The Role of Myocardial Fiber Direction in Epicardial Activation Patterns via Uncertainty Quantification

ABSTRACTThe “safety case” approach has been developed to address the issue of evaluating the performance of a geologic repository in the face of the large uncertainty that results for evaluations that extend over hundreds of thousands of years. This paper reviews the concept of the safety case as it has been defined by the international community. We contrast the safety case approach with that presently used in the U.S. repository program. Especially, we focus on the role of uncertainty quantification. There are inconsistencies between the initial proposal to dealing with uncertainties in a safety case and current U.S. practice. The paper seeks to better define the safety case concept so that it can be usefully applied to the regulatory framework of the U.S. repository program.

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Memory: Looking back and looking forward

Brain and Neuroscience Advances ◽

10.1177/2398212818794830 ◽

2018 ◽

Vol 2 ◽

pp. 239821281879483 ◽

Cited By ~ 5

Author(s):

John P. Aggleton ◽

Richard G. M. Morris

Keyword(s):

Neural Plasticity ◽

Imaging Studies ◽

Activation Patterns ◽

Memory Research ◽

Neuronal Ensembles ◽

Disadvantaged Populations ◽

Episodic Memories ◽

Source Of Information ◽

Looking Back

This review brings together past and present achievements in memory research, ranging from molecular to psychological discoveries. Despite some false starts, major advances include our growing understanding of learning-related neural plasticity and the characterisation of different classes of memory. One striking example is the ability to reactivate targeted neuronal ensembles so that an animal will seemingly re-experience a particular memory, with the further potential to modify such memories. Meanwhile, human functional imaging studies can distinguish individual episodic memories based on voxel activation patterns. While the hippocampus continues to provide a rich source of information, future progress requires broadening our research to involve other sites. Related challenges include the need to understand better the role of glial–neuron interactions and to look beyond the synapse as the sole site of experience-dependent plasticity. Unmet goals include translating our neuroscientific knowledge in order to optimise learning and memory, especially among disadvantaged populations.

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Revisiting the Role of the Fusiform Face Area in Expertise

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00974 ◽

2016 ◽

Vol 28 (9) ◽

pp. 1345-1357 ◽

Cited By ~ 11

Author(s):

Merim Bilalić

Keyword(s):

Pattern Analysis ◽

Spatial Relations ◽

Fusiform Face Area ◽

Multivariate Pattern Analysis ◽

Multiple Objects ◽

Activation Patterns ◽

Face Area ◽

Single Category ◽

Multivariate Pattern

The fusiform face area (FFA) is considered to be a highly specialized brain module because of its central importance for face perception. However, many researchers claim that the FFA is a general visual expertise module that distinguishes between individual examples within a single category. Here, I circumvent the shortcomings of some previous studies on the FFA controversy by using chess stimuli, which do not visually resemble faces, together with more sensitive methods of analysis such as multivariate pattern analysis. I also extend the previous research by presenting chess positions, complex scenes with multiple objects, and their interrelations to chess experts and novices as well as isolated chess objects. The first experiment demonstrates that chess expertise modulated the FFA activation when chess positions were presented. In contrast, single chess objects did not produce different activation patterns among experts and novices even when the multivariate pattern analysis was used. The second experiment focused on the single chess objects and featured an explicit task of identifying the chess objects but failed to demonstrate expertise effects in the FFA. The experiments provide support for the general expertise view of the FFA function but also extend the scope of our understanding about the function of the FFA. The FFA does not merely distinguish between different exemplars within the same category of stimuli. More likely, it parses complex multiobject stimuli that contain numerous functional and spatial relations.

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The The abdominal muscles – a functional review

South African Journal of Physiotherapy ◽

10.4102/sajp.v63i1.123 ◽

2007 ◽

Vol 63 (1) ◽

Author(s):

T. Puckree

Keyword(s):

Animal Studies ◽

Functional Organization ◽

Scientific Evidence ◽

Motor Units ◽

Abdominal Muscles ◽

Activation Patterns ◽

Wide Range ◽

Speech Control ◽

Human Function

The role of the abdominal muscles in human function as wellas their physiological mechanisms for these has been the subject of an increasing volume of reported research for more than 20 years. The abdominal muscles participate in a wide range of diverse functional tasks.These include breathing, postural stability, expulsive maneuvers and speech control. To perform these functions effectively and often concurrently, based on demand, the muscles are anatomically, physiologically and biochemical suited. The idea that the abdominal muscles function as a unit has been dispelled by many scientific reports. It is now known that they function differentially as individual muscles and also differentially at the motor unit level. Regional differences in the activation patterns of these muscles are also known. In addition the motor units within muscles are functionally organized to either subserve a specific function or more than one function. Knowledge of the functional organization of the abdominal muscles is critical to any rehabilitation process especially since rehabilitation is holistic and strives to achieve functional goals. This functional review is based on current scientific evidence for the multi functionality of all abdominal muscles. Literature based on animal studies has been excluded as far as is possible.

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The Role of the Non-Collagenous Extracellular Matrix in Tendon and Ligament Mechanical Behavior: A Review

Journal of Biomechanical Engineering ◽

10.1115/1.4053086 ◽

2021 ◽

Author(s):

Lainie E. Eisner ◽

Ryan Rosario ◽

Nelly Andarawis-Puri ◽

Ellen M. Arruda

Keyword(s):

Extracellular Matrix ◽

Mechanical Behavior ◽

Computational Models ◽

Matrix Protein ◽

Fiber Direction ◽

Future Studies ◽

Tissue Repair And Regeneration ◽

Resistance To Deformation ◽

Theoretical Mechanics

Abstract Tendon is a connective tissue that transmits loads from muscle to bone, while ligament is a similar tissue that stabilizes joint articulation by connecting bone to bone. 70-90% of tendon and ligament's extracellular matrix (ECM) is composed of a hierarchical collagen structure that provides resistance to deformation primarily in the fiber direction, and the remaining fraction consists of a variety of non-collagenous proteins, proteoglycans, and glycosaminoglycans (GAGs) whose mechanical roles are not well characterized. ECM elements such as elastin, the proteoglycans decorin, biglycan, lumican, fibromodulin, lubricin, and aggrecan and their associated GAGs, and Cartilage Oligomeric Matrix Protein (COMP) have been suggested to contribute to tendon and ligament's characteristic quasi-static and viscoelastic mechanical behavior in tension, shear, and compression. The purpose of this review is to summarize existing literature regarding the contribution of the non-collagenous ECM to tendon and ligament mechanics, and to highlight key gaps in knowledge that future studies may address. Using insights from theoretical mechanics and biology, we discuss the role of the non-collagenous ECM in quasi-static and viscoelastic tensile, compressive, and shear behavior in the fiber direction and orthogonal to the fiber direction. We also address the efficacy of tools that are commonly used to assess these relationships, including enzymatic degradation, mouse knockout models, and computational models. Further work in this field will foster a better understanding of tendon and ligament damage and healing as well as inform strategies for tissue repair and regeneration.

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Differential Activation Patterns of fMRI in Sleep-Deprived Brain: Restoring Effects of Acupuncture

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2014/465760 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 10

Author(s):

Lei Gao ◽

Ming Zhang ◽

Honghan Gong ◽

Lijun Bai ◽

Xi-jian Dai ◽

...

Keyword(s):

Sleep Deprivation ◽

Sham Group ◽

Anterior Cingulate ◽

Activation Patterns ◽

Unique Role ◽

Postcentral Gyrus ◽

Normal Sleep ◽

The Right ◽

Bilateral Thalamus

Previous studies suggested a remediation role of acupuncture in insomnia, and acupuncture also has been used in insomnia empirically and clinically. In this study, we employed fMRI to test the role of acupuncture in sleep deprivation (SD). Sixteen healthy volunteers (8 males) were recruited and scheduled for three fMRI scanning procedures, one following the individual’s normal sleep and received acupuncture SP6 (NOR group) and the other two after 24 h of total SD with acupuncture on SP6 (SD group) or sham (Sham group). The sessions were counterbalanced approximately two weeks apart. Acupuncture stimuli elicited significantly different activation patterns of three groups. In NOR group, the right superior temporal lobe, left inferior parietal lobule, and left postcentral gyrus were activated; in SD group, the anterior cingulate cortex, bilateral insula, left basal ganglia, and thalamus were significantly activated while, in Sham group, the bilateral thalamus and left cerebellum were activated. Different activation patterns suggest a unique role of acupuncture on SP6 in remediation of SD. SP6 elicits greater and anatomically different activations than those of sham stimuli; that is, the salience network, a unique interoceptive autonomic circuit, may indicate the mechanism underlying acupuncture in restoring sleep deprivation.

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The role of uncertainty quantification and propagation in accelerating the discovery of electrochemical functional materials

MRS Bulletin ◽

10.1557/mrs.2019.45 ◽

2019 ◽

Vol 44 (3) ◽

pp. 204-212

Author(s):

Gregory Houchins ◽

Dilip Krishnamurthy ◽

Venkatasubramanian Viswanathan

Keyword(s):

Uncertainty Quantification ◽

Functional Materials ◽

Image Position

Abstract

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Verapamil reduces incidence of reentry during ventricular fibrillation in pigs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00256.2014 ◽

2014 ◽

Vol 307 (9) ◽

pp. H1361-H1369 ◽

Cited By ~ 4

Author(s):

Qi Jin ◽

Derek J. Dosdall ◽

Li Li ◽

Jack M. Rogers ◽

Raymond E. Ideker ◽

...

Keyword(s):

Ventricular Fibrillation ◽

Conduction Velocity ◽

Cycle Length ◽

Conduction Block ◽

Antiarrhythmic Effect ◽

Delayed Rectifier ◽

Activation Patterns ◽

Long Duration ◽

Activation Rate

The characteristics of reentrant circuits during short duration ventricular fibrillation (SDVF; 20 s in duration) and the role of Ca++ and rapid-activating delayed rectifier potassium currents during long duration ventricular fibrillation (LDVF; up to 10 min in duration) were investigated using verapamil and sotalol. Activation mapping of the LV epicardium with a 21 × 24 electrode plaque was performed in 12 open-chest pigs. Pigs were given either verapamil (0.136 mg/kg) or sotalol (1.5 mg/kg) and verapamil. Reentry patterns were quantified for SDVF, and, for LDVF, activation patterns were compared with our previously reported control LDVF data. Verapamil significantly increased conduction velocity around the reentrant core by 10% and reduced the reentrant cycle length by 15%, with a net reduction in reentry incidence of 70%. Sotolol had an opposite effect of decreasing the conduction velocity around the core by 6% but increasing the reentrant cycle length by 13%, with a net reduction of reentry incidence of 50%. After 200 s of VF, verapamil significantly slowed wavefront conduction velocity and activation rate compared with control data. Verapamil decreased the incidence of reentry in SDVF by accelerating conduction velocity to increase the likelihood of conduction block, possibly through increased sympathetic tone. The drug slowed activation rate and conduction velocity after 200 s of VF, suggesting that L-type Ca++ channels remain active and may be important in the maintenance of LDVF. Sotalol in addition to verapamil caused no additional antiarrhythmic effect.

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EFFECTS OF ACUTE GLOBAL ISCHEMIA ON RE-ENTRANT ARRHYTHMOGENESIS: A SIMULATION STUDY

Journal of Biological System ◽

10.1142/s0218339015500114 ◽

2015 ◽

Vol 23 (02) ◽

pp. 213-230 ◽

Cited By ~ 3

Author(s):

WEIGANG LU ◽

JIE LI ◽

FEI YANG ◽

CUNJIN LUO ◽

KUANQUAN WANG ◽

...

Keyword(s):

Global Ischemia ◽

Therapeutic Interventions ◽

Fiber Direction ◽

Activation Patterns ◽

Cardiac Electrical Activity ◽

Ventricular Cells ◽

Ventricular Tissue ◽

Cellular Excitability ◽

The Stability ◽

Kinetics Of

Sudden cardiac death is mainly caused by arrhythmogenesis. For a functional abnormal heart, such as an ischemic heart, the probability of arrhythmia occurring is greatly increased. During myocardial ischemia, re-entry is prone to degenerate into ventricular fibrillation (VF). Therefore it has important meaning to investigate the intricate mechanisms underlying VF under an ischemic condition in order to better facilitate therapeutic interventions. In this paper, to analyze the functional influence of acute global ischemia on cardiac electrical activity and subsequently on re-entrant arrhythmogenesis, we take into account three main pathophysiological consequences of ischemia: hyperkalaemia, acidosis, and anoxia, and develop a 3D human ventricular ischemic model that combines a detailed biophysical description of the excitation kinetics of human ventricular cells with an integrated geometry of human ventricular tissue which incorporates fiber direction anisotropy and the stimulation activation sequence. The results show that under acute global ischemia, the tissue excitability and the slope of ventricular cellular action potential duration restitution (APDR) are greatly decreased. As a result, the complexity of VF activation patterns is reduced. For the three components of ischemia, hyperkalaemia is the dominant contributor to the stability of re-entry under acute global ischemia. Increasing [K+]o acts to prolong the cell refractory period, reduce the tissue excitability and slow the conduction velocity. Our results also show that VF can be eliminated by decreasing cellular excitability, primarily by elevating the concentration value of extracellular K+.

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