Surface localization of the sea urchin egg receptor for sperm

The sea urchin egg receptor for sperm is thought to be involved in species-specific sperm-egg interactions at the egg surface. Recent revisions in the deduced amino acid sequence of the cloned cDNAs indicate that the protein encoded does not possess the common structural hallmarks of a membrane protein. Thus, investigation of the localization and association of the protein with the egg surface is crucial. We describe and characterize a new monoclonal antibody raised against recombinant sperm receptor protein. This antibody, in conjunction with several polyclonal antibodies, was used to study the receptor protein in eggs. Immunoprecipitation studies indicated that the antibodies recognize the high Mr (ca. 350 K) sperm receptor protein which copurified with egg plasma membrane-vitelline layer complexes. The sperm receptor protein was solubilized only by detergents and not by treatments designed to solubilize peripherally associated or lipid-anchored membrane proteins, suggesting a tight association with the membrane fraction. Confocal immunofluorescence microscopy of live eggs indicated surface staining. Finally, lysylendoproteinase C treatment of live eggs resulted in a loss of the high Mr receptor protein epitopes, and the concomitant release of a 70-kDa proteolytic fragment, which correlated with a reduced ability of the eggs to be fertilized. Taken together, these data indicate that at least some fraction of the sperm receptor protein is present on the egg surface, a requisite locale for a sperm binding protein.     

Agens Faber: Toward a Theory of Artefacts for MAS

Human intelligence has evolved along with the use of more and more sophisticated tools, allowing Homo Faber (from Homo Habilis to Homo Sapiens Sapiens) to cope with environment changes, as well as to adapt the environment to his needs. Analogously, in this seminal paper we introduce the notion of Agens Faber, conveying the idea that agent intelligence should not be considered as separated by the agent ability to perceive and affect the environment—and so, that agent intelligence is strictly related to the artefacts that enable, mediate and govern any agent (intelligent) activity.

Along this line, we first discuss the notion of artefact for MAS in general, then we try to devise out the admissible / required / desirable features of an artefact for MAS. We elaborate on the many sorts of possible relations between agents and artefacts, focusing in particular on the issue of the rational exploitation of artefacts, and also rough out a possible taxonomy of artefacts for MAS.     

Silver electrodeposition from air and water-stable ionic liquid: An environmentally friendly alternative to cyanide baths

The influence of temperature on the kinetics and the morphology of silver deposits obtained from an air and water-stable ionic liquid (the 1-butyl-3-methyl imidazolium tetrafluoroborate) was studied by means of cyclic voltammetry and chronoamperometry. The nucleation and growth mechanisms have been investigated and the effect of temperature evaluated up to 200 °C. Dense, pure and very thin (about 0.3 μm) silver coatings, with decorative properties, have been obtained on commercial copper electrodes at different temperatures. The characterization of the deposits morphology has been performed by visual investigation and SEM microscopy. Data about thickness were acquired by Calotest® measurements. The deposits result constituted by pure silver as determined by combination of EDX microanalysis and Auger Electron Spectroscopy (AES). The deposition method promises to be a new, environmentally friendly, method for silver electrodeposition which is the reason for the absence of cyanide and volatile toxic solvents in the electroplating bath.     

Effects of temperature, ammonium and glucose concentrations on yeast growth in a model wine system

In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth‐cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae.     

The effect of physical exercise on the response to exertion in the elderly

BACKGROUND: A decrease in adaptation to exertion has been observed as age progresses. Although this decline may also be affected by factors such as health conditions and age, physical inactivity related to sedentary behaviour plays a dominant role. METHODS: In order to evaluate the influence of physical activity on cardiovascular response to exertion in the elderly, 4 groups of 22 subjects each were submitted to maximal electrocardiographic exercise test on a cycloergometer (multistage program with 30 Watts x 3 min. steps). All subjects were male. The composition of the groups was as follows: 1) veteran long distance runners (mean age: 71 +/- 5.4); 2) sedentary veterans (mean age: 69.8 +/- 3.9); 3) young long distance runners (mean age: 25.4 +/- 4.3); 4) sedentary young adults (mean age: 25.8 +/- 3.9). The endurance athletes, well fitted to competition, had been practicing sport activity for at least 3 years. RESULTS: Heart rate, arterial systolic and diastolic blood pressure were recorded; mean blood pressure and double product were calculated at baseline and at the climax of the stress test; furthermore, total and maximal watts were recorded. For each of the parameters, Student's t test for non-paired observations were used to evaluate statistical differences amongst the four groups. The most interesting result arises in the comparison between veteran long distance runners and sedentary young adults: between the two groups no statistically significant differences in workload, expressed as total watts (1649.55 +/- 296.32 vs 1650.00 +/- 446.32; p = NS) and maximal watts (175.91 +/- 19.19 vs 173.18 +/- 24.38; p = N.S.), were observed. On the contrary, highly significant differences in both total (p < 0.01) and maximal (p < 0.01) watts were noticed by comparing long distance runners and sedentary subjects of the same age. CONCLUSIONS: These data support the hypothesis that the progressive reduction in physical activity, which is usually observed in aging, is the major determinant of exercise deconditioning in the elderly.     

Design and performance of a recessed thin film inductive transducer

An improved inductive transducer is achieved by placing the coil and the majority of the transducer body into a recessed alumina basecoat. Process advantages of a recessed over planar structure includes lower top pole topography, improved pole trim capability, and improved top pole composition uniformity. Coil and photoresist processing in a recessed cavity allows for multiple layers with lower resistance without increasing transducer Permalloy path length. Recessed trimmed design performance has increased efficiency with higher amplitude and a narrower pulse width along with improved overwrite compared to planar untrimmed transducers. The recessed basecoat design is explained, and compared to planar transducers using modeling and performance results     

Two-Way Protocol with Imperfect Devices

The security of a deterministic quantum scheme for communication, namely the LM05 [1], is studied in presence of a lossy channel under the assumption of imperfect generation and detection of single photons. It is shown that the scheme allows for a rate of distillable secure bits higher than that pertaining to BB84 [2]. We report on a first implementation of LM05 with weak pulses.     

Techniques for the mechanical characterisation of civil structures

Broadly speaking, structural defects include all those changes affecting a structure so that its behaviour is no longer in keeping with its intended use characteristics or differs from the behaviour it was originally designed for. In recent years, damage recognition and location methods, relying on the measurement of parameters that are indicative of a structure's mechanical behaviour, have benefitted from the introduction of innovative approaches, which make it possible to process and correlate an unprecedented wealth of measurble data. The aim of this work is to illustrate the basic problems associated with the different methods used for structural identification (parametric and non-parametric, linear and non-linear, with known and unknown inputs, etc.) and to report on some interesting applications for civil structural diagnosis.     

Study of the hinge thickness deviation for a 316L parallelogram flexure mechanism fabricated via selective laser melting

3D printing offers great potential for developing complex flexure mechanisms. Recently, thickness-correction factors (TCFs) were introduced to correct the thickness and stiffness deviations of powder-based metal 3D printed flexure hinges during design and analysis. However, the reasons for the different TCFs obtained in each study are not clear, resulting in a limited value of these TCFs for future design and fabrication. Herein, the influence of the porous layer of 3D printed flexure hinges on the hinge thickness is investigated. Samples of parallelogram flexure mechanisms (PFMs) were 3D printed using selective laser melting (SLM) and 316L stainless steel powder. A 3D manufacturing error analysis was completed for each PFM sample via 3D scanning, surface roughness measurement and morphological observation. The thickness of the porous layer of the flexure hinge was independent of the designed hinge thickness and remained close to the average powder particle diameter. The effective hinge thickness could be estimated by subtracting twice the value of the porous layer thickness from the designed value. Guidelines based on finite element analysis and stiffness experiments are proposed. The limitations of the presented method for evaluating the effective hinge thickness of flexure hinges 3D printed via SLM are also discussed.