1
|
Putzke C, Malone L, Badoux S, Vignolle B, Vignolles D, Tabis W, Walmsley P, Bird M, Hussey NE, Proust C, Carrington A. Inverse correlation between quasiparticle mass and T c in a cuprate high-T c superconductor. Sci Adv 2016; 2:e1501657. [PMID: 27034989 PMCID: PMC4803492 DOI: 10.1126/sciadv.1501657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/28/2016] [Indexed: 06/05/2023]
Abstract
Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature T c is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-T c superconductivity. We have tested the robustness of this correlation between m* and T c by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as T c increases under pressure. This inverse correlation between m* and T c suggests that quantum fluctuations of the charge order enhance m* but do not enhance T c.
Collapse
Affiliation(s)
- Carsten Putzke
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Liam Malone
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Sven Badoux
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 31400 Toulouse, France
| | - Baptiste Vignolle
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 31400 Toulouse, France
| | - David Vignolles
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 31400 Toulouse, France
| | - Wojciech Tabis
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 31400 Toulouse, France
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, aleja Adama Mickiewicza 30, 30-059 Krakow, Poland
| | - Philip Walmsley
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Matthew Bird
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - Nigel E. Hussey
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, Netherlands
| | - Cyril Proust
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, 31400 Toulouse, France
| | - Antony Carrington
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| |
Collapse
|
2
|
Connick MJ, Beckman E, Ibusuki T, Malone L, Tweedy SM. Evaluation of methods for calculating maximum allowable standing height in amputees competing in Paralympic athletics. Scand J Med Sci Sports 2015; 26:1353-1359. [PMID: 26589580 DOI: 10.1111/sms.12586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2015] [Indexed: 11/28/2022]
Abstract
The International Paralympic Committee has a maximum allowable standing height (MASH) rule that limits stature to a pre-trauma estimation. The MASH rule reduces the probability that bilateral lower limb amputees use disproportionately long prostheses in competition. Although there are several methods for estimating stature, the validity of these methods has not been compared. To identify the most appropriate method for the MASH rule, this study aimed to compare the criterion validity of estimations resulting from the current method, the Contini method, and four Canda methods (Canda-1, Canda-2, Canda-3, and Canda-4). Stature, ulna length, demispan, sitting height, thigh length, upper arm length, and forearm length measurements in 31 males and 30 females were used to calculate the respective estimation for each method. Results showed that Canda-1 (based on four anthropometric variables) produced the smallest error and best fitted the data in males and females. The current method was associated with the largest error of those tests because it increasingly overestimated height in people with smaller stature. The results suggest that the set of Canda equations provide a more valid MASH estimation in people with a range of upper limb and bilateral lower limb amputations compared with the current method.
Collapse
Affiliation(s)
- M J Connick
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia.
| | - E Beckman
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - T Ibusuki
- Department of Physical Therapy, Oita College of Rehabilitation, Oita, Japan
| | - L Malone
- Lakeshore Foundation, Birmingham, Alabama, USA
| | - S M Tweedy
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
| |
Collapse
|
3
|
Putzke C, Walmsley P, Fletcher JD, Malone L, Vignolles D, Proust C, Badoux S, See P, Beere HE, Ritchie DA, Kasahara S, Mizukami Y, Shibauchi T, Matsuda Y, Carrington A. Anomalous critical fields in quantum critical superconductors. Nat Commun 2014; 5:5679. [PMID: 25477044 PMCID: PMC4268691 DOI: 10.1038/ncomms6679] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 10/28/2014] [Indexed: 11/22/2022] Open
Abstract
Fluctuations around an antiferromagnetic quantum critical point (QCP) are believed to lead to unconventional superconductivity and in some cases to high-temperature superconductivity. However, the exact mechanism by which this occurs remains poorly understood. The iron-pnictide superconductor BaFe2(As1−xPx)2 is perhaps the clearest example to date of a high-temperature quantum critical superconductor, and so it is a particularly suitable system to study how the quantum critical fluctuations affect the superconducting state. Here we show that the proximity of the QCP yields unexpected anomalies in the superconducting critical fields. We find that both the lower and upper critical fields do not follow the behaviour, predicted by conventional theory, resulting from the observed mass enhancement near the QCP. Our results imply that the energy of superconducting vortices is enhanced, possibly due to a microscopic mixing of antiferromagnetism and superconductivity, suggesting that a highly unusual vortex state is realized in quantum critical superconductors. Superconductivity in the iron pnictides is believed to be related to quantum critical fluctuations. Putzke et al. observe unexpected anomalies in the critical fields of BaFe2(As1−xPx)2 that emerge close to its magnetic critical point, which they argue is a generic feature of quantum critical superconductivity.
Collapse
Affiliation(s)
- C Putzke
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - P Walmsley
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - J D Fletcher
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - L Malone
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - D Vignolles
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - C Proust
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - S Badoux
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - P See
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - H E Beere
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - D A Ritchie
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - S Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Y Mizukami
- 1] Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan [2] Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - T Shibauchi
- 1] Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan [2] Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - A Carrington
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| |
Collapse
|
4
|
Sindall P, Lenton JP, Malone L, Douglas S, Cooper RA, Hiremath S, Tolfrey K, Goosey-Tolfrey V. Effect of low-compression balls on wheelchair tennis match-play. Int J Sports Med 2013; 35:424-31. [PMID: 24081621 DOI: 10.1055/s-0033-1354384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low vs. standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20 min) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P<0.05), forward distance (P<0.05), and average speed (P<0.05) were higher for play using a low-compression ball. A lower percentage of total time was spent stationary (P<0.001), with significantly more time spent at speeds of 1-1.49 (P<0.05), 1.5-1.99 (P<0.05) and 2.0-2.49 (P<0.05) m ∙ sec(-1) when using the low-compression ball. Main effects for physiological variables were not significant. Greater total and forward distance, and higher average speeds are achieved using a low-compression ball. The absence of any difference in measured HR and estimated physiological responses would indicate that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development.
Collapse
Affiliation(s)
- P Sindall
- School of Health Sciences, University of Salford, Salford, United Kingdom
| | - J P Lenton
- Peter Harrison Centre for Disability Sport, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - L Malone
- Lakeshore Foundation, Research & Education, Birmingham, United States
| | - S Douglas
- School of Sport and Exercise Science, University of Northern Colorado, Greeley, United States
| | - R A Cooper
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, United States
| | - S Hiremath
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, United States
| | - K Tolfrey
- Peter Harrison Centre for Disability Sport, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - V Goosey-Tolfrey
- Peter Harrison Centre for Disability Sport, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
| |
Collapse
|
5
|
Walmsley P, Putzke C, Malone L, Guillamón I, Vignolles D, Proust C, Badoux S, Coldea AI, Watson MD, Kasahara S, Mizukami Y, Shibauchi T, Matsuda Y, Carrington A. Quasiparticle mass enhancement close to the quantum critical point in BaFe2(As(1-x)P(x))2. Phys Rev Lett 2013; 110:257002. [PMID: 23829753 DOI: 10.1103/physrevlett.110.257002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/10/2013] [Indexed: 06/02/2023]
Abstract
We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe2(As(1-x)P(x))2. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point close to x=0.30 which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from a strong increase in the quasiparticle mass at the quantum critical point.
Collapse
Affiliation(s)
- P Walmsley
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Malone J, Baldelli P, Balter S, Bischof N, Bosmans H, Dowling A, Edyvean S, Gallagher A, Faulkner K, Horner K, Malone L, Mclean ID, O'Connor U, Schreiner A, Vassileva J, Vano E, Zoetelief J. Criteria and suspension levels in diagnostic radiology. Radiat Prot Dosimetry 2013; 153:185-189. [PMID: 23173220 DOI: 10.1093/rpd/ncs295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The EC (European Council) Directive on radiation protection of patients requires that criteria for acceptability of equipment in diagnostic radiology, nuclear medicine and radiotherapy be established throughout the member states. This study reviews the background to this requirement and to its implementation in practice. It notes and considers parallel requirements in the EC medical devices directive and International Electrotechnical Commission standards that it is also important to consider and that both sets of requirements should ideally be harmonised due to the global nature of the equipment industry. The study further reviews the types of criteria that can be well applied for the above purposes, and defines qualitative criteria and suspension levels suitable for application. Both are defined and relationships with other acceptance processes are considered (including acceptance testing at the time of purchase, commissioning and the issue of second-hand equipment). Suspension levels are divided into four types, A, B, C and D, depending on the quality of evidence and consensus they are based on. Exceptional situations involving, for example, new or rapidly evolving technology are also considered. The publication and paper focuses on the role of the holder of the equipment and related staff, particularly the medical physics expert and the practitioner. Advice on how the criteria should be created and implemented is provided for these groups and how this might be coordinated with the supplier. Additional advice on the role of the regulator is provided.
Collapse
Affiliation(s)
- J Malone
- Trinity College Centre for Health Sciences, Dublin 8, Ireland.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
O'Connor U, Gallagher A, Malone L, O'Reilly G. Occupational radiation dose to eyes from endoscopic retrograde cholangiopancreatography procedures in light of the revised eye lens dose limit from the International Commission on Radiological Protection. Br J Radiol 2013; 86:20120289. [PMID: 23385992 PMCID: PMC3608047 DOI: 10.1259/bjr.20120289] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 10/19/2012] [Accepted: 11/12/2012] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Endoscopic retrograde cholangiopancreatography (ERCP) is a common procedure that combines the use of X-ray fluoroscopy and endoscopy for examination of the bile duct. Published data on ERCP doses are limited, including staff eye dose from ERCP. Occupational eye doses are of particular interest now as the International Commission on Radiological Protection (ICRP) has recommended a reduction in the dose limit to the lens of the eye. The aim of this study was to measure occupational eye doses obtained from ERCP procedures. METHODS A new eye lens dosemeter (EYE-D(™), Radcard, Krakow, Poland) was used to measure the ERCP eye dose, H(p)(3), at two endoscopy departments in Ireland. A review of radiation protection practice at the two facilities was also carried out. RESULTS The mean equivalent dose to the lens of the eye of a gastroenterologist is 0.01 mSv per ERCP procedure with an undercouch X-ray tube and 0.09 mSv per ERCP procedure with an overcouch X-ray tube. Staff eye dose normalised to patient kerma area product is also presented. CONCLUSION Staff eye doses in ERCP have the potential to exceed the revised ICRP limit of 20 mSv per annum when an overcouch X-ray tube is used. The EYE-D dosemeter was found to be a convenient method for measuring lens dose. Eye doses in areas outside of radiology departments should be kept under review, particularly in light of the new ICRP eye dose limit. ADVANCES IN KNOWLEDGE Occupational eye lens doses from ERCP procedures have been established using a new commercially available dedicated H(p)(3) dosemeter.
Collapse
Affiliation(s)
- U O'Connor
- Department of Medical Physics and Bioengineering, St. James's Hospital, Dublin 8, Ireland.
| | | | | | | |
Collapse
|
8
|
Abstract
With a widely available magnetic field of 10 T, one can attain the quantum limit in bismuth and graphite. At zero magnetic field, these two elemental semi-metals host a dilute liquid of carriers of both signs. All quasi-particles are confined to a few Landau tubes, when the quantum limit is attained. Each time a Landau tube is squeezed before definitely leaving the Fermi surface, the Nernst response sharply peaks. For bismuth, additional Nernst peaks, unexpected in the non-interacting picture, are resolved beyond the quantum limit. The amplitudes of these unexpected Nernst peaks become more pronounced for the samples with the longest electron mean free path.
Collapse
Affiliation(s)
- Zengwei Zhu
- LPEM (UPMC-CNRS), Ecole Supérieure de Physique et de Chimie Industrielles, Paris, France
| | | | | | | | | | | |
Collapse
|
9
|
Yang H, Fauqué B, Malone L, Antunes AB, Zhu Z, Uher C, Behnia K. Phase diagram of bismuth in the extreme quantum limit. Nat Commun 2010; 1:47. [PMID: 20975701 DOI: 10.1038/ncomms1039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 06/18/2010] [Indexed: 11/09/2022] Open
Abstract
Elemental bismuth provides a rare opportunity to explore the fate of a three-dimensional gas of highly mobile electrons confined to their lowest Landau level. Coulomb interaction, neglected in the band picture, is expected to become significant in this extreme quantum limit, with poorly understood consequences. Here, we present a study of the angular-dependent Nernst effect in bismuth, which establishes the existence of ultraquantum field scales on top of its complex single-particle spectrum. Each time a Landau level crosses the Fermi level, the Nernst response sharply peaks. All such peaks are resolved by the experiment, and their complex angular dependence is in very good agreement with the theory. Beyond the quantum limit, we resolve additional Nernst peaks signaling a cascade of additional Landau sublevels caused by electron interaction.
Collapse
Affiliation(s)
- Huan Yang
- LPEM (UPMC-CNRS), Ecole Supérieure de Physique et de Chimie Industrielles, Paris 75005, France
| | | | | | | | | | | | | |
Collapse
|
10
|
Fletcher JD, Serafin A, Malone L, Analytis JG, Chu JH, Erickson AS, Fisher IR, Carrington A. Evidence for a nodal-line superconducting state in LaFePO. Phys Rev Lett 2009; 102:147001. [PMID: 19392472 DOI: 10.1103/physrevlett.102.147001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Indexed: 05/27/2023]
Abstract
In several iron-arsenide superconductors there is strong evidence for a fully gapped superconducting state consistent with either a conventional s-wave symmetry or an unusual s{+/-} state where the gap changes sign between the electron and hole Fermi-surface sheets. Here we report measurements of the penetration depth lambda(T) in very clean samples of the related iron-phosphide superconductor, LaFePO, at temperatures down to approximately 100 mK. We find that lambda(T) varies approximately linearly with T strongly suggesting the presence of gap nodes in this compound. Taken together with other data, this suggests the gap function is not universal for all pnictide superconductors.
Collapse
Affiliation(s)
- J D Fletcher
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, BS8 1TL, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Hale KS, Stanney KM, Malone L. Enhancing virtual environment spatial awareness training and transfer through tactile and vestibular cues. Ergonomics 2009; 52:187-203. [PMID: 18937109 DOI: 10.1080/00140130802376000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Haptic interaction has been successfully incorporated into a variety of virtual environment (VE) systems, yet designing multimodal VE training systems remains challenging as each cue incorporated during training should maximise learning and training transfer. This study examined the impact of incorporating two independent, spatialised tactile cues and vestibular cues into a military VE training environment with the goal of empirically examining whether such cues could enhance performance within the training environment and also that knowledge and skills gained during training could transfer to another environment. The results showed that tactile cues enhanced spatial awareness and performance during both repeated training and within a transfer environment, yet there were costs associated when two independent tactile cues were presented during training. In addition, results suggest that spatial awareness benefits from a tactile point indicator may be impacted by vestibular cues, as performance benefits were seen when tactile cues were paired with head tracking. To fully realise training potential, it is essential to determine how best to leverage multimodal capacity of VE training systems by identifying how multimodal training cues may advance knowledge, skills and attitudes of trainees. Results from this study provide design guidelines for incorporating tactile cues in VE training environments to enhance spatial awareness.
Collapse
Affiliation(s)
- K S Hale
- Design Interactive, Inc., Oviedo, FL 32765, USA.
| | | | | |
Collapse
|
12
|
Shortt CP, Malone L, Thornton J, Brennan P, Lee MJ. Radiation protection to the eye and thyroid during diagnostic cerebral angiography: A phantom study. J Med Imaging Radiat Oncol 2008; 52:365-9. [PMID: 18811760 DOI: 10.1111/j.1440-1673.2008.01970.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- C P Shortt
- Department of Radiology, Beaumont Hospital, Dublin, Ireland
| | | | | | | | | |
Collapse
|
13
|
Lashinger L, Malone L, Daniels E, Smith N, Pavone A, Colby JK, Perkins S, Fischer SM, Hursting SD. Reduced levels of IGF-1 decrease tumor burden in an orthotopic mouse model of pancreatic cancer. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.1504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
14
|
Malone L. Practical Nuclear Medicine. By P F Sharp, H G Gemmell, A D Murray. pp. 382, 2006 (Springer–Verlag, Heidelberg, Germany), $79.95 ISBN 1-85233-875-X. Br J Radiol 2007. [DOI: 10.1259/bjr.80.954.498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
15
|
Shortt CP, Fanning NF, Malone L, Thornton J, Brennan P, Lee MJ. Thyroid Dose During Neurointerventional Procedures: Does Lead Shielding Reduce the Dose? Cardiovasc Intervent Radiol 2007; 30:922-7. [PMID: 17533529 DOI: 10.1007/s00270-007-9093-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 04/18/2007] [Accepted: 04/22/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE To assess radiation dose to the thyroid in patients undergoing neurointerventional procedures and to evaluate dose reduction to the thyroid by lead shielding. METHODS AND MATERIALS A randomized patient study was undertaken to evaluate the dose reduction by thyroid lead shields and assess their practicality in a clinical setting. Sixty-five patients attending for endovascular treatment of arteriovenous malformations (AVMs) and aneurysms were randomized into one of 2 groups a) No Thyroid Shield and b) Thyroid Lead Shield. Two thermoluminescent dosimeters (TLDs) were placed over the thyroid gland (1 on each side) at constant positions on each patient in both groups. A thyroid lead shield (Pb eq. 0.5 mm) was placed around the neck of patients in the thyroid lead shield group after the neurointerventional radiologist had obtained satisfactory working access above the neck. The total dose-area-product (DAP) value, number and type of digital subtraction angiography (DSA) runs and fluoroscopy time were recorded for all patients. RESULTS Of the 72 patients who initially attended for neurointerventional procedures, 7 were excluded due to failure to consent or because of procedures involving access to the external carotid circulation. Of the remaining 65 who were randomized, a further 9 were excluded due to; procedureabandonment, unfeasible shield placement or shield interference with the procedure. Patient demographics included mean age of 47.9 yrs (15-74), F:M=1.4:1. Mean fluoroscopy time was 25.9 min. Mean DAP value was 13,134.8 cGy x cm(2) and mean number of DSA runs was 13.4. The mean relative thyroid doses were significantly different (p< 0.001) between the unshielded (7.23 mSv/cGy2 x 105) and shielded groups (3.77 mSv/cGy2 x 105). A mean thyroid dose reduction of 48% was seen in the shielded group versus the unshielded group. CONCLUSION Considerable doses to the thyroid are incurred during neurointerventional procedures, highlighting the need for increased awareness of patient radiation protection. Thyroid lead shielding yields significant radiation protection, is inexpensive and when not obscuring the field of view, should be used routinely.
Collapse
Affiliation(s)
- C P Shortt
- Department of Radiology, Beaumont Hospital, Dublin 9, Ireland
| | | | | | | | | | | |
Collapse
|
16
|
Shortt CP, Al-Hashimi H, Malone L, Lee MJ. Staff radiation doses to the lower extremities in interventional radiology. Cardiovasc Intervent Radiol 2007; 30:1206-9. [PMID: 17533541 DOI: 10.1007/s00270-007-9071-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 03/14/2007] [Accepted: 04/01/2007] [Indexed: 11/27/2022]
Abstract
The purpose of this study was to investigate the radiation doses to the lower extremities in interventional radiology suites and evaluate the benefit of installation of protective lead shielding. After an alarmingly increased dose to the lower extremity in a preliminary study, nine interventional radiologists wore thermoluminescent dosimeters (TLDs) just above the ankle, over a 4-week period. Two different interventional suites were used with Siemens undercouch fluoroscopy systems. A range of procedures was carried out including angiography, embolization, venous access, drainages, and biopsies. A second identical 4-week study was then performed after the installation of a 0.25-mm lead curtain on the working side of each interventional table. Equivalent doses for all nine radiologists were calculated. One radiologist exceeded the monthly dose limit for a Category B worker (12.5 mSv) for both lower extremities before lead shield placement but not afterward. The averages of both lower extremities showed a statistically significant dose reduction of 64% (p < 0.004) after shield placement. The left lower extremity received a higher dose than the right, 6.49 vs. 4.57 mSv, an increase by a factor of 1.42. Interventional radiology is here to stay but the benefits of interventional radiology should never distract us from the important issue of radiation protection. All possible measures should be taken to optimize working conditions for staff. This study showed a significant lower limb extremity dose reduction with the use of a protective lead curtain. This curtain should be used routinely on all C-arm interventional radiologic equipment.
Collapse
Affiliation(s)
- C P Shortt
- Department of Radiology, Beaumont Hospital, Beaumont Road, Dublin 9, Ireland
| | | | | | | |
Collapse
|
17
|
|
18
|
Malone L. PET: molecular imaging and its biological applications. Edited by M E Phelps. pp. xvi+621, 2004 (Springer-Verlag, Germany) £154.00 ISBN 0-387-40359-0. Br J Radiol 2005. [DOI: 10.1259/bjr.78.933.780871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
19
|
Malone L. Fundamentals of nuclear pharmacy. By G B Saha, pp. xvii+383, 2004 (Springer-Verlag, Berlin, Heidelberg, New York) £57.50 ISBN 0-387-40360-4. Br J Radiol 2005. [DOI: 10.1259/bjr.78.925.780088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
20
|
Grant AM, Hanson PK, Malone L, Nichols JW. NBD-labeled phosphatidylcholine and phosphatidylethanolamine are internalized by transbilayer transport across the yeast plasma membrane. Traffic 2001; 2:37-50. [PMID: 11208167 DOI: 10.1034/j.1600-0854.2001.020106.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The internalization and distribution of fluorescent analogs of phosphatidylcholine (M-C6-NBD-PC) and phosphatidylethanolamine (M-C6-NBD-PE) were studied in Saccharomyces cerevisiae. At normal growth temperatures, M-C6-NBD-PC was internalized predominantly to the vacuole and degraded. M-C6-NBD-PE was internalized to the nuclear envelope/ER and mitochondria, was not transported to the vacuole, and was not degraded. At 2 degrees C, both were internalized to the nuclear envelope/ER and mitochondria by an energy-dependent, N-ethylmaleimide-sensitive process, and transport of M-C6-NBD-PC to and degradation in the vacuole was blocked. Internalization of neither phospholipid was reduced in the endocytosis-defective mutant, end4-1. However, following pre-incubation at 37 degrees C, internalization of both phospholipids was inhibited at 2 degrees C and 37 degrees C in sec mutants defective in vesicular traffic. The sec18/NSF mutation was unique among the sec mutations in further blocking M-C6-NBD-PC translocation to the vacuole suggesting a dependence on membrane fusion. Based on these and previous observations, we propose that M-C6-NBD-PC and M-C6-NBD-PE are transported across the plasma membrane to the cytosolic leaflet by a protein-mediated, energy-dependent mechanism. From the cytosolic leaflet, both phospholipids are spontaneously distributed to the nuclear envelope/ER and mitochondria. Subsequently, M-C6-NBD-PC, but not M-C6-NBD-PE, is sorted by vesicular transport to the vacuole where it is degraded by lumenal hydrolases.
Collapse
Affiliation(s)
- A M Grant
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | | | |
Collapse
|
21
|
|
22
|
Siegmund A, Grant A, Angeletti C, Malone L, Nichols JW, Rudolph HK. Loss of Drs2p does not abolish transfer of fluorescence-labeled phospholipids across the plasma membrane of Saccharomyces cerevisiae. J Biol Chem 1998; 273:34399-405. [PMID: 9852106 DOI: 10.1074/jbc.273.51.34399] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yeast DRS2 gene, which is required for growth at 23 degreesC or below, encodes a member of a P-type ATPase subgroup reported to transport aminophospholipids between the leaflets of the plasma membrane. Here, we evaluated the potential role of Drs2p in phospholipid transport. When examined by fluorescence microscopy, a drs2 null mutant showed no defect in the uptake or distribution of fluorescent-labeled 1-palmitoyl-2[6-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl (NBD))aminocaproyl]phosphatidylserine) or 1-myristoyl-2[6-NBD-aminocaproyl]phosphatidylethanolamine. Quantification of the amount of cell-associated NBD fluorescence using flow cytometry indicated a significant decrease in the absence of Drs2p, but this decrease was not restricted to the aminophospholipids (phosphatidylserine and phosphatidylethanolamine) and was dependent on culture conditions. Furthermore, the absence of Drs2p had no effect on the amount of endogenous PE exposed to the outer leaflet of the plasma membrane as detected by labeling with trinitrobenzene sulfonic acid. The steady state pool of Drs2p, which was shown to reside predominantly in the plasma membrane, increased upon shift to low temperature or exposure to various divalent cations (Mn2+, Co2+, Ni2+, and Zn2+ but not Ca2+ or Mg2+), conditions that also inhibited the growth of a drs2 null mutant. The data presented here call into question the identification of Drs2p as the exclusive or major aminophospholipid translocase in yeast plasma membranes (Tang, X., Halleck, M. S., Schlegel, R. A., and Williamson, P. (1996) Science 272, 1495-1497).
Collapse
Affiliation(s)
- A Siegmund
- Institut für Biochemie der Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | | | | | | | | | | |
Collapse
|
23
|
Malone L. Horizons Project wants physicians to increase the rate of influenza/pneumococcal immunizations among elderly blacks. Tenn Med 1998; 91:422-3. [PMID: 9807939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
|
24
|
Watson K, Schaub B, Malone L, Demer L. 3.P.375 A subpopulation of vascular cells supports hematopoiesis and expresses stem cell factor. Atherosclerosis 1997. [DOI: 10.1016/s0021-9150(97)89451-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
25
|
Le TP, Tribble DR, Zhou SY, Malone L, Chung RC, Rusnak JM, Wagner KF. Clinical significance of discordant CD4 count and CD4 percentage in HIV-infected individuals. AIDS 1997; 11:1395-6. [PMID: 9302451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
26
|
Abstract
The chest X-ray is the most commonly performed radiological examination in the intensive care unit. We used TLDs to measure the radiation exposure in 30 ICU patients due to portable chest radiography. The mean number of CXR was 3 (range 1-11). The mean surface entry dose at the xiphisternum was 1.8 mGy (range 0.43-5.14 mGy) per patient and 0.63 mGy per CXR. Very small amounts of radiation were detected at the symphysis pubis and in more than half of the patients no radiation was detected at this site. These values are well above accepted norms. Patient exposure may be reduced by ordering fewer X-rays or by changing to a faster screen-film combination.
Collapse
Affiliation(s)
- L Lynch
- Department of Anaesthesia, Beaumont Hospital, Dublin
| | | | | |
Collapse
|
27
|
Barniville G, Hartigan PJ, Lydon A, Rawas O, Andrews JF, Donne B, Kelly M, Brady C, McNamara B, Taylor D, Ishtiaq A, Glacken P, O’brien M, Moraes D, Tyrrell J, McCormack PME, Feely J, Stinson J, Hemeryck L, Feely J, Chan R, Hemeryck L, Clancy L, Feely J, Sharma SC, Barry-Kinsella C, Cortell E, Harrison RF, O’connor JJ, Trout SJ, Kruk ZL, Sharma SC, Barry-Kinsella C, Foran K, Han B, Kelly JP, O’donnell JM, Hollywood MA, McHale NG, Kearns JB, Hardiman O, Harris AM, Harris CS, O’halloran KD, Bradford A, McKeogh D, Nolan P, O’regan RG, McDermott M, Maddineni VR, Mirakhur RK, Cooper AR, Clarke RSJ, O’brien W, Tarpey J, Cooney C, Blunnie WP, Moriarty DC, Niveditha Y, O’donovan DJ, Manning B, Furlong E, Martin F, Brazil DP, Smyth EM, Keenan AK, Nunan N, Faustman D, Li X, Sklar RM, Brown RH, O’gorman S, Bannigan J, Moynihan JB, Staunton HP, Breathnach CS, Lynch L, Bowen M, Malone L, Cunningham AJ, Armstrong NC, Allen JM, Strain JJ, McDermott BM, Strain JJ, Bailey CJ, Flatt PR, Megaw DP, Murphy FJ, Reen DJ, D’arcy G, Cooke T, Sheahan R, Foley D, Reilly M, Jauch W, Gibney M, Crean P, Gearty G, Walsh M, McGinley J, Hurley J, Phelan D, Neligan M, Luckwill RG, O’connor JJ, Rowan MJ, Anwyll R, Wall M, Houghton JA, Heatley M, Whiteside C, Maxwell P, Toner P, Walsh DM, Lowe AS, Baxter GD, Allen JM, Bell AJ, Lee TC, McNamara BP, Prendergast PJ, Taylor D, Campion DP, Leek BF. Royal academy of medicine in Ireland section of biomedical sciences. Ir J Med Sci 1992. [DOI: 10.1007/bf02983772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
28
|
Affiliation(s)
- G J Price
- Roche Products Ltd, Welwyn Garden City, Herts, UK
| | | |
Collapse
|
29
|
|
30
|
|
31
|
Delucchi L, Malone L, Thier HD. Science activities for the visually impaired: developing a model. Except Child 1980; 46:287-288. [PMID: 7358069 DOI: 10.1177/001440298004600408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
|