High-angular-resolution interferometric backscatter meter.

Backscatter limits many interferometric measurements, including gravitational wave detectors, by creating spurious interference. We describe an experimental method to directly and quantitatively measure the backscatter interference. We derive and verify experimentally a relation between backscatter interference, beam radius, and the scattering sample bidirectional reflectance distribution function. We also demonstrate that our method is able to measure backscatter from high-quality optics for angles as low as 500µ r a d with an angular resolution of 160µ r a d.

Alignment sensing and control for squeezed vacuum states of light.

Beam alignment is an important practical aspect of the application of squeezed states of light. Misalignments in the detection of squeezed light result in a reduction of the observable squeezing level. In the case of squeezed vacuum fields that contain only very few photons, special measures must be taken in order to sense and control the alignment of the essentially dark beam. The GEO 600 gravitational wave detector employs a squeezed vacuum source to improve its detection sensitivity beyond the limits set by classical quantum shot noise. Here, we present our design and implementation of an alignment sensing and control scheme that ensures continuous optimal alignment of the squeezed vacuum field at GEO 600 on long time scales in the presence of free-swinging optics. This first demonstration of a squeezed light automatic alignment system will be of particular interest for future long-term applications of squeezed vacuum states of light.

[The assessment and clinical significance of heart rate variability]. / Metody oceny i znaczenie kliniczne zmiennosci rytmu zatokowego.

Heart rate variability (HRV) is a phenomenon to generation through the sinus node consecutive impulses in the different succession. HRV is regarded as a marker of autonomic nervous system tone of the heart. To assess HRV following methods: time domain, frequency domain and non-linear analysis are known. Time domain parameters correlate with frequency domain parameters. Some parameters can be used substitution, particularly reflect parasympathetic activity: rMSSD, pNN50 and HF. In clinical practice the most useful is time domain analysis based on 24-hours ecg Holter monitoring. Among time domain parameters the most significant prognostic value has SDNN. Decreased HRV following many diseases has been described. Significant prognostic value of decreased HRV after myocardial infarction (MI) and in patients with chronic heart failure (CHF) has been proved. Decreased HRV after MI is independent as well as ejection fraction (EF) sudden cardiac death risk factor. In patients with SDNN value below 50 ms high risk of cardiac death is observed. SDNN should be estimated on 7th day of MI to evaluate patients with high risk of sudden cardiac death. In patients after MI with ventricular tachycardia (VT) before VT decreased HRV is described. During MI beneficial influence of infarct-related artery patency on HRV is observed. HRV correlates with EF and infarct site too. HRV in patients with CHF correlates with EF and functional severity of CHF. Correlation between decreased HRV and increased mortality in CHF has been shown. In diabetic patients decreased HRV is observed. Following diabetes examination of HRV is useful to estimate early phase of autonomic neuropathy. Increase HRV parameters is observed in the course of beta-adrenolytic and converting enzyme inhibition treatment. In other diseases, including heart transplantation prognostic value of HRV and its clinical significance are still investigated.

Effect of enflurane on selected neuropeptides and marker enzymes in rabbit brain.

The aim of this study was to evaluate the effect of 5-, 15-, and 60-min enflurane anesthesia on the levels of Met-enkephalin, Leu-enkephalin and neuropeptide Y in discrete areas of the rabbit brain. We also evaluated the effect of enflurane anesthesia on energetic, transport and catabolic processes by measuring the activities of succinate dehydrogenase, magnesium-dependent adenosine triphosphatase and acid phosphatase in the rabbit striatum and hypothalamus. Induction of anesthesia (5 min) decreased Met-enkephalin levels in the hypothalamus and striatum, and increased them in the hippocampus and mesencephalon. Induction of anesthesia increased Leu-enkephalin levels in all brain areas studied, except for the striatum, and increased neuropeptide Y content in the hippocampus. 15- and 60-min enflurane anesthesia increased Met-enkephalin content in the hypothalamus and hippocampus. After 15- and 60-min anesthesia, and after cessation of anesthesia, Leu-enkephalin levels were increased in the hypothalamus and mesencephalon, and were decreased in the striatum and hippocampus. In the striatum, neuropeptide Y content was significantly decreased during anesthesia and after cessation of anesthesia. Histochemical analysis revealed that enflurane enhanced ATP production, catabolic processes, and the rates of exchange and transport of energetic substrates in the striatum and hypothalamus. In conclusion, enflurane affects the levels of Met, Leu-enkephalins and NPY in a manner depending on the duration of anesthesia and the brain structure. Compared with isoflurane , which was studied in our previous study enflurane produces stronger alterations in the activities of enzymatic marker in the rabbit brain. This suggests that enflurane may be less safe than isoflurane.

Influence of isoflurane on enkephalin levels and on some indicatory enzymes in the central nervous system of rabbits.

The objective of this study was to analyse the effects of isoflurane anesthesia (lasting for 15 or 60 min) and isoflurane anesthesia termination (after 1 or 24 h) on met-enkephalin (MENK) and leu-enkephalin (LENK) levels in discrete brain areas and spinal cord segments in rabbits. Moreover histochemical analysis of activities of succinate dehydrogenase, magnesium-dependent adenosine triphosphatase (Mg++ATP-ase) and acid phosphatase in the striatum and hypothalamus were carried out to evaluate the effects of isoflurane anesthesia on energetic, transport and catabolic processes. Throughout anesthesia (15 and 60 min) and after its termination (1 h) the LENK contents were increased in hypothalamus, hippocampus, mesencephalon and lumbar segment of spinal cord. Moreover, during isoflurane anesthesia and after its termination (1 h) MENK and LENK levels decreased in cervical segment and MENK content dropped in thoracic segment of spinal cord. Histochemical data indicated, that isoflurane enhanced energetic processes as well as exchange processes in neurocytes, glial cells, capillary walls and ependymal cells of the third ventricle. Measurements of acid phosphatase activity provided evidence of no signs of toxicity of isoflurane in the examined areas. The changes in enkephalin levels observed during the isoflurane anesthesia and after its termination depended on the type of examined neuropeptides, as well as on parts of the brain and spinal cord studied. The changes observed after isoflurane administration in enkephalinergic system are discussed with regard to our earlier experiments with halothane and enflurane.