Correlation tuned cross-over between thermal and nonthermal states following ultrafast transient pumping

We examine electron-electron mediated relaxation following excitation of a correlated system by an ultrafast electric field pump pulse. The results reveal a dichotomy in the temporal evolution as one tunes through a Mott metal-to-insulator transition: in the metallic regime relaxation can be characterized by evolution toward a steady-state electronic distribution well described by Fermi-Dirac statistics with an increased effective temperature; however, in the insulating regime this quasithermal paradigm breaks down with relaxation toward a nonthermal state with a more complicated electronic distribution that does not vary monotonically as a function of energy. We characterize the behavior by studying changes in the energy, photoemission response, and electronic distribution as functions of time. Qualitatively these results should be observable on short enough time scales that the electrons behave like an isolated system not in contact with additional degrees of freedom which can act as a thermal bath. Importantly, proper modeling used to analyze experimental findings should account for this behavior, especially when using strong driving fields or studying materials whose physics may manifest the effects of strong correlations.Comment: Main Text: 5 pages, 4 figures; Supplementary Material: 3 pages, 5 figure

Reducing the Probability of False Positive Research Findings by Pre-Publication Validation - Experience with a Large Multiple Sclerosis Database

*Objective*
We have assessed the utility of a pre-publication validation policy in reducing the probability of publishing false positive research findings. 
*Study design and setting*
The large database of the Sylvia Lawry Centre for Multiple Sclerosis Research was split in two parts: one for hypothesis generation and a validation part for confirmation of selected results. We present case studies from 5 finalized projects that have used the validation policy and results from a simulation study.
*Results*
In one project, the "relapse and disability" project as described in section II (example 3), findings could not be confirmed in the validation part of the database. The simulation study showed that the percentage of false positive findings can exceed 20% depending on variable selection. 
*Conclusion*
We conclude that the validation policy has prevented the publication of at least one research finding that could not be validated in an independent data set (and probably would have been a "true" false-positive finding) over the past three years, and has led to improved data analysis, statistical programming, and selection of hypotheses. The advantages outweigh the lost statistical power inherent in the process

Examining electron-boson coupling using time-resolved spectroscopy

Nonequilibrium pump-probe time domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for "slow" versus "fast" recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.Comment: 23 pages, 4 figures + Supplementary Material and movies, to appear in PR

Kardiovaskuläre Manifestationen bei Rheumatoider Arthritis

Zusammenfassung : Die Rheumatoide Arthritis (RA) ist eine systemische Erkrankung des Bindegewebes, die durch eine polyartikuläre Entzündung mit synovialer Hyperplasie und progredienter Gelenkzerstörung, aber auch durch extraartikuläre Manifestationen und systemische pathologische Immunphänomene charakterisiert ist. Eine erhöhte Mortalität innerhalb der RA-Patientenpopulation ist seit langem bekannt und vor allem auf ein erhöhtes kardiovaskuläres Risiko zurückzuführen. Die Korrelation der kardiovaskulären Morbidität und Mortalität mit der Erkrankungsaktivität sowie dem Ausmaß extraartikulärer Manifestationen war der Ausgangspunkt für die Suche nach entzündungs- und erkrankungsassoziierten Pathomechanismen. Endothelzelldysfunktion und vaskuläre Inflammation konnten als zentrale Mechanismen der Atheroskleroseinduktion und deren Progression charakterisiert werden. Beide Phänomene stellen eine uniforme Reaktionsweise von Gefäßen unter dem Einfluss klassischer Risikofaktoren sowie einer systemischen-Entzündung dar. Für die akzelerierte Atherosklerose von RA-Patienten sind neben den klassischen Risikofaktoren erkrankungsbedingte Faktoren wie Immobilität, medikamentöse Therapie sowie Entzündungsmediatoren zu berücksichtigen. Bei den beschriebenen entzündungsvermittelten Mechanismen der Gefäßschädigung kommt vor allem den bei RA-Patienten als Folge der Synovialitis exzessiv gebildeten pro-inflammatorischen Zytokinen eine Bedeutung zu. Die Frage, ob der Entzündungsmarker CRP gleichzeitig einen kardiovaskulären Risikoindikator und einen Mediator atherosklerotischer Gefäßschädigung darstellt, bedarf noch endgültiger Beantwortung durch weitere Studien. Neben diesen unspezifischen entzündungsassoziierten Mechanismen können bei der Rheumatoiden Arthritis zusätzlich krankheitsspezifische Immunphänomene, wie die klonal expandierten autoreaktiven T-Zellen für die kardiovaskuläre Morbidität und Mortalität von Bedeutung sein. Die neueren TNFα-hemmenden Basistherapeutika interferieren auf unterschiedlichen Ebenen mit pro-atherosklerotischen Prozessen. Die Zukunft wird zeigen, wie sich diese Medikamente auf die kardiovaskuläre Morbidität und Mortalität auswirke

Measurements of the reverse current of highly irradiated silicon sensors to determine the effective energy and current related damage rate

The reverse current of irradiated silicon sensors leads to self heating of the sensor and degrades the signal to noise ratio of a detector. Precise knowledge of the expected reverse current during detector operation is crucial for planning and running experiments in High Energy Physics. The dependence of the reverse current on sensor temperature and irradiation fluence is parametrized by the effective energy and the current related damage rate, respectively. In this study 18 n-in-p mini silicon strip sensors from companies Hamamatsu Photonics and Micron Semiconductor Ltd. were deployed. Measurements of the reverse current for different bias voltages were performed at temperatures of −32 ° C, −27 ° C and −23 ° C. The sensors were irradiated with reactor neutrons in Ljubljana to fluences ranging from 2×1014neq∕cm2 to 2×1016neq∕cm2 . The measurements were performed directly after irradiation and after 10 and 30 days of room temperature annealing. The aim of the study presented in this paper is to investigate the reverse current of silicon sensors for high fluences of up to 2×1016neq∕cm2 and compare the measurements to the parametrization models

Hydrography in the Mediterranean Sea during a cruise with RV Poseidon in April 2014

We report on data from an oceanographic cruise in the Mediterranean Sea on the German research vessel Poseidon in April 2014. Data were taken on a west–east section, starting at the Strait of Gibraltar and ending south-east of Crete, as well on sections in the Ionian and Adriatic Sea. The objectives of the cruise were threefold: to contribute to the investigation of the spatial evolution of the Levantine Intermediate Water (LIW) properties and of the deep water masses in the eastern Mediterranean Sea, and to investigate the mesoscale variability of the upper water column. The measurements include salinity, temperature, oxygen and currents and were conducted with a conductivity, temperature and depth(CTD)/rosette system, an underway CTD and an acoustic Doppler current profiler (ADCP). The sections are on tracks which have been sampled during several other cruises, thus supporting the opportunity to investigate the long-term temporal development of the different variables. The use of an underway CTD made it possible to conduct measurements of temperature and salinity with a high horizontal spacing of 6 nm between stations and a vertical spacing of 1 dbar for the upper 800 m of the water column

On the behavior of micro-spheres in a hydrogen pellet target

A pellet target produces micro-spheres of different materials, which are used as an internal target for nuclear and particle physics studies. We will describe the pellet hydrogen behavior by means of fluid dynamics and thermodynamics. In particular one aim is to theoretically understand the cooling effect in order to find an effective method to optimize the working conditions of a pellet target. During the droplet formation the evaporative cooling is best described by a multi-droplet diffusion-controlled model, while in vacuum, the evaporation follows the (revised) Hertz-Knudsen formula. Experimental observations compared with calculations clearly indicated the presence of supercooling, the effect of which is discussed as well.Comment: 22 pages, 8 figures (of which two are significantly compressed for easier download

Maximal length of trapped one-dimensional Bose-Einstein condensates

I discuss a Bogoliubov inequality for obtaining a rigorous bound on the maximal axial extension of inhomogeneous one-dimensional Bose-Einstein condensates. An explicit upper limit for the aspect ratio of a strongly elongated, harmonically trapped Thomas-Fermi condensate is derived.Comment: 6 pages; contributed paper for Quantum Fluids and Solids, Trento 2004, to appear in JLT