Chemical Disorder in Topological Insulators: A Route to Magnetism Tolerant Topological Surface States.

We show that the chemical inhomogeneity in ternary three-dimensional topological insulators preserves the topological spin texture of their surface states against a net surface magnetization. The spin texture is that of a Dirac cone with helical spin structure in the reciprocal space, which gives rise to spin-polarized and dissipation-less charge currents. Thanks to the nontrivial topology of the bulk electronic structure, this spin texture is robust against most types of surface defects. However, magnetic perturbations break the time-reversal symmetry, enabling magnetic scattering and loss of spin coherence of the charge carriers. This intrinsic incompatibility precludes the design of magnetoelectronic devices based on the coupling between magnetic materials and topological surface states. We demonstrate that the magnetization coming from individual Co atoms deposited on the surface can disrupt the spin coherence of the carriers in the archetypal topological insulator Bi2Te3, while in Bi2Se2Te the spin texture remains unperturbed. This is concluded from the observation of elastic backscattering events in quasiparticle interference patterns obtained by scanning tunneling spectroscopy. The mechanism responsible for the protection is investigated by energy resolved spectroscopy and ab initio calculations, and it is ascribed to the distorted adsorption geometry of localized magnetic moments due to Se-Te disorder, which suppresses the Co hybridization with the surface states.

Spin-Orbit Semimetal SrIrO_{3} in the Two-Dimensional Limit.

We investigate the thickness-dependent electronic properties of ultrathin SrIrO_{3} and discover a transition from a semimetallic to a correlated insulating state below 4 unit cells. Low-temperature magnetoconductance measurements show that spin fluctuations in the semimetallic state are significantly enhanced while approaching the transition point. The electronic properties are further studied by scanning tunneling spectroscopy, showing that 4 unit cell SrIrO_{3} is on the verge of a gap opening. Our density functional theory calculations reproduce the critical thickness of the transition and show that the opening of a gap in ultrathin SrIrO_{3} requires antiferromagnetic order.

Programa de detección precoz de trastornos generalizados del desarrollo en las áreas de salud de Salamanca y Zamora / Pervasive developmental disorders screening program in the health areas of Salamanca and Zamora in Spain

OBJETIVO: Evaluar los resultados obtenidos por el programa de detección precoz de trastornos generalizados del desarrollo (TGD), actualmente en marcha en las áreas de salud de Salamanca y Zamora, en términos de participación y opinión de los profesionales hacia el mismo, así como la validez de la herramienta con la finalidad de extender su uso tanto a nivel autonómico como nacional. MÉTODO: Un total de 54 equipos de pediatría participaron en las sesiones de formación del programa de cribado de TGD en septiembre de 2005 y accedieron a administrar el cuestionario M-CHAT a todos los padres que acudían a sus consultas de pediatría en cualquiera de estas 2 visitas: 18 y/o los 24 meses dentro del Programa del Control del Niño Sano. Hasta diciembre de 2012 han participado un total de 9.524 niños. Adicionalmente, se ha evaluado la participación y opinión de los equipos de pediatría participantes mediante cuestionarios y entrevistas y se han estimado los costes por caso positivo detectado. RESULTADOS: Del total, 852 (8,9%) sujetos resultaron sospechosos de TGD en el cuestionario M-CHAT, de los cuales 61 (7,1%) se confirmaron mediante la entrevista de seguimiento. De estos, 22 obtuvieron un diagnóstico TGD y 31 de otros trastornos de inicio en la infancia según DSM-IV-TR. El 74% de los equipos encuestados consideran el programa totalmente viable y el 22% viable aunque con reservas (n = 54). CONCLUSIONES: Este estudio ha conseguido mostrar por primera vez en España, la viabilidad de realizar un programa de cribado de TGD de base poblacional dentro del sistema público de salud. La formación sobre los problemas del desarrollo comunicativo y social y la difusión de las señales de alerta entre los pediatras, además de la utilización del M-CHAT, es fundamental para el avance en la detección temprana de estos trastornos

OBJECTIVE: To evaluate the results of the Pervasive Developmental Disorders (PDD) screening program currently ongoing in the public health services in the health area of Salamanca and Zamora, Spain, in terms of feasibility, reliability and costs, with the purpose of extending the program at regional and national levels. METHOD: A total of 54 paediatric teams (nurses and paediatricians) from the provinces of Salamanca and Zamora participated in the training sessions for the PDD Screening Programme in September 2005, and agreed to administer the questionnaire M-CHAT1 to all parents attending their clinics in any of these two visits: 18 months and/or 24 months within the Well-baby Checkup Program. A total of 9,524 children have participated up to December 2012. Additionally, we evaluated the participation and opinions of the paediatric teams using questionnaires, and costs per positive case have estimated. RESULTS: Out of a total of 852 (8.9%) children determined as PDD high-risk with the M-CHAT questionnaire results, 61 (7.1%) were confirmed as positive with the M-CHAT follow-up interview. Of these, 22 were diagnosed with a PDD and 31 other disorders of childhood onset according toDSM-IV-TR2. Almost three-quarters (74%) of respondents felt the program was totally feasible, and 22% viable, but with reservations (n=54). CONCLUSIONS: This study has been able to show for the first time in Spain, the feasibility of a population-based PDD screening program within the public health system. Training in social and communicative development, and dissemination of the early signs of PDD among paediatricians, as well as the use of the M-CHAT, is essential for progress in the early detection of these disorders

[Pervasive developmental disorders screening program in the health areas of Salamanca and Zamora in Spain]. / Programa de detección precoz de trastornos generalizados del desarrollo en las áreas de salud de Salamanca y Zamora.

OBJECTIVE: To evaluate the results of the Pervasive Developmental Disorders (PDD) screening program currently ongoing in the public health services in the health area of Salamanca and Zamora, Spain, in terms of feasibility, reliability and costs, with the purpose of extending the program at regional and national levels. METHOD: A total of 54 paediatric teams (nurses and paediatricians) from the provinces of Salamanca and Zamora participated in the training sessions for the PDD Screening Programme in September 2005, and agreed to administer the questionnaire M-CHAT(1) to all parents attending their clinics in any of these two visits: 18 months and/or 24 months within the Well-baby Check-up Program. A total of 9,524 children have participated up to December 2012. Additionally, we evaluated the participation and opinions of the paediatric teams using questionnaires, and costs per positive case have estimated. RESULTS: Out of a total of 852 (8.9%) children determined as PDD high-risk with the M-CHAT questionnaire results, 61 (7.1%) were confirmed as positive with the M-CHAT follow-up interview. Of these, 22 were diagnosed with a PDD and 31 other disorders of childhood onset according to DSM-IV-TR(2). Almost three-quarters (74%) of respondents felt the program was totally feasible, and 22% viable, but with reservations (n=54). CONCLUSIONS: This study has been able to show for the first time in Spain, the feasibility of a population-based PDD screening program within the public health system. Training in social and communicative development, and dissemination of the early signs of PDD among paediatricians, as well as the use of the M-CHAT, is essential for progress in the early detection of these disorders.

[Psychosocial factors in patients with duodenal ulcer]. / Factores psicosociales en la úlcera duodenal.

The authors review the current literature on psychosocial aspects of duodenal ulcer. The initial simple psychosomatic approach, has evolved to a multifactorial schema in which stress and individual vulnerability plays an important role. Psychological features (personality, Type A behaviour, alexithymia, anxiety, depression) and socioenvironmental factors (stress, life events, coping, social support) are analyzed. Newer aspects like the probable stress influence on immunity and infection by Helicobacter pylori are considered.