Accurate, nondifferential, curve-fitted, self-referenced optical rotation polarimeter.

We describe a new method for the accurate measurement of optical rotation. It is based on curve-fitting the signal of a new optical rotation polarimeter that we have recently developed. The calculated accuracy ($\sim{80}\,\,\unicode{x00B5} ^\circ $∼80µ∘), and precision ($\sim{220}\,\,\unicode{x00B5} ^\circ )$∼220µ∘) are potentially useful for various applications in the fields of biomedical devices and analytical chemistry.

Self-referenced, microdegree, optical rotation polarimeter for biomedical applications: an analysis.

We comprehensively analyze the performance of a type of optical rotation (OR) polarimeter, which has been designed from the outset to fit the special requirements of two major applications: general chiral detection during the separation of optical isomers by high-pressure liquid chromatography systems in the pharmaceutical industry, and monitoring of glucose in the interstitial fluid of diabetics by a fully implanted long-term optical sensor. Both very demanding applications call for an OR polarimeter that can be miniaturized while maintaining high resolution and accuracy in the microdegree range in the face of considerable noise from various sources. These two characteristics­miniature size and immunity to noise­set this polarimeter apart from the traditional OR polarimeters currently in use, which are both bulky and very susceptible to noise. The following detailed analysis demonstrates the advantages of this polarimeter and its potential as an analytic and diagnostic tool.

Compact, high-resolution, self-referenced, optical activity polarimeter for high-pressure liquid chromatography systems.

Optical rotation (OR) polarimeters measure only the OR of a linearly polarized wave vector caused by the optical activity of the measured material. Such polarimeters are used to detect optically active materials and measure their concentration. Here we describe a novel type of high-resolution OR polarimeter. The new polarimeter is a compact device, based on a combination of two novel mechanisms: a referencing mechanism and an optical signal-gain mechanism. The patented referencing mechanism allows accurate measurements of small ORs in the presence of considerable polarization noise. The current limit of detection of the polarimeter is ∼20 micro-degrees, which we believe can be lowered further. The polarimeter is intended to serve as an add-on detector for existing high-pressure liquid chromatography (HPLC) systems in the pharmaceutical industry. The need for such a polarimeter, its optical setup, analysis of its performance, and experimental results are hereby given and discussed.

Risk factors for the development of posttraumatic stress disorder following combat trauma: a semiprospective study.

OBJECTIVE: When positioned in a combat situation, soldiers may be subjected to extreme stress. However, only a few combat-exposed soldiers develop long-term disturbance, namely, posttraumatic stress disorder (PTSD). This study aimed to explore risk factors for developing PTSD in order to improve the psychiatric screening process of new recruits. METHOD: In a semiprospective design, we compared 2,362 war veterans who developed PTSD (according to DSM-IV criteria) with an equal number of war veterans who did not develop PTSD. Controls were matched on the basis of sequential army identification numbers, that is, the soldier drafted immediately after the index PTSD veteran (usually on the same day). This method ensured similar demographic variables such as socioeconomic level and education. Data were collected from the Israeli Defense Force database and used in a comprehensive survey conducted between January 2000 and March 2001. Comparisons were made on predrafting personal factors (behavioral assessment, cognitive assessment, linguistic ability, and education) and pretrauma army characteristics (ie, rank and training). RESULTS: Neither behavioral assessment nor training were found to predict PTSD. The predictive factors that were found were essentially nonspecific, such as cognitive functioning, education, rank, and position during the trauma, with little effect from training. CONCLUSIONS: In an armed force that uses universal recruitment, carefully structured predrafting psychological assessment of social and individual qualifications (including motivation) failed to identify increased risk factors for PTSD. However, nonspecific factors were found to be associated with an increased risk for PTSD. This study suggests that the focus of future research on risk factors for PTSD should incorporate other domains rather than behavioral assessment alone. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00229359.