768 research outputs found
Circular intensity differential scattering of light for biophotonics applications
No full textThis thesis demonstrate the application of a label-free, non-invasive biophysical method based on angle-resolved light scattering calculations to characterize different biological samples; virus particles, chromatin fiber, and hierarchical chiral polymers.
Chapter 1 provides an introduction on the foundation of electromagnetic theory, light scattering phenomenon, Mueller scattering matrix and its applications to characterize various samples based on numerical simulations and experimental measurements. A numerical method to calculate light scattering quantities, discrete dipole approximation (DDA) method is discussed. In this thesis we have performed the electromagnetic scattering calculations using the DDA method implemented as ADDA code.
Chapter 2 demonstrates the angle-resolved circularly polarized light scattering calculations to characterize virus model particles. A coronavirus particle is modeled as having a spherical shaped envelope with cylindrical spikes projected from the envelope surface, and the single-stranded RNA genome polymer has been mimicked with a toroidal helix. The influence of genome polymer packaged as a standard helix in the virion core is also demonstrated. We investigated four different electromagnetic models: (i) a nucleated sphere with spikes that is a coronavirus particle, (ii) a nucleated sphere with no spikes, (iii) a homogeneous sphere, and (iv) a respiratory fluid containing a virus particle. The angular pattern of scattered circularly polarized light, the circular intensity differential scattering of light (CIDS), served as a particle's signature. This scattering signature is found sensitive to the chiral parameters that reveal information about the particles. The effect of changes in the RNA polymer, changes in its packaging, number of turns, handedness, and size are demonstrated on the scattering calculations. Additionally, the extinction efficiency, the depolarization ratio, the total scattered intensity, and the effect of changes in the wavelength of incident light on these scattering quantities are investigated. This biophysical method can offer a label-free identification of virus particles and can help understand their interaction with light.
Chapter 3 focus on the the characterization of chromatin organization. Understanding the structural organization of chromatin is essential to comprehend the gene functions. The chromatin
organization changes in the cell cycle, and it conforms to various compaction levels. We investigated a chromatin solenoid model with nucleosomes shaped as cylindrical units arranged in a helical array. The solenoid with spherical-shaped nucleosomes was also modeled. The changes in chiral structural parameters of solenoid induced different compaction levels of chromatin fiber. We calculated the angle-resolved scattering of circularly polarized light to probe the changes in the organization of chromatin fiber in response to the changes in its chiral parameters. The electromagnetic scattering calculations were performed using discrete dipole approximation (DDA). In the chromatin structure,
nucleosomes have internal interactions that affect chromatin compaction. The merit of performing computations with DDA is that it takes into account the internal interactions. We demonstrated sensitivity of the scattering signal's angular behavior to the changes in these chiral parameters: pitch, radius, the handedness of solenoid, number of solenoid turns, the orientation of solenoid, the orientation of nucleosomes, number of nucleosomes, and shape of nucleosomes. These scattering calculations can potentially benefit applying a label-free polarized-light-based approach to characterize chromatin DNA and chiral polymers at the nanoscale level.
Chapter 4 demonstrates the differential scattering of circularly polarized light to characterize the macromolecular structures consisting of hierarchical chirality. We modeled the B-DNA structure composed of a double-helix and a base-pairs helical structure. The angle-resolved scattering of circularly polarized light calculated for the B-DNA shows the additive behavior of the scattering signal contributed from the two individual chirality levels of B-DNA structure, a double-helix and a base-pairs helix. This additive behavior of angle-resolved scattering signal has also been demonstrated for other macromolecular structures comprising different chirality levels; a biological cell is also mimicked as a nucleated sphere, a sphere with a helical nucleus in its core. The individual chiral features of a structure add up to the angle-resolved scattering signal of circularly polarized light produced by the parent structure. These electromagnetic wave scattering calculations can offer a label-free approach to characterize chiral macromolecular structures with hierarchical chirality
HERStory Makers 2022: Shirin Ashraf
No full textShirin Ashraf is a postdoctoral research associate at the University of Glasgow studying novel viruses from Uganda and other parts of Africa. She took part in HERStory Makers 2022.What is HERStory Makers?HERStory Makers is a social media competition for female-identifying early career researchers to share their research, their career journeys, and to inspire the next generation. Winners are selected by public vote. HERStory Makers is also part of EXPLORATHON, Scotland's contribution to European Researchers' Night.In 2022-23, EXPLORATHON was supported by the Engineering & Physical Sciences Research Council [grant number EP/X020894/1].Author contributions to contentShirin Ashraf conceived, planned, and recorded the video content. Kirsty Ross edited the video content to insert HERStory Maker credits, add subtitles, and maintain video length below Twitter/X limit of 2 mins and 20 secs, prior to scheduling the social media posts.</p
PROFILE OF CHILDREN PRESENTS WITH TETANUS AT NISHTAR HOSPITAL MULTAN
No full textDr. Hafiza Ramisha Ashraf, Dr. Sajjad Hussain Moon* and Dr. Waseem Ahma
Multispectral Stokes/Mueller Detection Module for Multiphoton/Fluorescence Confocal Scanning Imaging Microscopy
No full textMueller-matrix microscopy as proved to be an important tool to extract the full optical properties of a sample, without labelling or a priori knowledge of the sample. It consists in studying the interaction between the polarized light and the medium, which can be summarized in a single 4x4 elements Mueller-matrix. In this way, this method gives access to physical parameters such as dichroism, birefringence and scattering, from the macro-to the microscopic scale. More particularly, it has been proven its efficiency for quantitative methods for materials science and biomedical diagnosis. Among these techniques, we have developed a versatile Stokes-vector/Mueller-matrix detection module, implemented in a commercial confocal fluorescence microscope. In our previous study, we have demonstrated its capability to image small animal (zebrafish) and biological fibers (collagen and muscle) at 808nm excitation/collection ..
IoD swarms collision avoidance via improved particle swarm optimization
No full textDrones flights have been investigated widely. In the presence of high density and complex missions, collision avoidance among swarm of drones and with environment obstacles becomes a challenging task and indispensable. This paper aims to enhance the optimality and rapidity of three dimensional IoD path generation by improving the particle swarm optimization (PSO) algorithm. The improvements include using chaos map logic to initialize the population of PSO. Also, adaptive mutation is utilized to balance local and global search. Then, the inactive particles are replaced by new fresh particles to push the solution toward global optimal. Furthermore, Monte Carlo simulation is carried out and the results are compared with slandered PSO and with recent work CIPSO. The results exhibit significant improvement in convergence speed as well as optimal solution which prove the ability of proposed method to generate safety path for IoD formation without collision with terrain obstacle and among drones.The authors would like to acknowledge the support of the department of the computer engineering at King Fahd University of Petroleum and Minerals for this work.Ahmed, G (corresponding author), King Fahd Univ Petr & Minerals, Comp Engn Dept, Dhahran, Saudi Arabia.
[email protected]; [email protected]; [email protected]; [email protected]
Automating the determination of wave speed using the pu-loop method
No full textThe PU-loop (pressure-velocity loop) is a method for determining wave speed and relies on the linear relationship between the pressure and velocity in the absence of reflected waves. This linearity of the PU-loop during early systole, which is directly related to wave speed, has always been established by eye. This paper presents a new technique that establishes this linearity and thus determining wave speed online. Pressure and flow were measured in the ascending aorta of 11 anesthetised dogs. The slope of the PU-loop, indicating wave speed was determined by eye and by using the new technique. The difference between the slopes of the two methods is in the order of 3%. The new technique is convenient and allows for the online assessment of wave speed, which could be used as a bedside tool for the assessment of arterial compliance
Keratoconus : current and future state-of-the-art
Get PDFThis book provides a practical guide to the most recent advances in the diagnostic management of corneal ectasia. Clear, concise chapters address new standardized nomograms of treatment of early progressive ectasia, new epithelium on future crosslinking with and without oxygen supplement, customized protocols, laser assisted corneal regularization protocols and the new femtolaser assisted lamellar corneal transplant. Clinicians and surgeons seeking a go-to guide on the topic of corneal ectasia will find this book to be an essential resource for the latest developments and predicted future trends in the field. © The Editor(s) (if applicable) and The Author(s)
Flood management, characterization and vulnerability analysis using an integrated RS-GIS and 2D hydrodynamic modelling approach: The case of Deg Nullah, Pakistan
No full textOne-dimensional (1D) hydraulic models have been extensively used to conduct flood simulations for investigating flood depth and extent maps. However, the 1D models cannot simulate many other flood characteristics, such as flood velocity, duration, arrival time and recession time when the flow is not restricted within the channel. These flood characteristics cannot be disregarded as they play an important role in developing flood mitigation and evacuation strategies. This study formulates a two-dimensional (2D) hydrodynamic model combined with remote sensing (RS) and geographic information system (GIS) approach to generate additional flood characteristic maps that cannot be produced with 1D models. The model was applied to a transboundary river of Deg Nullah in Pakistan to simulate an extreme flood event experience in 2014. The flood extent images from the moderate resolution imaging spectroradiometer (MODIS) and observed flood extents were used to evaluate the model performance. Moreover, an entropy distance-based approach was proposed to facilitate the integrated multivariate flood vulnerability classification. The simulated 2D flood modeling results showed a good agreement with the flood extents registered by MODIS and the observed ones. The northwest parts of Deg Nullah near Seowal, Dullam Kahalwan and Zafarwal were the most vulnerable areas due to high flood depths and prolonged flooding duration. Whereas high flood velocities, short flood arrival time, prolonged flood duration and recession times were observed in the upper reach of Deg Nullah thereby making it the most susceptible, critical and vulnerable region to flooding events.Higher Education Commission of Pakista
Correction to: Growth Factors and Neuroglobin in Astrocyte Protection Against Neurodegeneration and Oxidative Stress (Molecular Neurobiology, (2019), 56, 4, (2339-2351), 10.1007/s12035-018-1203-9)
No full textThe original version of this article unfortunately contained a typo error. The name of author “Ghulam Md Ashrad” should be written as “Ghulam Md Ashraf”. The authors hereby correct the name as displayed above. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Universidad Autónoma de Chil
IMR 665: Management of Audio Visual Records & Archives. Individual assignment: Article summary / Zuheir Ashraf Zakaria
Get PDFArticle on:
Article 1 - “Audio-visual piracy: towards a study of the underground networks of cultural globalization”
Article 2 - “Audiovisual Piracy, Informal Economy, and Cultural Globalization”
This article summary comprises of two article of the same author with a full name of Tristan Mattelart. The first article published on 2009 entitled; “Audio-visual piracy: towards a study of the underground networks of cultural globalization”, while the second article that were published on the year 2011 entitled; “Audiovisual Piracy, Informal Economy, and Cultural Globalization”. These two article consist of 19 and 16 pages consecutively. Both of these article discuss the cultural industries threat it presents to the western world and the underground networks it related to. Although both of these articles discuss the steps taken mainly by the US government to combat these problem in order to protect their intellectual property rights of US companies. Since both of the article are being authored by the same author, we can see that the later article; “Audiovisual Piracy, Informal Economy, and Cultural Globalization” often mention and cite the older article as a reference
- …
