Line shape of the muH(3p - 1s) hyperfine transitions

The (3p - 1s) X-ray transition to the muonic hydrogen ground state was measured with a high resolution crystal spectrometer. A Doppler effect broadening of the X-ray line was established which could be attributed to different Coulomb de-excitation steps preceding the measured transition. The assumption of a statistical population of the hyperfine levels of the muonic hydrogen ground state was directly confirmed by the experiment and measured values for the hyperfine splitting can be reported. The results allow a decisive test of advanced cascade model calculations and establish a method to extract fundamental strong-interaction parameters from pionic hydrogen experiments.Comment: Submitted to Physical Review Letter

Facial features of patients with sickle cell anemia

Objective: To characterize the craniofacial features of patients with sickle cell anemia (SCA). Materials and Methods: Fifty patients with SCA in the north of Minas Gerais, Brazil, were evaluated using standardized photographs (front and profile) for a subjective facial analysis and digital radiographs for a computerized cephalometric analysis. To obtain linear and angular measurements, cephalometric points were marked on the digital images by a single examiner, using the program Radiocef 6.0, and facial analyses were performed by four different orthodontists. Results: Of the population studied, 28 patients were female with a mean age of 27.7 years. Most of the patients (64%) had their faces classified as esthetically acceptable, although results showed a predominance of convex profiles (72%). The mean of the SNA angle was 84.56 degrees, diagnosing proper positioning of the maxilla from the base of the skull. The prevalence of pattern II was 32%, and 31% showed maxillary protrusion; the effective length of the maxilla was reduced in 64%. Retrusion of the mandible was observed in 30%, and 76% had reduced mandibular length. Four measurements (mandibular length, maxillary length, anterior face height, and maxillomandibular difference) showed statistically significant differences between genders, where these measurements were higher for males than for females. Conclusion: Most patients did not show compensatory maxillary expansion, which was determined by the prevalence of decreased maxillary length (64%) and by the absence of maxillary protrusion in 69% of the SCA patients evaluated. (Angle Orthod. 2011;81:115-120.)811115120Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG

Pionic Deuterium

The strong interaction shift and broadening in pionic deuterium have been remeasured with high statistics by means of the (3p-1s) X-ray transition using the cyclotron trap and a high-resolution crystal spectrometer. Preliminary results are (-2325+/-31) meV (repulsive) for the shift and (1171+23/-49} meV for the width, which yields precise values for the pion-deuteron scattering length and the threshold parameter for pion production.Comment: Conf. Proc. Few Body 19 (FB19), August 31 - September 5, 2009, Bonn, Germany 9 pages, 13 figure

Precision determination of the dpi -> NN transition strength at threshold

An unusual but effective way to determine at threshold the dpi -> NN transition strength is to exploit the hadronic ground-state broadening in pionic deuterium, accessible by x-ray spectroscopy. The broadening is dominated by the true absorption channel dpi- -> nn, which is related to s-wave pion production pp -> dpi+ by charge symmetry and detailed balance. Using the exotic atom circumvents the problem of Coulomb corrections to the cross section as necessary in the production experiments. Our dedicated measurement finds (1171+23/-49) meV for the broadening yielding (252+5/-11) \mub.Comment: 4 pages, 2 figures, 1 tabl

Line shape analysis of the Kβ\beta transition in muonic hydrogen

The K$\beta$ transition in muonic hydrogen was measured with a high-resolution crystal spectrometer. The spectrum is shown to be sensitive to the ground-state hyperfine splitting, the corresponding triplet-to-singlet ratio, and the kinetic energy distribution in the $3p$ state. The hyperfine splitting and triplet-to-singlet ratio are found to be consistent with the values expected from theoretical and experimental investigations and, therefore, were fixed accordingly in order to reduce the uncertainties in the further reconstruction of the kinetic energy distribution. The presence of high-energetic components was established and quantified in both a phenomenological, i.e. cascade-model-free fit, and in a direct deconvolution of the Doppler broadening based on the Bayesian approach.Comment: 22 pages, 21 figure

A Search for Variations of Fundamental Constants using Atomic Fountain Clocks

Over five years we have compared the hyperfine frequencies of 133Cs and 87Rb atoms in their electronic ground state using several laser cooled 133Cs and 87Rb atomic fountains with an accuracy of ~10^{-15}. These measurements set a stringent upper bound to a possible fractional time variation of the ratio between the two frequencies : (d/dt)ln(nu_Rb/nu_Cs)=(0.2 +/- 7.0)*10^{-16} yr^{-1} (1 sigma uncertainty). The same limit applies to a possible variation of the quantity (mu_Rb/mu_Cs)*alpha^{-0.44}, which involves the ratio of nuclear magnetic moments and the fine structure constant.Comment: 4 pages, 3 figures, 1 table submitted to Phys. Rev. Let

Line shape of the μ H(3 p - 1 s ) transition

The line shape of the (3p − 1s) X-ray transition in muonic hydrogen was measured for the first time with a high-resolution crystal spectrometer. The assumption of a statistical population of the hyperfine levels was directly confirmed by experiment, and a measured value for the hyperfine splitting is reported. An X-ray line broadening due to Doppler effect could be clearly identified and attributed to different Coulomb de-excitation transitions which precede the measured radiative transition. The results allow a decisive test of advanced cascade model calculations and establish an alternative and "model free” method to extract the strong-interaction parameters from pionic hydrogen dat

Mean-field description of collapsing and exploding Bose-Einstein condensates

We perform numerical simulation based on the time-dependent mean-field Gross-Pitaevskii equation to understand some aspects of a recent experiment by Donley et al. on the dynamics of collapsing and exploding Bose-Einstein condensates of $^{85}$Rb atoms. They manipulated the atomic interaction by an external magnetic field via a Feshbach resonance, thus changing the repulsive condensate into an attractive one and vice versa. In the actual experiment they changed suddenly the scattering length of atomic interaction from positive to a large negative value on a pre-formed condensate in an axially symmetric trap. Consequently, the condensate collapses and ejects atoms via explosion. We find that the present mean-field analysis can explain some aspects of the dynamics of the collapsing and exploding Bose-Einstein condensates.Comment: 9 Latex pages, 10 ps and eps files, version accepted in Physical Review A, minor changes mad

Rethinking Serious Games Design in the Age of COVID-19: Setting the Focus on Wicked Problems

We live in a complex world, in which our existence is defined by forces that we cannot fully comprehend, predict, nor control. This is the world of wicked problems, of which the situation triggered by the COVID-19 pandemic is a notable example. Wicked problems are complex scenarios defined by the interplay of multiple environmental, social and economic factors. They are everchanging, and largely unpredictable and uncontrollable. As a consequence, wicked problems cannot be definitively solved through traditional problem-solving approaches. Instead, they should be iteratively managed, recognizing and valuing our connectedness with each other and the environment, and engaging in joint thinking and action to identify and pursue the common good. Serious games can be key to foster wicked problem management abilities. To this end, they should engage players in collective activities set in contexts simulating real-world wicked problem scenarios. These should require the continuous interpretation of changing circumstances to identify and pursue shared goals, promoting the development of knowledge, attitudes and skill sets relevant to tackle real-world situations. In this paper we outline the nature, implications and challenges of wicked problems, highlighting why games should be leveraged to foster wicked problem management abilities. Then, we propose a theory-based framework to support the design of games for this purpose

The spatial aspects of fairness

As well as their family background, an individual's chances in life are determined by the opportunities available to them in their geographical context. This chapter therefore deals with the spatial aspects of fairness. It focuses, firstly, on socio-economic factors which are not randomly distributed in space (i.e. they have a geographical pattern). Secondly, it focuses, not on first nature geographical differences which cannot be changed (such as the presence of mountains), but on second nature geographical factors (such as access to basic services or hospitals) which can be altered and which are important in overcoming a region's natural disadvantages. It then links the two