Continuous Matrix Product Ansatz for the One-Dimensional Bose Gas with Point Interaction

We study a matrix product representation of the Bethe ansatz state for the Lieb-Linger model describing the one-dimensional Bose gas with delta-function interaction. We first construct eigenstates of the discretized model in the form of matrix product states using the algebraic Bethe ansatz. Continuous matrix product states are then exactly obtained in the continuum limit with a finite number of particles. The factorizing $F$-matrices in the lattice model are indispensable for the continuous matrix product states and lead to a marked reduction from the original bosonic system with infinite degrees of freedom to the five-vertex model.Comment: 5 pages, 1 figur

A Unified Algebraic Approach to Few and Many-Body Correlated Systems

The present article is an extended version of the paper {\it Phys. Rev.} {\bf B 59}, R2490 (1999), where, we have established the equivalence of the Calogero-Sutherland model to decoupled oscillators. Here, we first employ the same approach for finding the eigenstates of a large class of Hamiltonians, dealing with correlated systems. A number of few and many-body interacting models are studied and the relationship between their respective Hilbert spaces, with that of oscillators, is found. This connection is then used to obtain the spectrum generating algebras for these systems and make an algebraic statement about correlated systems. The procedure to generate new solvable interacting models is outlined. We then point out the inadequacies of the present technique and make use of a novel method for solving linear differential equations to diagonalize the Sutherland model and establish a precise connection between this correlated system's wave functions, with those of the free particles on a circle. In the process, we obtain a new expression for the Jack polynomials. In two dimensions, we analyze the Hamiltonian having Laughlin wave function as the ground-state and point out the natural emergence of the underlying linear $W_{1+\infty}$ symmetry in this approach.Comment: 18 pages, Revtex format, To appear in Physical Review

Overexpression. of dehydrin tas14 gene improves the osmotic stress imposed by drought and salinity in tomato

[EN] One strategy to increase the level of drought and salinity tolerance is the transfer of genes codifying different types of proteins functionally related to macromolecules protection, such as group 2 of late embryogenesis abundant (LEA) proteins or dehydrins. The TAS14 dehydrin was isolated and characterized in tomato and its expression was induced by osmotic stress (NaCl and mannitol) and abscisic acid (ABA) [Godoy et al., Plant Mol Biol 1994;26:1921-1934], yet its function in drought and salinity tolerance of tomato remains elusive. In this study, transgenic tomato plants overexpressing tas14 gene under the control of the 35SCaMV promoter were generated to assess the function of tas14 gene in drought and salinity tolerance. The plants overexpressing tas14 gene achieved improved long-term drought and salinity tolerance without affecting plant growth under non-stress conditions. A mechanism of osmotic stress tolerance via osmotic potential reduction and solutes accumulation, such as sugars and K+ is operating in tas14 overexpressing plants in drought conditions. A similar mechanism of osmotic stress tolerance was observed under salinity. Moreover, the overexpression of tas14 gene increased Na+ accumulation only in adult leaves, whereas in young leaves, the accumulated solutes were K+ and sugars, suggesting that plants overexpressing tas14 gene are able to distribute the Na+ accumulation between young and adult leaves over a prolonged period in stressful conditions. Measurement of ABA showed that the action mechanism of tas14 gene is associated with an earlier and greater accumulation of ABA in leaves during short-term periods. A good feature for the application of this gene in improving drought and salt stress tolerance is the fact that its constitutive expression does not affect plant growth under non-stress conditions, and tolerance induced by overexpression of tas14 gene was observed at the different stress degrees applied to the long term. (C) 2011 Elsevier GmbH. All rights reserved.This work was supported by the Spanish Ministry of Science and Innovation through grant AGL2009-13388-C03 and by the Council of Science and Technology from the Region of Murcia (Spain) (Fundacion SENECA) through grant 04553/GERM/06.Muñoz Mayor, A.; Pineda Chaza, BJ.; García Abellán, JO.; Antón Martínez, MT.; García Sogo, B.; Sánchez Bel, P.; Flores, FB.... (2012). Overexpression. of dehydrin tas14 gene improves the osmotic stress imposed by drought and salinity in tomato. Journal of Plant Physiology. 169(5):459-468. https://doi.org/10.1016/j.jplph.2011.11.018S459468169

An Osmotic Model of the Growing Pollen Tube

Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip

Replication blocking lesions present a unique substrate for homologous recombination

Homologous recombination (HR) plays a critical role in the restart of blocked replication forks, but how this is achieved remains poorly understood. We show that mutants in the single Rad51 paralog in Caenorhabditis elegans, rfs-1, permit discrimination between HR substrates generated at DNA double-strand breaks (DSBs), or following replication fork collapse from HR substrates assembled at replication fork barriers (RFBs). Unexpectedly, RFS-1 is dispensable for RAD-51 recruitment to meiotic and ionizing radiation (IR)-induced DSBs and following replication fork collapse, yet, is essential for RAD-51 recruitment to RFBs formed by DNA crosslinking agents and other replication blocking lesions. Deletion of rfs-1 also suppresses the accumulation of toxic HR intermediates in him-6; top-3 mutants and accelerates deletion formation at presumed endogenous RFBs formed by poly G/C tracts in the absence of DOG-1. These data suggest that RFS-1 is not a general mediator of HR-dependent DSB repair, but acts specifically to promote HR at RFBs. HR substrates generated at conventional DSBs or following replication fork collapse are therefore intrinsically different from those produced during normal repair of blocked replication forks

In Vivo Biodistribution of Amino-Functionalized Ceria Nanoparticles in Rats Using Positron Emission Tomography

A variety of nanoparticles have been proposed for several biomedical applications. To gauge the therapeutic potential of these nanoparticles, in vivo biodistribution is essential and mandatory. In the present study, ceria nanoparticles (5 nm average particle size) were labeled with F-18 to study their in vivo biodistribution in rats by positron emission tomography (PET). The F-18 isotope was anchored by reaction of N-succinimidyl 4-[F-18]fluorobenzoate (F-18-SFB) with a modified nanoparticle surface obtained by silylation with 3-aminopropylsilyl. Radiolabeled ceria nanoparticles accumulated mainly in lungs, spleen, and liver. Metabolic products of the radiolabeled nanoparticulate material were excreted into the urinary tract.The present work was supported by the Spanish MICINN (Grants CTQ-2009-11586, CTQ2006-06785, and CTQ2007-67805-AR07, PI10/1195, AP192/11); the Fondo de Investigacion Sanitaria (FIS) of the Instituto de Salud Carlos III (Grants PS09/02620, PI10/1195, and PS09/02217), the Generalitat Valenciana (Grant ACOMP/2012/045), La Marato Fundation (Grant 090530), and by CDTI under the CENIT Programme (AMIT Project) and the Spanish Ministry of Science and Innovation. V.M.V. is a recipient of a contract from the Regional Ministry of Health of the Valencian Regional Government and Carlos III Health Institute (CES10/030).Rojas, S.; Domingo Gispert, J.; Abad Fuentes, S.; Buaki-Sogo, M.; Victor, VM.; García Gómez, H.; Herance Camacho, JR. (2012). In Vivo Biodistribution of Amino-Functionalized Ceria Nanoparticles in Rats Using Positron Emission Tomography. Molecular Pharmaceutics. 9(12):3543-3550. https://doi.org/10.1021/mp300382nS3543355091