Exchangeable Claims Sizes in a Compound Poisson Type Proces

When dealing with risk models the typical assumption of independence among claim size distributions is not always satisfied. Here we consider the case when the claim sizes are exchangeable and study the implications when constructing aggregated claims through compound Poisson type processes. In par- ticular, exchangeability is achieved through conditional independence and using parametric and nonparametric measures for the conditioning distribution. A full Bayesian analysis of the proposed model is carried out to illustrate.Bayes nonparametrics, compound Poisson process, exchangeable claim process, exchangeable sequence, risk model.

The Evolution and Future Trends of Unsaturated Polyester Biocomposites: A Bibliometric Analysis

Unsaturated polyester resin (UPR) is one of the first commercialized polymer matrices for composites reinforced with glass fibers, but has remained popular to this day. To reduce their environmental impact, natural fibers have been used as reinforcements. Researchers all over the world are still interested in these composites, and numerous papers have been published in the last four decades. Using bibliometric analysis, this work provides compiled, structured, and relevant information about the evolution and current state of these materials. This first study on UPR biocomposites based on bibliometric analysis examined 531 published papers identified in the Scopus database from 1982 to July 2022. An analysis of the most active states, leading institutions, and leading authors is followed by the identification of key areas such as the most common natural fibers used as reinforcements, fiber treatments, and composite design parameters such as processing techniques; recently, composite testing; and technological applications. The findings emphasize the importance of staying active in this global field and provide information on novel promising topics for future research.This research was funded by Universidad Pontificia Bolivariana, grant number “692C-09/21-25” and “The Ministerio de Ciencia y Tecnología de Colombia” proyect name “Desarrollo de aplicaciones a partir del aprovechamiento de los subproductos de la cadena productiva del fique para la industria de alimentos, fitoterapeútica y cosmética.”, grant number 1210-903-86606

Retrospective Analysis of Emergency Department Ultrasound for Acute Appendicitis

OBJECTIVES: To determine whether emergency physicians (EPs) who have skills in the other applications of ultrasound can apply these in appendicitis diagnosis. METHODS: EPs did not have focused training in bedside ultrasound for appendicitis. We identified patients receiving an ED bedside ultrasound evaluation for appendicitis from our ultrasound log. Criterion reference was radiology ultrasound (RUS), CT scan, or pathology report. RESULTS: We performed 155 ED ultrasounds for appendicitis. There were 27/155 cases where the ED ultrasound was true positive and agreed with pathology (sensitivity = 39%, 95% CI 28 – 52%). In 42/155 (27%) the ED ultrasound was non-diagnostic (false negative) with pathology positive. In 77 cases the ED ultrasound was true negative with non-visualization of the appendix in concert with non-visualization by RUS or CT scan (specificity = 90%, 95% CI 81-95%). In nine cases (6%), ED ultrasound was falsely positive, compared to CT scan with surgical consult. CONCLUSION: ED ultrasound by EPs prior to focused appendicitis ultrasound training is insufficiently accurate

Early Response to Dehydration 7 Remodels Cell Membrane Lipid Composition During Cold Stress in Arabidopsis

Plants adjust to unfavorable conditions by altering physiological activities such as gene expression. Although previous studies have identified multiple stress-induced genes, the function of many genes during the stress responses remains unclear. Expression of ERD7 (Early Response to Dehydration 7) is induced in response to dehydration. Here, we show that ERD7 plays essential roles in both plant stress responses and development. In Arabidopsis, ERD7 protein accumulated under various stress conditions including exposure to low temperature. A triple mutant of Arabidopsis lacking ERD7 and two closely-related homologs had an embryonic lethal phenotype, whereas a mutant lacking the two homologs and one ERD7 allele had relatively round leaves, indicating that the ERD7 gene family has essential roles in development. Moreover, the importance of the ERD7 family in stress responses was evidenced by the susceptibility of the mutant lines to cold stress. ERD7 protein was found to bind to several, but not all, negatively charged phospholipids, and was associated with membranes. Lipid components and cold-induced reduction of PIP2 in the mutant line were altered relative to wild type. Furthermore, membranes from the mutant line had reduced fluidity. Taken together, ERD7 and its homologs are important for plant stress responses and development and associated with modification of membrane lipid composition

Climate driven life histories: the case of the Mediterranean Storm petrel

Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time

The effect of temperature and enzyme concentration in the transesterification process of synthetic microalgae oil

Throughout the world, the fossil fuel has supplied around the 80% of the energetic requirements, in Colombia alone 95.1% of energetic demand is made by the transportation sector solely, supplied by oil, kerosene, gasoline and diesel, this sector has an extremely small participation with biofuel of 3%, which is represented only by biodiesel. Microalgae had been proposed as biofactories with a remarkable third generation biofuels production. The culture of the microorganism comprehends interesting characteristics as countless environments where its natural growth could be replicated in fresh, salty and even sewage waters, with a higher growth rate and a higher oil production. The implementation of enzymes in the transesterification process have generated a good curiosity in the field, due to its mild reactions conditions, lesser energetic requirements, a high standard in the selection of the enzymes with the objective of avoiding the formation of soaps, creating in this way cleaner products and sub-products, in which the separation of the phases biodiesel/glycerol, give the possibility to recuperate the bio catalyzer and high output of reactions. However, the high volume of medium required to obtain lipids is one of the major drawbacks to test the viability of these enzymes. The present study aims to design an enzymatic transesterification process for the production of biodiesel form synthetic Chlorella oil. The synthetic oil was designed according to the lipid profile of C 16:0, C16:1, C18:0, C18:1, C18:2 and C18:3 from Chlorella spp CHL2 cultured on Bold Basal media under limited concentrations of NaNO3. The enzymatic transesterification efficiency was evaluated by the implementation of a 22 experimental factorial design (temperature and lipase concentration) under a 3: 1 molar ratio of alcohol:oil and a fixed reaction time of 6 hours. The obtained results show that, in order to obtain superior yields of biodiesel (>91%) the transesterification process must be carried out under temperature conditions close to 38°C and lipase concentrations of 5%

Formative Research to Design a Culturally-appropriate Cancer Clinical Trial Education Program to Increase Participation of African American and Latino Communities

Background: Addressing knowledge deficiencies about cancer clinical trials and biospecimen donation can potentially improve participation among racial and ethnic minorities. This paper describes the formative research process used to design a culturally-appropriate cancer clinical trials education program for African American and Latino communities. We characterized community member feedback and its integration into the program. Methods: We incorporated three engagement approaches into the formative research process to iteratively develop the program: including community-based organization (CBO) leaders as research team members, conducting focus groups and cognitive interviews with community members as reviewers/consultants, and interacting with two community advisory groups. An iterative-deductive approach was used to analyze focus group data. Qualitative data from advisory groups and community members were compiled and used to finalize the program. Results: Focus group themes were: 1) Community Perspectives on Overall Presentation; 2) Community Opinions and Questions on the Content of the Presentation; 3) Culturally Specific Issues to Participation in Cancer Clinical Trials; 4) Barriers to Clinical Trial Participation; and 5) Perspectives of Community Health Educators. Feedback was documented during reviews by scientific experts and community members with suggestions to ensure cultural appropriateness using peripheral, evidential, linguistic, sociocultural strategies, and constituent-involving. The final program consisted of two versions (English and Spanish) of a culturally-appropriate slide presentation with speaker notes and videos representing community member and researcher testimonials. Conclusions: Incorporating multiple community engagement approaches into formative research processes can facilitate the inclusion of multiple community perspectives and enhance the cultural-appropriateness of the programs designed to promote cancer clinical trial participation among African Americans and Latinos

Electrically-driven amplification of terahertz acoustic waves in graphene

In graphene devices, the electronic drift velocity can easily exceed the speed of sound in the material at moderate current biases. Under this condition, the electronic system can efficiently amplify acoustic phonons, leading to the exponential growth of sound waves in the direction of the carrier flow. Here, we demonstrate that such phonon amplification can significantly modify the electrical properties of graphene devices. We observe a super-linear growth of the resistivity in the direction of the carrier flow when the drift velocity exceeds the speed of sound, causing up to a 7 times increase over 8 micrometers. The resistance growth is observable for carrier densities away from the Dirac point and is enhanced at cryogenic temperatures. These observations are explained by a theoretical model for the electrical-amplification of acoustic phonons, which reach frequencies up to 2.2 terahertz with the nanoscale wavelength set by gate-tunable ~kF transitions across the Fermi surface. These findings offer a route to high-frequency on-chip sound generation and detection, which can be used to modulate and probe electronic physics in van der Waals heterostructures in the terahertz frequency range