Atom Interferometry with up to 24-Photon-Momentum-Transfer Beam Splitters

We present up to 24-photon Bragg diffraction as a beam splitter in light-pulse atom interferometers to achieve the largest splitting in momentum space so far. Relative to the 2-photon processes used in the most sensitive present interferometers, these large momentum transfer beam splitters increase the phase shift 12-fold for Mach-Zehnder (MZ-) and 144-fold for Ramsey-Borde (RB-) geometries. We achieve a high visibility of the interference fringes (up to 52% for MZ or 36% for RB) and long pulse separation times that are possible only in atomic fountain setups. As the atom's internal state is not changed, important systematic effects can cancel.Comment: New introduction. 4 pages, 4 figure

6 W, 1 kHz linewidth, tunable continuous-wave near-infrared laser

A modified Coherent 899-21 titanium sapphire laser is injection locked to produce 6-6.5 W of single-frequency light at 852 nm. After closed-loop amplitude control and frequency stabilization to a high-finesse cavity, it delivers 4-4.5 W with <1 kHz linewidth at the output of a single-mode fiber. The laser is tunable from about 700-1000 nm; up to 8 W should be possible at 750-810 nm.Comment: Published version with details and references added. 3 page

Noise-Immune Conjugate Large-Area Atom Interferometers

We present a pair of simultaneous conjugate Ramsey-Borde atom interferometers (SCI) using large (20\hbar k)-momentum transfer (LMT) beam splitters, where \hbar k is the photon momentum. Simultaneous operation allows for common-mode rejection of vibrational noise. This allows us to surpass the enclosed space-time area of previous interferometers with a splitting of 20\hbar k by a factor of 2,500. Among applications, we demonstrate a 3.4 ppb resolution in the fine structure constant and discuss tests of fundamental laws of physics.Comment: 4 pages revtex, 5 figure

Stresstest städtischer Infrastrukturen – Ein Experiment zur Wahrnehmung des Alters im öffentlichen Raum

Im Zuge des demographischen Wandels ist ein deutlicher Anstieg des Bevölkerungsanteils an Seniorinnen und Senioren (Personen ab 65 Jahren) in Deutschland abzusehen. Dadurch wächst auch die Anzahl der mobilitätseingeschränkten und behinderten Menschen. Insbesondere für die Gruppe der über 80-Jährigen spielen barrierearme Wege eine große Rolle, sie stellen dementsprechend eine zunehmend wichtiger werdende Herausforderung für die räumliche Planung dar. In einer Pilotstudie wurde hierfür im Bochumer Stadtteil Querenburg versucht, Barrieren (nach DIN 18040-3 etc.) in einem „barrierefreien Stadtplan“ zu erfassen. Es stellt sich jedoch die Frage, ob es tatsächlich diese Barrieren sind, die den mobilitätseingeschränkten Verkehrsteilnehmerinnen und -teilnehmern Stress verursachen. Um diese Problematik zu klären, wurde die Technik des „EmoMapping“ (dt. Emotionskartierung) verwendet. Dieses Verfahren dient dazu, Emotionen von einzelnen Personen mit einer Georeferenz zu erfassen. Zu diesem Zweck wurden Testpersonen mit einem Alterssimulationsanzug, einem GPS-Logger zur Erfassung der geographischen Position sowie einem Sensorband, welches die Hautleitfähigkeit und die Hauttemperatur misst, ausgestattet. In Testläufen wurden durch Erkennung von Mustern besondere Situationen, in denen die Probanden Stress verspürten, positionsgenau erfasst. Anschließend wurden die Messdaten des GPS-Loggers und des Sensorbands ausgewertet und kombiniert. Die daraus resultierenden Ergebnisse wurden als Dichtekarten (Heatmaps) in einem Geoinformationssystem dargestellt. Aus diesen wurde ersichtlich, an welchen Stellen im Straßennetz die Probanden Stress empfunden haben. Im Anschluss daran wurden die Daten des barrierefreien Stadtplans mit den Ergebnissen des EmoMappings validiert und die einzelnen Barrierearten hinsichtlich ihrer Relevanz für eine barriere- und stressfreie Navigation eingeschätzt. Da die Auswertung der Daten aus dem EmoMapping bislang nicht automatisiert und über verschiedene Software durchgeführt wurde, konnten die Daten nicht sehr zeitnah ausgewertet werden. Auch der Arbeitsaufwand war als relativ hoch einzustufen. Deshalb wurde im Rahmen einer Bachelorarbeit ein Werkzeug entwickelt, mit welchem sich die einzelnen Arbeitsschritte der Auswertung automatisiert durchführen lassen. Das Tool wurde in der frei verfügbaren Programmiersprache „R“ entwickelt und erleichtert den bisherigen Arbeitsablauf der Auswertung deutlich. Das lässt in Zukunft eine erhöhte Nutzung der EmoMapping-Methode zu

Design of a tourist driven bandwidth determined MultiModal mobile presentation system

In this paper we report on first experiences with a new software architecture for agent toolkits. Agent toolkits mainly consist of a software system that defines an agency, which is responsible to host software agents. Most architectures developed so far already define a large set of services, for example for agent migration, communication, and tracking. We propose to employ a kernel-based approach, where the kernel only provides fundamental concepts and functions common in all toolkits and abstracts from any of these services. We were able to show that in particular agent migration can be implemented as an optional service. We believe that this architecture is a useful foundation for research on agent-related topics as it allows research groups to implement their own results as a service which can be used by other groups running an agent system based on the same architecture

Light or Deep Pressure: Medical Staff Members Differ Extensively in Their Tactile Stimulation During Preterm Apnea

Background: Even though tactile stimulation is common practice to terminate preterm apnea, the style and intensity of these interventions is not specified during theoretical or practical training and has never been clinically evaluated. Objective: The present study was designed to analyze the various modes of tactile stimulation used to terminate preterm apnea and measure the pressure intensity and frequency of these stimulations. Methods: A model with the size and weight of an actual preterm infant was equipped with sensor technology to measure stimulation pressure and frequency of tactile stimulation. Additionally a camera system was used to record hand positions and stimulation modes. Seventy medical staff members took part in the experiment. Results: We found extreme between subjects differences in stimulation pressure that could not be explained by professional experience but, to a degree, depended on apnea intensity. Pressures ranged from 11.11 to 226.87 mbar during low intensity apnea and from 9.89 to 428.15 mbar during high intensity apnea. The majority of participants used rhythmic stimulation movements with a mean frequency of ∼1 Hz. Different modes (rubbing, squeezing, tickling, and tapping) and finger positions were used. Conclusion: Medical staff members intuitively adjust their tactile stimulation pressure depending on the premature infants’ apnea intensity. However, mean pressure values varied greatly between subjects, with similar pressure ranges for low and high intensity apnea. The question remains which pressure intensities are necessary or sufficient for the task. It is reasonable to assume that some stimulation types may be more effective in rapidly terminating an apneic event

Modelação da circulação induzida por ondas na zona de arrebentação /

Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.É apresenta uma metodologia para determinar as correntes induzidas por ondas curtas (i.e. geradas pelo vento) na zona de arrebentação através de modelagem numérica, considerando o caso mais simples que é o da circulação(permanente) induzida por ondas monocromáticas. A modelagem foi organizada em três módulos: i)Cálculo do campo de ondas utilizando um modelo de refração-difração baseado na Aproximação Parabólica da Equação do Declive Suave (Kirby,1986); ii)Cálculo do campo de forças induzido pelas ondas na massa d'água a partir dos gradientes de tensão de radiação (Longuet-Higgins, 1970a, b); iii)Cálculo das correntes (médias na coluna d'água e no período) e da elevação (média) da superfície resultantes da ação do campo de forças determinado no item (ii) através de um modelo de circulação 2D-H (Martins,1992). Para testar a metodologia e avaliar a qualidade dos resultados comparou-se os dados de um experimento de laboratório realizado no Laboratoire d'Hidraulique de France-LHF no qual ondas monocromáticas incidem perpendicularmente sobre um quebra-mar localizado numa praia plana e uniforme, e que contemplou medições detalhadas dos parâmetros de interesse. Os resultados obtidos pela presente metodologia reproduziram de forma satisfatória as medições de laboratório bem aqueles apresentados por outros modelos