Probing many-body dynamics in a two-dimensional dipolar spin ensemble.

The most direct approach for characterizing the quantum dynamics of a strongly interacting system is to measure the time evolution of its full many-body state. Despite the conceptual simplicity of this approach, it quickly becomes intractable as the system size grows. An alternate approach is to think of the many-body dynamics as generating noise, which can be measured by the decoherence of a probe qubit. Here we investigate what the decoherence dynamics of such a probe tells us about the many-body system. In particular, we utilize optically addressable probe spins to experimentally characterize both static and dynamical properties of strongly interacting magnetic dipoles. Our experimental platform consists of two types of spin defects in nitrogen delta-doped diamond: nitrogen-vacancy colour centres, which we use as probe spins, and a many-body ensemble of substitutional nitrogen impurities. We demonstrate that the many-body system's dimensionality, dynamics and disorder are naturally encoded in the probe spins' decoherence profile. Furthermore, we obtain direct control over the spectral properties of the many-body system, with potential applications in quantum sensing and simulation.

Studying bicyclists' perceived level of safety using a bicycle simulator combined with immersive virtual reality.

There is a need for methods that provide a better understanding of bicyclists' perceived safety and preferences on currently unavailable and/or unknown bicycle facilities. Different survey methods have been used to study bicyclists' behavior, experiences, and preferences; ranging from verbally described facilities to surveys including images and videos. Virtual Reality (VR) experiments blur the boundaries between stated preference (SP) surveys and revealed preference (RP) surveys and provide a realistic sense of design. This research introduces a novel research method in bicycling research and discusses the results of an experiment using a bicycle simulator combined with immersive VR. In total, 150 participants participated in this experiment and were asked about demographics and perceptions and preferences after bicycling in five different environments with an instrumented bicycle in VR. A 5 × 2 mixed design was used with bicycling environment as within-subject factor and pedestrian / traffic volume as between-subject factor. ANOVA tests revealed how each environment and ambient pedestrian / traffic volume affected perceived level of safety (PLOS) and willingness to bicycle (WTB). Pairwise comparison showed that participants felt safer bicycling on the segregated bicycle path compared to bicycling on the painted bicycle path on the road and roadside. There was no meaningful difference between WTB for less than 10 min and WTB for more than 10 min between bicycling on a painted bicycle path on the sidewalk and painted bicycle path on the road. PLOS and WTB ratings of men and women were not significantly different from each other. The older segment of the sample was more worried about roadside bicycling and bicycle commuters were more confident to ride on the roadside. Despite having several limitations, immersive 360-degree VR was found a powerful presentation tool to evaluate future street designs which can inform transport and urban planning.

Trace detection of oxygen--ionic liquids in gas sensor design.

This paper presents a novel electrochemical membrane sensor on basis of ionic liquids for trace analysis of oxygen in gaseous atmospheres. The faradaic response currents for the reduction of oxygen which were obtained by multiple-potential-step-chronoamperometry could be used for real time detection of oxygen down to concentrations of 30 ppm. The theoretical limit of detection was 5 ppm. The simple, non-expensive sensors varied in electrolyte composition and demonstrated a high sensitivity, a rapid response time and an excellent reproducibility at room temperature. Some of them were continuously used for at least one week and first results promise good long term stability. Voltammetric, impedance and oxygen detection studies at temperatures up to 200 °C (in the presence and absence of humidity and CO2) revealed also the limitations of certain ionic liquids for some electrochemical high temperature applications. Application areas of the developed sensors are control and analysis processes of non oxidative and oxygen free atmospheres.

Accurate atom counting in mesoscopic ensembles.

Many cold atom experiments rely on precise atom number detection, especially in the context of quantum-enhanced metrology where effects at the single particle level are important. Here, we investigate the limits of atom number counting via resonant fluorescence detection for mesoscopic samples of trapped atoms. We characterize the precision of these fluorescence measurements beginning from the single-atom level up to more than one thousand. By investigating the primary noise sources, we obtain single-atom resolution for atom numbers as high as 1200. This capability is an essential prerequisite for future experiments with highly entangled states of mesoscopic atomic ensembles.

Detection of chromosomal imbalances in leiomyosarcoma by comparative genomic hybridization and interphase cytogenetics.

Leiomyosarcomas comprise a group of malignant soft-tissue tumors with smooth-muscle differentiation. In this study, 14 cases of leiomyosarcoma were screened for changes in relative chromosome copy number by comparative genomic hybridization. A high number of imbalances (mean, 16.3; range, 6-26) was detected, with chromosomal gains occurring about twice as much as losses. The most frequent gains were found in 5p15, 8q24, 15q25-->q26, 17p, and Xp (43% to 50%), whereas the most frequent losses were found in 10q and 13q (50% and 78%, respectively). Twenty high-level amplifications affecting 15 different chromosomal subregions were detected in nine different tumors. In three leiomyosarcomas, sequences on chromosome arm 17p were found to be highly amplified, with a minimal overlapping region on subbands 17p12-->p11. We further discovered that the Smith-Magenis syndrome critical region on 17p11.2 is included in the 17p amplicons of two leiomyosarcoma cases. Using probes flanking this genetically unstable region, a mean of 14 and 22 signals per nucleus, respectively, was detected in both leiomyosarcomas by fluorescence in situ hybridization. In conclusion, this analysis identifies a number of characteristic chromosomal imbalances in leiomyosarcomas and provides evidence for the localization of potential oncogenes and tumor suppressor genes active in leiomyosarcoma genomes.

Telemetry as a new concept in long term monitoring of SIDS-risk infant.

Sudden Infant Death Syndrome (SIDS) is the most frequent cause of infant death within the period of 2 to 12 months in western countries. It has been found that a suit similar to that worn by the astronauts during the execution of experiments on the Spacelab Mission D-2 is a very simple and useful means to carry the sensors required to monitor vital signs of babies at risk. A small baby-suit has been developed with the same technology used for the Spacelab Mission. The baby s suit is equipped with similar sensors to record thoracic and abdominal respiratory movements as its big -space travel brother-. This is a typical example of a successful technology transfer from medical aerospace activities into fields of daily clinical routine. In addition to the above described sensors, ECG-electrodes were integrated, as well as sensors to record vascular oxygen saturation and the corresponding pulse curve, and the baby s movements. All these vital signs are registered by a medical monitor, and permanently stored and automatically analysed online. In case of a life-threatening situation the system alerts simultaneously the personal at hospital and the parents at home. The requisite software algorithms have been developed by DLR in Cooperation with the pediatricians of the Pediatric Hospital in Köln-Porz, Cologne. When the system registers an alteration of the parameters above described -as a signal of a change in the baby s health condition- all vital signs are transfered in real-time to the supervising hospital via radio data transmission devices, mobile phone or a fixed network phone. The parents are also alerted by the device, and they can carry out the necessary reanimation procedures in case of an emergency. Parents will be trained in such actions when newborns must to be monitored. But nevertheless, they are guided and tele-assisted by an expert via telephone during the action. A clinical field trial, that will start in December 1999 at the Pediatric Hospital in Köln-Porz, Cologne, will evaluate the benefits of teleprotection by home monitoring of SIDS risk-babies.

Analysis of chromosomal imbalances in sporadic and NF1-associated peripheral nerve sheath tumors by comparative genomic hybridization.

Peripheral nerve sheath tumors arise either sporadically or in association with neurofibromatosis type 1 (von Recklinghausen's neurofibromatosis, NF1) or type 2. In this study, comprehensive screening for relative chromosome copy number changes was performed on 10 benign and 19 malignant peripheral nerve sheath tumors (MPNSTs) by applying comparative genomic hybridization (CGH). In benign tumors, no chromosomal imbalances were found by CGH, whereas in MPNSTs chromosomal gains and losses were frequently detected. No differences regarding the frequency and distribution of chromosomal imbalances were observed between the 13 sporadic and 6 NF1-associated MPNSTs analyzed. In both, the number of gains was significantly higher than the number of losses, suggesting a predominant role of proto-oncogene activation during MPNST progression. Candidate regions with potentially relevant proto-oncogenes included chromosomal bands 17q24-q25, 7p11-p13, 5p15, 8q22-q24, and 12q21-q24; those with putative tumor suppressor genes were 9p21-p24, 13q14-q22, and 1p. High-level amplifications were restricted to sporadic tumors and affected eight different chromosomal subregions. In three of these MPNSTs, identical subregions on chromosomal arms 5p and 12q were coamplified. This study revealed a number of new characteristic chromosomal imbalances and provides a basis for molecular identification of oncogenes and tumor suppressor genes of pathogenetic relevance in both sporadic and NF1-associated MPNSTs. Genes Chromosomes Cancer 25:362-369, 1999.

[Analysis of chromosome copy number changes in leiomyosarcoma through molecular cytogenetic methods]. / Analyse numerischer Chromosomenveränderungen in Leiomyosarkomen durch molekular-zytogenetische Methoden.

Leiomyosarcoma (LMS) is a rare type of malignant soft tissue tumor occurring predominantly in adults. Up to now only few zytogenetic data resulting from chromosomal banding analyses were obtained from this tumor type. In general, highly complex karyotypes were observed, but no recurrent chromosomal aberrations could be identified. The aim of the present study was to analyze chromosomal imbalances in 14 cases of LMS using comparative genomic hybridization (CGH). Imbalances were detected in all cases analyzed, with chromosomal gains occurring more frequently than losses (9.9 gains/case vs. 6.9 losses/case, respectively). Chromosome arms predominantly overrepresented included Xp (9/14 cases), 5p and 8q (8/14 each), as well as 17p and 17q (6/14 each). Nineteen distinct high level amplifications, indicative for the location of relevant proto-oncogenes in LMS, were identified in nine different tumors. Interestingly, in three cases chromosomal arm 17p was involved. Interphase analysis with probes derived from the commonly amplified region 17p11-p12 revealed, that the tre oncogene is co-amplified and therefore could play a relevant role in LMS development. With regard to losses chromosome 13q was affected in 12/14, 10q in 8/14, and 2p as well as 2q in 7/14 tumors, respectively. The frequent deletions of chromosome 13 with a minimal affected region 13q14-q15 strongly support preliminary molecular evidence, that loss of the RB1 tumor suppressor gene is a critical step in LMS tumorigenesis.

Primary mediastinal (thymic) B-cell lymphoma is characterized by gains of chromosomal material including 9p and amplification of the REL gene.

Primary mediastinal (thymic) B-cell lymphoma is a high-grade non-Hodgkin's lymphoma with unique features. By using comparative genomic hybridization and interphase cytogenetics, 26 tumors were analyzed to identify genomic imbalances. Gains of chromosomal material were much more frequent than losses (110 v 10) and involved chromosomes 9p, 12q, and Xq (31% to 50%). Interestingly, gain of Xq coincided with gain of 9p. Distinct high-level amplifications were found in four subregions. In 2 cases, amplifications of proto-oncogene REL were shown by filter hybridization, indicating a possible pathogenic role of this gene. The characteristic pattern of chromosomal imbalances distinct from other B-cell lymphomas suggests a specific pathway of genetic changes associated with this lymphoma.

[The venae cavae and their major inflow. Anastomotic valve relations and endothelial abnormalities]. / Die Vv. cavae und ihre grossen Zuflüsse. Mündungsnahe Klappenverhältnisse und Endothelverwerfungen.

The site and condition of the valves at the junctions of the venae cavae and their tributaries were determined, abnormal endothelial structures identified and the vessel calibre measured in sections through the superior venae cavae of 122 and of the inferior venae cavae of 107 adults. A scale diagram of the venae cavae shows variations of the valve position and occurrence of abnormal endothelial structures in the brachiocephalic veins and the inferior vena cava. These structures might present a hazard for central venous catheterization and introduction of a vena cava filter.

Destabilization of egg lecithin liposomes on the skin after topical application measured by perturbed gamma gamma angular correlation spectroscopy (PAC) with 111In.

Unilamellar and oligolamellar liposomes were topically applied to the skin of porcine ears. Perturbed angular correlation spectroscopy of 111In-DTPA, initially entrapped into the liposomes, was used to study the release kinetics of the hydrophilic probe. After drying of the liposomal suspensions, a decrease of the time-integrated perturbation factor within 30 min indicated destabilization of the liposomes and total marker release in the upper epidermal layers.

Increased tumor necrosis factor alpha (TNF alpha), interleukin 1, and interleukin 6 (IL-6) levels in the plasma of stored platelet concentrates: relationship between TNF alpha and IL-6 levels and febrile transfusion reactions.

Increased interleukin 6 (IL-6) levels were found in 8 of 12 platelet concentrates (PCs) after 3 days of storage and in 10 of 12 PCs after 5 and 7 days of storage. Most of the PCs with an increased IL-6 level also showed increased tumor necrosis factor alpha (TNF alpha) and interleukin 1 beta (IL-1 beta) levels. Levels of IL-6 increased by 3 log10 over the base level during storage. Increased levels were found when the PC white cell count exceeded 3 x 10(9) per L. A linear correlation was found among the levels of TNF alpha, IL-1 beta, IL-1 alpha, and IL-6 in the PCs (r > 0.885). Comparison of the TNF alpha, IL-1 beta, and IL-6 levels in samples taken at various storage times indicates that the increased levels are the result of an active synthesis and release of interleukins during storage. In a second part of the study, 45 transfusions of white cell-reduced PCs were studied. Six transfusions were complicated by a febrile reaction. These reactions were related to high levels of IL-6 and TNF alpha in the PCs (p < 0.0001). These cytokines are known as endogenous pyrogens. These findings indicate that transfusion reactions might be due to the intravenous administration of plasma with high cytokine levels and might not always result from an antigen-antibody reaction.

[Protection of gonads in radiography of the pelvis (author's transl)]. / Gonadenschutz bei Beckenaufnahmen

The effectiveness of a new device for the protection of gonads has been tested by measuring doses on the water-phantom and on patients. The lead protector is applied below the light-soorce and protects the gonads in pelvic radiography. The reduction of dosage corresponds to the usual lead-protectors. It should be particularly useful in Orthopedics, since it is simple and hygienic.