Optical and evaporative cooling of cesium atoms in the gravito-optical surface trap

We report on cooling of an atomic cesium gas closely above an evanescent-wave atom mirror. At high densitities, optical cooling based on inelastic reflections is found to be limited by a density-dependent excess temperature and trap loss due to ultracold collisions involving repulsive molecular states. Nevertheless, very good starting conditions for subsequent evaporative cooling are obtained. Our first evaporation experiments show a temperature reduction from 10muK down to 300nK along with a gain in phase-space density of almost two orders of magnitude.Comment: 8 pages, 6 figures, submitted to Journal of Modern Optics, special issue "Fundamentals of Quantum Optics V", edited by F. Ehlotzk

Individual Differences in Children\u27s Eyewitness Memory Skills

The present study investigated the impact of individual differences on children\u27s eyewitness memory skills. Preschool (mean age of 4 years 8 months) and elementary (mean age of 11 years and 3 months) aged school children played a 5 minute game of Simon Says with an unknown male confederate. The children\u27s memories for the game and the man with whom they played the game were assessed on an objective questionnaire, free recall and photo recognition task. Both the free recall and the objective questionnaire were given immediately after the game and exactly one week later. Half of the subjects were exposed to misleading postevent information, immediately after the event. Several measures of individual differences were obtained from the children. The children\u27s ages, sex, and visual and verbal short term memories were directly assessed. Parents provided measures of the children\u27s anxiety, dependency, ego strength, intellectual functioning, attention, impulse control, reality contact, and social conformity using a standardized behavior rating scale. All of these variables were investigated to determine their impact on the various measures of eyewitness memory skills. Overall the older children performed significantly better than the younger children on the objective questionnaire, they were more expansive and accurate in their free recalls, they were less suggestible, and they were more accurate in identifying the man with whom they played the game from the photo lineup. Children with inferior short term memory skills demonstrated a deficit in their performance on the objective questionnaire and their ability to resist postevent information. In addition children with an inability to sustain attention were more suggestible. The results suggest that age is not the only factor which the courts should use to determine the reliability of children\u27s eyewitness testimonies. The impact of short term memory skills, time delays, and attention could provide the courts with additional valuable information

Evanescent-wave trapping and evaporative cooling of an atomic gas near two-dimensionality

A dense gas of cesium atoms at the crossover to two-dimensionality is prepared in a highly anisotropic surface trap that is realized with two evanescent light waves. Temperatures as low as 100nK are reached with 20.000 atoms at a phase-space density close to 0.1. The lowest quantum state in the tightly confined direction is populated by more than 60%. The system offers intriguing prospects for future experiments on degenerate quantum gases in two dimensions

Cold atom gas at very high densities in an optical surface microtrap

An optical microtrap is realized on a dielectric surface by crossing a tightly focused laser beam with an horizontal evanescent-wave atom mirror. The nondissipative trap is loaded with $\sim$$10^5$ cesium atoms through elastic collisions from a cold reservoir provided by a large-volume optical surface trap. With an observed 300-fold local increase of the atomic number density approaching $10^{14}{\rm cm}^{-3}$, unprecedented conditions of cold atoms close to a surface are realized

Semi-parametric geolocation estimation in NLOS environments

The position of a stationary target can be determined using triangulation in combination with time of arrival measurements at several sensors. In urban environments, none-line-of-sight (NLOS) propagation leads to biased time estimation and thus to inaccurate position estimates. Here, a semi-parametric approach is proposed to mitigate the effects of NLOS propagation. The degree of contamination by NLOS components in the observations, which result in asymmetric noise statistics, is determined and incorporated into the estimator. The proposed method is adequate for environments where the NLOS error plays a dominant role and outperforms previous approaches that assume a symmetric noise statistic

Preparation of Some lmino- and Cyano-imino-substituted Barbiturates

A number of imino- and cyano-iminobarbituric acid derivatives has been prepared in good yield by gradually adding sodium methoxide - as condensation catalyst - to some substituted cyanoacetic and malonic esters reacting with urea, dicyandiamide and guanidine

First record of a plasmodiophorid parasite in grapevine

In the context of an interdisciplinary project on grape pests and pathogens in Rheingau (Germany), the fine root system of grafted rootstocks has been screened for pathogenic fungi associated with root galls induced by grape phylloxera (Daktulosphaira vitifoliae (Fitch)). In several insect-induced galls, masses of resting spores of a plasmodiophorid could be seen. An additional selective screening revealed the occurrence of the plasmodiophorid parasite also in samples of gall-free rootlets: cortical cells of small necrotic areas were crowded with resting spores or other developmental stages of its life cycle. According to current taxonomic concepts, this plasmodiophorid could be identified as a member of the genus Sorosphaera Schroeter, resembling S. veronicae Schroeter. This is the first record of a plasmodiophorid parasite in grapevine