Search

Your search keyword '"Stavrinou, P."' showing total 443 results
Start Over Author "Stavrinou, P."
443 results on '"Stavrinou, P."'

151. Controlling radiative loss in quantum well solar cells

Author

Universitat Politècnica de València. Instituto Universitario de Tecnología Nanofotónica - Institut Universitari de Tecnologia Nanofotònica, Ekins-Daukes, N. J., Lee, K.H., Hirst, L., Chan, A., Fuehrer, M., Adams, J., Browne, B., Barnham, K.W.J., Stavrinou, P., Connolly, James Patrick, Roberts, J. S., Stevens, B., Airey, R., Kennedy, K., Universitat Politècnica de València. Instituto Universitario de Tecnología Nanofotónica - Institut Universitari de Tecnologia Nanofotònica, Ekins-Daukes, N. J., Lee, K.H., Hirst, L., Chan, A., Fuehrer, M., Adams, J., Browne, B., Barnham, K.W.J., Stavrinou, P., Connolly, James Patrick, Roberts, J. S., Stevens, B., Airey, R., and Kennedy, K.

Abstract

[EN] The inclusion of quantum well layers in a solar cell provides a means for extending the absorption and therefore increasing the photocurrent of the cell. In 2009, a single-junction GaAsP/InGaAs quantum well solar cell attained a peak efficiency of 28.3% under solar concentration. Since then InGaP/MQW/Ge quantum well devices have attained efficiencies in excess of 40% under concentration and over 30% under AM0. The principle motivation for incorporating a quantum well stack into a multi-junction solar cell is to increase the photocurrent delivered by the middle junction over the conventional In0.01GaAs bulk junction. This enables additional current to flow through the top and middle cells, resulting in a sharp rise in efficiency. However, quantum wells also provide some freedom to manipulate the radiative recombination in the quantum well solar cell. We show that under radiatively dominated, anisotropic emission, strong radiative coupling between sub-cells takes place, resulting in a multi-junction solar cell that is tolerant to daily and seasonal changes to the solar spectrum.

Published
2013

153. Early or late cranioplasty following decompressive craniotomy for traumatic brain injury: A systematic review and meta-analysis

Author

Zheng, Feng, Xu, Hao, von Spreckelsen, Niklas, Stavrinou, Pantelis, Timmer, Marco, Goldbrunner, Roland, Cao, Fang, Ran, Qishan, Li, Gang, Fan, Ruiming, Zhang, Qiang, Chen, Wei, Yao, Shengtao, and Krischek, Boris

Abstract

Objective To evaluate the effectiveness of early (<3 months) cranioplasty (CP) and late CP (>3 months) on post-operative complications in patients receiving decompressive craniotomy (DC) for traumatic brain injury (TBI).Methods The Cochrane Library, PubMed and EMBASE databases were systematically searched for studies published prior to May 21, 2017. A meta-analysis examined post-operative overall complication rates, infection rates, subdural fluid collection and operating times according to early and late CP.Results Of the initial 1675 references, five studies, all cohort, involving a total of 413 patients, were selected for the review. There was no difference between early and late CP in post-operative overall complication rate (RR=0.68, 95%CI [0.36, 1.29]) and the post-operative infection rate (RR=0.50, 95%CI [0.20, 1.24]) in patients receiving DC for TBI. However, there was a significant difference in post-operative subdural effusion (RR=0.24, 95%CI [0.07, 0.78]) and mean operative time (mean difference = −33.02 min, 95%CI [−48.19, −17.84]) both in favour of early CP.Conclusions No differences were found between early and late CP in post-operative overall complications and procedural related infections in patients receiving DC for TBI, but early CP reduced the complication of subdural effusion and the mean operating time. These findings need to be confirmed by large, randomised controlled trials.

Published
2018
Full Text
View/download PDF

154. Controlling Molecular Conformation for Highly Efficient and Stable Deep-Blue Copolymer Light-Emitting Diodes

Author

Hamilton, Iain, Chander, Nathan, Cheetham, Nathan J., Suh, Minwon, Dyson, Matthew, Wang, Xuhua, Stavrinou, Paul N., Cass, Michael, Bradley, Donal D. C., and Kim, Ji-Seon

Abstract

We report a novel approach to achieve deep-blue, high-efficiency, and long-lived solution-processed polymer light-emitting diodes (PLEDs) via a simple molecular level conformation change of an emissive conjugated polymer. We introduce rigid β-phase segments into a 95% fluorene—5% arylamine copolymer emissive layer. The arylamine moieties at low density act as efficient exciton formation sites in PLEDs, whereas the conformational change alters the nature of the dominant luminescence from a broad, charge transfer like emission to a significantly blue-shifted and highly vibronically structured excitonic emission. As a consequence, we observe a significant improvement in the Commission International de L’Eclairage (x, y) coordinates from (0.149, 0.175) to (0.145, 0.123) while maintaining high efficiency and improved stability. We achieve a peak luminous efficiency, η = 3.60 cd/A, and a luminous power efficiency, ηw= 2.44 lm/W, values that represent state-of-the-art performance for single copolymer deep-blue PLEDs. These values are 5-fold better than for otherwise-equivalent, β-phase poly(9,9-dioctylfluorene) PLEDs (0.70 cd/A and 0.38 lm/W). This report represents the first demonstration of the use of molecular conformation as a simple but effective method to control the optoelectronic properties of a fluorene copolymer; previous examples have been confined to homopolymers.

Published
2018
Full Text
View/download PDF

155. CELL BIOLOGY AND SIGNALING

Author

Agarwal, M., primary, Nitta, R., additional, Dovat, S., additional, Li, G., additional, Arita, H., additional, Narita, Y., additional, Fukushima, S., additional, Tateishi, K., additional, Matsushita, Y., additional, Yoshida, A., additional, Miyakita, Y., additional, Ohno, M., additional, Collins, V. P., additional, Kawahara, N., additional, Shibui, S., additional, Ichimura, K., additional, Kahn, S. A., additional, Gholamin, S., additional, Junier, M.-P., additional, Chneiweiss, H., additional, Weissman, I., additional, Mitra, S., additional, Cheshier, S., additional, Avril, T., additional, Hamlat, A., additional, Le Reste, P.-J., additional, Mosser, J., additional, Quillien, V., additional, Carrato, C., additional, Munoz-Marmol, A., additional, Serrano, L., additional, Pijuan, L., additional, Hostalot, C., additional, Villa, S. l., additional, Ariza, A., additional, Etxaniz, O., additional, Balana, C., additional, Benveniste, E. T., additional, Zheng, Y., additional, McFarland, B., additional, Drygin, D., additional, Bellis, S., additional, Bredel, M., additional, Lotsch, D., additional, Engelmaier, C., additional, Allerstorfer, S., additional, Grusch, M., additional, Pichler, J., additional, Weis, S., additional, Hainfellner, J., additional, Marosi, C., additional, Spiegl-Kreinecker, S., additional, Berger, W., additional, Bronisz, A., additional, Nowicki, M. O., additional, Wang, Y., additional, Ansari, K., additional, Chiocca, E. A., additional, Godlewski, J., additional, Brown, K., additional, Kwatra, M., additional, Bui, T., additional, Zhu, S., additional, Kozono, D., additional, Li, J., additional, Kushwaha, D., additional, Carter, B., additional, Chen, C., additional, Schulte, J., additional, Srikanth, M., additional, Das, S., additional, Zhang, J., additional, Lathia, J., additional, Yin, L., additional, Rich, J., additional, Olson, E., additional, Kessler, J., additional, Chenn, A., additional, Cherry, A., additional, Haas, B., additional, Lin, Y. H., additional, Ong, S.-E., additional, Stella, N., additional, Cifarelli, C. P., additional, Griffin, R. J., additional, Cong, D., additional, Zhu, W., additional, Shi, Y., additional, Clark, P., additional, Kuo, J., additional, Hu, S., additional, Sun, D., additional, Bookland, M., additional, Darbinian, N., additional, Dey, A., additional, Robitaille, M., additional, Remke, M., additional, Faury, D., additional, Maier, C., additional, Malhotra, A., additional, Jabado, N., additional, Taylor, M., additional, Angers, S., additional, Kenney, A., additional, Ren, X., additional, Zhou, H., additional, Schur, M., additional, Baweja, A., additional, Singh, M., additional, Erdreich-Epstein, A., additional, Fu, J., additional, Koul, D., additional, Yao, J., additional, Saito, N., additional, Zheng, S., additional, Verhaak, R., additional, Lu, Z., additional, Yung, W. K. A., additional, Gomez, G., additional, Volinia, S., additional, Croce, C., additional, Brennan, C., additional, Cavenee, W., additional, Furnari, F., additional, Lopez, S. G., additional, Qu, D., additional, Petritsch, C., additional, Gonzalez-Huarriz, M., additional, Aldave, G., additional, Ravi, D., additional, Rubio, A., additional, Diez-Valle, R., additional, Marigil, M., additional, Jauregi, P., additional, Vera, B., additional, Rocha, A. A. d. l., additional, Tejada-Solis, S., additional, Alonso, M. M., additional, Gopal, U., additional, Isaacs, J., additional, Gruber-Olipitz, M., additional, Dabral, S., additional, Ramkissoon, S., additional, Kung, A., additional, Pak, E., additional, Chung, J., additional, Theisen, M., additional, Sun, Y., additional, Monrose, V., additional, Franchetti, Y., additional, Shulman, D., additional, Redjal, N., additional, Tabak, B., additional, Beroukhim, R., additional, Zhao, J., additional, Buonamici, S., additional, Ligon, K., additional, Kelleher, J., additional, Segal, R., additional, Canton, D., additional, Diaz, P., additional, Scott, J., additional, Hara, K., additional, Kageji, T., additional, Mizobuchi, Y., additional, Kitazato, K., additional, Okazaki, T., additional, Fujihara, T., additional, Nakajima, K., additional, Mure, H., additional, Kuwayama, K., additional, Hara, T., additional, Nagahiro, S., additional, Hill, L., additional, Botfield, H., additional, Hossain-Ibrahim, K., additional, Logan, A., additional, Cruickshank, G., additional, Liu, Y., additional, Gilbert, M., additional, Kyprianou, N., additional, Rangnekar, V., additional, Horbinski, C., additional, Hu, Y., additional, Vo, C., additional, Li, Z., additional, Ke, C., additional, Ru, N., additional, Hess, K. R., additional, Linskey, M. E., additional, Zhou, Y.-a. H., additional, Hu, F., additional, Vinnakota, K., additional, Wolf, S., additional, Kettenmann, H., additional, Jackson, P. J., additional, Larson, J. D., additional, Beckmann, D. A., additional, Moriarity, B. S., additional, Largaespada, D. A., additional, Jalali, S., additional, Agnihotri, S., additional, Singh, S., additional, Burrell, K., additional, Croul, S., additional, Zadeh, G., additional, Kang, S.-H., additional, Yu, M. O., additional, Song, N.-H., additional, Park, K.-J., additional, Chi, S.-G., additional, Chung, Y.-G., additional, Kim, S. K., additional, Kim, J. W., additional, Kim, J. Y., additional, Kim, J. E., additional, Choi, S. H., additional, Kim, T. M., additional, Lee, S.-H., additional, Kim, S.-K., additional, Park, S.-H., additional, Kim, I. H., additional, Park, C.-K., additional, Jung, H.-W., additional, Koldobskiy, M., additional, Ahmed, I., additional, Ho, G., additional, Snowman, A., additional, Raabe, E., additional, Eberhart, C., additional, Snyder, S., additional, Gugel, I., additional, Bornemann, A., additional, Pantazis, G., additional, Mack, S., additional, Shih, D., additional, Sabha, N., additional, Tatagiba, M., additional, Krischek, B., additional, Schulte, A., additional, Liffers, K., additional, Kathagen, A., additional, Riethdorf, S., additional, Westphal, M., additional, Lamszus, K., additional, Lee, J. S., additional, Xiao, J., additional, Patel, P., additional, Schade, J., additional, Wang, J., additional, Deneen, B., additional, Song, H.-R., additional, Leiss, L., additional, Gjerde, C., additional, Saed, H., additional, Rahman, A., additional, Lellahi, M., additional, Enger, P. O., additional, Leung, R., additional, Gil, O., additional, Lei, L., additional, Canoll, P., additional, Sun, S., additional, Lee, D., additional, Ho, A. S. W., additional, Pu, J. K. S., additional, Zhang, X.-q., additional, Lee, N. P., additional, Dat, P. J. R., additional, Leung, G. K. K., additional, Loetsch, D., additional, Steiner, E., additional, Holzmann, K., additional, Pirker, C., additional, Hlavaty, J., additional, Petznek, H., additional, Hegedus, B., additional, Garay, T., additional, Mohr, T., additional, Sommergruber, W., additional, Lukiw, W. J., additional, Jones, B. M., additional, Zhao, Y., additional, Bhattacharjee, S., additional, Culicchia, F., additional, Magnus, N., additional, Garnier, D., additional, Meehan, B., additional, McGraw, S., additional, Hashemi, M., additional, Lee, T. H., additional, Milsom, C., additional, Gerges, N., additional, Trasler, J., additional, Pawlinski, R., additional, Mackman, N., additional, Rak, J., additional, Maherally, Z., additional, Thorne, A., additional, An, Q., additional, Barbu, E., additional, Fillmore, H., additional, Pilkington, G., additional, Tan, S. L., additional, Tan, S., additional, Choi, S., additional, Potts, C., additional, Ford, D. A., additional, Nahle, Z., additional, Kenney, A. M., additional, Matlaf, L., additional, Khan, S., additional, Zider, A., additional, Singer, E., additional, Cobbs, C., additional, Soroceanu, L., additional, McFarland, B. C., additional, Hong, S. W., additional, Rajbhandari, R., additional, Twitty, G. B., additional, Gray, G. K., additional, Yu, H., additional, Benveniste, E. N., additional, Nozell, S. E., additional, Minata, M., additional, Kim, S., additional, Mao, P., additional, Kaushal, J., additional, Nakano, I., additional, Mizowaki, T., additional, Sasayama, T., additional, Tanaka, K., additional, Mizukawa, K., additional, Nishihara, M., additional, Nakamizo, S., additional, Tanaka, H., additional, Kohta, M., additional, Hosoda, K., additional, Kohmura, E., additional, Moeckel, S., additional, Meyer, K., additional, Leukel, P., additional, Bogdahn, U., additional, Riehmenschneider, M. J., additional, Bosserhoff, A. K., additional, Spang, R., additional, Hau, P., additional, Mukasa, A., additional, Watanabe, A., additional, Ogiwara, H., additional, Aburatani, H., additional, Mukherjee, J., additional, Obha, S., additional, See, W., additional, Pieper, R., additional, Otsuka, R., additional, Kung, D., additional, Sinha, T., additional, Meares, G., additional, Nozell, S., additional, Ott, M., additional, Litzenburger, U., additional, Rauschenbach, K., additional, Bunse, L., additional, Pusch, S., additional, Ochs, K., additional, Sahm, F., additional, Opitz, C., additional, von Deimling, A., additional, Wick, W., additional, Platten, M., additional, Peruzzi, P., additional, Read, R., additional, Fenton, T., additional, Wykosky, J., additional, Vandenberg, S., additional, Babic, I., additional, Iwanami, A., additional, Yang, H., additional, Mischel, P., additional, Thomas, J., additional, Ronellenfitsch, M. W., additional, Thiepold, A. L., additional, Harter, P. N., additional, Mittelbronn, M., additional, Steinbach, J. P., additional, Rybakova, Y., additional, Kalen, A., additional, Sarsour, E., additional, Goswami, P., additional, Silber, J., additional, Harinath, G., additional, Aldaz, B., additional, Fabius, A. W. M., additional, Turcan, S., additional, Chan, T. A., additional, Huse, J. T., additional, Sonabend, A. M., additional, Bansal, M., additional, Guarnieri, P., additional, Soderquist, C., additional, Yun, J., additional, Kennedy, B., additional, Sisti, J., additional, Bruce, S., additional, Bruce, R., additional, Shakya, R., additional, Ludwig, T., additional, Rosenfeld, S., additional, Sims, P. A., additional, Bruce, J. N., additional, Califano, A., additional, Stockhausen, M.-T., additional, Kristoffersen, K., additional, Olsen, L. S., additional, Poulsen, H. S., additional, Stringer, B., additional, Day, B., additional, Barry, G., additional, Piper, M., additional, Jamieson, P., additional, Ensbey, K., additional, Bruce, Z., additional, Richards, L., additional, Boyd, A., additional, Sufit, A., additional, Burleson, T., additional, Le, J. P., additional, Keating, A. K., additional, Sundstrom, T., additional, Varughese, J. K., additional, Harter, P., additional, Prestegarden, L., additional, Petersen, K., additional, Azuaje, F., additional, Tepper, C., additional, Ingham, E., additional, Even, L., additional, Johnson, S., additional, Skaftnesmo, K. O., additional, Lund-Johansen, M., additional, Bjerkvig, R., additional, Ferrara, K., additional, Thorsen, F., additional, Takeshima, H., additional, Yamashita, S., additional, Yokogami, K., additional, Mizuguchi, S., additional, Nakamura, H., additional, Kuratsu, J., additional, Fukushima, T., additional, Morishita, K., additional, Tang, Y., additional, Vaka, D., additional, Chen, S., additional, Ponnuswami, A., additional, Cho, Y.-J., additional, Monje, M., additional, Nakamura, T., additional, Cahill, D., additional, Tiemann, K., additional, Hedman, H., additional, Niclou, S. P., additional, Timmer, M., additional, Tjiong, R., additional, Rohn, G., additional, Goldbrunner, R., additional, Stavrinou, P., additional, Perrech, M., additional, Tokita, M., additional, Mikheev, S., additional, Sellers, D., additional, Mikheev, A., additional, Kosai, Y., additional, Rostomily, R., additional, Tritschler, I., additional, Seystahl, K., additional, Schroeder, J. J., additional, Weller, M., additional, Wade, A., additional, Robinson, A. E., additional, Phillips, J. J., additional, Gong, Y., additional, Ma, Y., additional, Cheng, Z., additional, Thompson, R., additional, Fan, Q.-W., additional, Cheng, C., additional, Gustafson, W., additional, Charron, E., additional, Zipper, P., additional, Wong, R., additional, Chen, J., additional, Lau, J., additional, Knobbe-Thosen, C., additional, Jura, N., additional, Reifenberger, G., additional, Shokat, K., additional, Weiss, W., additional, Wu, S., additional, Hu, J., additional, Taylor, T., additional, Villa, G. R., additional, Mischel, P. S., additional, Gonias, S. L., additional, Yamashita, D., additional, Kondo, T., additional, Takahashi, H., additional, Inoue, A., additional, Kohno, S., additional, Harada, H., additional, Ohue, S., additional, Ohnishi, T., additional, Li, P., additional, Ng, J., additional, Yuelling, L., additional, Du, F., additional, Curran, T., additional, Yang, Z.-j., additional, Zhu, D., additional, Castellino, R. C., additional, Van Meir, E. G., additional, Begum, G., additional, Wang, Q., additional, Yang, S.-S., additional, Lin, S.-H., additional, and Kahle, K., additional

Published
2013
Full Text
View/download PDF

158. Controlling radiative loss in quantum well solar cells

Author

Ekins-Daukes, N J, primary, Lee, K-H, additional, Hirst, L, additional, Chan, A, additional, Führer, M, additional, Adams, J, additional, Browne, B, additional, Barnham, K W J, additional, Stavrinou, P, additional, Connolly, J., additional, Roberts, J S, additional, Stevens, B, additional, Airey, R, additional, and Kennedy, K, additional

Published
2013
Full Text
View/download PDF

159. Drift-diffusion modeling of InP-based triple junction solar cells

Author

Lumb, M. P., primary, González, M., additional, Bailey, C. G., additional, Vurgaftman, I., additional, Meyer, J. R., additional, Abell, J., additional, Yakes, M., additional, Hoheisel, R., additional, Tischler, J. G., additional, Stavrinou, P. N., additional, Fuhrer, M., additional, Ekins-Daukes, N. J., additional, and Walters, R. J., additional

Published
2013
Full Text
View/download PDF

163. Physiological and Metabolic Responses During a Simulated Judo Competition Among Cadet Athletes

Author

Stavrinou, Pinelopi S., Argyrou, Marios, and Hadjicharalambous, Marios

Abstract

This study examined the effects of a simulated judo competition among cadet judo athletes in physiological and metabolic responses. Nine cadet judo athletes participated in the study. The simulated competition consisted of four 4-minute judo matches, separated by fifteen minutes of recovery. During each match, the athletes’ attacks were recorded, and during the recovery time, concentrations of lactate (La), triglycerides (TG), and glucose (GLU) were measured. The heart rate (HR) and the rating of perceived exertion (RPE) were also obtained. The results of this study indicate the high impact multiple judo matches have in cardiovascular stress and perceived exertion and highlight the main metabolic involvement of anaerobic pathway. We conclude that the increase in blood lactate concentration is not a limiting factor in judo performance in multiple one-day judo matches. In addition, in the cadets’ category, the 14-minutes interval between the matches is long enough to positively influence blood lactate clearance.

Published
2016
Full Text
View/download PDF

173. New light from hybrid inorganic–organic emitters

Author

Belton, C R, primary, Itskos, G, additional, Heliotis, G, additional, Stavrinou, P N, additional, Lagoudakis, P G, additional, Lupton, J, additional, Pereira, S, additional, Gu, E, additional, Griffin, C, additional, Guilhabert, B, additional, Watson, I M, additional, Mackintosh, A R, additional, Pethrick, R A, additional, Feldmann, J, additional, Murray, R, additional, Dawson, M D, additional, and Bradley, D D C, additional

Published
2008
Full Text
View/download PDF

182. Integrated transceivers for optical wireless communications

Author

O'Brien, D.C., primary, Faulkner, G.E., additional, Zyambo, E.B., additional, Jim, K., additional, Edwards, D.J., additional, Stavrinou, P., additional, Parry, G., additional, Bellon, J., additional, Sibley, M.J., additional, Lalithambika, V.A., additional, Joyner, V.M., additional, Samsudin, R.J., additional, Holburn, D.M., additional, and Mears, R.J., additional

Published
2005
Full Text
View/download PDF

187. Radiation-induced meningiomas (RIM) in adults: A single-centre retrospective experience

Author

Banos, Stamatios, Solou, Mary, Ydreos, Ioannis, Papadopoulos, Evangelos K., Savvanis, Georgios, Politis, Anastasios A., Stavrinou, Lampis C., Gavra, Maria M., and Boviatsis, Efstathios J.

Abstract

Radiotherapy of central nervous system (CNS) is treatment against many paediatric cancers, even if it is a well-recognized risk factor for meningioma formation. An increased risk of developing secondary brain tumors like radiation-induced meningiomas (RIM) is related to irradiated patients.

Published
2023
Full Text
View/download PDF

190. Multiple-quantum-well asymmetric Fabry-Perot modulators for microwave photonic applications

Author

Killey, R.I., Liu, C.P., Whitehead, M., Stavrinou, P., Song, J.B., Chadha, J.S., Wake, D., Button, C.C., Parry, G., and Seeds, A.J.

Subjects
Microwave communications -- Research, Fiber optic networks -- Design and construction, Modulators (Electronics) -- Design and construction, Optoelectronic devices -- Design and construction, Business, Computers, Electronics, Electronics and electrical industries
Abstract

We describe the development of InGaAsP multi-quantum-well asymmetric Fabry-Perot modulators (AFPM) for RF-over-fiber applications. Advantages of the AFPM include low drive voltage and loss, high linearity and simple fiber alignment. Experimental results of initial devices, exhibiting 5.5-dB modulation depth and >3-GHz operation, are described. The effect of the optical power on the device performance was assessed, and the modulation bandwidth was found to be unaffected by incident optical powers up to 0 dBm. The linearity of the modulation characteristic was measured by carrying out two-tone intermodulation distortion tests, and a third-order intercept point of 30 dBm was observed. Index Terms--Electroabsorption, microwave communication, optical fiber communication, optical modulation, optoelectronic devices.

Published
2001

195. Methodological issues in the spectral analysis of the heart rate variability: Application in patients with epilepsy.

Author

Stavrinou, Maria L., Sakellaropoulos, George C., Trachani, Eftichia, Sirrou, Vassiliki, Polychronopoulos, Panayiotis, Nikiforidis, George, and Chroni, Elisabeth

Subjects
HEART rate monitoring, SPECTRAL analysis (Phonetics), PEOPLE with epilepsy, DYSAUTONOMIA, TIME-domain analysis
Abstract

Purpose Spectral analysis of heart rate variability (HRV) constitutes a useful tool for the evaluation of autonomic function. However, it is difficult to compare the published data because different mathematical approaches for the calculation of the frequency bands are applied. Our aim was to compare the HRV frequency domain parameters obtained by application of 2 parametric and 2 non-parametric spectral methods in a group of patients with chronic epilepsy. Methods Sixty-eight patients and 69 healthy controls underwent a 5-min recording of RR signal, which was analyzed off-line in time and in frequency domains. Results The time domain parameters -- variation RR ratio, standard deviation of normal-to-normal RR and coefficient of variation -- were significantly lower in patients than in controls. In spectral analysis of the patient group deviation toward opposite directions of Low Frequency band (p = 0.034) and Total Power (p = 0.013) measures was detected depending on the method used. The results of Burg's and Yule-Walker's parametric methods fitted best to those of time domain estimates for both control and patient groups. Conclusions Epilepsy-related abnormalities of HRV were disclosed by time as well as by frequency domain analysis. In the present setting, the parametric methods proved to be superior to the non-parametric ones in matching time domain parameters of patients and healthy subjects and at the same time in detecting abnormalities of the frequency domain measures of patients with epilepsy. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

196. Effects of renin-angiotensin-aldosterone system inhibitors and beta-blockers on markers of arterial stiffness.

Author

Koumaras, Charalambos, Tziomalos, Konstantinos, Stavrinou, Eirini, Katsiki, Niki, Athyros, Vasilios G., Mikhailidis, Dimitri P., and Karagiannis, Asterios

Abstract

Abstract: Antihypertensive agents may, even within the same class, exert variable effects on arterial stiffness variables. Nebivolol could have a better impact than atenolol on arterial stiffness, by increasing the bioavailability of endothelium-derived nitric oxide. Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) increase plasma renin activity (enhancing the production of angiotensin II via non-ACE-related pathways) whereas aliskiren does not, potentially affecting central hemodynamics differently. We compared the effects of two renin-angiotensin-aldosterone system (RAAS) inhibitors (quinapril and aliskiren) and 2 beta-blockers (atenolol and nebivolol) on arterial stiffness variables. Treatment-naïve patients (n = 72; 68.1% males; age, 47.6 ± 10.6 years) with uncomplicated stage I-II essential hypertension were randomly assigned to quinapril, aliskiren, atenolol, or nebivolol for 10 weeks. Central systolic and diastolic blood pressure (BP), central pulse pressure (PP), augmentation index (AIx), and pulse wave velocity (PWV) were measured at baseline, 2, and 10 weeks. The same measurements were performed in 20 normotensive subjects (65.0% males; age, 40.0 ± 8.9 years). Peripheral and central systolic and diastolic BP, peripheral PP, and PWV were significantly and similarly reduced by all agents. However, PWV continued to decline between the second and last visit in patients on quinapril and aliskiren but did not change in those on nebivolol or atenolol. Central PP and AIx decreased in patients on quinapril, aliskiren, and nebivolol but did not change in those taking atenolol. The decrease in central PP and AIx did not differ between patients on quinapril, aliskiren, and nebivolol. Despite similar reductions in peripheral BP, atenolol is less effective than nebivolol and RAAS inhibitors in improving central pulsatile hemodynamics. Aliskiren exerts similar effects on markers of arterial stiffness as quinapril. The clinical relevance of these differences remains to be established. [Copyright &y& Elsevier]

Published
2014
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results