scholarly journals Does sleep-dependent consolidation favour weak memories?

2020 ◽  
Author(s):  
Marit Petzka ◽  
Ian Charest ◽  
George M. Balanos ◽  
Bernhard Staresina
Keyword(s):  
Memory Consolidation ◽  
Retroactive Interference ◽  
Delay Period ◽  
Interference Task ◽  
Testing Conditions ◽  
Standard Testing ◽  
Different Types ◽  
Ceiling Effects ◽  
Consolidation Effect

Sleep stabilizes newly acquired memories, a process referred to as memory consolidation. According to recent studies, sleep-dependent consolidation processes might be deployed to different extents for different types of memories. In particular, weaker memories might benefit greater from post-learning sleep than stronger memories. However, under standard testing conditions, sleep-dependent consolidation effects for stronger memories might be obscured by ceiling effects. To test this possibility, we devised a new memory paradigm (Memory Arena) in which participants learned temporospatial arrangements of objects. Prior to a delay period spent either awake or asleep, training thresholds were controlled to yield relatively weak or relatively strong memories. After the delay period, retrieval difficulty was controlled via the presence or absence of a retroactive interference task. Under standard testing conditions (no interference), a sleep-dependent consolidation effect was indeed observed for weaker memories only. Critically though, with increased retrieval demands, sleep-dependent consolidation effects were seen for both weaker and stronger memories. These results suggest that all memories are consolidated during sleep, but that memories of different strengths warrant different testing conditions to unveil their benefit from post-learning sleep.

scholarly journals Evaluation of Wear Behaviour in Metallic Binders Employed in Diamond Tools for Cutting Stone

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3988
Author(s):  
Fátima Ternero ◽  
Pedro M. Amaral ◽  
Jorge Cruz Fernandes ◽  
Luís Guerra Rosa
Keyword(s):  
Wear Behavior ◽  
Wear Behaviour ◽  
Empirical Expression ◽  
Testing Conditions ◽  
Diamond Tools ◽  
Test Methodology ◽  
Different Types ◽  
Stone Material ◽  
The Difference ◽  
Wear Tests

A type of disc-on-plate test methodology was used to determine the wear behavior of metallic binders employed in the manufacturing of diamond impregnated tools. The disc consists of a special circular wheel that allows the binder materials alone (i.e., without diamond, but sintered under conditions identical to those of the complete tool) to be tested against a plate of stone material under pre-determined testing conditions. The testing conditions are intended to be equivalent to those used in the industrial processes. Using plates of five types of granite and one type of marble, this work comprises wear tests of 15 different types of metallic binders and two sintering modes conducted under, at least, three different values of contact-force. The analysis of the results demonstrated that the wear of the binders can be related to their mechanical properties through an empirical expression. The larger the difference between the characteristics of the tribological pair (binder versus stone), the higher is the correlation between the experimental wear data and the values given by the empirical expression. The relationships presented in this work allow predicting the wear behavior of the binder, and therefore may help in the design process of diamond tools. There was a clear difference between the wear behavior of metallic binders when they were employed against the two main classes of stone under analysis (marble and granite).

Abrasive Wear Research on Rubber

1961 ◽  
Vol 34 (2) ◽  
pp. 482-492 ◽  
Author(s):  
K. Wellinger ◽  
H. Uetz
Keyword(s):  
Abrasive Wear ◽  
Abrasion Resistance ◽  
Testing Methods ◽  
Sand Blasting ◽  
Testing Conditions ◽  
Different Types ◽  
Paper Method ◽  
Abrasive Paper ◽  
Blasting Method

Abstract The abrasion resistance of five different types of rubber were compared with steel (St 37) by various testing methods, such as the abrasive paper method, the abrasion cup method and the sand blasting method. The order of resistance of the various types of rubber against sand blasting is different from the order which is obtained with the sandpaper and abrasion cup methods. However, variations of the testing conditions within one method generally does not change the order. It has been shown, that rubber is more resistant against sand blasting than other materials investigated (basalb, malleable steel, non-alloyed hard castings) if the sand blast is directed essentially perpendicularly against the tested surface.

scholarly journals Determination of Cohesion values of Rock Materials using Double Shear Jaws

2018 ◽  
Author(s):  
Eren Komurlu ◽  
Aysegul Durmus Demir
Keyword(s):  
Failure Mechanisms ◽  
Shear Stresses ◽  
Compressive Test ◽  
Contact Conditions ◽  
Testing Conditions ◽  
Rock Materials ◽  
Double Shear ◽  
Different Types ◽  
Shear Planes

In this study, experimental and numerical analyses were carried out for determination of cohesion values of different types of rock materials using double shear jaws (DSJ) which can be practically used with the conventional compressive test equipment, to make shear planes in the rock core specimens. Effects of various parameters like jaw dimensions, gaps between triple blocks of the DSJ and contact conditions of the jaw on the results and validity of the cohesion test were investigated considering failure mechanisms of rock core specimens. Instead of a failure induced due to the shear stresses, tensile failures are mostly seen from conventional shear testing conditions. For a valid failure under the control of shear stresses, a DSJ design was suggested to be used in cohesion determination tests according to the results obtained from this study.

Detection of cracks in scratching tests in ceramic materials through acoustic emission

2005 ◽  
Vol 219 (9) ◽  
pp. 685-693 ◽  
Author(s):  
L E A Sanchez ◽  
J F G Oliveira ◽  
R T Coelho
Keyword(s):  
Acoustic Emission ◽  
Material Removal ◽  
Gradual Increase ◽  
Ceramic Materials ◽  
Polycrystalline Alumina ◽  
Testing Conditions ◽  
Emission Signal ◽  
Diamond Indenter ◽  
Different Types ◽  
Polycrystalline Ceramic

The mechanisms of material removal and the interactions among scratches performed in ceramic materials were investigated using acoustic emission signals, and scanning electron microscopy, in scratching experiments. Several testing conditions were used to produce different types of removing mechanism on a glass as well as on a polycrystalline alumina sample composed by heterogeneous grain size. It is known that the material removing process on a polycrystalline ceramic involves intergranular microfracture and grain dislodgement, unlike the chipping produced by the extension of lateral cracks in non-granular materials, such as glass. Distinct settings for velocities, loads, and two types of diamond indenter were tested. The material removal was carried out by three different methods of scratching: single passes, repeated overlapping passes, and parallel scratches. As a general result, there was a clear relationship between the acoustic emission signals and the damage intensity occurred in the material removal. More specifically there were differences in the acoustic emission signal levels in the scratches made on the alumina and on the glass owing to the material removal mechanisms associated with the structure of these materials. A gradual increase in the acoustic emission levels was observed when the number of repeated passes was increased as a result of the damage accumulation process followed by severe material removal. It was also noticed that the acoustic emission signals were capable of reflecting the interactions between two parallel scratches.

scholarly journals Retroactive Interference: Forgetting as an Interruption of Memory Consolidation

2017 ◽  
Vol 25 (3) ◽  
pp. 1055-1067 ◽  
Author(s):  
Marcus Vinicius C. Alves ◽  
Orlando Francisco A. Bueno
Keyword(s):  
Memory Consolidation ◽  
Retroactive Interference

The Role of Encoding Strategy in the Memory for Expectation-Violating Concepts

2019 ◽  
Vol 19 (3-4) ◽  
pp. 305-321
Author(s):  
Michaela Porubanova
Keyword(s):  
Memory Consolidation ◽  
Automatic Processing ◽  
Semantic Meaning ◽  
Memory Enhancement ◽  
Different Types ◽  
Shallow Condition ◽  
Encoding Strategy ◽  
Domain Level ◽  
Over Time

AbstractMinimal counterintuitiveness and its automatic processing has been suggested as the explanation of persistence and transmission of cultural ideas. This purported automatic processing remains relatively unexplored. We manipulated encoding strategy to assess the persistence of memory for different types of expectation violation. Participants viewed concepts including two types of expectation violation (schema-level or domain-level) or no violation under three different encoding conditions: in the shallow condition participants focused on the perceptual attributes of the concepts, a deep condition probed their semantic meaning, and intentional remembering condition. Participants’ recall was tested immediately as well as 2 weeks later. Our findings showed the greatest memory enhancement for schema-level violations regardless of the encoding condition, while the memory for domain-level violations improved over time. These results suggest two distinct memory patterns for different types of violations, and illustrate the importance of elaborative processes in memory consolidation especially for violations to our expectations.

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