Imposing high-symmetry and tuneable geometry on lanthanide centres with chelating Pt and Pd metalloligands

Exploitation of HSAB preferences allows for high-yield, one-pot syntheses of lanthanide complexes chelated by two Pd or Pt metalloligands, [MII(SAc)4]2− (SAc− = thioacetate, M = Pd, Pt). The resulting complexes with 8 oxygen donors surrounding the lanthanides can be isolated in crystallographically tetragonal environments as either [NEt4]+ (space group: P4/mcc) or [PPh4]+ (space group: P4/n) salts. In the case of M = Pt, the complete series of lanthanide complexes has been structurally characterized as the [NEt4]+ salts (except for Ln = Pm), while the [PPh4]+ salts have been structurally characterized for Ln = Gd–Er, Y. For M = Pd, selected lanthanide complexes have been structurally characterized as both salts. The only significant structural difference between salts of the two counter ions is the resulting twist angle connecting tetragonal prismatic and tetragonal anti-prismatic configurations, with the [PPh4]+ salts approaching ideal D4d symmetry very closely (φ = 44.52–44.61°) while the [NEt4]+ salts exhibit intermediate twist angles in the interval φ = 17.28–27.41°, the twist increasing as the complete 4f series is traversed. Static magnetic properties for the latter half of the lanthanide series are found to agree well in the high temperature limit with the expected Curie behavior. Perpendicular and parallel mode EPR spectroscopy on randomly oriented powder samples and single crystals of the Gd complexes with respectively Pd- and Pt-based metalloligands demonstrate the nature of the platinum metal to strongly affect the spectra. Consistent parametrization of all of the EPR spectra reveals the main difference to stem from a large difference in the magnitude of the leading axial term, B02, this being almost four times larger for the Pt-based complexes as compared to the Pd analogues, indicating a direct Pt(5dz2)–Ln interaction and an arguable coordination number of 10 rather than 8. The parametrization of the EPR spectra also confirms that off-diagonal operators are associated with non-zero parameters for the [NEt4]+ salts, while only contributing minimally for the [PPh4]+ salts in which lanthanide coordination approximates D4d point group symmetry closely.LHD acknowledges support from NSF-CCT EMT 08-517. (08-517 - NSF-CCT EMT

Learning about analysts

We examine an analyst with career concerns making cheap talk recommendations to a sequence of traders, each of whom possesses private information concerning the analyst's ability. The recommendations of the analyst influence asset prices that are then used to evaluate the analyst. An endogeneity problem thus arises. In particular, if the reputation of the analyst is sufficiently high then an incompetent but strategic analyst is able to momentarily hide her type. An equilibrium in which the market eventually learns the analyst type always exists. However, under some conditions, an equilibrium also exists in which the incompetent analyst is able to hide her type forever

Who acquires information in dealer markets?

We study information acquisition in dealer markets. We first identify a one- sided strategic complementarity in information acquisition: the more informed traders are, the larger market makers’ gain from becoming informed. When quotes are observable, this effect in turn induces a strategic complementarity in information acquisition amongst market makers. We then derive the equilibrium pattern of information acquisition and examine the implications of our analysis for market liquidity and price discovery. We show that increasing the cost of information can decrease market liquidity and improve price discovery

Dynamic persuasion with outside information

A principal seeks to persuade an agent to accept an offer of uncertain value before a deadline expires. The principal can generate information, but exerts no control over exogenous outside information. The combined effect of the deadline and outside information creates incentives for the principal to keep uncertainty high in the first periods so as to persuade the agent close to the deadline. We characterize the equilibrium, compare it to the single-player decision problem in which exogenous outside information is the agent's only source of information, and examine the welfare implications of our analysis

Essays in information transmission

La tesis consiste en tres capítulos independientes de investigación en economía de la información. El primer capítulo estudia cómo el sesgo político se sostiene en un mercado de medios de comunicación. El segundo capítulo describe la realización de un experimento en el laboratorio en el cual investigo la utilización de recomendaciones sesgadas por determinados sujetos. El tercer capítulo busca vínculos entre dos diferentes formas de modelar heterogeneidad en juegos de transmisión de información, siendo: (i) preferencias no comunes y creencias comunes, o (ii) preferencias comunes y creencias no comunes. Se analiza cuándo y bajo qué circunstancias los dos tipos de modelos son equivalentes. El capítulo 1 da comienzo con la observación de que votantes frecuentemente se suscriben a medios de comunicación que tienen más sesgo político que ellos mismos. Primero, muestro que eso es natural en un mercado es decir: un monopolista siempre elegir a el sesgo máximo y a pesar de que la competencia ayudar a a disminuir el sesgo del mercado típicamente, no lo suprimirá por completo. En el caso límite de un mercado grande con competencia perfecta, el sesgo del mercado ser a exactamente igual al sesgo de los votantes. Estos resultados analizan el lado de la oferta del mercado. Añadimos a esto un análisis del lado de la demanda del mercado. Es posible, que los votantes demanden medios que son más sesgados que ellos mismos, bien porque tengan mucha confianza en sus ideas políticas o bien porque exista cierta incertidumbre sobre el sesgo de las medios. El capítulo 2 es una prueba experimental de cómo utilizamos consejos de otras personas que tienen un sesgo comparado con nosotros. Para ello, se les pide a los sujetos del experimento que estimen la probabilidad de sacar una bola negra de una caja que contiene 10 bolas que son o negras o blancas. La distribución de los colores es incierta. Cuando los sujetos toman el papel del Recibidor observan la estimación de otro sujeto (el Consejero) que tiene información privada sobre el contenido de la caja pero cuya estimación es sesgada. No obstante, es fácil ajustar la estimación para eliminar el sesgo. Encuentro que recibidores le dan más peso al consejo del consejero si el sesgo es pequeño aunque todos los consejeros son igualmente informativos a priori. Además, en una extensión les permito a los recibidores que elijan al consejero, sabiendo sólo el sesgo de ese. Los recibidores les dan más peso a los consejeros en este caso (comparado con el caso en el que los consejeros se asignan exógenamente) aunque, aquí como antes, todos los consejeros son igualmente informados a priori. Sin embargo, este efecto está sólo presente cuando recibidores eligen el consejero con menos sesgo. Interpreto el primer resultado como un tipo de homofilia - a los recibidores les gustan más los consejeros que son más similares a ellos - y el segundo resultado como un efecto de ilusión de control - los recibidores les dan más peso a consejeros cuando los pueden elegir. El capítulo 3 trata dos diferentes formas de modular la heterogeneidad entre jugadores en juegos de transmisión de información. Tales juegos normalmente se caracterizan por dos jugadores: un Recibidor (R) y un Consejero (S). S tiene información privada sobre el estado del mundo y le manda un mensaje a R que toma una acción que afecta a los dos. Hay dos fuentes de heterogeneidad: las preferencias y las creencias de los jugadores. En la mayoría de los casos los jugadores tienen o preferencias no comunes y creencias comunes (CB) o preferencias comunes y creencias no comunes (CP). El capítulo investiga bajo qué circunstancias un modelo del tipo CB tiene un modelo del tipo CP que es equivalente. Esto es importante por dos razones: Primero, la elección entre modelos del tipo CB y del tipo CP es a veces arbitraria en el sentido de que no hay ninguna intuición que favorezca al uno o al otro. En este caso, es importante comprender cuando los dos enfoques son equivalentes. Segundo, a un cuando una situación favorece a uno de los dos, es importante saber cómo el enfoque afecta los resultados. Dos modelos son equivalentes si cumplen dos condiciones: (i) Equivalencia de Elección, que implica que en el modelo CB tanto como en el modelo CP los jugadores eligen la misma acción condicionada en la información, y (ii) Equivalencia de Estrategia, que implica que en el modelo CB tanto como en el modelo CP los jugadores eligen la misma estrategia en equilibrio. Primero, investigo el caso de espacios de acciones y de estados del mundo que son discretos. Entonces, cualquier modelo CB siempre tiene un modelo CP equivalente si el espacio de estados es lo suficientemente grande comparado con el espacio de acciones. En el caso de que sean continuos los espacios identifico condiciones de su ciencia para que un modelo CB tenga un modelo CP equivalente. Por último, expongo que ni siquiera si los dos modelos son equivalentes según la definición empleada, no implica que otras propiedades sean iguales

Genetic transformation of Fusarium avenaceum by Agrobacterium tumefaciens mediated transformation and the development of a USER-Brick vector construction system

BACKGROUND: The plant pathogenic and saprophytic fungus Fusarium avenaceum causes considerable in-field and post-field losses worldwide due to its infections of a wide range of different crops. Despite its significant impact on the profitability of agriculture production and a desire to characterize the infection process at the molecular biological level, no genetic transformation protocol has yet been established for F. avenaceum. In the current study, it is shown that F. avenaceum can be efficiently transformed by Agrobacterium tumefaciens mediated transformation. In addition, an efficient and versatile single step vector construction strategy relying on Uracil Specific Excision Reagent (USER) Fusion cloning, is developed. RESULTS: The new vector construction system, termed USER-Brick, is based on a limited number of PCR amplified vector fragments (core USER-Bricks) which are combined with PCR generated fragments from the gene of interest. The system was found to have an assembly efficiency of 97% with up to six DNA fragments, based on the construction of 55 vectors targeting different polyketide synthase (PKS) and PKS associated transcription factor encoding genes in F. avenaceum. Subsequently, the ΔFaPKS3 vector was used for optimizing A. tumefaciens mediated transformation (ATMT) of F. avenaceum with respect to six variables. Acetosyringone concentration, co-culturing time, co-culturing temperature and fungal inoculum were found to significantly impact the transformation frequency. Following optimization, an average of 140 transformants per 10(6) macroconidia was obtained in experiments aimed at introducing targeted genome modifications. Targeted deletion of FaPKS6 (FA08709.2) in F. avenaceum showed that this gene is essential for biosynthesis of the polyketide/nonribosomal compound fusaristatin A. CONCLUSION: The new USER-Brick system is highly versatile by allowing for the reuse of a common set of building blocks to accommodate seven different types of genome modifications. New USER-Bricks with additional functionality can easily be added to the system by future users. The optimized protocol for ATMT of F. avenaceum represents the first reported targeted genome modification by double homologous recombination of this plant pathogen and will allow for future characterization of this fungus. Functional linkage of FaPKS6 to the production of the mycotoxin fusaristatin A serves as a first testimony to this

Effects of experimental conditions and of addition of natural minerals on syngas production from lignin by oxy-gasification: comparison of bench- and pilot scale gasification

Gasification of spent lignin pellets was used to obtain a gas suitable for energy production. Spent lignin was obtained from second-generation cellulosic ethanol demo plant using wheat straw as feedstock. Gasification of lignin did not give rise to any feeding problems, thus no significant changes were needed in the existing gasification installation. The rise of temperature and steam flow rate favoured the formation of H2, while hydrocarbons (CnHm) and tar contents decreased. The increase of equivalent ratio (ER) also decreased hydrocarbons and tar contents, but syngas higher heating value (HHV) was reduced. The use of natural minerals improved lignin gasification. The presence of dolomite led to the highest H2 and to the lowest CnHm and tar contents. Results obtained at bench-scale were confirmed at pilot-scale, as similar trends were obtained. However, as the residence time in pilot gasifier was higher, greater gas yields with higher H2 and CH4 concentrations were obtained, while tar contents decreased. After syngas hot cleaning and upgrading, the final syngas composition showed to be suitable for a wide range of applications (e.g. energy production and synthesis of chemicals), since it was substantially enriched in hydrogen, whereas tar and heavier gaseous hydrocarbons were completely destroyed

The Impact of Goiter and Thyroid Surgery on Goiter Related Esophageal Dysfunction. A Systematic Review

Background: Patients with goiter referred for thyroidectomy report swallowing difficulties. This might be associated with esophageal compression and deviation as this is present in a significant number of patients. Studies on how goiter and subsequently its treatment affect the esophagus are sparse and point in various directions. Our aim was to investigate, through a systematic review, the impact of goiter and thyroidectomy on esophageal anatomy, esophageal physiology, and subjective swallowing dysfunction.Methods: The search period covered 1 January 1975 to 1 July 2018, using the scientific databases PubMed and EMBASE. Inclusion criteria were adult patients with goiter who were either observed or underwent thyroidectomy. Search terms were variations of the terms for goiter, esophagus, swallowing, and dysphagia. From an initial 3,040 titles, 55 full text evaluations led to the final inclusion of 27 papers. Seventeen papers investigated, prospectively, the impact of thyroidectomy on the esophagus, while five observational and five retrospective studies were also included.Results: Esophageal anatomy impairment: Esophageal deviation occurred in 14% and esophageal compression in 8–27% of goiter patients. The prevalence increased with goiter size and with the extent of substernal extension. The smallest cross-sectional area of the esophagus increased by median 34% after thyroidectomy. Esophageal physiology changes: Goiter patients had increased esophageal transit time, positively correlated with goiter size, but unrelated to esophageal motility disturbances. Decrease in the upper esophageal sphincter pressure occurred early after surgery, and normalized within 6 months. Swallowing related patient-reported outcomes: Evaluated by validated questionnaires, swallowing symptoms worsened in the early period after thyroidectomy, but improved after 6 months, as compared to baseline.Conclusions: Thyroidectomy relieved patients with goiter from dysphagia, within 6 months of surgery probably via increase in the cross-sectional area of the esophagus. Attention to the impact by goiter on the esophagus is needed, and balanced and individualized information about the potential benefits and risks of thyroid surgery is crucial in the management of patients with goiter

Molecular Basis of Enhanced Activity in Factor VIIa-Trypsin Variants Conveys Insights into Tissue Factor-mediated Allosteric Regulation of Factor VIIa Activity

The complex of coagulation factor VIIa (FVIIa), a trypsin-like serine protease, and membrane-bound tissue factor (TF) initiates blood coagulation upon vascular injury. Binding of TF to FVIIa promotes allosteric conformational changes in the FVIIa protease domain and improves its catalytic properties. Extensive studies have revealed two putative pathways for this allosteric communication. Here we provide further details of this allosteric communication by investigating FVIIa loop swap variants containing the 170 loop of trypsin that display TF-independent enhanced activity. Using x-ray crystallography, we show that the introduced 170 loop from trypsin directly interacts with the FVIIa active site, stabilizing segment 215–217 and activation loop 3, leading to enhanced activity. Molecular dynamics simulations and novel fluorescence quenching studies support that segment 215–217 conformation is pivotal to the enhanced activity of the FVIIa variants. We speculate that the allosteric regulation of FVIIa activity by TF binding follows a similar path in conjunction with protease domain N terminus insertion, suggesting a more complete molecular basis of TF-mediated allosteric enhancement of FVIIa activity