Control of hand shaping in response to object shape perturbation

This study assessed how hand shaping responds to a perturbation of object shape. In blocked trials (80% of total), subjects were instructed to reach, to grasp and lift a concave or a convex object. In perturbed trials (20% of total), a rotating device allowed for the rapid change from the concave to the convex object or vice versa. In this situation subjects grasped the last presented object. Flexion/extension at the metacarpal-phalangeal and proximal interphalangeal joints of all digits was measured by resistive sensors embedded in a glove. In the blocked condition we found that most joints of the fingers were modulated by the type of the to-be-grasped object during the reach. When object shape was perturbed, reach duration was longer and angular excursion of all fingers differed with respect to blocked trials. For the ‘convex → concave’ perturbation, a greater degree of finger extension was found than during the blocked ‘concave’ trials. In contrast, for the ‘concave → convex’ perturbation, fingers were more flexed than for the blocked ‘convex’ trials. The thumb reacted to the perturbation showing a similar pattern (i.e., over-flexion with respect to the blocked trials) regardless the ‘direction’ of the perturbation. The present results suggest that applying an object shape perturbation during a reach-to-grasp action determines a reorganization of all digits. This pattern is suggestive of a control strategy, which assigns to opposing digits different roles.     

Fractal dynamics of polarized bioelectrodes

This study is concerned with mathematical modelling of the fundamental relationship which exists between the current density and the overpotential across the metalsolution interface in the linear range using methods of system theory enhanced by ‘fractal’ concepts. A primer for both 1/f-type scaling and ‘anomalous’ relaxation/dispersion concepts is provided, followed by a brief review of the research history pertinent to the metal electrode polarization dynamics. Next, the ‘fractal relaxation systems’ approach is introduced to characterize, systems which attenuate with a fractional power-low dependence on frequency through a ‘scaling exponent’. The ‘singularity structure’ which is a scaling, rational system function is proposed to expand fractal systems in terms of basic subsystems individually representing elementary exponential relaxations and collectively exhibiting scaling properties. We stress that the ‘singularity structure’ carries scaling information identical to the conventional ‘distribution of relaxation times’ function. ‘Structure scale’ and ‘view scale’ concepts are presented in the due course to streamline the analysis of scaling phenomena in general and the polarization impedance in particular. System theory-wise, the notable result is that the fractional power function attenuation, or equivalently, the logarithmic nature of the distribution function translates into the ‘self-similar’ pattern replication of the system singularities in the s-plane. The singularity arrangement is governed by a recursive rule solely based on the knowledge of the fractional power factor or the scaling exponent.     

Information system for biomedical equipment management in a wide-area environment

An information system used in managing the inventory of equipment at the local health units (LHUs) of the Emilia Romagna region is presented. The system aims at efficient management of information on medical equipment and at supporting regional administrators in financial planning. The system uses ‘classification files’ and ‘working files’. The classification files can be either defined at national (classification of producers, models and equipment types) or local (classification of suppliers and hospital departments) level. The working files are used to store all information necessary for the inventory of equipment in the local health unit (equipment inventory file) and results of automatic annual economic computations (residual values and amortisation quota file). Starting from data stored in the above-mentioned files the system can perform several procedures, such as control on data entry, economic computations and report printings. The main aspects of these operations are described in detail. Finally, some information on biomedical equipment of one of the largest local health units of the Emilia Romagna region, obtained from elaboration of system data, is shown and discussed.     

Source density analysis of scalp potentials during linguistic and non-linguistic processing of visual stimuli

Summary Event-related potentials (ERPs) were recorded from 40 locations, covering most of the scalp, during repeated tasks in which the observer (O) had to judge either the tense of a printed verb (V) or the symmetry of a spatial pattern (S). Stimuli were drawn at random from large ensembles. A simplified method of Laplacean analysis (MacKay 1983, 1984) allowed the corresponding source densities to be mapped at up to 28 locations, relatively free of artefacts due to eye movements or tongue movements. O signalled his judgment in each case by pressing one of two buttons on a given cue. The decision time allowed was kept short (about 1 s) but long enough for the task to be handled successfully. When stimuli ‘V’ and ‘S’ were drawn from geometrically different ensembles, the source-density distributions for the two tasks differed significantly at a number of locations. When ‘V’ and ‘S’ were drawn from a common ensemble, however, and O was instructed on each trial (in random order) to assess each stimulus as a word or as a geometrical pattern, the similarities in the source-density maps were more striking than the differences. It would seem that during sufficiently rapid verbal and spatial judgments, little sign of hemispheric specialization or task-specific differences may appear in the spatiotemporal profile of ERP source densities. More salient differences, some lateralized, appeared during the preparation interval prior to verbal and spatial tasks; but their pattern varied widely from subject to subject.     

Dependence of cardiac strength-interval curves on pacing rate

The purpose of the research is to determine how the pacing rate affects the strength-interval curve in cardiac tissue. Computer simulations are used to calculate the cathodal and anodal strength-interval curves. The tissue is represented by the bidomain model with Beeler-Reuter membrane properties. The strength-interval curves shift to shorter intervals as the pacing rate increases. However, the shape of the strength-interval curve, including the separation into ‘make’ and ‘break’ sections and the presence of a ‘dip’, is insensitive to pacing rate.     

Gait control system for functional electrical stimulation using neural networks

In functional electrical stimulation (FES) systems for restoring walking in spinal cord injured (SCI) individuals, hand switches are the preferred method for controlling stimulation timing. Through practice the user becomes an ‘expert’ in determining when stimulation should be applied. Neural networks have been used to ‘clone’ this expertise but these applications have used small numbers of sensors, and their structure has used a binary output, giving rise to possible controller oscillations. It was proposed that a threelayer structure neural network with continuous function, using a larger number of sensors, including ‘virtual’ sensors, can be used to ‘clone’ this expertise to produce good controllers. Using a sensor set of ten force sensors and another of 13 ‘virtual’ kinematic sensors, a good FES control system was constructed using a three-layer neural network with five hidden nodes. The sensor set comprising three sensors showed the best performance. The accuracy of the optimum three-sensor set for the force sensors and the virtual kinematic sensors was 90% and 93%, respectively, compared with 81% and 77% for a heel switch. With 32 synchronised sensors, binary neural networks and continuous neural networks were constructed and compared. The networks using continuous function had significantly fewer oscillations. Continuous neural networks offer the ability to generate good FES controllers.     

Pattern recognition approach to the detection of single-trial event-related functional magnetic resonance images

Functional magnetic resonance imaging (FMRI) is an imaging technique for determining which regions of the brain are activated in response to a stimulus or event. Early FMRI experiment paradigms were based upon those used in positron emission tomography (PET), i.e. employing a block design consisting of extended periods of ‘on’ against ‘off’ activations. More recent experiments were based on event-related FMRI, harnessing the fact that very short stimuli trains or single events can generate robust responses. FMRI data suffer from low signal-to-noise ratios, and typical event-related experiment paradigms employ selective averaging over many trials before using statistical methods for determining active brain regions. The paper reports a pattern recognition approach to the detection of single-trial FMRI responses without recourse to averaging and at modest field strengths (1.5T). Linear discriminant analysis (LDA) was applied in conjunction with different feature extraction techniques. Use of the unprocessed data samples as features resulted in singletrial events being classified with an accuracy of 61.0±9.5% over five subjects. To improve classification accuracy, knowledge of the ideal template haemodynamic response was used in the feature extraction stage. A novel application of parametric modelling yielded an accuracy of 69.8±6.3%, and a matched filtering approach yielded an accuracy of 71.9±5.4%. Single-trial detection of event-related FMRI may yield new ways of examining the brain by facilitating new adaptive experiment designs and enabling tight integration with other single-trial electrophysiological methods.     

The use of a ‘phantom scalp’ to assess the possible direct pickup of mobile phone handset emissions by electroencephalogram electrode leads

A ‘Phantom Scalp’ was constructed from a conducting foam mat to form a layer under a 62-electrode electroencephalogram cap closely approximating the electrical properties of a human scalp. The mat was placed over a polystyrene manikin head to preserve a correct anatomical arrangement. Electrical signals were recorded with a Global System for Mobile (GSM) communications mobile phone handset in place against the side of the ‘head’. Amplitude spectra were compared for three phone conditions: ‘off’, ‘standby’ and ‘transmit’. At 217 Hz, significant differences were obtained between ‘transmit’ and the other two conditions, but no significant differences were noted for the physiologically important range 0.5–30 Hz. An anomalous difference was noted for one electrode in the range 30–45 Hz.     

Texture analysis of technegas lung ventilation images

Technegas lung ventilation images sometimes have ‘hot spots’, particularly in patients with respiratory disease. A novel technique is presented for quantifying this ‘spottiness’ using morphological texture analysis. A set of 32 images from patients with various respiratory diseases is studied. Images are filtered at a range of scales using morphological opening, and the slopes of image metrics versus structuring element size are used as texture parameters. The results are compared with the opinions of three experienced nuclear medicine physicians who have classified the images into two groups, ‘spotty’ and ‘non-spotty’, and have ranked the former. For the spotty images, the computer and observer ranks are compared; the highest correlation is r_s=0.66 (p=0.01) for a single parameter, andr _s =0.71 (p<0.01) for a combination of two parameters. Using a pair of parameters, 83% and 90% correct classification rates are obtained for the spotty and non-spotty classes, respectively. It is concluded that these texture parameters provide a useful measure of image spottiness, and it is demonstrated that this technique is superior to previously published methods. The practical value of the technique is illustrated using two applications.     

Digital assessment of lower rectum fixity in rectal prolapse (DALR): a simple clinical anatomical test to determine the most suitable approach (abdominal versus perineal) for repair

Selection of an appropriate approach to treat full thickness rectal prolapse remains problematic and controversial. We propose that rectal prolapse may be classified as ‘low type‘ (true rectal prolapse) or ‘high type’ (intussusception of the sigmoid with a fixed lower rectum). This assessment can be made via a simple clinical test of digital rectal assessment of lower rectal fixity (‘the hook test’) based on anatomic changes in rectal prolapse to guide the selection process. In cases with the low-type prolapse, a perineal approach is appropriate (either Delorme’s procedure, or rectosigmoidectomy with or without pelvic floor repair). For the high type, an abdominal rectopexy with or without high anterior resection is needed. Retrospective analysis of our cases treated over the last 6 years showed a recurrence rate of 6% in perineal procedures and 0% in abdominal rectopexy combined with resection to date. We believe that employing our simple test and classification can contribute to better patient selection for either approach, minimize anaesthetic and surgical risks and also result in lower recurrence rates.     

Computerised method for acquisition and display of gastrointestinal motility data

A computerised system is developed for the acquisition and display of gastrointestinal motility data which utilises a purpose developed software program called ‘PC-motil’, running on an IBM compatible microcomputer. ‘PC-motil’ displays data during collection, writes data to disk file and compresses all data at the end of a study on to a single monitor screen for convenient overview. Any area of interest, in single or multiple channels, may be selected and expanded for detailed examination. This system is tested by the recording of gastric and jejunal motility patterns of 11 healthy volunteers in fasting and fed states. All antral and jejunal migrating motor complexes (MMCs) in fasting studies, as well as all fed motility patterns were recognisable in both ‘compressed’ and ‘expanded’ form. The reproduction of motility patterns by the computer based system was indistinguishable from that of a conventional analogue chart recorder. This computerised system provides a convenient and cost-effective means of acquisition, storage and display of motility data in digital form.     

Reasons women give for abortion: a review of the literature

The aim was to identify from empirical research that used quantitative or qualitative methods the reasons women give for having an abortion. A search was conducted of peer-reviewed, English language publications indexed in eight computerized databases with publication date 1996–2008, using keywords ‘abortion’ and ‘reason’ (Medline: ‘induced abortion’ OR ‘termination of pregnancy’ OR ‘elective abortion’ and ‘reason’). Inclusion criteria were empirical research on humans that identified women’s reasons for undergoing an abortion, conducted in ‘high-income’ countries. 19 eligible papers were found. Despite variation in methods of generating, collecting, and analysing reasons, and the inadequacy of methodological detail in some papers, all contributed to a consistent picture of the reasons women give for having an abortion, with three main categories (‘Woman-focused’, ‘Other-focused’, and ‘Material’) identified. Ambivalence was often evident in women’s awareness of reasons for continuing the pregnancy, but abortion was chosen because continuing with the pregnancy was assessed as having adverse effects on the life of the woman and significant others. Women’s reasons were complex and contingent, taking into account their own needs, a sense of responsibility to existing children and the potential child, and the contribution of significant others, including the genetic father.     

Finger interaction during maximal radial and ulnar deviation efforts: experimental data and linear neural network modeling

The purpose of this study was to characterize finger interactions during radial/ulnar deviation, including interactions with flexion movements. Subjects performed single-finger and multi-finger maximal voluntary contraction (MVC), and maximal forces and various indices of interaction among the fingers were quantified. MVCs in radial/ulnar deviation were 50–80% as strong as in flexion. Along with the ‘master’ fingers (i.e., those explicitly instructed to produce force), substantial force production was also observed in ‘slave’ fingers (i.e., those not explicitly instructed to produce force), a phenomenon termed: force ‘enslaving’. In addition, a drop in MVC during multi-finger tasks as compared to single finger tasks (force ‘deficit’) was also observed. A previously unreported phenomenon that we term: ‘preferred direction enslaving’ was also apparent; both master and slave fingers produced force in the instructed direction with a non-zero perpendicular component. Due to the architectural separation of the involved muscles, preferred direction enslaving provides strong evidence that enslaving results from neural rather than biomechanical factors. A final new phenomenon: ‘negative deficit’, or force ‘facilitation’ was observed in 46.4% of the trials in 21 out of 23 subjects during multi-finger lateral efforts and was further demonstrative of extensive interconnection among neurons serving hand muscles. The data were modeled with high accuracy (∼4% mean square error) using a linear neural network with motor ‘commands’ as inputs and finger forces as outputs. The proposed network, equivalent to linear regression, can be used to determine the extent to which finger forces are influenced by peripheral constraints during functional prehensile activities.     

Breaking the flow of an action

The present study was aimed at investigating whether the execution of a sequential action changes when the temporal contiguity between the motor steps composing it is altered. Participants were requested to reach and grasp an object and pour its contents into a container under two conditions: a ‘fluent pouring’ condition in which participants were instructed to execute the action fluently and an ‘interrupted pouring’ condition in which participants were instructed to reach and grasp the object, wait for an acoustic signal and then complete the pouring action. A ‘control’ condition in which participants were requested to reach and grasp the object without performing any subsequent action was also administered. Results indicate that movement duration and hand kinematics varied depending on the temporal relationship between the reach-to-grasp and the lift-to-pour phases. When a delay at object contact was introduced, reach duration was longer and the thumb/index abduction angle was greater than when such a delay was not introduced. These results are interpreted in light of ‘internal model’ theories suggesting that a strict temporal contiguity between the motor steps composing an action is a prerequisite for a skilful movement to be planned and executed.     

Distractor objects affect fingers’ angular distances but not fingers’ shaping during grasping

The aim of the present study was to determine whether and how hand shaping was affected by the presence of a distractor object adjacent to the to-be-grasped object. Twenty subjects were requested to reach towards and grasp a ‘convex’ or a ‘concave’ object in the presence or absence of a distractor object either of the same or different shape than the target object. Flexion/extension at the metacarpal-phalangeal (MCP) and proximal interphalangeal joints of all digits, and abduction angle between digits were measured by resistive sensors embedded in a glove. The results indicate robust interference effects at the level of reach duration and the extent of fingers’ abduction angles together with changes at the level of a single joint for the thumb. No distractor effects on individual fingers’ joints except for the MCP of the middle and little fingers were found. These findings suggest that the presence of distractor object affects hand shaping in terms of fingers’ abduction angles, but not at the level of ‘shape dependent’ fingers’ angular excursions. Furthermore, they support the importance of the thumb for the guidance of selective reach-to-grasp movements. We discuss these results in the context of current theories proposed to explain the object selection processes underlying the control of hand action.     

Non-constraining sleep/wake monitoring system using bed actigraphy

This paper introduces a new method, bed actigraphy (BACT) for user-friendly sleep-wake monitoring. BACT provides a non-intrusive acquisition of activity data, and in particular does not require that sensors be attached to the subject’s body. The system consists of four load-sensing cells supporting the bed, an A/D converter, and a microcontroller with appropriate software. The performance of BACT was compared to that of standard polysomnography (PSG) recordings and wrist-worn actigraphy (ACT). Ten normal volunteers underwent overnight PSG recordings and were examined simultaneously with BACT and ACT. An automatic scoring algorithm scored each 30-s epoch of the BACT recordings for either ‘Wake’ or ‘Sleep.’ A sleep specialist manually scored the PSG recordings, and the results were divided into ‘Wake’ and ‘Sleep’ categories. The three methods showed a significant correlation when compared with in the contingency test. The mean epoch-by-epoch agreements between the BACT and PSG, ACT and PSG, and BACT and ACT recordings were 95.2, 92.9, and 94.3%, respectively. The mean absolute differences in sleep percentage (SP) between them were 1.8 ± 0.82, 3.4 ± 1.45, and 1.9 ± 1.16 %, respectively. BACT differentiation of the ‘Wake’ and ‘Sleep’ stages proved to be sufficiently robust, and its results were comparable to PSG analysis. This finding supports the experimental and clinical value of bed-activity monitoring during sleep.     

Analysis of wavelet-filtered tonic-clonic electroencephalogram recordings

EEG signals obtained during tonic-clonic epileptic seizures can be severely contaminated by muscle and physiological noise. Heavily contaminated EEG signals are hard to analyse quantitatively and also are usually rejected for visual inspection by physicians, resulting in a considerable loss of collected information. The aim of this work was to develop a computer-based method of time series analysis for such EEGs. A method is presented for filtering those frequencies associated with muscle activity using a wavelet transform. One of the advantages of this method over traditional filtering is that wavelet filtering of some frequency bands does not modify the pattern of the remaining ones. In consequence, the dynamics associated with them do not change. After generation of a ‘noise free’ signal by removal of the muscle artifacts using wavelets, a dynamic analysis was performed using non-linear dynamics metric tools. The characteristic parameters evaluated (correlation dimension D₂ and largest Lyapunov exponent λ₁) were compatible with those obtained in previous works. The average values obtained were: D₂=4.25 and λ₁=3.27 for the pre-ictal stage; D₂=4.03 and λ₁=2.68 for the tonic seizure stage; D₂=4.11 and λ₁=2.46 for the clonic seizure stage.     

Pre-screening via sleep logs in sleep-disordered patients—Adaptational effects, yes or no?

Summary Question of the study  Sleep logs are common tools in sleep research and clinical routine. Usually sleep logs have to be completed during a 2-week period, with the first week serving as an adaptation to the instrument itself. In the present study, we investigated whether there is indeed such an adaptation bias or not. Patients and methods  A total of 236 chronically sleep-disordered outpatients completed the standardized sleep log ‘Abend-Morgen-Protokoll’ during a 2-week pre-screening period prior to the first visit in our sleep ambulance. Two sets of items were established, the ‘instrumental’ and the ‘therapeutic’ set. The respective ratings of the first and second week (week A, B) were compared to evaluate clinically relevant changes. Results  The ratings of several ‘instrumental’ items significantly differed between week A and B. However, these changes—on average—were only marginal and therefore of little clinical importance. Regarding the ‘therapeutic’ set of items, no systematic variations could be ascertained over the assessment period. Conclusion  The present investigation could not confirm the presence of adaptation biases (instrumental, therapeutic) in a large sample of chronically sleep-disordered outpatients. Therefore, we consider a 1-week pre-screening period via sleep log as sufficient for the diagnostic process in these patients.      

Ice-lithographic fabrication of concave microwells and a microfluidic network

We describe a novel method to produce concave microwells utilizing solid–liquid phase change. This method, named ‘ice-lithography’, does not require any lithographic processes and consists of a few simple steps that yield multiple concave microwells. We demonstrated that the shape and size of the microwells can be controlled by varying substrates and vapor-collection time. Patterned wells with sizes in the range of 10μm to several millimeters in diameter could be produced. Additionally, we fabricated a uniformly aligned concave microwell pattern and a microfluidic network. Ice-lithography has potential biological and biomedical applications in areas such as the fabrication of cell docking devices and microbioreactors as well as the formation of uniformly sized embryoid bodies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.