A Novel Technique for Fundus Image Contrast Enhancement

ABSTRACT Digital fundus Image analysis plays a vital role in computer aided diagnosis of several disorders. Image acquired with fundus camera often have low grey level contrast and dynamic range .We present a new method for fundus image contrast enhancement using Discrete Wavelet Transform (DWT) and Singular Value Decomposition(SVD).The performance of this technique is better than conventional and state of the art-techniques. With the proposed method the given Fundus Image is decomposed into four frequency sub band images and Singular Value Decomposition applied on Low-Low subband Image, which determines the intensity information. Finally Image reconstructed using modified Low-Low subband coefficients and three high frequency sub band coefficients. The qualitative and quantitative performance of proposed technique i

Special Issue 01

ABSTRACT 1.INTRODUCTION Wireless mesh networks (WMNs) are being developed actively and deployed widely for a variety of applications, such as public safety, environment monitoring, and citywide wireless Internet services. The wireless backbone, consisting of wireless mesh routers equipped with one or more radio interfaces, highly affects the capacity of the mesh network. This has a significant impact on the overall performance of the system, thus generating extensive research in order to tackle the specific challenges of the WMN. This configuration adversely affects the capacity of the mesh due to interference from adjacent nodes in the network. Directional antennas and modified MAC protocols make the practical deployment of such solutions infeasible on a wide scale, the main issue in using multiple channels with a single radio is that dynamic channel switching requires tight time synchronization between the nodes. The protocol makes use of the knowledge of network topology by utilizing selective flooding of control messages in a portion of the network. In this way, broadcasting of control messages is avoided and thus the chances of network congestion and disruption of the flows in the network are reduced. A typical WMN application consists of three levels: wired networks, the WMN backbone, and mesh clients. Wired networks contain most resources in WMNs, such as file servers, file transfer protocol servers, etc. The WMN backbone is a collection of static wireless mesh routers. Traffic loads between the wired network and mobile users in mesh clients are transmitted by the WMN backbone in a multihop manner. Mesh clients can connect to the WMN backbone by establishing either wired or wireless links with mesh routers. WMN architecture as shown i

Biochemical Discrimination between Selenium and Sulfur 2: Mechanistic Investigation of the Selenium Specificity of Human Selenocysteine Lyase

Selenium is an essential trace element incorporated into selenoproteins as selenocysteine. Selenocysteine (Sec) lyases (SCLs) and cysteine (Cys) desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys, respectively, and generally accept both substrates. Intriguingly, human SCL (hSCL) is specific for Sec even though the only difference between Sec and Cys is a single chalcogen atom

Structural bases for the interaction of frataxin with the central components of iron–sulphur cluster assembly

Reduced levels of frataxin, an essential protein of as yet unknown function, are responsible for causing the neurodegenerative pathology Friedreich's ataxia. Independent reports have linked frataxin to iron–sulphur cluster assembly through interactions with the two central components of this machinery: desulphurase Nfs1/IscS and the scaffold protein Isu/IscU. In this study, we use a combination of biophysical methods to define the structural bases of the interaction of CyaY (the bacterial orthologue of frataxin) with the IscS/IscU complex. We show that CyaY binds IscS as a monomer in a pocket between the active site and the IscS dimer interface. Recognition does not require iron and occurs through electrostatic interactions of complementary charged residues. Mutations at the complex interface affect the rates of enzymatic cluster formation. CyaY binding strengthens the affinity of the IscS/IscU complex. Our data suggest a new paradigm for understanding the role of frataxin as a regulator of IscS functions

Structural Basis for Fe–S Cluster Assembly and tRNA Thiolation Mediated by IscS Protein–Protein Interactions

Crystal structures reveal how distinct sites on the cysteine desulfurase IscS bind two different sulfur-acceptor proteins, IscU and TusA, to transfer sulfur atoms for iron-sulfur cluster biosynthesis and tRNA thiolation

The persistent shadow of the supermassive black hole of M 87

In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M 87. These images reveal a ring with a southerly brightness distribution and a diameter of ∼42 μas, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear EHT observations provide independent snapshots of the horizon-scale emission, allowing us to confirm the persistence, size, and shape of the black hole shadow, and constrain the intrinsic structural variability of the accretion flow. We have confirmed the presence of an asymmetric ring structure, brighter in the southwest, with a median diameter of 43.3−3.1+1.5 μas. The diameter of the 2018 ring is remarkably consistent with the diameter obtained from the previous 2017 observations. On the other hand, the position angle of the brightness asymmetry in 2018 is shifted by about 30° relative to 2017. The perennial persistence of the ring and its diameter robustly support the interpretation that the ring is formed by lensed emission surrounding a Kerr black hole with a mass ∼6.5 × 109 M⊙. The significant change in the ring brightness asymmetry implies a spin axis that is more consistent with the position angle of the large-scale jet