Pion electromagnetic form factor in the Kroll-Lee-Zumino model at zero and finite temperature

Includes abstract.Includes bibliographical references (p. 47-48).The renormalizable Abelian quantum field theory model of Kroll, Lee and Zumino is used to calculate next-to-leading order corrections to the pion electromagnetic form factor in vector meson dominance. At zero temperature the predictions for both the form factor and electromagnetic radius are found to improve greatly over the tree level result, and are in good agreement with the experimental data. A calculation of the vertex and self energy functions in the Matsubara formalism at finite temperature do not agree with the results of the Gale & Kapusta calculations. The resulting prediction for the radius is found to increase with temperature, consistent vith ideas about haclronic deconfinernent

Pion form factor in the Kroll-Lee-Zumino model

The renormalizable Abelian quantum field theory model of Kroll, Lee, and Zumino is used to compute the one-loop vertex corrections to the tree-level, Vector Meson Dominance (VMD) pion form factor. These corrections, together with the known one-loop vacuum polarization contribution, lead to a substantial improvement over VMD. The resulting pion form factor in the space-like region is in excellent agreement with data in the whole range of accessible momentum transfers. The time-like form factor, known to reproduce the Gounaris-Sakurai formula at and near the rho-meson peak, is unaffected by the vertex correction at order $\cal{O}$(g_\rpp^2).Comment: Revised version corrects a misprint in Eq.(1

Blood lead, cadmium and mercury among children from urban, industrial and rural areas of Fez Boulemane Region (Morocco): Relevant factors and early renal effects

Objectives: To describe blood lead (Pb-B), cadmium (Cd-B) and mercury (Hg-B) levels in children living in urban, industrial and rural areas in Fez city (north of Morocco) and to identify the determinants and some renal effects of exposure. Material and Methods: The study was conducted from June 2007 to January 2008 in 209 school children (113 girls, 96 boys), aged 6-12 years, from urban, industrial and rural areas in Fez city. Interview and questionnaires data were obtained. Blood and urinary samples were analyzed. Results: The mean of blood lead levels (Pb-B) in our population was 55.53 μg/l (range: 7.5-231.1 μg/l). Children from the urban area had higher blood lead levels (BLLs) mean (82.36 μg/l) than children from industrial and rural areas (48.23 and 35.99 μg/l, respectively); with no significant difference between boys and girls. BLLs were associated with traffic intensity, passive smoking and infancy in the urban area. The mean of blood cadmium levels (BCLs) was 0.22 μg/l (range: 0.06-0.68 μg/l), with no difference between various areas. Rural boys had higher BCLs mean than rural girls, but no gender influence was noticed in the other areas. BCLs were associated with the number of cigarettes smoked at children's homes. The blood mercury levels (BMLs) mean was 0.49 μg/l (range: 0.01-5.31 μg/l). The BMLs mean was higher in urban and industrial areas than in the rural area with no gender-related difference. BMLs were associated with amalgam fillings and infancy in the urban area. About 8% of the children had BLLs ≥ 100 μg/l particularly in the urban area, microalbuminuria and a decrease in height were noticed in girls from the inner city of Fez and that can be related to high BLLs (89.45 μg/l). Conclusions: There is a need to control and regulate potential sources of contamination by these trace elements in children; particularly for lead

Braces for idiopathic scoliosis in adolescents. A cochrane review

STUDY DESIGN. Cochrane systematic review. OBJECTIVE. To evaluate the efficacy of bracing in adolescent patients with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA. AIS is a 3-dimensional deformity of the spine. Although AIS can progress during growth and cause a surface deformity, it is usually not symptomatic. However, in adulthood, if the final spinal curvature surpasses a certain critical threshold, the risk of health problems and curve progression is increased. Braces are traditionally recommended to stop curvature progression in some countries and criticized in others. They generally need to be worn full time, with treatment extending over years. METHODS. The following databases (up to July 2008) were searched with no language limitations: the Cochrane Central Register of Controlled Trials, MEDLINE (from January 1966), EMBASE (from January 1980), and CINHAL (from January 1982), and reference lists of the articles. An extensive handsearch of the gray literature was also conducted. Randomized controlled trials (RCTs) and prospective cohort studies were searched for comparing braces with no treatment, other treatment, surgery, and different types of braces. Two review authors independently assessed trial quality and extracted data. RESULTS. We included 2 studies. There was very low quality evidence from 1 prospective cohort study with 286 girls that a brace curbed curve progression at the end of growth (success rate, 74 95% confidence interval {CI}: 52%-84%), better than observation (success rate, 34% 95% CI: 16%-49%) and electrical stimulation (success rate, 33% 95% CI: 12%-60%). There is low-quality evidence from 1 RCT with 43 girls that a rigid brace is more successful than an elastic one (SpineCor) at curbing curve progression when measured in Cobb degrees, but there were no significant differences between the 2 groups in the subjective perception of daily difficulties associated with wearing the brace. CONCLUSION. There is very low quality evidence in favor of using braces, making generalization very difficult. Further research could change the actual results and our confidence in them; in the meantime, patients' choices should be informed by multidisciplinary discussion. Future research should focus on short- and long-term patient-centered outcomes, in addition to measures such as Cobb angles. RCTs and prospective cohort studies should follow both the Scoliosis Research Society and Society on Scoliosis Orthopedic and Rehabilitation Treatment criteria for bracing studies. © 2010, Lippincott Williams & Wilkins

Multimodal sensory contributions to hippocampal spatiotemporal selectivity

The hippocampal cognitive map is thought to be driven primarily by distal visual cues and self-motion cues, although other sensory cues have also been demonstrated to influence place cells. Performing controlled experiments exploring the precise role played by different sensory modalities in determining spatial representation in the hippocampus is challenging due to need to control non-specific stimuli such as scent cues and acoustic reflections.To overcome these challenges we have developed an immersive virtual reality system for rats, in which any spatial information in these non-specific sensory cues are eliminated. The system combines full field of view visual stimuli with spatially accurate auditory stimuli to enable a variety of complex spatial tasks. To eliminate much of the subjectivity in identifiying single units in extracellular recording, an improved automated spike sorting method was developed based on existing gaussian mixture approaches.These tools were then applied to determine whether visual cues alone are sufficient for standard place cell activity in the CA1 region of the hippocampus. Single unit activity was recorded both in virtual reality, where only visual cues and non-vestibular self-motion cues provided spatial information, and in the real world using a linear track experimental paradigm.iiPlace cells displayed robust spatial selectivity in virtual reality, but only 20% of putative pyramidal cells were active in virtual reality, compared with 45% in the real world task. Distal visual and nonvestibular self-motion cues are thus sufficient to provide spatial selectivity, but vestibular and other sensory cues present int he real world are necessary to fully activate the place cell population. While bidirectional cells preferentially encode absolute position in the real world, they exhibited a distance coding scheme in virtual reality, suggesting that other sensory cues such as scent marks are necessary for a robust bidirectional position code.The frequency of hippocampal theta oscillations was reduced in virtual reality, and its speed dependence abolished. Despite this, phase precession of place fields was essentially identical in the two environments. These results constrain mechanisms governing both hip- pocampal theta oscillations and the temporal code. Taken together, these results reveal cooperative and competitive interactions between sensory modalities for control over hip- pocampal spatiotemporal selectivity and theta rhythm