Control of Bimanual Rhythmic Movements: Trading Efficiency for Robustness Depending on the Context

in Experimental Brain Research = Experimentelle Hirnforschung = Expérimentation Cérébrale (2008)

This paper investigates how the efficiency and robustness of a skilled rhythmic task compete against each other in the control of a bimanual movement. Human subjects juggled a puck in 2D through impacts ... [more ▼]

This paper investigates how the efficiency and robustness of a skilled rhythmic task compete against each other in the control of a bimanual movement. Human subjects juggled a puck in 2D through impacts with two metallic arms, requiring rhythmic bimanual actuation. The arms kinematics were only constrained by the position, velocity and time of impacts while the rest of the trajectory did not influence the movement of the puck. In order to expose the task robustness, we manipulated the task context in two distinct manners: the task tempo was assigned at four different values (hence manipulating the time available to plan and execute each impact movement individually); and vision was withdrawn during half of the trials (hence reducing the sensory inflows). We show that when the tempo was fast, the actuation was rhythmic (no pause in the trajectory) while at slow tempo, the actuation was discrete (with pause intervals between individual movements). Moreover, the withdrawal of visual information encouraged the rhythmic behavior at the four tested tempi. The discrete versus rhythmic behavior give different answers to the efficiency/robustness trade-off: discrete movements result in energy efficient movements, while rhythmic movements impact the puck with negative acceleration, a property preserving robustness. Moreover, we report that in all conditions the impact velocity of the arms was negatively correlated with the energy of the puck. This correlation tended to stabilize the task and was influenced by vision, revealing again different control strategies. In conclusion, this task involves different modes of control that balance efficiency and robustness, depending on the context. [less ▲]

Control of breathing in healthy and pasteurella-exposed calves after 5-HT receptor blockade

in Proceedings of the XIXth World Association for Buiatrics Congress (1996)

Control of breathing in unanesthetized healthy and Pasteurella-exposed calves after 5-HT2 receptor antagonism by metrenperone

in Proceedings of the XVIIIth World Buiatrics Congress (1994)

Control of Dioscorea alata microtubers dormancy and germination by jasmonic acid

in Plant Growth Regulation (1999), 27(2), 113-117

Effects of appling exogenous jasmonic acid (JA) on the germination of Dioscorea alata L. microtubers were examined on Murashige and Skoog (MS) medium. Microtuber germination was promoted by JA (0.1 and 1 ... [more ▼]

Effects of appling exogenous jasmonic acid (JA) on the germination of Dioscorea alata L. microtubers were examined on Murashige and Skoog (MS) medium. Microtuber germination was promoted by JA (0.1 and 1 µM) supplemented to the culture medium but higher concentrations (30 and 100 µM) completely inhibited germination. When these inhibited microtubers were transferred to hormone-free medium, germination resumed. After transfer to greenhouse conditions, almost all plants (95%) from tubers previously cultivated on MS medium with 100 µM JA survived and all acclimatized plants had produced tubers after 8 months. It is concluded that depending on JA concentration, both the germination and dormancy processes in D. alata microtubers were affected. The release from dormancy is easily obtained by transferring dormant microtubers to hormone-free medium. [less ▲]

Control of drug-resistant epilepsy after head injury with intravenous nimodipine.

in Acta Anaesthesiologica Belgica (1994), 45(4), 175-8

The present report describes a young child who developed generalized epileptic seizures in the course of severe head injury. The start of epileptic seizures was associated with the occurrence of acute ... [more ▼]

The present report describes a young child who developed generalized epileptic seizures in the course of severe head injury. The start of epileptic seizures was associated with the occurrence of acute hyponatremia and hypoosmolality due to excessive Desmopressine administration. The seizures resistant to conventional therapy resolved completely with intravenous nimodipine infusion. [less ▲]

Control of floral transition in maize

Conference (2008, September)

Flowering time in plants is controlled by a number of environmental factors, among which photoperiod plays a key role. Maize ancestors are short-day (SD) plants, but breeding programs have selected ... [more ▼]

Flowering time in plants is controlled by a number of environmental factors, among which photoperiod plays a key role. Maize ancestors are short-day (SD) plants, but breeding programs have selected genotypes whose flowering is largely autonomous and occurs after production of a constant number of leaves regardless of photoperiod. Only few flowering time genes have been identified in maize; one of them is INDETERMINATE1 (ID1), cloned from a late-flowering mutant and encoding a zinc finger transcription factor. By contrast, the genetical control of flowering by photoperiod is best understood in the long-day (LD) dicot Arabidopsis and the SD monocot rice. A key regulator is the CONSTANS gene that mediates between the circadian clock – the time-keeper of the plant – and the synthesis of flowering signals. Here we report the analysis of a CONSTANS homolog in maize, ZmCO, in SD and in LD, and in different parts of the plant. Expression of ZmCO was found to be rhythmic and to be much higher in young leaf primordia than in mature leaf blades. Striking coincidence was observed with expression of ID1. [less ▲]

The control of flowering: do genetical and physiological approaches converge ?

in O'Neill, S. D.; Roberts, J. A. (Eds.) Plant Reproduction (2002)

Since the early 1990s, Arabidopsis thaliana has been studied as the species of choice of 'flowering geneticists'. Several pathways that either repress or promote flowering have been identified on the ... [more ▼]

Since the early 1990s, Arabidopsis thaliana has been studied as the species of choice of 'flowering geneticists'. Several pathways that either repress or promote flowering have been identified on the basis of (1) the flowering response of different genotypes to environmental factors (vernalization and photoperiod), (2) epistasis analyses, and (3) expression patterns of cloned genes in various backgrounds. Models attempting to include all information have been proposed repeatedly and their complexity is increasing with the bulk of data. In this review, we shall attempt to integrate into this genetical framework the physiological knowledge accumulated on a variety of plants by generations of researchers before the amost overnight breakthrough of Arabidopsis. [less ▲]

Control of hypertension in a kidney transplanted population : the EPARA study”.

Scientific conference (2010, November 27)

The prevalence of hypertension in this specific KT population remains high in spite of different antiHTA drugs use and the well known deleterious effect of HTA on kidney function and cardiovascular risk ... [more ▼]

The prevalence of hypertension in this specific KT population remains high in spite of different antiHTA drugs use and the well known deleterious effect of HTA on kidney function and cardiovascular risk. Home BP (and/or ABPM) should thus be recommended to identify this situation and secondary to adapt the treatment. [less ▲]

Control of inflammation in experimental bovine pneumonic pasteurellosis

in Bovine Practitioner (1998), 31(1), 5-13

Control of key pecking by the duration of a visual stimulus

in Journal of the Experimental Analysis of Behavior (1974), 22(1), 131-134

Pigeons' key peck were brought under the control of the duration of a visual stimulus in one-key and two-key procedures. In the one-key procedure, pecks were reinforeced after presentations of a long ... [more ▼]

Pigeons' key peck were brought under the control of the duration of a visual stimulus in one-key and two-key procedures. In the one-key procedure, pecks were reinforeced after presentations of a long-duration stimulus but not after presentations of a short-duration stimulus. In the two-key procedure, left-key pecks were reinforced after the long-duration stimulus and right-key pecks after the short-duration stimulus. In both procedures, the long-duration stimulus was 10 sec, and the short-duration stimulus was increased from 1 to 8 sec in1-sec steps. Discriminative control developed with both procedures, but with greater acuracy in the two-key procedures, in which a difference threshold was obtained at short-duration values between 7 and 8 sec, or about 2.5 sec shorter than the long-duration stimulus. [less ▲]