2,563 research outputs found

    High energy kink in the dispersion of a hole in an antiferromagnet -- double-occupancy effects on electronic excitations

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    Evolution of the hole spectral function along the Gamma-(pi,pi) cut is studied in the antiferromagnetic state of the Hubbard model. The kink in the calculated hole dispersion, the sharp spectral-weight transfer between the branches, and the drastically suppressed coherent spectral weight near k=(0,0), as observed recently in the high-resolution ARPES studies of cuprate antiferromagnets, are shown to be strongly enhanced by finite-U double-occupancy effects. Together with the anomalous spin-wave dispersion observed earlier in high-resolution neutron-scattering studies, the present study provides further evidence of a unified description of magnetic and electronic excitations in cuprate antiferromagnets in terms of the Hubbard model.Comment: 5 pages, 7 figure

    Hole and electron dynamics in the triangular-lattice antiferromagnet -- interplay of frustration and spin fluctuations

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    Single-particle dynamics in the 120^{\circ} ordered antiferromagnetic state of the triangular-lattice Hubbard model is studied using a physically transparent fluctuation approach in terms of multiple magnon emission and absorption processes within the noncrossing approximation. Hole and electron spectral features are evaluated at intermediate UU, and analyzed in terms of a competition between the frustration-induced direct hopping and the virtual hopping terms. Finite UU-induced competing interactions and frustration effects contributing through the magnon dispersion are also discussed. Finite contribution to self-energy correction from long-wavelength (Goldstone) modes, together with the high density of electron scattering states in the narrow, sharp peak in the upper band, result in strong fermion-magnon scattering leading to pronounced incoherent behaviour in the electron dynamics. The fluctuation-induced first-order metal-insulator transition due to vanishing band gap is also discussed.Comment: 10 pages, 13 figure

    Effect Of White Rot Fungi Variation On The Biopulping Of Oil Palm Trunk

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    Lignocelluloses biomass is an important and sustainable natural resource for paper making. Wood the predominant source consists of flexible cellulose fibres, its pretreatment makes cellulose more accessible to enzymatic hydrolysis by modification of the lignin.Biological pulping is the treatment of lignocellulosic materials with oxidative lignin-degrading white rot fungi prior to pulping process. Biojisim lignoselulosik adalah suatu sumber semulajadi yang penting dan berterusan bagi pembuatan kertas. Kayu merupakan sumber utama yang mengandungi gentian selulosa yang fleksibel, pra rawatan menghasilkan selulosa yang lebih cenderung untuk hidrolisis berenzim melalui pengubahsuaian penghalang lignin

    Allele-specific primer based identification of dimeric alpha-amylase inhibitor

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    Wheat is one of the most important staple food crops cultivated over 200 mha in the range of environment throughout the world. Wheat production must continue to increase by 2% annually, more particularly in developing world including south-east Asia. Besides increasing the inherent productivity of wheat, it is important to minimize the losses caused to production by various abiotic and biotic factors. Alpha–amylase inhibitors are attractive candidates for the control of seed weevils as these insects are highly dependent on starch as the energy source. They play an important role in the carbohydrate metabolism of many heterotrophic and autotrophic organisms. In this study, we aimed to make sequence comparison and phylogenetic relationship among dimeric alpha-amylase inhibitor genes. These genes were clustered into two major groups based on phylogenetic analysis. Multiple alignments show at least 24 candidates single nucleotide polymorphisms in inhibitor genes, which could further be exploited for SNPs based haplotype diversity among Indian released wheat genotype. We have detected dimeric alpha-amylase inhibitor genes in cultivated and wild ancestors of wheat using genome specific primers. Genes encoding dimeric alpha-amylase belong to the family of 24 kDa alpha-amylase inhibitors. In this study, specific primer pairs were designed based on SNPs of these genes and chromosome locations of inhibitor genes confirmed by amplification in accession of T. urartu, A. tauschii, and A. speltoides. Results obtained under this study support that inhibitor genes amplified with primer PSWDAIAF1/PSWDAIAF2 and PSWDAIBF1/PSWDAIBF2 is present on genome B. These results further support evidence at molecular level that dimeric alpha-amylase inhibitor in cultivated wheat is encoded by a multigene family.

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    Characteristics of COPD phenotypes classified according to the findings of HRCT and spirometric indices and its correlation to clinical characteristics

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    Introduction: In recent years, there has been increasing interest in diagnosing various components of chronic obstructive pulmonary disease (COPD) using high-resolution computed tomography (HRCT). The present study was undertaken to evaluate HRCT features in patients with COPD.Materials and methods: Fifty patients of COPD (confirmed on Spirometry as per the GOLD guidelines 2014 guidelines) were enrolled, out of which 35 patients got a HRCT done. The Philips computer program for lung densitometry was used with these limits (-800/-1, 024 Hounsfield unit [HU]) to calculate densities, after validating densitometry values with phantoms. We established the area with a free hand drawing of the region of interest, then we established limits (in HUs) and the computer program calculated the attenuation as mean lung density (MLD) of the lower and upper lobes.Results: There was a significant correlation between smoking index and anteroposterior tracheal diameter (P = 0.036). Tracheal index was found to be decreasing with increasing disease severity which was statistically significant (P = 0.037). A mild linear correlation of pre-forced expiratory volume in the first second (FEV1) was observed with lower lobe and total average MLD while a mild linear correlation of post-FEV1 was observed with both coronal (P = 0.042) and sagittal (P = 0.001) lower lobes MLD. In addition, there was a linear correlation between both pre (P = 0.050) and post (P = 0.024) FEV1/forced vital capacitywith sagittal lower lobe MLD.Conclusion: HRCT may be an important additional tool in the holistic evaluation of COPD.Keywords: Chronic obstructive pulmonary disease, high resolution computed tomography, spirometry.

    Maxillary first molar with three mesiobuccal canals confirmed with spiral computer tomography

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    Anatomic variations in root canal morphology have become easier to detect with the rapid advancements in clinical and diagnostic aids. Also an increased awareness of unusual anatomic morphology and a better understanding of the root canal system guides the clinician in diagnosis and treatment of such variations in order to achieve a successful endodontic outcome. Mesiobuccal root of first maxillary molar teeth have been considered to be one of the most complex and challenging root canal systems. This case report presents a successful management of a third canal in the mesiobuccal root of permanent maxillary first molar using dental operating microscope along with a modified access preparation and confirmed with the aid of spiral computed tomography

    Brahmi (Bacopa monnieri) : a mental illness drug

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    Ayurveda is the life science and practice that involve the care of the human being's physical, mental, and spiritual health. The term "Ayu” is defined as- "Sharir Indriya Satva Atma Sanyogo Dhari Jeevtam (Charak). According to Acharaya Charaka the individuality of Manas and Sarira is inseparable and interdependent. The paragon of the beauty of Ayurveda is that it always emphasizes prevention over cure. Yendri (Bacopa monnieri Linn). Mentioned as Medhya by Priyavrat Sharma in his book Dravyagun Vigyana. Nowadays, the use of herbal drugs for the treatment of various diseases is developing worldwide. Psychiatric and neurological disorders are generally associated with memory loss, cognitive deficits, impaired mental function, etc. Due to the multi-factorial nature of these diseases, psychoactive drugs of modern medicine have achieved restricted success. Therefore, there is an extended stipulation for novel products that could target multiple pathways and improve mental capabilities. According to "Ayurveda," the Indian traditional medicine system, "Medhya Rasayana" presents herbal therapeutics that restores cognitive deficits, boost memory, and improve mental functions. The current review emphasizes the components and application of such type of herbal medication

    Mandibular First Premolar with Three Roots: A Case Report

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    Anatomy of the root canal system always effects endodontic treatment outcome. Mandibular premolar teeth show extreme variations in root canal morphology. First premolars usually exhibit basic one root and one canal anatomy. The occurrence of three roots in mandibular first premolar has not been commonly reported in literature. This article reports a case of successful nonsurgical endodontic management of mandibular first premolar with three canals and three different apical foramina

    Screening of pregnant women for cervical malignancies

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    This study was carried out on a cross-sectional prospective basis on 590 pregnant women attending ante natal OPD in government medical college and hospital over a period of 1 year during their routine ante natal check up for screening cervical malignancies. The data obtained were analysed. 99% of the cases were less than 30 years of age. No single case of cervical dysplasia or malignancy was reported. Considering that we have limited resources, screening these young patients in whom we expect low incidence of pre cancer or cancerous lesions doesn’t appear to be a very good approach.
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