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Fast Recovery (fast + recovery)
Selected AbstractsImproving TCP performance over networks with wireless components using ,probing devices'INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2002A. Lahanas Abstract TCP error control mechanism lacks the ability to detect with precision the nature of potential errors during communication. It is only capable of detecting the results of the errors, namely that segments are dropped. As a result, the protocol lacks the ability to implement an appropriate error recovery strategy cognizant of current network conditions and responsive to the distinctive error characteristics of the communication channel. TCP sender always calls for the sending window to shrink. We show that probing mechanisms could enhance the error detection capabilities of the protocol. TCP could then flexibly adjust its window in a manner that permits the available bandwidth to be exploited without violating the requirements of stability, efficiency and fairness that need to be guaranteed during congestion. Our experiments have three distinct goals: First, to demonstrate the potential contribution of probing mechanisms. A simple probing mechanism and an immediate recovery strategy are grafted into TCP-Tahoe and TCP-Reno. We show that, this way, standard TCP can improve its performance without requiring any further change. Second, to study the performance of adaptive strategies. An adaptive TCP with probing is used, that is responsive to the detected error conditions by alternating slow start, fast recovery and immediate recovery. An adaptive error recovery strategy can yield better performance. Third, to study the design limitations of the probing device itself. The aggressive or conservative nature of the probing mechanisms themselves can determine the aggressive or conservative behaviour of the protocol and exploit accordingly the energy/throughput trade-off. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fast spin-echo triple-echo Dixon: Initial clinical experience with a novel pulse sequence for fat-suppressed T2-weighted abdominal MR imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2009Russell N. Low MD Abstract Purpose To evaluate a prototype fast spin echo (FSE) triple-echo-Dixon (fTED) technique for breath-hold, fat-suppressed, T2-weighted abdominal imaging. Materials and Methods Forty patients underwent breath-hold T2-weighted abdominal imaging with fTED and conventional fast recovery (FR) FSE with chemical shift-selective saturation (CHESS). FRFSE and fTED images were compared for overall image quality, homogeneity of fat suppression, image sharpness, anatomic detail, and phase artifact. Depiction of disease was recorded separately for FRFSE and fTED images. Results FTED successfully reconstructed water-only and fat-only images from source images in all 40 cases. Water and fat separation was perfect in 36 (0.90) patients. Homogeneity of fat suppression was superior on the fTED images in 38 (0.95) of 40 cases. FTED images showed better anatomic detail in 27 (0.68), and less susceptibility artifact in 20 (0.50). FRFSE images showed less vascular pulsation artifact in 30 (0.75) cases, and less phase artifact in 21 (0.53) cases. There was no difference in depiction of disease for FRFSE and fTED images. Conclusion FTED is a robust sequence providing breath-hold T2-weighted images with superior fat suppression, excellent image quality, and at least equal depiction of disease compared to conventional breath-hold T2-weighted FRFSE imaging. J. Magn. Reson. Imaging 2009;30:569,577. © 2009 Wiley-Liss, Inc. [source] Midazolam as a sole sedative for computed tomography imaging in pediatric patientsPEDIATRIC ANESTHESIA, Issue 9 2009RANJU SINGH MD Summary Objective:, To evaluate the efficacy and adverse effects of i.v. midazolam as a sole agent for sedation in children for computed tomography (CT) imaging. Materials and Methods:, Prospective clinical trial in which 516 children under ASA classification II,IV (273 boys and 243 girls) in the age group of 6 months to 6 years for elective CT scan were enrolled over a 17-month period. Patients were administered i.v. midazolam 0.2 mg·kg,1 and further boluses of 0.1 mg·kg,1 (total 0.5 mg·kg,1) if required. Measurements included induction time, efficacy, side effects, complications, and degree of sedation. Sedation was graded on the basis of Ramsay sedation score (RSS) as over sedated (RSS 5,6), adequately sedated (AS, RSS 3,4), under sedated (RSS 1,2), or failed if the procedure could not be completed or another agent had to be administered. Results:, Of the 516 procedures, 483 brains, 16 chests, and 17 abdomens were scanned with a mean duration of 4.75 ± 1.75 min with a mean dose of 0.212 mg·kg,1 of i.v. midazolam. Four hundred and sixty-five (90.12%) patients were AS in 5.9 ± 0.7 min while 40 (7.75%) patients required additional boluses. Of these 40 patients, 24 (4.65%) required a single bolus, 12 (2.32%) required two boluses, whereas the remaining four (0.78%) required three boluses. In 11 (2.13%; P < 0.0001) patients, the scan could not be completed satisfactorily. Side effects were seen in 46 (9.11%) patients in the form of desaturation, hiccups (seven patients, 1.38%), and agitation (four patients, 0.79%). Desaturation (SpO2 90,95%) was seen in 35 (6.93%) patients, which was corrected by topical application of oxygen. None of the patients exhibited any complications such as pulmonary aspiration or need to maintain airway. The patients were kept under observation for 1 h after the procedure. Conclusion:, The level of sedation achieved in children with midazolam 0.2 mg·kg,1 is adequate for imaging with minimal side effects, no airway complications, and fast recovery. It can be recommended as the sole agent for sedation in pediatric patients for CT imaging. [source] Changes in Structure, Composition, and Nutrients During 15 Yr of Hurricane-Induced Succession in a Subtropical Wet Forest in Puerto RicoBIOTROPICA, Issue 4 2010Tamara Heartsill Scalley ABSTRACT The trajectory of hurricane-induced succession was evaluated in a network of forest plots measured immediately before and 3 mo, 5, 10, and 15 yr after the direct impact of a Category 4 hurricane. Comparisons of forest structure, composition, and aboveground nutrients pools were made through time, and between species, life-history groups and geomorphic settings. The hurricane reduced aboveground biomass by 50 percent, causing an immediate decrease in stem density and diversity indices among all geomorphic settings. After 15 yr, basal area and aboveground biomass returned to pre-hurricane levels, while species richness, diversity indices, and stem densities exceeded pre-hurricane levels. Differences in species composition among geomorphic settings had not returned after 15 yr but differences in stem densities and structure were beginning to emerge. Significant differences were observed in the nutrient concentration of the three species that comprised the most aboveground biomass, and between species categorized as secondary high-light species and primary, low-light species. Species whose abundance was negatively correlated with the mature forest dominant also had distinct nutrient concentrations. When total aboveground nutrient pools were compared over time, differences in leaf nutrients among species were hidden by similarities in wood nutrient concentrations and the biomass dominance of a few species. The observed successional trajectory indicates that changes in species composition contributed to fast recovery of aboveground biomass and nutrient pools, while the influence of geomorphic setting on species composition occurs at time scales >15 yr of succession. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source] | ||||||||||