Physical Sciences and Mathematics Commons^™

Facing The Sun, Frank Prendergast, Muiris O'Sullivan, Ken Williams, Gabriel Cooney

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December 2017 marked 50 years since archaeologist Michael J. O’Kelly first observed the solar illumination of the burial chamber in the Neolithic passage tomb at Newgrange during the period of the winter solstice. O’Kelly subsequently recorded direct sunlight entering Newgrange through the ‘especially contrived slit which lies under the roof-box at the outer end of the passage roof’ on 21 December 1969. The discovery of this historic phenomenon, dating back over 5,000 years, captured the public interest and imagination at that time and ever since. In this major article published in the Winter 2017 edition of Archaeology Ireland (date of …

Probability Models And Compounding, David L. Farnsworth, James E. Marengo

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We present the case that the ideas contained in a particular sequence of formulas are important in probability and statistics. The synthesis offered by the concepts in the sequence can be very valuable. Facility with this sequence and its underpinnings should be in the skill set of anyone who uses or studies probability or statistics. For illustrative purposes, we give applications to mixture distributions and Bayesian analyses.

Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Doran

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We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method, we …

Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Breen

Articles

We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method, we …

A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond

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This paper applies boundary layer theory to the process of drug dissolution in the USP (United States Pharmacopeia) Flow Through Apparatus. The mass transfer rate from the vertical planar surface of a compact within the device is examined. The theoretical results obtained are then compared with those of experiment. The paper also examines the effect on the dissolution process caused by the interaction between natural and forced convection within the apparatus and the introduction of additional boundaries.

The Evaluation Of The Effect Of Strain Limits On The Physical Properties Of Magnetorheological Elastomers Subjected To Uniaxial And Biaxial Cyclic Testing., Dave Gorman, Niall Murphy, Ray Ekins, Stephen Jerrams

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Magnetorheological Elastomers (MREs) are “smart” materials whose physical properties are altered by the application of magnetic fields. In a previous study by the authors [1], variations in the physical properties of MREs have been evaluated when subjected to a range of magnetic field strengths for both uniaxial and biaxial cyclic tests. By applying the same magnetic field to similar samples, this paper investigates the effect of both the upper strain limit and the strain amplitude on the properties of MREs subjected to cyclic fatigue testing. As the magnetorheological (MR) effect is due to the dipole-dipole interactions of the …

A Geometric Derivation Of The Irwin-Hall Distribution, James E. Marengo, Lucas Stefanic, David L. Farnsworth

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The Irwin-Hall distribution is the distribution of the sum of a finite number of independent identically distributed uniform random variables on the unit interval. Many applications arise since round-off errors have a transformed Irwin-Hall distribution and the distribution supplies spline approximations to normal distributions. We review some of the distribution’s history. The present derivation is very transparent, since it is geometric and explicitly uses the inclusion-exclusion principle. In certain special cases, the derivation can be extended to linear combinations of independent uniform random variables on other intervals of finite length.The derivation adds to the literature about methodologies for finding distributions …

Broadband Acoustic Measurement Of The Agar-Based Tissue Mimicking Material – A Longitudinal Study, Adela Rabell-Montiel, Jacinta Browne, Stephen Pye, Tom Anderson, Carmel Moran

Articles

Commercially available ultrasound quality assurance test phantoms rely upon the long-term acoustic stability of tissue-mimicking-materials (TMMs). The measurement of the acoustic properties can be technically challenging and it is important to ensure its stability. The standard technique is to film-wrap samples of TMM and to measure the acoustic properties in a water bath. In this study, a modified technique is proposed whereby the samples of TMM are measured in a preserving fluid that is intended to maintain their characteristics. The acoustic properties were evaluated using a broadband pulse-echo substitution technique over the frequency range of 4.5 – 50 MHz at …

Formulation, Characterisation And Stability Assessment Of A Food Derived 1 Tripeptide, Leucine-Lysine-Proline Loaded Chitosan Nanoparticles, M.K. Danish, Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Sinead Ryan

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The chicken or fish derived tripeptide, Leucine-Lysine-Proline (LKP), inhibits the Angiotensin Converting Enzyme and may be used as an alternative treatment for pre-hypertension. However, it has low permeation across the small intestine. The formulation of LKP into a nanoparticle (NP) has the potential to address this issue. LKP-loaded NPs were produced using an ionotropic gelation technique, using chitosan (CL113). Following optimisation of unloaded NPs, a mixture amount design was constructed using variable concentration of CL113 and tripolyphosphate at a fixed LKP concentration. Resultant particle sizes ranged from 120-271 nm, zeta potential values from 29-37 mV and polydispersity values from 0.3-0.6. …

Antifungal Potential Of Copper(Ii), Manganese(Ii) And Silver(I) 1,10-Phenanthroline Chelates Against Multidrug-Resistant Fungal Species Forming The Candida Haemulonii Complex: Impact On The Planktonic And Biofilm Lifestyles, Rafael M. Gandra, Pauraic Mc Carron, Mariana F. Fernandes, Lívia S. Ramos, Thaís P. Mello, Ana Carolina Aor, Marta H. Branquinha, Malachy Mccann, Michael Devereux, André L. S. Santos

Articles

Candida haemulonii, Candida haemulonii var. vulnera and Candida duobushaemulonii, which form the C. haemulonii complex, are emerging etiologic agents of fungal infections known to be resistant to the most commonly used antifungals. The well-established anti-Candida potential ofmetal complexes containing 1,10-phenanthroline (phen) ligands encouraged us to evaluate different copper(II), manganese(II), and silver(I) phen chelates for their ability to inhibit planktonic growth and biofilm of C. haemulonii species complex. Two novel coordination complexes, {[Cu(3,6,9-tdda)(phen)2].3H2O.EtOH}n and [Ag2(3,6,9-tdda)(phen)4].EtOH (3,6,9-tddaH2 = 3,6,9-trioxaundecanedioic acid), were synthesized in a similar fashion to the other, previously documented, sixteen copper(II), manganese(II), and silver(I) chelates employed herein. Three isolates of …

Solid-Phase Peptide Synthesis Of Analogues Of The N-Terminus A-Ring Fragment Of The Lantibiotic Nisin: Replacements For The Dehydroalanine (Dha) Residue At Position 5 And The First Incorporation Of A Thioamide Residue, Kim Manzor, Keith Ó Proinsias, Fintan Kelleher

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A number of A-ring analogues of the lantibiotic nisin, containing replacements for the Dha at position 5, have been successfully prepared by solid-phase peptide synthesis. The Dha replacements include glycine, alanine, phenylalanine, serine and 1-aminocyclopropyl carboxylic acid (ACCa). The incorporation of a thioamide-isoleucine residue at position 4 is also described and is the first report of the preparation of a lantibiotic ring fragment containing a thioamide link.

Ultra-Filtration Of Human Serum For Improved Quantitative Analysis Of Low Molecular Weight Biomarkers Using Atr-Ir Spectroscopy, Franck Bonnier, Luis Felipe Cs. Carvalho, Matthew J. Baker, Hugh Byrne, Igor Chourpa

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Infrared spectroscopy is a reliable, rapid and cost effective characterisation technique, delivering a molecular finger print of the sample. It is expected that its sensitivity would enable detection of small chemical variations in biological samples associated with disease. ATR-IR is particularly suitable for liquid sample analysis and, although air drying is commonly performed before data collection, just a drop of human serum is enough for screening and early diagnosis. However, the dynamic range of constituent biochemical concentrations in the serum composition remains a limiting factor to the reliability of the technique. Using glucose as a model spike in human serum, …

Extraoral Maxillofacial Prosthesis Implant Retention Systems: A Critical Review., Hugh Byrne, Marina L. Pimentel

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Objectives: The purpose of this literature review is to provide information on the different available techniques for implant-supported prosthetic retention, which are bar-clip, o-ring or magnets. Through presenting the practitioner preferences reported in literature, although limited from strict comparison due to the heterogeneity of methodologies and studied individuals, this review aims to identify the choices for maxillofacial prosthesis implant retention systems, regarding patient comfort and good aesthetic outcome, as an aid to surgical and prosthetic planning for implant-supported extraoral maxillofacial prosthetics. With proper knowledge of each implant retention system, a practitioner can design a treatment plan which allows for a …

Industrial Grade 2d Molybdenum Disulphide (Mos2): An In-Vitro Exploration Of The Impact On Cellular Uptake, Cytotoxicity, And Inflammation, Caroline Moore, Hugh Byrne, Jonathan N. Coleman, Yuri Volkov, Jennifer Mcintyre

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The recent surge in graphene research, since its liquid phase monolayer isolation and characterization in 2004, has led to advancements which are accelerating the exploration of alternative 2D materials such as molybdenum disulphide (MoS2), whose unique physico-chemical properties can be exploited in applications ranging from cutting edge electronic devices to nanomedicine. However, to assess any potential impact on human health and the environment, the need to understand the bio-interaction of MoS2 at a cellular and sub-cellular level is critical. Notably, it is important to assess such potential impacts of materials which are produced by large scale production techniques, rather than …

Conformational Studies Of Gram-Negative Bacterial Quorum Sensing 3-Oxo N-Acyl Homoserine Lactone Molecules, Darren Crowe, Alan Nicholson, Adrienne Fleming, Ed Carey, Goar Sanchez-Sanz, Fintan Kelleher

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In their ¹H NMR spectra in CDCl₃ 3-oxo-N-acyl homoserine lactones (OHLs) show significant downfield chemical shifts of the amide N-H proton when compared to the parent N-acyl homoserine lactones (AHLs). NMR spectroscopic and DFT calculation studies have shown that this is most likely due to the presence of a stabilising intramolecular H-bond from the N-H to the 3-oxo group. The ¹H NMR spectra also show evidence for the enol tautomers and that the amount of enol present for a range of OHLs is 4.1-4.5% in CDCl₃ and 6.5-7.2% in CD₃CN. In …

Poisson Windowing, David L. Farnsworth

Articles

The statistical quality-control technique of windowing takes advantage of the additive property of the Poisson probability distribution and the geometry of the data. There are abundant applications of windowing to observations that naturally occur in arrays or that are produced in them, such as computer chips, which are manufactured many at a time on wafers. Standard statistical procedures are used.

Motor Preparation Rather Than Decision-Making Differentiates Parkinson’S Disease Patients With And Without Freezing Of Gait, John Butler, Conor Fearon, Isabelle Killane, Saskia M. Waechter, Richard B. Reilly, Timothy Lynch

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Objective: Freezing of gait (FOG) is a brief, episodic phenomenon affecting over half of people with Parkinson’s disease (PD) and leads to significant morbidity. The pathophysiology of FOG remains poorly understood but is associated with deficits in cognitive function and motor preparation.

Method: We studied 20 people with PD (10 with FOG, 10 without FOG) and performed a timed response target detection task while electroencephalographic data were acquired. We analysed the data to detect and examine cortical markers of cognitive decision making (P3b or centroparietal positivity, CPP) and motor readiness potential. We analysed current source density (CSD) to increase spatial …

Strain-Induced Spectral Tuning Of The Whispering Gallery Modes In A Cylindrical Micro-Resonator Formed By A Polymer Optical Fiber, Vishnu Kavungal, Arun Mallik, Gerald Farrell, Qiang Wu, Yuliya Semenova

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A mechanical strain assisted technique for spectral tuning of whispering gallery modes (WGM) in a cylindrical micro-resonator formed by a polymer optical fiber (POF) is investigated. WGMs in the POF based micro-cylinder are excited by evanescent light coupling using a tapered single mode silica fiber. WGMs observed in the transmission spectrum of the silica fiber taper have a high extinction ratio of up to 19 dB and a Q-factor of up to 2.64 × 10⁴. The application of tensile axial strain (μɛ) in the range from 0 to 1746 μɛ (0.17 %) to the POF micro-resonator results in …

The Conditional Poisson Process And The Erlang And Negative Binomial Distributions, Anurag Agarwal, Peter Bajorski, David L. Farnsworth, James E. Marengo, Wei Qian

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It is a well known fact that for the hierarchical model of a Poisson random variable Y whose mean has an Erlang distribution, the unconditional distribution of Y is negative binomial. However, the proofs in the literature provide no intuitive understanding as to why this result should be true. It is the purpose of this manuscript to give a new proof of this result which provides such an understanding. The memoryless property of the exponential distribution allows one to conclude that the events in two independent Poisson processes may be regarded as Bernoulli trials, and this fact is used to …

Robot Perception Errors And Human Resolution Strategies In Situated Human-Robot Dialogue, Niels Schütte, Brian Mac Namee, John D. Kelleher

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Errors in visual perception may cause problems in situated dialogues. We investigated this problem through an experiment in which human participants interacted through a natural language dialogue interface with a simulated robot.We introduced errors into the robot’s perception, and observed the resulting problems in the dialogues and their resolutions.We then introduced different methods for the user to request information about the robot’s understanding of the environment. We quantify the impact of perception errors on the dialogues, and investigate resolution attempts by users at a structural level and at the level of referring expressions.

An Ionic Liquid Based Sensor For Diclofenac Determination In Water, Emma Brennan, Pauline Futvoie, John Cassidy, Benjamin Schazmann

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This paper details a miniaturised, solid state ion-selective electrode selective for diclofenac. The sensor comprises a novel ionic liquid electroactive material – an imidazolium–diclofenac ion associate. The ion associate is present in a plasticised poly(vinyl chloride) (PVC) membrane on planar carbon electrodes, with an intermediate poly(3,4-ethylenedioxythiophene) layer. The sensitivity and selectivity of the sensor were determined using chronopotentiometric methods. In response to diclofenac, a slope of −53.3 ± 3.6 mV/dec was observed. A limit of detection of 2.90 × 10−3 g L−1 is reported, with a linear range of 3.18 × 10−3 g L−1 to 3.18 g L−1. …

Evaluation Of A Reel-To-Reel Atmospheric Plasma System For The Treatment Of Polymers, Kate O'Flynn, Vladimir Milosavljevic, Peter Dobbyn, Denis Dowling

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Plasma treatments are widely used to enhance the surface energy of polymers prior to bonding or the application of functional coatings. This study investigates the performance of a linear atmospheric pressure plasma source for the reel-to-reel treatment of polymer webs. The continuous argon plasma treatments were carried out on 15 cm diameter polyethylene terephthalate (PET) web substrates using the linear plasma source (Plamax), operating at 13.56 MHz. The study investigated how the processing parameters influenced the effectiveness of the plasma treatment in enhancing both the polymer web's water contact angle (WCA) and surface energy (SE). Based on these measurements the …

Application Of Phase Shifting Electronic Speckle Pattern Interferometry In Studies Of Photoinduced Shrinkage Of Photopolymer Layers, Mohesh Moothanchery, Viswanath Bavigadda, Manojit Pramanik, Vincent Toal, Izabela Naydenova

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Photoinduced shrinkage occurring in photopolymer layers during holographic recording was determined by Phase Shifting Electronic Speckle Pattern Interferometry. Phase maps were calculated from the changes in intensity at each pixel due to the phase differences introduced between object and reference beams. Shrinkage was then obtained from the changes in phase as recording proceeded. The technique allows for whole field measurement of the dimensional changes in photopolymers during holographic recording.

Ltl Type Nanozeolites Utilized In Surface Photonics Structures For Environmental Sensors, Sabad-E- Gul, Dervil Cody, Suzanne Martin, John Cassidy, Izabela Naydenova, Anastasia Kharchenko, Svetlana Mintovab

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Environmental monitoring has been continuously increasing due to an emerging global emphasis on the importance of sustainable development. Improving water quality monitoring and control is a challenge that calls for innovative solutions. Current methods of water monitoring are costly and analytical techniques suitable for field use are limited. There is a need for accurate, long–term monitoring of environmental contaminants using sensors that can be operated on site. The aim of our research is to theoretically model, fabricate and characterise holographic sensors for water quality monitoring that are simple to operate, capable of sensing copper present in fresh water and have …

N-Isopropylacrylamide-Based Photopolymer For Holographic Recording Of Thermosensitive Transmission And Reflection Grating, Tatsiana Mikulchyk, Suzanne Martin, Izabela Naydenova

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In recent years, functionalized photopolymer systems capable of holographic recording are in great demand due to their potential use in the development of holographic sensors. This work presents a newly developed Nisopropylacrylamide(NIPA)-based photopolymer for holographic recording in reflection and transmission modes. The optimized composition of the material is found to reach refractive index modulation of up to 5  10-3 and 1.6  10-3 after recording in transmission and reflection mode, respectively. In addition to fulfilling the requirements for holographic recording materials, the NIPA-based photopolymer is sensitive to temperature and has lower toxicity than acrylamide-based photopolymers. Possible application of the …

Humidity And Temperature Induced Changes In The Diffraction Efficiency And The Bragg Angle Of Slanted Photopolymer-Based Holographic Gratings, Tatsiana Mikulchyk, James Walshe, Dervil Cody, Suzanne Martin, Izabela Naydenova

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This work explores the humidity and temperature response of volume phase slanted gratings recorded in photopolymers with varied chemical composition. Acrylamide and diacetone acrylamide were used as monomers and triethanolamine and N-phenylglycine were used as photoinitiators. The study demonstrates that the response of photopolymer-based holographic gratings to relative humidity (RH) and temperature (T) can be tuned by alteration of the photopolymer composition.Humidity and temperature response of the holograms has been characterized by recording Bragg selectivity curves of transmission gratings and by monitoring the position of the maximum intensity in the spectral response of reflection gratings. Investigation of the humidity response …

Monitoring Doxorubicin Cellular Uptake And Trafficking Using In Vitro Raman Microspectroscopy: Short And Long Time Exposure Effects On Lung Cancer Cell Lines, Zeineb Farhane, Franck Bonnier, Hugh Byrne

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Raman microspectroscopy is a non-invasive, in vitro analytical tool which is being increasingly explored for its potential in clinical applications and monitoring the uptake, mechanism of action and cellular interaction at a molecular level of chemotherapeutic drugs, ultimately as a potential label-free preclinical screening and companion diagnostic tool. In this study, doxorubicin (DOX), a “gold standard” chemotherapeutic drug, is employed as a model in the in vitro lung cancer cell line A549 in order to demonstrate the potential of Raman microspectroscopy to screen and identify spectroscopic markers of its trafficking and mechanism of action. Confocal laser scanning microscopy (CLSM) was …

Strengthening The Development Of The Short-Rotation Plantations Bioenergy Sector: Policy Insights From Six European Countries, Carlos Parra-Lopez, Martin Holley, Kevin Lindegaard, Samir Sayadi, Gonzalo Esteban-Lopez, Victor Duran-Zuazo, Christoph Knauer, Hans-Georg Von Engelbrechten, Ralf Winterber, Annika Henriksson, Annette Lamley, Anders Nylander, Susanne Paulrud, Pauline Leonard, Patrick Daly, Lukasz Drzewaszewski, Wojciech Rzewuski

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This paper, based on a participatory methodological framework involving expert stakeholders and researchers from six European countries (Germany, Ireland, Poland, Spain, Sweden and UK), analyses the priority issues for the development of short-rotation plantations (SRP), and proposes a series of policy strategies to strengthen this development. The results indicate that there is a lack of awareness of the multifaceted benefits of SRP at the level of farmers, policy makers and public authorities. More research is required to put a value on the multifunctionality of SRP and justify its public support. Small-scale projects using established technologies are also required with energy …

Biofunctionalized Capillary Flow Channel Platform Integrated With 3d Nanostructured Matrix To Capture Circulating Tumor Cells, Shashwat Banerjee, Ganesh Khutale, Vrushali Khobragade, Narendra Kale, Milind Pore, Govind Chate, Archana Jalota-Badhwar, Manoj Dongare, Jayant Khandare

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Circulating tumor cells (CTCs) from peripheral blood account genetic information for cancer diagnosis and overall disease monitoring. Analysis of “liquid biopsy” holds immense promise as it may lead to new approaches for cancer treatment. The study reports effective and continuous flow microchannel system for isolating CTCs using transferrin conjugated 3D matrix synthesized by crosslinking polyethylene glycol-Fe3O4 nanostructures for rapid and efficient capturing of CTCs. The platform provides option of using multiple microchannel units in series that can influence higher cell-capture efficiency due to increasing cell-substrate contact frequency. CTCs are captured with high efficiency even at low concentration of target cells …

Integration Of Biological Effects, Fish Histopathology And Contaminant Measurements For The Assessment Of Fish Health: A Pilot Application In Irish Marine Waters, Michelle Giltrap, Jenny Ronan, John Bignell, Brett Lyons, Evelyn Collins, Heather Rochford, Brendan Mchugh, Evin Mcgovern, Lorraine Bull, James Wilson

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This study investigates the use of a weight of evidence (WOE) approach to evaluate fish health status and biological effects (BEs) of contaminants for assessment of ecosystem health and discusses its potential application in support of the Marine Strategy Framework Directive (MSFD). External fish disease, liver histopathology and several BEs of contaminant exposure including 7-ethoxy resorufin O-de-ethylase (EROD), acetylcholinesterase (AChE), bile metabolites, vitellogenin (VTG) and alkali labile phosphates (ALP) were measured in two flatfish species from four locations in Ireland. Contaminant levels in fish were generally low with PCBs in fish liver below OSPAR environmental assessment criteria (EAC). There were …