Uso de las proteínas de reserva de megagametofito como marcador de la diversidad genética en Abies pinsapo

El pinsapo (Abies pinsapo Boiss.) se localiza exclusivamente en el sur de España, en las comarcas de Cádiz y Málaga, donde ocupa unas 5.000 ha. Diversos factores como la presencia de plagas y el decaimiento de las masas, de origen aún no determinado, hacen temer por el futuro de la especie. A todo ello hay que sumar la circunstancia de que es posible que se esté produciendo un estrechamiento de la base genética de la especie, debido a problemas de consanguinidad y deriva genética. Por esta razón, el desarrollo de una estrategia de conservación de la especie exige la evaluación de su diversidad genética. En este estudio, se han analizado la posibilidad de utilizar las proteínas del megagametofito de pinsapo como marcador de la diversidad genética de las masas de esta especie. La fracción albúminas ha mostrado la existencia de polimorfismo. Un análisis preliminar efectuado en 27 árboles, permitió identificar más de 41 bandas de las que, al menos 12 son polimórficas entre árboles y 8 dentro de árboles. Este resultado permite ser optimista sobre la posibilidad de emplear este marcador con la finalidad señalad

Dynamical variables in Gauge-Translational Gravity

Assuming that the natural gauge group of gravity is given by the group of isometries of a given space, for a maximally symmetric space we derive a model in which gravity is essentially a gauge theory of translations. Starting from first principles we verify that a nonlinear realization of the symmetry provides the general structure of this gauge theory, leading to a simple choice of dynamical variables of the gravity field corresponding, at first order, to a diagonal matrix, whereas the non-diagonal elements contribute only to higher orders.Comment: 15 page

Social security, retirement, and the single-mindedness of the electorate

We propose a positive theory that is consistent with two important features of social security programs around the world: (1) they redistribute income from young to old and (2) they induce retirement. We construct a voting model that includes a “political campaign” or “debate” prior to the election. The model incorporates “single-mindedness” of the groups that do not work: while the workers divide their political capital between their “age concerns” and “occupational concerns”, the retired concentrate all their political capital to support their age group. In our model, the elderly end up getting transfers from the government (paid by the young) and distortionary labor income taxes induce the retirement of the elderly. In addition, our model predicts that occupational groups that work more will tend to have more political power. The opposite is true for non-occupational groups (such as the elderly). We provide some evidence that supports these additional predictions.Social Security, retirement, retirement incentives, single-mindedness, political theories of Social Security

VALLE-INCLÁN, Ramón del: Tirano Banderas. Introducción y notas de Alonso Zamora Vicente

Sin resume

On The spectrum of a Noncommutative Formulation of the D=11 Supermembrane with Winding

A regularized model of the double compactified D=11 supermembrane with nontrivial winding in terms of SU(N) valued maps is obtained. The condition of nontrivial winding is described in terms of a nontrivial line bundle introduced in the formulation of the compactified supermembrane. The multivalued geometrical objects of the model related to the nontrivial wrapping are described in terms of a SU(N) geometrical object which in the $N\to \infty$ limit, converges to the symplectic connection related to the area preserving diffeomorphisms of the recently obtained non-commutative description of the compactified D=11 supermembrane.(I. Martin, J.Ovalle, A. Restuccia. 2000,2001) The SU(N) regularized canonical lagrangian is explicitly obtained. In the $N\to \infty$ limit it converges to the lagrangian in (I.Martin, J.Ovalle, A.Restuccia. 2000,2001) subject to the nontrivial winding condition. The spectrum of the hamiltonian of the double compactified D=11 supermembrane is discussed. Generically, it contains local string like spikes with zero energy. However the sector of the theory corresponding to a principle bundle characterized by the winding number $n \neq 0$, described by the SU(N) model we propose, is shown to have no local string-like spikes and hence the spectrum of this sector should be discrete.Comment: 16 pages.Latex2

The entangling side of the Unruh-Hawking effect

We show that the Unruh effect can create net quantum entanglement between inertial and accelerated observers depending on the choice of the inertial state. This striking result banishes the extended belief that the Unruh effect can only destroy entanglement and furthermore provides a new and unexpected source for finding experimental evidence of the Unruh and Hawking effects.Comment: 4 pages, 4 figures. Added Journal referenc

Magnetic Field Effects on the Transport Properties of One-sided Rough Wires

We present a detailed numerical analysis of the effect of a magnetic field on the transport properties of a `small-$N$' one-sided surface disordered wire. When time reversal symmetry is broken due to a magnetic field $B$, we find a strong increase with $B$ not only of the localization length $\xi$ but also of the mean free path $\ell$ caused by boundary states. Despite this, the universal relationship between $\ell$ and $\xi$ does hold. We also analyze the conductance distribution at the metal-insulator crossover, finding a very good agreement with Random Matrix Theory with two fluctuating channels within the Circular Orthogonal(Unitary) Ensemble in absence(presence) of $B$Comment: 5 pages, 4 figures, to appear in Phys. Rev.

Structural Stability of Short Latency Alfalfa-Based Pastures in the Humid Pampa, Argentina

The aim of this study was to search the effects of grazing intensity and nitrogen fertilization on the structural stability of a mixed pasture composed by alfalfa (latency group 9), brome grass, tall fescue and white clover, sown in April 1997. Rotational grazing was carried out with dairy cattle with high intensity (HI: up to 3-4 cm) or moderate intensity (LI: up to 8-10 cm), whenever the alfalfa showed basal regrowth. According to a split-plot design, grazing intensities were subdivided to assign three levels of nitrogen fertilization: N0, without fertilization; N1 with 50 kg N/ha per year; and N2 with 100 kg N/ha per year, its supplied at the beginning of autumn and at the end of winter. The botanical composition (%), module density (number per m2) and basal cover (%) before grazing were measured from September 1997 through December 1999. After 20 grazing periods the use intensity affected significantly (p\u3c 0.05) all the variables, while N had minor effect. The average alfalfa content changed from 46.8% to 11.0% in HI, and 25.0% in LI in November 1999; fescue from 15.3% to 5.3% and 36% respectively; brome grass from 28.1% to 65% and 21.7% respectively; and perennial weeds from 4.3% to 8.3% and 6.3% respectively; the rest being dead material. The white clover practically disappeared during the drought of the second summer. The pasture basal cover showed an evolution from 21% to 20.7% in HI and 95% in LI in December 1999; the weed Bermuda grass from 15% to 68.8% and 3.3%, respectively, and the bare soil from 63.9% to 8.2% and 0.5%, respectively. The total module density of alfalfa, tall fescue and brome grass was dramatically reduced from a global mean of 577 mod per m2 to 79 in HI and 152 in LI