Commutators and Anti-Commutators of Idempotents in Rings

We show that a ring $\,R\,$ has two idempotents $\,e,e'\,$ with an invertible commutator $\,ee'-e'e\,$ if and only if $\,R \cong {\mathbb M}_2(S)\,$ for a ring $\,S\,$ in which $\,1\,$ is a sum of two units. In this case, the "anti-commutator" $\,ee'+e'e\,$ is automatically invertible, so we study also the broader class of rings having such an invertible anti-commutator. Simple artinian rings $\,R\,$ (along with other related classes of matrix rings) with one of the above properties are completely determined. In this study, we also arrive at various new criteria for {\it general\} $\,2\times 2\,$ matrix rings. For instance, $R\,$ is such a matrix ring if and only if it has an invertible commutator $\,er-re\,$ where $\,e^2=e$.Comment: 21 page

Foundations of mechanism design: a tutorial Part 1- Key concepts and classical results

Mechanism design, an important tool in microeconomics, has found widespread applications in modelling and solving decentralized design problems in many branches of engineering, notably computer science, electronic commerce, and network economics. Mechanism design is concerned with settings where a social planner faces the problem of aggregating the announced preferences of multiple agents into a collective decision when the agents exhibit strategic behaviour. The objective of this paper is to provide a tutorial introduction to the foundations and key results in mechanism design theory. The paper is in two parts. Part 1 focuses on basic concepts and classical results which form the foundation of mechanism design theory. Part 2 presents key advanced concepts and deeper results in mechanism design

IMPROVED KERNEL FUZZY ADAPTIVE THRESHOLD ALGORITHM ON LEVEL SET METHOD FOR IMAGE SEGMENTATION

Using thresholding method to segment an image, a fixed threshold is not suitable if the background is rough Here, we propose a new adaptive thresholding method using level set theory. The method requires only one parameter to be selected and the adaptive threshold surface can be found automatically from the original image. An adaptive thresholding scheme using adaptive tracking and morphological filtering. The Improved Kernel fuzzy c-means (IKFCM) was used to generate an initial contour curve which overcomes leaking at the boundary during the curve propagation. IKFCM algorithm computes the fuzzy membership values for each pixel. On the basis of IKFCM the edge indicator function was redefined. Using the edge indicator function of a image was performed to extract the boundaries of objects on the basis of the presegmentation. Therefore, the proposed method is computationally efficient. Our method is good for detecting large and small images concurrently. It is also efficient to denoise and enhance the responses of images with low local contrast can be detected. The efficiency and accuracy of the algorithm is demonstrated by the experiments on the images. The above process of segmentation showed a considerable improvement in the evolution of the level set function

Query Recommender System Using Hierarchical Classification

In data warehouses, lots of data are gathered which are navigated and explored for analytical purposes. Even for expert people, to handle such a large data is a tough task. Handling such a voluminous data is more difficult task for non-expert users or for users who are not familiar with the database schema. The aim of this paper is to help this class of users by recommending them SQL queries that they might use. These SQL recommendations are selected by tracking the users past behavior and comparing them with other users. At first time, users may not know where to start their exploration. Secondly, users may overlook queries which help to retrieve important information. The queries are recorded and compared using hierarchical classification which is then re-ranked according to relevance. The relevant queries are retrieved using users querying behavior. Users use a query interface to issue a series of SQL queries that aim to analyze the data and mine it for interesting information. DOI: 10.17762/ijritcc2321-8169.15067

Revisting SQL Query Recommender System Using Hierarchical Classification

For analytical purposes, lots of data are gathered which are gathered and explored in data warehouses. Even to handle such a large data is a tough task for expert people. For non-expert users or for users who are not familiar with the database schema, handling such a voluminous data is more difficult task. The aim of this paper is to facilitate this class of users by recommending them SQL queries that they may use. By following the users past behavior and comparing them with other users, these SQL recommendations are selected. Initially, users may not know from where they can start their exploration. Secondly, users may overlook queries which help them to retrieve important data. Using hierarchical classification, the queries are recorded and compared which is then re-ranked according to relevance. Using users querying behavior, the relevant queries are retrieved. To issue a series of SQL queries, users use a query interface which aim to analyze the data and mine it for interesting information. DOI: 10.17762/ijritcc2321-8169.150614

Monoclonal Gammopathy–Associated Scleromyxedema Presenting as Leonine Facies

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146383/1/art40530.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146383/2/art40530_am.pd

Thermal Analysis of Small Re-Entry Probe

The Small Probe Reentry Investigation for TPS Engineering (SPRITE) concept was developed at NASA Ames Research Center to facilitate arc-jet testing of a fully instrumented prototype probe at flight scale. Besides demonstrating the feasibility of testing a flight-scale model and the capability of an on-board data acquisition system, another objective for this project was to investigate the capability of simulation tools to predict thermal environments of the probe/test article and its interior. This paper focuses on finite-element thermal analyses of the SPRITE probe during the arcjet tests. Several iterations were performed during the early design phase to provide critical design parameters and guidelines for testing. The thermal effects of ablation and pyrolysis were incorporated into the final higher-fidelity modeling approach by coupling the finite-element analyses with a two-dimensional thermal protection materials response code. Model predictions show good agreement with thermocouple data obtained during the arcjet test

Beeswax–EVA/Activated-Charcoal-Based Fuels for Hybrid Rockets: Thermal and Ballistic Evaluation

Beeswax (C46H92O) is a naturally derived substance that has the potential to be used as a solid fuel for hybrid rocket applications and as a substitute for paraffin wax fuel in hybrid rockets. BW burns more efficiently than paraffin wax because of the oxygen molecule it contains. The low thermal stability and poor mechanical properties of BW limit its practical use for upper-stage propulsion applications, and these issues are rarely addressed in the literature on hybrid rockets. This study investigates the thermal stability and ballistic properties of BW using ethylene-vinyl acetate (EVA) and activated charcoal (AC) as an additive. The thermal stability of BW–EVA/AC fuel compositions was analyzed using a thermogravimetric analyzer (TGA). The thermal stability of the blended BW compositions improved significantly. A laboratory-scale hybrid rocket motor was used to evaluate such aspects of ballistic performance as regression rate, characteristic velocity, and combustion efficiency. The results revealed that the pure BW exhibited a higher regression rate of 26.5% at an oxidizer mass flux of 96.4 kg/m2-s compared to BW–EVA/AC blends. The addition of EVA and AC to BW was found to increase the experimental characteristic velocity and combustion efficiency. The combustion efficiency of BW-based fuel was improved from 62% to 94% when 20 wt.% EVA and 2 wt.% AC were added into the fuel matrix

Histopathological analysis of soft tissue changes in gingival biopsied specimen from patients with underlying corona virus disease associated mucormycosis (CAM)

Corona Virus Disease-2019 (COVID-19) is perhaps the disastrous medical emergencies that has ever hit globally with multiple strains. Amongst various sequelae, mucormycosis may be considered as the most debilitating one. Post COVID-19 mucormycosis is formally regarded as corona virus disease associated mucormycosis (CAM). The aim of the current paper is to present twelve cases of CAM with unique clinical presentation with a detailed histopathological correlation of the gingival biopsied material. Twelve cases of CAM were included in the study who presented initially with non-purulent swelling of the gingiva. The clinic-demographic data pertaining to age, gender, location, laterality and presence of co-morbidities was collected along with histopathological examination of biopsied specimen. The patients ranged from 31-65 years (mean age 47.33 years). There was a male predominance. Clearly, maxillary right gingiva was mostly affected and all cases presented with non purulent, non tender swelling of the gingiva. The incisional biopsy from the gingiva consistently showed pseudoepitheliomatous hyperplasia of the surface epithelium along with vacuolar degeneration, extensive stromal edema, massive mixed inflammatory reaction, congested blood vessels, hemorrhage and abundant multinucleated giant cells. Potassium hydroxide (10% KOH) mount served no additional diagnostic advantage. After two initial biopsies any suspected case of CAM with these features was treated with appropriate antifungal therapy and conservative excision. Gingival swelling with aforementioned histopathological features resembling post COVID-19 histological alterations could be alarming early signs of CAM and are candidate of prompt antifungal therapy rather than repeat biopsy for confirmation