Optics: finding the best fit in telecom transport networks

This paper aims at looking beyond the gloomy current market evolution of the optical industry. Based on an analysis of the telecom transport market evolution (metropolitan as well as backbone), taking benefit of very significant technological breakthroughs in optics in recent years, this paper will suggest promising, yet pragmatic applications in telecom transport networks where optics will play a significant role beyond pure optical transmission.     

Measurement of the increase in the SHG coefficient of proton-exchanged LiNbO/sub 3/ after annealing using a grating diffraction technique

The effect of limited levels of annealing on the second harmonic generation (SHG) coefficient (d/sub 33/) of proton-exchanged LiNbO/sub 3/ has been determined by measuring nonphasematched SHG in a diffraction grating structure. The effect of annealing is to partially restore the intrinsic nonlinearity of the proton-exchanged layer.<>     

Bronchogenic squamous cell carcinoma in childhood; a case report

Primary carcinoma of the lung is unusual in children and the squamous cell variant is extremely rare. This, to the best of our knowledge, is the sixth reported case of bronchogenic squamous cell carcinoma in childhood.     

Isolated retinal arterial aneurysms

We observed three patients with isolated retinal arterial aneurysms and obtained a clinicopathologic correlation in one of them. All three were hypertensive and in the sixth or seventh decade of life. Fatty exudates were present around the aneurysms, taking the form of large circinate rings in two cases. Microscopic examination in one case revealed a retinal arterial aneurysm with an extensive fibroglial reaction around it. Dilated capillaries, hemosiderin deposits, and both lipoidal and proteinaceous exudates were found in the adjacent retina. Isolated retinal arterial aneurysms appear to be distinct clinical entity as compared to miliary aneurysms of the cerebral circulation.     

Influence of processing conditions on some properties of anionically synthesized polycaprolactam in presence of lithium chloride

Nylon 6–LiCl systems of various concentrations were prepared by anionic polymerization of caprolactam in the presence of salt. A depression of both crystallization rate and melting temperature was evidenced through x-ray, density, and DSC analyses. Such a preliminary characterization allowed for choosing the proper conditions in order to obtain amorphous fibers from a spinning operation which was performed at a temperature lower than the pure polymer melting point. These results are of technological relevance, especially in view of obtaining, as in similar cases, large amorphous orientations through a spinning–drawing process and high-modulus fibers after subsequent crystallization. Also, the possibility of restoring some crystallinity in the material has been proven.     

Orientation and Crystallinity Measurements in Film Casting Products

Summary Film casting experiments were carried out with iPP under processing conditions causing the crystallization process to occur under orienting flow. Draw ratio and cooling rates were changed by varying mass flow rates and die thickness. The effect of processing conditions on film crystallinity was investigated by combining WAXS and FT-IR transmission methods, while orientation of both phases was measured by IR dichroism (according to Fraser's method) and successfully compared to birefringence measurements on final films. Crystallinity appears to be almost insensitive to draw ratio and cooling rate. Moreover the crystallinity profile turned out to be also constant along the transverse film direction. Phases orientation were found relatively low and no dependence on draw ratio was detected.     

Time since last use of oral contraceptives and risk of invasive cervical cancer

OBJECTIVE: To review our experience of surgical staging for residual masses after chemotherapy in patients with nonseminomatous germ cell tumour (NSGCT) and positive tumour markers. PATIENTS AND METHODS: Of 107 patients with metastatic NSGCTs treated surgically after chemotherapy from 1978 to 1995, 30 (median age 30.5 years, range 20-52) had positive tumour markers. These patients were reviewed and the outcome compared with 77 patients who had normal tumour marker values. RESULTS: Of the 77 patients with negative markers undergoing surgical/pathological staging, 71 (92%) became continuously disease-free, including 37 of 50 (74%) with viable NSGCT in excised specimens. Seventeen of 30 (57%) with raised marker levels undergoing similar surgery for chemotherapy-resistant tumour became disease-free, including 11 of 22 with viable NSGCT in the excised specimens. CONCLUSION: Although the outcome after surgery is better in patients with negative tumour markers, it is clear that surgery is curative for patients with localized chemotherapy-resistant masses. There is a need for continued debate on the timing of salvage surgery and subsequent chemotherapy.     

Establishing the Cryptosporidium parvum karyotype by NotI and SfiI restriction analysis and Southern hybridization

Endo-observers can be described and classified on the basis of a novel two-dimensional scheme. One axis stands for the observer's style of knowledge acquisition, whereas the other axis corresponds to the observer's style of knowledge representation. In this way several problems concerning the relation between the endo-observer and the exo-system can be studied more systematically. Among other things, it is shown that there are two complementarity relations which restrict the observer's capacity of information gain: a duality between structure and dynamics (an increased information gain on the structure of the endo-system implies a reduced information gain on its dynamics, and vice versa), and a duality between the predictive and the explanatory power of a model. Connections with the problem of hermeneutics are outlined.