The Effects of Noise Correlation and Power Imbalance on Terrestrial and Satellite DPSK Channels

New results are given for the bit error probability for binary DPSK modulation over both terrestrial and satellite channels taking into account noise correlation and power imbalance. The new expressions are remarkably simpler than their previously published counterparts. For the terrestrial channel, the results are in closed form in terms of tabulated functions and, for the hard-limiting satellite channel, both in terms of integrals readily evaluated by quadrature and in terms of infinite series. Using the results, it is shown that the error rate does not depend on the noise correlation (down-link in the satellite case) so long as the a priori symbol probabilities are equal, thereby solving an "open problem" posed by Lee, French, and Hong. Also, the satellite case in which each of the up-link and down-link channels contains nonzero noise correlations is briefly treated.     

Significance of the state of the celiac and mesenteric arteries in the treatment of occlusive lesions of the abdominal aorta and iliac vessels

The status of the celiac and mesenteric arteries in 124 patients with occlusive injuries to the abdominal aorta and iliac arteries has been studied by means of the antero-posterior and lateral translumbar abdominal aortography. Clinical picture and symptoms of pathological conditions with the regard to the localization of occlusion are described. Some practical recommendations are given.     

Transcapillary fluid responses to lower body negative pressure

The effect of lower body negative pressure (LBNP) on transcapillary fluid balance is unknown. Therefore, our objective was to assess leg interstitial fluid pressures (IFP), leg circumference, plasma volume (PV), and net whole body transcapillary fluid transport (TFT) during and after supine LBNP and to evaluate the addition of oral saline ingestion on transcapillary exchange. Six healthy men 23-41 yr old underwent 4 h of 30 mmHg LBNP, followed by 50 min of supine recovery on two separate occasions, once with and once without ingestion of 1 liter of isotonic saline. IFP was measured continuously in subcutis as well as superficial and deep regions of the tibialis anterior muscle by slit catheters. TFT was calculated by subtracting urine production and calculated insensible fluid loss from changes in PV. During exposure to LBNP, IFP decreased in parallel with chamber pressure, foot venous pressure did not change, leg circumference increased by 3 +/- 0.35% (SE) (P < 0.05), and PV decreased by 14 +/- 2.3%. IFP returned to near control levels after LBNP. At the end of minute 50 of recovery, PV remained decreased (by 7.5 +/- 5.2%) and leg circumference remained elevated (by 1 +/- 0.37%). LBNP alone produced significant movement of fluid into the lower body but no net TFT (-7 +/- 12 ml/h). During LBNP with saline ingestion, 72 +/- 4% of the ingested fluid volume filtered out of the vascular space (TFT = 145 +/- 10 ml/h), and PV decreased by 6 +/- 3%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intramyocardial small-vessel disease in chronic alcoholism

A morphologic study of the small (50 to 200 micron) intramyocardial coronary arteries was performed. The cases chosen for study were selected from a relatively young group of patients without clinical evidence of alcoholic cardiomyopathy or pathologic evidence of large coronary artery disease, in order to evaluate alterations in the small vessels which could possibly be attributed to the chronic alcoholic state. Five basic vascular abnormalities were described. The most common alteration found in all nine cases was vascular wall edema (48 per cent), followed by perivascular fibrosis (42 per cent), vascular sclerosis (36 per cent), subendothelial humps (13 per cent), and vascular wall inflammation (11 per cent). The significance and pathogenesis of these changes were discussed. Primary endothelial cell damage was proposed as a common pathogenic mechanism for all five types of vascular abnormality. It was suggested that following endothelial damage, fluid and macromolecules penetrate into the vessel wall or into the perivascular space where, by incompletely understood processes, they induce vascular wall myocytes to produce collagen, elastin, and basement membrane-like substances. Evidence supporting this mechanism was derived from the common observation of vascular wall edema, from the occasional presence of erythrocytes and leukocytes within the vessel wall, and from experimental data in the literature. Several possible etiologic agents were implicated in the pathogenesis of endothelial and vessel wall injury. These included alcohol itself, acetaldehyde, biogenic amines, and magnesium deficiency. It is probable, however, that there are multiple etiologic factors which affect the small cardiac vessels of the chronic alcoholic. Finally, the proposal was advanced that the nonspecific pathology of the myocardium in chronic alcoholism may be a result of ischemia secondary to disease of the small intramyocardial coronary ateries.     

The open surgical approach to subglottic hemangioma

The monthly distribution of relapses in ulcerative colitis was analysed retrospectively to assess seasonal variation. In 338 patients who were regularly followed up at the colitis clinic, 1013 relapses occurred during the period 1977 to 1988. A peak of relapses occurred in the spring and autumn, with a decrease in the summer; the ratio of the observed to expected number of relapses was 201:255.3 for the summer, 289:252.6 for the autumn, 243:249.8 for the winter, and 280:255.3 for the spring. In contrast, month of diagnosis was evenly distributed without seasonality. The data support the concept that exacerbations in ulcerative colitis are influenced by seasonal factors.     

Charge incorporation in ω-tricosenoic acid Langmuir-Blodgett multilayers

In order to investigate the amount of charge introduced into Langmuir- Blodgett (LB) films, multilayers of ω-tricosenoic acid have been deposited onto a number of silicon substrates under different dipping conditions. The effects of moisture and storage conditions on film properties have been examined, and a new mathematical model for the charge distribution within an LB film multilayer will be proposed.     

Solutions of lithium salts in liquid lithium: The interaction of hydride and of nitride with lead and with tin

Electrical resistivity studies of Li-Pb-H(N) ternary solutions ($\text{x}{}_{\mathrm{Li}}\text{? 0.96}$; $\text{T = 675 K}$) have shown that lead does not interact chemically with either LiH or Li₃N in liquid lithium solutions; similar studies of Li-Sn-H(N) ternary solutions ($\text{x}{}_{\mathrm{Li}}\text{? 0.96}$; $\text{T = 775 K}$) have shown that tin is also inert to both LiH and Li₃N in these solutions. Solubility data for LiH in liquid lithium-lead solutions ($\text{x}{}_{\mathrm{Pb}}\text{= 0.01}$; $\text{675 ? T(K) ? 735}$) have also been determined and compared with those for LiH in pure lithium. Enhanced solubilities are observed for the lithium-lead solutions; they are attributed to a decreased LiH activity in the ternary solutions vis-àvis the binary solutions. The significance of the results to the use of lead as a neutron multiplier in reactor lithium is discussed.