794 research outputs found

    On the Energetics of the HCO+^+ + C \to CH+^+ + CO Reaction and Some Astrochemical Implications

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    We explore the energetics of the titular reaction, which current astrochemical databases consider open at typical dense molecular (i.e., dark) cloud conditions. As is common for reactions involving the transfer of light particles, we assume that there are no intersystem crossings of the potential energy surfaces involved. In the absence of any such crossings, we find that this reaction is endoergic and will be suppressed at dark cloud temperatures. Updating accordingly a generic astrochemical model for dark clouds changes the predicted gas-phase abundances of 224 species by greater than a factor of 2. Of these species, 43 have been observed in the interstellar medium. Our findings demonstrate the astrochemical importance of determining the role of intersystem crossings, if any, in the titular reaction.Comment: Accepted for publication in ApJ; 14 pages, 2 figures, and 1 tabl

    Parametrized post-Newtonian virial theorem

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    Using the parametrized post-Newtonian equations of hydrodynamics, we derive the tensor form of the parametrized post-Newtonian virial theorem.Comment: 10 pages, submitted to CQ

    Review on Master Patient Index

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    In today's health care establishments there is a great diversity of information systems. Each with different specificities and capacities, proprietary communication methods, and hardly allow scalability. This set of characteristics hinders the interoperability of all these systems, in the search for the good of the patient. It is vulgar that, when we look at all the databases of each of these information systems, we come across different registers that refer to the same person; records with insufficient data; records with erroneous data due to errors or misunderstandings when inserting patient data; and records with outdated data. These problems cause duplicity, incoherence, discontinuation and dispersion in patient data. With the intention of minimizing these problems that the concept of a Master Patient Index is necessary. A Master Patient Index proposes a centralized repository, which indexes all patient records of a given set of information systems. Which is composed of a set of demographic data sufficient to unambiguously identify a person and a list of identifiers that identify the various records that the patient has in the repositories of each information system. This solution allows for synchronization between all the actors, minimizing incoherence, out datedness, lack of data, and a decrease in duplicate registrations. The Master Patient Index is an asset to patients, the medical staff and health care providers

    Custodial Isospin Violation in the Lee-Wick Standard Model

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    We analyze the tension between naturalness and isospin violation in the Lee-Wick Standard Model (LW SM), by computing tree-level and fermionic one-loop contributions to the post-LEP electroweak parameters and the Zbb coupling. The model is most natural when the LW partners of the gauge bosons and fermions are light, but small partner masses can lead to large isospin violation. The post-LEP parameters yield a simple picture in the LW SM: the gauge sector contributes to Y and W only, with leading contributions arising at tree-level, while the fermion sector contributes to S-hat and T-hat only, with leading corrections arising at one loop. Hence, W and Y constrain the masses of the LW gauge bosons to satisfy M1, M2 > 2.4 TeV at 95% CL. Likewise, experimental limits on T-hat reveal that the masses of the LW fermions must satisfy Mq, Mt > 1.6 TeV at 95% CL if the Higgs mass is light and tend to exclude the LW SM for any LW fermion masses if the Higgs mass is heavy. Contributions from the top-quark sector to the Zbb coupling can be even more stringent, placing a lower bound of 4 TeV on the LW fermion masses at 95% CL.Comment: 16 pages, 8 embedded eps figure

    Classification of resources in an e-library using machine learning algorithms

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    Library is the heart of a university and students spend a large amount of time in library in search of knowledge. The trend of reading resources in printed materials such as books, journals and other research publications is gradually changing. Since it is an uneasy and time-consuming process, students are interested in soft materials such as e-journals, e books and other web based resources. Nowadays, in a library most of the resources in digital form are stored without any classification. They are not categorized or utilized by the users since it does not have any proper way to access or find appropriate material when the users' queries applied. Even though there are a lot of manual ways to access text based materials or resources in a library, they cannot be applied to the digital resources since it needs some kind of text mining and machine learning. This project addresses this issue through a closed domain question answering system for a resource pool in an e-library. As the initial step, the project uses a narrowed down search space by processing the abstracts of the resources. More than 300 abstracts are extracted along with their title and pre-processed. 75% of the data are used as training sets and the remaining are used for testing. Different machine learning techniques such as classification and clustering are applied with this large collection of textual data using Weikato Environment of Knowledge Analysis (WEKA) and their performance metrics and error rates were compared. The most suitable machine learning technique and the mode of testing for the textual data were selected and applied for training models as the solution for the classification problem of the electronic resources
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