1,721,289 research outputs found
Phase ordering of conserved vectorial systems with field-dependent mobility
No full textThe dynamics of phase-separation in conserved systems with an O(N) continuous symmetry is investigated in the presence of an order-parameter-dependent mobility M{phi} = 1-a phi(2). The model is studied analytically in the framework of the large-N approximation and by numerical simulations of the N=2, N=3, and N=4 cases in d=2, for both critical and off-critical quenches. We show the existence of a universality class for a=1 characterized by a growth law of the typical length L(t)similar to t(1/z) with dynamical exponent z=6 as opposed to the usual value z=4, which is recovered for a<1
Telechelic melt polymer’s structure variation depending on shear deformation
No full textWe present the result of molecular dynamics (MD) simulations of bead and spring models
of associating polymers at melt-like densities, both in static conditions and when a shear
rate is applied. Specifically, we consider the response of telechelic polymers of general
formula AB12A to four different values of shear rate. The A terminals tend to associate
with each other and in bulk conditions form clusters or micelles. A reversible network or
physical gel is formed by a large fraction of bridging chains that interconnect different
clusters. The micelles assume different form depending on the interaction strengths.
When a shear rate is applied, the clusters are broken and the chains tend to stretch
Evaluation of viscosity and shear stress in a telechelic polymer when various shear rates are applied
No full textWe present the results of molecular dynamics (MD)
simulations of bead and spring models of associating polymers
at melt-like densities.We consider telechelic polymers of
general formula AB12A at different values of shear rate. Under
bulk conditions, A···A associations occur, leading to the construction
of clusters or micelles that are interconnected by a
number of bridging chains. This results in a physical gel or a
reversible network, and the corresponding micelles assume
different forms depending on the interaction strength.
Whenever a low shear deformation is applied, the clusters
are broken and there is a phase transition similar to that from
a gel to a common non-Newtonian fluid. However, if the
applied shear is increased, the chains stretch themselves (in a
manner similar to nematic liquid crystal ordering) in a different
way from what is seen without shear. In this work, we
calculate the stress needed to yield a required deformation
C. Castellano, La politica antimonopolistica negli Stati Uniti
No full textC. Castellano, La politica antimonopolistica negli Stati Uniti. In: Revue internationale de droit comparé. Vol. 13 N°4, Octobre-décembre 1961. pp. 855-856
C. Castellano, La politica antimonopolistica negli Stati Uniti
No full textC. Castellano, La politica antimonopolistica negli Stati Uniti. In: Revue internationale de droit comparé. Vol. 13 N°4, Octobre-décembre 1961. pp. 855-856
Effects of naloxone and naltrexone on locomotor activity in C57BL/6 and DBA/2 mice
No full textAdministration of naloxone or naltrexone in DBA/2 (DBA) mice was followed by dose related depressant effects. The locomotor activity of the C57L/6 (C57) mice injected with naltrexone was also depressed. Low doses of naloxone induced a decrease in activity in the C57 strain. This effect gradually disappeared at intermediate doses and recurred again at higher doses. The results are discussed in terms of differences in type number and/or distribution of the receptors influenced by naloxone and naltrexone in the two strains of mice tested
Strain-dependent modulation of memory by stress in mice
No full textThe effects of immobilization stress were investigated in Swiss Webster (Swiss), DBA/2 (DBA), and C57BL/6 (C57) mice, tested in a passive avoidance situation. Retention performance was impaired in Swiss and DBA mice, and improved in C57 mice, immobilized immediately, but not 2 hr, after training. These effects lasted for less than 7 days in DBA and Swiss mice, while they were still present, in the C57 strain, 14 days after training. The naloxone antagonism of the effects observed was also demonstrated. The results are discussed in terms of the possible role of endogenous opioids, stress hormones, and genetic makeup in the stress-induced modulation of memory processes in the mouse
- …
