A nuclear magnetic resonance study of vacancy and interstitial motion in scandium hydrides and deuterides

Nuclear Magnetic Resonance (NMR) methods have been used to study the nonstochiometric dihydrides and dideuterides of high purity scandium. For the first time, measurements have been made of the spin relaxation times T(,1) and T(,2) of all three nuclear species present ((\u2745)Sc, (\u272)D, (\u271)H) in a metal hydride (deuteride) system, permit- ting a comparison of the main features of both atomic and vacancy motion on the hydrogen sublattice. In the regions of the conventional diffusion induced (\u2745)Sc- and (\u272)D-T(,1) minima ( 0.03 and shows a weaker frequency dependence than expected. The jump-attempt frequencies (nu)(,o) obtained from the (\u2745)Sc-T(,1) data agree well with the values obtained from neutron scattering measurements, whereas the (\u271)H-T(,1) data yield anomalously low jump frequency prefactors. We interpret the departure of the (\u2745)Sc results from the Lorentzian model as indicating the formation of vacancy pairs and the importance of particle-particle interactions. The (\u2745)Sc- and (\u272)D- T(,1) data also reveal the importance of three particle correlations and conduction elec- tron screening for the quadrupolar relaxation mechanism. At high temperatures (\u3e800K), we have observed a new, previously unfore- seen and essentially frequency independent decrease of T(,1) and T(,2) for all three nuclear species ((\u2745)Sc, (\u272)D and (\u271)H). This second, high temperature T(,1) minimum suggests the formation of short-lived clusters on the H(D) sublattice similar to that occurring in superionic fluorides and the existence of highly correlated modes of motion. Large amplitude vibrations of the hydrogen (deuterium) atoms at high temperatures lead to an effective slowdown of atom diffusion and the T(,1) decrease. Several other high temperature relaxation;mechanisms have been considered and can be excluded on both theoretical and experimental grounds; (\u271)DOE REport IS-T-1237. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy

Quantification of myocardial perfusion by cardiovascular magnetic resonance

The potential of contrast-enhanced cardiovascular magnetic resonance (CMR) for a quantitative assessment of myocardial perfusion has been explored for more than a decade now, with encouraging results from comparisons with accepted "gold standards", such as microspheres used in the physiology laboratory. This has generated an increasing interest in the requirements and methodological approaches for the non-invasive quantification of myocardial blood flow by CMR. This review provides a synopsis of the current status of the field, and introduces the reader to the technical aspects of perfusion quantification by CMR. The field has reached a stage, where quantification of myocardial perfusion is no longer a claim exclusive to nuclear imaging techniques. CMR may in fact offer important advantages like the absence of ionizing radiation, high spatial resolution, and an unmatched versatility to combine the interrogation of the perfusion status with a comprehensive tissue characterization. Further progress will depend on successful dissemination of the techniques for perfusion quantification among the CMR community

(13)C-Urea breath test threshold calculation and evaluation for the detection of Helicobacter pylori infection in children

BACKGROUND: The (13)C-urea breath test (UBT) is performed in adults and children with epigastric pain for non-invasively diagnosing a suspected H. pylori infection. Criteria for UBT interpretation have not been generally agreed on and test reliability has not been established in children of different ages. This study aimed at identifying reliable UBT thresholds in children by using 251 UBTs in conjunction with reference histology and by analyzing 1232 UBTs. METHODS: At baseline and 30 and 60 minutes after the administration of 75 mg (13)C-urea to children and adolescents (0.25 to 18 years of age), the differences (Δ) of (13)CO(2)/(12)CO(2) ratio in exhaled air (δ) were determined by mass spectrometry. UBT Δδ value thresholds were calculated in random subgroups and evaluated in complementary subgroups using logistic regressions on reference histology or bimodal distribution analyses of Δδ values from UBTs alone. RESULTS: Δδ values were higher (median, 15.4‰) in positive (133/251, 53 %) than in negative histology (2.4‰). At 30 minutes, the calculated cut-off was 5.3‰ (mean regression determination R(2) = 0.91), and sensitivity (0.95), specificity (0.97), positive (0.97) and negative predictive values (0.95) were higher than at 60 minutes (threshold 6.8‰, R(2) = 0.85). Similar thresholds resulted from UBTs analysis (5.8‰ and 6.2‰) when sensitivity and specificity were maximized (concordance probabilities, 0.99 and 0.99). There was no systematic age effect. CONCLUSIONS: In children, (13)C UBT cut-offs were obtained and specially validated, entailing high accuracy of non-invasively testing for gastric H. pylori infection

Is practical subject matter knowledge still important? Examining the Siedentopian perspective on the role of content knowledge in physical education teacher education.

This is an Accepted Manuscript of an article published by Taylor & Francis in Physical Education and Sport Pedagogy on 30 May 2016, available online: http://www.tandfonline.com/10.1080/17408989.2016.1192592.Background: The role that content knowledge, an important component of practical subject matter knowledge, plays for pre-service teachers (PSTs) in physical education teacher education (PETE) remains contested and unclear. Whilst some researchers emphasise the facilitative nature of such knowledge, others criticise that too much focus on content knowledge has a negative effect on the development of pupil-centred and critical pedagogies. Despite of its seeming importance, specific research into this aspect of the knowledge base remains scarce. Purpose: This research set out to examine the effects that varying levels of content knowledge had on the development of PSTs in PETE. In doing so, it aimed to create an enhanced understanding of how this knowledge base influences the learning and development of PSTs in PETE. Methods and procedures: Shulman’s [1987. ‘Knowledge and Teaching: Foundation of the new Reform’. Harvard Educational Review 57 (1): 1–22] conceptualisation of the knowledge base for teaching was used to delineate the concept of content knowledge. Influenced by a constructivist approach to grounded theory, this study employed semi-structured interviews, lesson observations and post-lesson reflections as main instruments of data collection during three stages of a one-year PETE programme at a University in the UK. Using constant comparative analysis, data from 12 PSTs (6 female; 6 male) were analysed, following a 2-stage analysis procedure as outlined by Charmaz [2006. Constructing Grounded Theory: A Practical Guide Through Qualitative Analysis. London: Sage]. Main outcomes and results: Content knowledge limitations were found to have numerous effects on PSTs. Lack of teaching confidence, as well as adverse impact on enacted teaching knowledge (pedagogical content knowledge) highlighted that at least ‘adequacy’ of content knowledge is needed, if PSTs are to use more advanced pedagogical strategies with confidence. Content knowledge was seen to be context specific and contextualised within the curriculum delivered in the respective schools, where PSTs were placed. In-depth content knowledge was perceived to be an asset that could be used to design and teach lessons that were responsive to pupil need. Conclusions: In line with Siedentop’s [[1989] 2002. ‘Content Knowledge for Physical Education’. Journal of Teaching in Physical Education 21 (4): 368–377] critique of the academicisation of PETE, this study confirmed the facilitative role of content knowledge. Whilst such knowledge by itself does not guarantee good teaching, the debate about the wider role practical subject matter knowledge needs be re-visited. As universities and schools reposition and redefine their roles within a changing landscape of teacher education partnership models and the academic priorities and funding limitations at UK universities, the development of a range and depth of content knowledge represents an evolving challenge for all of those involved in PETE

Is practical subject matter knowledge still important?: Examining the Siedentopian perspective on the role of content knowledge in physical education teacher education

Background: The role that content knowledge, an important component of practical subject matter knowledge, plays for pre-service teachers (PSTs) in physical education teacher education (PETE) remains contested and unclear. Whilst some researchers emphasise the facilitative nature of such knowledge, others criticise that too much focus on content knowledge has a negative effect on the development of pupil-centred and critical pedagogies. Despite of its seeming importance, specific research into this aspect of the knowledge base remains scarce. Purpose: This research set out to examine the effects that varying levels of content knowledge had on the development of PSTs in PETE. In doing so, it aimed to create an enhanced understanding of how this knowledge base influences the learning and development of PSTs in PETE. Methods and procedures: Shulman’s [1987. ‘Knowledge and Teaching: Foundation of the new Reform’. Harvard Educational Review 57 (1): 1–22] conceptualisation of the knowledge base for teaching was used to delineate the concept of content knowledge. Influenced by a constructivist approach to grounded theory, this study employed semi-structured interviews, lesson observations and post-lesson reflections as main instruments of data collection during three stages of a one-year PETE programme at a University in the UK. Using constant comparative analysis, data from 12 PSTs (6 female; 6 male) were analysed, following a 2-stage analysis procedure as outlined by Charmaz [2006. Constructing Grounded Theory: A Practical Guide Through Qualitative Analysis. London: Sage]. Main outcomes and results: Content knowledge limitations were found to have numerous effects on PSTs. Lack of teaching confidence, as well as adverse impact on enacted teaching knowledge (pedagogical content knowledge) highlighted that at least ‘adequacy’ of content knowledge is needed, if PSTs are to use more advanced pedagogical strategies with confidence. Content knowledge was seen to be context specific and contextualised within the curriculum delivered in the respective schools, where PSTs were placed. In-depth content knowledge was perceived to be an asset that could be used to design and teach lessons that were responsive to pupil need. Conclusions: In line with Siedentop’s [[1989] 2002. ‘Content Knowledge for Physical Education’. Journal of Teaching in Physical Education 21 (4): 368–377] critique of the academicisation of PETE, this study confirmed the facilitative role of content knowledge. Whilst such knowledge by itself does not guarantee good teaching, the debate about the wider role practical subject matter knowledge needs be re-visited. As universities and schools reposition and redefine their roles within a changing landscape of teacher education partnership models and the academic priorities and funding limitations at UK universities, the development of a range and depth of content knowledge represents an evolving challenge for all of those involved in PETE

Cardiac Function Evaluation with Cine MRI of the Heart

This unit describes how to determine hemodynamic parameters of cardiac function such as ejection fraction (EF), end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV), and cardiac mass, based on experience using a Siemens 1.5 T Sonata scanner. Briefly, cine loops are acquired over several heartbeats, synchronized with the heart cycle by gating of the encoding steps with the patients electrocardiogram (ECG). Recently, it has become feasible to acquire cine loops in real time, although the temporal resolution is not optimal. Options discussed in this unit include breath hold versus free breathing, prospective triggering versus retrospective gating, and volumetric data sets versus biplanar approaches. Patient parameters such as heart rate or rhythm, degree of functional impairment, the presence of valvular disease, and the need to assess for jets from shunts or valve dysfunction are also treated.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145342/1/cpmia1104.pd

Cardiac Function Evaluation with Cine MRI of the Heart

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145199/1/cpmia1104.pd