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Establishment of in vitro tissue cultures from Echinacea angustifolia D.C. adult plants for the production of phytochemical compounds
No full textSUMMARY The establishment of in vitro cultures of Echinacea angustifolia D.C. was obtained directly from sections of flower stalks of adult plants. The shoot formation was obtained from this plantmaterial placed on a modified MS basal medium named CH supplemented with 0.5 mg L1 6 benzylaminopurine (BA). The in vitro propagation procedure of E. angustifolia consisted of three distinct phases: an initial regeneration phase fromstalk sections (IP shoots on basal mediumwith 0.25 mg L1 BA), an elongation phase on active charcoal and an axillary proliferation of the shoots (AP shoots on basal medium with 0.5 mg L1 BA).Regenerating calli were established from leaves of in vitro shoots cultured on CH medium supplemented with 3 mg L1 BA and 0.5 mg L1 indole-3-butyric acid (IBA). Developed shoots from the callus cultures were subcultured on the CH medium with 0.5 mg L1 BA (leaf regenerated shoots: LR shoots). The secondary metabolite content of the in vitro plant material was compared with that of the greenhouse growing plants. The quali-quantitative LC-DAD-ESI-MS analysis on the extracts from axillary proliferation shoots (AP shoots) showed significant production of caffeic acid derivatives while leaf callus and LR shoots, accumulated mainly alkamides. These results showed that the proper choice of the procedures for in vitro multiplication allowed us to obtain plant biomass able to produce the active compounds typical of E. angustifolia plants
Distributed consensus on boolean information
No full textIn this paper we study the convergence towards consensus on information in a distributed system of agents communicating over a network. The particularity of this study is that the information on which the consensus is seeked is not represented by real numbers, rather by logical values or compact sets. Whereas the problems of allowing a network of agents to reach a consensus on logical functions of input events, and that of agreeing on set{valued information, have been separately addressed in previous work, in this paper we show that these problems can indeed be attacked in a unied way in the framework of Boolean distributed information systems. Based on a notion of contractivity for Boolean dynamical systems, a necessary and sucient condition ensuring the global convergence toward a unique equilibrium point is presented. This result can be seen as a rst step toward the denition of a unied framework to uniformly address all consensus problems on Boolean algebras
Minimization of with a perimeter constraint
No full textWe study the problem of minimizing the second Dirichlet eigenvalue for the
Laplacian operator among sets of given perimeter. In two dimensions, we prove
that the optimum exists, is convex, regular, and its boundary contains exactly
two points where the curvature vanishes. In dimensions, we prove a more
general existence theorem for a class of functionals which is decreasing with
respect to set inclusion and lower semicontinuous
Analytic continuation of the critical line: suggestions for QCD
No full textSUMMARY We perform a numerical study of the systematic effects involved in the
determination of the critical line at real baryonic chemical potential by
analytic continuation from results obtained at imaginary chemical potentials.
We present results obtained in theories free of the sign problem, such as
two-color QCD with finite baryonic density and three-color QCD with finite
isospin chemical potential, and comment on general features which could be
relevant also to the continuation of the critical line in real QCD at finite
baryonic density
Finite size phase transitions in QCD with adjoint fermions
No full textWe perform a lattice investigation of QCD with three colors and 2 flavors of
Dirac (staggered) fermions in the adjoint representation, defined on a 4d space
with one spatial dimension compactified, and study the phase structure of the
theory as a function of the size Lc of the compactified dimension. We show that
four different phases take place, corresponding to different realizations of
center symmetry: two center symmetric phases, for large or small values of Lc,
separated by two phases in which center symmetry is broken in two different
ways; the dependence of these results on the quark mass is discussed. We study
also chiral properties and how they are affected by the different realizations
of center symmetry; chiral symmetry, in particular, stays spontaneously broken
at the phase transitions and may be restored at much lower values of the
compactification radius. Our results could be relevant to a recently proposed
conjecture of volume indepedence of QCD with adjoint fermions in the large Nc
limit
On the Stability of Non-Abelian Semi-local Vortices
No full textWe study the stability of non-Abelian semi-local vortices based on an N=2
supersymmetric H = [SU(Nc) x U(1)]/Z_Nc = U(Nc) gauge theory with an arbitrary
number of flavors (Nf > Nc) in the fundamental representation, when certain N=1
mass terms are present, making the vortex solutions no longer BPS-saturated.
Local (ANO-like) vortices are found to be stable against fluctuations in the
transverse directions. Strong evidence is found that the ANO-like vortices are
actually the true minima. In other words, the semi-local moduli, which are
present in the BPS limit, disappear in our non-BPS system, leaving the vortex
with the orientational moduli CP(Nc-1) only. We discuss the implications of
this fact on the system in which the U(Nc) model arises as the low-energy
approximation of an underlying e.g. G = SU(Nc+1) gauge theory
Critical and multicritical behavior of the +- J Ising model in two and three dimensions
No full textWe report our Monte Carlo results on the critical and multicritical behavior
of the +- J Ising model [with a random-exchange probability P(J_{xy}) = p
\delta(J_{xy} - J) + (1-p) \delta(J_{xy} + J)], in two and three dimensions. We
study the transition line between the paramagnetic and ferromagnetic phase,
which extends from p=1 to a multicritical (Nishimori) point. By a finite-size
scaling analysis, we provide strong numerical evidence that in three dimensions
the critical behavior along this line belongs to the same universality class as
that of the critical transition in the randomly dilute Ising model. In two
dimensions we confirm that the critical behavior is controlled by the pure
Ising fixed point and that disorder is marginally irrelevant, giving rise to
universal logarithmic corrections. In both two and three dimensions, we also
determine the location of the multicritical Nishimori point, as well as the
renormalization-group dimensions of the operators that control the
renormalization-group flow close to it
Types and deadlock free sessions for SCC
No full textThe notion of a session is fundamental in service oriented applications, as it serves to separate interactions between different instances of the same services, and to group together logical units of work. Recently, SCC has been proposed as a calculus centered around the concept of a dyadic session, where service interaction protocols and service orchestration can be conveniently expressed. In this paper we propose a generic type system to collect services' behaviors and then we fix a class of well typed processes that are guaranteed to be deadlock free. The type system is based on previous research on traditional mobile calculi, here conveniently extended and simplified thanks to the neat discipline imposed by the linguistic primitives of SCC
A Linear Programming Model for Traffic Engineering in 100% Survivable Networks under combined IS-IS/OSPF and MPLS-TE Protocols
No full textThe paper concers the problem of minimizing the maximum link utilization of IP telecommunication networks under the joint use of the traditional IS-IS/OPSF protocol and the more sophisticated MPLS-TE technology. Both working conditions and single link failure scenarios are addressed. An innovative Linear Programming mathematical model is proposed that, while optimizing the network utilization, provides optimal user performance, efficient use of network resources, and 100\% survivability in case of single link failure. The hybrid approach takes advantage of both IGP and MPLS-TE technologies providing a flexible tool for IP networks traffic engineers. The proposed model is validated by a wide experimentation performed on synthetic and real networks, both in working and failure conditions. The obtained results show that the new approach considerably reduces the maximum utilization of the network, thereby allowing a more efficient use of the network resources; setting a limited number of LSPs yields better results than those obtained by simply optimizing the IGP weights. In addition, an optimized set of IGP weigths allows to further improve the network performance in case of failures. The computational time needed to solve the LP model is very limited and it well matches the real time requirements
Characterization of abrasive waterjet processed surfaces
No full textThis paper describes the effect of different abrasive waterjet (AWJ) process parameters on the aesthetical results, such as roughness, waviness, main texture direction, and enhancement of material defects of marble samples. Surfaces have been digitalized by optical profilometry. About one hundred samples of White Carrara and Perlato of Coreno have been characterized using standard surface parameters extracted from the digital surface profiles. Statistical analyses have shown the correlation with the main process parameters, particularly with the waterjet head angle. An interpretation of the aesthetical meaning of the surface parameters is also given in the paper