Ruin probability functions and severity of ruin as a statistical decision problem

ABSTRACT: It is known that the classical ruin function under exponential claim-size distribution depends on two parameters, which are referred to as the mean claim size and the relative security loading. These parameters are assumed to be unknown and random, thus, a loss function that measures the loss sustained by a decision-maker who takes as valid a ruin function which is not correct can be considered. By using squared error loss function and appropriate distribution function for these parameters, the issue of estimating the ruin function derives in a mixture procedure. Firstly, a bivariate distribution for mixing jointly the two parameters is considered, and second, different univariate distributions for mixing both parameters separately are examined. Consequently, a catalogue of ruin probability functions and severity of ruin, which are more flexible than the original one, are obtained. The methodology is also extended to the Pareto claim size distribution. Several numerical examples illustrate the performance of these functions.This research was funded by (EGD) [Ministerio de Economía y Competitividad, Spain] grant number [ECO2013–47092]; (EGD)[Ministerio de Economía, Industria y Competitividad. Agencia Estatal de Investigación] grant number [ECO2017–85577–P ]; (JMS) [(Ministerio de Economía, Industria y Competitividad. Agencia Estatal de Investigación] grant number [ECO2016-476203-C2-1-P]; (ECO), research partially carried out while Calderín-Ojeda visited ULPGC as part of his Special Study Program leave, University of Melbourne

Analysis of the distribution of HII regions in external galaxies. IV The new galaxy sample. Position and Inclination angles

We have compiled a new sample of galaxies with published catalogs of HII region coordinates. This sample, together with the former catalog of Garcia-Gomez and Athanassoula (1991) will form the basis for subsequent studies of the spiral structure in disc galaxies. In this paper we address the problem of the deprojection of the galaxy images. For this purpose we use two deprojection methods based on the HII region distribution and compare the results with the values found in the literature using other deprojection methods. Taking into account the results of all the methods, we propose optimum values for the position and inclination angles of all the galaxies in our sample.Comment: TeX file with 16 postscript figure

Influences of salinity on the physiology and distribution of the Arctic coralline algae, Lithothamnion glaciale (Corallinales, Rhodophyta)

In Greenland, free-living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthåbsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured in situ during summers of 2015 and 2016, and annual patterns of productivity in L. glaciale were monitored in laboratory-based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold-room measurements indicate that both L. glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 ± 0.17 or 0.002 ± 0.023 μmol CaCO3 · g-1 · h-1 and -0.007 ±0.003 or -0.004 ± 0.001 mg O2 · L-1 · h-1 in each species respectively. Mesocosm experiments indicate L. glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L. glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 ± 1.73 mg · d-1 of biomass through summer. These results indicate high freshwater input to the Godthåbsfjord region may drive the low abundance of L. glaciale, and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.Peer reviewedFinal Accepted Versio

Who fans the flames of Alzheimer's disease brains? Misfolded tau on the crossroad of neurodegenerative and inflammatory pathways

Neurodegeneration, induced by misfolded tau protein, and neuroinflammation, driven by glial cells, represent the salient features of Alzheimer's disease (AD) and related human tauopathies. While tau neurodegeneration significantly correlates with disease progression, brain inflammation seems to be an important factor in regulating the resistance or susceptibility to AD neurodegeneration. Previously, it has been shown that there is a reciprocal relationship between the local inflammatory response and neurofibrillary lesions. Numerous independent studies have reported that inflammatory responses may contribute to the development of tau pathology and thus accelerate the course of disease. It has been shown that various cytokines can significantly affect the functional and structural properties of intracellular tau. Notwithstanding, anti-inflammatory approaches have not unequivocally demonstrated that inhibition of the brain immune response can lead to reduction of neurofibrillary lesions. On the other hand, our recent data show that misfolded tau could represent a trigger for microglial activation, suggesting the dual role of misfolded tau in the Alzheimer's disease inflammatory cascade. On the basis of current knowledge, we can conclude that misfolded tau is located at the crossroad of the neurodegenerative and neuroinflammatory pathways. Thus disease-modified tau represents an important target for potential therapeutic strategies for patients with Alzheimer's disease

Metabolomics for bioactivity assessment of natural products.

Natural products historically have been a rich source of lead molecules in drug discovery, based on their capability to create unique and diverse chemical structures. However, it is also true that the vast number of metabolites typically present in natural products and their huge dynamic range results in the loss of many possibly bioactive natural compounds, becoming an inextricable obstacle for drug development. Recently, new strategies which favour a holistic approach as opposed to the traditional reductionist methods used previously, have been introduced with the purpose of overcoming the bottlenecks in natural product research. This approach is based on the application of new technologies, including metabolomics, for example. Metabolomics allows a systematic study of a complex mixture such as a phytochemical preparation, which can be linked to observations obtained through biological testing systems without the need for isolating active principles. This may put drug discovery from natural products back in the limelight again. In this review paper, the description of some examples of successful metabolomics applications in several important fields related to drug discovery from natural sources aims at raising the potential of metabolomics in reducing the gap between natural products (NP) and modern drug discovery demand

Di-Zinc-Aryl Complexes: CO2 Insertions and Applications in Polymerisation Catalysis

Two new di-zinc aryl complexes, [LZn2Ph2] and [LZn2(C6F5)2], coordinated by a diphenol tetraamine macrocyclic ligand are prepared and fully characterized, including by single crystal X-ray diffraction experiments. The complexes’ reactivities with monomers including carbon dioxide, cyclohexene oxide, phthalic anhydride, iso-propanol and phenol are investigated using both experimental studies and density functional theory calculations. In particular, [LZn2Ph2] readily inserts carbon dioxide to form a carboxylate, at 1 bar pressure, whereas [LZn2(C6F5)2] does not react. Under these conditions [LZn2Ph2] shows moderate activity in the ring-opening copolymerisation of cyclohexene oxide / carbon dioxide (TOF = 20 h-1); cyclohexene oxide / phthalic anhydride (TOF = 33 h-1) and the ring opening polymerisations of rac-lactide (TOF = 99 h-1) and ε-caprolactone (TOF = 5280 h-1)

LRR Conservation Mapping to Predict Functional Sites within Protein Leucine-Rich Repeat Domains

Computational prediction of protein functional sites can be a critical first step for analysis of large or complex proteins. Contemporary methods often require several homologous sequences and/or a known protein structure, but these resources are not available for many proteins. Leucine-rich repeats (LRRs) are ligand interaction domains found in numerous proteins across all taxonomic kingdoms, including immune system receptors in plants and animals. We devised Repeat Conservation Mapping (RCM), a computational method that predicts functional sites of LRR domains. RCM utilizes two or more homologous sequences and a generic representation of the LRR structure to identify conserved or diversified patches of amino acids on the predicted surface of the LRR. RCM was validated using solved LRR+ligand structures from multiple taxa, identifying ligand interaction sites. RCM was then used for de novo dissection of two plant microbe-associated molecular pattern (MAMP) receptors, EF-TU RECEPTOR (EFR) and FLAGELLIN-SENSING 2 (FLS2). In vivo testing of Arabidopsis thaliana EFR and FLS2 receptors mutagenized at sites identified by RCM demonstrated previously unknown functional sites. The RCM predictions for EFR, FLS2 and a third plant LRR protein, PGIP, compared favorably to predictions from ODA (optimal docking area), Consurf, and PAML (positive selection) analyses, but RCM also made valid functional site predictions not available from these other bioinformatic approaches. RCM analyses can be conducted with any LRR-containing proteins at www.plantpath.wisc.edu/RCM, and the approach should be modifiable for use with other types of repeat protein domains

Active liquid crystal tuning of metallic nanoantenna enhanced light emission from colloidal quantum dots

A system comprising an aluminum nanoantenna array on top of a luminescent colloidal quantum dot waveguide and covered by a thermotropic liquid crystal (LC) is introduced. By heating the LC above its critical temperature, we demonstrate that the concomitant refractive index change modifies the hybrid plasmonic-photonic resonances in the system. This enables active control of the spectrum and directionality of the narrow-band (similar to 6 nm) enhancement of quantum dot photoluminescence by the metallic nanoantennas

Comparative analysis of Neph gene expression in mouse and chicken development

Neph proteins are evolutionarily conserved members of the immunoglobulin superfamily of adhesion proteins and regulate morphogenesis and patterning of different tissues. They share a common protein structure consisting of extracellular immunoglobulin-like domains, a transmembrane region, and a carboxyl terminal cytoplasmic tail required for signaling. Neph orthologs have been widely characterized in invertebrates where they mediate such diverse processes as neural development, synaptogenesis, or myoblast fusion. Vertebrate Neph proteins have been described first at the glomerular filtration barrier of the kidney. Recently, there has been accumulating evidence suggesting a function of Neph proteins also outside the kidney. Here we demonstrate that Neph1, Neph2, and Neph3 are expressed differentially in various tissues during ontogenesis in mouse and chicken. Neph1 and Neph2 were found to be amply expressed in the central nervous system while Neph3 expression remained localized to the cerebellum anlage and the spinal cord. Outside the nervous system, Neph mRNAs were also differentially expressed in branchial arches, somites, heart, lung bud, and apical ectodermal ridge. Our findings support the concept that vertebrate Neph proteins, similarly to their Drosophila and C. elegans orthologs, provide guidance cues for cell recognition and tissue patterning in various organs which may open interesting perspectives for future research on Neph1-3 controlled morphogenesis