The Transition from Heavy Fermion to Mixed Valence in Ce1-xYxAl3: A Quantitative Comparison with the Anderson Impurity Model

We present a neutron scattering investigation of Ce1-xYxAl3 as a function of chemical pressure, which induces a transition from heavy-fermion behavior in CeAl3 (TK=5 K) to a mixed-valence state at x=0.5 (TK=150 K). The crossover can be modeled accurately on an absolute intensity scale by an increase in the k-f hybridization, Vkf, within the Anderson impurity model. Surprisingly, the principal effect of the increasing Vkf is not to broaden the low-energy components of the dynamic magnetic susceptibility but to transfer spectral weight to high energy.Comment: 4 pages, 5 figure

A questionnaire survey reviewing radiologists’ and clinical specialist radiographers’ knowledge of CT exposure parameters

OBJECTIVE: To review knowledge of computed tomography (CT) parameters and their influence on patient dose and image quality amongst a cohort of clinical specialist radiographers (CSRs) and examining radiologists. METHODS: A questionnaire survey was devised and distributed to a cohort of 65 examining radiologists attending the American Board of Radiology exam in Kentucky in November 2011. The questionnaire was later distributed by post to a matching cohort of Irish CT CSRs. Each questionnaire contained 40 questions concerning CT parameters and their influence on both patient dose and image quality. RESULTS: A response rate of 22 % (radiologists) and 32 % (CSRs) was achieved. No difference in mean scores was detected between either group (27.8 ± 4 vs 28.1 ± 4, P = 0.87) although large ranges were noted (18–36). Considerable variations in understanding of CT parameters was identified, especially regarding operation of automatic exposure control and the influence of kilovoltage and tube current on patient dose and image quality. Radiologists were unaware of recommended diagnostic reference levels. Both cohorts were concerned regarding CT doses in their departments. CONCLUSIONS: CT parameters were well understood by both groups. However, a number of deficiencies were noted which may have a considerable impact on patient doses and limit the potential for optimisation in clinical practice. KEY POINTS: • CT users must adapt parameters to optimise patient dose and image quality. • The influence of some parameters is not well understood. • A need for ongoing education in dose optimisation is identified

Early risk factors for school-age ADHD and irritability: The roles of prenatal risk, intrusive parenting style during preschool and caregiver-child attachment quality.

ADHD is a highly impairing neurodevelopmental disorder and the family context provides a critical early environment where children’s risk for the disorder may be heightened or reduced. A parent’s style, that is their approach to interacting and guiding the child may provide children with warmth and security, or elicit fear, distrust and disappointment, both of which in turn impact behavior. However, the parent-child relationship is not unidirectional; it is dynamic. Children with high ADHD-like behaviors have greater difficulty relating to and interacting with their caregivers, while caregivers become increasingly stressed and show greater hostility and less warmth in their parenting. In turn, children’s frustration and responsiveness to the caregiver may become increasingly impaired. These coercive cycles may increase risk for greater severity of ADHD and childhood irritability as children get older. The present study used a moderated mediation model to assess these complex relations. It was hypothesized that pre- and perinatal risk would be associated with higher rates of less-than-optimal parenting, as seen through higher caregiver intrusiveness during preschool (ages 3-4 years), which in turn, would be associated with more severe ADHD and irritability at school-age (ages 8 – 9 years of age). It was also hypothesized that caregiver-preschool child attachment would moderate the relation between intrusive parenting style during preschool and child behavioral and emotional dysregulation at ages 8-9 years, such that stronger associations would be seen in the context of insecure attachment style than secure attachment style. An ethnically and racially diverse sample of community-dwelling preschoolers [N=139; baseline Sex (%) = 74 (80) male] was recruited. At baseline, (child mean age = 4.32, SD = .46 years), mothers completed a retrospective account of their pregnancy and delivery of their child, and each child and their mother completed a 15-minute videotaped parent-child interaction. Videos were coded using Biringen’s Emotional Availability Scale. Children were reassessed approximately four to five years later (child mean age = 8.58, SD = .34 years). At this school-age follow-up, caregivers and their children’s teachers were asked to complete questionnaires of ADHD severity (ADHD-RS) and irritability (BASC-2). These responses were integrated with parent responses to the Kiddie SADS, a psychiatric interview to assess children’s psychopathology; specifically, ADHD and ODD severity and diagnoses. Moderated mediation models were run using Hayes’ PROCESS to test study aims. Results showed some evidence that pre/perinatal risk, although not associated with increased maternal intrusiveness, was associated with attachment style, and attachment style moderated the association between maternal intrusiveness and higher ADHD/irritability severity, or increased chance of having an ADHD/ODD diagnosis at ages 8-9. Overall, there has been some support for the association between parenting style moderated by attachment style and ADD/ODD outcomes that highlights a picture of child development and its risk factors as well as its mechanistic pathways in understanding the developmental trajectories of childhood psychopathology

Approximating Soil Organic Carbon Stock in the Eastern Plains of Colombia

In Colombia, the rise of agricultural and pastureland expansion continues to exert increasing pressure on the structure and ecological processes of savannahs in the Eastern Plains. However, the effect of land use change on soil properties is often unknown due to poor access to remote areas. Effective management and conservation of soils requires the development spatial approaches that measure and predict dynamic soil properties such as soil organic carbon (SOC). This study estimates the SOC stock in the Eastern Plains of Colombia, with validation and uncertainty analyses, using legacy data of 653 soil samples. A random forest model of nine environmental covariate layers was used to develop predictions of SOC content. Model validation was determined using the Taylor series method, and root-mean-squared error (RMSE) and mean error (ME) were calculated to assess model performance. We found that the model explained 50.28% of the variation within digital SOC content map. Raster layers of SOC content, bulk density, and coarse rock fragment within the Eastern Plains were used to calculate SOC stock within the region. With uncertainty, SOC stock in the topsoil of the Eastern Plains was 1.2 G t ha−1. We found that SOC content contributed nearly all the uncertainty in the SOC stock predictions, although better determinations of SOC stock can be obtained with the use of a more geomorphological diverse dataset. The digital soil maps developed in this study provide predictions of extant SOC content and stock in the topsoil of the Eastern Plains, important soil information that may provide insight into the development of research, regulatory, and legislative initiatives to conserve and manage this evolving ecosystem

Non-Fermi-liquid behavior in Ce(Ru1−x_{1-x}Fex_x)2_2Ge2_2: cause and effect

We present inelastic neutron scattering measurements on the intermetallic compounds Ce(Ru$_{1-x}$Fe$_x$)$_2$Ge$_2$ ($x$=0.65, 0.76 and 0.87). These compounds represent samples in a magnetically ordered phase, at a quantum critical point and in the heavy-fermion phase, respectively. We show that at high temperatures the three compositions have the identical response of a local moment system. However, at low temperatures the spin fluctuations in the critical composition are given by non-Fermi-liquid dynamics, while the spin fluctuations in the heavy fermion system show a simple exponential decay in time. In both compositions, the lifetime of the fluctuations is determined solely by the distance to the quantum critical point. We discuss the implications of these observations regarding the possible origins of non-Fermi-liquid behavior in this system.Comment: 4 figures, submitted to PR

Physical properties of noncentrosymmetric superconductor LaIrSi3: A {\mu}SR study

The results of heat capacity C_p(T, H) and electrical resistivity \rho(T,H) measurements down to 0.35 K as well as muon spin relaxation and rotation (\muSR) measurements on a noncentrosymmetric superconductor LaIrSi3 are presented. Powder neutron diffraction confirmed the reported noncentrosymmetric body-centered tetragonal BaNiSn3-type structure (space group I4\,mm) of LaIrSi3. The bulk superconductivity is observed below T_c = 0.72(1) K. The intrinsic \Delta C_e/\gamma_n T_c = 1.09(3) is significantly smaller than the BCS value of 1.43, and this reduction is accounted by the \alpha-model of BCS superconductivity. The analysis of the superconducting state C_e(T) data by the single-band \alpha-model indicates a moderately anisotropic order parameter with the s-wave gap \Delta(0)/k_B T_c = 1.54(2) which is lower than the BCS value of 1.764. Our estimates of various normal and superconducting state parameters indicate a weakly coupled electron-phonon driven type-I s-wave superconductivity in LaIrSi3. The \muSR results also confirm the conventional type-I superconductivity in LaIrSi3 with a preserved time reversal symmetry and hence a singlet pairing superconducting ground state.Comment: 11 pages, 8 figures, 2 table

Crystal-fields in YbInNi4 determined with magnetic form factor and inelastic neutron scattering

The magnetic form factor of YbInNi4 has been determined via the flipping ratios R with polarized neutron diffraction and the scattering function S(Q,w) was measured in an inelastic neutron scattering experiment. Both experiments were performed with the aim to determine the crystal-field scheme. The magnetic form factor clearly excludes the possibility of a \Gamma7 doublet as the ground state. The inelastic neutron data exhibit two, almost equally strong peaks at 3.2 meV and 4.4 meV which points, in agreement with earlier neutron data, towards a \Gamma8 quartet ground state. Further possibilities like a quasi-quartet ground state are discussed.Comment: 7 pages, 5 figures, 2 tables, submitted to PR

Cost of care of chronic non-communicable diseases in Jamaican patients: the role of obesity

OBJECTIVE: To estimate the economic cost of Chronic Non-Communicable Diseases (CNCDs) and the portion attributable to obesity among patients in Jamaica.METHODS: The cost-of-illness approach was used to estimate the cost of care in a hospital setting in Jamaica for type 2 diabetes mellitus, hypertension, coronary heart disease, stroke, gallbladder disease, breast cancer, colon cancer, osteoarthritis, and high cholesterol. Cost and service utilization data were collected from the hospital records of all patients with these diseases who visited the University Hospital of the West Indies (UHWI) during 2006. Patients were included in the study if they were between15 and 74 years of age and if female, were not pregnant during that year. Costs were categorized as direct or indirect. Direct costs included costs for prescription drugs, consultation visits (emergency and clinic visits), hospitalizations, allied health services, diagnostic and treatment procedures. Indirect costs included costs attributed to premature mortality, disability (permanent and temporary), and absenteeism. Indirect costs were discounted at 3% rate.RESULTS: The sample consisted of 554 patients (40%) males (60%) females. The economic burden of the nine diseases was estimated at US$5,672,618 (males 37$ 1,157,173 (males 23%; females 77%). Total direct cost was estimated at US$3,740,377 with female patients accounting for 69.9$ 1,932,241 with female patients accounting for 50.6% of this cost. The greater cost among women was not found to be statistically significant. Overall, on a per capita basis, males and females accrued similar costs-of-illness (US$9,451.75 vs. US$ 10,758.18).CONCLUSIONS: In a country with per capita GDP of less than US$5,300, a per capita annual cost of illness of US$ 10,239 for CNCDs is excessive and has detrimental implications for the health and development of Jamaica