Super-heavy fermion material as metallic refrigerant for adiabatic demagnetization cooling

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, as the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with $^3$He gas are widely used for cooling below 1 Kelvin. However, usage of the gas is being increasingly difficult due to the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. Here, we show that a new type of refrigerant, super-heavy electron metal, YbCo$_2$Zn$_{20}$, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. A number of advantages includes much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb$_{1-x}$Sc$_x$Co$_2$Zn$_{20}$ by partial Sc substitution with $x\sim$0.19. The substitution induces chemical pressure which drives the materials close to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures enabling final temperatures well below 100 mK. Such performance has up to now been restricted to insulators. Since nearly a century the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for the cryogen-free refrigeration

Análisis factorial múltiple como técnica de estudio de la estabilidad de los resultados de un análisis de componentes principales

Una característica de los métodos factoriales es que siempre producen resultados y éstos no son una simple descripción, sino que ponen de manifiesto la estructura existente entre los datos, de ahí la necesidad de estudiar la validez de los resultados. Es preciso analizar la naturaleza de esta estructura y estudiar la estabilidad de los resultados. Consideramos que el mejor criterio es el análisis de la estabilidad de los mapas obtenidos en el análisis factorial. El Análisis Factorial Múltiple (AFM), desarrollado por E. Escofier and J. Pages (1992), permite el análisis simultáneo de tablas en las que un mismo conjunto de individuos se describe a través de varios grupos de variables. En este trabajo se muestra la eficacia de este método para el análisis de la estabilidad de los resultados obtenidos mediante Análisis de Componentes Principales

Análisis factorial múltiple como técnica de estudio de la estabilidad de los resultados de un análisis de componentes principales

Una característica de los métodos factoriales es que siempre producen resultados y éstos no son una simple descripción, sino que ponen de manifiesto la estructura existente entre los datos, de ahí la necesidad de estudiar la validez de los resultados. Es preciso analizar la naturaleza de esta estructura y estudiar la estabilidad de los resultados. Consideramos que el mejor criterio es el análisis de la estabilidad de los mapas obtenidos en el análisis factorial. El Análisis Factorial Múltiple (AFM), desarrollado por E. Escofier and J. Pages (1992), permite el análisis simultáneo de tablas en las que un mismo conjunto de individuos se describe a través de varios grupos de variables. En este trabajo se muestra la eficacia de este método para el análisis de la estabilidad de los resultados obtenidos mediante Análisis de Componentes Principales

Diagnostic trajectories of mental disorders in children and adolescents: a cohort study.

Mental disorders in children and adolescents may follow different trajectories, such as remission, change of diagnosis, or addition of two or more comorbid diagnoses, showing a heterotypic pattern. This study aims to describe the main diagnostic trajectories across a broad range of mental disorder diagnostic categories, from childhood to adolescence and from adolescence to young adulthood in a clinical population. A prospective study was conducted among a clinical sample of children and adolescents who were aged 3-17 years at the face-to-face baseline interview. Electronic health records of these participants were reviewed 10 years later. The diagnostic stability over time was examined using the kappa coefficient, and factors associated with stability were explored using simple logistic regression. The study included a sample of 691 participants. The kappa coefficient for diagnostic stability across all diagnoses was 0.574 for the transition from childhood to adulthood, 0.614 from childhood to adolescence, and 0.733 from adolescence to adulthood. Neurodevelopmental diagnoses had the highest stability. Factors associated with higher diagnostic stability included family history of mental disorders, receiving psychopharmacological treatment, and symptom severity at baseline. We found a variable diagnostic stability across different diagnoses and age categories. The different life transitions represent complex periods that should not be overlooked from a clinical standpoint. An appropriate transition from child and adolescent mental health services to adult mental health services may have a positive impact on children and adolescents with mental disorders