Early vs late string networks from a minimal QCD axion

We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such that the Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to a novel cosmological evolution, in which strings and domain walls re-enter the horizon and annihilate later than in the ordinary post-inflationary regime, possibly even after the QCD crossover. Such dynamics can occur if the PQ symmetry is restored by inflationary fluctuations, i.e. the Hubble parameter during inflation HI is larger than the PQ breaking scale fa, but it is not thermally restored afterwards. Solving the Fokker-Planck equation, we estimate the number of inflationary e-folds required for the PQ symmetry to be, on average, restored. Moreover, we show that, in the large parts of parameter space where the radial mode is displaced from the minimum by de Sitter fluctuations, a string network forms due to the radial mode oscillating over the top of its potential after inflation. In both cases we identify order one ranges in HI/fa and in the quartic coupling λ of the PQ potential that lead to the late-string dynamics. In this regime the cosmological dark matter abundance can be reproduced for axion decay constants as low as the astrophysical constraint (108) GeV, corresponding to axion masses up to 10−2 eV, and with miniclusters with masses as large as (10)M⊙

Early vs late string networks from a minimal QCD Axion

We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such that the Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to a novel cosmological evolution, in which strings and domain walls re-enter the horizon and annihilate later than in the ordinary post-inflationary regime, possibly even after the QCD crossover. Such dynamics can occur if the PQ symmetry is restored by inflationary fluctuations, i.e. the Hubble parameter during inflation $H_I$ is larger than the PQ breaking scale $f_a$, but it is not thermally restored afterwards. Solving the Fokker-Planck equation, we estimate the number of inflationary e-folds required for the PQ symmetry to be, on average, restored. Moreover, we show that, in the large parts of parameter space where the radial mode is displaced from the minimum by de Sitter fluctuations, a string network forms due to the radial mode oscillating over the top of its potential after inflation. In both cases we identify order one ranges in $H_I/f_a$ and in the quartic coupling $\lambda$ of the PQ potential that lead to the late-string dynamics. In this regime the cosmological dark matter abundance can be reproduced for axion decay constants as low as the astrophysical constraint $O(10^8)$ GeV, corresponding to axion masses up to $10^{-2}~{\rm eV}$, and with miniclusters with masses as large as $O(10)M_\odot$.Comment: 31 pages + appendice

Stochastic Resonance Training Improves Balance and Musculoskeletal Well-Being in Office Workers: A Controlled Preventive Intervention Study

Sixty-two office workers in a Swiss federal department were randomly assigned to a training and a control group. While the training group was instructed to complete 3 stochastic resonance whole-body vibration (SR-WBV) exercises every week for 4 weeks, the control group received no treatment. During this time all participants answered a daily questionnaire concerning their surefootedness, sense of balance, musculoskeletal well-being, and muscle relaxation. Before and after the 4-week SR-WBV intervention, balance was tested with a single-leg stance on a foam mat of the Balance Error Scoring System (BESS) using a SwayStar™-System measuring Total Angle Area (TotAngArea) and Total Velocity Area (TotVelArea). Multilevel results highlighted a significant increase over time for surefootedness and sense of balance (t = 2.491, p = .016), as well as for musculoskeletal well-being and muscle relaxation (t = 2.538, p = .014) in the training group but not in the control group. Balance tests showed improvement of balance in the training group (TotAngArea: Z = 2.550, p = .011; TotVelArea: Z = 3.334, p = .001) but not in the control group. SR-WBV exercise indicated a high compliance during this study (3.87±0.45 trainings per week) underlining its benefits for the working context. Especially office workers who spend most of their time in sitting position could profit from SR-WBV exercise to improve balance and reduce the risk of falls

Constraints on neutrino masses from leptogenesis models

Upper bounds on the CP asymmetry relevant for leptogenesis are reexamined and found weaker than in previous literature, both for hierarchical and for quasi-degenerate right-handed neutrinos. Successful leptogenesis implies the usual lower bound on right-handed neutrino masses, and an upper bound on left-handed neutrino masses (which we obtain to be 0.15eV at 3sigma) only if right-handed neutrinos are assumed to be much more hierarchical than left-handed neutrinos. Otherwise both bounds can be considerably relaxed. The constraint on light neutrino masses varies assuming different interpretations of why neutrinos should be quasi-degenerate. With conservative assumptions, we find that a mild quasi-degeneracy allows neutrinos heavier than an eV compatibly with leptogenesis. We also extend computations of thermal leptogenesis to an alternative model of neutrino mass mediated by fermion triplets which was never considered so far for leptogenesis. Leptogenesis can be successful despite the effect of gauge interactions, resulting in only slightly stronger constraints on neutrino masses.Comment: 16 pages, 6 figure

Exploring Cosmic Origins with CORE: Cosmological Parameters

We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED

K.3.1 [Computer Uses in Education]: Collaborative learning.

Learning effectiveness depends on a large range of parameters. Learners ’ activity has an important impact on long-term learning and comprehension of difficult concepts [1]. Collaboration is also an important parameter for learning efficiency. Collaboration does not work per se [2]; an appropriate Script is a capital factor for succeeding. We will describe our engagement in scripting advises based on the use of a Wiki. The creation of a hypertext is an integrative part of our collaborative script. A Wiki is a powerful tool for constructivist learning environments because it facilitates collaboration. The workshop aims to describe approaches to improve collaborative learning. We will give advice how to conduct a learning session with a Wiki and an appropriate script

Social skills as predictors of communication, performance and quality of collaboration in project-based learning

The assumption that social skills are necessary ingredients of collaborative learning is well established but rarely empirically tested. In addition, most theories on collaborative learning focus on social skills only at the personal level, while the social skill configurations within a learning group might be of equal importance. Using the integrative framework, this study investigates which social skills at the personal level and at the group level are predictive of task-related e-mail communication, satisfaction with performance and perceived quality of collaboration. Data collection took place in a technology-enhanced long-term project-based learning setting for pre-service teachers. For data collection, two questionnaires were used, one at the beginning and one at the end of the learning cycle which lasted 3 months. During the project phase, the e-mail communication between group members was captured as well. The investigation of 60 project groups (N = 155 for the questionnaires; group size: two or three students) and 33 groups for the e-mail communication (N = 83) revealed that personal social skills played only a minor role compared to group level configurations of social skills in predicting satisfaction with performance, perceived quality of collaboration and communication behaviour. Members from groups that showed a high and/or homogeneous configuration of specific social skills (e.g., cooperation/compromising, leadership) usually were more satisfied and saw their group as more efficient than members from groups with a low and/or heterogeneous configuration of skills

Computer Generated Voice-Over in a Medical E-Learning Application: The Impact on Factual Learning Outcome

The Medical Faculty of the University of Bern uses voice-over in picture driven e-learning modules to avoid split attention induced by the modality effect. To lower production costs, professional narrators have been replaced by computer-generated voices. The e-learning modules are produced with a content management system (CMS) offering text-to-speech functionality. 107 Swiss high school students passed a 20-minute e-learning sequence on cystic fibrosis. In a nested between-group design with four learning content presentation modalities (written text vs. human voice-over vs. artificial voice-over plus 15"-laptop-screens vs. 2,8"smart-phone screens), the learning outcome was assessed at three points in time: before, just after, and six weeks after the learning phase. All modalities led to significant short-term and long-term increase in factual knowledge about cystic fibrosis. Our two hypotheses are supported: (1) presenting pictures with both human and artificial voice-over leads to the same factual learning outcome, and (2) the e-learning module leads to the same learning outcome and acceptance independent of devices and their screen sizes. Furthermore, the image-voice-over modality on mobile devices (small screens) turned out to be a setting with no significant difference in effectiveness

Early vs late string networks from a minimal QCD Axion

We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such that the Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to a novel cosmological evolution, in which strings and domain walls re-enter the horizon and annihilate later than in the ordinary post-inflationary regime, possibly even after the QCD crossover. Such dynamics can occur if the PQ symmetry is restored by inflationary fluctuations, i.e. the Hubble parameter during inflation $H_I$ is larger than the PQ breaking scale $f_a$, but it is not thermally restored afterwards. Solving the Fokker-Planck equation, we estimate the number of inflationary e-folds required for the PQ symmetry to be, on average, restored. Moreover, we show that, in the large parts of parameter space where the radial mode is displaced from the minimum by de Sitter fluctuations, a string network forms due to the radial mode oscillating over the top of its potential after inflation. In both cases we identify order one ranges in $H_I/f_a$ and in the quartic coupling $\lambda$ of the PQ potential that lead to the late-string dynamics. In this regime the cosmological dark matter abundance can be reproduced for axion decay constants as low as the astrophysical constraint $O(10^8)$ GeV, corresponding to axion masses up to $10^{-2}~{\rm eV}$, and with miniclusters with masses as large as $O(10)M_\odot$