scholarly journals The effect of discrete recharge by moulins and heterogeneity in flow-path efficiency at glacier beds on subglacial hydrology

2012 ◽  
Vol 58 (211) ◽  
pp. 926-940 ◽  
Author(s):  
J.D. Gulley ◽  
M. Grabiec ◽  
J.B. Martin ◽  
J. Jania ◽  
G. Catania ◽  
...  
Keyword(s):  
Distributed Systems ◽  
Causal Relationship ◽  
Potential Theory ◽  
Hydraulic Head ◽  
Flow Path ◽  
Effective Pressure ◽  
Dendritic Networks ◽  
Direct Causal Relationship ◽  
Theoretical Predictions ◽  
Path Efficiency

AbstractSubglacial conduit systems are thought to consist of dendritic networks that exist at lower pressure than distributed systems and have locations that are determined by theoretical hydraulic potential. On glaciers with moulins, however, meltwater is delivered to glacier beds at discrete points, violating assumptions of uniform recharge needed to calculate potential. To understand how moulins affect subglacial conduit hydrology, we used speleological techniques to map 0.4 km of subglacial conduit at the base of a moulin in Hansbreen, Svalbard, and compared our observations with theoretical predictions. The conduit began in an area predicted to lack drainage, crossed equipotential contours at oblique rather than right angles and was locally anastomotic rather than dendritic. We propose moulin locations, which are determined by the locations of supraglacial streams and crevasses, control locations of subglacial recharge. Because conduits have no direct causal relationship with gradients in effective pressure, this recharge can form conduits in areas of glacier beds that may not be predicted by hydraulic potential theory to have conduits. Recharge by moulins allows hydraulic head to increase in conduits faster and to higher values than in adjacent distributed systems, resulting in an increase rather than a decrease in glacier sliding speeds above subglacial conduits.

The Effect of reversing the Internal Water-Current on the Spicule Orientation in Leucosolenia variabilis and L. complicata

1958 ◽  
Vol s3-99 (46) ◽  
pp. 263-278
Author(s):  
W. CLIFFORD JONES
Keyword(s):  
Causal Relationship ◽  
Structural Features ◽  
Water Current ◽  
Internal Water ◽  
Direct Causal Relationship ◽  
Aquarium Tank

1. Specimens grown in quiet water in an aquarium tank produce the same pattern of spicules as do those occurring naturally. Woodland's hypothesis, that the orientation arises from turbulence in the environment, is thereby disproved. 2. Reversing the internal water-current in excised oscular tubes of Leucosolenia has shown that no direct causal relationship exists between the direction of the current and the orientation of the spicules. 3. The spicule arrangement is modifiable by experiment; the orientation is not dependent on the existence of static structural features in the wall of the sponge. 4. Removal of the oscular rim has little effect on the orientation of the spicules subsequently developing in the tube behind. 5. Diverticula develop from bulges, formed largely by a reshaping process. The arrangement of the associated small spicules is essentially the same as for L. lieberkühnii. 6. A mechanical hypothesis explaining the orientation of the spicules is briefly described. The formative cell sextet is believed to be oriented by a movement of the mesogloea over the epithelium to which the sextet is contiguous.

Recalibrating the Gaze

2017 ◽  
Vol 9 (4) ◽  
pp. 225-235
Author(s):  
Michael McAllum
Keyword(s):  
Causal Relationship ◽  
Present Situation ◽  
Collective Learning ◽  
Knowledge Systems ◽  
First Century ◽  
Symbolic Language ◽  
Contemporary Society ◽  
The Gaze ◽  
Direct Causal Relationship ◽  
Existential Issues

If symbolic language, collective learning, and the means by which we use technology are humanity’s “fundamental, non-genetic, adaptive capacity,” then how these are extended and modified in the next few decades will fundamentally define what it means to be human in the twenty-first century. The scale and scope of that determination is, in turn, dependent on how cognitive framings or “gazes,” shaped by shared conceptions of time, are constructed, for these gazes bound conversation, available knowledge, and the contextualizing of decisions. This article argues that the dominant linear orientation with its present-future emphasis has a direct causal relationship with the existential issues contemporary society faces. It postulates their resolution requires going beyond existing constraints in language and learning together with the need to fundamentally rethink many explicit and tacit understandings, including those that inform futures thinking. If this were to occur, then the scope of symbolic language is broadened, thus, allowing a wider range of options to become available. However, it must be recognized at the same time that these same elements must morph to reflect both the inclusion, yet incompleteness, of all knowledge systems into a new ecology of understanding. Such propositions lead to a question: does contemporary society have sufficient awareness of its present situation to put aside (even for a while) what has made it successful thus far, to even consider possibilities that exist beyond the conventions it now accepts as axiomatic?

scholarly journals Modelling distributed and channelized subglacial drainage: the spacing of channels

2011 ◽  
Vol 57 (202) ◽  
pp. 302-314 ◽  
Author(s):  
Ian J. Hewitt
Keyword(s):  
Distributed Systems ◽  
Distributed System ◽  
Water Pressure ◽  
Ice Sheet ◽  
Length Scale ◽  
Effective Pressure ◽  
Open Drainage ◽  
Critical Discharge ◽  
Subglacial Drainage

AbstractModels are proposed for channelized and distributed flow of meltwater at the base of an ice sheet. The volumes of both channel and distributed systems evolve according to a competition between processes that open drainage space (e.g. sliding over bedrock, melting of the ice) and processes that close it (e.g. viscous creep of the ice due to a positive effective pressure). Channels are generally predicted to have lower water pressure and therefore capture water from the surrounding regions of distributed flow. There is a natural length scale associated with the distributed system that determines the width of the bed from which water can be drawn into a channel. It is suggested that this determines the spacing between major channels and that this may be reflected in the spacing of eskers. A more permeable distributed system results in more widely spaced, and therefore larger, channels. Calculations of the flow into the head of a channel reveal that there is a critical discharge necessary for it to form, and provide a criterion for where channels can exist.

scholarly journals Snail Mediates E-Cadherin Repression by the Recruitment of the Sin3A/Histone Deacetylase 1 (HDAC1)/HDAC2 Complex

2004 ◽  
Vol 24 (1) ◽  
pp. 306-319 ◽  
Author(s):  
Hector Peinado ◽  
Esteban Ballestar ◽  
Manel Esteller ◽  
Amparo Cano
Keyword(s):  
Transcription Factor ◽  
Causal Relationship ◽  
Histone Deacetylase ◽  
Trichostatin A ◽  
Hdac Activity ◽  
Histone Deacetylase 1 ◽  
Acetylation Status ◽  
Direct Causal Relationship ◽  
E Cadherin

ABSTRACT The transcription factor Snail has been described as a direct repressor of E-cadherin expression during development and carcinogenesis; however, the specific mechanisms involved in this process remain largely unknown. Here we show that mammalian Snail requires histone deacetylase (HDAC) activity to repress E-cadherin promoter and that treatment with trichostatin A (TSA) is sufficient to block the repressor effect of Snail. Moreover, overexpression of Snail is correlated with deacetylation of histones H3 and H4 at the E-cadherin promoter, and TSA treatment in Snail-expressing cells reverses the acetylation status of histones. Additionally, we demonstrate that Snail interacts in vivo with the E-cadherin promoter and recruits HDAC activity. Most importantly, we demonstrate an interaction between Snail, histone deacetylase 1 (HDAC1) and HDAC2, and the corepressor mSin3A. This interaction is dependent on the SNAG domain of Snail, indicating that the Snail transcription factor mediates the repression by recruitment of chromatin-modifying activities, forming a multimolecular complex to repress E-cadherin expression. Our results establish a direct causal relationship between Snail-dependent repression of E-cadherin and the modification of chromatin at its promoter.

scholarly journals Efficiency calculation on 10 MW experimental steam turbine

2018 ◽  
Vol 168 ◽  
pp. 06001
Author(s):  
Michal Hoznedl
Keyword(s):  
Steam Turbine ◽  
Flow Measurement ◽  
Flow Parameter ◽  
Flow Path ◽  
Measuring System ◽  
Parameter Distribution ◽  
Efficiency Evaluation ◽  
Path Efficiency ◽  
Efficiency Determination ◽  
Turbine Flow Path

The paper deals with defining flow path efficiency of an experimental steam turbine by using measurement of flow, torque, pressures and temperatures. The configuration of the steam turbine flow path is briefly described. Measuring points and devices are defined. The paper indicates the advantages as well as disadvantages of flow path efficiency measurement using enthalpy and torque on the shaft. The efficiency evaluation by the help pressure and temperature measurement is influenced by flow parameter distribution and can provide different values of flow path efficiency. The efficiency determination by using of torque and mass flow measurement is more accurate and it is recommended for using. The disadvantage is relatively very complicated and expensive measuring system.

Conditional Changes: Europeanization in the Western Balkans and the Example of Media Freedom

Intersections ◽  
2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Beáta Huszka ◽  
Zsolt Körtvélyesi
Keyword(s):  
Causal Relationship ◽  
Western Balkans ◽  
Media Freedom ◽  
The Past ◽  
Broad View ◽  
Liberal Democratic ◽  
Direct Causal Relationship

This paper takes a broad view on the context of EU conditionality and, after presenting various challenges, narrows down its focus to provide evidence for the shortcomings concerning media freedom in the Western Balkans. That enlargement is not the linear, one-way process it was once believed to be – where countries gravitating towards an evident liberal democratic consensus through the pull of integration – is evident from cases reaching beyond the Western Balkans. While we will not try to establish any direct causal relationship between the shortcomings of EU conditionality and the democratic backlash in the Western Balkans in the past ten years, we do seek to demonstrate how conditionality is failing in a particular context, by providing an overview of what the essential conditions of successful norm promotion, credibility and, most importantly, consistency are, and illustrate how these are lacking in the case of media freedom conditionality.

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