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

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because 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 3He gas are widely used for cooling below 1 K. However, usage of the gas has been increasingly difficult because of the current worldwide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1−xScxCo2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials 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. This performance has, up to now, been restricted to insulators. For 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 cryogen-free refrigeration

Development, behaviour and autism in individuals with SMC1A variants

Introduction: Development and behaviour in Cornelia de Lange Syndrome (CdLS), including autism characteristics, have been described infrequently stratified to genetic cause and only a few studies have considered behavioural characteristics in relation to developmental level. Here, we describe the behavioural phenotype in individuals with CdLS with SMC1A variants. Methods: We performed an international, interdisciplinary study on 51 individuals with SMC1A variants. Results of questionnaire studies are compared to those in individuals with Down Syndrome and with Autism Spectrum Disorder. Results on cognition and self-injurious behaviour (SIB) are compared to those in individuals with CdLS caused by NIPBL variants. For Dutch participants with SMC1A variants we performed direct in-person assessments of cognition, autism, and added an interview and questionnaire on adaptive behaviour and sensory processing. Results: Individuals with SMC1A variants show a higher cognitive level and less SIB than individuals with NIPBL variants. Individuals with SMC1A variants without classic CdLS phenotype but with a Rett-like phenotype show more severe intellectual disability and more SIB compared to those with a CdLS phenotype. Autism is less present if outcomes in direct in-person assessments are evaluated taking developmental level into account compared to results based on a questionnaire. Conclusions: Behaviour in individuals with CdLS should be evaluated taking genetic cause into account. Detailed interdisciplinary approaches are of clinical importance to inform tailored care and may eventually improve quality of life of patients and families

Perspectives on Autism Spectrum Disorder Diagnosis, Symptoms, Treatment and Gender Roles:A Qualitative Study of Similarities and Differences between Sexes

This study aims to compare the experiences of women and men of different age groups with regard to their first autism spectrum disorder (ASD) diagnosis, symptoms, treatment, and gender roles to inform our understanding in clinical practice of differences as well as similarities. Semi-structured interviews were conducted amongst 22 women ( n = 12) and men ( n = 10) in three adult age groups regarding their diagnostic process, symptoms, treatment, and gender roles. Participants also filled out questionnaires on gender traits, social support, coping, and quality of life. Framework analysis guidelines were followed to identify subthemes within the three pre-defined key themes of the semi-structured interviews, and quantitative analyses were performed on the questionnaire results. Women often had caregiver roles and were more focused on social and family-oriented life aspects than men. Family and societal expectations may have been different for women from an early age onward and were considered burdensome by some, but not all. Views on ASD diagnosis, symptoms, and treatment were largely individually determined. The questionnaire results mostly showed no significant sex differences. Perceived gender roles differed between participants. In diagnosis and treatment, awareness of general gender differences and gender roles is important, but inter-individual differences and similar experiences in men should not be overlooked. </p

Sixfold fermion near the Fermi level in cubic PtBi2

We show that the cubic compound PtBi2, is a topological semimetal hosting a sixfold band touching point in close proximity to the Fermi level. Using angle-resolved photoemission spectroscopy, we map the bandstructure of the system, which is in good agreement with results from density functional theory. Further, by employing a low energy effective Hamiltonian valid close to the crossing point, we study the effect of a magnetic field on the sixfold fermion. The latter splits into a total of twenty Weyl cones for a Zeeman field oriented in the diagonal, [111] direction. Our results mark cubic PtBi2, as an ideal candidate to study the transport properties of gapless topological systems beyond Dirac and Weyl semimetals.Comment: 15 pages, 6 figures; this is the final, published versio