920 research outputs found
Polarization-based Light-Atom Quantum Interface with an All-optical Trap
We describe the implementation of a system for studying light-matter
interactions using an ensemble of cold rubidium 87 atoms, trapped in a
single-beam optical dipole trap. In this configuration the elongated shape of
the atomic cloud increases the strength of the collective light-atom coupling.
Trapping all-optically allows for long storage times in a low decoherence
environment. We are able to perform several thousands of measurements on one
atomic ensemble with little destruction. We report results on paramagnetic
Faraday rotations from a macroscopically polarized atomic ensemble. Our results
confirm that strong light-atom coupling is achievable in this system which
makes it attractive for single-pass quantum information protocols.Comment: 8 pages, 4 figure
Remote sensing investigation techniques for the analysis of rocky slope stability in remote areas: a test from the Sierra Madre Occidental, Mexico
Direct field survey to assess slope stability in steep and remote rocky cliffs is time demanding and highly consuming in term of human and economic resources. However, evolving technologies allow remotely sensed data integrated with GIS to theoretically provide equivalent information. Here we present a case study comparison of these methods applied to the Eastern valley-side of the Chinipas River, Sierra Madre Occidental, Mexico.
Results show that remote sensing procedures provides the same discontinuity sets and equivalent attitude information with respect to the data acquired during field survey
Unimolecular Variant of the Fluorescence Turn-On Oxidative Coupling of Catecholamines with Resorcinols
Reported herein is a unimolecular variant of the fluorescence turn-on oxidative coupling of catecholamines with resorcinols ("FluoResCat") based on the easily accessible conjugate 4-(2-((2,4-dihydroxybenzyl)amino)ethyl)benzene-1,2-diol (1). The process involves an alkali-activatable sequence of autoxidation and intramolecular cyclization steps with loss of carbon, leading to a fluorescent methanobenzofuroazocinone product identical to that obtained from the oxidative coupling of dopamine with resorcinol. A mechanistic route for this unexpected reaction, mimicking the synthesis of the natural fluorophore matlaline, would involve highly constrained polycyclic spiro intermediates (liquid chromatography–mass spectrometry analysis of intermediates, model reactions, and density functional theory calculations). Emission turn-on from 1 in response to oxygen, superoxide-generating systems, or gaseous ammonia/volatile amines may be of interest for sensing applications, for example, in smart packaging
Time-resolved EPR investigation of oxygen and temperature effects on synthetic eumelanin
Synthetic eumelanin produced using 5,6-dihydroxyindole-2-carboxylic acid as precursor and H2O2/horseradish peroxidase as oxidative reagent, in form of dry powder, has been investigated under photoexcitation by TR-EPR spectroscopy. The formation of spin polarized radical pairs from triplet excited states of melanin has been observed both in absence and in presence of oxygen and has been followed as a function of the temperature in the range 140–290 K. The triplet mechanism explains the observed polarization pattern in net emission. In the presence of oxygen new radical pairs are formed by interaction of melanin with molecular oxygen
A preliminary study on a novel bioaugmentation technique enhancing lactic acid production by mixed cultures fermentation
The paper is a preliminary study on the selection of lactic acid producing microorganisms from a mixed microbial
population via bioaugmentation. The bioaugmentation technique is based on pH sudden variations occurring in
sequential batch steps of a dark fermentation process applied to simple substrates. Different conditions are tested
and compared. The structure of microbial communities and concentrations of metabolic intermediates are
analyzed to study the possible substrate conversion routes. Obtained results indicate that the initial mixed culture
produced a lactic acid percentage of 5% in terms of CODLA/CODPRODUCTS. In the most favourable conditions, the
selected culture produced a lactic acid percentage of 59%. The analysis of the composition of microbial communities before and after the bioaugmentation processes, indicates that lactic acid production mainly results
from the population change to bacteria belonging to the genus Bacillus. Indeed, the relative abundance of Bacilli
increased from 0.67%, to 8.40% during the bioaugmentation cycle
Collaborative mapping response to disasters through OpenStreetMap: the case of the 2016 Italian earthquake
Digital humanitarians represent the current generation of volunteers providing timely contributions in the form
of digital map data in the aftermath of natural disasters. Starting from the tragic 2010 earthquake in Haiti and
thanks to the success of the OpenStreetMap (OSM) project, the presence and coordination of these volunteers
have grown incredibly over the past years. This work investigates the dynamics of the mapping process and the
nature of the OSM volunteers who contributed map data after the 2016 earthquake in Central Italy. The analyses
show that the existing OSM users were the majority of those contributing to the mapping activity, with less edits
performed by new users. The collaborative mapping process was efficiently coordinated through a dedicated
platform and the area hit by the earthquake was significantly edited in OSM after the disaster
- …