The targeted force steps developed by a human wrist: Force trajectories under conditions of repetition or random alternation of different target levels

1994 ◽  
Vol 25 (5) ◽  
pp. 324-332 ◽  
Author(s):  
V. Ya. Pyatigorsky ◽  
D. A. Vasilenko ◽  
A. �. Ivanov
Keyword(s):  
Random Alternation

scholarly journals The Palatalisation of /ʤ/ into /j/ in Emirati Arabic (EA): A Rule-Governed or Random Alternation?

2017 ◽  
Vol 9 (5) ◽  
pp. 173
Author(s):  
Hodan Mohamoud Hassan
Keyword(s):  
Language Contact ◽  
Arabic Dialects ◽  
Random Alternation

This study aims to investigate a phonological phenomenon that occurs in Emirati Arabic (EA), whereby the voiced palato-alveolar affricate /ʤ/ changes into the voiced palatal approximate (glide) /j/. In particular, this study attempts to determine whether this phonological alternation is triggered by a certain phonological environment, or whether it occurs randomly without any rule. It also endeavours to examine the hypothesis that this phonological phenomenon was borrowed from other Arabic dialects spoken in the Gulf through language contact.

Mixed-layer kaolinite-illite-vermiculite in North Sea shales

Clay Minerals ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 333-344 ◽  
Author(s):  
B. A. Sakharov ◽  
H. Lindgreen ◽  
A. L. Salyn ◽  
V. A. Drits
Keyword(s):  
North Sea ◽  
Mixed Layer ◽  
Coherent Scattering ◽  
Upper Jurassic ◽  
The North ◽  
Dominant Component ◽  
The North Sea ◽  
Xrd Patterns ◽  
Layer Mineral ◽  
Random Alternation

AbstractThe finest fractions of Upper Jurassic shales from the North Sea and onshore Denmark contain 80–90% of an illite-smectite-vermiculite (I-S-V) mixed-layer mineral and, in addition a phase which has X-ray diffraction (XRD) peaks at 7.20–7.26 Å and 3.56–3.58 Å in air- dried and glycolated specimens. This phase may be a fine kaolinite with a small thickness of coherent scattering domains (CSDs) or alternatively a mixed-layer mineral which has kaolinite as the dominant component. For one sample from the Norwegian well 9/4-3, these alternatives are investigated using the multi-specimen method by which agreement between the experimental pattern and the pattern calculated for one and the same structure is obtained for each of several specimens saturated with different cations and with/without glycolation. It is demonstrated that the modelled XRD patterns for a kaolinite-illite-vermiculite (K-I-V) structure having 0.94 kaolinite, 0.03 illite and 0.03 vermiculite layers and random alternation fit the experimental patterns.

Contribution to the Study of Ethylene-Propylene Copolymers by Infrared Spectroscopy. Distribution of Monomeric Units

1965 ◽  
Vol 38 (2) ◽  
pp. 334-342 ◽  
Author(s):  
Giovanni Bucci ◽  
Tonino Simonazzi
Keyword(s):  
Infrared Spectroscopy ◽  
Numerical Evaluation ◽  
Distribution Functions ◽  
Reactivity Ratios ◽  
Block Polymers ◽  
Ethylene Propylene ◽  
Copolymer Microstructure ◽  
Catalyst Systems ◽  
Random Alternation ◽  
Theoretical Considerations

Abstract Elastomeric properties of ethylene-propylene copolymers depend not only on the composition but also on the copolymer microstructure, i.e., on the distribution of monomeric units along the macromolecular chain. According to Natta and coworkers the best polymer should be obtained when two monomeric units are randomly alternated in the macromolecule. The random alternation of the monomers is actually only partial because somewhat longer homosequences are formed. In such a case one deals with block polymers. On the basis of some theoretical considerations on the copolymerization process and also on the basis on the reactivity ratios of the two monomers, Natta and coworkers have calculated the distribution functions of sequences for various catalyst systems. Infrared spectroscopy has been widely used in connection with this problem though from different viewpoints and with different aims. The purpose of our work is to reanalyze the whole problem. We have focused our attention on the CH2 rocking band in the sequence (—CH2—)n, where n varies from 1 to 5 or more. Some disagreement exists between various authors on the assignment of these bands, especially in the case of the (—CH2—)3 and (—CH2—)4 sequences. We have then divided our work as follows: (a) assignment of infrared bands in the spectral region between 900 and 650 cm−1; (b) calculation of absorbances at various frequencies; (c) attempt at a numerical evaluation of the distribution of monomeric units.

SPATIAL PATTERNS INDUCED BY RANDOM SWITCHING

2002 ◽  
Vol 02 (01) ◽  
pp. L21-L29 ◽  
Author(s):  
J. BUCETA ◽  
KATJA LINDENBERG ◽  
J. M. R. PARRONDO
Keyword(s):  
Pattern Formation ◽  
Numerical Simulations ◽  
Spatial Patterns ◽  
Reaction Diffusion ◽  
Homogeneous State ◽  
Ordered Structures ◽  
Reaction Diffusion Systems ◽  
Diffusion Systems ◽  
Random Switching ◽  
Random Alternation

We propose a mechanism whereby a random alternation of two dynamics each leading to a different homogeneous state can lead to complex ordered structures. The proposed general formalism, based on the ideas of so-called paradoxical games, is illustrated via numerical simulations of particular examples. The relevance of the present study to other situations that lead to pattern formation, such as reaction-diffusion systems, is noted.

Dopamine neurons of the monkey midbrain: contingencies of responses to stimuli eliciting immediate behavioral reactions

1990 ◽  
Vol 63 (3) ◽  
pp. 607-624 ◽  
Author(s):  
W. Schultz ◽  
R. Romo
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Contralateral Side ◽  
Dopamine Neurons ◽  
Direct Reaction ◽  
Neuronal Responses ◽  
Behavioral Reactions ◽  
Door Opening ◽  
Trigger Stimulus ◽  
Random Alternation

1. This study investigates the behavioral conditions in which dopamine (DA) neurons of substantia nigra and adjoining areas A8 and A10 respond with impulses to visual and auditory trigger stimuli eliciting immediate arm- and eye-movement reactions. 2. In a formal task, the rapid opening of the door of a small, food-containing box located at eye level ahead of the animal served as visible and audible trigger stimulus. Most DA neurons on the contralateral side responded to this stimulus with a short burst of impulses with median onset latency of 50 ms and duration of 90 ms (75% of 164 neurons). Similar responses were seen in a comparable fraction of DA neurons during ipsilateral task performance, suggesting that responses were not specific for the limb being used. 3. When the sensory components of the door opening stimulus were separated, DA neurons typically responded in a similar manner to the moving visual stimulus of the opening door, the low-intensity sliding noise of the opening door, and the 1-kHz sound of 90-92 dB intensity emitted from a distant source at the onset of door opening. Responses to each component alone were lower in magnitude than to all three together. 4. In a variation of the task, a neighboring, identical food box opened in random alternation with the other box but without permitting animals to reach out (asymmetric, direct-reaction go/no-go task). With each sensory component, DA neurons typically responded both to opening of go and no-go boxes. Responses were enhanced when stimuli elicited limb movements in go trials. 5. Monkeys reacted to door opening with target-directed saccadic eye movements in the majority of both go and no-go trials. Neuronal responses were equally present during the occasional absence of eye movements. Thus responses were not specific for the initiation of individual arm or eye movements. 6. Neuronal responses were absent when the same stimuli occurred outside of the behavioral task with target-direct arm and eye movements lacking. This shows that responses were not of purely sensory nature but were related to the capacity of the stimulus for eliciting behavioral reactions. 7. In a variation of the go/no-go task, an instruction light illuminated 2-3 s before door opening prepared the animal to perform the reaching movement on door opening or to refrain from moving (asymmetric, instruction-dependent go/no-go task).(ABSTRACT TRUNCATED AT 400 WORDS)

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