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  • 1.
    Halilovic, Armin
    KTH, School of Technology and Health (STH), Naturvetenskapliga avdelningen (Closed 20130701).
    Oscillation and multilinear Stieltjes integral2001In: Glasnik Matematicki - Serija III, ISSN 0017-095X, E-ISSN 1846-7989, Vol. 36(56)(, no 1, 17-31 p.Article in journal (Refereed)
    Abstract [en]

    In this note we consider oscillation of regulated functions.

    We improve and simplify the proof of the existence theorem for multilinear

    Stieltjes integral in the Riemann-Stieltjes and Moore-Pollard sense and

    introduce multilinear Henstock-Kurzweil-Stieltjes integral.

  • 2.
    Hjalmarsson, Håkan
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Lindqvist, Kristian
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Identification of performance limitations in control2001In: 2001 European Control Conference, ECC 2001, IEEE conference proceedings, 2001, 1446-1451 p.Conference paper (Refereed)
    Abstract [en]

    Non-minimum phase zeros and poles of a process put upper and lower constraints on the bandwidth of a closed loop system. It is thus of great interest to be able to identify these quantities. In this contribution it is shown that non-minimum phase zeros and unstable poles can be identified using high order models without the standard o(n) (n is the model order) variance penalty for over modeling. An asymptotic, in the model order and the number of data, expression for the variance of non-minimum phase zeros is derived. This result shows that the problem of determining the performance limits of a system from experimental data is considerably easier than identifying the complete system. As a direct application of this an optimal experiment design problem for identification of performance limits is posed and solved.

  • 3. Jidéus, L
    et al.
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics.
    Stridsberg, M
    Nilsson, L
    Blomström, P
    Blomström-Lundqvist, C
    Diminished circadian variation in heart rate variability before surgery in patients developing postoperative atrial fibrillation.2001In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 35, no 4, 238-44 p.Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To evaluate the role of the autonomic nervous system for the development of atrial fibrillation (AF) after coronary artery bypass surgery.

    DESIGN: Eighty patients without a previous history of AF were included. The sympathetic and parasympathetic activity were evaluated by the analysis of heart rate variability (HRV) in the frequency domain from 24-h Holter recordings and by measuring neuropeptides (neuropeptide Y, chromogranin A, chromogranin B, and pancreatic polypeptide (PP)) and catecholamines, obtained pre- and postoperatively.

    RESULTS: Preoperatively, patients (36.3%) developing AF postoperatively showed a statistically significant less circadian variation in the HRV variables, the high-frequency (HF) component (p = 0.013) and the low-frequency (LF)/HF ratio (p = 0.007), than patients remaining in sinus rhythm. The HF component and PP. both reflecting parasympathetic activity, and all other variables in the frequency domain, decreased significantly after surgery in both patient groups (p < 0.0001). Although catecholamines increased significantly postoperatively in both patient groups, neither catecholamines nor neuropeptides expressing sympathetic activity, differed between the two groups. PP was, however, significantly higher in patients with postoperative AF than in those with sinus rhythm postoperatively on day 1.

    CONCLUSION: The diminished circadian variation in HRV before surgery and the indirect signs of a higher parasympathetic activity in patients developing postoperative AF compared with patients remaining in sinus rhythm, may indicate a propensity for AF.

  • 4. Jidéus, L
    et al.
    Joachimsson, P O
    Stridsberg, M
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics.
    Tydén, H
    Nilsson, L
    Blomström, P
    Blomström-Lundqvist, C
    Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation.2001In: Annals of Thoracic Surgery, ISSN 0003-4975, E-ISSN 1552-6259, Vol. 72, no 1, 65-71 p.Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG).

    METHODS: Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively.

    RESULTS: Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients (p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine (p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y (p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery (p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients (p = 0.004 versus p = 0.86).

    CONCLUSIONS: TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.

  • 5.
    Kleiven, Svein
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    CONSEQUENCES OF BRAIN SIZE FOLLOWING IMPACT IN PREDICTION OF SUBDURAL HEMATOMA EVALUATED WITH NUMERICAL TECHNIQUES2001In: IRCOBI (International Research Council on the Biokinetics of Impacts), 2001, 161-172 p.Conference paper (Refereed)
  • 6.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Computer-aided risk assessment: Claims data as expert system support for industrial safety management2001In: Safety In Action Conference: Invited paper / [ed] Safety Institute of Australia Ltd, 2001Conference paper (Refereed)
  • 7.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Pulverization of Risk - Privatization of Trauma2001Conference paper (Refereed)
  • 8.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    The Swedish Example2001In: : Invited paper / [ed] Victorian WorkCover Corporation, Melbourne, 2001Conference paper (Refereed)
  • 9.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Bråfelt, Olle
    IPSO Classification&Control, Sweden.
    Astervik, Magnus
    IPSO Classification&Control, Sweden.
    Knutsson, Eric
    IPSO Classification&Control, Sweden.
    Prevention of injury associated with rotating action machines2001In: Safety Science Monitor, ISSN 1443-8844, Vol. 5, no 1Article in journal (Refereed)
    Abstract [en]

    BACKGROUND

    Repeated analyses of the Swedish national workers’ compensation claims data material in the Occupational No-Fault Liability Insurance Scheme have pointed to the high incidence of severe hand injury associated with getting caught in rotating (drilling, milling, boring, turning, grinding) machines in the metal manufacturing and engineering industry (Jedeskog & Larsson, 1988; Larsson, 1990; Persson, 1992).

    In an analysis of all permanently disabling injuries sustained in the Swedish engineering industry during 1986, six out of ten injuries associated with machines for drilling, boring and threading were caused by the operator getting caught in the rotating tool or work-piece with his/her glove or other garment (Larsson, 1990).

    In a repeated analysis of the national claims data material from the Swedish engineering industry for the years 1987, 1988 and 1989, half of all injuries sustained at the same types of rotating machines were due to glove getting caught in the rotating action (Persson, 1992).

    A development project aimed at reducing the risk of traumatic hand injury associated with rotating action machines was initiated in 1994 by the Institute for Human Safety and Accident Research (IPSO), in co-operation with the Swedish Institute of Production Engineering Research. The main focus of the work has been to develop an improved solution to emergency braking and to drastically reduce inertia rotation in the relevant machine types.

  • 10. Rose, Linda
    et al.
    Ortengren, R
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics.
    Endurance, pain and resumption in fully flexed postures.2001In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 32, no 5, 501-8 p.Article in journal (Refereed)
    Abstract [en]

    In this study effects of low loads in fully flexed postures were investigated. Thirteen men who were unused to the postures participated. Thirteen professional construction workers with long experience of suchlike postures were also studied. Pain reactions during and after loading were observed, as well as endurance time and the recovery process, here by studying the resumption time. Endurance and resumption times differed little from those given by models used for more common postures. Pain from the legs and not from the back limited the working ability in 86% of the endurance tests. Thirdly, the construction workers had significantly longer endurance time and shorter resumption time.

  • 11. Spaak, J
    et al.
    Sundblad, Patrik
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Linnarsson, D
    Impaired pressor response after spaceflight and bed rest: evidence for cardiovascular dysfunction.2001In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 85, no 1-2, 49-55 p.Article in journal (Refereed)
    Abstract [en]

    We hypothesized that impaired cardiovascular responses to isometric muscle action contribute to the cardiovascular deconditioning that occurs after space flight (SF) and head-down-tilt bed rest (HDT). Six subjects were studied before, during and after 120 days of -6 degrees HDT, and four subjects were studied before, during (two subjects) and after 179-389 days of SF. Subjects performed a sustained handgrip (SHG) at a force equivalent to 30% of maximum contraction force for 2 min, and heart-rate (HR) and pressor (mean arterial pressure, deltaMAP) responses were recorded. At the same relative force, both deltaHR and deltaMAP were significantly reduced during the first days after HDT (-54%, P<0.05 and -43%, P<0.05). In two subjects studied within 24 h after their return from SF, deltaMAP was practically absent (-79%, P<0.05) whereas in four subjects studied 1-4 days after return from SF, deltaMAP was reduced by 35% (P<0.05). deltaHR was not significantly changed. Our finding of attenuated pressor responses to SHG after HDT and SF supports the notion of impairments at both the neurocirculatory control and effector organ levels.

  • 12. Storck, N
    et al.
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics.
    Lindblad, L
    Jensen-Urstad, M
    Automatic computerized analysis of heart rate variability with digital filtering of ectopic beats.2001In: Clinical Physiology, ISSN 0144-5979, E-ISSN 1365-2281, Vol. 21, no 1, 15-24 p.Article in journal (Refereed)
    Abstract [en]

    Analysis of heart rate variability (HRV) has been used in studies of autonomic function and risk assessment in different patient groups such as in patients with diabetes mellitus, after myocardial infarction (MI) and other cardiovascular disease. Ectopic beats can, however, interfere with HRV analysis and give erroneous results. We have therefore studied the impact of ectopic beats on HRV analysis and the ability of a filter algorithm to correct this. Power spectral analysis of synthetic data with an increasing proportion of ectopic beats and 24-h Holter recordings from 98 healthy subjects and 93 post MI patients was done with and without digital filtering and interpolation of errors in the data stream. The analysis of HRV was seriously hampered by less than 1% of ectopic beats. A filter algorithm based on detection and linear interpolation of ectopic beats and other noise in the data stream corrected effectively for this in the synthetic data employed. In the healthy subjects and the post MI patients, filtering markedly reduced the extra variability related to non-normal beats. The software could automatically analyse over one hundred 24-h files in one batch. HRV analysis should include filtering for ectopic beats even with a small number of such beats. It is possible to make a fast analysis automatically even in huge clinical series, which makes it possible to use the method both clinically and in epidemiological studies.

1 - 12 of 12
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