets; speakers in their thirties seem to display ‘retrograde movement’ (Sankoff & Wagner 2006) away from the community-wide change. This finding could be interpreted as incipient age-grading. A small-scale panel sample collected forty-two years after the initial interview suggests that some older speakers participate in the trend, albeit at very low frequencies. This finding, while exploratory at the moment, might be interpreted as indicative of ‘life-span change’ (Sankoff 2005). A conception of the change in progress in the quotative system as monotonous would thus both under and overestimate the rate of change. (Change across the life span, age-grading, retrograde change, life-span change, quotation, style, language ideologies)*

Modeling rate sensitivity of exercise transient responses to limb motion

2014 ◽  
Vol 117 (7) ◽  
pp. 699-705 ◽  
Author(s):  
Stanley M. Yamashiro ◽  
Takahide Kato
Keyword(s):  
Rapid Change ◽  
Rate Sensitivity ◽  
Rate Of Change ◽  
Fast Component ◽  
Transient Responses ◽  
Feed Forward ◽  
Exercise Load ◽  
Proposed Model ◽  
Sensitivity Rate ◽  
Response To Exercise

Transient responses of ventilation (V̇e) to limb motion can exhibit predictive characteristics. In response to a change in limb motion, a rapid change in V̇e is commonly observed with characteristics different than during a change in workload. This rapid change has been attributed to a feed-forward or adaptive response. Rate sensitivity was explored as a specific hypothesis to explain predictive V̇e responses to limb motion. A simple model assuming an additive feed-forward summation of V̇e proportional to the rate of change of limb motion was studied. This model was able to successfully account for the adaptive phase correction observed during human sinusoidal changes in limb motion. Adaptation of rate sensitivity might also explain the reduction of the fast component of V̇e responses previously reported following sudden exercise termination. Adaptation of the fast component of V̇e response could occur by reduction of rate sensitivity. Rate sensitivity of limb motion was predicted by the model to reduce the phase delay between limb motion and V̇e response without changing the steady-state response to exercise load. In this way, V̇e can respond more quickly to an exercise change without interfering with overall feedback control. The asymmetry between responses to an incremental and decremental ramp change in exercise can also be accounted for by the proposed model. Rate sensitivity leads to predicted behavior, which resembles responses observed in exercise tied to expiratory reserve volume.

Interaction Between Surge Behavior and Internal Flow Field in an Axial-Flow Compressor

2018 ◽  
Author(s):  
Yuu Sakata ◽  
Nobumichi Fujisawa ◽  
Yutaka Ohta
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Rapid Change ◽  
Internal Flow ◽  
Rotating Stall ◽  
Back Pressure ◽  
Rate Of Change ◽  
Operating Point ◽  
Tank Pressure

Interaction between surge behavior and internal flow field under coexisting phenomena of surge and rotating stall was experimentally investigated. In the experiment, the tank pressure of the compressor during surge was measured to detect the effect of the back-pressure fluctuation on the change in the internal flow field. Furthermore, the rotating stall in the compressor was investigated to define the influence of an unsteady internal flow field change on the surge behavior. From the tank pressure measurements, the amplitude of the tank pressure fluctuation was found to vary depending on the cycle. A larger maximal value for the tank pressure fluctuation led to a higher flow rate where the stall inception occurred. This difference in the flow rate indicated that the stall was induced by a severe adverse pressure gradient in the compressor. Then, the absolute rate of change in the flow coefficient was increased by both a large decrease in the compressor back pressure and performance degradation from stalling. In a case where the rate of decline in the flow rate was large, the scale of the stall cell developed up to a deep stall according to the movement of the operating point. Thus, a large trajectory for the surge cycle was selected, where the unsteady operating point went through the deep stall region. This development in the scale of the stall cell suggested to be influenced by the instability of the inner flow field caused by the rapid change in the flow rate.

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