391 research outputs found

    Iterative Roots of Multifunctions

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    Some easily verifiable sufficient conditions for the nonexistence of iterative roots for multifunctions on arbitrary nonempty sets are presented. Typically if the graph of the multifunction has a distinguished point with a relatively large number of paths leading to it then such a multifunction does not admit any iterative root. These results can be applied to single-valued maps by considering their pullbacks as multifunctions. This has been illustrated by showing the nonexistence of iterative roots of some specified orders for certain complex polynomials.Comment: 16 pages, 8 figure

    Laboratory Column flotation studies for reduction of alumina and silica in iron ore slimes of an operating plant

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    A typical iron ore washing plant for treating iron ore fines (<10 mm) consist of sizing of the ore by dry / wet screening, washing, classification by screw classifiers followed by single or multi-stage hydrocycloning of screw classifiers overflow. The underflow of the hydrocyclones forms the concentrate which is suitable for pellets making. Since the cut-point of hydrocyclones is usually at 20 µm or less, relatively lower diameter cyclones in a cluster with parallel feeding are used. This is found to, often, result in choking of the spigots, at times, by extraneous material reporting along with the slurry. It is observed to lead to sub-optimum performance of the cyclones with loss of iron values into cyclone overflow and thereafter into tailings. Analysis of the data of an operating beneficiation plant (Beneficiation plant - 1) of M/s Jindal South West (JSW) Steel Limited, Karnataka, India over a period of one year indicated that weight recovery of the concentrate from two-stage hydrocycloning was 45.9% (with respect to feed to the cyclones) and assaying 63.43% Fe, 4.43% SiO2 and 2.23% Al2O3. Considering the fineness of the slimes (d80: 40.5 µm), generated as screw classifier overflow, flotation is thought to be better alternative vis-à-vis hydrocyclones to recover iron values from it. The present study aims at improving the recovery of the iron values from the screw classifier overflow by adopting reverse cationic column flotation technology. After selecting a suitable collector, process parameters like collector and depressant dosages are optimized by statistically designed experiments on a Denver D12 flotation cell. Later, the effect of important operating parameters of flotation column like air flow-rate, froth depth and wash water on the separation process is studied and optimized. It was established that a typical screw classifier overflow analyzing 60.43% Fe, 6.88% SiO2 and 3.26% Al2O3 could be improved to 63.30% Fe, 4.04% SiO2 and 2.32% Al2O3 with 59.10% weight and 61.70% Fe recovery. This is an improvement of 29% in weight recovery of the concentrate at equivalent metallurgy compared to what is being obtained, by two-stage cycloning

    Quantification of benzene in groundwater sources and risk analysis in a popular South Indian Pilgrimage City – A GIS based approach

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    AbstractThe present research work quantified the concentration of benzene in a total of hundred groundwater samples at the proximity of petrol bunks and residential places in Madurai District. The average values recorded in Jan 2011, Feb 2011 and Mar 2011 were 0.100mgL−1 (10 times of PL), 0.138mgL−1 (14 times of PL) and 0.060mgL−1 (6 times of PL) respectively. A significant variation in the benzene level during February–March 2011 was validated through Student’s t-test analysis. Hierarchical cluster analysis using dendograms revealed the un-symmetric distribution of benzene during the study period. The cancer risk analysis at corporate locations among children was seven folds higher as compared to the risk of adults. The benzene concentration levels are interpreted using Arc Geographical Information System (Arc GIS) through thematic maps

    Determination of dynamic heights in the Bay of Bengal from XBT profiles and climatological salinities

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    Dynamic height (DH) computations are necessary for the estimation of geostrophic currents, heat transport studies, identification of eddies and to validate the altimeter sea surface height (SSH) observations. To compute DHs we need the temperature and salinity profiles to a reasonable deeper level. But, temperature profiles alone, such as from XBT (expendable bathy thermograph), are more numerous than combined temperature and salinity measurements from CTD (conductivity, temperature and depth). To use these voluminous temperature measurements from XBT observations in the computation of DHs, temperature/salinity relations were developed in many oceanic regions. Since such an exercise cannot be carried out in the Bay of Bengal due to the absence of adequate CTD measurements, we have proposed a method of utilizing XBT measurements and climatological (Levitus and Boyer, 1994) salinities to compute the DHs. The approach is demonstrated by replacing the CTD salinities with the climatological salinities. The relative errors compared to the DH signals are 3.8%, 2.7% and 2.6% for 200, 700 and 1000 dbar levels, respectively. The DHs relative to 700 dbar computed using the XBT temperature and climatological salinity profiles are compared with the SSH observations from TOPEX altimeter. The standard deviation of the difference between the DHs computed after converting to geometrical units and SSH is 7.3 cm

    Evaluation of the Anxiolytic Activity of NR-ANX-C (a Polyherbal Formulation) in Ethanol Withdrawal-Induced Anxiety Behavior in Rats

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    The present study investigates the anxiolytic activity of NR-ANX-C, a standardized polyherbal formulation containing the extracts of Withania somnifera, Ocimum sanctum, Camellia sinensis, Triphala, and Shilajit in ethanol withdrawal- (EW-) induced anxiety behavior in rats. Ethanol dependence in rats was produced by substitution of drinking water with 7.5% v/v alcohol for 10 days. Then, ethanol withdrawal was induced by replacing alcohol with drinking water, 12 hours prior to experimentation. After confirming induction of withdrawal symptoms in the alcohol deprived animals, the anxiolytic activity of the test compound in graded doses (10, 20, and 40 mg/kg) was compared to the standard drug alprazolam (0.08 mg/kg) in the elevated plus maze and bright and dark arena paradigms. In our study, single and repeated dose administration of NR-ANX-C reduced EW-induced anxiety in a dose-dependent manner. Even though the anxiolytic activity was not significant at lower doses, NR-ANX-C at the highest dose tested (40 mg/kg) produced significant anxiolytic activity that was comparable to the standard drug alprazolam. Based on our findings we believe that NR-ANX-C has the potential to be used as an alternative to benzodiazepines in the treatment of EW-induced anxiety

    Analysis by polymerase chain reaction of the physical state of human papillomavirus type 16 DNA in cervical preneoplastic and neoplastic lesions

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    Integration of human papillomavirus (HPV) DNA into the host cell genome is believed to be essential for malignant progression. However unambiguous detection of the physical state of HPV is a difficult and time-consuming procedure. To resolve this issue a simple, rapid and highly sensitive technique of polymerase chain reaction (PCR) has been utilized for detecting the physical state of HPV-16 DNA. Investigations were carried out in 122 cervical specimens comprising the whole spectrum of cervical lesions starting from cervical dysplasia to invasive carcinoma including HPV-16-positive normal controls. A pair of oligonucleotide primers specific to the E2 open reading frame, which is often deleted or disrupted following HPV integration, was used for the study. Distinction between episomal and integrated forms of viral DNA was accomplished by detecting amplification of the E2-specific fragment (1139 bp) in the PCR product. The PCR results were compared with those obtained by the conventional methods of Southern blotting, two-dimensional gel electrophoresis and chromosomal in situ hybridization; a high degree of agreement was observed between the methods. The findings indicate that although integrated forms of HPV-16 DNA were detected in more than 70% of cervical cancer specimens, integration was less frequent (23%) in severe dysplasia and carcinoma in situ. Only 2.5% of cases showed both episomal and integrated forms of HPV-16 DNA. The difference between episomal and integrated forms was statistically significant (P &lt; 0.01). The absence of integration in about 30% of cancer cases suggests that integration of HPV may not be necessary for malignant progression and alternative mechanism(s) of malignant transformation may occur without HPV integration. The PCR test thus provides an effective complement to Southern blotting and two-dimensional gel electrophoresis for accurate detection of the integration of HPV DNA

    Optimization of parameters effecting the heat recovery from a sand casting process

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    Energy crises has gripped the world to a large extent. Researchers are experimenting on newer and newer avenues to produce energy efficiently, economically. Energy saved is actually twice produced. Energy conservation is the need of the hour. Keeping this in mind the authors of the paper have developed a method to harness the heat that gets wasted during the casting process. Casting is basically one of the manufacturing processes were molten metal is poured into mould and then solidified. The solidifying metal takes the shape of the mould. Huge amount of energy is required for the melting of the raw material. When the metal solidifies it gives way the heat. In the present work the mould is modified such that the raw material that will be used for subsequent process gets pre heated by the heat that emanates due to the solidification process. A number of factors influence the amount of heat that is recovered. Here attempt is made to find out the factors that influence the pre heat of raw material and also using Particle swarm optimization technique the factors are optimized so that the heat recovered is maximised. The implementation of the process is simple and the gains are enormous in terms of the energy that is going to be saved

    Variation of phase lengths in wet and dry nylon 6 using SAXS data

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    Salinity Measurements Collected by Fishermen Reveal a “River in the Sea” Flowing Along the Eastern Coast of India

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    Being the only tropical ocean bounded by a continent to the north, the Indian Ocean is home to the most powerful monsoon system on Earth. Monsoonal rains and winds induce huge river discharges and strong coastal currents in the northern Bay of Bengal. To date, the paucity of salinity data has prevented a thorough description of the spreading of this freshwater into the bay. The potential impact of the salinity on cyclones and regional climate in the Bay of Bengal is, however, a strong incentive for a better description of the water cycle in this region. Since May 2005, the National Institute of Oceanography conducts a program in which fishermen collect seawater samples in knee-deep water at eight stations along the Indian coastline every 5 days. Comparison with open-ocean samples shows that this cost-effective sampling strategy is representative of offshore salinity evolution. This new dataset reveals a salinity drop exceeding 10 g kg−1 in the northern part of the bay at the end of the summer monsoon. This freshening signal propagates southward in a narrow (~100 km wide) strip along the eastern coast of India, and reaches its southern tip after 2.5 months. Satellite-derived alongshore-current data shows that the southward propagation of this “river in the sea” is consistent with transport by seasonal coastal currents, while other processes are responsible for the ensuing erosion of this coastal freshening. This simple procedure of coastal seawater samples collection could further be used to monitor phytoplankton concentration, bacterial content, and isotopic composition of seawater along the Indian coastlin
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