Entanglement of Dirac fields in an expanding spacetime

We study the entanglement generated between Dirac modes in a 2-dimensional conformally flat Robertson-Walker universe. We find radical qualitative differences between the bosonic and fermionic entanglement generated by the expansion. The particular way in which fermionic fields get entangled encodes more information about the underlying space-time than the bosonic case, thereby allowing us to reconstruct the parameters of the history of the expansion. This highlights the importance of bosonic/fermionic statistics to account for relativistic effects on the entanglement of quantum fields.Comment: revtex4, 7 figures, I.F. previously published as Fuentes-Guridi and Fuentes-Schuller. Journal reference update

On the mechanical properties of N-functionalised dipeptide gels

The properties of a hydrogel are controlled by the underlying network that immobilizes the solvent. For gels formed by the self-assembly of a small molecule, it is common to show the primary fibres that entangle to form the network by microscopy, but it is difficult to access information about the network. One approach to understand the network is to examine the effect of the concentration on the rheological properties, such that G cx, where G is the storage modulus and c is the concentration. A number of reports link the exponent x to a specific type of network. Here, we discuss a small library of gels formed using functionalized dipeptides, and describe the underlying networks of these gels, using microscopy, small angle scattering and rheology. We show that apparently different networks can give very similar values of x

Effects of three-body collisions in a two-mode Bose-Einstein condenstate

We study the effects of three-body collisions in the basic physical properties of a two-mode Bose-Einstein condensate. By finding the exact analytical solution of a model which includes two-body and three-body elastic and mode-exchange collisions, we show analytically that three-body interactions produce observable effects in the probability distribution of the ground state and the dynamics of the relative population. In particular, we find that three-body interactions under certain circumstances inhibit collapse of the relative population.Comment: 5 pages, 3 figures. I.F. previously published as I. Fuentes-Schuller and I. Fuentes-Guridi. v2:minor changes, published versio

A novel two-phase bioprocess for the production of Arthrospira (Spirulina) maxima LJGR1 at pilot plant scale during different seasons and for phycocyanin induction under controlled conditions

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions, was evaluated using a modified low-cost Zarrouk medium. Growth was monitored during 4 cycles in 2018 and 4 cycles in 2019. Biomass was harvested and concentrated using membrane technology at the end of each cycle for further phycocyanin induction using blue LED light (controlled conditions, 24h). The highest biomass productivity was observed during spring and summer cycles; during mid-fall and mid-end fall, a decrease was observed. Under favorable growth conditions, phycocyanin induction was successful. However, during cycles with unfavorable growth condition, phycocyanin induction was not observed. Reagent grade phycocyanin was recovered and purified using microfiltration and ultrafiltration technologies. It was concluded that this novel two phase process has a potential to be implemented at larger scale within a biorefinery approach including the production of sub products from residual biomass and exopolysaccharides

Berry Phase Quantum Thermometer

We show how Berry phase can be used to construct an ultra-high precision quantum thermometer. An important advantage of our scheme is that there is no need for the thermometer to acquire thermal equilibrium with the sample. This reduces measurement times and avoids precision limitations.Comment: Updated to published version. I. Fuentes previously published as I. Fuentes-Guridi and I. Fuentes-Schulle

Finite Element Analysis of Membrane Structures

This paper summarizes the development for a large displacement formulation of a membrance composed of three-node triangular elements. A formulation in terms of the deformation gradient is first constructed in terms of nodal variables. In particular, the use of the right Cauchy-Green deformation tensor is shown to lead to a particulary simple representation in terms of nodal quantities. This may then be used to construct general models for use in static and transient analyses

Hysteresis Heating of Railroad Bearing Thermoplastic Elastomer Suspension Element

Thermoplastic elastomers (TPE’s) are increasingly being used in rail service in load damping applications. They are superior to traditional elastomers primarily in their ease of fabrication. Like traditional elastomers they offer benefits including reduction in noise emissions and improved wear resistance in metal components that are in contact with such parts in the railcar suspension system. However, viscoelastic materials, such as the railroad bearing thermoplastic elastomer suspension element (or elastomeric pad), are known to develop self-heating (hysteresis) under cyclic loading, which can lead to undesirable consequences. Quantifying the hysteresis heating of the pad during operation is therefore essential to predict its dynamic response and structural integrity, as well as, to predict and understand the heat transfer paths from bearings into the truck assembly and other contacting components. This study investigates the internal heat generation in the suspension pad and its impact on the complete bearing assembly dynamics and thermal profile. Specifically, this paper presents an experimentally validated finite element thermal model of the elastomeric pad and its internal heat generation. The steady-state and transient-state temperature profiles produced by hysteresis heating of the elastomer pad are developed through a series of experiments and finite element analysis. The hysteresis heating is induced by the internal heat generation, which is a function of the loss modulus, strain, and frequency. Based on previous experimental studies, estimations of internally generated heat were obtained. The calculations show that the internal heat generation is impacted by temperature and frequency. At higher frequencies, the internally generated heat is significantly greater compared to lower frequencies, and at higher temperatures, the internally generated heat is significantly less compared to lower temperatures. However, during service operation, exposure of the suspension pad to higher loading frequencies above 10 Hz is less likely to occur. Therefore, internal heat generation values that have a significant impact on the suspension pad steady-state temperature are less likely to be reached. The commercial software package ALGOR 20.3TM is used to conduct the thermal finite element analysis. Different internal heating scenarios are simulated with the purpose of obtaining the bearing suspension element temperature distribution during normal and abnormal conditions. The results presented in this paper can be used in the future to acquire temperature distribution maps of complete bearing assemblies in service conditions and enable a refined model for the evolution of bearing temperature during operation

Detección de objetos abandonados

La detección de objetos abandonados es una de las áreas de interés en el ámbito de visión por computador, cuyo fin es evitar situaciones catastróficas. Para solucionar este problema han surgido investigaciones que incluyen una etapa de seguimiento. El algoritmo que se expone aquí deja de lado esta etapa para darle paso a un sistema basado en un modelo de fondo dual adaptativo, con el fin de obtener una implementación con bajo costo computacional, que detecte objetos abandonados en espacios interiores.Ingeniero (a) ElectrónicoPregrad

Revealing the remarkable structural diversity of the alkali metal transfer agents of the trans-calix[2]benzene[2]pyrrolidide ligand

Excellent reagents for transferring their heterocalix[4]arene ligand to f-block organometallic complexes, lithium, sodium and potassium trans-calix[2]benzene[2]pyrrolidides have been found to adopt a fascinating series of structures in their own right