Relaxation oscillations in optically pumped molecular lasers

We report the observation of relaxation oscillations in both the C¹³H3F and C¹²H3F optically pumped lasers. Expressions are derived for the oscillation frequency and its temperature and pressure dependences using a four-level rate equation model. We observe excellent agreement between measured frequencies and the theory presented. Models are considered for using this phenomenon to determine the rotational and vibrational relaxation mechanisms of the laser gases.     

Theory of cooperative transition of DNA complexes with multimodal ligands

The theory of the cooperative transition of DNA.ligand complexes have been developed, in which a model was implied where the multimodal ligands simultaneously interacted with DNA. Obtained formula express the dependence of the experimentally estimated values of the changes of transition point and width of transition on the concentration of the ligands. These expressions make possible to obtain the thermodynamic parameters of the interaction of the multimodal ligands with DNA (binding constants, number of base pairs corresponding to one binding site of DNA etc.) by comparing the theoretical and the experimental data.     

Cytological study of the puncture biopsy specimens of the Douglas' pouch for early diagnosis of ovarian tumors

The conducted studies indicated the diagnostic opportunities of a cytologic analysis of exudates and smears from the Douglas space in patients with a suspicion to ovarian tumor. Tumor cells may be present in the peritoneal cavity not only in different stages of malignant ovarian tumors, but also in secernent and proliferating cystadenomas. A correlation between the peritoneal cell content in patients with different forms of ovarian neoplasms and press-smears from the dissected surface of the removed tumors and histological sections indicated the morphological identitiy of tumor elements and enabled the determination of the cytological criteria for the differential diagnosis of ovarian tumors prior to surgical intervention.     

Reversed ileal segment for treatment of ileostomy dysfunction. Clinical application

Persistent, profuse ileostomy diarrhea developed gradually in a patient over a 12-hour period after proctocolectomy for ulcerative colitis. There was no evidence of ileostomy stenosis or dilation of the ileum proximal to the stoma. He was successfully treated with a reverse ileal segment of 10 cm, and gained 14 to 18 kg. ileostomy output became semisolid and decreased from 1,000 to 2,000 ml/day to 600 ml/day. The transit time changed from 12 minutes to 2 1/2 hours. Antiperistaltic segments of intestine prolong transit time and allow for greater absorption. While most patients with ileostomies are not troubled by severe diarrhea, the small proportion who are may be candidates for a reversed ileal segment.     

Limb salvage procedures for lower extremity ischemia

A series of 348 patients undergoing operative intervention because of thyroid masses is reviewed. The incidence of primary malignancy among these patients is 16.4%. Male sex and the presence of cervical adenopathy significantly increase the probability of malignancy. The presence of multiple nodules or a functional nodule on radioiodine thyroid scan significantly reduces the probability of cancer. A rational approach to thyroid nodules is presented based on these findings and new modalities that have become available.     

Optical bistability in a dissipative thermally expanding etalon

The phenomenon of optical bistability is examined for the case of a lossy Fabry-Perot etalon. Using a multibeam interference method and thermal length expansion relationships, we derive an inverted equation which predicts the output transmission for such an etalon. Specific operating parameters are given for silicon wafer structures operating in the lattice vibration absorption regime (10 μm). Experiments using 15 ms CO2laser pulses and Si wafers show resonance-to-nonresonance switching.