543 research outputs found
Progressive ataxia with oculo-palatal tremor and optic atrophy
The final publication is available at Springer via doi: 10.â1007/âs00415-013-7136-
Feasibility study of an internally cooled bipolar applicator for RF coagulation of hepatic tissue: Experimental and computational study
Purpose: To study the capacity of an internally cooled radiofrequency (RF) bipolar applicator to create sufficiently deep thermal lesions in hepatic tissue. Materials and methods: Three complementary methodologies were employed to check the electrical and thermal behaviour of the applicator under test. The experimental studies were based on excised bovine (ex vivo study) and porcine liver (in vivo study) and the theoretical models were solved by means of the finite element method (FEM). Results: Experimental and computational results showed good agreement in terms of impedance progress and lesion depth (4 and 4.5 mm respectively for ex vivo conditions, and approximately 7 and 9 mm respectively for in vivo conditions), although the lesion widths were overestimated by the computer simulations. This could have been due to the method used to assess the thermal lesions; the experimental lesions were assessed by the white coagulation zone, whereas the tissue damage function was used to assess the computational lesions. Conclusions: The experimental results suggest that this applicator could create in vivo lesions to a depth of around 7mm. It was also observed that the thermal lesion is mainly confined to the area between both electrodes, which would allow lesion width to be controlled by selecting a specific applicator design. The comparison between the experimental and computational results suggests that the theoretical model could be usefully applied in further studies of the performance of this device. Š 2012 Informa UK Ltd All rights reserved.This work received financial support from the Spanish Plan Nacional de I+D+I del Ministerio de Ciencia e Innovacion TEC2011-27133-C02-(01 and 02), from Universitat Politecnica de Valencia (INNOVA11-01-5502; and PAID-06-11 Ref. 1988). A. Gonzalez-Suarez is the recipient of grant VaLi+D (ACIF/2011/194) from the Generalitat Valenciana. The proof-reading of this paper was funded by the Universitat Politecnica de Valencia, Spain. The authors alone are responsible for the content and writing of the paper.GonzĂĄlez SuĂĄrez, A.; Trujillo Guillen, M.; BurdĂo Pinilla, F.; Andaluz MartĂnez, AM.; Berjano ZanĂłn, E. (2012). Feasibility study of an internally cooled bipolar applicator for RF coagulation of hepatic tissue: Experimental and computational study. International Journal of Hyperthermia. 28(7):663-673. https://doi.org/10.3109/02656736.2012.716900S663673287Topp, S. A., McClurken, M., Lipson, D., Upadhya, G. A., Ritter, J. H., Linehan, D., & Strasberg, S. M. (2004). Saline-Linked Surface Radiofrequency Ablation. Annals of Surgery, 239(4), 518-527. doi:10.1097/01.sla.0000118927.83650.a4Gnerlich, J. L., Ritter, J. H., Linehan, D. C., Hawkins, W. G., & Strasberg, S. M. (2009). Saline-Linked Surface Radiofrequency Ablation. Annals of Surgery, 250(1), 96-102. doi:10.1097/sla.0b013e3181ae91afSakamoto, Y., Yamamoto, J., Kokudo, N., Seki, M., Kosuge, T., Yamaguchi, T., ⌠Makuuchi, M. (2004). Bloodless liver resection using the Monopolar Floating Ball plus Ligasure diathermy: Preliminary results of 16 liver resections. World Journal of Surgery, 28(2), 166-172. doi:10.1007/s00268-003-7167-5Poon, R. T., Fan, S. T., & Wong, J. (2005). Liver resection using a saline-linked radiofrequency dissecting sealer for transection of the liver. Journal of the American College of Surgeons, 200(2), 308-313. doi:10.1016/j.jamcollsurg.2004.10.008EVERETT IV, T. H., LEE, K. W., WILSON, E. E., GUERRA, J. M., VAROSY, P. D., & OLGIN, J. E. (2008). Safety Profiles and Lesion Size of Different Radiofrequency Ablation Technologies: A Comparison of Large Tip, Open and Closed Irrigation Catheters. Journal of Cardiovascular Electrophysiology, 20(3), 325-335. doi:10.1111/j.1540-8167.2008.01305.xYokoyama, K., Nakagawa, H., Wittkampf, F. H. M., Pitha, J. V., Lazzara, R., & Jackman, W. M. (2006). Comparison of Electrode Cooling Between Internal and Open Irrigation in Radiofrequency Ablation Lesion Depth and Incidence of Thrombus and Steam Pop. Circulation, 113(1), 11-19. doi:10.1161/circulationaha.105.540062Demazumder, D., Mirotznik, M. S., & Schwartzman, D. (2001). Journal of Interventional Cardiac Electrophysiology, 5(4), 391-400. doi:10.1023/a:1013241927388Cooper, J. M., Sapp, J. L., Tedrow, U., Pellegrini, C. P., Robinson, D., Epstein, L. M., & Stevenson, W. G. (2004). Ablation with an internally irrigated radiofrequency catheter: Learning how to avoid steam pops. Heart Rhythm, 1(3), 329-333. doi:10.1016/j.hrthm.2004.04.019BurdĂo, F., Grande, L., Berjano, E., Martinez-Serrano, M., Poves, I., BurdĂo, J. M., ⌠GĂźemes, A. (2010). A new single-instrument technique for parenchyma division and hemostasis in liver resection: a clinical feasibility study. The American Journal of Surgery, 200(6), e75-e80. doi:10.1016/j.amjsurg.2010.02.020RĂos, J. S., Zalabardo, J. M. S., Burdio, F., Berjano, E., Moros, M., Gonzalez, A., ⌠GĂźemes, A. (2011). Single Instrument for Hemostatic Control in Laparoscopic Partial Nephrectomy in a Porcine Model Without Renal Vascular Clamping. Journal of Endourology, 25(6), 1005-1011. doi:10.1089/end.2010.0557Dorcaratto, D., BurdĂo, F., Fondevila, D., Andaluz, A., Poves, I., Martinez, M. A., ⌠Grande, L. (2012). Laparoscopic Distal Pancreatectomy: Feasibility Study of Radiofrequency-Assisted Transection in a Porcine Model. Journal of Laparoendoscopic & Advanced Surgical Techniques, 22(3), 242-248. doi:10.1089/lap.2011.0417Zeh, A., Messer, J., Davis, J., Vasarhelyi, A., & Wohlrab, D. (2010). The Aquamantys SystemâAn Alternative To Reduce Blood Loss in Primary Total Hip Arthroplasty? The Journal of Arthroplasty, 25(7), 1072-1077. doi:10.1016/j.arth.2009.10.008Sprunger, J., & Herrell, S. D. (2005). Partial Laparoscopic Nephrectomy Using Monopolar Saline-Coupled Radiofrequency Device: Animal Model and Tissue Effect Characterization. Journal of Endourology, 19(4), 513-519. doi:10.1089/end.2005.19.513Voeller, R. K., Zierer, A., Lall, S. C., Sakamoto, S., Schuessler, R. B., & Damiano, R. J. (2010). Efficacy of a novel bipolar radiofrequency ablation device on the beating heart for atrial fibrillation ablation: A long-term porcine study. The Journal of Thoracic and Cardiovascular Surgery, 140(1), 203-208. doi:10.1016/j.jtcvs.2009.06.034Pai, M., Spalding, D., Jiao, L., & Habib, N. (2012). Use of Bipolar Radiofrequency in Parenchymal Transection of the Liver, Pancreas and Kidney. Digestive Surgery, 29(1), 43-47. doi:10.1159/000335732Berjano, E. J. (2006). BioMedical Engineering OnLine, 5(1), 24. doi:10.1186/1475-925x-5-24Tungjitkusolmun, S., Staelin, S. T., Haemmerich, D., Jang-Zern Tsai, Hong Cao, Webster, J. G., ⌠Vorperian, V. R. (2002). Three-dimensional finite-element analyses for radio-frequency hepatic tumor ablation. IEEE Transactions on Biomedical Engineering, 49(1), 3-9. doi:10.1109/10.972834Doss, J. D. (1982). Calculation of electric fields in conductive media. Medical Physics, 9(4), 566-573. doi:10.1118/1.595107Abraham, J. P., & Sparrow, E. M. (2007). A thermal-ablation bioheat model including liquid-to-vapor phase change, pressure- and necrosis-dependent perfusion, and moisture-dependent properties. International Journal of Heat and Mass Transfer, 50(13-14), 2537-2544. doi:10.1016/j.ijheatmasstransfer.2006.11.045Jo, B., & Aksan, A. (2010). Prediction of the extent of thermal damage in the cornea during conductive keratoplasty. Journal of Thermal Biology, 35(4), 167-174. doi:10.1016/j.jtherbio.2010.02.004Pearce, J., Panescu, D., & Thomsen, S. (2005). Simulation of diopter changes in radio frequency conductive keratoplasty in the cornea. Modelling in Medicine and Biology VI. doi:10.2495/bio050451Yang, D., Converse, M. C., Mahvi, D. M., & Webster, J. G. (2007). Expanding the Bioheat Equation to Include Tissue Internal Water Evaporation During Heating. IEEE Transactions on Biomedical Engineering, 54(8), 1382-1388. doi:10.1109/tbme.2007.890740Zhao, G., Zhang, H.-F., Guo, X.-J., Luo, D.-W., & Gao, D.-Y. (2007). Effect of blood flow and metabolism on multidimensional heat transfer during cryosurgery. Medical Engineering & Physics, 29(2), 205-215. doi:10.1016/j.medengphy.2006.03.005Pätz T, KĂśrger T, Preusser T, Simulation of radiofrequency ablation including water evaporation. In: IFMBE Proceedings of the World Congress on Medical Physics and Biomedical Engineering 25/IV, 2009, 1287â1290Berjano, E. J., BurdĂo, F., Navarro, A. C., BurdĂo, J. M., GĂźemes, A., Aldana, O., ⌠Gregorio, M. A. de. (2006). Improved perfusion system for bipolar radiofrequency ablation of liver: preliminary findings from a computer modeling study. Physiological Measurement, 27(10), N55-N66. doi:10.1088/0967-3334/27/10/n03BurdĂo, F., Berjano, E. J., Navarro, A., BurdĂo, J. M., Grande, L., Gonzalez, A., ⌠Lequerica, J. L. (2009). Research and development of a new RF-assisted device for bloodless rapid transection of the liver: Computational modeling and in vivo experiments. BioMedical Engineering OnLine, 8(1), 6. doi:10.1186/1475-925x-8-6Chang, I. A., & Nguyen, U. D. (2004). BioMedical Engineering OnLine, 3(1), 27. doi:10.1186/1475-925x-3-27Beop-Min Kim, Jacques, S. L., Rastegar, S., Thomsen, S., & Motamedi, M. (1996). Nonlinear finite-element analysis of the role of dynamic changes in blood perfusion and optical properties in laser coagulation of tissue. IEEE Journal of Selected Topics in Quantum Electronics, 2(4), 922-933. doi:10.1109/2944.577317Panescu, D., Whayne, J. G., Fleischman, S. D., Mirotznik, M. S., Swanson, D. K., & Webster, J. G. (1995). Three-dimensional finite element analysis of current density and temperature distributions during radio-frequency ablation. IEEE Transactions on Biomedical Engineering, 42(9), 879-890. doi:10.1109/10.412649GonzĂĄlez-SuĂĄrez A, Alba J, Trujillo M, Berjano E, Experimental and theoretical study of an internally cooled bipolar electrode for RF coagulation of biological tissues. Conf Proc IEEE Eng Med Biol Soc 2011;6878â6881Rosenberg, A. G. (2007). Reducing Blood Loss in Total Joint Surgery With a Saline-Coupled Bipolar Sealing Technology. The Journal of Arthroplasty, 22(4), 82-85. doi:10.1016/j.arth.2007.02.018PETERSEN, H. H., ROMAN-GONZALEZ, J., JOHNSON, S. B., HASTRUP SVENDSEN, J., HAUNSO, S., & PACKER, D. L. (2004). Mechanisms for Enlarging Lesion Size During Irrigated Tip Radiofrequency Ablation:. Is There a Virtual Electrode Effect? Journal of Interventional Cardiology, 17(3), 171-177. doi:10.1111/j.1540-8183.2004.09879.
Is spoken language all-or-nothing? Implications for future speech-based human-machine interaction
Recent years have seen significant market penetration for voice-based personal assistants such as Appleâs Siri. However, despite this success, user take-up is frustratingly low. This article argues that there is a habitability gap caused by the inevitablemismatch between the capabilities and expectations of human users and the features and benefits provided by contemporary technology. Suggestions aremade as to how such problems might be mitigated, but a more worrisome question emerges: âis spoken language all-or-nothingâ? The answer, based on contemporary views on the special nature of (spoken) language, is that there may indeed be a fundamental limit to the interaction that can take place between mismatched interlocutors (such as humans and machines). However, it is concluded that interactions between native and non-native speakers, or between adults and children, or even between humans and dogs, might provide critical inspiration for the design of future speech-based human-machine interaction
Fibre Distribution and the Process-Property Dilemma
The options for the fibre reinforcement of polymer matrix composites cover a range from short-fibre chopped strand mat, through woven fabric to unidirectional pre-impregnated (prepreg) reinforcements. The modelling of such materials may be simplified by assumptions such as perfect regular packing of fibres and the total absence of fibre waviness. However, these and other features such as the crimp or waviness in woven fabrics make real materials more complex than the simplified models. Clustering of fibres creates fibre-rich and resin-rich volumes (FRV and RRV respectively) in the composites. Prior to impregnation, large RRV will be pore-space that can expedite the flow of resin in liquid composite moulding processes (especially resin transfer moulding (RTM) and resin infusion under flexible tooling (RIFT). In the composite, the clustering of fibres tends to reduce the mechanical properties. The use of image processing and analysis can permit micro-/meso-structural characterisation which may correlate to the respective properties. This chapter considers the quantification of microstructure images in the context of the process-property dilemma for woven carbon-fibre reinforced composites with the aim of increasing understanding of the balance between processability and mechanical performance
The dependence of dijet production on photon virtuality in ep collisions at HERA
The dependence of dijet production on the virtuality of the exchanged photon,
Q^2, has been studied by measuring dijet cross sections in the range 0 < Q^2 <
2000 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of
38.6 pb^-1.
Dijet cross sections were measured for jets with transverse energy E_T^jet >
7.5 and 6.5 GeV and pseudorapidities in the photon-proton centre-of-mass frame
in the range -3 < eta^jet <0. The variable xg^obs, a measure of the photon
momentum entering the hard process, was used to enhance the sensitivity of the
measurement to the photon structure. The Q^2 dependence of the ratio of low- to
high-xg^obs events was measured.
Next-to-leading-order QCD predictions were found to generally underestimate
the low-xg^obs contribution relative to that at high xg^obs. Monte Carlo models
based on leading-logarithmic parton-showers, using a partonic structure for the
photon which falls smoothly with increasing Q^2, provide a qualitative
description of the data.Comment: 35 pages, 6 eps figures, submitted to Eur.Phys.J.
Search for a narrow charmed baryonic state decaying to D^*+/- p^-/+ in ep collisions at HERA
A resonance search has been made in the D^*+/- p^-/+ invariant-mass spectrum
with the ZEUS detector at HERA using an integrated luminosity of 126 pb^-1. The
decay channels D^*+ -> D^0 pi^+_s -> (K^- pi^+) pi^+_s and D^*+ -> D^0 pi^+_s
-> (K^- pi^+ pi^+ pi^-) pi^+_s (and the corresponding antiparticle decays) were
used to identify D^*+/- mesons. No resonance structure was observed in the
D^*+/- p^-/+ mass spectrum from more than 60000 reconstructed D^*+/- mesons.
The results are not compatible with a report of the H1 Collaboration of a
charmed pentaquark, Theta^0_c.Comment: 22 pages, 7 figures, 1 table; minor text revisions; 2 references
adde
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
The azimuthal anisotropy of charged particles in PbPb collisions at
nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS
detector at the LHC over an extended transverse momentum (pt) range up to
approximately 60 GeV. The data cover both the low-pt region associated with
hydrodynamic flow phenomena and the high-pt region where the anisotropies may
reflect the path-length dependence of parton energy loss in the created medium.
The anisotropy parameter (v2) of the particles is extracted by correlating
charged tracks with respect to the event-plane reconstructed by using the
energy deposited in forward-angle calorimeters. For the six bins of collision
centrality studied, spanning the range of 0-60% most-central events, the
observed v2 values are found to first increase with pt, reaching a maximum
around pt = 3 GeV, and then to gradually decrease to almost zero, with the
decline persisting up to at least pt = 40 GeV over the full centrality range
measured.Comment: Replaced with published version. Added journal reference and DO
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