Magnetic properties and spin waves of bilayer magnets in a uniform field

The two-layer square lattice quantum antiferromagnet with spins 1/2 shows a zero-field magnetic order-disorder transition at a critical ratio of the inter-plane to intra-plane couplings. Adding a uniform magnetic field tunes the system to canted antiferromagnetism and eventually to a fully polarized state; similar behavior occurs for ferromagnetic intra-plane coupling. Based on a bond operator spin representation, we propose an approximate ground state wavefunction which covers all phases by means of a unitary transformation. The excitations can be efficiently described as independent bosons; in the antiferromagnetic phase these reduce to the well-known spin waves, whereas they describe gapped spin-1 excitations in the singlet phase. We compute the spectra of these excitations as well as the magnetizations throughout the whole phase diagram.Comment: 12 pages, 9 figs; added references; final version as publishe

Robust Sliced Inverse Regression Procedures

Sliced Inverse Regression (SIR) is a promising technique for the purpose of dimension reduction. Several properties of this relatively new method have been examined already, but little attention has been paid to robustness aspects. We show that SIR is very sensitive towards outliers in the data. Therefore a generalized estimation procedure which allows for robustness properties, especially for a high breakdown point, is proposed

Multi-Agent Based Information Systems For Patient Coordination in Hospitals

The health sector is a central domain in every economy. It is challenged by progressing costs and funding issues. Hospitals play a major role for the examination and treatment of patients. The sequence how patients are assigned to hospital units determines the quality of treatment, the resource utilization, as well as the patients’ overall treatment time. Thus, efficient scheduling of patients in hospitals is crucial. Current approaches disregard the decentral organization in hospitals and neglect the varying pathway of patients since they often focus on one single unit solely. We propose an agent-based coordination mechanism that overcomes these limitations. Patients and hospital resources are modeled as autonomous software agents which follow their own objectives. This reflects the decentralized structure in hospitals. Agents are coordinated by a distributed mechanism where software agents improve their situation through negotiations which moves towards an overall pareto-optimum. We show promising evaluations based on experiments

Protein Dynamics : Comparison of Incoherent Neutron Scattering and Molecular Dynamics Simulation

Proteindynamik und deren Beziehung zur biologischen Funktion von Proteinen ist Gegenstand zahlreicher experimenteller und theoretischer Untersuchungen. In der vorgelegten Arbeit werden Aspekte der Proteindynamik im Pico- und Nanosekundenbereich untersucht. Experimentelle Untersuchungen haben eine Abhaengigkeit zwischen enzymatischer Aktivitaet und atomaren Fluktuationen auf diesen Zeitskalen aufgezeigt. Inkohaerente Neutronenstreuung sowie Molekulardynamiksimulationen stellen geeignete Instrumente zur Untersuchung atomarer Dynamik auf diesen Zeitskalen zur Verfuegung. Ein interessantes Phaenomen im Hinblick auf den Zusammenhang zwischen Flexibilitaet und Aktivitaet ist die Dynamical Transition, d.h. ein nicht-linearer Anstieg atomarer Fluktuationen bei einer charakteristischen Temperatur T_0 ca. 200K. Die explizite Einbeziehung des instrumentellen Aufloesungsvermoegens eines Neutronenstreuspektrometers in die theoretische Analyse der Dynamical Transition fuehrt zu einer neuen Interpretation dieses Ueberganges. Mittels Molekulardynamiksimulationen wird die quantitative Uebereinstimmung dieser alternativen Interpretation mit der Zeitskalen- wie auch der Temperaturabaengigkeit der mittleren quadratischen Auslenkung eines Proteins in Loesung gezeigt. Darueberhinaus bietet diese Interpretation eine Erklaerung der experimentell beobachteten Verschiebung der Uebergangstemperatur, T_0, in Abhaengigkeit der instrumentellen Aufloesung. Die Gauss'sche Naeherung, grundlegend fuer die experimentelle Bestimmung der mittleren quadratischen Auslenkung, , wird untersucht und Korrekturen hierzu diskutiert. Abweichungen von dieser Naeherung werden fuer Q<6 Ang^{-2} auf die Heterogenitaet atomarer Bewegungen zurueckgefuehrt. Abschliessend wird eine Methode vorgeschlagen, um aus der inkohaerenten inelastischen Streufunktion die Schwingungsdichte des Systems abzuleiten. Mittels dieser Methode werden Aenderungen der Schwingungsdichte des Proteins Dihydrofolate Reduktase bei Bindung des Liganden Methotrexate bestimmt. Es wird gezeigt, dass die Aenderungen im Spektrum dieser internen Freiheitsgrade einen signifikanten Beitrag zur freien Bindungsenergie dieses Systems beitragen

Direct determination of vibrational density of states change on ligand binding to a protein

The change in the vibrational density of states of a protein (dihydrofolate reductase) on binding a ligand (methotrexate) is determined using inelastic neutron scattering. The vibrations of the complex soften significantly relative to the unbound protein. The resulting free-energy change, which is directly determined by the density of states change, is found to contribute significantly to the binding equilibrium

Face masks suitable for preventing COVID-19 and pollen allergy. A study in the exposure chamber

Background: Since the outbreak of the coronavirus pandemic, the population in Germany has been asked to wear face masks in public areas. The masks are accepted by the public. People with a pollen allergy have an interest in knowing whether masks can also provide protection against pollen and thus prevent symptoms even without medication. Method: In order to evaluate the potential 'antipollen effect' of face masks, 14 adults with confirmed grass pollen-induced allergic rhinoconjunctivitis were exposed to grass pollen for a period of two hours following a standardised protocol. The test was conducted outside of the grass pollen season. The subjects wore either no mask, a medical mask or a FFP2 mask. Results: Subjects wearing either mask were clearly able to avoid both nasal and conjunctival symptoms. There were no significant differences between the two masks in terms of effect. Mask wearing to prevent pollen exposure clearly supports overall well-being. Conclusion: Wearing a mask during pollen season can be recommended as an effective nondrug option for people with a pollen allergy. Supplementary information: The online version of this article (10.1007/s40629-021-00180-8) contains supplementary material, which is available to authorized users

Die Testung von Äpfeln auf ihre Allergenität

Apples have several allergens which, when eaten, lead to symptoms in the mouth within 5-10 min-and therefore cannot be eaten by those suffering from apple allergies. In Germany around 7.5 million people have developed specific antibodies against the main allergen (Mal d 1) in apples and are thus sensitized. At least 3.5 million of them develop the sometimes-considerable allergic symptoms as an expression of an Oral Allergy Syndrome. So far there is no drug therapy for this allergy. Apple allergy sufferers can therefore only do without apples entirely, or eat apples that have been heated beforehand or look for varieties that contain few allergens and can therefore be described as "allergy-friendly" apple varieties. Solely determinations of allergens in the laboratory cannot predict whether an apple can be eaten by apple allergy sufferers without allergic symptoms; clinical trials are required for this. We describe a standardized clinical, oral provocation test that can be used to characterize a low-allergen, allergy-friendly apple or apple variety. The results of such at least three-year tests can be used to award the ECARF seal for allergy-friendly products

A Procedure Model for Integrating Retailers into Digital Platforms

The integration into digital platforms is a vital countermeasure for retailers to counter rising customer expectations, emerging competition, and rapid technological developments. To break down the behemoth of integration projects into smaller steps, we synthesized a procedure model incorporating requirements from scientific literature and practice. We applied design science research to derive a well-structured and scientifically sound artifact that was evaluated in eleven interviews with practitioners. Our analysis revealed that integrating retailers into digital platforms can be standardized for different types and depths following specific guidelines outlined in the proposed procedure model of this work. Furthermore, the integration shows many similarities to other domains, especially when considering small- and medium-sized organisations. However, there are some peculiarities for retailers that could rationalize a distinct view on the integration

Musculature adaption in patients with lumbosacral transitional vertebrae: a matched-pair analysis of 46 patients

Objective: Even though lumbosacral transitional vertebrae (LSTV) are one of the most common congenital anomalies of the spine, their effect on surrounding soft tissues is not well-studied. We therefore aimed at analyzing the association between LSTV and changes in volume, mass, symmetry, and degeneration of lumbar and trunk muscles. Materials and methods: Abdomen-pelvis CT scans were analyzed in patients with LSTV and a matched control group. LSTV were classified according to the Castellvi classification. Muscles were segmented from the remaining soft tissue and their cross-sectional area and volume were examined at five defined levels. Threshold segmentation was used to differentiate between muscle fibers and fat tissue. Matched pairs were compared using Wilcoxon rank sum tests. For comparison of categorical data, chi-squared tests were performed and for associations between the degree of fusion and muscle size and degeneration, Spearman's correlation coefficients were calculated. Inter- and intrarater reliabilities were evaluated by computing intraclass correlation coefficients. Results: Forty-six patients with LSTV and 46 controls were included. Muscle volume of the paraspinal and trunk muscles was significantly lower (707.0 cm(3) vs. 809.7 cm(3), p < 0.001) and fatty muscle changes were significantly increased in all but the caudal paravertebral muscles of LSTV patients (M. psoas p < 0.04, M. quadratus lumborum p < 0.001, paravertebral muscles p = 0.011, M. rectus abdominis p < 0.001, M. obliquus abdominis p < 0.001). Correlations between the degree of Castellvi classification and muscle volume were significant (p = 0.001). Conclusion: LSTV are associated with a reduction in muscle volume and an increase in muscle degeneration of both lumbar and trunk muscles

Metric Dynamic Equilibrium Logic

In temporal extensions of Answer Set Programming (ASP) based on linear-time, the behavior of dynamic systems is captured by sequences of states. While this representation reflects their relative order, it abstracts away the specific times associated with each state. In many applications, however, timing constraints are important like, for instance, when planning and scheduling go hand in hand. We address this by developing a metric extension of linear-time Dynamic Equilibrium Logic, in which dynamic operators are constrained by intervals over integers. The resulting Metric Dynamic Equilibrium Logic provides the foundation of an ASP-based approach for specifying qualitative and quantitative dynamic constraints. As such, it constitutes the most general among a whole spectrum of temporal extensions of Equilibrium Logic. In detail, we show that it encompasses Temporal, Dynamic, Metric, and regular Equilibrium Logic, as well as its classic counterparts once the law of the excluded middle is added.Comment: arXiv admin note: text overlap with arXiv:2304.1477