Computation of (3)J(HH) coupling constants with a combination of density functional theory and semiempirical calculations. Application to complex molecules

This work evaluates the efficiency of economic levels of theory for the prediction of (3)J(HH) spin-spin coupling constants, to be used when robust electronic structure methods are prohibitive. To that purpose, DFT methods like mPW1PW91. B3LYP and PBEPBE were used to obtain coupling constants for a test set whose coupling constants are well known. Satisfactory results were obtained in most of cases, with the mPW1PW91/6-31G(d,p)//B3LYP/6-31G(d,p) leading the set. In a second step. B3LYP was replaced by the semiempirical methods PM6 and RM1 in the geometry optimizations. Coupling constants calculated with these latter structures were at least as good as the ones obtained by pure DFT methods. This is a promising result, because some of the main objectives of computational chemistry - low computational cost and time, allied to high performance and precision - were attained together. (C) 2012 Elsevier B.V. All rights reserved.

The wind profile in the atmospheric stable boundary layer over complex terrain and heterogeneous surfaces: limitations of local similarity theory

L'indagine ha riguardato il profilo del vento nei primi 30 metri dello strato limite atmosferico stabile nell'ambito della teoria di similarità locale. Ad oggi, diversi esperimenti hanno confermato la validità della teoria per strati-limite su terreni livellati e superfici omogenee. Tali condizioni ideali sono però infrequenti nella realtà ed è perciò importante capire quali siano i limiti della similarità locale per strati-limite su terreni complessi e superfici disomogenee. Entrambe le condizioni sono presenti a Ny-Alesund (Svalbard, Norvegia) dove il Consiglio Nazionale delle Ricerche (CNR), nel 2009, ha installato una torre di 30 m, la Amudsen-Nobile Climate Change Tower (CCT), per lo studio dello strato-limite artico. Il lavoro di tesi ha riguardato misure di vento e turbolenza acquisite sulla CCT da maggio 2012 a maggio 2014. Il confronto tra le velocità del vento misurate dagli anemometri installati sulla CCT, ha rivelato criticità nel dato sonico manifestatesi con sovrastime sistematiche e maggiore erraticità rispetto alle misure provenienti dagli anemometri a elica. Un test condotto fra diversi metodi per il calcolo dei gradienti verticali della velocità del vento ha rivelato scarsa sensibilità dei risultati ottenuti al particolare metodo utilizzato. Lo studio ha riguardato i gradienti verticali adimensionali della velocità del vento nei primi 30-m dello strato limite stabile. Deviazioni significative tra i tra le osservazioni e i valori predetti dalla similarità locale sono state osservate in particolare per i livelli più distanti dal suolo e per valori crescenti del parametro di stabilità z/L (L, lunghezza di Obukhov locale). In particolare, si sono osservati gradienti adimensionali inferiori a quelli predetti dalle più usate relazioni di flusso-gradiente. Tali deviazioni, presenti perlopiù per z/L>0.1, sono state associate ad un effetto di accentuazione della turbolenza da parte delle irregolarità del terreno. Per condizioni meno stabili, z/L<0.1, scarti positivi tra i gradienti osservati e quelli attesi sono stati attribuiti alla formazione di strati limite interni in condizioni di vento dal mare verso la costa. Sono stati proposti diversi metodi per la stima dell'effetto della self-correlazione nella derivazione delle relazioni di flusso-gradiente, dovuta alla condivisione della variabile u*. La formula per il coefficiente lineare di self correlazione e le sue distribuzioni di probabilità empiriche sono state derivate e hanno permesso di stimare il livello di self-correlazione presente nel dataset considerato.

Ruminant rhombencephalitis-associated Listeria monocytogenes alleles linked to a multilocus variable-number tandem-repeat analysis complex

Listeria monocytogenes is among the most important food-borne pathogens and is well adapted to persist in the environment. To gain insight into the genetic relatedness and potential virulence of L. monocytogenes strains causing central nervous system (CNS) infections, we used multilocus variable-number tandem-repeat analysis (MLVA) to subtype 183 L. monocytogenes isolates, most from ruminant rhombencephalitis and some from human patients, food, and the environment. Allelic-profile-based comparisons grouped L. monocytogenes strains mainly into three clonal complexes and linked single-locus variants (SLVs). Clonal complex A essentially consisted of isolates from human and ruminant brain samples. All but one rhombencephalitis isolate from cattle were located in clonal complex A. In contrast, food and environmental isolates mainly clustered into clonal complex C, and none was classified as clonal complex A. Isolates of the two main clonal complexes (A and C) obtained by MLVA were analyzed by PCR for the presence of 11 virulence-associated genes (prfA, actA, inlA, inlB, inlC, inlD, inlE, inlF, inlG, inlJ, and inlC2H). Virulence gene analysis revealed significant differences in the actA, inlF, inlG, and inlJ allelic profiles between clinical isolates (complex A) and nonclinical isolates (complex C). The association of particular alleles of actA, inlF, and newly described alleles of inlJ with isolates from CNS infections (particularly rhombencephalitis) suggests that these virulence genes participate in neurovirulence of L. monocytogenes. The overall absence of inlG in clinical complex A and its presence in complex C isolates suggests that the InlG protein is more relevant for the survival of L. monocytogenes in the environment.

Wide QRS-complex tachycardia with variable VA-conduction: what is the mechanism?

We describe the case of a 16-year-old woman with a surgically corrected tetralogy of Fallot presenting with recurrent wide-QRS-complex tachycardia. The tachycardia could be induced and terminated with ventricular stimulation only. QRS morphology during sinus rhythm and tachycardia was identical and variable VA-conduction was observed. Mapping of the tachycardia showed that variations of HH intervals preceded VV intervals. Therefore, a mechanism involving re-entry within the bundle branches was suggested. However, detailed mapping showed cranial to caudal depolarization of the His bundle, leading to the diagnosis of atrioventricular node re-entrant tachycardia. The tachycardia was abolished by radiofrequency catheter ablation of the slow AV nodal pathway. We conclude that variable VA conduction can occur in patients with atrioventricular node re-entrant tachycardia. The atrial tissue is not always an integral part of the re-entrant circuit.

Principal-Agent Theory and the World Trade Organization: Complex Agency and ‘Missing Delegation’

This paper analyses the World Trade Organization within a principal-agent framework. The concept of complex agency is introduced to focus on the variety of actors that comprise an international organization. Special attention is paid to the relationship between contracting parties’ representatives and the Secretariat. In the empirical part, the paper analyses the role of the Secretariat in assisting negotiations and presents evidence of declining influence. It is shown how principal-agent theory can contribute to addressing this ‘puzzle of missing delegation’. The paper concludes with a cautionary note as to the ‘location’ of international organizations’ emerging pathologies and calls for additional research to address the relationship between material and social sources to explain behaviour of the key actors within the complex agency.

Increased spread and replication efficiency of Listeria monocytogenes in organotypic brain-slices is related to multilocus variable number of tandem repeat analysis (MLVA) complex.

BACKGROUND Listeria (L.) monocytogenes causes fatal infections in many species including ruminants and humans. In ruminants, rhombencephalitis is the most prevalent form of listeriosis. Using multilocus variable number tandem repeat analysis (MLVA) we recently showed that L. monocytogenes isolates from ruminant rhombencephalitis cases are distributed over three genetic complexes (designated A, B and C). However, the majority of rhombencephalitis strains and virtually all those isolated from cattle cluster in MLVA complex A, indicating that strains of this complex may have increased neurotropism and neurovirulence. The aim of this study was to investigate whether ruminant rhombencephalitis strains have an increased ability to propagate in the bovine hippocampal brain-slice model and can be discriminated from strains of other sources. For this study, forty-seven strains were selected and assayed on brain-slice cultures, a bovine macrophage cell line (BoMac) and a human colorectal adenocarcinoma cell line (Caco-2). They were isolated from ruminant rhombencephalitis cases (n = 21) and other sources including the environment, food, human neurolisteriosis cases and ruminant/human non-encephalitic infection cases (n = 26). RESULTS All but one L. monocytogenes strain replicated in brain slices, irrespectively of the source of the isolate or MLVA complex. The replication of strains from MLVA complex A was increased in hippocampal brain-slice cultures compared to complex C. Immunofluorescence revealed that microglia are the main target cells for L. monocytogenes and that strains from MLVA complex A caused larger infection foci than strains from MLVA complex C. Additionally, they caused larger plaques in BoMac cells, but not CaCo-2 cells. CONCLUSIONS Our brain slice model data shows that all L. monocytogenes strains should be considered potentially neurovirulent. Secondly, encephalitis strains cannot be conclusively discriminated from non-encephalitis strains with the bovine organotypic brain slice model. The data indicates that MLVA complex A strains are particularly adept at establishing encephalitis possibly by virtue of their higher resistance to antibacterial defense mechanisms in microglia cells, the main target of L. monocytogenes.

Two intertidal, non-calcifying macroalgae (Palmaria palmata and Saccharina latissima) show complex and variable responses to short-term CO2 acidification

Ocean acidification, the result of increased dissolution of carbon dioxide (CO2) in seawater, is a leading subject of current research. The effects of acidification on non-calcifying macroalgae are, however, still unclear. The current study reports two 1-month studies using two different macroalgae, the red alga Palmaria palmata (Rhodophyta) and the kelp Saccharina latissima (Phaeophyta), exposed to control (pHNBS = 8.04) and increased (pHNBS = 7.82) levels of CO2-induced seawater acidification. The impacts of both increased acidification and time of exposure on net primary production (NPP), respiration (R), dimethylsulphoniopropionate (DMSP) concentrations, and algal growth have been assessed. In P. palmata, although NPP significantly increased during the testing period, it significantly decreased with acidification, whereas R showed a significant decrease with acidification only. S. latissima significantly increased NPP with acidification but not with time, and significantly increased R with both acidification and time, suggesting a concomitant increase in gross primary production. The DMSP concentrations of both species remained unchanged by either acidification or through time during the experimental period. In contrast, algal growth differed markedly between the two experiments, in that P. palmata showed very little growth throughout the experiment, while S. latissima showed substantial growth during the course of the study, with the latter showing a significant difference between the acidified and control treatments. These two experiments suggest that the study species used here were resistant to a short-term exposure to ocean acidification, with some of the differences seen between species possibly linked to different nutrient concentrations between the experiments.

Introduction to Coding Theory for Flow Equations of Complex Systems Models

The modeling of complex dynamic systems depends on the solution of a differential equations system. Some problems appear because we do not know the mathematical expressions of the said equations. Enough numerical data of the system variables are known. The authors, think that it is very important to establish a code between the different languages to let them codify and decodify information. Coding permits us to reduce the study of some objects to others. Mathematical expressions are used to model certain variables of the system are complex, so it is convenient to define an alphabet code determining the correspondence between these equations and words in the alphabet. In this paper the authors begin with the introduction to the coding and decoding of complex structural systems modeling.

Saint Mathew Law and Bonini Paradox in Textual Theory of Complex Models

The mathematical models of the complex reality are texts belonging to a certain literature that is written in a semi-formal language, denominated L(MT) by the authors whose laws linguistic mathematics have been previously defined. This text possesses linguistic entropy that is the reflection of the physical entropy of the processes of real world that said text describes. Through the temperature of information defined by Mandelbrot, the authors begin a text-reality thermodynamic theory that drives to the existence of information attractors, or highly structured point, settling down a heterogeneity of the space text, the same one that of ontologic space, completing the well-known law of Saint Mathew, of the General Theory of Systems and formulated by Margalef saying: “To the one that has more he will be given, and to the one that doesn't have he will even be removed it little that it possesses.

Syntactic and Semantic Relationships in Models of Complex Systems: An Ecological Case

In this paper, the authors extend and generalize the methodology based on the dynamics of systems with the use of differential equations as equations of state, allowing that first order transformed functions not only apply to the primitive or original variables, but also doing so to more complex expressions derived from them, and extending the rules that determine the generation of transformed superior to zero order (variable or primitive). Also, it is demonstrated that for all models of complex reality, there exists a complex model from the syntactic and semantic point of view. The theory is exemplified with a concrete model: MARIOLA model.

Cálculo del asiento elástico tridimensional de cimentaciones de rigidez variable en terrenos con una capa rígida inclinada

Las fórmulas basadas en la teoría de la elasticidad son ampliamente utilizadas para el cálculo de asientos de cimentaciones, ya que la totalidad de la normativa geotécnica recomienda su empleo. No obstante, estos métodos no cubren todas las situaciones geotécnicamente posibles ya que frecuentemente las condiciones geológicas son complejas. En este trabajo se analiza la influencia de la presencia de una capa rígida inclinada en los asientos elásticos de una cimentación superficial. Para ello se han resuelto 273 modelos tridimensionales no lineales de elementos finitos, variando los parámetros clave del problema: la inclinación y la profundidad de la capa rígida y la rigidez de la cimentación. Finalmente, se ha realizado un análisis estadístico de los resultados de los modelos y se ha propuesto una fórmula que puede ser utilizada en el cálculo de asientos por métodos elásticos, para tener en consideración la presencia de una capa rígida inclinada en profundidad.

Theory of functions of a real variable.

Mode of access: Internet.

Stair builders' guide; a treatise on the construction of straight flight, platform, cylindrical and eliptical [!] stairs, explaining the theory and practice so the average building mechanic may understand it, with examples of work ranging from the simplest to the most complex forms,

Mode of access: Internet.

A treatise on the integral calculus : containing the integration of explicit functions of one variable ; together with the theory of definite integrals and of elliptic functions /

Mode of access: Internet.