Optical observation of growth and melting dynamics of3He-4He mixture crystals

Crystals grown from 2.1% and 9.3% solutions of³ He in⁴He were observed in a cryostat with optical access from two orthogonal directions (above and from the side). Video films of dynamic processes were recorded at temperatures between 0.5K and 1.8K. Facetted melting of crystals (in contrast with rounded melting which is the general case) was observed below 0.75K. This is in accordance with previous experiments which showed a higher³He concentration along the edges of the crystal. We also recorded morphological growth instabilities of the 9.3% b.c.c. crystals. In the temperature region below about 0.9K where the latent heat is negative no dendritic growth was observed, which we interpret as resulting from opposing effects of temperature and concentration gradients.     

Complexity,Confusion, and Perceptual Grouping. Part II: Mapping Complexity

International Journal of Computer Vision - Intermediate-level vision is central to form perception, and we outline an approach to intermediate-level segmentation based on complexity analysis. In...     

Optical anisotropy of a worm-like chain and its application to the determination of the persistence length in an aromatic polyamide

The optical anisotropy, as obtained from the depolarization of light scattering, has been evaluated for a worm-like chain as a function of the segment anisotropy δ₀ and of the ratio of the contour length L to the persistence length q. The comparison between the theoretical curves and the experimental data obtained for an aromatic polyamide [poly(para-phenylene terephthalamide)] in a range of DP from 7 to 30 leads to a value of q in good agreement with that calculated from other methods requiring a wider range of molecular weights.     

Persistence length of cellulose tricarbanilate by small-angle neutron scattering

Small-angle neutron scattering measurements were made on cellulose tricarbanilate in dioxane at different temperatures. The persistence length evaluated from the Kratky plot was found to be 110 Å at room temperature. A decrease in persistence length with increasing temperature was observed.     

Ultimate Subjective Quality of a Satellite Television Network Covering Europe and Africa

The distribution of television programs over Europe and Africa via a geostationary satellite is considered on the basis of the satellite-earth liaison. The subjective quality of the image to be expected on the domestic TV receiver is expressed in terms of the ground antenna diameter for values of the satellite output power ranging from 10 to 100 watts, for different values of the RF bandwidth and several locations of the ground terminals in Europe, Africa, and the Middle East. The modulation technique used is the standard FM and the values considered for the carrier frequency are 4, 8, and 12 GHz. The effect of the dimensions of the ground receiving antenna on the subjective quality is given graphically for black-and-white and color television systems in both high and low field strengths relative to the local distribution station.     

Prognostic factors derived from recursive partition analysis (RPA) of Radiation Therapy Oncology Group (RTOG) brain metastases trials applied to surgically resected and irradiated brain metastatic cases

Platelet glycoprotein IIb/IIIa may be involved in the pathogenesis of myocardial infarction as the key element in platelet aggregation and as the binding site of lipoprotein(a) to platelets, inhibiting plasminogen binding and activation. Recently, a strong association between the P1A2 polymorphism of the glycoprotein IIIa gene and acute coronary thrombosis has been reported. although this has not been confirmed. In an associated study, we determined plasma lipoprotein levels, the apo E genotype and the P1A genotype in 250 males under 55 years with myocardial infarction and they were compared with 250 age- and sex-matched controls. Patients showed an over-representation of the epsilon3/4 genotype with respect to the control group. We found that there were no differences in the allelic frequency of P1A2 between case patients and age-matched controls (chi2 = 0.05, P = 0.92) and that subjects bearing the P1A2 allele showed higher plasma lipoprotein(a) concentration than p1A1/P1A1 individuals. Therefore, in this population there is no association between carriage of p1A2 allele and increased risk of myocardial infarction but the carriage of P1A2 is associated with higher plasma Lp(a) concentration.     

Validity of oxygen uptake measurements during exercise under moderate hyperoxia

PURPOSE: The validity of oxygen uptake in hyperoxia (FIO2 = 30%) measured by an automated system (MedGraphics, CPX/D system) was assessed during the simulation of gas exchanges during exercise with a mechanical system and during submaximal exercise by human subjects. METHODS: The simulation system reproduced a stable and accurate VO2 for 30 min (sim-test). This trial was repeated nine times in normoxia and nine times in hyperoxia. Ten subjects also performed two submaximal exercises (55% of normoxic VO2max) on a cycle ergometer at the same absolute power in normoxia and in hyperoxia (ex-test). RESULTS: There was a significant downward drift of the oxygen fraction measurement in hyperoxia (< or = 0.10% for FIO2 and FEO2) during sim-test, but VO2 measurement remained stable in the two conditions. There was also a downward drift of the oxygen fraction measurement in the two conditions (< or = 0.07% for FIO2) during ex-test. VO2 was significantly higher in hyperoxia (+4.6%), and this result was confirmed using a modified Douglas bag method. CONCLUSIONS: These findings show that the CPX/D system is stable and valid for assessing VO2 in moderate hyperoxia.