3,376 research outputs found
Methods of optimization of distributed databases
The great variety of existing databases is emphasized and their brief
description is given. When analyzing a distributed database management system, it is
emphasized that they consist of a single logical database, divided into a number of fragments.
Each fragment of the database is stored on one or more computers (nodes, sites), which are
interconnected by a communication network and each of which operates under the control of
a separate database.
The advantages, disadvantages and necessary requirements to the distributed database
are analyzed. The most effective ways to optimize the structure of distributed databases are
listed separately, approaches to assessing their effectiveness (performance, scalability
(extensibility), reliability, data protection, availability, ease of application development, the
level of interaction with the user). The fragment of grammar of T-SQL language is resulted
and the basic generalizing recommendations on writing of inquiries which are convenient for
the optimizer and effective at execution are resulted
Computer modeling of an impedance-controlled pulsing protocol for RF tumor ablation with a cooled electrode
[EN] Purpose: To develop computer models to mimic the impedance-controlled pulsing protocol implemented in radiofrequency (RF) generators used for clinical practice of radiofrequency ablation (RFA), and to assess the appropriateness of the models by comparing the computer results with those obtained in previous experimental studies.Methods: A 12-min RFA was modelled using a cooled electrode (17G, 3cm tip) inserted in hepatic tissue. The short (transverse) diameter of the coagulation zone was assessed under in vivo (with blood perfusion (BP) and considering clamping) and ex vivo (at 21 degrees C) conditions. The computer results obtained by programming voltage pulses were compared with current pulses.Results: The differences between voltage and current pulses were noticeable: using current instead of voltage allows larger coagulation zones to be created, due to the higher energy applied by current pulses. If voltage pulses are employed the model can accurately predict the number of roll-offs, although the waveform of the applied power is clearly not realistic. If current voltages are employed, the applied power waveform matches well with those reported experimentally, but there are significantly fewer roll-offs. Our computer results were overall into the ranges of experimental ones.Conclusions: The proposed models reproduce reasonably well the electrical-thermal performance and coagulation zone size obtained during an impedance-controlled pulsing protocol.This work was supported by the Spanish Plan Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad under grant number TEC2014-52383-C3-R (TEC2014-52383-C3-1-R). The authors alone are responsible for the content and writing of the paper.Trujillo Guillen, M.; Bon Corbín, J.; Rivera Ortun, MJ.; Burdio, F.; Berjano, E. (2016). Computer modeling of an impedance-controlled pulsing protocol for RF tumor ablation with a cooled electrode. International Journal of Hyperthermia. 32(8):931-939. doi:10.1080/02656736.2016.1190868S931939328Hocquelet, A., Balageas, P., Laurent, C., Blanc, J.-F., Frulio, N., Salut, C., … Trillaud, H. (2015). Radiofrequency ablation versus surgical resection for hepatocellular carcinoma within the Milan criteria: A study of 281 Western patients. International Journal of Hyperthermia, 31(7), 749-757. doi:10.3109/02656736.2015.1068382Fukushima, T., Ikeda, K., Kawamura, Y., Sorin, Y., Hosaka, T., Kobayashi, M., … Kumada, H. (2015). Randomized Controlled Trial Comparing the Efficacy of Impedance Control and Temperature Control of Radiofrequency Interstitial Thermal Ablation for Treating Small Hepatocellular Carcinoma. Oncology, 89(1), 47-52. doi:10.1159/000375166Goldberg, S. N., Stein, M. C., Gazelle, G. S., Sheiman, R. G., Kruskal, J. B., & Clouse, M. E. (1999). Percutaneous Radiofrequency Tissue Ablation: Optimization of Pulsed-Radiofrequency Technique to Increase Coagulation Necrosis. Journal of Vascular and Interventional Radiology, 10(7), 907-916. doi:10.1016/s1051-0443(99)70136-3Ahmed, M., Liu, Z., Humphries, S., & Nahum Goldberg, S. (2008). Computer modeling of the combined effects of perfusion, electrical conductivity, and thermal conductivity on tissue heating patterns in radiofrequency tumor ablation. International Journal of Hyperthermia, 24(7), 577-588. doi:10.1080/02656730802192661Lobo, S. M., Liu, Z.-J., Yu, N. C., Humphries, S., Ahmed, M., Cosman, E. R., … Goldberg, S. N. (2005). RF tumour ablation: Computer simulation and mathematical modelling of the effects of electrical and thermal conductivity. International Journal of Hyperthermia, 21(3), 199-213. doi:10.1080/02656730400001108Solazzo, S. A., Liu, Z., Lobo, S. M., Ahmed, M., Hines-Peralta, A. U., Lenkinski, R. E., & Goldberg, S. N. (2005). Radiofrequency Ablation: Importance of Background Tissue Electrical Conductivity—An Agar Phantom and Computer Modeling Study. Radiology, 236(2), 495-502. doi:10.1148/radiol.2362040965Barauskas, R., Gulbinas, A., & Barauskas, G. (2007). Investigation of radiofrequency ablation process in liver tissue by finite element modeling and experiment. Medicina, 43(4), 310. doi:10.3390/medicina43040039Haemmerich, D., & Wood, B. J. (2006). Hepatic radiofrequency ablation at low frequencies preferentially heats tumour tissue. International Journal of Hyperthermia, 22(7), 563-574. doi:10.1080/02656730601024727Haemmerich, D., Chachati, L., Wright, A. S., Mahvi, D. M., Lee, F. T., & Webster, J. G. (2003). Hepatic radiofrequency ablation with internally cooled probes: effect of coolant temperature on lesion size. IEEE Transactions on Biomedical Engineering, 50(4), 493-500. doi:10.1109/tbme.2003.809488Schutt, D. J., & Haemmerich, D. (2008). Effects of variation in perfusion rates and of perfusion models in computational models of radio frequency tumor ablation. Medical Physics, 35(8), 3462-3470. doi:10.1118/1.2948388Zhang, B., Moser, M. A. J., Zhang, E. M., Luo, Y., & Zhang, W. (2015). Numerical analysis of the relationship between the area of target tissue necrosis and the size of target tissue in liver tumours with pulsed radiofrequency ablation. International Journal of Hyperthermia, 31(7), 715-725. doi:10.3109/02656736.2015.1058429Solazzo, S. A., Ahmed, M., Liu, Z., Hines-Peralta, A. U., & Goldberg, S. N. (2007). High-Power Generator for Radiofrequency Ablation: Larger Electrodes and Pulsing Algorithms in Bovine ex Vivo and Porcine in Vivo Settings. Radiology, 242(3), 743-750. doi:10.1148/radiol.2423052039Abraham, 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.2006.11.045Pätz, T., Kröger, T., & Preusser, T. (2009). Simulation of Radiofrequency Ablation Including Water Evaporation. World Congress on Medical Physics and Biomedical Engineering, September 7 - 12, 2009, Munich, Germany, 1287-1290. doi:10.1007/978-3-642-03882-2_341Trujillo, M., Alba, J., & Berjano, E. (2012). Relationship between roll-off occurrence and spatial distribution of dehydrated tissue during RF ablation with cooled electrodes. International Journal of Hyperthermia, 28(1), 62-68. doi:10.3109/02656736.2011.631076Hall, S. K., Ooi, E. H., & Payne, S. J. (2015). Cell death, perfusion and electrical parameters are critical in models of hepatic radiofrequency ablation. International Journal of Hyperthermia, 31(5), 538-550. doi:10.3109/02656736.2015.1032370Chang, S.-J., Yu, W.-J., Chang, C.-C., & Chen, Y.-H. (2010). 7 PROTEOMICS ANALYSIS OF MALE REPRODUCTIVE PHYSIOLOGY BY TOONA SINENSIS ROEM. Reproductive BioMedicine Online, 20, S3-S4. doi:10.1016/s1472-6483(10)62425-xBeop-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:10.1109/2944.577317Doss, J. D. (1982). Calculation of electric fields in conductive media. Medical Physics, 9(4), 566-573. doi:10.1118/1.595107Jo, 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.2010.02.004Belous, A., & Podhajsky, R. J. (2009). The effect of initial and dynamic liver conditions on RF ablation size: a study in perfused and non-perfused animal models. Energy-based Treatment of Tissue and Assessment V. doi:10.1117/12.809597Song, K. D., Lee, M. W., Park, H. J., Cha, D. I., Kang, T. W., Lee, J., … Rhim, H. (2015). Hepatic radiofrequency ablation:in vivoandex vivocomparisons of 15-gauge (G) and 17-G internally cooled electrodes. The British Journal of Radiology, 88(1050), 20140497. doi:10.1259/bjr.20140497Cha, J., Choi, D., Lee, M. W., Rhim, H., Kim, Y., Lim, H. K., … Park, C. K. (2009). Radiofrequency Ablation Zones in Ex Vivo Bovine and In Vivo Porcine Livers: Comparison of the Use of Internally Cooled Electrodes and Internally Cooled Wet Electrodes. CardioVascular and Interventional Radiology, 32(6), 1235-1240. doi:10.1007/s00270-009-9600-0Lee, J. M., Han, J. K., Chang, J. M., Chung, S. Y., Kim, S. H., Lee, J. Y., … Choi, B. I. (2006). Radiofrequency Ablation of the Porcine Liver In Vivo: Increased Coagulation with an Internally Cooled Perfusion Electrode. Academic Radiology, 13(3), 343-352. doi:10.1016/j.acra.2005.10.020Romero-Méndez, R., Tobajas, P., Burdío, F., Gonzalez, A., Navarro, A., Grande, L., & Berjano, E. (2012). Electrical-thermal performance of a cooled RF applicator for hepatic ablation with additional distant infusion of hypertonic saline:In vivostudy and preliminary computer modeling. International Journal of Hyperthermia, 28(7), 653-662. doi:10.3109/02656736.2012.711894Ahmed, M., Lobo, S. M., Weinstein, J., Kruskal, J. B., Gazelle, G. S., Halpern, E. F., … Goldberg, S. N. (2002). Improved Coagulation with Saline Solution Pretreatment during Radiofrequency Tumor Ablation in a Canine Model. Journal of Vascular and Interventional Radiology, 13(7), 717-724. doi:10.1016/s1051-0443(07)61850-8Chinn, S. B., Lee, F. T., Kennedy, G. D., Chinn, C., Johnson, C. D., Winter, T. C., … Mahvi, D. M. (2001). Effect of Vascular Occlusion on Radiofrequency Ablation of the Liver. American Journal of Roentgenology, 176(3), 789-795. doi:10.2214/ajr.176.3.1760789Arenas, J., Perez, J. J., Trujillo, M., & Berjano, E. (2014). Computer modeling and ex vivo experiments with a (saline-linked) irrigated electrode for RF-assisted heating. BioMedical Engineering OnLine, 13(1), 164. doi:10.1186/1475-925x-13-164González-Suárez, A., Trujillo, M., Burdío, F., Andaluz, A., & Berjano, 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. doi:10.3109/02656736.2012.716900Schramm, W., Yang, D., Wood, B. J., Rattay, F., & Haemmerich, D. (2007). Contribution of Direct Heating, Thermal Conduction and Perfusion During Radiofrequency and Microwave Ablation. The Open Biomedical Engineering Journal, 1(1), 47-52. doi:10.2174/1874120700701010047Chang, I. A., & Nguyen, U. D. (2004). BioMedical Engineering OnLine, 3(1), 27. doi:10.1186/1475-925x-3-27Montgomery, R. S., Rahal, A., Dodd, G. D., Leyendecker, J. R., & Hubbard, L. G. (2004). Radiofrequency Ablation of Hepatic Tumors: Variability of Lesion Size Using a Single Ablation Device. American Journal of Roentgenology, 182(3), 657-661. doi:10.2214/ajr.182.3.1820657SCHUMACHER, B., EICK, O., WITTKAMPF, F., PEZOLD, C., TEBBENJOHANNS, J., JUNG, W., & LUDERITZ, B. (1999). Temperature Response Following Nontraumatic Low Power Radiofrequency Application. Pacing and Clinical Electrophysiology, 22(2), 339-343. doi:10.1111/j.1540-8159.1999.tb00448.xPETERSEN, H. H., & SVENDSEN, J. H. (2003). Can Lesion Size During Radiofrequency Ablation Be Predicted By the Temperature Rise to a Low Power Test Pulse in Vitro? Pacing and Clinical Electrophysiology, 26(8), 1653-1659. doi:10.1046/j.1460-9592.2003.t01-1-00248.
The Concept Of Deep Learning: Recognizing Elements In Cartographic Images
In the process of digitizing archives, there is a problem of transferring the obtained data to a vector image to further work with the obtained result, for example, take the cartographic schemes of hydraulic structures. To solve this problem, consider deep learning. Deep learning, in turn, is a class of machine learning algorithms that uses a multilayer system of nonlinear filters to separate the required characteristics with transformations. Consider how deep learning works, on the example of recognizing elements in a cartographic image
Search for the h_c meson in B^+- ->h_c K^+-
We report a search for the meson via the decay chain , \etac \gamma with and
. No significant signals are observed. We obtain upper limits on the
branching fractions for in bins of the
invariant mass. The results are based on an analysis of 253
fb of data collected by the Belle detector at the KEKB
collider.Comment: 12 pages, 6 figures, submitted to Phys. Rev.
Evidence for CP Violation in B0 -> D+D- Decays
We report measurements of the branching fraction and CP violation parameters
in B0 -> D+D- decays. The results are based on a data sample that contains 535
x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle
detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20
(stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The
measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09,
A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second
is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma
confidence level. While the value of S is consistent with expectations from
other measurements, the value of the parameter A favors large direct CP
violation at the 3.2 sigma confidence level, in contradiction to Standard Model
expectations.Comment: 12 pages, 3 figures, submitted to PR
Time-Dependent CP Asymmetries in B0 -> Ks pi0 gamma transitions
We report measurements of CP violation parameters in B0->Ks pi0 gamma
transitions based on a data sample of 535x10^6 BB pairs collected with the
Belle detector at the KEKB asymmetric-energy e+ e- collider. One neutral B
meson is fully reconstructed in the B0->Ks pi0 gamma mode. The flavor of the
accompanying B meson is identified from its decay products. For a Ks pi0
invariant mass up to 1.8 GeV/c^2, we obtain S = -0.10 +- 0.31 +- 0.07 and A =
-0.20 +- 0.20 +- 0.06. For a Ks pi0 invariant mass near the K*0(892) resonance,
we obtain S = -0.32 +0.36-0.33 +-0.05 and A=-0.20 +-0.24 +-0.05.Comment: 6 pages, 3 figures, accepted by PR
Measurements of Charmless Hadronic b->s Penguin Decays in the pi+pi-K+pi- Final State and First Observation of B0 -> rho0K+pi-
We report measurements of charmless hadronic B^0 decays into the pi+pi-K+pi+
final state. The analysis uses a sample of 657x10^6 BBbar pairs collected with
the Belle detector at the KEKB asymmetric-energy e+e- collider at the Y(4S)
resonance. The decay B^0 -> rho0 Kpi is observed for the first time; the
significance is 5.0sigma and the corresponding partial branching fraction for
M_Kpi in (0.75,1.20) GeV/c^2 is [2.8 +- 0.5(stat) +-0.5(syst)] x 10^{-6}. We
also obtain the first evidence for B^0 -> f0Kpi with 3.5sigma significance and
for B^0 -> pi+pi-K*0 with 4.5sigma significance. For the two-body decays B^0 ->
rho0K*0 and B^0 -> f0K*0, the significances are 2.7sigma and 2.5sigma,
respectively, and the upper limits on the branching fractions are 3.4x10^{-6}
and 2.2x10^{-6} at 90% confidence level.Comment: 6 pages, 3 figures. accepted by PRD(RC
Measurement Of |V_ub| From Inclusive Charmless Semileptonic B Decays
We present the partial branching fraction for inclusive charmless
semileptonic B decays and the corresponding value of the CKM matrix element
|Vub|, using a multivariate analysis method to access ~90% of the B -> Xu l nu
phase space. This approach dramatically reduces the theoretical uncertainties
from the b-quark mass and non-perturbative QCD compared to all previous
inclusive measurements. The results are based on a sample of 657 million B
-Bbar pairs collected with the Belle detector. We find that Delta BR(B -> Xu l
nu; p^*B_l>1.0 GeV/c=1.963 x (1 +/- 0.088(stat.) +/- 0.081(sys.)) x 10^-3.
Corresponding values of |Vub| are extracted using several theoretical
calculations.Comment: 9 pages, 1 figure, 2 tables. Published in PR
Evidence for B to K eta' gamma Decays at Belle
We present the results of a search for the radiative decay (B -> K eta'
gamma) and find evidence for (B^+ -> K^+ eta' gamma) decays at the 3.3 standard
deviation level with a partial branching fraction of (3.6 +/- 1.2 +/- 0.4) x
10e-6, where the first error is statistical and the second systematic. This
measurement is restricted to the region of combined (K eta') invariant mass
less than 3.4GeVc^2. A 90% confidence level upper limit of 6.4 x 10e-6 is
obtained for the decay (B^0 -> K^0 eta' gamma) in the same (K eta') invariant
mass region. These results are obtained from a 605 fb^-1 data sample containing
657 x 10e6 B anti-B pairs collected at the Upsilon(4S) resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider.Comment: 5 pages, 4 figures. Submitted to PRD-RC on 6/8/0
First study of \eta_c, \eta(1760) and X(1835) production via \eta'\pi^+\pi^- final states in two-photon collisions
The invariant mass spectrum of the \eta' \pi^+ \pi^- final state produced in
two-photon collisions is obtained using a 673 fb^{-1} data sample collected in
the vicinity of the \Upsilon(4S) resonance with the Belle detector at the KEKB
asymmetric-energy e^+e^- collider. We observe a clear signal of the \eta_c and
measure its mass and width to be M(\eta_c)=(2982.7 +- 1.8(stat) +- 2.2(syst) +-
0.3(model)) MeV/c^2 and \Gamma(\eta_c) = (37.8^{+5.8}_{-5.3}(stat) +- 2.8(syst)
+- 1.4(model)) MeV/c^2. The third error is an uncertainty due to possible
interference between the \eta_c and a non-resonant component. We also report
the first evidence for \eta(1760) decay to \eta' \pi^+ \pi^-; we find two
solutions for its parameters, depending on the inclusion or not of the X(1835),
whose existence is of marginal significance in our data. From a fit to the mass
spectrum using coherent X(1835) and \eta(1760) resonant amplitudes, we set a
90% confidence level upper limit on the product \Gamma_{\gamma\gamma} \BR
(\eta' \pi^+ \pi^-) for the X(1835).Comment: 13 pages, 7 figures, submitted to PR
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