11,673 research outputs found

    Underlying Fermi surface of Sr14−x_{14-x}Cax_xCu24_{24}O41_{41} in two-dimensional momentum space observed by angle-resolved photoemission spectroscopy

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    We have performed an angle-resolved photoemission study of the two-leg ladder system Sr14−x_{14-x}Cax_xCu24_{24}O41_{41} with xx= 0 and 11. "Underlying Fermi surfaces" determined from low energy spectral weight mapping indicates the quasi-one dimensional nature of the electronic structure. Energy gap caused by the charge density wave has been observed for xx=0 and the gap tends to close with Ca substitution. The absence of a quasi-particle peak even in xx=11 is in contrast to the two-dimensional high-TcT_c cuprates, implying strong carrier localization related to the hole crystalization.Comment: 5 pages, 3 figure

    ARPES studies of cuprate Fermiology: superconductivity, pseudogap, and quasiparticle dynamics

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    We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below Tc_c. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.Comment: To appear in a focus issue on 'Fermiology of Cuprates' in New Journal of Physic

    Level-crossing rate and average duration of fades for mobile radio channel with hyperbolically distributed scatterers

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    In this paper we study the geometrical and time-variant wireless vector channel model with hyperbolically distributed scatterers for a macrocell mobile environment. In this study we investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this recently-proposed model. The simulated results are verified against the analytical Clarke's channel model. In this paper we study the geometrical and time-variant wireless vector channel model with hyperbolically distributed scatterers for a macrocell mobile environment. In this study we investigate the level-crossing rate (LCR), the average duration of fades (ADF), the probability density function (PDF), the cumulative distribution function (CDF) and the autocorrelation functions (ACF) of this recently-proposed model. The simulated results are verified against the analytical Clarke's channel model

    Adherence to Gluten Free Diet in Pakistan-Role of Dietitian

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    Celiac disease (CD) is a common multi-system autoimmune disease, affecting approximately 1% of people worldwide 1. Predisposed individuals develop an immune response to gluten, a protein found in the cereal grains: wheat, barley and rye. Autoimmune intestinal damage is the cardinal feature of celiac disease, and typically involves villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes 2. Symptoms may be subclinical, varying from gastrointestinal upset to severe malabsorption 3,4. Skin, nervous system, and multisystem involvement is also recognized. Strict avoidance of gluten-containing foods can reverse both enteric and extra-intestinal manifestations of the disease

    A novel approach in development of dynamic muscle model for paraplegic with functional electrical stimulation

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    This paper presents the development of paraplegic muscle model with Adaptive Neuro-Fuzzy Inference System (ANFIS). A series of experiments using Functional Electrical Stimulation (FES) with different stimulation frequencies, pulse width and pulse duration to investigate the impact on muscle output torque are conducted. The data that is obtained is used to develop the paraplegic muscle model. 500 training data and 300 testing data set are used in the development of muscle model. The muscle model thus developed is validated with clinical data from one paraplegic subject and in comparison with two other muscle models from previous researchers. The ANFIS muscle model is found to be the most accurate muscle model representing paraplegic muscle model. The established model is then used to predict the behaviour of the underlying system and will be used in the future for the design and evaluation of various control strategies

    Hyperforin: A lead for antidepressants

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    Depression is a complex but treatable disorder if diagnosed appropriately. However, despite the advances in the understanding of the molecular basis of this disorder and the vast range of medication, psychotherapy and electroconvulsive therapy, very safe and effective drug to treat this disease is still being sought. Several studies suggest that St.John’s wort (Hypericum perforatum L.) has phloroglucinol derivative, hyperforin, exhibiting antidepressant activity. This bioactive component can be exploited to create a major shift in the safer treatment of depression. Keywords: Hypericum perforatum L., St. John's wort, Antidepressant, Hyperfori

    Water management reforms in the Yellow River Basin: implications for water savings, farm incomes and poverty

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    River basins / Water management / Governance / Water use / Crop production / Models / Farm income / Poverty / Water users’ associations / China / Yellow River Basin

    Estimation of volatile organic compounds in farmed and wild rohu, Labeo rohita

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    Volatile organic compounds in farmed and wild rohu, Labeo rohita, were extracted by Likens-Nickerson concurrent distillation apparatus. The farmed raised rohu of two weight categories designated as FW1 (1001-1200g) and FW2 (501-700g) were procured from the Fish Seed Hatchery, Faisalabad. Concurrently, wild rohu of two weight categories designated as WW1 (1001-1200g) and WW2 (501-700g) were captured with gillnet from the Trimu Head. Quantitative and qualitative estimation was made by gas chromatography. In farmed and wild L. rohita of the weight group FW1 and WW1, 14 and 6 volatile compounds were extracted, respectively. In weight group FW1, six compounds were identified as 3-methyl-1-butanol, 3-hexene-1-ol, heptanal, 3-octanol, decanal and 2-undecanone. In weight group WW1, out of six compounds three were identified as heptanal, 1-octen-3-ol, 2-nonanone. In weight categories FW2 and WW2, 14 and 13 volatile compounds were detected, respectively. In weight category FW2, out of 14 compounds, 3-hexene-1-ol, heptanal, 3-octanol, 2-undecanone and decanal were identified. In weight category WW2, out of 13 compounds, 7 were identified as 3-methyl-1-butanol, 2-heptanone, heptanal, 3-octanol, 2-nonanone, decanal and 2-undecanone. The analysis of variance for retention time and concentration of volatile compounds showed no significant difference (p>0.05). The correlation coefficient between retention time and concentration was significant (p< 0.05)
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