Levinson's Theorem for Dirac Particles

Levinson's theorem for Dirac particles constraints the sum of the phase shifts at threshold by the total number of bound states of the Dirac equation. Recently, a stronger version of Levinson's theorem has been proven in which the value of the positive- and negative-energy phase shifts are separately constrained by the number of bound states of an appropriate set of Schr\"odinger-like equations. In this work we elaborate on these ideas and show that the stronger form of Levinson's theorem relates the individual phase shifts directly to the number of bound states of the Dirac equation having an even or odd number of nodes. We use a mean-field approximation to Walecka's scalar-vector model to illustrate this stronger form of Levinson's theorem. We show that the assignment of bound states to a particular phase shift should be done, not on the basis of the sign of the bound-state energy, but rather, in terms of the nodal structure (even/odd number of nodes) of the bound state.Comment: Latex with Revtex, 7 postscript figures (available from the author), SCRI-06109

Black Hawk County’s Approach to Lead Poisoning

Scott County, IA is facing a community lead poisoning problem, much like other counties in the state. One of these are Black Hawk County, northwest of Scott. Black Hawk County approached the lead poisoning problem by partnering with organizations including the University of Northern Iowa, the Iowa Poison Control Center, and a multitude of medical groups. Funding, procedures for action, and education were also factors in assessing the lead problem. Black Hawk County’s number of lead poisonings decreased after approaching the problem, while Scott County’s problem worsened. By using similar methods, we hope that Scott County\u27s lead problem will also decrease

Letter from Josefina Niggli to her family – October 12, 1935

Josefina María Niggli was in Monterrey, Mexico on July 13, 1910, but her family fled to Texas when violence emerged during the Mexican Revolution. Her family stayed roving back and forth across the border for many years and Josefina was home-schooled for the majority of her primary school years. She and her mother eventually established a new home in San Antonio, Texas when Josefina was fifteen where she went on to complete high school and pursue a higher education while her father stayed in Mexico “until near the time of his death”. Niggli would continue making visits to Mexico, but America was her country of residence starting in 1925 (Martinez 7-8)

Associations between characteristics of the home food environment and fruit and vegetable intake in preschool children: A cross-sectional study

Early childhood is critical to the development of lifelong food habits. Given the high proportion of children with inadequate fruit and vegetable consumption, identification of modifiable factors associated with higher consumption may be useful in developing interventions to address this public health issue. This study aimed to identify the characteristics of the home food environment that are associated with higher fruit and vegetable consumption in a sample of Australian preschool children. A cross-sectional telephone survey was conducted with 396 parents of 3 to 5 year-old children attending 30 preschools within the Hunter region, New South Wales, Australia. Children's fruit and vegetable consumption was measured using a valid and reliable subscale from the Children's Dietary Questionnaire. Associations were investigated between children's fruit and vegetable intake and characteristics of the home food environment including parental role-modeling, parental providing behaviour, fruit and vegetable availability, fruit and vegetable accessibility, pressure to eat, family eating policies and family mealtime practices. Characteristics of the home food environment that showed evidence of an association with children's fruit and vegetable consumption in simple regression models were entered into a backwards stepwise multiple regression analysis. The multiple regression analysis used generalised linear mixed models, controlled for parental education, household income and child gender, and was adjusted for the correlation between children's fruit and vegetable consumption within a preschool. The multiple regression analysis found positive associations between children's fruit and vegetable consumption and parental fruit and vegetable intake (p = 0.005), fruit and vegetable availability (p = 0.006) and accessibility (p = 0.012), the number of occasions each day that parents provided their child with fruit and vegetables (p < 0.001), and allowing children to eat only at set meal times all or most of the time (p = 0.006). Combined, these characteristics of the home food environment accounted for 48% of the variation in the child's fruit and vegetable score. This study identified a range of modifiable characteristics within the home food environment that are associated with fruit and vegetable consumption among preschool children. Such characteristics could be considered potential targets for interventions to promote intake among children of this age

Close TNO Passages as a Driver of the Origin and Evolution of Ultra-Wide Kuiper Belt Binaries

Within the dynamically cold low inclination portion of the Classical Kuiper Belt, there exists a population of weakly bound binary systems with a number of unusual properties; most notable of which is their extremely wide orbital separations; beyond 7% of their Hill radii. The stability and evolution of these Ultra-Wide Trans-Neptunian Binaries (TNBs) have, in the past, been studied extensively under the assumption that the primary evolving mechanisms are interactions between the binary components and impacting Trans-Neptunian Objects (TNOs). Here, we instead study their evolution as driven by the gravitational perturbations of close passing but non-impacting TNOs. By simulating these passages, we show that the aggregate effects of encounters over billions of years have a significant effect on Kuiper Belt binary evolution. Such processes can lead to tight binaries widening significantly over time, approaching and sometimes surpassing the separation of the widest known TNBs. We also find that the eccentricity and inclination distributions of observed Ultra-Wide TNBs can be sampled from such widened binaries. While we are unable to produce enough wide binaries to explain their abundance, the orbital properties of ones we do produce are consistent with known wide binaries

Non-Invasive Imaging of Coronary Artery Disease — The Expanding Role of Coronary Computed Tomographic Angiography in the Management of Low- to Intermediate-Risk Patients and Dealing with Intermediate Stenosis

Non-invasive anatomic imaging modalities play a crucial role in the diagnosis of coronary artery disease (CAD), particularly in the case of the symptomatic patient presenting in the emergency department

The Moderating Effect of Family-Ownership on Firm Performance: An Examination of Entrepreneurial Orientation and Social Capital

Within the small business literature, a number of recent studies have examined the importance of entrepreneurial orientation (EO) and the development of social capital (SC) as each contributes to a firm's performance. While it is generally accepted in previous studies that each of these constructs positively affects firm performance, relatively less attention has been paid to potential moderating factors that can affect these relationships. The purpose of our research is to address one such moderator, family ownership. Using structural equation modeling (SEM) to test the moderating effect of family ownership on the relationships among entrepreneurial orientation, social capital, and firm performance, our results show that the effects of EO and SC vary depending upon whether the firm is family-owned or non-family owned. Implications of these findings and future research directions are provided

Mechanisms of change during group metacognitive therapy for repetitive negative thinking in primary and non-primary generalized anxiety disorder

© 2015 Elsevier Ltd. Repetitive negative thinking (RNT) is a transdiagnostic process that serves to maintain emotional disorders. Metacognitive theory suggests that positive and negative metacognitive beliefs guide the selection of RNT as a coping strategy which, in turn, increases psychological distress. The aim of this study was to test the indirect effect of metacognitive beliefs on psychological distress via RNT. Patients (N=52) with primary and non-primary generalized anxiety disorder attended a brief, six-week group metacognitive therapy program and completed measures of metacognitive beliefs, RNT, and symptoms at the first and final treatment sessions, and at a one-month follow-up. Prospective indirect effects models found that negative metacognitive beliefs (but not positive metacognitive beliefs) had a significant indirect effect on psychological distress via RNT. As predicted by metacognitive theory, targeting negative metacognitions in treatment appears to reduce RNT and, in turn, emotional distress. Further research using alternative measures at multiple time points during therapy is required to determine whether the absence of a relationship with positive metacognitive beliefs in this study was a consequence of (a) psychometric issues, (b) these beliefs only being relevant to a subgroup of patients, or (c) a lack of awareness early in treatment

Actividades deportivas en el medio natural: su representación en libros de texto de Educación Física en Primaria

The objective of this research is to analyze the sport activities carried out in the natural environment represented in the textbooks of Physical Education (PE) in Primary Education (EP), published according to Organic Law of Education 2/2006, of May 3rd, (LOE). 4339 images have been analyzed, from 44 different textbooks, belonging to eight Spanish publishers. The SAIMEF (Physical Analysis Images Analysis System) tool, elaborated ad hoc, was used to analyze the content of the images. The pilot test, panel of experts and triangulation with several observers were some of the scientific criteria that endorsed this tool. The results show that the presence of images related to sport activities in the natural environment continues to be very scarce in PE textbooks. The editorial Teide represents in greater proportion this type of activities compared to the rest of publishers. In the third cycle appears a greater number of images, predominating drawings over pictures. The most represented sport activity is the orientation, with a 25.6%, included within the multidisciplinary sports, prevailing the terrestrial environment. The representation of sports in the natural environment varies according to the analyzed publishers. Thus, in Anaya and Bruño predominates the orientation, in Edelvives, Paidotribo and Serbal predominates the ski, and in the publishers Santillana and Teide prevails the escalation. It is necessary to reflect on the low representation of these activities in EF textbooks