Classical and quantum exact solutions for a FRW multi-scalar field cosmology with an exponential potential driven inflation

A flat Fiedmann-Robertson-Walker (FRW) multi-scalar field cosmology is studied with a particular potential of the form $\rm V(\phi,\sigma)=V_0 e^{-\lambda_1 \phi-\lambda_2 \sigma}$, which emerges as a relation between the time derivatives of the scalars field momenta. Classically, by employing the Hamiltonian formalism of two scalar fields $\rm(\phi,\sigma)$ with standard kinetic energy, exact solutions are found for the Einstein-Klein-Gordon (EKG) system for different scenarios specified by the parameter $\rm\lambda^2=\lambda_1^2+\lambda_2^2$, as well as the e-folding function $\rm N_{e}$ which is also computed. For the quantum scheme of this model, the corresponding Wheeler-DeWitt (WDW) equation is solved by applying an appropriate change of variables.Comment: Latex file, accepted in Advances and Mathematical physics, Hindawi. arXiv admin note: text overlap with arXiv:1806.0119

SemTab 2019: Resources to Benchmark Tabular Data to Knowledge Graph Matching Systems

Tabular data to Knowledge Graph matching is the process of assigning semantic tags from knowledge graphs (e.g., Wikidata or DBpedia) to the elements of a table. This task is a challenging problem for various reasons, including the lack of metadata (e.g., table and column names), the noisiness, heterogeneity, incompleteness and ambiguity in the data. The results of this task provide significant insights about potentially highly valuable tabular data, as recent works have shown, enabling a new family of data analytics and data science applications. Despite significant amount of work on various flavors of this problem, there is a lack of a common framework to conduct a systematic evaluation of state-of-the-art systems. The creation of the Semantic Web Challenge on Tabular Data to Knowledge Graph Matching (SemTab) aims at filling this gap. In this paper, we report about the datasets, infrastructure and lessons learned from the first edition of the SemTab challenge

Diámetro del cuerpo lúteo y niveles de progesterona sérica, durante el ciclo estral en yeguas criollas colombianas

Objetivo. Determinar el diámetro del cuerpo lúteo (CL) y los niveles séricos de progesterona (P4) durante el ciclo estral (CE) en yeguas Criollas Colombianas (CC). Materiales y métodos. Se utilizaron 30 yeguas entre 4 a 14 años de edad, ubicadas en Pereira (Colombia). Se realizó ultrasonografía transrectal diariamente, desde la ovulación (día cero), durante dos CE para evaluar el diámetro del CL. Se tomaron muestras de sangre cada 48 horas entre una ovulación y la siguiente para cuantificar niveles séricos de P4 por la técnica de radioinmunoanálisis (RIA). Los datos fueron analizados con estadística descriptiva, desviación estándar, t de Student para determinar diferencias entre los CE y una prueba de correlación entre el diámetro del CL y P4. Resultados. El tamaño del CL durante el CE fue 18.3 ± 5.9 mm (promedio ± desviación estándar). El diámetro el día cero fue 25.1±4.5 mm y el tamaño final del CL 8.5±0.9 mm el día 20 del CE. El mayor diámetro se encontró el día 2 postovulación (26.4±5.0 mm). Los niveles máximos de P4 se encontraron al día 6 postovulación (10.7±4.3 rango 2.51 a 18.8 ng/ml). La concentración de P4 durante el diestro fue 6.6±3.6 (1.15 a 10.7 ng/ml) y durante el estro 0.25±0.3 (0.01m a 0.86 ng/ml). Conclusiones. La yegua CC presenta una dinámica del CL similar a la reportada en la literatura. Los valores aquí reportados pueden ser el punto de partida para establecer valores de referencia de utilidad clínica

Reversal of gulf stream circulation in a vertically vibrated triangular fluidized bed

Vibrated fluidized beds are a process intensification technique consisting in introducing vibratory kinetic energy in a fluidized bed (1). In this work we assess experimentally the effect of vibration on the gulf-stream circulation pattern of particles in a fluidized bed that is of triangular shape. The bed has 0.206 m span and 0.01 m thickness. The base of the bed is composed of two inclined walls, each one forming an angle of 45º with the horizontal. Air was injected through the inclined bed walls to fluidize the bed (see Figure 1a). This gas injection, together with vibration, can make the dynamics of this bed different to that found in a spouted fluidized bed (2). The bed is filled with ballotini particles with a mean diameter of 1.15 mm up to the top of the inclined walls. The bed vessel is made of antistatic PMMA to allow optical access with a high-speed camera. The bed was mounted on an electrodynamic shaker which produces the vibration. A high speed camera is used to record the motion of particles. The particle velocity was obtained via Particle Image Velocimetry (PIV). As a function of vibration amplitude and frequency, we observe several circulation patterns when the fluidization velocity is just below and above the minimum fluidization velocity. Noticeably, for zero gas velocity, particles ascend close to the side walls descend in the center of the bed. By injecting fluidization gas, the circulation pattern of the bed could be reversed (i.e. particles descending near the side walls ascend in the center of the bed) for certain conditions. For example, reversal of the gulf stream circulation of particles appeared in the triangular bed for gas superficial velocities higher than the minimum fluidization velocity and sufficiently high values of the vibration strength. This phenomenon is illustrated in Figure 1b in which, for the same vibrating conditions, the injection of gas superficial velocity through the walls reverses the gulf stream motion of particles in the bed. REFERENCES R. Gupta, A.S. Mujumdar, Hydrodynamic of vibrated fluidized bed, Can. J. Chem. Eng., 58:332-338, 1980. Vinayak S. Sutkar, Niels G. Deen, J.A.M. Kuipers, Spout fluidized beds: Recent advances in experimental and numerical studies, Chem. Eng. Sci., 86:124:136, 2013. Please click Additional Files below to see the full abstract

Job resources and recovery experiences to face difficulties in emotion regulation at work: a diary study among nurses

The present study examines the role of daily difficulties in emotion regulation at work in nurse’s daily well-being and how certain job resources and recovery experiences influence this relationship. We hypothesized that daily difficulties to regulate emotions at work would be significantly and positively related to emotional exhaustion at work in the afternoon, and to fatigue and negative affect at home at night. Moreover, we hypothesized that co-worker and supervisor support, as well as psychological detachment and relaxation, would buffer the negative impact of these difficulties on the outcomes. Seventy-four nurses from various Spanish hospitals and primary health care centres completed a general questionnaire and a diary booklet over 5 consecutive workdays at two different moments, after work and at night (N = 74 participants and N = 370 observations). The results of multilevel analyses showed that nurses’ daily difficulties in emotion regulation have a direct effect on daily emotional exhaustion at work, and on fatigue and negative affect at home at night. We also found that co-worker support, psychological detachment and relaxation minimize the unfavourable effects on well-being of difficulties in emotion regulation. Limitations and implications for nursing and other health occupations are mentionedThis research was supported by a grant Formación de Profesorado Universitario (FPU) from the Spanish Ministry of Education and by a project from the Spanish Ministry of Economy and Competitiveness (FEM2012-34692

Segregation of equal-sized particles of different densities in a vertically vibrated fluidized bed

Many operations in the chemical and energy-conversion industries rely on the fluidization of heterogeneous materials. During fluidization, particles of different densities can segregate, even if they are of the same size. Segregation is typically an undesired phenomenon, especially in fluidized bed reactors (1). Thus, an understanding of segregation on a fundamental level is paramount to identify effective measures to control it. One approach to control segregation could be the vibration of the bed vessel. However, there is very little literature available concerning the effect of vibration on density-induced segregation dynamics (2). Thus, this work studies the influence of vibration on density-induced segregation dynamics in a gas fluidized bed. Experiments were carried out in a pseudo-2D bed of 0.2 m width, 0.5 m height and 0.01 m thickness. The bed was filled with black, ballotini spheres (density 2500 kg/m3) mixed with heavier, white, ceramic particles (density 4100 kg/m3 and 6000 kg/m3). All particles have an average diameter of 1.1 mm. The bed was fluidized by air and vibrated by an electrodynamic shaker. High-speed images were recorded through the transparent front wall of the bed. Digital Image Analysis (DIA) was used to characterize the rate and extent of particle mixing with time (see Figure 1). At the start of the experiments the particles were mixed. The results obtained indicate that both the vibration strength and the gas velocity have an important effect on both the rate and the maximum degree of segregation of particles. We observed that particles become segregated for fluidization velocities greater than the minimum fluidization velocity of the denser particles. Adding vertical vibration to this system tended to enhance density-induced segregation. Interestingly, we found that, for sufficiently high vibration strengths, the degree of segregation decreased with vibration. These results indicate that by a judicious choice of the vibration strength and the fluidization velocity density-induced segregation can be controlled. REFERENCES W-C. Yang, Handbook of fluidization and fluid-particle systems, CRC Press, 2003. L. Sun, F. Zhao, Q. Zhang, D. Li, H. Lu, Numerical simulation of particle segregation in vibration fluidized bed, Chem. Eng. Technol., 37(12):2109-2115, 2014. Please click Additional Files below to see the full abstract

Vulnerability of Subaerial and Submarine Landscapes: The Sand Falls in Cabo San Lucas, Mexico

The coastal landscape of the south of the Baja California peninsula provides significant socio-economic benefits based on tourism. An analysis of coastal vulnerability was conducted for Cabo San Lucas, considering wave climate conditions, sediment characterization, beach profiles, and the historical occurrence of coastline changes, hurricanes, and El Nino Southern Oscillation (ENSO) events. The coastal scenery was also classified considering the landscape value of the environment from a touristic point of view, based on human and natural interactions on the landscape. Results show that the vulnerability increases close to the submarine sand falls, near intense urbanization, in resort areas, and at locations with narrow beach and dune widths. The degree of vulnerability along the coast alters abruptly, as urban and recreational sites alternate with natural sites. This coastline has seen exponential development since the 1980s, resulting in highly vulnerable areas with a low, and decreasing, touristic value, as the landscape has been changed into an urban settlement with limited natural attractions. Urban and recreational settlements threaten to cover dunes and reservoirs of natural sediments, increasingly affecting vulnerability in the area as well as the landscape values of many parts of the coast, including the submarine sand falls.Funding is acknowledged from the Program of Postdoctoral Grants from II-UNAM and DGAPA-UNAM for the first author, for research studies 2014-2016, and from CONACYT for the Master studies of the second author