Dispersion measures as immunization risk measures

The quadratic and linear cash flow dispersion measures M2 and Ñ are two immunization risk measures designed to build immunized bond portfolios. This paper generalizes these two measures by showing that any dispersion measure is an immunization risk measure and therefore, it sets up a tool to be used in empirical testing. Each new measure is derived from a different set of shocks (changes on the term structure of interest rates) and depends on the corresponding subset of worst shocks. Consequently, a criterion for choosing appropriate immunization risk measures is to take those developed from the most reasonable sets of shocks and the associated subset of worst shocks and then select those that work best empirically. Adopting this approach, this paper then explores both numerical examples and a short empirical study on the Spanish Bond Market in the mid-1990s to show that measures between linear and quadratic are the most appropriate, and amongst them, the linear measure has the best properties. This confirms previous studies on US and Canadian markets that maturity-constrained-duration-matched portfolios also have good empirical behavior.Publicad

A single serine residue determines selectivity to monovalent metal ions in metalloregulators of the MerR family

MerR metalloregulators alleviate toxicity caused by an excess of metal ions, such as copper, zinc, mercury, lead, cadmium, silver, or gold, by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion by using two conserved cysteine residues at the C-terminal metal-binding loop (MBL). Divalent metal ion sensors, such as MerR and ZntR, require a third cysteine residue, located at the beginning of the dimerization (α5) helix, for metal coordination, while monovalent metal ion sensors, such as CueR and GolS, have a serine residue at this position. This serine residue was proposed to provide hydrophobic and steric restrictions to privilege the binding of monovalent metal ions. Here we show that the presence of alanine at this position does not modify the activation pattern of monovalent metal sensors. In contrast, GolS or CueR mutant sensors with a substitution of cysteine for the serine residue respond to monovalent metal ions or Hg(II) with high sensitivities. Furthermore, in a mutant deleted of the Zn(II) exporter ZntA, they also trigger the expression of their target genes in response to either Zn(II), Cd(II), Pb(II), or Co(II).Fil: Ibáñez, María Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Checa, Susana Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Soncini, Fernando Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Shape-Adaptability and Redox-Switching Properties of a Di-Gold Metallotweezer

The use of a carbazolyl-connected di-gold(I) metallotweezer for the encapsulation of several electron-poor organic substrates, and a planar Au(III) complex containing a CNC pincer ligand, is described. The binding affinity of the receptor depends on the electron-deficient character of the planar guest, with larger association constants found for the more electron-poor guests. The X-ray diffraction molecular structures of two host:guest adducts show that the host approaches its arms in order to facilitate the optimum interaction with the surface of the planar guests, in a clear example of an guest-induced fit conformational arrangement. The electrochemical studies of the encapsulation of N,N’-dimethyl-naphthalenetetracarboxy diimide (NTCDI) show that the redox active guest is released from the receptor upon one electron reduction, thus constituting an example of redox-switchable binding.Funding for open access charge: CRUE-Universitat Jaume

Dimensional Matching versus Induced‐Fit Distortions: Binding Affinities of Planar and Curved Polyaromatic Hydrocarbons with a Tetragold Metallorectangle

This is the peer reviewed version of the following article: Dimensional Matching versus Induced‐Fit Distortions: Binding Affinities of Planar and Curved Polyaromatic Hydrocarbons with a Tetragold Metallorectangle, which has been published in final form at https://doi.org/10.1002/anie.201915401. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.A tetragold(I) rectangle‐like metallocage containing two pyrene‐bis‐imidazolylidene ligands and two carbazolyl‐bis‐alkynyl linkers is used for the encapsulation of a series of polycyclic aromatic hydrocarbons (PAHs), including corannulene. The binding affinities obtained for the encapsulation of the planar PAHs guests in CD2Cl2 are found to exponentially increase with the number of π‐electrons of the guest (1.3 > logK >6.6). For the bowl‐shaped molecule of corannulene, the association constant is much lower than the expected one according to its number of electrons. The molecular structure of the host–guest complex formed with corannulene shows that the molecule of the guest is compressed, while the host is expanded, thus showing an interesting case of artificial mutual induced‐fit arrangement

Interpretability of deep learning methods in carotid artery image classification and semantic segmentation

Treballs finals del Màster de Fonaments de Ciència de Dades, Facultat de matemàtiques, Universitat de Barcelona, Any: 2020, Tutor: Laura Igual Muñoz[en] Medical imagery is arguably one of the clearest use cases for Deep Neural Networks: automatic detection of illnesses as an additional guidance tool could massively help doctors in their everyday work. However, the nature of the field makes errors extremely costly. That means that understanding the reasons for the decisions made by any Deep Learning model is absolutely crucial to its implementation and use. Previous work has demonstrated the effectiveness of Deep Learning methods applied to the detection of atherosclerotic plaques in carotid arteries. These are a known factor in cardio-vascular diseases, and can be identified by measuring Intima Media Thickness (IMT). To the best of our knowledge, these effective models, such as CNNs, VGG and Tiramisu (U-Net type), have not been studied under the lens of interpretability in this context. Our goal is to study the classification and segmentation decisions from the models in order to determine how they were taken, and if they make sense when compared to medical knowledge. For this purpose, we propose to use previously studied interpretability techniques, mainly Grid Saliency and the well-documented SHAP values, both of which are adapted to Deep Learning models. Indeed, both of these methods attempt to study local decisions from the models, while having the advantage of being model agnostic and visual in the representation. This makes them easy to understand in general with minimal explanations, a clear advantage when one of the goals is to help medical personnel, as well as data scientists, in making better and faster decisions. This study is applied to a dataset of ultrasound images, REGICOR. This work is framed within a larger research project within the UB, which has already spawned various works. This makes the dataset well suited for the purpose of interpreting the results from our models

Micro-scale Experiments in the Increasingly Fashionable Laboratory in High Schools

Objective: Experimental activities in laboratories are an important part in teaching and learning chemistry. Nevertheless, its implementation may be limited by the lack of material, instrument and above all the risk involved in doing so in the laboratory. Not only because of the cost of the reagents, but also because of the safety of the students in the classroom. That is why the use of simple micro-scale experiments turns out to be a benefit for the teaching of chemistry to high school students. Methods: Micro-scale practices also facilitate the implantation of constructivist laboratory practices, presented as small investigations, displacing traditional laboratory practices. The design of practices from a constructivist approach allows working all or some aspects of the scientific method. A constructivist methodology will increase the student’s interest in the subject and bring them closer to the scientific method, which will provoke the development of their observation capacity, the ability to make hypotheses, the skill in the design of experimental setups, discussing results, drawing conclusions and relating empirical data to theoretical principles. In contrast, traditional practices are usually prescription-type practices completely lack the scientific method. Since there are numerous difficulties in implementing practices with a constructivist methodology, both methods may be considered according to the space, time, and materials possibilities. Conclusion: The micro-scale experiments is useful for different reasons: reduces chemical use by promoting waste reduction of the source, save money, improves safety, may be carry out in class and sometimes at home, decreases experiment time and student carry out the experiments by themselves which is important for a significant learning

Mono and dimetallic pyrene-imidazolylidene complexes of iridium (III) for the deuteration of organic substrates and the C-C coupling of alcohols

Three different Ir(III) complexes with pyrene-containing N-heterocyclic carbenes have been prepared and characterized. Two complexes contain a monodentate pyrene-imidazolylidene ligand, and have the formulae [IrCp*Cl2(pyrene-NHC)] and [IrCp*(CO3)(pyrene-NHC)]. The third complex is a dimetallic complex with a pyrene-di-imidazolylidene bridging ligand, with the formula [{IrCp*(CO3)}2(μ-pyrene-di-NHC)]. The catalytic activity of the three complexes was tested in the H/D exchange of organic substrates, and in the β-alkylation of 1-phenylethanol with primary alcohols. In the deuteration of organic substrates, the carbonate complexes are active even in the absence of additives. The dimetallic complex is the most active one in the catalytic coupling of alcohols, a result that may be interpreted as a consequence of the cooperativity between the two metal centres.We gratefully acknowledge financial support from the MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02, P11B2015-24

Cation-Driven Self-Assembly of a Gold(I)-Based Metallo-Tweezer

A combination of self-complementary pi-pi-stacking interactions and metallophilic interactions triggered the self-assembly of a new digold(I) metallo-tweezer in the presence of several types of M+ ions. Titrations by fluorescence spectroscopy enabled the determination of the association constants of the resulting inclusion duplex complexes

A D3h-symmetry hexaazatriphenylene-tris-N-heterocyclic carbene ligand and its coordination to iridium and gold: preliminary catalytic studies

A new D3h-symmetry tris-N-heterocyclic carbene ligand has been prepared and coordinated to iridium and gold. The ligand contains an electron-poor hexaazatriphenylene core; thus, the resulting tris-NHC ligand is a poor electron donor. The tris–Au(I) complex was tested in the hydroamination of terminal alkynes and in the three-component Strecker reaction.We gratefully acknowledge financial support from MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02 and P11B2015-24). We are grateful to the Serveis Centrals d’Instrumentació Científica (SCIC-UJI) for providing the spectroscopic facilities

The Complex Coordination Landscape of a Digold(I) U‐Shaped Metalloligand

Dedicated to Bob Crabtree on the occasion of his 70th birthdayA U‐shaped di‐gold metallotweezer with two pyrene‐imidazolylidene edges and a xanthenyl‐bis‐alkynyl connector was prepared. This metallotweezer acts as metalloligand in the presence of Cu+, Tl+, or Ag+, showing three clearly distinct coordination patterns depending on the cation used. The coordination to Cu+ leads to a complex in which the metalloligand is coordinated in a pincer form. The reaction with Tl+ affords a complex in which the ligand is acting as a ϰ2‐(trans)‐chelate ligand. The reaction with Ag+ leads to a self‐assembled structure, with two silver cations encased inside the cavity of a duplex structure formed by two self‐assembled metallotweezers