710 research outputs found
Closed form representations for the compactly supported radial basis functions of Buhmann, Wendland and Wu
No full textThe original compactly supported radial basis functions of Wendland and Wu have a polynomial form and are constructed using a two-step dimension walk strategy. Focussing on the Wendland functions, Schaback proposed a one-step dimension walk which is shown to recover the original Wendland functions at every second step but also introduces new examples, the so-called missing Wendland functions at the intermediate steps. In a recent paper by Huang et at., the analogue of Schaback's work is presented for the Wu functions and so deliver the so-called missing Wu functions. The original and missing Wendland functions belong to a much wider class proposed by Buhmann. The classical Buhmann functions, which are related to thin-plate spline radial basis functions, also belong to this much wider class. The theme uniting the classical Buhmann functions and the missing Wendland/Wu functions is that they are
non-polynomial and closed form expressions are not known for all of them. In this paper we revisit these functions and show how closed form representations can be given using direct techniques. The results for the classical Buhmann and Wu functions are new and the resulting expressions for the missing Wendland functions improve on those given iby the first author and so their implementation should be more straightforward
Dynamical Casimir-Polder interaction between a chiral molecule and a surface
No full textWe develop a dynamical approach to study the Casimir-Polder force between an initially bare molecule and a magnetodielectric body at finite temperature, valid for arbitrary magnetodielectric properties and also in the presence of chiral effects. Switching on the interaction between the molecule and the field at a particular time, we study the resulting temporal evolution of the Casimir-Polder interaction. The dynamical self-dressing of the molecule and its population-induced dynamics are accounted for and discussed. In particular, we find that the Casimir-Polder force between a molecule and a surface oscillates in time with a frequency related to the molecular transition frequency. We verify that the dynamical force converges to the static result for time much larger than the inverse of the transition frequency, and it is particularly strong around the back-reaction time t=2d/c, the time needed for the molecule to emit and reabsorb a photon reflected by the surface
Van der Waals interactions between excited atoms in generic environments
No full textWe consider the van der Waals force involving excited atoms in general environments, constituted by magnetodielectric bodies. We develop a dynamical approach studying the dynamics of the atoms and the field, mutually coupled. When only one atom is excited, our dynamical theory suggests that for large distances the van der Waals force acting on the ground-state atom is monotonic, while the force acting in the excited atom is spatially oscillating. We show how this latter force can be related to the known oscillating Casimir-Polder force on an excited atom near a (ground-state) body. Our force also reveals a population-induced dynamics: for times much larger that the atomic lifetime the atoms will decay to their ground states leading to the van der Waals interaction between ground-state atoms
Quality of Fundamental Movement Patterns in Chronic Low Back Pain Patients A Quasi-experimental Cross-sectional Study
No full textBackground: Chronic back pain may be associated with alterations of motor control and maladaptive movement. However, instruments that systematically screen fundamental movement patterns are rare. Using a newly developed functional movement analysis, this study aims to examine whether persons with chronic unspecific low back pain display altered quality of fundamental movement patterns and whether asymmetry exists between body sides. Subjects/Methods: 20 patients with chronic back pain (female = 8, male = 12; 49.4 +/- 11.3 years) and 20 healthy controls (female = 12, male = 8; 47.7 +/- 10.7 years) completed the functional movement analysis. It consists of 11 items screening movements of daily life. 8 of them were to complete left and right. The overall score and the number of observed asymmetries (in items to complete left and right) constituted the primary outcomes. A preliminary analysis of reliability (4 raters, 4 subjects) with pilot character was conducted using intra-class correlation (ICC). To compare differences in means, independent t-tests were performed. In case of significance, we calculated the effect size (Cohen's d). Results: The reliability analysis showed an ICC (2.1) of 0.82 (95 % CI: 0.72 - 0.90). Patients with chronic low back pain (31.95 +/- 5.82) scored significantly lower than healthy subjects (44.01 +/- 5.27; p < 0.001, d = 2.17). Additionally, patients averaged 3.8 +/- 1.28 asymmetries while pain-free participants only demonstrated 1.4 +/- 0.94 (p < 0.001; d = 2.14). Conclusion: Faulty and dysbalanced movement patterns appear to be linked to chronic low back pain. Nonetheless, given an existing relation, it remains unclear whether the detected deficiencies are causes or consequences of pain. Further studies about the reliability of the presented screening tool are needed
sj-docx-1-nms-10.1177_14614448211056863 – Supplemental material for Professionals, purpose-seekers, and passers-through: How microworkers reconcile alienation and platform commitment through identity work
No full textSupplemental material, sj-docx-1-nms-10.1177_14614448211056863 for Professionals, purpose-seekers, and passers-through: How microworkers reconcile alienation and platform commitment through identity work by Eliane Bucher, Christian Fieseler, Christoph Lutz and Alexander Buhmann in New Media & Society</p
Tuning the collective decay of two entangled emitters by means of a nearby surface
No full textWe consider the radiative properties of a system of two identical correlated atoms interacting with the electromagnetic field in its vacuum state in the presence of a generic dielectric environment. We suppose that the two emitters are prepared in a symmetric or antisymmetric superposition of one ground state and one excited state and we evaluate the transition rate to the collective ground state, showing distinctive cooperative radiative features. Using a macroscopic quantum electrodynamics approach to describe the electromagnetic field, we first obtain an analytical expression for the decay rate of the two entangled two-level atoms in terms of the Green's tensor of the generic external environment. We then investigate the emission process when both atoms are in free space and, subsequently, when a perfectly reflecting mirror is present, showing how the boundary affects the physical features of the superradiant and subradiant emission by the two coupled emitters. The possibility to control and tailor radiative processes is also discussed
Quantum tunneling through planar p-n junctions in HgTe quantum wells
No full textWe demonstrate that a p-n junction created electrically in HgTe quantum wells with inverted band structure exhibits interesting intraband and interband tunneling processes. We find a perfect intraband transmission for electrons injected perpendicularly to the interface of the p-n junction. The opacity and transparency of electrons through the p-n junction can be tuned by changing the incidence angle, the Fermi energy and the strength of the Rashba spin-orbit interaction (RSOI). The occurrence of a conductance plateau due to the formation of topological edge states in a quasi-one-dimensional (Q1D) p-n junction can be switched on and off by tuning the gate voltage. The spin orientation can be substantially rotated when the samples exhibit a moderately strong RSOI
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Changing sustainability norms through communication processes:the emergence of the business and human rights regime as transnational law /
No full textApplying the emergent Business and Human Rights (BHR) regime as a case, this book analyses regulatory strategies, communicative approaches and public-private processes to develop new sustainability-related norms, particularly for business, for maintaining and promoting public policy objectives and societal needs. Karin Buhmann sets out the concerns of public regulators and businesses that both inform debates and create power struggles in the construction of sustainability norms between public policy interests and the market. The author focuses on three trends in argumentative strategies applied in the BHR context and considers the use, impact and complementarity of these for sustainability regulation. Through analysis of selected transnational regulatory processes, the book identifies argumentative and negotiation strategies that led to agreement on BHR despite conflicting interests across public, private and not-for-profit (NGO) stakeholders, and develops insights for future multi-stakeholder sustainability regulation, focusing both on the regulatory process and the outcome. Changing Sustainability Norms through Communication Processes will be a valuable read for NGOs, regulators, managers and academics with a concern for sustainability regulation by helping to enhance their understanding of how to influence normative change in organisations, in support of sustainability and responsible business conduct
Dynamical Casimir-Polder force between an excited atom and a conducting wall
No full textWe consider the dynamical atom-surface Casimir-Polder force in the nonequilibrium configuration of an atom near a perfectly conducting wall, initially prepared in an excited state with the field in its vacuum state. We evaluate the time-dependent Casimir-Polder force on the atom and find that it shows an oscillatory behavior from attractive to repulsive both in time and in space. We also investigate the asymptotic behavior in time of the dynamical force and of related local field quantities, showing that the static value of the force, as obtained by a time-independent approach, is recovered for times much longer than the time scale of the atomic self-dressing but shorter than the atomic decay time. We then discuss the evolution of global quantities such as atomic and field energies and their asymptotic behavior. We also compare our results for the dynamical force on the excited atom with analogous results recently obtained for an initially bare ground-state atom. We show that new relevant features are obtained in the case of an initially excited atom, for example, much larger values of the dynamical force with respect to the static one, allowing for an easier way to single out and observe the dynamical Casimir-Polder effect
sj-docx-1-jdr-10.1177_00220345231200786 – Supplemental material for Preinterventional Third-Molar Assessment Using Robust Machine Learning
No full textSupplemental material, sj-docx-1-jdr-10.1177_00220345231200786 for Preinterventional Third-Molar Assessment Using Robust Machine Learning by J.S. Carvalho, M. Lotz, L. Rubi, S. Unger, T. Pfister, J.M. Buhmann and B. Stadlinger in Journal of Dental Research</p
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