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Copolymerisation of charged and neutral monomers is a well-known methodology to introduce charged moieties in a polymeric chain to obtain polyelectrolytes. New polyelectrolyte complexes have been synthesised by radical copolymerisation of neutral methacrylic monomer 2-hydroxyethyl methacrylate (HEMA) with cationic 2-methacryloyloxyethyltrimethyl ammonium chloride and anionic 2-acrylamido-2-methylpropane-sulphonic acid monomers in 10 : 1 : 1 and 10 :1 : 2 stechiometric ratio. Chemical structure of the synthesised terpolymers was confirmed by FT-IR spectroscopy, moreover, X-ray photoelectron spectroscopy showed the presence of a cationic charge excess on the 10 : 1 : 2 terpolymer surface with respect to 10 : 1 : 1 terpolymer. Swelling studies for 10 : 1 : 2 terpolymers showed a high water content in the swollen state and a “smart behaviour” upon changes in external stimuli such as pH, while, 10 : 1 : 1 terpolymer presented the behaviour of a neutral polymer. Mechanical and differential scanning calorimetry analysis confirmed that terpolymer networks were stabilised by ionic co-operative interactions. Infact, the inclusion of oppositely ionic charges in the polymeric network of p(HEMA) represent a way to achieve higher elastic modulus as they stabilise the terpolymer networks. Cytotoxicity and cytocompatibility studies demonstrated that all materials were not toxic, moreover, the presence of a cationic charge excess on 10 : 1 : 2 terpolymer surface was able to promote fibroblast adhesion.

Summary.Two groups of men were retrospectively selected according to their observed success in in-vitro fertilization. Seminal and post-migration sperm samples from a low fertilization rate group (≤33% cleaved embryos) have been compared to results obtained from a high fertilization rate group (≥ 66%). It was found that a low mean value of the amplitude of lateral sperm head displacement and an increased percentage of abnormal acrosomes were related to in-vitro fertilization failure. None of the individual sperm factors studied was found to determine in-vitro fertilization success with certainty; only when they were considered in combination was it possible to predict the likelihood of successful in-vitro fertilization of human oocytes.

We consider a quasi steady laminar axisymmetric flow of Bingham type under the assumption that the yield stress increases at a rate proportional to the internal power dissipation. Such a behaviour has been observed in coal-water slurries. Many different cases can occur (including the appearance of a rigid shell at the boundary of the pipeline), which are analyzed both theoretically and numerically.

Experiments show that the degradation effect observed during both stirring and pipelining tests of some coal-water slurries is mainly to be ascribed to the increase of the yield stress. Regardless of the particular mathematical model adopted to investigate the dynamics of these fluids, engineering applications force us to consider the problem of how long a constant flow rate can be maintained during the pipelining process. We choose a Bingham model where the yield stress is assumed to increase with the dissipated energy as in [5]. It is first shown that the constant flow rate problem is equivalent to solving a nonlinear functional equation in the unknown pressure gradient that generalizes the classical algebraic Buckingham equation for the same problem with constant rheological parameters. By means of a fixed-point argument we also prove that the functional equation has one and only one solution which is local in time. We finally find an estimate from below of the interval of the interval of existence. Numerical results are rather good and agree with those expected from the engineering point of view.

The CLUE experiment has started operation with four of the nine telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the same site as the HEGRA experiment. In winter 1997 we started taking data with the telescopes pointing directly at the moon. A description of the telescopes and the performance of the detector are given.

Oocyte recovery in an in vitro fertilization and embryo transfer (IVF-ET) program can be performed by laparoscopy or by sonography. Most IVF teams use either one or the other of these methods. In Clamart, we undertook 407 IVF attempts from September 1983 to March 1984, 225 by laparoscopy under general anesthesia, 97 by laparoscopy under local anesthesia, and 85 by sonography. Excluding the recovery techniques, all aspects of the program (ovulation monitoring, culture, and transfer) were identical in order to study the effects of the anesthesia and the ultrasound. We did not find any significant difference in pregnancy rates, inclusive of biochemical pregnancies, among these three recovery methods, although ultrasonically guided puncture gave fewer follicles, oocytes, and embryos than laparoscopy.

Purpose: The rate of objectively proven pulmonary embolism in patients with thrombophlebitis of the greater saphenous vein was studied. Methods: Consecutive ambulant patients with thrombophlebitis of the greater saphenous vein, involving the above-knee segment, underwent a complete venous echo color Doppler examination of the lower limbs, perfusion lung scanning, and chest radiography. A high probability of pulmonary embolism was defined as the presence of two or more large segmental defects, one large and two or more moderate perfusion defects, or four or more moderate perfusion defects, with no corresponding abnormality found by means of chest radiography. Results: Of the 21 patients included in the study, findings compatible with a high probability of pulmonary embolism were detected in seven patients (33.3%; 95% CI, 14.6 to 57.0), although clinical symptoms of pulmonary embolism were present only in one patient. No association was found between the presence of thrombosis at the saphenofemoral junction and the risk for pulmonary embolism. Conclusion: The rate of pulmonary embolism in patients with thrombophlebitis of the greater saphenous vein is unexpectedly high. This risk is similarly high in patients with thrombosis at the saphenofemoral junction and in patients without thrombosis at the saphenofemoral junction. Our results are consistent with those of other recent investigations and suggest that superficial thrombophlebitis of the thigh is not as benign a disease entity as previously described. (J Vasc Surg 1999;30:1113-5.)

We describe a trigger architecture developed for shower selection in the CLUE Cherenkov telescopes. The selection is made first in each telescope of the array looking at the low resolution images produced by fast electronics, than requiring temporal coincidence between units. Big effort has been put to simplify the programming of trigger configurations to help the user to switch easily between different observational and calibration requests.