Public exhibit for demonstrating the quantum of electrical conductance

We present a new robust setup that explains and demonstrates the quantum of electrical conductance for a general audience and which is continuously available in a public space. The setup allows users to manually thin a gold wire of several atoms in diameter while monitoring its conductance in real time. During the experiment, a characteristic step-like conductance decrease due to rearrangements of atoms in the cross-section of the wire is observed. Just before the wire breaks, a contact consisting of a single atom with a characteristic conductance close to the quantum of conductance can be maintained up to several seconds. The setup is operated full-time, needs practically no maintenance and is used on different educational levels

Stabilizing nuclear spins around semiconductor electrons via the interplay of optical coherent population trapping and dynamic nuclear polarization

We experimentally demonstrate how coherent population trapping (CPT) for donor-bound electron spins in GaAs results in autonomous feedback that prepares stabilized states for the spin polarization of nuclei around the electrons. CPT was realized by excitation with two lasers to a bound-exciton state. Transmission studies of the spectral CPT feature on an ensemble of electrons directly reveal the statistical distribution of prepared nuclear spin states. Tuning the laser driving from blue to red detuned drives a transition from one to two stable states. Our results have importance for ongoing research on schemes for dynamic nuclear spin polarization, the central spin problem and control of spin coherence.Comment: 5 pages, 4 figure

Partitioning of melt energy and meltwater fluxes in the ablation zone of the west Greenland ice sheet

We present four years (August 2003–August 2007) of surface mass balance data from the ablation zone of the west Greenland ice sheet along the 67° N latitude circle. Sonic height rangers and automatic weather stations continuously measured accumulation/ablation and near-surface climate at distances of 6, 38 and 88 km from the ice sheet margin at elevations of 490, 1020 and 1520 m a.s.l. Using a melt model and reasonable assumptions about snow density and percolation characteristics, these data are used to quantify the partitioning of energy and mass fluxes during melt episodes. The lowest site receives very little winter accumulation, and ice melting is nearly continuous in June, July and August. Due to the lack of snow accumulation, little refreezing occurs and virtually all melt energy is invested in runoff. Higher up the ice sheet, the ice sheet surface freezes up during the night, making summer melting intermittent. At the intermediate site, refreezing in snow consumes about 10% of the melt energy, increasing to 40% at the highest site. The sum of these effects is that total melt and runoff increase exponentially towards the ice sheet margin, each time doubling between the stations. At the two lower sites, we estimate that radiation penetration causes 20–30% of the ice melt to occur below the surface

Effect of Synovex, Synovex + FinaPlix, and Revalor on Daily Gain and Carcass Characteristics of Yearling Steers

The objective of this study was to determine if there were differences in daily gain and carcass traits of yearling steers implanted with Synovex-S (S), Synovex-S + Finaplix-S (S + F), or Revalor-S (R). Upon arrival at the feedlot, 264 steers (average weight 731 Ib) were allotted to 24 pens and adapted to a 90% concentrate diet over a period of 23 days. They were implanted on day 20 with either S, S+F, or R. No differences were found between S + F and R (P\u3e.10) at any time during the study. However, combination implants (S+F and R) both resulted in 10% greater weight gains (P\u3c .01) between days 57 and 84 of the study (37 and 64 days postimplanting) than S implanted steers. Some of this advantage was lost after day 11 3 (93 days postimplanting), as combination implant cattle gained almost 8% less per day than those implanted with S (P\u3c .01). During the portion of the study when all implants could be expected to be fully functional (days 9 through 93 postimplanting), combination implant treatments increased daily gain by 3.7% (P\u3c.05) over S. Steers were slaughtered at an average of 11 5 days postimplanting. No differences in carcass characteristics were found (P \u3e .20)

Manipulation of a single charge in a double quantum dot

We manipulate a single electron in a fully tunable double quantum dot using microwave excitation. Under resonant conditions, microwaves drive transitions between the (1,0) and (0,1) charge states of the double dot. Local quantum point contact charge detectors enable a direct measurement of the photon-induced change in occupancy of the charge states. From charge sensing measurements, we find T1~16 ns and a lower bound estimate for T2* of 400 ps for the charge two-level system.Comment: related articles at http://marcuslab.harvard.ed

Interference effects in isolated Josephson junction arrays with geometric symmetries

As the size of a Josephson junction is reduced, charging effects become important and the superconducting phase across the link turns into a periodic quantum variable. Isolated Josephson junction arrays are described in terms of such periodic quantum variables and thus exhibit pronounced quantum interference effects arising from paths with different winding numbers (Aharonov-Casher effects). These interference effects have strong implications for the excitation spectrum of the array which are relevant in applications of superconducting junction arrays for quantum computing. The interference effects are most pronounced in arrays composed of identical junctions and possessing geometric symmetries; they may be controlled by either external gate potentials or by adding/removing charge to/from the array. Here we consider a loop of N identical junctions encircling one half superconducting quantum of magnetic flux. In this system, the ground state is found to be non-degenerate if the total number of Cooper pairs on the array is divisible by N, and doubly degenerate otherwise (after the stray charges are compensated by the gate voltages).Comment: 9 pages, 6 figure

D.3.6 – Sediment dynamics and stability

The objective of the FAST project is to develop a Copernicus downstream service based on (Sentinel) satellite data and in situ data to assess the function of wetlands in reducing flood risk and erosion. This requires an assessment of the erodibility and stability of foreshores, as well as knowledge on how saltmarshes function and develop, in order to predict their future status, and hence their flood defence value over longer time-scales. While detailed results on sediment and marsh dynamics are presented in particularly Deliverable 5.2, this Deliverable 3.6 serves to lists publication output of the project related to the study of vertical and lateral sediment dynamics of foreshores and marsh range changes and their drivers. The potential for implementation of products and services related to sediment dynamics and stability in the Copernicus downstream service is discussed

Guías para la práctica de la autopsia en casos de muerte súbita cardíaca

A pesar de que la muerte súbita cardíaca es una de las formas más importantes de muerte en los países occidentales, este problema no ha recibido la atención que merece por parte de los patólogos y de los médicos de los sistemas públicos de salud. Se han desarrollado nuevos métodos de prevención de arritmias potencialmente mortales, y el diagnóstico de certeza de las causas de muerte súbita cardíaca es en este momento de particular importancia. Los patólogos son responsables de determinar la causa exacta de la muerte súbita pero existen diferencias considerables en el modo en el que se aborda esta cada vez más compleja tarea. La Asociación Europea de Patología Cardiovascular desarrolló unas guías que representan el estándar mínimo necesario en la práctica habitual de la autopsia para la valoración de la muerte súbita cardíaca, incluyendo no sólo un protocolo para el examen del corazón y el muestreo histopatológico, sino también para la investigación toxicológica y molecular. Nuestras recomendaciones son aplicables a centros médicos universitarios, a hospitales regionales y locales y a todo tipo de Institutos de Medicina Forense. La adopción a lo largo de la Unión Europea de un método uniforme de investigación supondrá la mejora de la práctica habitual, permitirá realizar comparaciones significativas entre distintas comunidades y regiones y, lo que es más importante aún, favorecerá que se monitoricen los patrones de las enfermedades que causan una muerte súbita. Although sudden cardiac death is one of the most important mode of death in Western Countries, pathologists and public health physicians have not given this problem the attention it deserves. New methods of preventing potentially fatal arrhythmias have been developed, and the accurate diagnosis of the causes of sudden cardiac death is now of particular importance. Pathologists are responsible for determining the precise cause of sudden death but there is considerable variation in the way in which they approach this increasingly complex task. The Association for European Cardiovascular Pathology developed guidelines, which represent the minimum standard that is required in the routine autopsy practice for the adequate assessment of sudden cardiac death, including not only a protocol for heart examination and histological sampling, but also for toxicology and molecular investigation. Our recommendations apply to university medical centres, regional and district hospitals and all types of forensic medicine institutes. If a uniform method of investigation is adopted throughout the European Union, this will lead to improvements in standards of practice, allow meaningful comparisons between different communities and regions and, most importantly, permit future trends in the patterns of disease causing sudden death to be monitored