4,258 research outputs found

    Generalized Derivations with Commutativity and Anti-commutativity Conditions

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    Let R be a prime ring with 1, with char(R) &#8800; 2; and let F : R &#8594; R be a generalized derivation. We determine when one of the following holds for all x,y &#8712; R: (i) [F(x); F(y)] = 0; (ii) F(x)&#927;F(y) = 0; (iii) F(x) &#927; F(y) = x &#927; y .</p

    Higgs Inflation, Quantum Smearing and the Tensor to Scalar Ratio

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    In cosmic inflation driven by a scalar gauge singlet field with a tree level Higgs potential, the scalar to tensor ratio r is estimated to be larger than 0.036, provided the scalar spectral index n_s >= 0.96. We discuss quantum smearing of these predictions arising from the inflaton couplings to other particles such as GUT scalars, and show that these corrections can significantly decrease r. However, for n_s >= 0.96, we obtain r >= 0.02 which can be tested by the Planck satellite.Comment: 10 pages, 3 figures and 3 table

    Iron(III)-catalyzed chlorination of activated arenes

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    A general and regioselective method for the chlorination of activated arenes has been developed. The transformation uses iron(III) triflimide as a powerful Lewis acid for the activation of N-chlorosuccinimide and the subsequent chlorination of a wide range of anisole, aniline, acetanilide and phenol derivatives. The reaction was utilized for the late-stage mono- and di-chlorination of a range of target compounds such as the natural product nitrofungin, the antibacterial agent chloroxylenol and the herbicide chloroxynil. The facile nature of this transformation was demonstrated with the development of one-pot tandem iron-catalyzed dihalogenation processes allowing highly regioselective formation of different carbon-halogen bonds. The synthetic utility of the resulting dihalogenated aryl compounds as building blocks was established with the synthesis of natural products and pharmaceutically relevant targets

    Analytical approaches to vibration analysis of circular, annular and sectorial plates subjected to classical and arbitrary boundary conditions – a literature survey

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    Plates are one of the most important structural components used in many industries like aerospace, marine and various other engineering fields and thus motivate designers and engineers to study the vibration characteristics of these structures. A lot of research work and studies have been done to study its vibration characteristics. This paper is a review of existing literature on vibration analysis of circular, annular and sector plates. The aim of this paper is to compile prominent studies related to circular, annular and sector plates subjected to classical and arbitrary boundary conditions under different supports and loadings. This review also identifies the analytical methods and approaches used to study the vibration characteristics of circular, annular and sector plates based on classical plate theories, Mindlin plate theory and higher order shear deformation theories. Few important citations related to functionally graded circular, annular and sector plates have also been included. Apart from helping researchers and engineers to identify relevant literature quickly and easily, this review will also help them to apply some of these analytical methods to study the vibration characteristics of other 2D and 3D built up and coupled structures

    Current Scenario of Environmental Pollution & Its Solution by Plantation In Changing Climate

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    Life’s quality is depending on quality of environment. As environment creates favorable surroundings for survival, growth and development of existing organisms. All living organisms are affected indirectly or directly due to environmental pollution. It is due to rapid increases in human being. Environmental pollution especially by anthropogenic activities is a main problem facing the world today and there is a need for increasing attentiveness that a clean and green environment is essential for better growth of living organisms in this changing climate of World. It is our top most priority to keep our country clean and green as cleanness is a part of our faith. Thus environmental pollution is causing great threat to plants, animals and to human all over the world. As each and every problem has a solution, because problem is always artificial, man desires to find the solution. In recent innovations there is a need to develop clean and green spaces within and around the polluted areas for existence of better environment. As some plants can act as pollution sink working as natural lungs. So,“the green revolution (Plantation) is the best solution to arrest the pollution”. If haphazard population growth goes on increasing without realizing the importance of trees especially those which act as pollution sink then there would be more critical changes for living organisms in near coming futur

    Diuretic, antidiuretic and laxative activities of Anthocleista vogelii extracts in rats

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    Background: Anthocleista vogelii Planch is a medicinal plant used by traditional healers in the treatment of Malaria, hypertension, ulcer, obesity, diabetes, and as a diuretic and purgative in Africa. Therefore, the present study sought to evaluate the diuretic, antidiuretic and laxative activities of the root bark of A. vogelii extracts and fractions in male Sprague-Dawley rats.Materials and methods: Sixty rats were placed in 10 groups which included: control (normal saline), furosemide/sodium picosulfate (25 mg/kg) as standard drugs, methanol extracts (250 mg/kg and 500 mg/kg), and 125 mg/kg and 250 mg/kg of saponin, flavonoid and neutral alkaloid fractions of A. vogelii. The drugs/extracts/fractions were administered orally using normal saline as the vehicle.Results: The 500 mg/kg methanol extracts (ME) significantly increased (p&lt;0.05) the urine volume and electrolytes (Na+, K+ and Cl-) excreted, while 125 mg/kg and 250 mg/kg flavonoid fraction (FF) decreased significantly (p&lt;0.05) urine volume and electrolytes (Na+, K+ and Cl-) excreted, but doses of saponin fraction (SF) and neutral alkaloid fraction (NAF) had no significant difference (p&lt;0.05) compared to the control after 5 hrs. ME, SF, NAF significantly increased (p&lt;0.05) the fecal output of the animals when compared to the control, while FF showed no significant difference (p&lt;0.05) after 8 hrs of administration.Conclusions: This study determined that ME revealed diuretic activity, although not remarkable to furosemide, while FF showed antidiuretic activity, and potent laxative activities were discovered in ME and SF of A. vogelii.Keywords: Anthocleista vogelii, Diuretic, Anti-Diuretic, Laxative, Traditional healer

    Prediction of Soil Macronutrients Using Machine Learning Algorithm

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    In this research work, machine learning algorithms were applied to find the relationship between independent variables and dependent variables for soil data analysis. The independent variables include moisture, temperature, soil pH, Cation Exchange Capacity(CEC) whereas, the dependent variables include Nitrogen, Phosphorus and Potassium (NPK). This research concludes relationships between Phosphorus, Potassium,&nbsp; soil pH and CEC; Nitrogen and soil moisture and temperature using machine learning(ML) algorithms so as to deduce NPK content of soil. A comparative analysis with obtained results from each ML method is also presented. Machine learning algorithms are best performed on data with multiple independent variables. The values computed for nitrogen relationship were more accurate than PK relationship values. The accuracy of data set I was less than data set II. A large data set would produce more accurate results for both data sets

    Automatic Detection of Aircraft Emergency Landing Sites

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    An automatic landing site detection algorithm is proposed for aircraft emergency landing. Emergency landing is an unplanned event in response to emergency situations. If, as is unfortunately usually the case, there is no airstrip or airfield that can be reached by the un-powered aircraft, a crash landing or ditching has to be carried out. Identifying a safe landing site is critical to the survival of passengers and crew. Conventionally, the pilot chooses the landing site visually by looking at the terrain through the cockpit. The success of this vital decision greatly depends on the external environmental factors that can impair human vision, and on the pilot\u27s flight experience that can vary significantly among pilots. Therefore, we propose a robust, reliable and efficient algorithm that is expected to alleviate the negative impact of these factors. We present only the detection mechanism of the proposed algorithm and assume that the image enhancement for increased visibility, and image stitching for a larger field-of-view have already been performed on the images acquired by aircraft-mounted cameras. Specifically, we describe an elastic bound detection method which is designed to position the horizon. The terrain image is divided into non-overlapping blocks which are then clustered according to a roughness measure. Adjacent smooth blocks are merged to form potential landing sites whose dimensions are measured with principal component analysis and geometric transformations. If the dimensions of the candidate region exceed the minimum requirement for safe landing, the potential landing site is considered a safe candidate and highlighted on the human machine interface. At the end, the pilot makes the final decision by confirming one of the candidates, also considering other factors such as wind speed and wind direction, etc. Preliminary results show the feasibility of the proposed algorithm
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