The effect of multispectral image fusion enhancement on human efficiency.

The visual system can be highly influenced by changes to visual presentation. Thus, numerous techniques have been developed to augment imagery in an attempt to improve human perception. The current paper examines the potential impact of one such enhancement, multispectral image fusion, where imagery captured in varying spectral bands (e.g., visible, thermal, night vision) is algorithmically combined to produce an output to strengthen visual perception. We employ ideal observer analysis over a series of experimental conditions to (1) establish a framework for testing the impact of image fusion over the varying aspects surrounding its implementation (e.g., stimulus content, task) and (2) examine the effectiveness of fusion on human information processing efficiency in a basic application. We used a set of rotated Landolt C images captured with a number of individual sensor cameras and combined across seven traditional fusion algorithms (e.g., Laplacian pyramid, principal component analysis, averaging) in a 1-of-8 orientation task. We found that, contrary to the idea of fused imagery always producing a greater impact on perception, single-band imagery can be just as influential. Additionally, efficiency data were shown to fluctuate based on sensor combination instead of fusion algorithm, suggesting the need for examining multiple factors to determine the success of image fusion. Our use of ideal observer analysis, a popular technique from the vision sciences, provides not only a standard for testing fusion in direct relation to the visual system but also allows for comparable examination of fusion across its associated problem space of application.

[Virtual reality in ophthalmological education]. / Virtuelle Realitäten für die augenchirurgische Ausbildung.

We present a computer-based medical training workstation for the simulation of intraocular eye surgery. The surgeon manipulates two original instruments inside a mechanical model of the eye. The instrument positions are tracked by CCD cameras and monitored by a PC which renders the scenery using a computer-graphic model of the eye and the instruments. The simulator incorporates a model of the operation table, a mechanical eye, three CCD cameras for the position tracking, the stereo display, and a computer. The three cameras are mounted under the operation table from where they can observe the interior of the mechanical eye. Using small markers the cameras recognize the instruments and the eye. Their position and orientation in space is determined by stereoscopic back projection. The simulation runs with more than 20 frames per second and provides a realistic impression of the surgery. It includes the cold light source which can be moved inside the eye and the shadow of the instruments on the retina which is important for navigational purposes.

[Importance of pre- and perinatal risk factors in respiratory distress syndrome of premature infants. A logical regression analysis of 1100 cases]. / Bedeutung von prä- und perinatalen Einflussfaktoren beim Surfactant-Mangelsyndrom Frühgeborener. Eine logistische Regressionsanalyse anhand von 1100 Fällen.

BACKGROUND: Respiratory distress syndrome (RDS) due to surfactant deficiency remains a cause of considerable mortality in the neonatal period. METHODS: In a retrospective study we analysed the records of 1109 premature newborns with a birth weight below 1500 g that were treated on our unit. RDS was assumed if the infants needed mechanical ventilation with oxygen supplementation and the typical radiological signs were present on chest x-ray. RESULTS: No changes in the incidence of RDS were found during the period of observation. Below 29 weeks gestational age 90% of infants suffered from RDS (55% severe RDS grade III or IV). The incidence was 75% (grade III or IV: 32%) for infants born at 29 and 30 weeks, 48% (grade III or IV: 15%) at 31 and 32 weeks and 33% (grade III or IV: 6%) for neonates born at 33 weeks of gestation. Using a logistic regression analysis model the following parameters were found to increase the risk for RDS significantly (p < 0.05): no prenatal steroid treatment, Cesarean section, male gender, APGAR at 5 min < 7, metabolic acidosis (base excess < or = -6 mval) and rectal temperature < 36 degrees C on admission. Following gestosis, insufficiency of the placenta and premature rupture of membranes a decrease in the incidence of RDS was observed. CONCLUSION: We conclude that although some risk factors for RDS will be difficult to exclude (e.g. maternal disease, gender) the incidence and severity of RDS can be reduced by measures like maternal antenatal steroid treatment. Perinatal asphyxia (low APGAR values and/or acidosis) and hypothermia should be avoided, as these conditions increase the relative risk for developing RDS.

Detection of Legionella DNA in human and guinea pig urine samples by the polymerase chain reaction.

A detection system for Legionella DNA in urine samples based on the polymerase chain reaction (PCR) was developed and tested on infected guinea pigs and patients suffering from pneumonia. Results were compared with standard methods for diagnosis of Legionnaires' disease. A primer system was selected which amplifies a 108 bp DNA fragment of the 5S rRNA gene. The sensitivity of the PCR system was one femtogram of extracted Legionella DNA. Three methods were tested for pretreatment of urine samples. Of these, the Geneclean II kit (Bio 101, USA) gave the best results for artificially contaminated urine samples as well as those from infected guinea pigs or patients. Thirty-seven urine samples from 15 guinea pigs intraperitoneally infected with either Legionella pneumophila serogroup 1, 3 and 6 or Legionella micdadei, 26 urine samples of 21 patients suffering from pneumonia, and 30 control samples of patients with urinary tract infection (UTI) were tested. Legionella DNA was detected in 29 of the guinea pig urine samples; whereas, urinary antigen detection using EIA was positive in only 20 of the samples. PCR was also positive in the samples of 11 patients with pneumonia, 9 of which were confirmed by other microbiological methods, such as culture, direct fluorescent antibody test, urinary antigen detection and antibody testing. However, of the 30 control samples from patients with UTI, three samples yielded positive results. The results demonstrate that Legionella DNA is excreted in the urine of infected individuals and that the PCR shows a higher degree of sensitivity than EIA to the detection of soluble Legionella antigen in urine.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mortality of premature infants 1980-1990: analysis of data from the Göttingen perinatal center]. / Mortalität unreifer Neugeborener von 1980-1990: Analyse aus dem Perinatalzentrum Göttingen.

We analyzed retrospectively (1980-1990) the causes of death and by using a logistic regression model the perinatal and neonatal risk factors influencing the mortality in preterm infants < 34 weeks of gestation (n = 1132). When comparing the interval from 1980-1986 to 1987-1990 we observed a decreasing mortality in infants < or = 1000 g from 57% to 19% as well as in the preterm infants > 1000 g from 8.3% to 3.0% (p < 0.001). The causes of death changed considerably. During 1980-1986 fifty-two (8.2%) out of the 632 preterm infants and during 1987-1990 only seven (1.3%) out of the 600 preterm infants died in the course of a severe respiratory distress syndrome or intracranial hemorrhages. From 1980 to 1986 21% (n = 10) and from 1987 to 1990 77% (n = 10) of the neonatal deaths in preterm infants > 1000 g were attributed to lethal malformations. In those infants without lethal malformations (n = 1109) we performed a logistic regression analysis. 87 (7.8%) of these neonates died. The risk of dying was significantly higher in infants born before 1987, in male newborns and in infants suffered from a severe respiratory distress syndrome III-IV or septicemia (p < 0.0001). An increasing gestational age of one week resulted in a lowered risk of mortality (odds ratio 0.59, p < 0.0001). Adjusted for these basic variables the mortality risk was also significantly higher for birth weights < or = 1000 g, low Apgar scores, peripartal acidosis, hypothermia and intracranial hemorrhages. An intrauterine growth retardation < 10. percentile resulted in a lower mortality risk.