An independent estimate of the triple-Pomeron coupling

The value of the important triple-Pomeron coupling is estimated by an unorthodox procedure using the known diffractive parton distribution functions. The result is g_{3P}\simeq 0.2g_N, where g_N is the Pomeron-nucleon coupling. This is in excellent agreement with an independent determination, g_{3P}\simeq 0.2g_N, previously obtained by analysing the available data in the triple-Regge region with absorptive effects taken into account.Comment: 7 pages, 5 figure

Individual differences in the production of disfluency: a latent variable analysis of memory ability and verbal intelligence

Recent work has begun to focus on the role that individual differences in executive function and intelligence have on the production of fluent speech. However, isolating the underlying causes of different types of disfluency has been difficult given the speed and complexity of language production. In this study, we focused on the role of memory abilities and verbal intelligence, and we chose a task that relied heavily on memory for successful performance. Given the task demands, we hypothesised that a substantial proportion of disfluencies would be due to memory retrieval problems. We contrasted memory abilities with individual differences in verbal intelligence as previous work highlighted verbal intelligence as an important factor in disfluency production. A total of 78 participants memorised and repeated 40 syntactically complex sentences, which were recorded and coded for disfluencies. Model comparisons were carried out using hierarchical structural equation modelling. Results showed that repetitions were significantly related to verbal intelligence. Unfilled pauses and repairs, in contrast, were marginally (p <.09) related to memory abilities. The relationship in all cases was negative. Conclusions explore the link between different types of disfluency and particular problems arising in the course of production, and how individual differences inform theoretical debates in language production

Evaluation of Cardiac Circadian Rhythm Deconditioning Induced by 5-to-60 Days of Head-Down Bed Rest

Head-down tilt (HDT) bed rest elicits changes in cardiac circadian rhythms, generating possible adverse health outcomes such as increased arrhythmic risk. Our aim was to study the impact of HDT duration on the circadian rhythms of heart beat (RR) and ventricular repolarization (QTend) duration intervals from 24-h Holter ECG recordings acquired in 63 subjects during six different HDT bed rest campaigns of different duration (two 5-day, two 21-day, and two 60-day). Circadian rhythms of RR and QTend intervals series were evaluated by Cosinor analysis, resulting in a value of midline (MESOR), oscillation amplitude (OA) and acrophase (f). In addition, the QTc (with Bazett correction) was computed, and day-time, night-time, maximum and minimum RR, QTend and QTc intervals were calculated. Statistical analysis was conducted, comparing: (1) the effects at 5 (HDT5), 21 (HDT21) and 58 (HDT58) days of HDT with baseline (PRE); (2) trends in recovery period at post-HDT epochs (R) in 5-day, 21-day, and 60-day HDT separately vs. PRE; (3) differences at R + 0 due to bed rest duration; (4) changes between the last HDT acquisition and the respective R + 0 in 5-day, 21-day, and 60-day HDT. During HDT, major changes were observed at HDT5, with increased RR and QTend intervals’ MESOR, mostly related to day-time lengthening and increased minima, while the QTc shortened. Afterward, a progressive trend toward baseline values was observed with HDT progression. Additionally, the f anticipated, and the OA was reduced during HDT, decreasing system’s ability to react to incoming stimuli. Consequently, the restoration of the orthostatic position elicited the shortening of RR and QTend intervals together with QTc prolongation, notwithstanding the period spent in HDT. However, the magnitude of post-HDT changes, as well as the difference between the last HDT day and R + 0, showed a trend to increase with increasing HDT duration, and 5/7 days were not sufficient for recovering after 60-day HDT. Additionally, the f postponed and the OA significantly increased at R + 0 compared to PRE after 5-day and 60-day HDT, possibly increasing the arrhythmic risk. These results provide evidence that continuous monitoring of astronauts’ circadian rhythms, and further investigations on possible measures for counteracting the observed modifications, will be key for future missions including long periods of weightlessness and gravity transitions, for preserving astronauts’ health and mission success

A new numerical method for obtaining gluon distribution functions G(x,Q2)=xg(x,Q2)G(x,Q^2)=xg(x,Q^2), from the proton structure function F2γp(x,Q2)F_2^{\gamma p}(x,Q^2)

An exact expression for the leading-order (LO) gluon distribution function $G(x,Q^2)=xg(x,Q^2)$ from the DGLAP evolution equation for the proton structure function $F_2^{\gamma p}(x,Q^2)$ for deep inelastic $\gamma^* p$ scattering has recently been obtained [M. M. Block, L. Durand and D. W. McKay, Phys. Rev. D{\bf 79}, 014031, (2009)] for massless quarks, using Laplace transformation techniques. Here, we develop a fast and accurate numerical inverse Laplace transformation algorithm, required to invert the Laplace transforms needed to evaluate $G(x,Q^2)$, and compare it to the exact solution. We obtain accuracies of less than 1 part in 1000 over the entire $x$ and $Q^2$ spectrum. Since no analytic Laplace inversion is possible for next-to-leading order (NLO) and higher orders, this numerical algorithm will enable one to obtain accurate NLO (and NNLO) gluon distributions, using only experimental measurements of $F_2^{\gamma p}(x,Q^2)$.Comment: 9 pages, 2 figure

The formal and informal surgical ethics curriculum: views of resident and staff surgeons in Toronto.

BACKGROUND: Understanding what staff surgeons think surgical trainees should learn and the ethical issues that trainees need to manage can strengthen surgical ethics education. METHODS: Participants were recruited from the 15 surgical specialty and subspecialty programs at the University of Toronto. Semistructured interviews and focus groups were conducted with 13 ethics coordinators from the surgical staff and 64 resident trainees. Data were analyzed qualitatively using modified thematic analysis. RESULTS: All coordinators and trainees felt that ethics education was an important component of surgical training. Real cases, varying teaching methods, and teachers with applicable clinical experience were valued. Trainees identified intraprofessional and interprofessional conflict, staff behavior perceived to be unethical, and their own lack of experience as challenging issues rarely addressed in the formal ethics curriculum. CONCLUSIONS: Ethics education is highly valued by trainees and teachers. Some ethical issues important to trainees are underrepresented in the formal curriculum. Staff surgeons and senior residents are practicing ethicists and role models whose impact on the moral development of residents is profound. Their participation in the formal curriculum helps less experienced junior residents realize its value

On parton distributions beyond the leading order

The importance of properly taking into account the factorization scheme dependence of parton distribution functions is emphasized. A serious error in the usual handling of this topic is pointed out and the correct procedure for transforming parton distribution functions from one factorisation scheme to another recalled. It is shown that the conventional $\overline{\rm {MS}}$ and DIS definitions thereof are ill-defined due to the lack of distinction between the factorisation scheme dependence of parton distribution functions and renormalisation scheme dependence of the strong coupling constant $\alpha_s$. A novel definition of parton distribution functions is suggested and its role in the construction of consistent next-to-leading order event generators briefly outlined.Comment: PRA-HEP-93/05, Latex, 10 pages and 2 Postscript figures appended at the end of this fil

Effective computer-aided assessment of mathematics; principles, practice and results

This article outlines some key issues for writing effective computer-aided assessment (CAA) questions in subjects with substantial mathematical or statistical content, especially the importance of control of random parameters and the encoding of wrong methods of solution (mal-rules) commonly used by students. The pros and cons of using CAA and different question types are discussed. Issues surrounding the selection and encoding of mal-rules are highlighted, especially for multi-choice and responsive numerical input questions. These generate mal-rule-specific feedback, the mal-rule used being deduced 15 from the student’s selection or input. Student answer file data from the use of over 800 questions and their embedding within an overall assessment regime is analysed and presented to show that this has had a very beneficial effect on the examination performance of a large cohort of first-year economics students in their mathematics module over the last 6 years. Question analysis of over 270,000 question attempts, identifying the most 20 difficult/discriminating questions, shows that the questions are robust, valid and span an appropriate range of difficulties. The idea of underlying mal-rules is examined to see how far this explains this range

Joint resummation in electroweak boson production

We present a phenomenological application of the joint resummation formalism to electroweak annihilation processes at measured boson momentum Q_T. This formalism simultaneously resums at next-to-leading logarithmic accuracy large threshold and recoil corrections to partonic scattering. We invert the impact parameter transform using a previously described analytic continuation procedure. This leads to a well-defined, resummed perturbative cross section for all nonzero Q_T, which can be compared to resummation carried out directly in Q_T space. From the structure of the resummed expressions, we also determine the form of nonperturbative corrections to the cross section and implement these into our analysis. We obtain a good description of the transverse momentum distribution of Z bosons produced at the Tevatron collider.Comment: 27 pages, LaTeX, 8 figures as eps files. Some additions to earlier version, this version as published in Phys. Rev. D66 (2002) 01401