Causal and Temporal Asymmetry

1991 ◽  
pp. 99-122
Author(s):  
Robin Le Poidevin
Keyword(s):  
Temporal Asymmetry

scholarly journals Effect of robotic-assisted gait training on objective biomechanical measures of gait in persons post-stroke: a systematic review and meta-analysis

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Heidi Nedergård ◽  
Ashokan Arumugam ◽  
Marlene Sandlund ◽  
Anna Bråndal ◽  
Charlotte K. Häger
Keyword(s):  
Kinetic Parameters ◽  
Step Length ◽  
Gait Training ◽  
Risk Of Bias ◽  
Current Evidence ◽  
Temporal Asymmetry ◽  
Robotic Assisted ◽  
Post Stroke ◽  
Gait Biomechanics ◽  
Affected Side

Abstract Background Robotic-Assisted Gait Training (RAGT) may enable high-intensive and task-specific gait training post-stroke. The effect of RAGT on gait movement patterns has however not been comprehensively reviewed. The purpose of this review was to summarize the evidence for potentially superior effects of RAGT on biomechanical measures of gait post-stroke when compared with non-robotic gait training alone. Methods Nine databases were searched using database-specific search terms from their inception until January 2021. We included randomized controlled trials investigating the effects of RAGT (e.g., using exoskeletons or end-effectors) on spatiotemporal, kinematic and kinetic parameters among adults suffering from any stage of stroke. Screening, data extraction and judgement of risk of bias (using the Cochrane Risk of bias 2 tool) were performed by 2–3 independent reviewers. The Grading of Recommendations Assessment Development and Evaluation (GRADE) criteria were used to evaluate the certainty of evidence for the biomechanical gait measures of interest. Results Thirteen studies including a total of 412 individuals (mean age: 52–69 years; 264 males) met eligibility criteria and were included. RAGT was employed either as monotherapy or in combination with other therapies in a subacute or chronic phase post-stroke. The included studies showed a high risk of bias (n = 6), some concerns (n = 6) or a low risk of bias (n = 1). Meta-analyses using a random-effects model for gait speed, cadence, step length (non-affected side) and spatial asymmetry revealed no significant differences between the RAGT and comparator groups, while stride length (mean difference [MD] 2.86 cm), step length (affected side; MD 2.67 cm) and temporal asymmetry calculated in ratio-values (MD 0.09) improved slightly more in the RAGT groups. There were serious weaknesses with almost all GRADE domains (risk of bias, consistency, directness, or precision of the findings) for the included outcome measures (spatiotemporal and kinematic gait parameters). Kinetic parameters were not reported at all. Conclusion There were few relevant studies and the review synthesis revealed a very low certainty in current evidence for employing RAGT to improve gait biomechanics post-stroke. Further high-quality, robust clinical trials on RAGT that complement clinical data with biomechanical data are thus warranted to disentangle the potential effects of such interventions on gait biomechanics post-stroke.

The effects of temporal asymmetry on the detection and perception of short chirps

2001 ◽  
Vol 158 (1-2) ◽  
pp. 71-83 ◽  
Author(s):  
Stefan Uppenkamp ◽  
Sandra Fobel ◽  
Roy D Patterson
Keyword(s):  
Temporal Asymmetry

Temporal asymmetry as a gait quality indicator

1980 ◽  
Vol 18 (5) ◽  
pp. 689-693 ◽  
Author(s):  
M. E. Dewar ◽  
G. Judge
Keyword(s):  
Quality Indicator ◽  
Temporal Asymmetry ◽  
Gait Quality

Dendritic competition in the developing retina: Ganglion cell density gradients and laterally displaced dendrites

1993 ◽  
Vol 10 (2) ◽  
pp. 313-324 ◽  
Author(s):  
Rafael Linden
Keyword(s):  
Density Gradient ◽  
Cell Density ◽  
Time Course ◽  
Ganglion Cells ◽  
Lateral Displacement ◽  
Optic Tract ◽  
Density Gradients ◽  
Temporal Asymmetry ◽  
Dendritic Arbors ◽  
Contralateral Eye

AbstractDendrites of retinal ganglion cells (RGCs) tend to be distributed preferentially toward areas of reduced RGC density. This, however, does not occur in the retina of normal pigmented rats, in which it has been suggested that the centro-peripheral gradient of RGC density is too shallow to provide directional guidance to growing dendrites. In this study, laterally displaced dendrites of RGCs retrogradely labeled with horseradish peroxidase were related to cell density gradients induced experimentally in the rat retina. Neonatal unilateral lesions of the optic tract produced retrograde degeneration of contralaterally projecting RGCs, but spared ipsilaterally projecting neurons in the same retina. These lesions created an anomalous temporal to nasal gradient of cell density across the decussation line, opposite to the nasal to temporal gradient found along the same axis in either normal rats or rats that had the contralateral eye removed at birth. RGCs in rats that received optic tract lesions had their dendrites displaced laterally toward the depleted nasal retina, while in either normal or enucleated rats there was no naso-temporal asymmetry. The lateral displacement affected both primary dendrites and higher-order branches. However, the gradient of cell density after optic tract lesions was less steep than the gradient in either normal or enucleated rats. To test for the presence of steeper gradients at early stages of development, RGC density gradients were also examined at postnatal day 5 (P5). In normal rats, the RGCs were homogeneously distributed throughout the retina, while rats given optic tract lesions at birth already showed a temporo-nasal density gradient at P5. Still, this anomalous gradient was less steep than that found in normal adults. It is concluded that the time course, rather than the steepness of the RGC density gradient, is the major determinant of the lateral displacement of dendritic arbors with respect to the soma in developing RGCs. The data are consistent with the idea that the overall shape of dendritic arbors depends in part on dendritic competition during retinal development.

scholarly journals Asynchronous Coreceptor Downregulation after Positive Thymic Selection: Prolonged Maintenance of the Double Positive State in CD8 Lineage Differentiation Due to Sustained Biosynthesis of the CD4 Coreceptor

1997 ◽  
Vol 185 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Thomas Barthlott ◽  
Hubertus Kohler ◽  
Klaus Eichmann
Keyword(s):  
T Cell ◽  
Degradation Kinetics ◽  
Cell Lineage ◽  
Turnover Rates ◽  
Double Positive ◽  
Color Flow ◽  
Temporal Asymmetry ◽  
Translational Activity ◽  
Lineage Differentiation

In several experimental systems analyzing the generation of single positive (SP) thymocytes from double positive (DP) thymocytes, CD4 SP cells have been shown to appear before CD8 SP cells. This apparent temporal asymmetry in the maturation of CD4 SP and CD8 SP thymocytes could either be due to divergent molecular differentiation programs of the two T cell lineages, or merely to slower degradation kinetics of the CD4 protein. To study this question in unmanipulated in vivo differentiation, we developed a four-color flow cytometry protocol which identifies a recently activated TCRintCD69pos thymocyte population containing DP cells and early CD4 SP cells but no CD8 SP cells. We show that these TCRintCD69pos thymocytes represent a transitory stage in the mainstream αβ T cell lineage. The precursors of the CD8 SP cells are contained in this population as incompletely selected DP cells. Moreover, we show that expression of both coreceptors in the TCRintCD69pos population depends on transcriptional and translational activity, thus excluding differences in turnover rates of the CD4 and CD8 proteins as the cause of the asynchrony in differentiation of the CD4 and CD8 lineages.

scholarly journals Time, perspective and semantic representation

2017 ◽  
Vol 10 (1) ◽  
pp. 26-55 ◽  
Author(s):  
K. M. JASZCZOLT
Keyword(s):  
Time Perspective ◽  
Semantic Representation ◽  
Building Blocks ◽  
The Self ◽  
Epistemic Modality ◽  
Conceptual Approach ◽  
Temporal Asymmetry ◽  
Temporal Reference ◽  
Semantic Building Blocks ◽  
Cognitive Plausibility

abstractI discuss the perspectival nature of temporality in discourse and argue that the human concept of time can no more be dissociated from the perspectival thought than the concept of the self can. The corollary of this observation is that perspectival temporality can no more be excluded from the semantic representation than the notion of the self can: neither can be reduced to the bare referent for the purpose of semantic representation if the latter is to retain cognitive plausibility. I present such a semantic qua conceptual approach to temporal reference developed within my theory of Default Semantics. I build upon my theory of time as epistemic modality according to which, on the level of conceptual qua semantic building blocks, temporality reduces to degrees of detachment from the certainty of the here and the now. I also address the questions of temporal asymmetry between the past and the future, and the relation between metaphysical time (timeM), psychological time (timeE, where ‘E’ marks the domain of epistemological enquiry), and time in natural language (timeL), concluding that the perspective-infused timeE and timeL are compatible with timeM of mathematical models of spacetime: all are definable through possibility and perspectivity.

Temporal Asymmetry (continued)

1982 ◽  
pp. 98-109
Author(s):  
T. Chapman
Keyword(s):  
Temporal Asymmetry

Effects of load addition during gait training on weight-bearing and temporal asymmetry after stroke

2019 ◽  
pp. 1
Author(s):  
Tatiana S. Ribeiro ◽  
Emília Márcia G.S. Silva ◽  
Isabelly Cristina R. Regalado ◽  
Stephano T. Silva ◽  
Catarina de Oliveira Sousa ◽  
...  
Keyword(s):  
Weight Bearing ◽  
Gait Training ◽  
Temporal Asymmetry
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