15 research outputs found
Maude: specification and programming in rewriting logic
AbstractMaude is a high-level language and a high-performance system supporting executable specification and declarative programming in rewriting logic. Since rewriting logic contains equational logic, Maude also supports equational specification and programming in its sublanguage of functional modules and theories. The underlying equational logic chosen for Maude is membership equational logic, that has sorts, subsorts, operator overloading, and partiality definable by membership and equality conditions. Rewriting logic is reflective, in the sense of being able to express its own metalevel at the object level. Reflection is systematically exploited in Maude endowing the language with powerful metaprogramming capabilities, including both user-definable module operations and declarative strategies to guide the deduction process. This paper explains and illustrates with examples the main concepts of Maude's language design, including its underlying logic, functional, system and object-oriented modules, as well as parameterized modules, theories, and views. We also explain how Maude supports reflection, metaprogramming and internal strategies. The paper outlines the principles underlying the Maude system implementation, including its semicompilation techniques. We conclude with some remarks about applications, work on a formal environment for Maude, and a mobile language extension of Maude
Uniqueness in MHD in divergence form: right nullvectors and well-posedness
Magnetohydrodynamics in divergence form describes a hyperbolic system of
covariant and constraint-free equations. It comprises a linear combination of
an algebraic constraint and Faraday's equations. Here, we study the problem of
well-posedness, and identify a preferred linear combination in this divergence
formulation. The limit of weak magnetic fields shows the slow magnetosonic and
Alfven waves to bifurcate from the contact discontinuity (entropy waves), while
the fast magnetosonic wave is a regular perturbation of the hydrodynamical
sound speed. These results are further reported as a starting point for
characteristic based shock capturing schemes for simulations with
ultra-relativistic shocks in magnetized relativistic fluids.Comment: To appear in J Math Phy
Early Pleistocene volcanism in the Emile Baudot Seamount, Balearic Promontory (western Mediterranean Sea)
The recovery of calcareous breccia and other carbonate-cemented rocks from Mont dels Oliva in the Balearic Promontory indicates that both this seamount and the adjacent Mont Ausias Marc, east of Ibiza and Formentera islands, are of continental origin. Recent multibeam echosounder mapping and high-resolution seismic reflection profiles indicate that the third high, Emile Baudot Seamount, is located within a field of more than 118 pinnacles. Based on their magnetic signature and the recovery of basalt in the vicinity of the pinnacles suggest that the features are of volcanic origin. A basalt sample dredged from Emile Baudot Seamount indicates an igneous origin for this seamount. The limited sampling, the chemistry of the rock recovered and the size of the seamount itself (18 by 3 km), however, does not preclude the possibility that Emile Baudot may be a fractured uplifted continental block intruded by the basalt. The K/Ar age of 1.46±0.18 my yielded by the basalt sample verifies the earlier proposal by Acosta et al. (Mar. Pet. Geol. 128 (2001a) 349) that the volcanism that created part or all of Emile Baudot Seamount and the Southwest Majorca Volcanic Field associated with the seamount took place in the Pleistocene. This volcanism is probably related to decompression resulting from the normal faulting that led to the subsidence of the low (Central Depression) between Ibiza and Majorca (Balearic Islands)
Catchment soil moisture and rainfall characteristics as determinant factors for discharge/suspended sediment hysteretic loops in a small headwater catchment in the Spanish Pyrennes
The concentration of suspended sediment and discharge generated during flood events are not normally homogenous, and the curve representing sediment concentration vs. discharge through time is often a hysteretic loop. Three types of hysteretic loops were found at Arnás, a Mediterranean headwater catchment in the Central Spanish Pyrenees: clockwise (the most frequent), counter-clockwise and eight-shaped. They are associated with different levels of humidity and rainfall and therefore indicators of different processes of runoff and sediment transport. Clockwise loops are generated under 'normal' stormflow conditions, when the catchment is very moist and runoff generation and sediment supply is limited to areas next to the channel (i.e. sediments are removed, transported and depleted rapidly). Counter-clockwise curves occur under very high moisture and high antecedent rainfall conditions. In this case, flood propagation occurs as a kinematic wave. Sediment sources are incorporated all over the catchment. In both cases, saturation excess overland flow generates the superficial runoff. The eight-shaped loop (partial clockwise followed by counter-clockwise) occurs with low water content. Here, the runoff generation process is supposed to be infiltration excess overland flow, which causes a rapid extension of the contributing areas both near the channel and over the whole catchment. © 2003 Elsevier B.V. All rights reserved
Ruthenium Red Colorimetric and Birefringent Staining of Amyloid‑β Aggregates in Vitro and in Tg2576 Mice
Alzheimer’s disease (AD) is a devastating neurodegenerative
disease most notably characterized by the misfolding of amyloid-β
(Aβ) into fibrils and its accumulation into plaques. In this
Article, we utilize the affinity of Aβ fibrils to bind metal
cations and subsequently imprint their chirality to bound molecules
to develop novel imaging compounds for staining Aβ aggregates.
Here, we investigate the cationic dye ruthenium red (ammoniated ruthenium
oxychloride) that binds calcium-binding proteins, as a labeling agent
for Aβ deposits. Ruthenium red stained amyloid plaques red under
light microscopy, and exhibited birefringence under crossed polarizers
when bound to Aβ plaques in brain tissue sections from the Tg2576
mouse model of AD. Staining of Aβ plaques was confirmed via
staining of the same sections with the fluorescent amyloid binding
dye Thioflavin S. In addition, it was confirmed that divalent cations
such as calcium displace ruthenium red, consistent with a mechanism
of binding by electrostatic interaction. We further characterized
the interaction of ruthenium red with synthetic Aβ fibrils using
independent biophysical techniques. Ruthenium red exhibited birefringence
and induced circular dichroic bands at 540 nm upon binding to Aβ
fibrils due to induced chirality. Thus, the chirality and cation binding
properties of Aβ aggregates could be capitalized for the development
of novel amyloid labeling methods, adding to the arsenal of AD imaging
techniques and diagnostic tools