Size and scaling in ideal polymer networks

The scattering function and radius of gyration of an ideal polymer network are calculated depending on the strength of the bonds that form the crosslinks. Our calculations are based on an {\it exact} theorem for the characteristic function of a polydisperse phantom network that allows for treating the crosslinks between pairs of randomly selected monomers as quenched variables without resorting to replica methods. From this new approach it is found that the scattering function of an ideal network obeys a master curve which depends on one single parameter $x= (ak)^2 N/M$, where $ak$ is the product of the persistence length times the scattering wavevector, $N$ the total number of monomers and $M$ the crosslinks in the system. By varying the crosslinking potential from infinity (hard $\delta$-constraints) to zero (free chain), we have also studied the crossover of the radius of gyration from the collapsed regime where R_{\mbox{\tiny g}}\simeq {\cal O}(1) to the extended regime R_{\mbox{\tiny g}}\simeq {\cal O}(\sqrt{N}). In the crossover regime the network size R_{\mbox{\tiny g}} is found to be proportional to $(N/M)^{1/4}$.Comment: latex, figures available on request, to be published: J. Phys I Franc

Langevin Dynamics of a Polymer with Internal Distance Constraints

We present a novel and rigorous approach to the Langevin dynamics of ideal polymer chains subject to internal distance constraints. The permanent constraints are modelled by harmonic potentials in the limit when the strength of the potential approaches infinity (hard crosslinks). The crosslinks are assumed to exist between arbitrary pairs of monomers. Formally exact expressions for the resolvent and spectral density matrix of the system are derived. To illustrate the method we study the diffusional behavior of monomers in the vicinity of a single crosslink within the framework of the Rouse model. The same problem has been studied previously by Warner (J. Phys. C: Solid State Phys. {\bf 14}, 4985, (1981)) on the basis of Lagrangian multipliers. Here we derive the full, hence exact, solution to the problem.Comment: To appear in PRE, Figures on reques

La conciliación extrajudicial en temas de familia (Ley Nº 29876 que modifica la ley Nº 26872 y el D.L. 1070)

En el presente trabajo se pretende establecer la relación existente entre los derechos disponibles en materia de familia y la vulneración de los derechos de terceros, en este caso, menores de edad, quienes son los que a través de sus padres son representados al no tener capacidad jurídica. Sin embargo, podría darse el caso de vulnerar sus derechos e interés del menor al disponer de sus derechos. Es necesario regular normativamente estas posibilidades y definir la libre disposición de derechos que es la pieza fundamental de los sistemas alternativos

Collapse of Randomly Linked Polymers

We consider polymers in which M randomly selected pairs of monomers are restricted to be in contact. Analytical arguments and numerical simulations show that an ideal (Gaussian) chain of N monomers remains expanded as long as M<<N. This result is inconsistent with results obtained from free energy considerations by Brygelson and Thirumalai (PRL76, 542 (1996)).Comment: 1 page, 1 postscript figure, LaTe

Outer jet X-ray and radio emission in R Aquarii: 1999.8 to 2004.0

Chandra and VLA observations of the symbiotic star R Aqr in 2004 reveal significant changes over the three to four year interval between these observations and previous observations taken with the VLA in 1999 and with Chandra in 2000. This paper reports on the evolution of the outer thermal X-ray lobe-jets and radio jets. The emission from the outer X-ray lobe-jets lies farther away from the central binary than the outer radio jets, and comes from material interpreted as being shock heated to ~10^6 K, a likely result of collision between high speed material ejected from the central binary and regions of enhanced gas density. Between 2000 and 2004, the Northeast (NE) outer X-ray lobe-jet moved out away from the central binary, with an apparent projected motion of ~580 km s^-1. The Southwest (SW) outer X-ray lobe-jet almost disappeared between 2000 and 2004, presumably due to adiabatic expansion and cooling. The NE radio bright spot also moved away from the central binary between 2000 and 2004, but with a smaller apparent velocity than of the NE X-ray bright spot. The SW outer lobe-jet was not detected in the radio in either 1999 or 2004. The density and mass of the X-ray emitting material is estimated. Cooling times, shock speeds, pressure and confinement are discussed.Comment: 23 pages, 8 figure

Los efectos de la homologación de la transacción extrajudicial Análisis Casatorio: casación nº 3435-2009-arequipa

La transacción es un medio de solución de conflictos, mediante el cual las partes autocomponen sus diferencias, a través de concesiones recíprocas, con ahorro de tiempo y gastos, aliviando la carga procesal. Pese a ello y a la notoria relevancia social y jurídica que dicha institución posee, se advierte que no se ha comprendido su verdadero contenido. Razón por la cual, a continuación se realizará un breve análisis acerca de las implicancias jurídicas que posee en nuestro ordenamiento. Posteriormente, se comparará la transacción extrajudicial y judicial, junto con la homologación y los efectos como cosa juzgada. Por último, se realizará un análisis sobre la Casación Nº 3435-2009-Arequipa

Diskurspragmatische Faktoren für Topikalität und Verbstellung in der ahd. Tatianübersetzung (9. Jh.)

The paper presents work in progress on the interaction between information structure and word order in Old High German based on data from the Tatian translation (9th century). The examination of the position of the finite verb in correspondence with the pragmatic status of discourse referents reveals an overall tendency for verb-initial order in thetic/all-focus sentences, whereas in categorical / topic-comment sentences verb-second placement with an initial topic constituent is preferred. This conclusion provides support for the hypothesis stated in Donhauser & Hinterhölzl (2003) that the finite verb form in Early Germanic serves to distinguish the information-structural domains of Topic and Focus. Finally, the investigation sheds light on the process of language change that led to the overall spread of verb-second in main clauses of modern German

Temporär reduzierte Bodenbearbeitung: Kann das Unkrautaufkommen in Ackerbohnen durch Gemengeanbau oder Striegeln nachhaltig reduziert werden?

Reduzierte Bodenbearbeitung kann auch unter den Bedingungen des Ökologischen Landbaus zur Einsparung fossiler Brennstoffe beitragen. Ein nachhaltiges Unkrautmanagement ist jedoch erforderlich. Es ist daher ein Ziel unseres Projektes, die Unkrautregulierung durch den Vergleich eines direkten (Rollstriegel) mit einem indirekten Verfahren (Gemengeanbau von Ackerbohnen mit Hafer) zu verbessern. In einem Feldversuch am Standort Göttingen-Reinshof zeigten beide Methoden im Mai und Juni 2014 gute Ergebnisse. Der Feldversuch wird 2014 bzw. 2015 wiederholt (2014: Gerste, Zwischenfrüchte; 2015: Ackerbohnen/Hafer)

The ultraviolet spectrum of HH 24A and its relation to optical spectra

The spectrum of the brightest part (HH 24A) of the complex Herbig-Haro object HH 24 in the short wavelength UV range was studied. The object is of special interest since it is known that in the optical range the continuum is due to dust scattered light originating in a young stellar object while the shock excited emission lines are formed in HH 24A itself. The spectrum shows only a continuum or a quasi-continuum and is not comparable to that of the typical high excitation object like HH1 or HH2 nor to that of a low excitation object like HH3 or HH47