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Short Cycles (short + cycle)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Ischemic preconditioning attenuates the oxidant-dependent mechanisms of reperfusion cell damage and death in rat liver

LIVER TRANSPLANTATION, Issue 11 2002
Barbara Cavalieri
In an in vivo rat model of liver ischemia followed by reperfusion a consistent appearance of necrosis and activation of biochemical pathways of apoptosis was reproduced and monitored after 30 minutes reperfusion. Preconditioning by application of a short cycle of ischemia-reperfusion (10 minutes + 10 minutes) positively conditioned recovery of the organ at reperfusion, attenuating both necrotic and apoptotic events. Preconditioning at least halved cell oxidative damage occurring early at reperfusion, and as a major consequence, the increase of cytolysis and apoptosis occurring at reperfusion was about 50% less. The attenuation of both pathways of cell death by preconditioning appeared at least partly related to its modulate action on H2O2 and 4-hydroxy-2,3-trans-nonenal production. The overall data point to a marked diminished oxidant generation and oxidative reactions as one major possible mechanism through which ischemic preconditioning exerts protection against necrotic and apoptotic insult to the postischemic liver. [source]

Semi-random LDPC codes for CDMA communication over non-linear band-limited satellite channels

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2006
Mohamed Adnan Landolsi
Abstract This paper considers the application of low-density parity check (LDPC) error correcting codes to code division multiple access (CDMA) systems over satellite links. The adapted LDPC codes are selected from a special class of semi-random (SR) constructions characterized by low encoder complexity, and their performance is optimized by removing short cycles from the code bipartite graphs. Relative performance comparisons with turbo product codes (TPC) for rate 1/2 and short-to-moderate block sizes show some advantage for SR-LDPC, both in terms of bit error rate and complexity requirements. CDMA systems using these SR-LDPC codes and operating over non-linear, band-limited satellite links are analysed and their performance is investigated for a number of signal models and codes parameters. The numerical results show that SR-LDPC codes can offer good capacity improvements in terms of supportable number of users at a given bit error performance. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Short cycle distribution in random regular graphs recursively generated by pegging

RANDOM STRUCTURES AND ALGORITHMS, Issue 1 2009
Pu Gao
Abstract We introduce a new method of generating random d -regular graphs by repeatedly applying an operation called pegging. The pegging operation is abstracted from a type of basic operation applied in a type of peer-to-peer network called the SWAN network. We prove that for the resulting graphs, the limiting joint distribution of the numbers of short cycles is independent Poisson. We also use coupling to bound the rate at which the distribution approaches its limit. The coupling involves two different, though quite similar, Markov chains that are not time-homogeneous. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2009 [source]

Effect of GnRH Dose on Occurrence of Short Oestrous Cycles and LH Response in Cyclic Dairy Heifers

REPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2009
MH Rantala
Contents Prostaglandin F2, (PGF2,) and GnRH treatments given 24 h apart have been shown to result in short oestrous cycles (8,12 days) in some cows and heifers. The differences in responses may depend on the dose of GnRH. Therefore, the effect of the dose of GnRH on occurrence of short cycles and LH response was studied here. Oestrus was induced with dexcloprostenol (0.15 mg) in two groups of Ayrshire heifers. A second luteolysis was induced similarly on day 7 after ovulation; 24 h after PGF2, treatment, the heifers were administered either a high (0.5 mg, n = 15, group T500) or low (0.1 mg, n = 10, group T100) dose of gonadorelin. Blood samples for progesterone analyses were collected daily from the second PGF2, administration to the second ovulation after the PGF2, injection. Beginning 24 h after the GnRH treatment, ovaries were examined by transrectal ultrasonography every 6 h until ovulation, and daily between day 4 and the next ovulation. Five heifers from both groups were sampled for LH analyses via a jugular catheter every 30 min from 1 h before to 6 h after the GnRH administration. Short oestrous cycles were detected in 7 of 10 cases in group T100 and in 12 of 15 cases in group T500. No significant differences in LH responses were detected between the groups. In group T500, the rise in LH concentration tended to be somewhat slower than in group T100. The dose of GnRH (0.1 vs 0.5 mg) did not affect the occurrence of short oestrous cycles and LH response. [source]