Background: Endocannabinoids (ECs) are rapidly acting immune-modulatory lipid-signaling molecules that are important for adaptation to stressful and aversive situations. They are known to interact with glucocorticoids and other stress-responsive systems. Maladaptation to acute or chronic stress represents a major risk factor for the development of psychiatric disorders. In the present study, we administered stress doses of hydrocortisone in a prospective, randomized, placebo-controlled doubleblind study in patients undergoing cardiac surgery (CS) to examine the relationship between the use of glucocorticoids, plasma EC levels, and the occurrence of early postoperative cognitive dysfunction (delirium) and of later development of depression. Methods: We determined plasma levels of the ECs anandamide and 2-arachidonoylglycerol (2-AG) in CS patients of the hydrocortisone (n = 56) and the placebo group (n = 55) preoperatively, at postoperative day (POD) 1, at intensive care unit discharge, and at 6 months after CS (n = 68). Postoperative delirium was diagnosed according to Diagnostic and Statistical Manual of the American Psychiatric Association IVth Edition (DSM-IV) criteria, and depression was determined by validated questionnaires and a standardized psychological interview (Structured Clinical Interview for DSM-IV ). Results: Stress doses of hydrocortisone did not affect plasma EC levels and the occurrence of delirium or depression. However, patients who developed delirium on POD 1 had significantly lower preoperative 2-AG levels of the neuroprotective EC 2-AG (median values, 3.8 vs. 11.3 ng/ml; p = 0.03). Preoperative 2-AG concentrations were predictive of postoperative delirium (sensitivity = 0.70; specificity = 0.69; cutoff value = 4.9 ng/ml; receiver operating characteristic curve area = 0.70; 95% confidence interval = 0.54 -0.85). Patients with depression at 6 months
The objective of applying transmission holograms in automotive headlamp systems requires the adaptation of holograms to divergent and polychromatic light sources like light-emitting diodes (LEDs). In this paper, four different options to describe the scalar light waves emitted by a typical automotive LED are regarded. This includes a new approach to determine the LED's wavefront from interferometric measurements. Computer-generated holograms are designed considering the different LED approximations and recorded into a photopolymer. The holograms are reconstructed with the LED and the resulting images are analyzed to evaluate the quality of the wave descriptions. In this paper, we show that our presented new approach leads to better results in comparison to other wave descriptions. The enhancement is evaluated by the correlation between reconstructed and ideal images. In contrast to the next best approximation, a spherical wave, the correlation coefficient increased by 0.18% at 532 nm, 1.69% at 590 nm, and 0.75% at 620 nm.
Holograms have found their use as optical elements in a variety of applications. Yet using them with incoherent and divergent lightsources like LEDs proves difficult, as their characteristics need to be simulated by lasers during manufacturing to get a correct reconstruction of the desired light distribution. We present a new setup to allow for a high flexibility during the manufacturing process, which is able to produce volume holographic cell arrays (VCAs) that can be illuminated directly with uncollimated LEDs. Results are presented for the case of reflection holograms.
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