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31.
Neural classifier construction using regularization, pruning and test error estimation 总被引:1,自引:0,他引:1
Mads Hintz-Madsen Lars Kai Hansen Jan Larsen Morten With Pedersen Michael Larsen 《Neural networks》1998,11(9):1659-1670
In this paper we propose a method for construction of feed-forward neural classifiers based on regularization and adaptive architectures. Using a penalized maximum likelihood scheme, we derive a modified form of the entropic error measure and an algebraic estimate of the test error. In conjunction with optimal brain damage pruning, a test error estimate is used to select the network architecture. The scheme is evaluated on four classification problems. 相似文献
32.
Michael Sørensen M.D. Michael Bachmann Nielsen M.D. Jan Fog Pedersen M.D. Ph.D. John Christiansen M.D. Ph.D. 《Diseases of the colon and rectum》1994,37(2):138-143
PURPOSE: The aim of our study was to investigate internal anal sphincter electromyographic signals. METHODS: Electromyography of the internal anal sphincter was performed with platinum wire electrodes in six healthy volunteers (three males and three females), inserted under endosonographic guidance. Platinum wire electrodes were also inserted into the external anal sphincter. Activity of both the internal and external anal sphincter in a 40-second period was measured. RESULTS: Internal anal sphincter median activity was 22.1 (range, 5.5–67.6) μ V. Slow-wave activity was 47 cycles/minute (range, 34–55 cycles/minute). After inflation of a rectal balloon with air until a constant relaxation of the anal canal was obtained, a decrease in internal anal sphincter activity to 15.9 (1.2–31.3) μV as well as a decrease in slow-wave activity to 34 cycles/minute (range, 27–40 cycles/minute) was found. The original internal anal sphincter EMG was resumed after deflation of the rectal balloon. External anal sphincter median activity was 31 (range, 0.77–18.6)μV. During inflation of the rectal balloon, a reflex increase in external sphincter EMG activity was found. With the rectal balloon fully inflated a part of this increase was still present, 11.0 (1.9–24.6)μV. In some of the subjects, this increased activity was superimposed on the internal anal sphincter recordings as well. During a voluntary squeeze it was not possible to identify internal anal sphincter activity due to activity of the external anal sphincter totally overriding the internal anal sphincter signal. CONCLUSION: Precise EMG recordings from the internal anal sphincter is possible with endosonographic guidance of the electrodes, except during voluntary squeezing of the external anal sphincter. 相似文献
33.
The influence of physical activity on the plasma digoxin concentration was investigated in 13 digitalised patients suffering from a variety of cardiac diseases. Plasma digoxin concentration was determined four times during two consecutive days. In the morning, the standing position and one hour of physical activity caused a consistent and significant decrease in the plasma digoxin concentration, the mean reduction being 26.7 percent. In the afternoon, no consistent changes of plasma digoxin concentration were observed during one hour's rest. Consequently, we suggest standardisation of the blood sampling procedure so that no blood collection takes place in the morning until the patient has been performing normal physical activity for at least one hour. 相似文献
34.
From a group of 1,111 patients who had stapedectomy or stapedotomy performed in a 10-year period, a thorough investigation was made of 11 patients who had a total hearing loss and 8 patients who developed a partial sensorineural hearing loss after operation. The data obtained indicate that postoperative infection with influenza virus may be responsible for unexpected complications following stapedectomy. A close relation was found between the appearance of complications and periods of epidemics of influenza. 相似文献
35.
We have studied asthma mortality in Denmark from 1969 to 1988. Age standardized mortality rates calculated in three age groups, 10-34, 35-59, and greater than or equal to 60 years, disclosed similar trends. Increasing mortality from asthma in the mid-1970s to 1988 was seen in all three age groups with higher mortality in 1979-88 as compared with 1969-78 of 95%, 55%, and 69%, respectively. Since the eighth revision of the International Classification of Diseases (ICD8) was used in Denmark over the entire 20-year period, changes in coding practice due to change of classification system cannot explain the findings. 相似文献
36.
H S Jensen N Tvede M Diamant H H Mogensen M B Hansen B S Thomsen P B Pedersen K Bendtzen 《Scandinavian journal of rheumatology》1991,20(2):83-90
Synovial fluid (SF) and blood from 24 patients with non-traumatic, sterile hydarthron were examined for monocyte elastolysis (M?E) and for levels of interleukin 6 (IL-6) and of soluble interleukin 2 receptor (sIL-2R). Six patients had osteoarthrosis (OA) and 18 patients had inflammatory hydarthron (IH), 10 of whom had rheumatoid arthritis (RA). Blood M?E was lower in OA than in IH, both measured as basal M?E activity and after in vitro stimulation with immune complexes and phorbol myristate acetate (PMA). SF M?E was higher than M?E in blood (p less than 0.01). This increase in SF M?E could be mimicked in vitro by prestimulation of blood M? with low levels of IC. SF IL-6 and sIL-2R were also elevated (p less than 0.01). All three parameters correlated to the degree of joint inflammation evaluated by SF leucocyte level, complement activation, blood C Reactive Protein, and to the clinical evaluation of the joint. The increase in SF M?E, IL-6 and sIL-2R in patients with IH, points to a stimulation of M? and lymphocytes in the joint. 相似文献
37.
Antoinette MaassenVanDenBrink MSc ; Monique N. Vergouwe MSc ; Roel A. Ophoff PhD ; Pramod R. Saxena MD PhD ; Michel D. Ferrari MD PhD ; Rune R. Frants PhD 《Headache》1998,38(4):288-291
The 5-HT1 receptor agonist, sumatriptan, is highly effective in the treatment of migraine. Some patients, however, do not respond or experience recurrence of the headache. In addition, some patients report chest symptoms after sumatriptan. We investigated whether these different responses could be attributed to genetic diversity of the 5-HT1B receptor, which most likely mediates the therapeutic action and the coronary side effects of sumatriptan. Allele frequencies of two polymorphisms in the 5-HT1B receptor gene ( G861C and T-261G ) were investigated in migraine patients with consistently good response to sumatriptan (n=14), with no response (n=12), with recurrence of the headache (n=12), with chest symptoms (n=13), and in patients without chest symptoms (n=27). Allele frequencies (G:0.74; C:0.26 at nt 861 and T:0.39; G:0.61 at nt -261) did not differ between patient groups, indicating that genetic diversity of the 5-HT1B receptor does not seem to be involved in the different clinical responses to sumatriptan. 相似文献
38.
N. H. Staalsen J. M. Hasenkam J. Winther M. Ulrich E. M. Pedersen 《Heart and vessels》1993,8(4):194-202
Summary Earlier studies using hot-film anemometry in pigs have revealed skewed tangentially rotating velocity profiles in the ascending aorta during systole. The reason for this phenomenon has been postulated to be caused by the left ventricular contraction pattern. Therefore, the aim of this study was to investigate the influence of the left ventricular contraction pattern on the velocity fields in the ascending aorta of pigs. We used a 10 MHz perivascular pulsed Doppler ultrasound system to measure point blood velocities at two axial locations over the entire cross sectional area in the ascending aorta of 90 kg pigs. The axial component of the velocity profiles was visualized dynamically by computerized 3-dimensional animation techniques. Changing left ventricular contraction patterns were accomplished by reversible occlusion of either the left anterior descending or right posterior descending coronary artery. The axial development of the systolic rotating and skewed velocity profiles in the ascending aorta was described. The appearance of the systolic velocity profiles were virtually unaffected by changes in left ventricular contraction pattern.This study was kindly supported by The Danish Heart Foundation, Civilingeniør Frode Nyegaard og Hustru's Fond and NOVO's Forskningsfond 相似文献
39.
P.H. Andersen H. Vestergaard S. Lund P. Vedel S. Junker B.B. Kahn O. Pedersen 《Diabetic medicine》1993,10(8):699-706
Studies in normal man and rodents have demonstrated that the expression of the dominant glucose transporter in skeletal muscle, GLUT4, is regulated by insulin at supraphysiological circulating levels. The present study was designed to determine whether intensified insulin replacement therapy for 24 h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble insulin for 24 h the fasting plasma glucose concentration decreased from 20.8 ± 2.3 (SD) to 8.7 ± 2.3 mmol 1?1 whereas the fasting serum insulin level increased from 0.06 ± 0.02 to 0.17 ± 0.09 nmol 1?1 However, despite a 2.8-fold increase in serum insulin levels and more than a halving of the plasma glucose concentration for at least 15 h no significant alterations occurred in the amount of GLUT4 protein (0.138 ± 0.056, poor control vs 0.113 ± 0.026 arb. units, improved control, p = 0.16) or GLUT4 mRNA (96432 ± 44985, poor control vs 81395 ± 25461 arb. units, improved control, p = 0.54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients. 相似文献
40.
K Overgaard T Sereghy G Boysen H Pedersen S H?yer N H Diemer 《Journal of cerebral blood flow and metabolism》1992,12(3):484-490
The purpose of this study was the development of a model of embolic stroke with high reproducibility concerning infarct volume. In 37 male Sprague-Dawley rats, the internal carotid artery was embolized with in vitro preformed suspensions of autologous microemboli resembling arterial thrombi. With a method of continuous flow through the carotid arterial catheter, reflux of blood with uncontrolled clotting and embolization was avoided, thereby providing control animals free of ischemic damage. The embolized animals had arterial occlusions on angiograms immediately after embolization and no spontaneous recanalization on angiograms 2 h later. The cerebral blood flow measured by the intra-arterial 133Xe injection method decreased to 21-37% of baseline values. All embolized animals developed hemiparesis with spontaneous circling behavior, embolization with more than 150 microliters clot suspension resulted in hemispherical infarcts. There was a strong statistically significant correlation between amount of emboli, rate of vascular occlusion, and volume of infarcted tissue. This is the first model presented utilizing autologous in vitro microemboli imitating "white" arterial thrombi. The animals developed infarction, resembling human stroke. 相似文献