Algorithm for the numerical calculation of the serial components of the normal form of depolarizing Mueller matrices

The normal form of a depolarizing Mueller matrix constitutes an important tool for the phenomenological interpretation of experimental polarimetric data. Due to its structure as a serial combination of three Mueller matrices, namely a canonical depolarizing Mueller matrix sandwiched between two pure (nondepolarizing) Mueller matrices, it overcomes the necessity of making a priori choices on the order of the polarimetric components, as this occurs in other serial decompositions. Because Mueller polarimetry addresses more and more applications in a wide range of areas in science, engineering, medicine, etc., the normal form decomposition has an enormous potential for the analysis of experimentally determined Mueller matrices. However, its systematic use has been limited to some extent because of the lack of numerical procedure for the calculation of each polarimetric component, in particular in the case of Type II Mueller matrices. In this work, an efficient algorithm applicable to the decomposition of both Type II and Type I Mueller matrices is presented

Physical significance of the determinant of a Mueller matrix

The determinant of a Mueller matrix M plays an important role in both polarization algebra and the interpretation of polarimetric measurements. While certain physical quantities encoded in M admit a direct interpretation, the understanding of the physical and geometric significance of the determinant of M (detM) requires a specific analysis, performed in this work by using the normal form of M, as well as the indices of polarimetric purity (IPP) of the canonical depolarizer associated with M. We derive an expression for detM in terms of the diattenuation, polarizance and a parameter proportional to the volume of the intrinsic ellipsoid of M. We likewise establish a relation existing between the determinant of M and the rank of the covariance matrix H associated with M, and determine the lower and upper bounds of detM for the two types of Mueller matrices by taking advantage of their geometric representation in the IPP space

Regional Differences in Heat Shock Protein 25 Expression in Brain and Spinal Cord Astrocytes of Wild-Type and SOD1 (G93A) Mice

Heterogeneity of glia in different CNS regions may contribute to the selective vulnerability of neuronal populations in neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS). Here, we explored regional variations in the expression of heat shock protein 25 in glia under conditions of acute and chronic stress. Hsp27 (Hsp27; murine orthologue: Hsp25) fulfils a number of cytoprotective functions and may therefore be a possible therapeutic target in ALS. We identified a subpopulation of astrocytes in primary murine mixed glial cultures that expressed Hsp25. Under basal conditions, the proportion of Hsp25-positive astrocytes was twice as high in spinal cord cultures than in cortical cultures. To explore the physiological role of the elevated Hsp25 expression in spinal cord astrocytes, we exposed cortical and spinal cord glia to acute stress, using heat stress and pro-inflammatory stimuli. Surprisingly, we observed no stress-induced increase in Hsp25 expression in either cortical or spinal cord astrocytes. Similarly, exposure to endogenous stress, as modelled in glial cultures from SOD1 G93A-ALS mice, did not increase Hsp25 expression above that observed in astrocytes from wild-type mice. In vivo, Hsp25 expression was greater under conditions of chronic stress present in the spinal cord of SOD1 G93A mice than in wild-type mice, although this increase in expression is likely to be due to the extensive gliosis that occurs in this model. Together, these results show that there are differences in the expression of Hsp25 in astrocytes in different regions of the central nervous system, but Hsp25 expression is not upregulated under acute or chronic stress conditions

Rapid flow cytometric measurement of protein inclusions and nuclear trafficking.

Proteinaceous cytoplasmic inclusions are an indicator of dysfunction in normal cellular proteostasis and a hallmark of many neurodegenerative diseases. We describe a simple and rapid new flow cytometry-based method to enumerate, characterise and, if desired, physically recover protein inclusions from cells. This technique can analyse and resolve a broad variety of inclusions differing in both size and protein composition, making it applicable to essentially any model of intracellular protein aggregation. The method also allows rapid quantification of the nuclear trafficking of fluorescently labelled molecules

Triassic tholeiitic dolerites («ophites») of the El Grado diapir (Pyrenees, Huesca, Spain): emplacement and composition

Mesozoic dolerites in the south Pyrenean sector of El Grado (Huesca, Spain) preserve emplacement structures (fluidity structures at the top and load structures at the base) developed during their intrusion into unconsolidated marly-evaporitic Triassic sediments (Keuper facies). By analogy with other dolerites in the south Pyrenean domain, their emplacement age is equivalent to the uppermost Keuper facies terms, but prior to the final Triassic-early Liassic carbonated sediments. Radiometric ages (187-197±7 Ma) show that the emplacement occurred during the lower Liassic. The petralogical differentiation from the chilled margin facies to the central facies, and also to the late pegmatitoids, is consistent with that obtained from major elements, trace elements and REE. Their tholeiitic affinity, as defined by their geochemical composition, is equivalent to that of similar racks in the Pyrenean domain. However, the rocks analyzed here, which are located at the external sector of this domain, display a greater petralogical and geochemical differentiation as compared to similar rocks in the central sectors of the Pyrenean domain.Las doleritas mesozoicas del sector surpirenaico de El Grado (Huesca) conservan estructuras de emplazamiento (con desarrollo del movimiento de lava fluida al techo y de carga en su base) desarrolladas al instruir en los sedimentos margo-evaporíticos en facies Keuper, todavía inconsolidados. Por similitud con otras doleritas del dominio surpirenaico, la edad del emplazamiento es equivalente a la de los términos superiores de la facies Keuper y previa a la sedimentación carbonatada del Trías terminal-Lías inferior. Las determinaciones de edades radiométricas (187-197±7 Ma) indican que el emplazamiento debió tener lugar durante el Lías inferior. La diferenciación petralógica, desde la facies del borde enfriado a la central y, también, al posterior diferenciado pegmatoide concuerda con la obtenida con elementos mayores, trazas y REE. Su afinidad toleítica, definida por su composición geoquímica, coincide con la obtenida en rocas análogas para el dominio pirenaico; no obstante, estas rocas situadas en el borde más externo de dicho dominio representan una mayor diferenciación (petralógica y geoquímica) respecto a la obtenida, hasta el momento, para rocas análogas situadas en sectores más centrales del citado dominio pirenaico

The triassic alkaline dolerites of the Valacloche-Camarena Area (SE-Iberian Chain, Teruel): Geodynamic implications

The dolerite sills outcropping in the Valacloche-Camarena area (SE Iberian Chain), are the expression of an alkaline magmatism, emplaced in Keuper facies sedimentary rocks. Their pre-Hettangian age is deduced from the development of fluidality structures at the top of the sills together with the very low grade contact metamorphism of the host rocks. A differentiation trend, represented by two rock-types, with variable Ti-augite content, is confirmed by geochemical data (REE). The alkaline composition of this magmatism is close to that of the OIB type. Crust-derived enclaves (metapelites and granitoids) are common in these sills, suggesting that magma ascent took place through a fracture system, related to a distensive tectonic regime, that affected different levels of the crust. This magmatism was one of the expressions of the triassic rifting events that are well represented in the SE border of the Iberian Chain.Un magmatismo alcalino, emplazado en sedimentos triásicos en facies Keuper, está bien representado en los sills doleríticos del área de Valacloche-Camarena (SE de la Cordillera Ibérica). La edad pre-Hettangiense ha sido deducida a partir de la presencia de estructuras de fluidalidad y de un metamorfismo de contacto de grado muy débil. Petrológicamente se identifica una fraccionación según dos litotipos (con contenido variable en Ti-augita) que está corroborada por los datos de composición geoquímica (en tierras raras); la composición alcalina de este magmatismo es próxima a la del tipo OIB. La presencia, frecuente, de enclaves de corteza (metapelitas y granitoides) indica una fracturación que, en condiciones distensivas, afectó a distintos niveles de dicha corteza. Este magmatismo está ligado al rifting triásico que está bien expresado en el borde SE de la Cordillera Ibérica

Catalytically Active Imine-based Covalent Organic Frameworks for Detoxification of Nerve Agent Simulants in Aqueous Media

A series of imine-based covalent organic frameworks decorated in their cavities with di erent alkynyl, pyrrolidine, and N-methylpyrrolidine functional groups have been synthetized. These materials exhibit catalytic activity in aqueous media for the hydrolytic detoxification of nerve agents, as exemplified with nerve gas simulant diisopropylfluorophosphate (DIFP). These preliminary results suggest imine-based covalent organic frameworks (COFs) as promising materials for detoxification of highly toxic molecules.MINECO (MAT2016-77608-C3-1-P and 2-P, CTQ2017-84692-R) and EU FEDER fundin

Heterometallic Titanium-Organic Frameworks as Dual Metal Catalysts for Synergistic Non-Buffered Hydrolysis of Nerve Agent Simulants

Heterometallic metal-organic frameworks (MOFs) can offer important advantages over their homometallic counterparts to enable targeted modification of their adsorption, structural response, electronic structure, or chemical reactivity. However, controlling metal distribution in these solids still remains a challenge. The family of mesoporous titanium-organic frameworks, MUV-101(M), displays heterometallic TiM2 nodes assembled from direct reaction of Ti(IV) and M(II) salts. We use the degradation of nerve agent simulants to demonstrate that only TiFe2 nodes are capable of catalytic degradation in non-buffered conditions. By using an integrative experimental-computational approach, we rationalize how the two metals influence each other, in this case, for a synergistic mechanism reminiscent of bimetallic enzymes. Our results highlight the importance of controlling metal distribution at an atomic level to span the interest of heterometallic MOFs to a broad scope of cascade or tandem reactions. Summary Mixed-metal or heterometallic metal-organic frameworks (MOFs) are gaining importance as a route to produce materials with increasing chemical and functional complexities. We report a family of heterometallic titanium frameworks, MUV-101(M), and use them to exemplify the advantages of controlling metal distribution across the framework in heterogeneous catalysis by exploring their activity toward the degradation of a nerve agent simulant of Sarin gas. MUV-101(Fe) is the only pristine MOF capable of catalytic degradation of diisopropyl-fluorophosphate (DIFP) in non-buffered aqueous media. This activity cannot be explained only by the association of two metals, but to their synergistic cooperation, to create a whole that is more efficient than the simple sum of its parts. Our simulations suggest a dual-metal mechanism reminiscent of bimetallic enzymes, where the combination of Ti(IV) Lewis acid and Fe(III)–OH Brönsted base sites leads to a lower energy barrier for more efficient degradation of DIFP in absence of a base.Financial support for this work was provided by the Marie Skłodowska-Curie Global Fellowships (749359-EnanSET, N.M.P) within the European Union research and innovation framework programme (2014-2020

Dynamics of localized structures in vector waves

Dynamical properties of topological defects in a twodimensional complex vector field are considered. These objects naturally arise in the study of polarized transverse light waves. Dynamics is modeled by a Vector Complex Ginzburg-Landau Equation with parameter values appropriate for linearly polarized laser emission. Creation and annihilation processes, and selforganization of defects in lattice structures, are described. We find "glassy" configurations dominated by vectorial defects and a melting process associated to topological-charge unbinding.Comment: 4 pages, 5 figures included in the text. To appear in Phys. Rev. Lett. (2000). Related material at http://www.imedea.uib.es/Nonlinear and http://www.imedea.uib.es/Photonics . In this new version, Fig. 3 has been replaced by a better on