Physics Commons^™

Spectral Cross Correlation As A Supervised Approach For The Analysis Of Complex Raman Datasets: The Case Of Nanoparticles In Biological Cells, Mark Keating, Franck Bonnier, Hugh Byrne

Articles

Spectral Cross-correlation is introduced as a methodology to identify the presence and subcellular distribution of nanoparticles in cells. Raman microscopy is employed to spectroscopically image biological cells previously exposed to polystyrene nanoparticles, as a model for the study of nano-bio interactions. The limitations of previously deployed strategies of K-means clustering analysis and principal component analysis are discussed and a novel methodology of Spectral Cross Correlation Analysis is introduced and compared with the performance of Classical Least Squares Analysis, in both unsupervised and supervised modes. The previous study demonstrated the feasibility of using Raman spectroscopy to map cells and identify polystyrene …

The Effect Of Genetic Background And Dose On Non-Targeted Effects Of Radiation, Sarah Irons, Virginia Sierra, Deborah Bowler, Kim Chapman, Stefania Militi, Fiona Lyng, Munira Kadhim

Articles

Purpose: This work investigates the hypothesis that genetic background plays a significant role in the signalling mechanisms underlying induction and perpetuation of genomic instability following radiation exposure.

Materials and methods: Bone marrow from two strains of mice (CBA and C57) were exposed to a range of X-ray doses (0, 0.01, 0.1, 1 and 3 Gy). Different cellular signalling endpoints: Apoptosis, cytokine levels and calcium flux, were evaluated at 2 h, 24 h and 7 d post-irradiation to assess immediate and delayed effects.

Results: In CBA (radiosensitive) elevated apoptosis levels were observed at 24 h post X-irradiation, and …

Evaluation Of Cirs String Doppler Phantom As A Test Tool For Use In A Doppler Ultrasound Quality Assurance Program, Jacinta Browne, S. Cournane, Andrew Fagan

Articles

Ultrasound Doppler systems are routinely used to perform blood flow velocity measurements which assist in the clinical assessment and diagnosis of vascular. Doppler measurements of peak velocities for vascular applications provide an indication of the degree of the stenosis which will ultimately assist in deciding how a patient is managed. It is imperative that Doppler systems are capable of accurately measuring blood flow velocities to ensure correct diagnosis and appropriate patient treatment; therefore such systems should be evaluated regularly as part of a Quality Assurance program. Although a range of Doppler test phantoms have been developed for quality control (QC) …

Modifications Of Existing Doppler Ultrasound Test Devices For The Evaluations Of Colour Doppler Spatial Resolution, Nisma Arshad, Jacinta Browne

Articles

No abstract provided.

Characterisation Of The Colour Doppler "Twinkle" Artefact, Deirdre Cassidy, Andrew Fagan, Jacinta Browne

Articles

This investigation involved the development of a range of Colour Doppler Twinkle Artefact phantoms to characterise and quantify the “Twinkle” artefact which is often present when an irregular structure is encountered in the imaged field of view. The artefact occurs in both colour and power Doppler ultrasound imaging and manifests as a false depiction of colour velocity information in stationary soft tissue and therefore can cause significant misdiagnosis of areas of flow within the patient. It has been hypothesised that it is generated due to a strongly reflecting medium composed of individual reflectors and therefore becomes a clinical concern when …

Search For A T-Odd, P-Even Triple Correlation In Neutron Decay, T. E. Chupp, R. L. Cooper, K. P. Coulter, S. J. Freedman, B. K. Fujikawa, A. Garcia, Gordon L. Jones, H. P. Mumm, J. S. Nico, A. K. Thompson, C. A. Trull, F. E. Wietfeldt, J. F. Wilkerson

Articles

Background: Time-reversal-invariance violation, or equivalently CP violation, may explain the observed cosmological baryon asymmetry as well as indicate physics beyond the Standard Model. In the decay of polarized neutrons, the triple correlation D⟨⃗Jn⟩/Jn⋅(⃗βe׈pν) is a parity-even, time-reversal-odd observable that is uniquely sensitive to the relative phase of the axial-vector amplitude with respect to the vector amplitude. The triple correlation is also sensitive to possible contributions from scalar and tensor amplitudes. Final-state effects contribute to D at the level of 10−5 and can be calculated with a precision of 1% or better.

Purpose: We have improved the sensitivity to T-odd, P-even …

Comparative Review Of Imaging Methods Used For Diagnosing Renal Artery Stenosis (Ras), Deirdre King, Carmel Moran, Jacinta Browne

Articles

This comparative review examines the efficacy of different imaging methods to detect and quantify renal artery stenosis (RAS). Detection of RAS is important because it can lead to renovascular hypertension which is the most common form of secondary hypertension. Furthermore, it is important that a RAS is detected as early as possible as it is a potentially correctable cause of hypertension.¹ If detected at an early stage RAS can potentially be treated using a minimally invasive drug treatment regimen rather than the more invasive percutaneous transluminal renal angioplasty without or with stent placement or surgery. Currently there are a …

Stiefel And Grassmann Manifolds In Quantum Chemistry, Eduardo Chiumiento, Michael Melgaard

Articles

We establish geometric properties of Stiefel and Grassmann manifolds which arise in relation to Slatertype variational spaces in many-particle Hartree-Fock theory and beyond. In particular, we prove thatthey are analytic homogeneous spaces and submanifolds of the space of bounded operators on the single-particle Hilbert space. As a by-product we obtain that they are complete Finsler manifolds. These geometric properties underpin state-of-the-art results on existence of solutions to Hartree-Fock type equations.

Kinetic Studies Of The Photo-Degradation Of Poly Arylene Vinylenes, Luke O'Neill, Patrick Lynch, Niamh Mcgoldrick, Hugh Byrne, Mary Mcnamara

Articles

The kinetics of the degradation of a homologous series of Poly phenylene vinylenes in which the phenylene units of the PPV structure are systematically substituted by naphthyl and anthyrl units is presented. Degradation is monitored according to the decay of the long wavelength absorption maximum upon illumination with UV radiation. Compared to Toluene solution, the photo-degradation is seen to be accelerated in Chloroform solution. All decays are fitted with first order kinetics. It is found that all substitutions improve the stability of the vinylene polymers against decay. In particular the highly electro-negative naphthyl group serves to drastically increase the stability …

Impaired Clearance And Enhanced Pulmonary Inflammatory/Fibrotic Response To Carbon Nanotubes In Myeloperoxidase-Deficient Mice, Aidan Meade, Anna Shvedova, Alexandr Kapralov, Wei Hong Feng, Elena Kisin, Ashley Murray, Robert Mercer, Claudette St. Croix, Megan Lang, Simon Watkins, Nagarjun Konduru, Brett Allen, Jennifer Conroy, Gregg Kotchey, Bashir Mohamed, Yuri Volkov, Alexander Star, Bengt Fadeel, Valerian Kagan

Articles

Advancement of biomedical applications of carbonaceous nanomaterials is hampered by their biopersistence and proinflammatory action in vivo. Here, we used myeloperoxidase knockout B6.129X1-MPO (MPO k/o) mice and showed that oxidation and clearance of single walled carbon nanotubes (SWCNT) from the lungs of these animals after pharyngeal aspiration was markedly less effective whereas the inflammatory response was more robust than in wild-type C57Bl/6 mice. Our results provide direct evidence for the participation of MPO – one of the key-orchestrators of inflammatory response – in the in vivo pulmonary oxidative biodegradation of SWCNT and suggest new ways to control the biopersistence of …

Assessment Of An Osteoblast-Like Cell Line As A Model For Human Primary Osteoblasts Using Raman Spectroscopy, Lindsay Mcmanus, Franck Bonnier, George Burke, Brian Meenan, Adrian Boyd, Hugh Byrne

Articles

Raman spectroscopy is employed to determine the suitability of the U20S osteoblast-like cell line for use as a model for human primary osteoblasts, with emphasis on the ability of these cell types to replicate their tissue of origin. It was found that both cell types demonstrated early stage mineral deposition that followed significantly different growth patterns. Analysis of the growth pattern and spectral data from primary cells revealed increasing bone quality ratios and a high crystallinity, consistent with previous reports. Conversely the investigation of the U20S osteoblast-like cell line provided evidence of dense multilayered mineralised regions that corresponded more closely …

Review Of Ultrasound Elastography Quality Control And Training Test Phantoms, S. Cournane, Andrew Fagan, Jacinta Browne

Articles

While the rapid development of ultrasound elastography techniques in recent decades has sparked its prompt implementation in the clinical setting adding new diagnostic information to conventional imaging techniques, questions still remain as to its full potential and efficacy in the hospital environment. A limited number of technical studies have objectively assessed the full capabilities of the different elastography approaches, perhaps due, in part, to the scarcity of suitable tissue-mimicking materials and appropriately designed phantoms available. Few commercially-available elastography phantoms possess the necessary test target characteristics or mechanical properties observed clinically, or indeed reflect the lesion-to-background elasticity ratio encountered during clinical …

Determination Of The Levitation Limits Of Dust Particles Within The Sheath In Complex Plasma Experiments, Angela Douglass, Victor Land, Ke Qiao, Lorin Matthews, Truell Hyde

Articles

Experiments are performed in which dust particles are levitated at varying heights above the powered electrode in a radio frequency plasma discharge by changing the discharge power. The trajectories of particles dropped from the top of the discharge chamber are used to reconstruct the vertical electric force acting on the particles. The resulting data, together with the results from a self-consistent fluid model, are used to determine the lower levitation limit for dust particles in the discharge and the approximate height above the lower electrode where quasineutrality is attained, locating the sheath edge. These results are then compared with current …

Identifying And Localizing Intracellular Nanoparticles Using Raman Spectroscopy, Jennifer Dorney, Franck Bonnier, Amaya Garcia, Alan Casey, Gordon Chambers, Hugh Byrne

Articles

Raman microscopy is employed to spectroscopically image biological cells previously exposed to fluorescently labelled polystyrene nanoparticles and, in combination with K-means clustering and Principal Component Analysis (PCA), is demonstrated to be capable of localising the nanoparticles and identifying the subcellular environment based on the molecular spectroscopic signatures. The neutral nanoparticles of 50 nm or 100 nm, as characterised by dynamic light scattering, are shown to be non-toxic to a human lung adenocarcinoma cell-line (A549), according to a range of cytotoxicity assays including Neutral Red, Alamar Blue, Coomassie Blue and (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Confocal fluorescence microscopy identifies intracellular fluorescence due to …

Quantitative Reagent-Free Detection Of Fibrinogen Levels In Human Blood Plasma Using Raman Spectroscopy, Kelvin Poon, Fiona Lyng, Peter Knief, Orla L. Howe, Aidan Meade, James Curtin, Hugh Byrne, Joseph Vaughan

Articles

Fibrinogen assays are commonly used as part of clinical screening tests to investigate haemorrhagic states, for detection of disseminated intravascular coagulation and as a predictor of a variety of cardiovascular events. The Clauss assay, which measures thrombin clotting time, is the most commonly used method for measuring fibrinogen levels. Nevertheless, inconsistencies are present in inter-manufacturer reagent sources, calibration standards and methodologies. Automated coagulation analysers, which measure changes in optical density during the prothrombin time (PT-Fg), have found use in many hospitals. However, the PT-Fg method is found to give falsely elevated values due to varying choices of calibrants, reagents and …

Photonic Crystal Fiber Interferometer For Dew Detection, Jinesh Mathew, Yuliya Semenova, Gerald Farrell

Articles

A novel method for dew detection based on photonic crystal fiber (PCF) interferometer that operates in reflection mode is presented in this paper. The fabrication of the sensor head is simple since it only involves cleaving and fusion splicing. The sensor shows good sensitivity to dew formation with a large wavelength peak shift of the interference pattern at the onset of dew formation. The device’s response to ambient humidity and temperature are also studied and reported in this paper. From our experiment it is also concluded that by attaching a thermoelectric cooler with temperature feedback, the sensor head demonstrated can …

Comparison Of Micro- And Nanoscale Fe+3-Containing (Hematite) Particles For Their Toxicological Properties In Human Lung Cells In Vitro, Kunal Bhattacharya, Eik Hoffmann, Roel Schins, Jens Boertz, Eva-Maria Prantl, Gerrit Alink, Hugh Byrne, Thomas Kuhlbusch, Qamar Rahman, Hartmut Wiggers, Christof Schulz, Elke Dopp

Articles

The specific properties of nanoscale particles, large surface-to-mass ratio and highly reactive surfaces, have increased their commercial application in many fields. However, the same properties are also important for the interaction and bio-accumulation of the non-/biodegradable nanoscale particles in a biological system and are a cause for concern. Hematite (α-Fe2O3), being a mineral form of Fe(III) oxide, is one of the most used iron oxides besides magnetite. The aim of our study was the characterization and comparison of biophysical reactivity and toxicological effects of α-Fe2O3 nano- (d < 100 nm) and microscale (d < 5 μm) particles in human lung cells. Our study demonstrates that the surface reactivity of nanoscale α-Fe2O3 differs to that of microscale particles with respect to the state of agglomeration, radical formation potential, and cellular toxicity. The presence of proteins in culture medium and agglomeration were found to affect the catalytic properties of the hematite nano- and microscale particles. Both the nano- and microscale α-Fe2O3 particles were actively taken up by human lung cells in vitro, although, they were not found in the nuclei and mitochondria. …

Nonlinear Optical Properties Of Carbon Nanotube Hybrids In Polymer Dispersions, Jun Wang, Kang-Shyang Liao, Daniel Früchtl, Ying Tian, Aisling Gilchrist , T, Nigel Alley, Enrico Andreoli, Brad Aitchison, Albert Nasibulin, Hugh Byrne, Esko I. Kauppinen, Long Zhang, Werner Blau, Seamus Curran

Articles

A series of double-walled carbon nanotubes (DWNTs) and multi-walled nanotubes (MWNTs) functionalized with selected organic chromophores, fluorescein 5(6)-isothiocyanate (FITC), rhodamine B isothiocyanate (RITC) and fullerene (C₆₀) were synthesized by covalently linking these electron-donor groups to the metallic nanotubes. These versatile carbon nanotube composites show remarkable nonlinear optical (NLO) performance, due to a merged effect of the complementary NLO characteristics of the moieties of the composites. The hybrids were characterized by UV-Vis spectroscopy and Raman spectroscopy. Evidence suggests charge transfer species are formed between the chromophores and the nanotubes. The optical limiting performance of the DWNT, MWNT hybrids and …

Analysis Of Human Skin Tissue By Raman Microspectroscopy: Dealing With The Background, Franck Bonnier, Syed Mehmood Ali, Peter Knief, Helen Lambkin, Kathleen Flynn, Vincent Mcdonagh, Claragh Healy, Thomas Lee, Fiona Lyng, Hugh Byrne

Articles

Raman microspectroscopy is widely used for molecular characterisation of tissue samples. Nevertheless, when working in vitro on tissue sections, the presence of a broad background to the spectra remains problematic and its removal requires advanced methods for pre-processing of the data. To date, research efforts have been primarily devoted to development of techniques of statistical analysis to extract the relevant information contained in the spectra. However, few attempts have been made to understand the origin of the background and to improve the protocols used for the collection of Raman spectra that could lead to the reduction or elimination of the …

Impaired Cleanance And Enhanced Pulmonary Inflammatory/Fibrotic Response To Carbon Nanotubes In Myeloperoxidase-Deficient Mice, Anna A. Shvedova, Alexandr A. Kapralov, Wei Hong Feng, Elena R. Kisin, Ashley R. Murray, Robert R. Mercer, Claudette M. St. Croix, Megan A. Lang, Simon C. Watkins, Nagarjun V. Konduru, Brett L. Allen, Jennifer Conroy, Gregg P. Kotchey, Bashir M. Mohamed, Aidan Meade, Yuri Volkov, Alexander Star, Bengt Fadeel, Valerian E. Kagan

Articles

Advancement of biomedical applications of carbonaceous nanomaterials is hampered by their biopersistence and pro-inflammatory action in vivo. Here, we used myeloperoxidase knockout B6.129X1-MPO (MPO k/o) mice and showed that oxidation and clearance of single walled carbon nanotubes (SWCNT) from the lungs of these animals after pharyngeal aspiration was markedly less effective whereas the inflammatory response was more robust than in wild-type C57Bl/6 mice. Our results provide direct evidence for the participation of MPO – one of the key-orchestrators of inflammatory response – in the in vivo pulmonary oxidative biodegradation of SWCNT and suggest new ways to control the biopersistence …

Characterisation Of The Acoustic Output Of Three Sonoporation Drug Delivery Ultrasound Systems Using An Acoustic Radiation Force Balance, Tapihwa Mabvaro, Jacinta Browne

Articles

No abstract provided.

Effect On Diagnostic Image Quality Of 3d Warping Registration Algorithms For Mr Angiography In The Lower Legs, Andrew Fagan, Daniel Foley, Jacinta Browne, Barry Sheane, Dearbhail O'Driscoll, Niall Sheehy, James Meaney

Articles

No abstract provided.

Quantum Geometry Phenomenology: Angle And Semiclassical States, Seth Major

Articles

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used to develop a model of angular corrections to local, continuum flat-space 3-geometries. The physical effects involve neither breaking of local Lorentz invariance nor Planck scale suppression, but rather only involve the combinatorics of SU(2) recoupling. Bhabha scattering is discussed as an example of how the effects might be observationally accessible.

Plane Gravitational Waves And Loop Quantization, F. Hinterleitner, Seth Major

Articles

Starting from the polarized Gowdy model in Ashtekar variables, the Killing equations characteristic for plane-fronted parallel gravitational waves are introduced in part as a set of first-class constraints, in addition to the standard ones of General Relativity. These constraints are expressed in terms of quantities that have an operator equivalent in Loop Quantum Gravity, making plane wave space-times accessible to loop quantization techniques.

A First Course In Loop Quantum Gravity, Seth Major

Articles

No abstract provided.

The Effects Of Fatty Desposits On The Accuracy Of The Fibroscan Liver Transient Elastography Ultrasound System, S. Cournane, Jacinta Browne, Andrew Fagan

Articles

A new generation of ultrasound transient elastography (TE) systems have emerged which exploit the well-known correlation between the liver’s pathological and mechanical properties through measurements of the Young’s elastic modulus; however, little work has been carried out to examine the effect that fatty deposits may have on the TE measurement accuracy. An investigation was carried out on the effects on the measurement accuracy of a transient elastography ultrasound system, the Fibroscan®, caused by overlaying fat layers of varying thickness on healthy liver-mimicking phantoms, simulating in vivo conditions for obese patients. Furthermore, a steatosis effect similar to that in non-alcoholic fatty …

Effect Of Motion On The Adc Quantification Accuracy Of Whole-Body Dwibs, A. Stone, Jacinta Browne, Brian Lennon, James Meaney, Andrew Fagan

Articles

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Diffusion-weighted whole-body imaging with background body signal subtraction was introduced as a qualitative approach to detecting metastases in the body. A liver-mimicking phantom with embedded tumours that could be moved to replicate respiratory motion was developed to assess its ability to accurately quantify ADC values.

RESULTS:

Mean tumour ADC values were unaltered by the motion; however, a significant (p < 0.05) increase in the spread of ADC values was measured, even for relatively large tumours.

CONCLUSIONS:

These findings may be of significance in cancer therapy monitoring where subtle changes in ADC histograms may reveal changes in tumour heterogeneity.

New Non-Toxic Holographic Photopolymer Material, Dervil Cody, Izabela Naydenova, Emilia Mihaylova

Articles

There is an increasing need for environmentally friendly holographic recording materials which can be produced in bulk with little risk to the health of workers in manufacturing. This is why the development of non-toxic photopolymer materials is crucial, and has attracted attention in recent years. Composition and preliminary characterization of a new non-toxic photopolymer material are presented. It operates well at a range of spatial frequencies, and achieves diffraction efficiencies and refractive index modulation comparable to the known acrylamide-based photopolymers.

The Driving Forces Of Change In Energy-Related Co2 Emissions In Ireland: A Multi-Sectoral Decomposition From 1990 To 2007, Tadhg O'Mahony, Peng Zhou, John Sweeney

Articles

Ireland recorded significant growth in energy-related carbon emissions from 1990 to 2007 as the country underwent rapid economic development. Using the LMDI decomposition analysis method, this paper aims to identify and analyse the driving forces of CO2 emissions in eleven final energy consuming sectors. This multi-sectoral analysis is based on four economic sectors, the residential sector and gives a detailed representation of transport in keeping with UNFCCC recommendations. Scale, structure and intensity effects are explored and substantial heterogeneity in sectoral performance is observed. Scale growth in economic and transport activity was considerable. Some improvements in energy intensity were recorded in …