PubMed Health⌕ Search

Biomedical subjects

Peter Schreiber

Publications and source records attributed to Peter Schreiber.

3 recordsLinked to original sources

Thin compound-eye camera.

An artificial compound-eye objective fabricated by micro-optics technology is adapted and attached to a CMOS sensor array. The novel optical sensor system with an optics thickness of only 0.2 mm is examined with respect to resolution and sensitivity. An optical resolution of 60 x 60 pixels is determined from captured images. The scaling behavior of artificial compound-eye imaging systems is analyzed. Cross talk between channels fabricated by different technologies is evaluated, and the influence on an extension of the field of view by addition of a (Fresnel) diverging lens is discussed. The lithographic generation of opaque walls between channels for optical isolation is experimentally demonstrated.

Animals↗

Inflammatory C-reactive protein and cytokine levels in asymptomatic people with chronic spinal cord injury.

OBJECTIVE: To determine the relation between serologic markers of information and clinical characteristics of people with chronic spinal cord injury (SCI). DESIGN: Cross-sectional study. SETTING: Academic medical center SCI outpatient clinic. PARTICIPANTS: Convenience sample of 37 men with chronic SCI and 10 healthy control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and C-reactive protein (CRP). RESULTS: The following results achieved statistical significance at P less than .05. Asymptomatic chronic SCI patients differed from referent controls with respect to serum CRP levels but not IL-6 or TNF-alpha. In SCI patients, higher levels of CRP correlated negatively with hemoglobin and albumin levels. A longer time since injury correlated with lower TNF-alpha values, whereas higher TNF-alpha levels correlated with higher serum albumin. Pressure ulcers and indwelling urinary catheters were associated with higher mean levels of CRP but not of the cytokines TNF-alpha and IL-6. Intermittent urinary catheterization was associated with lower levels of CRP when compared with other methods of bladder management. CONCLUSIONS: Asymptomatic people with long-term SCI, especially those with indwelling urinary catheters, showed serologic evidence of a systemic inflammatory state. There was no evidence of an elevation in proinflammatory cytokines. Detection of an ongoing systemic inflammatory response in apparently healthy people with indwelling urinary catheters and small skin ulcers further supports the aggressive pursuit of catheter-free voiding options and pressure ulcer healing.

Adult↗

Artificial apposition compound eye fabricated by micro-optics technology.

By exploring micro-optical design principles and technology, we have developed an artificial apposition compound eye. The overall thickness of the imaging system is only 320 microm, the diagonal field of view is 21 degrees, and the f-number is 2.6. The monolithic device consists of an UV-replicated microlens array upon a thin silica substrate with a pinhole array in a metal layer on the back side. The pitch of the pinholes differs from that of the lens array to provide individual viewing angle for each channel. Theoretical limitations of resolution and sensitivity are discussed as well as fabrication issues and compared with experimental results. A method to generate nontransparent walls between optical channels to prevent cross talk is proposed.

Journal Article↗