Word Up! Directed motor action improves word learning [Abstract]

Can simple motor actions help people expand their vocabulary? Here we show that word learning depends on where students place their flash cards after studying them. In Experiment 1, participants learned the definitions of ”alien words” with positive or negative emotional valence. After studying each card, they placed it in one of two boxes (top or bottom), according to its valence. Participants who were instructed to place positive cards in the top box, consistent with Good is Up metaphors, scored about 10

Lateral guidance of all-wheel steered multiple-articulated vehicles

Nowadays, roads are becoming more and more congested, resulting in increasing economic losses due to delays. One way to solve this problem is to persuade people use public transp ortation more frequently. To achieve this, public transportation has to be improved. One way to improve public transportation is to construct a new kind of vehicle that combines the advantages of both commuter busses and railroad vehicles. Such a vehicle could be an all-wheel steered multiple-articulated vehicle. In the city of Eindhoven in The Netherlands, a new kind of transportation system will be operational in the year 2003, which is based on such vehicles. To achieve a track following behaviour similar to railroad vehicles, these vehicles have to be equipped with a lateral guidance system for steering them along a prede¯ne d path. This thesis deals with the design of such a guidance system. To achieve good tracking performance, the guidance system has to be modelbased. Therefore, a dynamic vehicle model has been derived. This model describes the nonlinear planar dynamics of an all-wheel steered n-carriage multiple-articulated vehicle. To validate this model, its frequency responses have been compared with the frequency responses of a 125 degrees of freedom multi-body model. This comparison shows good performance between both models. In order to show that a dynamic vehicle model is required, a comparison has been made between the dynamic vehicle model and a model describing only the kinematics of the vehicle. The position of the vehicle with respect to the path to be followed is crucial for proper control and therefore a measurement method based on the utilization of rotation symmetric bar magnets is presented. These magnets are buried in the road. By utilizing the rotation symmetry, the position to the magnet can be determined independently of the measurement height and the strength of the magnet. One requirement is that two ¯eld components are measured. It is shown that the sensitivity of this method to slant of the magnet and/or vehicle can be reduced by using a second dual-axes ¯eld sensor instead of one. Validation measurements show that the distance to the magnet can be determined with about 2 cm accuracy with 90 slant of the magnet. The permanent magnets yield position information exclusively and only at discrete instances. For controller design, knowledge of the complete state of the vehicle is desirable. An extended Kalman ¯lter has been designed to obtain continuous estimates of this state. To keep the in°uence of varying vehicle parameters small, accelerometers are used as input of the Kalman ¯lter. The accelerometer o®sets, road banking angle and vehicle roll angle are estimated online, to reduce the e®ect of these parameters. The position information obtained from the permanent magnets is used to apply corrections to state predictions that are based on the accelerometer outputs. The discrete and asynchronous character of this position information has been dealt with by implementing the Kalman ¯lter in a multi-rate fashion. Articulation angle sensors, wheel encoders and rate gyros are added to the Kalman ¯lter to improve the performance and to obtain redundan cy of sensors. The vehicles that will be used in the public transportation system in Eindhoven have, apart from all-wheel steering, also independent electrical drives on each of the wheels, except the two wheels at the front. This independent drive can in principle also be used for steering the vehicle, by using the drives on one axle in a di®erential way. A singular value analysis shows that steering with normal steering angles is much more in°uential than using these di®erential torques. It has also been analyzed that both at low and high speed all-wheel steering is bene¯cial to reduce o®-tracking of the rear axles and to improve the yaw dynamics of the vehicle. Two di®erent controllers have been designed for steering the vehicle, based on the outputs of the Kalman ¯lter, along the path to be followed. The ¯rst of these controllers is a feedback linearizing controller. This controller can be considered to consist of two control loops. The inner loop linearizes the planar vehicle dynamics, under the assumption that the steering system dynamics can be neglected. The outer control loop is used to counteract parameter uncertainty and disturbances. For this outer loop, a PID controller has been used. The second controller is a so-called backsteppin g controller. With this controller, also the steering actuator dynamics are taken into account. To simulate the behavior of the lateral guidance system, a more complex vehicle model has been used. This model describes besides the planar vehicle dynamics also the dynamics of the susp ension system. A nonlinear tire model has been used in this model. Simulations with this 3D simulation model show good tracking performance for both the feedback linearizing controller and the backstepping controller. The backstepping controller shows improved tracking performance compared to the feedback linearizing controller. However, this goes at the cost of increased high frequent behavior or the lateral acceleration

Lateral guidance of all-wheel steered multiple-articulated vehicles

Nowadays, roads are becoming more and more congested, resulting in increasing economic losses due to delays. One way to solve this problem is to persuade people use public transp ortation more frequently. To achieve this, public transportation has to be improved. One way to improve public transportation is to construct a new kind of vehicle that combines the advantages of both commuter busses and railroad vehicles. Such a vehicle could be an all-wheel steered multiple-articulated vehicle. In the city of Eindhoven in The Netherlands, a new kind of transportation system will be operational in the year 2003, which is based on such vehicles. To achieve a track following behaviour similar to railroad vehicles, these vehicles have to be equipped with a lateral guidance system for steering them along a prede¯ne d path. This thesis deals with the design of such a guidance system. To achieve good tracking performance, the guidance system has to be modelbased. Therefore, a dynamic vehicle model has been derived. This model describes the nonlinear planar dynamics of an all-wheel steered n-carriage multiple-articulated vehicle. To validate this model, its frequency responses have been compared with the frequency responses of a 125 degrees of freedom multi-body model. This comparison shows good performance between both models. In order to show that a dynamic vehicle model is required, a comparison has been made between the dynamic vehicle model and a model describing only the kinematics of the vehicle. The position of the vehicle with respect to the path to be followed is crucial for proper control and therefore a measurement method based on the utilization of rotation symmetric bar magnets is presented. These magnets are buried in the road. By utilizing the rotation symmetry, the position to the magnet can be determined independently of the measurement height and the strength of the magnet. One requirement is that two ¯eld components are measured. It is shown that the sensitivity of this method to slant of the magnet and/or vehicle can be reduced by using a second dual-axes ¯eld sensor instead of one. Validation measurements show that the distance to the magnet can be determined with about 2 cm accuracy with 90 slant of the magnet. The permanent magnets yield position information exclusively and only at discrete instances. For controller design, knowledge of the complete state of the vehicle is desirable. An extended Kalman ¯lter has been designed to obtain continuous estimates of this state. To keep the in°uence of varying vehicle parameters small, accelerometers are used as input of the Kalman ¯lter. The accelerometer o®sets, road banking angle and vehicle roll angle are estimated online, to reduce the e®ect of these parameters. The position information obtained from the permanent magnets is used to apply corrections to state predictions that are based on the accelerometer outputs. The discrete and asynchronous character of this position information has been dealt with by implementing the Kalman ¯lter in a multi-rate fashion. Articulation angle sensors, wheel encoders and rate gyros are added to the Kalman ¯lter to improve the performance and to obtain redundan cy of sensors. The vehicles that will be used in the public transportation system in Eindhoven have, apart from all-wheel steering, also independent electrical drives on each of the wheels, except the two wheels at the front. This independent drive can in principle also be used for steering the vehicle, by using the drives on one axle in a di®erential way. A singular value analysis shows that steering with normal steering angles is much more in°uential than using these di®erential torques. It has also been analyzed that both at low and high speed all-wheel steering is bene¯cial to reduce o®-tracking of the rear axles and to improve the yaw dynamics of the vehicle. Two di®erent controllers have been designed for steering the vehicle, based on the outputs of the Kalman ¯lter, along the path to be followed. The ¯rst of these controllers is a feedback linearizing controller. This controller can be considered to consist of two control loops. The inner loop linearizes the planar vehicle dynamics, under the assumption that the steering system dynamics can be neglected. The outer control loop is used to counteract parameter uncertainty and disturbances. For this outer loop, a PID controller has been used. The second controller is a so-called backsteppin g controller. With this controller, also the steering actuator dynamics are taken into account. To simulate the behavior of the lateral guidance system, a more complex vehicle model has been used. This model describes besides the planar vehicle dynamics also the dynamics of the susp ension system. A nonlinear tire model has been used in this model. Simulations with this 3D simulation model show good tracking performance for both the feedback linearizing controller and the backstepping controller. The backstepping controller shows improved tracking performance compared to the feedback linearizing controller. However, this goes at the cost of increased high frequent behavior or the lateral acceleration

Walking behaviour of healthy elderly: attention should be paid

<p>Abstract</p> <p>Background</p> <p>Previous studies have reported an association between executive function (EF) and measures of gait, particularly among older adults. This study examined the relationship between specific components of executive functions and the relative dual task costs of gait (DTC) in community-dwelling non-demented older adults, aged 65 years and older.</p> <p>Methods</p> <p>Temporal (stride time, stride velocity) and spatial (stride length) gait characteristics were measured using a GAITRite^®-System among 62 healthy community dwelling older adults while walking with and without backward counting (BC) at preferred and fast walking speeds. Specific executive functions <it>divided attention</it>, <it>memory </it>and <it>inhibition </it>were assessed using the Test for Attentional Performance (TAP). Other measures included Mini-Mental State Examination (MMSE), amount of daily medications taken, educational level and sociodemographic characteristics. Adjusted and unadjusted multivariable linear regression models were developed to assess the relations between variables.</p> <p>Results</p> <p>High relative DTC for stride time, stride velocity and stride length were associated with divided attention at fast walking speed. High relative DTC for stride time was associated with divided attention at preferred walking speed. The association between high DTC of stride length and memory was less robust and only observable at preferred walking speed. None of the gait measures was associated with inhibition.</p> <p>Conclusions</p> <p>Spatial and temporal dual task cost characteristics of gait are especially associated with divided attention in older adults. The results showed that the associated DTC differ by executive function and the nature of the task (preferred versus fast walking). Further research is warranted to determine whether improvement in divided attention translates to better performance on selected complex walking tasks.</p

Equilibrium states for potentials with \sup\phi - \inf\phi < \htop(f)

In the context of smooth interval maps, we study an inducing scheme approach to prove existence and uniqueness of equilibrium states for potentials $\phi$ with he `bounded range' condition \sup \phi - \inf \phi < \htop, first used by Hofbauer and Keller. We compare our results to Hofbauer and Keller's use of Perron-Frobenius operators. We demonstrate that this `bounded range' condition on the potential is important even if the potential is H\"older continuous. We also prove analyticity of the pressure in this context.Comment: Added Lemma 6 to deal with the disparity between leading eigenvalues and operator norms. Added extra references and corrected some typo

Virtual reality rehabilitation as a treatment approach for older women with mixed urinary incontinence : a feasibility study

Background Motivated patients are more likely to adhere to treatment resulting in better outcomes. Virtual reality rehabilitation (VRR) is a treatment approach that includes video gaming to enhance motivation and functional training. Aims The study objectives were (1) to evaluate the feasibility of using a combination of pelvic floor muscles (PFM) exercises and VRR (PFM/VRR) to treat mixed urinary incontinence (MUI) in older women, (2) to evaluate the effectiveness of the PFM/VRR program on MUI symptoms, quality of life (QoL), and (3) gather quantitative information regarding patient satisfaction with this new combined training program. Methods Women 65 years and older with at least 2 weekly episodes of MUI were recruited. Participants were evaluated two times before and one time after a 12-week PFM/VRR training program. Feasibility was defined as the participants' rate of participation in and completion of both the PFM/VRR training program and the home exercise. Effectiveness was evaluated through a bladder diary, pad test, symptom and QoL questionnaire, and participant's satisfaction through a questionnaire. Results Twenty-four women (70.5 ± 3.6 years) participated. The participants complied with the study demands in terms of attendance at the weekly treatment sessions (91%), adherence to home exercise (92%) and completion of the three evaluations (96%). Post-intervention, the frequency and quantity of urine leakage decreased and patientreported symptoms and QoL improved significantly. Most participants were very satisfied with treatment (91%). Conclusion A combined PFM/VRR program is an acceptable, efficient, and satisfying functional treatment for older women with MUI and should be explore through further RCTs

Complex maps without invariant densities

We consider complex polynomials $f(z) = z^\ell+c_1$ for $\ell \in 2\N$ and $c_1 \in \R$, and find some combinatorial types and values of $\ell$ such that there is no invariant probability measure equivalent to conformal measure on the Julia set. This holds for particular Fibonacci-like and Feigenbaum combinatorial types when $\ell$ sufficiently large and also for a class of `long-branched' maps of any critical order.Comment: Typos corrected, minor changes, principally to Section