253 research outputs found

    Reply to: Comment on `Long-range electrostatic interactions between like-charged colloids: steric and confinement effects'

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    In his Comment (cond-mat/0104060) to [Phys. Rev. E 60, 6530 (1999)], Mateescu shows that while the effective interactions remain repulsive when the specific size of the micro-ions is taken into account via a Modified Poisson-Boltzmann equation, a similar conclusion cannot be reached for the situation of complete lateral confinement. This point is correct but has already been considered in a more general study [Phys. Rev. E 62, R1465 (2000), where repulsion is generically obtained]; moreover, we argue that it illustrates the irrelevancy of the notion of pair potential in completely confined configurations, as shown on a simple example

    USE OF AN INNOVATIVE METHOD FOR STRUCTURAL ANALYSIS OF THE DISTRIBUTION DEVICE USED IN PNEUMATIC MACHINES FOR WEEDING PLANT SOWING

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    The topic addressed is a computer-aided design (CAD) method combined with computer-aided engineering (CAE) used in the analysis of choosing the optimal constructive variant of the distribution device used in pneumatic machines for weeding plant sowing. The CAD configurations, realized by the 3D parametric modeling using the SolidWorks program, were subjected to structural analysis (von Mises equivalent stress distribution, relative displacement field distribution and safety factor). Based on the resulting data, the mass/resistance coefficient for the 3 analyzed configurations were determined. The comparison of these indicators led to the choice of the optimal constructive variant, namely the most efficient one

    Organized condensation of worm-like chains

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    We present results relevant to the equilibrium organization of DNA strands of arbitrary length interacting with a spherical organizing center, suggestive of DNA-histone complexation in nucleosomes. We obtain a rich phase diagram in which a wrapping state is transformed into a complex multi-leafed, rosette structure as the adhesion energy is reduced. The statistical mechanics of the "melting" of a rosette can be mapped into an exactly soluble one-dimensional many-body problem.Comment: 15 pages, 2 figures in a pdf fil

    CAD-CAE METHOD FOR STRUCTURAL ANALYSIS OF THE WELDED FRAME WITHIN THE COMPONENT OF A SEED DRILL USED FORDIRECTLY SOWING STRAW CEREALS

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    This paper presents a Computer Assisted Design (CAD) method combined with computer-aided engineering (CAE) used in the analysis of choosing the constructive variant of the welded frame from within the component of a seed drill used fordirectly sowing straw cereals, so that the ratio between the consumption of material for the construction structure per unit of safety coefficient to be minimal and the carrying capacity to be maximal. For this purpose 3D modeling with SolidWorks software has effectively managed three dimensional configurations of the welded frame using Design Table. The three configurations were subjected to structural analysis (the von Mises equivalent of the tension field distribution, the relative displacement of field distribution and the safety coefficient). Based on the resulting data, the mass / resistance ratios for the three configurations analyzed were determined. The comparison of these indicators led to the choice of the optimal constructive variant in the most efficient way. The presented method contributes to reducing the design validation time by eliminating physical performance and testing

    Comment on "Long-range electrostatic interactions between like-charged colloids: Steric and confinement effects"

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    In a recent study [Phys. Rev. E 60, 6530 (1999)], Trizac and Raimbault showed that the effective pair interaction between like charged colloids immersed in a cylindrically confined electrolyte remains repulsive even when the size of the micro-ions or the finite longitudinal extension of the confining cylinder are taken into account. Contrary to their claim, we argue that the case of finite longitudinal confinement doesn't always generate repulsive interactions and to illustrate this point we also provide a simple example.Comment: 3 pages, 1 figure. Accepted for publication in Phys. Rev. E 200

    ECO-INNOVATIVE SYSTEM PROVIDED WITH "DEFLECTOR" TO REDUCE POWDER EMISSIONS AT HOEING PLANTS SOWING

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    This paper presents experimental research carried out by INMA Bucharest for the implementation of measures to reduce particulate matter emissions from seeds treated with plant protection chemicals during sowing crops. The work is justified by stringent national and European requirements to increase the capacity and capability of the R & D system in the agricultural field by promoting and supporting the development of eco-innovative systems to mitigate the risks associated with the use of plant protection products

    Conformation of a Polyelectrolyte Complexed to a Like-Charged Colloid

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    We report results from a molecular dynamics (MD) simulation on the conformations of a long flexible polyelectrolyte complexed to a charged sphere, \textit{both negatively charged}, in the presence of neutralizing counterions in the strong Coulomb coupling regime. The structure of this complex is very sensitive to the charge density of the polyelectrolyte. For a fully charged polyelectrolyte the polymer forms a dense two-dimensional "disk", whereas for a partially charged polyelectrolyte the monomers are spread over the colloidal surface. A mechanism involving the \textit{overcharging} of the polyelectrolyte by counterions is proposed to explain the observed conformations.Comment: 4 pages, 4 figures (6 EPS files

    Analysis and Verification of Service Interaction Protocols - A Brief Survey

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    Modeling and analysis of interactions among services is a crucial issue in Service-Oriented Computing. Composing Web services is a complicated task which requires techniques and tools to verify that the new system will behave correctly. In this paper, we first overview some formal models proposed in the literature to describe services. Second, we give a brief survey of verification techniques that can be used to analyse services and their interaction. Last, we focus on the realizability and conformance of choreographies.Comment: In Proceedings TAV-WEB 2010, arXiv:1009.330

    A model of inversion of DNA charge by a positive polymer: fractionization of the polymer charge

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    Charge inversion of a DNA double helix by an oppositely charged flexible polyelectrolyte (PE) is considered. We assume that, in the neutral state of the DNA-PE complex, each of the DNA charges is locally compensated by a PE charge. When an additional PE molecule is adsorbed by DNA, its charge gets fractionized into monomer charges of defects (tails and arches) on the background of the perfectly neutralized DNA. These charges spread all over the DNA eliminating the self-energy of PE. This fractionization mechanism leads to a substantial inversion of the DNA charge, a phenomenon which is widely used for gene delivery.Comment: 4 pages, 2 figures. Improved figures and various corrections to tex

    Site-Directed Insertion: Decision Problems, Maximality and Minimality

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    Site-directed insertion is an overlapping insertion operation that can be viewed as analogous to the overlap assembly or chop operations that concatenate strings by overlapping a suffix and a prefix of the argument strings. We consider decision problems and language equations involving site-directed insertion. By relying on the tools provided by semantic shuffle on trajectories we show that one variable equations involving site-directed insertion and regular constants can be solved. We consider also maximal and minimal variants of the site-directed insertion operation
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