Auxiliary space preconditioning in H 0(curl; Ω)

We adapt the principle of auxiliary space preconditioning as presented in [J. Xu, The auxiliary space method and optimal multigrid preconditioning techniques for unstructured grids, Computing, 56 (1996), pp. 215-235.] to H (curl; ω)-elliptic variational problems discretized by means of edge elements. The focus is on theoretical analysis within the abstract framework of subspace correction. Employing a Helmholtz-type splitting of edge element vector fields we can establish asymptotic h-uniform optimality of the preconditioner defined by our auxiliary space metho

Gravimeter search for compact dark matter objects moving in the Earth

Dark matter could be composed of compact dark objects (CDOs). These objects may interact very weakly with normal matter and could move freely {\it inside} the Earth. A CDO moving in the inner core of the Earth will have an orbital period near 55 min and produce a time dependent signal in a gravimeter. Data from superconducting gravimeters rule out such objects moving inside the Earth unless their mass $m_D$ and or orbital radius $a$ are very small so that $m_D\, a < 1.2\times 10^{-13}M_\oplus R_\oplus$. Here $M_\oplus$ and $R_\oplus$ are the mass and radius of the Earth.Comment: 8 pages, 7 figure

Avalanches and Dynamical Correlations in supercooled liquids

We identify the pattern of microscopic dynamical relaxation for a two dimensional glass forming liquid. On short timescales, bursts of irreversible particle motion, called cage jumps, aggregate into clusters. On larger time scales, clusters aggregate both spatially and temporally into avalanches. This propagation of mobility, or dynamic facilitation, takes place along the soft regions of the systems, which have been identified by computing isoconfigurational Debye-Waller maps. Our results characterize the way in which dynamical heterogeneity evolves in moderately supercooled liquids and reveal that it is astonishingly similar to the one found for dense glassy granular media.Comment: 4 pages, 3 figure

Dynamic facilitation explains democratic particle motion of metabasin transitions

Transitions between metabasins in supercooled liquids seem to occur through rapid "democratic" collective particle rearrangements. Here we show that this apparent homogeneous particle motion is a direct consequence of dynamic facilitation. We do so by studying metabasin transitions in facilitated spin models and constrained lattice gases. We find that metabasin transitions occur through a sequence of locally facilitated events taking place over a relatively short time frame. When observed on small enough spatial windows these events appear sudden and homogeneous. Our results indicate that metabasin transitions are essentially "non-democratic" in origin and yet another manifestation of dynamical heterogeneity in glass formers.Comment: 6 pages, 6 figure

Shuntchirurgie in Europa und den USA: Ein kritischer Vergleich

Zusammenfassung: Nach einem anfänglich gemeinsamen Weg in der Fistelchirurgie begann in den USA ab etwa 1975 der bevorzugte Einsatz von Prothesenshunts. In bis zu 80% wurden bei Erstoperationen Gefäßprothesen implantiert, mit entsprechend hoher Komplikationsrate und hohen Folgekosten. Europa pflegte, mit lokalen Unterschieden, das Konzept der vorzugsweisen Verwendung von arteriovenösen Fisteln weiter (AVF). Der Prothesenanteil war nie höher als 40%. Unterstützt von Richtlinien, versuchen die USA seit 1997 einen deutlichen Umschwung herbeizuführen. Der Anteil primärer AVF ist seither angestiegen, bei allerdings wohl erhöhter initialer Versagerquote im internationalen Vergleich. Über Richtlinien hinaus sollte für beide Kontinente als vordringliche Aufgaben die interdisziplinäre Zusammenarbeit aller beteiligten Fachgebiete gelten: Durchführung zertifizierter, interdisziplinärer Kurse mit konsensfähigen Inhalten, Einrichtung von Referenzzentren mit einheitlicher, umfassender Dokumentation, Aufbau von Datenbanken zur Qualitätskontrolle mit abrufbaren Komplikations- und Funktionsraten, Standardisierung der Überwachung von Gefäßzugängen im Dialysezentru

May direct-to-consumer genetic testing have an impact on general practitioners' daily practice? a cross-sectional study of patients' intentions towards this approach.

Direct-to-consumer genetic testing (DTCGT) offers individuals access to information on their probable risks of suffering from a wide range of chronic diseases. General practitioners (GPs) will probably play a major role in supporting its use, but patients' perception of DTCGT remain unclear. This study aimed to describe those attitudes and expectations and how they might affect GPs' daily practices. In 2018-2019, a study related to the use of DTCGT for preventive care in general medicine was conducted among patients in Switzerland's French-speaking areas. Data were collected in the waiting room using a self-administrated questionnaire about patients' interest in DTCGT and what their attitudes might be if testing revealed an elevated risk of diabetes, colorectal cancer, or Alzheimer's disease. About 40% of the 929 participating (participation rate about 80%) patients had heard about DTCGT and, once the test had been explained, 43% reported that they would be interested in being tested. If that testing suggested an elevated risk of disease, the majority of patients reported that they would change their lifestyle (65%-81%, depending on the disease), request more examinations (63%-77%), and expect changes in their GP's follow-up (48%-59%). Personal characteristics such as sex, age, urbanity, marital status, and perceived health were factors predictive of patients' attitudes. Findings indicated that the generalization of DTCGT might affect GPs' daily practices in terms of workload and knowledge about this approach. However, this result must be qualified by the fact that it is based on hypothetical situations

The surface science of quasicrystals

The surfaces of quasicrystals have been extensively studied since about 1990. In this paper we review work on the structure and morphology of clean surfaces, and their electronic and phonon structure. We also describe progress in adsorption and epitaxy studies. The paper is illustrated throughout with examples from the literature. We offer some reflections on the wider impact of this body of work and anticipate areas for future development. (Some figures in this article are in colour only in the electronic version