450 research outputs found
Correct quantum chemistry in a minimal basis from effective Hamiltonians
We describe how to create ab-initio effective Hamiltonians that qualitatively
describe correct chemistry even when used with a minimal basis. The
Hamiltonians are obtained by folding correlation down from a large parent basis
into a small, or minimal, target basis, using the machinery of canonical
transformations. We demonstrate the quality of these effective Hamiltonians to
correctly capture a wide range of excited states in water, nitrogen, and
ethylene, and to describe ground and excited state bond-breaking in nitrogen
and the chromium dimer, all in small or minimal basis sets
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Overview of mathematical approaches used to model bacterial chemotaxis II: bacterial populations
We review the application of mathematical modeling to understanding the behavior of populations of chemotactic bacteria. The application of continuum mathematical models, in particular generalized Keller–Segel models, is discussed along with attempts to incorporate the microscale (individual) behavior on the macroscale, modeling the interaction between different species of bacteria, the interaction of bacteria with their environment, and methods used to obtain experimentally verified parameter values. We allude briefly to the role of modeling pattern formation in understanding collective behavior within bacterial populations. Various aspects of each model are discussed and areas for possible future research are postulated
Opening the black box of energy modelling: Strategies and lessons learned
The global energy system is undergoing a major transition, and in energy planning and decision-making across governments, industry and academia, models play a crucial role. Because of their policy relevance and contested nature, the transparency and open availability of energy models and data are of particular importance. Here we provide a practical how-to guide based on the collective experience of members of the Open Energy Modelling Initiative (Openmod). We discuss key steps to consider when opening code and data, including determining intellectual property ownership, choosing a licence and appropriate modelling languages, distributing code and data, and providing support and building communities. After illustrating these decisions with examples and lessons learned from the community, we conclude that even though individual researchers' choices are important, institutional changes are still also necessary for more openness and transparency in energy research
Alternatives to antibiotics-a pipeline portfolio review
Antibiotics have saved countless lives and enabled the development of modern medicine over the past 70 years. However, it is clear that the success of antibiotics might only have been temporary and we now expect a long-term and perhaps never-ending challenge to find new therapies to combat antibiotic-resistant bacteria. A broader approach to address bacterial infection is needed. In this Review, we discuss alternatives to antibiotics, which we defined as non-compound approaches (products other than classic antibacterial agents) that target bacteria or any approaches that target the host. The most advanced approaches are antibodies, probiotics, and vaccines in phase 2 and phase 3 trials. This first wave of alternatives to antibiotics will probably best serve as adjunctive or preventive therapies, which suggests that conventional antibiotics are still needed. Funding of more than £1·5 billion is needed over 10 years to test and develop these alternatives to antibiotics. Investment needs to be partnered with translational expertise and targeted to support the validation of these approaches in phase 2 trials, which would be a catalyst for active engagement and investment by the pharmaceutical and biotechnology industry. Only a sustained, concerted, and coordinated international effort will provide the solutions needed for the future.</p
A theoretical approach to spot active regions in antimicrobial proteins
Background: Much effort goes into identifying new antimicrobial compounds able to evade the increasing resistance of microorganisms to antibiotics. One strategy relies on antimicrobial peptides, either derived from fragments released by proteolytic cleavage of proteins or designed from known antimicrobial protein regions. Results: To identify these antimicrobial determinants, we developed a theoretical approach that predicts antimicrobial proteins from their amino acid sequence in addition to determining their antimicrobial regions. A bactericidal propensity index has been calculated for each amino acid, using the experimental data reported from a high-throughput screening assay as reference. Scanning profiles were performed for protein sequences and potentially active stretches were identified by the best selected threshold parameters. The method was corroborated against positive and negative datasets. This successful approach means that we can spot active sequences previously reported in the literature from experimental data for most of the antimicrobial proteins examined. Conclusion: The method presented can correctly identify antimicrobial proteins with an accuracy of 85% and a sensitivity of 90%. The method can also predict their key active regions, making this a tool for the design of new antimicrobial drugs
A Novel System for Transcutaneous Application of Carbon Dioxide Causing an “Artificial Bohr Effect” in the Human Body
BACKGROUND: Carbon dioxide (CO(2)) therapy refers to the transcutaneous administration of CO(2) for therapeutic purposes. This effect has been explained by an increase in the pressure of O(2) in tissues known as the Bohr effect. However, there have been no reports investigating the oxygen dissociation of haemoglobin (Hb) during transcutaneous application of CO(2)in vivo. In this study, we investigate whether the Bohr effect is caused by transcutaneous application of CO2 in human living body. METHODS: We used a novel system for transcutaneous application of CO(2) using pure CO(2) gas, hydrogel, and a plastic adaptor. The validity of the CO(2) hydrogel was confirmed in vitro using a measuring device for transcutaneous CO(2) absorption using rat skin. Next, we measured the pH change in the human triceps surae muscle during transcutaneous application of CO(2) using phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) in vivo. In addition, oxy- and deoxy-Hb concentrations were measured with near-infrared spectroscopy in the human arm with occulted blood flow to investigate O2 dissociation from Hb caused by transcutaneous application of CO(2). RESULTS: The rat skin experiment showed that CO(2) hydrogel enhanced CO(2) gas permeation through the rat skin. The intracellular pH of the triceps surae muscle decreased significantly 10 min. after transcutaneous application of CO(2). The NIRS data show the oxy-Hb concentration decreased significantly 4 min. after CO(2) application, and deoxy-Hb concentration increased significantly 2 min. after CO(2) application in the CO(2)-applied group compared to the control group. Oxy-Hb concentration significantly decreased while deoxy-Hb concentration significantly increased after transcutaneous CO(2) application. CONCLUSIONS: Our novel transcutaneous CO(2) application facilitated an O(2) dissociation from Hb in the human body, thus providing evidence of the Bohr effect in vivo
Using Intrinsic X-ray Absorption Spectral Differences To Identify and Map Peptides and Proteins
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