Gauge invariant fluctuations of the metric during inflation from new scalar-tensor Weyl-Integrable gravity model

We investigate gauge invariant scalar fluctuations of the metric during inflation in a non-perturbative formalism in the framework of a recently introduced scalar-tensor theory of gravity formulated on a Weyl-Integrable geometry. We found that the Weyl scalar field can play the role of the inflaton field in this theory. As an application we study the case of a power law inflation. In this case the quasi-scale invariance of the spectrum for scalar fluctuations of the metric is achieved for determined values of the $\omega$ parameter of the scalar-tensor theory. In our formalism the physical inflaton field has a geometrical origin.Comment: 9 pages, no figures. This is a revised version accepted for publication in Physical Review

Determination of Soluble Sugars in Arabidopsis thaliana Leaves by Anion Exchange Chromatography

Determination of soluble sugars is basic for the study of carbon metabolism in plants. Soluble sugar quantitation can be achieved by enzymatic methods implying different coupled reactions. Here we describe a simple method that allows rapid determination of the most abundant soluble sugars (glucose, fructose and sucrose) in Arabidopsis leaves by anion exchange chromatography. We have applied this method to study the levels of soluble sugars during the photoperiodic transition to flowering (Ortiz-Marchena et al., 2014).España, MINECO projects CSD2007-00057, BIO2008-02292, and BIO2011-28847-C02-00España, Junta de Andalucía P06-CVI-01450 and P08-AGR-0358

Nonsymmetric moving breather collisions in the Peyrard-Bishop DNA model

We study nonsymmetric collisions of moving breathers (MBs) in the Peyrard-Bishop DNA model. In this paper we have considered the following types of nonsymmetric collisions: head-on collisions of two breathers traveling with different velocities; collisions of moving breathers with a stationary trapped breather; and collisions of moving breathers traveling with the same direction. The various main observed phenomena are: one moving breather gets trapped at the collision region, and the other one is reflected; breather fusion without trapping, with the appearance of a new moving breather; and breather generation without trapping, with the appearance of new moving breathers traveling either with the same or different directions. For comparison we have included some results of a previous paper concerning to symmetric collisions, where two identical moving breathers traveling with opposite velocities collide. For symmetric collisions, the main observed phenomena are: breather generation with trapping, with the appearance of two new moving breathers with opposite velocities and a stationary breather trapped at the collision region; and breather generation without trapping, with the appearance of new moving breathers with opposite velocities. A common feature for all types of collisions is that the collision outcome depends on the internal structure of the moving breathers and the exact number of pair-bases that initially separates the stationary breathers when they are perturbed. As some nonsymmetric collisions result in the generation of a new stationary trapped breather of larger energy, the trapping phenomenon could play an important part of the complex mechanisms involved in the initiation of the DNA transcription processes.MICIN

Blue organic seven segment display based on poly (9,9-dioctyfluorene)with β-phase emission

In this work, organic seven segment displays based on poly(9,9-dioctyfluorene), PFO, have been fabricated. PFO has consolidated as an attractive material for PLEDs due to its efficient blue emission [1] and high hole mobility. Additionally, PFO has a particular conformation, called β-phase associated to extended PFO chain conformation, which is of great interest for potential device applications because, among all others, it has the highest photoluminescence quantum efficiency [2] and the best colour stability [3]. The structure fabricated uses Indium Tin Oxide (ITO) as anode, Poly(3,4 -ethylenedioxythiophene) /poly(4- styrenesulfonate) (PEDOT:PSS) as hole transport layer and Ba:Al as cathode. After thoroughly cleaning the substrates (covered with ITO) a photolithography process is carried out in order to pattern the anode. Next, the organic layers (PEDOTT:PSS and PFO) are spin casted. Finally, metals (Ba~30 nm and Al~100 nm) are thermally evaporated in an atmosphere of 6x10 -6 Torr. PFO is dissolved in toluene at 1 % wt. A detailed description of the fabrication process can be found in [4]. Finally, the device is encapsulated (using an epoxy and a glass tap) and contacts are indium soldered on the pads. In figure 1, we can observe the shadow mask used for the anode photolitography process (left) and the final device lighting in a zero configuration (right)