Jahn-Teller versus quantum effects in the spin-orbital material LuVO3

We report on combined neutron and resonant x-ray scattering results, identifying the nature of the spin-orbital ground state and magnetic excitations in LuVO3 as driven by the orbital parameter. In particular, we distinguish between models based on orbital Peierls dimerization, taken as a signature of quantum effects in orbitals, and Jahn-Teller distortions, in favor of the latter. In order to solve this long-standing puzzle, polarized neutron beams were employed as a prerequisite in order to solve details of the magnetic structure, which allowed quantitative intensity-analysis of extended magnetic excitation data sets. The results of this detailed study enabled us to draw definite conclusions about classical vs quantum behavior of orbitals in this system and to discard the previous claims about quantum effects dominating the orbital physics of LuVO3 and similar systems.Comment: Phys. Rev. B 91, 161104(R) (2015

Reply to "Comment on: 'Case for a U(1)π_\pi Quantum Spin Liquid Ground State in the Dipole-Octupole Pyrochlore Ce2Zr2O7\mathrm{Ce}_2\mathrm{Zr}_2\mathrm{O}_7' "

In his comment [arXiv:2209.03235], S. W. Lovesey argues that our analysis of neutron scattering experiments performed on Ce$_2$Zr$_2$O$_7$ is invalid. Lovesey argues that we have not properly accounted for the higher-order multipolar contributions to the magnetic scattering and that our use of pseudospin-$1/2$ operators to describe the scattering is inappropriate. In this reply, we show that the multipolar corrections discussed by Lovesey only become significant at scattering wavevectors exceeding those accessed in our experiments. This in no way contradicts or undermines our work, which never claimed a direct observation of scattering from higher-order multipoles. We further show that Lovesey's objections to our use of pseudospins are unfounded, and that the pseudospin operators are able to describe all magnetic scattering processes at the energy scale of our experiments, far below the crystal field gap. Finally, we comment on certain assumptions in Lovesey's calculations of the scattering amplitude which are inconsistent with experiment.Comment: 6 pages, 1 figur

Machine Learning Identifies Clinical and Genetic Factors Associated With Anthracycline Cardiotoxicity in Pediatric Cancer Survivors

BACKGROUND Despite known clinical risk factors, predicting anthracycline cardiotoxicity remains challenging. OBJECTIVES This study sought to develop a clinical and genetic risk prediction model for anthracycline cardiotoxicity in childhood cancer survivors. METHODS We performed exome sequencing in 289 childhood cancer survivors at least 3 years from anthracycline exposure. In a nested case-control design, 183 case patients with reduced left ventricular ejection fraction despite low-dose doxorubicin (\u3c= 250 mg/m(2)), and 106 control patients with preserved left ventricular ejection fraction despite doxorubicin \u3e250 mg/m(2) were selected as extreme phenotypes. Rare/low-frequency variants were collapsed to identify genes differentially enriched for variants between case patients and control patients. The expression levels of 5 top-ranked genes were evaluated in human induced pluripotent stem cell-derived cardiomyocytes, and variant enrichment was confirmed in a replication cohort. Using random forest, a risk prediction model that included genetic and clinical predictors was developed. RESULTS Thirty-one genes were differentially enriched for variants between case patients and control patients (p \u3c 0.001). Only 42.6% case patients harbored a variant in these genes compared to 89.6% control patients (odds ratio: 0.09; 95% confidence interval: 0.04 to 0.17; p = 3.98 x 10(-15)). A risk prediction model for cardiotoxicity that included clinical and genetic factors had a higher prediction accuracy and lower misclassification rate compared to the clinical-only model. In vitro inhibition of gene-associated pathways (PI3KR2, ZNF827) provided protection from cardiotoxicity in cardiomyocytes. CONCLUSIONS Our study identified variants in cardiac injury pathway genes that protect against cardiotoxicity and informed the development of a prediction model for delayed anthracycline cardiotoxicity, and it also provided new targets in autophagy genes for the development of cardio-protective drugs

Children's very low food security is associated with increased dietary intakes in energy, fat, and added sugar among Mexican-origin children (6-11 y) in Texas border Colonias

<p>Abstract</p> <p>Background</p> <p>Food insecurity among Mexican-origin and Hispanic households is a critical nutritional health issue of national importance. At the same time, nutrition-related health conditions, such as obesity and type 2 diabetes, are increasing in Mexican-origin youth. Risk factors for obesity and type 2 diabetes are more common in Mexican-origin children and include increased intakes of energy-dense and nutrient-poor foods. This study assessed the relationship between children's experience of food insecurity and nutrient intake from food and beverages among Mexican-origin children (age 6-11 y) who resided in Texas border <it>colonias</it>.</p> <p>Methods</p> <p>Baseline data from 50 Mexican-origin children were collected in the home by trained <it>promotora</it>-researchers. All survey (demographics and nine-item child food security measure) and 24-hour dietary recall data were collected in Spanish. Dietary data were collected in person on three occasions using a multiple-pass approach; nutrient intakes were calculated with NDS-R software. Separate multiple regression models were individually fitted for total energy, protein, dietary fiber, calcium, vitamin D, potassium, sodium, Vitamin C, and percentage of calories from fat and added sugars.</p> <p>Results</p> <p>Thirty-two children (64%) reported low or very low food security. Few children met the recommendations for calcium, dietary fiber, and sodium; and none for potassium or vitamin D. Weekend intake was lower than weekday for calcium, vitamin D, potassium, and vitamin C; and higher for percent of calories from fat. Three-day average dietary intakes of total calories, protein, and percent of calories from added sugars increased with declining food security status. Very low food security was associated with greater intakes of total energy, calcium, and percentage of calories from fat and added sugar.</p> <p>Conclusions</p> <p>This paper not only emphasizes the alarming rates of food insecurity for this Hispanic subgroup, but describes the associations for food insecurity and diet among this sample of Mexican-origin children. Child-reported food insecurity situations could serve as a screen for nutrition problems in children. Further, the National School Lunch and School Breakfast Programs, which play a major beneficial role in children's weekday intakes, may not be enough to keep pace with the nutritional needs of low and very low food secure Mexican-origin children.</p

Evolución de los niños tratados por leucemia linfoblástica aguda recidivante en América Central

Background. Outcomes for relapsed childhood acute lymphoblastic leukemia (ALL) have not been documented in resource-limited settings. This study examined survival after relapse for children with ALL in Central America. Methods. A retrospective cohort study was performed and included children with first relapse of ALL in Guatemala, Honduras, or El Salvador between 1990 and 2011. Predictors of subsequent eventfree survival (EFS) and overall survival (OS) were examined. Results. There were 755 children identified with relapsed disease. The median time from diagnosis to relapse was 1.7 years (interquartile range, 0.8-3.1 years). Most relapses occurred during (53.9%) or following (24.9%) maintenance chemotherapy, and the majority occurred in the bone marrow (63.1%). Following the initial relapse, subsequent 3-year EFS (± standard error) and OS were 22.0% ± 1.7%, and 28.2% ± 1.9%, respectively. In multivariable analysis, worse post relapse survival was associated with age ± 10 years, white blood cell count ± 50 ± 109/L, and positive central nervous system status at the original ALL diagnosis, relapse that was not isolated central nervous system or testicular, and relapse &lt; 36 months following diagnosis. Site and time to relapse were used to identify a favorable risk group whose 3-year EFS and OS were 50.0% ± 8.9% and 68.0% ± 8.1%, respectively. Conclusions. Prognosis after relapsed ALL in Central America is poor, but a substantial number of those with favorable risk features have prolonged survival, despite lack of access to stem cell transplantation. Stratification by risk factors can guide therapeutic decision-making.Fondo. Los resultados de la leucemia linfoblástica aguda (LLA) infantil en recaída no se han documentado en entornos de recursos limitados. Este estudio examinó la supervivencia después de la recaída en niños con LLA en América Central. Métodos. Se realizó un estudio de cohorte retrospectivo e incluyó niños con primera recaída de LLA en Guatemala, Honduras o El Salvador entre 1990 y 2011. Se examinaron los predictores de supervivencia libre de eventos (SSC) y supervivencia general (SG) subsiguientes. Resultados. Hubo 755 niños identificados con enfermedad recidivante. La mediana de tiempo desde el diagnóstico hasta la recaída fue de 1,7 años (rango intercuartílico, 0,8-3,1 años). La mayoría de las recaídas ocurrieron durante (53,9 %) o después (24,9 %) de la quimioterapia de mantenimiento, y la mayoría ocurrió en la médula ósea (63,1 %). Después de la recaída inicial, la SSC (± error estándar) y la SG posteriores a los 3 años fueron de 22,0 % ± 1,7 % y 28,2 % ± 1,9 %, respectivamente. En el análisis multivariable, la peor supervivencia posterior a la recaída se asoció con la edad ± 10 años, el recuento de glóbulos blancos ± 50 ± 109/l y el estado positivo del sistema nervioso central en el diagnóstico original de LLA, recaída que no fue del sistema nervioso central aislada o testicular, y recaída &lt; 36 meses después del diagnóstico. El sitio y el tiempo hasta la recaída se usaron para identificar un grupo de riesgo favorable cuya SSC y SG a 3 años fueron 50,0 % ± 8,9 % y 68,0 % ± 8,1 %, respectivamente. Conclusiones. El pronóstico después de la LLA recidivante en América Central es malo, pero un número considerable de personas con características de riesgo favorables tienen una supervivencia prolongada, a pesar de la falta de acceso al trasplante de células madre. La estratificación por factores de riesgo puede orientar la toma de decisiones terapéuticas

Towards understanding the magnetic properties of the breathing pyrochlore compound Ba(3)Yb(2)Zn(5)O(11)through single-crystal studies

Ba3Yb2Zn5O11 is exceptional among breathing pyrochlore compounds for being in the nearly-decoupled limit where inter-tetrahedron interactions are weak, hosting isolated clusters or molecular magnet-like tetrahedra of magnetic ytterbium (Yb3+) ions. In this work, we present the study carried out on single-crystal samples of the breathing pyrochlore Ba3Yb2Zn5O11, using a variety of magnetometry and neutron scattering techniques along with theoretical modeling. We employ inelastic neutron scattering to investigate the magnetic dynamics as a function of applied field (with respect to both magnitude and direction) down to a temperature of 70 mK, where inelastic scattering reveals dispersionless bands of excitations as found in earlier powder sample studies, in good agreement with a single-tetrahedron model. However, diffuse neutron scattering at zero field and dc-susceptibility at finite field exhibit features suggesting the presence of excitations at low-energy that are not captured by the single tetrahedron model. Analysis of the local structure down to 2 K via pair distribution function analysis finds no evidence of structural disorder. We conclude that effects beyond the single tetrahedron model are important in describing the low-energy, low-temperature physics of Ba3Yb2Zn5O11, but their nature remains undetermined