1,068 research outputs found

    Holography of Charged Dilaton Black Holes

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    We study charged dilaton black branes in AdS4AdS_4. Our system involves a dilaton ϕ\phi coupled to a Maxwell field FμνF_{\mu\nu} with dilaton-dependent gauge coupling, 1g2=f2(ϕ){1\over g^2} = f^2(\phi). First, we find the solutions for extremal and near extremal branes through a combination of analytical and numerical techniques. The near horizon geometries in the simplest cases, where f(ϕ)=eαϕf(\phi) = e^{\alpha\phi}, are Lifshitz-like, with a dynamical exponent zz determined by α\alpha. The black hole thermodynamics varies in an interesting way with α\alpha, but in all cases the entropy is vanishing and the specific heat is positive for the near extremal solutions. We then compute conductivity in these backgrounds. We find that somewhat surprisingly, the AC conductivity vanishes like ω2\omega^2 at T=0 independent of α\alpha. We also explore the charged black brane physics of several other classes of gauge-coupling functions f(ϕ)f(\phi). In addition to possible applications in AdS/CMT, the extremal black branes are of interest from the point of view of the attractor mechanism. The near horizon geometries for these branes are universal, independent of the asymptotic values of the moduli, and describe generic classes of endpoints for attractor flows which are different from AdS2×R2AdS_2\times R^2.Comment: 33 pages, 3 figures, LaTex; v2, references added; v3, more refs added; v4, refs added, minor correction

    Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry

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    We investigate the dynamics of pairs of drops in microfluidic ladder networks with slanted bypasses, which break the fore-aft structural symmetry. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative drop spacing, enabling them to contract, synchronize, expand, or even flip at the ladder exit. Our experiments confirm all these behaviors predicted by theory. Numerical analysis further shows that while ladder networks containing several identical bypasses are limited to nearly linear transformation of input delay between drops, mixed combination of bypasses can cause significant non-linear transformation enabling coding and decoding of input delays.Comment: 4 pages, 5 figure

    Fracturing ranked surfaces

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    Discretized landscapes can be mapped onto ranked surfaces, where every element (site or bond) has a unique rank associated with its corresponding relative height. By sequentially allocating these elements according to their ranks and systematically preventing the occupation of bridges, namely elements that, if occupied, would provide global connectivity, we disclose that bridges hide a new tricritical point at an occupation fraction p=pcp=p_{c}, where pcp_{c} is the percolation threshold of random percolation. For any value of pp in the interval pc<p1p_{c}< p \leq 1, our results show that the set of bridges has a fractal dimension dBB1.22d_{BB} \approx 1.22 in two dimensions. In the limit p1p \rightarrow 1, a self-similar fracture is revealed as a singly connected line that divides the system in two domains. We then unveil how several seemingly unrelated physical models tumble into the same universality class and also present results for higher dimensions

    Bio-nanotechnology application in wastewater treatment

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    The nanoparticles have received high interest in the field of medicine and water purification, however, the nanomaterials produced by chemical and physical methods are considered hazardous, expensive, and leave behind harmful substances to the environment. This chapter aimed to focus on green-synthesized nanoparticles and their medical applications. Moreover, the chapter highlighted the applicability of the metallic nanoparticles (MNPs) in the inactivation of microbial cells due to their high surface and small particle size. Modifying nanomaterials produced by green-methods is safe, inexpensive, and easy. Therefore, the control and modification of nanoparticles and their properties were also discussed

    A Review of Vrushya Dravyas of Guduchyadi Varga of Bhavaprakasha Nighantu

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    Bhavaprakasha Nighantu, an important lexicon of Ayurveda consists of 23 Vargas where Guduchyadi Varga is one among them which consists of 190 drugs. Among them 28 drugs are attributed to Vrushya property. As Infertility has emerged as one of the most common health issues that many young couples are facing, there is a great demand for the treatment of infertility. While, the herbal therapies are better positioned to offer more holistic approaches to improve reproductive health. So here an attempt is made to screen the Vrushya Dravyas mentioned in Guduchyadi Varga of&nbsp; Bhavaprakasha Nighantu with their Rasa, Guna, Veerya, Vipaka

    Set optimization - a rather short introduction

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    Recent developments in set optimization are surveyed and extended including various set relations as well as fundamental constructions of a convex analysis for set- and vector-valued functions, and duality for set optimization problems. Extensive sections with bibliographical comments summarize the state of the art. Applications to vector optimization and financial risk measures are discussed along with algorithmic approaches to set optimization problems

    Partial purification and biochemical characterization of acid phosphatase from germinated mung bean (Vigna radiata) seeds

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    Mung bean (Vigna radiata) is one of the important crops of the North Eastern Region of India. In the present study, acid phosphatase enzyme was isolated and partially purified from germinated local mung bean seeds. The sequential partial purification process was performed using ammonium sulphate precipitation method. The crude enzyme having a specific activity of 0.50 U/mg was purified using 30 to 70% ammonium sulphate precipitation method. The acid phosphatase was purified by 2.6 fold with a yield of 58.9% and specific activity of 1.3 U/mg. One prominent band was obtained on sodium dodecyl sulphate-polyacrylamide gel electrophresis (SDS-PAGE) which confirmed the purity of the enzyme. Molecular weight of the enzyme was estimated as 34.5 kDa. The enzyme activity was measured at different incubation time, pH, temperature and substrate concentration. The activity increased slowly from 10 to 70 min of incubation. The maximum activity was obtained at 70 min, thereafter the activity decreased gradually. The enzyme was found to be active over a wide range of temperature (30 to 80°C) and maximum activity was observed at 70°C. The optimal pH value of the enzyme activity was found to be 5.2. There was a corresponding increase in the rate of reaction with the increase in the substrate concentration from 0.1 to 0.8 mM and a linear relationship was obtained at 2 to 8 mM. Both Km and Vmax value were calculated as 0.416 mM and 1.33 µmoles/min, respectively.Key words: Acid phosphatase, mung bean, Vigna radiata, enzyme purification, enzyme characterization

    On the Temperature Dependence of the Shear Viscosity and Holography

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    We examine the structure of the shear viscosity to entropy density ratio eta/s in holographic theories of gravity coupled to a scalar field, in the presence of higher derivative corrections. Thanks to a non-trivial scalar field profile, eta/s in this setup generically runs as a function of temperature. In particular, its temperature behavior is dictated by the shape of the scalar potential and of the scalar couplings to the higher derivative terms. We consider a number of dilatonic setups, but focus mostly on phenomenological models that are QCD-like. We determine the geometric conditions needed to identify local and global minima for eta/s as a function of temperature, which translate to restrictions on the signs and ranges of the higher derivative couplings. Finally, such restrictions lead to an holographic argument for the existence of a global minimum for eta/s in these models, at or above the deconfinement transition.Comment: references adde

    Quark Number Susceptibility with Finite Chemical Potential in Holographic QCD

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    We study the quark number susceptibility in holographic QCD with a finite chemical potential or under an external magnetic field at finite temperature. We first consider the quark number susceptibility with the chemical potential. We observe that approaching the critical temperature from high temperature regime, the quark number susceptibility divided by temperature square develops a peak as we increase the chemical potential, which confirms recent lattice QCD results. We discuss this behavior in connection with the existence of the critical end point in the QCD phase diagram. We also consider the quark number susceptibility under the external magnetic field. We predict that the quark number susceptibility exhibits a blow-up behavior at low temperature as we raise the value of the magnetic field. We finally spell out some limitations of our study.Comment: 25 pages, 3 figures, published versio

    Evaluation of Intereye Corneal Asymmetry in Patients with Keratoconus. A Scheimpflug Imaging Study

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    Purpose: To assess the correlation between keratoconus severity and intereye asymmetry of pachymetric data and posterior elevation values and to evaluate their combined accuracy in discriminating normal corneas from those with keratoconus. Methods: This study included 97 patients: 65 subjects with bilateral normal corneas (NC) and 32 with keratoconus (KC). Central corneal thickness (CCT), thinnest corneal thickness (ThCT) and posterior elevation (PE) at the thinnest point of the cornea were measured in both eyes using Scheimpflug imaging. Intereye asymmetry and its correlation with keratoconus severity were calculated for each variable. The area under the receiver operating characteristic curve (AUROC) was used to compare predictive accuracy of different variables for keratoconus. Results: In normal eyes, intereye differences were significantly lower compared with the keratoconus eyes (p<0.001, for CCT, ThCT and PE). There was a significant exponential correlation between disease severity and intereye asymmetry of steep keratometry (r(2) = 0.55, p<0.001), CCT (r(2) = 0.39, p<0.001), ThCT (r(2) = 0.48, p<0.001) and PE (r(2) = 0.64, p<0.001). After adjustment for keratoconus severity, asymmetry in thinnest pachymetry proved to be the best parameter to characterize intereye corneal asymmetry in keratoconus. This variable had high accuracy and significantly better discriminating ability (AUROC: 0.99) for KC than posterior elevation (AUROC: 0.96), ThCT (AUROC: 0.94) or CCT (AUROC: 0.92) alone. Conclusions: There is an increased intereye asymmetry in keratometry, pachymetry and posterior corneal elevation values in keratoconic patients compared to subjects with normal corneas. Keratoconus patients with more severe disease are also more asymmetric in their disease status which should be taken into account during clinical care
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