193 research outputs found
Synthesis and Testing of Second Generation Azatilbenes
Based on previous research, azastilbenes have been reported as effective chemical sensors for organophosphates and organothiophosphates; they are related classes and the active components of agricultural pesticides, environmental pollutants and chemical warfare agents. This project builds on previous work and involves the synthesis of a variety of these azastilbenes and the testing of their respective properties. Azastilbene sensors are prepared using high-yield organic synthetic methodology developed in Professor Murray\u27s lab. The next step involves testing the sensors through a measure, by UV-Vis spectroscopy and fluorometry, of an optical change upon the addition of analyte to a solution containing azastilbene sensor
Ătude archĂ©ologique de la plate-forme du MÄlamatagata Ă âUtuleve, Ăźle de âUvea (Wallis)
La tradition orale rapporte que la plate-forme du MÄlamatagata, sur le site de âUtuleve Ă âUvea (Wallis), a Ă©tĂ© construite par un chef de Tonga Ă lâoccasion de lâaccouchement de sa fille, afin de montrer Ă tous le haut rang quâelle occupait dans la sociĂ©tĂ© tongienne. Au dĂ©but des annĂ©es 1990, les autoritĂ©s du territoire ont souhaitĂ© que soit rĂ©alisĂ©e lâĂ©tude scientifique et la mise en valeur de cette structure. Ce programme a permis de montrer que le monument avait Ă©tĂ© construit en plusieurs Ă©tapes et a contribuĂ© Ă mieux dĂ©finir les techniques de construction employĂ©es pour lâĂ©dification des monuments anciens en PolynĂ©sie occidentale.The oral traditions report that the MÄlamatagata platform, located on the site of âUtuleve on âUvea island (Wallis), was constructed by a chief from Tonga, as a birthplace for his grand-son, in order to show to all the high rank occupied by his daughter in the Tongan society. In the early 1990s, the political authorities of the Territory decided to fulfil a scientific study and a restauration project on this monument. This program has shown that the monument had gone through various episodes of construction, and provided a better knowledge of the construction techniques used for the building of ancient monuments in Western Polynesia
Metrical Diophantine approximation for quaternions
Analogues of the classical theorems of Khintchine, Jarnik and
Jarnik-Besicovitch in the metrical theory of Diophantine approximation are
established for quaternions by applying results on the measure of general `lim
sup' sets.Comment: 30 pages. Some minor improvement
Les poissons de la Grande Grotte d'Arcy-sur-Cure (Yonne)
Un original mĂ©todo de investigacion, mediante adelgazamiento de la calcita, utilizado por primera vez en una cueva con decoraciĂłn paleolĂtica ha permitido sacar a la luz, entre otras cosas, cuatro peces pintados en negro sobre las paredes de la Grande Grotte d'Arcy-sur-Cure (Yonne, France). Dichos peces, salmĂłnidos y lucio, confirman el carĂĄcter excepcional el bestiario de esta gruta constituido por animales que no estĂĄn presentes en las demĂĄs, a excepciĂłn de la de la cueva Chauvet (ArdechĂš) ; mamuts, rinocerontes, osos, felino, aves, megĂĄceros. Los vestigios, bien conservados, encontrados sobre su suelo nos han permitido determinar que fue utilizada en la Ă©poca auriñaciense gravetiense
The EROS2 search for microlensing events towards the spiral arms: the complete seven season results
The EROS-2 project has been designed to search for microlensing events
towards any dense stellar field. The densest parts of the Galactic spiral arms
have been monitored to maximize the microlensing signal expected from the stars
of the Galactic disk and bulge. 12.9 million stars have been monitored during 7
seasons towards 4 directions in the Galactic plane, away from the Galactic
center. A total of 27 microlensing event candidates have been found. Estimates
of the optical depths from the 22 best events are provided. A first order
interpretation shows that simple Galactic models with a standard disk and an
elongated bulge are in agreement with our observations. We find that the
average microlensing optical depth towards the complete EROS-cataloged stars of
the spiral arms is , a number that is
stable when the selection criteria are moderately varied. As the EROS catalog
is almost complete up to , the optical depth estimated for the
sub-sample of bright target stars with () is easier to interpret. The set of microlensing events
that we have observed is consistent with a simple Galactic model. A more
precise interpretation would require either a better knowledge of the distance
distribution of the target stars, or a simulation based on a Galactic model.
For this purpose, we define and discuss the concept of optical depth for a
given catalog or for a limiting magnitude.Comment: 22 pages submitted to Astronomy & Astrophysic
Superconductivity close to the Mott state: From condensed-matter systems to superfluidity in optical lattices
Since the discovery of high-temperature superconductivity in 1986 by Bednorz
and Mueller, great efforts have been devoted to finding out how and why it
works. From the d-wave symmetry of the order parameter, the importance of
antiferromagnetic fluctuations, and the presence of a mysterious pseudogap
phase close to the Mott state, one can conclude that high-Tc superconductors
are clearly distinguishable from the well-understood BCS superconductors. The
d-wave superconducting state can be understood through a Gutzwiller-type
projected BCS wave-function. In this review article, we revisit the Hubbard
model at half-filling and focus on the emergence of exotic superconductivity
with d-wave symmetry in the vicinity of the Mott state, starting from ladder
systems and then studying the dimensional crossovers to higher dimensions. This
allows to confirm that short-range antiferromagnetic fluctuations can mediate
superconductivity with d-wave symmetry. Ladders are also nice prototype systems
allowing to demonstrate the truncation of the Fermi surface and the emergence
of a Resonating Valence Bond (RVB) state with preformed pairs in the vicinity
of the Mott state. In two dimensions, a similar scenario emerges from
renormalization group arguments. We also discuss theoretical predictions for
the d-wave superconducting phase as well as the pseudogap phase, and address
the crossover to the overdoped regime. Finally, cold atomic systems with
tunable parameters also provide a complementary insight into this outstanding
problem.Comment: 98 pages and 18 figures; Final version (references added and
misprints corrected
Calibration of GENEActiv accelerometer wrist cut-points for the assessment of physical activity intensity of pre-school aged children
This study sought to validate cut-points for use of wrist worn GENEActiv accelerometer data, to analyse preschool childrenâs (4 to 5 year olds) physical activity (PA) levels via calibration with oxygen consumption values (VO2). This was a laboratory based calibration study. Twenty-one preschool children, aged 4.7 ± 0.5 years old, completed six activities (ranging from lying supine to running) whilst wearing the GENEActiv accelerometers at two locations (left and right wrist), these being the participantsâ non-dominant and dominant wrist, and a Cortex face mask for gas analysis. VO2 data was used for the assessment of criterion validity. Location specific activity intensity cut points were established via Receiver Operator Characteristic curve (ROC) analysis. The GENEActiv accelerometers, irrespective of their location, accurately discriminated between all PA intensities (sedentary, light, and moderate and above), with the dominant wrist monitor providing a slightly more precise discrimination at light PA and the non-dominant at the sedentary behaviour and moderate and above intensity levels (Area Under the Curve (AUC) for non-dominant = 0.749-0.993, compared to AUC dominant = 0.760-0.988). Conclusion: This study establishes wrist-worn physical activity cut points for the GENEActiv accelerometer in pre-schoolers.N/
emerging technologies for food and drug safety
Abstract Emerging technologies are playing a major role in the generation of new approaches to assess the safety of both foods and drugs. However, the integration of emerging technologies in the regulatory decision-making process requires rigorous assessment and consensus amongst international partners and research communities. To that end, the Global Coalition for Regulatory Science Research (GCRSR) in partnership with the Brazilian Health Surveillance Agency (ANVISA) hosted the seventh Global Summit on Regulatory Science (GSRS17) in Brasilia, Brazil on September 18â20, 2017 to discuss the role of new approaches in regulatory science with a specific emphasis on applications in food and medical product safety. The global regulatory landscape concerning the application of new technologies was assessed in several countries worldwide. Challenges and issues were discussed in the context of developing an international consensus for objective criteria in the development, application and review of emerging technologies. The need for advanced approaches to allow for faster, less expensive and more predictive methodologies was elaborated. In addition, the strengths and weaknesses of each new approach was discussed. And finally, the need for standards and reproducible approaches was reviewed to enhance the application of the emerging technologies to improve food and drug safety. The overarching goal of GSRS17 was to provide a venue where regulators and researchers meet to develop collaborations addressing the most pressing scientific challenges and facilitate the adoption of novel technical innovations to advance the field of regulatory science
HBM4EU chromates study - Overall results and recommendations for the biomonitoring of occupational exposure to hexavalent chromium
Exposure to hexavalent chromium [Cr(VI)] may occur in several occupational activities, e.g., welding, Cr(VI) electroplating and other surface treatment processes. The aim of this study was to provide EU relevant data on occupational Cr(VI) exposure to support the regulatory risk assessment and decision-making. In addition, the capability and validity of different biomarkers for the assessment of Cr(VI) exposure were evaluated. The study involved nine European countries and involved 399 workers in different industry sectors with exposures to Cr(VI) such as welding, bath plating, applying or removing paint and other tasks. We also studied 203 controls to establish a background in workers with no direct exposure to Cr(VI). We applied a cross-sectional study design and used chromium in urine as the primary biomonitoring method for Cr(VI) exposure. Additionally, we studied the use of red blood cells (RBC) and exhaled breath condensate (EBC) for biomonitoring of exposure to Cr(VI). Personal measurements were used to study exposure to inhalable and respirable Cr(VI) by personal air sampling. Dermal exposure was studied by taking hand wipe samples. The highest internal exposures were observed in the use of Cr(VI) in electrolytic bath plating. In stainless steel welding the internal Cr exposure was clearly lower when compared to plating activities. We observed a high correlation between chromium urinary levels and air Cr(VI) or dermal total Cr exposure. Urinary chromium showed its value as a first approach for the assessment of total, internal exposure. Correlations between urinary chromium and Cr(VI) in EBC and Cr in RBC were low, probably due to differences in kinetics and indicating that these biomonitoring approaches may not be interchangeable but rather complementary. This study showed that occupational biomonitoring studies can be conducted successfully by multi-national collaboration and provide relevant information to support policy actions aiming to reduce occupational exposure to chemicals.This work has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 733032 and received co-funding from the author's organizations and/or Ministries. Luxembourg entered the study at a later stage and thus financed the study at its own means.S
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