332 research outputs found
On Auxiliary Fields in BF Theories
We discuss the structure of auxiliary fields for non-Abelian BF theories in
arbitrary dimensions. By modifying the classical BRST operator, we build the
on-shell invariant complete quantum action. Therefore, we introduce the
auxiliary fields which close the BRST algebra and lead to the invariant
extension of the classical action.Comment: 7 pages, minor changes, typos in equations corrected and
acknowledgements adde
Calculated Electronic Energy Loss of Heavy Ions at Low Energies in LR-115, Kapton, SiO2, and Al2O3 Amorphous Materials
The electronic stopping powers of LR-115 and Kapton polymeric foilshave been estimated, using Monte Carlo simulations, for 9Be, 11B, 12C, 14N, 16O, and 35Cl ions covering the energy range ~0.1-1.0 MeV/n. Comparison of stopping power based on Lindhard, Scharff, and Schiott (LSS) theory with the corresponding values obtained by SRIM and MSTAR codes in LR-115 and Kapton polymeric foils illustrate a significantly large deviations. However, a semiempirical equation has been proposed here and tested for better stopping power calculations at low-energy regime in the domain of LSS theory for ZÂ =Â 4-8 ions across materials. Furthermore, the electronic energy losses for 9Be and 16O ions in SiO2 and Al2O3, respectively, have been calculated in the energy range of ~0.1-1.0 MeV/n. The calculated stopping powers exhibit up to 10 % deviation from the experimental values and MSTAR data
Geodiversity Examples of Morocco: From Inventory to Regional Geotourism Development
The soil and subsoil of Morocco are rich in geological phenomena that bear the imprint of a history which goes back in time more than 2000 million years. Very many geologically remarkable sites exposed in accessible outcrops, with good quality remained unknown to the general public and therefore deserved to be vulgarized. It is a memory to acquaint the present generations but also to preserve for future generations. In total, a rich geological heritage in many ways: Varied land- scapes, international stratotypes, various geological structures, varied rocks, mineral associations, a huge procession offossiles, remnants of oceanic crust (ophiolites) among oldests ones in the world (800 my), etc. For this geological heritage, an approach of an overall inventory is needed, both regionally and nationally, taking into account all the skills of the earth sciences. This will put the item on the natural (geological) potentialities as a lever for sustainable regional development. For this, it is necessary to implement a strategy of âgeoconservationâ for the preservation and as- sessment of the geological heritage. A website âlithothĂšque du Marocâ is under construction.info:eu-repo/semantics/publishedVersio
Systematics of detrital zircon UâPb ages from CambrianâLower Devonian rocks of northern Morocco with implications for the northern Gondwanan passive margin
This study was found by the Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR (CGL2015-71692) and the Pre-Doctoral scholarship BES-2016-078168. We are indebted to Mike Hall and Brad McDonald for their assistance and technical support on sample preparation and the LA-ICPMS, respectively. The CL imaging was carried out on the Curtin University's Microscopy & Microanalysis Facility, whose instrumentation has been partially funded by the University, State and Commonwealth Governments, and the Scanning Electron Microscope (SEM) Facility at the University of Edinburgh. Analysis in the SHRIMP and GeoHistory Facilities, JdLC, Curtin University were enabled by AuScope (auscope.org.au) and the Australian Government via the National Collaborative Research Infrastructure Strategy (NCRIS) and an Australian Geophysical Observing System grant provided to AuScope Pty Ltd. by the AQ44 Australian Education Investment Fund program, respectively. The NPII multi-collector was obtained via funding from the Australian Research Council LIEF program (LE150100013). The SIMS analyses were performed at the NERC Ion Microprobe Facility of the University of Edinburgh (UK). Comments from two anonymous reviewers and editorial handling by Prof. Victoria Pease are acknowledged. Funding for open access charge: YUniversidad de Granada / CBUA.The systematic acquisition of UâPb geochronological data from detrital zircon grains has become an essential
tool in tectonic studies focused on reconstructing the preâVariscan geography of the northern Gondwanan
passive margin. New detrital zircon ages for 16 samples from the CambrianâLower Devonian succession of the
Moroccan Mesetas (northern Morocco) are reported here. The results, combined with previously published data,
reassert the strong West African Craton affinity of the Paleozoic sedimentary rocks, characterized by dominant
Cadomian/PanâAfrican (c. 850â540 Ma) and Eburnean (c. 2.2â1.9 Ga) detrital zircon populations and a minor
Leonian/Liberian (c. 2.5 Ga) population. Primary sources of these zircon grains are well established as the West
African Craton located just to the south, but also in the Precambrian basement that locally crops out in the
Moroccan Mesetas themselves. During the CambrianâEarly Ordovician, erosion preferentially dismantled
Cadomian (c. 590â540 Ma) arcâderived rocks of the Gondwanan continental margin, while later, the slightly
older PanâAfrican (c. 650â600 Ma) basement became the main sediment source. In the studied samples, irregularly
present minor detrital zircon populations suggest additional sediment provenance from secondary sources
such as: (i) remote northeastern African cratons (e.g., Saharan Metacraton and/or ArabianâNubian Shield) that
likely could have provided the c. 1.1â0.9 Ga and, possibly, the c. 1.9â1.7 Ga zircon grains, and (ii) riftârelated
CambrianâEarly Ordovician volcanic centers in the Moroccan Mesetas that supplied heterogeneously distributed
â although locally dominant in small areas â sedimentary detritus before rift abortion and burial underneath the
overlying passive margin sedimentary succession.Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR CGL2015-71692Scanning Electron Microscope (SEM) Facility at the University of EdinburghAustralian Geophysical Observing System grant by AQ44 Australian Education Investment Fund programAustralian Research Council LE150100013Universidad de Granada / CBUA
BES-2016-07816
Total Synthesis of a Mycolic Acid from Mycobacterium tuberculosis
In Mycobacterium tuberculosis, mycolic acids and their glycerol, glucose, and trehalose esters ("cord factor") form the main part of the mycomembrane. Despite their first isolation almost a century ago, full stereochemical evaluation is lacking, as is a scalable synthesis required for accurate immunological, including vaccination, studies. Herein, we report an efficient, convergent, gram-scale synthesis of four stereo-isomers of a mycolic acid and its glucose ester. Binding to the antigen presenting protein CD1b and T cell activation studies are used to confirm the antigenicity of the synthetic material. The absolute stereochemistry of the syn-methoxy methyl moiety in natural material is evaluated by comparing its optical rotation with that of synthetic material
Stereoselective Protection-Free Modification of 3-Keto-saccharides
Unprotected 3-keto-saccharides have become readily accessible via site-selective oxidation, but their protection-free functionalization is relatively unexplored. Here we show that protecting groups are obsolete in a variety of stereoselective modifications of our model substrate methyl α-glucopyranoside. This allows the preparation of rare sugars and the installation of click handles and reactive groups. To showcase the applicability of the methodology, maltoheptaose has been converted into a chemical probe, and the rare sugar evalose has been synthesized
Tectonic evolution of the Eastern Moroccan Meseta: from Late Devonian foreâarc sedimentation to Early Carboniferous collision of an Avalonian promontory
This study was founded by the Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR (CGL2015-71692-P) and the Doctoral scholarship BES-2016-078168. GeoHistory Facility instruments were funded via an Australian Geophysical Observing System grant provided to AuScope Pty Ltd. by the AQ44 Australian Education Investment Fund program. The NPII multicollector was obtained via funding from the Australian Research Council LIEF program (LE150100013). The authors want to express their gratitude to Dr. Manuel Francisco Pereira (University of Evora, Portugal) and Dr. Michel Villeneuve (Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, France) for their constructive reviews that helped to improve the quality of the original manuscript. Special thanks to Brad McDonald (Curtin University, Australia) for technical assistance regarding LA-ICPMS and Hf analyses, Profs. Abdelfatah Tahiri (University Mohammed V of Rabat, Morocco) and Hassan El Hadi (University Hassan II of Casablanca, Morocco) for their support during field work, Prof. Yvette Kuiper (Colorado School of Mines, USA) for her precious hints about the interpretation of Hf data, and Dr. Lorenzo Valetti for proofreading the manuscript. Supporting information can be obtained in Mendeley Data: https://doi.org/10.17632/b8fdbykmbx.1 (https://data.mendeley.com/datasets/b8fdbykmbx/draft?a=eaae2da0-8e224056-861b-4824984f1c10).The deformed Paleozoic succession of the Eastern Moroccan Meseta crops out in relativelysmall and isolated inliers surrounded by Mesozoic and Cenozoic rocks. Two of the largest inliers(Mekkam and Debdou) are characterized by a monotonous succession of slates and greywackes affected bypolyphasic folding that occurred at lowâto very low grade metamorphic conditions. New UâPb ages ondetrital zircon grains from the DebdouâMekkam metasediments constrain the maximal depositional age asLate Devonian, interpreted to be close to the true sedimentation age. Furthermore, theΔHfvalues of theDevonian detrital zircons, together with the presence of a series of scattered zircon grains with ages betweenc. 0.9 and c. 1.9 Ga, suggest provenance from a subductionârelated magmatic arc located on the Avalonianmargin. The DebdouâMekkam massif is characterized by an Early Carboniferousfirst deformationalevent (D1), which gave way to a pervasive cleavage (S1) associated with plurikilometricâscale, tight toisoclinal, overturned to recumbent folds. Later events (Dc) occurred at Late Carboniferous time andgenerated variably developed crenulation cleavages (Sc) associated with variously oriented metricâtokilometricâscale folds, which complicate the pattern of both D1 intersection lineations (L1) and axial traces.The restoration of this pronounced curved pattern yields originally SWâNEâoriented D1 fold axes withregional SEâvergence. This important Early Carboniferous shortening and SEâdirected tectonic transport canbe explained by closure of the Rheic Ocean and thefirst phases of the collision between the northern passivemargin of Gondwana and an Avalonian promontory.Ministerio de Economia y Competitividad (MINECO) of Spain
CGL2015-71692-P
BES-2016-078168Australian Geophysical Observing SystemAustralian Education Investment Fund program
AQ44Australian Research Council
LE15010001
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