Chiral Corrections to the Hyperon Vector Form Factors

We present the complete calculation of the SU(3)-breaking corrections to the hyperon vector form factors up to O(p^4) in the Heavy Baryon Chiral Perturbation Theory. Because of the Ademollo-Gatto theorem, at this order the results do not depend on unknown low energy constants and allow to test the convergence of the chiral expansion. We complete and correct previous calculations and find that O(p^3) and O(1/M_0) corrections are important. We also study the inclusion of the decuplet degrees of freedom, showing that in this case the perturbative expansion is jeopardized. These results raise doubts on the reliability of the chiral expansion for hyperons.Comment: 20 pages, 4 figures, v2: published versio

Quantum Monte Carlo study of a positron in an electron gas

Quantum Monte Carlo calculations of the relaxation energy, pair-correlation function, and annihilating-pair momentum density are presented for a positron immersed in a homogeneous electron gas. We find smaller relaxation energies and contact pair-correlation functions in the important low-density regime than predicted by earlier studies. Our annihilating-pair momentum densities have almost zero weight above the Fermi momentum due to the cancellation of electron-electron and electron-positron correlation effects

Surface properties of SmB6 from x-ray photoelectron spectroscopy

We have investigated the properties of cleaved SmB$_6$ single crystals by x-ray photoelectron spectroscopy. At low temperatures and freshly cleaved samples a surface core level shift is observed which vanishes when the temperature is increased. A Sm valence between 2.5 - 2.6 is derived from the relative intensities of the Sm$^{2+}$ and Sm$^{3+}$ multiplets. The B/Sm intensity ratio obtained from the core levels is always larger than the stoichiometric value. Possible reasons for this deviation are discussed. The B $1s$ signal shows an unexpected complexity: an anomalous low energy component appears with increasing temperature and is assigned to the formation of a suboxide at the surface. While several interesting intrinsic and extrinsic properties of the SmB$_6$ surface are elucidated in this manuscript no clear indication of a trivial mechanism for the prominent surface conductivity is found

Labels for non-individuals

Quasi-set theory is a first order theory without identity, which allows us to cope with non-individuals in a sense. A weaker equivalence relation called ``indistinguishability'' is an extension of identity in the sense that if $x$ is identical to $y$ then $x$ and $y$ are indistinguishable, although the reciprocal is not always valid. The interesting point is that quasi-set theory provides us a useful mathematical background for dealing with collections of indistinguishable elementary quantum particles. In the present paper, however, we show that even in quasi-set theory it is possible to label objects that are considered as non-individuals. We intend to prove that individuality has nothing to do with any labelling process at all, as suggested by some authors. We discuss the physical interpretation of our results.Comment: 11 pages, no figure

Shear-current effect in a turbulent convection with a large-scale shear

The shear-current effect in a nonrotating homogeneous turbulent convection with a large-scale constant shear is studied. The large-scale velocity shear causes anisotropy of turbulent convection, which produces the mean electromotive force \bec{\cal E}^{(W)} \propto {\bf W} {\bf \times} {\bf J} and the mean electric current along the original mean magnetic field, where ${\bf W}$ is the background mean vorticity due to the shear and ${\bf J}$ is the mean electric current. This results in a large-scale dynamo even in a nonrotating and nonhelical homogeneous sheared turbulent convection, whereby the $\alpha$ effect vanishes. It is found that turbulent convection promotes the shear-current dynamo instability, i.e., the heat flux causes positive contribution to the shear-current effect. However, there is no dynamo action due to the shear-current effect for small hydrodynamic and magnetic Reynolds numbers even in a turbulent convection, if the spatial scaling for the turbulent correlation time is $\tau(k) \propto k^{-2}$, where $k$ is the small-scale wave number.Comment: 8 pages, Physical Review E, in pres

Interdisciplinary system architectures in agile modular development in the product generation development model using the example of a machine tool manufacturer

This paper considers the orientation of product development structures towards interdisciplinary system architectures using the example of a tool machine manufacturer. Due to the change from simple mechanical products to extensively designed systems, whose successful development requires the integration of all disciplines involved, it is analyzed which requirements there are for these interdisciplinary system architectures in today\u27s development environment. In addition, it is validated on the basis of the investigation environment that interdisciplinary system structures are necessary for the development on the different levels of the system view. In doing so, the investigation environment addresses the concept of extracting customer-relevant features (systems) from a physical-tailored modular system (supersystem) in order to develop and test them autonomously, as well as to transfer them to the entire product range in a standardized manner. The elaboration identifies basic requirements for the development of a knowledge base in interdisciplinary system structures and places them into the context of an agile modular kit development

Evaluating palliative care training in the oncology registrar programme in South Africa

Background. Following a World Health Assembly call in 2014 to strengthen palliative care, the South African (SA) Department of Health approved this strategy as part of the SA National Policy Framework and Strategy on Palliative Care. In 2016, the University of Cape Town, together with the College of Radiation Oncology of SA, identified the need to integrate palliative care (PC) into the oncology curriculum. In collaboration with the Cancer Association of SA, a research project was developed to introduce a 12-module curriculum at five teaching hospitals. The aim of this research was to evaluate the impact of a 1-year PC course within the training programme for specialist oncologists in SA. Objective. To determine the reaction of oncology registrars and their supervisors to the course to determine changes in knowledge and skills, and to determine the application in oncology practice. Methods. This study was a mixed-method prospective evaluation of an educational intervention. The educational programme used a blended learning method to train and support registrars (n=32) and facilitators (n=5) across five universities from August 2017 to September 2018. Evaluation feedback was electronically collected to determine the registrars’ reactions to the course materials. Pre and post multiple-choice questions (MCQs) were used to review their knowledge. Focus group discussions (FGDs) were used to explore reactions, change in knowledge and skills and how registrars integrated PC into their daily work. Results. There was an overwhelmingly positive reaction to the PC course by the oncology registrars and their supervisors. The training was found to be feasible, and the topics addressed appropriate. Concerns previously raised by the College of Radiation Oncology of SA regarding the feasibility and appropriateness of the course and material were found to be unsubstantiated. The poor MCQ results can be ascribed to poor sequencing of the execution of the question. However, the MCQs in modules 7 and 8 (symptom management) demonstrated the most significant change in knowledge and skills (symptom management). The FGDs demonstrated a perceived change in knowledge and skills, especially for communication skills and pain and symptom management. The FGDs also indicated that the registrars’ approach to PC changed in that they were able to integrate the principles of PC into practice, and now saw PC as an essential component of oncology. Lastly, registrars and their supervisors felt that the course addressed topics that formed part of their daily clinical work. Conclusion. This research supports the view that PC training is an essential component of oncology training in the SA setting. PC forms part of the daily practice of oncologists, and a structured curriculum prepares clinicians to be able to integrate evidence-based PC into the practice of oncology if they receive appropriate training. Supervisors of the oncology training programme and registrars are confident that the training of 12 modules across 1 year is feasible and appropriate