Boson Peak Decouples from Elasticity in Glasses with Low Connectivity.

We perform molecular-dynamics simulations of the vibrational and elastoplastic properties of polymeric glasses and crystals and the corresponding atomic systems. We evidence that the elastic scaling of the density of states in the low-frequency boson peak (BP) region is different in crystals and glasses. Also, we see that the BP of the polymeric glass is nearly coincident with the one of the atomic glasses, thus revealing that the former-unlike the elasticity-is controlled by nonbonding interactions only. Our results suggest that the interpretation of the BP in terms of the macroscopic elasticity, discussed in highly connected systems, does not hold for systems with low connectivity.

The effect of free air carbon dioxide enrichment (FACE) and soil nitrogen availability on the photosynthetic capacity of wheat.

A simple system for free air carbon dioxide enrichment (FACE) was recently developed and it is here briefly described. Such a MiniFACE system allowed the elevation of CO2 concentration of small field plots avoiding the occurrence of large spatial and temporal fluctuations. A CO2 enrichment field experiment was conducted in Italy in the season 1993-1994 with wheat (cv. Super-dwarf Mercia). A randomized experimental design was used with the treatment combination CO2 × soil N, replicated twice. Gas exchange measurements showed that photosynthetic capacity was significantly decreased in plants exposed to elevated CO2 and grown under nitrogen deficiency. Photosynthetic acclimation was, in this case, due to the occurrence of reduced rates of rubP saturated and rubP regeneration limited photosynthesis. Gas exchange measurements did not instead reveal any significant effect of elevated CO2 on the photosynthetic capacity of leaves of plants well fertilized with nitrogen, in spite of a transitory negative effect on rubP regeneration limited photosynthesis that was detected to occur in the central part of a day with high irradiance. It is concluded that the levels of nitrogen fertilization will play a substantial role in modulating CO2 fertilization effects on growth and yields of wheat crops under the scenario of future climate change.

[Puntino and the injections of Popeye]. / Puntino e le punturine di Braccio di Ferro.

Subcutaneous injection of active principles must be performed through a short and thin needle and an insuline syringe (because of the few quantity of drug to administrate). In our Centre, to prevent preterm chronic anemia wc practice subcutaneous therapy with recombinant human erythropoietin. 300 UI three times a week, to all the newborns weighing < 1500 g at birth. Injections to the newborns are performed in correspondence of their gluteal and deltoid muscles, and in the outer part of their thigh. To prevent atrophy, it is important to change every time the site of Injection. For this goal, we have created the shape of a newborn, nained Puntino, and we have located 24 points on it. Each point has received a number between 0 and 23. During the treatment we have followed the guide of Puntino to locate each time the correct site of injection. Thanks to Puntino's aid, there were no cases of skin adverse reaction and atrophy, even in newborns weighing < 1000 g.