Symmetry Induced 4-Wave Capillary Wave Turbulence

We report theoretical and experimental results on 4-wave capillary wave turbulence. A system consisting of two inmiscible and incompressible fluids of the same density can be written in a Hamiltonian way for the conjugated pair $(\eta,\Psi)$. When given the symmetry $z\to-z$, the set of weakly non-linear interacting waves display a Kolmogorov-Zakharov (KZ) spectrum $n_k\sim k^{-4}$ in wave vector space. The wave system was studied experimentally with two inmiscible fluids of almost equal densities (water and silicon oil) where the capillary surface waves are excited by a low frequency random forcing. The power spectral density (PSD) and probability density function (PDF) of the local wave amplitude are studied. Both theoretical and experimental results are in fairly good agreement with each other.Comment: 6 pages, 2 figure

Wave-vortex interaction

We present an experimental study on the effect of a electromagneticaly generated vortex flow on parametrically amplified waves at the surface of a fluid. The underlying vortex flow, generated by a periodic Lorentz force, creates spatio-temporal fluctuations that interact nonlinearly with the standing surface waves. We characterize the bifurcation diagram and measure the power spectrum density (PSD) of the local surface wave amplitude. We show that the parametric instability threshold increases with increasing intensity of the vortex flow.Comment: 8 pages, 10 figures, submitted to Phys. Rev.

CALIFA reveals Prolate Rotation in Massive Early-type Galaxies: A Polar Galaxy Merger Origin?

We present new evidence for eight early-type galaxies (ETGs) from the CALIFA Survey that show clear rotation around their major photometric axis ("prolate rotation"). These are LSBCF560-04, NGC 0647, NGC 0810, NGC 2484, NGC 4874, NGC 5216, NGC 6173 and NGC 6338. Including NGC 5485, a known case of an ETG with stellar prolate rotation, as well as UGC 10695, a further possible candidate for prolate rotation, we report ten CALIFA galaxies in total that show evidence for such a feature in their stellar kinematics. Prolate rotators correspond to ~9% of the volume-corrected sample of CALIFA ETGs, a fraction much higher than previously reported. We find that prolate rotation is more common among the most massive ETGs. We investigate the implications of these findings by studying N-body merger simulations, and show that a prolate ETG with rotation around its major axis could be the result of a major polar merger, with the amplitude of prolate rotation depending on the initial bulge-to-total stellar mass ratio of its progenitor galaxies. Additionally, we find that prolate ETGs resulting from this formation scenario show a correlation between their stellar line-of-sight velocity and higher order moment h_3, opposite to typical oblate ETGs, as well as a double peak of their stellar velocity dispersion along their minor axis. Finally, we investigate the origin of prolate rotation in polar galaxy merger remnants. Our findings suggest that prolate rotation in massive ETGs might be more common than previously expected, and can help towards a better understanding of their dynamical structure and formation origin.Comment: accepted for publication in A&

Capillary wave turbulence on a spherical fluid surface in low gravity

We report the observation of capillary wave turbulence on the surface of a fluid layer in a low-gravity environment. In such conditions, the fluid covers all the internal surface of the spherical container which is submitted to random forcing. The surface wave amplitude displays power-law spectrum over two decades in frequency, corresponding to wavelength from $mm$ to a few $cm$. This spectrum is found in roughly good agreement with wave turbulence theory. Such a large scale observation without gravity waves has never been reached during ground experiments. When the forcing is periodic, two-dimensional spherical patterns are observed on the fluid surface such as subharmonic stripes or hexagons with wavelength satisfying the capillary wave dispersion relation

High temperature tribological characterization of TiAl laser cladding coating on Ti6Al4V alloy

Ti6Al4V alloy has proven to be an important engineering material due to the excellent strength, weight ratio, high corrosion resistance and biocompatibility. However, the alloy is susceptible to mechanical degradation in applications involving sliding wear or abrasion. In order to improve wear resistance, coatings by laser cladding of intermetallic Ti48Al2Cr2Nb on Ti6Al4V have been developed. Different process parameters: laser power (W), scanning speed (mm/min), powder feeding rate (g/min) and preheating temperature of substrate (°C) were optimized, resulting in a microstructure of the coatings considered appropriate, with good metallurgical bond, though cracks and pores were observed [1]. The composition and microstructure of the coatings were evaluated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, further the tribological properties were evaluated using a ball on disk tribometer, with Al2O3 ball, constant speed of 0.1 m/s, 10 N load at room temperature and 500 °C. We measure the 3D surface topography obtained from the wear scar and calculated the wear rate. The coatings microstructure consists of -TiAl phase and 2-Ti3Al. The wear test results at room temperature show a lower wear rate for the coating compared to the substrate. At high temperature the coating have a higher friction coefficient and a higher rate of wear is obtained when compared with the substrate, obtaining differences between the coatings depending on the wear mechanism observed in the worn surface.The authors acknowledge the economical support from the Ministry of Science and Innovation of the Government of Spain through research project MAT2011-28492-03 and the Generalitat Valenciana through support ACOMP/2014/151. Thanks also to Dr. José Luis Jorda by X-ray diffraction analysis performed

Key soft skills in the orientation process and level of employability

We understand soft skills as an integrated set of knowledge, skills and values that facilitate the effective, affective and efficient development of a skill or activity. The objective of this study was to identify the soft skills that are most often used in the orientation process and those that improve employability, according to Spanish counselors. A qualitative methodology was used. The participants (n = 57) were orientation professionals. A total of 273 interviews were conducted over five years. The results and conclusions show that communication and decision-making are the most important competencies in the orientation process and at the level of employability, followed by intrapersonal skills, skills in interpersonal relationships, teamwork, problem solving, adaptation to new situations, creativity and leadership

Development of laser cladding MCrAlY coatings: high temperature friction and wear behaviour

Temperature can have a significant effect on the extent of wear damage of metallic components. Thermal barrier coatings with MCrAlY (where M=Ni, Co, Fe or combinations) alloys can improve the high temperature tribological and friction wear behaviour. In this work the dry friction and wear behaviour at room temperature and high temperature of new developed NiCoCrAlY and CoNiCrAlY laser cladding coatings were evaluated. Dense coatings, with good metallurgical bonding to the AISI 304 substrate was obtained by coaxial laser cladding tracks (40% overlapping), with previously optimized laser parameters. Tribological tests were performed by sliding wear at room temperature and 500 ºC, with an Al2O3 counterpart in ball on disk configuration tribometer. The wear scar surface was evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) microanalysis. The 3D wear track topography was measured by inductive contact profilometer which enabled the wear rate calculation. The microstructure of the coatings consists of - Ni/-NiAl or -Co/-(Co,Ni)Al phases depending on the chemical composition of the alloy, as confirmed by X-ray diffraction (XRD) analysis. The wear test results show a reduction in wear rate at high temperature for all materials tested. For the NiCoCrAlY coating, the high temperature also reduces the friction coefficient, while it significantly increases the friction coefficient of CoNiCrAlY coating. The main damage mode is abrasion and adhesion, caused by oxides and partially-oxidized particles in the contact surface. The coatings and substrate results were compared, resulting in improved wear behaviour.The authors acknowledge the financial support of the Ministry of Science and Innovation of the Government of Spain through research project MAT2011-28492- C03 and the Generalitat Valenciana through ACOMP/2013/114 support. Professor Juan Carlos Pereira Falcón thanks the University of Carabobo for the financial support to pursue his doctoral studies at the UPV

EVALUATION OF BODY MEASUREMENTS FOR THE SELECTION OF LAMAS AND THEIR BABIES

En las llamas y crías del núcleo reproductor del Centro Experimental IVITA-UNMSM se evaluó el peso corporal (PC), perímetro torácico (PT), las medidas del muslo (MU), grupa (GR) y ubre, y la producción de leche para determinar, a través de pruebas de correlación, los indicadores fenotípicos apropiados en la selección de llamas para producción de carne. La evaluación incluyó el efecto de la edad y paridad de la madre de años anteriores a través del análisis de varianza. En las medidas del muslo se consideró la circunferencia de su perímetro superior (CSMU) e inferior (CIMU) y su longitud (LMU); y en la grupa, la distancia entre sus tuberosidades isquiática medial, lateral, sacra y coxal. En la ubre se consideró su longitud y ancho y el perímetro del área entre pezones (PAP), registradas previo al ordeño. El volumen de leche fue medido cada semana hasta la semana 7 de lactación y simultáneo a estas medidas se obtuvo el peso corporal de la madre y crías. La paridad y edad afectó el PC, PT y todas las medidas de la ubre; y en las medidas del muslo solo hubo efecto de la edad. En las madres, hubo correlación significativa (alta y media) de su PC con PT, ancho de la ubre y PAP con todas las medidas del muslo y de la grupa. En la producción de leche, no hubo efecto de la paridad y la edad y en su relación con las diferentes variables, destacaron la correlación media alta con el ancho de la ubre (p<0.00l) y media baja con el PAP (p<0.l). En la cría, hubo correlación alta y significativa entre PC, edad y PT y de LMU del muslo con CSMU y CIMU; con la edad su relación fue inversamente proporcional. En la relación madre-cría, las variables paridad, edad, PC, ancho de ubre, PAP y producción de leche tuvieron relaciones positivas con PC de las crías; similar patrón se tuvo con PT, a excepción de la paridad y edad, incluso con PT y CSMU e CIMU de la madre. La CSMU y CIMU y LMU de la cría solo tuvo correlación media con las medidas de la ubre. En conclusión, las variables asociados a la producción de leche (largo, ancho y PAP de la ubre) son las más importantes para determinar crías de mejor peso y, por lo tanto, pueden ser consideradas como criterios de selección de las madres con la finalidad de obtener crías de alto valor fenotípico. Aunado a ellos, las variables PC de la madre, y la CSMU y CIMU del muslo deben de ser incluidas para la selección de animales élite.Lamas and their babies from the IVITA Research Center of San Marcos University were used to evaluate the body weight (BW), thoracic perimeter (TP), measures of thigh (TH), rump (RU) and udder, and milk yield, through correlation test to determine the suitable phenotype indicators for the selection of animals for meat production. The evaluation included the effect of age and parity of the dams from previous years using the ANOVA analysis. In the thigh was measured the length (LTH) and the circumference of its upper (CSTH) and lower (CITH) perimeter and, on the rump, the distance between its medial, lateral, sacral and coxal tuberosities. In the udder was measured the length, width and perimeter of the area between teats (PAT). The milk yield was weekly recorded until week seven of lactation and simultaneous to these measures was obtained the body weight of both mothers and babies. There were age and parity effects on TP and udder measurements; however, only the former effect was evident on thigh measurement. There was a significant relationship (high and mediun) of BW with TP, udder width and PAT with all thigh and rump measurements. Milk yield was not affected by age and parity, however had a clear relationship with udder width (p<0.0l) and PAT (p<0.l). In babies was found a high and significant relationship of BW with age and TP, LTH with CSTH and CITH while had an inverse relationship with age. In the mother-baby interaction, parity, age, BW, udder width, PAT and mother milk yield had positive relationships with baby BW; similar pattern had with TP, with the exception of parity and age, even with mother PT, CSTH and CITH. The CSTH and CITH and length of baby thigh had only a mediun relationship with udder measurements. In conclusion, the variables associated with milk yield (length and width of the udder and the PAT) were the most important to determine BW of baby lamas, which allow the selection of lama mothers to produce babies of high phenotypic value. The variables BW of the mother and the CSTH and CITH must be considered to select superior animals