Double-heterodyne probing for an ultra-stable laser based on spectral hole burning in a rare-earth-doped crystal.

We present an experimental technique for realizing a specific absorption spectral pattern in a rare-earth-doped crystal at cryogenic temperatures. This pattern is subsequently probed on two spectral channels simultaneously, thereby producing an error signal allowing frequency locking of a laser on the said spectral pattern. Appropriate combination of the two channels leads to a substantial reduction in detection noise, paving the way to realizing an ultra-stable laser for which the detection noise can be made arbitrarily low when using multiple channels. We use this technique to realize a laser with a frequency instability of $ 1.7 \times 1{0^{{\bf - }15}} $1.7×10-15 at 1 s, not limited by the detection noise but by environmental perturbation of the crystal. This is comparable with the lowest instability demonstrated at 1 s to date for rare-earth-doped crystal stabilized lasers.

[Agglutinins in the diagnosis of pertussis]. / Aglutinini u dijagnostici pertussisa.

The performed investigation showed that the results of agglutination test in diagnostics must be explained with reserve as a supplement to the clinical picture and the other laboratory findings. Titre must be followed at least for 20 days on many blood samples. The more reliable diagnosis according to agglutination test can be given only if we know in question is a nonimmunized child and titre is > or = 1:80. The negative and lower titres cannot exclude or confirm the disease.

[Comparison of the immunoenzyme test (ELISA) with other methods in the detection of rheumatoid factor]. / Komparacija enzimskog imunoloskog testa (ELISA) sa drugim metodama u detekciji reumatoidnog faktora.

IgM rheumatoid factor was detected, beside ELISA test, by Waaler-Rose, Latex agglutination and indirect immunofluorescent test. 107 patients hospitalized in the Clinic for heart diseases and rheumatism, as well as 50 healthy subjects were examined. In the first group were 50 patients with RA, 30 patients with other rheumatic diseases and 27 with nonrheumatic diseases. According to our results there was no significant difference between sensitivity of ELISA test and other laboratory tests used. ELISA test was positive in 94% of cases of RA, 20% in other rheumatic diseases and only in one case (3,7%) of a nonrheumatic disease. Compared with the control group in which there was no specific reaction, Waaler-Rose and immunofluorescent testing showed a nonspecific reaction in 2% and Latex test in 4% of all cases. Although ELISA test was not significantly sensitive as compared with other laboratory methods, according to our results, it has high reproducibility, specificity and precision (it is measured in international units/mL serum), and it allows following of the concentration of rheumatoid factor. Besides, ELISA test can be done on 100 specimen of blood within 6 hours and the results are known the same day.

[Determination of B and T lymphocytes in bronchoalveolar lavage and peripheral blood of patients with active sarcoidosis]. / Odredivanje B i T limfocita u bronhioalveolarnom ispirku i perfirnoj krvi kod bolesnika sa aktivnom sarkoidozom.

The total number of cells, alveolar lymphocytes as well as T lymphocytes is increased in BAL in patients with active sarcoidosis (acute phase and relapse) with disturbed relation T4-T8 subpopulation. T lymphocytes are significantly decreased in peripheral blood of patients with active sarcoidosis, while B lymphocytes are also decreased but without evident significance in relation to normal values.

[Bacteriological control of blood preservation, production of infusion solutions and dry human plasma under conditions of aseptic work and possible sources of their contamination]. / Bakterioloska kontrola konzervacije krvi, proizvodnje infuzionih rastvora i suhe ljudske plazme u uslovima asepticnog rada i moguci izvori njihove kontaminacije

In premises for blood conservation, production of dry human plasma and infusion solutions "notwithstanding the permanent measures for desinfection, new bacterial contamination occurs from time to time and whose source are the casings and material originating from non-sterile environment. Bacteriological control, which has primarily a preventive character, enables a due forecast for measures to be undertaken by the appropriate desinfection of the working surfaces and air, satisfactory conditions of aseptic work can be maintained. General hygiene should be paid attention to as well as mechanical cleansing of premises, avoidance of groups for lunch-time etc., since the treatment by desinfectors would not be sufficient for maintenance of aseptic working conditions. In order to prevent the transmission of bacterial contamination, premises for blood conservation should be strictly separated from other operations and also prevent the unnecessary movements of personnel through corridors. The results of the bacteriological control of the personnel show that greater attention should be paid to their health care since the workers there work in closed aseptic systems and thus avoid them as a bacteria transmittors in respect to danger of blood and dry human plasma contamination. It is also necessary to efficiently educate the personnel for work in aseptic conditions and also increase their elementary knowledge from bacteriology and hygiene. The bacterial skin-flora on the spot of donor's venepuncture also presents a certain danger for blood contamination. Therefore, it is necessary to establish the most optimal manner of skin desinfecate together with the most appropriate means having a fast bactericidal and fungicidal action. It would also be useful, on the basis of further test, to suggest certain standard for an allowed number of conditionally pathogenic and saprophytic microorganisms which would be used by the instutions performing the blood transfusion and production of the intravenous solutions during their bacteriological controls.