Multiple-scattering effects on incoherent neutron scattering in glasses and viscous liquids

Incoherent neutron scattering experiments are simulated for simple dynamic models: a glass (with a smooth distribution of harmonic vibrations) and a viscous liquid (described by schematic mode-coupling equations). In most situations multiple scattering has little influence upon spectral distributions, but it completely distorts the wavenumber-dependent amplitudes. This explains an anomaly observed in recent experiments

WEXTOR: A Web-based tool for generating and visualizing experimental designs and procedures

WEXTOR is a Javascript-based experiment generator and teaching tool on the World-Wide Web that can be used to design laboratory and Web experiments in a guided step-by-step process. It dynamically creates the customized Web pages and Javascripts needed for the experimental procedure and provides experimenters with a print-ready visual display of their experimental design. WEXTOR flexibly supports complete and incomplete factorial designs with between-subjects, within-subjects, and quasiexperimental factors, as well as mixed designs. The software implements client-side response time measurement and contains a content wizard for creating interactive materials, as well as dependent measures (graphical scales, multiple-choice items, etc.), on the experiment pages. However, it does not aim to replace a full-fledged HTML editor. Several methodological features specifically needed in Web experimental design have been implemented in the Web-based tool and are described in this paper. WEXTOR is platform independent. The created Web pages can be uploaded to any type of Web server in which data may be recorded in logfiles or via a database. The current version of WEXTOR is freely available for educational and noncommercial purposes. Its Web address is http://www.genpsylab.unizh.ch/wextor/index.html

A Sparse Stress Model

Force-directed layout methods constitute the most common approach to draw general graphs. Among them, stress minimization produces layouts of comparatively high quality but also imposes comparatively high computational demands. We propose a speed-up method based on the aggregation of terms in the objective function. It is akin to aggregate repulsion from far-away nodes during spring embedding but transfers the idea from the layout space into a preprocessing phase. An initial experimental study informs a method to select representatives, and subsequent more extensive experiments indicate that our method yields better approximations of minimum-stress layouts in less time than related methods.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

Predictors of state-of-the-art management of early breast cancer in Switzerland

Background: The aim of this study was to investigate predictors of state-of-the-art management of early breast cancer in Switzerland. Patients and methods: The study included 3499 women aged 25-79 years diagnosed with invasive breast cancer stages I-IIIA in 2003-2005. Patients were identified through population-based cancer registries and treated in all kinds of settings. Concordance with national and international recommendations was assessed for 10 items covering surgery, radiotherapy, systemic adjuvant therapy and histopathology reporting. We used multivariate logistic regression to identify independent predictors of high (10 points) and low (≤7 points) concordance. Results: In one-third of the patients, management met guidelines in all items, whereas in about one-fifth, three or more items did not comply. Treatment by a surgeon with caseload in the upper tercile and team involved in clinical research were independent predictors of a high score, whereas treatment by a surgeon with a caseload in the lower tercile was associated with a low score. Socioeconomic characteristics such as income and education were not independent predictors, but patient's place of residence and age independently predicted management according to recommendations. Conclusion: Specialization and involvement in clinical research seem to be key elements for enhancing the quality of early breast cancer management at population leve

Der deutsche Sydney Swallow Questionnaire

Hintergrund Der Sydney Swallow Questionnaire (SSQ) ist ein patientenbasierter Fragebogen zur Erhebung von subjektiven Beschwerden oropharyngealer Schluckstörungen unterschiedlicher Ursachen, mit starker inhalts-, konstrukt-, diskriminativer und prädiktiver Validität. Ziel der Arbeit/Fragestellung Ziel dieser Arbeit war die Überprüfung der Reliabilität und Validität der deutschen Fassung des Sydney Swallow Questionnaire (SSQ-G). Material und Methode In einer Kreuzvalidierungsstudie füllten 48 erwachsene deutschsprachige Patienten (12 Frauen/36 Männer) mit neurogen (n = 16), strukturell (n = 16) und funktionell (n = 16) bedingten Schluckstörungen den deutschen SSQ‑G und MD Anderson Dysphagia Inventory (MDADI) aus. Die Reliabilität des SSQ‑G wurde anhand der internen Konsistenz mittels Cronbach‑α berechnet. Die Überprüfung der Kriterien- und der Konstruktvalidität erfolgte durch eine Kreuzvalidierung mittels Spearman-Korrelationskoeffizient. Ergebnisse Die interne Konsistenz des SSQ‑G war mit Cronbach-α = 0,94 exzellent. Die SSQ-G-Fragen 1 und 17 wiesen mit MDADI-Frage 1 einen moderat signifikanten bzw. hochsignifikanten Korrelationskoeffizienten von −0,43 und −0,45 auf (p < 0,5; p < 0,001). Zwischen Fragen 8, 11 und 12 des SSQ‑G und Fragen 7, 13 und 10 des MDADI lag mit Korrelationen von −0,48 bis −0,55 ein mittlerer bis starker hochsignifikanter Zusammenhang vor (p < 0,001). Somit wurden die Reliabilität, die Kriteriums- und Konstruktvalidität statistisch bestätigt. Schlussfolgerung Mit der deutschen Version des SSQ (SSQ-G) können funktionsspezifische Schluckbeschwerden reliabel und valide erfasst werden. In Kombination mit Fragenbögen zur symptomspezifischen Lebensqualität wie dem MDADI ist somit eine differenziertere klinische Analyse von Schluckbeschwerden möglich

Dynamics of DNA replication loops reveal temporal control of lagging-strand synthesis

In all organisms, the protein machinery responsible for the replication of DNA, the replisome, is faced with a directionality problem. The antiparallel nature of duplex DNA permits the leading-strand polymerase to advance in a continuous fashion, but forces the lagging-strand polymerase to synthesize in the opposite direction. By extending RNA primers, the lagging-strand polymerase restarts at short intervals and produces Okazaki fragments. At least in prokaryotic systems, this directionality problem is solved by the formation of a loop in the lagging strand of the replication fork to reorient the lagging-strand DNA polymerase so that it advances in parallel with the leading-strand polymerase. The replication loop grows and shrinks during each cycle of Okazaki fragment synthesis. Here we use single-molecule techniques to visualize, in real time, the formation and release of replication loops by individual replisomes of bacteriophage T7 supporting coordinated DNA replication. Analysis of the distributions of loop sizes and lag times between loops reveals that initiation of primer synthesis and the completion of an Okazaki fragment each serve as a trigger for loop release. The presence of two triggers may represent a fail-safe mechanism ensuring the timely reset of the replisome after the synthesis of every Okazaki fragment.

Disentangling the respective contribution of task selection and task execution in self-directed cognitive control development

peer reviewedTask selection and task execution are key constructs in cognitive control development. Yet, little is known about how separable they are and how each contributes to task switching performance. Here, 60 4- to 5-year olds, 60 7- to 8-year olds, and 60 10- to 11-year olds children completed the double registration procedure, which dissociates these two processes. Task selection yielded both mixing and switch costs, especially in younger children, and task execution mostly yielded switch costs at all ages, suggesting that task selection is costlier than task execution. Moreover, both task selection and execution varied with task self-directedness (i.e., to what extent the task is driven by external aids) demands. Whereas task selection and task execution are dissociated regarding performance costs, they nevertheless both contribute to self-directed control

Energy landscape - a key concept for the dynamics of glasses and liquids

There is a growing belief that the mode coupling theory is the proper microscopic theory for the dynamics of the undercooled liquid above a critical temperature T_c. In addition, there is some evidence that the system leaves the saddlepoints of the energy landscape to settle in the valleys at this critical temperature. Finally, there is a microscopic theory for the entropy at the calorimetric glass transition T_g by Mezard and Parisi, which allows to calculate the Kauzmann temperature from the atomic pair potentials. The dynamics of the frozen glass phase is at present limited to phenomenological models. In the spirit of the energy landscape concept, one considers an ensemble of independent asymmetric double-well potentials with a wide distribution of barrier heights and asymmetries (ADWP or Gilroy-Phillips model). The model gives an excellent description of the relaxation of glasses up to about T_g/4. Above this temperature, the interaction between different relaxation centers begins to play a role. One can show that the interaction reduces the number of relaxation centers needed to bring the shear modulus down to zero by a factor of three.Comment: Contribution to the III Workshop on Nonequilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials, 22-27 September 2002, Pisa; 14 pages, 3 figures; Version 3 takes criticque at Pisa into account; final version 4 will be published in J.Phys.: Condens.Matte