Biomedical subjects

Gert Andersson

Publications and source records attributed to Gert Andersson.

5 recordsLinked to original sources

PubMed2006

Replication of continuous-profiled micro-optical elements for silicon integration.

A novel scheme for the integration of diffractive optical elements onto silicon is presented. The processing is made in reverse order, meaning that the process of structuring the optical elements on the wafer precedes the silicon microstructuring. The first processing step on the wafer is the hot embossing of the optical microstructures into an amorphous fluorocarbon polymer spin coated on the wafer. The cured polymer forms a highly stable material with excellent optical properties. The remaining silicon processing is thus performed with the diffractive optical elements already in place. Two different diffractive structures were used in the development of the method-a (Fresnel) lens with a rather low f-number and a diffractive element producing a fan-out of a large number of paraxial beams.

Journal Article↗

PubMed2005

Multifocal visual evoked potentials--a method study of responses from small sectors of the visual field.

OBJECTIVE: A method study of the mfVEP technique to establish a standardised way to identify stable response components from small areas in all parts of the visual field and a test-retest reliability study. METHODS: MfVEP was recorded from 26 healthy volunteers. RESULTS: Two response components could be clearly identified. The latencies corresponded to those of the traditional VEP response (N75 and P100). The visual field was divided into 12 sectors. A characteristic pattern was obtained. Component I was mainly negative in the upper sectors and positive in the lower sectors. Component II was positive in the upper sectors and negative in the lower ones. Most of the sectors with missing responses were the ones adjacent to the horizontal meridian, corresponding to the phase reversals. In a test-retest reliability study, the amplitude and latency measurements of the second test were plotted against those of the first test. Correlation coefficients between 0.84 and 0.93 were obtained. CONCLUSIONS: The mfVEP allows a reliable quantification of two response components from small parts of the visual field. SIGNIFICANCE: This paper suggests that mfVEP could be a valuable supplement to the traditional VEP for exploring restricted parts of the visual pathways.

Adult↗

PubMed2004

Effects of short-term cycling on knee joint proprioception in ACL-deficient patients.

It has previously been shown that knee injuries with ACL ruptures may lead to decreased proprioception and that exercise in a normal population, uninjured individuals, may reduce the proprioceptive ability. How proprioception is affected by exercise in patients with ACL deficiency has, to our knowledge, not been studied before. Knee joint proprioception was estimated in 36 patients, 18 males and 18 females, with ACL deficiency by measuring thresholds for detection of slow passive motion before and after a short period of exercise on an ergometer bicycle. In addition, the results were compared with a control group of 24 individuals of the same age. We found trends of enhanced proprioception towards extension in the patient group after cycling, but not in the control group. Towards flexion, both groups showed poorer proprioception after cycling. When difference scores of proprioceptive change in each group were compared, a trend towards different reaction upon cycling between the groups was seen in measurement towards extension from 20 degrees where the patients seemed to improve proprioception, which the controls did not. The results are not conclusive in this pilot study, but the possibility that ACL-deficient patients and controls may not react likewise to cycling, as regards their proprioceptive ability, is discussed.

Adolescent↗

PubMed2004

Knee joint proprioception in ACL-deficient knees is related to cartilage injury, laxity and age: a retrospective study of 54 patients.

BACKGROUND: ACL-deficient patients have been found to have proprioceptive defects, but the cause of these defects has not been identified nor has the relationship between proprioception and subjective function, laxity, activity level and age been adequately studied. PATIENTS AND METHODS: Therefore, we analyzed proprioception, defined as the threshold to detect a slow passive motion (TTDPM), in relation to activity level, laxity, meniscal injuries, collateral ligament injuries, cartilage injuries, age and subjective function in 54 patients with a previous ACL rupture. We used multiple pair-wise correlation analyses, followed by a stepwise linear regression model. RESULTS: We found that poorer proprioception was related to lateral cartilage lesions, increased laxity and older age while a high activity level before injury was related with better proprioception after injury. The results also suggest a relation between proprioception and subjective knee function. INTERPRETATION: Anatomical injuy classification may need to be considered when discussing proprioceptive ability in patients with an ACL injury, laxity is related to proprioception and proprioception may decrease with age.

Adolescent↗

PubMedDate not supplied

Effects of short-term cycling on knee joint proprioception in healthy young persons.

BACKGROUND: Criteria are needed for measuring the effects of exercise and fatigue on proprioception. PURPOSE: To measure knee joint proprioception in healthy subjects before and after exercise and to establish a reference for further comparisons of patients with knee injuries. STUDY DESIGN: Controlled laboratory study. METHODS: We tested proprioception in the knees of 24 healthy subjects with a mean age of 24 years and median Tegner score of 5. Subjects were tested to estimate their thresholds for detecting slow passive motion, from starting positions of 20 degrees and 40 degrees before and after cycling on an ergometer bicycle until the pulse rate reached a steady state level and they reached a score of 14 to 17 on Borg's Ratio of Perceived Exertion scale. RESULTS: After cycling, significantly higher threshold values were found for perception of movement toward flexion from both 20 degrees and 40 degrees. No significant differences were seen in measurements of movement toward extension. CONCLUSIONS: Knee joint proprioception seems to be impaired by exercise or training. CLINICAL RELEVANCE: This impairment may lead to defective dynamic stabilization of the joint, leading to an increased risk of injuries.

Adult↗