Single-site-resolved measurement of the current statistics in optical lattices

At present, great effort is spent on the experimental realization of gauge fields for quantum many-body systems in optical lattices. At the same time, the single-site-resolved detection of individual atoms has become a new powerful experimental tool. We discuss a protocol for the single-site resolved measurement of the current statistics of quantum many-body systems, which makes use of a bichromatic optical superlattice and single-site detection. We illustrate the protocol by a numerical study of the current statistics for interacting bosons in one and two dimensions and discuss the role of the on-site interactions for the current pattern and the ground-state symmetry for small two-dimensional lattices with artificial magnetic fields.Comment: 5+2 pages, published versio

Seguridad, rescate en el mar y acceso legal

Para cumplir con sus propios valores, la UE debería reforzar las operaciones de búsqueda y salvamento en el Mediterráneo y establecer accesos legales a la protección en Europa con el fin de evitar la necesidad de emprender peligrosos viajes cruzándolo

Preoperative Imaging of Charcot Neuroarthropathy in Diabetic Patients: Comparison of Ring PET, Hybrid PET, and Magnetic Resonance Imaging

Introduction: The treatment of Charcot neuroarthropathy in the feet of diabetic patients has undergone fundamental changes in the last few years. Formerly, treatment was almost exclusively limited to nonoperative measures; since the late 1990s, however, current practice has shifted to early, stage-appropriate surgical therapy. The objective of this prospective study was to investigate the value of two types of positron emission tomography (PET) in the preoperative evaluation of diabetic patients with Charcot foot deformities. Materials and Methods: Ring 18FFDG (2-fluoro-2-deoxy-glucose) and hybrid PET were compared to magnetic resonance imaging (MRI). MRI, ring PET, and hybrid PET imaging were used as part of the preoperative evaluation of 16 patients with type II diabetes mellitus. The diagnosis of Charcot neuropathy of the foot requiring operative treatment had been made on the basis of clinical and radiographic criteria. Results: Of 39 Charcot lesions confirmed at surgery, 37 were detected by ring PET, 30 by hybrid PET, and 31 by MRI. Conclusions: PET (ring or hybrid) can be used in the evaluation of patients with metal implants that would compromise the accuracy of MRI. Another advantage of PET is its ability to distinguish between inflammatory and infectious soft-tissue lesions, and between osteomyelitis and Charcot neuroarthropathy. The differentiation between Charcot neuroarthropathy and florid osteomyelitis provides the surgeon with important additional information that often is unavailable from MRI. Because it provides important additional data, ring PET may be preferable to radiography and MRI in the preoperative evaluation of patients with Charcot neuroarthropathy of the foot. Hybrid PET, because of its poorer resolution compared to ring PET, appears less suitable for routine clinical application

Hummingbird diversity, food niche characters, and assemblage composition along a latitudinal precipitation gradient in the Bolivian lowlands

As for many other taxa, hummingbird diversity declines away from the equator, but the causes for this decline are still disputed and might involve, among others, climatic factors or the availability of food resources. Because hummingbirds are one of the classical examples for plant-animal coevolution, it has been proposed that the diversity of hummingbird assemblages might depend on the diversity of food plants available. We tested this hypothesis by studying the hummingbird assemblages and their food plants for 1year at six sites along a 660-km-long transect in Bolivian lowland forests extending from the southernmost Amazonian rain forests to dry Chaco forests. Hummingbird diversity was higher in the northern three sites as compared to the southern ones, with an abrupt decline in species numbers and a corresponding change in taxonomic composition at the boundary from evergreen to drought deciduous forests. Hummingbird diversity and abundance were only weakly correlated to climatic factors or to the diversity of humming-visited flowers, but strongly to the seasonal abundance of flowers. The overlap in nectar diet between hummingbird species depended on the number of plant species: when numerous species were available, the hummingbirds segregated by feeding preferences, but when few flowers were available, all hummingbirds fed on the same plants. We conclude that the local diversity of hummingbird species is not primarily determined by the diversity of food plants, but rather by the abundance of flowers available at any given point in tim

Pro-amateur information space: www.bildungsgeschichte.ch

The paper discusses the possibilities and prospects of a disciplinary search portal for sources and data on the history of education in Switzerland called “Bildungsgeschichte Schweiz” (www.bildungsgeschichte.ch). The open-access and multilingual portal offers a combined full-text and metadata search of historic holdings from different collections and providers. In the context of increasing digitisation and public accessibility of historical materials and the ongoing digital transformation of the humanities, the goal is to create a user-friendly “information space” for researchers and non-researchers alike. The paper focuses on the ideas behind building up this information space and on the possibilities that are given with the application of a search function to a large and diverse data basis. Particular attention is paid to the reuse of research data in the light of current open research data strategies. (DIPF/Orig.)Die Webpräsenz „Bildungsgeschichte Schweiz“ (bildungsgeschichte.ch) zielt darauf ab, Quellen und Daten in großer Vielfalt nicht nur Forschenden, sondern auch einer größeren Öffentlichkeit zur Verfügung zu stellen. Die Kernfunktion dieser Internetseite ist die Möglichkeit einer kombinierten Volltext- und Metadatensuche in mehreren digitalen Beständen. (DIPF/Orig.

Pro-amateur information space: www.bildungsgeschichte.ch

The paper discusses the possibilities and prospects of a disciplinary search portal for sources and data on the history of education in Switzerland called “Bildungsgeschichte Schweiz” (www.bildungsgeschichte.ch). The open-access and multilingual portal offers a combined full-text and metadata search of historic holdings from different collections and providers. In the context of increasing digitisation and public accessibility of historical materials and the ongoing digital transformation of the humanities, the goal is to create a user-friendly “information space” for researchers and non-researchers alike. The paper focuses on the ideas behind building up this information space and on the possibilities that are given with the application of a search function to a large and diverse data basis. Particular attention is paid to the reuse of research data in the light of current open research data strategies

Seasonal changes in odour preferences by male euglossine bees (Hymenoptera: Apidae) and their ecological implications

Orchid bees are an important group of specialized insect pollinators in the Neotropics. Male orchid bees are attracted by a wide range of aromatic substances often produced by flowers. Previous studies found that in some species the males change their aromatic preferences between seasons. In our study we documented seasonal changes of aromatic preferences in five euglossine bee assemblages along a 380-km-long seasonality and precipitation gradient and related them to climatic factors. We found that the proportion of species per site showing changes in their aromatic preference between seasons increased with climatic seasonality towards the south. Those species mainly belong to the genus Euglossa, subgenus Euglossa. We conclude that climatic seasonality mainly affects the orchid bees via the turnover of the aromatic substances provided by the plants. Further, we suggest that the ability to change the aromatic preference between seasons could be interpreted as a phylogenetic pre-adaptation that enabled some species to colonize climatically strongly seasonal habitat

Diversity and community composition of euglossine bee assemblages (Hymenoptera: Apidae) in western Amazonia

Tropical forests are known for their diverse insect fauna. We aimed to determine the effect and relative importance of latitude, elevation and climatic factors affecting species richness and turnover in euglossine bee assemblages along a gradient of 18°latitude from tropical rainforests to subtropical, deciduous dry forests in Peru and Bolivia. Sixteen forest sites were sampled during the dry season. Variance partitioning techniques were applied to assess the relative effects of the spatial and environmental variables on species richness and composition. Furthermore, we conducted a Species Indicator Analysis to find characteristic species for the biogeographic zones. There was a significant decrease in species richness towards the subtropical area. The best predictors of species richness were precipitation and its consequences on soil properties as well as temperature seasonality. The abundance of euglossines was most closely related to precipitation and soil-pH, but the causal links of abundance to these factors is unclear since soil-pH itself is correlated to a drastic turnover of vegetation structure. Based on the analysis of assemblage composition we propose three different assemblages with a transitional zone at the southern tropical area. The biogeographical distribution of euglossine bees along our study transect appears to be primarily related to climatic conditions and does not reflect the common subdividion of Amazonia into drainage system