99 research outputs found
A group theoretical treatise on color mixing
On relating the three primary colors namely red, green and blue with a
triplet representation of the non-abelian group , it is established that
the three secondary and six tertiary colors along with two neutral colors
transform as anti-triplet and octet under the same group respectively
Thermal properties of accretion disc in non-Kerr spacetime: distinguishing black hole and naked singularity
In this paper, we study the properties of accretion flow including its
spectral features in Johannsen and Psaltis (JP) non-Kerr spacetime. In doing
so, we numerically solve the governing equations that describe the flow motion
around the compact objects in a general relativistic framework, where spin
() and deformation parameters () demonstrate the nature of
the central source, namely black hole (BH) or naked singularity (NS). With
this, we obtain all possible classes of global accretion solutions (, O,
A, W and I-type) by varying the energy () and angular momentum ()
of the relativistic accretion flow, and examine the role of thermal
bremsstrahlung emission in studying the spectral energy distributions (SEDs) of
the accretion disc. We divide the parameter space in plane in terms
of the different classes of accretion solutions for BH and NS models. We
further calculate the disc luminosity () corresponding to these accretion
solutions, and observe that I-type solutions yield higher and SEDs than the
remaining types of solutions for both BH and NS models. For BH model, SEDs for
W and I-type solutions differ significantly from the results for O and A-type
solutions for low values. On the contrary, for NS model, SEDs for different
accretion solutions are identical in the whole parameter space of and
. We also examine the effect of on the SEDs and observe that a
non-Kerr BH yields higher SEDs than the usual Kerr BH. Finally, for accretion
solutions of identical and , we compare the SEDs obtained from BH
and NS models, and find that naked singularity objects produce more luminous
power spectra than the black holes.Comment: 15 pages, 13 figures, 2 table
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Wear of fine pearlite, nanostructured bainite and martensite
Abrasion is a form of wear prominent particularly in the agricultural, mining, mineral and transportation industries. The cost of abrasive wear to the national economy is estimated to be about 1% of the gross national product, and it can compromise the safety and reliability of engineering components. The mechanism of wear is complex and dependent on all the materials involved in the process, environmental conditions and many subtle factors such as the shape of the abrading particles. Many abrasion-resistant steels are based on a quenched and tempered martensitic microstructure, because the hardness of the steel should intuitively matter in determining the wear rate. Nevertheless, the relationship between the rate of material loss and steel hardness is unlikely to be monotonic. The purpose of the work presented in this thesis was primarily to study the abrasive wear behavior of a nanostructured bainitic steel that has been successful in structural applications, is capable of mass production, and can achieve hardness levels comparable to martensitic steels without compromising ductility, toughness and fatigue resistance. A variety of wear mechanisms have been studied, in each case with a detailed characterisation of the damage, the structural evolution and a panoply of theoretical approaches. In the case of three-body abrasion, it is found that huge variations in hardness, achieved by changing the structure from pearlite, nanostructured bainite to martensite by heat treatment, do not lead to significant differences in the wear rate. This is because the wear mechanisms change, for example from severe sub-surface deformation leading to sticking in the case of pearlite, to brittle detachment of material in the martensitic state. The nanostructured bainite, on the other hand, undergoes reaustenitisation at the surface that leads to the formation of a fine martensitic layer with consequent surface hardening, in contrast to the pearlite and martensite, both of which soften at the contact surfaces. It is the presence of stable austenite in the nanostructured bainite that causes this difference, because austenitisation becomes easier to achieve. This hypothesis has been further tested by eliminating the austenite from the nanostructured bainite. The experiments confirm that a reaustenitised layer no longer forms during three-body abrasion. The softening observed on martensitic samples also disappears when similar tests are done on tempered martensite, indicating the effect of the localised heat generated during dry abrasion on untempered martensite. In contrast to three-body abrasion using silica where the weight loss is insensitive to hardness, the nanostructured bainite outperforms most commercial alloys of equivalent hardness, and sometime even harder materials, during dry rolling/sliding wear. The mechanisms involved have been rationalised in terms of structural damage mechanisms, the development of beneficial residual stresses, and detailed changes in crystallite size and dislocation character as a function of rolling. It has, in general, been possible to rationalise the observed variations in different types of wear tests and micro- or nanostructures, and it is believed that the work will be of use in designing commercially important products
Structural review of relics tourism by text mining and machine learning
Purpose: The objective of the paper is to find trends of research in relic tourism-related topics. Specifically, this paper uncovers all published studies having latent issues with the keywords "relic tourism" from the Web of Science database. Methods: A total of 109 published articles (2002-2021) were collected related to "relic tourism." Machine learning tools were applied. Network analysis was used to highlight top researchers in this field, their citations, keyword clusters, and collaborative networks. Text analysis and Bidirectional Encoder Representation from Transformer (BERT) of artificial intelligence model were used to predict text or keyword-based topic reference in machine learning. Results: All the papers are published basically on three primary keywords such as "!relics," "culture," and "heritage." Secondary keywords like "protection" and "development" also attract researchers to research this topic. The co-author network is highly significant for diverse authors, and geographically researchers from five countries are collaborating more on this topic. Implications: Academically, future research can be predicated with dense keywords. Journals can bring more special issues related to the topic as relic tourism still has some unexplored areas
Evaluating mild traumatic brain injury in adults: an emergency physicianâs dilemma
Background: Mild traumatic brain injury (MTBI) is a common presentation in emergency departments across the globe. A controversy about the policy of evaluating them with CT scan and hospital admission or discharge and for these patients. This study is directed towards correlation of clinical profile with CT brain findings of the patients to predict the possibility of an intracranial lesion and need for early neurosurgical intervention.Methods: This prospective observational study was carried out in the Emergency Department (ED) of a tertiary care government medical college and hospital. All patients aged more than 12 years presenting to the ED with mild traumatic brain injury (MTBI) within 24 hours of injury in whom NCCT head (trauma protocol) was done during the Study. Descriptive and analytical statistics were applied. Multiple logistic regression analysis was used to identify factors related to different outcomes.Results: 178 patients with MTBI were enrolled in the study among which intracranial injuries were found by CT scan in 28 patients (15.7%). Odds of finding intracranial injuries were highest with the presence of post-traumatic vomiting, post traumatic amnesia (PTA), pre-existing alcohol use disorder, GCSâ€14, focal neurological deficit and clinical signs of basal skull fracture. 2.8% patients required urgent neurosurgical intervention.Conclusions: Presence of post-traumatic vomiting, PTA, alcohol use disorder, GCSâ€14, focal neurodeficit and signs of basal skull fracture in a MTBI patient should be considered as high-risk factors for significant intracranial injuries.Â
Fluconazole induced multifocal bullous eruptions: a case report
The term bullous drug eruption refers to adverse drug reactions that result in fluid filled blisters. Blistering can be due to various medications. A 22 year old primigravida developed bullous lesions on upper limbs, lower legs and face after taking six doses of lumether forte (artemether 80 mg + lumefantrine 480 mg themis medicare ltd) and difenac plus (diclofenac 50 mg + paracetamol 500 mg intermed), and single dose of flucan (fluconazole 150 mg Bombay tablet Mfg co) and mebex (mebendazole 100 mg Cipla Limited). She had a previous history of localized bullous eruption 2 years back after taking a single dose of forcan (fluconazole 150 mg Cipla Limited) for vaginal candidiasis. There are reported cases of bullous eruptions due to diclofenac, mebendazole and paracetamol. However in our case past history of localized bullous eruptions after taking fluconazole, made it superior to other offenders to be suspected as the âprobableâ culprit. Naranjo causality score was (âŠ+5âŠ)
Study of antibacterial, anti-proliferative and pro-apoptotic potential of the cell extracts of endophytic fungi and bacteria isolated from Pajanelia longifolia (Willd.) K. Schuman
Endophytes contribute to the synthesis of significant metabolites in symbiotic association with their host plants. On considering the medicinal importance of the prominent tree species Pajanelia longifolia (Willd.) K. Schuman, the study was conducted to isolate and identify the endophytic bacteria and fungi for their bioactivity. The isolation of endophytic bacteria and fungi were performed by surface sterilisation of the stem and leaf samples of P. longifolia. The obtained bacterial and fungal endophytic isolates were maintained in nutrient agar and Potato Dextrose Agar (PDA) media and were examined for colony morphology and microscopic appearances with varied biochemical characterisations. Furthermore, both the fungal and bacterial isolates were subjected to solvent extractions to evaluate antibacterial activity. Also, anti-proliferative effects due to apoptotic induction by the endophytic fungal extracts were checked against proliferative yeast cells. Moreover, endophytic bacteria belonging to Enterococcaceae had shown antibacterial activity against Salmonella species. In the present study, fungal species belonging to Cladosporium predominantly found to inhabit as endophytic fungi in the plant samples. Also, this particular fungus among other selected endophytic fungi attributed to causing effective anti-proliferative activity. The endophytic bacteria belonging to Enterococcus and Micrococcus genera showed significant antimicrobial activity against Salmonella typhimurium (ATCC 23564)
Seasonal variation of arsenic concentrations in tubewells in west Bengal, India.
This study was conducted to monitor the changes in arsenic concentration during different seasons in a one-year period during 2002-2003 in selected tubewells in an arsenic-affected area in the district of South 24 Parganas in West Bengal, India, and to map the location of the wells. Seasonal variations in concentrations of arsenic in water were measured from 74 selected tubewells, ranging in depth from 40 to 500 feet. Water samples were collected from these wells during winter, summer, monsoon, and the following winter in 2002-2003. A global positioning system was used for locating the tubewells, and a geographic information system was used for mapping. There was evidence of seasonal variation in concentrations of arsenic in water (p=0.02) with the minimum average concentration occurring in the summer season (694 microg/L) and the maximum in the monsoon season (906 microg/L). From the winter of 2002 to the winter of 2003, arsenic concentrations increased, irrespective of the depth of the tubewells, from an average of 464 microg/L to 820 microg/L (p<0.001). This extent of variation in arsenic concentration, if confirmed, has important implications for both epidemiological research and mitigation programmes
Notes on the discovery and ecology of the invasive armoured catfish Pterygoplichthys disjunctivus (Weber, 1991) and the exotic cichlid Amphilophus trimaculatus (Gunther, 1867) from Southern West Bengal, India
This paper documents the first occurrence of the exotic, highly invasive, South American armoured sucker mouth catfish Pterygoplichthys disjunctivus (Weber, 1991) from the brackish waters of the Sundarban Tiger Reserve, West Bengal, India and the Central American cichlid Amphilophus trimaculatus (Gunther, 1867) from Southern Bengal, India. Notes on the possible threats due to invasion, sources of introduction, extent of spread and management of these and other invasive species are discussed in the paper
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