Origin, ore forming fluid evolution and timing of the Logrosán Sn-(W) ore deposits (Central Iberian Zone, Spain)

The Logrosán Sn–(W) ore deposits in the metallogenic Sn–W province of the European Variscan Belt consist of endo- and exogranitic greisen-type and quartz–cassiterite veins associated with a S-type granite. Mineral characterization, fluid inclusion study, isotope geochemistry and Ar–Ar geochronology have been combined in order to reconstruct the conditions for Sn–(W) mineralization. The endo- and exogranitic mineralization must have been developed in a relatively long-lived system (~ 308–303 Ma), during or soon after the emplacement of the Logrosán related-granite (at ca. 308 Ma). The mineralizing fluids are characterized by complex aqueous and volatile (H2O–N2–CO2–CH4–NaCl) fluid inclusions. Microthermometry and Raman analyses indicate that fluid composition evolved from N2–CH4 to N2-rich, followed by CO2-rich fluids, with varying amounts of H2O. The presence of N2 and CH4 suggests the interaction with fluids derived from the nearby metasedimentary host rocks. A model of host-rock interaction, assimilation, and mixing of metamorphic and magmatic fluids, resulting in change of the redox conditions, is proposed for tin deposition. Later sulfide minerals were precipitated as a result of pressure and temperature release

Construction of global optimization constrained NLP test cases from unconstrained problems

This paper presents a novel construction technique for constrained nonconvex Nonlinear Programming Problem (NLP) test cases, derived from the evaluation tree structure of standardized bound constrained problems for which the global solution is known. It is demonstrated in a step-by-step procedure how first an equality constrained problem can be derived from an unconstrained one, with bounds imposed on all variables, using the Directed Acyclic Graph (DAG) of the unconstrained objective function and the use of interval arithmetic to derive bounds for the new variables introduced. An advantage of the proposed methodology is that several standard unconstrained global optimization test cases can be constructed for varying number of optimization variables, thus leading to adjustable size derived NLP’s. Further to this in a second step it is demonstrated how any subset of the equalities derived can be relaxed into inequalities giving an equivalent optimization problem. Finally, in a third step it is demonstrated how, by reducing the number of equality constraints derived, it is possible to obtain more complex expressions in the constraints and objective function. The methodology is highlighted throughout by motivating examples and a sample code in Mathematica TM is provided in the Appendix.This is the author accepted manuscript. The final version is available from Elsevier via https://doi.org/https://doi.org/10.1016/j.cherd.2016.03.01

Poly(bromoethyl acrylate) : a reactive precursor for the synthesis of functional RAFT materials

Postpolymerization modification has become a powerful tool to create a diversity of functional materials. However, simple nucleophilic substitution reactions on halogenated monomers remains relatively unexplored. Here we report the synthesis of poly(bromoethyl acrylate) (pBEA) by reversible addition–fragmentation chain transfer (RAFT) polymerization to generate a highly reactive polymer precursor for postpolymerization nucleophilic substitution. RAFT polymerization of BEA generated well-defined homopolymers and block copolymers over a range of molecular weights. The alkylbromine-containing homopolymer and block copolymer precursors were readily substituted by a range of nucleophiles in good to excellent conversion under mild and efficient reaction conditions without the need of additional catalysts. The broad range of nucleophilic species that are compatible with this postmodification strategy enables facile synthesis of complex functionalities, from permanently charged polyanions to hydrophobic polythioethers to glycopolymers

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 144

This bibliography lists 257 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Skyrmion and other extended solutions of non-linear σ-models in 2 and (2+1) dimensions

Low dimensional models are generally regarded to be a convenient theoretical laboratory for studying various aspects of elementary particle theory. In this thesis, the extended solutions of one particular class of such models, namely the ₵p(^n-1) non-linear a-models in 2 dimensions, are discussed. Special attention is paid to the shape of these extended structures and their dependence on the parameters of the solutions. Time dependence is introduced into the models, and properties of the moving objects in these (2 + l)-dimensional theories are explored. In particular, the Hopf terms of the theories are investigated, and their relation to the spin of the extended solutions is discussed. Also the classical dynamics of these moving objects, and their explanation in terms of the geodesic motions on certain Hermitian and Kāhler manifolds is considered. Finally the embedding of the (₵p(^n-1) solutions into the 2-dimensional U(n) chiral models is studied, paying particular attention to the stability of these embedded solutions in the larger group space, and to the number of independent negative modes of the fluctuation operator around these solutions

Stateful-Failure Reactive Designs in Isabelle/UTP

Stateful-Failure Reactive Designs specialise reactive design contracts with failures traces, as present in languages like CSP and Circus. A failure trace consists of a sequence of events and a refusal set. It intuitively represents a quiescent observation, where certain events have previously occurred, and others are currently being accepted. Following the UTP book, we add an observational variable to represent refusal sets, and healthiness conditions that ensure their well-formedness. Using these, we also specialise our theory of reactive relations with operators to characterise both completed and quiescent interactions, and an accompanying equational theory. We use these to define the core operators — including assignment, event occurrence, and external choice — and specialise our proof strategy to support these. We also demonstrate a link with the CSP failures-divergences semantic model

Mutations in Orai1 transmembrane segment 1 cause STIM1-independent activation of Orai1 channels at glycine 98 and channel closure at arginine 91

Stim and Orai proteins comprise the molecular machinery of Ca(2+) release-activated Ca(2+) (CRAC) channels. As an approach toward understanding the gating of Orai1 channels, we investigated effects of selected mutations at two conserved sites in the first transmembrane segment (TM1): arginine 91 located near the cytosolic end of TM1 and glycine 98 near the middle of TM1. Orai1 R91C, when coexpressed with STIM1, was activated normally by Ca(2+)-store depletion. Treatment with diamide, a thiol-oxidizing agent, induced formation of disulfide bonds between R91C residues in adjacent Orai1 subunits and rapidly blocked STIM1-operated Ca(2+) current. Diamide-induced blocking was reversed by disulfide bond-reducing agents. These results indicate that R91 forms a very narrow part of the conducting pore at the cytosolic side. Alanine replacement at G98 prevented STIM1-induced channel activity. Interestingly, mutation to aspartate (G98D) or proline (G98P) caused constitutive channel activation in a STIM1-independent manner. Both Orai1 G98 mutants formed a nonselective Ca(2+)-permeable conductance that was relatively resistant to block by Gd(3+). The double mutant R91W/G98D was also constitutively active, overcoming the normal inhibition of channel activity by tryptophan at the 91 position found in some patients with severe combined immunodeficiency (SCID), and the double mutant R91C/G98D was resistant to diamide block. These data suggest that the channel pore is widened and ion selectivity is altered by mutations at the G98 site that may perturb α-helical structure. We propose distinct functional roles for G98 as a gating hinge and R91 as part of the physical gate at the narrow inner mouth of the channel