Void fraction thermo-kinematics for subcooled flow boiling

This work presents some preliminary results about a new void fraction model in subcooled flow boiling based on brand new mass and energy balances developed by the author over the past years. As main novelties, the new mass balance is based on the liquid velocity and the mixture specific volume, whereas the new heat balance is a function of the mixture enthalpy, based on the thermodynamic quality, and explicitly includes the mean vapor–liquid velocity ratio, or the slip ratio. The core of the model is to predict the slip ratio profile and then to calculate the mixture enthalpy from the new heat balance and, finally, to derive the void fraction. In this work, it is shown that the continuity of the first derivative of the mixture specific volume just at saturation establishes a first equation to obtain the slip evolution. A second kinematic equation between the onset of nuclear boiling (ONB) and the vapor velocity is also found. Three additional parameters, related to the ONB and the point of net vapor generation, are needed for void fraction profiles predictions, which have been found by trial and error, searching the best fitting to the measured void fraction. The new model is compared to eight full axial void fraction profiles data for upward subcooled flow of water at high pressure

Bilayer graphene under pressure: Electron-hole Symmetry Breaking, Valley Hall Effect, and Landau Levels

The electronic structure of bilayer graphene under pressure develops very interesting features with an enhancement of the trigonal warping and a splitting of the parabolic touching bands at the K point of the reciprocal space into four Dirac cones, one at K and three along the T symmetry lines. As pressure is increased, these cones separate in reciprocal space and in energy, breaking the electron-hole symmetry. Due to their energy separation, their opposite Berry curvature can be observed in valley Hall effect experiments and in the structure of the Landau levels. Based on the electronic structure obtained by Density Functional Theory, we develop a low energy Hamiltonian that describes the effects of pressure on measurable quantities such as the Hall conductivity and the Landau levels of the system.Comment: 11 pages, 9 figure

High-precision analysis of binary stars with planets. I. Searching for condensation temperature trends in the HD 106515 system

We explore the probable chemical signature of planet formation in the remarkable binary system HD 106515. The A star hosts a massive long-period planet with 9 MJup detected by radial velocity. We also refine stellar and planetary parameters by using non-solar-scaled opacities when modeling the stars. Methods. We carried out a simultaneous determination of stellar parameters and abundances, by applying for the first time non-solar-scaled opacities in this binary system, in order to reach the highest possible precision. Results. The stars A and B in the binary system HD 106515 do not seem to be depleted in refractory elements, which is different when comparing the Sun with solar-twins. Then, the terrestrial planet formation would have been less efficient in the stars of this binary system. Together with HD 80606/7, this is the second binary system which does not seem to present a (terrestrial) signature of planet formation, and hosting both systems an eccentric giant planet. This is in agreement with numerical simulations, where the early dynamical evolution of eccentric giant planets clear out most of the possible terrestrial planets in the inner zone. We refined the stellar mass, radius and age for both stars and found a notable difference of 78% in R compared to previous works. We also refined the planet mass to mp sini = 9.08 +/- 0.20 MJup, which differs by 6% compared with literature. In addition, we showed that the non-solar-scaled solution is not compatible with the classical solar-scaled method, and some abundance differences are comparable to NLTE or GCE effects specially when using the Sun as reference. Then, we encourage the use of non-solar-scaled opacities in high-precision studies such as the detection of Tc trends.[abridged]Comment: 9 pages, 10 figures, A&A accepted. arXiv admin note: text overlap with arXiv:1507.0812

Comparison between the Use of Lecture and Workbook in Improving the Academic Performance of Students in Ecology

This study aimed to compare the effectiveness of lecture and workbook in improving the academic performance of students in ecology in Don Mariano Marcos Memorial State University, Philippines. This an action research that made use of actual scores and interventions to improve the academic performance of 44 students enrolled in Ecology. There were 22 students in the A group (lecture) and another 22 students in B group (workbook). The use of pure lecture was applied to group A (lecture) and workbook was utilized to group B. The frequency, percentage and average mean were utilized to compare the performance of   both groups in the pre-test and post-test. T-test was used to determine the difference of students’ performance. Both groups, group A (lecture) and group B (workbook) performed poorly (59%) before the utilization of lecture to group A and workbook to group B as interventions. The average performance of group A (lecture) after the implementation of lecture as intervention was very good (89%) with 21.38% progress while group B (workbook) got (90%) equivalent to very good performance with 23.09% progress. Both groups have improved in their academic performance in ecology after the utilization of interventions but the use of workbook was more advantageous

Autonomy and sustainability: an integrated analysis of the development of new approaches to agrosystem management in family-based farming in carnaubais territory, Piauí, Brazil.

This paper seeks to analyze an endogenous development scheme implemented by farming families, involving innovations in the organic production of watermelons; this was a novel local initiative reflecting the creative drive of the farmers themselves, against a background marked by considerable political and institutional uncertainty. The scheme was evaluated in terms of a set of systemic properties measured by multidimensional indicators for farming systems. Data on the selected indicators were collected by field observations, monitoring of production units, and direct semi-structured interviews with farmers. In general terms, the innovations prompted improvements in the various components of extensive environmental and social sustainability, enabling a more sustainable land use through chemical, physical and biological improvements to the soil in the farming systems studied, ensuring increased incomes and the maintenance of family employment, strengthening the farmers? resources and improving their control over resources, and reducing the degree of dependency in relations between the farming unit and the broader context

Harmonic motion modes in parabolic GRIN fibers

We report electromagnetic field modes solving the inhomogeneous Maxwell equations for parabolic gradient index fibers in the low refractive index contrast approximation. The first family comprises accelerating fields characterized by an intensity distribution center tracing a circular trajectory transverse to the fiber optical axis. These fields maintain an invariant shape for both their intensity and phase distributions while rotating around their center. The second family comprises breathing fields characterized by an intensity distribution center aligned with the fiber optical axis. These fields exhibit intensity distribution scaling along propagation, while their phase swirls and rotates around the optical axis without changing their intensity distribution shape and topological charge.Comment: 11 pages, 4 figure

Condrosarcoma en pie

El condrosarcoma óseo en el pie es una lesión muy rara. Se presenta 1 caso de bajo grado de malignidad histológico y primario en su origen, que afecta al primer radio, tratado mediante resección amplia y sin signos de recidiva a los 3 años y medio de evolución.Bone chondrosarcoma very rarely affccts the foot. We report a case of primary bone chondrosarcoma vvith low grade malignancy involving the first metatarsal bone. Tumor was treated by wide resection. Three and half years later, there was not signs of recurrence

3D MODELLING OF THE NEGRO TOWER FOR ITS COMPREHENSIVE ANALYSIS AND A CONSERVATION PROPOSAL

Abstract. The Negro Tower, in El Algar, Cartagena (Region of Murcia, Spain), is a building which dates to 1585. It is a tower built in a rural environment, inland from the coast, to alert and protect the population from pirate attacks. It was part of the network of watchtowers and defense posts along the coast of Murcia built between the sixteenth and seventeenth centuries. The tower is protected as a historical monument, but its state of conservation is very poor. For this reason, a comprehensive study has been carried out to ensure its correct restoration and future conservation. Historical and constructive analysis has allowed us to discover the social, cultural and architectural characteristics of the tower. Digital photogrammetry and 3D laser scanning compatible with classic topography have been used for the graphic survey of the tower. All this information has permitted the elaboration of thorough three-dimensional modelling and the proposal of a volumetric recomposition of the tower. The presentation will set out the working methodology followed as well as the important results achieved. This research work aims to contribute to the recognition and correct conservation of the Tower. The graphic survey and the three-dimensional model obtained will allow the recovery of the tower and its integration into the natural environment

Quiste óseo aneurismático postraumático

Se presenta un caso de quiste óseo aneurismático de localización superficial en la cara externa del húmero. El tumor fue tratado mediante la resección en bloque y relleno con hueso liofilizado. La evolución ha sido satisfactoria no habiéndose presentado recurrencia del tumor y considerándose el enfermo completamente curado a los tres años de realizado el tratamiento. Se establece una relación próxima en el tiempo con un episodio traumático, que se considera desencadenante del desarrollo tumoral y de la sintomatología.A case of aneurysmal bone cyst located at the lateral periosteal surface of the humeral diaphysis is presented. The patient was treated by in-bloc tumor resection and grafting of liophylized bone. The outcome has been satisfactory without tumor recurrence. Three years after surgery the patients remains free from disease. A relationship between previous trauma and the development of tumor could be found

Fractura bipolar de clavícula

Se presenta un caso de fractura que afecta a ambos extremos de la clavícula. Fractura tipo II de Neer del fragmento distal y fractura del extremo esternal de la clavícula. Se realizó tratamiento quirúrgico mediante reducción abierta y osteosíntesis con agujas de Kirschner en ambas. El resultado a largo plazo ha sido satisfactorio cosmética y funcionalmente.A case of bipolar fracture affecting both ends of the clavicle is reported. The lesion consisted of a Neer type II fracture at the distal segment and a fracture close to the proximal joint with the sternum. Surgical treatment was carried out by open reduction and Kirschner wire fixation stabilizing both sides. At follow up, clinical and cosmetic results are satisfactories