Strategic control and medial frontal negativity: beyond errors and response conflict

Errors in timed choice tasks typically produce an error-related negativity (ERN) in the event-related potential (ERP). The error specificity of the ERN has been challenged by studies showing a correct response negativity (CRN). Forty-five participants engaged in a flanker task in which both compatibility between flankers and target and the probability of compatible flankers were manipulated. Correct responses elicited a CRN, the amplitude of which increased with the degree of mismatch between the presence of conflict and conflict probability, even on low-conflict (compatible) trials. The fronto-central N2 component was larger on high-conflict (incompatible) correct response trials. However, in contrast to some recent accounts, this N2 was largest for highly probable stimuli. These findings suggest revision to models of the effects of conflict on response-related negativity to account for strategic adjustments made in preparation for the response.     

Hyperglycemic and Hyperosmolar Responses to Graded Hemorrhage

Changes of the arterial plasma osmolality and of the glucose concentration were followed during a 30 min period of graded hemorrhagic hypotension (80, 50, and 30 mmHg) in the cat. Bleeding evoked a significant plasma hyperosmolality at all three hypotension levels and the responses were quantitatively related to the degree of hypotension. An approximate steady state increase in the arterial plasma osmolality was reached about 20 min after the start of the bleeding and it then averaged 8, 20, and 25 mOsm/kg H₂O at 80, 50, and 30 mmHg, respectively. Bleeding also evoked an increase in the plasma glucose concentration, which almost entirely accounted for the observed hyperosmolality, especially at 80 and 50 mmHg. In late stages of hypotension at 30 mmHg, elevated plasma lactate and potassium concentrations contributed to the overall hyperosmolality. — Previous hemorrhagic hypotension experiments at 50 mmHg (Järhult 1975 b) have shown that hyperosmolality serves as an important regulator of the plasma and extracellular fluid volumes during bleeding. The present results indicate that such an osmolar compensatory mechanism is operating over wide ranges of hemorrhagic hypotension.     

Thermogenesis due to noradrenaline in muscles under different rates of perfusion

Vascularly isolated hind legs of cold acclimated rats were perfused with arterial blood either without noradrenaline (NA) or with a constant concentration of NA (10 ng·ml^–1) at different perfusion rates ranging from 2 to 14l·g^–1·min^–1. The oxygen consumption of the leg during perfusion both with or without NA was linearly related to the perfusion rate. The linear increase of leg oxygen consumption with respect to the perfusion was steeper after NA, which indicates that the same arterial concentration of NA may produce a greater thermogenic effect at higher blood flow rates (the difference between resting metabolic rate and the thermogenesis stimulated by NA, was 8.20 l O₂·g^–1·h^–1 at a blood flow of 3l·g^–1·min^–1, compared with 45.02 l O₂·g^–1·h^–1 at a blood flow of 14 l·g^–1·min^–1). These data confirm the important role of the extravascular influx rate of NA in the control of thermogenesis due to NA in muscles.     

Sensory-feedback system compatible with myoelectric control

Progress in the development of a system to provide sensory feedback of the pinch force of an artificial hand is described. Design criteria relating to electrocutaneous stimulation and compatibility with myoelectric control are discussed. Details of a practical system, presently in use by two amputees prior to full-scale clinical evaluation, are presented.     

Effect of accuracy constraint on joint coordination during pointing movements

Given the number of muscles and joints of the arm, more ways are available to produce an identical hand movement when pointing to a target than are strictly necessary. How the nervous system manages these abundant degrees of freedom was the focus of this study of pointing to targets of low and high indices of difficulty (ID). Two essential features of movement synergies were examined. The first reflects the preferred relations among the outputs of each movement element and was studied through principal component analysis. The second feature of synergy reflects the flexibility of those relationships evidenced by the use of multiple, goal-equivalent solutions to joint coordination. This second feature, which is the main focus of this report, was studied using the uncontrolled manifold approach. Motor abundance was defined operationally as the component of variance of joint combinations that left unchanged the value of important performance variables (goal-equivalent variability, GEV). This variance component was contrasted with the component of variance leading to a change in the value of these variables (non-goal-equivalent variability, NGEV). The difference between GEV and NGEV was evaluated with respect to the performance variables movement extent, movement direction, and path of the arm's center of mass. More than 90% of the variance of joint motions across the pointing trial were accounted for by one principal component, indicating a consistent temporal coupling among most joint motions in a single functional synergy. The flexible nature of this synergy was revealed by the variability analysis. All subjects had significantly higher GEV than NGEV for most of the movement path. Thus, variable patterns of joint coordination did not represent noise but the use of equivalent coordinative solutions related to stabilizing important performance variables. Higher GEV than NGEV was present regardless of the task's ID. One exception was at the time of peak velocity, leading to poorer control of movement extent than movement direction. Increasing the task's ID led to an overall reduction of joint configuraion variance, particularly GEV. These results support earlier work indicating that the use of goal-equivalent solutions to joint coordination is a common feature of the control of this and many other motor tasks. Functionally important performance variables appear to be controlled through flexible but task-specific coordination among the motor elements Electronic Publication     

Chemical,radiochemical, and radionuclide purity of eluates from different commercial fission99Mo/99mTc generators

Seven⁹⁹Mo/^99mTc generators (using fission⁹⁹Mo) obtained from seven different manufactures were studied in 1984 and 1985 to test the quality of the eluates. We present the findings concerning the elution efficiency, radionuclide purity,⁹⁹Mo breakthrough, radiochemical purity, pH, and aluminium content of the eluates. One generator was overloaded with⁹⁹Mo by about 40%, while one generator had^99mTc yields of only about 80%. The eluates generally (although with some exceptions) exhibited a high and satisfactory radionuclidic purity and good radiochemical purity. The low-level determination of⁹⁹Mo break-through using a commercially available dose calibrator with a⁹⁹Mo assay shiled indicated a misleadingly high⁹⁹Mo content. All of the eluates had pH values of between 5.0 and 5.5, and the aluminium content was always below the detection limit of 1 g per milliliter of eluate. The generators performed well and proved their capability of functioning as reliable sources of sodium pertechnetate Tc99m. In all cases, the pertechnetate produced met the requirements of the European Pharmacopeia.This report is based on work conducted within the scope of a research poject devised by the Ministry of the Interior of the Federal Republic of Germany (Hammermaier et al. 1985). The present report reflects the opinions of the authors and does not necessarily express the views of the Federal Ministry of the Interior     

Reflections on experimental and human pathology of aggression

On the basis of the already proposed distinction between "normal" and "pathological" aggression in laboratory animals, it is essayed an integration of the experimental findings derived from a specific animal model of aggression with the available clinical information on human violent behavior. The too disregarded importance of the role played by the inhibitory control of brain functions, appears instead reportedly essential in the regulation of emotions and behavior, and is of great relevance in explaining the behavioral changes that follow induced or spontaneous impairment of the serotonergic system of the brain. As a matter of fact, the numerous evidences indicate that genetic predisposition and induced or acquired defects of serotonergic inhibitory control greatly concur to precipitate anomalous strong aggression. Interestingly, the cluster of symptoms presented by laboratory rats in consequence of the serotonergic discontrol, has many unexpected similarities with several pathological conditions of man. This fact confers to laboratory experiments the value of a tool aimed at a better understanding of the biological mechanisms which underlie corresponding alterations of human conduct, with special reference to pathological aggression and violence. In this line, some specific nutrient defects and/or malabsorption conditions can be important in the facilitation or elicitation of mental illness including human aggression. In addition, the efficacy and neurochemical action of those substances capable to partially or completely block or prevent experimental aggression, will likely assume equal relevance in the management or prevention of human violent behavior.     

基于HART协议的实时设备管理系统

讨论了基于HART协议智能设备的实时管理系统,介绍了HART协议的基本规范,以及如何利用已有集散控制系统（DCS）和工厂信息网络的集成实现实时信息共享,取得了良好的实际效果。     

Palliative medicine and end of life care in surgery

Surgeons are privileged to offer treatments that often cure disease. Optimizing comfort for those who cannot be cured is also a core part of every clinician's duty: surveys repeatedly tell us that when death is approaching, people value quality of life above length of survival. Recognizing when someone is dying can be difficult. Tools exist to help; it is worth noting that emergency presentation with life-threatening symptoms can be a marker of poor prognosis. Clear, effective communication is crucial: understanding the patient's perspective and expectations is vital before attempting to offer information that allows future care planning. Judicious use of surgery combined with careful prescribing will optimize comfort, allowing the patient to live as well as possible for as long as possible. Anticipatory prescribing includes opioid, anti-emetic, anti-secretory and sedative medication. Attention should also be given to care of the bereaved. Generalists should understand when to refer to specialist palliative care and remember that reflecting on care when someone has died can be beneficial for professional wellbeing.