Electrical transport properties of manganite powders under pressure

We have measured the electrical resistance of micrometric to nanometric powders of the La$_{5/8-y}$Pr$_y$Ca$_{3/8}$MnO$_3$ (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments to samples synthesized by a microwave assisted denitration process, we obtained two particular grain characteristic dimensions (40 nm and 1000 nm) which allowed us to analyze the grain size sensitivity of the electrical conduction properties of both the metal electrode interface with manganite (Pt / LPCMO) as well as the intrinsic intergranular interfaces formed by the LPCMO powder, conglomerate under the only effect of external pressure. We also analyzed the effects of pressure on the phase diagram of these powders. Our results indicate that different magnetic phases coexist at low temperatures and that the electrical transport properties are related to the intrinsic interfaces, as we observe evidences of a granular behavior and an electronic transport dominated by the Space Charge limited Current mechanism.Comment: 4 pages, 7 figures, to be published in Physica B Corresponding author: C. Acha ([email protected]

Note: "Lock-in accelerometry" to follow sink dynamics in shaken granular matter

Understanding the penetration dynamics of intruders in granular beds is relevant not only for fundamental Physics, but also for geophysical processes and construction on sediments or granular soils in areas potentially affected by earthquakes. While the penetration of intruders in two dimensional (2D) laboratory granular beds can be followed using video recording, it is useless in three dimensional (3D) beds of non-transparent materials such as common sand. Here we propose a method to quantify the sink dynamics of an intruder into laterally shaken granular beds based on the temporal correlations between the signals from a reference accelerometer fixed to the shaken granular bed, and a probe accelerometer deployed inside the intruder. Due to its analogy with the working principle of a lock in amplifier, we call this technique Lock in accelerometry (LIA). During Earthquakes, some soils can lose their ability to sustain shear and deform, causing subsidence and sometimes substantial building damage due to deformation or tumblin

Distribución del Sn y W en relación con las facies del Batolito de Jálama. Aplicación a la valoración del potencial metalogenético

Este plutón puede incluirse dentro de los granitoides tipo Araya (Corretgé et al. 1985). Se trata de un cuerpo granítico alóctono, de geometría ovoidal y extensión de 220 km2, emplazado en el dominio Epizonal de la Zona Centro Ibérica. Se han diferenciado las siguientes facies (Fig. 1): granitos con sillimanita de grano fino-medio (Gst granito porfídico de dos micas de grano mediogrueso (GP), leucogranito con turmalina (LT) y leucogranitos tardíos (Lt) (Ramirez, 1996). Este plutón presenta mineralizaciones de Sn y intra y extrabatolítica, y raramente de Pb-Zn

Prevalence of Mental Illness Among Latino Youth

Mental illness a marginalized area of public health, particularly for Latino youth ages 10-18. A unique combination of socioeconomic and cultural factors contribute to why Latino youth experience a higher prevalence of mental illness such as depression, anxiety, and bipolar disorder when compared to other ethnicities of the same age group. These factors include but are not limited to access to health care, religion, and family dynamics. An abundance of peer-reviewed articles report that minorities (such as African-Americans and Latinos) experience higher levels of mental illness and mental health related stigma that other ethnic groups. A survey regarding mental health prevalence and stigma was distributed among various ethnic groups in Reno, NV. Out of 100 responses, data indicates that Latino youth ages 10-18 report a higher level of mental illness and a lower level of treatment seeking behavior when compared to other minority groups such as cauasians, Asian-Americans, and African-Americans