Simulation of spacecraft attitude dynamics using TREETOPS and model-specific computer Codes

The simulation of spacecraft attitude dynamics and control using the generic, multi-body code called TREETOPS and other codes written especially to simulate particular systems is discussed. Differences in the methods used to derive equations of motion--Kane's method for TREETOPS and the Lagrangian and Newton-Euler methods, respectively, for the other two codes--are considered. Simulation results from the TREETOPS code are compared with those from the other two codes for two example systems. One system is a chain of rigid bodies; the other consists of two rigid bodies attached to a flexible base body. Since the computer codes were developed independently, consistent results serve as a verification of the correctness of all the programs. Differences in the results are discussed. Results for the two-rigid-body, one-flexible-body system are useful also as information on multi-body, flexible, pointing payload dynamics

Interaction and Localization of One-electron Orbitals in an Organic Molecule: Fictitious Parameter Analysis for Multi-physics Simulations

We present a new methodology to analyze complicated multi-physics simulations by introducing a fictitious parameter. Using the method, we study quantum mechanical aspects of an organic molecule in water. The simulation is variationally constructed from the ab initio molecular orbital method and the classical statistical mechanics with the fictitious parameter representing the coupling strength between solute and solvent. We obtain a number of one-electron orbital energies of the solute molecule derived from the Hartree-Fock approximation, and eigenvalue-statistical analysis developed in the study of nonintegrable systems is applied to them. Based on the results, we analyze localization properties of the electronic wavefunctions under the influence of the solvent.Comment: 4 pages, 5 figures, the revised version will appear in J. Phys. Soc. Jpn. Vol.76 (No.1

Dimensionality, topology, energy, the cosmological constant, and signature change

Using the concept of real tunneling configurations (classical signature change) and nucleation energy, we explore the consequences of an alternative minimization procedure for the Euclidean action in multiple-dimensional quantum cosmology. In both standard Hartle-Hawking type as well as Coleman type wormhole-based approaches, it is suggested that the action should be minimized among configurations of equal energy. In a simplified model, allowing for arbitrary products of spheres as Euclidean solutions, the favoured space-time dimension is 4, the global topology of spacelike slices being ${\bf S}^1 \times {\bf S}^2$ (hence predicting a universe of Kantowski-Sachs type). There is, however, some freedom for a Kaluza-Klein scenario, in which case the observed spacelike slices are ${\bf S}^3$. In this case, the internal space is a product of two-spheres, and the total space-time dimension is 6, 8, 10 or 12.Comment: 34 pages, LaTeX, no figure

Sick-leave track record and other potential predictors of a disability pension. A population based study of 8,218 men and women followed for 16 years

<p>Abstract</p> <p>Background</p> <p>A number of previous studies have investigated various predictors for being granted a disability pension. The aim of this study was to test the efficacy of sick-leave track record as a predictor of being granted a disability pension in a large dataset based on subjects sampled from the general population and followed for a long time.</p> <p>Methods</p> <p>Data from five ongoing population-based Swedish studies was used, supplemented with data on all compensated sick leave periods, disability pensions granted, and vital status, obtained from official registers. The data set included 8,218 men and women followed for 16 years, generated 109,369 person years of observation and 97,160 sickness spells. Various measures of days of sick leave during follow up were used as independent variables and disability pension grant was used as outcome.</p> <p>Results</p> <p>There was a strong relationship between individual sickness spell duration and annual cumulative days of sick leave on the one hand and being granted a disability pension on the other, among both men and women, after adjustment for the effects of marital status, education, household size, smoking habits, geographical area and calendar time period, a proxy for position in the business cycle. The interval between sickness spells showed a corresponding inverse relationship. Of all the variables studied, the number of days of sick leave per year was the most powerful predictor of a disability pension. For both men and women 245 annual sick leave days were needed to reach a 50% probability of transition to disability. The independent variables, taken together, explained 96% of the variation in disability pension grantings.</p> <p>Conclusion</p> <p>The sick-leave track record was the most important predictor of the probability of being granted a disability pension in this study, even when the influences of other variables affecting the outcome were taken into account.</p

Supersonic Electroweak Baryogenesis: Achieving Baryogenesis for Fast Bubble Walls

Standard electroweak baryogenesis in the context of a first order phase transition is effective in generating the baryon asymmetry of the universe if the broken phase bubbles expand at subsonic speed, so that CP asymmetric currents can diffuse in front of the wall. Here we present a new mechanism for electroweak baryogenesis which operates for supersonic bubble walls. It relies on the formation of small bubbles of the symmetric phase behind the bubble wall, in the broken phase, due to the heating of the plasma as the wall passes by. We apply the mechanism to a model in which the Higgs field is coupled to several singlets, and find that enough baryon asymmetry is generated for reasonable values of the parameter space

Collaborative multidisciplinary learning : quantity surveying students’ perspectives

The construction industry is highly fragmented and is known for its adversarial culture, culminating in poor quality projects not completed on time or within budget. The aim of this study is thus to guide the design of QS programme curricula in order to help students develop the requisite knowledge and skills to work more collaboratively in their multi-disciplinary future workplaces. A qualitative approach was considered appropriate as the authors were concerned with gathering an initial understanding of what students think of multi-disciplinary learning. The data collection method used was a questionnaire which was developed by the Behaviours4Collaboration (B4C) team. Knowledge gaps were still found across all the key areas where a future QS practitioner needs to be collaborative (either as a project contributor or as a project leader) despite the need for change instigated by the multi-disciplinary (BIM) education revolution. The study concludes that universities will need to be selective in teaching, and innovative in reorienting, QS education so that a collaborative BIM education can be effected in stages, increasing in complexity as the students’ technical knowledge grows. This will help students to build the competencies needed to make them future leaders. It will also support programme currency and delivery

Chiral perturbation theory in a magnetic background - finite-temperature effects

We consider chiral perturbation theory for SU(2) at finite temperature $T$ in a constant magnetic background $B$. We compute the thermal mass of the pions and the pion decay constant to leading order in chiral perturbation theory in the presence of the magnetic field. The magnetic field gives rise to a splitting between $M_{\pi^0}$ and $M_{\pi^{\pm}}$ as well as between $F_{\pi^0}$ and $F_{\pi^{\pm}}$. We also calculate the free energy and the quark condensate to next-to-leading order in chiral perturbation theory. Both the pion decay constants and the quark condensate are decreasing slower as a function of temperature as compared to the case with vanishing magnetic field. The latter result suggests that the critical temperature $T_c$ for the chiral transition is larger in the presence of a constant magnetic field. The increase of $T_c$ as a function of $B$ is in agreement with most model calculations but in disagreement with recent lattice calculations.Comment: 24 pages and 9 fig

The Evershed Effect with SOT/Hinode

The Solar Optical Telescope onboard Hinode revealed the fine-scale structure of the Evershed flow and its relation to the filamentary structures of the sunspot penumbra. The Evershed flow is confined in narrow channels with nearly horizontal magnetic fields, embedded in a deep layer of the penumbral atmosphere. It is a dynamic phenomenon with flow velocity close to the photospheric sound speed. Individual flow channels are associated with tiny upflows of hot gas (sources) at the inner end and downflows (sinks) at the outer end. SOT/Hinode also discovered ``twisting'' motions of penumbral filaments, which may be attributed to the convective nature of the Evershed flow. The Evershed effect may be understood as a natural consequence of thermal convection under a strong, inclined magnetic field. Current penumbral models are discussed in the lights of these new Hinode observations.Comment: To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200

Gastroenterologist perceptions of faecal microbiota transplantation

© 2015 Baishideng Publishing Group Inc. All rights reserved. AIM: To explore gastroenterologist perceptions towards and experience with faecal microbiota transplantation (FMT). METHODS: A questionnaire survey consisting of 17 questions was created to assess gastroenterologists' attitude towards and experience with FMT. This was anonymously distributed in hard copy format amongst attendees at gastroenterology meetings in Australia between October 2013 and April 2014. Basic descriptive statistical analyses were performed. RESULTS: Fifty-two clinicians participated. Twenty one percent had previously referred patients for FMT, 8% more than once. Ninety percent would refer patients with Clostridium difficile infection (CDI) for FMT if easily available, 37% for ulcerative colitis, 13% for Crohn's disease and 6% for irritable bowel syndrome. Six percent would not refer any indication, including recurrent CDI. Eighty-six percent would enroll patients in FMT clinical trials. Thirty-seven percent considered the optimal mode of FMT administration transcolonoscopic, 17% nasoduodenal, 13% enema and 8% oral capsule. The greatest concerns regarding FMT were: 42% lack of evidence, 12% infection risk, 10% non infectious adverse effects/lack of safety data, 10% aesthetic, 10% lack of efficacy, 4% disease exacerbation, and 2% inappropriate use; 6% had no concerns. Seventy seven percent believed there is a lack of accessibility while 52% had an interest in learning how to provide FMT. Only 6% offered FMT at their institution. CONCLUSION: Despite general enthusiasm, most gastroenterologists have limited experience with, or access to, FMT. The greatest concerns were lack of supportive evidence and safety issues. However a significant proportion would refer indications other than CDI for FMT despite insufficient evidence. These data provide guidance on where education and training are required